• Journal of the Korean Chemical Society
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• v.40 no.8
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• pp.557-564
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• 1996

FAB CAD MS/MS(Fast Atom Bombardment Collision Activated Dissociation Mass Spectrometry/Mass Spectrometry) was used to study different degree of bond stability according to the linkage positions of alkali cationized $(Na^+, Li^+, K^+, NH_4^+)$ stereoisomeric and synthetic oligosaccharides. The alkali metal cations were much more stable, requiring over -40 eV of collision energy vs. only -10 eV for the protonated forms. Of the cations, the potassium cationized trisaccharides were more stable than the others. They would not yield fragment ions under the conditions of collision available in triple quadrupole. Other cationized species exhibited decreasing stability in the series $Nap^+>Li^+>NH_4^+$ using 0.8 mTorr argon pressure in the collision cell. Metal cations of the oligosaccharides maintained charge principally on the amino sugar as shown by shift of all the fragment ions containing the amino sugar. The reason for the higher stability of the metal cationized form is the formation of crown ether-like bond around metal cations, N-acetyl group on GlcNAc and oxygens on fucose moiety. Depending on the metal sizes and the conformation of linkage-isomeric region, cationized species gave linkage dependent fragment patterns and exhibited stability in the series 1-6 > 1-4 > 1-3 linkage.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.841-850
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• 2004

The modeling of uplift pressure within dam, on the foundation on which it was constructed, and on the interface between the dam and foundation is a critical aspect in the analysis of concrete gravity dams, i.e. crack stability in concrete dam can correctly be predicted when uplift pressures are accurately modelled. Current models consider a uniform uplift distribution, but recent experimental results show that it varies along the crack faces and the procedures for modeling uplift pressures are well established for the traditional hand-calculation methods, but this is not the case for finite element (FE) analysis. In large structures, such as dams, because of smaller size of the fracture process zone with respect to the structure size, limited errors should occur under the assumptions of linear elastic fracture mechanics (LEFM). In this paper, the fracture behaviour of concrete gravity dams mainly subjected to uplift Pressure at the crack face was studied. Triangular type, trapezoidal type and parabolic type distribution of the uplift pressure including uniform type were considered in case of evaluating stress intensity factor by surface integral method. The effects of body forces, overtopping pressures are also considered and a parametric study of gravity dams under the assumption of LEFM is performed.

• Journal of the Mineralogical Society of Korea
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• v.15 no.4
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• pp.243-257
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• 2002

Ca-type and Na-type bentonites show the great difference of some physicochemical properties. Na exchanged bentonite is mainly used for the foundry and construction materials in domestic utilization. This study tries to identify in detail the differences of some physicochemical properties and thermal properties between Ca-type and Na-type bentonites. Also the adsorption behavior and interlayer expansion for the HDTMA (Hexadecyltrimethylammonium) exchanged and CP (Cetylprydinium) exchanged Ca-type and Na-type bentonites were compared. Na-type bentonite shows the strong alkaline property, high viscosity and swelling compared to Ca-type bentonite. However, two types are very similar for the cation exchange capacity and MB (Methylene Blue) adsorption. The decomposition of adsorbed and interlayer water of Na-type bentonite is caused in the lower temperature than Ca-type bentonite. And Ca-type bentonite shows the decomposition of structural water in the lower temperature than Na-type bentonite. The interlayer expansion of montmorillonite resulted to the intercalation of HDTMA and CP into bentonite is so strongly caused from 12～15 $\AA$ to $40\AA$ (basal spacing). HDTMA-bentonite is almost expanded to $37～38\AA$ when 200% CEC equivalent amount of HDTMA is added, and CP-bentonite is fullly expanded to 40 $\AA$ in the 140% CEC equivalent amount of CP It means that CP causes the stronger interlayer expansion of montmorillonite and easier adsorption than HDTMA. Adsorption behaviors of CP into bentonite is so stable and continuously sorbed in the proportion to the treatment of amount until 200% of the CEC equivalents. CP-bentonite shows the same adsorption behavior regardless of Ca-type or Na-type montmorillonite.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.4
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• pp.340-355
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• 1996

