• Title/Summary/Keyword: t-analysis

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Effect of Finite Element Model on the Integrity Evaluation of Nuclear Piping (유한요소 해석모델이 원자력 배관의 건전성 평가에 미치는 영향)

  • Huh, Nam-Su;Kim, Young-Jin;Pyo, Chang-Ryul;Yu, Young-Jin
    • Journal of the Korean Society of Safety
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    • v.15 no.2
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    • pp.51-58
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    • 2000
  • Recently, the J/T analysis based on elastic-plastic finite element analysis is popularly used in the nuclear industry to assess the integrity of a cracked pipe. The objective of this paper is to evaluate the effect of stress-strain curve for weld metal, variation of crack incremental length(${\delta}a$), and crack face pressure on the J/T analysis result. For this purpose, a parametric analysis was performed and the results calculated from finite element analysis were compared with those from the piping experimental data(stainless steel weldment pipe with circumferential through-wall crack). The numerical result using base metal material property is in agreement with the experimental one and the maximum load is decreased as the ${\delta}a$ for J/T analysis is increased.

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Analysis on the Type of S&T Knowledge Expert Network : A Case Study of the Global Network of Korean Scientists & Engineers (과학기술 지식전문가 정책 네트워크 유형분석 : 한민족과학기술자 네트워크(KOSEN)를 중심으로)

  • Jeong, Yion-Il;Lee, Joo-Young;Yoon, Jung-Sun
    • Journal of Information Management
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    • v.36 no.4
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    • pp.199-215
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    • 2005
  • Experts participating in the knowledge expert network externalize their implicit knowledge by providing information or writing reports. Almost all the members of the network share externalized knowledge and the network facilitate the dissemination and diffusion of knowledge. Individuals reproduce another implicit knowledge by internalizing shared knowledge through the network and re-created knowledge is externalized, establishing knowledge circulation. In this paper, we analyze the expert groups of the Global Network of Korean Scientists & Engineers(KOSEN, www.kosen21.org), the Korea's No. 1 science and engineering knowledge expert community, with the application of the theory of policy network proposed by Marsh & Rhodes. According to the principal standards of policy network classification such as the number of participants, interaction among participants, consistency, distribution of resources and dependency, we categorize the KOSEN expert groups as closed policy network and opened issue network, and divide closed policy network into core community and periphery community.

Ku Band Antenna G/T Analysis and Experiment According to Elevation Angle Change (앙각변동에 따른 Ku 밴드 안테나 G/T 분석 및 실험)

  • Lee, Kyung-Soon;Koo, Kyung-Heon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.7
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    • pp.550-559
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    • 2017
  • In order to maintain communication while the vehicle is moving, satellite azimuth angle and elevation angle correction are needed in real time. The elevation angle correction affects the system G/T according to the variation of the external noise temperature flowing into the antenna. G/T is expressed as a ratio of power gain G to noise temperature T and is an important performance function required for antenna gain design. This paper aims to G/T analysis considering elevation angle change and the establishment of an antenna design procedure. For this purpose, the relationship between elevation angle and brightness temperature including rain attenuation was analyzed according to recommendation ITU-R P.372 radio noise. Next, an antenna was designed based on the analysis results and design procedure was verified by G/T measurement. Through this experiment, G/T according to elevation angle was confirmed, and the minimum antenna gain analysis and design procedure required in the system could be established.

The Relationship between Personality Traits and Job Preference in Foodservice Industry (외식 산업 종사자의 성격 특성과 직업 선호도와의 관계)

  • Kim, Doo-Ra;Kang, Jae-Ho
    • Culinary science and hospitality research
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    • v.13 no.4
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    • pp.67-79
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    • 2007
  • This study verified the relationship between the personality traits and the job preference in the foodservice industry. Questionnaire was held with targeting to the persons who engage in the foodservice industry, especially restaurants located in Seoul and Gyeonggi Province. Factor analysis, regression analysis, t-analysis and dispersion analysis were carried out as the methodology of this study to analyze the relation with the Big Five Theory of Personality, which includes agreeableness, conscientiousness, extraversion, openness to experience, and neuroticism and job preference. As a result, conscientiousness, openness to experience and neuroticism were founded as the meaningful factors of effect on the job preference. In order to promote the job preference in the foodservice industry, engagement of employees who have suitable personality traits should be considered as an important issue in result of this study.

