• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.762-767
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• 1998

The main torsional vibration source of the powertrain is the fluctuation of engine torque. The gear rattle is impact generating in the backlash of the free gear due to this torsional vibration. Optimization of the clutch torsional characteristic is one of the effective method to reduce the idle gear rattle. Many researches have been reported on this problem but only few of them give sufficient consideration to the detailed clutch modeling and the experiment. This paper pays attention to the optimization of clutch design parameters and the experiment to reduce the idle gear rattle vibration and noise.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.743-752
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• 1998

Numerical analysis for the flow and heat transfer in solid particle moving beds of heat exchangers is presented. The solid particle flow through the bundle of heat source tubes by the gravitational force. The heat energy is transferred through the direct contact of particles with the heat source tubes. The viscous-plastic fluid model and the convective heat transfer model are employed in the analysis. The flow field dominantly influences the total heat transfer in a heat exchanger. As the velocities of solid particles around the heat source tubes increase, the amount of heat transfer from the tubes increases. Some examples are presented to show the performance of the numerical model. The flow effect on the heat transfer is also studied through the examples.

• Publications of The Korean Astronomical Society
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• v.22 no.2
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• pp.35-41
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• 2007

We present the result of radial velocity observation of a W UMa type binary star EX Leo. We observed the star on February 16, 2003, using Long-Slit spectrograph of BOAO(Bohyunsan Optical Astronomical Observatory). Since the spectral lines are broad due to its fast rotation, it is difficult to distinguish two radial velocities from cross correlation function. Instead of cross correlation function, we used broadening function to develop our own code which estimate the radial velocity of the broadened line spectra. With our own code, radial velocities of primary and secondary stars are derived simultaneously. From the radial velocity curve fit, we obtained $K_1=50.24{\pm}8.29km/s$ and $K_2=254.05{\pm}20.984km/s$ respectively.

• Textile Coloration and Finishing
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• v.22 no.4
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• pp.293-299
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• 2010

A methacrylate monomer having phospholipid polar group and cell membrane structure is known as highly biocompatible. Based on these properties, new biocompatible multi-functional textile finishing agent was developed using phospolipid copolymer. 2-Methacryloyloxyethyl phosphorylcholine (MPCE) was synthesized using 2-hydroxyethyl methacrylate (HEMA), 2-chloro-2-oxo-1,3,2-dioxaphospholane (COP) and triethylamine (TEA), and then polymerized to prepare MPCE copolymer by radical polymerization using azobisisobutyronitrile(AIBN). The structures of MPCE was characterized by FT-IR and 1H NMR and will be evaluated as textile finishing agent in further study.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.3
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• pp.17-22
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• 1986

This paper investigates on the performance of liquid magnetic compass measuring the concomitant angle of the directional system by the kind of compass and the coefficiant of viscosity of the liquid of ones in accordance with the turning angular velocity of the compass bowl in artificial horizontal magnetic fields. The obtained results are as follows; 1. The concomitant angle is to be in proportion to the coefficiant of viscosity of the liquid of compass and the turning angular velocity of the compass bowl, but ones is to be in contrary proportion to the magnetic moment of the magnetic needle and the horizontal geomagnetic. 2. The overdevelopment of the concomitant angle keeps on regularly at any optional degree in the turning angular velocity over$\pi$ radian per minute, but varies periodically at 180 degree below 3 $\pi$ radian per minute.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.4
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• pp.358-364
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• 2012

This work dealt with dynamic characteristics of spur gear and helical gear system to understand the gear vibration and noise. To find out dynamic characteristics in the gear system, a finite element model and an analytic model for the gear system were used. Using the models, the natural frequency and mode-shape characteristics of spur gears and helical gears were calculated. Two models show that natural frequencies of helical gears were lower than those of spur gears. Mode-shape characteristics of gear pairs by analytical model and some issues of finite element modeling were also discussed. Impact test was used to validate the finite element model.

