• Journal of the Korean Chemical Society
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• v.40 no.6
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• pp.420-426
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• 1996

The critical micelle concentration(CMC) and the counterion binding $constant(\beta)$ at the CMC of the mixtures of Sodium dodecylsulfate(SDS) with Sodium dodecylbenzenesulfonate(DBS) in aqueous solutions have been determined from the concentration dependence of electrical conductance at several temperatures from $15^{\circ}C$ to $35^{\circ}C.$ Thermodynamic parameters(${\Delta}C_p,\;{\Delta}G_m^{\circ},\;{\Delta}H_m^{\circ}$ 및 ${\Delta}S_m^{\circ}$ and ${\Delta}C_p$), associated with the micelle formation of SDS/DBS mixtures, have been estimated from the temperature dependence of CMC and $\beta$ values. The measured values of ${\Delta}G_m^{\circ}\;and\;{\Delta}C_p$ are negative but the values of ${\Delta}S_m/^{\circ}$ are positive in the whole measured temperature region. The significance of these thermodynamic parameters and their relation to the theory of the micelle formation of SDS/DBS mixtures have been also considered.

• Journal of the Microelectronics and Packaging Society
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• v.5 no.2
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• pp.59-64
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• 1998

Pt/SiO2/Si 기판구조위에 스크린인쇄법과 졸-겔법에 의해 (Pb, La)TiO3(PLT) 후막 과 박막을 도포시켜 $650^{\circ}C$후속열처리 온도에서 결정화한후 결정특성과 전기적 특성을 조사 하였다. $650^{\circ}C$ 온도에서 후속열처리된 PLT 시료의 경우 전형적인 perovskite 결정구조를 보 여주었다. SEM 단면형상으로부터 Pt 전극과 PLT막 사이에는 비교적 평활한 계면형상을 보여주었다. PLT 후막과 박막시료의 잔류분극(2Pr) 값은 약 1$\mu$C/cm2 으로각각 나타났으며 이와같이 후막 PLT시료에 비해 박막시료의 잔류분극값이 큰이유는 박막시료가 보다 양호 한 결정성을 지니기 때문이었다. 상온부근에서 후막과 박막시료의 초전계수값은 약 1.5nC/cm2.$^{\circ}C$와 4.0nC/cm2.$^{\circ}C$의 값을 각각 나타내었으며 누설전류의 크기는 약 0.3~0.8$\mu$ A/cm2의 비교적 양호한 누설전류 특성을 얻었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5492-5500
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• 2015

Low-density lipoprotein cholesterol (LDL-C) is a major modifiable risk factor for cardio- cerebrovascular disease. In clinical practice, however, it is primarily calculated using the Friedewald formula as a cost-effective method. The aim of this study was to compare Friedewald-estimated and directly measured LDL-C values and assess the concordance in guideline LDL-C risk classification between the two methods. The data were derived from the 2009 and 2010 Korea National Health and Nutrition Survey (KNHANES). Analysis was done for 4,319 subjects with lipid panels-total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), directly measured LDL-C using an enzymatic homogeneous assay, and triglycerides (TG). For subjects with TG lower than 400 mg/dL, Friedewald-estimated and directly measured LDL-C were highly correlated (r = 0.958, p < 0.001) and overall concordance was 82.7%. As TG increased, overall concordance decreased. Overall concordance was 85.4% at TG lower than 150 mg/dL; 78.2% at TG of 150-199 mg/dL; and 71.4% at TG of 200-399 mg/dL. The Friedewld equation tended to overestimate LDL-C when TG are of < 150 mg/dL; however, underestimate LDL-C when TG are of ${\geq}150mg/dL$. As a result, Friedewald estimation misclassified 382 subjects (9.1%) in a higher category versus 348 subjects (8.3%) in a lower category. Our findings suggest that overestimation of LDL-C by the Friedewald formula can be a great problem as well as underestimation.

• Nuclear Engineering and Technology
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• v.8 no.1
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• pp.19-27
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• 1976

The strain ageing behaviour of Zircaloy-4 has been studied in the temperature range 175$^{\circ}C$ to 575$^{\circ}C$ for both quenched and annealed specimens. The strain ageing in quenched Zircaloy-4 was found in the temperature range 175$^{\circ}C$ to 50$0^{\circ}C$ and its Peak occured at 3$25^{\circ}C$ while the strain ageing in annealed specimens occured in the temperature range 175-575$^{\circ}C$, showing two peaks, one at 323$^{\circ}C$ and a higher one at 45$0^{\circ}C$. The peak at 3$25^{\circ}C$ in both quenched and annealed specimens is considered to be due to the segregation of interstitial oxygen atoms to cell walls during ageing. The peak at 45$0^{\circ}C$ in annealed specimens is considered to he due to the interaction of dislocations with Fe atoms. It has been found that strain ageing stress at ~30$0^{\circ}C$ in zirconium alloys is proportional to the square root of oxygen content.

