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CVD 방법을 이용한 단결정 InSb 나노와이어의 성장과 Open/Close 시스템에서의 반응 메커니즘 연구
강은지,박이슬,이진석,Kang, Eun Ji,Park, Yi-Seul,Lee, Jin Seok 한국진공학회 2013 Applied Science and Convergence Technology Vol.22 No.6
화학적 증기증착(Chemical Vapor Deposition, CVD) 방법을 이용하여 단결정 Indium antimonide (InSb) 나노와이어를 $SiO_2$ wafer 위에 성장시켰으며, 성장된 InSb 나노와이어의 결정성과 조성비를 X-Ray Diffraction (XRD)과 Energy Dispersive x-ray Spectroscopy (EDS)의 측정을 통하여 확인하였다. 또한, 반응 source로 사용된 InSb 분말의 기상화(vaporization) 정도를 source container의 모형, 즉 open 및 close 시스템으로 변형하여 조절하였고 이렇게 성장된 InSb 나노와이어들의 구조적 특성을 주사전자현미경(Scaning Electron Microscopy, SEM)을 통하여 자세히 분석함으로써, 그들의 성장과정을 Vapor-Liquid-Solid (VLS) 및 Vapor-Solid (VS) 메커니즘으로 설명하였다. Open-boat를 사용하여 나노와이어를 성장시켰을 경우, close-boat 의 경우와 비교하여 합성된 나노와이어의 yield가 높았으며 나노와이어의 길이와 두께도 증가하는 현상이 관측되었다. 이러한 결과는, InSb source 의 기상화 정도가 close-boat에서 보다 open-boat에서 더욱 가속화되면서 공통적으로 일어나는 VLS 성장 이외에 VS 성장이 추가적으로 진행되어지기 때문으로 추측되어진다. 또한, 반응시간을 증가시켰을 때, 나노와이어의 두께가 증가하는 결과를 통하여 InSb 나노와이어의 성장에서 VS 메커니즘이 우세하게 작용하고 있음을 확인할 수 있었다. Single-crystalline InSb nanowire was synthesized on $SiO_2$ wafer via vapor-liquid-solid (VLS) mechanism using chemical vapor deposition method. According to the source container system (open or close) which contain InSb powder and $SiO_2$ wafer, the single-crystalline InSb nanowires have different growth mechanisms. Structural characterization of the InSb nanowires was examined by scanning electron microscope (SEM). Composition of the nanowires was investigated using x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDS). This study demonstrates that length and diameter of the InSb nanowires are long and thick using open-boat system by VLS and additional vapor-solid (VS) mechanisms, because open-boat system can carry a large amount of vapor-phase InSb precursor than close-boat system.
부두 설계 접안에너지를 고려한 선박 규모별 허용접안속도에 대한 분석
강은지(Eun-Ji Kang),이형탁(Hyeong-Tak Lee),조익순(Ik-Soon Cho) 한국연안방재학회 2021 한국연안방재학회지 Vol.8 No.4
The berthing velocity is the factor that has the greatest influence on the berthing energy. For the vessel to berth safely, it should not exceed the appropriate berthing velocity. In addition, when the vessel is berthing, it should be berthed with berthing energy smaller than the energy absorption of the fender. This study intends to derive the allowable berthing velocity by ship size considering the berthing capacity. When a small vessel berth, the allowable berthing velocity is greater than when a relatively large vessel berths. In this study, the extrapolated velocity is defined as the relative value of the ship’s berthing velocity when considering the ship s size and the berthing capacity. A regression equation for the allowable berthing velocity by ship size was derived by calculating the designed berthing energy for each fender performance. It was also verified whether any ships were exceeding the allowable berthing velocity by comparing it with the measured data for each jetty. In addition, the extrapolated velocity was proposed using the regression equation, and as a result of applying the measured data, 11 ships exceeded the designed velocity in jetty 1, but it was confirmed that all ships were safely berthed in jetty 2,3. Therefore, the target pier of this study was evaluated as a pier where ships can be berthed safely. A safer berthing velocity operation guideline can be suggested if the allowable berthing velocity by ship size is analyzed and utilized at various piers. Extrapolated velocity can also be used for risk analysis of berthing.