• Natural Product Sciences
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• v.1 no.1
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• pp.43-49
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• 1995

Two cucurbitane-compounds were isolated from the roots of Bryonia alba L. and the chemical structures were established as 19-norlanost-5-ene-3,1l,22-trione-$2{\beta}$, $16{\alpha}$,$20{\beta}$,25-tetrahydroxy-9-methyl (23,24-dihydrocucurbitacin D) and 2-O-${\alpha}$-D-glucopyranosyl 19-norlanost-5-ene-3,11,22-trione-$2{\beta}$,$16{\alpha}$,$20{\beta}$,25-tetrahydroxy-9-methyl (arvenin IV), respectively, on the basis of chemical and spectral methods. Both of the compounds showed cytotoxic activity against cancer cell lines, A549, SK-MEL-2, COLO 205 and L1210.

• Korean Journal of Medicinal Crop Science
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• v.22 no.4
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• pp.262-269
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• 2014

Complex of mulberry extract (CME) is composed of extracts of mulberry (Morus alba L.) fruit, mulberry leaves and black beans (Glycine max (L.) Merr.). In this study, we investigated prevention effects of CME on degenerative arthritis. The $SC_{50}$ value of DPPH radical scavenging by CME was $158.49{\pm}11.35{\mu}/mL$. We found that CME significantly reduced the production of nitric oxide (NO) and protein expression of cyclooxygenase-2 (COX-2) in RAW 264.7 cells which were activated by LPS. Experiments using animal model of degenerative arthritis showed that CME (400 mg/kg body weight) inhibited the production of TNF-${\alpha}$ (77.5%) and IL-$1{\beta}$ (95.0%). Furthermore, it was observed that CME reduced to 85.9% of paw edema induced by carrageenan. These results suggest that CME could improve degenerative arthritis.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.22.2-22.2
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• 2011

Si 나노와이어를 합성하는 다양한 방법들 중에서 Si 기판을 나노와이어 형태로 제작하는 무전해 식각법은 쉽고 간단하기 때문에 최근 많은 연구가 진행되고 있다. 무전해 식각법을 이용한 Si 나노와이어는 p 또는 n형의 전기적 특성을 갖는 Si 기판의 도핑농도에 따라 원하는 전기적 특성을 갖는 나노와이어를 얻을 수 있을 것이라는 기대가 있었지만 n형으로 제작된 나노와이어의 경우 식각에 의한 표면의 거칠기 때문에 그 특성을 나타내지 못하는 문제점을 가지고 있다. 본 연구에서는 무전해 식각법을 이용하여 p와 n형 나노와이어를 합성하고 field-effect transistors (FETs) 소자를 제작하여 각각의 특성을 구현하였다. 나노와이어와 절연막 사이의 계면 결함을 최소화하기 위하여 poly-4-vinylphenol (PVP) 고분자 절연막에 나노와이어를 삽입시킨 형태로 소자를 제작하였고, 특히 n형 나노와이어의 표면을 보다 평평하게 하기 위하여 열처리를 진행 하였다. 이렇게 각각의 특성이 구현된 나노와이어를 이용하여 soft-lithography 공정을 통해 complementary metal-oxide semiconductor (CMOS) 구조의 인버터 소자를 제작하였으며 그 전기적 특성을 평가하였다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.5
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• pp.342-348
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• 2011

This study analyzes the current and after retrofit energy consumption of lighting and cooling system of a superstore in Seoul. Energy consumption data were measured and collected with a measurement system. Annual energy consumption was calculated using TRNSYS program. After replacing lighting and chiller with higher efficiencies, annual TOE consumption decreased from 1,066 before retrofit to 832 after retrofit, saving 234 TOE (22%) in total. Similarly, total annual $TCO_2$ consumption decreased from 2,214 to 1,721, reducing 493 $TCO_2$ (22%) during this pilot study.