• 대한기계학회논문집B
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• 제21권9호
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• pp.1126-1138
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• 1997

An axisymmetric laminar jet diffusion flame has been numerically modelled. The present study employs the refined physical submodels to account for the detailed chemical kinetics and the variable transport properties. It is found that preferential diffusion resulting from variable transport properties significantly influences the hydrogen diffusion flame structure in terms of the spatial distribution for temperature, species concentration, thermal and mass diffusivity, Lewis number, and NO concentration. The preferential diffusion effects on the diffusion flame in the high-pressure environment are also discussed in detail.

• 한국초전도ㆍ저온공학회논문지
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• 제15권1호
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• pp.6-10
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• 2013

We investigate the electrical and thermal transport properties of a sesquicarbide superconductor $La_2C_3$, including electrical resistivity, thermoelectric power, and thermal conductivity. The electrical resistivity exhibits a typical metallic character with a saturation behavior at high temperatures. The thermoelectric power shows a metallic behavior with pronounced phonon-drag effect, comparable with pure metals. The broad peak of the thermal conductivity is observed in the superconducting state, which is rapidly suppressed by magnetic fields. These observations suggest that the electron-phonon scattering is significant in $La_2C_3$, which is relevant with the relatively high-$T_c$ in $La_2C_3$ through strong electron-phonon coupling with low frequency phonon modes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 학술대회 및 기술세미나 논문집 디스플레이 광소자
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• pp.85-88
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• 2006

The transport properties of amorphous selenium typical of the material used in direct conversion x-ray imaging devices are reported. The effects of As addition on the carrier mobility and recombination lifetime in amorphous selenium (a-Se) films have been studied using the moving photocarrier grating (MPG) technique. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density. The transport properties for As doped a-Se films obtained by using MPG technique have been compared with the drift mobilities of holes and electrons obtained by time of flight (TOF) measurement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.984-986
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• 1999

In the case of immobilizing of glucose oxidase in organic polymer using electrosynthesis, the glucose oxidase obstructs charge transfer and mass transport during the film growth. This may lead to short chained polymer and make charge-coupling weak between the glucose oxidase and the backbone of the polymer. That is mainly due to insulating property and net chain of the glucose oxidase. Such being the case, it is useless to increase in amount of glucose oxidase more than reasonable in the synthetic solution. We establish by means of qualitative analysis that amount of immobilized glucose oxidase can be improved by adding a hole ethyl alcohol in the synthetic solution. As ethyl alcohol was added by 0.1mol $dm^{-3}$ in the synthetic solution, the faradic impedance of resultant electrode was increased about five times as much as the case of ethyl alcohol free in the solution, and mass transport was limited more than over. That is due to insulating property and net chain of the glucose oxidase. Moreover, in ultraviolet spectra of the synthetic solution, the adsorption peak at 285nm corresponding to glucose oxidase was decreased. It suggests increase in amount of immobilized glucose oxidase.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
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• pp.17-20
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• 2002

The effects of relatively low lead content (0.2~0.3) on the 2223 phase formation and transport property of Bi-2223/Ag tapes have been investigated. The results show that lead contents have great impact on the phase assemblage of precursors, subsequently, on the phase formation and transport property of silver sheathed BSCCO-2223 tapes. Powders containing Pb=0.25 and Pb=0.3 resulted in the nearly identical $J_c$ values in fully processed tapes, but leaded to significant difference on the phase formation process. For the case of Pb=0.2, both low conversion fraction of 2212 to 2223 and low $J_c$ value were obtained in final reacted tape, which was probably due to lack of enough liquid phase to facilitate the phase transformation.

• 한국의류학회지
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• 제41권1호
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• pp.84-97
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• 2017

Water vapor and thermal transmission properties of high emotional garments are important to evaluate wear comfort; in addition, the measuring methods of these properties are also critical for breathable and warm suit fabrics. In this study, the water vapor and thermal properties of composite yarn fabrics made of CoolMax, Tencel, and Bamboo fibers with filaments were measured and compared according to the measuring method. Water Vapor Transmittance (WVT) of the fabric woven by the sheath/core composite yarn in the warp direction was the highest due to the small staple fiber volume in the sheath/core yarn structure and high air voids in the sheath/core yarn fabrics. This property was also the highest in fabrics woven by bamboo staple yarns in the weft direction, and was the lowest on hi-multi filament fabrics. However, water vapor resistance ($R_{ef}$) of these fabrics by KSK ISO 11092 showed the opposite results to the water vapor transmittance method ($CaCl_2$ method); in addition, its correlation coefficient was low. The correlation coefficient between $R_{ef}$ and the drying rate was 0.719; therefore, the measurement mechanism of $R_{ef}$ is analogous to the drying property measurement. The thermal conductivity of the fabrics woven with compact staple yarn showed a high value; however, the hi-multi filament fabric showed low thermal conductivity. Therefore, fiber characteristics affect thermal properties more than yarn structure. The correlation between thermal property and moisture transport was also low. This study showed that: water vapor transmittance was active at the loose yarn structure, dry heat transport was vigorous at the compact yarn structure, and heat transport was affected more by fiber characteristics than yarn structure. In conclusion, sheath/core composite yarns were relevant to the high absorptive cool suit along with siro-fil and CoolMax/Bamboo staple yarns that were relevant to the heat diffusive cool suit.

