• 전기학회논문지
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• 제67권12호
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• pp.1633-1640
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• 2018

Epoxy resin is a polar thermosetting polymer that is widely employed in different branches of industry and everyday life, due to their stable physical and chemical properties. Of all the polymer materials currently being used in the electrical insulation industry, epoxy resin is the most widely used kind, chosen as the base polymer material in the present study. Composites were prepared according to the mixing ratio (MS: MA, 1: 9, 3: 7, 5: 5, 7: 3, 9: 1)of mixture for Heterogeneous Minerals(Micro Silica:MS, Micro Alumina:MA) (MS+MA). We have investigated for AC electrical insulation breakdown characteristics and the dielectric properties (permittivity, dielectric loss, and conductivity) with frequency changes. The electrical AC insulation breakdown performance was improved with the increase of the mixing ratio of MS according to heterogeneous mineral material mixture(MS+MA). As Dielectric properties, the dielectric constant and dielectric loss increased with decreasing frequency and decreased with increasing MS content ratio of heterogeneous mineral mixture. Tensile strength and flexural strength according to the mixing ratio (MS + MA) of epoxy / heterogeneous mineral mixture were studied by mechanical properties. The performance of mechanical tensile and flexural strength was significantly improved as the fill contents ratio of MS increased.

• Geomechanics and Engineering
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• 제37권2호
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• pp.149-166
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• 2024

The acoustic emission (AE) technique is utilized to estimate the rock failure status in underground spaces. Understanding the AE characteristics under loading conditions is essential to ensure the reliability of AE monitoring. The AE characteristics depend on the material properties (p-wave velocity, density, UCS, and Young's modulus) and damage stages (stress ratio) of the target rock mass. In this study, two groups of granite specimens (based on the p-wave velocity regime) were prepared to explore the effect of material properties on AE characteristics. Uniaxial compressive loading tests with an AE measurement system were performed to investigate the effect of the rock properties using AE indices (count index, energy index, and amplitude index). The test results were analyzed according to three damage stages classified by the stress ratio of the specimens. Count index was determined to be the most suitable AE index for evaluating rock mass stability.

• 자원리싸이클링
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• 제25권1호
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• pp.40-47
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• 2016

니켈 산화광인 라테라이트광은 건식제련 원료인 사프로라이트광과 습식제련 원료인 리모나이트광으로 구성되어 있다. 사프로라이트광이 혼재된 리모나이트광을 습식제련용으로 사용할 경우 무기산 소모량이 증가할 뿐만 아니라 슬러지 발생량이 증가하여 공정비용을 증가시키는 단점이 발생한다. 이러한 이유로 니켈 리모나이트광은 Si+Mg함량 10% 이하, Fe 함량 40% 이상이어야 습식제련 원료로 사용하기 적합하다. 본 연구에서는 뉴칼레도니아산 니켈 라테라이트광을 대상으로 습식제련 원료인 리모나이트광을 분리선별하는 연구를 수행하였다. 뉴칼레도니아산 니켈라테라이트광의 입도에 따른 광물성분 및 화학성분 변화를 규명하여 분급에 의한 사프로라이트 및 리모나이트의 광물간 분리선별 가능성을 확인하였다. 뉴칼레도니아산 니켈 라테라이트 원광(함수율 23.0%) 및 니켈 라테라이트 건조광(함수율 9.1%)을 핀밀을 이용 해쇄한 후 건식분급한 결과, 니켈 라테라이트광을 함수율 9% 수준으로 건조할 경우 분급효율이 높아지는 것을 확인하였다.

• 한국환경과학회지
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• 제7권3호
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• pp.269-274
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• 1998

In order to develop of support medla for bloom reactor, physicochemical properties and attachability of surface of activated carbon, clay mineral, non-clay mineral, and waste mold sand were enamined. Measured physicochemical properties of materials were surface roughness, mean particle size, surface area, hydrophobicity, and surface charge. At a tested materials, activated carbon was the best attachable material and microorganisms were attached $20.1{\times}10^7CFU/cm^2$ at surface, compared with diatomaceous earth which were attached of $9.2{\times}10^7CFU/cm^2$ in our research, surface area and hydrophobicity show- ed more Influence than any other factor on attachment of microorganisms.

• 전기학회논문지
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• 제60권5호
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• pp.984-989
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• 2011

Electrical insulation is one of the most important part in a high voltage apparatus. Recently, researchers are interested in the environmental friendly vegetable oil from environmental viewpoint. Accelerated aging transformer insulating material in vegetable oil was compared to that of mineral oil. Accelerated aging oil samples produced in the oven at $140^{\circ}C$ for 500, 1000, 1500, 2000hours. And Real transformer insulation oils samples of vegetable oil and mineral oil were aged by thermal cycles repeating from $30^{\circ}C$ to $120^{\circ}C$. Samples were analyzed at 42, 63, 93, 143, 190, 240, 300 cycles. The mineral and vegetable insulating oils were investigated for breakdown voltage, water content, total acid number, viscosity, volume resistivity, insulating paper and oil permittivity, and dissolved gas analyses. The breakdown voltage of the vegetable insulating oil is higher than that found for the mineral oil; the accelerated aging progress decreased the breakdown voltage. The vegetable oil had a higher water saturation than the mineral oil; the vegetable oil has the superior water characteristics and breakdown voltage. And high viscosity of vegetable oil, care has to be taken, especially when designing the cooling system for a large transformer.

