• 대한교통학회지
• /
• 제27권5호
• /
• pp.189-194
• /
• 2009

환승은 대중교통의 대표적인 취약점으로 꼽히는 불편함으로, 대중교통의 경쟁력을 약화시키는 요소이다. 이에 환승으로 인한 불편함 중 개선가능한 요소들을 체계적이고 효과적으로 개선하기 위하여 환승시설 및 환승체계의 물리적 요소들에 대한 보행자 편의성을 계량화하여 환승역사의 환승 편의성에 대한 객관적 평가기준을 마련하고자 한다. 본 연구는 특히 KTX 역사 및 철도 역사를 대상으로 지역간 통행에 있어서 환승역사의 물리적 특성이 환승수단의 선택에 미치는 영향을 파악하고 그 과정에서 환승저항 모형을 구축하였다. 또한 이를 바탕으로 국내 주요 KTX역사 및 철도역사 환승시설을 대상으로 환승저항값을 산정하여 비교하였다. KTX 역사와 철도역사의 물리적 요소들 중 환승 의사결정에 유의하게 영향을 미치는 요소는 환승패스의 외부보행거리, 환승패스의 내부보행거리, 계단 수, 에스컬레이터 수로 동일하게 나타났으나 환승저항 요소의 상대적 크기에 있어서는 차이가 있는 것으로 분석되었다. 에스컬레이터 1대는 약 1~3분의 체감시간 절감 효과를 가지는 것으로 나타났다. 산출된 환승저항 모형은 환승역사별 시설여건을 비교하고 시설개선의 우선순위를 판단하는 데에 객관적 지표로 활용될 수 있을 것이라 기대된다.

• 수산해양교육연구
• /
• 제16권2호
• /
• pp.257-270
• /
• 2004

The two-phase closed thermosyphon is a heat transfer device capable of transfer large quantities of heat from a source to a sink by taking advantage of the high heat transfer rates associated with the evaporation and condensation of a working fluid within the device. A study was carried out with the performance of the heat transfer of the thermosyphon having 50, 60, 70, 80, 90 internal micro grooves in which boiling and condensation occur. A plain thermosyphon having the same inner and outer diameter as the grooved thermosyphon is also tested for comparison. Water, methanol and ethanol have been used as the working fluids. The liquid filling as the ratio of working fluid volume to total volume of thermosyphon, the inclination angle, micro grooves and operating temperature have been used as the experimental parameters. The heat flux and the boiling and the condensation heat transfer coefficient and overall heat transfer coefficient at the condenser and evaporator zone are estimated from the experimental results. The experimental results have been assessed and compared with existing correlations. Imura's and Kusuda's correlation for boiling showed in good agreement with experimental results within ${\pm}20$％ in plain thermosyphon. The maximum heat transfer rate was obtained when the liquid fill ratio was about 25%. The high heat transfer coefficient was found between 25o and 30o of inclination angle for water and between 20o and 25o for methanol and ethanol. The relatively high rates of heat transfer have been achieved in the thermosyphon with internal micro grooves. The micro grooved thermosyphon having 60 grooves shows the best heat transfer coefficient in both condensation and boiling. The maximum enhancement (i.e. the ratio of the heat transfer coefficients of the micro grooved thermosyphon to plain thermosyphon) is 2.5 for condensation and 2.3 for boiling.

• 국제지역연구
• /
• 제22권1호
• /
• pp.23-40
• /
• 2018

중국은 2000년대 들어 '삼농(三?)'문제(농민, 농업, 농촌)를 국가 최우선과제로 추진하고 있다. '삼농'문제 해결책의 하나인 농지유동은 최근 10여 년간 급속히 성장하였다. 특히 농지유동을 추진함에 따라 농촌경제가 발전하였으며 동시에 농가 생활수준도 크게 개선되었다. 그러나 전포방식 위주의 농지유동유형은 농가의 농지유출 의욕을 저해하여 궁극적으로 대규모 농지유동의 저해요인으로 작용하고 있다. 본 논문은 중국 농가의 농지유동유형 영향요인과 농지유동가격 결정요인을 분석하였고, 그 결과를 토대로 다음과 같은 시사점을 찾았다. 첫째, 농가들이 입고방법으로 농지를 유출하도록 지도해야 하고; 둘째, 계약기간을 장기화해야 하며; 셋째, 작물별 농지유동 대응책을 마련해야 하고; 넷째, 농지유출 농가에 대해 교육프로그램을 구축해야 한다.

