• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.433-438
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• 2002

The flow field around a symmetrical airfoil in a uniform flow under the generation of noise was numerically studied and compared with experimental datum. The numerical simulation was carried out by LES which employs a deductive dynamic model as subgrid-scale model. The result of an attack angle of $6^{\circ}$ indicate that the discrete frequency noise is generated when the separated laminar flow reattaches near the trailing edge of the pressure side and the turbulent boundary layer is formed over the suction side of the airfoil near the trailing edge. The periodic behavior of vortex formation was observed around the trailing edge and it persists further downstream in the wake. The frequency of the vortex formation in the wake was consistent with that of the discrete frequency noise.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.504-507
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• 2009

The purpose of this work is to predict the low frequency aero-acoustic noise generated from the horizontal axis wind turbine, NREL Phase VI using large eddy simulation and Ffowcs-Williams and Hawkings model provided in the commercial code, FLUENT. Calculated aerodynamic performances such as shaft torque and power are compared with experimentally measured value. Performance results show a good agreement with experimental data within about 0.8%. If the distance by two times is changed from 32D to 64D toward the downstream region, sound pressure level is reduced by about 6.4dB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.762-767
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• 2001

LES formulation was applied to simulate the flow fields around rotating fan blades tested by DLR. The turbulent flows around fan blade rotating with 500 RPM were simulated and the far-field noise was exactly computed by using the Focus Williams and Hawkings equation with an inclusion of quadrapole source formulation. The dipole noise computed at the far-field by predicted drag and lift forces at steady state was in good agreement with experimental data and the dipole source was also found to be the major factor than other sound sources from unsteady calculation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.768-773
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• 2001

The self-noise from blade cascade at off-design points mainly comes from separated boundary layer and vortex sheddings, and is also dependent on blade shape. If the incidence angle to the cascade increases, the stalling in blades may occur and the noise level increases significantly. The hybrid method using acoustic analogy was employed to compute the far-field noise spectra and directivity patterns from the separated vortex shedding at off-design points of the cascade of impeller. This paper is compared with the experimental data of a stationary cascade in the same conditions. The simulated result is in excellent .agreement with the measured data except th slight under-prediction near the maximum radiation angle for a dipole sound.

• Annual Conference on Human and Language Technology
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• 2001.10d
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• pp.365-372
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• 2001

한국어나 일본어는 영어 등 서구의 언어와 비교하여 매우 발달된 경어 체계를 가지고 있다. 그러나 이러한 경어 체계는 이들 언어를 모국어로 사용하지 않는 사람들을 포함하여 모국어로 사용하는 많은 사람들까지도 정확하게 구사하기는 어려워 하는 것이 현실이다. 그럼에도 불구하고 경어 체계의 정확한 구사 능력은 적절한 어휘 선택 능력과 함께 자연스러운 의사 소통을 위한 중요한 언어 능력으로 간주되고 있다. 특히 기계번역기나 문법검사기를 구현하고자 할 때 이러한 경어 체계를 정확하게 이해하는 시스템의 구현은 한 차원 높은 자연스러운 표현을 제공하기 위하여 필수적이라고 할 수 있다. 본 논문에서는 한국어의 경어 체계를 조사하고 결합범주문법을 통하여 이를 검증하는 시스템을 소개한 뒤 사극 대본을 대상으로 하여 이 시스템의 성능을 확인한다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1012-1013
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• 2015

포항가속기 연구소 PLS-II 저장링은 빔에너지 3.0 GeV, 빔전류 400 mA 그리고 5.8 mm-rad로 성능을 향상 하였다. 저장링 전체의 이극, 사극, 육극 및 셉텀 전자석의 구동을 위하여 디지털 제어기를 적용한 독립된 강압형 buck-converter를 인터리버 방식으로 응용한 고정밀 단방향 전자석전원장치를 개발 하였다. 이들 전자석전원장치의 출력전류 안정도는 +/-10 ppm 이하이다. 본 논문에서는 PLS-II 저장링의 단방향 전자석전원장치의의 설계 및 성능에 대하여 논하고자 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.8
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• pp.648-655
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• 2002

For a discharge system of rotary compressor, analytical investigation on the discharge gas pulsation has been carried out. With the aid of four pole theory, acoustic impedance of the discharge system composed of muffler and cavities on both sides of motor with gas passages between them can be calculated using discrete acoustic elements described by transfer matrices, yielding the relationship between discharge mass flow rate and gas pulsation at the discharge port. This method of predicting the gas pulsation was validated by measurement data. Effects of change in discharge muffler geometries on the gas pulsation also were investigated, demonstrating that this method can be used for muffler design.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.697-703
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• 2003

For a single stage two cylinder rotary compressor, an analytical study has been made on the discharge gas pulsation. Discharge system of the twin rotary compressor consists of lower and upper mufflers and connecting passage holes between them, and cavities on both sides of the motor and passages between them. Acoustic modeling for the discharge system by transfer matrix method gives acoustic impedances at discharge valves so that gas pulsation at the valve sections can be obtained from discharge mass velocity. Since the mass velocity and the pressure pulsation at the valves are affected by each other, iteration should be made for convergence. Gas pulsations at other sections can also be calculated by using transfer matrix.

• Korean Journal of Pharmacognosy
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• v.41 no.4
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• pp.308-312
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• 2010

The purpose of this research is to provide basic informations to discriminate between sea buckthorn (Hippophae rhamnoides) cultivated in the Republic of Korea and Mongolia. The phenolic compounds of sea buckthorn, were measured by the HPLC analysis. Catechin, rutin, quercetin, isorhamnetin were found in methanol extracts of sea buckthorn. Total phenolic compound of Korean sea buckthorn leaves (1.852%) was about five times higher than those of Mongolian sea buckthorn berries (0.338%). As a result, the order of the total phenolic compound and Catechin content was 1) sea buckthorn leaves, 2) sea buckthorn stems, 3) sea buckthorn roots, and 4) sea buckthorn berries. Statistically no big differences in levels of phenolic compounds were consistently found in sea buckthorn cultivated in the Republic of Korea and Mongolia investigated in this work.

• The Korean Journal of Mycology
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• v.9 no.1
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• pp.13-18
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• 1981

This study was performed to investigate the high yielding potential of Pleurotus ostreatus (Fr.) Quel derived from intermating and intramating of three strains: Local strain, Nonggi 201, and Pleurotus florida Eger. All the strains tested were tetrapola mating systems, and hybridable. Intermating system resulted in more fresh sporophores than those from intramating. The highest yield of fresh sporophores of P. ostreatus was obtained from Nonggi 201 crossed with P. florida, when cultivated on the rice straw substrates.