• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.7
• /
• pp.712-722
• /
• 1992

Several voltage instability/collapse problems that have occurred in the electric utility industry worldwide have gained the attention of engineers and researchers of electric power systems. This paper proposes an effective calculation scheme of the extreme loading point and nose curves(P-V curves) using modified Newton-Raphson(N-R) load flow method and the Continuation Method. This method provides detail and visual information of the power system voltage profile and operating margin ro operators and planners. In this paper, a modified load flow claculation method for ill-conditioned power systems is introduced for the purpose of seeking more precise load flow solutions and nose curves, and the Continuation Method is also used as a part of the solution algorithm for the calculation of extreme loading point and nose curves. The conventional polar coordinate based N-R load flow program is modified to avoid numerical difficulties caused by the singularity of the Jacobian matrix occuring in the vicinity of extreme loading point of heavily loaded systems. Application results of the proposed method to Klos-Kerner 11-bus system and modified IEE-30-bus system are presented to assure the usefulness of the approach.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.4
• /
• pp.297-304
• /
• 2022

This study compares the performance of artificial intelligence (AI)-based maximum power point tracking (MPPT) methods under partial shading conditions in a photovoltaic generation system. Although many studies on AI-based MPPT have been conducted, few studies comparing the tracking performance of various AI-based global MPPT methods seem to exist in the literature. Therefore, this study compares four representative AI-based global MPPT methods including fuzzy logic control (FLC), particle swarm optimization (PSO), grey wolf optimization (GWO), and genetic algorithm (GA). Each method is theoretically analyzed in detail and compared through simulation studies with MATLAB/Simulink under the same conditions. Based on the results of performance comparison, PSO, GWO, and GA successfully tracked the global maximum power point. In particular, the tracking speed of GA was the fastest among the investigated methods under the given conditions.

• Korean Journal of Oriental Medicine
• /
• v.8 no.2 s.9
• /
• pp.47-65
• /
• 2002

This project is planned to grasp the present situation of traditional medicine part in our country and to study protection method about this by the intellectual property which is the international concerning point recently. Through this, we will be able to devise means to deal with protection method of traditional medicine being developed by WIPO now. Traditional medicine field In our country Is organized with specific condition separated into the part of institution and the part of non-institution. So, because of the closed peculiarity, we have experienced the difficulties to understand the real facts about traditional medicine. We cannot be indifferent to the matter anymore. Because the expectation of object people is high, we could expect the realization of research content. In 1 detail project, we investigated the situation of traditional medicine in our country through various collecting methods for excavation of oriental treatment technique and herb medicine which is worth protecting. With it, we sorted again into 56 kinds of 11 parts through analysis of validity in the way of oriental medicine. And we tried to link this up 2 detail project which is about legal and institutional guarantee concerning protection. furthermore, we tried to find approach ways for security of objectivity into 4 steps with the example of model disease. we could complete practical classification of traditional medicine in our country. In 2 detail project, we studied the protection method by the intellectual property through research result in 1 detail project. For this, we observed an outline of the intellectual property including a patent application analysis in folk traditional medicine part, and problems of traditional medicine protection and world trend by traditional knowledge protection tendency and the patent law In domestic traditional medicines, the aspects unprotectable with the patent law now were remained. So, we suggested supplementary plan. And we also suggested the freedom of utilization between traditional medicine possession countries (in-situ utilization) and the demand compensation payment for a third country (ex-situ utilization) in connection with international movement.

• Structural Engineering and Mechanics
• /
• v.53 no.5
• /
• pp.981-995
• /
• 2015

This paper presents a finite element procedure for dynamic analysis of non-uniform Timoshenko beams made of axially Functionally Graded Material (FGM) under multiple moving point loads. The material properties are assumed to vary continuously in the longitudinal direction according to a predefined power law equation. A beam element, taking the effects of shear deformation and cross-sectional variation into account, is formulated by using exact polynomials derived from the governing differential equations of a uniform homogenous Timoshenko beam element. The dynamic responses of the beams are computed by using the implicit Newmark method. The numerical results show that the dynamic characteristics of the beams are greatly influenced by the number of moving point loads. The effects of the distance between the loads, material non-homogeneity, section profiles as well as aspect ratio on the dynamic responses of the beams are also investigated in detail and highlighted.

