Se/CS₂용액으로 처리한 n-GaAs 표면의 Photoreflectance 특성에 관한 연구

장광수,김인수,배인호,한병국,이정열 嶺南大學校 基礎科學硏究所 1997 基礎科學硏究 Vol.17 No.-

The surface of of n-GaAs(100) was treated using 1.5㎎/100ml solution of Se/CS₂. The passivation of the surface of this sample was investigated by photoreflectance(PR) experiment. After the surface treatment, the samples were annealed between 300 to 700 ℃ in a N₂atmosphere for 10 min. From the obtained Franz-Keldysh oscillations, we have evaluated the surface electric field(E?) and built-in voltage(V??). The density of surface states(Q??) and surface Fermi level(E??) of n-GaAs treated with CS₂and Se/CS₂solution were determined 1.78 ×10??㎝?? , 1.81×10?㎝? and 0.734 eV, 0.737 eV, respectively. After annealed at 600 ℃, These values were about 45% and 13% smaller than those in unannealed samples. It has found that the passivation of surface occured when the surface of the sample had been treated with Se/CS₂ solution and annealed from 400 to 600 ℃. This is ascribed to effects due to activation of elemental Se on the surface.

7학년 분자의 운동 단원에서 사회적 상호작용을 강조한 탐구실험 수업의 효과와 학생들의 인식

장진아,이경희,박소영,김동진,최병순,박국태 韓國敎員大學校 敎育硏究院 2009 敎員敎育 Vol.25 No.3

이 연구는 7학년 분자의 운동 단원에서 사회적 상호작용을 강조한 탐구실험 수업이 중학교 1학년 학생들의 개념 이해와 학업 성취도에 미치는 효과와 학생들의 인식을 알아보기 위한 것이다. 연구를 위하여 S시 소재 Y중학교 1학년 3개 학급 107명을 실험집단l파 실험집단2 및 통제집단으로 나누어, 실험집단l에는 학생간의 사회적 상호작용을 강조한 탐구실험 수엽을 실시하고, 실험집단2에는 교사와 학생간의 사회적 상호작용을 강조한 탐구실험 수업을 실시하였으며, 통제집단에는 전통적인 실험 수엽을 실시하였다. 수업 전과 후에 개념 이해도 검사를 하였으며, 성취도 검사와 인식 조사는 수업 후에 실시하였다. 연구 결과에 의하면, 실험집단1과 섣험집단2의 사회적 상호작용을 강조한 탐구싣험 수업이 통제집단의 전통적인 설험 수엽에 비하여 분자의 운동에 대한 개념 이해에 효과적이었다. 학업 성취도에 있어서는 사회적 상호작용을 강조한 실험집단1과 실험집단2의 학업 성취도 평균이 통제집단의 학업 성취도 평균에 비해 통계적으로 유의마하게 높았다. 실험집단1과 실험집단2의 학생들은 전반적으로 분자의 운동 단원에서 사회적 상호작용을 강조한 탐구실험 수업을 긍정적으로 인식하였다. 실험집단1에서 인지수준이 높은 학생들은 명확하게 답을 제시해 주는 것보다 동료와의 상호작용을 통해 시행착오를 거치면서 스스로의 힘으로 문제를 해결함으로써 자신감과 만족감을 느꼈다. 실험집단2에서 인지수준이 중하위인 학생들은 애매하고 시행착오적인 동료와의 상호작용보다는 교사와의 상호작용을 통해 직접적으로 답에 이르고 명확하게 개념 정리를 해주는 것을 선호하였다. The purpose of this study was to investigate effects of the inquiry experiment instruction emphasizing social interaction in the 7th grade motion of molecules unit on middle school students' scientific concept, achievement, and the perception of the instructions. For this study, 107 7th grade students were divided into three groups: the experimental group I, the experimental group 2, and the control group. The experimental group 1 were given inquiry experiment instruction emphasizing student-student interaction and the experimental group 2 were given inquiry experiment instruction emphasizing teacher-student interaction, while the control group were given traditional experiment instruction. They were all tested on their level of scientific concept understanding before and after the instruction and after the instruction they were given achievement test and surveyed on their perception. According to the result of this study, the inquiry experiment instruction emphasizing social interaction of experimental group 1 and 2 was more effective than the traditional experiment instruction of the control group in understanding the scientific concept of molecular motion, and the achievement level of experimental group 1 and 2 was significantly higher than the control group. Generally both students of group 1 and 2 were found to affirmatively perceive the inquiry experiment instruction emphasizing social interaction in the motion of molecules unit. Students of group 1 with high cognitive level were satisfied when they were able to independently solve problems by trial and error through student-student interaction than being given the exact answers. Meanwhile students of group 2 with middle to low cognitive level preferred the inquiry experiment instruction emphasizing teacher-student interaction that easily and cleary gives them the correct answer than student-student interaction which can be obscure and requires trial and error.

