• Journal of Welding and Joining
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• 제25권4호
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• pp.28-34
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• 2007

The heating unit of direct heating method manufactured as the plasma spray coating of $TiO_2/NiCr$ conductive heating material on the surface of heating unit in order to improve the disadvantages of indirect heating method. $TiO_2$ and NiCr (80wt.%Ni-20wt.%Cr) that had the properties of conduction and heating was chosen for the conductive heating material. The compositions of the composite powders were studied $TiO_2-30wt.%NiCr\;and\;TiO_2-10wt.%NiCr$. As the heating temperature was increased, the hardness of heating layer was increased because of the fine microstructure and the decrease of porosity. The adhesion strength was decreased for coarsening and connection of voids in the insulation layer, and the electrical resistivity of heating layer was increased for fine crack formation and growth. In this study, the best efficient sprayed coatings with heating unit was concluded as the plasma sprayed $TiO_2-10wt.%NiCr$ coatings that was heat treated at $300^{\circ}C$.

• 한국화재소방학회논문지
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• 제32권3호
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• pp.27-34
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• 2018

본 연구는 송엽분과 질석을 주 원료로 하여 건축용 및 선박용으로 적용될 수 있는 준불연 단열복합보드를 개발하고 불연성능, 준불연성능, 보드 전체의 열관류율을 평가하였다. 가연성 물질인 송엽분과 유연바인더의 비율에 따라 보드의 화재저항성능이 결정되었으며, 가연물질이 불포함된 보드의 경우 불연성능을 확보하였다. 송엽분 6%를 첨가한 보드는 준불연 성능을 확보할 수 있었으며, 그 이상의 송엽분이 포함되거나 가연성의 바인더가 첨가될 경우 준불연 성능을 확보할 수 없는 것으로 나타났다. 또한, 글래스울과 폴리우레탄 뿜칠을 단열층으로 하고 개발된 불연/준불연 보드를 이용하여 1차 마감한 복합벽체는 200 mm 두께에서 국내법규 상의 건축물 단열기준을 상회하여 만족하는 것으로 나타났다.

• Composites Research
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• 제37권3호
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• pp.232-237
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• 2024

접착용 테이프는 다양한 기계적 강도를 요구하는 재료와 특유의 접착 물질을 결합시켜 편리하게 다양한 용도로 사용할 수 있다. 그 중 덕트 테이프(duct tape)는 대개 쉽게 구할 수 있고, 널리 사용되는 접착 테이프로 뽑을 수 있다. 덕트 테이프는 일반 테이프와 달리 섬유 소재를 함유하고 있는 복합재료이고 기계적 강도가 우수하다. 그 외에도 전선의 절연 용도로 사용되는 전기 절연테이프도 매우 오랜 기간 동안 사용되었고 실제로는 절연용도 외에도 전선의 기계적 강도 보강 및 댐핑 역할을 한다. 최근에는 다양한 종류의 폼 테이프(foam tape) 및 양면 테이프도 여러 용도로 널리 사용되고 있다. 하지만, 이러한 테이프의 소음 차단 효과에 대해서는 기존 자료에 명확하게 나타나 있지 않다. 본 연구에서는 미세한 공혈(hole)을 이용하여 다양한 테이프의 삽입손실을 측정하여 소음 차단 효과를 나타내었고, 그 중에서도 양면 폼 테이프의 소음 차단 효과가 가장 좋게 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1621-1623
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• 1999

Recently, high voltage outdoor ploymer insulators have been widely used commercially owing to their excellent electrical and mechanical properties, superior comtamination flashover performance, light weight, easy installation or handing, no maintenance during service, competitive price and so on. compared to porcelaain and glass insulators. For instance, silicone rubber(SR) for polymeric insulators specially has much superior insulating and anti-pollution performance due to its specific hydrophobicity even in severe contaminated environments. We have investigated surface discharge current characteristics of silicone rubbers(SR) for HV outdoor composite insulation specimen under accelerated aging codition using a computer measuring system. The relations of average leakage current and surface discharge current repetition rates and discharge current amplitude, the distribution of discharge current amplitude were studied to investigate electrical conduction of silicone rubber surface with the salt fog condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1676-1678
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• 2004

Class-F resin-rich type insulating tapes are generally used for the groundwall insulations of the large turbine generators with air-cooled and hydrogen-cooled stator windings. In this paper, mechanical strength properties degraded over aging time in higher temperature than designed one in normal condition were experimentally investigated and the results of comparative tests were presented on the existing class-F resin-rich type tape and a developed one after curing. The resin-rich insulating tapes with composite material of Mica/Epoxy/support currently were used in this test. The tests for tensile and flexural strength properties were conducted with the specimens which were composed of unaged and the aged specimens accelerated for one, two, and three thousand hours at 180 $^{\circ}C$. The tensional strength was only measured for the unaged specimens and the results are also presented to make a comparative test for their initial mechanical characteristics.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.149-149
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• 2016

