• Geomechanics and Engineering
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• 제3권2호
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• pp.131-151
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• 2011

The electrical conductivity of a soil-water system is related to its engineering properties. By measuring the soil electrical conductivity, one may obtain quantitative, semi-quantitative, or qualitative information to estimate the in-situ soil behavior for site characterization. This paper presents the results of electrical conductivity measured on compacted kaolin clay samples using a circular two-electrode cell in conjunction with a specially designed compaction apparatus, which has the advantage of reducing errors due to sample handling and increasing measurement accuracy. The experimental results are analyzed to observe the effects of various parameters on soil electrical conductivity, i.e. porosity, unit weight, water content and pore water salinity. The performance of existing analytical models for predicting the electrical conductivity of saturated and unsaturated soils is evaluated by calculating empirical constants in these models. It is found that the Rhoades model gives the best fit for the kaolin clay investigated. Two general relationships between the formation factor and soil porosity are established based on the experimental data reported in the literature and measured from this study for saturated soils, which may provide insight for understanding electrical conduction characteristics of soils over a wide range of porosity.

• 약학회지
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• 제25권4호
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• pp.161-165
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• 1981

The binding of two cephalosporins, cephalothin and cefazoline to human serum albumin(HSA) was studied by difference spectrophotometry using a spectrophotometric probe, 2-(4'-hydroxybenzeneazo) benzoic acid. The probe is strong visible absorbing material which interacts with serum albumin to give characteristic spectrophotometric peaks and provides the basis for a convenient assay to measure free and bound amounts in the presence of serum albumin and competitive drugs. The results obtained showed that the probe and cephalosporin compete for the same binding site on human serum albumin; thus the probe can be used to gauge the displacement of cephalosporins from human serum albumin. The data were interpreted on the basis of theory of multiple equilibria. The number of binding sites of human serum albumin for 2-(4'-hydroxybenzeneazo) benzoic acid(HBAB), cephalothin and cefazoline appears to be 4. By using this technique the binding constants were found as follows: HSA-HBAB, $7.89{\times}10^{4}M^{-1}$; HSA-cephalothin, $1.09{\times}10^{3}M^{-1}$ ; HSA-cefazoline, $1.21{\times}10^{3}M^{-1}$.

• 약학회지
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• 제41권6호
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• pp.756-764
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• 1997

Ile-224 in I269S mutant horse liver alcohol dehydrogenase isoenzyme S (HLADH-S) was mutated to serine by site-directed mutagenesis in order to study the role of the residue in c oenzyme binding to the enzyme. The specific activity of the I269S and I224S mutant enzyme to ethanol was increased 6-fold and all Michaelis constants($K_a,\;K_b,\;K_p,\;and\;K_q$,/TEX>) were larger than those for the wild-type and I269S enzyme. The substitution decreased the afffinity to coenzymes and increased the specific activity of the enzyme. The mutant enzyme showed the highest catalytic efficiency for octanol among the primary alcohols. But it didn`t have activities on retinoids and 5${\beta}$-cholanic acid-3-one. From these results, it was confirmed that the hydrophobic interaction of Ile-224 residue with coenzyme was related to coenzyme affinity in ADH reaction. The substitution also affected the substrate affinities to the enzyme.

• 한국결정학회지
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• 제7권2호
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• pp.165-174
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• 1996

본 연구는 Pb(Zr0.52Ti0.48)O3을 기본 조성으로하여 Pb-site에 Pb2+보다 이온 반경이 큰 Ba2+, 비슷한 크기의 Sr2+ 그리고 이온 반경이 작은 Ca2+를 치환하여 유전 및 압전 특성을 조사하고, 압전 열화에 대한 영향을 고찰하고자 하였다. 치환하지 않은 기본 조성에 비해 치환된 조성의 비유전율과 전기기계결합게수는 Ba2+ 치환시 가장 높았고, Sr2+ 치환시 기본조성과 비슷하였으며 Ca2+ 치환시 감소하였다. 기계적 품질계수는 지본 조성에 비해 Ba2+ 치환시에는 감소하였으며, Sr2+, Ca2+ 치환으로 갈수록 증가하는 경향을 나타내었다. 그리고 압전 열화시 주파수 변화 특성에서는 각 이온 치환에 따른 변화는 보이지 않았으나 상온 방치시와 고온 방치(100℃)후의 열화속도가 상온방치후보다 빨랐다.

