스마트 적층제조 공정 최적화 방안

최균석 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.5

UV/O_3와 ECR 플라즈마를 이용한 wafer storage box로부터 발생하는 Si 웨이퍼 표면 위의 유기오염물 제거

崔均碩,林鍾旻,李鍾武,羅寬球,朴相俊 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.7

The problem of organic contamination is still there due to the outgassing from the plastic materials in the storage boxes. Such organic contaminants have deleterious effects not only on the gate oxide integrity, but also on the chemical vapor deposition steps. In this paper, we report the experimental results for the removal of the organic contaminants existing on wafer surfaces by UV/O_3 cleaning, ECR H_2 plasma and ECR O_2 plasma cleaning. After cleaning, Si wafers were analyzed by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Atomic Force Microscrope(AFM). The ECR oxygen plasma cleaning technique seems to be more effective than the ECR hydrogen plasma or the UV/O_3 cleaning technique for the removal of organic contaminants. Also, organic contaminants removal mechanisms of UV/O_3 cleaning, ECR H_2 plasma and ECR O_2 plasma cleaning are discussed.

Magnesiothermic Reduction for Direct Synthesis of Ti-Nb Alloy at 1073 K (800 °C)

최균석,이광희,Basit Ali,최상훈,박경태,손일 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.5

Direct fabrication of titanium (Ti) and niobium (Nb) alloys by direct magnesiothermic reduction from the respectiveinitial metal oxides and complex oxides has been studied. TiO2, Nb2O5, and complex TiNb2O7 oxides wereused as raw materials with Mg used as a reductant. To ensure a high chemical potential of the reactants to drive thespontaneous magnesiothermic reduction of the oxide mixtures, excess Mg five times higher than the required stoichiometricmolar ratio was added. Samples were heated in a glove box under recycled and purified Ar atmosphereat 1073 K (800 °C) for 10 h. After the reduction of TiO2, intermediate oxide phases of Ti6O could still be observed,but reduction of Nb2O5 and TiNb2O7 showed metallic Nb and Ti-Nb to be present with negligible oxides accordingto the scanning electron microscope-energy dispersive spectroscopy and x ray diffraction analysis. This indicatedthat direct fabrication of Ti-Nb alloys through a complex TiNb2O7 oxide is possible and can be more efficient thanalloying pure metallic elements of Ti and Nb.

철도 전철 부품의 스마트 제조기술 기초연구

최균석(Kyunsuk Choi),김주욱(Joo-Uk Kim),이기원(Kiwon Lee),서경주(Kyoung-Ju Seo),박영(Young Park) 대한전기학회 2020 전기학회논문지 Vol.69 No.10

Recently, smart manufacturing technology research is being conducted in various fields, using digital parts-based technologies. Components that are used for electrification in electric railways are manufactured using casting techniques. This is because the mechanical and electrical properties required to ensure safety considerably vary, and the standards defined for errors are strict. To apply digital parts-based manufacturing technology to parts for electrification, the design of existing parts must be 3D-modelled, and research must be conducted on manufacturing techniques using metals. In this study, we investigated digital laminate manufacturing technology for smart manufacturing of parts for electrification. The clevis-type terminal clamp of the contact wire was manufactured using stereolithography apparatus. The deviation, which was measured using a 3D hybrid scanner and a 3D coordinate measuring device, was observed to be approximately ± 500 μm. The model illustrated in this paper will be used as a reference to study metal train parts in the future. In addition, it is expected to be used as a pre-modelling development technology for manufacturing singular-shaped parts.

전해 크롬도금 대체용으로서의 CrC 스퍼터링에 관한 연구

임종민,최균석,이종무,Im, Jong-Min,Choe, Gyun-Seok,Lee, Jong-Mu 한국재료학회 2002 한국재료학회지 Vol.12 No.1

Chromium carbide films were deposited on high speed steels using a Cr_3C_2$ target by magnetron sputtering. Effects of the deposition parameters (power, Ar pressure and substrate temperature) on deposition rates and surface roughnesses of the films were investigated. The morphologies of those films were characterized by scanning electron microscopy and atomic force microscopy. The grain size of the samples deposited using dc-power is larger than that using equivalent rf-power. The hardness of the sample increases with increasing rf-power, whereas the elastic modulus nearly does not change with rf-power. The optimum sputter deposition conditions for chromium carbide on high speed steels in the corrosion resistance aspect were found to be the rf-power with small roughness.

