• 반도체디스플레이기술학회지
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• 제8권4호
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• pp.53-58
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• 2009

A SMT mounter is a kind of equipment that mounts SMD parts quickly on the printed circuit board. By using linear motors, it is controlled with high speed and precision, which is similar to semi-conductor and display process equipment. It is necessarily used in an assembly process of an electronic device. Mobile devices such as a mobile phone and PDA are required to reduce mount areas due to the demands for high performance and small size. Hence, super small sized and complex mobile devices have been developed. To improve the productivity of the corresponding equipment, designs with large sized, high speed, and multidisciplinary functions have been consistently performed. Meanwhile, a design trend of large size and light-weight on SMT mounter causes a low natural frequency of systems and vibration problems at the high speed operation. In this paper, the dynamic characteristics of the SMD mounter system were investigated through a modal test and transmissibility test, and verified by finite element method. Also, various design improvement was performed to avoid the resonance phenomena.

• 설비공학논문집
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• 제9권3호
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• pp.284-291
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• 1997

A hydrogen liquefaction equipment by direct cooling has been designed and built at KIST. Cool-down characteristics and liquefaction performance of the equipment have been investigated. The hydrogen liquefaction equipment consists of a GM refrigerator, a liquefaction velssel, a radiation shield and a cryostat. It is found that the hydrogen starts to be liquefied in the liquefaction vessel after 40~50 minutes of cool-down from the gas state of 270K. The effect of natural convection phenomena of charged gas in liquefaction vessel on the cool-down characteristics is evaluated by comparing with those in vacuum of liquefaction vessel. It is seen that the cool-down time of a liquefaction vessel is substantially increased in vacuum environment of liquefaction vessel. The experiments have been performed for 1~5 atm of hydrogen pressure to investigate the influence of hydrogen pressure on the liquefaction rate and figure of merit(FOM). It is found that both liquefaction rate and FOM are increased as the charged hydrogen pressure is increased.

• 환경영향평가
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• 제15권2호
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• pp.101-109
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• 2006

Water quality simulation models include the difference between the measured and estimated values as an inevitable consequence because they represent the complicated natural phenomena as simplified mathematical equations. The major reason of the difference occurrence is due to the use of the imprecise values of the model parameters, but the parameter values are currently determined by the try and error method directly performed by humans. However, the use of this method requires many time and endeavor of humans, and generally does not obtain the most suitable parameter values. A method for deciding model parameter values is, therefore, developed in this study. The method minimizes the difference between the measured and estimated values and also distributes uniformly the measured values on the upper and lower sides of the line representing the estimated values. A user interface based on this method is also developed by using the Visual Basic 6.0 of Microsoft, and it can be operated in the environment of Windows 98/2000. In this study, the method for deciding model parameter values is applied for estimating the water quality of the stream Ko-heung. The results of the application show that the method, including its computer program, can effectively obtain the most suitable parameter values and also save many working time in comparison with the existing method directly performed by humans.

• 한국소음진동공학회논문집
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• 제16권3호
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• pp.219-225
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• 2006

In Seoul, several railway depots are located at the places where a public can easily access. Since a depot occupy a large amount of land itself, it is natural to use those sites for a public building construction such as an apartment complex or a transportation terminal, as an example. Most of the buildings on a depot, however, are exposed to vibration problems, because foundations are excited from the dynamic loading whenever heavy trains pass on the track. Severe vibration may cause a damage to building structures and a troublesome to a community. In this paper, some vibration practices have been examined in order to resolve the vibration problems. First, a critical speed of a train in a railway depot is evaluated. Then, the structural effect has been investigated. Finally, practical approaches to reduce the vibration level have been proposed. In this first half part of the paper, the focus has been on the critical speed and a structural transmission phenomena.

• 한국실내디자인학회논문집
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• 제41호
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• pp.246-255
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• 2003

All art forms are the results of the artist's response to the philosophical, sociological, and cultural tendencies of the period in which the artist lives. Post-modern period differentiates itself from Modern period in many aspects. One of these is the emphasis on phenomena which are ephemeral and changing. This paper looks at the perceptive and cognitive bases of these expressions of change in space design and their affordances on human behavior The first chapter provides the purpose and the background of the research. It studies the philosophical, sociological and cultural characteristics of the Post-modern era which bring forth expressions of time ＆ change in space design. The second chapter explains two basic approaches which can be applied to the perception and cognition of the environment. The third chapter deals with the perceptional and cognitive bases, and the human affordances of the expressions of change in space design. Finally this paper will analyze the types of space design which show this tendency : change by the technology, change by the participation of viewers, and change by the natural and chance. In each type, there will be analyses of examples. this will lead us to the understanding of how the space design including time & change expresses the spirit of the age and how it can play positive roles in human psychology.

