• Journal of Advanced Marine Engineering and Technology
• /
• 제21권5호
• /
• pp.549-556
• /
• 1997

The inverse heat conduction problems is the calculation of surface heat transfer coefficients by utilizing measured temperature. The numerical technique of finite element analysis and optimizition is introduced to calculate temperatures and heat transfer coefficients. The calculated heat transfer coefficients and temperature distribution are good agreement with the results of direct analysis. The inverse method has been applied to the control valve of nuclear power plant.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 춘계학술대회 논문집
• /
• pp.196-200
• /
• 2003

To fulfill the railroad station's duties efficiently, it is essential to view passenger transfer system within the railroad station and in the vicinity of railroad station in the context of broader technological developments in easy access to railroad station. To do the direct service to local station or easy transfer to other mass transportation modes, necessary courses for local govemments and each transportation agency involvement should be taken and long-term integrated transfer strategy must be found. The research designed here was designed to derive a general overview of the integrated transfer patterns with an emphasis on passenger intermodal transportation system.

• 설비공학논문집
• /
• 제14권1호
• /
• pp.38-45
• /
• 2002

Evaporative heat transfer characteristics of carbon dioxide have been investi- gated by experiment. The experiments have been carried out for a seamless stainless steel tube of the outer diameter of 9.55 mm, the inner diameter of 7.75 mm and the length of 5.0 m. Direct heating method was used for supplying heat to the refrigerant where the test tube was uniformly heated by electric current which was applied to the tube wall. Experiments were conducted with$CO_2$of purity 99.99% at saturation temperatures of 0.0 to 10.5$^{\circ}C$, heat fluxes of 12 to 27kW/$m^2$s and mass fluxes of 212 to 530 kg/$m^2$s. The heat transfer coefficients of $CO_2$are decreased as the vapor quality increases and these phenomena are explained by dimensionless Weber and Bond numbers. The heat transfer coefficients of$CO_2$increase when the heat and mass fluxes increase, and the saturation temperature effects are minor in the test range of this study. The present experimental data are compared with six renowned correlations with root-mean-squared deviations ranging from 23.0 to 94.9% respectively.

• 한국태양에너지학회 논문집
• /
• 제22권4호
• /
• pp.35-43
• /
• 2002

This research makes that quantitative radiation property of an actual town ward is obtained in quest of the parameter with regard to a radiation heat transfer property and set up several town ward models that reproduced a solid form of a city along the attribute of the city. A regular trend possibility that is able to evaluate a radiation characteristics of a town ward quantitatively from a town ward guideline and confirmation that is produced about each parameter as a result of a numerical value simulation it obtained. This research shot a coefficient of Gebhart's emission absorption. sky radiation absorption rate direct solar radiation absorption rate the parameter with regard to a radiation heat transfer characteristics of a town ward in each town ward model and a volume rate of a town ward advances case study under regular such condition and shot the absorption rate, direct and others days and calculated an absorption rate and checked about the relation between a town ward and each radiation heat transfer property of a city.

• 한국생산제조학회지
• /
• 제7권6호
• /
• pp.110-116
• /
• 1998

For the vibration analysis of 3-dimensional piping system containing fluid flow, a transfer matrix method is presented. The fluid velocity and pressure were considered, that coupled to longitudinal and flexural vibrations. Transfer matrices and point matrices were derived from direct solutions of the differential equations of motion of pipe conveying fluids, and the variations of natural frequency with flow velocity for 3-dimensional piping system were investigated.

• Journal of Welding and Joining
• /
• 제20권5호
• /
• pp.127-133
• /
• 2002

In this study, metal transfer characteristics in pulsed current metal inert gas (MIG) welding of aluminum was investigated. Based on the metal transfer characteristics from direct current electrode negative MIG welding, the one drop per one pulse(ODOP) condition was predicted and compared with experimental data. The results indicated that experimental pulse range for the ODOP condition is wider than that predicted from the DCEP MIG welding data. In addition, more stable metal trnasfer behavior was obtained at the higher end of the ODOP condition.

