• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.44.4-45
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• 2018

(4179) Toutatis (Toutatis hereafter) is one of the Near-Earth Asteroids which has been studied most rigorously not only via ground-based photometric, spectroscopic, polarimetric, and radar observations, but also via the in-situ observation by the Chinese Chang'e-2 spacecraft. However, one of the most fundamental physical properties, the geometric albedo, is less determined. In order to derive the reliable geometric albedo and further study the physical condition on the surface, we made photometric observations of Toutatis near the opposition (i.e., the opposite direction from the Sun). We thus observed it for four days on 2018 April 7-13 using three 1.6-m telescopes, which consist of the Korean Microlensing Telescope Network (KMTNet). Since the asteroid has a long rotational period (5.38 and 7.40 days from Chang'e-2, Zhao et al., 2015), the continuous observations with KMTNet matches the purpose of our photometric study of the asteroid. The observed data cover the phase angle (Sun-asteroid-observer's angle) of 0.65-2.79 degree. As a result, we found that the observed data exhibited the magnitude changes with an amplitude of ~0.8 mag. We calculated the time-variable geometrical cross-section using the radar shape model (Hudson & Ostro 1995), and corrected the effect from the observed data to derive the geometric albedo. In this presentation, we will present our photometric results. In addition, we will discuss about the regolith particles size together with the polarimetric properties based on the laboratory measurements of albedo-polarization maximum.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.228.2-228.2
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• 2015

We have developed a TOF-MEIS system using 70~100 keV He+. A TOF-MEIS system was designed and constructed to minimize the ion beam damage effect by utilizing a pulsed ion beam with a pulse width < 1 ns and a TOF delay-line-detector with an 120 mm diameter and a time resolution of 180 ps. The TOF-MEIS is an useful tool for interfacial analysis of the composition and structure of nano and bio systems. Our recent applications are reported. We investigated the effect with Polyaspartic Acid (pAsp) and Osteocalcin on the initial bone growth of calcium hydroxyl appatite on a carboxyl terminated surface. When pAsp is not added to the self-assembled monolayers of Ca 2mM with Phosphate 1.2 mM, the growth procedure of calcium hydroxyl appatite cannot be monitored due to its rapid growth. When pAsp is added to the SAMs, the initial grow stage of the Ca-P can be monitored so that the chemical composition and their nucleus size can be analyzed. Firstly discovered the existence of 1-nm-sized abnormal calcium-rich clusters (Ca/P ~ 3) comprised of three calcium ions and one phosphate ion. First-principles studies demonstrated that the clusters can be stabilized through the passivation of the non-collagenous-protein mimicking carboxyl-ligands, and it progressively changes their compositional ratio toward that of a bulk phase (Ca/P~1.67) with a concurrent increase in their size to ~2 nm. Moreover, we found that the stoichiometry of the clusters and their growth behavior can be directed by the surrounding proteins, such as osteocalcin.

• Microbiology and Biotechnology Letters
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• v.13 no.2
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• pp.115-118
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• 1985

Rifamycin B oxidase converts rifamycin B to rifamycin S using oxygen as cosubstrate. Humnicola spp. (ATCC 20620) was treated with acetone and the cell powder was immobilized with cellulose acetate. The properties of the immobilized enzyme was examined. The optimum pHs of the immobilized and the free enzymes were 7.2. The optimum temperature of the immobilized enzyme was at 50-55$^{\circ}C$, which was 5$^{\circ}C$ higher than that of the free enzyme. The activities of the immobilized enzyme appeared less sensistive with respect to the changes of temperature and pH as compared to those of the free enzyme. Twenty percent of the enzyme activity was recovered when the enzyme was immobilized in 3mm beads. The storage stability was good below 4$0^{\circ}C$, but the activity decreased very rapidly above 5$0^{\circ}C$. The physical strength of the beads was good and was suitable as packing material in a three-phase enzyme reactor.

