• Journal of Power Electronics
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• v.17 no.5
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• pp.1308-1316
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• 2017

The distributed maximum power point tracking (DMPPT) concept is widely adopted in photovoltaic systems to avoid mismatch loss. However, the high cost and complexity of DMPPT hinder its further promotion in practice. Based on the concept of DMPPT, this paper presents an integrated submodule level half-bridge stack structure along with an optimal current point tracking (OCPT) control algorithm. In this full power processing integrated solution, the number of power switches and passive components is greatly reduced. On the other hand, only one current sensor and its related AD unit are needed to perform the ideal maximum power generation for all of the PV submodules in any irradiance case. The proposal can totally eliminate different small-scaled mismatch effects in real-word condition and the true maximum power point of each PV submodule can be achieved. As a result, the ideal maximum power output of the whole PV system can be achieved. Compared with current solutions, the proposal further develops the integration level of submodule DMPPT solutions with a lower cost and a smaller size. Moreover, the individual MPPT tracking for all of the submodules are guaranteed.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.2
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• pp.138-150
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• 2013

This study investigates changes in body size (as well as fit) before/after wear, according to the breast and brassiere type. To offer producers basic data on how to develop excellent brassieres, we accordingly conducted preliminary research on 183 20's women. The research revealed that breast-related size and fit change by about 10%; however, the upper length and inner length of breasts decreases. The fit of domed ones is the best and the fit of the elongated ones is the worst; subsequently, a closer representation of the ideal breast leads to a better fit to wear.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2095-2101
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• 2008

In this paper, we consider a performance improvement of neural network for predicting defect size of steam generator tube using early stopping. Usually, neural network is trained until MSE becomes less than a prescribed error goal. The smaller the error goal, the greater the prediction performance for the trained data. However, as the error goal is decreased, an over fitting is likely to start during supervised training of a neural network, which usually deteriorates the generalization performance. We propose that, for the prediction of an axisymmetric defect size, early stopping can be used to avoid the over-fitting. Through various experiments on the axisymmetric defect samples, we found that the difference bet ween the prediction error of neural network based on early stopping and that of ideal neural network is reasonably small. This indicates that the error goal used for neural network training for the prediction of defect size can be efficiently selected by early stopping.

• Korean Institute of Interior Design Journal
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• no.2
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• pp.17-21
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• 1994

The purpose of this study was to compare the spatial structures for household activities according to the house size. multi-Dimentional Scaling analysis was done, using questinonaire data from 349 middle income housewives living in apartment in the area of Captital region. This was an extended article of previous one. In case of house whose size was less than 20 Pyung, washing cloth and bathing behavior took place in the same place whereas in other house size, bathing behavior was incoperated into various behaviors usually shown in the bedroom. The ideal structure in the house of 20 Pyung's showed home office space closer to the bedroom area whereas in others it appeared independently.

• Journal of the Korean Society of Costume
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• v.44
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• pp.104-116
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• 1999

This study was intended to make an inquiry into the effect of lines, shapes and colors (achromatic colors) as apparel design elements on the perceptions of facial size, brightness and shape through an empirical research based on the theories of visual perception and optical illusion that have been studied in Gestalt Psychology, which becomes the basis of apparel design principles. It was shown that the facial size was influenced by the collar size, the degree of neckline cut, and the thickness of the trimming line. The white scarf with the white jacket made the face look darkest while the black scarf with the black jacket made the face look brightest. When the neckline had the characteristic of the line contrasted with the facial shape, the oval-shaped face was perceived to be the most ideal. When the facial shape and the neckline shape were similar, the facial shape was perceived to be more highlighted.

