• Wind and Structures
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• 제32권4호
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• pp.293-308
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• 2021

For the past three decades a significant amount of research has been conducted on bridge flutter. Wind tunnel tests for a 2000 m class twin-box suspension bridge have revealed that a twin-box deck carrying 4 m tall 50% open area ratio wind screens at the deck edges achieved higher critical wind speeds for onset of flutter than a similar deck without wind screens. A result at odds with the well-known behavior for the mono-box deck. The wind tunnel tests also revealed that the critical flutter wind speed increased if the bridge deck assumed a nose-up twist relative to horizontal when exposed to high wind speeds - a phenomenon termed the "nose-up" effect. Static wind tunnel tests of this twin-box cross section revealed a positive moment coefficient at 0° angle of attack as well as a positive moment slope, ensuring that the elastically supported deck would always meet the mean wind flow at ever increasing mean angles of attack for increasing wind speeds. The aerodynamic action of the wind screens on the twin-box bridge girder is believed to create the observed nose-up aerodynamic moment at 0° angle of attack. The present paper reviews the findings of the wind tunnel tests with a view to gain physical insight into the "nose-up" effect and to establish a theoretical model based on numerical simulations allowing flutter predictions for the twin-box bridge girder.

• 한국안전학회지
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• 제33권2호
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• pp.52-60
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• 2018

This study compares the differences of the fit factor by the order of wearing preference between Particulate filtering facepiece respirators(PFFR) and glasses when participants wore simultaneously and a survey of physical and visual complaint. Recognition level about fit of respirators was investigated and the educational (before- and after-) effect of the fit factor. When participants wore PFFR and glasses, physical complaints were nose pressure, slipping, nose and ear pressure, ear pressure and rim loosen, the most highly physical complaints were nose pressure. Visual complaints were demister, blurry vision, dizziness, visual field, and lens dirty, the most highly visual complaints were demister. But, there was significant difference in physical complaint such as nose pressure(10.3%), slipping (23.0%), nose and ear pressure(14.3%), and rim loosen(16.2%), visual complaint such as visual field(13.8%) and lens dirty(32.4%). For the recognition of fit of respirators, respirators fitness, leak site, an initial point and an object, faulty factor, recognition level was higher. Fit factor was increased after education of proper wearing of respirator. Change of the fit factor was smaller compared to the normal breathing and after 6 actions in case of after education. Questionnaire consisted of general characteristics and physical/visual complaint, recognition of fit. Complaints were measured after the QNFT with multiple choices. Quantitative fit factor was measured by device and compared the result of (before- and after-) educational effect. Also, we selected to 6 actions (Normal breathing, Deep breathing, Bending over, Turning head side to side, Moving head up and down, Normal breathing) among 8 actions OSHA QNFT (Quantitative Fit testing) protocol to measure the fit factors. The fit factor was higher after the training (p=0.000). Descriptive statistics, paired t-test, and Wilcoxon analysis were performed to describe the result of questionnaire and fit test. (P=0.05) Therefore, it is necessary to investigate the quantitative research such as training program and glasses fitting factor about the wearing of PFFR and glasses simultaneously.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.414-419
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• 2011

Missile am fighter aircraft have been challenged by low restoring nose-down pitching moment at high angle of attach. The consequence of weak nose-down pitching moment can be resulting in a deep stall condition. Especially, the pressure oscillation has a huge effect on noise generation, structure damage, aerodynamic performance and safety, because the flow has strong unsteadiness at high angle of attack. In this paper, the unsteady aerodynamics coefficients were analyzed at high angle of attack up to 60 degrees around two dimensional NACA0012 airfoil. The two dimensional unsteady compressible Navier-Stokes equation with a LES turbulent model was calculated by OHOC (Optimized High-Order Compact) scheme. The flow conditions are Mach number of 0.3 and Reynolds number of $10^5$. The lift, drag, pressure distribution, etc. are analyzed according to the angle of attack. The results at a low angle of attack are compared with other results before a stall condition. From a certain high angle of attack, the strong vortex formed by the leading edge are flowing downstream as like Karman vortex around a circular cylinder. Unsteady velocity field, periodic vortex shedding, the unsteady pressure distribution on the airfoil surface, and the acoustic fields are analyzed. The effects of these unsteady characteristics in the aerodynamic coefficients are analyzed.

