• Communications for Statistical Applications and Methods
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• v.23 no.5
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• pp.399-409
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• 2016

Many of studies have suggested the modifications on Weibull distribution to model the non-monotone hazards. In this paper, we combine two cumulative hazard functions and propose a new modified Weibull distribution function. The newly suggested distribution will be named as a new flexible Weibull distribution. Corresponding hazard function of the proposed distribution shows flexible (monotone or non-monotone) shapes. We study the characteristics of the proposed distribution that includes ageing behavior, moment, and order statistic. We also discuss an estimation method for its parameters. The performance of the proposed distribution is compared with existing modified Weibull distributions using various types of hazard functions. We also use real data example to illustrate the efficiency of the proposed distribution.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.209-213
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• 2005

To enhance the reliability of distribution transformers in service and to reduce the cost of maintaining and replaceing these, the condition and life of those insulating system should be evaluated accurately and the time to replace should be determined economically. Since the transformer failures related to insulation failure indicates that the primary cause is normally mechanical failure of integrity due to loss of mechanical strength as a result of degradation, the tensile strength characteristics of paper during ageing under accelerated conditions in insulating oil and research trends for assessing the life of insulating paper were investigated.

• Fashion & Textile Research Journal
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• v.14 no.2
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• pp.184-192
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• 2012

This study analyzed silhouette expressions in the fashion illustrations by theory based on results of studying the characteristics of the forms and meanings of the silhouette expressions in art historically. For the actual considering this study collected and categorized fashion illustrations from 1990 to the present limitedly, and clarified the meaning of the silhouette expressions. Those expressions in fashion illustrations were categorized to the 5 items; black & white silhouette, color silhoutte, pattern silhouette, paper silhouette, line silhouette. Silhouette expressions of the fashion illustrations were categorized to 3 items: metaphorical fantasy, essential minimization, anonymous representation.

• Journal of the Korean Ceramic Society
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• v.30 no.7
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• pp.563-570
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• 1993

Spherical, monosized gadolinium compound was prepared by the reaction of Gd(NO3)3 solution with decomposition products of urea in the solution at evaluated temperature. Chemical composition and calcination characteristics of spherical gadolinium compound prepared were investigated by X-ray IR and TG-DTA. The approximate chemical composition of the spherical particle precipitated was Gd(OH)CO3.1.5H2O. Gd(OH)CO3.1.5H2O was calcined to monoclinic type Gd2O3 at 115$0^{\circ}C$ via cubic type Gd2O3 near $600^{\circ}C$. The effects of various parameters such as pH, temperature, concentration ratio of urea to gadolinium precusor, ageing time, and others material (CCl3COOH and HOCNH2) in stead of urea as precipitating agent on the properties of the resulting precipitates were studied systematically.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.239-244
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• 2001

Natural clayey soils or improved grounds are in a overconsolidated conditions due to changes in vertical stress and pore pressures, desiccation, ageing and so on. These grounds show inelastic stress-strain behaviour characteristics within all range of strain except very small strain (${\gamma}$$\_$s/$\leq$10￣$^3$∼10￣$^4$%) when construction, such as excavations and retaining walls, is performed. Also it strongly depends on loading rate of current stress path and recent stress path. This study carried out drained stress path tests by varying loading rate of current and recent stress path. Test results indicated that stress-strain behaviour of overconsolidated clay depends on loading rate, especially loading rate of current stress path.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.148-149
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• 2017

Recently, South Korea is reaching aged society through ageing society. Accordingly, facility related to aged is increased consistently because of effort to improve the welfare of the elderly through elderly long term care insurance in 2008. however, the number of fires in the elderly facilities is increasing rapidly too. It is becoming bigger and higher and the characteristics of person who is unable to afford are mostly having difficult evacuation. so fire safety guildelines are urgently needed but korea research is insufficient. In this study, we propose a fire scenario through investigation of fire causes for fire safety guideline development of elderly facility, and describe to the fire safety countermeasure.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.485-487
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• 2000

Dielectric strength of insulators made of epoxy composites rapidly decreases due to ageing to interfaces between the matrix resin and filler particles. The adhesion variation of interfaces caused by moisture absorption also alters electrical properties that are the basic characteristics of insulators, particularly, in out door use. In this paper, electrical properties of epoxy/$SiO_2$ composites were investigated at boiling absorption condition to observe that influence of moisture. The breakdown time of samples were measured under AC 6[kV] applied voltage, and the variation of lifetime was varified by using Weibull distribution function.

• Journal of information and communication convergence engineering
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• v.1 no.2
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• pp.70-73
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• 2003

We have studied the effects of solvents and additives in the precursor solutions on the characteristics of barium strontium titanate (BST) thin films. The solution having two solvents, ie. acetic acid for barium acetate and strontium acetate and 2-methoxyethanol for titanium isopropoxide and also having an additive of ethylene glycol shows good stability and remains homogeneous even after a month of ageing. It produces excellent BST thin film without cracks. Dielectric constant, loss tangent at 10KHz and leakage current density at 3V of the BST (70/30) thin film made from this solution are 339, 0.052 and 13.3 ${\mu}\textrm{A}$/$\texmrm{cm}^2$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.454-455
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• 2007

송전용 자기 애자에 대하여 산물화염 특성과 송전선로의 환경 검토를 토대로 송전용 절연물에 대한 산불화염 열화특성을 1)내열충격 열화와 2) 열충격 싸이클 열화로 나누어 가속시킨 후 절연물의 성능을 시험 평가하였다. 또한 승전용 자기애자 (254mm, 36,000lbs)를 대상으로 실제 삼불열화 조건을 근간으로 기계적, 열적 환경을 고려한 자기애자의의 수축, 팽창 변위에 따른 계면의 응력거동을 열충격 및 내열충격 시험의 결과와 비교 분석하였다.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.230-234
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• 2008

Urban Railway was used importantly with transport for several decades. This transportation facilities used electricity. When the breakdown occurs, social, the economic loss is enormous. In addition to, the power equipment was ageing. We need preventive diagnostic monitoring system in order to prevent breakdown of power equipment. In this paper, we investigates characteristic and breakdown type of the Urban Railway power equipment. Through the this research, we can contribute in the operation which power equipment is efficient of the Urban Railway.