• 폴리머
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• 제34권6호
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• pp.540-546
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• 2010

본 실험실에서 연구되어진 poly(vinyl alcohol)(PVA)/poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) 이온교환막에 메탄올 투과도 감소를 위하여 실리카기를 함유하고 또한 프로톤 도너 역할을 할 수 있는 3-(trihydroxysilyl)-1-propanesulfonic acid(THS-PSA)를 도입하여 가교된 PVA/PSSA-MA/THS-PSA 막을 제조하였다. 제조된 막의 내구성 향상을 위하여 500 ppm $F_2$ 기체를 이용하여 시간에 따라 직접불소화를 실시하였으며, 불소기의 도입에 따른 막의 물리화학적 변화를 관찰하기 위하여 접촉각 특정, 열 중량분석 및 X-ray photoelectron spectroscopy(XPS)를 통해 확인하였다. 표면불소화된 PVA/PSSA-MA/THS-PSA막의 전기화학적 특성을 평가하기 위하여 함수율, 이온교환용량, 이온전도도, 메탄올 투과도 측정을 실시하여 상용화된 Nafion 115와 비교하였다. 불소화 시간이 증가함에 따라 도입된 불소의 함량은 최고 4.3%의 함량과 50 nm의 침투 깊이를 나타내었다. 불소화 시간이 60분 경과했을 때 이온전도도는 0.036 S/cm으로 Nafion 115의 0.024보다 향상되었으며, 메탄올 투과도는 $9.26E-08cm^2/s$으로 Nafion의 1.17E-06보다 감소되었음을 확인하였다. 또한 MEA를 제작하여 전류밀도에 따른 셀 전압을 측정하였다.

• 한국자기학회지
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• 제16권4호
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• pp.211-215
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• 2006

구조 강이나 터빈로터 강의 기계적 물성은 자기적 특성과 관계되므로, 비파괴적으로 자기적 특성을 측정하여 기계적 물성을 평가하는 연구가 많이 수행되었다. 따라서 자동차용 강판으로 사용되는 냉연강판에서도 비파괴적으로 자기적 특성을 측정함으로써 냉연강판의 기계적 물성을 유추할 수 있을 것이고, 냉연강판 생산 라인에서 자기적 특성을 측정하여 온라인상에서 냉연강판의 기계적 특성을 모니터할 수 있을 것이다. 기계적 특성이 다른 세 종류의 냉연강판 CBQ 3060, CBQ 3041 및 CBQ 3036의 시편을 준비하고 교류 섭동 자기장을 인가하여 자기적 특성인 가역투자율을 비파괴적으로 측정함으로서 기계적 물성인 경도와의 상관관계를 규명하였다. 세 종류의 냉연강판 시편에서 기계적 물성인 비커스 경도, 항복강도 및 인장강도를 측정하였다. 주파수가20 Hz일 때, surface type 프로브로 측정한 섭동자기장의 제 1차 고조파인 가역투자율의 피크 간 간격에서 구한 보자력은 비커스경도, 항복강도 및 인장강도가 증가할 때 선형적으로 증가하였다. 주파수 20 Hz에서 lift-off에 대한 가역투자율 측정을 하였는데,lift-off가 증가함에 따라 고조파의 amplitude가 급격히 감소하였다.

• 한국정보통신학회논문지
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• 제23권9호
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• pp.1131-1138
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• 2019

부품 또는 제품들의 정전기 방지와 내마모성 및 내부식성 향상, 미각화 등 다양한 목적으로 코팅의 중요성이 증가되고 있다. 코팅막의 두께를 측정하는 방법으로 주로 프로브(probe)로 코팅면을 측정하는 접촉식 측정방식이 이용되는데, 코어의 투자율 변화에 의해 센서 출력 왜곡이나 부하 현상이 발생하여 정확도가 떨어지는 문제점이 있다. 본 논문에서는 비선형적인 특성에 의해 발생할 수 있는 문제점을 최적화된 회로설계와 두께측정 알고리즘을 적용하여 코팅막의 측정 오차를 줄이는 방법을 제안한다. 여러 코팅 샘플을 통한 실험 결과 ${\pm}2%$ 이내의 측정 정확도를 갖는 것을 확인할 수 있다.

