• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
• /
• pp.248-248
• /
• 1999

현재 반도체 공정에서 사용하는 건식식각 공정은 고밀도 프라즈마를 사용한 플라즈마 장비를 사용하는 경향이 증대되고 있으며 이와 같은 고밀도 플라즈마 장비의 사용은 반도체 소자의 최소 선폭(CD)이 deep sub-micron으로 감소하고 반면 실리콘 웨이퍼의 크기는 8인치 직경이상으로 증가하여 가고 있어서 그 필요성이 더욱 더 증가되고 있다. 특히 TFT-LCD를 비롯한 PDP, 그리고 FED 등과 같은 여러 가지 형태의 평판 디스플레이의 제조공정에 있어서도 실리콘 기판에 비하여 대면적의 기판을 이용하고 또한 사각형 형태의 시편공정이 요구되므로 평판 디스플레이에서도 고밀도의 균일한 플라즈마 유지가 중요하다. 따라서, 본 실험에서는 여러 가지 형태의 영구자석 및 전자석의 세기 및 배열이 유도결합형 플라즈마에 미치는 효과(plasma&etch uniformity, etch rate, etc.)를 살펴보기 위해서, 유도결합형 플라즈마 chamber(210mm$\times$210mm) 내부에 magnetic cusping을 위한 영구자석용 하우스를 제작하여 표면에서 3000Gauss의 자장세기를 갖는 소형영구자석을 부착하였으며,외벽에는 chamber와 같이 사각형태로 40회 감겨진 50cm$\times$50cm 의 크기로 chamber 상하에 1개씩 Helmholtz 코일 형태로 설치하였다. 식각가스로는 Cl2, HBr, 그리고 BCl3 gas를 이용하여 axial magnet과 multidipole magnet 유무에 따른 반응성 gas의 polysilicon 식각특성을 살펴보았으며, 또한 electrostatic probe(ESP, Hiden Analytic미)를 이용하여 이들 반응성 gas에 대한 magnetically enhanced inductively coupled plasma의 특성분석을 수행하였따. Cl2, HBr, BCl3의 반응성 식각가스 조합을 이용하여 polysilicon의 식각속도 및 식각선택도를 관찰한 결과, 어떠한 자장도 가하지 않은 경우에 비해 gas의 분해율이 가장 높은 영구자석과 전자석의 조합에서 가장 높은 식각도가 관찰되었다. 특히 pure Cl2 플라즈마의 경우, Axial 방향의 전자석만을 가한 경우 식각속도에 있어서는 큰 증가를 보였으나, 식각균일도(식각균일도:8.8%)는 다소 감소하였으며, Axial 방향의 전자석과 영구자석을 조합한 경우 가장 높은 식각속도를 얻었으며, 식각균일도는 Axial 방향의 전자석만을 사용하였을 경우와 비교하여 향상되었다.

• Korean Journal of Ichthyology
• /
• 제27권3호
• /
• pp.228-232
• /
• 2015

The structure of the ventricle in the heart of Hypomesus nipponensis was investigated by light and scanning electron microscope. The heart consisted of four consecutive chambers, the sinus venosus, atrium, ventricle and bulbus arteriosus. The wall of the ventricle was divided into endocardium, myocardium, subepicardium and epicardium. The valves were observed in the artrioventricular and bulboventricular junctions. The ventricular myocardium was an entirely spongy without coronary vessels. The trabecular network was formed with lumina included a central lumen and the trabecula was cylindrical shape. Collagen distribution was apparent in the subepicardium, artrioventricular valve and bulboventricular valve. But in the trabeculae, collagen distribution was observed partly in the base of the ventricle. Especially, the endocardial bridges were observed between trabeculae. These results might be considered that the structure of the ventricle in the heart of pond smelt is adapted to sedentary habit associated with its habitat and lifestyle.

• Journal of the Korean Institute of Gas
• /
• 제5권3호
• /
• pp.73-79
• /
• 2001

The corner protection which is consist of insulation and $9\%$ nickel liner is designed to mitigate the high hoop tension at the corner of LNG storage tank by LNG leakage. So the design loads depend on thermal and liquid pressure from leaked LNG In this paper design conditions are suggested as operating, major and minor leak conditions. And in order to check integrity of comer protection for the design conditions by appendix 4 in ASME section VIII div.2, acceptability checking process that have stress categorization and finite element analysis is explained.

