• 터널과지하공간
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• 제6권1호
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• pp.1-9
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• 1996

Pocheon granite specimens were thermally treated with cycles of predetermined temperatures ranging 2$0^{\circ}C$ to $600^{\circ}C$. Characterization of thermally-induced microcracks were carried out using optical microscopy and their effect on the various physical & mechanical properties were studied. Generally. uniaxial compressive strength, Young's modulus, Poisson's ratio, elastic wave velocity and specific gravity were found to decrease with increasing temperature. From 30$0^{\circ}C$ upwards, negative lateral strains were observed, which resulted in negative Poisson's ratio. Dynamic Young's modulus and Poisson's ratio were found to be generally most sensitive indicators to thermal cracking.

• Restorative Dentistry and Endodontics
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• 제16권2호
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• pp.62-84
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• 1991

The purpose of this study was to evaluate the cytotoxicity of four root canal sealers(Tubliseal, AH26, Apatite Root Canal Sealer I, Apatite Root Canal Sealer II) in Vitro. The root canal sealers were mixed and filled in molds which were $14{\times}1.25mm$ in diameter, in height to use for cell counting and agar overlary method, and $7{\times}1.25mm$ for millipore filter method and set for 7 days to use for experiment. Silicone and copper plate were used for negative and positive control respectively. Using the culture of L929 fibroblast, total cell number and vital cell number were counted and the ratio of vital cell number to total cell number was calculated on 2 nd, 4 th, 6 th experimental day, and the change of cell membrane permeability was tested by agar overlay method, and the succinate dehydrogenase activity was tested by millipore filter method. The obtained results were as follows. 1. In ail experimental groups, the mitotic activity of fibroblast was reduced when compared with that of negative control group, so ail experimental groups showed cytotoxicity. Apatite Root Canal Sealer I group exhibited mild cytotoxicity, and Tubliseal, AH26, Apatite Root Cenal Sealer II groups exhibited severe cytotoxicity. 2. In the test of the change of cell membrane permeability by agar overlay method, all experimental groups showed cytotoxicity. AH26 group exhibited mild cytotoxicity, and Apatite Root Canal Sealer I group exhibited moderate cytotoxicity, and Tubliseal and Apatite Root Canal Sealer II group exhibited severe cytotoxicity. 3. In the test of SDH activity by millipore filter method, there was no cytotoxicity in Apatite Root Canal Sealer I and Apatite Root Canal Sealer II group, but Tubliseal and AH26 group showed mild cytotoxicity.

• 한국전자통신학회논문지
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• 제9권8호
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• pp.921-926
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• 2014

본 논문에서는 CSLR(Complementary Single Loop Resonator)을 이용한 인셋 급전 마이크로스트립 안테나의 특성에 대해 연구하였다. SLR(Single Loop Resonator) 단일 구조에서 시뮬레이션 셋업 과정을 통해 산란계수로부터 실효투자율을 계산하였으며, 실효투자율이 음의 값을 갖는 주파수에서 SLR 구조의 치수를 선택하였다. 그리고 인셋 급전된 마이크로스트립 안테나의 접지면에 SLR 구조의 쌍대 구조인 CSLR을 $3{\times}3$으로 배열하여 최적 안테나를 설계하였다. 설계한 안테나의 반사손실과 복사패턴을 구하였으며, 공진주파수 2.82 GHz에서 기존의 인셋 급전 안테나와 크기를 비교하면 면적 대비 약 56.8%가 감소하는 결과를 얻었다. 사용된 툴은 3차원 FEM 툴인 Ansoft사의 HFSS를 사용하였다.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2001년도 Proceedings of 2001 KSAM Annual Meeting
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• pp.14-16
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• 2001

The outer membrane (OM) of gram-negative bacteria acts as an effective permeability barrier against noxious agents including several antibiotics and organic solvents, and lipopolysaccharide (LPS) is the key molecule for this function. Outer membrane modified mutants (Ml-166, M2-42, M3-21) of E. coli DH5$\alpha$/pBSl were selected through a mutation using EMS (ethyl-methane-sulfonate). Among the selected mutants, M3-21 was twice as sensitive as LumisTo $x^{ }$ to benzene and M2-41 was 8 times as sensitive as LumisTo $x^{ }$ to toluene. To identify the structural change in the membrane by mutation, the relative cell surface hydrophobicities and the absorption of the crystal violet to the organisms were measured. All the mutants absorbed more crystal violet than their parent and the absorption of crystal violet increased in cell walls as carbohydrate of lipopolysaccharide decreased. When the cell surface hydrophobicities of DH5/pBSl and its mutants were measured by the BATH, the hydrophobicities of mutants increased compared to their parent in several organic solvents. The difference of lipopolysaccharide between DH5/pBSl and its mutants was identified by various ways such as the SDS-PAGE gel, the screening of LPS molecular weights, the mass spectrometry, and MALDI-TOF.F.

