• Journal of the Korean institute of surface engineering
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• v.41 no.5
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• pp.226-231
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• 2008

Titanium and its alloy have been widely used in dental implant and orthopedic prostheses. Electrochemical characteristics of dental implant in the various simulated body fluids have been researched by using electrochemical methods. Ti-6Al-4V alloy implant was used for corrosion test in 0.9% NaCl, artificial saliva and simulated body fluids. The surface morphology was observed using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The electrochemical stability was investigated using potentiosat (EG&G Co, 263A). The corrosion surface was observed using scanning electron microscopy (SEM). From the results of potentiodynamic test in various solution, the current density of implant tested in SBF and AS solution was lower than that of implant tested in 0.9% NaCl solution. From the results of passive film stability test, the variation of current density at constant 250 mV showed the consistent with time in the case of implant tested in SBF and AS solution, whereas, the current density at constant 250mV in the case of implant tested in 0.9% NaCl solution showed higher compared to SBF and AS solution as time increased. From the results of cyclic potentiodynamic test, the pitting potential and |$E_{pit}\;-\;E_{corr}$| of implant tested in SBF and AS solution were higher than those of implant tested in 0.9% NaCl solution.

• Journal of Embryo Transfer
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• v.27 no.2
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• pp.107-111
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• 2012

Miniature pig sperm cryopreservation is continually researched in biotechnology for breed conservation and reproduction. It is important to control the temperature at each stage of cryopreservation and cryoprotectant. It is also necessary to find the optimal cryoprotectant concentration and chemical elements of the extender. Recently, many studies have used various cryoprotectant materials, such as dimethyl sulphoxide (DMSO), ethylene glycol (EG), antifreeze protein (AFP), amides, and glycerol. Glycerol is a commonly used cryoprotectant. However, glycerol has critical cytotoxic properties, including osmotic pressure and it can cause irreversible damage to live cells. Therefore, We focused on membrane fluidity modifications can reduce cell damage from freezing and thawing procedures and evaluated on the positive effects of trehalose to the viability, chromatin integrity, and motility of boar sperm. Miniature pig sperm was separated from semen by washing with modified- Modena B (mMB) extender. After centrifugation, the pellet was diluted with the prepared first extender. This experiment was designed to compare the effects that sperm cryopreservation using two different extenders has on sperm chromatin. The control group used the glycerol only and it was compared with the glycerol and glycerol plus trehalose extender. Sperm viability and motility were evaluated using WST1 assays and computer-assisted semen assays (CASA). Chromatin structure was examined using acridine orange staining. For the motility descriptors, trehalose caused a significant (p<0.01) increase in total motility ($57.80{\pm}4.60%$ in glycerol vs. $75.50{\pm}6.14%$ in glycerol + trehalose) and progressive ($51.20{\pm}5.45%$ in glycerol vs. $70.74{\pm}8.06%$ in glycerol + trehalose). A significant (p<0.05) increase in VAP ($42.70{\pm}5.73{\mu}m/s$ vs. $59.65{\pm}9.47{\mu}m/s$), VSL ($23.06{\pm}3.27{\mu}m/s$ vs. $34.60{\pm}6.58{\mu}m/s$), VCL ($75.36{\pm}11.36{\mu}m/s$ vs. $99.55{\pm}12.91{\mu}m/s$), STR ($54.4{\pm}2.19%$ vs. $58.0{\pm}1.63%$), and LIN ($32.2{\pm}2.05%$ vs. $36.0{\pm}2.45%$) were also detected, respectively. The sperm DNA fragmentation index was 48.8% to glycerol only and 30.6% to glycerol plus trehalose. Trehalose added group showed higher percentages of sperm motility, stability of chromatin structure than glycerol only. In this study, we suggest that trehalose is effective in reducing freezing damage to miniature pig sperm and can reduce chromatin damage during cryopreservation.

• KSBB Journal
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• v.16 no.1
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• pp.48-53
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• 2001

Bovine serum albumin(BSA) was solubilized into the reverse micellar phase consisting of sodium bis(2-ethylhexyl) sulfosuccinate(AOT) and isooctane using the phase transfer method. Of particular interest in this study were the effects of pH and the added salt type and concentration on the solubilization efficiency. When univalent or divalent salts such as KCl, NaCl, $MgCl_2$, or $CaCl_2$ were added to the aqueous phase at a concentration of 0.1 M, maximum solubilization efficiency was attained at a pH ranging from 5 to 7, depending on the added salt type. Increased salt concentration up to 1 M resulted in an increased solubilization efficiency for $CaCl_2$ and NaCl, while the addition of $MgCl_2$ beyond 0.1 M showed an anomalous trend. Further, it was noteworthy that too a large extent the protein precipitated in the interface between the organic and aqueous phases at lower pHs and lower salt concentrations. The size of the reverse micelle water pool was estimated by measuring the molar ratio of the surfactant to the water, $W_0$. Irrespective of pH in the aqueous phase, the resulting value of $W_0$ was almost constant, eg., 20 for $MgCl_2$ . However, the value of $W_0$ decreased with increased salt concentration in the cases of KCl and $CaCl_2$.