• 예술인문사회 융합 멀티미디어 논문지
• /
• 제6권1호
• /
• pp.39-48
• /
• 2016

암묵지는 전이를 통해 증식되며, 가치 또한 증대된다. 암묵지 전이는 조직의 경쟁력 향상을 위한 가장 중요한 역할을 담당하고 있다. 암묵지 전이가 매우 중요함에도 불구하고, 암묵지 전이는 활발히 이루어지지 못하고 있다. 암묵지 전이를 방해하는 장벽이 암묵지 전이를 저해하고 있기 때문이다. 암묵지 전이를 방해하는 장벽은 지식과 지식전문가에 대한 이해부족, 업무 가중 및 미흡한 보상, 신뢰부족과 지식 접착성(Knowledge Stickiness)이다. 암묵지 전이의 장벽을 극복하기 위해서는 암묵지 지식전이를 주도적으로 추진하는 대리인이 필요하다. 지식중개자는 암묵지 전이를 위한 근간이며, 효율적인 지식네트워크의 구축은 암묵지 전이를 위한 핵심성공요소이다. 그러나 지식네트워크 관련된 대부분의 연구는 네트워크의 근접성과 밀도, 중심성 등 기초지표를 활용하는 수준에 머무르고 있다. 암묵지 전이 활성화를 위한 새로운 지식중개인 진단 프레임워크가 필요하다. 따라서 사회연결망분석을 기반으로 조직관점 및 지식근로자관점의 암묵지 전이를 분석하고, 이를 기반으로 BSKT 구축안을 제시하고자 한다.

• 한국주조공학회지
• /
• 제14권3호
• /
• pp.248-257
• /
• 1994

Research in heat transfer and solidification commonly involves experimentation and mathematical modeling with associated numerical analysis and computation. Inverse problems in heat transfer are part of this paradigm. During the solidification of metal casting, an interfacial heat transfer resistance exists at the boundary between the casting and the mold, and this heat transfer resistance usually varies with time. In the case of the squeeze casting the contact heat transfer resistance is decreased by pressure and ideal contact is almost accomplished. In the present work, heat transfer coefficient, which is inverse value of the heat transfer resistance, was used for convenience. A numerical technique, Non-Linear Estimation has been adopted for calculation of the casting/mold interfacial heat transfer coefficient during the squeeze casting process. In this method, the measured temperature data from experiment were used. The computational results were applied to the analysis of heat transfer and solidification.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.3395-3400
• /
• 2007

Heat transfer experiments at a vertical annulus passage were carried out in the SPHINX(Supercritical Pressure Heat Transfer Investigation for NeXt Generation) to investigate the heat transfer behaviors of supercritical $CO_2$. The collected test data are to be used for the reactor core design of the SCWR (SuperCritical Water-cooled Reactor). The mass flux was in the range of 400${\sim}$1200 kg/$m^2$s and the heat flux was chosen up to 150 kW/$m^2$. The selected pressures were 7.75 and 8.12 MPa. The heat transfer data were analyzed and compared with the previous tube test data. The test results showed that the heat transfer characteristics were similar to those of the tube in case of a normal heat transfer mode and degree of heat transfer deterioration became smaller than that in the tube. Comparison of the experimental heat transfer coefficients with the predicted ones by the existing correlations showed that there was not a distinct difference between the correlations.