상추(Lactuca sativa L.)의 ACAT 억제 Diterpenoid, Phytol : 식용 식물자원으로부터 활성물질의 탐색 Development of Biologically Active Compound from Edible Plant Sources

장태오,방면호,송명종,홍윤희,김지영,정대균,배동근,권병목,김영국,이현선,김인호,백남인 한국농화학회 2003 Applied Biological Chemistry (Appl Biol Chem) Vol.46 No.1

순수티타늄 용접재의 피로크랙 진전거동에 관한 연구

최병기,국중민,장경천,권택용 朝鮮大學校 機械技術硏究所 2001 機械技術硏究 Vol.4 No.1

본 연구에서는 원자력 발전소의 터빈장치에 사용되는 순수티타늄 용접재의 피로수명과 크랙성장속도 등을 열영향부, 용접부 그리고 모재부를 각각 비교하기 위하여 시험편을 크게 용접된 4개의 시험편(Specimen1∼4 ; 초기노치에서 2∼3mm 떨어진 부분이 각각 H.A.Z, 본드부, 용접부, 모재부 등에 위치함)과 모재 시험편으로 나누어 피로시험을 수행한 결과 다음과 같은 결론을 얻을 수 있었다. 1) 순수티타늄 용접재 중 Specimen-2가 모재 시험편에 비해 피로수명이 약 700%로 가장 크게 나타났다. 2) 초기 크랙이 1mm로 성장하는데 걸리는 평균 크랙진전속도를 조사한 결과 Specimen-2가 모재에 비하여 약 30배로 가장 낮은 크랙진전속도를 나타내고 있었으며, 초기 크랙진전속도가 최종 파단 수명에 매우 큰 영향을 미치고 있음을 알 수 있었다. 3) 시험편 중 피로수명이 가장 큰 Specimen-2 시험편은 노치 선단으로부터 H.A.Z까지 거리가 약 6.7mm로 전체 파단길이의 약 25%를 차지하고 있었다. 4) da/dN과 ΔK를 고찰한 결과 용접으로 인해 생긴 두 개의 기울기로 인하여 Paris 법칙에 적용하기에는 부적당함을 알 수 있었다. In this study, Specimens were classified four welded specimens and a base metal to investigate fatigue life and crack growth rate of pure titanium welding materials, and Ti was used in turbine equipment of nuclear power generation, etc. The summarized results are as follows ; 1) Specimen-2 was bigger 712% than base metal, when it was compared with other welding materials. 2) As the result of specimens data. Specimen-2 crack Behavior rate was lower 30 times than base metal, and so total fracture life was very influenced by it 3) Notch tip of Specimen-2 was offsetted 6.7mm from boundary H.A.Z, and it formed 25% in total fracture length. 4) As the considering of da/dN and ΔK, Paris' law is incongruous in this study, because two inclines were on one date.

아미노산 투여가 운동중 싸이클선수의 젖산 및 심박수에 미치는 영향

이승국,유병렬,김문희,김완조,이선장 韓國體育大學校附屬 體育科學硏究所 1992 韓國體育大學校附屬 體育科學硏究所論文集 Vol.11 No.1

The purpose of the study was to determine whether a 15.6mg.Kg ??' does of glutamate given one hour prior to incremental exercise test would reduce the lactate formation. Five well trained cyclists served as subjects in this experiment which included a placebo and glutamate trial. The subjects initially work on treadmill 200m/min for 3 minutes and here increased the workload by 20m/min every 3minutes until exhaustion. Blood lactate were collected from finger-tip. Subjects in the glutamate trial showed significantly lower lactate formation during exercise then they did in the placebo trial. In both groups no significant difference was found on heart rate. During the recovery lactate and heart, rate were unaltered in either the glutamate or placebo trials. In summary, glutamate ingestion may reduce lactate formation resultly improvement of performance.

殘留應力을 考慮한 鎔接材의 疲勞龜裂 進展擧動에 關한 硏究

최병기,이을호,국중민,기준호,임선빈,정장만 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.1

The effect of welding residual stress on the initiation and propagation of fatigue crack is investigated so as to study the fatigue behavior in welding residual stress field. Especially, the relation between welding residual stress and fatigue crack opening behavior is investigated and the redistribution of residual stress as a fatigue crack propagates is examined. Following results are obtained. 1) In case of the load range is constant, as the stress ratio is changing to 0.1, 0.33, 0.5 the propagation life is constant but the growth life decreases. And than, when maximum load or minimum load is constant, as the stress ratio increases the growth life and propagation life increase. 2) The fatigue crack propagations rate da/dN appears to accelerate when the stress intensity factor range ΔK is less than 15MPa-m^1/2. 3) The residual stress that is appeared by welding decreases after cutting. 4) Fatigue crack propagation ratio is affected by tensional and compressible residual stress at the initial time, but it's similar to the original in the more than 20mm of crack length.