• Journal of the Korean Institute of Gas
• /
• 제17권2호
• /
• pp.1-8
• /
• 2013

In this study, 120 cases of damage due to ground subsidence of city gas pipeline which is hanging on apartment outer wall were investigated. From the survey results, it was determined to be approximately 100m~200mm ground subsidence occurred and at severe damage, pipeline was cut and the gap was about 50mm between two cut pipeline. Device for measuring the amount of deformation of standing gas pipeline was designed and fabricated. And installed it on apartment outer wall for measuring the deformation due to ground subsidence, after 5 months measurement the amount of ground subsidence was measured to 1.3mm. Stress assessment was conducted based on results of ground subsidence occurred on standing gas pipeline.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• 제33권3호
• /
• pp.184-191
• /
• 2000

Gametogenesis and the reproductive cycle of the marsh clam, Corbicula leana(Prime} were investigated monthly Hyongsan estuary, Korea from January to December 1998 by histological observation. C. leana had separate sexes, and oviparous. The gonads were located between the sub-region of mid-intestinal gland in visceral cavity and reticular cennective tissue. The ovary and testis were composed of a number of ovarian and testicular tubules, respectively, Mature oocytes were characterized by germinal vesicles with nucleoli and their sizes ranged $70\;to\;80{\mu}m$ in diameter. A number of mesenchymal tissues and pigment granular cells were distributed in the growing oocytes and spermatocytes during early developmental stages. With the further development of gonad, these tissuse and cells gradually disappeared. The monthly changes in the fatness index were closely related to reproductive cycle. Minimun size for sexual maturity was reached over 10.0 mm in shell length. The reproductive cycle could be classified into 6 stages : multiplicative (March to April): early growing and growing (May to June), mature (July to August), spent (September), degenerative (October) and recovery (November to February).

• Journal of the Korean Institute of Intelligent Systems
• /
• 제26권5호
• /
• pp.383-389
• /
• 2016

In this paper, we present the hull blasting machine with vision-based weld bead recognition device for cleaning shipment exterior wall. The purpose of this study is to introduce the mechanism design of the high efficiency hull blasting machine using the vision system to recognize the weld bead. Therefore, we have developed a robot mechanism and drive controller system of the hull blasting robot. And hull blasting characteristics such as the climbing mechanism, vision system, remote controller and CAN have been discussed and compared with the experimental data. The hull blasting robots are able to remove rust or paint at anchor, so the re-docking is unnecessary. Therefore, this can save time and cost of undergoing re-docking process and build more vessels instead. The robot uses sensors to navigate safely around the hull and has a filter system to collect the fouling removed. We have completed a pilot test of the robot and demonstrated the drive control and CAN communication performance.

• Transactions of the Korean Society of Mechanical Engineers
• /
• 제16권9호
• /
• pp.1760-1769
• /
• 1992

An experimental study of thermal transport from a uniformly heated pipe to a pulsating flow has been carried out. Surface of the pipe is imposed with constant heat flux providing by electric heating band. This problem is of particular interest in the design of Stirling engine heat exchangers and in understanding the blood flow in the aorta. Temporal Variatiens of temperature and pressure inside the circular pipe are measured. The dependence of temperature distributions and heat transfer rate on the mean flow rate in the pipe and on the pulsating frequency is investigated in detail. The experimental results indicate that the measured temporal variations of temperature and pressure become nearly sinusoidal The amplitude of temperature variation near the pipe wall is much more substantial than that in core of the pipe. It is also found that the heat transfer rate is increased significantly as the frequency of the pulsating pressure is increased or the mean flow rate in a pipe is increased. The results obtained are also compared with those for non-pulsating flow circumstance.

