• 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.

• Composites Research
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• 제36권4호
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• pp.241-245
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• 2023

비철계 합금인 알루미늄과 구리 합금은 전기 및 열전도성이 우수하지만 철계 합금대비 상대적으로 기계적 특성은 낮다. 철계 합금인 스테인레스 스틸은 비철계인 알루미늄과 구리 대비 가공성은 나쁘지만 기계적 특성과 내부식성이 우수하여 고강도 공업용 소재로 사용되고 있다. 본 연구에서는 알루미늄과 구리 그리고 스테인레스 스틸을 융복합화 하여 기능 맞춤형 경사기능재료를 분말프로세스를 이용하여 제조하였다. 제조된 경사기능재료는 구리와 철계 합금 대비 경량의 우수한 표면 경도를 나타내었으며 열전도도 역시 단일 알루미늄과 스테인레스 스틸 소재 보다 높은 값을 나타내었다.

• 대한기계학회논문집A
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• 제37권6호
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• pp.739-745
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• 2013

본 연구에서는 급수 순환 시스템 중 동작 유체의 이송을 위해 사용하는 배관을 대상으로 관로 크기 및 고온 급수 환경에 따른 침식-부식 거동과 그 영향을 규명하고자 하였다. 이를 위해 일반적인 관로 소재인 철과 핵심 부식 인자인 산소의 화학반응식을 기반으로 Hayduk 과 Minhas 가 제안한 모델을 이용하여 침식-부식 해석을 실시하였다. 상용 유한요소해석 프로그램인 ABAQUS 를 사용하여 해석을 수행하였으며 배관의 직경 및 급수 온도를 변화시킴에 따른 침식-부식률을 평가할 수 있었다. 결과를 통해 급수 온도가 침식-부식률에 가장 큰 영향을 미치는 요인이 됨을 알 수 있었으며, 특히 $290^{\circ}C$ 급수에 노출된 스테인리스 316 강은 연간 $2.59{\mu}m$의 두께 손실이 발생할 것으로 예상되었다.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.657-665
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• 2021

Nondestructive evaluation methods play an important role in ensuring component integrity and safety in many industries. Operator fatigue can play a critical role in the reliability of such methods. This is important for inspecting high value assets or assets with a high consequence of failure, such as aerospace and nuclear components. Recent advances in convolution neural networks can support and automate these inspection efforts. This paper proposes using residual neural networks (ResNets) for real-time detection of corrosion, including iron oxide discoloration, pitting and stress corrosion cracking, in dry storage stainless steel canisters housing used nuclear fuel. The proposed approach crops nuclear canister images into smaller tiles, trains a ResNet on these tiles, and classifies images as corroded or intact using the per-image count of tiles predicted as corroded by the ResNet. The results demonstrate that such a deep learning approach allows to detect the locus of corrosion via smaller tiles, and at the same time to infer with high accuracy whether an image comes from a corroded canister. Thereby, the proposed approach holds promise to automate and speed up nuclear fuel canister inspections, to minimize inspection costs, and to partially replace human-conducted onsite inspections, thus reducing radiation doses to personnel.

• 자원환경지질
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• 제35권3호
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• pp.229-239
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• 2002

본 연구는 직류전원(DC)과 zero valent iron(ZVI)을 이용한 실험실 규모의 투수성 반응벽의 모사를 통하여 야외규모의 반응벽 설치시 반응벽과 전원의 설치 위치에 따른 trichloroethylene(TCE)의 처리시 효율성과 반응벽 사용가능 수명을 알아보고자 하였다. 실험결과 12개의 컬럼 type 중 ZVI와 DC를 동시에 사용하는 경우, ZVI만을 사용하는 경우의다. TCE의 환원적 탈염소화는 촉진되었다. 설치된 ZVI충진물질의 양을 고려할 경우, 하류에 ZVI를 설치하고, 전극배열은 상류에 양극을, 하류에 음극을 배열하는 것이 가장 적은 실비로 높은 처리 효율을 나타냄이 밝혀졌다.