• Journal of the Korean Ceramic Society
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• v.37 no.7
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• pp.625-631
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• 2000

In this study, the characteristics and sinterablities of TiO2 powders which were fabricated on sol-gel process and supercritical fluid process were examined. The powders fabricated on sol-gel process were amorphous. The particle size and shape were changed with the amount of water used for hydrolysis of titanium ethoxide. The powders were changed from amorphous to crystalline by heating at 400℃. The crystalline anatase TiO2 powders were directly prepared in ethanol supercritical fluid condition that temperature was 270±3℃ and pressure was 7.3 MPa. It's primary crystalline size was 20 nm and agglomerated as spherical shape whose size was 0.7∼1㎛. The powders prepared on sol-gel process were not sintered densely at 900℃ because of abnormal grain growth. However, the powders which prepared on supercritical fluid process were sintered densely at the comparatively low temperature of 800℃ by ideal growth of grain, which are fired at 900℃.

• Journal of the Korean Society of Clothing and Textiles
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• v.42 no.5
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• pp.839-854
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• 2018

This study (1) explores female consumers' attitudes toward fat people and perceptions about plus-size models, (2) addresses female consumers' responses to models with different body sizes, and (3) examines the effect of plus-size model presence on female consumers' body image. We collected an online questionnaire from a total of 600 female participants in their 20's and 30's. Stimuli included six full-colored photo images of models with thin and plus body sizes (three in each group). Images were captured from the online shopping site of the fashion brand currently providing both average and plus-size clothes. Respondents were randomly assigned one of the groups by model size. Results support the sociocultural perspective that a thin/ideal body of models has a negative influence on female viewers' sociocultural attitudes toward appearance, mood state and body satisfaction. Findings also suggest that exposure to plus-size models can reduce negative media effects on females body image perceptions, regardless of individual body size.

• Restorative Dentistry and Endodontics
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• v.49 no.1
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• pp.3.1-3.8
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• 2024

This article is a narrative review that discusses the recommended sample size requirements to design a pilot study to assess the reliability of a questionnaire. A list of various sample size tables that are based on the kappa agreement test, intra-class correlation test and Cronbach's alpha test has been compiled together. For all calculations, type I error (alpha) was set at a maximum value of 0.05, and power was set at a minimum value of 80.0%. For the kappa agreement test, intra-class correlation test, and Cronbach's alpha test, the recommended minimum sample size requirement based on the ideal effect sizes shall be at least 15, 22, and 24 subjects respectively. By making allowances for a non-response rate of 20.0%, a minimum sample size of 30 respondents will be sufficient to assess the reliability of the questionnaire. The clear guideline of minimum sample size requirement for the pilot study to assess the reliability of a questionnaire is discussed and this will ease researchers in preparation for the pilot study. This study provides justification for a minimum requirement of a sample size of 30 respondents specifically to test the reliability of a questionnaire.

• Journal of the Korean Institute of Landscape Architecture
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• v.22 no.2
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• pp.13-24
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• 1994

the purpose of this study was to suggest managemental strategies for one-day use recreational area in public sector under competitive environment with private sector. Data was collected from citizens of Seoul, and 10 recreational areas were determined by a preliminary survey. Theses areas were regarded as "products", then positioning was applied to these products. Perceptual map was produced by multidimensional scaling to identify degree of competition among areas. Properties, which were developed by the Kelly Repertory Grid, were utilized to understand the strong and weak points of each area. Ideal types of recreational areas were analyzed by PREFMAP, then the size and distribution of recreation market of Seoul were found by grouping of individual ideal point by cluster analysis. Several strategies were suggested to enhance the competitive power for public recreation areas, and a few comments were described to improve this method for future research.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.859-864
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• 1998

Compact and small size, reliable and failsafe operation and low cost featuring fault current limiter causing the designer to take a close look into the use of passive fault current limiter(FCL) for the protection of power semiconductor devices in power electronic systems. This paper has identified the main parameters responsible for the development of ideal passive magnetic current limiter. The effect of those parameters on the range of operation and the voltage-current characteristics of the magnetic current limiter has been studied using tableau approach. Desirable characteristics are discussed and the simulation results are presented.