• 한국태양에너지학회 논문집
• /
• 제37권3호
• /
• pp.23-32
• /
• 2017

This paper presents losses comparison and analysis results for different types of fault modes of grid-connected photovoltaic system generated for long-term operation. The approach of losses comparison and analysis by faults is to identify relationship between measured and estimated values of five loss factors which are quantified from irradiance to system output power. This paper presents the symptom results for faults such as snow, shading, sensor defect, blackout, soiling and so on from three years or more monitored data. These results will indicate that it is useful to develop fault detection and diagnosis tool to enhance capacity factor and save operation and maintenance cost of grid-connected photovoltaic system in the field.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.122-125
• /
• 2004

This paper presents the loss analysis comparison for Three-Level Converter and Full-Bridge converter. The result of the analysis is verified with 2.5kW prototype.

• Journal of Magnetics
• /
• 제19권2호
• /
• pp.146-150
• /
• 2014

The objective of this paper is to provide a comparison between two transverse flux rotary machines (TFRM) with different topologies of stator cores. Depending on how to make stator core with laminated steel sheets, the one topology is 'perpendicular stacking core' and the other is 'separated core'. Both of the two cores have been designed considering 3-dimensional (3-D) magnetic flux path with the same output power conditions, but the core losses are quite different and it causes different magnetic and thermal characteristics. For comparison of these two topologies of stator cores, therefore, core losses have been calculated and used as a heat source in no-load conditions, and the thermal stress has been also calculated. 3-D finite element method has been used for the magnetic field, thermal, and stress analysis to consider the 3-D flux path of the TFRM. After comparing the analysis results of the two topologies, experimental results are also presented and discussed.

• 한국IT서비스학회지
• /
• 제12권4호
• /
• pp.349-367
• /
• 2013

In MANET, the AODV routing protocol with on-demand method has a problem in large control packet overhead. In order to improve this, we first need a comprehensive analysis of correlation between performance metrics and factors affecting the performance of AODV. Selected parameters based on this analysis make it enable to be a more accurate and fair performance analysis, as well as to reduce the time and effort when constructing a scenario for performance analysis. In this paper, various scenarios are configured to apply AODV by varying the values of factors affecting the performance with network simulator QualNet 5.0, and then the results are analysed using performance metrics proposed by IETF MANET working group. This paper also founds a correlation between performance metrics and factors affecting the performance for AODV routing protocol, choosing the values of factors that represent many of the most maximum and minimum values of each performance metrics, and proposes optimal simulation parameters for a more accurate performance evaluation of routing protocols with minimal scenario in experiments. Next, performance comparison of AODV, DSR and DYMO routing protocols based on the proposed simulation parameters is shown which provides a comparative analysis on the performance of on-demand routing protocols. Results of this paper could be very useful for the researcher or service provider who wants to find nice simulation environment or select a proper routing protocol.

• Journal of Nutrition and Health
• /
• 제22권4호
• /
• pp.275-289
• /
• 1989

The purpose of this study is to develop a computer system with data file and computerized programs for nutrition counseling. In this research, a 16 / XT personal computer (word : COBOL) compatible with IBM-PC/XT was used. Computer system developed for this study was as follows: Data files(food composition list, food exchange list, nutrition management comment, special diet therapy) were used for analysis the nutritional status and the ntrition education comment. (1) Programs for the nutritional status assessment 1) General information a) Name, age, sex, higher, weight, activity, disease and special diet b) Ideal body weight and Obesity assessment(Kaup index and Broca index) c) Rest and athletics status d) Biochemical data comparision with standard 2) Food Intakes 3) Nutrient Intakes a) Comparison of the amounts intaked with the recommended dietary allowances for present weight. b) Comparison of the energy composition rate intaked with the recommended dietary allowances for present weight. b) Comparison of the energy composition rate intaked with the recommended for present weight and ideal weight. c) Nutrient analysis by each meal and snack. 4) Food intakes from each food group and comparison with recommended 5) Special nutrient analysis. (2) Programs for the nutrition education based on nutritional status assessment. 1) Suggestion of number of food exchange group 2) Nutritional assessment and advise comments 3) Nutritional management comments 4) Special diet therapy In the study, the nutritioal status and nutrition education comments are based on individual data from nutrition counseling.

