• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.125-134
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• 1989

Pseudo-random load waves for fatigue testing were generated by personal computer simulation and preliminary study was performed on the growth behavior of surface fatigue crack under random ladings. The closure behavior and growth rates of surface fatigue crack were significantly influenced by the characteristics of random waves. It was also found that the growth rates of surface fatigue crack under random loadings could not be always described by the effective stress intensity factor based on the concept of crack closure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.370-375
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• 1997

The ratings of noise are consisted of physical factors and psychological factors. The physical factor means the scales and the spectrum characteristics of noise, on the other hand the psychological factor means the subjective emotion, sensation and individual judgement for it. Therefore the rating of noise must reflect the subjective psychology of people for it. But it is very difficult to establish an effective scale which can reflect well that because the subjective psychology has many variables according to the cultural differency, nationality and individual personalities. In this paper, Korean Vocabularys for the assessment of noise were surveyed in order to find out the effective noise scale for Korean.

• Journal of the Korea Safety Management & Science
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• v.10 no.1
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• pp.67-73
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• 2008

National Education Information System (NEIS) is an ambitious reform project that can improve the competitiveness and performance of education field and to link administrational work of between schools and their senior administration offices via internet. NEIS is introduced to lighten the teachers' overburden, to standardize the work process and to bring better quality education to each classroom and make it possible for those involved in education to resolve any related educational problem on line. This paper aims to construct a hierarchy model consisting of key factors such as technological and administrative factors for the effective use of NEIS and to evaluate the relative importance among key factors using fuzzy AHP technique included fuzzy concepts. Eventually, the analysis results can be utilized to develop the future improvement strategy of NEIS and to satisfy the users.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.337-340
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• 2006

The purpose of this study is to propose the stiffness reduction factor for flat plate slabs under lateral loads. Current design code (e.g., ACI 318-05) requires considering the effects of cracks for calculating slab stiffness under lateral loads. This study collected the test results of 20 interior slab-column connections, from which stiffness reduction in each test was estimated with respect to the ratio of applied moment to cracking moment ($M_a/M_{cr}$). Based on collected data, this study proposed equations for calculating stiffness reduction with respect to $M_a/M_{cr}$. To verify the proposed equations, this study conducted the experimental test of interior slab-column connections under quasi-static cyclic loading. From the test, load-deformation curve is compared to that obtained from effective beam width method with the proposed equation for the stiffness reduction. It is shown that the effective beam width method with the proposed equation for stiffness reduction predicts accurately the test results.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.232-233
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• 2012

This paper presents an effective control scheme for an electric vehicle battery charger where a symmetrical bridgeless power factor-corrected converter and a buck converter are cascaded. Both converters have been popular in industries because of their high efficiency, low cost, and compact size, hence combining these converters makes the overall battery charging system strongly efficient. Moreover, this charger topology can operate at universal input voltage and attain a desired battery current and voltage without ripple. In order to achieve a unity input power factor and zero input current harmonic distortion, the proposed control scheme adopts duty ratio feed-forward control technique in both current and voltage control loop. Additionally, in the current loop, its reference is created by a phase-locked loop (PLL) block, leading to a pure sinusoidal input current although the input voltage waveform is being distorted. The feasibility and practical value of the proposed approach are verified by simulation and experiment with an 110V/60Hz ac line input and 1.5kW-72V dc output of the battery charging system.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.2
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• pp.183-191
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• 2023

The potential impact of hypothetical accidents that occur during the immediate and deferred dismantling of the Kori Unit 1 steam generator has been comprehensively evaluated. The evaluation includes determining the inventory of radionuclides in the Steam Generator based on surface contamination measurements, assuming a rate of release for each accident scenario, and applying external and internal exposure dose coefficients to assess the effects of radionuclides on human health. The evaluation also includes calculating the atmospheric dispersion factor using the PAVAN code and analyzing three years of meteorological data from Kori NPP to determine the degree of diffusion of radionuclides in the atmosphere. Overall, the effective dose for residents living in the Exclusion Area Boundary (EAB) of Kori NPP is predicted, an it is found that the maximum level of the dose is 0.034% compared to the annual dose limit of 1 mSv for the general public. This implies that the potential impact of hypothetical accidents on human health discussed above is within acceptable limits.