• 여성건강간호학회지
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• 제14권1호
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• pp.12-19
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• 2008

Purpose: This study was to identify the influencing factors in postmenopausal women's bone mineral density (BMD). Method: The sample for the study was 107 postmenopausal women who took the BMD test. For BMD measurement, lumbar spine BMD(L2-5) was measured by Dual-energy X-ray absorptiometry(DEXA). Data was collected by questionnaires on the selected variables such as reproductive factors and life style factors. Result: In reproductive factors, parity shows significant differences with BMD (F=4.16, p=.02). In life style factors, diet (F=3.01, p=.05) and exercise (F=7.39, p=.00) show significant differences with BMD. Excercise, diet and parity accounted for 42.0% of the influencing factors in Postmenopausal Women's Bone Mineral Density. Conclusion: The influencing factors in postmenopausal women's bone mineral density were excercise, diet and parity. In this paper, it is suggested that the influence of reproductive and life style factors in postmenopausal women's BMD should be studied by long term and needs repeated research. This study can be used as foundation material for nursing education program development for osteoporosis prevention and improvement.

• 한국염색가공학회지
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• 제24권4호
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• pp.270-280
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• 2012

This study examined the dyeing characteristics of five oriental herbs, namely Gardenia jasminoides, Sophora japonica L., Rheum coreanum, Rhus javanica L., Ginkgo biloba L., on fabrics with traditional fermentation using malt. And the properties of Hwangsu (mineral water) of Yeongcheon (Korea)as a mordant in the post-treatment of textile were evaluated. The dyeability and fastness of cotton fabric and silk to light and washing as well as different fermentation periods and temperatures were investigated, and the following results were obtained. The dyeability of the fermented and non-fermented material did not show a significant difference. Fabrics mordanted with Hwangsu generally exhibited a reddish color due to the presence of iron. The dyeing of cotton fabric and silk by fermentation and Hwangsu mordanting were found to be effective on Rhus javanica L. and Rheum coreanum. These results were confirmed through fastness to light 3 of cotton on Rheum coreanum and 3-4 of silk on Rhus javanica L., respectively. The washing fastness of both fabrics dyed with fermented Rhus javanica L. and Rheum coreanum was improved, showing higher K/S value after washing than before washing.

• 한국건설순환자원학회논문집
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• 제2권4호
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• pp.291-296
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• 2014

건축물 에너지 사용량과 온실가스 배출량 감소를 목적으로, 열적 물성 등이 향상된 새로운 단열소재가 개발 사용되는 추세이다. 이중 기존 단열소재의 문제점 (가연성, 처짐, 수분 취약성, 단열성능 저하 등)을 보완한 미네랄 하이드레이트 소재가 새롭게 사용되고 있다. 미네랄 하이드레이트는 건축물 구조체로 사용되는 ALC의 제조방법과 유사하나, 구조체가 아닌 단열소재만으로 사용된다는 특징을 갖는다. 미네랄 하이드레이트 제조를 위해서는 시멘트, 생석회 및 무수석고 등이 사용되며, 무수석고는 전량 수입에 의존하고 있다. 따라서 본 연구에서는 수입대체효과 뿐만 아니라, 폐기물 재활용 측면에서 무수석고를 대체하여 석유제조 공정 부산 탈황석고를 사용하고자 하였다. 탈황석고를 미네랄 하이드레이트 원료로 사용할 경우, 무수석고 전량과 생석회 일부를 대체할 수 있었다. 더불어 탈황석고를 사용한 미네랄 하이드레이트는 기존 무수석고 사용시와 유사한 열적, 물리적 특성도 발현되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.253-256
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• 1997

Recently, mixture insulating oils is widely used in respect that the physical and the electrical properties is more excellentthan mineral oils, such as alkylbenzene oils and silicone oils, and that cost is lower than alkylbenzene oils or silicone oils. Also, it is important to research for the additive BTA(Benzotriazole) as a study for the phenomena of streaming electrification of mineral oils. So, mixture insulating oils class 7-2, is selected as a specimen in this experiments, and the contents of BTA in specimen are 0.2[ppm], 10[ppm] and 30[ppm], respectively. Then, the physical and the electrical properties for each specimen is made researches.

• 한국임상수의학회지
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• 제35권5호
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• pp.215-217
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• 2018

A one-year-old, intact male, 24 kg, mixed breed dog was referred to the Animal Medical Center, Iksan, Chonbuk, Korea for treatment of a gunshot wound to the head. Physical examinations revealed bilateral nasal bleeding and open-mouth breathing. Radiographic examination showed fracture of the right maxilla bone and multiple fractures of the nasal bone. A $1cm{\times}1cm{\times}1.8cm$ region of mineral opacity material was observed in the right-cranial ventralnasal cavity and a $6mm{\times}6mm{\times}9mm$ region of mineral opacity material was present in the left-cranial dorsal-nasal cavity. The surgical procedure involved removal of bone fragments and the lodged bullet as well as the installation of three intraosseous wires. At two weeks after surgery, the patient exhibited no complications and had a good prognosis.