• 한국전산유체공학회지
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• 제18권1호
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• pp.1-6
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• 2013

Missile and fighter aircraft have been challenged by low restoring nose-down pitching moment at high angle of attach. The consequence of weak nose-down pitching moment can be resulting in a deep stall condition. Especially, the pressure oscillation has a huge effect on noise generation, structure damage, aerodynamic performance and safety, because the flow has strong unsteadiness at high angle of attack. In this paper, the unsteady aerodynamics coefficients were analyzed at high angle of attack up to 50 degrees around two dimensional NACA0012 airfoil. The two dimensional unsteady compressible Navier-Stokes equation with a LES turbulent model was calculated by OHOC (Optimized High-Order Compact) scheme. The flow conditions are Mach number of 0.3 and Reynolds number of $10^5$. The lift, drag, pressure, entropy distribution, etc. are analyzed according to the angle of attack. The results of average lift coefficients are compared with other results according to the angle of attack. From a certain high angle of attack, the strong vortex formed by the leading edge are flowing downstream as like Karman vortex around a circular cylinder. The primary and secondary oscillating frequencies are analyzed by the effects of these unsteady aerodynamic characteristics.

• 한국식품영양과학회:학술대회논문집
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• 한국식품영양과학회 2001년도 International Symposium on Food,Nutrition and Health for 21st Century
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• pp.140-151
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• 2001

This study was performed to examine a possible application of the beverage as a bad breath controlling food. To achieve this objective, methods of gas chromatography, electronic nose, sensory analysis and halimeter were used to detect reduction in odor intensities of bad breath caused by the functional beverage as well as its active ingredients. According to results of GC and electronic nose, adding green tea and champignon extracts to bad breath indicators, methylmercaptan and trimethylamine, resulted in significant reduction in headspace concentrations of two indicators. GC results revealed that headspace concentrations of 5 ug/ml of methylmercaptan and 30 ug/ml of trimethylamine added to various concentrations of two extracts were reduced up to $100\%$ after incubating mixtures at $37^{\circ}C$ for 5min. When the functional beverage was properly formulated with green tea extract, champignon extract and $\alpha$-cyclodextrin and evaluated for its deodorizing effect systematically, it also showed distinctive deodorizing activities against bad breath indicators. Conclusively, results obtained from this study might encourage introduction of a new type of bad breath control food in near future.

• 대한기관식도과학회:학술대회논문집
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• 대한기관식도과학회 1981년도 제15차 학술대회연제순서 및 초록
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• pp.12.4-12
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• 1981

비강 및 부비동에 발생하는 반전성유두종은 극히 드문 양성종양으로 1854년 Ward가 처음으로 보고하였으며 이후 여러학자들에 의하여 본증이 논의되어왔으나 우리나라에서는 그 보고례가 몇례 없었다. 비강 및 부비동에 발생하는 반전성유두종은 진성종양으로 비용과 현저히 다르며 제거후에도 재발하는 경우가 많고 드물긴 하지만 악성으로 변하는 경우가 있다. 일단 반전성유두종으로 밝혀지게 되면 가능한 한 광범위하게 제거해줘야되며 계속적인 추적조사가 필요하다. 최근 저자들은 비출혈, 비폐색, 취각장애, 두통을 주소로 내원한 64세된 여자환자에서 좌측 상악등에 압박괴사를 초래한 반전성유두종 1례를 치험하였기에 문헌고찰과 아울러 보고하는 바이다.

• 한국항공우주학회지
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• 제44권1호
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• pp.23-32
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• 2016

초고속으로 비행하는 물체의 항력을 줄이기 위해 노즈콘으로부터 제트를 분사하는 다양한 연구가 진행되고 있다. 본 연구에서는 항력감소의 기초자료와 핵심 변수를 파악하기 위해서 미국의 항력감소용 분사 제트 연구 동향을 조사하고 요약하였다. 연구에 활용한 노즈콘 모델의 형상은 반구 실린더, 잘린 콘, 재돌입 캡슐이었으며, 각 모델의 시험조건에 대해 정리하였다. 항력감소의 핵심 변수는 분사제트의 마하수, 질량유량, 압력비율이다. 항력감소효과는 주어진 조건에 따라 다양한 결과를 보였지만, 최대 40~50% 정도까지 항력이 감소하였다.

