• 한국컴퓨터정보학회논문지
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• 제23권5호
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• pp.65-72
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• 2018

This study analyzes college dropout cases to reduce its rate. The analysis is preferentially carried out by figuring out our current situation of college dropout rate in pertinent cases and all around country's. Based on the current states, statistical analysis is accomplished as follows; analyzing the characteristic differences between the being in school's and the dropouts' by T-Test, determining the influence factor by logistic regression analysis and drawing the target group for special treatments through these statistical analysis. To reduce dropout rate, several measures could be adopted; focused counseling for each target group, special monitoring for students on leave of absence and opening major subjects for improving relationship between students and professors. The measures suggested by the analysis through this study are expected to lower the dropout rates effectively in college or specific fields including engineering science.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.96-98
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• 2003

Many of research efforts have been focused on the improvement of critical current density Jc of silver-sheathed Bi-2223 tapes for practical applications of material. Bi-2223 superconducting wires with 55 filaments were fabricated by stacking, drawing process with different heat-treatment histories. After rolling process, Bi-2223 tapes were heat-treatment at 780~826$^{\circ}C$ with variable mass flow rate of mixed gas. In this study, the effect of changes in the variable mass flow rate of mixed gas during the heat treatment of Bi-2223/Ag tapes has been investigated. Distinct differences were observed in the Bi-2223 phase and critical current as flow rate of mixed gas. We could achieve proper conditions of mass flow rate of mixed gas for Ag-alloy clad Bi-2223 superconducting tapes.

• 폴리머
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• 제26권3호
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• pp.335-343
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• 2002

블렌드 (PET/PETG 70/30 블렌드) 수지는 폴리에틸렌테레프탈레이트 (PET)와 폴리에틸렌테레프탈레이트 글리콜 (PETG)을 무게 비 70/30으로 혼합하여, 이축 압출기를 사용하여 제조하였다. 미연신 필름은 이 블렌드와 순수 PETG 수지를 압축성형기로 각각 용융 압축시켜 제조하였고 연신 필름은 미연신 필름을 모세관 레오메타를 사용하여 연신시켜 제조하였다. 제조된 블렌드 연신 필름과 PETG 연신 필름의 결정성, 수축율, 열적, 동역학적 및 기계적 특성을 X-선 회절분석기, 오븐기, DSC, 및 인장시험기를 사용하여 조사하였다. 블렌드와 PETG필름의 결정화도와 밀도는 연신비와 연신 속도의 증가와 더불어 증가하였으나 반면 연신 온도 증가와 더불어 감소하였다 또한 블렌드 필름의 결정화도와 밀도는 PETG 필름보다 높게 나타났다. 두 필름의 인장강도와 인장탄성률은 연신비 및 연신 속도 증가와 더불어 증가하였고 연신온도 증가에 따라 감소하였다. 또한 블렌드 필름의 인장강도와 인장탄성률이 PETG 필름 보다 높게 나타났다. 두 필름의 수축율은 연신비와 연신 속도가 증가할수록 감소하였고 미연신 블렌드 필름의 수축율이 순수 PET 필름보다 600% 증가함을 보였다.

• 한국주거학회논문집
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• 제18권3호
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• pp.63-72
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• 2007

The purpose of this study is to identify the impact of the building, site, and region characteristic factors on the annual average price rising rate of apartment housing in Seoul. The data were consisted of 272 apartment units in Seoul. A survey included checking the drawing documents and interview with apartment maintenance staffs and real estate agencies from October 2006 to February 2007. Data were analyzed with descriptives, frequency, crosstabs, and linear regression by SPSS/PC for Window. The linear regression model was employed to evaluate the price rising rate in apartment housing. Following results were obtained. The price rising rate for pyeong ($3.3m^2$) of apartment housing was determinated by the district zone, the construction company's brand name, the building age, the building stories, the floor space index, the building-to-land ratio, the green space rate, and the distance from the downtown. Especially, the district zone was the most important factor that affected the price rising of apartment housing in Seoul. Therefore, the policy has to focus to solve the imbalance between autonomous districts with the collaborated tax.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1191-1196
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• 2009

The T-s chart of air displays graphically the thermophysical properties, so it is very conveniently used in various thermal systems. In previous study, the software analyzing 31 kinds of values in water system and 32 kinds of values in air-conditioning system were developed. In this study, the software drawing 13 kinds of quantity of state on air properties as ideal gas and analyzing 25 kinds of values in any air system was developed. The 13 kinds of quantity of state on air properties are temperature, pressure, specific volume, specific internal energy, specific enthalpy, specific entropy, specific exergy, exergy ratio, density, isobaric specific heat, isochoric specific heat, ratio of specific heat, and velocity of sound, and the 25 kinds of values including 13 kinds are mass flow rate, volume flow rate, internal energy flow rate, enthalpy flow rate, entropy flow rate, exergy flow rate, heat flow rate, power output, power efficiency, reversible work, lost work, and relative humidity. The developed software can draw any range of chart and analysis any state or process on air system. Also, this supports various document-editing functions such as power point. We wish to this chart is a help to design, analysis, and education in air system field.

