• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.04b
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• pp.99-105
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• 1996

공기 베어링은 마찰과 열 발생이 적고 회전 정밀도가 우수하여 고속 회전하는 축을 지지하는 용도로 많이 사용되고 있다. 그러나 공기 베어링도 유체 베어링이라면 어느것이나 갖는 Whirl 불안정성이라는 치명적인 결점을 갖는데 현재 이것의 발생 시점이 공기 베어링을 사용하는 시스켐에 있어서 고속화의 한계로 되어있다. 본 논문에서는 불안정성의 원인이 되는 동압 발생을 억제할 수 있는 방법으로 베어링의 위치가 축의 위치에 대해 일정한 각도 지연을 갖도록 제어되는 것을 제안하고 여러 각도지연 크기와 제어게인에 따른 안정특성을 이론 해석을 통해 조사하였다.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.13-22
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• 2006

The geotextile have been used in filtration and drainage for over 30 years in many applications of civil and environmental projects. Geotextile tube is compound technology of filtration and drainage property of geotextile. Geotextile have been used for various types of containers, such as small hand-filled sandbags, 3-dimensional fabric forms for concrete paste, large soil and aggregate filled geotextile gabion, prefabricated hydraulically filled containers, and other innovative systems involving containment of soils using geotextile. They are hydraulically filled with dredged materials. It have been applied in coastal protection and scour protection, dewatering method of slurry, and isolation of contaminated material. Recently, geotextile tube technology is no longer alternative construction technique but suitable desired solution. This paper presents the behavior of geotextile tube composite structure by 2-D limit equilibrium and plane strain analysis. 2-D limit equilibrium analysis was performed to evaluate the stability of geotextile tube composite structure for the lateral load and also the plane strain analysis was conducted to determine the design and construction factors. Based on the results of this paper, the three types of geotextile tube composite structure is stable. And the optimum tensile strength of geotextile is 151kN/m and maximum pumping pressure is 22.7kN/m.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.173-179
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• 2005

In succession to previous study(A Study on the Limit of Anchor Dragging for Ship at Anchor sim I), the experiment of anchor dragging by ship handling simulator was performed to investigate the anchoring stability of ship at anchor in this study. The purpose of this experiment is to check the behavior charateristics of ship being dragged and the limit of anchor dragging for ship at anchor. A small tanker ship, which had been anchored in Jinhae Bay when the typhoon MAEMI passed on September 2003, was chosen as model ship for the experiment of anchor dragging and the result of experiment was confirmed to be very similar to the result of theoretical review and field report.

• Journal of Korea Water Resources Association
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• v.33 no.4
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• pp.385-392
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• 2000

An experimental investigation was conducted to determine the effect of a nonuniform pier on the stability of riprap placed around bridge piers. A nonuniform pier is one of which the cross-sectional dimension varies over the length of the pier and comprises a cylinder of diameter bp placed on a larger diameter of foundation bf. and the stability of riprap are significantly influenced by the height of foundation z. The critical height of foundation is defined as the height of foundation which has the same critical velocity to that of uniform pier without foundation, and it was found to be zc=0.8bf. For z

• Journal of Korean Society of Transportation
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• v.15 no.2
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• pp.83-103
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• 1997

교차로 지체를 추정하기 위해서는 대기행렬 모형이 적합한데 모든 대기시스템은 시 간의 함수로 운영되므로 우리는 분석하고자 하는 시스템이 가변상태인지 또는 안정상태인지 를 먼저 결정하여야 한다. 신호화된 교차로에 유입·유출되는 특히 유입교통량은 시간대별 변화가 심하다. 미국 HCM에서는 이를 15분 단위로 분석하도록 제안하였으나 신호교차로 체계의 정밀 분석을 위해서는 만족스럽지 못한 시간단위이다. 이러한 문제점을 극복하기 위 해서는 시스템이 안정상태가 아닌 가정으로 접근하여야 하며, 더 나아가 Dynamic한 분석이 요구된다. 안정상태의 지체는 Webster를 비롯한 여러 학자들에 의해 광범위하게 연구되어 왔다. 그러나 그들이 갖는 가정은 일반적으로 비현실적이어서 정밀한 지체추정은 실제로 가 능하지 않다. 안정상태 가정하에서 해법의 결점은 도착교통량이 용량에 다다를수록 더욱 심 하게 되어 비현실적인 지체예측을 하게 된다. 본 논문은 기존 분석방법론의 제반 한계성과 제약성을 검토하고 현실적인 교차로 지체모형을 개발하기 위해 고려되어져햐 할 변수들을 정립하고자 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.244-249
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• 2008

