• Journal of the Korean Society of Safety
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• v.11 no.2
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• pp.52-59
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• 1996

This paper presents a new approach for assessing the dynamic reliability in a complex system such as a nuclear power plant. The method is applied to a dynamic analysis of the potential accident sequences which may occur during mid-loop operation. Mid-loop operation is defined as an operation to make RCS water level below the top of the flow area of the hot legs at the junction with the reactor vessel for repairs and maintenance of steam generators and reactor coolant pumps for a specific time. The Idea behind this approach consists of both the use of the concept of the performance achievement/requirement correlation and of a dynamic event tree generation method. The assessment of the system reliability depends on the determination of both the required performance distribution and the achieved performance distribution. The quantified correlation between requirement and achievement represents a comparison between two competing variables. It is demonstrated that this method is easily applicable and flexible in that it can be applied to any kind of dynamic reliability problem.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1514-1522
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• 2010

This paper dealt with the HVDC concept design of Cheju HVDC #2, which will be operated at 2011. The concept design is the first step of HVDC design procedures and the contents which were presented in this paper, are HVDC operation conditions based on the reliability of HVDC and AC network conditions, short circuit ratios(SCR) to related to HVDC stability and overvoltage and interactions between AC network including FACTS and generators, and HVDC system. The results of this paper are a keystone of HVDC #2 design.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.4
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• pp.328-333
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• 2013

Since a slight malfunction of control systems in a nuclear power plant may cause huge catastrophes, such control systems usually have multiple redundancy and reliable features, and their reliability and availability should be analyzed and verified thoroughly. This paper performed the reliability analysis of the SPLC (Safety Programmable Logic Controller) that is under developed as the control systems for the next generation nuclear power plant. One of the key features of SPLC is that it has multiple redundancy modes as faults happen, which means the reliability analysis for one fixed redundant model is not enough to analyze the reliability of SPLC. With considering this reconfigurable concept, FTA (Fault Tree Analysis) was used to capture fault-relationship among sub-modules. The analysis results show that MTTF (Mean Time to Fault) of SPLC is 45,080 hours, which is a about 4.5 times longer than the regulation, 10,000 hours.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.10a
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• pp.240-247
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• 1993

The precise prediction of reserved carrying capacity of bridge as a system is extremely difficult especially when the bridges are highly redundant and significantly deteriorated or damaged. This paper is intended to propose a new approach for the evaluation of reserved system carrying capacity of bridges in terms of equivalent system-strength, which may be defined as a bridge system-strength corresponding to the system reliability of the bridge. This can be derived from an inverse process based on the concept of FOSM form of system reliability index. It may be emphasized that this approach is very useful for the evaluation of the deterministic system redundancy and reserve strength which are measured in terms of either probabilistic system redundancy factor and reserve factor or deterministic system redundancy factor and reserve factor. The system reliability of bridges is formulated as a parallel-series model obtained from the FAM(Failure Mode Approach) based on the major failure mechanisms. AFOSM and IST methods are used for the reliability analysis of the proposed models. The proposed approach and method for the system redundancy and reserve safety/strength are applied to the safety assessment of actual RC and steel box-girder bridges. The results of the evaluation of reserved system safety or bridge system-strength in terms of the system redundancy and the system safety/strength are significantly different from those of element reliability-based or conventional methods.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.3
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• pp.222-235
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• 2018

The hydrocarbon gas leak in the offshore plant can cause large accidents and lead to significant damages to human, property and environment. For prevention of fire or explosion accidents from gas leak, a SIS(Safety Instrumented System) should be installed. In the early stage of the offshore design, required SIL(Safety Integrated Level) is determined and reliability analysis is performed to verify the design in reliability aspects. This study collected data, information related to reliability analysis and created knowledge model of safety design for the offshore system with MBSE(Model-Based Systems Engineering) concept. Knowledge model could support safety engineer's design tasks as the guidance of reliability analysis procedure of safety design and make good conversation with other engineers in yard, class, company, etc.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.584-589
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• 2006

In this paper, a test apparatus for reliability evaluation of a rotary compressor has been suggested with a short-cycle concept. $CO_2$ refrigerant is adopted for this cycle to avoid phase change during cycle operation. Evaporator is not necessary in short-cycle. Utilizing a short-cycle, the test apparatus was built on the purpose of evaluating the reliability of each rotary compressor on the conveyer belt of the factory. The primary validation of the test apparatus is discussed by analyzing the experimental heat balance data. Additional validation was performed through the overload continuous operation test where the wear rate of the $CO_2$ short-cycle was found to similar to that of the R22 normal-cycle. The reliability evaluation test apparatus with a short-cycle in present investigation was found simple and efficient in the view of reducing sample numbers, costs, and test time in analyzing the reliability of rotary compressors.

