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Though-silicon-via를 사용한 3차원 적층 반도체 패키징에서의 열응력에 관한 연구
황성환,김병준,정성엽,이호영,주영창,Hwang, Sung-Hwan,Kim, Byoung-Joon,Jung, Sung-Yup,Lee, Ho-Young,Joo, Young-Chang 한국마이크로전자및패키징학회 2010 마이크로전자 및 패키징학회지 Vol.17 No.1
Through-silicon-via (TSV)를 포함하고 있는 3차원 적층 반도체 패키지에서 구조적 변수에 따른 열응력의 변화를 살펴보기 위하여 유한요소해석을 수행하였다. 이를 통하여 TSV를 포함하고 있는 3차원 적층 반도체 패키지에서 웨이퍼 간 접합부의 지름, TSV 지름, TSV 높이, pitch 변화에 따른 열응력의 변화를 예측하였다. 최대 von Mises 응력은 TSV의 가장 위 부분과 Cu 접합부, Si, underfill 계면에서 나타났다. TSV 지름이 증가할 때, TSV의 가장 위 부분에서의 von Mises 응력은 증가하였다. Cu 접합부 지름이 증가할 때, Si과 Si 사이의 Cu 접합부가 Si, underfill과 만나는 부분에서 von Mises 응력이 증가하였다. Pitch가 증가할 때에도, Si과 Si 사이의 Cu 접합부가 Si, underfill과 만나는 부분에서 von Mises 응력이 증가하였다. 한편, TSV 높이는 von Mises 응력에 크게 영향을 미치지 못하였다. 따라서 TSV 지름이 작을수록, 그리고 pitch가 작을수록 기계적 신뢰성은 향상되는 것으로 판단된다. Finite-element analyses were conducted to investigate the thermal stress in 3-dimensional stacked wafers package containing through-silicon-via (TSV), which is being widely used for 3-Dimensional integration. With finite element method (FEM), thermal stress was analyzed with the variation of TSV diameter, bonding diameter, pitch and TSV height. It was revealed that the maximum von Mises stresses occurred at the edge of top interface between Cu TSV and Si and the Si to Si bonding site. As TSV diameter increased, the von Mises stress at the edge of TSV increased. As bonding diameter increased, the von Mises stress at Si to Si bonding site increased. As pitch increased, the von Mises stress at Si to Si bonding site increased. The TSV height did not affect the von Mises stress. Therefore, it is expected that smaller Cu TSV diameter and pitch will ensure mechanical reliability because of the smaller chance of plastic deformation and crack initiation.
Phosphorus-Doped ZnO 나노로드의 열처리 효과
황성환,문경주,이태일,명재민,Hwang, Sung-Hwan,Moon, Kyeong-Ju,Lee, Tae Il,Myoung, Jae Min 한국재료학회 2013 한국재료학회지 Vol.23 No.5
An effect of thermal annealing on activating phosphorus (P) atoms in ZnO nanorods (NR) grown using a hydrothermal process was investigated. $NH_4H_2PO_4$ used as a dopant source reacted with $Zn^{2+}$ ions and $Zn_3(PO_4)_2$ sediment was produced in the solution. The fact that most of the input P elements are concentrated in the $Zn_3(PO_4)_2$ sediment was confirmed using an energy dispersive spectrometer (EDS). After the hydrothermal process, ZnO NRs were synthesized and their PL peaks were exhibited at 405 and 500 nm because P atoms diffused to the ZnO crystal from the $Zn_3(PO_4)_2$ particles. The solubility of the $Zn_3(PO_4)_2$ initially formed sediment varied with the concentration of $NH_4OH$. Before annealing, both the structural and the optical properties of the P-doped ZnO NR were changed by the variation of P doping concentration, which affected the ZnO lattice parameters. At low doping concentration of phosphorus in ZnO crystal, it was determined that a phosphorus atom substituted for a Zn site and interacted with two $V_{Zn}$, resulting in a $P_{Zn}-2V_{Zn}$ complex, which is responsible for p-type conduction. After annealing, a shift of the PL peak was found to have occurred due to the unstable P doping state at high concentration of P, whereas at low concentration there was little shift of PL peak due to the stable P doping state.
