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AlN 세라믹의 hot pressing에 사용되는 Y<sub>2</sub>O<sub>3</sub> 및 Al<sub>2</sub>O<sub>3</sub> 소결조제의 효과
공만식,홍현선,이성규,서민혜,정항철,Kong, Man-Sik,Hong, Hyun-Seon,Lee, Sung-Kyu,Seo, Min-Hye,Jung, Hang-Chul 한국재료학회 2007 한국재료학회지 Vol.17 No.10
AlN plates were fabricated by hot pressing at $1700-1900^{\circ}C$ using yttria and alumina (3 and $10\;{\mu}m$ particle size) powders as additives and characterized: density, thermal conductivity, transverse rupture strength, and grain size measurement by SEM and EDS. Density values of $3.31-3.34\;g/cm^3$ are largely attributed to hot pressing of powder mixtures in carbon mold under $N_2$ atmosphere which caused effective degree of oxygen removal from yttrium-aluminate phase expected to form at $1100^{\circ}C$. The grain size of hot pressed AlN was almost homogeneous, with size approximately from 3.2 to $4.0\;{\mu}m$ after hot pressing. $Al_2O_3$ powder of $3\;{\mu}m$ particle size resulted in better transverse rupture strength and finer grain size compared to $10\;{\mu}m$ $Al_2O_3$ powder. The thermal conductivity of AlN ranged between $83-92.7\;W/m{\cdot}K$ and decreased with $Al_2O_3$ addition. Fine grain size is preferred for better mechanical properties and thermal conductivity.
공만식 ( Man Sik Kong ),김건홍 ( Geon Hong Kim ),정항철 ( Hang Chul Jung ),채홍준 ( Hong Jun Chae ) 한국공업화학회 2015 공업화학전망 Vol.18 No.5
과거 탈공업화 정책으로 인해 경제 주도권을 서비스업에 내주었던 제조업이 21세기 경제 성장과 고용창출의 중심으로 재조명되고 있다. 과거의 제조업이 기계화, 자동화, 집중화로 경제 성장과 고용창출에 기여를 했다면, 현재의 제조업은 생산 설비와 ICT 인프라가 융합된 서비스화, 디지털화라는 새로운 가능성을 제시하면서 선진국을 중심으로 제조업 부활의 가능성을 예고하고 있다. 특히 ICT 기반의 화학 산업은 국내 경제침체를 극복하는 중요한 성장 동력으로 산업으로, 최근 기술동향과 ICT 융합 시장의 변화에 대한 정부정책 및 민간투자에 대한 기초자료를 제공할 필요가 있으므로, ICT 기반 화학산업의 경제 및 산업 환경에 따른 최근 ICT-화학 융합사례를 분석하고 향후 ICT 기반 화학소재산업이 나아가야 할 방향을 제시하고자 한다.
RTK-GPS를 이용한 시공중 발생하는 구조물변위의 웨이브릿, 칼만필터 해석
공만식(Kong Man Sik),윤홍식(Yoon Hong Sik),황진상(Hwang Jin Sang),염민교(Youm Min Kyo) 한국측량학회 2012 한국측량학회 학술대회자료집 Vol.2012 No.4
본 연구에서는 조석간만의 차로 설치중인 교각의 기초부분에서 발생하는 구조물의 변위를 RTK-GPS를 사용하여 구조물 거동의 건전도 평가에 사용 하였다. 측정 시에 사용한 필터링방법은 웨이브릿 대역필터와 칼만필터를 사용하였다. RTK-GPS 관측 에는 24시간 관측과 8시간 관측 2가지를 나누어 관측하였다. 획득한 RTK-GPS 관측 값을 칼만 필터와 웨이브릿 대역필터를 이용하였으며 그 밖의 과대오차를 소거하기위하여 3σ공식을 사용하여 필터링 하였다. 필터링을 통하여 시간대별 구조물의 거동을 추정하는 정확도가 향상되었음을 확인할 수 있다. In this study, the tidal bridge is being installed ebb and high tide that is raised at the base of the displacement of the structure using RTK-GPS Integrity Assessment of the behavior of structures were used. When measured using the wavelet band filtering method was used to filter and Kalman filter. RTK-GPS observations and a 24-hour observation for eight hours into two kinds of observations were observed. RTK-GPS observation values obtained with the Kalman filter was used for wavelet bandpass filters and other blunder to clear the filter using the official was 3σ. Hourly through filtering to estimate the behavior of the structure can be found that improves the accuracy.
