Micro Pixels with a Operational Voltage- Independent Bias Circuit for Positron Emission Tomography

Himchan Park,Jungbin Lee,Hyunmook Kim,Jinwook Burm 대한전자공학회 2018 대한전자공학회 학술대회 Vol.2018 No.6

반도체 및 디스플레이 산업의 삼불화질소(NF₃) 배출량 추산 및 향후 관리 전략

박힘찬(Himchan Park),김상현(Sang-Hyoun Kim) 대한환경공학회 2024 대한환경공학회지 Vol.46 No.5

목적: 본 연구는 대한민국이 선언한 ‘2050 탄소중립’ 목표에 부응하여, 국가 주력 산업인 반도체 및 디스플레이 산업에서의 삼불화질소(NF3) 배출량을 추산하고, NF₃가 국가 온실가스 감축 목표(NDC)에 미치는 영향을 평가하는 것을 목적으로 한다. 또한, 『환경오염시설의 통합관리에 관한 법률』, 『대기환경보전법』, 『기후위기 대응을 위한 탄소중립ㆍ녹색성장 기본법』을 중심으로 NF₃ 배출에 대한 현행법적 규제의 현황을 조사하고, NF₃ 저감 및 대체 기술에 대한 국내 연구 및 개발 현황을 파악하였다. 방법: 이 연구에서는 국내 반도체 및 디스플레이 산업에서의 NF₃ 배출량을 추산하기 위하여 IPCC 2006 Tier 1에 근거한 계산 방법을 적용하였다. 산정식에 대한 계수의 채택은 IPCC 가이드라인에 주어진 계수, 기업별 공시 자료, 건축물대장, 구글 어스를 사용하였고 추산 값에 관한 판단은 기업의 공시 자료를 통해 수행하였다. 관계 법령 검토는 22개 법, 시행령, 시행규칙에 대해 반도체 및 디스플레이 사업장에서 배출되는 ‘NF₃’ 또는 ‘삼불화질소’를 규제하는 조목의 유무를 검토하였다. 저감 및 대체 기술에 관한 탐색은 Web of Science 등 인터넷 검색 플랫폼을 이용하였으며 기간은 반도체 및 디스플레이 업종의 최적가용기법의 논의 시점에 따라 2019년부터 2023년의 5년으로 지정되었다. 결과 및 토의: 추산 결과, NF₃ 배출량은 반도체 산업에서 상당한 온실가스 배출 요인이 될 수 있음을 확인하였다. A, B, C, D 기업의 ESG 보고서상 직접배출량과 본 연구에서의 추산 값을 비교한 결과 추산 값이 차지하는 비율이 기업 직접배출량의 평균 55%, 44%, 66%, 84%에 해당하는 것을 확인할 수 있었다. 이때, A, B 기업은 자사 ESG 보고서에 국내외 사업장별 직접배출량이 구분 없이 하나로 합산하여 발표하고 있어 해외 사업장 면적을 포함한 추산 값을 비교에 사용하였다. 추산 값의 총합은 2030년 산업 부문 온실가스 배출량 목표치의 2.066-2.233%에 달하는 것을 알 수 있어 이는 국가 온실가스 감축 목표 달성에 있어 중대한 영향을 미칠 수 있음을 시사한다. 법령 검토 결과, NF₃는 주로 『대기환경보전법』에 의해 관리되고 있으나, 두 업종의 ‘최적가용기법 기준서’를 제외한 광범위한 온실가스 관리 법령에서는 대부분 다루어지지 않는 것으로 확인되었다. NF₃ 저감 기술에 관한 연구는 상대적으로 미비한 것으로 보이며, 대체 가스 개발 또한 제한적이었다. 결론: 본 연구를 통해 NF₃ 배출이 대한민국의 온실가스 감축 목표에 상당한 영향을 미칠 수 있음이 확인되었다. 따라서, NF₃ 배출 저감 및 대체 기술 개발을 위한 국가적, 산업적 차원의 협력이 필요함을 제언한다. 본 연구의 결과는 NF₃ 관리 강화 및 저감 기술 개발을 위한 기초 자료로 활용 가능할 것으로 사료된다. Objectives : This study aims to estimate the emissions of nitrogen trifluoride (NF3) from South Koreas semiconductor and display industries, in alignment with the countrys “2050 Carbon Neutrality” goal, and assess the impact of NF₃ emissions on the national greenhouse gas reduction targets (NDC). It also investigates the current status of legal regulations on NF₃ emissions under key acts such as the 『Act On The Integrated Control Of Pollutant-discharging Facilities』, the 『Clean Air Conservation Act』, and the 『Framework Act On Carbon Neutrality And Green Growth For Coping With Climate Crisis』, alongside surveying mainly South Korea’s research and development on NF₃ mitigation and alternative technologies. Methods : To estimate NF₃ emissions in South Koreas semiconductor and display industries, the study applied the IPCC 2006 Tier 1 calculation method. Coefficients for the estimation were derived from IPCC guidelines, corporate disclosures, building registers, and Google Earth, with corporate disclosures being utilized for estimate validation. The legal review covered 22 laws, decrees, and regulations to check for provisions regulating “NF₃” or “nitrogen trifluoride” emissions from semiconductor and display facilities. Exploration of mitigation and alternative technologies was conducted through internet platforms like Web of Science, spanning five years from 2019 to 2023, in line with the timeline of Best Available Techniques discussions for these sectors. Results and Discussion : Estimated results confirmed that NF3 emissions could be a significant contribute to greenhouse gas emissions in the semiconductor industry. Comparing the estimated values with the direct emissions reported in the ESG reports of companies A, B, C, and D, it was found that the estimated values correspond to an average of 55%, 44%, 66%, and 84% of the companies direct emissions, respectively. For companies A and B, since their ESG reports combine domestic and overseas direct emissions without distinction, the estimated values including the area of overseas operations were used for comparison. The sum of the estimated values amounts to 2.066-2.233% of the industrial sectors greenhouse gas emission targets for 2030, which suggests that this could have a significant impact on achieving national greenhouse gas reduction goals. The legislative review revealed that while NF3 is mainly managed under the 『Clean Air Conservation Act』, it is largely unaddressed in a wide range of greenhouse gas management legislation, with the exception of the Best Available Techniques Reference Documents for the two industries. Research on NF₃ reduction technologies seems to be relatively scarce, and the development of alternatives to the gas has also been constrained. Conclusion : The study confirms the significant impact of NF₃ emissions on South Koreas greenhouse gas reduction goals, underscoring the need for national and industrial collaboration in developing NF₃ emission mitigation and alternative technologies. The results are expected to serve as valuable foundational data for policy decisions on strengthening NF₃-related regulations and developing mitigation technologies.

