• Journal of Power Electronics
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• v.19 no.1
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• pp.296-306
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• 2019

The flyback topology is being widely used in power adapters. The coupling capacitance between primary and secondary windings of a flyback transformer is the main path for common-mode (CM) noise conduction. A Y-cap is usually used to effectively suppress EMI noise. However, this results in problems in space, cost, and the danger of safety leakage current. In this paper, the CM noise behaviors due to the electric field coupling of the transformer windings in a flyback adapter with synchronous rectification are analyzed. Then a scheme with balance winding is proposed to reduce the CM noise with a transformer winding design that eliminates the Y-cap. The planar transformer has advantages in terms of its low profile, good heat dissipation and good stray parameter consistency. Based on the proposed scheme, with the help of a full-wave simulation tool, the key parameter influences of the transformer PCB winding design on CM noise are further analyzed. Finally, a PCB transformer for an 18W adapter is designed and tested to verify the effectiveness of the balance winding scheme.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.183-187
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• 2015

The Risk Management (RM) is applied for managing uncertainty of project. In this circumstance, the competences of RM have a direct effect on the performance of its application. Especially, as the RM, one of the project management areas, is a peopleoriented management field, the individual behavioral competences are significant for a risk manager. Therefore, this paper describes the development of individual behavioral competences for construction project risk manager. For this, the research classifies the individual behavioral competences of RM. And, the Exploratory Factor Analysis (EFA) are applied to verify a validity of the competences. Likewise, a reliability analysis using Cronbach's alpha values is performed to test internal consistency. Based on the results, the authors carry out the Focus Group Interview (FGI) on expert panels of construction RM to confirm the hierarchical model of the individual behavioral competences. It is concluded that the proposed hierarchical model of individual behavioral competences helps construction companies to diagnose the competences of their project risk manager for progressing.

• Journal of Gifted/Talented Education
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• v.22 no.1
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• pp.61-85
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• 2012

The OSPG(Observation Scale for Parents of the Gifted in Korean Traditional and Western Music) is one of the tools for screening of the Gifted in Korean traditional and Western music. So the validity and reliability of the OSPG has an influence on securing validity of the whole identification process. The purpose of this study is to examine the validity and reliability of the OSPG-2 that input screening processing, and to suggest systematization of identification processing for the Gifted in Korean traditional and Western Music. For the achievement of this purpose, this study administered the OSPG-2 to 261 gifted students aged between 13 and 16 in the middle or high school for the arts. To validate the OSPG-2, I analyzed items of the OSPG-2, and conducted the exploratory and confirmative factor analysis. I also examined the internal consistency. As a result of the exploratory factor analysis, I collected 40 items of the OSPG-2 finally. Furthermore, I could identify psychological construct of the Gifted in Korean traditional and Western Music. The consequence of confirmative factor analysis, the model provided good fit to observed data. As a result of reliability analysis, the internal consistency of the internal characteristic verified Cronbach's ${\alpha}$=.939, and the internal consistency of the external environmental characteristic verified Cronbach's ${\alpha}$=.887. This result of validity study reflects the fact that the OSPG-2 is a valid scale and is able to input to gifted educational field instantly.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.5
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• pp.55-62
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• 2011

In this paper, a temporal color and luminance variation suppression algorithm for a digital video sequence is proposed by considering time-varying light source. When a video sequence is sampled with the periodically emitting illuminant and with a short exposure time, the color rolling phenomenon occurs, where the color and the luminance of the image periodically change from field to field. In conventional signal processing techniques, the luminance variation remaining in the resultant video sequence degrades the constancy of the image sequence. In the proposed method, we obtain video sequences with constant luminance and color by compensating for the inter-field luminance variation. Based on a motion detection technique, the amount of the luminance variation for each channel is estimated on the background of the sequence without the effects of moving objects. The experimental results clearly show that our strategy efficiently estimated the illuminant change without being affected by moving objects, and the variations were efficiently reduced.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.2 s.72
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• pp.151-160
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• 2006

In this study, we propose a new efficient 2-noded hybrid-mixed element for curved beam vibrationshaving a uniform and non-uniform cross section. The present element considering transverse shear strain is based on Hellinger-Reissner variational principle and introduces additional nodeless degrees for displacement field interpolation in order to enhance the numerical performance. The stress parameters are eliminated by the stationary condition and then the nodeless degrees are condensed out by the Guyan reduction. In the performance evaluation process of the present field-consistent higher-order element, we carefully examine the effects of field consistency and the role of higher-order interpolation functions on the hybrid-mixed formulation. Several benchmark tests confirm e superior behavior of the present hybrid-mixed element for curved beam vibrations.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.681-688
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• 2022

In this study, the process of drone photography, automatic volume calculation, total floor area conversion, and waste calculation was constructed as a QGIS plug-in to predict the demolition waste (DW) generated in an aged area where drawing information or building information is uncertain. Through a case study, the high consistency between the automatically calculated volume using the drone and the BIM volume based on the field measurement was confirmed. Field application was carried out for the planned demolition work site, and the consistency between the drone-based volume and the actual measurement-BIM-based volume was reconfirmed. The waste generation unit was applied and the amount of DW was calculated by setting the floor height and building type, and the entire process was completed within 6 hours. Although the difference between building information and building objects through drones occurred according to the setting of temporary structures, loads, and floor heights, it was found that the actual amount of DW was generated more than the initial estimate. It is expected that measures to improve the accuracy of volume and floor area conversion will be required through case studies in the future.

