• Journal of Ocean Engineering and Technology
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• v.21 no.5
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• pp.61-67
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• 2007

As part of the government's fishery resource creation policy, fishing ground creation projects have been undertaken in Korea's major seashore fishing spots since the 1970s, where artificial reefs constructed using new materials that make up for the weakness of concrete reefs have been used. In this study, the stability of these artificial reefs when acted upon by external forces, their ability to attract and gather fish, and their economic feasibility were examined. For this purpose, an experimental artificial steel reef was constructed and was installed in an area of the sea. Then the corrosion of the experimental material attached to it was investigated. The efficiency of the artificial steel reef was then verified by examining its functionality, removal, and burying, as well as the speed of insertion of living things into its structure and its ability to attract and gather fish.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.9-10
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• 2015

본 논문에서는 전자기 유도의 동일 원리를 기반으로 하는 무선전력전송(WPT, Wireless Power Transfer)와 인덕션 히팅(IH, Induction Heating) 기술을 융합하기 위한 고효율 중전력(100W~2.4kW) 시스템을 제안한다. 제안하는 시스템은 고효율 PFC 컨버터와 무선전력 전송 및 IH렌지 겸용 고주파 인버터로 구성된다. PFC 컨버터는 단위역률과 동시에 고효율을 달성할 수 있는 Bridgeless PFC로 구성하였으며 인버터는 중전력 및 넓은 출력 범위를 지니는 Full-Bridge 인버터로 구성하였다. 무선전력전송과 IH렌지를 위한 송/수신부 코일 구조를 개발하였으며 최대 전력 전송을 위한 공진회로를 개발하였다. 중전력에서 고효율 및 시스템 안정성을 기반으로 하여 국내외 규제를 만족하는 시제품을 제작하여 상용화 가능성에 대한 확인을 목표로 한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.524-532
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• 2012

In this paper, we used MOM-based BIM(Born Iterative Method) algorithm to implement the inverse scattering for the detection of cancer. We adopted two-dimensional breast structure, integral equations and two-dimensional Green's function is solved with MoM(Method of Moment) to analyzing electromagnetic scattering phenomena. In addition, verifying the calculation of developed inverse scattering algorithm and analyzing medical applicability and limitations of the algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.540-544
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• 2017

In this study, we analyzed the effects of TID(Total Ionizing Dese) and TREE(Transient Radiation Effects on Electronics) on nMOSFET and pMOSFET fabricated by 0.18um CMOS process. The size of nMOSFET and pMOSFET is 100um/1um(W/L). The TID test was conducted up to 1 Mrad(Si) with a gamma-ray(Co-60). During the TID test, the nMOSFET generated leakage current proportional to the applied dose, but that of the pMOSFET was remained in a steady state. The TREE test was conducted at TEST LINAC in Pohang Accelerator Laboratory with a maximum dose-rate of $3.16{\times}10^8rad(si)/s$. In that test nMOESFET generated a large amount of photocurrent at a maximum of $3.16{\times}10^8rad(si)/s$. Whereas, pMOSFETs showed high TREE immunity with a little amount of photocurrent at the same dose rate. Based on the results of this experiment, we will progress the research of the radiation hardening for CMOS unit devices.

• Korean Journal of Materials Research
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• v.10 no.12
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• pp.799-806
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• 2000

Cu$_{6}$Sn$_{5}$-dispersed 63Sn-37Pb solder bumps of 760$\mu\textrm{m}$ size were fabricated on Au(0.5$\mu\textrm{m}$)/Ni(5$\mu\textrm{m}$)/Cu(27$\pm$20$\mu\textrm{m}$) BGA substrates by screen printing process, and their shear strength were characterized with variations of dwell time at reflow peak temperature and aging time at 15$0^{\circ}C$ . With dwell time of 30 seconds at reflow peak temperature, the solder bumps with Cu$_{6}$Sn$_{5}$ dispersion exhibited higher shear strength than the value of the 63Sn-37Pb solder bump. With increasing the dwell time longer than 60 seconds, however the shear strength of the Cu$_{6}$Sn$_{5}$-dispersed solder bumps became lower than that the 63Sn-37Pb solder bumps. The failure surface of the solder bumps could be divided into two legions of slow crack propagation and critical crack propagation. The shear strength of the solder bumps was inversely proportional to the slow crack propagation length, regardless of the dwell time at peak temperature, aging time at 150 $^{\circ}C$ and the volume fraction of Cu$_{6}$Sn$_{5}$ dispersion.> 5/ dispersion.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.490-494
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• 2014

