• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.142-148
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• 1998

Environmental baseline information is necessary in order to assess the potential environmental impact of future manganese-nodule mining on the deep-seabed ecosystem. Total ATP (T-ATP), dissolved ATP (D-ATP) and particulate ATP (P-ATP) were measured to estimate total microbial biomass and to elucidate their vertical distribution patterns in the seabed of KODOS (Korea Deep Ocean Study) area, northeast equatorial Pacific Ocean. Within the upper 6 cm depth of sediment, the concentrations of T-ATP, D-ATP and P-ATP ranged from 4.4 to 40.6, from 0.6 to 16.1, and from 3.0 to 29.2 ng/g dry sediment, respectively. Approximately 84% of T-ATP, 81% of D-ATP, and 74% of P-ATP were present within the topmost 2 cm depth of sediment, and the distributions of ATP were well correlated with water content in the sediment. These results indicate that the distribution of total microbial biomass was largely determined by the supply of organic matter from surface water column. Fine-scale vertical variations of ATP were detected within 1-cm thick veneer of the sediment samples collected by multiple corer, while no apparent vertical changes were observed in the box-cored samples. It is evident that the box-core samples were disturbed extensively during sampling, which suggests that the multiple corer is a more appropriate sampling gear for measuring fine-scale vertical distribution pattern of ATP within thin sediment veneer. Overall results suggest that the concentrations of ATP, given their clear changes in vertical distribution pattern within 6 cm depth of sediment, are a suitable environmental baseline parameter in evaluating the variations of benthic microbial biomass that are likely to be caused by deep-seabed mining operation.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.721-727
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• 2002

In order to overcome trade-off among compositions, process and properties of the glasses with high PbO-base composition for PDP Rib, we studied glass crystallization and crystallization kinetics by Differential Thermal Analysis(DTA). Glass powder was obtained through melting/cooling/grinding, with 3 wt%TiO2 addition for the crystal nucleation and growth in $62PbO-19B_2O_3-10SiO_2-9(Al_2O_3-K_2O-BaO-ZnO)$(in wt%) composition glass. This powder was heat-treated for 1 to 10 h at $445^{\circ}C$ for nucleation. DTA measurements were performed to obtain the crystallization peak with $5∼25^{\circ}C/min$ heating rates. DTA crystallization peak temperature increased with increasing the heating rate and decreased with increasing the heating time. Because the Avrami parameter (n) was approximately 1, the surface crystallization occurred. The maximum nucleation time was 2 h.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.1
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• pp.109-117
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• 2016

This paper is focused on the determination of friction parameter which is a predominant factor in the design of inflatable structure system. This inflatable structure system is very valuably used to protect passively and rapidly the possibilities of tunnel damages by flooding threats and unusual leakage to be occurred during and after underground infrastructure construction. In particular, this system should be necessary in subsea tunnel. This study presents the experimental results obtained from the relative friction characteristics tests of the fabric materials that constitute the inflatable structure. In order to evaluate the relative friction behaviour of the inflatable structure system, friction tests and scaled model tunnel friction tests are carried out. The friction tests are carried out to determine the friction coefficient for different surface conditions between tunnel and inflatable structure. These friction coefficients are then evaluated and compared with the result obtained from the model tunnel friction tests. Interaction behaviours between tunnel and system are also reviewed and described in this study. The results clearly show that the friction coefficients derived from scaled model slippage tests are about 12% lower than values obtained from the friction tests. In addition, this study will be necessary to verify the real friction behaviour with prototype tests before applying in practice.

• Journal of Food Hygiene and Safety
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• v.23 no.4
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• pp.330-337
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• 2008

Betarich carrots were washed at various hypochloric acid(HCA) concentration and steeping time and packed in PE bag keeping at $8^{\circ}C$ for 12 days, in order eventually to examine microbiology, firmness, surface color, whiteness index(WI) and sensory quality. It was found that total bacterial counts at T-II and T-III with the 3 minute steeping were $4.37{\pm}0.19\;\log\;CFU/g$ and $4.27{\pm}0.13\;\log\;CFU/g$ respectively, showing slight decrease compared to control condition. E. coli was not detected at all treatments but less coliforms were detected at the 8-day treatments of T-II and T-III. Treatment of 3-minute steeping showed smaller reduction in firmness than that of I-minute steeping at 12-days, and T-1 (T-3) had the largest (smallest) reduction among them. It was also found that during the treatment the L-value showed decreasing trend, but the parameter a- and b-value showed increasing trend. WI increased, and its change was small with the increase in HCA concentration. The sensory quality check after 8 day storage showed that evaluation of the off-flavor appeared to be significantly high (p<0.05) at both non-treatment and HCA treatment. On the basis of the results above, it is likely to be more effective to prolong the period of circulation of beta rich carrots if you use HCA over 50 ppm for washing betarich carrots. This study will contribute to improve safety and quality in circulation of beta rich carrots.