• Corrosion Science and Technology
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• 제4권4호
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• pp.121-129
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• 2005

Basic design concept of the future steel structure requires environmental compatibility and maintenance free capability to minimize economic burdens. Recent trends in alloy design for advanced weathering steel include addition of various alloying elements which can enhance formation of stable and protective rust layer even in polluted urban and/or high $Cl^{-}$ environment. The effects of Ca, Ni, W, and Mo addition on the corrosion property of Ca-modified weathering steel were evaluated through a series of electrochemical tests (pH measurement and electrochemical impedance spectroscopy: EIS) and structural analysis on rust layer formed on the steel surface. Ca-containing inclusions of Ca-Al-Mn-O-S compound are formed if the amount of Ca addition is over 25 ppm. Steels with higher Ca content results in higher pH value for condensed water film formed on the steel surface, however, addition of Ni, W, and Mo does not affect pH value of the thin water film. The steels containing a high amount of Ca, Ni, W and Mo showed a dense and compact rust layer with enhanced amount of ${\alpha}-FeOOH$. Addition of Ni, W and Mo in Ca-modified weathering steel shows anion-selectivity and contributes to lower the permeability of $Cl^{-}$ ions. Effect of each alloying element on the formation of protective rust layer will be discussed in detail with respect to corrosion resistance.

• Corrosion Science and Technology
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• 제5권4호
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• pp.117-122
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• 2006

Hydrogen permeation measurements have been carried out on API X65 grade linepipe steel. In order to study the effect of steel microstructure on hydrogen diffusion behavior in linepipe steel, the accelerated cooling condition was applied and then three different kinds of microstructures were obtained. Hydrogen permeation measurement has been performed in reference to modified ISO17081 (2004) and ZIS Z3113 method. Hydrogen trapping parameters in these steels were evaluated in terms of the effective diffusivity ($D_{eff}$), permeability ($J_{ss}L$) and the amount of diffusible hydrogen. In this study, microstructures which affect both hydrogen trapping and diffusion were degenerated pearlite (DP), acicular ferrite (AF), bainite and martensite/austenite constituents (MA). The low $D_{eff}$ and $J_{ss}L$ mean that more hydrogen can be trapped reversibly or irreversibly and the corresponding steel microstructure is dominant hydrogen trapping site. The large amount of diffusible hydrogen means that corresponding steel microstructure is predominantly reversible. The results of this study suggest that the hydrogen trapping efficiency increases in the order of DP, bainite and AF, while AF is the most efficient reversible trap.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권5호
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• pp.250-257
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• 2006

It is well known that Grain-oriented electrical steel sheets have two dimensional magnetic properties according to the direction of exciting field such as non-linear phase difference between magnetic flux density and magnetic field intensity vectors, different iron loss and permeability even when an alternating magnetic field is applied. The measurement and application of the two dimensional magnetic properties of the Grain-oriented electrical steel sheets, therefore, are very important for the design and precise performance analysis of electric machines made of them. As the direction of exciting field changes, in this paper, the two dimensional magnetic properties of a Grain-oriented electrical steel sheet, i.e., non-linear B-H curves, phase difference between B and H, and iron loss characteristics, are measured using SST(Single Sheet Tester) which has two axes excitation. The measured results are presented in two ways: using $(B,\theta_B)$ method and using hysteresis loops along rolling and transverse directions, respectively.

