• 콘크리트학회논문집
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• 제29권1호
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• pp.109-116
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• 2017

본 연구에서는 콘크리트 중의 철근부식의 보수로 전기방식법을 적용할 경우의 탈염, 부식복원 및 구조거동을 효과적이고 정량적으로 평가하였다. $160{\times}160{\times}1000mm$의 콘크리트 시편을 제작하였으며 피복두께 20 mm의 원형철근 3본을 매립하였으며 콘크리트 타설 시 염소이온 5.0%를 혼입하여 철근부식을 가속한 뒤 전기방식을 인가하였다. 전기방식 전류는 직류 $750mA/m^2$를 2, 4, 8주간 인가하였다. 결과로서 탈염효과는 인가 기간에 따라 증가하였으며 최대 탈염비는 8주간의 인가 시 64.7-83.7%로 측정되었다. 이는 시멘트계에서 염소이온의 50-60%가 고정화됨을 고려할 때, 일정량의 고정화된 염소이온 역시 탈염된 것으로 판단된다. 또한 부식상태는 8주간의 전기방식 이후에도 $6.5mA/m^2$의 부식 전류 및 330 mV (vs. SCE)의 부식전위를 나타내 여전히 부식이 존재함을 확인하였다. 구조거동에 있어 부식의 증가로 인해 콘크리트의 최대하중은 증가하였으나, 전기방식을 적용함에 따라 오히려 최대하중은 감소하였으나 Control시편보다는 상회한 값을 나타내 전기방식이 구조적 악영향은 없음을 확인하였다.

• 박물관보존과학
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• 제5권
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• pp.23-30
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• 2004

고려경상들은 1986년과 1996년에 1차 보존처리하였으나 소장품 점검과정에서 분말화된 동제부식물을 발견하였고 이에 대한 재처리가 필요한 상태였다. 따라서 안정화와 강화처리 등의 보존처리를 실시하여 더 이상의 부식이 진행하지 않도록 하였다. 또한 경상표면의 문양을 채우고 있는 분말과 조금(彫金)기법을 실체현미경과 휴대용X-선형광분석기로 조사한 결과 경상의 문양을 채우고 있던 분말은 금분, 은분, 호분(또는 석고) 등이며 또한 경상표면의 문양을 시문한 주된 조금(彫金)기법은 점선조각, 모조각(삼각선파기와 둥근선파기), 축조각 등을 사용하여 표현한 것으로 보인다.

• 한국건축시공학회지
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• 제2권2호
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• pp.165-172
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• 2002

A reinforced concrete building neighboring in Pusan or Ulsan where is directly exposed to salt water contrasting with other in land areas contains much salt content percolated from the outside that the high salt content percolates and diffuses through the inside of reinforced concrete; therefore, an immovable tunic surrounding it begins to be destroyed and eroded with high speed. At the time, the cross-sectional area and volume expansion of re-bar reinforcing result in being cracks make a rapid progress gradually until they appear in the surface of the one, the phenomenon such as being a thin layer or falling off the part of it causes a lowering of its durability and might collapse the concrete construction. So far, we've investigated into salt content of reinforced concrete constructions neighboring in a seaside district and damage by carbonation, and we came to a conclusion as follows: $\circled1$ Under the oceanic circumstance a concrete construction is influenced by sea water directly that contains much amount of salt content contrasting with other constructions on inland areas. $\circled2$ Because of chloride penetration the carbonation of reinforced concrete made a rapid progress until more than the covering thickness of re-bar. $\circled3$ An old reinforced concrete building which has been piled up salt injury and proceeding the carbonation of its cross-sectional area. $\circled4$ According to rapidly cracking from the inside to surface of reiforced concrete, the phenomenon of being a thin layer or falling off the part of reinforced concrete results in a lowering of durability and shortening the life-time of concrete construction itself.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.223-227
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• 2005