• YAKHAK HOEJI
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• v.54 no.4
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• pp.226-231
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• 2010

Oral fluid has become increasingly popular as an alternative specimen in the field of driving under the influence of drugs (DUID) and work place drug testing. In this study, an analytical method for the detection and quantification of ${\Delta}^9$-tetrahydrocannabinol (THC) and its metabolite, 11-nor-9-carboxy-${\Delta}^9$-tetrahydrocannabinol (THC-COOH) in oral fluid by SPE and GC-MS was established and fully validated. The stability of THC and THC-COOH in oral fluid during storage was also determined by examining the THC and THC-COOH concentration changes depending on time and container materials. Oral fluid samples were kept over 21 days at room temperature, $-4^{\circ}C$ and $-20^{\circ}C$ in two different specimen collection tubes; glass and polypropylene tubes. Three replicates for each condition with different temperature and types of a container were analyzed at five different time points over 21 days. When oral fluid samples were stored in glass tubes, the loss of both THC and THC-COOH was less than 10% at all room temperature, $-4^{\circ}C$ and $-20^{\circ}C$. However, in polypropylene tubes, the loss of both THC and THC-COOH increased significantly over the study period. In particular, the concentration of THC decreased more rapidly than that of THC-COOH at room temperature and the maximal percentage of THC lost was 90.3% after 21 days. The result indicates that it would be necessary to collect oral fluid samples in glass containers and cool the samples until analysis in order to prevent the degradation of analytes.

• Korean Journal of Materials Research
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• v.14 no.10
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• pp.701-706
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• 2004

Bismuth layered structure ferroelectric thin films, La-substituted $Bi_{4}Ti_{3}O_{12}$ ($Bi_{1-x}La_{x}Ti_{3}O_{12}$, x=0.75, BLT) were prepared on the $Pt(111)/Ti/SiO_2/Si(100)$ substrates by a sol-gel spin coating process. The thin films were annealed in various conditions, i.e., oxygen, nitrogen and vacuum atmospheres for various annealing time. We investigated the annealing condition effects on the grain orientation and ferroelectric properties. The measured XRD patterns revealed that the BLT thin films showed only $Bi_{4}Ti_{3}O_{12}$-type phase with random orientation. $La^{3+}$ ion substitution for $Bi^{3+}$ ion in perovskite layers of $Bi_{4}Ti_{3}O_{12}$ decreased the degree of c-axis orientation and increased the remanent polarization ($2P_{r}$). The remanent polarization ($2P_{r}$) and the coercive field ($2E_{c}$) of the BLT thin film annealed at $650^{\circ}C$ for 5 min in oxygen atmosphere were $87{\mu}C/cm^2$ and 182 kV/cm, respectively, at an applied electric field of 240 kV/cm. For all of the BLT thin films annealed in various conditions, the fatigue resistance was shown. The improvement of ferroelectric properties with La substitution in $Bi_{4}Ti_{3}O_{12}$ could be attributed to the changes in space charge densities and grain orientation in the thin film.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.1
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• pp.37-44
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• 2019

Recentrly, early dental care for children is becoming more important, and the number of children patients' dental services is on the rise. So, a variety of seduction therapies are needed to alleviate the tension in children who are anxious about dental care. This paper describes the development process and contents of system that can display the animation of different stories according to the treatment stage by grasping the use state of the treatment device in real time. In the animation, the hreo character and the villain, the cavity character, appear and the hero defeat the villain at each treatment stage. Animation is played when treatment starts and ends after treatment. Current existing one-side played animation of dental clinics is not enough to attract children's attention. If the flow of animation changes depending on the treatment process, it will give children a different enjoyment and consequently ease the tension over the treatment.

