• 소음진동
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• 제5권2호
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• pp.207-213
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• 1995

본 논문에서 구조동력학 문제를 풀기 위한 명시적(explicit) 예측 수정자 시간적분법을 개발하였으며, 이 알고리즘은 최근 개발된 암시적(implicit) 일반화된 $\alpha$ 방법으로부터 유도하였다. 암시적 방법과 같이 명시적 일반화된 .alpha. 방법도 하나의 변수를 갖는 알고리즘의 집합이며, 이 변수는 고주파 영역에서 수치 감쇠의 양을 정의한다. 제안된 알고리즘은 수치감쇠가 없는 시간적분법으로 파의 젼달 문제를 풀때 나타나는 가상의 진동을 감소시키는 수치감쇠를 가지고 있기 때문 에 선형 혹은 비선형의 구조동력학 문제에 효과적으로 이용될 수 있다.

• 지구물리와물리탐사
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• 제3권4호
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• pp.125-128
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• 2000

본 연구에서는 탄성파 임펄스 반응 해를 구하는 하나의 대안으로서 시간적분(formal time-integration)을 이용하여 시간 영역에서의 이론 변위를 계산하는 방법에 대해 고찰하였다. 이는 복소 적분법을 이용하여 푸리에 적분식을 직접 적분하는 대신 우선 가속도에 대한 해를 유도하고, 이로부터 시간적분을 이용하여 변위에 대한 해를 유도하는 방법이다. 이 방법은 시간에 대한 푸리에 적분식을 복소적분을 이용하여 구하는 경우 야기되는 유인성과 관련된 혼란을 피할 수 있어, 변위에 대한 이론 임펄스 반응 해가 직관적인 델타함수와 층계함수에 대한 미적분 관계만을 사용하여 쉽게 구해진다.

• 한국항만경제학회지
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• 제20권1호
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• pp.95-122
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• 2004

This study focuses on analyzing the potentiality of economic integration and the changes in logistics circumstances in Northeast Asia. So far as the changes in logistics circumstances in it, it is emphasized a complex transport system by sea and by land, according to the connection with the Railroad of South-North in Korean Peninsula and the Railroad of the Continent of Siberia. It first considers the propriety of economic integration among Korea, China and Japan in Northeast Asia. The first stage of the economic integration in Northeast Asia means it is started from contracting of FTA(Free Trade Agreement) which just agreed at the Summit Conference among Korea, China and Japan in ASEAN＋3(Korea China. Japan). At that time, the Summit Conference between the three countries have agreed to study on the propriety of FTA charging by own country's research organization. At first China has been hesitated to join with FTA in spite of high growth in his economy, because the time is not yet for it. After all, China also decided himself to participate to FTA together with Korea and Japan by reacted to the stimulus at the conference atmosphere between every country of ASEAN. The discussion on the changes in logistics circumstances also is needed to deal simultaneously with a situation in the economic integration in Northeast Asia. It is worthy to be paid our attention to the restoration of the Railroad of South-North in Korean Peninsula, which was disconnected for a long time from the dispute between South Korea and North Korea. Therefore, it needs to be investigated together with the movement of economic integration in Northeast Asia. The reaction on the restoration of the Railroad of South-North in Korean Peninsula is not only limited to the transport of trade cargo between South Korea and North Korea, but also it is reached to all of Northeast Asia, so far as to all of the area of Russia, Europe, and the other neighbor countries. Because this railroad is connected with the Railroad of the Continent of Siberia. The transport of trade cargo in Northeast Asia have been mostly depended upon the transport by sea until now. However, it would be divided into the transport by sea as well as by land from now. As its economic effect, the restoration of the Railroad of South-North in Korean Peninsula could be not only contributed to reduce the cost of logistics within South Korea and North Korea, but also within or without in Northeast Asia, Russia, and Europe. Consequently, it could be improved the power of international competitiveness of goods in Northeast Asia, according to the formation of a complex transport system together with the transport by sea and by land.

• 대한감각통합치료학회지
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• 제17권2호
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• pp.1-17
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• 2019

