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Graphene-Based Transparent Electrodes for Highly Efficient Flexible OLEDs
A Korean research team developed an ideal electrode structure composed of graphene and layers of titanium dioxide and conducting polymers, resulting in highly flexible and efficient OLEDs.
The arrival of a thin and lightweight computer that even rolls up like a piece of paper will not be in the far distant future. Flexible organic light-emitting diodes (OLEDs), built upon a plastic substrate, have received greater attention lately for their use in next-generation displays that can be bent or rolled while still operating.
A Korean research team led by Professor Seunghyup Yoo from the School of Electrical Engineering, KAIST and Professor Tae-Woo Lee from the Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH) has developed highly flexible OLEDs with excellent efficiency by using graphene as a transparent electrode (TE) which is placed in between titanium dioxide (TiO2) and conducting polymer layers. The research results were published online on June 2, 2016 in Nature Communications.
OLEDs are stacked in several ultra-thin layers on glass, foil, or plastic substrates, in which multi-layers of organic compounds are sandwiched between two electrodes (cathode and anode). When voltage is applied across the electrodes, electrons from the cathode and holes (positive charges) from the anode draw toward each other and meet in the emissive layer. OLEDs emit light as an electron recombines with a positive hole, releasing energy in the form of a photon. One of the electrodes in OLEDs is usually transparent, and depending on which electrode is transparent, OLEDs can either emit from the top or bottom.
In conventional bottom-emission OLEDs, an anode is transparent in order for the emitted photons to exit the device through its substrate. Indium-tin-oxide (ITO) is commonly used as a transparent anode because of its high transparency, low sheet resistance, and well-established manufacturing process. However, ITO can potentially be expensive, and moreover, is brittle, being susceptible to bending-induced formation of cracks.
Graphene, a two-dimensional thin layer of carbon atoms tightly bonded together in a hexagonal honeycomb lattice, has recently emerged as an alternative to ITO. With outstanding electrical, physical, and chemical properties, its atomic thinness leading to a high degree of flexibility and transparency makes it an ideal candidate for TEs. Nonetheless, the efficiency of graphene-based OLEDs reported to date has been, at best, about the same level of ITO-based OLEDs.
As a solution, the Korean research team, which further includes Professors Sung-Yool Choi (Electrical Engineering) and Taek-Soo Kim (Mechanical Engineering) of KAIST and their students, proposed a new device architecture that can maximize the efficiency of graphene-based OLEDs. They fabricated a transparent anode in a composite structure in which a TiO2 layer with a high refractive index (high-n) and a hole-injection layer (HIL) of conducting polymers with a low refractive index (low-n) sandwich graphene electrodes. This is an optical design that induces a synergistic collaboration between the high-n and low-n layers to increase the effective reflectance of TEs. As a result, the enhancement of the optical cavity resonance is maximized. The optical cavity resonance is related to the improvement of efficiency and color gamut in OLEDs. At the same time, the loss from surface plasmon polariton (SPP), a major cause for weak photon emissions in OLEDs, is also reduced due to the presence of the low-n conducting polymers.
Under this approach, graphene-based OLEDs exhibit 40.8% of ultrahigh external quantum efficiency (EQE) and 160.3 lm/W of power efficiency, which is unprecedented in those using graphene as a TE. Furthermore, these devices remain intact and operate well even after 1,000 bending cycles at a radius of curvature as small as 2.3 mm. This is a remarkable result for OLEDs containing oxide layers such as TiO2 because oxides are typically brittle and prone to bending-induced fractures even at a relatively low strain. The research team discovered that TiO2 has a crack-deflection toughening mechanism that tends to prevent bending-induced cracks from being formed easily.
Professor Yoo said, “What’s unique and advanced about this technology, compared with previous graphene-based OLEDs, is the synergistic collaboration of high- and low-index layers that enables optical management of both resonance effect and SPP loss, leading to significant enhancement in efficiency, all with little compromise in flexibility.” He added, “Our work was the achievement of collaborative research, transcending the boundaries of different fields, through which we have often found meaningful breakthroughs.”
Professor Lee said, “We expect that our technology will pave the way to develop an OLED light source for highly flexible and wearable displays, or flexible sensors that can be attached to the human body for health monitoring, for instance.”
