• Title/Summary/Keyword: cheY

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The BMAP/G/1Queue with Correlated Flows of Customers and Disasters

  • Kim, Che-Soong
    • Journal of Korea Society of Industrial Information Systems
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    • v.10 no.2
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    • pp.42-47
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    • 2005
  • A single-server queueing model with the Batch Markovian Arrival Process and disaster ow correlated with the arrival process is analyzed. The numerically stable algorithm for calculating the steady state distribution of the system is presented.

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An Experimental Study on the heat transfer characteristics and performance of storage tanks with mantle heat exchanger (맨틀형 축열조의 열전달 성능 및 특성에 관한 실험적 연구)

  • Kang, Y.H.;Kwak, H.Y.;Yoon, H.G.;Yoo, C.G.;Yoon, H.S.;Chun, W.G.
    • Journal of the Korean Solar Energy Society
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    • v.21 no.1
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    • pp.61-69
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    • 2001
  • The heat transfer characteristics of horizontal and vertical mantle heat storage tanks are studied in order to replace the tank-coil heat exchanger for application in thermosyphon solar water heaters. In this study, 5 mantle storage tanks with different geometric shape are manufactured into stainless steel and each tank is tested. For the test, The inlet flow rate of the heat transfer fluid is maintained 1.2 lpm consistently. The heat transfer fluid temperature through the mantle is $70{\pm}1^{\circ}C$. The temperatures of 26 points included the ambient temperature are measured at every one minute. The measured data are used to calculate the overall heat transfer coefficient(UA) using the LMTD(Log Mean Temperature Difference) method and it is used on the analysis of the heat transfer characteristics to search for optimum arrangement.

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Development of Molecular Simulation Software for the Prediction of Thermodynamic Properties (열역학 물성 예측을 위한 분자 시뮬레이션 소프트웨어의 개발)

  • Chang, Jaee-On
    • Korean Chemical Engineering Research
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    • v.49 no.3
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    • pp.361-366
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    • 2011
  • By using Monte Carlo simulation method we developed a new molecular simulation software which can be used to predict the thermodynamic properties of organic compounds. Starting from molecular structure and intermolecular potential function, rigorous statistical mechanical principles give a probability distribution for the behavior of a system containing many molecules, which enables us to calculate macroscopic thermodynamic properties of the system. The software developed in this work, cheMC, is based on Windows platform providing with easy access. One can efficiently administrate simulations by using an intuitive interface equipped with visualization tool and chart generation. It is expected that molecular simulations supplement the equation of state approach and will play a more important role in the study of thermodynamic properties.

A Study on Modeling of Spatial Land-Cover Prediction (공간적 토지피복 예측을 위한 모형에 관한 연구)

  • 김의홍
    • Spatial Information Research
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    • v.2 no.1
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    • pp.47-51
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    • 1994
  • The purpose of the study is to establ ish models of land Cover (use) prediction system for development and management of land resources using remotely sensed data as well as ancillary data in the context of multi-dis¬ciplinary approach in the application to CheJoo Island. The model adopts multi-date processing techniques and is a spatial/temporal land-Cover projection strategy emerged as a synthesis of the probability tra-nsition model and the discrimnant-analys is model. A discriminant modelis applied to all pixels in CheJoo landscape plane to predict the most likely change in land Cover. The probability transition model provides the number of these pixels that will convert to different land Cover in a given future time increment. The syntheric model predicts the future change in land Cover and its volume of pixels in the landscape plane.

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Study on the Optical Performance of Evacuated Solar Collectors (진공복사관식 집열기의 성능실측 및 최적화 연구)

  • Chun, Won-Gee;Kang, Sang-Hoon;Kim, Ki-Hong;Lee, Yong-Kuk;Chang, Rae-Woong
    • Journal of the Korean Solar Energy Society
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    • v.21 no.4
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    • pp.63-71
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    • 2001
  • This work has been carried out to find the ideal operating conditions for solar vacuum tube collectors which are widely used at present. Various types of solar collectors including a flat plate one were experimentally tested and examined to determine their thermal efficiencies and operating characteristics. Generally, solar vacuum tubes can be classified into two groups according to their design features. Of these, one is characterized by the insertion of a metallic device(such as a finned heat pipe) in an evacuated glass tube for the collection and transportation of solar energy. The other utilizes double glass tubes where the smaller one is contained inside the bigger one and soldered to each other after the small gap between them is evacuated. Both of these solar collectors are designed to minimize convection heat losses by removing the air which is in direct contact with the absorber surface. The performance of the former type can be readily analyzed by applying the relevant correlations developed for flat plate solar collectors. This has been demonstrated in the present study for the case of a solar collector where a heat pipe is inserted in an evacuated tube.

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A study on the degree of perceived powerlessness of the elderly (노인의 무력감 지각 정도에 관한 연구)

  • Park, In-Hyae;Lee, Jeong-Hee;Kang, Ki-Sun;Kwon, Hye-Jin;Kim, Kyung-Hee
    • Research in Community and Public Health Nursing
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    • v.8 no.1
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    • pp.61-73
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    • 1997
  • The purpose of this study was to identify the degree of perceived powerlessness and the factors which influence the powerlessness of the elderly. Data were collected by self-reported structured questionnare from 210 subjects living in Kwang-Ju and Che-Ju cities on 5th to 17th February 1996. Data were analyzed using statistical package SAS. The findings were as follows : 1. The mean scores of the degree of perceived powerlessness of the subjects were 58.90 out of 85. The elderly people in Kwang-Ju city perceived more powerlessness than elderly people of Che-Ju city. 2. The factors which influence the powerlessness of the elderly were age, gender, education level, living standard, spouse, former and present job, health condition, family support, social and recreational activities. From the results of this study, to alleviate the powerlessness of the elderly, with the efforts of health maintenance and promotion various community based social activities and support system should be developed for the elderly.

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The Effect of Interpersonal Relationships and Communication Curriculum (인간관계와 의사소통 교과목의 효과 측정)

  • Hyun, Mi-Yeul;Park, Eun-Ok
    • The Journal of Korean Academic Society of Nursing Education
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    • v.14 no.1
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    • pp.5-11
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    • 2008
  • Purpose: The purpose of this study was to identify the effects of interpersonal relationships and communication curriculum on interpersonal relations and self-esteem. Method: This study employed a two-group pre-post test study design. Data was collected from 70 subjects from April to June, 2006 at C university in Jeju, Korea. Forty subjects were in the control group and 30 subjects were in the experimental group. A structured curriculum was conducted for the experimental group once a week for 12 weeks, but not for the control group. For both groups the scores of interpersonal relations and self-esteem were measured before and after the curriculum. Data was analysed by $X^2$-test, t-test, paired t-test and Pearson correlation with SPSS. Results: The scores of interpersonal relations and self-esteem significantly increased in the experimental group. There were significant positive correlations between interpersonal relationships and self-esteem. Conclusion: In light of these results, interpersonal relationships and communication curriculum have a positive effect on interpersonal relations and self-esteem. Therefore, this study can provide basic data and direction in developing and applying a curriculum in education.