n-GaAs 구조에서의 ArF excimer laser annealing에 따른 Photoreflectance 특성 연구

김기홍,유재인,심준형,배인호,임진환,김진희,유재용,Kim, Ki-Hong,Yu, Jae-In,Sim, Jun-Hyoung,Bae, In-Ho,Lim, Jin-Hwan,Kim, Jin-Hi,Yu, Jae-Yong 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.2

n-GaAs의 시료를 furnace annealing 처리와 laser annealing 처리를 한 후, PR 방법으로 비교 조사하였다. 시료는 Furnace annealing을 5 분간 $400{\sim}800^{\circ}C$에서 처리한 시료와 ArF excimer laser($30{\sim}50\;W$)로 5 분간 Laser annealing 처리 한 시료로 준비하였다. Furnace로 annealing을 한 경우에 주 신호(정점)는 1.43 eV에서 관측되었는데 비해 laser로 annealing 한 샘플은 1.42 eV로 0.01 eV가 더 작게 관측되었다. 이는 laser annealing이 furnace annealing 보다 표면과 내면에서 일어나는 열처리 효과가 더 고르게 일어나가 때문이다. We investigated variation of the photoreflectance(PR) signals for n-GaAs furnace and laser annealed. The samples were annealed by using ArF excimer laser(5 min, $30{\sim}50\;W$) and furnace(5 min $400{\sim}700^{\circ}C$). The PR signals(top point) measured from the ArF excimer laser annealed sample showed 1.42 eV and furnace annealed sample showed 1.43 eV. This result is ArF excimer laser annealed sample was uniform annealed surface and inter state.

탄소섬유/고인성 에폭시 수지 적층판의 모드Ⅱ 파괴인성 평가

심재기,양인영,김영남,조규재,김지훈 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.1

본 연구에서는 탄소섬유/고인성 EPOXY의 일방향 CFRP적층시험편에 대해 정적 ENF 시험 및 스프릿홉킨손봉법에 의한 동적 ENF시험을 하여 일방향 CFRP 적층판의 모드Ⅱ층간파괴인성치를 측정된 하중응답, 반력봉 반력의 J-적분과 시험편의 변위해석을 통하여 평가하였다 실험결과, 준정적 변위속도 δ = 5 × 10 근방에서 하중 최저점에서부터 하중의 진동이 발생하기 시작함을 알 수 있었으며, 또한 최저 측정점에서 하중점 변위속도의 증가와 더불어 동적 층간파괴 인성치가 증가함을 알 수 있었다. In this paper, an investigation was performed on the dynamic interlaminar fracture toughness of CFRP(carbon fiber reinforced plastics) composite laminates. Composite laminates used in this experimentation are CF/high toughness Epoxy Resin composite laminated plates. In the experiments, Split Hopkinson's Bar(SHPE) test was applied to dynamic and notched flexure test. The mode Ⅱ fracture toughness of each unidirectional CFRP was estimated by the analyzed deflection of the specimen and J-integral with the measured impulsive load and reactions at the supported points. As an experimental results, Loading vibrations are generated when quasi-static displacement velocity, δ becomes 5×10 from the lowest loading point. It is thought that the dynamic fracture toughness of specimens(CF/EPOXY) with the increase of displacement velocity becomes a little greater at a measuring point within the range of measurement.

개의 신장 및 요관결석증 1례

심재현,정성목,신상태,조종기 충남대학교 수의과대학 동물의과학연구소 2004 動物醫科學硏究誌 Vol.12 No.-

A 1-year 2-months old Shih-tzu dog was presented with history of abdominal distention and tenderness, vomiting, anorexia and constipation. On physical and laboratory examination, WBC count was severely elevated (48.38×10^(6)/μl). On radiographs and ultrasonographs, dilation of right renal pelvis and right proximal ureter and renal calculi of both kidney were shown. It was diagnosed as a infectious renal and ureteral urolithiasis. Pyelolithotomy of right kidney was undertaken. After operation, normal urination was observed and appetite was recovered. By ultrasonographic examination, hyperechoic mass was not observed in the right kidney.

