• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.26-32
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• 2015

Purpose: The main purpose of this study is to suggest application plan of dipping method by comparing & analysing the difference between addition method and dipping method in the manufacture of metal-ceramic substructure of maxillary central incisor (#1), followed by assessing the work efficiency. Materials and Methods: Master die and hard plaster-copied one were produced and then a total of 20 copies, 10 copies for each through addition method and dipping method, were manufactured and experimented. Copings were fixed on the abutment model and invested in epoxy mounting cup. Samples were cut in labial and lingual direction, using cutter and then rubbed on sandpaper, whose 4 points were measured by using digital microscope. Results: The comparison of mean values by using t-test, parametric statistical method, shows overall significant difference (P < 0.05). Conclusion: The result of this study can be suggested as an application plan, since there is no significant difference between addition method and dipping method in the manufacture of metal-ceramic substructure.

• 보존과학연구
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• s.32
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• pp.61-74
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• 2011

This study examines the removal effects of solvents which were applied on three adhesives and three filling materials for ceramics. The chosen materials are Cemedine C, Loctite$^{(R)}$ 401$^{TM}$, Araldite Rapid Type, plaster of paris, CDKI 520A+B, Araldit$^{(R)}$ SV427-2+HV427-1. For the first examination, each different materials were soaked into different solvents, and then the soften level were compared by compressive pressure. The result of the first exam showed that Cemedine C was dissolved easily in acetone. Furthermore Araldite, CDK and SV427 were soften efficiently by Dichloromethan, Tetrahydrofuran and DMX(Dichloromethan+Methanol+Xylene). However, Loctite and plaster were not able to make sample for the first test. Therefore, the second test carried on only. The second examination, chosen effective solvents from the first test were applied with two different methods; soaking and saturated atmosphere. Almost every sample could removed by soaking method in ten minutes, and saturated atmosphere method needs 24 hours for the safety.

• Journal of Conservation Science
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• v.27 no.4
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• pp.345-356
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• 2011

To remove metal stains of the ceramics, chemical cleaning is essential case by case. This study investigated the removal characteristics of iron stains by oxalic acid and citric acid including their application methods of soaking and poultice. The soaking method in cleaning agents showed removal process by color difference and released iron contents from iron stains on ceramics. Iron stains were removed successfully from ceramics, which soaked in oxalic acid for 60 hours. However, it is recommendable to soak in 0.25M oxalic acid for one to three hours because most iron stains were disappeared in 3 hours soaking. Citric acid is less effective than oxalic acid in removing iron stains because of heavy molecular weight and low acidity. Poultices (bentonite, sepiolite, activated carbon fiber and celite) with oxalic acid were applied on contaminated ceramics. After ten hours, iron stains on ceramics were removed successfully by poultice. Among them, bentonite and sepiolite have better application. Therefore, sepiolite with 0.25M oxalic acid was applied on the iron stains of whiteware and celadon from Ma Island, and then stains were removed. However, it is judged that the application methods can be varied according to the form and depth of contaminant. In addition, the residues of poultice on the ceramics will be considered for preventing contamination.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.273-276
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• 2003

대기 침적은 환경 내에서 침적된 물질들이 미치는 악영향으로 인하여 그에 대한 관심이 증대되고 있다. 특히 이 중에서 건식침적이란 대기 중 입자상이나 가스상 오염물질들이 눈이나 비가 오지 않을 때 지구 표면으로 이동되어 제거되거나 반응하는 기작을 말한다. 이러한 건식침적에 관한 연구는 그 측정의 어려움으로 인하여 주로 간접 측정법에 의하여 추정한 것이 대부분이었으나, 최근 대체 표면을 사용하여 건식침적량을 직접 측정을 하고자 하는 시도가 이루어져왔다. (중략)

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.699-706
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• 1998

현재까지 박막코팅 분야에 주로 이용해 오던 플라즈마 용융분사법을 이용하여 고밀도의 두꺼운 세라믹 침적물을 제조하였다. 용융점이 2910K인 ZrO2-20wt%Y2O3분말을 이용하여 최적조건에서 이론밀도의 약 97%의 침적물을 얻었다. 고밀도 침적에 영향을 미치는 변수는 챔버 내부압력, 플라즈마동력, 플라즈마 가스조성, 분사거리, 분말입자 크기 등이었으며, 침적밀도 및 침적된 splat의 형태는 분말의 용융정도 및 챔버 내부압력에 크게 좌우되었다. 높은 밀도으 침적물을 만들기 위해서는 분말을 완전히 용융시키는 것이 중요하며, 완전히 용융된 조건에서는 챔버 내부압력이 낮고 분말분사거리가 짧은 조건 즉, 분사되는 분말이 높은 모멘텀을 가질수록 침적물의 밀도가 증가함을 알 수 있었다. 실험에서 얻어진 결과는 ANOVA 통계방법으로 분석하여 단일변수의 영향뿐만 아니라 이들 변수가 서로 조합하여 밀도에 미치는 영향도 분석하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.208-208
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• 2009

