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A Return-to-zero DAC with Tri-state Switching Scheme for Multiple Nyquist Operations
Yun, Jaecheol,Jung, Yun-Hwan,Yoo, Taegeun,Hong, Yohan,Kim, Ju Eon,Yoon, Dong-Hyun,Lee, Sung-Min,Jo, Youngkwon,Kim, Yong Sin,Baek, Kwang-Hyun The Institute of Electronics and Information Engin 2017 Journal of semiconductor technology and science Vol.17 No.3
A return-to-zero (RZ) digital-to-analog converter (DAC) with a tri-state switching scheme is proposed in this paper. The proposed scheme provides a triple weight output for RZ operation by using a conventional differential current switch and simple pseudo-differential F/Fs. The RZ function is realized with only two additional transistors in each F/F cell, which results in a power dissipation increase of less than 5%. To verify the performance of the proposed method, a 10-bit RZ DAC is fabricated using standard 180-nm CMOS technology. Measured results show that the worst SFDR performances are 60 dBc and 55 dBc in the 1st and 2nd Nyquist bands, respectively, when operating at 650 MHz clock frequency. The total power consumption is 64 mW, and the active area occupies $0.25mm^2$.
A Return-to-zero DAC with Tri-state Switching Scheme for Multiple Nyquist Operations
Jaecheol Yun,Yun-Hwan Jung,Taegeun Yoo,Yohan Hong,Ju Eon Kim,Dong-Hyun Yoon,Sung-Min Lee,Youngkwon Jo,Yong Sin Kim,Kwang-Hyun Baek 대한전자공학회 2017 Journal of semiconductor technology and science Vol.17 No.3
A return-to-zero (RZ) digital-to-analog converter (DAC) with a tri-state switching scheme is proposed in this paper. The proposed scheme provides a triple weight output for RZ operation by using a conventional differential current switch and simple pseudo-differential F/Fs. The RZ function is realized with only two additional transistors in each F/F cell, which results in a power dissipation increase of less than 5%. To verify the performance of the proposed method, a 10-bit RZ DAC is fabricated using standard 180-㎚ CMOS technology. Measured results show that the worst SFDR performances are 60 ㏈c and 55 ㏈c in the 1st and 2nd Nyquist bands, respectively, when operating at 650 ㎒ clock frequency. The total power consumption is 64 ㎽, and the active area occupies 0.25 ㎟.
Activity gradient carbon felt electrodes for vanadium redox flow batteries
Kim, Youngkwon,Choi, Yun Young,Yun, Nari,Yang, Mingyu,Jeon, Yonghee,Kim, Ki Jae,Choi, Jung-Il Elsevier 2018 Journal of Power Sources Vol.408 No.-
<P><B>Abstract</B></P> <P>An activity gradient carbon felt (AGCF) electrode is prepared by a simple thermal oxidation method, which is composed of both a low activity electrode near the inlet side and a high activity electrode near the outlet side. The vanadium redox flow battery (VRFB) full cell with AGCF electrodes shows higher discharge capacity (18.7 Ah L<SUP>−1</SUP>) and coulomb efficiency (93.6%) than non-gradient carbon felt electrodes (14.3 Ah L<SUP>−1</SUP>, 88.4%) at a current density of 80 mA cm<SUP>−2</SUP>. From the computational analysis, the AGCF electrodes exhibit reduced overpotential results as well as improved uniform activity at low reactant concentration condition during charging and discharging at the current density. These results suggest that the AGCF electrode is an effective electrode design for high-performance VRFB featuring high energy density by improving electrolyte utilization as well as high roundtrip efficiency by improving energy efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Activity gradient carbon felt was prepared by a thermal oxidation pre-treatment. </LI> <LI> AGCF enhanced electrolyte utilization at the current density of 80 mA cm<SUP>-2</SUP>. </LI> <LI> AGCF enhanced the uniformity of the reaction rates in the electrode. </LI> <LI> AGCF improved energy efficiency, yielding to a decrease of the overpotential. </LI> </UL> </P>