순수티타늄 용접재의 피로수명 예측에 관한 연구

최병기,국중민,장경천 朝鮮大學校 機械技術硏究所 2001 機械技術硏究 Vol.4 No.1

본 연구에서는 순수티타늄를 TIG용접하여 모재와 용접재의 피로시험을 수행하여 피로크랙 진전거동을 고찰하고, Nisitani가 제안한 역학적 변수에 의해 재료상수를 구한 후 그 적용성을 검토해 보았으며 얻어진 결과는 다음과 같다. 1. 동일한 하중비 조건에서 피로수명은 모재에 비해 Specimen-A, B, C는 각각 약 481%, 751%, 562% 크게 조사되었다. 2. 동일한 조건의 시험편에서 피로수명은 하중비 0.01에 비해 0.1과 0.2는 평균적으로 129%, 180% 크게 나타났다. 3. 모재 시험편를 제외한 용접재 시험편에서 피로크랙이 3mm 진전되는데 소모된 반복수는 전체피로수명의 약 90%를 차지하였으며, 이후에는 급속파단이 일어났다. 4. 본 재료에 실험으로부터 얻어진 재료상수를 이용하여 Nisitani의 피로크랙 전파속도 예측식에 적용하여 피로수명을 예측한 결과 노치의 위치 및 하중비에 관계없이 약 5% 내외의 낮은 오차를 보이며 잘 일치함을 알 수 있었다. In this study, the fatigue test was carried out with pure titanium and TIG welded material using in chemical plants and airplane frames etc.. The fatigue the propagation behavior and the fatigue life were investigated at 190% (400 kgf) of fatigue limit of base metal. Then, we compared and reviewed the result of experimented values and predicted values with the fatigue crack propagation equation reported by Nisitani in the present study. The summarized results are as follows; 1. The fatigue life of specimen B was showed to be about 751% longer than that of the base material at same load ratio. 2. The average fatigue lives at R=0.1 and 0.2 were respectably showed to be about 129% and 180% longer than that at R=0.01 at the same condition. 3. The fatigue life of the welded specimen was consumed about 90% of the whole fatigue life to grow 3mm fatigue crack length and then, the rupture was occurred rapidly. 4. The fatigue lives were predicted with the formula of the fatigue crack propagation, da/dN = C_2a^p_2, and compared with the experimented results, the results were shown good and in agreement within 5.0% error regardless of the notch position.

Ti 鎔接材의 機械的 特性 및 殘留應力의 分布에 關한 硏究

최병기,장경천,국중민,정장만,구남열 한국산업안전학회 2003 한국안전학회지 Vol.18 No.1

The objective of this paper was to investigate the welding characteristics according to the restraint condition, the pass number, and the shield gas quantity with titanium commonly using in power stations, aircrafts, ships, and so forth. The residual stress distribution was measured under restraint and nonrestraint welding conditions. The tensile strength and elongation of the 4 pass welded specimen were shown higher about 10% and 30% than those of the 7 pass welded specimen at the same welding conditions respectably. Also, the more shield gas quantity and the shorter natural cooling time, the higher tensile strength and the lower elongation.

개에서 이중 결찰법을 통한 동맥관 개존증의 완치 예

윤헌영,정순욱,박희명,박철,정만복,김준영,한현정,황민,노병국,박상혁,장하영,박정윤 한국임상수의학회 2004 한국임상수의학회지 Vol.21 No.1

A ten months old, female Yorkshire terrier weighing 2.88 kg referred to veterinary teaching hospital of college of veterinary medicine, Konkuk University because of syncope, cough and dyspnea. First hematological and serum chemical test revealed thrombocytopenia, mild anemia, and increase of concentration of ALP (195 U/L). On 57 days later, second hematological and serum chemical test revealed polycythemia, increase of concentration of ALP (211 U/L), and Tchol (387 mg/dl). Right atrium enlargement, main pulmonary artery bulge and cardiomegaly (VHS = 11.5) were observed in radiographic findings. Ultrasonographic images showed both right and left ventricular dilation and turbulent flow between the descending aorta and the main pulmonary artery in color Doppler imaging. ECG showed left ventricular enlargement, SA block, and electrical alternant. Thoracotomy was performed through left fourth intercostal incision under isoflurane anesthesia. Patent ductus arteriosus was double ligated with 1-0 silk. Cough and dyspnea disappeared on 5 days after operation. Turbulent flow was not found in color doppler imaging of ultrasonography on 10 days after operation. Ten months later after the operation, syncope could not exist any more.

Association between Matrix Metalloproteinase-1 (MMP-1), IL4R Promoter Polymorphism and Hepatocellular Carcinoma

( Byung Kuk Jang ),( Kyung Sik Park ),( Kwang Bum Cho ),( Woo Jin Chung ),( Jae Hoon Bae ),( Mi Young Lee ),( Dong Hoon Shin ),( Jae Seok Hwang ) 대한간학회 2004 Clinical and Molecular Hepatology(대한간학회지) Vol.10 No.3(S)