• Korean Journal of Animal Reproduction
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• v.19 no.3
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• pp.217-226
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• 1995

The objective of this experiment was to test the effect of EG F on nuclear maturation of pig immature oocytes in vitro. Basic medium used TCM-199 supplemented with 0.2 mM pyruvate, 1 ${\mu}\textrm{g}$/ml estradiol-I7$\beta$ and 25 ${\mu}\textrm{g}$/ml gentamycin, this medium treated with EGF, FSH and FBS. Experiment 1 examined to the effect according to the addition of FSH or EGF (0, 1. 10 and 100 ng EGF/ml) in oocytes maturation. Nuclear maturation rates (M ll %) of 1, 10 and 100 ng EGF/ml (83.0. 8fi.7 and H7.5%) treatments were significantly higher than those of non- and FSH-treated groups (27.3 and 60.3%, p < 0. 001). Experiment 2 examined to the interactive effects of EGF. FSH or FBS during oocytes maturation. Nuclear maturation rates (M ll %) of EGF alone, EGF plus FSH, EGF plus FBS, FSH plus FBS, and EGF plus FSH added FBS treatments (86.7, 90.2, 87.1. 89.6% and 92.6%) were significantly higher than those of non, FSH, and FBS alone treatments (22.3, 52.2 and 42.3%, p < 0.001). Also, cumulus cells expansion of oocytes maturation was examined to total treatments. Normal cumulus cells expansion was shown by FSH plus FBS, EGF or EGF with FBS combination treatments, but cumulus cells of oocyte complexes were still clumped together in EGF-treated groups although they had separated from oocytes. However, EGF showed a positive on nuclear maturation. These results conclude that EGF alone can stimulate nuclear maturation in pig immature oocytes.

• Korean journal of communication and information
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• v.28
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• pp.171-218
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• 2005

There is a original routine on dealing the first edition newspaper in Korea. Korean national morning newspapers print about 0.5% of total circulation as the first edition and sale those only in Seoul where the newspapers is published. The dead line of first edition is even about 5 pm. According to this routine which couldn't be found in the advanced western nations, like UK, USA etc., there can be some original characteristics and problems on the contents of Korean national morning newspapers. The present study investigated what the characteristics and problems means on the quality of newspaper and the free flow of diverse informations and opinions. Content analysis comparing the first edition to the last edition of 8 national morning newspapers is used to reveal the original characteristics and problems. Major findings in the result of the content analysis are three. First, the quality of the newspapers is damaged by the early dead line. Second, Inter-media agenda setting, which minor papers follow major papers on not only contents but also tone & manner, is manifest. Third, the early time publishing of the first edition allow the reported group including government and business sorter to take time to do make some negotiations on the articles about them, in which procedure even about 40% of total observed articles are changed(eg. removed, replaced, modified).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.211-220
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• 1998

The stochiometric composition of $AgGaS_2$polycrystal source materials for the single crystal thin films were prepared from horizontal furnace. From the extrapolation method of X-ray diffraction patterns, it was found that the polycrystal $AgGaS_2$has tetragonal structure of which lattice constant $a_0\;and \;c_0$ were 5.756 $\AA$ and 10.305 $\AA$, respectively. $AgGaS_2$single crystal thin film was deposited on throughly etched GaAs(100) substrate from mixed crystal $AgGaS_2$by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $590^{\circ}C$ and $440^{\circ}C$ respectively, and the growth rate of the single crystal thin films was about 0.5 $mu \textrm{m}$/h. The crystallinity of the grown single crystal thin films was investigated by the DCRC (double crystal X-ray diffraction rocking curve). The optical energy gaps were found to be 2.61 eV for $AgGaS_2$single crystal thin films at room temperature. The temperature dependence of the photocurrent peak energy is well explained by the Varshni equation, then the constants in the Varshni equation are given by${\Alpha};=;8.695{\times}10^{-4};eV/K,and;{\beta};=;332;K$. from the photocurrent spectra by illumination of polarized light of the $AgGaS_2$single crystal thin film, we have found that crystal field splitting $\Delta$Cr was 0.28 eV at 20 K. From the PL spectra at 20 K, the peaks corresponding to free and bound excitons and a broad emission band due to D-A pairs are identified. The binding energy of the free excitons are determined to be 0.2676 eV and 0.2430 eV and the dissociation energy of the bound excitons to be 0.4695 eV.

