• Journal of the Korean Applied Science and Technology
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• v.7 no.1
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• pp.107-114
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• 1990

Optical resolution of aminoalcohols had been achived efficiently by use of (R)-2,2'-dihydroxy-l,1'-binaphtholphosphoric acid as the resolving agent in various organic solvents. Racemic aminoalcohols were resolved very easily and high enantiomer yield (about 70% e,e) in THF. On the other hand, absolute configuration of resolved aminoalcohol was (R)-configuration but one of the Valinnol and Phhenylglycinol was anti-type because of sterichindrance.Optical resolution of aminoalcohols had been achived efficiently by use of (R)-2,2'-dihydroxy-1,1'-binaphtholphosphoric acid as the resolving agent in various organic solvents. Racemic aminoalcohols were resolved very easily and high enantiomer yield (about 70% e,e) in THF. On the other hand, absolute configuration of resolved aminoalcohol was (R)-configuration but one of the Valinnol and Phhenylglycinol was anti-type because of sterichindrance.

• The KSFM Journal of Fluid Machinery
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• v.4 no.2 s.11
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• pp.15-21
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• 2001

Basic equations and their solution procedure we derived for the analysis of an annular pump seal in which the rotor has a large static displacement from the centered position. The Bulk-flow is assumed for a control volume set in the seal clearance and the flow is assumed to be completely turbulent in axial and circumferential direction. Moody's wall-friction-factor formula is used for the calculation of wall shear stresses in the control volume. For the reaction force developed by the seal, linearized zeroth-order and first-order perturbation equations are developed for small motion about an eccentric position. Flow variables are expanded by using Fourier series for the solution procedure. Integration of the resultant first-order pressure distribution along and around the seal defines the 12 elements of rotordynamic coefficients of the eccentric annular pump seal. The results of leakage and rotordynamic coefficients aye presented and compared with the Marquette's experimental results and the San Andres' theoretical analysis.

• Tribology and Lubricants
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• v.25 no.3
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• pp.150-156
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• 2009

Precise leakage prediction for annular type seals of turbomachinery is necessary for enhancing their efficiency and various prediction methods have been developed. As the seal passage is designed intricately, the analysis based on Bulk-flow concept which has been mainly used in predicting seal leakage is limited. In order to improve the seal leakage prediction, full Navier-Stokes Equations with turbulent model derived in the seal flow passage have to be solved. In this study, 3D CFD (Computational Fluid Dynamics) analysis has been performed for predicting leakage of various non-contact type anular seals using FLUENT. Compared to the results by Bulk-flow model analysis, experiment, and 2D CFD analysis, the result of 3D CFD analysis shows improvement in predicting seal leakage, especially for the parallel grooved pump seal.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.6
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• pp.101-108
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• 1991

During torsional fatigue of externally cracked cylindrical specimen, crack face rubbing may occur. At this time, normal contact forces arise when shear displacements cause the crack faces to be wedged open due to mismatch of the fracture surface asperities. These normal forces, in turn, generate friction force which act in opposition to the applied shear stresses and reduce the effective stress intensity factor. The premise of the proposed work is that friction and wedging can be studied by measuring the shear and normal displacement across the crack mouth. We have measured the crack mouth compliance using the new biaxial extensometer.

• 한국IT서비스학회:학술대회논문집
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• 2009.11a
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• pp.83-88
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• 2009

본 연구는 모바일 게임의 이용의도에 관한 연구로서 기존연구들을 바탕으로 한국과 중국 양국간의 차이를 비교하고자 한다. 기존의 연구에서 제시한 게임의 이용의도인 탈출, 사회적 상호작용, 경쟁/도전감, 환상감, 시간 보내기에 모바일기기의 이용의도인 정황성, 과시욕을 추가하여, 중국의 모바일 게임 이용자들의 이용의도를 조사하고 한국의 모바일 게임 이용의도와 비교하고자 한다. 본 연구를 통해서 중국과 한국 게이머의 이용의도에 있어서 공통점과 차이점이 무엇인지를 파악하고, 양국의 사회문화적 특성이 이용의도의 차이에 미치는 영향에 대해 설명하고자 한다. 현재 소수의 한국 게임기업들이 중국에 진출하고 있고 중국의 문화와 시장을 충분히 파악하지 못하고 있는 실정이다. 본 연구의 결과는 향후 한국기업이 중국 모바일 게임 시장에 진출하는데 도움이 되는 시사점을 제시할 수 있을 것으로 여겨진다.

