• The Korean Journal of Physiology and Pharmacology
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• v.18 no.4
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• pp.313-320
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• 2014

The study was conducted to investigate the role of vitamin E in the high altitude hypoxia-induced damage to the intestinal barrier in rats. Sprague-Dawley rats were divided into control (Control), high altitude hypoxia (HH), and high altitude hypoxia + vitamin E (250 mg/kg $BW^*d$) (HV) groups. After the third day, the HH and HV groups were placed in a hypobaric chamber at a stimulated elevation of 7000 m for 5 days. The rats in the HV group were given vitamin E by gavage daily for 8 days. The other rats were given equal volume saline. The results showed that high altitude hypoxia caused the enlargement of heart, liver, lung and kidney, and intestinal villi damage. Supplementation with vitamin E significantly alleviated hypoxia-caused damage to the main organs including intestine, increased the serum superoxide dismutase (SOD) (p< 0.05), diamino oxidase (DAO) (p< 0.01) levels, and decreased the serum levels of interleukin-2 (IL-2) (p< 0.01), interleukin-4 (IL-4) (p<0.001), interferon-gamma ($IFN-{\gamma}$) (p<0.01) and malondialdehyde (MDA) (p<0.001), and decreased the serum erythropoietin (EPO) activity (p<0.05). Administration of vitamin E significantly increased the S-IgA (p<0.001) in ileum and significantly improved the expression levels of occludin and $I{\kappa}B{\alpha}$, and decreased the expression levels of hypoxia-inducible factor 1 alpha and 2 alpha ($HIF-1{\alpha}$ and $HIF-2{\alpha}$), Toll-like receptors (TLR4), P-$I{\kappa}B{\alpha}$ and nuclear factor-${\kappa}B$ p65(NF-${\kappa}B$ P65) in ileum compared to the HH group. This study suggested that vitamin E protectis from intestinal injury caused by high altitude hypoxia environment. These effects may be related to the HIF and TLR4/NF-${\kappa}B$ signaling pathway.

• Spatial Information Research
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• v.19 no.1
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• pp.21-28
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• 2011

With the recent overcrowding of metropolitan cities and people's increasing interest in housing environment, there are frequent disputes occurring over the right to daylight. In order to determine whether daylight has been encroached accurately. we need to consider the daylight change by the effect of the geographical features of the surrounding areas but most of the previous relevant studies overlooked this consideration. Thus, in order to determine the encroachment of daylight accurately, this study analyzed the change in the duration of daylight according to geographical features by applying the Hemispherical Viewshed Algorithm to Busan Metropolitan City. According to the results of the analysis, the minimum and average duration of daylight decreased with an increase of altitude by 50m. Second, according to the time bound designated by law, up to 78.6% of the area was influenced by the duration of daylight. Third, the geographical features of the surrounding areas had a significant effect on the duration of daylight. Accordingly, in order to analyze the right to daylight accurately, it is essential to consider the geographical features of the surrounding areas. Furthermore, the Hemispherical Viewshed Algorithm used in this study and the visible area of the sky obtained from the algorithm are considered helpful to analyze the influence of the geographical features of surrounding areas on the legal duration of daylight before analyzing the practical right to daylight.

• Korean Journal of Remote Sensing
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• v.34 no.6_2
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• pp.1273-1282
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• 2018

Recently, active research on the Arctic Ocean has been conducted due to the influence of global warming and new Arctic ship route. Although previous studies already calculated quantitative extent of sea ice using passive microwave radiometers, melting at the edge of sea ice and surface roughness were hardly considered due to low spatial resolution. Since Sentienl-1A/B data in Extended Wide (EW) mode are being distributed as free of charge and bulk data for Arctic sea can be generated during a short period, the entire Arctic sea ice data can be covered in high spatial resolution by mosaicking bulk data. However, Sentinel-1A/B data in EW mode, especially in HV polarization, needs significant radiometric correction for further classification. Thus, in this study, we developed algorithms that can correct thermal noise and scalloping effects, and confirmed that Arctic sea ice and open-water were well classified using the corrected dual-polarization SAR data.

• Journal of Korea Foundry Society
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• v.41 no.2
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• pp.127-131
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• 2021

Based on its good compatibility with high-temperature environments, the Ti-48Al-2Cr-2Nb alloy is used for high-temperature materials of industrial equipment. In this study, a Ti-48Al-2Cr-2Nb alloy turbocharger turbine wheel was fabricated by a vacuum centrifugal casting method. The conditions that prevent misrun defects of the turbocharger turbine wheel blade from centrifugal casting using alumina molds were investigated. The microstructure of the alloy prepared by vacuum centrifugal casting was studied by means of optical microscopy (OM), with a micro-Vickers hardness analyzer (HV), by X-ray diffraction (XRD) and by SEM-EDS. The HV and SEM-EDS examinations of the as-cast Ti-48Al-2Cr-2Nb alloy showed that the thickness of the oxide layer (α-case) was typically less than 50 ㎛. At a high preheating temperature of 1,100℃, a moderate RPM of 260, and with an alumina mold with a large gate size, there were almost no misrun defects. Therefore, it was confirmed that a Ti-48Al-2Cr-2Nb alloy turbocharger turbine wheel with fewer misrun defects could be achieved through a high preheating temperature, a moderate RPM, a large gate size and an alumina mold to suppress the formation of alpha-case components.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.2
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• pp.15-23
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• 2021