파우더 블라스팅을 이용한 사파이어 글라스의 가공성 평가
강은지(Eun Ji Kang),김정호(Jung Ho Kim),장호수(Ho Su Jang),박동삼(Dong Sam Park) 한국생산제조학회 2015 한국생산제조학회지 Vol.24 No.2
In this study, the machinability of sapphire glass is tested using the powder blasting method under various blasting conditions. The thickness and diameter of the sapphire glass samples were 0.4 mm and 50.8 mm (2 inch), respectively. The machined patterns from each sample were a circle, a square, and a rectangle. The powder we used was GC #400 and #800. The blasting pressures of the powders were 2, 4, and 6 bar. The scanning time of the nozzle was 20 and the scanning speeds of the nozzle were 80, 100, and 120 mm/s. Experimental results showed that machining depths increased in proportion to blasting pressure. The machining depth of GC #800 was much higher than that of GC #400, while surface roughness was worst with GC #400. These results imply that the blasting pressure and size of the blasting powder are the most important parameters for machining sapphire glass.
강은지(Eun-Ji Kang),민경탁(Kyung-Tak Min) 한국생산제조학회 2016 한국생산제조학회지 Vol.25 No.2
Ultrasonic metal welding, unlike the conventional welding techniques, does not require an external heat source, welding rod, or filler metal. Therefore, ultrasonic metal welding is not only economical but also environment-friendly, and hence, it has been receiving much attention. In ultrasonic welding, heat is generated because of the plastic deformation and the friction between both surfaces of the welded materials. It is important to identify the heat-affected zone by measuring the temperature generated at the weld. In this study, the effects of the welding pressure, welding time, and vibration amplitude on the temperature distribution in the weld were evaluated by performing a transient thermal analysis of the heat generated during ultrasonic metal welding. The experimental results indicated that the temperature of the weld tends to increase with the welding time and vibration amplitude. However, an increase in the pressure does not affect the temperature of the weld largely.
선행 제왕절개술 후 질식 분만의 성공인자 및 분만 진행 시간에 관한 연구
강은지 ( Eun Ji Kang ),이경아 ( Kyung A Lee ),박미혜 ( Mi Hye Park ),김영주 ( Young Ju Kim ),전선희 ( Sun Hee Chun ),안정자 ( Jung Ja Ahn ) 대한산부인과학회 2007 Obstetrics & Gynecology Science Vol.50 No.12
Objective: The purpose of this study was to determine which factors influence the likelihood of successful trial of labor, to evaluate the risks of VBAC and to evaluate the criteria of dystocia and the safety of VBAC. Methods: This retrospective study was peformed based on 61 pregnant women who succeeded VBAC, 37 VBAC failure women, 100 nulliparas and 100 multiparas. Results: In clinical characteristics, the parity, the number of previous cesarean section, gestational age, estimated fetal body weight by ultrasonography, and neonatal body weight had notable differences between the success and the failure group. In obstetric and historical factors, cervical effacement, dilation, and Bishop score at admission, spontaneous labor and method of induction of labor had differences. Among these factors, estimated fetal body weight by ultrasonography, cervical effacement and augmentation of labor using oxytocin were the most prognostic factors affecting the success of VBAC. In VBAC group, the duration of active-phase, second phase and total duration of labor were 313.5, 36.4 and 350.2 minutes, which were significantly shorter than nulliparas, but longer than multiparas. Conclusion: The trial of labor after cesarean section will decrease repeat operation, if it is performed under exact understanding of successful prognostic factors and the unique time length of labor. It will contribute to increase advantages for mother and economic benefits.
300 g 이상 자궁에서 수술 흉터를 통한 3-투관침 복강경하 질식 전자궁절제술
강은지 ( Eun Ji Kang ),문혜성 ( Hye Sung Moon ) 대한산부인과학회 2010 Obstetrics & Gynecology Science Vol.53 No.10
Objective: The purpose of this study is to examine the feasibility and safety of laparoscopically assisted vaginal hysterectomy (LAVH) using 3-trocar method through the previous operation scar for uterus weighing 300 g or more in the management of gynecologic disease. Methods: This retrospective study was peformed in 51 cases of LAVH with uterus weighing 300 g or more and with symptomatic benign gynecologic diseases (leiomyoma or adenomyosis). LAVH was performed through 3-trocar method (one trocar below the umbilicus, and two trocars at the point about 2 cm above and medial side of each anterior superior iliac spine, or at the bilateral edges of the previous operation scar). Results: Previous operation history was found in 17 cases (33.3%) and cesarean section was the most common. There was no difference in the age, body mass index, parity, length of operation, amount of blood loss, hemoglobin change, length of gas out, and hospital stay, rate of transfusion and complication between two groups divided by history of operation (P>0.05). Uterine weight in the group having operation history was lighter than that in group having not operation history (519.91±220.53 g and 381.24±70.63 g, respectively, P<0.05). Conclusion: LAVH for large uterus weighing 300 g or more using 3-trocar method through previous operation scar is safe and effective operation method, and may be an alternative to abdominal hysterectomy in selected patients.