• 제목/요약/키워드: Transfer-related factor

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곡관부 하류에 핀휜이 부착된 회전 냉각유로의 최적설계 (Optimization of a Rotating Two-Pass Rectangular Cooling Channel with Staggered Arrays of Pin-Fins)

  • 문미애;김광용
    • 한국유체기계학회 논문집
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    • 제13권5호
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    • pp.43-53
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    • 2010
  • This study investigates a design optimization of a rotating two-pass rectangular cooling channel with staggered arrays of pin-fins. The radial basis neural network method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of fluid flow and heat transfer with shear stress transport turbulent model. The ratio of the diameter to height of the pin-fins and the ratio of the streamwise spacing between the pin-fins to height of the pin-fin are selected as design variables. The optimization problem has been defined as a minimization of the objective function, which is defined as a linear combination of heat transfer related term and friction loss related term with a weighting factor. Results are presented for streamlines, velocity vector fields, and contours of Nusselt numbers, friction coefficients, and turbulent kinetic energy. These results show how fluid flow in a two-pass square cooling channel evolves a converted secondary flows due to Coriolis force, staggered arrays of pin-fins, and a $180^{\circ}$ turn region. These results describe how the fluid flow affects surface heat transfer. The Coriolis force induces heat transfer discrepancy between leading and trailing surfaces, having higher Nusselt number on the leading surface in the second pass while having lower Nusselt number on the trailing surface. Dean vortices generated in $180^{\circ}$ turn region augment heat transfer in the turning region and in the upstream region of the second pass. As the result of optimization, in comparison with the reference geometry, thermal performance of the optimum geometry shows the improvement by 30.5%. Through the optimization, the diameter of pin-fin increased by 14.9% and the streamwise distance between pin-fins increased by 32.1%. And, the value of objective function decreased by 18.1%.

딤플 유로의 열전달 증진을 위한 최적화모델 비교 (Evaluation of Optimization Models for a Dimpled Channel to Enhance Heat Transfer)

  • 신동윤;김광용;압두스 사마드
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회B
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    • pp.2552-2557
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    • 2007
  • Shape optimization of an internal cooling passage with staggered dimples on single surface is performed and performances of surrogates are evaluated in this paper. Optimizations are performed so that turbulent heat transfer can be enhanced compromising with pressure loss due to friction. The three-dimensional governing differential equations have been solved to find the overall Nusselt number and friction factor which are related to the objective functions of this problem. Three design variables were selected among the dimensionless geometric variables. Basic surrogate models such as second order polynomial response surface approximation (RSA), Kriging meta-modeling technique, radial basis neural network (RBNN), and derived press based averaged (PBA) surrogate model are constructed. The optimal points are searched from the above constructed surrogates by sequential quadratic programming (SQP). It is shown that use of multiple surrogates can increase the robustness in prediction of better design with minimum computational cost.

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TRANSGENIC LIVESTOCK - Review -

  • Jin, D.I.;Petters, R.M.;Im, K.S.
    • Asian-Australasian Journal of Animal Sciences
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    • 제7권1호
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    • pp.1-17
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    • 1994
  • There are several gene transfer methods available to introduce foreign DNA into animal. The most common method at present is microinjection. However, the overall efficiency of producing practical application of gene transfer technology to livestock species is production of pharmaceuticals. Rare human proteins, which cannot be produced into milk of transgenic animals. Large amount of biologically active protein may be obtained from transgenic farm animals using this system. Growth-related application to livestock species using growth hormone genes or factor genes have been disappointing. There were many undesirable side effects noted in the transgenic animals. More sophisticated on or off transgene expression are needed to control expression of transgenes in the transgenic animals. Turning positive effects while circumventing potentially harmful effects.