• Journal of Korean Academy of Nursing
• /
• v.34 no.3
• /
• pp.552-564
• /
• 2004

Purpose: This study was to develop a client health status outcome evaluation instrument, and examine content validity, reliability, construct validity, and the acceptability of this instrument. Method: A preliminary list was made of such key information as standards, criteria, indicators and measures, by means of a broad review of literature within the field. After determining the preliminary instruments, the study sought to obtain examination, consensus, and modification of two groups of experts in the home-care field. Finally, the instrument examined content validity, reliability, construct validity, and the acceptability of this instrument. Result: The tool was considered of 13 criteria, 48 indicators, and 167 detail measures. The content validity index of the tool was above 0.8 according to the expert group. Regarding the reliability of the evaluators of standards 1 and 2, the degree of agreement between evaluators was high(96.4% through 98.2%). Construct validity in this study, the difference in the mean score between the baseline point and the follow up point of each of standards 1 and 2 was significant, and the mean score of the follow up point was more than that of the baseline point. After examining the acceptability of this instrument with practice managers and home care nurses in home care institutions, a positive opinion was given of this instrument, and it was indicated that to be useful and applicable in home care practice. Conclusion: The results of evaluating client outcome will contribute to overall outcome-based quality improvement and service marketing in home care by providing a constant gauge of home care effectiveness.

• Fashion & Textile Research Journal
• /
• v.4 no.6
• /
• pp.534-543
• /
• 2002

The purpose of this study was to identify the body proportions of girls in middle and high school who have been a major sales target of clothing manufacturers and thus to provide the basic information on the proportion of human body, which is essential for manufacturer to produce clothing and for individual consumers to select right apparels to wear and purchase. The subjects were 133 girls in middle school and 141 girls in high school. As measuring instruments, the Martin's anthropometer, tapelines, and belts for marking waistline were used. In order to analyze the data, t-test and factor analysis were used. The measurement of vertical distance between vertex and measuring points, showed a significant difference between the high school group and middle school group in every item. In the comparison of eight head proportion between the two groups, middle school students had 7.2 head proportion while girls in high school had 6.9 head proportion in detail. The factor analysis of major divided body parts of the two groups indicated that waist-hip and hip-crotch, constituting lower trunk together, vertex-apex nasi, and apex nasi-back neck point, constituting head together, back neck point-spina scapula and spina scapula-waist, constituting posterior of upper body together, and mentum-bust point and bust point-waist, constituting anterior of upper body together, were in inverse proportion.

• The Research Journal of the Costume Culture
• /
• v.11 no.4
• /
• pp.487-499
• /
• 2003

The purpose of this study was to suggest marketing strategies to internet fashion shopping malls identifying factors that customers consider important. Data were collected by survey questionnaire and the subjects were 322 men and women in their twenties and thirties living in Seoul and Kyung-gi. SPSS 10.0 package were used and reliability, frequency, cross tabulation, chi-square, paired t-test, ANOV A and Duncan test were conducted for data analysis. The results were as follows. I) Subjects placed the most importance on providing the precise and detail information of products but its satisfaction level was low. 2) Subjects considered the ‘low price’ very importantly but its satisfaction level of it was not high. 3) Subject's importance and satisfaction level of ‘point system’ were about an average. 'Point system' has to be activated by using systems such as 'point network system' by pointbanking co. as one of price-cutting strategies. 4) Internet fashion shopping mall users treated 'the security system of personal data' importantly while they were not sufficiently satisfied with the system. 5) Female placed more importance on design and color of products and suppliance of the trendy items.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.809-811
• /
• 2010

In most floating-point operations related with 3D graphic applications for mobile devices, properly approximated data calculations with reduced complexity and low power are preferable to exactly rounded floating-point operations with unnecessary preciseness with cost. Among all the sophisticated floating-point arithmetic operations, multiplication and division are the most complicated and time-consuming, and they can be transformed into addition and subtraction repectively by adopting the logarithmic conversion. In this process, the most important factor for performance is how high we can make an approximation of the logarithm conversion. In this paper, we cover the trends in studying the logarithm conversion circuit designs. We also discuss the important factor in design issues and the applicable fields in detail.

• Journal of Power Electronics
• /
• v.17 no.3
• /
• pp.601-609
• /
• 2017

Gallium nitride (GaN) power switching devices are promising candidates for high switching frequency and high efficiency power conversion due to their fast switching, low on-state resistance, and high-temperature operation capability. In order to facilitate the use of these new devices better, it is required to investigate the device characteristics and performance in detail preferably by comparing with various conventional silicon (Si) devices. This paper presents a comprehensive study of GaN high electron mobility transistor (HEMT) based non-isolated point-of-load (POL) synchronous buck converter operating at 2.7 MHz with a high step-down ratio (24 V to 3.3 V). The characteristics and performance of GaN HEMT and three different Si devices are analytically investigated and the optimal operating point for GaN HEMT is discussed. Zero-voltage switching (ZVS) is implemented to minimize switching loss in high switching frequency operation. The prototype circuit and experimental data support the validity of analytical and simulation results.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2004.04a
• /
• pp.209-214
• /
• 2004

This paper presents a RFM-based image matching algorithm which put constraints on the search space through the object-space approach. Also, the detail procedure of generating 3-D surface models from the RFM is introduced as an end-user point of view. The proposed algorithm provides the PML (Piecewise Matching Line) for image matching and reduces the search space to within the confined line-shape area.