• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.502-506
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• 2005

Three EGCG analogues were synthesized by the acceptor reaction of a glucansucrase from Leuconostoc mesenteroides B-1299CB with EGCG and sucrose. The transfer products was purified using Sephadex LG-20 column chromatography and high performance liquid chromatography (HPLC). EGCG-G1 and EGCG-G2 were novel compounds for the first time reported in this paper. EGCG glycosides showed similar or slower antioxidative effects according to their structures $(EGCG{\geq}EGCG-G1>EGCG-G1'>EGCG-G2)$. However, the water solubilities of the EGCG-G1, EGCG-G1' and EGCG-G2 were 52, 76 and 140 times higher than that of EGCG. Furthermore, they showed more browning resistance against UV irradiation than EGCG.

• 전기화학회지
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• 제2권3호
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• pp.163-170
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• 1999

AFC 단전지에서 운전조건의 영향은 이제까지 자세히 연구된 바 없다. 본 연구에서는 초기 전해질 농도와 가스 운전압력의 영향을 살펴보기 위하여 1차원 등온 모델을 이용해 전산모사를 수행하였다. 결과에 의하면, base-case에서 최적 전해질 농도는 $3.0\~3.5M$사이에 있는 것으로 발견되었다. 전해질 농도에 따른 전지 성능의 변화는 주로 양쪽 전극의 전하전달 저항과 용해된 기체의 헨리상수 및 액상확산이 원인인 것으로 밝혀졌다. 또한, 운전 압력의 증가는 반응속도와 가스의 용해도를 증가시켰으며, 이것으로 인해 전지 성능이 상당히 향상되는 것으로 조사되었다

• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.951-961
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• 2001

The present article presents an extension to the computational model for spray/wall interaction and liquid film processes that has been dealt with in the earlier studies (Lee and Ryou, 2000a). The extensions incorporate film spread due to impingement forces and dynamic motion induced by film inertia to predict the dynamic characteristics of wall films effectively. The film model includes the impingement pressure of droplets, tangential momentum transfer due to the impinging droplets on the film surface and the gas shear force at the film surface. Validation of the spray/wall interaction model and the film model was carried out for non-evaporative diesel sprays against several sources of experimental data. The computational model for spray/wall interactions was in good agreement with experimental data for both spray radius and height. The film model in the present work was better than the previous static film model, indicating that the dynamic effects of film motion should be considered for wall films. On the overall the present film model was acceptable for predication of the film radius and thickness.

• 대한기계학회논문집B
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• 제23권10호
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• pp.1254-1264
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• 1999

A three-dimensional coupled turbulent fluid flow and solidification process were analyzed in a continuous casting process of a steel slab with Electromagnetic Brake(EMBR). A revised low-Reynolds number $k-{\varepsilon}$ turbulence model was used to consider the turbulent effects. The enthalpy-porosity relation was employed to suppress the velocity within a mushy region. The electromagnetic field was described by Maxwell equations. Tile application of EMBR to the mold region results in the decrease of the transfer of superheat to the narrow face, the increase of temperature in free surface region and most liquid of submold region, and the higher temperature gradient near the solidifying shell. The increasing magnetic flux density effects mainly to the surface temperature of the solidifying shell of narrow face, hardly to the one of wide face. It is seen that in the presence of EMBR a thicker solidifying shell is obtained at the narrow face of the slab.

• 한국가시화정보학회지
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• 제15권1호
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• pp.11-18
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• 2017

A two-phase flow observed in a heat exchanger or nuclear power generation often has a profound effect on undesirable noise or flow characteristics. Void fraction, which refers to the ratio of gas (or liquid) to the total fluid, affects heat transfer coefficient, vibration and so forth. In other words, void fraction is one of most important parameters in two-phase flow since it contributes to comprehend the characteristics of two-phase flow. We developed a two-phase flow visualization system to measure cross-sectional and volumetric void fractions by using quick closing valves and image processing software. With this system, we could observe the plug, slug, and stratified flow patterns of two-phase flow and measure a myriad of void fractions. As a consequence of the experiment, we found that the estimated void fractions were largely coincident with the predictive values by Chisholm model.

