• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.1077-1085
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• 1997

The use of "clean fuels" such as butane, propane, and mixtures of these (LPG) is an attractive way to reduce exhaust emissions. In this study internal flow of the pintle type injector for LPG engine is studied. The breakup of liquid jet is the result of competing, unstable hydrodynamic forces acting on the liquid jet as it exits the nozzle. The nozzle geometry and up-stream injection conditions affect the characteristics of flow inside the nozzle, such as turbulence and cavitation bubbles. A set of calculations of the internal flow in a pintle type nozzle were performed using a two dimensional flow simulation under different nozzle geometry and upstream flow conditions. The calculation showed that the turbulent intensity and discharge coefficient are related to needle leading angle(.alpha.) and needle lift.edle lift.

• Toxicological Research
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• v.17 no.4
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• pp.249-253
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• 2001

Fumonisin B1, a mycotoxin, is thought to induce esophageal cancer in humans and apoptosis in animal cells by inhibiting ceramide synthase. Dumonisin Bl may also generate reactive oxygen species directly or indirectly, leading to DNA damage and lipid peroxidation. In this study, a DNA fragmentation assay, dichlorofluorescein (DCF) analysis, and single cell gel electrophoresis (SCGE) were used to investigate the involvement of cellular free radicals, specifically hydrogen peroxide, in the DNA damaging activity of fumonisin B1. From an in vitro DNA fragmentation assay, E. coli DNA, damage by fumonisin Bl was increased by the addition of superxide dismutase (SOD) and decreased by catalase. SCGE and DCF analysis in vivo showed that the nuclear DNA damage and intracellular free radicals in cultured rat hepatocytes treated with fumonisin B1 were increased with the concentration of fumonisin Bl . DNA damage and free radical generation were inhibited by the addition of catalase. Fumonisin Bl , in the presence of SOD, produces hydrogen peroxide causing oxidative DNA damage and protein malfunction, leading to genotoxicity and cytotoxicity of the toxin.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.5
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• pp.680-687
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• 2001

In this study, spin-up flows in a rectangular container are analysed both numerically and experimentally. In the numerical computation, we use two Ekman pumping models, the classical leading order and the first order. We also compared our results with those obtained for the case without a pumping model. Effect of two parameters, Reynolds number and the Rossby number on the flow evolution is studied. The first order and the leading order Ekman pumping models are in good agreement with the experimental result compared with the non-Ekman pumping model. Attention is given to the merging of two cyclonic vortices.

• Natural Product Sciences
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• v.7 no.4
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• pp.114-119
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• 2001

The effect of Rhinacanthus nasutus leaf extract on the growth of dermatophytes had been investigated. In vitro the extract exhibited high activity against various species of dermatophytes (Trichophyton mentagrophytes var. mentagrophytes, T. mentagrophytes var. interdigitale, T. rubrum, Microsporum canis and M. gypseum). The minimal inhibitory concentration (MIC) values of the extract revealed that all the dermatophytes tested had MIC values of 13.6 mg/ml. The extract exhibited fungistatic activity at lower concentrations $({\leq}13.6\;mg/ml\;or\;below\;the\;MIC\;value)$ and fungicidal activity at higher concentrations $({\geq}13.6\;mg/ml$\;or\;above\;the\;MIC\;value)$. The results suggested that the extract acted on the cell wall of the dermatophytes which subsequently leading to the formation of cytopathological and membrane structural degeneration and finally leading to cell lysis and death.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.93-101
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• 2006

풍력발전의 보급확대는 전력시장의 특성으로 인하여 국가적 차원의 정책에 의존될 수 밖에 없는 태생적 한계를 지니고 있다. 역설적으로, 풍력발전은 정부기획에 의하여 시장조성(설계)이 가능하고, 따라서 풍력발전과 관련한 설비제조업, 발전사업, 단지 건설업 및 서비스업 등으로 구성되는 '풍력산업'은 국가적 차원의 적정한 정책 수단으로 육성될 수 있는 새롭게 부상하는 산업부문이다. 선진 외국의 전력시장에서 관찰되는 풍력산업의 출현 및 성숙과정을 참고로, 우리나라에서의 풍력발전의 보급확대를 위한 전략을 원론적 차원에서 모색하고자 하였다. 기술경영학적 관점에서 풍력산업의 육성도 결국 '기술주도'가 아닌 '시장주도'에 의한 것이 효과적일 수밖에 없으며, 풍력발전의 보급확대를 통한 수요의 창출은 에너지믹스(Energy Mix)와 관련한 국가차원의 정책적 의지와 선택의 문제일 뿐이다.