• International Journal of Railway
• /
• 제2권2호
• /
• pp.60-69
• /
• 2009

In recent years, technology developments in different countries, especially in newly industrialized countries, are extremely indebted to appropriate technology transfer by these countries. Nevertheless the technology transfer process in the present situation is complex, and its success is related to the coordination rate with the political, economic, social, and environmental objectives of countries. Today debates related to the transfer of the technical know how accompanied by equipment hardware has found remarkable importance such that countries seek increasing comprehensive capabilities in the field of transferred technology for which Preventive Maintenance (PM) is one of the aspects. This research with the purpose to determine the technological capability level and to study the role of PM in the effective & appropriate technology transfer in subway industry is carried out for presenting a suitable model for the technology transfer in this industry with an attitude towards the effects of principal PM factors. For this purpose, after the study of different and relevant models existing in the field of suitable methods for technology transfer, some equipment PM theories and models were selected as the base for the compilation of the questionnaire. With the help of questionnaire, main PM factors that are effective in the field of technology transfer were extracted, and finally, their effects on technology transfer were analyzed, identified and a comprehensive model suggested in this connection.

• Membrane and Water Treatment
• /
• 제2권3호
• /
• pp.159-173
• /
• 2011

The air gap membrane distillation (AGMD) process was applied for water desalination. The main objective of the present work was to study the heat and mass transfer mechanism of the process. The experiments were performed on a flat sheet module using aqueous NaCl solutions as a feed. The membrane employed was hydrophobic PTFE of pore size 0.22 ${\mu}m$. A mathematical model is proposed to evaluate the membrane mass transfer coefficient, thermal boundary layers' heat transfer coefficients, membrane / liquid interface temperatures and the temperature polarization coefficients. The mass transfer model was validated by the experimentally and fitted well with the combined Knudsen and molecular diffusion mechanism. The mass transfer coefficient increased with an increase in feed bulk temperature. The experimental parameters such as, feed temperature, 313 to 333 K, feed velocity, 0.8 to 1.8 m/s (turbulent flow region) were analyzed. The permeation fluxes increased with feed temperature and velocity. The effect of feed bulk temperature on the boundary layers' heat transfer coefficients was shown and fairly discussed. The temperature polarization coefficient increased with feed velocity and decreased with temperature. The values obtained were 0.56 to 0.82, indicating the effective heat transfer of the system. The fouling was observed during the 90 h experimental run in the application of natural ground water and seawater. The time dependent fouling resistance can be added in the total transport resistance.

• 유통과학연구
• /
• 제12권1호
• /
• pp.35-46
• /
• 2014

Purpose - This Study aims to promote technology transfer commercialization and ultimately make contribution towards enhancement of the success rate of commercialization of technology transfer at national level by deducing the factors that impart influence on the negotiation at the time of technology trading between the seller and buyer of technology of public research institutions subjected to transfer and sales. Research design, data and methodology - This Study deduced 5 research hypotheses through preceding researches related to technology transfer commercialization related technology marketing for technology trading negotiation. This Study was conducted by verifying the hypotheses through multiple regression analysis. Results - As the result of the Study, the research hypothesis H1, 'Promotion of commercialization of technology transfer trading will be affected in accordance with the innate characteristic factors of the technology', and H5, 'Promotion of commercialization of technology transfer trading will be affected in accordance with the mutual factors of the parties of the technology trading', among the 5 research hypotheses were chosen. Conclusions - It was found that the technology seller must be able to demonstrate technological value of the technology being sold in order to successfully conclude technology transfer trading negotiation and mutual understanding and harmonious communication between the parties.

• 한국물환경학회지
• /
• 제26권6호
• /
• pp.1008-1015
• /
• 2010

Discharged pollution load is varied as rainfall changes in the area with combined sewer system. Changes in discharged pollution load are directly related with those of sewer transfer flow. Therefore, it is important to identify the pattern of sewer transfer flow for the analysis of changes in discharged pollution load. This study reviewed the type of distribution of sewer transfer flow for 17 sewage treatment plants and developed simple formular to estimate sewer transfer flow as rainfall changes. 11 facilities showed to have some relation with rainfall in the change of sewer transfer flow but 6 facilities to have no relation. Relationships between rainfall amount and sewer transfer flow showed that 6 facilities out of 11 had relatively strong relationships above R2=0.5, which were considered to be affected directly by rainfall changes. The formular which explain the relationship between rainfall and sewer transfer flow can be applied in the analysis of rainfall effects on discharged pollution load, therefore, the more appropriate evaluation will be done.