곡률을 갖는 복합적층쉘의 에너지 흡수특성 및 충격손상

황재중,이철우,김영남,심재기,양인영 朝鮮大學校 機械技術硏究所 2003 機械技術硏究 Vol.6 No.1

본 연구에서는 CFRP 복합재 적층쉘 형상의 구조부재 설계 시 고려해야 할 고강성, 고강도 측면을 중점으로 2개의 계면수를 갖는 직교이방성 CFRP 복합재 적층쉘에 대하여 횡방향 하중 정적실험 및 ANSYS를 이용한 유한요소해석을 행하여 직교이방성 적층쉘의 역학적 특성을 실험 및 유한해석을 통하여 고찰하고자 한다. 또한, 곡률의 크기에 따른 CFRP 적층쉘의 충격특성을 정량적으로 평가하기 위하여 충격속도의 크기에 따른 에너지 흡수특성 및 충격손상기구를 규명하고자 한다. 정적실험의 경우보다 FEM해석의 경우가 약 25%∼35% 정도 높게 나타났고 충격에너지가 증가할수록 박리현상은 선형적으로 증가하였으며, 같은 충격에너지 범위라 할지라도 곡률 반경이 증가할수록 흡수에너지는 증가하였다. Centering on high rigidity and intensity 'to be considered in the design of sub-materials of the perpendicular anisotropic CFRP composite material laminate shells with two interlaminar number, this study performed width-direction load static experiments and the finite element method using the ANSYS to examine dynamic properties of perpendicular anisotropic laminate shells. Also, to evaluate the impact property of the CFRP laminate shell according to size of curvature quantitatively, it was to identify energy absorption and impact damage instruments according to size of impact speed. Absorption energy of the .FEM analysis was about 25-35% higher than that of the static experiment and the more impact energy increased, the more damage area increased linearly. Despite of the same impact energy range, the more curvature radius increased, the mere absorption energy.

3차원 레이저 진동 측정기를 이용한 초고속 진공청소기 모터의 진동특성분석

김재열,김우진,심재기,김영석 한국공작기계학회 2004 한국공작기계학회 추계학술대회논문집 Vol.2004 No.-

Recently technology resulted in highly efficient and multiple-functional electric appliances considering environmental problems. One of the environmental problems is noise of a product in respect to its function. A vacuum cleaner is an essential electric appliance in our daily lives. However, severe noise resulted from high motor speed for improving the function of the appliance is a nuisance for the user. This noise is caused by vibration from various parts of the appliance and fluid noise during a series of intake and exhaust processes while rotating the impeller connected to the axle at a high speed of the fan motor inside the vacuum cleaner rotating around 30,000-35,000 rpm. Despite the fact that many researchers conducted studies on reducing the noise level of the fan motor in a vacuum cleaner, only few studies have been conducted considering both the theoretical and experimental aspects using fluid analysis by measuring vibration and noise. Moreover, there has not been a study that accurately compared major noise data obtained considering both of the aspects. In this study, both aspects were considered by considering the following experimental and theoretical methods to verify the major causes of noise from the fan motor in a vacuum cleaner.