Ceramic is widely known material due to its outstanding mechanical property. Besides, Zirconia(ZrO2) has a low thermal conductivity so it is advantage in a heat insulation. Because of these superior properties, ZrO2 is attracted to many fields using ultra high temperature for example vehicle engines, aerospace industry, turbine, nuclear system and so on. However brittle fracture is a disadvantage of the ZrO2. In order to overcome this problem, we can make the ceramic materials to the forms of ceramic nanoparticles, ceramic nanowhiskers and these forms can be used to an agent of composite materials. In this work, we selected Au catalyzed Vapor-Liquid-Solid mechanism to synthesize ZrO2 nanowhiskers. The ZrO2 whiskers are grown through Hot-wall Chemical Vapor Deposition(Hot wall CVD) using ZrCl4 as a powder source and Au film as a catalyst. This Hot wall CVD method is known to comparatively cost effective. The synthesis condition is a temperature of $1100^{\circ}C$, a pressure of 760torr(1atm) and carrier gas(Ar) flow of 500sccm. To observe the morphology of ZrO2 scanning electron microscopy is used and to identify the crystal structure x-ray diffraction is used.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.262-263
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• 2009

To add Nanofiller in the epoxy which is used with the solid insulation material of existing and is a research which observes the improvement of the structural quality to produce the Nanocomposite. Montmorillonite uses with Nanofiller, MMT of the content expense (wt%) which is various and mixed an epoxide and produced sample. According to content of the sample result MMT according to respectively content expense to measure SEM photographing which is the possibility of knowing the minute structure of section with sample where is produced and the tensile strength will be able to observe the change of quality. MMT silicate layer uniformly more in the result and within epoxy matrix, being dispersed, will be able to observe.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.327_328
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• 2009

The insulator being used for transmission line is to mount the charged conductor on the tower or other supports. The insulators are classified according to its material: porcelain, glass and polymer. Polymer insulators are also called as composite insulator or non ceramic insulator (NCI). Insulators are a major element of a power transmission system. Since a faulty insulator can lead to a wide spreading blackout, it must have sufficient mechanical and electrical strength. It must be durable, have high electrical insulation and be able to withstand a leakage current. It must also be able to withstand the toughest weather conditions. In Korea, porcelain insulators have been used widely. However, to make compact equipment and keep up with global trends, we have enhanced domestic production of polymer insulator and are encouraging its applications. Accordingly, this thesis will look at types of insulators, use and trends, and prospects of insulators application in the field.

• 대한안전경영과학회지
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• 제11권2호
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• pp.77-85
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• 2009

Considering heat insulation and beautiful sight of construction, making use of exterior panels is increasing. Recently the exterior panels now are weak very much, and so in consequence of the weakness fire spreads rapidly. Compared with internal fire, external vertical fire spread rate goes rapidly and it is extensive in spread range, therefore it is dangerous very much. Accordingly, under present condition of poor standard of exterior panels, it is required to take measure to meet the appropriate situation. In this study, by making use of FDS(Fire Dynamic Simulation) program about external vertical fire of high rise building, fire behavior is searched by computer. It is important that realizing by computer fire modeling about external vertical fire must be included certainly in procedure of fire performance design in the future. In modeling program, FDS version 5 is available, and aluminium composite panel is applied in external panels. In this study, for realizing of actual fire condition, FDS is applied by details of fire scenarios considering influence of wind.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.121-126
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• 2000

Metal/Ceramic structures have many attractive properties, with great potential for applications that demand high stiffness, as well as chemical and biological stability, thermal and electrical insulation. They are currently in use for mechanical and thermal protection in cutting tool and engine parts. With all their great advantage, ceramics suffer from one major problem they are brittle, and are especially susceptible to cracking from surface contacts. Delamination at the interfaces with adjacent layers is a particularly disturbing problem, and can cause premature failure of a composite system. so determination of adhesive properties of coating is one of the most important problems for the extension of the use of coated materials. In this work, mechanical characteristics of Interface of ceramic/Metal composites are evaluated by means of hardness test, indentation test apparent interfacial toughness and bonding strength test. The interface indentation test provides a relation between the applied load(P) and the length of the crack(a) created at the interface between the coating and the substrate.