급속 리뉴얼을 위한 전기철도 전철부품 제작 연구

김주욱,정호성,박정준,황선우,최균석,박영 한국철도학회 2021 한국철도학회논문집 Vol.24 No.5

전기철도의 전차선로는 다양한 부품의 조합으로 이루어져 있으며 차량 팬터그래프와의 접촉과 전기 에너지 전달을 위해 일정 이상의 기계적, 전기적 특성을 유지하여야 하며 이를 위해 금속제품을 주조방식으로 제조하고 있다. 전차선로는 속도에 따라 부품의 치수와 성능이 다르며 유지보수나 리뉴얼에 따라 부품 단종 시에 소량의 제작에도 주물을 제작하여야 하며 일부 제품은 규격이 없어 소품종 생산에 적합한 기술이 필요하다. 본 논문은 3D 프린팅을 이용한 클레비스형 단말클램프와 회전형 클립 제작을 위해 기존의 2차원 도면을 3D 각각 3차원 모델링을 수행하였다. 제작후 기계적 특성 시험결과 인장강도와 내력은 532 N/㎟와 189 N/㎟로 KRSA의 기준값인 600 N/㎟과 250 N/㎟에 비해 낮은 특성을 나타내었다. 재료의 화학적 특성 분석 결과 Ni가 다소 낮게 나타났으나 본 논문에서 제안한 3차원 모델링 기반의 전철부품 제작 기술은 설계, 제작 및 시공을 연계하거나 부품 보강을 통한 전차선로 특성향상기술에 활용될 것으로 기대된다.

PBF 적층 제조 공정 중 매크로 해석을 통한 불균일 단면의 support별 열 누적 최소화에 관한 연구

윤석철,신재호,김재웅,최균석 대한전기학회 2024 전기학회논문지 Vol.73 No.2

In this study, a numerical analysis model was developed for temperature distribution history analysis. To verify the numerical model, the temperature accumulation results analyzed through simulation were compared with the temperature accumulation results for each layer measured with an IR camera. Through temperature distribution history analysis using the commercial program vAMfire/Macro Ⓡ, the maximum height at which the maximum temperature is reached in each process according to the change in cross-sectional area was predicted. In addition, the temperature distribution history for each support was analyzed considering general support, wall support, and modified wall support to minimize heat dissipation and heat accumulation. The difference in heat dissipation effect depending on the type of support was quantitatively analyzed. By applying optimal support, we were able to solve the stacking problem caused by heat accumulation. Through heat transfer analysis, it was confirmed that quantitative analysis was possible to solve problems such as lamination failure and thermal deformation.

3D 프린팅 출력물을 위한 3D 모델링의 오류 분석과 해결방안

서경주(Kyoung-Ju Seo),최균석(Kyunsuk Choi),김호영(Hoyoung Kim) 대한전기학회 2023 전기학회논문지 Vol.72 No.2

전기철도 전차선로 부품의 3차원 디지털화 연구

홍석진,이종우,이기원,최균석,박영 한국철도학회 2022 한국철도학회논문집 Vol.25 No.5

In electric railway, the OCS (Overhead Contact System) is designed in consideration of the material, shape, and wave propagation speed of the contact wire in order to supply electric energy stably to the railway vehicle. Although the Korean railway standards define electrical and mechanical characteristic values to ensure the safety of parts, it is difficult to confirm the manufacturing tolerances required for the assembly interface between parts and mutual assembly. Reliability of manufacturing tolerances is required for OCS products, and it is necessary to determine the connectivity with all part; also, study the reverse engineering process for the parts without drawings. Therefore, in this paper, 3D data of parts for the introduction of digital-based parts management system in the OCS was implemented. For digital data production, a 3D scanner was used to scan a swivel clip applied to a steady arm, and reverse engineering was used to produce 3D data. In addition, the data produced for the analysis of the ability to assemble of the parts and products using 3D printer were compared to confirm the conformity.

L-PBF 제조공정에서 17-4PH 스테인리스 강의 Down-skin 영역 미세조직 및 기계적 물성에 관한 연구

김영경,어두림,이승호,최균석 대한전기학회 2024 전기학회논문지 Vol.73 No.2

17-4 Precipitation Hardening Stainless Steel(17-4PH SS) is a material with excellent corrosion resistance and high strength and has recently been widely used to make parts of complex shapes through the Laser Powder Bed Fusion(L-PBF) process. The high strength is expressed by fine and uniform precipitation of Cu deposits in the martensite matrix tissue. However, in the L-PBF process, laser is selectively irradiated on metal powder to melt and solidify the local area repeatedly, and even if 17-4 PH SS powder of the same composition is used and the process conditions are kept uniform, the cooling rate and thermal history of each area are different depending on the shape of the sculpture. As a result, it appears a different microstructure(martensite fraction, etc.) depending on the area of the final stack, resulting in uneven mechanical properties. In particular, in the case of L-PBF products with complex geometries, heat dissipation is not smooth in the Down-skin area, so stacking failures frequently occur , or even if they are successful, unexpected problems with weak mechanical property occur frequently. These results could be suggested for observing microstructure and mechanical properties on the Down-skin area of 17-4PH Stainless Steel processed by Laser-Powder Bed Fusion.