• 한국항만학회지
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• 제14권4호
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• pp.451-461
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• 2000

The design and maintenance of navigation channel and water facilities of an harbor which is located at the mouth of river or at the estuary area are difficult due to the complexity of estuarial water and sediment circulation. Effects of deepening navigable waterways, of changing coastline configurations, or of discharging dredged material to the open sea are necessary to be investigated and predicted in terms of water quality and possible physical changes to the coastal environment. A borad analysis of the transport mechanism in the estuary area was made in terms of sediment property, falling velocity, concentration and flow characteristics. In order to simulate the transport processes, a two-dimensional finite element model is developed, which includes erosion, transport and deposition mechanism of suspended sediments. Galerkin’s weighted residual method is used to solve the transient convection-diffusion equation. The fluid domain is subdivided into a series of triangular elements in which a quadratic approximation is made for suspended sediment concentration. Model could deal with a continuous aggregation by stipulating the settling velocity of the flocs in each element. The model provides suspended sediment concentration, bed shear stress, erosion versus deposition rate and bed profile at the given time step.

• 한국ITS학회 논문지
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• 제6권1호
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• pp.27-37
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• 2007

과속단속시스템은 지능형교통체계(ITS)의 한 영역인 첨단교통관리시스템(ATMS)으로서 중요한 역할을 수행하고 있다. 그러나 과속사고를 방지하기 위해 설치된 시스템이 시거가 확보되지 않은 구간이나 급커브 지역 등에 설치됨으로써 추가적인 교통사고 위험을 내포하고 있다. 이에 본 연구에서는 고속도로의 기하구조별로 시스템 설치위치를 구분하고, 각 위치에서 발생한 교통사고 자료를 시스템 설치 전 후로 나누어 기하구조별 과속단속시스템의 설치 전 후의 사고건수(Frequency), 대물피해환산법(EPDO, Equivalent Property Damage Only)을 통한 사고심각도와 사고비용(Accident Cost)을 분석하였다. 이와 같은 연구수행 절차를 통해 시거가 충분히 확보되지 않는 구간에서의 과속단속시스템의 설치가 사고에 미치는 영향을 알아보고 최종적으로 과속단속시스템의 설치위치에 따른 영향을 분석하고자 한다.

• 한국ITS학회 논문지
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• 제14권5호
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• pp.30-37
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• 2015

MIMO(Multiple Input Multiple Output) 시스템을 사용하여 주파수 선택적 페이딩 환경에서 동작하는 차세대 무선 통신 시스템의 데이터 전송 속도를 향상시키기 위한 연구가 현재 활발히 진행 중이다. 여러 개의 송신 안테나에서 송신된 시호들이 혼합되어 각 수신 안테나에 수신되는데 이렇게 혼합된 신호를 분리하기 위해서 직교 특성을 갖는 훈련신호가 필요하며, 이 훈련신호를 사용하여 신호의 동기화 및 채널 추정을 수행할 수 있어야 한다. 본 논문에서는 MIMO 통신 시스템에 사용 가능한 시퀀스들을 소개하고, 관심 영역에 대하여 우수한 자기 상관 특성을 갖는 변형된 WeCAN(weighted cyclic algorithm new) 시퀀스를 제안한다. 모의실험을 통해 각 훈련신호의 자기 상관도를 비교하였으며, 또한 도플러 주파수 변화와 다중경로 전달 페이딩 환경에서의 상관 특성을 비교하였다.

• 한국통신학회논문지
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• 제30권11A호
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• pp.979-986
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• 2005

광전달망(Optical Transport Network)에서 사용자의 서비스 요구는 종종 주기적인 특성을 보이므로 이러한 계획 연결 요구에 대하여 시간 중복성을 RWA 문제에 이용할 수 있다. 계획 연결 요구의 RWA 문제는 조합 최적화 방법(Combinatorial Optimal Solution)과 그래프 컬러링(Graph Coloring)의 조합으로 해결되거나, 경로 선택에 기반한 순차적(sequential) RWA(sRWA) 의해서 해결된다. 이와 같은 방법은 복잡하거나 많은 연산을 필요로 하므로 본 논문에서는 그룹화를 통해 계획 연결 요구들의 시간 중복성을 이용하여 효과적으로 경로 설정 및 파장 할당을 하는 알고리즘을 제안한다. 본 논문에서 제안하는 알고리즘이 현재 실질적으로 효율적이라 알려진 sRWA 보다 같거나 작은 파장 수를 사용하여 $54\%$ 이상의 계산량의 성능 향상을 보인다.