주조용 TiAl 합금의 조직 미세화를 위한 반복열처리 공정 조건에 관한 연구
공만식 ( Man-sik Kong ),양현석 ( Hyunseok Yang ) 한국열처리공학회 2019 熱處理工學會誌 Vol.32 No.5
For expanding the applications and workability of TiAl alloy, elongation is very important property. Fine microstructure is needed for elongation and physical properties of TiAl alloys. In this study, The effects of cyclic heat treatment process for fine microstructure of Ti-46Al-Nb-W-Cr-Si-C alloy, which was made by VAR (vacuum arc remelting) and VIM(vacuum induction melting) centrifugal casting process, was investigated. Cycle heat treatment process was very effective for recrystallization of this TiAl system, which has microstructure size of 50~100 μm through pre-heat treatment, cyclic heat treatment in α+γ phase region and solution heat treatment respectively. Refined grain size was finally confirmed by photos of optical microscope and scanning electron microscope.
킬레이트 수지를 이용한 구리 합금 부산물에서의 니켈의 농축 및 분리
이정일,공만식,류정호,Lee, Jung-Il,Kong, Man-Sik,Ryu, Jeong Ho 한국결정성장학회 2013 韓國結晶成長學會誌 Vol.23 No.2
최근 금속자원 재활용과 환경보호에 대한 기술적 필요성에 의해 구리(Cu)를 주성분으로 하는 동합금으로부터 니켈, 주석 등의 유가금속 분리/회수에 대한 관심이 높아지고 있다. 본 연구에서는 동합금에 포함된 유가금속들을 분리/회수하는 기초연구중 하나로서, 킬레이트 수지를 이용하여 동합금 제련시 발생하는 부산물에 포함되어 있는 대표적인 유가금속인 니켈(Ni)을 분리/추출할 수 있는 농축 공정의 가능성에 대해 검토하였다. 킬레이트 수지는 원자량이 높은 $Cu^{2+}$ 이온을 $Ni^{2+}$ 이온보다 선택적으로 흡수하였으며, 이러한 과정을 수차례 반복함으로써 실제 동합금 부산물 샘플의 $Ni^{2+}$ 및 $Cu^{2+}$ 이온을 농축할 수 있었으며, XRF 분석을 통하여 각각 70 % 및 99 %의 농도로 분리할 수 있음을 확인하였다. Separation/recovery of valuable metals such as nickel or tin from copper based alloys has recently attracted from the viewpoints of environmental protection and resource recycling. In this report, preliminary study on concentration and separation of nickel from copper based alloy dross using selective adsorption by chelate resin was performed. The chelate resin used in this study has absorbed copper ions more easily than nickel ions in the metal solution, which could allow the concentration/separation of the nickel from the copper base alloy solution. The final molar ratios of Ni and Cu ions in the two concentrated solutions were 70 and 99 % respectively after three-time flowing the solution through the chelate resin column.
Pulse-reverse도금을 이용한 다층 PCB 빌드업 기판용 범프 생성특성
서민혜,공만식,홍현선,선지완,공기오,강계명,Seo, Min-Hye,Kong, Man-Sik,Hong, Hyun-Seon,Sun, Jee-Wan,Kong, Ki-Oh,Kang, Kae-Myung 한국재료학회 2009 한국재료학회지 Vol.19 No.3
Micro-scale copper bumps for build-up PCB were electroplated using a pulse-reverse method. The effects of the current density, pulse-reverse ratio and brightener concentration of the electroplating process were investigated and optimized for suitable performance. The electroplated micro-bumps were characterized using various analytical tools, including an optical microscope, a scanning electron microscope and an atomic force microscope. Surface analysis results showed that the electroplating uniformity was viable in a current density range of 1.4-3.0 A/$dm^2$ at a pulse-reverse ratio of 1. To investigate the brightener concentration on the electroplating properties, the current density value was fixed at 3.0 A/$dm^2$ as a dense microstructure was achieved at this current density. The brightener concentration was varied from 0.05 to 0.3 ml/L to study the effect of the concentration. The optimum concentration for micro-bump electroplating was found to be 0.05 ml/L based on the examination of the electroplating properties of the bump shape, roughness and grain size.