• 대한인간공학회지
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• 제18권1호
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• pp.71-90
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• 1999

This study was conducted to examine the comfortability of wearing pantyhose in summer. To satisfy this purpose. 4 types of pantyhose were chosen from the market: a Mono type(M), a Wooly type(W), and two Support types(Sl, S2), were chosen. After the performances of samples were measured, these were worn by 8 healthy adult women. Under the summer field environment, psychological comfort ability was examined through the 5 steps of SD method. Physiological comfort ability was examined by measuring the body reactions(clothing pressure, skin temperature, total body weight loss, rectal temperature, pulse rates, and blood pressure), under the artificial environment($28.5{\pm}0.5^{\circ}C$, $82{\pm}3%$). The results of this examination were as follows : The order of comfortability which people felt in the field was W>M>S1>S2. The number of items which showed the highest correlation with comfort ability decreased and the correlation was lowered on the whole as time went by. There was positive high correlation between the performances of samples and comfort ability in compressibility, air permeability, water vapor permeability, while a negative high correlation in thickness, weight, compressional resiliency, strain (course) and moisture regain. The mean skin temperature was in the comfort zone, and rectal temperature, pulse rates, blood pressure were mostly in the normal range. Also it was showed that the correlation between the performance of samples and body reactions, except total body weight loss, was low.

• 대한전자공학회논문지TC
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• 제45권8호
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• pp.28-34
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• 2008

MRI(magnetic resonance imaging)의 신호검출기로 활용 가능한 간단한 형태의 자기장 검출기를 제안하였다. 제안된 검출기는 SRR(split ring resonator)이라고 하는 음의 투자율을 구현하는데 최초 사용되었던 일종의 LC 공진회로와 간단한 루프안테나를 유도성 결합시킨 것으로 기존의 MRI 신호검출기에 비해 단순한 구성으로 유사한 감도를 가질 수 있음을 확인하였다.

• 토지주택연구
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• 제1권1호
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• pp.59-65
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• 2010

The paper presents a comparison between a semi-implicit time integration linear finite element implementation and fully-implicit nonlinear Newton-Raphson finite element implementation of a triphasic small strain mixture formulation of an elastic partially saturated porous medium. The pore air phase pressure pa is assumed atmospheric, i.e., $p_a$ = 0, although the formulation and implementation are general to handle increase in pore air pressure as a result of loading, if needed. The solid skeleton phase is assumed linear isotropic elastic and partially saturated 'consolidation' in the presence of surface infiltration and traction is simulated. The verification of the implementation against an analytical solution for partially saturated pore water flow (no deformation) and comparison between the two implementations is presented and the important of the porosity-dependent nature of the partially saturated permeability is assessed on comparison with a commercial code for the partially saturated flow with deformation. As a result, the response of partially saturated permeability subjected to the porosity influences on the saturation of a soil, and the different behaviors of the partially saturated soil between staggered and monolithic coupled programs is worth of attention because the negative pore water pressure in the partially saturated soil depends on the difference.

• 한국의류학회지
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• 제21권4호
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• pp.750-756
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• 1997

The purpose of the study was to investigate a transmittance rate of UVB (Ultraviolet B) through summer fabrics and a protection rate of summer fabric from UVB. The subjects were randomly selected 159 fabrics from Korean common summer fabrics. The protection rates of 159 fabrics from UVB were measured by UVB lamp and UVB sensor, and 14 fabrics among these fabrics were selected for an assay of MTT(3-(4, 5-dimethylthiazol-2-yl) -2, 5 -diphenyltetrazolium). The protection rate of fabrics from cell toxicity of UVB was measured by investigating the difference of the amount of cell toxic substance on between fabrics covered with and without HeLa cell The average protection rate of 159 fabrics from UVB was 95.08%. As result findings, three negative correlations were found between: 1) the transmittance rate of UVB and the amount of MTT on fabrics (y=0.0373+0.O0518 x, r=-0.9323, p<0.001); 2) the air permeability of fabrics and the amount of MTT (r: -0.79, p< 0.01); 3) the air permeability of fabrics and the protection rate of fabrics from UVB (r=0.89, p<0.01). However, there was no effect of thickness of fabrics on the protection rate from UVB and the amount of MTT.

