• Journal of Astronomy and Space Sciences
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• 제35권2호
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• pp.83-92
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• 2018

The summer polar lower thermosphere (90-100 km) has an interesting connection to meteors, adjacent to the mesopause region attaining the lowest temperature in summer. Meteors supply condensation nuclei for charged ice particles causing polar mesospheric summer echoes (PMSE). We report the observation of meteor trail with nearly horizontal transit at high speed (20-50 km/s), and at last with re-enhanced echo power followed by diffusive echoes. Changes in phase difference between radar receivers aligned in meridional and zonal directions are used to determine variations in horizontal displacements and speeds with respect to time by taking advantage of radar interferometric analysis. The actual transit of echo target is observed along the straight pathway vertically and horizontally extended as much as a distance of at least 24 km and at most 29 km. The meteor trail initially has a signature similar to 'head echoes', with travel speeds from 20 - 50 km/s. It subsequently transforms into a different type of echo target including specular echo and then finally the power reenhanced. The reenhancement of echo power is followed by fume-like diffusive echoes, indicating sudden release of plasma as like explosive process probably involved. We discuss a possible role of meteor-triggered secondary plasma trail, such as fireball embedded with electrical discharge that continuously varies the power and transit speed.

• Journal of Chest Surgery
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• 제11권1호
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• pp.102-107
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• 1978

This is a report of a chylous cyst in the mediastinum found in a 61 year old Korean female patient who suffered from mild swallowing difficulty and right chest discomfort. These symptoms had developed 5 years previously when chest P-A view showed thumb-tip sized mass shadow in right mediastinum, just right to ascending aorta. Esophagogram revealed an indentation of midesophagus. Follow up checks showed growing mass shadow which suggested aneurysm of ascending aorta. On admission chest X-ray revealed a well circumscribed infant head sized mass density along the right heart border and middle mediastinal border, and extended near to the middle clavicular line in right chest cavity. Aortogram revealed no relationship between the mass and aorta. Right thoracotomy was performed under impression of mediastinal tumor. There was a large cyst containing 700 cc of milky fluid. There was no connection to the thoracic duct nor adjacent organs. The fluid was analyzed chemically and identified the fluid as chyle. The origin of the isolated chylous cyst was uncertain postoperative course was uneventful.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.352-364
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• 2007

It is essential to reduce track maintenance costs and to extend the periodic replacements of continuous welded rails based on accumulated passing tonnage. As recently train load decrease and rail joints wear down less, the periodic replacements of continuous welded rails can be extended. There are many kinds of rail damage like squat, head-check and corrugation. These can be taken nondestructive or naked eye test. So the periodic replacements of continuous welded rails based on accumulated passing tonnage were examine with focusing on a crack of rail bottom of continuous welded rail. Therefore, this study measure dynamic response of track by metro train load, it compute impact coefficient and track spring coefficient for estimating a condition of actual track system. Also, it is converted the measured stress waveform into stress frequency histogram by the rain-flow counting methods, and then the equivalence of stress is calculated. As apply s-n curve of a new welded rail, accumulated fatigue damage ratio of laid rail and remaining service lives is estimated. This study suggest a plan of the periodic replacements of continuous welded rails based on accumulated passing tonnage classified by the types of track system.

• 대한화장품학회지
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• 제27권1호
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• pp.3-15
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• 2001

The bilayer forming ability of pseudo-ceramide PC104 in octanoic acid/water/n-octyl $\beta$-D-glucoside mixtures was investigated through the phase diagram. Because of its low solubility in water and of its crystallization, pseudoceramide PC104 was dissolved in octanoic acid, which is nontoxic additive for foods and cosmetics. The mixtures formed four different phases (L1, L2, LC and two phases). Depending on the concentration of PC104 in octanoic acid, the region of each phase was extended or contracted. On the contrary to the region of L2, regions of lamellar phase and L1 phase were expanded. The bilayer-forming ability of PC104 was explained on the basis of concentration of PC104 at interface and interaction between PC104 and octanoic acid. From FT-IR results, it was found that the interactions of PC104’s polar head group with octanoic acid increased as the amount of PC104 in octanoic acid increased. Also emulsion size and size distribution have been studied depending upon the emulsification path. droplets of emulsion prepared from lamellar phase were smaller and more homogeneous compared to those of emulsions formed from L2 phase.

• 한국기술혁신학회:학술대회논문집
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• 한국기술혁신학회 2000년도 추계 학술대회(The 2000 Autumn Conference of korea Technology Inovation Society)(한국기술혁신학회)
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• pp.227-245
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• 2000

Korean firms have attempted to catch up in the aircraft industry during last quarter century. Korean firms have built up their capabilities by moving from parts manufacturing through subassembly to system integration. The number of projects carried out and the intensity of technological effort undertaken by firms strongly influences market position and firm performance. However, successful catching up is not simply dependent on capability building within the firm. The national environment (Porter, 1990) in which firms are located plays a pivotal role. The Korean government has been effective in creating a favorable environ-ment in many areas, but has not been able to replicate this success in the aircraft industry. Opportunities for learning in the aircraft industry have been hampered by the small size of the Korean civilian aircraft market and the sophisticated requirements of military systems. A policy of domestic rivalry in airframe manufacture has created too many firms for such a small market. The ability of Korean firms to catch up in the aircraft industry depends on both the internal capabilities of firms as well as appropriate government policies and the involve- ment of government research institutions and universities over an extended period of time. There have been many studies about the catching up of developing countries in mass production (such as automobile, consumer electronics, and recently DRAM), but few in complex systems, such as aircraft.

