Electrical Characteristics of AlxGa1-xN/GaN Heterostructure withIsoelectronic Al-Doped Channel for HFET Application

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.

세계화와 상호공존의 시민정신: 하퍼 리의 『앵무새 죽이기』

이정희 ( Chung Hee Lee ) 한국현대영미소설학회 2004 현대영미소설 Vol.11 No.1

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.

산업부산물을 이용하여 제조된 시멘트 클링커의 수용성 6가 크롬 용출 특성

이정희,추용식,송훈,이종규,Lee, Jung-Hui,Chu, Yong-Sik,Song, Hoon,Lee, Jong-Kyu 한국재료학회 2010 한국재료학회지 Vol.20 No.4

Since it was developed by Joseph Aspdin, cement has been a common construction materials up to the present time. However, there are trace constituents in cement clinker. One of the trace constituents included in cement clinker, chromium, has become prominent and highly noticed lately as a social issue both inside and outside of this country because it affects the human body negatively. The aim of the present study was to investigate the concentration of water-soluble hexavalent chromium in cement clinker by using industrial by-products. For that reason, raw materials were prepared to add different $SiO_2$, $Al_2O_3$, and $Fe_2O_3$ sources. After the raw materials such as the limestone, the sand and the clay, iron ore was pulverized and mixed, and the raw meal was burnt at about $1450^{\circ}C$ in a furnace with an oxidizing atmosphere. The part in the raw materials of the clinker was substituted with slag, sludge, etc. and this was used to manufacturing cement clinker. To investigate the water-soluble hexavalent chromium content in clinker, raw meal was prepared by changing the modulus, the type, and the content of clinker materials and tested concentrations of hexavalent chromium in the clinkers. To determine $Cr^{+6}$ formation of the clinker, tests were done with raw meals adding chromium by using different industrial by-products. Consequently because the chromium was to be included in the raw materials of the clinker, production of Portland cement clinker was included with the chromium. Also, the chromium was converted into hexavalent chromium in the burning process.

독서(讀書) 사고력(思考力) 계발(啓發)을 위한 독서지도(讀書指導)

이정희,Lee, Jeong-Hui 한국비블리아학회 1981 한국비블리아학회지 Vol.5 No.-

국내 쯔쯔가무시증의 감염자 분포와 유병자수 추정

이정희,박정수,Lee, Jung-Hee,Murshed, Sharwar,Park, Jeong-Soo 한국데이터정보과학회 2009 한국데이터정보과학회지 Vol.20 No.1

쯔쯔가무시증은 가을철 유행성 출혈열 중 80%이상을 차지하는 질병으로 1주에서 2주의 잠복기를 가지는 것으로 알려져 있다. 우리는 그 잠복기간의 확률분포가 감마분포라 가정하고 후향연산식을 이용하여, ${\hat{\mu}}=309.92$$, ${\hat{\sigma}}=14.154$인 정규분포를 따르는 감염자 분포를 추정하였다. 감염자는 10월에 집중적으로 분포하는 것으로 나타났다. 이러한 감염자 분포형태는 발병자 수가 11월동안 급격하게 증가하는 것에 기인한다. 본 연구에서 추정한 감염확률에 의해 미래의 유병자수를 계산한 결과 최대 1200명이었고 이는 매년 증가하는 발병자 수의 경향을 반영하지 못한 한계가 있다. 또한 우리는 전염병 모형으로 잘 알려져 있고 전염발전 단계간의 상호작용을 고려하는 SIRS 모형을 적용해 보았다. 모수는 초기값으로부터 잘 근사되어 수렴하는 값으로 추정하였다. Tsutsugamushi fever occupies more than 80% of total fall epidemic diseases and has an incubation period of 1 or 2 weeks as well. We have assumed that the incubation period distribution is gamma and therefore, reach an agreement that the infected distribution is normal with ${\hat{\mu}}=309.92$, ${\hat{\sigma}}=14.154$ by back calculation method. The infection cases are found severely large around the month of October. The infection case distribution demonstrates the incidence number increasing rapidly and progresses fast during the month of November. In this study, we have calculated the future prevalence number of maximum 1,200 people by inferred infection probability and incubation period distribution with some sort of limitation that the trend of increasing incidence number is not taking into an account. We considered the SIRS model which is also known as epidemic model, familiar to interaction between epidemiological classes. Our estimated parameters converged well with the initial parameter values.

