귀비탕가감방(歸脾湯加減方)이 구속 Stress 유발 백서(白鼠)에 미치는 영향

김기현,장규태,김장현,권혁란,Kim, Ki-Hyun,Chang, Gyu-Tae,Kim, Jang-Hyun,Kwon, Hyuk-Ran 대한한방소아과학회 2005 대한한방소아과학회지 Vol.19 No.2

Objectives: This study was aimed to find out the anti-stress and protective-memory effect of Quibitanggagam(QBT) on stress of rats Methods : This experimental study was conducted with elevated plus maze test, passive avoidance test, morris water maze test, and consequently density of AchE reactivity in the CA1 of hippocampus to research the learning and memory of rats affected by restraint stress, Results: Passive avoidance test revealed that time latency of retention test for QBT+Stress group significantly decreased on 2, 3rd day. Morris water maze revealed that acqusitive ability of QBT+Stress group significantly improved on 2, 3rd day and retentive ability of QBT+Stress group was significantly improved on 7th day. Elevated plus maze test revealed that latency in open arm of QBT+Stress group significantly decreased and locomotor activity(number of entered arm) of QBT+Stress group was significantly increased. The values of density of AchE stained nuclei in the CA1 of hippocampus QBT+Stress group was significantly increased compared with SAL+Stress group. Conclusion : According to the above results, it is concluded that QBT will be useful as a remedy against stress disease and improving memory.

급속승온공정을 이용한 사출성헝된 Fe 소결체의 미세조직 및 소결거동

김기현,한재길,유지훈,최철진,이병택,Kim Ki-Hyun,Han Jae-Kil,Yu Ji-Hun,Choi Chul-Jin,Lee Byong-Taek 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.6

Using the nano Fe powders having 50 nm in diameter, Fe compact bodies were fabricated by injec-tion molding process. The relationship between microstructure and material properties depending on the volume ratio of powder/binder and sintering temperature were characterized by SEM, TEM techniques. In the compact body with the volume percentage ratio of 45(Fe powder) : 55(binder), which was sintered at $700^{\circ}C,$ the relative density was about $97{\%},$ and the values of volume shrinkage and hardness were about $66.3{\%}$ and 242.0 Hv, respec-tively. Using the composition of 50(Fe powder) : 50(binder) and sintered at $700^{\circ}C,$ the values of relative density, volume shrinkage and hardness of Fe sintered bodies were $73.3{\%},\;47.6{\%}$ and 152.8 Hv, respectively. They showed brittle fracture mode due to the porous and fine microstructure.

용매열법을 이용한 CuInSe₂ 나노 입자 합성

김기현,전영갑,박병옥,윤경훈,Kim Ki-Hyun,Chun Young-Gab,Park Byung-Ok,Yoon Kyung-Hoon 한국재료학회 2004 한국재료학회지 Vol.14 No.10

$CuInSe_2$ (CIS) nanoparticles of chalcopyrite structure were directly synthesized by a solvothemal method in an autoclave with diethylamine as a solvent. A morphology change of the nanoparticles was observed as a function of reaction temperatures and times. Dense rod-type CIS nanoparticles with width of $5\sim10mm$ and length in the range of 30-80 nm were obtained at $180^{\circ}C$ for 36 hrs whereas spherical particles with diameter in the range of 5-10 nm were observed at $250^{\circ}C$ for 36 hrs. The formation of the rod-like nanoparticles in diethylamine, without double N-chelation, was explained by the Solution-Liquid-Solid (SLS) mechanism.

북동태평양지역의 방산충 생층서 및 고해양환경 연구

김기현,박정희,Kim, Ki-Hyune,Park, Jeoung-Hee 한국해양과학기술원 1999 Ocean and Polar Research Vol.21 No.2

Radiolarian assemblages from KODOS area were analyzed in order to understand the biostratigraphy and paleoceanography of deep-sea sediment from the Northeast Equatorial Pacific. The sediment core was divided into two or three units on the basis of the chemical and physical properties. In the upper sediment, mixtures of Quaternary and Tertiary radiolarians are found indicating active reworking processes. Dissolution of radiolarians seem to increase with depth. Radiolarians are seldom in Unit III presumably due to dissolution and corrosion. The middle part of unit I appears to correspond to Collosphaera invaginata Zone (0.21 Ma). Unit II belongs to Collosphaera tuberosa Zone. Based on the absence of Stylatractus universus, we estimate its age to be younger than 0.42 Ma. Based on our analyses of radiolarians in Unit I and II, we estimated the age of unit III as Tertiary, particularly from Oligocene to Miocene. There may to be hiatuses of more than 3 My from late Miocene to Pliocene, which probably resulted from erosion and dissolution by the Antarctic Bottom Water Sedimentation rates during Quaternary range from 0.15 to 0.50 mm/ky with significant variabilities among stations. Radiolarians in the study area were mostly warm-water species.