The research paper is entitled “Synergistic Electrode Architecture for Efficient Graphene-based Flexible Organic Light-emitting Diodes” (DOI. 10.1038/NCOMMS11791). The lead authors are Jae-Ho Lee, a Ph.D. candidate at KAIST; Tae-Hee Han, a Ph.D. researcher at POSTECH; and Min-Ho Park, a Ph.D. candidate at POSTECH.
This study was supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF) through the Center for Advanced Flexible Display (CAFDC) funded by the Ministry of Science, ICT and Future Planning (MSIP); by the Center for Advanced Soft-Electronics funded by the MSIP as a Global Frontier Project; by the Graphene Research Center Program of KAIST; and by grants from the IT R&D Program of the Ministry of Trade, Industry and Energy of Korea (MOTIE).
Figure 1: Application of Graphene-based OLEDs
This picture shows an OLED with the composite structure of TiO2/graphene/conducting polymer electrode in operation. The OLED exhibits 40.8% of ultrahigh external quantum efficiency (EQE) and 160.3 lm/W of power efficiency. The device prepared on a plastic substrate shown in the right remains intact and operates well even after 1,000 bending cycles at a radius of curvature as small as 2.3 mm.
Figure 2: Schematic Device Structure of Graphene-based OLEDs
This picture shows the new architecture to develop highly flexible OLEDs with excellent efficiency by using graphene as a transparent electrode (TE).
2016.06.07 View 14051 -
KAIST Researchers Receive the 2016 IEEE William R. Bennett Prize
A research team led by Professors Yung Yi and Song Chong from the Electrical Engineering Department at KAIST has been awarded the 2016 William R. Bennett Prize of the Institute of Electrical and Electronics Engineers (IEEE), which is the most prestigious award in the field of communications network. The IEEE bestows the honor annually and selects winning papers from among those published in the past three years for its quality, originality, scientific citation index, and peer reviews.
The IEEE award ceremony will take place on May 24, 2016 at the IEEE International Conference on Communications in Kuala Lumpur, Malaysia.
The team members include Dr. Kyoung-Han Lee, a KAIST graduate, who is currently a professor at Ulsan National Institute of Science and Technology (UNIST) in Korea, Dr. Joo-Hyun Lee, a postdoctoral researcher at Ohio State University in the United States, and In-Jong Rhee, a vice president of the Mobile Division at Samsung Electronics. The same KAIST team previously received the award back in 2013, making them the second recipient ever to win the IEEE William R. Bennett Prize twice.
Past winners include Professors Robert Gallager of the Massachusetts Institute of Technology (MIT), Sachin Katti of Stanford University, and Ion Stoica of the University of California at Berkeley.
The research team received the Bennett award for their work on “Mobile Data Offloading: How Much Can WiFi Deliver?” Their research paper has been cited more than 500 times since its publication in 2013. They proposed an original method to effectively offload the cellular network and maximize the Wi-Fi network usage by analyzing the pattern of individual human mobility in daily life.
2016.05.02 View 13665 -
KAIST and McKinsey Korea Agreed to Cultivate Management Leaders
KAIST and McKinsey Korea signed a memorandum of understanding (MOU) for the “Joint Research on Innovative Instructional Method to Cultivate Future Management Leaders” on April 8, 2016, at the SUPEX Management Hall of KAIST Management School in Seoul.
Under the MOU, both organizations will cooperate in the following research areas: management strategies to overcome the low growth of Korean economy, instructional methods to foster leaders in the field of business and management, and innovative management systems for business.
President Kang said, “We are pleased to work with McKinsey, a worldwide management consulting firm, to foster leaders in science and business. As we see more demanding challenges of managing and leading science-based businesses today, this alliance is indeed timely and will be very helpful.”
2016.04.15 View 5794 -
KAIST, NTU, and Technion Collaborate for Research in Emerging Fields
KAIST, Nanyang Technological University (NTU) of Singapore, and Technion of Israel signed an agreement on April 11, 2016 in Seoul to create a five-year joint research program for some of the most innovative and entrepreneurial areas: robotics, medical technologies, satellites, materials science and engineering, and entrepreneurship. Under the agreement, the universities will also offer dual degree opportunities, exchange visits, and internships.
In the picture from the left, Bertil Andersson of NTU, Sung-Mo Kang of KAIST, and Peretz Lavie of Technion hold the signed memorandum of understanding.