A Study on the Incorporation of Sulfate-sulfur into Sulfur-containing Protein

이정희,전세열,신상주,Lee, Chung-Hee,Chun, Sea-Yull,Shinn, Sang-Joou 생화학분자생물학회 1971 한국생화학회지 Vol.4 No.1

고등동물에 있어서 황산염 유황의 단백질 전환은 소화관내에 기식하는 미생물의 도움으로만 가능한 것으로 알려져 있으나 본 실험에서는 고등 동물자체가 독자적으로 그와 같은 기능을 가졌는가를 구명하고져 반추초식덩물 아닌 토끼를 이용하여 표지된 황산염을 여러가지 방법으로 투여하여 그것이 단백질 합성에 이용됨을 구명하였고 토끼가 그와 같은 능력을 독자적으로 지녔음을 확인하였다. 각 기관에 있어서의 방사능 분포 상태도 아울러 조사하였다. Hinted by a symbiotic relationship between rumen microorganisms and host ruminant in utilization of inorganic sulfur compounds such as sodium sulfate and ammonium sulfate, an investigation was conducted to determine a similar symbiotic effect between ceacum microflora and host rabbit, for ammonium sulfate. Radioactivity of fecal emission was detected from the first day of administration but the radioactive compound(s) was not precipitated by barium chloride. A similar fact was found when the labelled sulfate-sulfur was administered by intraperitoneal injection. When urinary ejection was fractionated into 3 parts, namely, trichloroacetic acid precipitate, barium chloride precipitate and supernatant fractions, radioactivity was almost equally distributed into barium chloride precipitable and supernatant fractions with a minor beta-ray emission from TCA precipitated fraction. Radioactivity was detected in hairs of experimental subjects regardless the mode of drug administration. Our finding shows that angola rabbit possesses per se the capacity of such utilization independent to its ceacum microflora. Liver homogenates made 48 hours after the suspension of drug administrations showed no radioactive emission from its barium chloride precipitated fracton. Majorities of beta-ray emission was detected in the TCA precipitated fraction. A minor amount of count, detected from supernatant is interpreted as an evidence that in the liver, transformation of inorganic sulfate sulfur into other sulfur compound (s) is a pre-requisite for protein incorporation or other physiological or metabolic process. The results of in vitro test for microbial incorporation of labelled sulfate-sulfur show that when ceacum microfiora are incubated under anaerobic conditions the microorganisms can incorporate the labelled element into their cellular protein. The capacity of doing so seems to be increased by a prolonged exposure to or contact with such compound expressed otherwise, they can be trained to do so.

선천성 식도폐쇄및 기관식도루;수술치험 1례

이정희,최형호,Lee, Jeong-Hui,Choe, Hyeong-Ho 대한흉부심장혈관외과학회 1993 Journal of Chest Surgery (J Chest Surg) Vol.26 No.4

Esophageal atresia and tracheoesophageal fistula may occur as separate entities but usually occur in combination.The first report of esophageal atresia with tracheoesophageal fistula was done by Thomas Gibson in 1696.In1941, Haight and Towlseg performed the first successful primary repair,recently we were experienced a case of esophageal atresia with distal tracheoesophageal fistula in infant patient who presented the symptoms of dyspnea and vomiting.The operation was performed transpleurally through right 4th intercostal space.Patient tolerated all the operative procedure and recovered uneventflly.He was well-being without other problem.

흉막액의 임상적 고찰

이정희,임진수,Lee, Jeong-Hui,Im, Jin-Su 대한흉부심장혈관외과학회 1993 Journal of Chest Surgery (J Chest Surg) Vol.26 No.5

A clinical analysis of pleural effusion was done on 100 patients who were between 5 and 67 years old. The etiologic diagnosis of pleural effusion at the time of discharge were pulmonary tuberculosis in 38 cases[38%],pneumonia in 20 cases[20%],lung carcinoma in 16 cases[16%],liver cirrosis in 9 cases[9%],congestive heart failure in 4 cases[4%],nephrosis in 3 cases[3%],Meig,s syndrom in 3 cases[3%].liver abscess 2 cases[2%],pancreatitis in 1 cases[1%] and other metastatic malignancy in 4 cases[4%]. Their chief complaints was chest pain in 89 cases[89%],dyspnea in 74 cases[74%],coughing in 46 cases[46%], fever in 13 cases[13%],weakness in 12 cases[12%] and dizziness in 11 cases[11%].

음악요법이 상태불안과 활력징후에 미치는 효과

이정희,정현택,조은미,황옥남,Lee, Jung-Hee,Jung, Hyun-Teak,Kim, Eun-Mi,Hwang, Ok-Nam 한국재활간호학회 2006 재활간호학회지 Vol.9 No.1

Purpose: This study has tried to find out the effects of music therapy on anxiety of surgery patients during operation under regional anesthesia. In order to find out the effects, this research design was used nonequivalent control group non-synchronized design. Method: The subjects were the sixty inpatients under regional anesthesia in K hospital. They were assigned to two groups, thirty to the experimental group and thirty to control group. The data were collected using the Visual Analogue Scale(VAS) for State Anxiety and vital sign. The Experimental group received favorite music of the 4 different genre. The control group were inserted ear plug during operation. Data were analyzed by $X^2$-test, T-test, ANOVA and Repeated Measured ANOVA of the SPSS WIN (12.0) version program. Results: 1) Hypothesis 1: The hypothesis "that the figure for state anxiety of the experimental group provided with music therapy would be lower than that of the control group" was confirmed(F=0.27, P=0.01). 2) Hypothesis 2 : Three subordinating hypotheses were established in order to verify the hypothesis "that the figures for vital sings of the experimental group provided with such as music therapy would be lower than those of the control group." were rejected. Conclusion: Music therapy can be regarded as an effective nursing intervention that relieves operative anxiety of surgical patients under regional anesthesia.