• 대한전기학회논문지
• /
• 제39권9호
• /
• pp.903-911
• /
• 1990

When load areas on a feeder are deenergized due to faults and scheduled outage, operators need to identify neighboring feeders, try to restore customers and minimize out-of-service areas. These cases include knowledge of system states and various constraints such as voltage drop. This paper concerns the load transfer in fault restoration and scheduled outage. Also, the operating constraints such as line current capacity, relay trip current, transformer capacity, voltage drop and line loss are considered. This expert system can propose the optimal load transfer method by analyzing the system state and considering the constraints.

• 소성∙가공
• /
• 제18권1호
• /
• pp.20-25
• /
• 2009

A finite element analysis was carried out for a 4:1 planar contraction die for polymer melts using the viscoelastic constitutive equation of Leonov. Viscoelastic fluids showed significant differences in pressure drop and birefringence in contraction and expansion flows. The pressure drop was higher and the birefringence smaller in expansion than in contraction flow. The difference increased with increasing flow rate. The nonlinear Leonov model was shown to describe the viscoelastic effects observed in experiments.

• 한국방사성폐기물학회:학술대회논문집
• /
• 한국방사성폐기물학회 2017년도 춘계학술논문요약집
• /
• pp.155-156
• /
• 2017

In this study, the structural integrity of the spent nuclear fuel assemblies was evaluated by carrying out a 0.3 m drop impact analysis, one of the normal transportation conditions of the nuclear fuel assemblies. For this purpose, the spent nuclear fuel assembly was modeled in detail as beam elements, and a coupled model for impact analysis was developed by inserting the modeled nuclear fuel assemblies into a cask.

• 영재교육연구
• /
• 제24권5호
• /
• pp.757-780
• /
• 2014

본 연구에서는 학교중퇴를 선택했던 영재학생들 두 명을 대상으로 학교를 그만두기까지의 학교생활과 중퇴를 선택하게 된 요인을 알아보았다. 면담, 관찰, 문서 및 어린 시절 비디오 분석의 삼각측량 사례연구 결과, 첫째, 일반 학생들에 맞추어진 학교 학업에서는 많은 시간 기다려야 했고 지루했으며 특별히 기대했었던 과학영재교육원에서도 만족하지 못하였었다; 둘째, 다른 학생들과 관심을 갖는 부분이 달라서 흥미를 교류할 수 있는 친구가 없었다; 셋째, 일반학생들이 간과하는 문제들을 예민하게 받아들이고 남다른 정서적 민감성과 정의감으로 인하여 힘든 경험들이 있었다; 넷째, 이해해주지 않았던 학교 교사들과 부딪히면서 어려움을 겪은 경험이 있었다; 다섯째, 평범하지 않은 자녀를 위해 최대한 지원해주려고 노력하는 부모가 있다는 공통점을 찾을 수 있었다. 지적 정의적으로 도움이 필요한 영재학생들이 학교를 떠나게 됨으로써 학교환경과 영재교육원 교육이 다시 한 번 돌아볼 기회가 되었으며 특별한 관심과 배려가 필요할 것으로 사료된다.

• 한국의류산업학회지
• /
• 제25권2호
• /
• pp.241-247
• /
• 2023

This study sought to investigate the effect of academic satisfaction on the dropout intention of cosmetology undergraduates. Analyzing the effect of academic satisfaction on career dropouts showed that the sub-factors of academic satisfaction-evaluation satisfaction, class satisfaction had a statistically significant part effect. Analyzing the effect of academic satisfaction on psychological factors for dropping out showed that the sub-factors of academic satisfaction have a statistically significant effect. Furthermore, regarding the effect of academic satisfaction on environmental factors, the sub-factors of academic satisfaction have a statistically significant effect on wealth. High satisfaction was shown to have no statistically significant effect on dropout intention. The results of the study showed that the higher the degree of satisfaction with the evaluation and the degree of satisfaction with the course of beauty majors, the more negative (-) the impact on dropout. For cosmetology majors, academic satisfaction is a subjective emotion felt through study at university and major. Students with high academic satisfaction are more likely to love their school and their work, and positively influence their intention to stay in school and reduce student dropout rates. Intention to drop out indicates the intention to lose interest and purpose in cosmetology college students. This is directly linked to the dropout rate of school students and requires steady research. Through this research, we hope that active discussions will be held on academic satisfaction and intention to drop out of university students specializing in cosmetology.