2016.04.14 View 11637 -
Efficient Methane C-H Bond Activated by KAIST and UPenn Teams
Professor Mu-Hyun Baik of the Chemistry Department at KAIST and his team collaborated with an international team to discover a novel chemical reaction, carbon-hydrogen borylation using methane, and their research results were published in the March 25th issue of Science.
For details, please refer to the following press release from the Institute for Basic Sciences (IBS) in Korea and the University of Pennsylvania in the United States.
Efficient Methane C-H Bond Activation Achieved for the First Time
The Institute for Basic Science, March 24, 2016
Penn Chemists Lay Groundwork for Countless New, Cleaner Uses of Methane
University of Pennsylvania, March 24, 2016
2016.03.25 View 9728 -
Public Lectures on the Korean Language and Alphabet
The School of Humanities and Social Sciences at KAIST will offer public lectures on the Korean language and alphabet, Hangul, from March 22, 2016 to April 26, 2016.
The lectures, which are entitled “The Riddle of Hangul,” will take place on campus in Daejeon.
A total of six lectures will be held on such topics as the origin of Korean, the grammar of ancient Korean in the Chosun Dynasty (1392-1897), and subsequent developments in contemporary Korean.
Professor Jung-Hoon Kim, who is responsible for organizing the public lecture program, said, “The audience will have an interesting opportunity to understand the history of Korean and its mechanism, while reviewing the unique spelling system of Hangul. I hope many people will show up for these wonderful classes.”
For further information and registration, please visit: http://hss.kaist.ac.kr. All lectures, available only in Korean, are free and open to the public.
2016.03.15 View 8999 -
Non-Natural Biomedical Polymers Produced from Microorganisms
KAIST researchers have developed metabolically engineered Escherichia coli strains to synthesize non-natural, biomedically important polymers including poly(lactate-co-glycolate) (PLGA), previously considered impossible to obtain from biobased materials.
Renewable non-food biomass could potentially replace petrochemical raw materials to produce energy sources, useful chemicals, or a vast array of petroleum-based end products such as plastics, lubricants, paints, fertilizers, and vitamin capsules. In recent years, biorefineries which transform non-edible biomass into fuel, heat, power, chemicals, and materials have received a great deal of attention as a sustainable alternative to decreasing the reliance on fossil fuels.
A research team headed by Distinguished Professor Sang Yup Lee of the Chemical and Biomolecular Engineering Department at KAIST has established a biorefinery system to create non-natural polymers from natural sources, allowing various plastics to be made in an environmentally-friendly and sustainable manner. The research results were published online in Nature Biotechnology on March 7, 2016. The print version will be issued in April 2016.
The research team adopted a systems metabolic engineering approach to develop a microorganism that can produce diverse non-natural, biomedically important polymers and succeeded in synthesizing poly(lactate-co-glycolate) (PLGA), a copolymer of two different polymer monomers, lactic and glycolic acid. PLGA is biodegradable, biocompatible, and non-toxic, and has been widely used in biomedical and therapeutic applications such as surgical sutures, prosthetic devices, drug delivery, and tissue engineering.
Inspired by the biosynthesis process for polyhydroxyalkanoates (PHAs), biologically-derived polyesters produced in nature by the bacterial fermentation of sugar or lipids, the research team designed a metabolic pathway for the biosynthesis of PLGA through microbial fermentation directly from carbohydrates in Escherichia coli (E. coli) strains.
The team had previously reported a recombinant E. coli producing PLGA by using the glyoxylate shunt pathway for the generation of glycolate from glucose, which was disclosed in their patents KR10-1575585-0000 (filing date of March 11, 2011), US08883463 and JP5820363. However, they discovered that the polymer content and glycolate fraction of PLGA could not be significantly enhanced via further engineering techniques. Thus, in this research, the team introduced a heterologous pathway to produce glycolate from xylose and succeeded in developing the recombinant E. coli producing PLGA and various novel copolymers much more efficiently.
In order to produce PLGA by microbial fermentation directly from carbohydrates, the team incorporated external and engineered enzymes as catalysts to co-polymerize PLGA while establishing a few additional metabolic pathways for the biosynthesis to produce a range of different non-natural polymers, some for the first time. This bio-based synthetic process for PLGA and other polymers could substitute for the existing complicated chemical production that involves the preparation and purification of precursors, chemical polymerization processes, and the elimination of metal catalysts.