• Journal of Power Electronics
• /
• 제15권5호
• /
• pp.1380-1391
• /
• 2015

This paper provides a loss analysis and comparison of high power semiconductor devices in 5MW Permanent Magnet Synchronous Generator (PMSG) Medium Voltage (MV) Wind Turbine Systems (WTSs). High power semiconductor devices of the press-pack type IGCT, module type IGBT, press-pack type IGBT, and press-pack type IEGT of both 4.5kV and 6.5kV are considered in this paper. Benchmarking is performed based on the back-to-back type 3-level Neutral Point Clamped Voltage Source Converters (3L-NPC VSCs) supplied from a grid voltage of 4160V. The feasible number of semiconductor devices in parallel is designed through a loss analysis considering both the conduction and switching losses under the operating conditions of 5MW PMSG wind turbines, particularly for application in offshore wind farms. This paper investigates the loss analysis and thermal performance of 5MW 3L-NPC wind power inverters under the operating conditions of various power factors. The loss analysis and thermal analysis are confirmed through PLECS Blockset simulations with Matlab Simulink. The comparison results show that the press-pack type IGCT has the highest efficiency including the snubber loss factor.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2021년도 춘계학술대회
• /
• pp.563-565
• /
• 2021

최근 증가하는 콘텐츠 제공 서비스의 가장 큰 특징은 콘텐츠의 시간의 흐름에 따른 콘텐츠 증가량이 매우 크다는 것이다. 이에 따라 사용자 큐레이션의 중요성이 같이 증가하고 있으며 이를 구현하기 위한 여러 가지 기법들이 사용되고 있다. 본 논문에서는 영상 추천을 위한 기법 중 음성데이터 및 자막을 활용한 분석 기법과 키프레임 추출 기반 영상 비교 기법을 실제 빅데이터 영상 콘텐츠를 대상으로 구현, 적용한 결과에 대하여 비교한다. 또한, 비교결과를 통해 각 분석 기법이 적용될 수 있는 영상 콘텐츠 환경에 대하여 제안한다.

• 한국의류학회지
• /
• 제28권9_10호
• /
• pp.1219-1230
• /
• 2004

This study was conducted to compare the physical shapes of Korean males in their 20s between those residing in Yenbien, China and those living in Korea. Measurements were checked fur 57 items on 167 Korean male residents in Yenbien, China and 295 Korean male residents in Seoul and the other large cities around it. The conclusions are as follows: 1. The comparison of 58 items in physical measurements of Korean male residents in China and those in Korea showed differences in 49 items. Korean male residents in China had the smaller physical shapes short in limbs and height. 2. The comparison of the factor analysis results for physical measurements did not reveal big differences. In terms of the contribution of variables, however, obesity played an exceptionally large role fur Korean residents in China, while the importance of obesity and vertical length were similar for those in Korea. 3. The comparison of the physical shapes according to the grouping resulted in three types each for both groups, with different features for individual types. Korean residents in China were grouped according to the obesity factor rather than the changes in height, while those in Korea were classified according to both vertical length and obesity.

• 한국IT서비스학회지
• /
• 제21권2호
• /
• pp.43-59
• /
• 2022

This study investigates an association among Facebook users' upward comparison (e.g., envy), social support (e.g., favorable comments and like), and life satisfaction, putting their self-esteem as a mediating variable. For this analysis, 1,332 female and male Facebook users in Seoul and other four cities in South Korea were surveyed. Structural equation modeling including confirmative factor analysis were employed as quantitative analysis methods. Results show that Facebook users' upward comparison with other users and social support significantly impact their satisfaction mediated by their self-esteem. Specifically, when users feel envious of other users, this emotion lowers their self-esteem, and subsequently, the self-esteem reduces their satisfaction. On the other hand, sufficient social support for users positively affects their self-esteem, which leads to the increase of their satisfaction. The present study is differentiated from previous studies in that it focuses on Facebook users' emotional changes in the process of sharing massive amounts of posts and finds a stepwise relationship among their feelings, including self-esteem as a mediating variable. Additionally, this study is the first to verify a situation when Facebook users' envy of other users' posts affects the decline in their satisfaction through the mediation of their self-esteem.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 B
• /
• pp.1069-1071
• /
• 2003

This paper presents the loss analysis comparison for Three-Level Converter and Full-Bridge converter. The result of the analysis is verified with 2.5kW prototype.