• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.3
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• pp.55-64
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• 2013

In this paper, a new topology which can add a small reactor in series to a condenser-bank type reactive power compensator to limit current is proposed. And also the proposed topology can add or remove a power condenser safely without any addition of inrush-current suppression resistance. The proposed method tests variable resistance of the drain source of a switching device which is controlled by gate voltage in a two-way switch with a diode rectifier and FET switch. In other words, the proposed method is a inrush-current suppression method with the structure of variable resistance. In particular, the proposed method creates smooth current without any resonance in inrush-current as well as is not limited by the time of switch on and off.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.4
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• pp.45-52
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• 2019

The most ordinary form of residential type in Korea is a plate-type apartment, and the common space in these apartment is attracting as an important factor for enhancing social exchanges among neighbors and forming community consciousness. In addition, it provides a sense of psychological security by enabling natural exchanges and communication in contemporary society. It is desirable to plan the flow of space in such a way that private, semi-private, semi-public, and public spaces are linked. Semi-private and semi-public spaces can be defined as common spaces. Semi-private spaces are strongly recognized in the order of unit household entrance, main entrance, elevator, corridor, staircase, playground, bench, trail, walkway and parking lot, exercise space, main/back gate, the ability to gratify is increased sense of belonging, ownership consciousness formation, defensive function. Semi-public space is strongly recognized in the order of playground, bench, exercise space, trail, main entrance, walkway and parking lot, unit household entrance, main/back gate, corridor, staircase, elevator, the ability to gratify is increase of social contact, Secondary activity space function. In addition, the function to gratify in the common space differs according to gender and age group among resident characteristics, and differs according to corridor type, parking lot type and main entrance type. Therefore, differentiated planning of common space is needed in consideration of these differences in the design of common space in future.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.386-393
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• 2017

Field programmable gate arrays (FPGAs) are widely used for verification in chip development. In order to verify the circuit programmed to the FPGA, data must be input to the FPGA. There are many ways to communicate with a chip through a PC and an external board, but the simplest and easiest way is to use a universal asynchronous receiver/transmitter (UART). Most recently, most circuits are designed to be internally connected to the advanced microcontroller bus architecture (AMBA) bus. In other words, to verify the designed circuit easily and simply, data must be transmitted through the AMBA bus through the UART. Also the AMBA bus has been available in various versions since version 4.0 recently. Advanced peripheral bus (APB) is suitable for simple testing. In this paper, we design a circuit for UART-to-APB interface. Circuits designed using Verilog-HDL were implemented in Altera Cyclone FPGAs and were capable of operating at speeds up to 380 MHz.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.427-427
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• 2012

Ferroelectric-gate field effect transistor based memory using a nanowire as a conducting channel offers exceptional advantages over conventional memory devices, like small cell size, low-voltage operation, low power consumption, fast programming/erase speed and non-volatility. We successfully fabricated ferroelectric nonvolatile memory devices using both n-type and p-type Si nanowires coated with organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] via a low temperature fabrication process. The devices performance was carefully characterized in terms of their electrical transport, retention time and endurance test. Our p-type Si NW ferroelectric memory devices exhibit excellent memory characteristics with a large modulation in channel conductance between ON and OFF states exceeding $10^5$; long retention time of over $5{\times}10^4$ sec and high endurance of over 105 programming cycles while maintaining ON/OFF ratio higher $10^3$. This result offers a viable way to fabricate a high performance high-density nonvolatile memory device using a low temperature fabrication processing technique, which makes it suitable for flexible electronics.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3B
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• pp.277-284
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• 2010

To examine how the width of connecting channels, the width of the Kumho lock gate, and the opening/shutting criteria of the Yeongam connecting channel lock gate affect the flood stage of Lake Yeongsan, Lake Yeongam, and Lake Kumho, located in the lower reaches of the Yeongsan River, unsteady flood routing was performed by connecting the three lakes into a single interlinked system. The coupled operation of the three lakes was found to have little effect when the widths of the lock gates and the Yeongam and Kumho connecting channels are set at the current level. The most effective way to lower the water level in Lake Yeongsan was to widen the Yeongam connecting channel, but this caused the water level in Lake Yeongam to rise. To lower the increased water level in Lake Yeongam by utilizing the water storage capacity of Lake Kumho, it was necessary to widen both the Kumho lock gate and the Kumho connecting channel. It was found that the optimum opening/shutting criterion for the Yeongam connecting channel lock gate is approximately EL.(+)0.8 m under the simulated conditions used in this study and the criterion allows of maximal lowering of the water levels in Lake Yeongam and Lake Kumho while maintaining a near-constant water level in Lake Yeongsan.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.768-777
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• 2013