Professor Lee and his team performed in silico genome-scale metabolic simulations of the E. coli cell to predict and analyze changes in the metabolic fluxes of cells which were caused by the introduction of external metabolic pathways. Based on these results, genes are manipulated to optimize metabolic fluxes by eliminating the genes responsible for byproducts formation and enhancing the expression levels of certain genes, thereby achieving the effective production of target polymers as well as stimulating cell growth.
The team utilized the structural basis of broad substrate specificity of the key synthesizing enzyme, PHA synthase, to incorporate various co-monomers with main and side chains of different lengths. These monomers were produced inside the cell by metabolic engineering, and then copolymerized to improve the material properties of PLGA. As a result, a variety of PLGA copolymers with different monomer compositions such as the US Food and Drug Administration (FDA)-approved monomers, 3-hydroxyburate, 4-hydroxyburate, and 6-hydroxyhexanoate, were produced. Newly applied bioplastics such as 5-hydroxyvalerate and 2-hydroxyisovalerate were also made.
The team employed a systems metabolic engineering application which, according to the researchers, is the first successful example of biological production of PGLA and several novel copolymers from renewable biomass by one-step direct fermentation of metabolically engineered E.coli.
Professor Lee said, “We presented important findings that non-natural polymers, such as PLGA which is commonly used for drug delivery or biomedical devices, were produced by a metabolically engineered gut bacterium. Our research is meaningful in that it proposes a platform strategy in metabolic engineering, which can be further utilized in the development of numerous non-natural, useful polymers.”
Director Ilsub Baek at the Platform Technology Division of the Ministry of Science, ICT and Future Planning of Korea, who oversees the Technology Development Program to Solve Climate Change, said, “Professor Lee has led one of our research projects, the Systems Metabolic Engineering for Biorefineries, which began as part of the Ministry’s Technology Development Program to Solve Climate Change. He and his team have continuously achieved promising results and been attracting greater interest from the global scientific community. As climate change technology grows more important, this research on the biological production of non-natural, high value polymers will have a great impact on science and industry.”
The title of the research paper is “One-step Fermentative Production of Poly(lactate-co-glycolate) from Carbohydrates in Escherichia coli (DOI: 10.1038/nbt.3485).” The lead authors are So Young Choi, a Ph.D. candidate in the Department of Chemical and Biomolecular Engineering at KAIST, and Si Jae Park, Assistant Professor of the Environmental Engineering and Energy Department at Myongji University. Won Jun Kim and Jung Eun Yang, both doctoral students in the Department of Chemical and Biomolecular Engineering at KAIST, also participated in the research.
This research was supported by the Technology Development Program to Solve Climate Change’s research project titled “Systems Metabolic Engineering for Biorefineries” from the Ministry of Science, ICT and Future Planning through the National Research Foundation of Korea (NRF-2012M1A2A2026556).
Figure: Production of PLGA and Other Non-Natural Copolymers
This schematic diagram shows the overall conceptualization of how metabolically engineered E. coli produced a variety of PLGAs with different monomer compositions, proposing the chemosynthetic process of non-natural polymers from biomass. The non-natural polymer PLGA and its other copolymers, which were produced by engineered bacteria developed by taking a systems metabolic engineering approach, accumulate in granule forms within a cell.
2016.03.08 View 11982 -
K-Glass 3 Offers Users a Keyboard to Type Text
KAIST researchers upgraded their smart glasses with a low-power multicore processor to employ stereo vision and deep-learning algorithms, making the user interface and experience more intuitive and convenient.
K-Glass, smart glasses reinforced with augmented reality (AR) that were first developed by KAIST in 2014, with the second version released in 2015, is back with an even stronger model. The latest version, which KAIST researchers are calling K-Glass 3, allows users to text a message or type in key words for Internet surfing by offering a virtual keyboard for text and even one for a piano.
Currently, most wearable head-mounted displays (HMDs) suffer from a lack of rich user interfaces, short battery lives, and heavy weight. Some HMDs, such as Google Glass, use a touch panel and voice commands as an interface, but they are considered merely an extension of smartphones and are not optimized for wearable smart glasses. Recently, gaze recognition was proposed for HMDs including K-Glass 2, but gaze cannot be realized as a natural user interface (UI) and experience (UX) due to its limited interactivity and lengthy gaze-calibration time, which can be up to several minutes.