• Clinics in Shoulder and Elbow
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• v.2 no.2
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• pp.138-142
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• 1999

Coracoclavicular ligament is main restraint to superior instability of the distal clavicle. Coracoacromial ligament, extensor tendon of toe, palmaris longus tendon, and Dacron tape have been used to reconstruct coracoclavicular ligament. We used semitedinosus tendon to reconstruct coracoclavicular ligament. The semitendinosus tendon was harvested as a usual fashion. After the distal clavicle and coracoid process were exposed, a hole of six millimeter diameter was made on the center of whole thickness of the distal clavicle. A malleolar screw was fixed from distal clavicle to coracoid process to maintain the reduced position of the acromioclavicular joint. The leading suture of tendon graft was passed through the hole of the distal clavicle and looped under the coracoid process. After leading portion of ten­don graft was looped over the clavicle, sutures were made between each end of the tendon graft with nonabsorbable suture materials.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.11 s.242
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• pp.1439-1444
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• 2005

A two-dimensional boundary element method was used for the scattering analysis of side-drilled hole(SDH). The far-field scattering amplitude was calculated for shear vertical(SV) wave, and their frequency and time-domain results were presented. The time-domain scattering amplitude showed the directly reflected wave from the SDH leading edge as well as the creeping wave. In an immersion, pulse-echo testing, two measurement models were introduced to predict the response from SDHs. The 2-D boundary element scattering amplitude was converted to the 3-D amplitude to be used in the measurement model. The receiver voltage was calculated fer SV wave incidence at 45$^{\circ}C$ on the 1 m diameter SDH, and the result was compared with experiment.

• Wind and Structures
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• v.4 no.6
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• pp.481-494
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• 2001

Wind tunnel pressure tests were conducted on a 1:100 scale model of a large industrial building with solar panels mounted parallel to the flat roof. The model form was chosen to have the same aspect ratio as the Texas Tech University test building. Pressures were simultaneously measured on the roof, and on the topside and underside of the solar panel, the latter two combining to produce a nett panel pressure. For the configurations tested, varying both the lateral spacing between the panels and the height of the panels above the roof surface had little influence on the measured pressures, except at the leading edge. The orientation of the panels with respect to the wind flow and the proximity of the panels to the leading edge had a greater effect on the measured pressure distributions. The pressure coefficients are compared against the results for the roof with no panels attached. The model results with no panels attached agreed well with full-scale results from the Texas Tech test building.

• Annals of Geriatric Medicine and Research
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• v.22 no.4
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• pp.159-166
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• 2018

The Korean Geriatrics Society was founded on October 3, 1968. Over the 50 years since then, the Society has incessantly strived to stay attuned to the aging society and to achieve an increasingly greater research impact in the field of gerontology and geriatric medicine. The Society has passed through periods of preparation for a leap forward, followed by rapid growth, expansion, and maturity. As a result, the Society has gained a firm foothold at home and abroad as a leading research society for both qualitative and quantitative achievements in geriatric medicine. At this juncture, with an ultra-aging society being just around the corner, we are celebrating its 50th anniversary and anticipating our second half-century with great enthusiasm about our mission and role as a leading geriatric research organization.

• Bulletin of the Korean Mathematical Society
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• v.56 no.4
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• pp.1077-1097
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• 2019

Let M be a finitely generated module over a regular local ring (R, n). We will fix an n-stable filtration for M and show that the minimal free resolution of M can be obtained from any filtered free resolution of M by zero and negative consecutive cancellations. This result is analogous to [10, Theorem 3.1] in the more general context of filtered free resolutions. Taking advantage of this generality, we will study resolutions obtained by the mapping cone technique and find a sufficient condition for the minimality of such resolutions. Next, we give another application in the graded setting. We show that for a monomial order ${\sigma}$, Betti numbers of I are obtained from those of $LT_{\sigma}(I)$ by so-called zero ${\sigma}$-consecutive cancellations. This provides a stronger version of the well-known cancellation "cancellation principle" between the resolution of a graded ideal and that of its leading term ideal, in terms of filtrations defined by monomial orders.