In this paper, a design of high-speed power-off circuit and analysis. The incidence of high-dose transient radiation into the silicon-based semiconductor element induces the photocurrent due to the creation of electron-hole pairs, which causes the upset phenomenon of active elements or triggers the parasitic thyristor in the element, resulting in latch-up. High speed power-off circuit was designed to prevent burn-out of electronic device caused by Latch-up. The proposed high speed power-off circuit was configured with the darlington transistor and photocoupler so that the power was interrupted and recovered without the need for an additional circuit, in order to improve the existing problem of SCR off when using the thyristor. The discharge speed of the high speed power interruption circuit was measured to be 19 ${\mu}s$ with 10 ${\mu}F$ and 500 ${\Omega}$ load, which was 98% shorter than before (12.8 ms).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.214-214
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• 2009

While critical properties of BSCCO wires rely considerably on grid direction upon BSCCO and have very complicated mechanism of generating a superconducting phase, making it difficult to improve properties of wires, YBCO thin-film wires which can be formed in a superconducting phase upon metal board through vapor deposition processing can get excellent direction and reduce manufacturing costs with more flexibility in improving critical properties; thus, they will be suitable for instrument application in the future. Contrary to BSCCO wires for which thick silver alloy covering materials should inevitably be used, moreover, YBCO thin-film wires have an advantage of making thickness and quality of covering materials different by usage. Such a property can be an important element to widen application of wires by presenting possibility of using thin-film wires as superconducting material for fault current limiter as well as for high power current application. In this study we intend to prepare YBCO thin-film wires with different stabilizer layers to analyze current application and current restriction properties by stabilizer layers on the basis of detailed researches on changes in current classification properties below critical value.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.1
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• pp.51-56
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• 2004

이번 연구의 목적은 순수 타이타늄의 표면을 양극산화법으로 표면처리하여 표면의 특성변화를 연구하고, 이에 따른 세포부착 특성의 차이를 연구하는 것이다. 원반 모양의 타이타늄을 전해질용액에서 300V - 550V의 전압을 주어 양극산화 하고 표면특성을 관찰한 결과, 전압이 높아짐에 따라 표면의 분화구 크기가 커지는 양상을 보였으며 아울러 표면 거칠기도 증가되었다. 세포 부착 실험결과 전압이 증가함에 따라 세포부착 및 증식세포수는 감소하였다. 300V 이상의 양극산화 전압은 표면의 거칠기는 증가시키지만 세포증식은 오히려 억제되는 것이 관찰되었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.797-805
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• 2009

In this paper, we developed MoM(Moment of Method) forward solver to implement the inverse scattering by using BIM(Born Iterative Method) for the detection of cancer in human body Especially, we adopted two-dimensional breast structure to analyze electromagnetic scattered phenomena. For the two-dimensional scattering structure, the integral equations is solved with MoM employing two-dimensional Green's function. Also, calculated results are compared with the measured results obtained from breast cancer detecting equipment.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.3
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• pp.294-300
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• 2004

The present experimental study was designed to address two issues. The first was to investigate whether oxidation voltage of titanium implants influenced bone tissue responses after an in vivo implantation. The second aim was to investigate secondary stability change after 1 to 3months period. Screw-shaped implants with a wide range of oxide properties were prepared by electrochemical oxidation methods, where the oxide thickness varied in the range of $3-15{\mu}m$. The micro structure revealed pore sizes of $1-3{\mu}m$, the crystal structures of the titanium oxide were amorphous, anatase and a mixture of anatase and rutile type. Bone tissue responses were evaluated by resonance frequency measurements that were undertaken 1 to 3months after insertion in the rabbit tibia. It was concluded that no statistical difference of RFA values was found between the groups, RFA gains after Imonth and 3months were calculated.