• Title/Summary/Keyword: Hypothetical Model

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NUMERICAL METHOD FOR EVALUATION OF HYDROGEN FLAME ACCELERATION IN A COMPARTMENT OF A NUCLEAR POWER PLANT (원자력발전소 격실에서의 수소화염 가속에 대한 수치해석 연구)

  • Kim, Jong-Tae;Kim, Sang-Baik;Kim, Hoo-Joong
    • Journal of computational fluids engineering
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    • v.15 no.4
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    • pp.67-75
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    • 2010
  • Hydrogen safety is one of important issues for future public usage of hydrogen. When hydrogen is released in a compartment, the occurrence of detonation must be prohibited. In order to evaluate the possibility of DDT (Deflagration to Detonation Transition) in the compartment with the hydrogen release, sigma-lambda criteria which were developed from experimental data are commonly used. But they give a little conservative results because they do not consider the detailed geometrical effect of the compartment. This is the main reason of the need to mechanistic combustion model for evaluation of hydrogen flame propagation and acceleration. In this study, sigma-lambda criteria and combustion model were systematically applied to evaluate a possibility of DDT in a IRWST compartment of APR1400 nuclear power plant during a hypothetical accident. A combustion model in an open source CFD code OpenFOAM has been applied for analyses of hydrogen flame propagation. The model was validated by evaluating the flame acceleration tests conducted in FLAME facility. And it was applied to evaluate the characteristics of a hydrogen flame propagation in the IRWST compartment of APR1400.

A Structural Model Development on the Cardiovascular Disease Risk Factors among Male Manufacturing Workers (제조업 남자 근로자의 심혈관질환 위험요인에 대한 모형 구축)

  • Choi, Eun-Sook
    • Research in Community and Public Health Nursing
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    • v.17 no.2
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    • pp.153-165
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    • 2006
  • Purpose: The purpose of this study was to develop and test a structural model on cardiovascular disease risk factors among male manufacturing workers. Methods: Data were collected through questionnaires and health exams from 201 workers in a local electronic company during September 2004. Data analysis was done with SAS 9.1 for descriptive statistics and PC-LISREL 8.54 for covariance structural analysis Results: The overall fit of the hypothetical model to the data was moderate, it was modified by deleting five paths. The modified model had a better fit to the data($x^2=504.23$(p<001, df: 180), $x^2/df=2.80$, GFI=.95, RMR=.07, NFI=.90, PGFI=.64). Health behaviors and psychosocial distress were found to have significant direct effects on the cardiovascular disease risk factors. Self-concept had direct effect on psychosocial distress or health behaviors. Self-concept, work environment, and work condition had direct effect on social support. Work environment had indirect effect on psychosocial distress. Social support had indirect effect on health behaviors. But work environment and work condition were found to have little direct effect on health behaviors, psychosocial distress or cardiovascular disease risk factors. Conclusion: A cardiovascular health promotion program should therefore include psycho-social factors as well as health behavioral determinants in worksites.

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The Effect of Meteorological Information on Business Decision-Making with a Value Score Model (가치스코어 모형을 이용한 기상정보의 기업 의사결정에 미치는 영향 평가)

  • Lee, Ki-Kwang;Lee, Joong-Woo
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.30 no.2
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    • pp.89-98
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    • 2007
  • In this paper the economic value of weather forecasts is valuated for profit-oriented enterprise decision-making situations. Value is estimated in terms of monetary profits (or benefits) resulted from the forecast user's decision under the specific payoff structure, which is represented by a profit/loss ratio model combined with a decision function and a value score (VS). The forecast user determines a business-related decision based on the probabilistic forecast, the user's subjective reliability of the forecasts, and the payoff structure specific to the user's business environment. The VS curve for a meteorological forecast is specified by a function of the various profit/loss ratios, providing the scaled economic value relative to the value of a perfect forecast. The proposed valuation method based on the profit/loss ratio model and the VS is adapted for hypothetical sets of forecasts and verified for site-specific probability of precipitation forecast of 12 hour and 24 hour-lead time, which is generated from Korea meteorological administration (KMA). The application results show that forecast information with shorter lead time can provide the decision-makers with great benefits and there are ranges of profit/loss ratios in which high subjective reliability of the given forecast is preferred.

