• 한국세라믹학회지
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• 제42권4호
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• pp.282-286
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• 2005

인공치과재료인 도재에 백류석(Leucite)결정을 이용해 왔는데, 이는 치과재료에 함께 사용하는 금속재질의 열팽창계수가 크기 때문에 이에 맞추기 위한 것이다. 산업적으로는 카리 장석으로부터 부조화 용융으로 leucite 결정을 합성하여 이용하고 있으며 이는 $1150^{\circ}C$ 이상에서 생성된다. 본 연구는 치과 재료에 사용하는 leucite를 보다 낮은 온도에서 조화 용융으로 합성하기 위한 것이다. 이를 위하여 카리 장석을 주원료로, 그 이외에 탄산칼륨, 수산화알루미늄을 사용하여 화학 양론적인 조성으로 고상합성법을 이용하여 leucite 합성 실험을 하였다. 그 결과 leucite를 조화 용융으로 $950^{\circ}C$부터 고상법으로 합성되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.465-466
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• 2011

The global trend is to make transmission lines light weight and compact by using insulators and other equipment made of advanced materials. In Korea, the diversification of insulators supply route has begun in order to obtain price competitiveness. In May 1999, polymer insulators were finally introduced for the first time and installed to the 154kV transmission lines. After that, the construction and procurement standards were made and domestic polymer insulators were developed. And then, foreign and domestic manufacturers were registered in KEPCO as qualified insulator suppliers. As of 2010, purchasing polymer insulators by competitive bidding from foreign and domestic manufacturers has been possible. For this reason, it was decided to reduce the use of porcelain insulators and increase the use of polymer insulators taking the installation price into consideration

• The Journal of Advanced Prosthodontics
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• 제9권1호
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• pp.52-56
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• 2017

PURPOSE. Considering the importance of metal-ceramic bond, the present study aimed to compare the bond strength of ceramics to cobalt-chrome (Co-Cr) alloys made by casting and selective laser melting (SLM). MATERIALS AND METHODS. In this in-vitro experimental study, two sample groups were prepared, with one group comprising of 10 Co-Cr metal frameworks fabricated by SLM method and the other of 10 Co-Cr metal frameworks fabricated by lost wax cast method with the dimensions of $0.5{\times}3{\times}25\;mm$ (following ISO standard 9693). Porcelain with the thickness of 1.1 mm was applied on a $3{\times}8-mm$ central rectangular area of each sample. Afterwards, bond strengths of the samples were assessed with a Universal Testing Machine. Statistical analysis was performed with Kolmogorov-Smirnov test and T-test. RESULTS. Bond strength in the conventionally cast group equaled $74.94{\times}16.06\;MPa$, while in SLM group, it equaled $69.02{\times}5.77\;MPa$. The difference was not statistically significant ($P{\leq}.05$). CONCLUSION. The results indicated that the bond strengths between ceramic and Co-Cr alloys made by casting and SLM methods were not statistically different.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.481-484
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• 2003

Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators have significant advantages over porcelain and glass insulators. With the gradual improvement of their design and material, their reliability has also increased. It is however difficult to establish how they will perform after several years of service. Aging of the insulator weathershed may lead to damages such as excessive chalking and crazing, erosion and tracking which affect the insulator performance. In service insulator are subjected to aging stresses such as humidity, pollution and electrical field which act singly or in combination. There have been numerous accelerated laboratory tests developed with the intention of evaluating suitability of polymeric materials. Some of these are strictly material tests, where as, others evaluate full scale devices. Service experience plays a key role in the utility selection of polymer insulator, but is time consuming, and may not always be available. Hence there is a need for a meaningful and reliable accelerated aging test for polymer insulator. This paper describes multi-stress aging test for reliability of polymer insulator This paper presents the rule of multi-stress aging test and test chamber for polymer insulator in korea electrotechnology research institute.

• The Journal of Advanced Prosthodontics
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• 제2권2호
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• pp.54-57
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• 2010

PURPOSE. The aim of this study was to evaluate the periodontal and prosthodontic complications of multiple freestanding implants in the posterior jaws for up to 1 year of function. MATERIALS AND METHODS. Eight patients received 20 implants posterior to canines. Two or more implants were consecutively inserted to each patient. Single crowns were delivered onto the implants. Marginal bone loss, implant mobility, probing depth, and screw loosening were examined to evaluate the clinical success of such restorations for maximum 1 year of functional loading. RESULTS. All the implants performed well during the observation period. Neither periodontal nor prosthodontic complications were found except a slight porcelain chipping. While the marginal bone level was on average 0.09 mm lower around the implant after 6 months of loading, it was 0.15 mm higher after 1 year. CONCLUSION. Within the limits of this investigation, separate single-tooth implant restorations to replace consecutive missing teeth may clinically function well in the posterior jaw.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.565-569
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• 1999

In these days, the silicone insulators have been increasingly studied and applied for outdoor insulators because it has superior characteristics than porcelain and glass insulators, which have been used for outdoor insulators. First of all, The excellent performance of the silicone rubber in polluted and wet conditions is attributed to the ability of the material to maintain the hydrophobicity of the surface in the presence of severe contamination and wet conditions. This is because of the presence of low molecular weight mobile fluid in the silicone rubber which diffuses to the surface and to above the contamination layer. But, the leakage current and some surface discharge occurs on surface of the composite polymeric insulation materials when the insulator is used for a long time with severe contaminative condition and it can lead the contamination flashover. So the leakage current and the discharge current are important to estimate the condition of the silicone rubber surface. In this paper, the average leakage current, the relation of surface discharge current and phase angle were study to investigate electrical conduction of silicone rubber surface with the salt fog condition.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.119-122
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• 2000

Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators for transmission line have significant advantages over porcelain and glass insulators, especially for ultra-high voltage transmission lines. Their advantages are light weight, vandalism resistance and hydrophobicity. Polymer insulators are a relatively new technology, but their expected life is still unknown. Therefore these estimating technique are very important. Their life time is related to weathering and operating condition. Multi-aging test is requested because aging factor is occurred by multi-aging than unique aging. The aging test about polymer insulators have mainly carried out by IEC 61109. This paper presents multi-stress chamber experiments and tracking wheel test to examine the tracking and erosion performance of polymer insulator for transmission. Multi-stress testing is able to demonstrate deficiencies of polymer insulator materials and designs, including the nature of interfaces in insulation design. We have investigated IEC 61109 Annex C (5000h aging test) and CEA tracking wheel test as test methods of artificial accelerated aging. The aging degree of polymer insulator is estimated by leakage current, measurement of hydrophobicity degree, damage conditions of insulator surface, withstand voltage test etc.

• 한국전기전자재료학회논문지
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• 제20권6호
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• pp.555-560
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• 2007

This paper describes the results of a study on the sealing integrity of polymer housed surge arrester based on the thermal mechanical test. The polymer housed surge arrester employs silicone insulating materials for its housing, instead of the conventional porcelain housing. The polymer housed surge arresters exhibited the highest sealing integrity because it is not air volume between the FRP(fiber reinforced plastics) module and the silicone housing. In accordance, the sealing integrity of station class surge arresters is investigated with moisture ingress test. And, the influence of sealing integrity was evaluated through such as measurement of the deflection, reference voltage, leakage current. In electrical characteristics, reference voltage decreased in the range of $16.45{\sim}16.15\;kV$ with after thermal mechanical test. In contrary, despite the continued moisture ingress, the polymer housed surge arresters exhibited almost the same leakage current value and the resistive leakage current has risen slightly. As a results, It was thought that the polymer housed surge arresters shows good stability with sealing integrity.

• 대한치과보철학회지
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• 제52권2호
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• pp.90-96
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• 2014

연구 목적: 이 연구의 목적은 열가압성형기법이 금속도재관의 치경부 변연적합도에 미치는 영향을 확인하는 것이다. 연구 재료 및 방법: 실험에 앞서, 4개의 금속 주모형을 형성하였다. 각 모형은 각각chamfer, heavy chamfer, shoulder with bevel, shoulder (collarless)변연을 형성하였다. 각 변연당 10개씩의 금관을 제작하여, 총 40개를 제작하였다. Coping 단계에서, 그리고 금속도재관 완성 단계에서 주모형과 금관 사이의 변연간극은 100배율의 광학현미경 관찰을 통하여 측정되었다. Data분석은 paired t-test along with one-way ANOVA와 Duncan multiple comparison test를 이용하여 이루어졌다. 결과: 변연간극의 평균과 표준편차를 분석한 결과, 금속 코핑과 그 후 완성된 금속도재관, 모든 경우에서 변연부 간격은 임상적 허용범위 안에 있었다. Chamfer 변연 실험군의 경우 Heavy chamfer 변연 실험군에 비하여 금속도재관 완성 후 변연부 간격의 유의한 증가가 있었다. 그리고Shoulder 변연 실험군에서 도재로 처리된 변연이 Chamfer와 Shoulder변연 실험군의 금속변연에 비하여 변연부 간격이 유의하게 작게 나타났다. 결론: 열가압성형기법을 통하여 제작한 금속도재수복물의 변연적합도는 전통적인 방법으로 제작한 금속도재수복물의 변연적합도와 유의한 차이점이 없었다. 제작과정의 효율성으로, 열가압성형기법은 임상에서의 효과적인 사용법으로 고려될 수 있다.

• 대한치과보철학회지
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• 제52권1호
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• pp.18-26
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• 2014

연구 목적: 본 연구의 목적은 가장 최근에 수행된 치과의원의 경영 분석 자료를 바탕으로 상향식 방법을 적용하여 임플란트 원가를 산정하는데 있다. 연구 재료 및 방법: 본 연구에서는 진료행위 각각에 소요되는 직간접 비용을 모두 합산하는 상향식 방식으로 산출하였다. 상향식 원가계산의 경우 총원가는 인건비, 재료비, 관리비, 의료사고비용, 투자자본의 기회비용 등으로 구성이 된다. 이를 임플란트 원가 구성요소로 구분하면 인건비, 기공료, 재료비, 감가상각비 등의 직접비용과 관리운영비를 포함하는 간접비용, 치과의원 투자분에 대한 기회비용으로 구성된다. 결과: 상부보철물의 종류에 따라 금속관일 경우 1,449천원, 도재관일 경우 1,583천원, 오버덴쳐의 경우 2,471천원으로 산정되었다. 임플란트 원가는 인건비, 재료비, 관리비, 기타비용으로 나누어지는데 총 원가 중 인건비가 차지하는 비율은 50%, 재료비 33%, 관리비 15%, 기타비용2%로 나타났다. 이를 직접비, 간접비, 투자비용으로 구분하면 상부 보철물이 금속관일 경우 각각 원가의 83%, 15%, 2%를 차지한다. 결론: 전체 원가 중 인건비가 73만원(약 50%)으로 가장 많은 비중을 차지한다. 상향식 원가계산 결과 관행수가에 근접하게 나타났는데 금속관의 경우 145만원, 도재관일 경우 158만원 추계되었다.