메탄의 수증기-이산화탄소 복합개질반응에서 니켈 촉매의 탄소 침적 저항성에대한 Ce 증진 효과를 살펴보기 위해, Ni-Ce/${\alpha}-Al_2O_3$ 촉매를 제조하였다. Ce/Ni 비율 변화에 따른 촉매 비표면적, Ni 입자 분산도 및 촉매 활성 변화를 살펴보았고, Ce 첨가량을 최적화 할 수 있었다. Ce/Ni 비율 증가에 따라 NiO 결정크기가 감소하고 표면적과 Ni 분산도는 증가하였다. 특히, Ce/Ni=0.5 첨가 시, 촉매는 가장 넓은 비표면적과 Ni 분산도를 가졌으며, 우수한 촉매 활성 및 높은 탄소 침적 저항성을 보였다. 또한, 본 연구에서는 Ni과 Ce 담지 방법에 따른 Ni 분산도 향상과 Ni과 Ce간의 접촉 면적 극대화를 통한 활성산소 공급 향상에 대한 영향을 함께 살펴보았다. Ni과 Ce를 동시 함침법과 연속 함침법으로 담지하여 비교한 결과, 동시 함침법으로 제조한 Ni-Ce/${\alpha}-Al_2O_3$ (Ce/Ni=0.5) 촉매가 가장 우수한 촉매 성능 및 높은 탄소 침적 저항성을 보였다. 이는 동시 함침법으로 고분산된 Ni 입자와 담체간의 강한 상호작용 형성과 원활한 활성 산소 공급에 기인한 것이다.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.05a
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• pp.57-57
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• 1999

핵연료 펠렛제조공정의 단순화를 위하여 분말을 플라즈마로 용융시킨 후 이를 펠렛몰더에 직접 침적시키는 방법으로 핵연료를 제조하고자 하였다. 침적물의 밀도에 미치는 영향을 관찰하기 위하여 쉬스가스 조성, 플라즈마 동력, 챔버내부압력 및 분말 공급량, 입자크기, 분사관 위치, 분사거리 및 쉬스가스조성 등을 변수로 하였다$^{1)}$ . 실험으로 얻어진 결과는 ANOVA(Analysis of Variance)의 통계적 방법으로 각각의 인자가 밀도에 미치는 영향의 크기뿐만 아니라, 두 가지 이상의 인자가 조합되어 나타나는 영향에 대해서도 분석하였다.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.249-256
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• 2006

Catalytic combustion of toluene was investigated on the Cu-Mn oxide catalysts prepared by the impregnation(Imp) and the deposition-precipitation(DP) methods. The mixing of copper and manganese has been found to enhance the activity of catalysts. It is then found that catalytic efficiency of the Cu-Mn oxide catalyst prepared by the DP method on combustion of toluene is much higher than that of the Cu-Mn oxide catalyst prepared by Imp method with the same chemical composition. The catalyst prepared by the deposition-precipitation method observed no change of toluene conversion at time on stream during 10 days and at the addition of water vapor. On the basis of catalyst characterization data, it has been suggested that the catalysts prepared by the DP method showed uniform distribution and smaller particle size on the surface of catalyst and then enhanced reduction capability of catalysts. Therefore, we think that the DP method leads on progressive capacity of catalyst and promotes stability of catalyst. It was also presumed that catalytic conversion of toluene on the Cu-Mn oxide catalyst depends on redox reaction and $Cu_{1.5}Mn_{1.5}O_4$ spinel phase acts as the major active sites of catalyst.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.599-609
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• 1997

The phase behavior and dynamics of colloid suspensions and the resulting structures and properties of powder compacts were examined by a computer experimental method for cooperative packing processes. A wide range of properties and process conditions such as arbitrary particle size, medium densities, field strength, and temperature could be examined using the Peclet number (Pe). We demonstrated that an optimum range of Peclet number for the ordering of sediments was present and that the phenomena related to the ordering such as the onset of crystallization, the phase behavior, etc. strongly depend on process conditions. The present work appears to be useful to design the processing method of ceramic spherical submicron powders for the preparation of high-density green compacts.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2000.05a
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• pp.65-66
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• 2000