• 한국분말재료학회지
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• 제13권5호
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• pp.340-350
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• 2006

Nanostructured materials exhibit attractive mechanical properties that are often superior to the performance of their coarse-grained counterparts. However, one major drawback is their low ductility, which limits their potential applications. In this paper, different strategies to obtain both high strength and enhanced ductility in nanostructured materials are reported for Ti-base and Zr-base alloys. The first approach consists of designing an in-situ composite microstructure containing ductile bcc or hop dendrites that are homogeneously dispersed in a nanostructured matrix. The second approach is related to refining the eutectic structure of a Ti-Fe-Sn alloy. For all these materials, the microstructure, mechanical properties, deformation and fracture mechanisms will be discussed.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.141-146
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• 2000

It has many variables and factors to design the friction materials for automotive brake pads. In this study, the friction and wear characteristics of automotive blake pads have been studied using 1:l full size dynamo meter. Using conventional manners, it takes a great of time and efforts to know that it affects the each raw materials for friction characteristics. For the purpose of examining the effect of each major raw materials, we used the more convenient Taguchi L9 ($3^4$) orthogonal matrix and 1/5 scale dynamo machine for evaluation of the friction characteristics of composite brake pads.

• 한국세라믹학회지
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• 제56권3호
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• pp.233-255
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• 2019

Thermal batteries are reserve batteries with molten salts as an electrolyte, which activates at high temperature. Due to their excellent reliability, long shelf life, and mechanical robustness, thermal batteries are used in military applications. A high-performance cathode for thermal batteries should be considered in terms of its high capacity, high voltage, and high thermal stability. Research progress on cathode materials from the recent decade is reviewed in this article. The major directions of research were surface modification, compounding of existing materials, fabrication of thin film cathode, and development of new materials. In order to develop a high-performance cathode, a proper combination of these research directions is required while considering mass production and cost.

• Elastomers and Composites
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• 제53권4호
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• pp.220-225
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• 2018

Resilient pads play a major role in reducing the impact of loads on a rail in a rail-fastening system, which is essentially used for a concrete track. Although a compression set test is commonly used to measure the durability of a resilient pad, the static spring constant is often observed to be different from the fatigue test. In this study, a modified compression set test method was proposed to monitor the variations in the compression set and static spring constant of a resilient pad with respect to temperature and time. In addition, the life of the resilient pad was predicted by performing an acceleration test based on the Arrhenius equation.

• 소성∙가공
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• 제11권8호
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• pp.668-675
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• 2002

The circles deform into various shape during deformation, the major and minor axes of which indicate the direction of the major and minor principal strains. Likewise, the measured dimensions are used to determine the major and minor principal strain magnitudes. This circular grid technique of measuring strains can be used to diagnose the causes of necking and fracture in industrial practice and to investigate whether these defects were caused by material property variation, changes in lubrication, of incorrect press settings. In non-axisymmetric deep drawing, three modes of forming regimes are found: draw, stretch, plane strain. The stretch mode for non-axisymmetric deep drawing could be defined when the major and minor strains are positive. The draw mode could be defined when the major strain is positive and minor strain is negative, and plane strain mode could be defined when the major strain is positive and minor strain is zero. Through experiments the draw mode was shown on the wall and flange are one of a drawn cup, while the plane strain and the stretch mode were on the punch head and the punch corner area respectively, We observed that the punch load of elliptical deep drawing was decreased according to increase of die corner radius and the thickness deformation of minor side was more large than major side.

• Preventive Nutrition and Food Science
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• 제10권1호
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• pp.103-110
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• 2005

Opuntia ficus-indica, commonly known as prickly pear cactus, is commercially grown as a food and medicinal plant in Jeju Island, Korea. The crushed pads and fruits of Opuntia ficus-indica were dried in a freeze-dryer and ground into flour to be used for food materials. The major components of proximate compositions were part of a nitrogen free extract. The major minerals were Ca (4391.2-2086.9㎎%), K (1932.1-2608.7㎎%), and Mg (800.6-1984.8㎎%). The major amino acid was glutamic acid, comprising 16.3% of total amino acids in fruit and 25.2% in pad. Dihydroflavonols were identified as (+)-trans-dihydrokaempferol and (+)-trans-dihydroquercetin. Citric acid methyl esters extracted from fruits showed inhibitory activities against monoamine oxidase-B. The presence of trimethyl citrate has been reported in other plants, but 1,3-dimethyl citrate and 1-monomethyl citrate have not been previously reported. The results of pharmacological efficacy tests, including serum biochemical and hematological parameters, autonomic nervous system, anti-inflammatory, analgestic activity, anti-diabetic activity, antithrombotic, anticoagulant, dopamine beta-hydroxylase, monoamine oxidase activity, hyperlipidemia, the respiratory system, antigastic, and anti-ulcerative actions indicate that the fruit and pad of the Opuntia ficus-indica are rich sources of food and medicinal materials.

