• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.33.3-34
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• 2008

As an activity of building Korean Space Weather Prediction Center (KSWPC), we has studied of radiation effect on the spacecraft components. High energy charged particles trapped by geomagnetic field in the region named Van Allen Belt can move to low altitude along magnetic field and threaten even low altitude spacecraft. Space Radiation can cause equipment failures and on occasions can even destroy operations of satellites in orbit. Sun sensors aboard Science and Technology Satellite (STSAT-1) was designed to detect sun light with silicon solar cells which performance was degraded during satellite operation. In this study, we try to identify which particle contribute to the solar cell degradation with ground based radiation facilities. We measured the short circuit current after bombarding electrons and protons on the solar cells same as STSAT-1 sun sensors. Also we estimated particle flux on the STSAT-1 orbit with analyzing NOAA POES particle data. Our result clearly shows STSAT-1 solar cell degradation was caused by energetic protons which energy is about 700 keV to 1.5 MeV. Our result can be applied to estimate solar cell conditions of other satellites.

• Smart Media Journal
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• v.9 no.3
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• pp.25-30
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• 2020

The purpose of this paper is to implement a deep learning-based real-time video analysis algorithm that monitors safety of workers in industrial facilities. The worker's clothes were divided into six classes according to whether workers are wearing a helmet, safety vest, and safety belt, and a total of 5,307 images were used as learning data. The experiment was performed by comparing the mAP when weight was applied according to the number of learning iterations for 645 images, using YOLO v4. It was confirmed that the mAP was the highest with 60.13% when the number of learning iterations was 6,000, and the AP with the most test sets was the highest. In the future, we plan to improve accuracy and speed by optimizing datasets and object detection model.

• Economic and Environmental Geology
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• v.44 no.5
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• pp.373-386
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• 2011

Geochemical study was performed on black slates and interbedded U-bearing coaly slates in Deokpyeongri area, the representative uranium mineralized district of the Ogcheon Metamorphic Belt, to discuss the genetic environments of the uranium deposit. REE concentration (254 ppm) of the black slates is higher than that (169 ppm) of the coaly slates and NASC-normalized REE patterns of the coaly slates show remarkable positive Eu anomaly. l11e redox-sensitive trace elements such as V, Cr, Co, Ni, Mo and U in the coaly slates are highly enriched compared to the black slates, especially for V of 24 times, Mo of 62 times, and U of 60 times. In additions, Pd and Pt are also enriched in the coaly slates. Positive Eu anomaly and the noticeable enrichment of the elements listed above compared to those of NASC indicate that those elements were not derived from common seawater but deposited under high temperature and reducing environment of submarine hydrothermal activities. Wide compositional ranges of major elements ($SiO_2/Al_2O_3$: 3.98~11.88, $Al_2O_3/Na_2O$: 25.6~139.06, $K_2O/Na_2O$: 6.80~46.85) also suggest that the source rocks of the sediments are mixtures of sedimentary rocks and igneous rocks. Higher sulfur contents in the coaly slates, 2.6 wt.%, than those in the black slates, 0.6 wt.% also indicates that the former was influenced by hydrothermal activities containing much sulfur. These geochemical characteristics are similar to the genetic environments of South China type PGE deposits (Mo-Ni-Zn-PGE) which is geotectonically correlated with the Ogcheon Metamorphic Belt and is known as sedimentary-exhalative deposits. In conclusions, the uranium and other metallic elements mineralization seems to have occurred in the sedimentary basin that was affected by submarine hydrothermal activities and rich in organic materials under oxygen-poor environments as well.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.435-444
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• 2008

High energy charged particles are trapped by geomagnetic field in the region named Van Allen Belt. These particles can move to low altitude along magnetic field and threaten even low altitude spacecraft. Space Radiation can cause equipment failures and on occasions can even destroy operations of satellites in orbit. Sun sensors aboard Science and Technology Satellite (STSAT-l) was designed to detect sun light with silicon solar cells which performance was degraded during satellite operation. In this study, we try to identify which particle contribute to the solar cell degradation with ground based radiation facilities. We measured the short circuit current after bombarding electrons and protons on the solar cells same as STSAT-1 sun sensors. Also we estimated particle flux on the STSAT-l orbit with analyzing NOAA POES particle data. Our result clearly shows STSAT-l solar cell degradation was caused by energetic protons which energy is about 700keV to 1.5MeV. Our result can be applied to estimate solar cell conditions of other satellites.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.1
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• pp.21-28
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• 2000

