• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.129-136
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• 2010

Axial piston pumps have been widely used as power sources for hydraulic systems, but studies on the fluid flow within the pump have been usually performed using 1-D analysis because of the difficulties in considering the fluid compressibility, high-speed revolution, variation of the flow rate, and complicated geometry. The goal of this study was to understand the hydraulic fluid flow within axial piston pumps by using the 3-D numerical method and the process of generating discharge pressure ripples. To improve the convergence and robustness of the simulation model, a grid system was constructed with hexahedron-type grids around the valve plate. Furthermore, we employed an empirical formula to describe the relationship between the oil density and pressure. The CFD (computational fluid dynamics) results compared well with the experimental data.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.11a
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• pp.127-130
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• 2009

국가 간 문화의 차이에 의하여 생활습관이나 방식이 많이 다르게 나타난다. 그 중에서도 음식은 다른 분야보다 많은 차이를 나타난다. 특히 음식의 종류에 따라 사용되는 음식도구 중 디자인요소가 동일하고 유사한 것이 있거나 다른 요소와 기능을 갖는 경우도 있다. 따라서 각 국가 간의 음식도구를 유니버설 하게 사용할 수 있는 도구 디자인 연구가 필요하다. 본 연구의 목적은 음식에 대한 행동분석프로세스를 개발하여 국가 간 음식문화의 차이에서 오는 공통점과 차이점을 찾아내어 공용으로 사용할 수 있는 음식도구의 디자인요소를 창의성의 관점에서 제안하기 위한 연구이다. 본 연구의 연구방법과 내용으로는 첫째, 음식에 대한 소비자행동 분석 프로세스의 개발 및 관찰을 통하여 행동분석에 대한 이론적 고찰과 현장에서 일어나고 있는 행동분석을 접목하여 음식행동분석프로세스를 개발하였다. 둘째로, 개발된 프로세스를 이용하여 국가 간 음식의 주문부터 평가까지의 과정을 비교 분석하고 나타난 현상에 대한 문제점 파악 및 이에 대한 결과물을 각 국가별 학생들을 대상으로 음식도구에 대한 디자인 개발을 진행하였다. 셋째, 국가별 개발된 디자인 안을 대상으로 선호도, 요인분석, 상관분석을 통하여 국가별 선호요소와 창의성평가요소의 상관관계를 알아보았다. 본 연구를 통하여 얻어지는 효과는 개발된 프로세스를 이용하여 국가별, 음식별, 행동별, 식당형태별로 비교분석이 가능하도록 하게 하고 얻어진 결과를 이용하여 구체적으로 음식도구 디자인에 이용할 수 있으며 국가간 동일 아이템을 디자인 교육시간에 진행시켜 대학의 디자인교육의 비교를 통하여 상호간에 협력과 상호보완으로 새로운 아이디어를 공유, 아이디어 전개에 도움이 될 수 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.834-841
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• 2012

In order to the mobile service uses the wireless terminal including the development of the wire wireless network and Smart phone, and etc. use including mobile office, which and etc. increases. Because in order that the u-Healthcare service using this appeared before the footlights and the existing quality measurement reference considered the speed, error rate, and etc. just, guarantees the stability of the u-Healthcare, the quality control by service are necessary. In this paper, the quality measurement reference by mobile service considering the radio environment as the method for satisfying the quality guarantee of the u-Healthcare mobile service user and user needs was presented. The WiBro u-Healthcare wireless data service quality based system in the end user perspective was established through the main performance index and entrepreneur case presented in the international standardization institute including 3GPP, WiMAX forum, GSMA, and etc. through the related research and the validity of the quality index establishment was presented according to each service.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.2
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• pp.241-248
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• 2013

In this study, bearings were developed for a high-power propulsion motor operating in inclined operation conditions through a simulation and similitude-experimental methods using commercial rotating machinery dynamics analysis software. The developed journal bearing is electrically insulated and has low thermal conductivity because each part is connected with 2-4 -mm-thick epoxy plates. To realize an appropriate oil thickness, an oil lift system is adopted, and a half separated structure is applied to ensure the feasibility of maintaining very heavy components. This study discusses some of the key design aspects of sleeve bearing design for high-torque and low-speed propulsion motor applications. Furthermore, the conditions of variable slope tests are examined to prevent oil leakage from the bearing lip seal on the test rig.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1237-1244
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• 2015