• Journal of the Korean Chemical Society
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• v.32 no.2
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• pp.135-143
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• 1988

The correlations between chromatographic parameters of monosubstituted benzenes and several physical parameters in reversed phase liquid chromatography were studied. The relationships between retention data and polarity index were investigated by plotting $log(log k'_S/k'_B)$ vs. $P'_S/P'_B$ which were relative retention and relative polarity index of monosubstituted benzenes with respect to benzene, respectively. The linear relationship between relative retention and polarity index was observed for the monosubstituted benzenes having polar group, while in case of those having nonpolar group, the good linearity was observed by combination with relative molecular weight i.e. $(P'_S/P'_B)/(MW_S/MW_B)$. Multivariant regression analysis, $a(P'_S/P'_B)+b(MW_S/MW_B)$+c did not give significantly better correlations compared to single variant analysis, $a[(P'_S/P'_B)/(MW_S/MW_B)]$+c, but multiple stepwise regression analysis was recommended when several physical parameters simultaneously were chosen. The best correlation between retention data for monosubstituted benzenes taken from the literature and substituent constant(${\pi}$), derived from hydrophobic parameter and the first order molecular connectivity index$(^1{\chi}^{\nu})$, was established for methanol/water mobile phase system. The larger the surface coverage of the stationary phase, the higher was the correlation coefficient between these two parameters and retention data.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.2 s.29
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• pp.119-125
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• 2007

In order to illustrate the variation cf stratification and to know the effects of the temperature and the salinity on the stratification in the South Sea of Korea, the stratification parameter defined as potential energy anomaly (PEA, $V(J/m^3)$) introduced by Simpson and Hunter (1974) was used. The oceanographic data were obtained in August 1999 and February 2000 by National Fisheries Research and Development Institute (NFRDI). V in August is generally high in offshore and low in near shore. However, in February, V in the near shore is higher than that cf the offshore due to the vertical temperature gradient between surface and bottom layer caused by the expansion of South Korean Coastal Waters (SKCW). In summer, the increase of the atmospheric heating acts on the stratification as the buoyancy forcing. In most cases, the effect cf the temperature on the stratification is stronger than that of the salinity. The temperature effect is predominantly due to the extent of the intrusion of Tsushima Warm Current into the study area. However, at stations where V is high the effect of the salinity is also significant. In winter, V is very low due to the decrease cf the buoyancy forcing, but some stations show the relatively high V due to the expansion of SKCW and salinity in winter unlike that in summer makes the stratification weak.

• Clean Technology
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• v.26 no.2
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• pp.122-130
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• 2020

The isotherm, kinetic, and thermodynamic parameters of reactive blue 4 adsorbed by activated carbon were investigated for activated carbon dose, pH, initial concentration, contact time, and temperature data. The adsorption of the RB 4 dye by activated carbon showed a concave shape in which the percentage of adsorption increased in both directions starting from pH 7. The isothermal adsorption data were applied to Langmuir, Freundlich, and Temkin isotherms. Both Freundlich and Langmuir isothermal adsorption models fit well. From determined Freundlich separation factor (1/n = 0.125 ~ 0.232) and Langmuir separation factor (R_L = 1.53 ~ 1.59), adsorption of RB 4 by activated carbon could be employed as an effective treatment method. The constant related to the adsorption heat (B_T = 2.147 ~ 2.562 J mol^-1) of Temkin showed that this process was physical adsorption. From kinetic experiments, the adsorption process followed the pseudo second order model with good agreement. The results of the intraparticle diffusion model showed that the inclination of the first straight line representing the surface diffusion was smaller than that of the second straight line representing the intraparticle pore diffusion. Therefore, it was confirmed that intraparticle pore diffusion is the rate-controlling step. The negative Gibbs free energy change (ΔG = -3.262 ~ -7.581 kJ mol^-1) and the positive enthalpy change (ΔH = 61.08 kJ mol^-1) indicated the spontaneous and endothermic nature of the adsorption process, proving this process to be spontaneous and endothermic.

• Geotechnical Engineering
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• v.3 no.4
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• pp.41-54
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• 1987

A stochastic numerical analysis for predicting the groundswater fluctuations in hillside slopes is performed in this paper to account for the uncertainties associated with the rainfall and site characteristics. The effect of spatial variabilities of aquifer parameters and the effect of temporal variability of recharge on the groundwater fluctuations are studied in depth. The Kriging is used to account for the spatial tariabilities of aquifer parameters. This technique prolevides the best linear unbiased estimator of a parameter and its minimum variance from a litsitem number of measured data. A stochastic one-dimensional numerical model is delreloped b) combining the groundwater flow model, the Kriging, and the first-order second-moment analysis. In addition, a two dimensional detelministic groundwater model is developed to study the change of ground water surfas in the transverse direction as well as in the downslope direction. It is revealed that the undulations of the impervious bedrock in addition to the permeability and the specific yield have an important influence on the fluctuations of the groundwater surface. It is also found that th'e groundwater changes significantly in the transverse direction as well as in the downslope direction. The results obtained in this analysis may be used for evaluation of landslide risks due to high porewater pressure.

