• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1995.06b
• /
• pp.14-20
• /
• 1995

본 연구에서는 압축기내의 이상류, 즉 냉매와 오일의 혼합상태라 하는 특수한 환경에서 하중을 지지하고 있는 상하부 베어링에서의 윤활특성파악을 위하여, 압축기의 동역학해석 및 레이놀즈방정식을 이용, 베어링의 축심궤적을 수치해석에 의해 결정하고, 여러 운전조건에서 축심궤적의 변화를 살펴 보았다. 또한, 실험에서는 실제의 냉방시스템에 사용되고 있는 로터리 압축기의 축심궤적을 갭-센서를 이용하여 파악, 그 결과를 나타냈다.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 1996.03a
• /
• pp.95-106
• /
• 1996

건물발파해체 설계 및 시공에 있어서 중요한 공정의 하나는 불안정성을 유도하도록 실시하는 건물의 주요 지지부 기둥에 대한 발파이다. 이와 관련된 요소기술로는 기둥단면에 따라 천공패턴을 결정하고 적정장약량을 산정하는 것과 폭파시 파괴된 파편의 비산에 대한 방호기술을 들 수 있다. 비산은 인접건물에 대한 피해와 인명사고들을 유발할 수 있으므로 사전에 철저한 대책이 강구되어야 할 대상이다. (중략)

• 대한예방의학회:학술대회논문집
• /
• 1999.10a
• /
• pp.159-160
• /
• 1999

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.10
• /
• pp.791-797
• /
• 2018

In this work, the high-altitude environment simulation study was carried out at an altitude of 65 km exceeding Mach number of 6 after the launch of Korean Space Launch Vehicle using a shock tunnel. To minimize the flow disturbance due to the strut support of test model as much as possible, a few different types of strut configurations were considered. Using the configuration with minimum disturbance, the high-altitude environment simulation experiment including a propulsion system with a single-plume, was conducted. From the thruster test through flow visualization, not only a shockwave pattern, but a general flow-field pattern from the mutual interaction between the exhaust plume and the free-stream undisturbed flow, was experimentally observed. The comparison with the computation fluid dynamic(CFD) results, showed a good agreement in the forebody whereas in the afterbody and the nozzle the disagreement was about ${\pm}7%$ due to unwanted shockwave formation emanated from the nozzle-exit.

• Geotechnical Engineering
• /
• v.11 no.4
• /
• pp.5-12
• /
• 1995

Although the pile Load test provides various informations to predict the bearing capacity of a pile, it has a considerable difficulty of requiring a large amount of weight to enable the test pile to be loaded sufficiently until the yielding or ultimate load is obtained. Many graphical and mathematical methods have been attempted to estimate the bearing capacity from the result of a vertical load test without loading to failure. In the previous work an analytical method to estimate the failure load using the maxi mum curvature which was based on the Southwell's theory was presented by the author. The failure load, as proposed by Crowther, should be defined as the load at which the predefined that criteria are exceeded. The allowable loads by Davisson's method and DIN 4014 were compared with the loads of piles using the maximum curvature, and this paper proposed the allowable load in which the safety factor of the maximum curvature was 2.5. As a result of study, it was reasonable to conclude that the allowable load determined by the maximum curvature method could estimate the vertical bearing capacity from the pile load test without loading to failure.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.36 no.4
• /
• pp.295-299
• /
• 2016

Residual foreign objects at the secondary side (top of the tubesheet and tube support plates) of a steam generator are likely to cause a leak by causing wear in the tube. The extent of wear is significantly affected by the material, shape, and size of the foreign object, and the corrosion properties of the tube. The presence of foreign objects at the top of the tubesheet and tube support plates has been identified using remote visual inspection methods such as the foreign object search and retrieval and eddy current test (ECT). The detection of the residual foreign object at the secondary side of a steam generator has limitations that depend on the material properties and the condition of contact with the tube. In this study, which is vertical and horizontal from the upper tubesheet, the corresponding bobbin ECT signals were collected and analyzed to measure its ability to detect foreign objects.

• Journal of the Korean Society for information Management
• /
• v.24 no.1 s.63
• /
• pp.251-271
• /
• 2007

This paper studies the problem of classifying documents with labeled and unlabeled learning data, especially with regards to using document similarity features. The problem of using unlabeled data is practically important because in many information systems obtaining training labels is expensive, while large quantities of unlabeled documents are readily available. There are two steps In general semi-supervised learning algorithm. First, it trains a classifier using the available labeled documents, and classifies the unlabeled documents. Then, it trains a new classifier using all the training documents which were labeled either manually or automatically. We suggested two types of semi-supervised learning algorithm with regards to using document similarity features. The one is one step semi-supervised learning which is using unlabeled documents only to generate document similarity features. And the other is two step semi-supervised learning which is using unlabeled documents as learning examples as well as similarity features. Experimental results, obtained using support vector machines and naive Bayes classifier, show that we can get improved performance with small labeled and large unlabeled documents then the performance of supervised learning which uses labeled-only data. When considering the efficiency of a classifier system, the one step semi-supervised learning algorithm which is suggested in this study could be a good solution for improving classification performance with unlabeled documents.

• International Journal of Highway Engineering
• /
• v.13 no.2
• /
• pp.21-29
• /
• 2011

Recently, typhoons or heavy rainfalls frequently occurred because of the effect of global warming, which caused serious damage such as landslide of mountain road, debris flow and uplift seepage pressure. Uplift seepage pressure induced on the pavement of mountain roads may cause serious pavement damage. It was known that subsurface drainage method is very effective to reduce uplift seepage pressure. Suitable permeability and stiffness of drainable base is very important to have the effectiveness of subsurface drainage. In this study, optimum particle size distribution of drainable base is investigate to meet the required permeability and bearing capacity of drainable base.

• Journal of Chest Surgery
• /
• v.37 no.3
• /
• pp.220-227
• /
• 2004

The number of patients with coronary artery disease and peripheral vascular disease are increasing, and the need of small diameter vessel is also increasing. We developed small diameter artificial vessel and experimented in vivo. We got allogenic valve from mongrel dogs, and removed all cells from the allogenic valve. Then, we seeded autologous bone marrow cells onto the decellularized scaffold. After implantation of artificial vessel into the canine carotid artery, we performed angiography regularly. In case of vessel occlusion or at 8 weeks after operation, we euthanized dogs, and retrieved the implanted artificial vessels. Control vessels were all occluded except one (which developed aneurysmal dilatation). But autologous cell seeded vascular graft were patent by 4 weeks in one, by 6 in one and by 8 weeks in two. Histologic examination of patent vessel revealed similar structure to native artery. Tissue-engineered vascular graft manufactured with decellularized allogenic matrix and autologous bone marrow cells showed that tissue engineered graft had similar structure to native artery.

• Korean Journal of Applied Biomechanics
• /
• v.19 no.4
• /
• pp.707-717
• /
• 2009

The purpose of this study was to investigate the kinematic parameters between a stalled group and a less skilled group of female javelin throwers, in order to record differences in their support landing and release phase. For this, the female athletes were divided into two groups: the sidled group, which consisted of javelin throwers with records over 45m, and the less skilled group, which consisted of javelin throwers with records below 45m. During the release phase, the horizontal velocity differed significantly(p<.05) between the two groups. The projection angle at the release moment also differed significantly(p<05) between the groups. The knee angle of the support leg differed significantly(p<.05) between the two groups at E1, E2, and E3, but there was no difference at E4. The shoulder angle differed significantly(p<.05) between the two groups only during the landing of the power leg.