• Wind and Structures
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• 제24권5호
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• pp.447-464
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• 2017

The flutter instability is one of the most important themes need to be carefully investigated in the design of long-span bridges. This study takes the central-slotted ideal thin flat plate as an object, and examines the characteristics of unsteady surface pressures of stationary and vibrating cross sections based on computational fluid dynamics (CFD) simulations. The flutter derivatives are extracted from the surface pressure distribution and the critical flutter wind speed of a long span suspension bridge is then calculated. The influences of angle of attack and the slot ratio on the flutter performance of central-slotted plate are investigated. The results show that the critical flutter wind speed reduces with increase in angle of attack. At lower angles of attack where the plate shows the characteristics of a streamlined cross-section, the existence of central slot can improve the critical flutter wind speed. On the other hand, at larger angles of attack, where the plate becomes a bluff body, the existence of central slot further reduces the flutter performance.

• Clinical and Experimental Pediatrics
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• 제58권8호
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• pp.313-316
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• 2015

Interstitial deletions involving the chromosome band 15q22q24 are very rare and only nine cases have been previously reported. Here, we report on a 12-day-old patient with a de novo 15q22q23 interstitial deletion. He was born by elective cesarean section with a birth weight of 3,120 g at 41.3-week gestation. He presented with hypotonia, sensory and neural hearing loss, dysmorphism with frontal bossing, flat nasal bridge, microretrognathia with normal palate and uvula, thin upper lip in an inverted V-shape, a midline sacral dimple, severe calcanovalgus at admission, and severe global developmental delay at 18 months of age. Fluorescence in situ hybridization findings confirmed that the deleted regions contained at least 15q22. The chromosome analysis revealed a karyotype of 46,XY,del(15) (q22q23). Parental chromosome analysis was performed and results were normal. After reviewing the limited literature on interstitial 15q deletions, we believe that the presented case is the first description of mapping of an interstitial deletion involving the chromosome 15q22q23 segment in Korea. This report adds to the knowledge of the clinical phenotype associated with the 15q22q23 deletion.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권1호
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• pp.24-29
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• 2000

We propose a simple method to control the crystallization depth of amorphous silicon (a-Si) deposited by PECVD or LPCVD during the excimer laser annealing (ELA). Employing the new method, we have formed poly-Si/a-Si double film and fabricated a new poly-Si TFT with vertical a-Si offsets between the poly-Si channel and the source/drain of TFT without any additional photo-lithography process. The maximum leakage current of the new poly-Si TFT decreased about 80% due to the highly resistive vertical a-Si offsets which reduce the peak electric field in drain depletion region and suppress electron-hole pair generation. In ON state, current flows spreading down through broad a-Si cross-section in the vertical a-Si offsets and the current density in the drain depletion region where large electric field is applied is reduced. The stability of poly-Si TFT has been improved noticeably by suppressing trap state generation in drain region which is caused by high current density and large electric field. For example, ON current of the new TFT decreased only 7% at a stress condition where ON current of conventional TFT decreased 89%.

• 한국농촌건축학회논문집
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• 제16권2호
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• pp.1-8
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• 2014

In the past, Korea was classified as a region not affected by earthquakes. However, recent increase of earthquakes has forced to strengthen standards of earthquake resistant designs of structures to minimize seismic damage. In addition, it was thought that masonry infill walls in buildings are only acting as partitions, so these walls are not considered in analyzing building structures. But it was found that when seismic loads are applied to a structure with masonry infill walls, the walls affect the structure. Accordingly, this study conducted nonlinear static analyses for a structure constructed before applying earthquake resistant designs in two cases: when considering masonry walls and when not. The result showed that the seismic performance of the structure is insufficient. Thus, the structural resistance of the structure was also studied in two cases: when reinforcing with steel plate braces and when using carbon fiber braces. In the two cases reinforcing two different stiffeners, it was appeared that the behaviors of the structure were similar, though the cross-section area of a carbon fiber brace used to reinforcing the structure is only 12.6% of a steel plate brace, and its weight is only 2.8%. Thus, the reinforcing effect of the thin, light-weighted carbon fiber brace is much larger than that of the steel plate brace, when considering usability and constructability of both materials.

• 한국지구과학회지
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• 제24권5호
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• pp.402-410
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• 2003

이매패류 화석의 미구조를 박편상에서 관찰하면 시대가 오래된 것일수록 방해석의 재결정작용으로 인하여 성장선이 대부분 지워지는 반면 시대가 젊거나 현생의 이매패류는 매우 세밀한 성장선 및 구조가 그대로 보존된다. 패각이속성작용을 겪으면서 각피성분이 없어지고 외부에 노출되어 패각의 구성 물질인 Ca$^{2+}$이 주위 퇴적물에 존재하던 Fe$^{2+}$, Mg$^{2+}$, Mn$^{2+}$ 등과 치환되면서 색깔이 검게 된다. 이 과정에서 화석에서는 Ca함량이 낮아지는 대신 다른 금속의 함량이 높아진다. 자외선 및 가시광선 분광 분석 결과 반사도는 백악기 화석에서 현저히 낮고 제3기 화석 및 현생에서 비교적 높게 나타나며, 이는 주요 금속이온의 치환에 영향을 받는다는 사실을 알 수 있다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.61-65
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• 2005