As a solution, Professor Hoi-Jun Yoo and his team from the Electrical Engineering Department recently developed K-Glass 3 with a low-power natural UI and UX processor. This processor is composed of a pre-processing core to implement stereo vision, seven deep-learning cores to accelerate real-time scene recognition within 33 milliseconds, and one rendering engine for the display.
The stereo-vision camera, located on the front of K-Glass 3, works in a manner similar to three dimension (3D) sensing in human vision. The camera’s two lenses, displayed horizontally from one another just like depth perception produced by left and right eyes, take pictures of the same objects or scenes and combine these two different images to extract spatial depth information, which is necessary to reconstruct 3D environments. The camera’s vision algorithm has an energy efficiency of 20 milliwatts on average, allowing it to operate in the Glass more than 24 hours without interruption.
The research team adopted deep-learning-multi core technology dedicated for mobile devices. This technology has greatly improved the Glass’s recognition accuracy with images and speech, while shortening the time needed to process and analyze data. In addition, the Glass’s multi-core processor is advanced enough to become idle when it detects no motion from users. Instead, it executes complex deep-learning algorithms with a minimal power to achieve high performance.
Professor Yoo said, “We have succeeded in fabricating a low-power multi-core processer that consumes only 126 milliwatts of power with a high efficiency rate. It is essential to develop a smaller, lighter, and low-power processor if we want to incorporate the widespread use of smart glasses and wearable devices into everyday life. K-Glass 3’s more intuitive UI and convenient UX permit users to enjoy enhanced AR experiences such as a keyboard or a better, more responsive mouse.”
Along with the research team, UX Factory, a Korean UI and UX developer, participated in the K-Glass 3 project.
These research results entitled “A 126.1mW Real-Time Natural UI/UX Processor with Embedded Deep-Learning Core for Low-Power Smart Glasses” (lead author: Seong-Wook Park, a doctoral student in the Electrical Engineering Department, KAIST) were presented at the 2016 IEEE (Institute of Electrical and Electronics Engineers) International Solid-State Circuits Conference (ISSCC) that took place January 31-February 4, 2016 in San Francisco, California.
YouTube Link: https://youtu.be/If_anx5NerQ
Figure 1: K-Glass 3
K-Glass 3 is equipped with a stereo camera, dual microphones, a WiFi module, and eight batteries to offer higher recognition accuracy and enhanced augmented reality experiences than previous models.
Figure 2: Architecture of the Low-Power Multi-Core Processor
K-Glass 3’s processor is designed to include several cores for pre-processing, deep-learning, and graphic rendering.
Figure 3: Virtual Text and Piano Keyboard
K-Glass 3 can detect hands and recognize their movements to provide users with such augmented reality applications as a virtual text or piano keyboard.
2016.02.26 View 13180 -
KAIST Commencement 2016
KAIST hosted its 2016 commencement ceremony on February 19, 2016 at the Sports Complex on campus.
KAIST celebrated the event with five thousand participants including graduating students, faculty, guests, Vice Minister Nam-Ki Hong of Science, ICT and Future Planning of Korea, Chairman Jang-Moo Lee of KAIST's Board of Trustees, and President Jeong-Sik Ko of the KAIST Alumni Association.
President Patrick Aebischer of the Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland, and the former Speaker of the National Assembly of Korea Chang-Hee Kang received honorary doctorates in science and technology for their contributions to the advancement of science and engineering in education and research.
KAIST granted 570 doctoral degrees, 1,329 master’s degrees, and 867 bachelor degrees on this day.
Yoon-Bum Lee of the Chemistry Department graduated with honors; Woo-Young Jin of the Mathematical Sciences Department received the Chairman’s Award of the KAIST Board and Eun-Hee Yoo of the Biological Sciences Department for the KAIST Presidential Award. Min-Hyun Cho and Yoon-Seok Chang were recipients of the President’s Award of the KAIST Alumni Association and the President’s Award of the University Supporting Association, respectively.
President Steve Kang addressed the ceremony and congratulated the graduates, saying,
“Now, your task is to make significant contributions to your communities: be leaders in your fields and remain active members of society. Given your academic knowledge and vision for the future, I encourage you to dream big.”