In this paper, the stable region for missile guidance loop employing an integrated proportional navigation guidance law is derived. The missile guidance loop is formulated as a closed-loop control system consisting of a linear time-invariant feed-forward block and a time-varying feedback gain. By applying the circle criterion to the system, a bound for the time of flight up to which stability can be assured is established as functions of flight time. Less conservative results, as compared to the result by Popov criterion, are obtained.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.109-110
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• 2008

전체송전용량은 열 안정도, 과도안정도, 전압안정도 등에 의하여 제한을 받게 되는데, 한전 전력시스템에서는 주로 전압안정도에 의하여 제한을 받는다. 현재에도 상당한 규모로 북상조류가 흐르고 있어서, 전력시스템의 안정도를 고려한 융통전력의 한계가 중요한 문제로 부각되고 있다. 본 논문에서는 평가선로 조류의 모선 전력 민감도를 활용하여 전체송전용량을 산정하는 기법이 IEEE 39 모선 테스트 시스템에 적용되며, 실제적으로 운용하고 있는 경제급전의 순서인 Merit order(우선 순위)를 적용하여 전체송전용량 산정을 하는 것과의 결과를 비교 검토한다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.333-334
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• 2015

2015년 발,송,배전 설비 신설, 변경과 최대부하82,000MW에 대비하여 우리나라 전력계통의 운영방안을 검토하였다. 고장전류를 차단기 정격 내에 유지할 수 있도록 모선분리, 선로분리 등을 적용하였고, 특히 765kV 송전선로 고장시 계통안정을 위해 수도권의 부하를 차단하는 장치를 정지하는 방안을 마련하여 수도권 계통안정에 기여하였다. 인천지역에서 나타난 과전압 및 안정도 약화에 대해 적절한 발전및 송전제약 한계값을 적용하여 인천지역의 안정 운영에도 기여하였다.

• Journal of the Korean GEO-environmental Society
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• v.5 no.4
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• pp.65-72
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• 2004

Within a country, owing to the restriction of aggregate which have been supplied to construction sites, applicability of byproducts such as the copper slag is expected to be more reasonable. In this study, on the basis of characteristics, grain distribution and environmental stability of copper slag, its engineering application was estimated as the vertical and horizontal drainage material. As a results of laboratory tests, it was shown that the permeability of the copper slag was similar to that of sands under vertical drainage condition. In addition, the copper slag showed higher critical hydraulic gradient than that of sand under upward vertical flow state. The copper slag has potential safety against piping and it that the copper slag is suitable for drainage and filter material.

• Journal of the Korean GEO-environmental Society
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• v.8 no.2
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• pp.11-18
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• 2007

Slope failure triggered by rainfall produces severe effects on the serviceability and stability of railway, Therefore, slope stability problem is one of the major concerns on the operation of railway. In this study, the rainfall conditions triggering slopes failure adjacent to railroads are investigated and the numerical analysis approach in consideration of infiltration and limit equilibrium method based upon multiple slip surfaces are proposed. The rainfall conditions triggering slope failure are as follow: cumulative rainfall is in the range of 150~500 mm, and duration is from 3 to 24 hours. Base upon the rainfall conditions, infiltration analysis and limit equilibrium method for infinite slope condition are carried out. The depth of infinite slope is assumed as 2 m and the multiple slip surfaces modeled with 16.7 cm interval from the bottom slip surface located at the 2 m depth. The assumed bottom slip surface is the location at which factor of safety is converging. The proposed approach shows more reasonable results than the results from the general codes assuming water table at slope surface. In addition, three dimensional plot of cumulative rainfall, rainfall duration, and factor of safety shows that slope stability analysis in consideration of rainfalll must account for cumulative rainfall (rainfall duration).