폐(廢) 냉장고(冷藏庫) 재활용(再活用) 현황(現況)과 기술(技術) 전망(展望)
양현석,김건홍,공만식,박기진,이광원,김보생,Yang, Hyunseok,Kim, Geon-Hong,Kong, Man-Sik,Park, Kiejin,Lee, Gwang Weon,Kim, Bo Saeng 한국자원리싸이클링학회 2013 資源 리싸이클링 Vol.22 No.4
냉장고는 폐 전기전자제품(WEEE)에서 가장 많은 양이 처리되고 있는 품목이며 또한 가장 재활용이 복잡한 공정이다. 이는 가전제품 중 부피와 중량이 가장 크며 철, 비철금속, 플라스틱(PP, PS, ABS)등으로 이루어진 다양한 부품과 소재를 사용하고 있기 때문이다. 특히 최근에는 대용량 양문형 냉장고나 스탠드형 김치냉장고 등의 새로운 모델 출시와 더불어 다양한 혼합 재질의 사용으로 인해 폐 냉장고 재활용 공정의 어려움이 더욱 증가되고 있다. 뿐만 아니라 국내외 WEEE 재활용 관련 입법의 도입으로 폐 냉장고의 재활용 및 재자원화는 필수이고 관련 자원순환기술개발은 국가 기술경쟁력의 강화 및 국제 환경규제 대응 측면에서도 매우 중요하다고 할 수 있다. 따라서 현재 우리나라의 폐 냉장고 재활용 처리 및 기술개발 현황을 분석하고 선진국의 재활용 기술을 비교 분석하고자 한다. Waste refrigerator is the most large amount of item being recycled and the recycling process is the most complicated in WEEE (Waste Electrical and Electronic Equipment) because refrigerator is biggest product and consists of various parts and materials such as ferrous, non-ferrous, and plastics. Recently, recycling process of waste refrigerator has been being more complex since large capacity 2 door refrigerators and standing Kimchi refrigerators with various material are distributed on custom market. In addition, recycling of valuable resource from waste refrigerator is mandatory by WEEEs recycling legislation; therefore, high efficiency recycling enough for economic and environment-friendly recovery of valuable resource through present technical situation analysis and comparison of recycling technologies of waste refrigerator with advanced country.
MoS<sub>2</sub> 첨가에 따른 Fe-Cr-Mn-C-V계 소결합금의 기계적 특성 평가
김건홍,양현석,공만식,Kim, Geon-Hong,Yang, Hyun Seok,Kong, Man-Sik 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.4
The connecting rod is one of the most important parts in automotive engines, transforming the reciprocal motion of a piston generated by internal combustion into the rotational motion of a crankshaft. Recent advances in high performance automobile engines demand corresponding technological breakthroughs in the materials for engine parts. In the present research, the powder metallurgy (P/M) process was used to replace conventional quenching and/or tempering processes for mass production and ultimately for more cost-efficient manufacturing of high strength connecting rods. The development of P/M alloy powder was undertaken not only to achieve the improvement in mechanical properties, but also to enhance the machinability of the P/M processed connecting rods. Specifically $MoS_2$ powders were added as lubricants to non-normalizing Fe-Cr-Mn-V-C alloy powder to improve the post-sintering machinability. The effects of $MoS_2$ addition on the microstructure, mechanical properties, and machining characteristics were investigated.
수증기 메탄 개질 반응을 이용한 수소 생산용 Ni-Cr-Al 다공체 지지 촉매의 제조, 기계적 안정성 및 수소 환원 효율
김규식,강태훈,공만식,박만호,윤중열,안지혜,이기안,Kim, Kyu-Sik,Kang, Tae-Hoon,Kong, Man Sik,Park, Man-Ho,Yun, Jung-Yeul,Ahn, Ji Hye,Lee, Kee-Ahn 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.3
Ni-Cr-Al metal-foam-supported catalysts for steam methane reforming (SMR) are manufactured by applying a catalytic Ni/Al<sub>2</sub>O<sub>3</sub> sol-gel coating to powder alloyed metallic foam. The structure, microstructure, mechanical stability, and hydrogen yield efficiency of the obtained catalysts are evaluated. The structural and microstructural characteristics show that the catalyst is well coated on the open-pore Ni-Cr-Al foam without cracks or spallation. The measured compressive yield strengths are 2-3 MPa at room temperature and 1.5-2.2 MPa at 750℃ regardless of sample size. The specimens exhibit a weight loss of up to 9-10% at elevated temperature owing to the spallation of the Ni/Al<sub>2</sub>O<sub>3</sub> catalyst. However, the metal-foam-supported catalyst appears to have higher mechanical stability than ceramic pellet catalysts. In SMR simulations tests, a methane conversion ratio of up to 96% is obtained with a high hydrogen yield efficiency of 82%.