• Korean Journal of Food Science and Technology
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• v.21 no.2
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• pp.313-319
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• 1989

Hydration Properties of Olchal(Japonica type) and Hankangchalbyeo $(J{\times}I\;type)$ waxy rices at soaking temperatures of $4-40^{\circ}C$ were examined. The water uptake rate constant of Olchal was greater than that for Hankangchalbyeo. Volume increase rate during hydration of Olchal was faster. The rate constants of hardness decrease during hydration were similar between the two varieties. The Z-value and $Q_{10}$ were $39.7^{\circ}C$ and 1.78, respectively.

• Water for future
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• v.29 no.5
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• pp.139-150
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• 1996

This paper presents the effect of numerical parameters, such as grid size and grid ratio, on the outflow hydrograph of a unit-width plane in the linear Muskingum-Cunge method. The numerical results depend on Courant number C and cell Reynolds number D, two physically and numerically meaningful parameters. As C approache 1 and D increases, the numerical dispersion-relating oscillations are difficult to occur. The numerical oscillations occur in the front of a propagating wave for C < 1, while smaller oscillations occur behind the wave for C > 1 due to the numerical diffusion effect. For a plane with a small value of characteristic reach length L (e.g., a steep plane), the numerical solution of the Muskingum-Cunge method is similar to that of the kinematic wave method, which shows no wave attenuation. However, for a plane with a large value of L (e.g., a mild plane), the Muskingum-Cunge method leads to the diffusion waves which are essentially independent of the Courant number. Accordingly, the Muskingum-Cunge method will be suited for the routing of the catchment with relatively mild slopes.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.614-620
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• 1999

The critical micelle concentration (CMC) and the counterion binding constant (${\beta}$) at the CMC of the mixtures of Dodecylpyridinium chloride (DPC) and Tetradecyltrimethylammonium bromide (TTAB) have been determined from the concentration dependence of electrical conductance at various temperatures from $4^{\circ}C$ to $36^{\circ}C$. Thermodynamic parameters (${\Delta}C_p$, ${\Delta}G^o_m$, ${\Delta}H^o_m$ and ${\Delta}S^o_m$), associated with the micelle formation of DPC/TTAB mixtures, have been estimated from the temperature dependence of CMC and ${\beta}$values. The measured values of ${\Delta}C_p$ and ${\Delta}G^o_m$ are negative but the values of ${\Delta}S^o_m$ are positive in the whole measured temperature region. The values of ${\Delta}H^o_m$ are positive at low temperature region and negative at high temperature region. The results show that all of the thermodynamic parameters are dependent on temperature and mole fraction of DPC(${\alpha}_DPC$).

• Journal of KIISE:Software and Applications
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• v.31 no.4
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• pp.516-524
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• 2004

In this paper, the initial value problem in clustering using K-means or Fuzzy-c-means is considered to reduce the number of iterations. Conventionally the initial values in clustering using K-means or Fuzzy-c-means are chosen randomly, which sometimes brings the results that the process of clustering converges to undesired center points. The choice of intial value has been one of the well-known subjects to be solved. The system of clustering using K-means or Fuzzy-c-means is sensitive to the choice of intial values. As an approach to the problem, the uniform partitioning method is employed to extract the optimal initial point for each clustering of data. Experimental results are presented to demonstrate the superiority of the proposed method, which reduces the number of iterations for the central points of clustering groups.

• Geophysics and Geophysical Exploration
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• v.12 no.3
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• pp.263-267
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• 2009

Recently intrinsic and scattering quality factor ($\varrho_i^{-1}$ and $\varrho_s^{-1}$) was successfully separated from total quality factor ($\varrho_t^{-1}$) on the seismic data of the Korean Peninsula. From this result, we theoretically calculated the expected coda quality factor ($\varrho_{Cexp}^{-1}$) based on multiple scattering model, and compared with other quality factors such as $\varrho_t^{-1}$, $\varrho_i^{-1}$, $\varrho_s^{-1}$, and observed coda quality factor ($\varrho_c^{-1}$) obtained by single scattering model. While the $\varrho_{Cexp}^{-1}$ values are comparable to the $\varrho_i^{-1}$ values, the $\varrho_c^{-1}$ values are close to the values of $\varrho_t^{-1}$ rather than $\varrho_i^{-1}$ and $\varrho_{Cexp}^{-1}$ except for the 24 Hz frequency. This results suggest that the assumption of uniform scatterer in the Korean Peninsula is unrealistic.

• The Korean Journal of Malacology
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• v.30 no.2
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• pp.101-106
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• 2014

Clearance rate and feeding of surf clam, Mactra veneriformis were determined for 5 different water temperature regime (5, 10, 15, 20, $25^{\circ}C$) and salinity regime (8, 14, 20, 26, 32 ‰) with small group ($86.62{\pm}7.10mm$ in shell length) and large group ($147.99{\pm}10.83mm$ in shell length). Clearance rate and feeding increased with water temperature up to $20^{\circ}C$, but rapidly decreased at $25^{\circ}C$. The minimal clearance rate and feedign was recorded at $5^{\circ}C$. surf clam showed low clearance rate and feeding at low salinity (below 20 ‰) and maximum values at high salinity (26-32 ‰).