Kim, Youngkwon,Kim, Hyeong Jun,Kim, Jin-Seong,Yun, Hongseok,Park, Hyeonjung,Han, Junghun,Kim, Bumjoon J. American Chemical Society 2018 Chemistry of materials Vol.30 No.21
<P>In selective solvents, poly(3-hexylthiophene) (P3HT)-based block copolymers (BCPs) assemble into one-dimensional nanowires (NWs) due to strong π-π stacking interactions of the P3HT block. Herein, we report the effect of P3HT regioregularity (RR) on the assembly of P3HT-based amphiphilic BCPs in solution. We synthesized a series of P3HT-<I>block</I>-poly(2-vinylpyridine) (P3HT-<I>b</I>-P2VP) copolymers with similar molecular weights and P3HT volume fractions but with different RRs, ranging from 55% to 95%, and studied their assembly in tetrahydrofuran/<I>n</I>-butanol mixtures. P3HT-<I>b</I>-P2VP copolymers with high RR (>80%) crystallized into well-ordered NWs with core widths consistent with fully extended P3HT chains. In BCP nanostructures with decreasing RR, more flexible P3HT chains produced gradual increases in the width of the NWs, from 12 to 24 nm. Eventually, a morphological transition to spherical micelle structures was observed at 55% RR. The structural differences were visualized by incorporating Au nanoparticles, which locate at the interface of P3HT and P2VP blocks, onto the NWs and imaging the resulting hybrid nanostructures by transmission electron microscopy. In addition, the crystalline behaviors of the assembled nanostructures were determined using differential scanning calorimetry and grazing incidence X-ray scattering. We elucidated important relationships between the solution assembly behaviors and the crystalline interactions of conjugated semicrystalline-coil BCPs, which will guide design of future versatile BCP nanostructures.</P> [FIG OMISSION]</BR>
Sangwon Yun,Boohwi Hong,Hoseop Kim,Woosuk Chung,Youngkwon Ko,Yoon-Hee Kim 조선대학교 의학연구원 2021 Medical Bilogical Science and Engineering Vol.4 No.1
Cerebral venous sinus thrombosis (CVST), a rare cerebrovascular event, occurs in approximately 5 out of 1,000,000 people. Because subarachnoid hemorrhage (SAH) due to CVST during emergency cesarean section is rare, this condition is difficult to recognize and diagnose in patients under anesthesia. This report describes a parturient who experienced severe headache and motor weakness during an emergency cesarean section. The first manifestation of CVST was a severe headache, which overlapped with the presentation of SAH, making early diagnosis verydifficult. Anesthesiologists should be aware of the risk of CVST in pregnant women and closely monitor those who experience slight changes in intraoperative neurological symptoms.
근적외선을 이용한 휴대용 쇠고기 냉해동 여부 판별 시스템 개발
박성민 ( Seongmin Park ),양명균 ( Myeongkyoon Yang ),윤영권 ( Youngkwon Yun ),김동준 ( Dong Jun Kim ),조성인 ( Seong In Cho ) 한국농업기계학회 2019 한국농업기계학회 학술발표논문집 Vol.24 No.2
본 연구는 쇠고기의 냉해동 여부를 판별하기 위한 근적외선 분광분석 시스템 개발에 대한 것이다. 2018년 기준 우리나라 국민이 1인당 소비하는 쇠고기는 연간 12.6kg으로 이를 감당하기 위한 쇠고기 공급은 국내 생산량이 약 24만 톤, 수입량이 약 41만 톤에 이른다. 그런데 쇠고기는 단가가 비싼 것이 비해 냉동하지 않을 시 보관 가능 기간이 길지 않기 때문에 유통업자들이 냉동과정을 거친 제품을 냉장육으로 속여서 파는 일이 흔하다. 이는 특별사법경찰이 출동하여 단속하는 심대한 범죄이나 일선 소비자들이 구매 과정에서 확인할 수 없기 때문에 피해 사례가 계속 발생하고 있다. 이에 본 연구에서는 신선한 상태로 냉장된 시료와 일정 기간 냉동을 거친 후 냉해동된 시료에 대한 근적외선 스펙트럼을 휴대용 스펙트로미터로 획득하여 그 결과를 머신러닝하고, 이렇게 분류된 결과를 토대로 소비자가 구매 직전 즉시 본인이 구매하려는 쇠고기가 냉동된 적이 있는지에 대한 여부를 판정할 수 있는 스마트폰 애플릿을 제작하였다. 추후 실험실 환경에서 얻어진 전단응력 및 보수력 데이터와 함께 연계시키면 보다 완성도 높은 결과를 얻을 수 있을 것으로 전망된다.