• Bulletin of the Korean Chemical Society
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• 제19권5호
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• pp.569-575
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• 1998

Investigation of the structure of the gangliosides has proven to be very important in the understanding of their biological roles. We have determined the tertiary structure of asialoganglioside GM1 $(GA_1)$ using NMR spectroscopy and distance geometry calculations. All of the structures are very similar except the glycosidic torsion angles in the ring IV and ring III linkages. There are two low-energy structures for GA1, G1 and G2. G1 differs from G2 only in the IV-III glycosidic linkages and the orientation of acetamido group in ring III. There is a stable intramolecular hydrogen bond between the third hydroxyl group in ring I and the ring oxygen atom in ring II. Also, there may be a weak hydrogen bond between the second hydroxyl group in ring IV and the acetamido group in ring III. Small coupling constants of $^3J_{IH3,IOH3}\; and\; ^3J_{IVH2,IVOH2}$ support this result. Overall structural features of $(GA_1)$ are very similar to those of $(GM_1)$. It implicates that specificities of the sugar moieties in GM1 are caused not by their tertiary foldings, but mainly by the electrostatic interactions between the polar sialic acid and its receptors. Since it is evident that $(GA_1)$ is more hydrophobic than $(GA_1)$, a receptor with a hydrophobic binding site can recognize the $(GA_1)$ better than $(GA_1)$. Studies on the conformational properties of $(GA_1)$ may lead to a better understanding of the molecular basis of its functions.

• Geomechanics and Engineering
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• 제16권5호
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• pp.539-545
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• 2018

Longitudinal Displacement Profile (LDP) is an appropriate tool for determination of the displacement magnitude of the tunnel walls as a function of the distance to the tunnel face. Some useful formulations for calculation of LDP have been developed based on the monitoring data on site or by 3D numerical simulations. However, the presented equations are only based on the tunnel dimensions and for different quality of rock masses proposed a unique LDP. In the present study, it is tried to present a new formulation, for calculation of LDP, on the basis of Rock mass quality. For this purpose, a comprehensive numerical simulation program was developed to investigate the effect of rock mass quality on the LDP. Results of the numerical modelling were analyzed and the least square technique was used for fitting an appropriate curve on the derived data from the numerical simulations. The proposed formulation in the present study, is a logistic function and the constants of the logistic function were predicted by rock mass quality index (GSI). Results of this study revealed that, the LDP curves of the tunnel surrounded by rock masses with high quality (GSI>60) match together; because the rock mass deformation varies over an elastic range.

• Bulletin of the Korean Chemical Society
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• 제17권4호
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• pp.353-357
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• 1996

Second-order rate constants have been measured spectrophotometrically for the reaction of 2,4-dinitrophenyl X-substituted benzenesulfonates with Z-substituted phenoxides in absolute ethanol at 25.0±0.1 ℃. The nucleophilic substitution reaction gives both S-O bond and C-O bond cleavage products. The extent of S-O bond cleavage increases significantly with increasing electron withdrawing ability of the sulfonyl substitutent X, while that of the C-O bond cleavage is independent on the electronic effect of the substituent. On the contratry, the effect of the substituent Z in the nucleophilic phenoxide is more significant for the C-O bond cleavage than for the S-O bond cleavage. Aminolyses of 2,4-dinitrophenyl benzenesulfonate (1) with various 1°, 2° and 3°amines have revealed that steric effect is little important. The extent of S-O bond cleavage increases with increasing the basicity of the amines, but decreases with increasing the basicity of the nucleophilic aryloxides, indicating that the HSAB principle is not always operative. Besides, reactant and solvent polarizability effect has also been found to be an important factor in some cases but not always to influence the reaction site.

