Distinct U-shape efficiency-versus-current curves in AlGaN-based deep-ultraviolet light-emitting diodes.

Park, Jun Hyuk,Lin, Guan-Bo,Kim, Dong Yeong,Lee, Jong Won,Cho, Jaehee,Kim, Jungsub,Lee, Jinsub,Kim, Yong-Il,Park, Youngsoo,Schubert, E Fred,Kim, Jong Kyu Optical Society of America 2015 Optics express Vol.23 No.12

<P>The efficiency of an AlGaN deep-ultraviolet light-emitting diode with peak emission wavelength of 285 nm is investigated as a function of current over a wide range of temperatures (110 K to 300 K). We find that the efficiency-versus-current curve exhibits unique and distinct features over the entire temperature range including three points of inflection. At low temperatures, the change in slope in the efficiency-versus-current curve is particularly pronounced producing a minimum in the efficiency after which the efficiency rises again. Furthermore, at high current density, the low-temperature efficiency exceeds the room-temperature efficiency. The feature-rich efficiency-versus-current curve is consistent with an enhancement in p-type conductivity by field-ionization of acceptors that occurs in the high-injection regime and is particularly pronounced at low temperatures. Differential conductivity measurements show a marked rise in the high-injection regime that is well correlated to the minimum point in the efficiency-versus-current curve.</P>

Variation of the external quantum efficiency with temperature and current density in red, blue, and deep ultraviolet light-emitting diodes

Park, Jun Hyuk,Lee, Jong Won,Kim, Dong Yeong,Cho, Jaehee,Schubert, E. Fred,Kim, Jungsub,Lee, Jinsub,Kim, Yong-Il,Park, Youngsoo,Kim, Jong Kyu American Institute of Physics 2016 JOURNAL OF APPLIED PHYSICS - Vol.119 No.2

윈도우 환경에서 프로세스 할로잉 공격과 탐지방법

이정섭(Jungsub Lee),박은석(Eunseok Park),박용수(Yongsu Park) 한국통신학회 2020 한국통신학회 학술대회논문집 Vol.2020 No.8

선거운동에서의 표현의 자유에 대한 유권자 인식 분석

박선경 ( Sunkyoung Park ),신정섭 ( Jungsub Shin ),박상운 ( Sang-un Park ) 인제대학교 민주주의와자치연구소 2022 비교민주주의연구 Vol.18 No.1

선거운동에서의 표현의 자유는 민주 시민의 권리이자 민주주의 발전을 위해 보장해야 하는 중요한 가치이다. 그러나 현행 공직선거법은 법리적 차원에서뿐만 아니라 비교정치적 차원에서도 선거운동에서의 표현의 자유를 심각하게 제한하고 있다는 지적을 받아왔다. 그럼에도 불구하고, 실제로 일반 시민들이 선거 운동에서의 표현의 자유에 대해 어떻게 생각하는지, 과연 어느 정도로 표현의 자유 확대를 찬성 혹은 반대하는지에 대한 실증적인 연구는 전무하다. 이에 본 연구는 다양한 설문조사 문항을 통해 시민들의 선거운동에서의 표현의 자유에 대한 선호를 확인하였다. 설문조사 분석결과, 과반이 훨씬 넘는 유권자들이 선거운동 기간 자신의 정치적 지지를 표현하는 홍보물과 소품 사용을 찬성하고 있었다. 또한, 다중회귀분석과 매개분석을 통해, 자유주의적 태도를 가진 사람 일수록 표현의 자유 확대를 지지할 확률이 높으며, 당파적 입장이 두드러진 게시물에 대해서는 이념과 선거품질에 대한 만족도가 영향을 미침을 확인하였다. Freedom of expression in election campaign is one of essential constitutional rights in democratic countries. However, the current Korean election law has been criticized for restricting freedom of expression not only in the aspect of jurisprudence but also comparative politics. In spite of this criticism, there has been no study that surveys and analyzes public attitudes toward freedom of expression in election campaign in South Korea. This study conducted a public opinion survey to analyze Korean perceptions and attitudes toward the current election law. The results show that an overwhelming majority of Koreans support for the idea that freedom of expression in election campaign should be enlarged and citizens are allowed to use election campaign badges and stickers to express their political support. Furthermore, those who are more liberal are more likely to support freedom of expression in election campaign, and political ideology and perception of electoral integrity affect the attitudes toward advertisements of election campaign that show partisan cues.