The purpose of this study is to minimize radiation exposure to the workers and public members during CT examination. The objects are seven of the CT rooms in university hospitals and four of the CT rooms in clinics located in Busan and Gyung-nam area. The places of measurement for radiation leakage are 1) 3 m above the ground of shielding wall in the control room 2) particular space in the control room 3) worker's gate in the control room 4) the patient gate. Its values were calculated maximum leakage radiation per week(MLRW). As a result, the worker's gate of M clinic displayed the highest dose. When it was calculated by MLRW in classic method, it showed 1) $5.97{\pm}0.23$, 2) $0.50{\pm}0.02$, 3) $10.00{\pm}0.11$, 4) $2.37{\pm}0.47$ mR/week. All of them did not exceed limit for maximum permissible dose per week(MPDW). However, When MLRW of M clinic was calculated by empirical method, its value displayed $118.31{\pm}17.72$ mR/week.(MPDW>100 mR/week). Radiation leakage influenced in the control room(p<0.05). Therefore, The way of calculating MLRW must be developed and shielding wall in control room is designed 3 m above the ground for reducing dangerous of leakage radiation.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1891-1895
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• 2003

Switch-mode power supplies (SMPS) have become a major source of conducted electromagnetic interference (EMI) which is the combination between differential mode (DM) noise and common mode (CM) noise. This paper presents the conducted EMI reduction approach in flyback switched mode power supply by rerouting for circuit balance to reduce common mode noise. And differential mode noise can be reduce by adding $c_x$ capacitor across the input power line, and passive element to the gate drive of switching device MOSFET to slow down the switching times. This combination of our approach is the effective way to reduce the conducted EMI and it is also a cost effective for product design

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.187-187
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• 2016

진공 압력에 따른 플라즈마 발생의 관계, 전압에 따른 방전 밝기, gas와 방전 전극에 따른 플라즈마 색의 변화 등 실험을 통하여 학부생들에게 진공 시스템과 플라즈마의 이해도를 높이기 위해 Geissler tube cart를 제작하였다. Pump는 TMP station (PFEIFFER Vacuum Hi Cube ECO 80)을 사용하였으며 reducer를 이용하여 CF-4.5"에서 CF-2.75" adaptor를 설치, gate valve를 연결하여 진공도를 조절 할 수 있게 하였으며, 5-way를 이용하여 왼쪽은 gas line, 정면 view port, 상단 geissler tube, 후면 compact full range gauge를 설치하였고, cart 제작 결과를 Fig. 1에 나타내었다. Geissler tube의 수치모델은 Fig. 2에 나타내었다. 저진공(<10-3 Torr) 영역부터 고진공(<10-4 Torr) 영역까지 진공도에 따른 방전을 관찰 할 수 있으며, 표면과 플라즈마 사이의 전위 변화에 따른 쉬스(sheath) 관찰, trans 와 slidacs를 이용하여 전압 조정이 가능하기 때문에 전압에 따른 방전 관찰과 gas line을 통한 gas 주입에 따른 색의 변화를 관찰이 가능하도록 설계하였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.6
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• pp.469-476
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• 2008

Condition based maintenance(CBM) for the preventive diagnosis of important equipments related to safety or accident in power plant is essential by using the suitable methods based on actual power plant conditions. To improve the reliability and accuracy of the measured value at the minute leak situation, and also to monitor continuously internal leak condition of power plant valve, the development of a diagnosis and monitoring technique using multi-measuring method should be performed urgently. This study was conducted to estimate the feasibility of multi-measuring method using three different methods such as acoustic emission(AE) method, thermal image measurement and temperature difference$({\Delta}T)$ measurement that are applicable to internal leak diagnosis for the power plant valve. From the experimental results, it was suggested that the multi-measuring method could be an effective way to precisely diagnose and evaluate internal leak situation of valve.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.406-408
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• 2002

미래의 통신망 구조인 NGN(Next Generation)으로의 이행을 위하여 현재의 방대한 PSTN(Public Switched Telephone Network) 인프라를 한번에 모두 교체할 수 없으므로 신설되는 VoIP(Voice on IP) 기반의 네트워크와 기존의 PSTN이 상호 연동되는 과도기적 과정으로 Pre NGN이 제안되고 있으나 SS7(Signaling System No 7)을 기반으로 하고 있어 아직도 상당수를 차지하는 SD(Space Division) 교환기의 교체는 불가피한 것으로 보인다. 본 논문에서는 SD 교환기를 TD(Time Division) 교환기로 교체하기보다는 미래의 NGN을 지향하며 소요비용의 절감을 위하여 Soft Switch기능을 보유한 AGW(Access Gate Way)로의 교체를 제안하고 현재의 망에서 필요한 기능 및 조건을 제시 하였다.