Unravelling additive-based nanocrystal pinning for high efficiency organic-inorganic halide perovskite light-emitting diodes

Park, Min-Ho,Jeong, Su-Hun,Seo, Hong-Kyu,Wolf, Christoph,Kim, Young-Hoon,Kim, Hobeom,Byun, Jinwoo,Kim, Joo Sung,Cho, Himchan,Lee, Tae-Woo Elsevier 2017 Nano energy Vol.42 No.-

<P><B>Abstract</B></P> <P>Organic-inorganic halide perovskite light emitting diode (PeLED) as a narrow band emitter is an emerging research field. To overcome limited electroluminescence efficiency of PeLEDs, trap-assisted non-radiative recombination in polycrystalline perovskite films should be reduced and the electron-hole balance in the PeLEDs must be improved. In this work, we investigated a practical way to effectively overcome above-mentioned issues by unravelling additive-based nanocrystal pinning (A-NCP) process using the carefully controlled electron transporting organic material solutions diluted in a volatile non-polar solvent. We found that without affecting the intrinsic crystal structure, A-NCP improved the radiative recombination rate by reducing effective defect density at grain boundaries due to the defect healing effect. Moreover, it induced the improved electron-hole balance in the dominantly p-type CH<SUB>3</SUB>NH<SUB>3</SUB>PbBr<SUB>3</SUB> based PeLEDs, leading to the highest efficiency of 8.79% ever reported to date among organic-inorganic halide perovskite-based green PeLEDs. Therefore, our work gives the effective approaches for efficient PeLEDs from the investigations of the role of A-NCP incorporating a tiny amount of an electron transporting molecule as an additive to increase radiative recombination rate of polycrystalline perovskite films.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effects of additive-based nanocrystal pinning process is systematically investigated. </LI> <LI> Grain size effect, defect healing effect, and improvedelectron injection are investigated. </LI> <LI> We achieved the highest device efficiency of 8.79% among OHP-based PeLEDs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Mechanism and effects of additive-based nanocrystal pinning process are investigated for highly efficient organic-inorganic halide perovskite light-emitting diodes.</P> <P>[DISPLAY OMISSION]</P>