A PCV valve is a part to control the flow rate of Blowby gas in a PCV system. A PCV system re-burns Blowby gas with fuel in a combustion chamber. Some gas enters to a crankcase room through the gap between piston ring and engine cylinder wall. This gas si called 'Blowby gas'. This gas causes many problems. In environmental view, Blowby gas includes about $25\~35\%$ hydrocarbon{HC) of total generated HC in an automobile. Hydrocarbon is a very harmful pollutant element in our life. In mechanical view, Blowby gas has some reaction with lubricant oil of crankcase room. Then, this causes lubricant oil contamination, crankcase corrosion and a decrease fo engine efficiency. Consequently, Blowby gas must be eliminated from a crankcase room. In this study, we simulated internal flow characteristics in a PCV valve according to spool dynamic behavior using local remeshing method And, we programmed our sub routine to simulate a spool dynamic motion. As results, spool dynamic behavior is periodically oscillated by the relationship between fluid force and elastic force of spring. And its magnitude is linearly increased by the differential pressure between inlet and outlet. Also, as spool is largely moved, flow area is suddenly decreased at orifice. For this reason, flow velocity is rapidly decreased by viscous effect.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.105-106
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• 2018

Cracks are typical defects that occur in concrete structures. When cracks occur in the structure, durability reduction, concrete neutralization, and steel corrosion cause functional safety problems. In order to prevent such cracks, surface repair method is performed for cracks smaller than 0.3 mm and rechargeable method is performed for cracks larger than 0.3 mm. However, even if it is applied by the surface repair method at less than 0.3 mm, re-leakage cracks continue to occur. Recently, the Supreme Court ruled that the rechargeable method should be applied to cracks less than 0.3mm in order to reduce the occurrence of defects. However, it was considered that the repair fees were too high relative to the observed defect rate, resulting in a necessitation of modifying the existing construction analysis administration standards. This study analyzes the differences in the subjective views on the durability degradation with regards to surface repair methods in concrete structures.

• 한국안전학회지
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• 제18권3호
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• pp.14-21
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• 2003

This study deals with the influence of ceramic coating on characteristics of friction and abrasion of aluminum allot(7075 T6) used in mechanical casting. In this research, frictional wear characteristic of ceramic coating materials such as $A1_2O_3$, $Si_3N_4$, SiC was investigated using aluminum alloy(7075 T6) and stainless 403 cast iron under room temperature and normal air pressure. The coating layer was observed using SEM. The conclusions are as follows: 1) Friction coefficients of $A1_2O_3$, SiC and $Si_3N_4$ are obtained 0.63 0.56 and 0.54 respectively. 2) Abrasion resistance of stainless 403 cast iron with $Si_3N_4$ is the best among the ceramic coating materials. 3) Abrasion mechanism of aluminum alloy(7075 T6) coaled with ceramic material and stainless 403 cast iron is caused by brittle fracture. 4) Coating the ceramic material on the aluminum alloy(7075 T6) can effectively increase the antiwear, impact properties, and corrosion resistance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.227-230
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• 2004

As the organic acids were added in the slurry, zeta potential of alumina was changed to negative value and IEP value was shifted from alkaline to acidic pH. In citric acid based slurry, Cu surface continuously dissolved and etching depth linearly increased. On the contrary, passivation layer was grown on Cu surface in oxalic acid based slurry. As the platen rotation speed increased, Preston coefficient decreased in both slurries. With oxalic acid based slurry, at low velocity, removal rate is high value because of high friction force compared to citric acid based slurry. As platen velocity increased, removal of Cu in citric acid based slurry became higher value than oxalic acid based slurry. Typical lubrication behaviors were observed in both slurries. As Sommerfeld number increased, COF values gradually decreased and then re-increased. It indicated that lubrication was changed to direct contact or semi-direct contact mode to hydro-lubrication mode.