• 한국식품저장유통학회지
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• 제4권3호
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• pp.279-286
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• 1997

The effect of drying temperature (30, 40, 50, 60$^{\circ}C$) on chemical components of Shiitake mushroom(Lentinus edodss) was investigate. When compared proximate composition on pileus and stipe of raw and dried materials, all of them were found to be higher in the stipe part than in the pileus part. The major components of organic acid were oxalic, citric, malic, malonic and pyroglutaric acid. The contents of free and total amino acids in pileus and stipe were 3458.4, 7640.2mg% for pilueus; 2298.0, 6171.5mg% for stipe on dry basis, respectively. On the other hand, there was no significant difference in the changes of crude ash and organic acids content of Shiitake mushroom among drying temperatures. But the amount of crude fats was increased and that of reducing sugars was decreased with increase of drying temperature. The contents of crude proteins of pileus part of dried materials were increased with increased drying temperature, but those of stile part were gradually decreased. The contents of free amino acids decreased with increase in drying temperature, but those of total amino acids were gradually increased.

• 한국실천공학교육학회논문지
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• 제2권1호
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• pp.126-134
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• 2010

공업계 고등학교의 금속재료 교과목 중에 재료시험법은 과학기술이 급격히 발전하는 것에 비해 교육수준이 시대에 뒤떨어지고 있다. 특히 기존의 파단면 해석방법보다 훨씬 진일보된 장비와 기술력으로 해석이 가능한 Fractography기법 도입의 필요성이 부각되고 있다. 이런 Fractography의 중요성과 해석방법을 중수로 압력관 재료를 이용하여 파단면의 특성을 정성적으로 해석을 통하여 입증하였다. 추후 공업계 고등학생들의 전문성을 늘이고, 자긍심을 함양하기 위해서 이런 최신 교과내용을 포함해야 할 것이다. 이런 교과내용을 현존하는 과학기술과 맞추는 작업은 주무행정기관에 의해 이루어지기 전에 일선 교사들의 자발적인 참여에 의해 수행될 필요성이 있다고 생각된다.

• 동력기계공학회지
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• 제17권2호
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• pp.108-113
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• 2013

In this study, lightweight aggregate was made from basalt stone powder sludge. Clay and glass powder were respectively added from 0 to 20 wt% and from 0 to 100 wt%. The glass powder helped to form glassy phase which trapped generating gas in the materials. $CaCO_3$ helping bloating process was added from 0 to 10 wt%. It was possible to produce lightweight aggregate at range from $1150^{\circ}C$ to $1200^{\circ}C$. The specimen was heated in furnace at 1100, 1150 and $1200^{\circ}C$ for 15 min, respectively, to sinter aggregates. Chemical composition of materials were determined, and characteristics were analyzed, including specific gravity, water absorption. Lightweight aggregate which was heated at $1200^{\circ}C$ had specific gravity of $0.53g/cm^3$, water absorption of 3.08%, and this value satisfied KS L 8551 standard.

• 복식문화연구
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• 제12권5호
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• pp.743-756
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• 2004

The purpose of this study is to set measurement parts which are important to identify the size and shape of the head in order to produce tightly fitted hats, and to identify detailed sizes and the major factors of head shape classifications of Korean women. A total of 285 Korean women's in the age group of 18 to 35 years old. It were measured through the direct measurement method by selecting 67 measurement items. Materials were analyzed by SPSS Ver.10 and technology statistics and factor analysis were performed according to the agenda. An attempt was made to conduct factor analysis of the measured region of the head in women's. Here, this study drew the head and the facial parts horizontal size as Factor 1, the head and facial parts vertical size as Factor 2, the circumference and width item as Factor 3, the factor representing the form of head height as Factor 4, the factor expressing the proportion of the facial form as Factor 5 and the factor about the frontal and back head form on the plan of the middle as Factor 6. Through this study, we will be able to systemize head measurement materials that can differentiate Korean's head from other peoples' and can use the results in developing head shape models according to Korean's head shape by selecting major head parts needed to identify the sizes and shapes.