2016.02.23 View 42323 -
GSIS Graduates Its First Doctor
The Graduate School of Information Security at KAIST (GSIS) granted its first doctoral degree to Il-Goo Lee at the university’s 2016 commencement on February 19, 2016.
Lee received the degree for his dissertation entitled “Interference-Aware Secure Communications for Wireless LANs.”
He explained the background of his research:
“As we use wireless technology more and more in areas of the Internet of Things (IoT), unmanned vehicles, and drones, information security will become an issue of major concern. I would like to contribute to the advancement of communications technology to help minimize wireless interference between devices while ensuring their optimal performance.”
Based on his research, he developed a communications technique to increase wireless devices’ energy efficiency and the level of their security, and created a prototype to showcase that technique.
He plans to continue his research in the development of the next generation WiFi chip sets to protect the information security of IoT and wireless devices.
Since its establishment in March 2011, KAIST’s GSIS has conferred 50 master’s and one doctoral degrees.
2016.02.18 View 9226 -
Meditox Donates 600 Million KRW Scholarship
On February 17, a Korean biopharmaceutical company Meditox, headed by Chief Executive Officer (CEO) Hyun-Ho Jeong, signed a memorandum of understanding (MOU) with KAIST to establish the “Meditox Fellowship” and donated a total of 600 million Korean won (KRW) to the university to assist in promoting more scientists in the field of biology.
Meditox CEO Hyun-Ho Jeong, KAIST President Steve Kang, Dean of Life Science and Bioengineering College Jung-Hoe Kim, and Dean of the Department of Biological Sciences Byung-Ha Oh participated in the agreement ceremony.
According to the MOU, Meditox will donate 60,000,000 KRW over a ten year period, from which KAIST can draw on to grant scholarships for master’s and doctoral students.
The “Meditox Fellowship” will support promising and enthusiastic students whose finances limit their studies. The first scholarship students for 2016 were: Kwang-Uk Min, In-suk Yeo, Sung-ryung- Lee, Si-on Lee, and Jung-hyun Kim.
Meditox CEO Jeong, who graduated from KAIST’s Department of Biological Sciences, said, "I felt it was important to start the Meditox Fellowship at my alma mater to contribute to the cultivation of outstanding scientists in the field of biological sciences."
He also said that he would plan to launch projects that aim to support not only those who receive the scholarship but also the development of Korea’s biological sciences in general.
President Steve Kang (right) and Chief Executive Officer Hyun-Ho Jeong (left) of Meditox hold the signed memorandum of understanding together.
2016.02.18 View 10256 -
Ph.D. Candidate Seo Wins the Human Tech Paper Award
Hyun-Suk Seo, a doctoral student of KAIST’s Department of Electrical Engineering, received the grand prize of the “22nd Human Tech Paper Award” on February 3, 2016 from Samsung Electronics Co., Ltd.
Seo was the first to receive this prize ever since the Human Tech Paper Award was established 22 years ago. Until last year, the highest prize awarded for KAIST was a gold one.
The “Human Tech Paper Award” was established in 1994 by Samsung Electronics to discover and support outstanding scientists in the field of electrical engineering.
Entitled “Self-Gated Cardiac Cine MRI Using Phase Information,” Seo’s paper presented a technology that would reduce discomforts and inconveniences experienced by patients who take a magnetic resonance imaging (MRI).
This technology uses the speed changes of aorta and the abdominal movements of body to obtain the phase changes of magnetic resonance signals so that MRIs may be taken despite the organs’ movements.
Seo commented on his research, “I wanted to develop a technique that can make MRI a more comfortable experience. I will continue my research on this subject and hope to serve the needs of the society.”
In addition, the “Special Award,” which is given to schools, was awarded to KAIST. KAIST’s Department of Electrical Engineering has also been named the department that has received the second most awards (15 awards) this year.
Oh-Hyun Kwon, Vice President of Samsung Electronics, Steve Kang, President of KAIST, and Nak-In Seo, President of Seoul National University, participated in the event.
Picture: Hyun-Suk Seo (left), the recipient of the grand prize of the 2016 Human Tech Paper Award, and Oh-Hyun Kwon (right), Vice President of Samsung Electronics
2016.02.06 View 9232