상생형 현장실습교육을 통한 기업가정신과 창업가 역량 향상에 관한 연구: 새가게운동 사례 (The Study of the Increase of Entrepreneurship and Entrepreneurial Competency Thru Win-Win Type Field Study: New Store Movement Case)

  • 이유태;정대성;오윤석
    • 벤처창업연구
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    • 제11권1호
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    • pp.121-130
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    • 2016
  • 본 연구에서는 상생형 현장체험 창업교육의 일환인 새가게운동이 대학생 창업의도와 현장체험 대상기업인 소상공인 경영개선에 미치는 영향을 분석하였다. 본 연구의 주요 결과는 다음과 같다. 첫째, 새가게운동 체험이 기업가정신, 창업태도, 창업의도를 향상시키는 것으로 나타났다. 둘째, 기업가정신은 창업태도에, 창업태도는 창업의도에 정(+)의 영향을 미치는 것으로 나타났다. 셋째, 소상공인들의 창업가 역량(경영역량)과 기업가정신이 향상되고 이들의 향상은 재무적, 비재무적 성과에 유의한 정(+)의 영향을 미치는 것으로 나타났다. 본 연구의 시사점은 새가게운동과 같은 새로운 상생형 체험 프로그램이 참여한 대학생과 업주에게 양방향적으로 긍적적인 영향을 주고 있는 것이다. 따라서 창업교육에 있어서 세대별로 단절되는 것보다는 새가게운동과 같이 청장년이 같이 노력해서 그 결과가 상생적인 양방형 현장체험학습의 강화가 필요하다고 볼 수 있다.

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환자-교차 대조군 연구를 적용한 산업재해 발생의 단기적 영향 요인 (Transient Effects the Risk of Occupational Injuries as an Acute Events : a Case-crossover Study)

  • 정선아;원종욱;노재훈;이종태
    • Journal of Preventive Medicine and Public Health
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    • 제34권1호
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    • pp.35-40
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    • 2001
  • Objectives : To elucidate the transient effects on the risk of occupational injuries as acute events and establish so alternative proposal. Methods : The study population comprised a total of 302 workers randomly selected from applications for occupational injury compensation reported to the Inchon local labor office from January 1. 1999 to December 31. A case-crossover design, where each case serves its own control, was applied to this study. Through a telephone interview, workers provided useful data concerning five job related stressful events such as company transfer, work load change, overtime work, exchange duty, and work-part transfer. They were asked whether there were stressful events within a week of the occurrence of injury and the degree of stress. Exposure status from one year prior was used as control information. In the end, the data provided by 158 of selected persons was used for the analysis based on the quality of the data provided by the participants. A conditional logistic regression was used to discover the transient effects on the risk of occupational injuries as acute events. Results : The effects a company transfer and work load change on occupational injury was statistically significant on the risk of occupational Injuries as an acute event(RR=5.5, 95% CI=2.501-12.428; RR=3.1, 95% CI=1.963-5.017, respectively). Other stressful events were found to elevate the risk factor for the occurrence of occupational jujury, but were not significant. Conclusions : Our results suggested that transient stressful events elevated the risk factor for the occurrence of occupational injury.

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Whitening effect of novel peptide mixture by regulating melanosome biogenesis, transfer and degradation

  • Lee, Eung-Ji;Kim, Jandi;Jeong, Min Kyeong;Lee, Young Min;Chung, Yong Ji;Kim, Eun Mi
    • The Korean Journal of Physiology and Pharmacology
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    • 제25권1호
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    • pp.15-26
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    • 2021
  • Peptides are short chain of amino acids linked by peptide bonds. They are widely used as effective and biocompatible active ingredients in cosmetic industry. In this study, we developed novel peptide mixture and identified its anti-pigmentation effect on melanocytes and keratinocytes. Our results revealed that peptide mixture inhibited melanosome biogenesis through the regulation of microphthalmia-associated transcription factor, a key factor of melanogenesis in melanocytes. And we observed that peptide mixture inhibited melanosome uptake through the reduction of protease-activated receptor 2, a phagocytosis-related receptor in keratinocytes. Furthermore, peptide mixture activated autophagy system resulting in degradation of transferred melanosomes in keratinocytes. The anti-pigmentation effect of multi-targeting peptide mixture was assessed in a human skin equivalent model (MelanoDerm). Melanin contents in epidermal layer were significantly decreased by topical treatment of peptide mixture, suggesting that it can be applied as a novel cosmetics material having a whitening function.

