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이정희,Jae-Hee Park,Jae-Hoon Lee,Jae-Seung Lee,Jong-Wook Kim,Kye-Seok Lee,Sung-Bum Bae,Sung-Ho Hahm 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.III
Based on investigating the effects of isoelectronic Al-doping on GaN film, a new layer structure is proposed for a heterostructure field effect transistor (HFET) including an isoelectronic Al-doped channel. The electron mobility measured at 77 (300) K significantly increased from 145 (130) cm$^2$/V$\cdot$s in the undoped sample to 823 (440) cm$^2$/V$\cdot$s in the Al-doped sample grown with a trimethylaluminum flow rate of 3 $\mu$mol /min, while maintaining the background doping concentration below $\sim$ 6 $\times$ 10$^{16}$ cm$^{-3}$. Two-dimensional electron gas mobilities of 1690 and 9280 cm$^2$/Vs were measured for a 25-nm Al$_{0.3}$Ga$_{0.7}$N/1-nm AlN/70-nm Al-doped channel/GaN heterostucture at 300 and 77 K, respectively. The improved results are explained based on a decrease in the compensating acceptors or other defects associated with the formation of screw dislocation due to the incorporation of Al in the channel layer, plus a decrease in the alloy disorder scattering in the heterostructure based on introducing a binary thin AlN layer between the Al$_{0.3}$Ga$_{0.7}$N and Al-doped channel layers.
WAVESTAR형 파력발전장치의 유압식 2차변환장치의 물리모델 구축에 관한 연구
이정희,오재원,하윤진,박지용,천호정,김경환,Lee, Jung-Hee,Oh, Jaewon,Ha, Yoon-Jin,Park, Ji-Yong,Cheon, Ho-Jeong,Kim, Kyong-Hwan 한국산업융합학회 2020 한국산업융합학회 논문집 Vol.23 No.6
This study was conducted to develop an efficiency prediction program of a hydraulic secondary energy converter for calculating annual power generation of a Wavestar type wave power generator. Using the period and wave height obtained from the frequency domain analysis, the behavior of the floating body was obtained by assuming the sin function. The piston displacement and speed of the hydraulic cylinder were calculated considering the behavior of the floating body and the shape of the mechanism. The numerical simulation of the hydraulic system was performed by physically modeling the hydraulic cylinders, check valves, hydraulic motors, which are the main devices. In the future, this analysis program will be used to develop a program for estimating annual power generation of a moveable body type wave power generation device.
터빈블레이드의 냉각에서 충돌제트에 의해 변화되는 유동 및 열전달 특성에 관한 수치해석적 연구
이정희,김신일,유홍선,최영기,Lee, Jeong-Hui,Kim, Sin-Il,Yu, Hong-Seon,Choe, Yeong-Gi 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.12
A numerical simulation has been carried out for the jet impinging on a flat plate and a semi-circular concave surface. In this computation finite volume method was employed to solve the full Navier-Stokes equation based on a non-orthogonal coordinate with non staggered variable arrangement. The standard k-.epsilon. turbulent model and low Reynolds number k-.epsilon. model(Launder-Sharmar model) with Yap's correction were adapted. The accuracy of the numerical calculations were compared with various experimental data reported in the literature and showed good predictions of centerline velocity decay, wall pressure distribution and skin friction. For the jet impingement on a semi-circular concave surface, potential core length was calculated for two different nozzle(round edged nozzle and rectangular edged nozzle) to consider effects of the nozzle shape. The result showed that round edged nozzle had longer potential core length than rectangular edged nozzle for the same condition. Heat transfer rate along the concave surface with constant heat flux was calculated for various nozzle exit to surface distance(H/B) in the condition of same jet velocity. The maximum local Nusselt number at the stagnation point occurred at H/B = 8 where the centerline turbulent intensity had maximum value. The predicted Nusselt number showed good agreement with the experimental data at the stagnation point. However heat transfer predictions along the downstream were underestimated. This results suggest that the improved turbulence modeling is required.
통증완화를 위해 비파엽 찜질을 병행한 암환자 6례에 대한 증례보고
이정희,장보형,권혁성,권오섭,Lee Jung-Hee,Jang Bo-Hyoung,Kweon Hyug-Sung,Kweon O-Seob 대한한방내과학회 2003 大韓韓方內科學會誌 Vol.24 No.4
Objective: The purpose of this study is to see whether pain in cancer patients is decreased by Eriobotryae Folium Fomentation. Methods: We examined the change in pain among six cancer patients, prescribing Eriobotryae Folium Fomentation. As for evaluating methods, we used the case history of pain, the direct evaluation of pain, the indirect evaluation of pain. The direct evaluation of pain is subdivided by the language expression, the non-language expression, and Visual analog scale(VAS). The indirect evaluation of pain is subdivided by the condition of walking, mood and the condition of sleep. Results: After two weeks, any remarkable pain decrease is not observed in both of the direct evaluation and indirect evaluation.