This study was conducted to evaluate the field application of the developed recommendation system in organic rice (Oriza sativa L.) paddy and to investigate the mineral nitrogen content in soil and rice productivity. According to the developed system, hairy vetch (HV), rye+rapeseed oil cake (R+OC), rapeseed oil cake (OC) for only basal fertilization (OC-B), OC for split application (OC-S), pig manure compost (PMC), and chemical fertilizer (CHM) were applied to paddy soil at the rate of 107~133 kg N/ha. Results were followed, unhulled rice yield of OC-S (111%), OC-B (110), R+OC (106), HV (101), and PMC (96) were no significantly different with CHM (100). Also there was positive correlation (R²=0.803^*) between unhulled rice yield and cumulative inorganic N in soil. For nitrogen use efficiency of rice, OC-B, OC-S, and R+OC were not significantly different with CHM. In conclusions, the developed organic materials use recommendation system was effective for organic rice productivity. It could be useful for organic farmer to apply the organic materials use recommendation system for rice.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.4
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• pp.198-205
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• 2023

We investigated the effects of Al and Mg on the microstructure and hardness of the coating layer of galvanized steel sheets, by thermodynamic calculations, X-ray diffraction, scanning electron microscopy, and Vickers hardness tests of Zn-0.2Al, Zn-6Al-2Mg, and Zn-10Al-5Mg coating layers. Regardless of the alloy composition of the galvanizing bath, a Fe-Al layer was observed between the coating layer and steel sheet. The Zn-0.2Al coating layer consists of major h.c.p. Zn phase and minor f.c.c. Al phase. The fraction of f.c.c. Al phase (containing a significant amount of Zn) of the coating layer increases with increasing the chemical composition of Al of the galvanizing bath. The h.c.p. MgZn₂ phase was formed in the Al/Mg-containing Zn-6Al-2Mg and Zn-10Al-5Mg coating layers, forming Zn-Al-MgZn₂ eutectic microstructure. The primary MgZn₂ phase was additionally formed in the Zn-10Al-5Mg coating layers containing high concentrations of Al and Mg. The Vickers hardness values of Zn-0.2Al, Zn-6Al-2Mg, and Zn-10Al-5Mg coating layers were 59.1 ± 1.2 HV, 161.2 ± 5.7 HV, and 215.5 ± 40.3 HV, respectively. The addition of Al and Mg increased the hardness of the coating layer by increasing the fraction of the Al phase (containing Zn) and MgZn₂ intermetallic compound, which were harder than the Zn phase.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.153-156
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• 1990

High voltage impulse measuring system gives an output signal that is a deformed responce of the input signal. This paper describes a method of reconstructing the input signal from the deformed output. The method is applicable to any wave shape, full or chopped impulse voltages.

• 전기의세계
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• v.42 no.4
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• pp.29-35
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• 1993

1. 현장 시험을 위하여 여러가지 방법이 제안되어 적용되고 있지만 그 어느것도 뚜렷한 결과를 제시하지 못 하고 있다. 2. DC test는 이미 언급된 문제로 인하여 시험목록에서 제외되어야 한다. 3. 교류 시험은 현재 많이 적용되고 있지만, 경우에 따라서는 적용이 불가능하다. 그러나 전력원에 직접 케이블 선로를 연결하는 것이 가능한 경우에는 1.732U$_{0}$ 전압에서의 시험은 타당하다고 할 수 있다(시험 시간이 명기되어야 함). 4. 진동파 시험은 충분히 민감하지 않지만, U$_{0}$하에서 PD측정을 병행하면 타당한 방법이 될 수 있다. 5. HV 케이블에 있어서 다른 방법(VLF와 SI)의 적용은 더 구체적으로 연구되어야 한다.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.106-107
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• 2002

Extreme ultraviolet (EUV) radiation of wavelength $\lambda$~10 nm or photon energy hv~100 eV is presently a blank region in the electromagnetic spectrum where applications are concerned. This is because no powerful sources were available until when intense-laser-produced plasmas are available. Both a new laboratory-sized source of EUV radiation and its new applications in lithography of semiconductor devices have been developed. (omitted)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.357-360
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• 1995

Since the streaming electrification phenomena of transformer were made clear on 1970s, many researches have been continued on the improvement of the transformer. This paper describes the effect of additive (BTA, DBPC) and temperature on the streaming electrification of the various materials. The streaming current in the various materials decreases in proportion to the concentration of BTA, results in the inverse electrification. We believe that these results will contribute to the optimal design of HV large-capacity transformer.