Existing test methods for thick-section specimens ( 4mm) have not provided precise compressive properties to date for the analysis and design of thick structure. A survey of the failure behaviour of such thick specimens revealed that the failure initiated at the top corner of the specimen and propagated down and across the width of the specimen as premature failure, not typically reported for thin compression specimens. In the current study, the premature failure was successfully avoided during compressive testing and the failure mode was quite similar regardless of increasing specimen thickness and specimen volume. Failure mode was similar regardless of increasing specimen thickness and specimen volume, i.e. brooming failure mode combined with longitudinal splitting, interlaminar cracking, fibre breakage and kinkband formation (fibre microbuckling). Nevertheless, average failure strengths of the specimens decreased with increasing specimen thicnkiness from 2mm to 8mm with the T800/924C system (36% strength reduction) and specimen volumes from scaling factor I to scaling factor 4 with the IM7/8552 system (46% strength reduction). It was revealed from the literature$^{11}$ that the thickness effect and scaling effect arc caused by manufacturing defects such as void content and fibre waviness.

• Natural Product Sciences
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• 제9권4호
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• pp.264-269
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• 2003

The rhizome of Acorus calamus Linn. is commonly known as "Vacha" in indigenous systems of medicine. It is distributed in marshy tracts of Kashmir, Sirmaur (Himachal Pradesh), Manipur and the Naga hills. It is regularly cultivated in Koratagere Taluk in Karnataka and other parts of India. This study deals with the detailed pharmacognostical evaluation of the dried rhizomes of Acorus calamus collected from DehraDun (Uttaranchal), Lucknow (Uttar Pradesh). The commercial sample procured from Delhi market was also evaluated to observe the difference between collected and market samples. Dried rhizome is vertically compressed, pale yellow to dark brown and occasionally orangish brown in colour. Transverse section showed two distinct region with scattered, concentric vascular bundles surrounded by fibrous bundle sheath. Some vascular bundles just beneath the endodermis devoid of bundle sheath. Though the botanical and physico-chemical characters of all the samples were quite similar but some variations were observed in High Performance Thin Layer Chromatography (HPTLC) fingerprint profile, the essential oil content and total percentage of asarone which was found to be highest in Lucknow and lowest in Delhi market sample. These variations may be explained due to some edaphic factors or storage conditions. An attempt was also made to test antioxidant activity (in vitro) and it was found to be 88% at 0.2 g/ml concentration.

• Geomechanics and Engineering
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• 제3권3호
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• pp.219-231
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• 2011

Waste fills resulting from coal mining should consist of large, free-draining sedimentary rocks fragments. The successful performance of these fills is related to the strength and durability of the individual rock fragments. When fills are made of shale fragments, some fragments will be durable and some will degrade into soil particles resulting from slaking and inter-particle point loads. The degraded material fills the voids between the intact fragments, and results in settlement. A laboratory program with point load and slake durability tests as well as thin section examination of sixty-eight shale samples from the Appalachian region of the United States revealed that pore micro-geometry has a major influence on degradation. Under saturated and unsaturated conditions, the shales absorb water, and the air in their pores is compressed, breaking the shales. This breakage was more pronounced in shales with smooth pore boundaries and having a diameter equal to or smaller than 0.060 mm. If the pore walls were rough, the air-pressure breaking mechanism was not effective. However, pore roughness (measured by the fractal dimension) had a detrimental effect on point load resistance. This study indicated that the optimum shales to resist both slaking as well as point loads are those that have pores with a fractal dimension equal to 1.425 and a diameter equal to or smaller than 0.06 mm.

• 동아시아식생활학회지
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• 제7권1호
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• pp.47-55
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• 1997

This study aims to know what the physicochemical properties and physical properties of the Korean traditional rice cake injulmi made from persimmon powder and glutinous rice(powder), and to come up with a standard recipe of it with the premixed powder of persimmon and glutinous rice. Cooked rice powder with 9 different levels of persimmon in cooling dough(75, 100 and 150${\mu}{\textrm}{m}$ power with each 20, 40, and 60%) was tested for rheological parameters, the rate of swelling, degree of gelatinization, sensory evaluation, and the observation of cross section used to electronmicroscope. 1. sensory evaluation conducted by 20 university students as panelists showed that mixed glutinous rice powder and persimmon powder lost their regular forms. increase in persimmon powder content increased a thin layer of starch granule, presumably due to sugar and fiber in the mixed persimmon powder granule. 3. In cooking the rice cake with 20~60% of persimmon, it showed 6.3 to 5.5 pH. 4. Quantitative description analysis conducted by 20 university student s panelists showed that sample that sample C was preferred among 9 samples. From these results, it was concluded that glutinous rice cake cooked with 20% of persimmon powder was quiet acceptable. Optimum cooking condition for the glutinous rice with persimmon powder rice cake was 30min of cooking time and 25$0^{\circ}C$ of cooking temperature with gas oven.

• 센서학회지
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• 제25권3호
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• pp.184-188
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• 2016

Highly ordered $SnO_2$ and NiO nanocolumns have been successfully achieved by glancing-angle deposition (GLAD) using an electron beam evaporator. Nanocolumnar $SnO_2$ and NiO sensors exhibited high performance owing to the porous nanostructural effect with the formation of a double Schottky junction and high surface-to-volume ratios. When all gas sensors were exposed to various gases such as $C_2H_5OH$, $C_6H_6$, and $CH_3COCH_3$, the response of the highly ordered $SnO_2$ nanocolumn were over 50 times higher than that of the $SnO_2$ thin film. This work will bring broad interest and create a strong impact in many different fields owing to its particularly simple and reliable fabrication process.