• 상하수도학회지
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• 제36권5호
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• pp.261-273
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• 2022

In this study, we collect water control valves that have had accidents due to existing cracks, etc. are collected, and propose investigation items for strengthening the valve structural safety evaluation through a series of analyzes from valve specifications to physicochemical properties are proposed. The results of this study are as follows. First, there was a large variation in the thickness of the body or flange of the valves to be investigated, which is considered to be very important factor, because it may affect the safety of the valve body against internal pressure and the flange connected with the bolt nut. Second, 60% of the valves under investigation had many voids in the valve body and flange, etc. and the decrease in thickness due to corrosion was relatively large on the inner surface in contact with water rather than the outer surface. It is judged that the investigation of depth included voids is very important factor. Third, all valves to be investigated are made of gray cast iron foam, and therefore it is judged that there is no major problem in chemical composition. It is judged that the chemical composition should be investigated. Fourth, as a physical investigation item, the analysis of metal morphology structure seems to be a very important factor for nodular cast iron from rather than a gray cast iron foam water valve with a flake structure. As it was found to be 46.7~68.8% of the standard recommended by KS, it could have a direct effect on damage such as cracks, and therefore it is judged that the evaluation of tensile strength is very important in evaluating the safety of the valve.

• 보존과학연구
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• 통권17호
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• pp.20-38
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• 1996

Horse armour from Dohang-ri site had been retained its original form and all iron metal fragments of armour were very completely corroded without remaining metal core. Horse armour excavated is archaeologically very important, Also it should be maintained the original form. So, only moderate treatments such as brushing and consolidation techniques were performed. The processes for the conservation is as follows : 1) preliminary investigation, 2)removal of chlorides and corrosion products, 3) consolidation with 40% ParaloidNAD-10, 4) joining and restoration

• 상하수도학회지
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• 제35권6호
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• pp.465-476
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• 2021

Scale and rust generation in water pipes is a common phenomenon when cast iron water pipes have been used for a long time. A physical water treatment device is known among various means for suppressing rust in a water pipe, and a zinc ionization device for putting zinc metal into a pipe and emitting the zinc cation into water is one of such devices. This research measured the amount of zinc ion generated, which is known to exhibit an effect of inhibiting rust and scale generation in a pipe, and examined the scale and rust inhibition effect of the ionization device installed for ground or building water supply. In the case of distilled water, the concentration of zinc ion increased by circulating water in the ionization device several times, and it was verified to be hundreds of ㎍/L, and in the case of discharging ground or tap water, it was verified to be tens of ㎍/L. In addition, a verification pipe was installed to confirm the change inside the pipe before and after installation of the zinc ionization device, and the internal condition of the pipe was observed 3 months to several years after installation. It was confirmed that the corrosion area of the surface of the pipe was no longer increased by installing a corrosion inhibitor, and if the pipe was already filled with corrosion products, the amount of corrosion products gradually decreased every year after installation. The phenomenon of fewer corrosion products could be interpreted as expanding the space in the pipe due to the corrosion product as Fe₂O₃ adhered to the inner surface of the pipe and turned into a smaller black Fe₃O₄. In addition, we found that scale such as CaCO₃ together in the corrosion by-products gradually decreased with the attachment of the ionization device.

• 대한기계학회논문집
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• 제17권6호
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• pp.1404-1411
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• 1993

본 연구는 오스템퍼링 온도와 유지시간을 변화시켜 오스템퍼링 한 저합금구 상흑연주철을 실험재로 하여 증류수 및 NaCI수용액 중에서의 부식마멸특성 및 그 기구 를 규명하여 Tribology 설계에 대한 자료를 제시하는 것을 목적으로 하였다.

• 박물관보존과학
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• 제7권
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• pp.25-31
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• 2006

경남 창녕군 화왕산성에서 발굴된 비격진천뢰의 보존처리를 실시하였다. 비격진천뢰는 일부 결실된 상태였다. 단, 결실된 부분은 내부를 관찰할 수 있도록 복원처리를 실시하지 않았다. X-선 투과검사 및 C.T(Computed Tomography)촬영 결과 주조과정에서 주형선 주위에 기공이 많이 발생한 것을 확인할 수 있었고, 표면에는 주조시 내범을 유지하기 위한 형지공이 확인되었으며, 이 부분에 다시 철판을 덧대어 보강한 흔적도 확인할 수 있었다. 표면에 존재하는 청색 부식물의 주성분은 SEM/EDS 분석결과 산소(O), 철(Fe), 인(P), 규소(Si), 알루미늄(Al)이라는 것을 확인하였으며, XRD 분석결과 청색 부식물은 비비아나이트[vivianite, Fe₃(PO₄)₂·8H₂O]로 확인되었다. 그리고 미세조직 분석결과 전형적인 회주철조직으로 판명되었다.