• 대한수의학회지
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• 제32권4호
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• pp.543-553
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• 1992

Properties of unitary ATP-sensitive $K^+$ channels were studied using planar lipid bilayer technique. Vesicles were prepared from bullfrog (Rana catesbeiana) skeletal muscle. ATP-sensitive $K^+$ (K (ATP)) channels were identified by their unitary conductance and sensitivity to ATP. In the symmetrical solution containing 200mM KCI, 10mM Hepes, 1mM EGTA and pH 7.2, single K (ATP) channels showed a linear current-voltage relations with slight inward rectification. Slope conductance at reversal potential was $60.1{\pm}0.43$ pS(n=3)). Micromolar ATP reversibly inhibited the channel activity when applied to the cytoplasmic side. In the range of -50~＋50 mV, the channel activity was not voltage-dependent, but the channel gating within a burst was more frequent at negative voltage range. Varying the concentrations of external/internal KCl(mM) to 40/200, 200/200, 200/100 and 200/40 shifted reversal potentials to $-30.8{\pm}2.9$(n=3), $-1.1{\pm}2.7$(n=3), 10.5 and 30.6(mV), respecrivety. These reversal potentials were close to the expected values by the Nernst equation, indicating nearly ideal selectivity for $K^+$ over $Cl^-$. Under bi-ionic conditions of 200mM external test ions and 200mM internal $K^+$, the reversal potentials for each test ion/K pair were measured. The measured reversal potentials were used for the calculation of the releative permeability of alkali cations to $K^+$ ions using the Goldman-Hodgkin-Katz equation. The permeability sequence of 5 cations relative to $K^+$ was $K^+$(1), $Rb^+$(0.49), $Cs^+$(0.27), $Na^+$(0.027) and $Li^+$(0.021). This sequence was recognized as Eisenman's selectivity sequence IV. In addition, modelling the permeation of $K^+$ ion through ATP-sensitive $K^+$ channel revealed that a 3-barrier 2-site multiple occupancy model can reasonably predict the observed current-voltage relations.

• 한국건설순환자원학회논문집
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• 제11권4호
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• pp.299-306
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• 2023

현무암폐석을 활용한 투수믈록의 성능을 평가하기 위해 현무암폐석의 치환율을 0, 20, 40, 60 (%) 4가지 수준으로 변화시켜 시멘트 및 무시멘트 기반의 투수블록을 제작하여 휨강도, 압축강도, 투수 계수, 흡수율, 밀도, 이산화탄소 저감, 미세먼지 저감 등에 대하여 평가하였다. 그 결과, 휨강도, 압축강도와 밀도는 현무암 폐석의 치환율이 증가함에 따라 감소하였지만 치환율 20 %에서 휨강도가 KS규격에 만족하는 결과값을 보였다. 흡수율, 투수계수, 이산화탄소 저감. 미세먼지 저감 등은 현무암 폐석의 치환율이 증가함에 따라 증가하는 경향을 보였으며, 투수계수는 모든 치환율에서 KS규격을 만족하는 결과를 나타내었고 미세먼지, 이산화탄소 저감과 흡수율은 모든 치환율에서 높은 값을 나타났다. 따라서 시멘트를 사용하지 않아 시멘트 생산과정에서 바생하는 이산화탄소량을 감소시킬 수 있는 무시멘트 기반 투수블록에서 중요한 지표인 투수계수가 KS규격을 만족하였고 공기질 오염물질 저감 성능이 뛰어나기 때문에 휨강도 기준을 만족하는 현무암 폐석 치환율 20 % 내에서 활용한다면 기존의 투수블록이 가지고 있는 문제점을 해결할 수 있는 방안으로 사용할 수 있을 것으로 판단된다.