• 한국산학기술학회논문지
• /
• 제18권5호
• /
• pp.531-542
• /
• 2017

강선이나 강화플라스틱선 등의 선박 재료는 선박안전법에 규정된 규격재료를 사용하는 경우로서 판두께 측정시험이나 종굽힘강도시험을 통하여 제작 선체의 구조 안전성을 쉽게 확인할 수 있다. 한편, 염가의 폴리에틸렌 등과 같은 비규격재료를 선체 전장이 짧은 플레저 보트의 선체로 사용하는 경우 역학적 특성을 파악하기 쉬워 선체 설계를 수행하기에 매우 유리하고, 대량 생산 시스템을 갖추는 경우 제작 비용이 낮아 해당 제품의 가격 경쟁력을 가질 수 있다. 그러나 폴리에틸렌 선체의 경우 비규격재료를 사용함에 따라 기존의 소형선체에 대한 종굽힘강도시험을 이용하여 선체의 구조 안전성을 평가할 수 없다. 이러한 문제점을 해결하기 위하여 본 연구에서는 플레저 보트의 낙하시험 표준절차인 플레저 보트 검사 기준과 ISO 12215-5를 기초로 폴리에틸렌 선체에 대한 낙하시험을 수행한 후 이것을 기초로 정적구조해석을 수행하여 비규격재료로 개발된 선체의 구조 안전성을 확인함으로서 플레저 보트 검사 기준과 ISO 12215-5의 낙하시험방법이 선체 구조설계에 이용될 수 있음을 보였다.

• 전기학회논문지
• /
• 제57권6호
• /
• pp.932-937
• /
• 2008

The transformer inrush current can cause a voltage drop by source impedance. This current can impact sensitive loads by the voltage drop. Therefore, it is necessary to take measures to limit this inrush current. This study, described in this paper, analyzes the power quality affected by transformer inrush current using the X power system in Korea. The Electromagnetic Transients Program(EMTP) is used to analyze the transient phenomenon. We discuss a method to model the hysteresis curve of the transformer in EMTP. We carried out various simulations to analyze the power quality during transformer energization. The analysis results of voltage drop by the inrush current occurrence when certain requirements are met are presented.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집D
• /
• pp.477-482
• /
• 2001

An experimental study on the performance evaluation of a brazed plate heat-exchanger with 10RT of normal cooling capacity has been carried out. In the present study, a brazed type plate heat exchanger was tested at a chevron angle $25^{\circ}$ with refrigerant R-22. Mass flux was ranged from $23\;to\;58kg/m^{2}s$ in condensation, and from $22\;to\;53kg/m^{2}s$ in evaporation. The heat transfer coefficient and pressure drop increased with the mass flux increases. The water side pressure drop increased with the cooling water flow rate and chilled water flow rate increases, while mass flux has little affect. It is also shown that the system performance can be improved by enlarging condensation heat transfer area.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.1046-1051
• /
• 2004

A plate-fin-tube heat exchanger used for a $SF_{6}$ gas-insulated transformer is extremely important since the dissipation of the heat generated from inside coils has a significant effect on the performance as well as the durability of the transformer. The heat exchanger consists of corrugated plate fins and staggered array tube bundles for coolant. In order to find out heat transfer and pressure drop characteristics, series of numerical analyses for plate fins with enhanced surface geometries were conducted. Based on the results of the numerical analyses, an improved model of the plate fin has been proposed.

• 한국소음진동공학회논문집
• /
• 제23권4호
• /
• pp.372-378
• /
• 2013

An acoustical shape optimization problem is formulated for optimal design of a perforated reactive muffler with offset inlet/outlet. The mean transmission loss value in a target frequency range is maximized for an allowed pressure drop value between an inlet and an outlet. Partitions in the chamber are divided into several sub-partitions, whose lengths are selected as design variables. Each sub-partition has the same number of holes, whose sizes are equal. A finite element model is employed for acoustical and flow analyses. A gradient-based optimization algorithm is used to obtain an optimal muffler. The acoustical and fluidic characteristics of the optimal muffler are compared with those of a reference muffler. Validation experiment is carried out to support the effectiveness of our suggested method.