• 한국음향학회지
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• 제1권1호
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• pp.19-26
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• 1982

n optimization technique is adapted to determine the stage enclosure configuration preferred by performers. The merit function which quantifies the ease of ensemble among the performers is derived from a set of qualitative conditions recommended by researchers of hall acoustics. The ray path tracing technique based on the modified method of images is used to analyze acoustical characteristics at any locations of performers in stage enclosure. The gradient search technique is employed to find the geometric parameters which maximmize the merit function. As an example, optimum stage enclosure configuration of the trio chamber music is obtained using the computer program developed. The developed technique can be used in the design of concert hall stage and also in forming a special enclosure with movable reflecting surfaces.

• 제어로봇시스템학회논문지
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• 제12권5호
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• pp.444-449
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• 2006

Path planning is a key element in navigation of a mobile robot. Several algorithms such as a gradient method have been successfully implemented so for. Although the gradient method can provide the global optimal path, it computes the navigation function over the whole environment at all times, which result in high computational cost. This paper proposes a high-speed path planning scheme, called a gradient method with topological information, in which the search space for computation of a navigation function can be remarkably reduced by exploiting the characteristics of the topological information reflecting the topology of the navigation path. The computing time of the gradient method with topological information can therefore be significantly decreased without losing the global optimality. This reduced path update period allows the mobile robot to find a collision-free path even in the dynamic environment.

• 한국군사과학기술학회지
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• 제12권1호
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• pp.1-7
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• 2009

Tracking and detecting targets by the M/W seeker is affected by the clutter reflecting from the earth's surface. In order to detect the look-down retreating targets, which appear in the sidelobe clutter region, in the M/W seeker of High PRF mode, it is necessary to understand statistical characteristics of the surface sidelobe clutter. Statistical analysis of sidelobe clutter is conducted for several configurations of the surface using data obtained by the CFT (Captive Flight Test) of the M/W seeker in High PRF mode. The probability density function(PDF) fitting is conducted for several configuration and conditions of the surface. PDFs and PDF parameters, which best describe statistical distribution of sidelobe clutter, are estimated.

• Steel and Composite Structures
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• 제10권4호
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• pp.317-329
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• 2010

According to the results of 9 circular concrete filled steel tube (CFT) push-out tests, a new theoretical model for average bond stress versus free end slip curve is proposed. The relationship between verage bond stress and free end slip is obtained considering some varying influential parameters such as slenderness ratio and diameter-to-thickness ratio. Based on measured steel tube strain and relative slip at different longitudinal positions, the distribution of bond stress and relative slip along the length of steel tube is obtained. An equation for predicting the varying bond-slip relationship along longitudinal length and a position function reflecting the variation are proposed. The presented method can be used in the application of finite element method to analyze the behavior of CFT structures.

• 한국IT서비스학회지
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• 제18권1호
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• pp.131-140
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• 2019

This study compares and analyzes the spatial distribution of people in two cities using location information in twitter data. The target cities were selected as Paris, a traditional tourist city, and Dubai, a tourist city that has recently attracted attention. The data was collected over 123 days in 2016 and 125 days in 2018. We compared the spatial distribution of two cities according to the two periods and residence status. In this study, we have found a hot place using a spatial statistical model called dart-shaped space division and estimated the urban area by reflecting the distribution of tweet population. And we visualized it as a CDF (cumulative distribution function) curve so that the distance between all the tweets' occurrence points and the city center point can be compared for different cities.

