• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3213-3217
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• 2012

Reactive adsorption desulfurization (RADS) experiments were conducted over a series of commercial metal oxide supports ($Al_2O_{3-}$, $SiO_{2-}$, $TiO_{2-}$ and $ZrO_{2-}$) supported Ni/ZnO adsorbents. The adsorbents were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), and Fourier transform infrared spectroscopy (FTIR) in order to find out the influence of specific types of surface chemistry and structural characteristics on the sulfur adsorptive capacity. The desulfurization performance of all the studied adsorbents decreased in the following order: Ni/ZnO-$TiO_2$ > Ni/ZnO-$ZrO_2$ > Ni/ZnO-$SiO_2$ > Ni/ZnO-$Al_2O_3$. Ni/ZnO-$TiO_2$ shows the best performance and the three hour sulfur capacity can achieve 12.34 mg S/g adsorbent with a WHSV of $4h^{-1}$. Various characterization techniques suggest that weak interaction between active component and support component, high dispersion of NiO and ZnO, high reducibility and large total Lewis acidity of the adsorbents are important factors in achieving better RADS performance.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2508-2512
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• 2012

Cold shock proteins (CSPs) are a family of proteins induced at low temperatures. CSPs bind to single-stranded nucleic acids through the ribonucleoprotein 1 and 2 (RNP 1 and 2) binding motifs. CSPs play an essential role in cold adaptation by regulating transcription and translation via molecular chaperones. The solution nuclear magnetic resonance (NMR) or X-ray crystal structures of several CSPs from various microorganisms have been determined, but structural characteristics of psychrophilic CSPs have not been studied. Therefore, we optimized the purification process to obtain highly pure Lm-Csp and determined the three-dimensional structure model of Lm-Csp by comparative homology modeling using MODELLER on the basis of the solution NMR structure of Bs-CspB. Lm-Csp consists of a ${\beta}$-barrel structure, which includes antiparallel ${\beta}$ strands (G4-N10, F15-I18, V26-H29, A46-D50, and P58-Q64). The template protein, Bs-CspB, shares a similar ${\beta}$ sheet structure and an identical chain fold to Lm-Csp. However, the sheets in Lm-Csp were much shorter than those of Bs-CspB. The Lm-Csp side chains, E2 and R20 form a salt bridge, thus, stabilizing the Lm-Csp structure. To evaluate the contribution of this ionic interaction as well as that of the hydrophobic patch on protein stability, we investigated the secondary structures of wild type and mutant protein (W8, F15, and R20) of Lm-Csp using circular dichroism (CD) spectroscopy. The results showed that solvent-exposed aromatic side chains as well as residues participating in ionic interactions are very important for structural stability. Further studies on the three-dimensional structure and dynamics of Lm-Csp using NMR spectroscopy are required.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4586-4594
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• 2015

This study investigated the relationship between self-esteem and the maladaptive behavior of the youth and examined the moderating effects of father attachment and mother attachment in the relationship of self-esteem and maladaptive behavior. Utilizing SPSS win18.0 program for data analysis, after carrying out descriptive statistics analysis and a simple correlation analysis, hierarchical multiple regression analysis was performed to investigate the interaction model, the primary purpose of this study. The results of this study are as follows. First, the relationship of both self-esteem and maladaptive behaviors of adolescents was significant in the negative direction. Second, father attachment showed no moderation effect in the relationship between self-esteem and maladaptive behavior of adolescents. Third, mother attachment played a quantitative moderating role in the relationship of self-esteem and maladaptive behaviors of adolescents. This study suggested the implication to reduce youth maladaptive behavior in the base of these results.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.52.2-52.2
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• 2015

SgrA* located in the center of the Milky Way is of great interest to understand the physics of supermassive black hole(SMBH) and the interaction of the G2 cloud around SgrA* with the accretion flow which was expected since 2013. In order to seize this rare opportunity, KVN and VERA Array (so called, KaVA) has started an intensive monitoring program of SgrA* at 22/43 GHz where scatter broadening is reduced compared to lower frequency VLBI observations. We present the results of KaVA SgrA* observation together with Takahagi (32m) and Yamaguchi (32m) telescopes at 22 GHz on March 24, 2013. We have tested both a standard amplitude calibration methods using the Tsys and antenna gain information and a template amplitude calibration method which uses a peak of H2O maser line of nearby maser source (SgrB2), and found that the latter method is useful when an accuracy of Tsys measurement or antenna gain of a telescope is poor. In our comparison, the difference between the two methods is around 20% (~5% for the KVN and ~15% for the VERA when the elevation is above $20^{\circ}$). We also imaged SgrA* with a total flux of ~0.7 Jy at 22GHz, and fitted an elliptical Gaussian model which has a size of ~2.5mas for major axis and ~1.7mas for minor axis, respectively.