목적 : 본 연구는 감각통합중재가 감각방어가 있는 성인의 수면의 질 향상에 미치는 영향을 알아보고자 하였다. 연구방법 : 감각방어가 있는 비숙면군 성인 3명을 대상으로 연구 설계는 단일대상연구(single subject research)중 다중기초선 설계를 사용하였다. 기초선 기간은 대상자 1은 4회기, 대상자 2는 7회기, 대상자 3은 14회기로 하였고, 중재기간은 총 4주로 주 3회씩 총 12회기 개별 감각통합치료를 제공하였다. 모든 회기에는 총 수면시간, 수면 잠복기, 밤 중 깨기 횟수를 측정하였고 중재 전 후로 수면의 질 변화, 감각방어를 포함한 감각통합능력의 변화와 대상자의 수면 만족도 변화를 알아보았다. 연구결과 : 감각통합중재 적용 후 총 수면시간, 수면잠복기, 밤 중 깨기 횟수를 시각적으로 분석한 결과 모든 대상자에게서 눈에 띄는 향상은 보이지 않았다. 그러나 중재 전 후 평가에서 수면의 질과 대상자가 직접 보고한 수면 만족도가 큰 폭으로 향상되었다. 또한 모든 대상자의 감각통합운동능력은 큰 폭의 향상을 보였다. 그러나 감각처리영역에서 일부 대상자는 눈에 띄는 변화가 없는 것으로 나타났다. 결론 : 본 연구는 성인에게 감각통합중재를 적용했다는 것과 감각통합치료를 수면장애치료를 위한 새로운 중재방법으로 제안했다는 점에서 의의가 있다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제2권3호
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• pp.127-131
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• 2010

A two-layer fluid with free surface is simulated in the time domain by a two-dimensional potential-based Numerical Wave Tank (NWT). The developed NWT is based on the boundary element method and a leap-frog time integration scheme. A whole domain scheme including interaction terms between two layers is applied to solve the boundary integral equation. The time histories of surface elevations on both fluid layers in the respective wave modes are verified with analytic results. The amplitude ratios of upper to lower elevation for various density ratios and water depths are also compared.

• Journal of Mechanical Science and Technology
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• 제16권10호
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• pp.1320-1326
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• 2002

In a one-dimensional heat conduction domain with heated and insulated walls, an integral approach is proposed to estimate time-dependent boundary heat flux without internal measurements. It is assumed that the expression of the heat flux is not known a priori. Hence, the present inverse heat conduction problem is classified as a function estimation problem. The spatial temperature distribution is approximated as a third-order polynomial of position, whose four coefficients are determined from the heat fluxes and the temperatures at both ends at each measurement. After integrating the heat conduction equation over spatial and time domain, respectively, a simple and non-iterative recursive equation to estimate the time-dependent boundary heat flux is derived. Several examples are introduced to show the effectiveness of the present approach.

• 대한조선학회지
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• 제22권2호
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• pp.27-34
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• 1985

In this paper, the second order time mean forces acting on the circular cylinder floating on the free surface of a finite water depth are calculated. Under the assumption that fluid is idea and the wave the linear gravity wave, the velocity potential is calculated by the source distribution method, and the second order time mean lateral and vertical drifting forces are calculated by the direct integration of fluid pressures over the immersed body surface. The comparison of the lateral drifting forces with Rhee's results by momentum theorem shows good agreements. And it is shown that the second order time sinkage forces of a floating circular cylinder cross zero for all water depths.

• 한국소음진동공학회논문집
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• 제21권8호
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• pp.691-697
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• 2011

The purpose of this study is to analyze nonlinear dynamics of a tethered satellite. The coupled non-linear equations of motion are derived by using the extended Hamilton's principle with the polar coordinate system. In order to analyze the response of tethered satellite, time responses are computed by the Newmark's time integration method. We also investigate the dynamic behavior of the system and the effects of length of tether, tip mass and conveyed fluid through the tether with time variation.

• Journal of Mechanical Science and Technology
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• 제20권3호
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• pp.376-381
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• 2006

In this paper, the quaternion, the dual Euler, and the direction cosine methods are numerically compared using a non-aerodynamic 6 degree-of-freedom rigid model at all-attitude angles of an aircraft. The dual Euler method turns out to be superior to the others in the applications because it shows better numerical accuracy, stability, and robustness in integration step sizes. The dual Euler method is affordably less efficient than the quaternion method in terms of computational cost. Numerical accuracy and stability, which allow larger integration step sizes, are more critical in modern real-time applications than computational efficiency because of today's increased computational power. If the quaternion method is required because of constraints in computation time, then a suppression mechanism should be provided for algebraic constraint errors which will eventually add computational burden.

• 대한기계학회논문집
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• 제18권1호
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• pp.223-231
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• 1994

When manufacturing mold dies, an operation sheet is required for each part of the mold dies. The consistent estimation of standard operation time in the operation sheet is difficult, because the estimation is mainly based on subjective judgement. In order to resolve it, concept of feature is introduced in this study. For CAD/CAPP integration, feature technology is being implemented to represent geometrical and technological information of part drawings. A feature database has already been designed, and then used to generate data for process and operation planning modules. Related to this former research, standard operation time is calculated using the feature information and tables used in a real factory.