• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.82-98
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• 1994

A mathematical model for the hydrodynamic forces acting on the ship manoeuvring in waves is formulated and a numerical method for the problem is developed. The motion of a ship, which manoeuvres in waves, may be thought to have two components; one is a high frequency component due to encounter waves, and the other is a low frequency component due to manoeuvring motion. So the method of two time scale expansion is used to divide linear boundary value problem. For the effects of waves on the manoeuvring motion of a ship, only the second order drift forces are considered. The integral equation for the velocity potential is solved by 3 dimensional panel method and hydrodynamic forces are calculated by direct integral method.

• Proceedings of the ESK Conference
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• 1995.04a
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• pp.145-154
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• 1995

복잡한 생산시스템 속에서 빠른 속도로 제품을 생산하기 위해서 도입된 신형 고성 능 기계류의 경우에는 검사 작업자가 제품의 결점을 검출하기가 매우 어렵다. 검사작 업을 위해서 충분한 시간이 주어진다면 정확하게 처리할 수 있겠지만, 실제로는 많은 제약이 있다. 이러한 관점에서 검출오류의 결과에 대한 중요성은 증가되고 있다. 본 연구에서는 검사작업의 개인차에서 비롯하는 작업자의 결점검출방법에 관하여 살펴보고자 한다. 이를 위해서, 먼저 피실험자를 대상으로 두가지 작업방법, 즉 기능적 검사(functional search)를 하는 작업자와 지형적 검사(topographic search)를 하는 작업자로 나누어 실험을 하였다. 또한 이들이 검사작업을 하는 동안 일어나는 안구운동(eye movements)의 몇가지 요인을 측정하여 시각검사작업에 영향을 미치는 안구운동요인을 파악하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.327-328
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• 2015

최근 건강을 생각하는 사람이 증가하면서 걷는 사람들이 증가하고 있다. 걷기를 통한 건강관리에 대한 관심이 증대되면서 스마트 디바이스를 활용한 운동 관련 어플리케이션도 역시 증가하고 있다. 본인의 기록을 측정하기 어렵고 별도의 장비가 필요하던 과거와 달리 이제는 누구나 가지고 있는 스마트폰만으로도 자신의 운동을 효율적으로 자신의 운동을 관리할 수 있도록 하는 어플리케이션이 인기를 끌고 있다. 이러한 수요에 맞추어 스마트 상의 GPS센서를 이용한 걸음 가이드 시스템 '걸어보자'는 별도의 센서를 부착할 필요 없이 스마트폰에 기본적으로 포함되어 있는 GPS센서를 이용하여 사용자에게 추천루트를 제공한다.

• Journal of Oral Medicine and Pain
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• v.37 no.2
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• pp.107-112
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• 2012

Orofacial movement disorders (OMD) are uncontrolled movement of the muscles involving the face, tongue, lip and mandible. Due to variable oral and lingual muscles affected, the patients with OMD are interfered with the appropriate performance such as chewing, swallowing and talking. In this study, there are 4 OMD cases with oral dryness that saliva flow rate is decreased or not. The symptoms are improved after oral administration of pilocarpine to 4 patients with OMD. Therefore, we suggest that objective or subjective oral dryness could be etiologic factor in OMD and pilocarpine could be regarded as medication for OMD.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.351-357
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• 2013

In flip chip packaging, underfill process is used to fill epoxy bonder into the gap between a chip and a substrate in order to improve the reliability of electronic devices. Underfill process by capillary motion can give rise to unwanted air void formations since the arrangement of solder bumps affects the interfacial dynamics of flow meniscus. In this paper, the unsteady flows in the capillary underfill process are visualized and then the racing effect and merging of the meniscus are investigated according to the arrangement of solder bumps. The result is shown that at higher bump density, the fluid flow perpendicular to the main direction of flow becomes stronger so that more air voids are formed. This phenomenon is more conspicuous at a staggered bump array than at a rectangular bump array.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.4
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• pp.50-60
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• 2014

Many countries are paying efforts to the research and development of water-breathing ramjet propulsion for submersible vehicle with the super-cavitation which makes traveling at high speed in underwater possible. In this study, a conceptual design of an underwater vehicle with water-breathing ramjet was carried out. Mission profiles and operating conditions are determined by examining the operation environment. Drag is estimated based on the theories of super-cavitation and fluid mechanics. The sizing and performance analysis of the components were performed using thrust required, thrust and specific impulse of designed engine were verified.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.3
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• pp.395-403
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• 2016

A cylinder-type underwater vehicle for military use that is running near the free surface at the final homing stage to hit a surface ship target is affected by wave force and moment. Since wave can affect an underwater vehicle running at the depth less than half of the modal wave length, it is important to confirm that the underwater vehicle can work well in such a situation. In this paper, wave force and moment per unit wave amplitude depending on wave frequency, wave direction, and vehicle's running depth were calculated by 3-Dimensional panel method, and the numerical results were modeled in external force terms of six degrees of freedom equations of motion. Motion simulation of the underwater vehicle running in various speed, depth, and sea state were performed.

• Korean journal of communication and information
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• v.19
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• pp.125-153
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• 2002

Because most of feminist researches on the media have been primarily concerned with women's roles and representations in main scream mass media, women's media as alternative media remain remarkably understudied. Thus this study explores women's media in relation to women's movement during the period of US military Government in Korea. There were five women's newspapers which were means of women's movement in this period. However, failing to attract enough appropriate revenues and resort to fund-raising, women's newspapers could nor be published a long time. And women's newspapers as means of women's movement had the defects in women's representations because women's movement lacked a certain degree of autonomy from the male-dominated political activities. In other words, women's newspapers maintained women's participation in political areas, but on the other hand they emphasized the women's role as mother and housewife.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.8 s.227
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• pp.968-975
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• 2004

Nanofluids have anomalously high thermal conductivities at very low fraction, strongly temperature-dependent and size-dependent conductivities, and three-fold higher critical heat flux than that of base fluids. Traditional conductivity theories such as the Maxwell or other macroscale approaches cannot explain why nanofluids have these intriguing features. So in this paper, we devise a theoretical model that accounts for the fundamental role of dynamic nanoparticles in nanofluids. The proposed model not only captures the concentration and temperature-dependent conductivity, but also predicts strongly size-dependent conductivity. Furthermore, we physically explain the new phenomena for nanofluids. In addition, based on a proposed model, the effects of various parameters such as the ratio of thermal conductivity of nanofluids to that of a base fluid, volume fraction, nanoparticle size, and temperature on the thermal conductivities of nanofluids are investigated.

• ICROS
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• v.15 no.4
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• pp.38-42
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• 2009

제어 및 로봇 응용에서 다양한 좌표계와 이를 기반으로한 벡터의 좌표값이 활용되고 있다. 이는 운동을 수반하는 대다수의 지능 시스템에 있어서 시스템의 현재 위치 및 자세 정보가 미래의 동작을 결정하고 제어하는데 필수 불가결하 정보로 인식되기 때문이다. 다양한 응용분야에 활용되는 중용성에도 불구하고, 필자의 경험에 의하면, 벡터 및 좌표계 관련 사항들은 입문자가 처음 접하는 단계에서 큰 부담을 느끼는 부분으로 이해된다. 이와 같은 경험을 바탕으로 본 고는 벡터와 좌표계 그리고 좌표값에 접해본 경험이 없는 독자에게 기본적인 개념들을 별도의 보조 문헌이 필요 없이 알기 쉽게 설명하는데 그 목적이 있다.