• 한국안전학회지
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• 제12권1호
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• pp.77-93
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• 1997

The natural convection and combined heat transfer induced by fire in a rectangular enclosure is numerically studied. The model for this numerical analysis is partially opened, it is divided by a vertical baffle projecting from ceiling. The solution procedure Includes the standard k- $\varepsilon$ model for turbulent flow and the discrete ordinates method (DOM ) is used for the calculation of radiative heat transfer equation. In this study, numerical simulation on the combined naturnal convection and radiation is carried out in a partial enclosure filled with absorbed-emitted gray media, but is not considered scattering problem. The velocity vectors, streamlines, and isothermal lines are compared the results of pure convection with those of the combined convection-radiation, the combined heat transfer. Comparing the results of pure convection with those of the combined convection-radiation, the combined heat transfer analysis shows the stronger circulation than those of the pure convection. Three different locations of heat source are considered to observe the effect of heat source location on the heat transfer phenomena. As the results, the circulation and the heat transfer In the left region from heating block are much more influenced than those in the right region. It is also founded that the radiation effect cannot be neglected in analyzing the building in fire.

• 한국게임학회 논문지
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• 제7권3호
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• pp.77-88
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• 2007

본 논문에서는 불을 애니메이션하고 가시화하는 새로운 방법을 제시한다. 불을 애니메이션하기 위해서 해결해야 하는 문제들 중에서 가장 어려운 문제는 불이 빛과 열을 주위로 방사하는 과정을 시뮬레이션하는 것이다. 이 방법을 해결하기 위해서 연료가 빛과 열을 발산하고 연소물이 되는 연소 과정을 유체 방정식이 구현되는 복셀화된 공간에서 시뮬레이션하는 복합적인 방법을 제안한다. 불의 움직임은 다른 유체의 경우와 같이 유체 방정식을 이용해서 시뮬레이션하며, 시뮬레이션의 각 단계마다 연소 과정에서 발생한 열이 유체의 온도를 높이고, 이렇게 높아진 온도가 불의 복잡한 움직임을 더욱 가중시키는 과정을 반복시키면서 불에 대한 애니메이션이 처리된다. 또한, 불과 불이 주변을 밝히는 효과를 처리하기 위해서 널리 알려진 포톤 매핑 알고리즘의 효율성을 개선한 새로운 가시화 알고리즘을 구현한다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.105-106
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• 2008

As a carrier of malaria and sneak of blood, mosquitoes are an unpleasant insect. However, there are several unknown natural secretes related with mosquitoes. Among them, we focused on the blood sucking process of a female mosquito. The main objective of this study is to understand the mosquito's blood sucking mechanism that can be used to resolve the problem encountered in the injection or transport of infinitesimal biological fluids in a micro-chip. At first, the velocity fields of blood-sucking flow in a proboscis were measured using a micro-particle image velocimetry (PIV) technique. The velocity signals of flow in the proboscis show periodic variation. This seems to be resulted from the beating of the pharyngeal pump which works as driving power. To analyze the pumping mechanism, the temporal variation of the pharyngeal pump was visualized using the synchrotron X-ray micro-imaging technique. The volume variation was estimated by the help of digital image processing techniques. Once the main mechanism of blood sucking process was found, a effective micro-pumping system with high efficiency would be developed in near future.

• 한국의류산업학회지
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• 제4권4호
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• pp.317-326
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• 2002

This study is to analyze the works introduced in the collections of Paco Rabanne in an aim to identify formative aesthetic and design concepts. As the data to study the creative concepts and expressions of the designer, fashion photographs were gathered in a focus on collections. Paco Rabanne's fashion philosophy is to shine women who has passion, energy and self-confidence, with glittering materials. For he had a career of fashion accessary designer and architect, he tried to make his work constructively with non-sewing technology. So, his works could be divided three parts of materials which he has made creative fashion with. They are metallic, non-metallic and fabric. In metallic, design concepts are cosmos, egypt, the middle ages, modern technology. And from these the formative aesthetic were mainly characterized by the futurism, cubism and eroticism. In non-metallic, building, purism of primitiveness, nature. And from these the formative aesthetic were mainly characterized by surrealism, primitivism, romantism. In fabric, design concepts are natural phenomena, optical illusion. And from these the formative aesthetic were mainly characterized by cubism, optical art.

• 대한기계학회논문집
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• 제16권5호
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• pp.910-923
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• 1992

본 연구에서는 가장 응용 빈도가 큰 크랭크-레버 4절 기구를 제작하고 강성과 유연성 두가지 베어링을 사용하여 연결봉과 레버의 중점의 변형률을 스트레인 게이지 로 측정하여 앞의 이론 논문에서 수행한 수치해석의 결과와 비교 검토하였다.