Improved performance of AlGaN-based deep ultraviolet light-emitting diodes with nano-patterned AlN/sapphire substrates

Lee, Donghyun,Lee, Jong Won,Jang, Jeonghwan,Shin, In-Su,Jin, Lu,Park, Jun Hyuk,Kim, Jungsub,Lee, Jinsub,Noh, Hye-Seok,Kim, Yong-Il,Park, Youngsoo,Lee, Gun-Do,Park, Yongjo,Kim, Jong Kyu,Yoon, Euijoon American Institute of Physics 2017 Applied Physics Letters Vol.110 No.19

Computer-aided Analysis of Stability and Muscular Movement of Lower Limbs during Pirouette in Ballet

Sungwoo Park(박성우),Changmin Pyo(표창민),Jungsub Lee(이정섭),Junghoon Kwon(권정훈),Kunwoo Lee(이건우) (사)한국CDE학회 2010 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2010 No.1

Ballet is a famous dance form characterized by elegant motion. Ballet dancers wear special shoes developed specifically to reduce the load on the muscles of their lower limbs. Such shoes are necessary because normal shoes have limited capacity when it comes to expressing beautiful and stable motion. Since ballet shoes are popularly used by dancers, it would be beneficial to verify their functions by computer simulations. To verify the functions of ballet shoes, we studied the pirouette, a motion in which a dancer makes one or two revolutions on a vertical axis passing through the left leg. During a pirouette, dancers balance themselves on their left leg; therefore, this motion requires stability and the muscular force of the left leg. We conducted experiments with three types of shoes?pointe shoes, sneakers, and normal shoes?and we compared the three types. We used SIMM to analyze motion stability and the load on the muscle of the axial leg. For measuring stability during a pirouette, we used the standard deviation of the distances between the axis of rotation and the center of mass of the dancer. The sneakers showed the least standard deviation, followed by the pointe shoes; normal shoes had the greatest standard deviation. The experiment with pointe shoes showed the least muscle burden. The burden with normal shoes was four times as large as that with pointe shoes and two times as large as that with sneakers. In this paper, we have used computer simulation as a study approach to help dancers select shoes most effective for them and to suggest new designs for ballet shoes.

지식 창출을 위한 논리로서 가추법(假推法)과 교수설계 적용을 위한 탐색

김정섭 ( Jungsub Kim ),박수홍 ( Su Hong Park ) 한국교육공학회 2002 교육공학연구 Vol.18 No.4

종합병원 영상의학과의 감염관리 대한 분석

신정섭(Jungsub Shin),박철우(Cheolwoo Park),전병규(Byeongkyou Jeon) 한국방사선학회 2012 한국방사선학회 논문지 Vol.6 No.5

경상북도에 소재한 5개 종합병원 영상의학과의 오염도를 계수하고, 오염 원인균을 배양하여 동정하고 이를 토대로 지역사회 영상의학과의 효율적인 감염관리 방안을 모색하고자 하였다. 확인된 표면오염 균주는 Staphylococcus, Micrococcus, Pseudomonas stutzeri, Pseudomonas oryzihabitans로 병원 감염의 원인균으로 알려진 균주였고 영상의학과의 오염원으로 특이성을 가진 균주는 없었다. 조사대상 병원은 비슷한 감염관리교육을 실시하고 있었으나 병원별 오염도의 차이는 유의한 차이를 보였다. 조사대상 병원별 접촉원에 따른 오염도의 차이는 방사선사 사용, 환자사용, 공통사용으로 구분하여 분석한 결과 환자사용이 방사선사사용, 공통사용에 비해 유의하게 높은 오염도를 보였다(p<0.001). 병원별 월평균 검사건수의 차이가 적은 장치는 모든 병원에서 유의한 차이를 보이지 않았으나 이에 비해 촬영건수가 가장 많은 일반촬영장치, 흉부전용촬영대의 오염도가 다른 촬영장치에 비해 오염도가 높았다. 또한 월평균 촬영건수가 많은 A, B, C 병원은 방사선사가 단독으로 사용하거나 또는 환자와 공통으로 사용하는 방사선조사장치, 사무용책상, 출입문 손잡이에서 비교적 높은 오염도를 보였다. This study aims to find a way to control infection of community radiology effectively by calculating the degree of contamination, culture and identifying the flora in radiology of five general hospitals in Gyeongsangbuk-do. Staphylococcus, Micrococcus, Pseudomonas stutzeri, Pseudomonas oryzihabitans were identified as surface flora. These are know to be pathogens of hospital acquired infection and there was no radiology-specific flora. Research subject hospitals were conducting similar infection control education but degree of contamination of each hospital showed significant difference. Difference in degree of contamination according to contact sources were analyzed by Contact sources were classified into technologist-using, patients-using and common-using materials. Analysis of each hospital’s degree of contamination showed that patient-using materials were significantly more contaminated than technologist-using and common-using materials (p<0.001). Devices which are similar to each other in monthly average frequency of use showed no significant difference in degree of contamination, but general X-ray devices and chest boards which are used most frequently showed higher degree of contamination than others. In addition, hospital A, B and C which have heavier monthly average caseload showed relatively high degree of contamination on irradiation devices which are used by technologists only or by technologists and patients commonly, office desks and doorpulls. Hence it is considered that intensity of infection control education should be different according to the degree of monthly average caseload. This study provided an opportunity to aware that technologists’ feeling of contamination is crucial for infection control of radiology, and the Accupoint ATP public hygiene monitoring system which was used in this study for measuring the degree of contamination was proved to be an effective measuring device for hospital acquired infection management.