• Proceedings of the Korea Water Resources Association Conference
• /
• 한국수자원학회 2011년도 학술발표회
• /
• pp.177-177
• /
• 2011

환형수조는 점착성 퇴적물의 침/퇴적실험을 위한 실험장치로서, 수조내부의 수면과 접하여 회전하는 상부링(top ring)의 마찰력에 의해 흐름이 생성되며, 시간의 제약없이 흐름조건을 동일하게 만들 수 있다는 큰 장점을 갖는다. 그러나 환형수조는 원주유속의 속도차이 및 원심력으로 인한 2차 순환류가 형성되어 바닥전단응력이 불균일해지는 단점을 가지고 있으며, 이러한 이유로 인하여 환형수조를 이용한 침/퇴적실험 수행시 수조의 외벽부근에서 더 큰 침식이 발생한다. 따라서, 2차 순환류의 발생을 줄이고 바닥전단응력의 분포를 균등하게 하기 위해 양방향 회전(환형수조의 몸체를 상부링의 회전방향과 반대방향으로 회전)이 가능한 환형수조가 고안되었는데, 이러한 방법으로 2차 순환류의 크기를 저감시키고, 바닥전단응력을 균일하게 만들 수 있다. 한편, 환형수조의 양방향 회전(counter-rotation)은 현장용 환형수조에는 적용될 수 없는 단점을 갖는다. 현장실험에서는 바닥면이 없는 현장용 환형수조를 해저면에 거치시켜 자연상태의 비교란 퇴적물 시료를 저면으로 형성시키는데, 바닥면이 존재하지 않는 환형수조 본체는 회전시킬 수 없으므로 양방향 회전을 통한 2차 순환류의 저감 및 바닥전단응력 균일화의 효과를 기대할 수 없다. 이러한 이유로 환형수조의 양방향 회전은 단지 실내실험용 환형수조에만 적용된다. 이에 본 연구에서는 환형수조 본체를 회전시키지 않고 수조의 측벽과 상부링의 각도 조절을 통해 수조단면의 형상을 변화시켜 2차 순환류를 저감시키고 바닥전단응력을 균등하게 하는 방법에 대한 연구가 수행되었다. 이 방법은 본체의 회전이 필요 없으므로 현장용 환형수조에 적용될 수 있을 뿐만 아니라, 실험장치의 구조가 단순해져 실험장치의 제작비가 절감될 수 있다. 또한 원주속도에 수직한 단면에서 속도구배가 감소되어 2차 순환류가 저감됨과 동시에 바닥전단응력이 균등하게 됨으로서 양방향 회전시와 동일한 효과가 얻어질 수 있을 것으로 예상된다.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2002년도 생물공학의 동향 (X)
• /
• pp.112-115
• /
• 2002

The green colonial algae Botryococcus braunii is characterized by unusual high hydrocarbon contents, ranging from 15 to 75% of dry weight, as long-chain unsaturated hydrocarbons. In two-phase bubble column using various organic solvents, poor recovery 08 - 32%) of hydrocarbon seems to be caused by insufficient mixing between two phases, which was operated using only aeration on the narrow interface between hydrophobic solvent and cell suspension. In addition, hydrocarbon was entrapped tightly in cell-matrix (formed by exopolysaccharide) of algal colony, which make difficult to extract using two-phase system. To improve recovery efficiency, mixed-solvent of extractive solvent (octane) and biocompatible solvent (octane) was tested in two-phase column for in situ extraction. In two-phase extraction culture using mixed-solvent, the algal growth was intensely inhibited even at low concentration of polar octanol solvent. the hydrocarbon recovery in two-stage cell-recycle extraction showed a 2.9 fold increase (57%) over that in two-phase extraction. Up to 60 % of hydrocarbon could be recovered without serious cell-damage in the case of downstream separation for 6 h at the high recycle flow rate using this process after batch culture.

• Journal of the Korean Geographical Society
• /
• 제46권4호
• /
• pp.425-441
• /
• 2011

Ridge traversing trail in Mount Jiri National Park is classified as flat, gully-like, unilateral, and asymmetric bilateral, paths based on a location and gradient of paths. These types are interchangeable due to a drainage condition of trail surfaces. Using a rapid survey, the trail is 135.9 cm wide, 23.6 cm deep and $5.1^{\circ}$ in a gradient, respectively. All treads have been compacted due to human trampling. The path width is affected by a slope aspect and a distribution of Sasa borealis. An asymmetric path is wider than a symmetric path. A soil erosion rate is equivalent to $68.9cm^2/year$ for the period from 1960 to 2009, suggesting that the trail has been widened 2.7 cm/year and the tread lowered 0.4 cm/year. Trampling and needle ice action combined with rainwash induced by a pipeflow are dominant erosion processes contributing to the trail expansion.