경피적 겸자 정복 및 골수강내 금속핀 고정을 이용한 쇄골 골절의 치료

홍기도,하성식,정남식,심재천,김경호 대한골절학회 2004 대한골절학회지 Vol.17 No.4

목적 : 경피적 겸자 정복 및 골수강내 금속판 고정술을 이용한 쇄골 간부 골절의 치료에 대해 유용성을 규명해 보고자 하였다. 대상 및 방법 : 2002년 1월부터 2003년 7월까지 본원에서 쇄골 간부 골절 환자 중 신경 및 혈관 손상이 없었고, 골절의 분쇄상이 비교적 적었던 총 16례를 대상으로 겸자를 이용한 경피적 정복 후에 골수강에 금속판을 삽입하여 고정하였다. 술 후 유합 정도 및 결과를 임상적, 방사선학적으로 분석하였다. 결과 : 방사선학적으로 골유합을 보인 경우가 총 15례였으며, 술 후 평균 9.1주에 유합 소견을 관찰하였다, 임상적으로 강 등의 기준에 따라 구분한 결과, 우수 이상이 14례로 나타났다. 1례에서 1주 만에 K-강선의 내측전위로 골절부위가 재전위되어 관혈적 정복 및 금속판 내 고정을 시행한 이외에 다른 주요 합병증은 없었다. 결론 : 저자들의 방법은 수술시간이 짧고 간단하며, 연부조직의 추가적 손상이 적어 골유합율이 높고, 수술 반흔을 남기지 않아 수술적 적응을 신중히 고려한다면 쇄골 간부 골절의 치료법의 하나로 유용할 것으로 사료된다. Purpose: To investigate the utility of surgical treatment of clavicle shan fracture using a percutaneous towel clip reduction and intramedullary fixation. Materials and Methods : This study was conducted for total 16 case of patients who had no neurovascular injury and a few comminuted bone fragment among patients with clavicle shaft fracture from January 2002 to July 2003. The method of operation was percutaneous towel clip reduction and intramedullary fixation. The clinical and radiological results were evaluated. Results : Radiologically, 15 cases showed bone unions and the avenge time was 9.1 weeks. According to Kang's criteria clinically, there were 14 cases which were more than an excellence. One case substituted open reduction and nailing fixation due to a medial migration of K-wire and re-displacement of fracture even in 1 week. However, there wasn't any other major complication. Conclusion : Due to its having no additional injury to soft tissues, no scar formations, and its short operation time, percutaneous towel clip reduction and intramedullary fixation will be very useful as one of the treatments of clavicular shaft fracture if it follows correct surgical indications.

초음파 검사 기반의 용접결함 분류성능 개선에 관한 연구

김재열,윤성운,김창현,송경석,양동조,--,-- 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-

In this study, we made a comparative study of backpropagation neural network and probabilistic neural network and bayesian classifier and perceptron as shape recognition algorithm of welding flaws. For this purpose, variables are applied the same to four algorithms. Here, feature variable is composed of time domain signal itself and frequency domain signal itself. Through this process, we comfirmed advantages/disadvantages of four algorithms and identified application methods of four algorithms.

오스템퍼링한 구상흑연주철(ADI)의 드릴 가공시 경도 및 현미경조직변화에 관한 연구

조규재,장우양,심재기,홍성오,김선진 한국공작기계학회 1999 한국생산제조학회지 Vol.8 No.1

This paper was carried out to know the influence of advanced austempered ductile cast iron (ADI) on the tool life and mechanical properties of drilling machinability. For manufactured method of ADI, the spheroidal graphite cast iron were austenized at 900℃ for 1 hour and then austempered for 2 hour at 370℃ in the salt bath. And interrelationship has been investigated between tool life and mechanical characteristics of specimen material on drilling condition when the ordinary and step-feed drilling are carried out to drill holes of specimens. Tensile strength and hardness of ADI decrease and elongation of ADI increases with the increase austempered temperature. It is known that about 2 times of tool life in the case of step-feed decreases compared with ordinary feed due to the high hardness of ADI and hardness ascribed to the fact that retained austenite beame to martensite state due to cutting heat in drilling. Under the constant feed rate 0.1㎜/rev relation between hardness and length of end tip after drilling can be formularized to Hv=788.46L^-0.096 for the cutting speed 6.1m/min.

7FA G/T 코팅층 크랙 평가를 위한 IR카메라 활용

김재열,심재기,최철준,송경석 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-

In this investigation, we evaluated diagnoses of a defect concerning coating of land-base gas turbine using infrared thermography camera. In this camera method has a strong point which is able to save time and costs compared with former method. Because it can be long field acquire temperature distribution by using non-contact method. But it has a week point that method applies thermal load about inspection sample. Presently, Method used widely in detection of crack is ultrasonic inspection. But this method, There is problem in application in place that uneven surface. In order to check cracks on a blade coating of a gas turbine, a part with cracks in a waste blade disposed after having been used in the field was extracted to produce a sample. So we apply the method by a infrared thermography camerato the produced sample, the sample was heated by means of a halogen lamp. In this paper, we want to describe production of land-base turbine sample, a method of applying thermal load at produced sample, infrared thermography camera technique, an analysis technique of thermography, a defect analysis of coating of land-base gas turbine blades.

소아 대퇴골 간부 골절에대한 Nancy정 고정술

홍기도,하성식,정남식,심재천,김재영 대한골절학회 2003 대한골절학회지 Vol.16 No.4