• Journal of the Korean Applied Science and Technology
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• v.40 no.6
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• pp.1298-1308
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• 2023

This study collected 245 questionnaires from college students in Gyeonggi-do and analyzed them using SPSS statistical packages, with the aim of identifying the status of hair loss perception due to the relationship between stress and hair loss received by college students and analyzing the correlation between stress and hair loss perception by type. As a result of the study, it was analyzed that the biggest problem caused by hair loss was 'loss of confidence', and in particular, people who were stressed about career/employment and studies were analyzed to consider the problem of 'loss of confidence' the most serious. As a result of cross-analysis of the general characteristics of awareness and the 'most recent stress' item, and as a result of correlation analysis between stress by type and hair loss status that constitutes hair loss awareness, it was analyzed that all types of stress affect hair loss in college students. Among them, career/employment stress and academic stress were found to be the most influential stress, and in the event of hair loss, it was analyzed that they were more willing to engage in hair loss treatment for career/employment, study, and appearance before interpersonal relationships or economic problems. Therefore, this study is of great significance in that it classified stress by type and analyzed the correlation through empirical research methods by specifying the contents of hair loss recognition into three categories: hair loss status, hair loss management, and hair loss treatment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.924-931
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• 2008

This paper presents a buswise transmission loss allocation algorithm utilizing the transaction strategy. We prove that whatever calculated by any transaction strategy, the total of the allocated transmission losses of each bus, including no-load loss allocation, almost equals the total loss of AC power flow algorithm and the loss is perfectly slackbus-independent. In this paper, the allocated transmission losses of each bus is calculated by the method of integrating loss sensitivities using by the load level parameter ${\lambda}$. The performance of the proposed algorithm is evaluated by the case studies carried out on the WSCC 9-bus and IEEE 14-bus systems.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2168-2180
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• 2014

In this paper, a generalized power loss algorithm for multilevel neutral-point clamped (NPC) PWM inverters is presented, which is applicable to any level number of multilevel inverters. In the case of three-level inverters, the conduction loss depends on the MI (modulation index) and the PF (power factor), and the switching loss depends on a switching frequency, turn-on and turn-off energy. However, in the higher level of inverters than the three-level, the loss of semiconductor devices cannot be analyzed by conventional methods. The modulation depth should be considered in addition, to find the different conducting devices depending on the MI. In a case study, the power loss analysis for the three- and five-level NPC inverters has been performed with the proposed algorithm. The validity of the proposed algorithm is verified by simulation for the three-and five-level NPC inverters and experiment for three-level NPC inverter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.3
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• pp.33-38
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• 2010

In this paper, the nature of iron loss in electrical steel during alternating field excitation is investigated more precisely. The exact definition of AC iron loss is cleared by accurately measuring the iron loss for conditions of both the sinusoidal magnetic field and sinusoidal magnetic flux density. The results of this approach to iron loss calculations in electrical steel are compared to experimentally-measured losses. In addition, an inverse hysteresis model considering eddy current loss was developed to analyze the iron loss when the input is the voltage source. With this model, the inrush current in the inductor or transformer as well as the iron loss can be calculated.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.1
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• pp.15-19
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• 2005

This paper analyzed the power loss characteristics according to winding thickness and winding method of high frequency transformer. Power loss was analyzed by PExprt using FEM tool. The ferrite core model for analysis be used the EE10 type of TDK cop.. Transformer model objected flyback transformer type applied to flyback converter/inverter. Therefore, analysis results of loss were obtained from inner parameters of DC, AC resistance, leakage inductance, copper loss, core loss, and temperature etc.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.169-171
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• 2001

The transport loss of a Bi-2223 tape exposed to external magnetic field was investigated. The results show that the transport loss is independent on voltage lead arrangements in case the magnetization loss is compensated. An serious increase of the transport loss due to external magnetic fields is observed. The loss is described well by dynamic resistance loss in relatively high fields, but another mechanism than the dynamic resistance must be responsible for the increase of the loss in low fields. The transport loss is also dependent strongly on the orientation of the applied field.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.7
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• pp.333-339
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• 2001

The transmission networks are not perfect conductors and a percentage of the power generated is therefore lost before it reaches the loads. This network loss effects to the cost of suppling power to consumers, and must be considered if the most efficient dispatch and location of generators and loads is to be achieved. In this paper, we propose an approximate calculation of marginal loss factors to analyze characteristics of transmission loss of KEPCO power system. These static marginal loss factors are approximately calculated based on the KEPCO's expected summer peak load data of year 2000.

• The Korean Journal of Community Living Science
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• v.27 no.3
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• pp.405-418
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• 2016

This study was conducted to explore the influences of loss experiences and depression on ego-integraty and transcendence of elderly Koreans and to identify gender differences in the relationships among loss experiences, depression, ego-integrity, and transcendence from 146 men and 194 women aged over 60 years in Busan, Gyeong-Nam, and Gyeong-Buk area. The main results were as follows: elderly men reported more loss experiences and transcendence than elderly women. Next, loss experiences influenced ego-integrity and depression mediated the relationship between loss experiences and ego-integrity. Also, ego-integrity had a direct effect on transcendence. Last, depression of elderly men fully mediated the relationship between loss experiences and transcendence. The relationship between loss experiences and ego-integration was partially mediated by depression for elderly women. These results were discussed in terms of gero-education and elderly welfare.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.102-109
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• 2005

In this study, a prototype model of earthquake loss estimation method will be proposed for the quantitative and qualitative damage evaluation of buried pipeline subjected to Permanent Ground Deformation(PGD) due to liquefaction. With this objective, domestic and foreign status of the arts related with earthquake loss estimation method is summarized at first. Domestic development of computer aided earthquake loss estimation method seems to be difficult for the time being. Thus, referring to HAZUS : Earthquake Loss Estimation Methodology which is developed by FEMA (Federal Emergency Management Agency) and NIBS (National Institute of Building Sciences), earthquake loss estimation procedure of buried pipeline subjected to PGD due to liquefaction are proposed, and then exemplary loss estimation are executed. Considering that there have been no practical earthquake loss estimation method and procedure in Korea, the research accomplishments such as above are considered to be helpful for the substantial development of earthquake loss estimation method of buried pipeline subjected to PGD due to liquefaction.

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.619-625
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• 2006

Amount of soil loss is important information for the proper water quality management, In this research, annual average soil loss of the Geum River basin was estimated using RUSLE (Revised Universal Soil Loss Equation) and GIS (Geographic Information System). Input data were manipulated using ArcGIS ver. 8.3. From crop field which constitute 8.2% of the Geum River Basin, annual average soil loss was estimated as 53.6 ton/ha/year. From the rice paddy field which constitutes 20% of the Geum River Basin, soil loss was estimated as 33.5 ton/ha/year, In comparison, forestry area which constitutes 61.8% of the basin discharged 2.8 ton/ha/year, It could be known from this research that appropriate measures should be implemented to prevent excessive soil loss from the agricultural areas.