• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.34.1-34.1
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• 2008

Cosmic ray (CR)s are energetic particles that are found in space and filter through our atmosphere. They are classified with galactic cosmic ray (GCR)s and solar cosmic ray (SCR)s from their origins. The process of a CR particle colliding with particles in our atmosphere and disintegrating into smaller pions, muons, neutrons, and the like, is called a cosmic ray shower. These particles can be measured on the Earth's surface by neutron monitor (NM)s. Regarding with the space weather, there are common types of short term variation called a Forbush decrease (FD) and a Ground Level Enhancement (GLE). In this talk, we will briefly introduce our recent studies on CRs observed by NM: (1) simultaneity of FD depending on solar wind interaction, (2) an association between GLE and solar proton events, and (3) diurnal variation of the GCR depending on geomagnetic cutoff rigidity. NM will provide a crucial information for the Korea Space Weather Prediction Center (KSWPC).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.3
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• pp.137-145
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• 2014

We present a design sensitivity analysis(DSA) method for multiscale problems based on bridging scale decomposition. In this paper, we utilize a bridging scale method for the coupled system analysis. Since the analysis of full MD systems requires huge amount of computational costs, a coupled system of MD-level and continuum-level simulation is usually preferred. The information exchange between the MD and continuum levels is taken place at the MD-continuum boundary. In the bridging scale method, a generalized Langevin equation(GLE) is introduced for the reduced MD system and the GLE force using a time history kernel is applied at the boundary atoms in the MD system. Therefore, we can separately analyze the MD and continuum level simulations, which can accelerate the computing process. Once the simulation of coupled problems is successful, the need for the DSA is naturally arising for the optimization of macro-scale design, where the macro scale performance of the system is maximized considering the micro scale effects. The finite difference sensitivity is impractical for the gradient based optimization of large scale problems due to the restriction of computing costs but the analytical sensitivity for the coupled system is always accurate. In this study, we derive the analytical design sensitivity to verify the accuracy and applicability to the design optimization of the coupled system.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1375-1377
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• 1995

This paper describes characteristic of ozone Generation by positive streamer corona discharge. Experiments were carried out with needle-plane Electrodes in a pyrex glass tube, in order to in crease the ozone yield. The results of Experiments confirmed needle an gle $45^{\circ}$ Gap spacing 15mm is adaptive Electrode arrangement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.3
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• pp.311-318
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• 2004

We have studied electro-optic characteristics as a function of pretilt angle ($\theta$$_{p}$) in the fringe-field switching (FFS) mode using the LC with positive dielectric anisotropy. When $\theta$$_{p}$ is increased from 0$^{\circ}$ to 20$^{\circ}$, a maximum transmittance and an operating voltage are obviously decreased. In the viewing angle characteristics, the cell with low pretilt angle has a wide region for the contrast ratio greater than 5 and has a best luminance uniformity. Therefore, in the FFS device, a low pretilt angle is favored for high transmittance and wide viewing angle.gle.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.1
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• pp.15-21
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• 2018

Skin-aging is accelerated by the increased expression of MMP-1 caused by the increased skin temperature induced by IR/visible light as well as UV. Thus, the control of skin temperature is important to inhibit heat-induced aging. Many studies have been conducted to lower the skin temperature through the controlling transient receptor potential melastatin 8 channel (TRPM8), which is known as the cold and menthol receptor 1 (CMR1) and is activated at temperature below $25^{\circ}C$. In this study, we first investigated the effect of Ganoderma lucidum extract (GLE) on the TRPM8 expression. Results showed that GLE, hexane (Hex) fractions and water fractions increased the TRPM8 expression in a dose dependent manner. Active compound in Hex fractions were separated by chromatography and analyzed by $^1H$ and $^{13}C$ NMR spectroscopy. The isolated compounds were identified as ergosterol and it also significantly increased the TRPM8 expression. Taken together, these results strongly suggest that G. lucidum extract and ergosterol have the potential as a new cooling ingredient in the cosmetics.

• Journal of the Korean Ceramic Society
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• v.35 no.3
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• pp.303-309
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• 1998

The fabrication of Al2O3/Al composite by pressureless infiltration was investigated by the change of Mg and Si content in Al alloy infiltration process and infiltration atmosphere. The effect of alloying elements infiltration atmosphere and interfacial reactants between Al alloy matrix and Al2O3 particles were in-vestigated in terms of bendingstrength and harness test,. The fabrication of Al2O3/Al composite by the vestigated in terms of bending strength and hardness test. The fabrication of Al2O3/Al composite by the pressureless infiltration was done in nitrogen atmosphere with Mg in Al alloy. It was successfully fabricated at $700^{\circ}C$ according to Mg contents in Al alloy and infiltration condition. Because Mg in the Al alloy and ni-trogen atmosphere of infiltratio condition produced Mg-N compound(Mg3N2) it decreased the wetting an-gle between molten Al alloy and Al2O3 particles by coating on surface of Al2O3 particles. The fracture strength of Al2O3/Al-Mg composite was 800MPa and Al2O3/Al-Si-Mg composite was 400MPa. Si in Al alloy decreased the interfacial strength between Al alloy matrix and Al2O3 particles.