• Molecular & Cellular Toxicology
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• 제1권2호
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• pp.87-91
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• 2005

Although 2D-PAGE has been widely used as the primary method for protein separation, difficulties in displaying proteins with an extreme values of isoelectric paint (pI), molecular size and hydrophobicity limit the technique. In addition, time consuming steps involving protein transfer and extraction from the gel-pieces can result in sample loss. Here, we describe a novel protein separation technique with capillary size-exclusion chromatography (CSEC) for rapid protein identification from human plasma. The method includes protein fractionation along with molecular size followed by in-solution tryptic digestion and peptide analysis through reversed phase liquid chromatography (RPLC) coupled to nanoflow electrospray-tandem mass spectrometry (ESI-MS/MS). Tryptic peptides are applied an a $100\;{\mu}m\;i.d.{\times}10mm$ length pre-column and then separated on a $75\;{\mu}m{\times}200mm$ analytical column at -100 nL/min flaw rate. Proteins were identified over the wide ranges of pI (3.7-12.3) when this technique was applied to the analysis of $1-2\;{\mu}L$ of human plasma. This gel-free system provides fast fractionation and may be considered a complementary technique to SDS-PAGE in proteomics.

• Journal of Advanced Marine Engineering and Technology
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• 제36권1호
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• pp.64-71
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• 2012

An efficient cooling system is an essential part of the electronic packaging such as a high-luminance LED lighting. A special technology, Pulsating Heat Pipe (PHP), can be applied to improve cooling of a sealed, explosion-proof LED light fixture. In this paper, the characteristics of the pulsating heat pipes in the imposed thermal boundary conditions of LED lightings were experimentally investigated and a PHP device that works free of alignment angle was investigated for cooling of explosion-proof LED lights. Five working fluids of ethanol, FC-72, R-123, water, and acetone were chosen for comparison. The experimental pulsating heat pipe was made of copper tubes of internal diameter of 2.1 mm, 26 turns. A variable heat source of electric heater and an array of cooling fins were attached to the pulsating heat pipe. For the alignment of the heating part at bottom, an optimum charging ratio (liquid fluid volume to total volume) was about 50% for most of the fluids and water showed the highest heat transfer performance. For the alignment of the heating part on top, however, only R-123 worked in an un-looped construction. This unique advantage of R-123 is attributed to its high vapor pressure gradient. Applying these findings, a cooling device for an explosion-proof type of LED light rated 30 W was constructed and tested successfully.

• 설비공학논문집
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• 제6권4호
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• pp.399-405
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• 1994

Beacuse of the energy resources exhaustion, the aggravating environmental air pollution and the smoke phenomena etc., the importance of clean gas fuel compared with liquid fuel is highly considered in recent years. The combustion system which consists of porous media is actively studied as a new method for solving above problems. Therefore, excess enthalpy combustion using porous media was interested by many researchers and investigated through numerical and experimental analysis. In this study, the simplified combustor has the unique combustion characteristics of mixture gas preheated effect using radiative and convective heat energy by changing the flow passage of unburned gas with solenoid valves and has the intensive excess enthalpy phenomena As the result of according to reduce equivalence ratio, flame temperature was remarkably higher than adiabatic flame temperature. This show the ability of super-lean combustion.

• 센서학회지
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• 제1권1호
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• pp.35-41
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• 1992

기체와 액체의 유숙을 측정하기 위한 반도체 기술을 이용한 소형의 정온도형 유속센서가 제작되었다. 유속센서는 유속에 영향을 받는 대류 열전달만을 검출하도록 설계되었고, 다른 종류의 열전달과 간섭효과는 기준센서의 사용으로 상쇄되도록 하였다. 원리는 유동에 의한 센서 양단전류의 변화로 유속을 측정하는 것이다. 이 유속센서의 실험은 수돗물로 가는 관(지름 8mm)을 사용하여 수행되었다. 그 결과 센서의 소비전력과 유속의 제곱근 사이의 관계는 유속이 0-200cm/sec 범위에서 거의 선형으로 나타났다.

• 식물조직배양학회지
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• 제22권2호
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• pp.115-120
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• 1995

국내품종인 동진벼와 태백벼의 미숙접합자배 유래 배발생 현탁배양 세포의 초저온 보존 시스템을 개발하였다. 동결/해동 후 캘러스 재생률은 동진벼의 경우 2 M DMSO와 0.4 M sucrose를 태백벼의 경우 0.64 M DMSO와 0.4 M sucrose를 혼용처리하였을 때 캘러스 재생률이 각가 88%와 90%로 가장 높았다. 또한 고농도의 삼투용액에서 배양세포 의 전처리 과정은 필요하지 않았다. 재생된 캘러스를 1 mg/L NAA와 5 mg/L kinetin이 첨가 된 $N_{6 }$, 배지로 이식하여 명배양하였을 때 체세포배발생을 통하여 다수의 유식물체가 발달하였다. 약 100여개의 식물체가 재분화되었으며, 이중 25%는 albino이었다.다.