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권의혁,장성환,한정환,김병수,정진기,이재천,Kwon Eui-Hyuk,Jang Sung-Hwan,Han Jeong-Whan,Kim Byung-Su,Jeong Jin-Ki,Lee Jae-Chun 한국재료학회 2005 한국재료학회지 Vol.15 No.1
It is well known that PCB (Printed Circuit Board) is a complex mixture of various metals mixed with various types of plastics and ceramics. In this study, high temperature pyre-metallurgical process was investigated to extract valuable metallic components from the PCB scrap. For this purpose, PCB scrap was shredded and oxidized to remove plastic materials, and then, quantitative analyses were made. After the oxidation of the PCB scrap, $30.6wt\%SiO_2,\;19.3wt\%Al_2O_3\;and\;14wt{\%}CaO$ were analyzed as major oxides, and thereafter, a typical composition of $32wt\%SiO_2-20wt\%Al_2O_3-38wt{\%}CaO-10wt\%MgO$ was chosen as a basic slag system for the separation of metallic components. Moreover a size effect of crushed PCB scrap was also investigated. During experiments a high frequency induction furnace was used to melt and separate metallic components. As a result, it was found that the size of oxidized PCB scrap was needed to be less 0.9 m to make a homogeneous liquid slag and to recycle metallic components over $95\%$.
폴리머 기판위에 형성된 나노구조제어 알루미나의 캐패시터 특성
정승원,민형섭,한정환,이전국,Jung, Seung-Won,Min, Hyung-Sub,Han, Jeong-Whan,Lee, Jeon-Kook 한국재료학회 2007 한국재료학회지 Vol.17 No.2
Embedded capacitor technology can improve electrical perfomance and reduce assembly cost compared with traditional discrete capacitor technology. To improve the capacitance density of the $Al_2O_3$ based embedded capacitor on Cu cladded fiber reinforced plastics (FR-4), the specific surface area of the $Al_2O_3$ thin films was enlarged and their surface morphologies were controlled by anodization process parameters. From I-V characteristics, it was found that breakdown voltage and leakage current were 23 V and $1{\times}10^{-6}A/cm^2$ at 3.3 V, respectively. We have also measured C-V characteristics of $Pt/Al_2O_3/Al/Ti$ structure on CU/FR4. The capacitance density was $300nF/cm^2$ and the dielectric loss was 0.04. This nano-porous $Al_2O_3$ is a good material candidate for the embedded capacitor application for electronic products.
유가금속(有價金屬) 회수(回收)를 위한 PCB 스크랩의 건식처리기술(乾式處理技術)
신동엽,이상동,정현부,유병돈,한정환,정진기,Shin, Dong-Yeop,Lee, Sang-Dong,Jeong, Hyeon-Bu,You, Byung-Don,Han, Jeong-Whan,Jung, Jin-Ki 한국자원리싸이클링학회 2008 資源 리싸이클링 Vol.17 No.2
폐 컴퓨터나 OA기기 중 PCB (Printed Circuit Board)에는 귀금속을 포함한 많은 양의 금속성분이 함유되어 있으며, 본 연구에서는 이들을 분리회수하기 위한 건식처리 기술을 검토하였다. 폐 컴퓨터로부터 얻은 PCB 스크랩을 산화처리한 시료에 대해 정량분석을 실시하고, 함유된 산화물 종류에 대하여 적합한 슬래그계를 선정하여 유가금속을 분리회수하기 위한 산화물 성분의 슬래그화를 시도하였다. 용융작업을 위해 슈퍼칸탈 회전로를 사용하였으며, 이때 도가니 회전이 금속의 회수율에 미치는 영향을 조사하였다. It is well known that PCB (Printed Circuit Board) is a complex mixture of various metals. In this study, pyro-metallurgical process was investigated to extract valuable metallic components from the PCB scrap. PCB scrap was shredded and oxidized to remove plastic materials, and then, quantitative analysis were made. 15 mass %$Al_2O_3-45$ mass %CaO-40 mass %$SiO_2$ and 32 mass %$SiO_2-20$ mass %$Al_2O_3-38$ mass %CaO-10 mass %MgO, were chosen as basic slag compositions which are determined based on the quantitative analysis of PCB scrap. During experiments a super kanthal rotating furnace was used to melt and separate metallic components. Moreover the revolution effect on was the recovery of valuable metals from PCB scrap also investigated.
초크랄스키법에서 도가니의 온도구배가 유동장에 미치는 영향에 대한 수치해석 연구
박종인 ( Jong In Park ),한정환 ( Jeong Whan Han ) 대한금속·재료학회 2009 대한금속·재료학회지 Vol.47 No.11
It is well known that the temperature and the flow pattern of the crystal-melt interface affect the qualities of the single crystal in the Czochralski process. Thus the temperature profile in the growth system is very important information. This work focuses on controlling the temperature of the silicon melt with a thermal gradient of the crucible. Therefore, the side heater is divided into three parts and an extra heater is added at the bottom for thermal gradient. The temperature of the silicon melt can be strongly influenced and controlled by the electric power of each heater.