Development of a System Grading Color and Texture of Beef using Spectral Information
( Seongmin Park ),( Daesik Son ),( Myongkyoon Yang ),( Jinshi Cui ),( Youngkwon Yun ),( Sung Ho Yoon ),( Seong In Cho ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1
The meat color and texture are important factors in determining beef grade. However, unlike marbling, which can be easily judged by the human eye, the color and texture grade of the meat are highly likely to be misjudged by the person who makes the judgment according to the environment of the place. Therefore it is important to make equipment that can easily determine the color and texture of meat. In this study, we tried to develop a system for easily determining the color and texture grade of beef using portable spectroscopic analyzer. First, the spectroscopic information of each beef carcass was collected at the place where the beef grade was actually judged by the portable spectrometer. The wavelength band is from 400 nm to 1000 nm. And machine learning was used to match the meat color and texture grade information to this spectral information. The number of iterations was set to 10,000. Machine learning has reached an accuracy level that allows the system to judge adequately the color and texture. Based on these results, we made a mobile application. By using this application, we have implemented a system that can easily rate meat color and texture grade at the judgment place.
근적외선을 이용한 휴대용 한우 조직감 등급 판별 시스템 개발
박성민 ( Seongmin Park ),손대식 ( Daesik Son ),양명균 ( Myeongkyoon Yang ),윤영권 ( Youngkwon Yun ),김동준 ( Dong Jun Kim ),조성인 ( Seong In Cho ) 한국농업기계학회 2019 한국농업기계학회 학술발표논문집 Vol.24 No.1
본 연구는 한우육의 조직감을 판별하기 위한 근적외선 분광분석 시스템 개발에 대한 것이다. 한우육은 등급 판정에 있어서 마블링이 가장 중요한 요소로 알려져 있었으나 최근 과도한 지방 섭취를 피하는 소비자들의 트렌드 및 곡물사료를 사용하는 한우 사육 방식에 대한 문제가 제기되어 육색과 조직감을 중심으로 한 새로운 등급판정체계가 도입될 예정이다. 그런데 조직감에 대한 수치 데이터를 얻기 위해서는 실험실 환경에서 전단 응력을 측정하는 것이 유일한 방법이기 때문에 등심육을 파괴하지 않고 빠르게 판정해야 하는 도축장 환경에서는 전단응력 측정 대신 품질판정사의 감에 의존하고 있다. 판정을 인력에 맡기면 사람마다 결과가 달라지기도 하고 개인의 컨디션 및 환경요소에 의해 영향을 받을 수도 있는 문제가 발생한다. 이에 본 연구에서는 품질판정사의 분류에 따라 조직감 등급이 나누어진 한우육에 대한 근적외선 스펙트럼을 휴대용 스펙트로미터로 획득하여 그 결과를 머신러닝하고, 이렇게 분류된 결과를 토대로 도축장 환경에서 즉시 판정이 이루어질 수 있는 스마트폰 애플릿을 제작하여 현장 테스트까지 수행하는 것을 목표로 하였다. 추후 실험실 환경에서 얻어진 전단응력 데이터와 함께 연계시키면 보다 완성도 높은 결과를 얻을 수 있을 것으로 전망된다.