• 한국의상디자인학회지
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• 제15권4호
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• pp.157-173
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• 2013

In the pleats of the statue in the ancient Greece, a vivid expression is included about clothing, which has organic relationship with a human body. This study examined about diverse expressions of pleats that were shown in the Greek sculpture, based on understanding about a pleat meaning and function, and clothes. As a result, the clothes, which were shown in the statue in the ancient Greece, were reflecting spirit and fashion of the times. The pleats, which were expressed in clothing, are closely related to a human body and simultaneously are those that a sculptor showed own creative intention in a work by reflecting a historical demand, thereby having become an important element of dominating the image in the whole clothing. Also, a change and development in expression were being progressed according to a flow of each period. Amidst what expressiveness based on lines are excellent, the unity and the dynamic formative characteristic were forming the mainstream. The design-based elements related to these characteristics are judged to possibly give many inspirations to designers in the modern fashion design sphere, which is mixed diverse styles, and are considered to be able to be helpful even for establishing newer and more creative design.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.508-513
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• 2000

Micro wave seeker detects micro wave signal reflecting from a object and modifies the angle of a antenna in the direction of a reflecting signal. Gimbal structure makes a motion in the direction of an elevation axis and an azimuth axis and change the direction of a missile toward a object. As before, Micro wave seeker is a important part of a missile. Especially, gimbal structure is designed to resist a external force generated by a strong propelling power. For that reason, it is essential to analyze a vibration feature of gimbal structure. In this paper, we analyze dynamic characteristics of a gimbal structure of a micro wave seeker. And we measure frequency response functions of a gimbal structure in order to investigate the effect of a pre-load on bearing.

• 한국환경과학회지
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• 제12권2호
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• pp.185-193
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• 2003

The purpose of this study was attempted to establish concepts of environmental-friendly applications of flood plain and to suggest the application plans. The results of this study can be summarized as follows; 1. Roles of flood plain as biotop (restoration, preservation, and creation of stream corridor ecosystem) should be considered. 2. Application methods considering environmental and scenic values should be reviewed. 3. Application methods reflecting values as regional ecological resources should be planned. 4. Preservation and application should be considered together, and obtaining a means of living for regional residents and creation of economic profits should be considered together. 5. Land application and approach method by usages (integrated management model) should be applied to utilize and manage flood plain efficiently. 6. Flood plain application programs should be designed reflecting opinions of regional residents. 7. With respect to space planning of flood plain, introduction of facilities focused on ecosystem preservation/ecosystem restoration/experiences/observation/learning/culture/ recreation/water purification could be reviewed positively.

• 한국해안해양공학회지
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• 제19권5호
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• pp.502-510
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• 2007

본 연구는 항만입구 부근에서 해저준설을 실시하여 Pit를 설치하였을 경우 이에 따른 항내, 항만입구 주위, 그리고 항외곽 수역에서의 파랑장에 관한 것이다. 항내 및 항외에서의 파랑장은 평면2차원으로 취급하고, 준설에 의한 Pit는 장방형의 형태로 구성한다. 본 연구에서 사용한 해는 경계적분 방정식(BIE)을 기본으로 하여 얻어진 Green 함수를 이용하여 수치계산을 실시한다. 본 연구에서는 입사각 $90^{\circ}$ 및 부분 반사 경계면을 갖는 항내 안벽으로 적용하여 그 결과를 제시한다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권6호
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• pp.46-52
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• 2010

Derivative analysis, based on the derivative of the drawdown as a function of time (i.e., rate of drawdown change), was applied to the evaluation of hydraulic parameters of the aquifer as an aid of the aquifer test interpretation based on the Theis solutions. Pumping tests were conducted at a coastal fractured aquifer in Muan county, Korea, of which the drawdown data, measured at the two observation wells, were used for derivative analysis. Wellbore storage and transition period were hard to identify at conventional log-log and semi long plots, but was easily recognized by distinctive curves of positive unit slope, hump and negative unit slope in the derivative plot. For the observation well of OW-2 at which wellbore storage and transition lasted over an hour, conventional aquifer analysis would suffer from the uniqueness problems and in further result in erroneous hydraulic parameters. Derivative analysis was found to be effective for distinguishing the drawdown data directly reflecting the aquifer property from those reflecting non aquifer effects such as wellbore storage and transition, which offers a unified methodology to yield correct hydraulic parameters from aquifer test data.