회전하는 냉각유로의 곡관부에 부착된 가이드 베인의 형상 최적설계 (Shape Optimization of a Rotating Two-Pass Duct with a Guide Vane in the Turning Region)

  • 문미애;김광용
    • 한국유체기계학회 논문집
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    • 제14권1호
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    • pp.66-76
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    • 2011
  • The heat transfer and pressure loss characteristics of a rotating two-pass channel with a guide vane in the turning region have been studied using three-dimensional Reynolds-averaged Navier-Stokes (RANS) analysis, and the shape of the guide vane has been optimized using surrogate modeling optimization technique. For the optimization, thickness, location and angle of the guide vanes have been selected as design variables. The objective function has been defined as a linear combination of the heat transfer and the friction loss related terms with a weighting factor. Latin hypercube sampling has been applied to determine the design points as design of experiments. A weighted-average surrogate model, PBA has been used as the surrogate model. The guide vane in the turning region does not influence the heat transfer in the first passage upstream of the turning region, but enhances largely the heat transfer in the turning region and the second passage. In an example of the optimization, the objective function has been increased by 13.6%.

경제적 은퇴준비행동의 영향요인: 세대간 자산이전 요인을 중심으로 (Factors on Financial Preparation for Retirement: Focusing on Money Transfer between generations)

  • 정지영;양세정
    • 가족자원경영과 정책
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    • 제17권1호
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    • pp.199-219
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    • 2013
  • The purpose of the study was to investigate the effects of money transfer between generations on preparation behaviors for retirement, separated into assets and saving for retirement. The survey was conducted by targeting 422 married people across the nation. The factor of money transfer between generations was defined as the inheritance and gift variable. The data were analyzed using SPSS 20. Correlation, analysis of variance (ANOVA), and multiple regressions were utilized. The results indicated that preparation behaviors for retirement are affected by the economic independence of parents, inheritance, expenses for children's education, and marriage. Retirement assets were significantly affected by inheritance, the economic independence of parents, educational expenses for children, financial assets, and amount of debt, while the significant factors related to retirement savings were interests on retirement, income, wedding expenses for children, economic independence of parents, and educational expenses for children. It was concluded that the financial preparation for retirement ought to be expanded from one household's finances to finances between generations.

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비정상상태의 미세기포에 의한 산소 전달 특성 모사 (Simulation of non-steady state oxygen transfer caused by microbubble supply)

  • 이재엽;김일호
    • 상하수도학회지
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    • 제32권5호
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    • pp.381-388
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    • 2018
  • Microbubbles oxygen transfer to water was simulated based on experimental results obtained from the bubbles generation operated under varying liquid supply velocity to the multi-step orifices of the generator. It had been known that liquid supply velocity and bubble size are inversely related. In the oxygen transfer, a non-steady state was assumed and the pseudo stagnation caused the slow movement of bubbles from the bottom to the water surface. Two parameters were considered for the simulation: They represent a factor to correct the pseudo stagnation state and a scale which represented the amount of bubbles in supply versus time. The sum of absolute error determined by fitting regression to the experimental results was comparable to that of the American Society of Civil Engineers (ASCE) model, which is based on concentration differential as the driving force. Hence, considering the bubbles formation factors, the simulation process has the potential to be easily used for applications by introducing two parameters in the assumptions. Compared with the ASCE model, the simulation method reproduced the experimental results well by detailed conditions.

신경회로망기법을 사용한 타원형 딤플유로의 냉각성능 최적화 (Optimization of a Cooling Channel with Staggered Elliptical Dimples Using Neural Network Techniques)

  • 김현민;문미애;김광용
    • 한국유체기계학회 논문집
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    • 제13권6호
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    • pp.42-50
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    • 2010
  • The present analysis deals with a numerical procedure for optimizing the shape of elliptical dimples in a cooling channel. The three-dimensional Reynolds-averaged Navier-Stokes (RANS) analysis is employed in conjunction with the SST model for predictions of the turbulent flow and the heat transfer. Three non-dimensional geometric design variables, such as the ellipse dimple diameter ratio, ratio of the dimple depth to the average diameter, and ratio of the distance between dimples to the pitch are considered in the optimization. Twenty-one experimental points within design space are selected by Latin Hypercube Sampling. Each objective function values at these points are evaluated by RANS analysis and producing optimal point using surrogate model. The linear combination of heat transfer coefficient and friction loss related terms with a weighting factor is defined as the objective function. The results show that the optimized elliptical dimple shape improves considerably the heat transfer performance than the circular dimple shape.