한국 황해지역의 DMS 분포특성에 대한 연구 - 덕적도를 중심으로

김기현,김지영,송기범,김나영,이강웅,배귀남,Kim, Ki-Hyun,Kim, Ji-Young,Song, Ki-Bum,Kim, Na-Young,Lee, Gang-Woong,Bae, Gwi-Nam 한국지구과학회 2000 한국지구과학회지 Vol.21 No.1

황해지역에서 생성 및 배출되는 자연황화합물의 규모를 정량적으로 구명하기 위한 노력의 일환으로, 본 연구진은 황해에 위치한 덕적도를 주 측정점으로 설정하고 대기 중에 존재하는 DMS의 농도분포를 1999년 4월과 9월 2차례의 집중측정기간을 통해 측정하였다. 그리고 이에 덧붙여 1999년 6월에는 청도-인천간 해상실험을 통해 황해상의 DMS 농도를 측정하였다. 덕적도를 중심으로 시행한 양 측정기간 중 DMS의 농도값은 4월 측정의 경우 평균과 표준오차가 $24.0{\pm}40.5$ pptv(n=40)인데 반해 9월 측정의 경우 $61.1{\pm}37.9$ pptv(n=35)로 나타났다. 그리고 선상실험에서 측정한 DMS 값은 대체로 배경농도에 가까운 낮은 농도범위를 갖는 것으로 밝혀졌다. DMS의 농도분포는 일반적으로 불규칙한 양상을 보였지만, 주변 기상인자의 변화경향과 유사하게 변화하는 것으로 나타났다. 본문에서는 이러한 연구결과와 기존의 연구결과 등을 연계하여 잠정적인 연간 배출량규모를 4Gg 대로 추정하였다. 이러한 배출규모는 과거 제주지역 등을 중심으로 측정한 결과에 비해 상대적으로 낮은 수치인데, 시간적 및 공간적으로 대표성이 강한 보다 객관적인 배출량을 산정하기 위해서는 추가적인 측정 자료의 축적이 요구된다. This study was performed to accumulate database for natural sulfur emissions in the Yellow Sea region of Korea. The atmospheric concentrations of dimethylsulfide(DMS) were measured during two intensive field experiments (April and September 1999) from Duk-Juk Island located in the Yellow Sea. Ship-measurement of DMS was made additionally between Chungdo(China) and Inchun(Korea) across the Yellow Sea during June 1999. The mean(and ISD) of DMS concentrations in Duk-Juk Island during two field campaigns was $24.0{\pm}40.5$(n=40, April) and $61.1{\pm}37.9$ pptv(n=35, September), respectively. The atmospheric DMS measured from ship experiments was generally low and close to the background concentrations in the open sea area. The temporal distributions of DMS concentration were complicated in some sense but comparable to those of ambient meteorological parameters. On the basis of our measurements of atmospheric DMS(and evidence found from previous studies), the sea-to-air flux of DMS in the Yellow Sea is estimated to be about 4Gg S/yr. This amount of natural S emissions is relatively lower than the estimates derived for Cheju Island. Therefore, additional experiments may be desperate to derive more reliable figures for natural sulfur emissions in the Yellow Sea region.

JFET 영역의 이중이온 주입법을 이용한 Power MOSFET의 온저항 특성에 관한 연구

김기현,김정한,박태수,정은식,양창헌,Kim, Ki Hyun,Kim, Jeong Han,Park, Tae-Su,Jung, Eun-Sik,Yang, Chang Heon 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.4

Device model parameters are very important for accurate estimation of electrical performances in devices, integrated circuits and their systems. There are a large number of methods for extraction of model parameters in power MOSFETs. For high efficiency, design is important considerations of a power MOSFET with high-voltage applications in consumer electronics. Meanwhile, it was proposed that the efficiency of a MOSFET can be enhanced by conducting JFET region double implant to reduce the On-resistance of the transistor. This paper reports the effects of JFET region double implant on the electrical properties and the decreasing On-resistance of the MOSFET. Experimental results show that the 1st JFET region implant diffuse can enhance the On-resistance by decreasing the ion concentration due to the surface and reduce the On-resistance by implanting the 2nd Phosphorus to the surface JFET region.