• The Mathematical Education
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• v.54 no.4
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• pp.317-334
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• 2015

In this article we study structure of the concept of creative products in mathematics using mathematical creative products. We develop MCPSS1 that improve reliability and validity of MCPSS(Creative Product Semantic Scale in Mathematics). And we search structure of the concept of creative products in mathematics using mathematical creative products focused on theoretical investigation. So we suggest structure model of the concept of creative products focused on theoretical investigation. We compare the result with preceding research using various mathematical creative products, find some difference between relations of sub-factors of structure of the concept of creative products. Our result will provide meaningful data to mathematics education researchers that want to know structure of the concept of creative products in mathematics.

• Journal of The Korean Association For Science Education
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• v.36 no.3
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• pp.509-517
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• 2016

Previous studies have investigated the similarity between the development of evolutionary explanations and students' conceptual developments on evolution. However, the validity and reliability of the assessment method reflecting the similarity have not been quantitatively examined yet. In addition, no study has examined the conceptual progressions of evolution concept based on contexts although literature has addressed the contextual difference of evolutionary explanation in the history of science. This study examined the validity and reliability of history-of-science-based evolution concept assessment using ordered multiple choice (OMC) methods and Rasch analysis and explored conceptual progression by three contexts (e.g., human, animal, and plant). The evolution concept assessment developed by Ha (2007) was used to examine 1711 elementary, middle, and high school students, and pre- and in-service science teachers' (biology majors and non-majors) evolution concepts. Internal consistency reliability and item response fitness of the OMC method that provide 0- to 4-point scores to creationism, teleology, intentionality, use/disuse, and natural selection respectively met the benchmark based on the Cronbach alpha and MNSQ indices of Rasch analysis. The level of elementary and middle school students' evolution concepts were located between intentionality and use/disuse while the level of high school and non-biology science teachers' evolution concepts were located between use/disuse and natural selection. The conceptual progressions of evolution concepts were differentiated according to three contexts. This study provided the quantitative evidence for the similarity between the development of evolutionary explanations and students' conceptual developments on evolution and suggest new analysis methods (i.e., OMC) of evolution concept assessment.

• Journal of Korean Public Health Nursing
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• v.4 no.2
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• pp.5-13
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• 1990

The purpose of this study was to investigate physical self concept between high school boys and girls and to find various factors affecting them. For the Survey, 331 respondents for boys and 347 for girls were randomly selected from one coeducational high school in Seoul, from May 16 to May 19, 1990. The instrument used in this questionaire survey method was a part of Won Shik Jung's Physical Self Concept Scale for measuring Self Concept, it's reliability was' Cronbach a = 0.718. For the analysis. descriptive statistics were used by calculating frequencies, percentages and mean scores. $X^2-test$, t-test, and analysis of variance were employed to test the differences and statistical significance. The relationship between physical self concept and area variables was analysed by use of Pearson's correlation coiefficients. For the examine of various factors affecting physical self concept, multiple stepwise regression method was employed. The results of this study are summarized as follows: 1. There was no significant difference in physical self concept between male and female students. 2. The scores of physical self concept among the students were negatively correlated with their academic year, even though statistical signification was not found. 3. Physical self concept was classified into two areas; health area and appearance area. There was no significant difference in health area between boys and girls. But, the difference of health area was significant in accordance with the academic years. That, the scores of the health area are dropped as academic year going up. 4. Significant relationship was revealed among health area, appearance area, and physical self concept. The correlation between health area and physical self concept was the highest relationship (r = 0.71) The main factors affecting the physical self concept were (1) father's educational background (2) year (3) number of brother (4) religion (5) father's age. 5. As academic year going up, the rate of counseling with parents are dropped. In conclusion, the result of the study indicate that, a person managed the school health and parents can help students to promote their physical, mental, and emotional health by means of health education and counseling.

• Child Health Nursing Research
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• v.4 no.1
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• pp.105-115
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• 1998

The purpose of the study was to test the reliability and validity of the Korean version of Children's Health Locus of Control Scale (CHLC), an instrument designed to measure health locus of control in children aged 7 to 12. The scale was administered to 467 children in grades 4 to 6, enrolled in 2 elementary schools located in city. The mean age of the subject was 10.03 (SD=1.33). The findings were as follows: 1. Cronbach alpha coefficient for internal consistency was .69 for the total, and .67, .65, and .56 on the respective subscales. 2. Construct validity was supported through factorial isolation of three theory consistent subscales : internal, chance, and powerful others. Two items did not fit well with the originally developed subscale. The total percent of varience explained by 3 factors was 34.5%. The result of the factor analysis according to Kaiser's criterion revealed that the scale was consisted of 5 factors. But, The items of the subscales were rather inconsistent with the dimensions of the locus of control concept. 3. There were significant differences according to parent's educational level and occupation, and birth order on the scores of the CHLC. There were no significant differences according to grade level and sex. 4. The score of the CHLC was significantly correlated with the self concept of the children(r=.14, p<.001). The result indicated that the Korean version of Children's Health Locus of Control Scale was valid and reliable in measuring health locus of control concept in children, even though luther research is required to reconfirm and increase the reliability of the instrument. CHLC could be used for study explaining the health related behavior of the children and research project related to health education program.