A Structural Equation Model on Health Behavior Adherence for Elders with Prehypertension: Based on Self-Determination Theory (자기결정성 이론에 근거한 고혈압 전단계 노인의 건강행위이행 구조 모형)

  • Lee, Eun-Ha;Park, Jee-Won
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.19 no.3
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    • pp.343-352
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    • 2012
  • Purpose: The purpose of this study was to develop and test a hypothetical model which explains health behavior adherence in elderly people with prehypertension. The model was based on self-determination theory (SDT). Methods: Data were collected from June 21 to July 15, 2010, using self-report questionnaires. The participants were 140 elders with prehypertension who lived in D Metropolitan City. Collected data were analyzed using PASW 18.0 for descriptive statistics and correlation analysis and AMOS 5.0 for covariance structure analysis. Results: It appeared that the overall fit index was good with a ${\chi}^2$ score of 13.23 (p<0.05), GFI of 0.97, AGFI of 0.79 and RMR of 0.28 in the modified model. The results revealed that significant main effects of both health provider's autonomy support and autonomous motivations were found on the measure of health behavior adherence. These factors explained 72% of variance in the participants, health behavior adherence. Conclusion: The overall findings may provide useful assistance in developing effective motivation-enhanced programs for health behavior adherence.

Analysis of Decision-Making in Ethical Dilemma Cases among Clinical Nurses (윤리적 딜레마 사례에 대한 간호사의 의사결정 분석)

  • Kim, Hyun-Gyung
    • Journal of Korean Academy of Nursing Administration
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    • v.9 no.3
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    • pp.459-480
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    • 2003
  • Purpose: This study was done to analyze the contents of nurses' ethical decision-making in four of hypothetical dilemma cases using the Cameron's Ethical Decision-Making Model of 'Value, Be, Do'. Method: Sixteen nurses who work at ICU at present or worked before, participated from April 10 to May 10 in 2002. The participants were interviewed three times each and for 40 minutes at once, with a structured questionnaire at their working places and locker rooms. The data was analyzed by a procedure of qualitative content analysis into three categories; what should I value, who should I be, what should I do. Result: 1) In consistency, most of subjects showed a unified voice in 'Value, Be, Do'. Exceptionally 8 subjects showed inconsistency such as 3 in active treatment to the incurable patients(case 1), 1 in treatment truth-telling to the terminally ill patients(case 2), 3 in conflict with uncooperative doctors(case 3), 3 in dying patients and euthanasia(case 4). Only one subject showed inconsistency in 3 dilemma cases. 2) Closing the interview procedure, the subjects evaluated Cameron's Model as it would help them build consistent value, carry right action, and cope to conflicts. Conclusion: On the basis of the results, it is recommended that nursing ethics should adopt the ethical decision-making model, and be applied to the curriculum of nursing colleges and continuing education program for clinical nurses.

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A study on hypothetical switching software through of the analysis of failure data (고장 데이터 분석을 통한 교환 소프트웨어 특성 연구)

  • 이재기;신상권;이영목
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.23 no.8
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    • pp.1915-1925
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    • 1998
  • The switching system software is large scale, real-time multi-task system which requires high reliability. The reliability assessment of large-scale software is very important for the success of software development project. For this raeson, the software quality measurement is much more important. In this paper, we have learned about the software reliability, metho of the analysis of failure data and estimation of software quality. To estimate the software reliability, using the failure data found during of the system test. We apply the two software reliability growth models, named Goel-Okumoto(G-O) and S-shaped model, to estimate the software reliability. Also, we compared with the results and we reviewed fully not only development cycle but validation and verification of the test data, for each software versions. This paper presents a software reliability model that suitale the software development project and the activeity of quality control for the switching system.

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Analysis of Burnout and Job Satisfaction among Nurses Based on the Job Demand-Resource Model (직무요구-자원모형에 의한 간호사의 소진과 직무만족 분석)