• 동의생리병리학회지
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• 제19권4호
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• pp.848-859
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• 2005

The following conclusions are drawn, through studying of referring literature, of contents of the prescription and of clinical applications in Hyungsang Medicine. Insamyangyung-tang(인삼양영탕) was appeared first in Taepunghyemin-whajegugbang(태평혜민화제국방) which was written by Jin and others at Song Dynasty. This prescription is applied to senility and long lasting weakness, little strength of spleen and lung(비폐기허), and insufficiency of blood. The Insamyangyung-tang is composed of medical stuffs which Rhizoma Cnidii is taken out from Sipjiendaebotang and Pericarpium Citri Nobilis, Fructus Schizandrae, Radix Polygalae are added to it. This prescription is used in China up to the present. In korea, according to Donguibogam, Rhizoma Cnidii and Poria are taken out from Sipjiendaebotang and Pericarpium Citri Nobilis, Fructus Schizandrae, Radix Polygalae are added to it, and Ramulus Cinnamomi is changed to Cortex Cinnamomi, and also Radix Ledebouriellae is newly added to it. This is reorganized to fit for Korean physical conditions and to be useful for deficiency of blood, and also to be efficacious for coming and going of chillness and fever and running with sweat due to weakness of Liver. In the point of view of Hyunsang medicine, Insamyangyung-tang is applied to shapes and symptoms as follows : This prescription becomes more efficacious to women than to men. At the age of fifties when liver grows weak it effects a cure. It takes effect to the shape of going easily into the deficiency of blood, that is, to the Hyul Kwa with an oval face. It effects a cure on the man who has wrinkles on the bridge of the nose, who has marks of being choked up on the central area between two brows, or who has distinctive size of eyes and nose. It is efficacious against symptoms which are to be exhausted, to be weak, to lose flesh, to be coming and going of chillness and fever and running with sweat.

• Composites Research
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• 제28권3호
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• pp.136-141
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• 2015

The stitching process has been widely utilized for the improvement of through-thickness property of the conventional laminated composites. This paper reports the effects of stitching on the flexural and interlaminar shear properties of multi-axial warp knitted (MWK) composites in order to identify the mechanical property improvements. In order to minimize the geometric uncertainties associated with the stacking pattern of fabrics, the regular lay-up was considered in the examination of the stitching effect. The key parameters are as follows: the stitch spacings, the stitching types, the stitching location, and the location of compression fixture nose. These parameters have little effect on the flexural and interlaminar shear properties, except for the case of stitching location. However, the geometry variations caused by the stitching resulted in minor changes to the mechanical properties consistently. Stitching on the $0^{\circ}$ fibers showed the lowest flexural strength and modulus (12% reduction for both properties). The stitch spacing of 5 mm resulted in 8% reduction for the case of interlaminar strength compared with that of 10 mm spacing.

• Archives of Plastic Surgery
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• 제32권5호
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• pp.593-598
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• 2005

Although several suspension biomaterials have been considered to be relatively safe and convenient, varying degrees of resorption have required repeated percutaneous injection. In the previous animal study the authors have reported that cultured human fibroblasts suspended in $Restylane^{(R)}$, which is modified hyaluronic acid, could produce human dermal matrices and prolong the effect of this gel. This study was undertaken to evaluate the clinical efficacy of this method. A total of 11 patients ranging from 25 to 57 years of age were included in this study between January of 2002 and December of 2003. All the patients were treated for the purpose of augmentation rhinoplasty. $1{\times}10^7/ml$ or $1.5{\times}10^7/ml$ cultured fibroblasts were suspended in 0.7 to 1.4 ml of $Restylane^{(R)}$. The implants were transferred to a 1-ml syringe and injected subcutaneously to the nose of the patients. Among 11 patients, long term follow-up for more than 1 year was possible in 6 patients. The injected implants remained in site without evidence of resorption or loss of correction. All the patients were satisfied with long term results of this method. There was no complication during the follow-up period.