• 한국지진공학회논문집
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• 제10권3호
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• pp.101-111
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• 2006

이 논문에서는 안정대륙권역(Stable Continental Regions, SCRs)에서의 중규모 지진에 의한 근단층지반운동(Near Fault Ground Motion, NFGM) 모델을 처음으로 제시한다. 근단층지반운동은 큰 진폭의 장주기 속도 펄스를 갖는 특징을 가지고 있다. 이 속도 펄스를 모델링하기 위해서는 그 주기와 진폭을 지진의 규모와 단층거리의 함수로 표현할 수 있어야 한다. 그런데 안정대륙권역에서는 관측 자료가 빈약하여 지진데이터로부터 이 관계식을 직접 유도하는 것은 어렵기 때문에 이 연구에서는 간접적인 접근법을 채택하였다. 속도 펄스의 주기와 진폭은 단층파열의 상승시간과 파열속도의 함수임이 알려져 있고 활성구조권역(Active Tectonic Regions, ATRs)에 속하는 미국 서부지역에서는 실험적 공식이 확립되어 있다. 안정대륙권역에서의 상승시간과 단층파열속도의 지진규모에 대한 함수관계는 WUS와 CEUS에서의 자료를 비교하여 도출하였다. 이 관계식들로부터 안정대륙권역에서의 NFGM의 속도 펄스의 주기와 진폭을 지진규모 및 단층 거리에 대한 관계식으로 유도하였다. 안정대륙권역에서의 NFGM의 가속도 시간이력은 추계학적으로 생성된 원역지진지반가속도에 새로운 관계식에 의한 속도 펄스를 중첩하여 얻어진다. 적용 예제로서 탄소성 단자유도 시스템의 근단층지반운동에 대한 응답을 분석하였다.

• 한국수자원학회논문집
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• 제45권10호
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• pp.1035-1041
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• 2012

본 연구는 유역의 침수특성치를 기준으로 하여 치수계획규모를 설정하는 방법을 연구한 것이다. 본 연구에서는 2010년 9월21일 광화문일대에 발생한 침수피해를 이용하여 XP-SWMM 2010 모형을 검증한 후 침수예상도를 산정하였다. 확률강우량은 Huff의 4분위법으로 분포시켰으며, 기존의 유역출구점을 기준으로 한 임계지속시간의 문제점을 제시하였으며 침수특성치(관로첨두유출량, 평균침수심, 특정지점의 최대침수심, 침수면적, 침수총량, 침수지속시간)를 기준으로 유역치수계획규모를 설정하는 방법을 제시하였다. 현재 유역의 치수계획규모 설정시 사용되고 있는 관로첨두유출량은 도시유역의 침수특성을 합리적으로 반영하지 못하는 것으로 판단되었으며 도시유역에서 발생하는 침수의 결과치인 침수특성이 치수계획규모 설정에 합리적인 것으로 나타났다. 유역의 치수계획규모는 각 유역의 지리 물리 사회 경제적 특성에 기반한 침수특성치를 선택하여 그 유역이 감당할 수 있는 침수특성치를 제외한 나머지의 침수특성치를 극복할 수 있도록 설정해야할 것이다.

• 대한전기학회논문지:전력기술부문A
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• 제50권6호
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• pp.275-278
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• 2001

This paper presents an algorithm for detecting current transformer (CT) saturation. At the instants of beginning (or end) of saturation, as a magnetizing inductance of the core is changed significantly, the shapes of the secondary current are also changed significantly though secondary currents are continuous the instants. At the instants, the second-order of third-order difference of the secondary current has big values. Thus, the third difference of the current is used to detect the beginning/end of CT saturation in this paper. If the magnitude of third-order difference of the secondary current is larger than a threshold value, the CT begins of ends saturation at the instants. The proposed detection method is unaffected by the amount of residual flux. The results of various tests with residual flux from -80% to +80% indicate satisfactory performance of the method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1603-1605
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• 1996

We have studied the static electricity and optical retardation generated by rubbing the surfaces of polyimide (PI) and polyamide (PA) films. The static electricity increases with the rubbing strength (RS) and varies with the different PI films. We also investigated how the differences in the rubbing fabric affects the magnitude of the induced static electricity; the order of this effect is nylon > rayon > cotton. The induced static electricity is not only directly related to the values of the specific resistivity of the rubbed PI films, but also the RS and the ability of the rubbing fabric to generate and add a static electric charge. The order of the optical retardation produced by the rubbing fabraic on rubbed PI films is nylon > rayon > cotton, coinciding with the order of the generated static electricity.

• 소음진동
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• 제9권5호
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• pp.914-921
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• 1999

There are many theoretical investigations to analyze higher order mode of reactive type single expansion chambers with offset inlet/outlet locations. But the conventional method has the restriction that the ratio between the area of inlet(or outlet) pipe and that of chamber must be natural number. In the paper, a new method was suggested to apply the Kim's method to silencer with circular cross-section. Not only the offset location but also the magnitude of cross-section area of inlet/outlet pipe can be considered by the suggested method. The predictions by this new method also compared with those by the finite element method and Munjal's method in order to verify the accuracy of the suggested method presented here.

• Tribology and Lubricants
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• 제16권6호
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• pp.461-468
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• 2000

In this study, a neural network based diagnostic system of a rotating spindle system supported by ball bearings was introduced. In order to create actual failure situations, two exemplary abnormal status were made. Out of several possible data source locations, ten measurement spots were chosen. In order to discriminate multiple abnormal status, a neural network system was introduced using back propagation algorithm updating connecting weight between each nodes. In order to find the optimal structure of the neural network system reducing the information sources, magnitude of the weight of the network was referred. Hinton diagram was used to visually inspect the least sensitive weight connecting between input and hidden layers. Number of input node was reduced from 10 to 7 and prediction rate was increased to 100%.

• 천문학회지
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• 제17권2호
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• pp.115-125
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• 1984

Effect of magnetic field on the thermal instability is studied in the radiatively cooling region behind an interstellar shock of moderate propagation velocity (${\sim}10\;km/sec$). It is shown that the presence of interstellar magnetic field of a few micro gauss is very effective in preventing the thermal instability from building-up density concentration. In the absence of magnetic field, the shock-induced thermal instability amplifies preshock density inhomogeneity by more than an order of magnitude. However, in the presence of magnetic field, the amplified density contrast is shown to be only a factor 2.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.665-669
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• 1997

In this study, the fatigue lives of two kinds of specimens made by co/sab 2/ gas were assessed. The materials for two kinds of specimens were taken out of the virgin carbon steel tubes and used carbon steel tubes, respectively. As a result, it was found that the fatigue lives of two groups of specimens were in the same order of magnitude.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2001년도 학술대회 논문집
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• pp.65-67
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• 2001

Temperature and resistance of a Bi-2223 tape for fault currents up to 10 $I_{c}$ were measured in two types of samples taking into account real applications. The results indicate that the Bi-2223 tape is safe from burn-out for fault currents with a few cycles up to 10 I$_{c}$. For fault currents of over an order of magnitude higher than the nominal current, the temperature of the Bi-2223 tape depends strongly on fault durations.s.

• 한국정밀공학회지
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• 제15권1호
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• pp.13-18
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• 1998

In this study. the fatigue lives of two kinds of specimens made by $CO^2$ gas weld were assessed. The materials for two kinds of specimens were taken out of the virgin carbon steel tubes and the used carbon steel tubes respectively. As a result, it was found that the fatigue lives of two groups of specimens were in the same order of magnitude.