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Correlative Changes between Photosynthetic Activities and Chlorophyll Fluorescence in Wheat Chloroplasts Exposed to High Temperature

  • Young-Nam Hong
    • Journal of Plant Biology
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    • v.37 no.1
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    • pp.37-42
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    • 1994
  • Correlative changes between photosynthetic O2 exchange rates and room temperature Chl fluorescence were investigated in wheat (Triticum aestivum L.) chloroplasts treated with high temperature for 5 min. With increasing treatment temperature, photosynthetic O2 evolution rate mediated by PSII was decreased, showing 50% inhibition at 38$^{\circ}C$ (I50). But PSI activity measured by O2 uptake rates was stimulated as a function of increasing temperature. Dark level fluorescence (Fo)-temperature (T) analysis showed that fluorescence rising temperature (Tr), critical temperature (Tc), and peak temperature (Tp) was 38, 43, and 52$^{\circ}C$, respectively. Quenching analysis of Chl fluorescence showed that both the oxidized fraction of plastoquinone (qQ) and degree of thylakoid membrane energization (qNP) increased up to 4$0^{\circ}C$ and then declined dramatically. These results suggest that Tr is correlated with temperature showing a 50% of inhibition of photosynthesis and under mild high temperature stress, qNP is worth regarding as indicator for heat-induced damage of photosynthesis.

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A study of an analysis into effects and relations on learning performance from e-learning (이러닝 학습성과에 미치는 영향 관계 분석에 관한 연구)

  • Kwon, Yeongae;Lee, Aeri
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.16 no.2
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    • pp.69-81
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    • 2020
  • The objective of this study is to seek ways to maximize learning effects from e-learning by drawing improvement directions through investigating and analyzing an awareness of e-learning among e-learning attendees. The study was conducted among the attendees who are taking the e-learning program operated by K University and collected data from the students taking second semester in 2018 with the use of structured questionnaires. For data processing, SPSS Statistics 22.0 and AMOS were used, along with such analytical methods as frequency anslysis, descriptive statistical analysis, ANOVA (Analysis of Variance), t-analysis and cross tabulation. For significant data, it conducted an analysis by carrying out the Scheffe's test. According to the findings from this study, they showed a significant difference only in gender and curriculum desired to be opened in the question about e-learning participation motives per background factor. As for the learners' motives to study, it was confirmed that they tend to become more biased on time utilization and convenience of learning methods. The analysis of which factor of the three - learning factors, system factors and instructor's factors - has greatest effects on learning satisfaction indicated that learning factors influenced learning satisfaction the most in accordance with values for non-standard coefficient beta, followed by instructor factors which had a direct effect.

Application of aqueous carbonated slags in the immobilization of heavy metals in field-contaminated soils

  • Choi, Jiyeon;Shin, Won Sik
    • Environmental Engineering Research
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    • v.25 no.3
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    • pp.356-365
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    • 2020
  • The aqueous carbonation efficiencies of basic oxygen furnace (BOF) and ladle slags at various pressures, temperatures, and liquid-to-solid (L/S) ratios were investigated to determine optimum conditions. The maximum CO2 carbonated concentrations in slag (0.584 mmol/g for BOF slag and 1.038 mmol/g for ladle slag) was obtained at 10 bars, 40℃, and L/S = 5 mL/g-dry. The L/S ratio was the most critical parameter for carbonation. The effect of carbonated slag amendment on the immobilization of heavy metals in two field-contaminated soils was also investigated. The immobilization efficiencies evaluated by using the toxicity characteristic leaching procedure (TCLP) and the Standards, Measurements and Testing Programme (SM&T) were above 90% for both raw and carbonated slags for all soils. The TCLP-extractable heavy metals concentrations were below the criteria (5.0, 1.0 and 5.0 g/L for Pb, Cd, and Cr, respectively) after immobilizations with both slags except for Pb in soil B. The SM&T analysis showed the decrease in the exchangeable phase but the increase in residual phase after immobilization with raw and carbonated slags. The results of this study imply the promising potential of the carbonated slags on the immobilization of heavy metals in the field-contaminated soils.