• 한국광물학회지
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• 제17권3호
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• pp.209-220
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• 2004

구리 흡착 실험과 MINTEQA2 및 FITEQL3.2 컴퓨터 프로그램을 이용하여 고성군 판곡리에서 산출되는 황토 현탁액의 구리 흡착 특성을 연구하였다 구리 흡착 실험은 pH, 구리 용액의 양, 전해질의 이온 세기를 변화시키면서 실시하였고, 구리의 농도는 유도결합플라즈마분광분석기를 사용하여 분석하였다. 첨가하는 구리 이온의 양과 pH가 증가할수록 흡착되는 구리 이온의 양도 증가한다. 특히 pH가 5.5에서 6.5로 변할 경우 급격한 흡착률의 증가가 있으며, pH 7.5에서 거의 100% 흡착된다. 배경 전해질의 이온 세기에 영향을 받지 않는 것으로 보아 구리 이온은 황토 표면과 내부권 복합체(inner-sphere complex)로써 아주 강한 화학적 결합을 하고 있는 것으로 판단할 수 있다. MINTEQA2 프로그램을 이용하여 구리의 화학종 분포를 계산한 결과, pH가 증가함에 따라 $Cu^{2+}$ 의 농도는 점점 감소하고 $Cu(OH)_2$ 농도는 점점 증가한다. FITEQL3.2 프로그램을 이용하여 황토의 표면을 규산염 광물 자리와 산화염 광물 자리로 나눈 two sites-three pKas 모델을 적용하여 흡착 양상을 모델링한 결과, 구리 용액의 부피가 2～6 mL인 경우 구리 흡착 평형 상수 값을 도출할 수 있었다. 철산화염 광물 반응 자리에 흡착되는 구리의 앙은 pH 4.5～6.5 범위에서 급격한 흡착 양상을 보이다가 그 이상 pH에서는 흡착되는 양이 조금씩 밖에 증가하지 않는다. 규산염 광물 반응 자리에 흡착되는 구리의 양은 구리 용액의 양이 적을 때는 미약하다가 구리 용액의 양이 커질 경우 그 양이 많아진다. 침전에 의하여 제거되는 구리의 양은 광물 표면 자리에 흡착되는 양과 비교하면 아주 적다. 구리 이온에 대한 흡착 친화도는 규산염 광물보다는 철산화염 광물이 더 큰 것으로 판단된다.

• 한국안전학회지
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• 제10권3호
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• pp.81-95
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• 1995

Now, safety assurance in construction sites should be accomplished by its own organization rather than control of the code or government. It is believed that the safety assurance can be considerably improved by a lecture or an education using the existing theories or literatures up to now, but it is thought that fundamental safety assurance we not able to be accomplished without developing safety devices '||'&'||' equipment or taking fundamental measures, based on the result analyzed from workers behaviors. There are various behaviors of the workers showed in construction site, but only tests for hammerusing works such as form, re-bar, stone workers directly related to the grip strength are mainly performed, investigated and measured here for the study. The above works are similar to power grip, 7th picture on seven items which are categorized for hand grip types(Ammermin 1956 ; Jones ; Kobrick 1958). Measurements of grip strength are commonly taken in anthropometric surveys. They are easy to administer but unfortunately it is rather dubious whether they yield any data that are of interest to the engineer. Very fewer controls of tools are grasped and squeesed studies showed very little overall correlation between grip strength and other measures of bodily strength (Laubach, Kromer, and Thordsen 1972), but hammer-using work which is practically progressed in construction site are mainly influenced with grip strength. According to the investigation on work measurement, it is shown that 77% of form worker are using hammer to be related to grip strength. In this study, it is particularly noticed that wearing safety gloves in construction site is required for workers safety but 20% difference between grip strength with safety gloves and without ones are commonly neglected in the site(Fig. 1). Nevertheless, safety operation with consideration of the above 20% difference is not considered in the construction site. Factors of age, kinds of work, working time, with or without safety gloves are in vestigated '||'&'||' collected at the sites for this study. Test, not at each working hour but at 14 : 00 when the almost all of the workers think the most tired, resulting from the questionaires, also when it is shown on the research report has been performed and compared for main kinds of works : form '||'&'||' re-bar work. Tests were performed with both left SE rightand of the workers simultaneously in construction site using Rand Dynamometer(Model 78010, Lafayette Instrument Co., Indiana, U.S.A) by reading grip strength on the gauge while they are pulling, and then by interviewing on their ages, works, experiences and etc., directly. The above tests have been performed for the dates of 15th march-26th May '95 with consideration of site condition. And even if various factors of ambient temperature on the testing date, working condition, individual worker's habit and worker's condition of the previous ate are concerned with the study. Those are considered as constants in this study. Samples are formwork 53, rebar 62, electrician 5, plumber 4, welding 1 from D construction Co., Ltd, ; formwork 12, re-bar 5, electrician 2, from S construction Co., Ltd, , formwork 78, re-bar 18, plumber 31, electrician 13, labor 48, plumber 31, plasterer 15, concrete placer 6, water proof worker 3, maisony 5 from B construction Co., Ltd. As In the previously mentioned, main aspect to be investigated in this study will be from '||'&'||' re-bar work because grip strength will be directly applied to these two kinds of works ; form '||'&'||' re-bar work, eventhough there are total 405 samples taken. It is thought that a frequency of accident occurrence will be mainly two work postures "looking up '||'&'||' looking down" to be mainly sorted, but this factor is not clarified in this study because It will be needed a lot of work more. Tests has been done at possible large scale of horizontally work-extended sites within one hour in order to prevent or decrease errors '||'&'||' discrepancies from time lag of the test. Additionally, the statistical package computer program SPSS PC＋has been used for the study.