• Journal of the Korean Ceramic Society
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• v.32 no.11
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• pp.1292-1300
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• 1995

The ionic conductivity of NASICON solid electrolytes was simulated by using Monte Carlo Method (MCM). There were included two conduction paths: (1) Na1-Na2 and (2) Na1-Na2 including Na2-Na2. We assumed that mid-Na ions provde an additional driving force for Na mobile ions due to the interionic repulsion between Na1 and Na2 ions. The inflection point of vacancy availability factor, V has been shown at nearby x=2, the maximum mid-Na ions. The inflection point of vacancy availability factor, V has been shown at nearby x=2, the maximum mid-Na sites are occupied. The effective jump frequency factor, V has been shown at nearby x=2, the maximum mid-Na sites are occupied. The effective jump frequency factor, W increased rapidly with the composition at low temperature, but decreased at high temperature region. On Na1-Na2 conduction path, the minimum of charge correlation factor, fc and the maximum of $\sigma$T were appeared at x=2.0. this indicated that mid-Na ions affect on the high ionic conductivity behavior. At the whole range of NASICON composition, 1n $\sigma$T vs. 1/T* plots have been shown Arrhenius behavior but 1n (VWFc) vs. 1/T* have been shown the Arrhenius type tendency at x=2, which mid-Na is being the maximum. The results of MCM agreed with the experimental one when the chosen saddle point value was 6$\varepsilon$ : 3$\varepsilon$. Here the calculated characteristic parameter of materials, K and the phase transition temperature were -4.001$\times$103 and 178$^{\circ}C$ (1/T*=1.92, 1000/T=2.22), respectively.

• Informatization Policy
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• v.22 no.2
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• pp.75-92
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• 2015

The purpose of this study was to analysis about the relationship among Cyber Home Learning System(CHLS) circumstance, learner construct, learning satisfaction in elementary school students. Base on the selected data which was gathered from Chungbuk & Deajeon elementary schools, Structural Equation Modeling was used to examine the relationship between factors. The main results of the research were as follow : First, CHLS circumstance factor was more effective on the CHLS satisfaction than CHLS learner construct. In CHLS circumstance factor, 'service' factor was more influential variable. Second, there is high correlation between CHLS circumstance factor and CHLS learner construct. In CHLS satisfaction, 'contents and design' factor was more influential variable. Third, the model fit, = 624.945 (p<.001), RMR .020, GFI .929, AGFI .878, NFI .927, CFI .930, RMSEA .102 was relatively satisfied with the standard using structural equation model. As based on this results, CHLS in elementary education needs elaborate circumstance for the effective achievement.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.475-485
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• 2017

This paper develops a conversion function and method transforming from daily peak load curve used $LOLE_D$ [days/year] to hourly load curve used $LOLE_H$[hours/year]and describes relationship between $LOLE_D$ [days/year] and $LOLE_H$ [hours/year]. The indices can not only be transformed just arithmetically but also have different characteristics physically because of using their different load curves. The conversion function is formulated as variables of capacity and forced outage rate of generator, hourly load daily load factor and daily peak load yearly load factor, etc. Therefore, the conversion function (${\gamma}={\varphi}$(.)) can not be simple. In this study, therefore, the function is formulated as linear times of separated two functions. One is an exponential formed conversion function of daily load factor. Another is formulated with an exponential typed conversion function of daily peak load yearly load factor. Futhermore, this paper presents algorithm and flow chart for transforming from $LOLE_D$[days/year] to $LOLE_H$[hours/year]. The proposed conversion function is applied to sample system and actual KPS(Korea Power System) in 2015. The exponent coefficients of the conversion functions are assessed using proposed method. Finally, assessment errors using conversion function for case studies of sample system and actual system are evaluated to certify the firstly proposed method.

• Journal of People, Plants, and Environment
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• v.22 no.5
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• pp.435-444
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• 2019

This study is based on the premise that a garden space is a place that not only requires physical labor but also encourages conversation in the gardening group. We suggest the use of urban gardens as a place to revitalize local communities by promoting people to participate in various event programs. Through the theoretical study, we set the requirements that can be applied to "urban garden events". We developed measurement items and scales to be used as variables of each construction concept. Our survey was conducted on adults aged 19 and above who visited the 8th Korean Urban Agriculture Expo. Out of total 310 copies of the distributed questionnaire, only 298 effective samples were used in the empirical analysis. We can assume that people want to revitalize local communities based on the fact that 71 (23.8%) participants said they thought the purpose of the event is to achieve unity among residents. Throughout analysis, 15 of the necessary items were confirmed and classified into two factors: image of event (Factor 1) and evaluation item (Factor 2). As a result of verifying the relationship between educational level for Factor 1, age was significant in five items and education level was significant in six items. For Factor 2, four items were effective in relation to education level, while significant results were not found in relation to age. These results are expected to be significant if the intellectual curiosity of the residents is satisfied and the demand base of the urban garden events according to the characteristics of city people is expanded. Based on this study, it is necessary to conduct research on the use of urban gardens as an event with social functions as well as various programs that can be carried out in gardens to build and revitalize the community.