• The Korean Journal of Archival Studies
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• no.64
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• pp.5-25
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• 2020

The archives should not document the absence of labor records, but document the traces of workers' lives. In other words, it is the responsibility of the archive to reproduce the acts and sufferings of contingent workers with records, and to reveal the oppressive structure of capitalism based on them. Records representing the lives of contingent workers, such as labor manuals, should be at the core of records that symbolize the present, and archives should be documented. The archives should discard the illusion of neutrality.

• Solar Energy
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• v.8 no.2
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• pp.66-72
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• 1988

Natural convection in a horizontal annulus with spacers has been studied on the effects of diameter ratio and Rayleigh numbers and position of spacers by experimental method. In case of vertical spacers, the local spacer Nusselt numbers show positive values on the lower spacer, but negative values on the upper spacer. In case of horizontal spacers, the local spacer Nusselt numbers show positive values on the upward surface of spacer, but negative values on the downward surface of spacer. The mean tube Nusselt numbers and mean cylinder Nusselt numbers with vertical spacer are increased 10% and 2.1%, respectively by those of horizontal spacer.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.4
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• pp.257-267
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• 1990

A numerical and experimental investigation has been carried out to understand a characteristic of natural convection within a horizontal non-circular annulus. A finite-difference method has been used to solve the governing equations numerically. The effect of Rayleigh number. Prandtl number, aspect ratio and diameter ratio is studied analytically. The ranges of the parameters studied herein are Rayleigh number from $10^3$ to $2{\times}10^4$, Prandtl number from 0.1 to 10, aspect ratio from 0.25 to 1.5 and diameter ratio from 1.5 to 9.0. A Mach-Zehnder interferometer is used to obtain isothermal fringes for a diameter ratio Do/Di=2.6 and aspect ratio H/L=0.75 experimentally. A comparison between the experimental and numerical results under similar conditions shows good agreement.

• Proceedings of the Acoustical Society of Korea Conference
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• 1996.06a
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• pp.9-12
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• 1996

This paper introduces an analysis of the non-axisymmetric mode due to in-plane vibration of an annular type piezoelectric actuator using FEM(Finite Element Method). The actuator is used as stator of ultrasonec motor. The freqrency charecterisrics and non-axisymmetric mode of the annular piezoelectric acruator are considered at a steady-state condition. The non-axisymmetric mode is occured by two sinusodial voltage sources with $\pi$/2 phase difference on the time domain. The resonant frequency of non-axisymmetric of non-axisymmetric mode is 60.358 kHz and 59.880 kHz for calculation and measurement, respectivly. The error was 0.8% between calculation and measurement. The revolution of the non-axisymmetric mode for actuator is analized at a period of exciting voltage sources using annimation. It is confirmed that the actuator has an usefulness as the stator of ultrasonic motor and the preposed method has a properity.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.3
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• pp.81-88
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• 1993

This report describes the experimental research on the flow phenomena of the aq uaous polymer solution within the Cuette flow of the concentric, cylinders type with a wide circular gap. We have investigated the phenomena of the fluid flow through torque measuring in the system that the inner cylinder is stationary and the outer one is rotating. Geometrical parameters of the system are the gap ratio of t/R$_{0}$=0.2 and Aspect ratio of l/t=100. The torque increases considerably in about 420-480RPM, So, it is considered a turbulent transition boundary, the higher plymer concentration is, the lower torque value is and the higher transition Reynolds number is. In each of the polymer concentration, the unstable boundary of torque, that is, idiosyncrasies of torque is observed around 220-280RPM. and the boundary is looked upon as a resonant vibration which is caused by the inner cylinder and tortional vibration of torque sensor.r.