• Journal of computational fluids engineering
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• v.21 no.2
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• pp.112-119
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• 2016

NEXTSat-1 is the next-generation small-size artificial satellite system planed by the Satellite Technology Research Center(SatTReC) in Korea Advanced Institute of Science and Technology(KAIST). For the control of attitude and transition of the orbit, the system has adopted a RHM(Resisto-jet Head Module), which has a very simple geometry with a reasonable efficiency. An axisymmetric model is devised with two coil-resistance heaters using xenon(Xe) gas, and the minimum required specific impulse is 60 seconds under the thrust more than 30 milli-Newton. To design the module, seven basic parameters should be decided: the nozzle shape, the power distribution of heater, the pressure drop of filter, the diameter of nozzle throat, the slant length and the angle of nozzle, and the size of reservoir, etc. After quasi one-dimensional analysis, a theoretical value of specific impulse is calculated, and the optima of parameters are found out from the baseline with a series of multi-physical numerical simulations based on the compressible Navier-Stokes equations for gas and the heat conduction energy equation for solid. A commercial code, COMSOL Multiphysics is used for the computation with a FEM (finite element method) based numerical scheme. The final values of design parameters indicate 5.8% better performance than those of baseline design after the verification with all the tuned parameters. The present method should be effective to reduce the time cost of trial and error in the development of RHM, the thruster of NEXTSat-1.

• Journal of computational fluids engineering
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• v.21 no.2
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• pp.90-98
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• 2016

A numerical study is conducted on thermal performance of a large-area hot plate specially designed as a heating and cooling tool for thermal nanoimprint lithography process. The hot plate has a dimension of $240mm{\times}240mm{\times}20mm$, in which a series of cartridge heaters and cooling holes are installed. The material is stainless steel selected for enduring the high molding pressure. A numerical model based on the ANSYS Fluent is employed to predict the thermal behavior of the hot plate both in heating and cooling phases. The PID thermal control of the device is modeled by adding user defined functions. The results of numerical computation demonstrate that the use of cartridge heaters provides sufficient heat-up performance and the active liquid cooling in the cooling holes provides the required cool-down performance. However, a crucial technical issue is raised that the proposed design poses a large temperature non-uniformity in the steady heating phase and in the transient cooling phase. As a remedy, a new hot plate in which heat pipes are installed in the cooling holes is considered. The numerical results show that the installation of heat pipes could enhance the temperature uniformity both in the heating and cooling phases.

• 대한예방의학회:학술대회논문집
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• 1994.02a
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• pp.651-657
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• 1994

To assess quantitatively the association between benzene exposure and leukemia, we examined the mortality rate of a cohort with occupational exposure to benzene. Cumulative exposure for each cohort member was estimated from historical air-sampling data and, when no sampling data existed, from interpolation on the basis of existing data. The overall standardized mortality ratio (a measure of relative risk multiplied by 100) for leukemia was 337 (95 percent confidence interval, 154 to 641), and that for multiple myeloma was 409 (95 percent confidence interval, 110 to 1047). With stratification according to levels of cumulative exposure, the standardized mortality ratios for leukemia increased from 109 to 322, 1186, and 6637 with increases in cumulative benzene exposure from less than 40 parts per million-years (ppm-years), to 40 to 199, 200 to 399, and 400 or more. respectively. A cumulative benzene exposure of 400 ppm years is equivalent to a mean annual exposure of 10 ppm over a 40-year working lifetime; 10 ppm is the currently enforceable standard in the United States for occupational exposure to benzene. To examine the shape of the exposure-response relation, we performed a conditional logistic-regression analysis, in which 10 controls were matched to each cohort member with leukemia. From this model, it can be calculated that protection from benzene induced leukemia would increase exponentially with any reduction in the permissible exposure limit.

