산화환원 화학 종이 단 분자 층으로 화학 흡착된 전극에서의 전기화학적 정류

이치우,윤정현,오미경,Lee, Chi-Woo J.,Yoon, Jung-Hyun,Oh, Mi-Kyung 한국전기화학회 2007 한국전기화학회지 Vol.10 No.1

산화환원 화학 종이 화학적으로 흡착 된 전극에서의 전자 이동 현상은 흡착 화학 종이 전극표면에 흡착 되기 전과는 다르게 흡착 된 산화환원 화학 종의 전자 이동 특성에 전적으로 의존한다. 이러한 전극 표면에서의 전자이동에 관한 기본적인 변화는 전자 이동 현상에 관한 기초 연구를 넘어 전기화학 촉매, 전기화학적 바이오센서, 분자전자공학 등에 유용한 지식이 되고 있다. 본 고에서는 산화환원 화학 종이 자기 조립 막을 형성하여 화학적으로 흡착 된 전극을 사용 할 때 전극/용액 계면에서 관측 되는 전기화학 정류 전류와 전압 사이의 관계에 대한 상관관계를 소개 한다. Electrochemical rectification at electrode chemically modified with redox active agents isolated at monolayer level was considered. Formulation of the rising part of linear sweep voltammogram at steady and rotating disc electrode was introduced.

돌출높이와 초기온도 변화에 따른 연소실 벽면에서의 열유속에 관한 연구

이치우,Lee Chi-Woo 한국마린엔지니어링학회 2004 한국마린엔지니어링학회지 Vol.28 No.7

As for the Production of internal combustion engines there has been further movement toward development of high Performance engines with improved fuel efficiency as well as a lightweight and a small size. These tendencies help to solve the problems in engines for example, such as thermal load. abnormal combustion and so on. In order to investigate these Problems, a thin film-type probe for measuring instantaneous temperature has been suggested. A method for manufacturing such a probe was established in this study The instantaneous surface temperature of a constant volume combustion chamber was measured by using this probe and the heat flux was obtained through Fourier analysis In order to thoroughly understand the characteristics of combustion. authors measured wall temperature of combustion chamber and calculated heat flux through a cylinder wall while varying the protrusion height of probe. For these Purposes, the instantaneous surface temperature probe was developed. thereby making possible the analysis of instantaneous temperature of wall surface and the detection of unsteady heat flux in the constant volume combustion chamber.

해양구조물용 고압 컨트롤 밸브에 대한 기초 연구

이치우,장성철,Lee, Chi-Woo,Jang, Sung-Cheol 한국생산제조학회 2010 한국생산제조학회지 Vol.26 No.1

This study have goal with conceptual design for Offshore Structures of high pressure control valve for localization. Ball valve for development accomplished with flow analysis based on provision of ANSI B16.34, ANSI B16.10, ANSI B16.25 In order to localize the Offshore Structures high pressure control valve. Numerical simulation using CFD (Computational Fluid Dynamic) in order to predict a mass flow rate and a flow coefficient form flow dynamic point of view. The working fluid assumed the glycerin (C3H8O3). The valve inlet and outlet setup a pressure boundary condition. The outlet pressure was fixed by atmospheric pressure and calculated until increasing 1bar to 10bar. CFD analysis used STAR-CCM+ which is commercial code and Governing equations were calculated by moving mesh which is rotated 90 degrees when ball valve operated opening and closing in 1 degree interval. The result shows change of mass flow rate according to opening and closing angle of valve, Flow decrease observed open valve that equal percentage flow paten which is general inclination of ball valve. Relation with flow and flow coefficient can not be proportional according to inlet pressure when compare with mass flow rate. Because flow coefficient have influence in flow and pressure difference. Namely, flow can be change even if it has same Cv value. The structural analysis used ANSYS which is a commercial code. Stress analysis result of internal pressure in valve showed lower than yield strength. This is expect to need more detail design and verification for stem and seat structure.

STM 이미지와 산소 흡탈착 그리고 N-docosyl-N'-methyl viologen의 흡착으로부터 구한 다결정 금 전극 표면의 거칠기의 비교

이치우,장재만,Lee Chi-Woo,Jang Jai-Man 한국전기화학회 2000 한국전기화학회지 Vol.3 No.2

전기화학에 있어서 전극 물질의 실제 거칠기(real roughness)를 아는 것은 매우 중요하다. 그러나 여러 가지 이유 때문에 전극 물질의 절대적인 거칠기를 아는 것은 불가능하다. 여기에서는 scanning tunneling microscopy (STM), 순환전압전류법을 이용하여 전기화학에서 자주 사용하는 다결정 금 전극의 거칠기를 구하여 Au(111), HOPG로부터 구한 거칠기와 비교해 보았다. STM으로부터 얻은 다결정 금전극의 거칠기는 $1.1(\pm0.1)$,산소의 탈착으로부터는 $2.4(\pm0.7)$, N-docosyl-N'-methyl viologen의 흡착으로부터 는 $1.6(\pm0.1)$이 얻어졌다. It is very important to know the real roughness of electrode surface in electrochemistry. But it is impossible to know absolute roughness of electrode surface for various reasons. In this work, we compared the roughnesses of polycrystalline gold electrode often used in electrochemistry calculated from the images of scanning tunneling microscopy (STM) and cyclic voltammetry with those of Au (111) and HOPG. The roughness of polycrystalline gold calculated from STM image was $1.1(\pm0.1)$, that from adsorption-desorption of oxygen was $2.4(\pm0.7)$ and that from adsorption of N-docosyl-N'-methyl viologen was $1.6(\pm0.1)$.