Overcoming the electroluminescence efficiency limitations of perovskite light-emitting diodes

Cho, Himchan,Jeong, Su-Hun,Park, Min-Ho,Kim, Young-Hoon,Wolf, Christoph,Lee, Chang-Lyoul,Heo, Jin Hyuck,Sadhanala, Aditya,Myoung, NoSoung,Yoo, Seunghyup,Im, Sang Hyuk,Friend, Richard H.,Lee, Tae-Woo American Association for the Advancement of Scienc 2015 Science Vol.350 No.6265

<P><B>Brighter perovskite LEDs</B></P><P>Organic-inorganic hybrid perovskites such as methyl ammonium lead halides are attractive as low-cost light-emitting diode (LED) emitters. This is because, unlike many inorganic nanomaterials, they have very high color purity. Cho <I>et al.</I> made two modifications to address the main drawback of these materials, their low luminescent efficiency. They created nanograin materials lacking free metallic lead, which helped to confine excitons and avoid their quenching. The perovskite LEDs had a current efficiency similar to that of phosphorescent organic LEDs.</P><P><I>Science</I>, this issue p. 1222</P><P>Organic-inorganic hybrid perovskites are emerging low-cost emitters with very high color purity, but their low luminescent efficiency is a critical drawback. We boosted the current efficiency (CE) of perovskite light-emitting diodes with a simple bilayer structure to 42.9 candela per ampere, similar to the CE of phosphorescent organic light-emitting diodes, with two modifications: We prevented the formation of metallic lead (Pb) atoms that cause strong exciton quenching through a small increase in methylammonium bromide (MABr) molar proportion, and we spatially confined the exciton in uniform MAPbBr<SUB>3</SUB> nanograins (average diameter = 99.7 nanometers) formed by a nanocrystal pinning process and concomitant reduction of exciton diffusion length to 67 nanometers. These changes caused substantial increases in steady-state photoluminescence intensity and efficiency of MAPbBr<SUB>3</SUB> nanograin layers.</P>

선형 회귀분석을 활용한 국내선 내륙권 항공여객 수요예측

조힘찬(Himchan Cho),곽동기(Donggi Kwag),이강석(Kangseok Lee),최원혁(Wonhyuck Choi),박정표(Jungpyo Park),김서빈(Seobeen Kim) 항공우주시스템공학회 2018 항공우주시스템공학회 학술대회 발표집 Vol.2018 No.4

트레이닝 마스크 착용 유무에 따른 6주간 인터벌 훈련이 심폐기능에 미치는 영향

심힘찬 ( Himchan Shim ),양정옥 ( Jungok Yang ),김영수 ( Yiungsoo Kim ),이범진 ( Bomjin Lee ),김인형 ( Inhyung Kim ),김종빈 ( Jongbin Kim ),박준성 ( Joonsung Park ) 한국체육대학교 체육과학연구소 2021 스포츠사이언스 Vol.39 No.3

The purpose of this study is to compare and analyze changes in lung function depending on whether or not a training mask is worn, and to provide basic data on training methods and duration. This study targeted 16 men in their 20s and conducted 6-week training in the training mask wearing group and the non-wearing group. FVC: forced vital capacity in one second FEV1 / FVC: from the lungs. Statistical processing is performed by non-parameter statistical test (non-parameter statistical test of IBM SPSS 26.0 program) by observing changes in vital capacity (amount of air that can be forcibly exhaled), muscle activity of respiratory assist muscles (nose nose muscle, isobaric muscle), and maximal oxygen uptake. The change between pre- and post-time periods was tested by the Wilcoxon code rank test of nonparametric statistical test), and the statistical significance level was set to α = .05. The research results show that the TM-HIIT group (TM-HIIT: training mask-high intensity training group) has a significant difference between forced vital capacity FVC (p = .036) and forced forced expiratory volume FEV1 (p = .018). Shown. And no significant difference was found in the HIIT group (HIIT: high intensity training group). Second, in the TM-HIIT group, muscle activity necking on (p = .012) and isobaric muscle (p =. Appeared. Third, in the TM-HIIT group, maximal oxygen uptake (p =. .026) showed a significant difference. Overall, the results show that after wearing a training mask, there is an effect on lung function and maximal oxygen uptake during continuous training, strengthening the respiratory muscles and breathing. It is judged to have a positive effect on the function.

