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Printed cylindrical lens pair for application to the seam concealment in tiled displays
Lee, Seunghwan,Lee, Seungjae,Yoon, Hyungsoo,Lee, Chang-Kun,Yoo, Chanhyung,Park, Jongjang,Byun, Junghwan,Kim, Geonhee,Lee, Byeongmoon,Lee, Byoungho,Hong, Yongtaek The Optical Society 2018 Optics express Vol.26 No.2
Effects of External Humidification on the Performance of a Polymer Electrolyte Fuel Cell
Yongtaek Lee,Yongchan Kim,Yonghee Jang,Jong Min Choi 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.12
The dryness of the membrane of a polymer electrolyte fuel cell (PEFC) decreases the ionic conductivity, resulting in performance reduction. In this study, the effects of external humidification to the membrane were investigated by vary-ing the humidification side such as anode humidification, cathode humidification, and both anode and cathode humidification (called as both-side humidification). The amount of required water vapor into the gas was increased rapidly to maintain the relative humidity constant with the increase of cell temperature. The best performance of the cell was achieved by both-side humidification. However, as the humidity condition approached saturation state, anode humidification yielded comparable performance to both-side humidification. In anode humidification, the increase of the cell temperature degraded the performance, even though the amount of water supply to the membrane remained constant. At constant relative humidity conditions with anode humidification, the polarization curves of the PEFC were almost the same, regardless of the cell temperature when the relative humidity was higher than 60%.
탄산칼륨 수용액 액막을 통한 이산화탄소의 촉진수송에 미치는 온도와 수송담체 농도의 영향
이규호,염봉열,박유인,이용택,이용희 한국화학공학회 1998 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.36 No.5
액막내에서 이산화탄소의 투과 거동을 예측하기 위하여 액막으로서 탄산칼륨 수용액을 선정하여 액막내의 아산화탄th와 관련된 가역반응을 고려한 시스템 지배방정식의 모델해석을 수행하였다. 모델해석에 사용된 반응속도상수, 평형상수, 용해도 그리고 확산계수를 탄산이온의 농도와 온도의 함수로 나타내었으며, 문헌값을 통하여 특정조건에서의 예측값을 확인하였다. 액막에서 이산화탄소의 투과에 영향을 미치는 중요한 인자들인 액막의 두께, 이산화탄소의 부분압력, 수송담체의 농도, 그리고 시스템의 온도를 실행 변수로 하여 이산화탄소의 투과속도를 예측할 수 있었다. 각각의 경우에 대하여 반응에 의한 이산화탄소의 투과속도 증가를 전체 이산화탄소의 투과속도와 촉진인자로 표현할 수 있었으며, 탄산칼륨 수용액내에서의 반응에 의하여 이산화탄소의 투과속도가 상당히 증가함을 알 수 있었다. 또한 온도가 증가함에 따라 전반적으로 투과속도와 함께 촉진인자가 증가함을 알 수 있었으며, 본 연구를 통해 액막에서의 이산화탄소 투과에 대한 수송담체의 농도와 온도를 포함한 효율적인 운전조건들을 제시할 수 있었다. Model analysis was carried out using the system controlling equations which include the reversible reactions of carbon dioxide with potasaium carbonate to predict the permeation behavior of carbon dioxide in a potassium carbonate liquid membrane. The physicochemical properties of reaction rate constants, equilibrium constants, solubility and diffusion coefficient were represented as a function of the concentration of carbonate ion and the temperature; the calculated solubility and the predicted diffusion coefficient were found to be identical to those published data. The permeation rates could be successfully predicted with several important parameters : the thickness of liquid membrane, the partial pressure of carbon dioxide, the concentration of carrier and the temperature. The increment of the permeation rate was represented in terms of the facilitation factor as a function of carrier concentration, It was found that the permeation rate of carbon dioxide increases significantly as the concentration of carrier increases. The facilitation factor considerably increases together with the permeation rate as the temperature increases. The effective operating conditions could be obtained through this model analysis for the permeation rate as well as the facilitation factor of carbon dioxide across the liquid membrane.
Rational Design of Extractive Distillation Toward Enhanced Separation of HFPO from HFP/HFPO Mixture
Lee, Yongtaek The Korean Society of Clean Technology 2018 청정기술 Vol.24 No.1
Hexafluoropropyleneoxide ($C_3F_6O$, HFPO) is highly expensive and it may be used as a raw material for the synthesis of various fluorine based compounds. Currently, extractive distillation method has gained considerable attention to collect the HFPO from a mixture of HFPO / hexafluoropropylene ($C_3F_6$, HFP). Optimized operating conditions are studied using a theoretical method for the extraction process. Among available solvents for the purification process, the use of 1,1-dichloro-1-fluoroethane exhibits a high purity of HFPO as a top product and minimize the required heat duty. Since the boiling point of the solvent increases as the pressure in the column increases, the enhanced extractive capability of the solvent led to the high purity of HFPO at the high pressure.