• 동력기계공학회지
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• 제16권5호
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• pp.63-69
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• 2012

This paper presents an analysis on the induction heating of ring flange for wind farm. Ring flange is used for the connection of poles when building a column of wind power plant. Heat treatment of ring flange with the diameter of ${\O}1,000mm$ has been considered. For analysis on the induction heating, FEA is used. Firstly, electromagnetic filed analysis was performed to get the induction current distribution on the steel, After that, heat transfer analysis was performed using the magnetic filed analysis results. for more precise analysis, some measurement for permeability has been performed and the measurement data was used during the analysis. From the analysis, we get the temperature distribution on the ring flange.

• 약학회지
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• 제52권4호
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• pp.293-298
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• 2008

Non-steroidal anti-inflammatory drug (NSAID)-induced gut damage and bacterial translocation (BT) have not been studies well, especially from the perspective of time after administration of NSAIDs. We therefore examined these changes in animals. The study was performed on 5 groups of rat; a control group (group A) and diclofenac groups (groups B, C, E, and F). Rats in the diclofenac groups were orally administered diclofenac sodium before intestinal permeability (IP) measurement (group B, 1 h before measurement; group C, 10 h before; group D, 22 h before; and group E, 52 h before). The IP, stool pellet number, serum biochemical profile, enteric bacterial number, and BT in the mesenteric lymph nodes (MLNs), liver, spleen, kidney and heart were measured. The administration of diclofenac resulted in significantly increased IP, caused intestinal protein loss, decreased stool pellet number, caused enteric bacterial overgrowth and increased BT in multiple organs in groups A, B, C, and D. IF, intestinal protein loss, and the BT in the liver and the spleen in group E were decreased than those in group D. There were no differences in the other parameters between group D and E. In the recovery phase of the diclofenac-induced gut damage, enteric bacterial overgrowth and BT in the kidneys and the heart did not change while the BT in the reticuloendothelial systems such as in the MLNs and liver was decreased.

• 한국자기학회지
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• 제7권6호
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• pp.327-333
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• 1997

페라이트, 비정질 코아등의 고주파 연자성재료의 고주파 자기특성 데이터를 디지타이징 방법으로 얻고, 철손 및 B-H 곡선, 투자율을 자동적으로 측정할 수 있는 고주파 자기특성측정장치를 제작하였다. 본 시스템은 교류 인가를 위한 신호발생기와 전력증폭기, 인가자장을 게측하기 위한 전류측정용 저항, H 및 B 신호를 디지타이징 (digitizing)하기 위한 대역폭 500 MHz, 샘플링속도 1 Gs/s의 디지털 오실로스코프, 시스템 제어에 사용되는 GPIB 케이블 및 퍼스널 컴퓨터로 구성되었다. 자계 H 계측을 위한 전류센서로서 저항기(resistor)와 Rogowski 코일을 비교 검토한 결과 고주파 변류기 (current transformer : 이하 CT)가 주파수 특성과 노이즈 억제효과에서 보다 우수하였다. 측정시스템에 동작자속밀도 설정, 비대칭 B-H 곡선의 보정, 구형파등의 다양한 파형지원등의 기능을 부가하였다.

• 한국염색가공학회지
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• 제17권1호
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• pp.52-59
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• 2005

The purpose of this study is to establish the scientific data of cotton fabric pretreated with skim milk powder and to improve the dyeability. The surface monophology, add on, whiteness, stiffness, air permeability, moisture regain and absorption of cotton fabrics were evaluated by varying concentration of SMP to get the optimal conditions in pretreatment. FT-IR of cotton fabrics pretreated with SMP were measured. Amino acid compositions, viscosity of SMP were evaluated. The K/S values by varying concentration of cinnamon cassia and subtract of dyed SMP-C were measured. I attempted to evalute the color fastness of untreated and AI. The results are as follow; The optimal concentration of SMP was 9%(w/v) to be pretreated with cotton fabrics. From FT-IR spectrum, formation of -NH$_2$ and -COOH was verified by SMP-C. Denaturalization of protein and condensation of carbohydrate, fat, etc. were found in a measurement of amino acid and viscocity. The K/S value of cotton fabrics pretreated with SMP was higher than that of untreated. Most of the color fastnesses were great.