모빌리티 산업의 경쟁 지형을 고려한 디지털 전환 추진 전략 연구

윤정섭(Jungsub Yoon),김석관(Seok-Kwan Kim),전지은(Jieun Jeon),박현준(Hyunjun Park) 과학기술정책연구원 2021 정책연구 Vol.- No.-

This study aims to propose policies for the emerging industry in consideration of the competitive landscape of the mobility industry, where the industrial ecosystem is rapidly changing. Firms in the mobility industry can be largely divided into traditional car-makers, digital-based firms, and mobility service firms. Promotion policies for digital transformation are derived according to the policy needs of each type of firm. The analysis of this study focused on ① the automobile industry at the technology-firm-industry level, ② the digital transformation policy for the mobility industry, and ③ the needs of the mobility industry. First, as a result of the industrial ecosystem analysis, this study addresses that the digitalization of traditional car-makers is very urgent in the process of changing the industrial structure centered on electric vehicles and future cars due to electrification and autonomous driving in the traditional automobile industry. In particular, the autonomous driving sector, which is the core of the future automobile industry, is shifting mainly to start-ups, but in the case of the domestic automobile industry, its competitiveness is declining due to its high dependence on OEM firms. Next, as a result of analyzing the evolution of technology, it is unveiled that the transition to electric vehicles was initiated in 2014, and it was confirmed that electric vehicles are at the beginning of the growth phase in the technology life cycle. Turning to the analysis of the representative firm of each type, Hyundai Motor, Tesla, and Uber, most of them are growing in a direction that invades each others territory. Hyundai Motor had pursued closed ecosystem, but after the industrial transition, it has tried to form an open ecosystem, whereas Tesla gradually shifted to a closed ecosystem. Furthermore, we found that Uber has pursued an open ecosystem as a limitation of service firms. Next, as a result of analyzing mobility industry support and digital transformation policies, major countries were focusing on the transition to zero-emission vehicles, while the United States and China are spurring autonomous driving technology innovation. In Korea, the mobility industry policy is being promoted by the Ministry of Trade, industry and Energy, the Ministry of Land, Infrastructure and Transport, and the Ministry of Environment. From the interview of experts in each type of firm, we derived several difficulties and needs which is necessary for the successful digital transformation in the mobility industry. First, the regulation related to new technologies has not been fully legitimated. In addition, due to the significances of digital experts, firms are hard to hire new digital experts who is required for digitalization. Even if firms tried to contribute to digitalization pursued by the government, they may fail due to the lack of the common data platform. In addition, mobility infrastructure such as charging station and cities should be designed for the introduction of next-generation mobility. Lastly, they considered that the government should manage the education curriculum for nurturing experts for data analysis and actively expand the employment support business to solve the wage problem of professional manpower. Finally, this study proposes five policies in response to the transformation of the industrial ecosystem and the policy needs required by firms. First, it is necessary to form a support organization to clarify new industrial technology regulations and review laws and systems. Second, the infrastructure to support the development of new industries should be expanded. Third, a system to support industrial technology development in the long term should be implemented. Fourth, the data platform for inter-firm cooperation needs to be standardized. Lastly, it is necessary to operate a program to support the human resources for new industry transformation and foster professional workers. The

TSV 기반 3D IC Pre / Post Bond 테스트를 위한 IEEE 1500 래퍼 설계기술

오정섭(Jungsub Oh),정지훈(Jihun Jung),박성주(Sungju Park) 대한전자공학회 2013 전자공학회논문지 Vol.50 No.1

칩 적층기술의 발달로 TSV(Through Silicon Via) 기반 3D IC가 개발되었다. 3D IC의 높은 신뢰성과 수율을 얻기 위해서는 pre-bond 와 post-bond 수준에서 다양한 TSV 테스트가 필수적이다. 본 논문에서는 pre-bond 다이의 TSV 연결부에서 발생하는 미세한 고장과 post-bond 적층된 3D IC의 TSV 연결선에서 발생하는 다양한 고장을 테스트할 수 있는 설계기술을 소개한다. IEEE 1500 표준 기반의 래퍼셀을 보완하여 TSV 기반 3D IC pre-bond 및 post-bond의 at speed test를 통하여 known-good-die와 무결점의 3D IC를 제작하고자 한다. TSV based 3D ICs have been widely developed with new problems at die and IC levels. It is imperative to test at post-bond as well as pre-bond to achieve high reliability and yield. This paper introduces a new testable design technique which not only test microscopic defects at TSV input/output contact at a die but also test interconnect defects at a stacked IC. IEEE 1500 wrapper cells are augmented and through at-speed tests for pre-bond die and post-bond IC, known-good-die and defect free 3D IC can be massively manufactured+.