Although commercial PIV systems have been widely used for the non-intrusive velocity field measurement of fluid flows, they are still under development and have considerable room for improvement. In this study, a single-frame double-exposure PIV system using a high-resolution CCD camera was developed. A pulsed Nd:Yag laser and high-resolution CCD camera were synchronized by a home-made control circuit. In order to resolve the directional ambiguity problem encountered in the single-frame PIV technique, the second particle image was genuinely shifted in the CCD sensor array during the time interval dt. The velocity vector field was determined by calculating the displacement vector at each interrogation window using cross-correlation with 50% overlapping. In order to check the effect of spatial resolution of CCD camera on the accuracy of PIV velocity field measurement, the developed PIV system with three different resolution modes of the CCD camera (512 ${\times}$ 512, lK ${\times}$ IK, 2K ${\times}$ 2K) was applied to a turbulent flow which simulate the Zn plating process of a steel strip. The experimental model consists of a snout and a moving belt. Aluminum flakes about $1{\mu}m$ diameter were used as scattering particles for the liquid flow in the zinc pot and the gas flow above the zinc surface was seeded with atomized olive oil with an average diameter of 1-$3{\mu}m$. Velocity field measurements were carried out at the strip speed $V_s$=1.0 m/s. The 2K ${\times}$ 2K high-resolution PIV technique was significantly superior compared to the smaller pixel resolution PIV system. For the cases of 512 ${\times}$ 512 and 1K ${\times}$ 1K pixel resolution PIV system, it was difficult to get accurate flow structure of viscous flow near the wall and small vortex structure in the region of large velocity gradient.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.54-54
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• 2009

Ag thick film has been used for electrode materials with the excellent conductivity. Ag electrode is used in screen-printed silicon solar cells as a electrode material. Compared to photolithography and buried-contact technology, screen-printing technology has the merit of fabricating low-priced cells and enormous cells in a few hours. Ag paste consists of Ag powders, vehicles and additives such as frits, metal powders (Pb, Bi, Zn). Frits accelerate the sintering of Ag powders and induce the connection between Ag electrode and Si wafer. Thermophysical properties of frits and reactions among Ag, frits and Si influence on cell performance. In this study, Ag pastes were fabricated with adding different kinds of frits. After Ag pastes were printed on silicon wafer by screen-printing technology, the cells were fired using a belt furnace. The cell parameters were measured by light I-V to determine the short-circuit current, open-circuit voltage, FF and cell efficiency. In order to study the relationship between the reactivity of Ag, frit, Si and the electrical properties of cells, the reaction of frits and Si wafer on was studied with thermal properties of frits. The interface structure between Ag electrode and Si wafer were also measured for understanding the reactivity of Ag, frit and Si wafer. The excessive reactivity of Ag, frit and Si wafer certainly degraded the electrical properties of cells. These preliminary studies suggest that reactions among Ag, frits and Si wafer should optimally be controlled for cell performances.

• Journal of the Korean Society of Costume
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• v.63 no.3
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• pp.1-16
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• 2013

Xiognu people were the first of the Central-Asian nomads to establish a nation in 209 B.C. They always moved around looking for places to breed their animals and fertile grounds, so they wore clothes made of fur and leather and covered their tents with felt from the livestock. This research studies on the literatures, costumes and the achievement of archaeological excavation. Furthermore, to investigate on costumes excavated of Xiongnu, we visited the Mongolian National Museum and the Hermitage Museum. A corn-hat made of felt, a felt hat with ear flaps and a golden crown with a bird on the top were unearthed from a tomb of Xiongnu in Inner mongolia. Women usually wore pigtails, and men wore pigtails or ponytails but they cut their hair short when holding a funeral. Many pigtails discovered in Noyon uul tombs can be considered as their funeral customs. The Xiongnu wore a round or v-neck caftan attached straight sleeves reaching knees in the left folded style, and because they always rode horses, having the length of the caftan not go past their buttocks would have made it more convenient for them. During the period of Western Han, Ho refered to Xiongnu and it became a common name for northern races. They used leather belts and an animal-designed buckle was found. Women commonly rouged their cheeks for a vivid and cute look, and many ornaments were excavated including bracelets, rings and decorations made of gold, silver, copper and jade, among which there were hair ornaments used to identify one's class. A horse pattern with wings and a horn of Golmod T20 was substitution for the Schythian use of deer. Patterns or shape of unearthed articles present in the Xiongnu culture in Noyon uul had a close relationship with Altaic, Greek and Persian cultures. The Xiongnu clothing was made of animals' skin and fur, woolen textiles and felt. It was folded to the left for upper garments, and the pants were adjusted using a belt and shoes were made of leather, which was very suitable for protection against the cold and horse riding. Mobility played a significant role in their clothing.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.1
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• pp.19-32
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• 2014

