신경망을 이용한 냉간단조품의 금형형상 설계

김동진,김태형,김병민,최재찬,Kim, D.J,Kim, T.H,Kim, B.M,Choi, J.C 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.5

In practice, the design of forging processes is performed based on an experience-oriented technology, that is designer's experience and expensive trial and errors. Using the finite element simulation and the artificial neural network, we propose an optimal die geometry satisfying the design conditions of final product. A three-layer neural network is used and the back propagation algorithm is employed to train the network. An optimal die geometry that satisfied the same between inner extruded rib and outer extruded one is determined by applying the ability of function approximation of neural network. The neural networks may reduce the number of finite element simulation for determine the optimal die geometry of forging products and further they are usefully applied to physical modelling for the forging design.

AuSn 솔더 박막의 스퍼터 증착 최적화와 접합강도에 관한 연구

김동진,이택영,이홍기,김건남,이종원,Kim, D.J.,Lee, T.Y.,Lee, H.K.,Kim, G.N.,Lee, J.W. 한국마이크로전자및패키징학회 2007 마이크로전자 및 패키징학회지 Vol.14 No.2

본 연구에서는 Au 와 Sn을 rf-magnetron sputter를 이용하여 다층막(multilayer)과 동시증착(Co-sputter)방법으로 스퍼터링하여 기판위에 AuSn 솔더를 형성하였고, 솔더의 조성제어와 특성 분석을 통해 Sn rich AuSn 솔더의 형성 기술에 대하여 연구하였다. AuSn 솔더를 형성하기 앞서 Au와 Sn에 대하여 단일 금속 증착을 하였다. 이를 토대로 AuSn솔더를 증착하기 위한 실험 조건을 확보하였다. 증착변수로는 기판의 온도, rf 전력과 두께 비를 이용하였다. 다층막의 경우, 고온의 기판에서 솔더 합금의 표면거칠기와 조성이 보다 정확하게 제어되었다. 이에 비해 동시증착 솔더는 기판의 온도에 의한 조성의 변화가 거의 없었으나, rf전력에 의해서 조성이 보다 쉽게 제어할 수 있었다. 여기에 더해, 동시 증착 솔더 박막의 대부분은 증착동안에 금속간 화합물로 변화한 것을 알 수 있었다. 화합물의 종류는 XRD로 분석하였다. 형성된 솔더 박막을 플럭스를 이용하지 않고 리드프레임에 접합하여 접합강도를 측정하였다. 다층형의 경우 Au 10wt%의 조건에서 최대 $33(N/mm^2)$ 전단응력을 나타내었으며, 동시증착형은 Au 5wt%에서 $460(N/mm^2)$ 전단응력을 나타내었다. Au-Sn solder alloy were deposited in multilayer and co-sputtered film by rf-magnetron sputter and the composition control and analysis were studied. For the alloy deposition condition, each components of Au or Sn were deposited separately. On the basis of pure Sn and Au deposition, the deposition condition for Au-Sn solder alloy were set up. As variables, the substrate temperature, the rf-power, and the thickness ratio were used for the optimum composition. For multilayer solder alloy, the roughness and the composition of solder alloy were controlled more accurately at the higher substrate temperature. In contrast, for co-sputtered solder, the substrate temperature influenced little to the composition, but the composition could be controlled easily by rf-power. In addition, the co-sputtered solder film mostly consisted of intermetallic compound, which formed during deposition. The compound were confirmed by XRD. Without flux during bonding of solder alloy film on leadframe, the adhesion strength were measured. The maximum shear stress was $330(N/mm^2)$ for multilayer solder with Au 10wt% and $460(N/mm^2)$ for co-sputtered solder with Au 5wt%.

KMTNet 자료처리 시스템 설계와 측광데이터베이스 구축

김동진,이충욱,김승리,박병곤,이재우,Kim, D.J.,Lee, C.U.,Kim, S.L.,Park, B.G.,Lee, J.W. 한국천문학회 2009 天文學論叢 Vol.24 No.1

We have designed data processing server system to include data archiving, photometric processing and light curve analysis for KMTNet (Korea Microlensing Telescope Network). Outputs of each process are reported to the main photometric database, which manages the whole processing steps and archives the photometric results. The database is developed using ORACLE 11g Release 2 engine. It allows to select objects applying any set of criteria such as RA/DEC coordinate and Star ID, etc. We tested the performance of the database using the OGLE photometric data. The searching time for querying 70,000,000 records was under 1 second. The database is fully accessed using query forms via web page.

Review on bioleaching of uranium from low-grade ore

김동진,안종관,윤호성,Patra, A.K.,Pradhan, D.,Kim, D.J.,Ahn, J.G,Yoon, H.S. 한국자원리싸이클링학회 2011 資源 리싸이클링 Vol.20 No.2