High Frame-Rate VGA CMOS Image Sensor Using Non-Memory Capacitor Two-Step Single-Slope ADCs

Junan Lee,Himchan Park,Bongsub Song,Kiwoon Kim,Jaeha Eom,Kyunghoon Kim,Jinwook Burm IEEE 2015 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS PART 1 R Vol.62 No.9

<P>This paper proposes a column-parallel two-step single-slope analog-to-digital converter (SS ADC) for high-frame-rate CMOS image sensors. The proposed two-step SS ADC circuit does not utilize an analog memory capacitor to store the value of the first ramp step. Instead, to handle problems such as the slope errors of the second ramp and the stored charge error from charge feed-through, it utilizes a very simple digital column circuit consisting of a coarse counter (coarse step counter) and a 4-to-16 decoder. The second ramp (fine ramp) slope has only one slope generator, regardless of the results of the first ramp decisions, to eliminate the slope mismatch between fine ramp slopes. A prototype sensor comprising 640 × 480 pixels was fabricated with a 0.13- μm CMOS process. The results of experiments conducted indicate that the proposed ADC can achieve a conversion time of 6.4 μs at a main clock frequency of 62.5 MHz, which is 10.2 times faster than the conventional SS ADC. The maximum frame rate of the proposed VGA CMOS Image Sensor (CIS) is 320 frames per second (fps). Further, the proposed circuit employs redundancy error correction logic to calibrate the error between the coarse and fine steps. The total power consumption is 72 mW from supply voltages of 2.8 V (analog) and 1.5 V (digital). The figure of merit (FoM) of the proposed VGA CMOS image sensor is 2.01 [e<SUP>-</SUP> nJ].</P>

Trajectory-based Active Inverse Reinforcement Learning for Learning from Demonstration

Sehee Kweon,Himchan Hwang,Frank C. Park 제어로봇시스템학회 2023 제어로봇시스템학회 국제학술대회 논문집 Vol.2023 No.10

딥러닝 분산 처리 시스템 구축 및 평가

윤동근(Dounggeun Yun),황힘찬(Himchan Hwang),박영민(Yeongmin Park),윤재찬(Jaechan Yoon),이대원(Daewon Lee) 한국정보기술학회 2023 Proceedings of KIIT Conference Vol.2023 No.6

Approaching ultimate flexible organic light-emitting diodes using a graphene anode

Han, Tae-Hee,Park, Min-Ho,Kwon, Sung-Joo,Bae, Sang-Hoon,Seo, Hong-Kyu,Cho, Himchan,Ahn, Jong-Hyun,Lee, Tae-Woo Nature Publishing Group 2016 NPG Asia Materials Vol.8 No.-

<P>Ultimate flexible organic light-emitting diodes (OLEDs) should have an ultra-high device efficiency, a low-efficiency roll-off at a high luminance and excellent flexibility. Here, we realized flexible tandem OLEDs using a graphene anode with a very high electroluminescent efficiency of similar to 205.9 cd A(-1), 45.2% (similar to 396.4 cd A(-1), 87.3% with a hemispherical lens) and a very low efficiency roll-off at a high luminance of similar to 6.6% at 10 000 cd m(-2) (similar to 3.8% with a hemispherical lens) by stacking two organic electroluminescence (EL) units. For the first time, we used an easily controlled and low-temperature processable charge generation layer with lithium nitride (Li3N). This simultaneously provided efficient stacking of EL units and enhanced compatibility of the flexible device on a thin plastic substrate. The flexible tandem OLEDs with a graphene anode also showed great flexibility against bending up to a bending strain of 6.7%. These results represent a significant advancement towards the production of next-generation flexible displays and solid-state lighting that use a graphene anode.</P>