• Journal of the Korean Ceramic Society
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• v.35 no.5
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• pp.458-464
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• 1998

Variations of reaction sequence of $Pb(Zn_{0.6}Mg_{0.4})_{1/3}Nb_{2/3}O_3$[PZMN] with precusor mixing methods were ex-amined using X-ray diffraction and dielectric characteristics. In the present study three different types of precursor mixing methods (oxide mixing PbO+$ZnNb_2O_6+MgNb_2O_6$[Zn+MN] and PbO+(Zn,Mg)$Nb_2O_6$[ZMN] precursor mixing) were adopted. When the oxide mixing method was used for the PZMN synthesis a Zn-rich perovskite phase and pyrochlore phase were formed. Compared with PbO+ZN+MN precursor mixing method the PbO-ZMN precursor led to a lowering of the formation temperature for perovskite sin-gle phase. These variation of composition and formation temperature of the perovskite phase were dis-cussed in terms of the difference in the solid-reaction requence between these three different types of pre-cursor mixing.

• Journal of Veterinary Clinics
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• v.17 no.2
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• pp.480-484
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• 2000

A 10 years old female Poodle weighing 4.38 kg and a 10 years old female Maltese weighing 4.33kg were referred to veterinary leaching hospital of college of veterinary medicine, Konkuk uni-versity because of hematuria and severa anorexia. Preoperative hematological and srum chemical values revealed that counts of WBC were $78.4{\times}10^3$,/TEX>/ul in the Poodle and $21.6{\times}10^3$in the Maltese, concentrations of BUN 105 and 13 mg/dl, concentrations of creatinine 4.0 and 1.4 mg/dl, concentration of ALKP 542 U/L in the Poodle and concentration of ALF 37 U/L in the Maltese, respectively. Radiographic findings were observed radiopaque bilateral nephroliths in the Poodle and right renal cal- culus in the Maltese. Ultrasonographic findings were showed hyperechoic mass with severe acoustic shadowing, which were ]ocated in the center of both kidneys parenchyma in the Poodle and in right kidney in the Maltese. Bisectional nephrotomy in right kidney for removal of calculus, which had ,sin- gle stone and more large than splitted stones in lets kidney in the Poodle, was performed under isnf- lurane anesthesia in 100% $O_2$. The time from temporary occlusion of blood flow to suture of incisioned kidney after removal of renal calculi was elapsed 12 minutes. During operation and until 24hrs after operation was infusioned mannitol and tranexanic acid solution. There were normal urination with yellow color in the Poodle at 3 days after operation and in the Maltese at 1 day and good appetite after 7 days and 1 day after operation. At 7 days and 9 days after operation, hematolgoical and seam chemical values repealed that counts of WBC were $29.8{\times}10^3/u1 in the Poodle and 13.1 {\itmes}10^3$/ul in the Mal- tese, concentrations of BUN 13 and 10 mg/dl. concentrations of creatinine 1.3 and 1.1 mg/dl, con-centrations of ALT 34 and 97U/L, concentraion of AST 10 U/L in the Poodle, respectively, By ultra-sonographic view there was not observed hyperechoic mass and radippaque calculus in operated kid-ney in radiographic view.

• Journal of Korea Technology Innovation Society
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• v.14 no.4
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• pp.965-982
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• 2011

Currently, dependency of natural and energy resources on world economy may not be more serious than any before increasing the uncertainty of Korea's national economy, especially as China uses unexpectedly fast glowing portion of world resources. Due to insufficient natural resources and unmatured renewable energy system, it is very important for Korea to secure the energy sources not only for national prosperity but also security for the future. In this regard, importance and necessity of nuclear energy as a major electric power source in Korea are in need to be emphasized. Korea currently imports all the necessary enriched uranium for fabrication of nuclear fuel from abroad. Thus, it is extremely important to establish a secured supply system for enriched uranium regardless of the global political unstability as well as economic fluctuation. In order to build the nuclear fuel procurement system, it is required to analyze the global market status, current enrichment service systems, and the future technology under development. For this purpose, this study comparatively analyzes the laser based advanced technology for uranium enrichment under development in the United States, which is assumed to be 2~3 times more economically viable than currently available technologies.

• Journal of the Korean Society of Radiology
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• v.14 no.6
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• pp.763-772
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• 2020

During X-ray examinations in the DR system, the scattered X-rays physically generated by the patient cause image blurring in poor quality. Although X-rays to increase the contrast of images, this increases the patient's exposure dose and is likely to result in grid induced artifacts. Therefore, the purpose of this study is obtain images similar to those of real-grid with non-grid level conditions using a VGR (Virtual Grid Role) algorithm that serves as a virtual grid. Comparing MTF, SNR and CNR of non-grid and VGR algorithm images obtained with 70% exposure conditions of real-grid images showed that the MTF0.5 differed from 0.265 to 0.350 and the MTF0.1 from 0.412 to 0.467 and the SNR, CNR were also different. In addition, comparing MTF, SNR and CNR of VGR algorithm and real-grid images showed that the MTF0.5 differed from 0.350 to 0.367 and the MTF0.1 from 0.467 to 0.483 and the SNR, CNR by little.