In order to suggest the useful information of fishing ground, a data base system on 32bit personal computer was constructed and handled by using the catch data of Korean tuna long-line, catch by species, fishing time and place, fish price and etc. mainly from 1975 to 1992. The results obtained are as follows ; In the fishing ground displaying catch rate, the catch rate has reduced as time passed, and this penomenon was more evident in Indian. And yellowfin have high catch tate in the Western Pacific of low latitute region, bigeye tuna have in the Eastern. The region of high catch rate of bigeye tuna was moved from the Indian and the Atlantic to the Pacific. The patterns of catch numbers of yellowfin and bigeye tuna appeared nearly same that, having nothing to do with catch numbers in all oceans. The region of least catch was the Northwestern Pacific, the regions of most catch were the Western Indian and the Pacific of low latitute. As to simulation of fishing ground estimation, there were economical grounds in the Western Pacific of low latitute region, the Eastern Pacific of this, the Western Indian, the Eastern Indian, and the Atlantic, in order.

• Korean journal of food and cookery science
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• v.26 no.6
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• pp.804-810
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• 2010

Sulforphane (SF) is a family of biologically active compound that is distributed widely in broccoli. Although studies in rodents have shown that these compounds are effective and versatile inhibitors of tumorigenesis, the role of dietary SF in protection against human cancers remains to be established. The objective of this study was to explore the quantitative relationship between the dietary intake of cruciferous vegetables and urinary excretion of SF. The effects of dietary broccoli on the body's ability to detoxify were studied in six male subjects between the ages of 22~30 years. Study included administering a glucosinolate-free diet for 8 days (control period). The broccoli diet was further subdivided into two periods; 250 g broccoli was fed per day during the first three days and 500 g broccoli was fed per day during the latter three days. After an 8-day washout period, a second experiment was conducted. The same protocol was used with the exception that uncooked broccoli was consumed. Urinary SF mercapturate was measured to determine the bioavailability of broccoli. The linear trend for mercapturate excretion was dose-dependent, resulting in 3.8- and 1.9-fold increase by the third and six days, respectively, compared to the control. Lower amount of SF-NAC conjugate was detected in cooked broccoli compared to fresh broccoli suggesting cooking may have caused a significant loss in glucosinolates in cruciferous vegetables. Therefore, SF can be used as a biomarker for intake of cruciferous vegetables.

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1221-1234
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• 2013

The purpose of this study is to suggest the methodology for the computation of uplift pressure and discharge of the seepage flow under gravity dam. A 3-dimensional FDM model is developed for this purpose and this model can simulate the saturated Darcian flow in heterogeneous media. For the verification of the numeric model, test simulation has been executed and the mass balance has been checked. The error does not exceed 3%. Using the developed model, The uplift pressure and seepage flow discharge under gravity dam has been calculated. The uplift pressure shows the similar pattern, comparing with the result of flow-net method. As the length of grout curtain increases, the uplift pressure decreases linearly, but the seepage flow discharge shows the non-linear decreasing pattern. The coefficients of the formulas in the dam-design criteria have been analysed, and ${\alpha}=1/3$ corresponds to the value when the length of curtain grout is 70% of the aquifer height. The uplift pressure near the pressure relief drain has the big curvature vertically and horizontally. The developed model in this study can be used for the evaluation of the effects of seepage flow under gravity dam.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.2
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• pp.51-58
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• 2017

We investigated the efficiency of natural zeolite with different cation exchange capacity (CEC) as capping material for the remediation of marine sediments contaminated with heavy metals. Three different zeolite with high CEC (HCzeo, 163.74 cmolc/kg), medium CEC (MCzeo, 127.20 cmolc/kg), and low CEC (LCzeo, 70.62 cmolc/kg) were used. The surface area of the zeolite was in decreasing order: HCzeo ($59.43m^2/g$) > MCzeo ($52.10m^2/g$) > LCzeo ($10.12m^2/g$). The results of mineralogical composition obtained from X-ray diffraction (XRD) show that LCzeo was mainly composed of quartz and albite. In the XRD result of MCzeo and HCzeo, the peaks of clinoptilolite, heulandite, and mordenite were also observed along with that of quartz and albite. Sorption equilibrium onto the HCzeo, MCzeo, and LCzeo was reached in 6 h at initial concentration of 10 mg/L and 100 mg/L. Higher adsorption of Cd and Zn onto the zeolite with higher CEC were achieved but adsorption of Cu and Ni were not dependent on the CEC of zeolite. It can be concluded that the zeolite with high cation exchange ability is recommended for the contaminated sediments with Cd and Zn but the inexpensive zeolite with low CEC for Cu and Ni.