• Journal of The Korean Astronomical Society
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• v.36 no.3
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• pp.89-95
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• 2003

Observations of dark matter dominated dwarf and low surface brightness disk galaxies favor density profiles with a flat-density core, while cold dark matter (CDM) N-body simulations form halos with central cusps, instead. This apparent discrepancy has motivated a re-examination of the microscopic nature of the dark matter in order to explain the observed halo profiles, including the suggestion that CDM has a non-gravitational self-interaction. We study the formation and evolution of self-interacting dark matter (SIDM) halos. We find analytical, fully cosmological similarity solutions for their dynamics, which take proper account of the collisional interaction of SIDM particles, based on a fluid approximation derived from the Boltzmann equation. The SIDM particles scatter each other elastically, which results in an effective thermal conductivity that heats the halo core and flattens its density profile. These similarity solutions are relevant to galactic and cluster halo formation in the CDM model. We assume that the local density maximum which serves as the progenitor of the halo has an initial mass profile ${\delta}M / M {\propto} M^{-{\epsilon}$, as in the familiar secondary infall model. If $\epsilon$ = 1/6, SIDM halos will evolve self-similarly, with a cold, supersonic infall which is terminated by a strong accretion shock. Different solutions arise for different values of the dimensionless collisionality parameter, $Q {\equiv}{\sigma}p_br_s$, where $\sigma$ is the SIDM particle scattering cross section per unit mass, $p_b$ is the cosmic mean density, and $r_s$ is the shock radius. For all these solutions, a flat-density, isothermal core is present which grows in size as a fixed fraction of $r_s$. We find two different regimes for these solutions: 1) for $Q < Q_{th}({\simeq} 7.35{\times} 10^{-4}$), the core density decreases and core size increases as Q increases; 2) for $Q > Q_{th}$, the core density increases and core size decreases as Q increases. Our similarity solutions are in good agreement with previous results of N-body simulation of SIDM halos, which correspond to the low-Q regime, for which SIDM halo profiles match the observed galactic rotation curves if $Q {\~} [8.4 {\times}10^{-4} - 4.9 {\times} 10^{-2}]Q_{th}$, or ${\sigma}{\~} [0.56 - 5.6] cm^2g{-1}$. These similarity solutions also show that, as $Q {\to}{\infty}$, the central density acquires a singular profile, in agreement with some earlier simulation results which approximated the effects of SIDM collisionality by considering an ordinary fluid without conductivity, i.e. the limit of mean free path ${\lambda}_{mfp}{\to} 0$. The intermediate regime where $Q {\~} [18.6 - 231]Q_{th}$ or ${\sigma}{\~} [1.2{\times}10^4 - 2.7{\times}10^4] cm^2g{-1}$, for which we find flat-density cores comparable to those of the low-Q solutions preferred to make SIDM halos match halo observations, has not previously been identified. Further study of this regime is warranted.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.118-126
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• 2011

The objective of this paper is to study the structural behavior of Composite Basement Wall (CBW) according to shear span-to-depth ratio through an experiment and predict the nonlinear behavior of CBW by using ADINA program widely has been being used for FE analysis. Especially, this study focuses on the part of CBW in which the Reinforced Concrete (RC) is under compression stress; At the region of CBW around each floor, RC part stresses by compressive force when lateral press by soil acts on the wall. The contact condition between RC wall and steel (H-Pile) including stud connector is main factor in the analysis since it governs overall structural behavior. In order to understand the structural behavior of CBW whose RC part is under compressive stress, an experimental work and finite element analysis were performed. Main parameter in the test is shear span-to-depth ratio. For simplicity in analysis, reinforcements were not modeled as a seperated element but idealized as smeared to concrete. All elements were modeled to have bi-linear relation of material properties. Three type of contact conditions such as All Generate Option (AGO), Same Element Group Option with Tie(SEGO-T) and Same Element Group Option with Not tie(SEGO-NT) were considered in the analysis. For each analysis, the stress flow and concentration were reviewed and analysis result was compared to test one. From the test result, CBW represented ductile behavior by contribution of steel member even if it had short shear span-to-depth ration which is close to "1". The global composite behavior of CBW whose concrete wall was under compressive stress could be predicted by using contact element in ADINA program. Especially, the modeling by using AGO and SEGO-T showed more close relation on comparing with test result.