A gerotor can be manufactured in a miniature size because it has a high discharge per cycle and a simple structure. Gerotors are widely used for the lubrication oil of an engine and as the hydraulic source of an automatic transmission. Recently, improvements in fuel efficiency and noise reduction have come to the fore in the automobile industry, and it has been necessary for better fuel efficiency to continuously improve the flow rate and noise of internal gear pumps through the optimal design of the gerotor and port shape. In this study, gerotors were generated based on the equations derived for a lobe shape with multiple profiles (ellipse 1-elliptical involute-ellipse 2). The ranges of the design parameters were considered to prevent a cusp and loop. In addition, the optimal lobe shape was obtained by determining the influence of the lobe shape on the performances (flow rate, irregularity, etc.), according to the values of the design parameters.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.772-776
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• 2001

The flow structures of turbulent shear layer behind oil fences with different tip configurations were investigated experimentally using flow visualization and PIV velocity field measurement. An oil fence was installed in a circulating water channel and the flow structure around the fence tip was mainly analyzed in this experiment. The four tip configurations tested in this experiment are knife edge; semi-circle edge, circular edge and rectangular edge. The 300 instantaneous velocity fields were measured using the single-frame PIV system and they were ensemble averaged to give the mean velocity field and spatial distribution of turbulent statistics. Free stream velocity was fixed at 10ms/sec and the corresponding Reynolds number based on the fence height was Re=4000. As a result, for the oil fence with rectangular edge, the streamwise velocity component was decreased. On the other hand it was increased for the oil fence with circular edge. For all four fences tested in this study, general flow pattern of the lower shear layer is analogous but the upper layer shows difference depending on the tip configurations. The oil fence with circular edge has more diffusive upper shear layer than that of the others. The shear layer of the oil fence with rectangular edge has relatively thin thickness. The oil fence with circular edge was found to be proper shape for tandem fence.

• Korean Journal of Medicinal Crop Science
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• v.8 no.2
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• pp.94-101
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• 2000

On the purpose of development of antioxidative compounds from natural sources, 38 plants known to have antioxidant activity have been examined concerning DPPH radical scavenging activity. Among 13 plants exhibiting the activity, the seed of Carthamus tinctorius L, was selected as resources to search for active compounds due to rareness of study. The seed of the plant has been used as edible oil or preventive and remedial drugs for osteoporosis, arthritis. To reveal the principal component manifesting the antioxidant activity, the MeOH extracts was successively solvent-fractionated with EtOAc, n-BuOH and water. In order to isolate active component from the EtOAc fractions, application of silica gel column chromatographies and activity tests were repeated for a active component to be isolated. Its chmical structure was determined to be N-feruloylserotonin, a conjugated serotonin compound, by the interpretation of spectral data, NMR. MS and the adaptation of chemical reactions.

• The KSFM Journal of Fluid Machinery
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• v.3 no.1 s.6
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• pp.43-50
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• 2000

Upgrade development of a high pressure ratio centrifugal compressor in marine engine turbochargers is presented. A new matched operating point at increased speed of rotation was determined through system cycle analysis using the exisitng test data of turbine performance. Under some severe restrictions for geometric parameters, the state-of-the-art methods of both aerodynamic design and CFD analysis were applied, in which only an impeller, a vaned diffusor and some part of casing wall were modified. Prototype hardware was fabricated and assembled for system performance tests. Excellent performance in pressure ratio and efficiency was obtained over whole speed region. Reduced surge and choke margin was, however, observed at design speed of rotation.

• Archives of design research
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• no.18
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• pp.153-162
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• 1996

underground space have many negative environmental clements which should be confirmed on location and line of action by the artificial signs. iccordingly, environmental graphics as visual language for popular signification-function have to be studied on sign theory of symbolic meanings. Ho\/ever, its usage has not only decorated by microscopiC appreciative eye but also lost its meanlllg as a visual language which was caused by the negligence of systematic management of the facility in charge Result of study, Visual environmental factors as a cause of behavioral attitude based on the study, which has been carefully considered as a communication of the visual language. Therefore, considering the underground environmental graphics as the: sign or the signification-function, It has to be studied on syntactic, semantic and pragmatic viewpoint. SpeCifically, to maKe the color and formation language a signification-function as a generalized connotation to the public, a distinctive classified Visual language must be applied.

• Journal of Astronomy and Space Sciences
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• v.24 no.2
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• pp.155-166
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• 2007

We have designed a high resolution proton and electron telescope for the detection of high energy particles, which constitute a major part of the space environment. The flux of the particles, in the satellite orbits, can vary abruptly according to the position and solar activities. In this study, a conceptual design of the detector, for adapting these variations with a high energy resolution, was made and the performance was estimated. In addition, a parallel processing algorithm was devised and embodied using FPGA for the high speed data processing, capable of detecting high flux without losing energy resolution, on board a satellite.