• Journal of Biomedical Engineering Research
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• v.31 no.6
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• pp.438-448
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• 2010

The social activities of the elderly have been increasing as our society progresses toward an aging society. As their activities are increased, the occurrence of falls that could lead to fractures are increased. Falls are serious health hazards to the elderly and we need more thorough understanding of falls including the progress of falls and the impact area in various fall directions. Many of the traditional methods of falls research dealt with voluntary falls by younger subject since older subject can easily get fracture from voluntary falls. So, it has been difficult to get exact data about falls of the elderly. Here, we tried to capture the characteristics of the movements of major joints using three dimensional motion capture system during falls experiments using a moving mattress that can safely induce unexpected falls. Healthy younger subjects participated in the actual falls experiment and the moving mattress was actuated by a pneumatic system. The kinematic parameters such as velocities of major segments were imported to a computer simulation environment and falls to hard surfaces were simulated in a computational environment using a realistic human model of aged persons. The simulation was able to give approximations to contact forces which can occur during actual falls. And we designed impact absorption system to reduce the impact during falls. We can adapt this system to fracture prevention system that we are going to study.

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.96-109
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• 1997

In order to simulate the corrosion behavior of Zr-4 alloy in pressurized water reactors it was implanted (or bombarded) with 190ke V $Zr^+\; and \;Ar^+$ ions at liquid nitrogen temperature and room temperature respectively up to a dose of $5times10^{15} \sim 8\times10^{16} \textrm{ions/cm}^2$ The oxidation behavior and electrochemical vehavior were studied on implanted and unimplanted samples. The oxidation kinetics of the experimental samples were measured in pure oxygen at 923K and 133.3Pa. The corrosion parameters were measured by anodic polarization methods using a princeton Applied Research Model 350 corrosion measurement system. Auger Electron Spectroscopy (AES) and X-ray Photoelectric Spectroscopy (XPS) were employed to investigate the distribution and the ion valence of oxygen and zirconium ions inside the oxide films before and after implantation. it was found tat: 1) the $Zr^+$ ion implantation (or bombardment) enhanced the oxidation of Zircaloy-4 and resulted in that the oxidation weight gain of the samples at a dose of $8times10^{16}\textrm{ions/cm}^2$ was 4 times greater than that of the unimplantation ones;2) the valence of zirconium ion in the oxide films was classified as $Zr^0,Zr^+,Zr^{2+},Zr^{3+}\; and \;Zr^{4+}$ and the higher vlence of zirconium ion increased after the bombardment ; 3) the anodic passivation current density is about 2 ~ 3 times that of the unimplanted samples; 4) the implantation damage function of the effect of ion implantation on corrosion resistance of Zr-4 alloy was established.

• Journal of Oriental Neuropsychiatry
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• v.24 no.3
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• pp.309-320
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• 2013

Objectives : There is a possibility LRE as remedy in Alzheimer disease (AD), but it's nerve protection effect and mechanism have to be elucidate. In this research, we applied LRE on $A{\beta}_{25-35}$ pre-treated SH-SY5Y cells, to find out the nerve protection effect and mechanism in AD cell model. Methods : We tried to confirm that effect by experimenting with 20, 50, and $100{\mu}g/ml$ concentration of LRE as a medicine. Next experiment, we assessed damage effect which induced $A{\beta}_{25-35}$, known to cause AD, on SH-SY5Y cell. In addition, cellular viability test is executed under $H_2O_2$ treatment condition in a SH-SY5Y cell. Results : 1. In $A{\beta}_{25-35}$ treated SH-SY5Y cell, LRE exhibited an anti-phosphorylation effect about tau protein, JNK, and IKB. 2. LRE prevent nerve cell apoptosis, which indued $A{\beta}_{25-35}$ and oxidative stress, modify JNK engaged synaptic structure and $NF{\kappa}B$ induced p75-neurotrophin receptor polymorphism. Conclusions : We found that LRE prevented oxidative stress-induced cellular destruction, for example, increased SOD activity of $A{\beta}_{25-35}$ treated SH-SY5Y cell and reduced toxicity of oxygen free radical. Consequently, the ingredients of LRE have a role as a catalyzer for $A{\beta}_{25-35}$ clearance and as scavenger for active oxygen free radical.