흰쥐에서 DWP-04가 D-galactosamine에 의해 유도된 간독성의 보호효과
이정희,지상철,김석환,신영호,최종원,Lee Jung-Hee,Chi Sang Cheol,Kim Seok-Hwan,Shin Young-Ho,Choi Jongwon 한국생명과학회 2005 생명과학회지 Vol.15 No.3
This study was conducted to investigate the biological activity and hepatoprotective effect of DWP-04 [DDB : selenium yeast: glutathione (31.1 : 6.8 : 62.1(w/w/w)] in D-galactosamine (GaIN) intoxicated rats. The DWP-04 (50, 100 or 200 mg/kg) or its vehicle was orally administered everyday before the start of GaIN injection (400 mg/kg, ip) for two weeks and animal decapitated for 24 hrs after GaINinjected. The activities of serum enzymes, markers of liver function, were increased in the GaIN group compared to normal group and significantly lowered in the DWP-04 pretreated group than in the GaIN group. Hepatic lipid peroxide level and activities of phase 1 enzymes were significantly higher than those of GaIN group compared to normal group and lower in the DWP-04 pretreated group than in the GaIN group, and phase II enzyme activities in liver were lower in the GaIN group than in the normal group and were increased in the DWP-04 pretreated group than in the GaIN group. Total hepatic glutathione content and glutathione biosynthesis enzymes were lower in the GaIN group than in the normal group and were increased in the DWP-04 pretreated group than in the GaIN group. Therefore, the current results indicated that DWP-04 administration alleviated the GaIN-induced adverse effect through enhancing the antioxidant enzyme activities. 간기능 보호 작용이 있는 것으로 알려진 DDB, selenium과 glutathione의 혼합제제인 DWP-04의 간보호 작용을 검토할 목적으로 DWP-04를 실험동물에 경구로 투여하고서 D-galactosamine으로 간독성을 유발하여 혈액의 변동 및 간 조직에서의 활성산소 생성계 및 해독계의 활성에 미치는 영향을 관찰한 결과 GaIN의 단독투여는 대조군에 비하여 혈중 간 기능 지표효소 및 간 조직에서의 지질과산화의 함량이 현저히 증가하였으나, DWP-04의 전처리로 현저히 감소되었다. CaIN의 단독 투여로 활성산소의 생성계인 phase 1계의 효소가 현저히 증가하던 것이 DWP-04의 처리로 억제되었으며 해독계인 phase II계의 효소는 GaIN의 투여로 대조군에 비하여 억제되던 것이 DWP-04의 전처리로 정상군에는 미치지 않으나 유의성 있게 증가되었다. 간 조직중 glutathine의 함량은 CaIN의 투여로 현저히 억제되었으며 DWP-04의 투여로 증가하였는데 이러한 결과는 DWP-04의 투여로 glutathione peroxidase의 활성보다는 $\gamma-glutamylcysteine$ synthetase의 활성을 조절한 결과로 생각된다. 이상의 결과를 종합하여 볼 때 DWP-04의 투여는 활성산소의 생성 및 해독계를 조절하므로서 GaIN으로 인한 간손상을 보호하는 효과가 있는 것으로 사료된다.
지식정보인프라 구축 선도를 위한 과학기술정보 정책연구 및 조사.분석
이정희,Lee, Jeong-Hui 한국과학기술정보연구원 2003 지식정보인프라 Vol.12 No.-
현재 우리나라는 지식정보인프라 관련 정책, 제도, 계획 등을 종합조정하고 체계적으로 연계, 지원할 수 있는 국가단위의 조정체계가 확립되어 있지 못하다. 또한 관련 기관간의 정책협의, 조정을 위한 기능이 매우 미약하다. 또한 새롭게 변화하는 지식정보유통의 패러다임의 변화에 대한 공공부문의 대응이 선진국에 비해 매우 뒤처지고 있다. 이러한 점에서 지식정보인프라의 구축을 선도하기 위한 관련 선행연구 및 방법론 개발과 이를 통한 개념정립과 전략개발이 매우 시급하다고 하겠다.