• 기술사
• /
• 제42권3호
• /
• pp.41-46
• /
• 2009

A new subway, line 9 linking Western and Eastern Seoul began its services for citizens between Gimpo airport and Gangnam area within 30 minutes by express transit service. Seoul Metro Line 9 Corporation plans to operate both local transit service which will stop at every station, and express transit service that will stop at several key stations including junctions. The passengers on line 9 will be able to transfer to lines 2, 3, 5, 8, Bundang and Incheon International Airport. The Line 9 is expected to disperse the demand for line 2, having the most number of subway users, and will provide passengers with less crowded travel. The new line will also help residents in southern Seoul outskirts and Gyeonggi provincial cities including Bundang vicinity, and Gangdong area commuters get better access to Gimpo and incheon Airports. The Corporation expects to transfer 560,000 passengers daily by the subway line 9. Seoul Development Institute conducted network reshuffle study for Seoul Metro system to sort out congestion problem due to its irrational line alignments and inconvenient transfer. Among several candidate plans of network reshuffling, the direct connection of line 9 with line 5 was chosen as a pilot study. The study found that direct connection of the 2 lines is essential for enhancing transit utility and reducing automobile commuters.

• 한국가시화정보학회지
• /
• 제22권1호
• /
• pp.79-84
• /
• 2024

As microchips' degree of integration is getting higher, its cooling problem becomes important more than ever. One of the promising methods is using fractal microchannel heat sink by mimicking nature's Murray networks. However, most of the related works have been progressed only by numerical analysis. Perhaps such lack of direct experimental studies is due to the technical difficulty of the temperature and heat flux measurement in complex geometric channels. Here, we demonstrate the direct visualization of in situ temperature profile in a fractal microchannel heat sink. By using the temperature-sensitive fluorescent dye and a transparent Polydimethylsiloxane window, we can map temperature profiles in silicon-based fractal heat sinks with various fractal scale factors (a=1.5-3.5). Then, heat transfer rates and pressure drops under a fixed flow rate were estimated to optimize hydrodynamic and thermal characteristics. Through this experiment, we found out that the optimal factor is a=1.75, given that the differences in heat transfer among the devices are marginal when compared to the variances in pumping power. This work is expected to contribute to the development of high-performance, high-efficiency thermal management systems required in various industrial fields.

• 한국전자파학회논문지
• /
• 제24권1호
• /
• pp.47-54
• /
• 2013

본 연구는 국내 최초로 개발된 직접 비교법을 이용한 W-band 밀리미터파 전력 표준 전달 시스템에 대한 것이다. 이 시스템은 75~110 GHz 대역에서 W-band 도파관형 전력감지기의 실효 효율과 교정 인자를 측정하기 위하여 개발되었다. 전력 표준 전달 시스템 구성의 핵심 요소인 방향성 결합기의 반사 특성 평가 기법을 소개하고 실험 결과를 보인다. 구현된 시스템을 이용하여 측정하고자 하는 전력감지기의 교정 인자 측정 결과를 보이고, 불확도 요인에 대하여 고찰한다. 측정 결과를 기준값과 비교하여 W-band 밀리미터파 전력 표준 전달 시스템에 의한 측정의 유효성을 검증한다.

• 한국수정란이식학회지
• /
• 제11권2호
• /
• pp.151-158
• /
• 1996

This study was carried out to investigate the effect of equilibration time, sucrose concentration and age of embryo on survival and developmental rates of bovine IVF expanding blastocysts frozen-thawed by direct transfer method. The bovine oocytes were collected from 2~5mm follicles, matured for 20~24hrs in 5% $CO_2$incubator and then fertilized with frozen-thawed semen. Expanding blastocysts at day 7, 8, 9, 10 and 11 after IVF were frozen in 1.8M ethylene glycol(EG). Survival and hatching rates of frozen-thawed IVF embryos were examined. The results were as follow ; Survival and hatching rate of TVF expanding blastocysts after 10, 20, 3Omin exposure in 1.8M EG were 100,0,90.9, 47.1, 85.0, 75.0 and 62.5% respectively. Survival rates of IVF expanding blastocysts frozen with 1.8M EG and various concentration(0, 0.25, 0.5, 1M) of sucrose were 73.3, 25. 0, 16.7, 9.1% respectively. Survival and hatching rates of IVF expanding blastocysts frozen-thawed according to age of embryo(Day 7, 8, 9,10, 11) were 86.1, 84.8, 79.3, 61.4, 51.3, 74.2, 76.9, 71.7, 63.0 and 65.0% respectively. In conclusion, the age of the embryo(Day 7, 8) is very important for the successful freezing of IVF bovine embryos and 1.8M ethylene glycol not containing sucrose may be effective cryoprotectant for direct transfer method.