• 품질경영학회지
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• 제26권4호
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• pp.51-64
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• 1998

Mean shifts may be found in tool wear in machining, drawing, stamping and moulding operations, which make the process quality level deteriorate over time. In such situations, it is necessary to reset or readjust the manufacturing process at regular time basis or by inspection to prevent defective items produced. Although the deterioration rate may be assumed to be linear in a production cycle, there are many cases where the rate varies after resetting due to the variation of tool characteristics or by using the resharpened tools. In such cases, the deterioration rate should not be assumed to be a deterministic constant but a random variable. This paper is to find an optimal resetting period and quality level for such production processes.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.73.1-76
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• 2003

Recently, as the alternatives to preserve environment such as effective usage of wastes or unusable resources are drawing attentions, researches and measures for the two tasks, which are reuse of waste wood and development of eco-friendly materials, are being examined and established in various fields. However, they are still insufficient. Therefore, in this study, for the efficient application of waste woods and eco-friendly effects, mortar was produced using sawdust as the waste wood and mineral material cement for combination, in order to produce inorganic boards using waste woods. which were made when sawing. This study attempted to suggest a basic material about the physical properties of mortar, which used waste woods, after examining the features of wood mixture rate, water-cement rate, consolation according to the mixture rate of the setting accelerator, specific gravity, compression intensity, and bending intensity as experiment factors.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 박판성형기술의 진보
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• pp.11-23
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• 1994

Formability of sheet metals can be evaluated using tensile testing. Easily measured tensile properties such as yield strength, tensile strength, elongation, strain hardening exponent, strain rate sensitivity and plastic strain ratio are important parameters to evaluated the sheet formability. This paper briefly explains how these properties are related to deep drawability and stretchability. The plastic anisotropy of sheet metals is usually attributed to the crystallographic texture. However dislocation distribution may influence the anisotropy.

• 한국산업정보학회논문지
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• 제11권4호
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• pp.93-104
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• 2006

본 논문은 도면관리 시스템과 BOM 시스템간의 데이터 공유를 통하여 효과적인 BOM산출을 시도하였다. 본 논문에서는 이러한 목적을 달성하기 위해서 본 논문에서는 CAD도면을 이용한 컴포넌트 기반 소프트웨어 시스템을 구현하였다. 본 연구의 결과로는 BOM 산출을 하는데 있어서 여러 번의 시행착오를 거쳐야하는 문제점들을 현저히 감소시켰다. 특히 본 연구의 결과로는 BOM의 산출 기간이 2주에서 2일로 단축되었으며, BOM 산출의 정확도는 95%에 도달하였다. 본 논문에서는 이 이외에도 다음과 같은 효과를 가져왔다. 첫째, 컴포넌트 개발 방법으로 인한 프로그램의 재사용성, 유지/보수 및 수정의 용이성 둘째, 웹 기반 개발 기법으로 인한 원격지에서의 시스템 운영 가능, 셋째, 이미지 및 텍스트 데이터베이스 구축으로 인한 데이터 관리의 효율화 넷째, 도면관리의 체계화, 다섯째, 회사에 적합한 맞춤형 BOM시스템 구현 등이다.

• 전기화학회지
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• 제9권1호
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• pp.29-33
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• 2006

A new porous separator based on poly(vinyl chloride) (PVC)/poly(vinylidene fluoride-co-hexafluoro-propylene) (P(VdF-co-HFP)/poly(methyl methacrylate) (PMMA) was prepared by a phase inversion method. To enhance mechanical property, the membrane was stretched uniaxially at high temperature. Tensile strength and ionic conductivity were measured for various draw ratios. The tensile strength and ionic conductivity were increased with increasing draw ratio. The tensile strength of the separator reached 52MPa after stretching to draw ratio of 5, and the ionic conductivity of the separator was increased from $1.9Xs10^{-4}S/cm\;to\;4.6X10^{-4}S/cm\;at\;25^{\circ}C$. The stretched separator immersed in liquid electrolyte was electrochemically stable up to 4.7 V. The cell based on the stretched separator was maintained at about 99% of the initial discharge capacity after 10th cycle operation at 0.2C rate.