• The Journal of the Acoustical Society of Korea
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• v.29 no.6
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• pp.381-387
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• 2010

Both timbral features and spatial features are important in the assessment of multichannel audio coding systems. The prediction model, extending the ITU-R Rec. BS. 1387-1 to multichannel audio coding systems, with the use of spatial features such as ITDDist (Interaural Time Difference Distortion), ILDDist (Interaural Level Difference Distortion), and IACCDist (InterAural Cross-correlation Coefficient Distortion) was proposed by Choi et al. In that model, ITDDistswere only computed for low frequency bands (below 1500Hz), and ILDDists were computed only for high frequency bands (over 2500Hz) according to classical duplex theory. However, in the high frequency range, information in temporal envelope is also important in spatial perception, especially in sound localization. A new model to compute the ITD distortions of temporal envelopes in high frequency components is introduced in this paper to investigate the role of such ITD on spatial perception quantitatively. The computed ITD distortions of temporal envelopes in high frequency components were highly correlated with perceived sound quality of multichannel audio sounds.

• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.335-345
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• 2013

The present study investigates the effect of the inter-aural level difference(ILD) on the syllable articulation test in classrooms which can be occurred by the absorption of interior surfaces. In order to do this, the sound absorbing materials were installed in the classroom and sound pressure level(SPL) at each ear was measured using binaural recording systems. Also, syllable articulation tests were carried out at a classroom with and without sound absorption materials by 20 students who have normal hearing condition, in order to investigates the effect of the ILD on the speech intelligibility. As a result, it was found that the larger inter-aural level differences was occurred at the nearer positions to lateral walls after sound absorptions were applied to lateral walls in the classroom. At some places, the measured ILD was lager than JND of sound level (3dB). Also, it was shown that the correlation coefficient of inter-aural level difference with the score of syllable test has the significant result(-0.441). Thus, It is concluded that ILD can affect the subjective speech intelligibility in classrooms.

• The Korean Journal of Financial Management
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• v.13 no.1
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• pp.51-78
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• 1996

본 연구는 대리이론과 정보비대칭이론 그리고 패킹오더가설등을 기초로 재무정책의 결정요인과 상호의존관계를 규명하는데 그 목적을 두고 있다. 분석자료가 횡단면적 특성과 시계열적 특성을 동시에 갖고 있는 패널자료인 점을 감안하여 일반적인 OLS에 의한 회귀분석 대신에 동시적인 복합오차 모형과 일반화 최소자승법에 의한 회귀분석을 실시하였다. 자본조달정책 분석으로부터 배당비율과 내부자지분율이 재무레버리지에 각각 음(-) 및 양(+)의 영향을 주고 있음을 알 수 있었다.이외에도 경영위험, 수익성, 성장기회는 재무레버리지와 음(-)의 관계이며, 주식분산성과는 재무레버리지와 제한적으로 음(-)의 관계에 있었다. 그리고 기업규모와 경제적 부가가치는 재무레버리지와 양(+)의 영향을 주고 있음도 확인할 수 있었다. 배당정책 분석으로부터 재무레버리지는 대체로 그리고 내부자지분을은 제한적으로만 배당비율에 음(-)의 영향을 주고 있음을 확인하였다. 이외에도 경영위험과 수익성은 일관되게 배당비율과 양(+)의 관계를 갖고 있었다. 기업규모, 경제적 부가가치는 배당비율과 대체로 양(+)의 영향을 미치는 것으로 확인하였다. 성장기회는 제한적으로만 배당비율과 음(-)의 관계를 유지하고 있었다. 소유권구조 분석으로부터 재무레버리지는 내부자지분율에 대체로 양(+)의 영향을 미치는 것으로 확인하였다. 이외에도 기업규모, 경제적 부가가치 및 성장기회는 내부자지분율에 일관되게 음(-)의 관계를 갖고 있었다. 주식분산성과는 내부자지분율에 대체로 양(+)의 영향을 주고 있었다. 재무정책간의 상호의존성을 요약하면 다음과 같다. 내부자지분율과 배당비율은 재무레버리지에 각각 양(+)과 음(-)의 상호영향을 주고 있었으며, 내부자지분율은 배당비율에 제한적으로만 음(-)의 영향을 미치고 있다는 미약한 결과를 얻었다. 그러나 배당비율이 내부자지분율에 영향을 미친다는 증거는 확인할 수 없었다.