  • Yom, Young-Hee
    • Journal of Korean Academy of Nursing
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    • v.43 no.1
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    • pp.114-122
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    • 2013
  • Purpose: The purpose of this study was to examine burnout and job satisfaction among nurses based on Job Demand-Resource Model. Methods: A survey using a structured questionnaire was conducted with 464 hospital nurses. Analysis of data was done with both SPSS Win 17.0 for descriptive statistics and AMOS 18.0 for the structural equation model. Results: The hypothetical model yielded the following Chi-square=34.13 (p=<.001), df=6, GFI=.98, AGFI=.92, CFI=.94, RMSR=.02, NFI=.93, IFI=.94 and showed good fit indices. Workload had a direct effect on emotional exhaustion (${\beta}$=0.39), whereas supervisor support had direct effects on emotional exhaustion (${\beta}$=-0.24), depersonalization (${\beta}$=-0.11), and low personal accomplishment (${\beta}$=-0.22). Emotional exhaustion (${\beta}$=-0.42), depersonalization (${\beta}$=-0.11) and low personal accomplishment (${\beta}$=-0.36) had significant direct effects on job satisfaction. Conclusion: The results suggest that nurses' workload should be decreased and supervisor's support should be increased in order to retain nurses. Further study with a longitudinal design is necessary.

Structural Equation Model for Job Stress in Intensive Care Unit Nurses (중환자실 간호사의 직무 스트레스 관련 변인들 간의 구조모형 분석)

  • Jin, Su Jin;Lee, Ji Hyun
    • Korean Journal of Occupational Health Nursing
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    • v.24 no.2
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    • pp.103-113
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    • 2015
  • Purpose: This study was to construct a structural equational model for explaining and predicting job stress of intensive care unit (ICU) nurses based on the Integrated model of stress of Ivancevich and Matteson (1980). Methods: The subjects of this study were 220 nurses at ICU. The data were collected from August 5 to 30, 2013 through self-reporting questionnaire survey. Results: According to the hypothetical model of this study, perceived nursing practice environment, perceived role conflict, perceived transformational leadership and perceived self-esteem showed statistically significant effects on job stress of ICU nurses directly. Professional self-concept indirectly affect job stress of ICU nurses. In conclusion, job stress of ICU nurses was directly influenced by nursing practice environment, role conflict, transformational leadership and self-esteem. Professional self-concept of the relationships among variables did not have a direct impact on job stress. Conclusion: Based on the results of this study, it is needed to develop stress management measures and programs considering these variables in order to adequately manage job stress of ICU nurses.

Performance Design Techniques for Scramjet Engines with Finite-rate Chemistry Combustion Models (유한화학반응 연소 모델을 고려한 스크램제트 엔진의 성능설계 기법)

  • Kim, Sun-Kyoung;Seo, Bong-Gyun;Kim, Sung-Jin;Sung, Hong-Gye;Byen, Jong-Ryul;Yoon, Hyun-Gull
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.401-405
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    • 2010
  • An efficient performance model for scramjet engines has been proposed for scramjet performance design. In supersonic air intake design, the compression angles of the wedge were determined to maximize the total pressure recovery of the intake based on Oswatisch criterion. Both combustion models of chemical equilibrium and finite-rate chemistry model are implemented, and compared each model with the results by Starkey for Waverider engine configuration. Finally, the performance model of concern has been confirmed by conducting performance analysis with hypothetical mission profile and design conditions.

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Development of Analytic Model for Determinants on the Stages of Change in Colorectal Cancer Screening (대장암검진 수검 결정요인 분석모형 개발)

  • Kye, Su-Yeon;Moon, In-Ok
    • Korean Journal of Health Education and Promotion
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    • v.27 no.2
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    • pp.79-93
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    • 2010
  • Objectives: This study aims to identify the factors associated with the stages of change in colorectal cancer screening, and develop a model explaining these stages of change by using structural equation modeling analysis. Methods: On the basis of literature review and expert advice, we constructed our hypothetical model that consisted of five theoretical constructs(process of change, pros, cons, self-efficacy, stage of change). In 2009, data was collected from 486 participants aged between 50 and 69. The data were analyzed by SPSS 15.0 and AMOS 6.0. Results: In the case of stage of adoption, the contemplation stage was the most common (37.4%), followed by the action stage (26.5%). In the final model of the stage of change for colorectal cancer screening, there was a direct influence of the process of change ($\gamma$=.562, p<.001), and cons ($\gamma$=.132, p<.01) on the stage of change with the terms of GFI .931, AGFI .904, RMR .038, NFI .930, and NNFI .936. Conclusion: It is necessary to produce and disseminate evidence-based cancer screening information, which can mitigate the negative attitude among the public toward cancer screening. Also, it is essential to provide a safer and more comfortable environment at cancer screening center.