산화처리된 PCB 스크랩을 첨가한 Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub>-CaO 3성분계 슬래그의 점도
권의혁,한신석,지재홍,한정환,유병돈,김병수,이재천,Kwon, Eui-Hyuk,Han, Sin-Suk,Ji, Jae-Hong,Han, Jeong-Whan,You, Byung-Don,Kim, Byung-Soo,Lee, Jae-Chun 한국재료학회 2003 한국재료학회지 Vol.13 No.4
In order to explore the possibility to extract precious metals from PCB(Printed Circuit Board) scrap by gravity separation, a high temperature melting process was adopted, from the recycling view point, to investigate the influence of viscosity on A1$_2$$O_3$-CaO$-SiO_2$ slag system composed of PCB scrap. For optimizing the pre-treatment process of PCB scrap, an experimental condition for the complete calcination and oxidation of organic materials in PCB scrap was established and a quantitative analysis of oxidized PCB scrap was also carrie out. It was found that 6 hours were enough for the complete oxidation of PCB scrap at 1273 K in an atmosphere condition. A slag, l5wt%$A1_2$$O_3$-45wt%CaO-40wt%SiO$_2$, was chosen as a basic slag composition which is determined based on the quantitative analysis of PCB scrap. Viscosities were measured in slag systems both made from pure fluxes and from PCB scrap with additional fluxes. Slag viscosities composed of pure fluxes were measured to be 5.29 poise and 30.52 poise at temperatures of 1773 and 1573 K, whereas that of PCB scrap with additional fluxes were 3.37 poise and 69.89 poise, respectively.
Ag첨가 마그네슘 합금의 이중열처리에 따른 미세조직 및 기계적 특성변화
이병덕 ( Byeong Deok Lee ),백의현 ( Ui Hyun Baek ),장경수 ( Kyoung Soo Jang ),한정환 ( Jeong Whan Han ),손현택 ( Hyeon Taek Son ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.6
To improving the mechanical properties of Mg alloys at high temperature, we investigated the mechanical properties at high temperature and the change of microstructure of Mg-6 wt%Zn-0.4 wt%Mn and Mg-6 wt%Zn-0.4 wt%Mn-1 wt%Ag alloys on age treatment that have a stable MgZn phase at high temperature and AgMg4 improving yield stress. In order to predict thermodynamic data of Mg alloys, a phase diagram and precipitation phase were calculated using a thermodynamic program, and it was confirmed that the MgZn and AgMg4 phase existed as main precipitation in this alloys. The experimental data examined using DSC and XRD were comparable with the calculated data for reliability. In order to analysis the microstructure and precipitate phase during aging treatment, it was measured by SEM/EDS and TEM. Lastly, mechanical properties of the MgZn and AgMg4 phase were measured by a tensile test at high temperature.
Pidgeon process를 통한 마그네슘 제련 공정에서의 열 환원 거동 해석
백의현 ( Ui Hyun Baek ),이병덕 ( Byeong Deok Lee ),이기우 ( Ki Woo Lee ),한길수 ( Gil Soo Han ),한정환 ( Jeong Whan Han ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.2
This study examined methods to increase the production of Mg crown and minimize the amounts of solid impurities using the thermodynamic commercial package Factsage. A thermodynamic calculation was carried out to predict the degree of reduction of Mg vapor depending on the operating parameters through a single-stage calculation method involving the use of the CaO/MgO molar ratio, ferrosilicon/ dolime mass ratio and the pressure and temperature during the Pidgeon process. The results indicate that the CaO/MgO molar ratio was 1.4~1.5 to increase the degree of the reduction of Mg vapor in a non- equilibrium state. The thermodynamic calculations were designed to examine the effect the ferrosilicon had on specific ferrosilicon/dolime ratios. A good effect was observed between 25 and 30%. Moreover, it was determined that the optimum operating conditions which offer a high purity level of magnesium and reduce the degree of vapor was the case 5 (1200 ℃, 0.1 ~ 0.01 torr). In addition, the distribution of solid impurities in the Mg crown was calculated by a multi-stage calculation method while decreasing the temperature. Solid impurities existed as compounds in the Mg crown depending on the condensation temperature range in retort. The compound was composed of Mg2Si under 700 ℃ and CaAl2 under 500 ℃, also FeAl3, MnB under 400 ℃. A comparison of the thermodynamic calculations and experimental results regarding the types of impurities were in good agreement.(Received July 2, 2015)
돌출길이 및 air gap size에 따른 가스분무 조업 시 가스거동 해석
권의혁 ( Eui Hyuk Kwon ),정훈제 ( Hun Je Jung ),장경수 ( Kyoung Soo Jang ),구용모 ( Yong Mo Koo ),한정환 ( Jeong Whan Han ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.4
The optimization of the gas atomization for particle size control and optimal energy efficiency cannot be achieved simply, due to the lack of understanding of the basic atomization process. A numerical analysis is performed in order to optimize the manufacturing process and to understand the behavior of the gas at the end of the nozzle. In this study, the gas flow is analyzed numerically using a computational fluid dynamics software package (Fluent). It is found that a protrusion length of 3 mm is optimal for nozzles with a quick gas velocity and stable aspiration pressure. In addition, the impact on the air gap size is also investigated.
턴디쉬 내 용강의 체류시간분포를 이용한 주편에서의 합금철 농도분포 예측
박종인 ( Jong In Park ),권의혁 ( Eui Hyuk Kwon ),이기우 ( Ki Woo Lee ),김종철 ( Jong Chul Kim ),한정환 ( Jeong Whan Han ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.3
In this study, the dispersion behavior of a ferroalloy containing cerium in a steel melt and the concentration along the slab length were predicted by a fluid analysis and spreadsheet-based model development in the continuous casting process. The residence time distribution of the ferroalloy according to the flow pattern was calculated and used for calculating the ferroalloy discharge rate from the tundish and concentration in the slab. Effective operating conditions for homogeneous concentration distribution of the ferroalloy were determined by controlling the injection speed and time of the ferroalloy obtained from this analysis model.