• Journal of Technologic Dentistry
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• v.30 no.1
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• pp.25-31
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• 2008

Cp-Ti and Ti-6Al-4V alloys commonly used dental implant materials, particularly for orthopaedic and osteosynthesis because of its suitable mechanical properties and excellent biocompatibility. This alloys have excellent corrosion behavior in the clinical environment. The first factor to decide the success of dental implantation is sufficient osseointegration and high corrosion resistance between on implant fixture and its surrounding bone tissue. In this study, in order to increase corrosion resistance and biocompatibility of Cp-Ti and Ti-6Al-4V alloy that surface of manufactured alloy was coated with TiN by RF-magnetron sputtering method. The electrochemical behavior of TiN coated Cp-Ti and Ti-6Al-4V alloy were investigated using potentiodynamic (EG&G Co, PARSTAT 2273. USA) and potentiostatic test (250mV) in 0.9% NaCl solution at 36.5 $\pm$ 1$^{\circ}C$. These results are as follows : 1. From the microstructure analysis, Cp-Ti showed the acicular structure of $\alpha$-phase and Ti-6Al-4V showed the micro-acicular structure of ${\alpha}+{\beta}$ phase. 2. From the potentiodynamic test, Ecorr value of Cp-Ti and Ti-6Al-4V alloys showed -702.48mV and -319.87mV, respectively. Ti-6Al-4V alloy value was higher than Cp-Ti alloy. 3. From the analysis of TiN and coated layer, TIN coated surface showed columnar structure with 800 nm thickness. 4. The corrosion resistance of TiN coated Cp-Ti and Ti-6Al-4V alloys were higher than those of the non-coated Ti alloys in 0.9% NaCl solution from potentiodynamic test, indicating better protective effect. 5. The passivation current density of TiN coated Cp-Ti and Ti-6Al-4V alloys were smaller than that of the noncoated implant fixture in 0.9% NaCl solution, indicating the good protective effect resulting from more compact and homogeneous layer formation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.919-929
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• 2013

Recently, a variety of IT technologies are applied to the vehicle. However, some vehicle-IT technologies without security considerations may cause security problems. Specially, some researches about a smart key system applied to automobiles for authentication show that the system is insecure from replay attacks and modification attacks using a wireless signal of the smart key. Thus, in this paper, we propose an authentication method for the driver by using driving patterns. Nowadays, we can obtain driving patterns using the In-vehicle network data. In our authentication model, we make driving ppatterns of car owner using standard normal distribution and apply these patterns to driver authentication. To validate our model, we perform an k-fold cross validation test using In-vehicle network data and obtain the result(true positive rate 0.7/false positive rate is 0.35). Considering to our result, it turns out that our model is more secure than existing 'what you have' authentication models such as the smart key if the authentication result is sent to the car owner through mobile networks.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.3
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• pp.363-368
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• 1999

This study was to confirm whether the vitrification method using EFS40 freezing solution has detrimental effect on the cytoskeleton and chromosome constitution of the immature mouse oocytes by indirect immunocytochemistry and chromosome analysis. Immature mouse oocytes were vitrified using EFS40 (40% EG, 18% ficoll, 0.5 M sucrose diluted in M2 medium), thawed and then survived oocytes were in vitro matured for 16 hr. When the microtubule morphology and micro filament distribution in vitrified-thawed immature mouse oocytes were examined, normal percentage of two cytoskeleton in vitrified group (93.9 and 100.0%) was not significantly different from that in control (100.0 and 100.0%) and exposed group (94.4 and 100.0%). The rate of oocytes containing a normal chromosome number in vitrified group was 65.8%, this result was not significantly different from that in control (79.6%) and exposed group (69.0%). These results indicated that exposure to cryoprotectant or freezing has not effect on the alteration of cytoskeleton morphology and the chromosome constitution of mouse oocytes and that our vitrification methods using EFS40 freezing solution was suitable for the cryopreservation of immature mouse oocytes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.1
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• pp.1-6
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• 2012

In this study, we conducted to identify predictive parameters affecting the head rice ratio for developing high quality rice cultivar adaptable to the early-transplanting cultivation. The recombinant inbred lines (RILs) population from a cross between the parents of Pungmi and Koshihikari was used for test materials. Variations were observed in most of the measurements, eg culm length (ranging from 51.0 cm to 97.0 cm), amylose content (14.0~20.1%), protein content (5.2~7.4%), pasting properties (peak viscosity, 227.2~309.8 RVU) and head rice ratio (67.7~96.7%). Significant correlations between head rice ratio versus culm length (0.443) and head rice ratio versus protein content (-0.458) were detected in RIL population. However, culm length was negatively related to lodging tolerance. In order to develop a commercially suitable cultivar, selection for short culm and high head rice ratio of rice grains with physiochemical properties such as protein content, amylase content and taste value should be considered. This results can be used to increase the efficiency of breeding program for developing a new early-maturing rice variety adaptable to early transplanting cultivation in Korea.