물에 사는 작은 생물을 활용한 환경교육

이치우(Chi Woo Lee),박종근(Jong-Geun Park) 한국환경교육학회 2014 한국환경교육학회 학술대회 자료집 Vol.2014 No.12

가솔린 엔진(3.8L)에서 바이오에탄올 혼합연료의 성능 및 배출특성에 관한 연구

이치우(Chi-Woo Lee) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.4

This article is about using the fuel mixed with 10% and 20% bio-ethanol to gasoline for the engine as a way to reduce carbon emission before commercializing future automobiles like fuel cell cars. The fuel mixed with 10% and 20% bio-ethanol showed output equivalent to that of the previous gasoline fuel. CO and CO2 emission was somewhat reduced, but the difference was not significant. And the consumption of the fuel increased slightly. However, bio-ethanol is produced from bio mass growing with the absorption of carbon dioxide, so the total amount of carbon dioxide did not increase according to the result. In NOx, as the use of ethanol increases, the effect of reduction gets greater, and the emission of oxygen showed almost no change compared with gasoline.

PEI(Polyethyleneimine)를 이용하여 음이온계 레진에 고정화된 Lipase AH 제조 및 효소적 Interesterification을 통한 반응 특성 연구

이치우(Chi Woo Lee),이기택(Ki Teak Lee) 한국식품영양과학회 2014 한국식품영양과학회지 Vol.43 No.7

This study assessed the effect of immobilized lipase on weak base styrene resin using polyethyleneimine (PEI) with cross-linking. Two procedures were used in this study. The first one, “mono-layer” lipase immobilization, involves washing PEI after adsorption. The second procedure, “multi-layer” lipase immobilization, has no washing before the cross-linking step. Treverlite XS-100200 (weak base styrene resin) was immersed with PEI solution (2.2 mg/mL). Lipase AH (from Burkholderia cepacia) was adsorbed onto the support coated with PEI before cross-linking with glutaraldehyde. Structured lipid was synthesized by immobilized lipase-catalyzed interesterification using canola oil, palmitic ethyl ester (PEE), and stearic ethyl ester (StEE). Total fatty acid contents of triacylglycerol (TAG) in structured lipids were analyzed to investigate activity, properties, and reusability of immobilized lipases. Activities of immobilized lipases on the multi-layer and mono-layer increased at a high concentration (8 mg/mL) of lipase solution used for immobilization. The results show that immobilized lipase with the mono-layer method at pH 8.0 on resin had the highest total saturated fatty acid content (26.17 area%). Activity of immobilized lipase with the multi-layer method at pH 7.5 on support was lower than that of the mono-layer, but total saturated fatty acid content was 16.79 area% higher than that of lipase AH (15.01 area%).

열충격이 작용하는 취성구조의 신뢰성 평가

이치우(Chi-woo Lee),장건익(Kun-ik Chang),김종태(Jong-tae Kim) 한국해양공학회 1998 韓國海洋工學會誌 Vol.12 No.1

An analysis method for the reliability of ceramic structures subjected to thermal shocks is presented. Flaws with the size of given probability distribution function are assumed to be distributed at random with a certain density per unit volume in the structures. Criterions for crack instability are derived for brittle solids under general thermal stresses. A probabilistic failure model is presented to study the probability of crack instability for brittle solids containing cracks with uncertain crack size. The reliabilities of brittle structures are evaluated based on the weakest-link hypothesis, which states that a structure fails when the cracks in any differential volume become unstable. A numerical example is given to demonstrate the application of the proposed method.

다중압출공정을 이용하여 제조한 섬유상 HAp-(t-ZrO2)/Al2O3-(m-ZrO2) 복합소결체의 미세조직과 기계적특성

이치우 ( Chi Woo Lee ),윤민호 ( Min Ho Youn ),송호연 ( Ho Yeon Song ),이병택 ( Byong Taek Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 대한금속·재료학회지 Vol.44 No.6

Core-shell structured HAp-(t-ZrO2)/Al2O3-(m-ZrO2) composites were fabricated using a multi extrusion process. The shell of Al2O3-(m-ZrO2) phases was selected due to their excellent biocompatibility and mechanical properties and the core was designed with t-ZrO2 dispersed HAp matrix, In the 3rd passed sample, core/shell and fibrous microstructures having 4㎛ in diameter and 1㎛ in thickness were clearly observed. In the composite sintered at 1200℃, many pores were observed in both HAp-(t-ZrO2) core and Al2O3-(m-ZrO2) shell regions. However at 1500℃, the shell regions showed dense microstructure. The values of relative density, hardness, bending strength and fracture toughness in the sample sintered at 1500℃ were higher than those of 1200℃ and their maximum values were at 1500℃ about 95%, 967Hv, 278 MPa and 4.2 MPam(1/2), respectively. The fracture morphology was appeared with homogeneously rough surface due to the crack deflection and phase transformation of t-ZrO2 particles.

시뮬레이션에 의한 금속게이트 FD-SOI 와 MuGFET의 불소 이온 주입효과

이치우(Chi-Woo Lee),D. Lederer,A. Afzalian,Ran Yan,J.P. Colinge 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7

Fluorine (F) implantation creates negative charges at the Si/SiO₂ interface in FDSOI transistors[1]. This paper describes simulation of the influence of F Implant on Threshold Voltage(Vth) for Metal Gate FDSOI and MuGFETs using FEMLAB<SUP>ⓡ</SUP> The origin of the large V th shift observed in planar FDSOI due to is the creation of negative charge states in the BOX by the F implant. F implant is a suitable approach for planar FDSOI SoC integration with single work function (WF) metal gate, but NOT for MuGFETs.