• 한국생산제조학회지
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• 제18권4호
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• pp.348-354
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• 2009

In order to reduce the risk of roll over crash, one of the greatest risk events, National Highway Traffic Safety Administration(NHTSA) issued Notice of Proposed Rulemaking(NPRM) enhancing the safety standard on roof crush resistance, FMVSS No. 216 and changing some part of the test procedure. According to this NPRM, the boundary Gross Vehicle Weight Rating(GVWR) of the vehicles applied by this standard is extended from 2,722kg(6000 lb) to 4,536 kg(10000 lb) and the applied test force is increased from 1.5 times to 2.5 times of Unloaded Vehicle Weight (UVW). Also the current limit on the amount of roof crush, 127mm(5 inch), is replaced with a new requirement of maintaining enough headroom without touching the head of a seated 50% male dummy. In this paper, we carried out the rollover crash test on some domestic cars and investigated their safety due to the KMVSS No. 92 and the enhanced safety standard, FMVSS No. 216, respectively. The result shows that most of them can satisfy the new standards but further tests will be necessary, especially for heavier cars.

• Food Science and Biotechnology
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• 제18권5호
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• pp.1071-1075
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• 2009

Allyl isothiocyanate (AI), a volatile compound of mustard, has excellent antimicrobial effects, but its volatility hinders its wide usage as an ingredient of food products. Microencapsulation technique, therefore, was applied for delaying the release time of AI. For delaying the release time of AI, the mustard powder, which contained AI, was microencapsulated with 5% modified starch by using fluidized bed processing. The efficiency of the controlled release of AI at various pH was analyzed by the head space (HS) analysis and solid phase microextraction (SPME) method using gas chromatography (GC). Also, modified starch encapsulated powder was added into kimchi for applying in food industry. As the result, the release time of AI was delayed by microencapsulation with modified starch and the higher pH could be the faster release of AI. Also, the period until the pH values and total acidity of kimchi reached up to 4.5 and 0.6%, which give its malsour taste, was extended by microencapsulation. These results showed that modified starch encapsulated powder could prolong the preservation in food system.

• Parasites, Hosts and Diseases
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• 제58권1호
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• pp.81-86
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• 2020

Trematode specimens were collected from the intestine of a herring gull, Larus argentatus, which was found in a critical condition on the shore of a small island (Yubu-do, Seocheon-gun, Chungcheongnam-do) located at the western coast of the Korean peninsula. Total 11 specimens of intestinal flukes, including 3 Cryptocotyle lingua (Heterophyidae), 1 Himasthla alincia (Echinostomatidae), 5 Cardiocephaloides medioconiger (Strigeidae), and 2 Diplostomum spathaceum (Diplostomidae), were recovered. C. lingua was morphologically characterized by the presence of a large ventrogenital apparatus and 2 obliquely tandem testes. H. alincia had an elongated body and a head collar equipped with 31 collar spines. C. medioconiger had a bisegmented body and a voluminous copulatory bursa containing the seminal vesicle and ejaculatory duct. D. spathaceum also had a bisegmented body and its vitellaria extended up to the anterior border of the tribocytic organ. It is of note that C. lingua is potentially zoonotic that can occur in birds and humans. Three of them, i.e., C. lingua, C. medioconiger, and D. spathaceum, are new trematode fauna in Korea. Studies on trematode fauna of migratory birds should be continued in Korea.

• 디지털콘텐츠학회 논문지
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• 제7권1호
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• pp.1-8
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• 2006

테크놀러지의 발전에 따른 대중매체의 발달은 다양한 콘텐츠의 개발을 활발하게 하고 있다. 그 중 음악콘텐츠는 이제 문화콘텐츠 전반으로 그 역할이 확대되어 그 시장 또한 빠른 속도로 성장하고 있다. 음악시장이 음반중심에서 디지털 음원시장으로 변화하면서 디지털 사운드콘텐츠의 창작, 유통, 마케팅의 방법이 달라지고 있으며 이렇듯 음악 산업 환경이 역동적으로 변화하며 음악산업 패러다임 변화를 요구하기에 이르렀다. 본 연구에서는 이러한 시대적 변화에 따른 국가적 정책과 지완 법률의 개정, 국민적 인식 둥 음악 산업을 발전시키기 위해 진행되고 있는 사항들을 고찰하고 앞으로의 나아갈 방향을 제시하고자 하는데 의의가 있다.

• 정보저장시스템학회논문집
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• 제6권2호
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• pp.79-82
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• 2010

In optical imaging systems, such as microscopes, high resolution exposure systems, and optical storage devices, higher optical resolution is a requirement. One of the promising technologies that is able to satisfy this requirement with relatively simple construction and reliable performance are, solid immersion lens (SIL)-based near-field (NF) optical systems. High NA optical systems using annular apertures have been investigated as one solution to achieve higher resolutions and an extended focal depth. By applying an optimized annular aperture to convention SIL optical head resolution can be increased by approximately 20%. This novel SIL-based near-field optics will be verified through experiments such as measuring focused beam spot profiles and observing the topology of a measurement sample. The studied SIL-based near-field optics can be applicable to not only next generation optical storage device but also high resolution microscopy and pattering technologies.