• The KSFM Journal of Fluid Machinery
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• v.2 no.1 s.2
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• pp.43-49
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• 1999

Flow field and near-field noise of a centrifugal fan has been studied with an efficient compressible method and STAR-CD. The flow field of the centrifugal fan is assumed to be two-dimensional. Most of the compressible studies have been done by inviscid solver because viscous simulation shows little difference. The near field noise is estimated in terms of sound pressure level in frequency domain transformed from the computed pressure fluctuations using FFT. The simulation has been done on various design elements such as impeller blade shapes, the number of blades and cut-off clearance. The comparison shows that the number of blades has a significant effect on near-field noise without losing aerodynamic performance.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.660-664
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• 2004

The flow fields of a lubrication oil pump has been simulated by using CFD in order to improve performance of the pump. The grid for the one flow passage is applied for estimating pump performance. The calculation result shows that there are unfavorable flow characteristics of flow recirculation in the casing part by the guide vane. Thus, the guide vane is modified to reduce the recirculation region. Performance test shows that the modified model pump efficiency is increased by $6\%$ at the rated point compared to that of the original model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.9 s.90
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• pp.785-791
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• 2004

The objective of this research is to suggest anoise prediction method for a centrifugal compressor. It is focused on the Blade Passing Frequency component which is regarded as the main part of the rotating impeller noise. Navier-Stokes solver is used to simulate the flow-field of the centrifugal compressor, and the time-dependent pressure data are calculated to perform the near-field noise prediction by using Ffowcs Williams - Hawkings formulation. Indirect Boundary Element Method is applied to consider the noise propagation effect. Pressure fluctuations of the inlet and the outlet in the centrifugal compressor impeller are presented and the sound pressure level prediction results are compared with the experimental data.

• Proceedings of The KACE
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• 2018.08a
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• pp.171-174
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• 2018

정보교과는 컴퓨터과학적 지식과 기술의 탐구와 더불어 실생활의 문제 해결을 위해 새로운 지식과 기술을 창출하고 이를 통합적으로 적용하는 능력과 태도를 함양하는 교과이다. 2015 개정 교육과정에서 정보교과의 교과역량 중 하나가 협력적 문제해결력이다. 정보교육을 통하여 배울 수 있는 프로그래밍 분야에서 강조하는 역량 역시 협력이다. 본 연구는 정보교과의 관점에서 협력적 문제해결력 측정 방식을 깃허브, 스택오버플로우의 사례와 PISA, ATC21S의 평가사례를 비교하고자 한다. 협업을 통한 더 나은 결과물을 도출해내는 프로그래밍의 과정을 통하여 협력적 문제해결력을 살펴볼 수 있는 토대를 마련하는데 의의가 있다.

• Journal of the Korean Society of Costume
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• v.5
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• pp.185-196
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• 1981

This study concerns Jeugo-ris' collar patterns according to the pictures of the actual measurement of the bequests in Yi dynasty. In early Yi dynasty not only outside collar but also inside collar was the Mog-pan collar. In middle Yi dynasty many Jeugo-ris' bequests has been discovered. The form of the collar was various In before and after the 1590's, the Mog-pan collar and Kal-collar, Dang-ko callar was coexisted. But after the 1700's Jeugo-ris' collar pattern was fixed to the Dang-ko collar. In early and middle Yi dynasty the width of the collar was three or four times as wide as it on these days. In late Yi dynasty the inside collar length was longer than the outside collar length and the width of the collar was gradually narrow. The same thing as the form of the collar on these days had been appeared from the 1900's.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.153-161
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• 1998

This study describes the results of the analysis of measured rotating stall signal in a centrifugal compressor with vaneless diffuser. Unsteady flow and rotating stall in vaneless diffuser were investigated by measuring of unsteady velocity fluctuation using hot-wire anemometer. Experiments were carried out in several impeller rotating speeds, at different radius ratios. Single hot -wire was used to study the characteristics of rotating stall. As a result, the abrupt rotating stall was detected at all measured impeller rotating speeds and the several flow coefficients which are less than 0.16. The number of the stall cell was one at all measured rotational speeds, and the rotating direction was the same as that of the impeller. As the flow rate decreased, the profile of the phase averaged radial velocity component with time changed from a sawtooth to a sine wave.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.2 s.257
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• pp.190-196
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• 2007

A few intake stations have vibration problems caused by pumps, motors and pipes. The vibration transferred from pumps, motors and pipes excites building severely. Therefore, the crack is generated on building wall and people who work at intake station are damaged. In this paper, the vibration has been measured and analyzed for pumps, motors, pipes and building at intake station. Also, the cause of vibration is identified. Finally, the solution of structural vibration is established using the results of measurement.

• Korean Journal of Plant Taxonomy
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• v.38 no.2
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• pp.179-185
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• 2008

Unrecorded species from the beach at Gangnung City is reported: Cakile edentula, Brassicaceae. The genus Cakile is unrecorded in Korea and easily distinguished from other genera in Brassicaceae by the upper member of fruits distinctly longer or thicker than the lower part, petiole white or anthocyanic, style absent and leaves glabrous. The local name is Seo-yang-gaet-naeng-i and the morphological characters and illustrations of the species are provided.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.234-241
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• 1999

The flow at the impeller exit is important to validate engineering design and numerical analysis of pumps. However, it is not easy to measure the flow at the impeller exit and evaluate the impeller performance since there is usually strong interaction between the impeller and the volute casing. We installed axisymmetric collector instead of the volute casing, so there is no interaction between the impeller and casing. A 3-hole Cobra probe is used to investigate the flow at impeller exit and vaneless diffuser region for design and on design flow rate. For a single suction centrifugal pump of low specific speed, the flow field such as velocity, flow angle, and total pressure are measured by traversing the probe across the vaneless diffuser. These data can be used for performance prediction, desist and numerical analysis of pumps.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.514-519
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• 2003

The objective of this study is to document the secondary flow and the total pressure loss distribution in the contoured endwall installed linear turbine nozzle guide vane cascade passage and to propose an appropriate contraction ratio of the contoured endwall which shows the best loss reduction among the simulated cases. In this study, three different contraction ratio of contoured endwalls have been tested. This study was performed by experimental method and when the contoured endwall has the contraction ratio of 0.17 on exit height the results showed the best loss reduction.