Lee, Ju-Young,Joo, Bitna,Nam, Jin Han,Nam, Hye Yeon,Lee, Wonil,Nam, Youngpyo,Seo, Yongtaek,Kang, Hye-Jin,Cho, Hyun-Ji,Jang, Young Pyo,Kim, Jeongyeon,We, Young-Man,Koo, Ja Wook,Hoe, Hyang-Sook Frontiers Media S.A. 2018 FRONTIERS IN AGING NEUROSCIENCE Vol.10 No.-
<P>Recent studies have shown that Liuwei Dihuang pills (LWPs) can positively affect learning, memory and neurogenesis. However, the underlying molecular mechanisms are not understood. In the present study, we developed ALWPs, a mixture of <I>Antler</I> and LWPs, and investigated whether ALWPs can affect neuroinflammatory responses. We found that ALWPs (500 mg/ml) inhibited lipopolysaccharide (LPS)-induced proinflammatory cytokine IL-1β mRNA levels in BV2 microglial cells but not primary astrocytes. ALWPs significantly reduced LPS-induced cell-surface levels of TLR4 to alter neuroinflammation. An examination of the molecular mechanisms by which ALWPs regulate the LPS-induced proinflammatory response revealed that ALWPs significantly downregulated LPS-induced levels of FAK phosphorylation, suggesting that ALWPs modulate FAK signaling to alter LPS-induced IL-1β levels. In addition, treatment with ALWPs followed by LPS resulted in decreased levels of the transcription factor NF-κB in the nucleus compared with LPS alone. Moreover, ALWPs significantly suppressed LPS-induced BV2 microglial cell migration. To examine whether ALWPs modulate learning and memory <I>in vivo</I>, wild-type C57BL/6J mice were orally administered ALWPs (200 mg/kg) or PBS daily for 3 days, intraperitoneally injected (i.p.) with LPS (250 μg/kg) or PBS, and assessed in Y maze and NOR tests. We observed that oral administration of ALWPs to LPS-injected wild-type C57BL/6J mice significantly rescued short- and long-term memory. More importantly, oral administration of ALWPs to LPS-injected wild-type C57BL/6J mice significantly reduced microglial activation in the hippocampus and cortex. Taken together, our results suggest that ALWPs can suppress neuroinflammation-associated cognitive deficits and that ALWPs have potential as a drug for neuroinflammation/neurodegeneration-related diseases, including Alzheimer’s disease (AD).</P>
Rational Design of Extractive Distillation Toward Enhanced Separation of HFPO from HFP/HFPO Mixture
Yongtaek Lee 한국청정기술학회 2018 청정기술 Vol.24 No.1
Hexafluoropropyleneoxide (C3F6O, HFPO) is highly expensive and it may be used as a raw material for the synthesis of various fluorine based compounds. Currently, extractive distillation method has gained considerable attention to collect the HFPO from a mixture of HFPO / hexafluoropropylene (C3F6, HFP). Optimized operating conditions are studied using a theoretical method for the extraction process. Among available solvents for the purification process, the use of 1,1-dichloro-1-fluoroethane exhibits a high purity of HFPO as a top product and minimize the required heat duty. Since the boiling point of the solvent increases as the pressure in the column increases, the enhanced extractive capability of the solvent led to the high purity of HFPO at the high pressure.
이용택(Yongtaek Lee),이원희(Wonhee Lee),장하늘(Haneul Jang) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
A CO₂ incubator is a device used for culturing, growing, and maintaining cells or microorganisms, and it is necessary to precisely maintain the optimum temperature, humidity, and CO₂ concentration in the internal atmosphere for cell growth. Through the benchmarking of the existing CO₂ incubator, internal flow and transient heat transfer were observed through computational analysis. Variation of the temperature distribution inside the chamber was observed when the air was heated from the 6 sides surrounding the chamber. After 8 seconds from the start of heating, the vicinity of the wall was heated to 67 ℃, but the temperature of the tray on which the sample would be placed did not reach the target temperature of 37 ℃. It is expected that the results of this study will be utilized in determining the control logic of the heating unit and the temperature measuring location during product development.