• 방사성폐기물학회지
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• 제19권1호
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• pp.9-27
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• 2021

As an example of research activities in decontamination for decommissioning, new data are presented on the options for corrosion layer dissolution during the decommissioning decontamination, or persulfate regeneration for decontamination solutions re-use. For the management of spent decontamination solutions, new method based on solvent extraction of radionuclides into ionic liquid followed by electrodeposition of the radionuclides has been developed. Fields of applications of composite inorganic-organic absorbers or solid extractants with polyacrylonitrile (PAN) binding matrix for the treatment of liquid radioactive waste are reviewed; a method for americium separation from the boric acid containing NPP evaporator concentrates based on the TODGA-PAN material is discussed in more detail. Performance of a model of radionuclide transport, developed and implemented within the GoldSim programming environment, for the safety studies of the LLW/ILW repository is demonstrated on the specific case of the Richard repository (Czech Republic). Continuation and even broadening of these activities are expected in connection with the approaching end of the lifespan of the first blocks of the Czech NPPs.

• 보존과학회지
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• 제28권1호
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• pp.29-37
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• 2012

이 연구는 매장상태에서 출토되는 금동유물의 표면색이 고유한 금색 이외에 붉은 계열의 색들과 교반되어 나타나는 원인을 규명하고자 수은아말감도금법을 재현해 보고 완성품에 대하여 열처리 조건을 변화시켜 도금층의 표면색과 표면 및 단면의 상태변화를 알아보고자 하였다. 그 결과 높은 열처리 실험조건 일수록 도금층에 검은 산화물층이 넓게 생성되었으며, 산화물층을 제거한 부분에서는 붉은색의 도금 표면색이 표출되었다. 또한 표면이 노란색과 붉은색으로 교반된 시료의 미세 표면관찰에서는 색상에 따라 표면상태의 변화양상이 다르게 나타났으며 단면에서는 도금층 공극의 밀도와 크기가 점차 커지는 것으로 밝혀졌다. 열처리 실험 후 표면성분분석 결과 온도가 올라갈수록 Hg와 Au의 비율은 감소하였으나 Cu의 성분비는 증가하였다. 또한 단면분석 결과에서도 실험조건에 따른 층위별 Au와 Cu의 성분변화가 반비례하는 경향을 보였다. 이러한 실험결과들을 볼 때 아말감을 이용한 금동유물은 생산과정이나 생산 이후에 열이 도금층의 표면색에 영향을 미치는 것을 의미하며 도금층 상태에도 관계된다는 것을 확인할 수 있었다.

• 보존과학연구
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• 통권22호
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• pp.115-132
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• 2001

No. 3 Tomb of Bogam-ri, in Naju City, Chollanam-do Province, was a site excavated and inspected from 1996 to 1998 and had a various grave forms, including jar-coffins, stone-chambers and stone-cists. Although most of the metal artifacts excavated from it were severely corroded, we could implement microstructure investigation by collecting samples from the iron axes, iron coffin-nails and iron clamps in which the metal parts were remained. The metal structures were inspected by using metallographic microscope and SEM, and fine components analysis was implemented by ICP. To examine the hardness differences in accordance with the structure distribution, we measured the hardness by structures with Vickers hardness testing machine. As a result of the metal structure inspection, most of them were pure iron, ferrite, and also pearlite, cementite and widmannstaten structures were displayed. We could confirm carbonization was formed on the surface of the iron axes-B, iron coffin-nails-B, and iron clamps-A. There was no carbonization in the rest of the artifacts, and it is not certain that whether the carbonized parts were peeled off through extreme corrosion or they were not carbonized when they were made. In the particular part of a blade, the quality of the material was strengthened through processing. Due to the processing re-grain was caused and fine grain particles were formed. As a result of the ICP component analysis, there were no addition atoms because pure irons were used as materials. In the mean time, No. 17 jar-coffin where the iron axes-A are excavated, is chronologically ordered as from the late-fourth century to the mid-fifth century, and No. 1 and No. 2 stone chambers, where the rest of the artifacts were excavated, as the early-sixth century. It was difficult to relate the periodic differences with the manufacture technique artifacts which we inspected because there were no distinct characteristics of the manufacture technique of the metal structures and it is impossible to conclude the artifacts and sites are at the same period although their periods are different.