저가의 cryogenic milling 비진공법을 이용한 나노입자 CuInSe₂ 광흡수층 제조

김기현,박병옥,Kim, Ki-Hyun,Park, Byung-Ok 한국결정성장학회 2013 韓國結晶成長學會誌 Vol.23 No.2

$CuInSe_2$(CIS) chalcopyrite 물질은 고효율 박막 태양전지를 위한 광흡수층의 물질로 매우 잘 알려져 있다. 최근 태양광 산업의 흐름은 안정적인 재료 개발과 가격 경쟁력 있는 태양전지를 위한 효율적인 제조 공정을 일치시키는 것이다. 저가의 CIS 광흡수층 위해 다양한 방법으로 제조를 시도하였고, 본 논문에서는 CIS 광흡수층을 저가형으로 제조를 위해 상용화되는 6 mm pieces를 사용하여 high frequency ball milling과 cryogenic milling을 이용해 CIS 나노입자를 얻었다. 그리고, CIS 광흡수층은 불활성 분위기의 glove box 안에서 milling된 나노입자를 사용하여 paste coating법으로 제조하였다. Chalcopyrite CIS 박막은 기판온도 550도에서 30분간 셀렌화 한 후 성공적으로 제조되었으며, Al/ZnO/CdS/CIS/Mo 구조의 CIS 태양전지는 evaporation, sputtering 및 chemical bath deposition(CBD) 등 다양한 증착 방법으로 각각 제조하였다. 결론적으로, 나노입자를 이용한 CIS 태양전지 전기적 변환효율은 1.74 %를 얻었으며, 개방전압(Voc)는 29 mV, 합선전류밀도(Jsc)는 35 $mA/cm^2$, 그리고 충진율(FF)은 17.2 %였다. 나노입자 CIS 광흡수층은 energy dispersive spectroscopy(EDS), x-ray diffraction(XRD) 그리고 high-resolution scanning electron microscopy(HRSEM) 등으로 특성 분석을 하였다. Chalcopyrite material $CuInSe_2$ (CIS) is known to be a very prominent absorber layer for high efficiency thin film solar cells. Current interest in the photovoltaic industry is to identify and develop more suitable materials and processes for the fabrication of efficient and cost-effective solar cells. Various processes have been being tried for making a low cost CIS absorber layer, this study obtained the CIS nanoparticles using commercial powder of 6 mm pieces for low cost CIS absorber layer by high frequency ball milling and cryogenic milling. And the CIS absorber layer was prepared by paste coating using milled-CIS nanoparticles in glove box under inert atmosphere. The chalcopyrite $CuInSe_2$ thin films were successfully made after selenization at the substrate temperature of $550^{\circ}C$ in 30 min, CIS solar cell of Al/ZnO/CdS/CIS/Mo structure prepared under various deposition process such as evaporation, sputtering and chemical vapor deposition respectively. Finally, we achieved CIS nanoparticles solar cell of electric efficient 1.74 % of Voc 29 mV, Jsc 35 $mA/cm^2$ FF 17.2 %. The CIS nanoparticles-based absorber layers were characterized by using EDS, XRD and HRSEM.

HEVC를 위한 저면적 고성능 다중 모드 1D 변환 블록 설계

김기현,류광기,Kim, Ki-Hyun,Ryoo, Kwang-Ki 한국정보통신학회 2014 한국정보통신학회논문지 Vol.18 No.1

본 논문에서는 연산 시간이 긴 곱셈기 패스를 낮은 주파수에서 동작하는 저면적의 HEVC(High Efficiency Video Coding)용 다중 모드 일차원 변환 블록을 구현하는 효율적인 방법을 제시하였다. 제시한 방법은 전체 면적을 줄이기 위하여 일반적인 변수와 변수를 입력으로 받는 곱셈기 대신 행렬의 계수 특성을 이용한 상수와 변수를 입력으로 받는 상수 곱셈기를 사용하였다. 상수 곱셈기 사용으로 인하여 전체적인 처리량을 증가시켰으며 늘어난 처리량으로 인해 남는 동작 사이클을 이용하여 연산시간이 많이 걸리는 곱셈기 부분에 멀티 사이클 패스를 구성하여 곱셈기의 동작 주파수를 낮게 하면서 전체 연산량은 유지시켰다. TSMC 0.18um CMOS 공정 라이브러리를 이용하여 실제 하드웨어를 구현한 결과 4k($3840{\times}2160$) 영상을 기준으로 최소 동작 주파수는 186MHz이고 최대 동작 주파수는 300MHz이다. This paper suggest an effective idea to implement an low area multi-mode one dimension transform block of HEVC(High Efficiency Video Coding). The time consuming multiplier path is designed to operate on low frequency. Normal multipliers dealing with variable operands are replaced with smaller constant multipliers which do the product with constant coefficient and variable only using shifters and adders. This scheme increases total multiplier counts but entire areas are reduced owing to smaller area of constant multiplier. Idle cycles caused by doubled multipliers enable to use multi-cycle paths on the cycle eating multiplier data path. Operating frequency is lowered by multi-cycle path but total throughput is maintained. This structure is implemented with TSMC 0.18 CMOS process library, and operated on 186MHz frequency to process a 4k($3840{\times}2160$) image. Max operating frequency is 300MHz.

전단벽 구조물의 진동대 시험결과와 유한요소 내진해석결과 비교

김기현,장영선,Kim, Ki Hyun,Jang, Young Sun 한국지진공학회 2021 한국지진공학회논문집 Vol.25 No.3

In this study, the seismic safety of nuclear power plant structures is evaluated and verified by performing a vibration test on a relatively simple shear wall structure. The shear walls are the prominent members of nuclear power plants and resist the seismic load. The shear wall structure is designed and manufactured to perform shaking table tests and is used to increase the accuracy of the analytical method by comparing them with the numerical analysis results. Different results will be checked and more efficient application methods will be studied depending on the method of designing reinforced concrete structures.

논문편 : 양육스트레스 척도의 개발

김기현,강희경 ( Ki Hyun Kim,Hee Kyung Kang ) 대한가정학회 1997 Human Ecology Research(HER) Vol.35 No.5