ZnO 나노 막대 성장을 위한 기판층으로서 hexagonal β상 Ni(OH)<sub>2</sub> 나노 시트 합성 및 미세구조 분석
황성환,이태일,최지혁,명재민,Hwang, Sung-Hwan,Lee, Tae-Il,Choi, Ji-Hyuk,Myoung, Jae-Min 한국재료학회 2011 한국재료학회지 Vol.21 No.2
As a growth-template of ZnO nanorods (NR), a hexagonal $\beta-Ni(OH)_2$ nanosheet (NS) was synthesized with the low temperature hydrothermal process and its microstructure was investigated using a high resolution scanning electron microscope and transmission electron microscope. Zinc nitrate hexahydrate was hydrolyzed by hexamethylenetetramine with the same mole ratio and various temperatures, growth times and total concentrations. The optimum hydrothermal processing condition for the best crystallinity of hexagonal $\beta-Ni(OH)_2$ NS was determined to be with 3.5 mM at $95^{\circ}C$ for 2 h. The prepared $Ni(OH)_2$ NSs were two dimensionally arrayed on a substrate using an air-water interface tapping method, and the quality of the array was evaluated using an X-ray diffractometer. Because of the similarity of the lattice parameter of the (0001) plane between ZnO (wurzite a = 0.325 nm, c = 0.521 nm) and hexagonal $\beta-Ni(OH)_2$ (brucite a = 0.313 nm, c = 0.461 nm) on the synthesized hexagonal $\beta-Ni(OH)_2$ NS, ZnO NRs were successfully grown without seeds. At 35 mM of divalent Zn ion, the entire hexagonal $\beta-Ni(OH)_2$ NSs were covered with ZnO NRs, and this result implies the possibility that ZnO NR can be grown epitaxially on hexagonal $\beta-Ni(OH)_2$ NS by a soluble process. After the thermal annealing process, $\beta-Ni(OH)_2$ changed into NiO, which has the property of a p-type semiconductor, and then ZnO and NiO formed a p-n junction for a large area light emitting diode.
위암 환자에서 p53 , DCC 및 nm23 유전자 변이의 발현 양상과 임상적 의의
황성환(Sung Hwan Hwang),오상훈(Sang Hoon Oh),최영길(Young Kil Choi) 대한소화기학회 2001 대한소화기학회지 Vol.38 No.5
Background/Aims: Multiple gene abnormalities are observed in gastric carcinogenesis. We analyzed the mutation of p53, DCC and nm23 genes in gastric carcinoma and evaluated their clinical significance. Methods: Mutations of p53, DCC and nm23 genes were investigated using PCR-SSCP analysis in 40 patients with gastric carcinoma. The correlations between mutations of these genes and clinicopathologic variables or prognosis were examined. Results: The incidence of mutation in the p53, DCC and nm23 genes were 47.5%, 30.0% and 25.0%, respectively. The mutation of the p53 genes significantly correlated with lymph node metastasis and lymphatic invasion. The mutation of the nm23 genes showed a significant correlation with tumor size, histologic type, depth of invasion, lymph node metastasis, and venous invasion. The mutation of the DCC genes had no correlation with clinicopathologic variables. The overall 5-year survival rate of the patients was 60.0%. The mutation of the p53 and nm23 genes significantly affected on survival of the patients, but mutation of the DCC genes did not. By multivariate analysis, the most significant prognostic factors were lymph node metastasis and depth of invasion. The mutation of p53, DCC, and nm23 genes had little prognostic value in gastric carcinoma. Conclusions: It is suggested that the mutation of the p53 and nm23 genes may have a role in the tumor invasion and metastasis in gastric carcinoma, possibly leading to a poor prognosis. (Korean J Gastroenterol 2001;38:325-335)
황성환 ( Sung Hwan Hwang ),안태호 ( Tae Ho Ahn ) 한국경영공학회 2014 한국경영공학회지 Vol.19 No.3
ROK`s paradigm regarding Weapons Acquisition based on reinforcing military strength via Defense R&D(Research and Development) requires careful risk management when it comes to promoting research development programs. First procedure in risk management of national defense research and development project is to identify risk factors affecting the performance. Through in-depth management of these risk factors, we may minimize a possibility of program failure. Thus, for this research we have suggested national defense research development risk factors categorization system through advanced research review, survey, search and confirmatory factor analysis. Upon reviewing, areas of national defense research development risk factors have been categorized in 10 areas with 2~4 factors for each of the relevant areas summing up to 29 risk factors in total. The risk factor categorization system suggested from this research will serve as a foundation in ROK national defense research development program risk management process and minimize failures of programs.