The Taekwondo uniform has remained consistent since it was officially designed in a V-neck form in 1976. Taekwondo is a martial art that emphasizes social etiquette; therefore, it is necessary to dress in a uniform that reflects Korean traditions and ancient oriental philosophy. However, the current official uniform has limitations in endowing traditionality and many usability problems. Thus, recognizing the problems raised with the uniform, the Kukkiwon (World Taekwondo Headquarters) developed a new style official uniform in 2011. This study is to endow traditional meaning to a new style uniform and proposes some design modifications that can convey a more traditional adequacy. The development of the new official uniform began with a specific plan for change from the existing uniform, this study as subsequent work is significant in that its endowment of symbolism and modification proposal is for the actual execution and global dissemination of traditional Taekwondo culture. The results of this study are as follows. First, we can endow Korea's traditional historicity and symbolism to the new uniform in form and colors. All contents of the design (in which the front side is open, the top is adjusted rightward, the rear length is shorter than the front length, comfort provided by side vents, dual collars for children's uniforms, and a belt) are adapted from the Korean traditional costume. Consequently, historicity can be endowed to the uniform. It is also confirmed that the traditional oriental philosophy including heaven and earth (天地), Yin-Yang (陰陽), and Five Elements (五行) can be endowed in the use of colors. Second, in order to project deeper historicity and symbolism to the form of the new uniform, this study proposes design modifications based on the selection as an item of Simui (深衣), a type of traditional clothing that contains a high symbolism similar to the Taekwondo uniform. It proposes giving shape to the practice of manners, the righteous life, and the straightforward mind by modifying the design of the uniform in the fish belly part of the sleeves, collars, back stitches, and side seams.

• Economic and Environmental Geology
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• v.17 no.4
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• pp.289-298
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• 1984

Uraniferous black slates of the Okchon sequence occur in Koesan (northeast) through Miwon-Boun (middle) to the southwest off Taejon (southwest) within the Okchon fold belt. The Uraniferous balck slates in the southwest off Taejon are particularly well developed in Chubu (northeast) and Moksso-ri (middle) areas whereas they are less developed in Jinsan (southwest) area. The uraniferous beds range from less than a meter to 40 meters in thickness and range from less than 0.02% $U_3O_8$ (cut-off-grade) to 0.05% $U_3O_8$ in the southwestern district off Taejon. Electron microprobe analysis of uranium-minerals found in graphitic slate samples enables to estimate their major compositions semi-quantitatively so that uraninite, ferro-uranophane and chlopinite are tentatively identified. Uranium-minerals are closely associated with carbon and metal sulfides. Correlation analysis of trace element concentrations revealed that U and F.C., and U and Mo are lineary correlative respectively and their correlation coefficients are positively high whereas those of U and V, U and Mn, and U and Zr are negatively low, implying that uranium mineralization has been closely related with concentrations of carbon and molybdenum. Stable isotope analyses of pyrite sulfur range widely from +11.5% to -23.3% in ${\delta}^{34}S$ values whereas those of graphite carbon fall within a narrow range between -23.3% and -28.9% in ${\delta}^{13}C$ values. The wide range of ${\delta}^{34}S$ values suggests that the sulfur could be of meteoric origin rather than of igneous source. The narrow range of ${\delta}^{13}C$ values, which are close to those of coal, indicates that the graphite is organic carbon in origin. Therefore, it is concluded that the uranium mineralization in the Okchon sequence took place primarily in sedimentary environment rich in organic matter and sulfide ion, both of which served as the reducing agents to convert soluble uranyl complex to insoluble uranium dioxide.

• Journal of the Korean Society of Costume
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• v.22
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• pp.97-118
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• 1994

This stud is my second trial to examine the costume of Balhae Dyansty. The subject of this study is the costume of a bronze statue excavated in the Maritime Provinces of Russia. The bronze statue is in the custody of Vladivostok Museum E.V. Shavkunov a Russian archelogist reported it a statue of-ficial of balhae dynasty in the 7-8th century. Judged his report lack of basis I suggest new opinion on sex, age, married or unmarried. social position manufactured time of the statue by comparative study on the costume hair-style and appearance of the statue with around nations' antiquities. hair-style of the statue is basically included in Ssangge and complexed style of Sage Ssangsuhuange, and Guange, Generally, Ssangge is a hair style of children, unmarried women, court ladies, dancing girls, and instrument player (lady)s'. The statue wears round-necked blouse long skirt broad fabric belt at high waist broad sleeve and confront collar coat cloud shaped shawl and risen tip shoes. The figure of statue is de-scribed plump. The statue shows straight sil-houette and high waist typical style of Tang, Uddai, The most characteristic facto is cloud shaped shawl Cloud shaped shawl was originally one of the northern race's shoulder ornaments. From the view of Comparative study the antiquities of NamDang and JunChock are simi-lar to this statue. Besides Tsukanovka river where the statue was excavated is Kraskino ruins of a castle formed single cultural layer of Balhae Dynasty and are relics of the layer of Balhae Dynasty and are relics of the latter period of Balhae Dynasty. Therefore this statue is assumed to have been manufactured at the last years of Balhae Dynasty and to be a figure of unmarried woman not official.