• Korean journal of food and cookery science
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• v.27 no.4
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• pp.67-73
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• 2011

This study was performed to assess the neuroprotective effects of methanolic extracts from sweet persimmon peel (PPE) against glutamate-induced cytotoxicity in hybridoma N18-RE-105 cells. The neuroprotective effects of PPE in N18-RE-105 cells were measured using the MTT reduction assay, LDH release assay, and phase-contrast microscopy. The results of the MTT reduction assay showed that treating cells with 500 ${\mu}g/ml$ PPE resulted in cell viability of 66.9%. Additionally, the morphological changes and the results of the LDH release assay showed that glutamate-induced damage to nerve cells was strongly inhibited by PPE. GSH content of N18-RE-105 cells was 3.5 ${\mu}M$ compared to that of the control, whereas pretreatment with 500 ${\mu}g/ml$ PPE increased GSH content by 4.7 ${\mu}M$. PPE was fractionated with hexane, and that layer had the highest neuroprotective effects in glutamate-stressed N18-RE-105 cells. In conclusion, our data showed that glutamate potentiated the effects of N18-RE-105 cell death by a mechanism involving oxidative stress. Therefore, PPE may be a potential candidate for prevention and therapy of neurodegenerative diseases.

• The Journal of Internal Korean Medicine
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• v.19 no.2
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• pp.7-16
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• 1998

Background and Purpose The increasing evidence for neurally mediated cardiac damage and sudden death has focused attention on the central autonomic control of cardiac function. Power spectral analysis of heart rate variability(HRV) can detect autonomic consequences of stroke. We performed power spectral analysis of heart rate variability from 24-hour holter recording to identify cerebral hemispheric lateralization and gender effect in cardiac autonomic control. Methods Data were obtained from 24-hour holter recordings in 30 consecutive patients with hemispheric brain infarction in the subacute phase. We analysed the time domain and frequency domain measures of HRV and ST segment by hemispheric lateralization and Gender. Results ST segment was depressed in women compared with man. There was no statistically significant differences between right and left hemisphere stroke patients in any standard index of HRV and ST segment changes. Conclusions These data are partial consistent with evidence from the recent literature that two cerebral hemispheres and gender have a differential influence on the nature and severity of cardiac dysfunction. We think the prospective and definite study was necessary.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.394-405
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• 2022

This paper presents the numerical estimation results of oil outflows from damaged single-hull and double-hull ships by using computational fluid dynamics (CFD) simulations. A CFD method for multi-phase flow analysis was used, and the effects of numerical parameters on oil flows was investigated. Numerical simulations were conducted to predict the changes in oil outflows under various damage conditions owing to grounding or collision accidents and verified through available experimental results. The present numerical results showed a good agreement with the experimental results according to the geometrical characteristics of single and double hulls. In particular, the oil outflows from double hulls accompanying complex interactions between water and oil were reasonably predicted a shown in the experiment. This study established a reliable CFD technique necessary for estimating the oil outflows of damaged ships.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.2
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• pp.82-86
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• 2006

Leukemia arises in hematopoietic progenitor cells and is characterized by impaired or blocked differentiation, uncontrolled proliferation and resistance to apoptosis. Molecular mechanisms underlying cellular functions by $As_2O_3$, however, have been poorly investigated. The consensus of several reports is that $As_2O_3$ induces apoptosis in leukemia cells by activating genes for apoptosis. The present study aimed to investigate the effects of $As_2O_3$ on the cell cycle and its morphological change and a relationship between the caspase-3 and $As_2O_3$-induced apoptosis. Caspase-3 is involved in $As_2O_3$-induced apoptosis in K562 cells. In this study, to address whether $As_2O_3$-induced apoptosis is mediated by caspase-3 activity, the same samples were probed with a specific antibody. The pretreatment of $25{\mu}M$ Z-VAD-fmk, a specific inhibitor of caspase, decreased $As_2O_3$-induced cytotoxicity. And $As_2O_3$ significantly increased the percentages of the cells accumulated in the G2/M phase of the cell cycle in a time- and dose-dependent manner. Chromatin condensational changes were observed with Hoechst 33258 staining after treatment of $As_2O_3$. It was shown that $As_2O_3$-induced apoptosis is controlled through caspase-3 activation. These results may provide a useful rationale for CML treatment.