• 한국광학회지
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• 제18권5호
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• pp.351-361
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• 2007

마그네트론 스퍼터링 방법을 사용하여 광기록 매체인 GST 박막과 보호층인 $ZnS-SiO_2$ 박막 또는 $Al_2O_3$ 박막을 c-Si 기판위에 증착한 뒤 in-situ 타원계를 사용하여 상변화 광기록층인 GST 시료의 타원상수 온도의존성을 실시간으로 측정한 결과 $300^{\circ}C$ 이상의 온도에서 GST의 고온 타원상수는 가열 환경 및 보호층의 종류에 따라 큰 차이를 보여주었다. 가열 환경 및 보호층의 종류에 따라 GST의 고온 타원상수가 달라지는 원인인 $1{\sim}2$시간의 긴 승온시간을 줄이기 위해 Phase-change Random Access Memory(PRAM) 기록기를 사용하였고 수십 ns 이내의 짧은 시간 내에 순간적으로 GST 시료를 가열 및 냉각하였다. GST층이 손상되지 않고 결정화 및 고온 열처리가 되는 PRAM 기록기의 기록모드와 레이저출력 최적조건을 찾았으며 다층박막 구조에서 조사되는 레이저 에너지가 광기록층인 GST에 흡수되는 양과 이웃하는 층으로 전파되는 양을 열확산방정식으로 나타내고 이를 수치해석적으로 풀어 레이저출력과 GST 박막의 최고 온도와의 관계를 구하였다. 지름이 1um 정도인 레이저스폿을 대략 $0.7{\times}1.0mm^2$의 면적내에 촘촘히 기록한 다음 고온 열처리된 GST 시료의 분광타원데이터를 500 um의 빔 크기를 가지는 마이크로스폿 분광타원계를 사용하여 구하고 그 복소굴절률을 결정하였다. In-site 타원계를 사용할 때에 가열 환경 보호층 물질의 영향을 크게 받은 GST의 고온 복소굴절률은 PRAM 기록기를 사용하였을 때에는 가열환경이나 보호층의 종류에 무관하게 안정된 값을 보여주었다 Atomic Force Microscope(AFM)과 Scanning Electron Microscopy(SEM)을 통해 관찰한 GST 다층박막시료의 고온 열처리 전후 표면미시거칠기 변화도 PRAM 기록기를 사용할 때에는 in-situ 타원계를 사용할 때보다 1/10 정도의 크기를 보여주어 PRAM 기록기와 분광타원계를 사용하여 결정한 GST의 고온광학물성의 신뢰성을 확인하여 주었다.