• Korean Journal of Remote Sensing
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• v.39 no.5_1
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• pp.599-608
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• 2023

The increasing interest in soil moisture data using satellite data for applications of hydrology, meteorology, and agriculture has led to the development of methods for generating soil moisture maps of variable resolution. This study demonstrated the capability of generating soil moisture maps using Sentinel-1 and Sentinel-2 data provided by Google Earth Engine (GEE). The soil moisture map was derived using synthetic aperture radar (SAR) image and optical image. SAR data provided by the Sentinel-1 analysis ready data in GEE was applied with normalized difference vegetation index (NDVI) based on Sentinel-2 and Environmental Systems Research Institute (ESRI)-based Land Cover map. This study produced a soil moisture map in the research area of Victoria, Australia and compared it with field measurements obtained from a previous study. As for the validation of the applied method's result accuracy, the comparative experimental results showed a meaningful range of consistency as 4-10%p between the values obtained using the algorithm applied in this study and the field-based ones, and they also showed very high consistency with satellite-based soil moisture data as 0.5-2%p. Therefore, public open data provided by GEE and the algorithm applied in this study can be used for high-resolution soil moisture mapping to represent regional land surface characteristics.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.97-105
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• 2005

In order to reduce the uncertainties and improve the air flow field, objective analysis using asynoptic observational data is chosen as a method that enhances the reality of meteorology. In surficial data and their numerical interpolation for improving the interpretation of meteorological components, objective analysis scheme should perform a smooth interpolation, detect and remove the bad data and carry out internal consistency analysis. For objective analysis technique which related to data reliability and error suppression, we carried out two quality control methods. In site quality control, asynoptic observational data at urban area revealed low representation by the complex terrain and buildings. In case of wind field, it was more effective than temperature field when it were interpolated near waterbody data. Many roads, buildings, subways, vehicles are bring about artificial heat which left out of consideration on the simulation of air flow field. Therefore, in temperature field, objective analysis for more effective result was obtained when surficial data were interpolated as many as possible using value quality control rather than the selection of representative site.

• Journal of the Korean Home Economics Association
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• v.33 no.1
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• pp.1-18
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• 1995

This study examined the confronting problems in home economics and its historical and philosophical causing background, and suggested the future direction for home economics and home economics education. This study, hoped to help home economics overcoming its chaotic situation, and to establish academic characteristics through a philosophical consistency: 1. What are the significant problems which home economics has confronted, and the consequences of those problems\ulcorner 2. What are the fundamental caues of the problem\ulcorner 3.What should be the nature of home econimics to be able to overcome the confronting problems and what can be proposed for the future of home economic\ulcorner Each research question was addressed by analyzing Journal articles, theses, philosophical studies in the field. The results were as follows; 1. such problems as the ambiguity in research focus and the nature of academic charateristcs, and the limitation of research method have resulted fragmentation and specialization in the field, and the lack of philosophical research. Also they led home and family. Moreover each problem brought chaos into curriculum of home economics and that of home economics deucation. 2. The philosophical causing backgrounds of present problems are western ideas such as pragmatism, positivism, Social Darwnism and Korean ideas such as Confucian tradition, Practical Science movement in the 19th century, and modernization and industrialization from the middle of 20th century. Along with influencing historical situation these backgrounds have distorted home economics to be technical science oriented. 3. To solve these problems academic characteristics of home economics must be reestablished as practical science and as profession. This study proposed following for the future of home economics and home economics education: (1) For the future of home economics, first, it needs to recover the unity as one academic field with its focus on family by overcoming fragmentation and specialization trend in the field. Secondly, philosophical and historical studies must be carried o for the unity of all specialized field in home economics. Thirdly, home economics must try to reestablish and reflect in pratice its acadimic characteristics as practical science and as profession. (2) For home economic eduation, first, it should not be the instrument for idelogies of powerful social systems. And teacher education for home economics teachers must inclued principles of home economics and philosophy and history of home economics enabling teachers to achieve purposes of home economics. Secondly, its curriculum contents should be composed of practical ones beyond technical ones.

• Wind and Structures
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• v.18 no.2
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• pp.195-213
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• 2014

Recently, the horizontal axis rotor performance optimizer (HARP_Opt) tool was developed in the National Renewable Energy Laboratory, USA. This innovative tool is becoming more popular in the wind turbine industry and in the field of academic research. HARP_Optwas developed on the basis of two fundamental modules, namely, WT_Perf, a performance evaluator computer code using the blade element momentum theory; and a genetic algorithm module, which is used as an optimizer. A pattern search algorithm was more recently incorporated to enhance the optimization capability, especially the calculation time and consistency of the solutions. The blade optimization is an aspect that is highly dependent on experience and requires significant consideration on rotor control strategies, wind data, and generator type. In this study, the effects of rotor control strategies including fixed speed and fixed pitch, variable speed and fixed pitch, fixed speed and variable pitch, and variable speed and variable pitch algorithms on optimal blade shapes and rotor performance are investigated using optimized blade designs. The effects of environmental wind data and the objective functions used for optimization are also quantitatively evaluated using the HARP_Opt tool. Performance indices such as annual energy production, thrust, torque, and roof-flap moment forces are compared.