본 총설은 광석으로부터 우라늄의 미생물 침출시 사용하는 Acidithiobacillus forrooxidans, Acidithiobacillus thiooxidans 그리고 Leptospirillum ferrooxidans 등에 역할과 침출반응에 관하여 기술하였다. 미생물에 의한 우라늄의 침출반응은 박테리아가 우라늄 광석과 직접 반응하기 보다는 박테리아가 $U^{4+}$를 산화시키는데 필요한 $Fe^{3+}$를 공급하고, $Fe^{3+}$가 우라늄 광석과 반응하는 간접반응기구(indirect mechanism)에 의하여 일어난다. 건식제련법과 같은 전통적인 금속회수 공정에 비하여 환경친화적이고 경제적인 장점 때문에 저품위 광물자원으로부터 유기금속을 회수하는데 미생물 제련법이 널리 활용되고 있다. 현재 우라늄은 heap, dump 그리고 in situ를 이용한 미생물 침출법으로 회수되고 있다. Bioheap의 공기 투입량, 교반반응용기의 디자인 및 조업 개선 분야에서 기술개발이 지속적으로 이루어졌으며 최근에는 미생물 침출반응에 투입된 박테리아의 특성 개선 및 균주수를 제어하기 위한 molecular biology 분야에서 활발한 연구가 진행되고 있다. This review describes the involvement of different microorganisms for the recovery of uranium from the ore. Mainly Acidithiobacillus forrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans are found to be the most widely used bacteria in the bioleaching process of uranium. The bioleaching of uranium generally follows indirect mechanism in which bacteria provide the ferric iron required to oxidize $U^{4+}$. Commercial applications of bioleaching have been incorporated for extracting valuable metals, due to its favorable process economics and reduced environmental problems compared to conventional metal recovery processes such as smelting. At present the uranium is recovered through main bioleaching techniques employed by heap, dump and in situ leaching. Process development has included recognition of the importance of aeration of bioheaps, and improvements in stirred tank reactor design and operation. Concurrently, knowledge of the key microorganisms involved in these processes has advanced, aided by advances in molecular biology to characterize microbial populations.

부상식 상향류 생물여과 장치 개발에 관한 연구

김동진,김건협,차기철,이규현,이용택,이태진 ( D . J . Kim,G . H . Kim,G . C . Cha,K . H . Lee,Y . T . Lee,T . J . Lee ) 한국화학공학회 1995 화학공학의이론과응용 Vol.1 No.2

PIMS 모형의 응용에 의한 측정투자효과분석 우리나라 주요기업을 중심으로

김동진,안웅환 ( D . J . Kim,W . H . An ) 한국품질경영학회 1990 품질경영학회지 Vol.18 No.2

KMTNet 시험운영 서버 구축

김동진,이충욱,김승리,Kim, D.J.,Lee, C.U.,Kim, S.L. 한국천문학회 2011 天文學論叢 Vol.26 No.4

We constructed two test server systems for KMTNet data management. One is the photometry database server which is optimized for stable operation, and the other is the photometric data process server which is optimized for fast I/O between devices. The performances of servers and data storage units were tested using various methods. Database upload was also checked using five different methods. From tests, we concluded that the most efficient method to upload photometric data processing results to database is the use of three nodes with job scheduler under the InnoDB engine. In this study we provide the test results for prototype servers for KMTNet data management.

중력렌즈 사건 측광 데이터베이스 및 프레임워크 개발

김동진,이충욱,김승리,박병곤,Kim, D.J.,Lee, C.U.,Kim, S.L.,Park, B.G. 한국천문학회 2011 天文學論叢 Vol.26 No.1

We constructed a photometric database system which is optimally designed for microlensing events from KMTNet (Korea Microlensing Telescope Network) observation. We developed a framework software for the convenience of archiving, uploading, searching, and downloading of processed photometric data. From various tests for optimal data archiving engines, we found that the MyISAM storage engine shows the best performance. For the high performance of database system, data types of each field are carefully suggested from various combinations of tests especially to correct round-off errors. The developed framework provides the convenience of access to the database server using query forms via web pages, and displays the light curve of selected target for a quick view.

KMTNet 실시간 자료처리 파이프라인 개발

김동진,이충욱,김승리,박병곤,Kim, D.J.,Lee, C.U.,Kim, S.L.,Park, B.G. 한국천문학회 2013 天文學論叢 Vol.28 No.1

Real-time data reduction pipeline for the Korea Microlensing Telescope Network (KMTNet) was developed by Korea Astronomy and Space Science Institute (KASI). The main goal of the data reduction pipeline is to find variable objects and to record their light variation from the large amount of observation data of about 200 GB per night per site. To achieve the goal we adopt three strategic implementations: precision pointing of telescope using the cross correlation correction for target fields, realtime data transferring using kernel-level file handling and high speed network, and segment data processing architecture using the Sun-Grid engine. We tested performance of the pipeline using simulated data which represent the similar circumstance to CTIO (Cerro Tololo Inter-American Observatory), and we have found that it takes about eight hours for whole processing of one-night data. Therefore we conclude that the pipeline works without problem in real-time if the network speed is high enough, e.g., as high as in CTIO.

B-Site Disordered New Lead-Free Relaxor Ferroelectric Gd(Ni0:5Ti0:5)O3 System

박성균,장민수,김동진,정일경,박철홍,S. S. Park,배종성,J. P. Kim,K. S. Hong,E. D. Jeong,Y. S. Kim 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6

Gd(Ni0:5Ti0:5)O3 solid solutions were synthesized and their structural and physical properties characterized. The X-ray diraction showed that the average structure of the system at room temperature was orthorhombic (Pbnm). The temperature-dependent AC-dielectric constant showed an anomaly (hump) around 500 { 600 K, depending on the frequency. The D-E hysteresis loops were also measured at room temperature and exhibited ferroelectric characteristics. The relaxor ferroelectric behavior of this lead-free centrosymmetric system might be related to the B-site local disorder in the system.