Effect of Nozzle on Leak-Before-Break Analysis Result of Nuclear Piping (노즐이 원자력 배관의 파단전누설 해석 결과에 미치는 영향)

  • Kim, Yeong-Jin;Heo, Nam-Su;Gwak, Dong-Ok;Yu, Yeong-Jun;Pyo, Chang-Ryul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.11
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    • pp.2796-2803
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    • 2000
  • For traditional Leak-Before-Break(LBB) analyses, symmetric conditions were assumed for a pipe-nozzle interface to simplify the analysis in calculating J-integral. However. this assumption could result in an overly conservative design criteria for a pipe-nozzle interface, Since the pipe-nozzle interface is asymmetric due to the difference of stiffness between pipe and nozzle, it is required to develop a new methodology considering the nozzle effect. The objective of this paper is to evaluate the effect of nozzle no the development of LBB design criteria for nuclear pipings. For this purpose, extensive finite element analysis were performed to evaluate the effect of nozzle on Crack Opening Area(COA), Detectable Leakage Crack(DLC) length and J-integral values. In conclusion, it was proven that the application of LBB concept could be extended for more nuclear piping system by considering the nozzle.

Development of Main Steam Line Break Mass and Energy Release Analysis with RETRAN-3D Code

  • Park, Young-Chan;Kim, Yoo
    • Journal of Energy Engineering
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    • v.12 no.2
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    • pp.93-100
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    • 2003
  • An estimation methodology of the mass and energy (M/E) release due to the main steam line break (MSLB) has been developed with the RETRAN-3D code. In the case of equipment qualification (EQ), the over-estimated temperature would exceed the design limits of some cables or valves. In order to have a more flexible EQ profiles from the MSLB M/E release, the methodology with the best-estimated code was used. The major conditions affecting the MSLB M/E were found to be the initial SG level, heat transfer between primary and secondary sides, power level, operable protection system, main or auxiliary feedwater availability, and break conditions. The RETRAN-3D models were developed for the Kori unit 1 (KRN-1) which is typical two loop Westinghouse (WH) designed plant. Particularly, a detailed model of the steam generators was developed to estimate a more realistic two-phase heat transfer effect of the steam flow. After the modeling, the methodology has been developed through the sensitivity analyses. The M/E release data generated from the analyses have been used as the input to the inside containment pressure and temperature (P/T) analysis. According to the results at the point of view containment P/T, the Kori unit 1 can have more margin of 5∼15 ㎪ in pressure and 8∼15$^{\circ}C$ in temperature.

A Study of Dichotic Listening Using the TOEIC Listening Test

  • Lee, Myung-Sook;Cha, Kyung-Whan
    • Speech Sciences
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    • v.13 no.2
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    • pp.121-132
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    • 2006
  • The purpose of this research was to investigate dichotic listening, that is, whether the left and right ears have different functionalities in actual listening. Unlike previous studies, which used short words or a list of two or three numbers, these researchers investigated more comprehensive listening ability using the Toeic listening test. Sixty-three university students participated in this study. The subjects took three tests in total: one using only the right ear, another using the left ear, and the third using both. T-analysis of SPSS on the data revealed that there is a significant difference between the test results with only the right or left ear and the ones with both ears. So we cannot find right-ear priority in this study. We can see that in comprehensive listening, right hemisphere plays an important role as well as left hemisphere. When grouped according to language ability, test result of low group is the same as the total test result. However, in high group there is no significant difference between the test results with left ear and the results with both ears in high group. In mid group there is no significant difference between the test results with right ear and the results with both ears. The different functionalities of left and right ears and suggestions for future research are presented.

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