• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.663-668
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• 1997

한국형 차세대 원자로(KNGR)는 안전주입계통에 Advanced Design features를 채택하고 있는데, 그 중의 하나가 안전주입의 주입구를 Downcomer Annulus의 상부에 위치시킨 Direct Vessel Injection(DVI)으로서 영광 및 울진 3&4호기의 Cold Leg Injection(CLI)과는 다른 설계 개념이다. 본 논문에서는 DVI가 채택된 KNGR에 대하여 기존의 C-E형 발전소 해석에 적용한 C-E Evaluation Model(EM)을 사용하여 대형파단 냉각재상실사고를 해석해 보고자 하였다. 먼저 DVI의 Modeling은 KNOGR의 참조 발전소라 할 수 있는 System80+에서 Modeling한 것과 같이 CLI 해석에 사용한 Nodalization Scheme 중 Cold Leg Node에 연결된 SIT 만을 Downcomer Annulus Node에 연결하는 방법을 사용하여 DVI 해석을 수행하였다. 아울러 기존의 안전주입 형태인 CLI에 대한 해석을 KNGR에 대해 병행하여 수행함으로써 DVI와 CLI의 ECCS performance를 비교하고 CLI 대비 DVI의 특성을 알아보았다. 또한 DVI의 해석에 있어서 SIT와 Cold Leg이 함께 연결되는 Downcomer Annulus Node를 상하 2개로 분리하여 SIT와 Cold Leg 각각에 연결시킴으로써 DVI 주입구의 위치에 대한 보다 정확한 Modeling을 시도하였다. 그 결과 DVI 주입구의 높이를 고려한 경우가 DVI의 일반적 물리 현상에 근접하게 계산되는 것으로 판단되나 현재로서는 특별한 검증 수단이 없으므로 향후 Licensing 해석 수행에 앞서 방법론을 포함한 이에 대한 보다 심도 있는 검토가 필요할 것으로 판단된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.782-789
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• 2018

Multi-Function Display (MFD) of Korean Utility Helicopter (KUH) displays image information(navigation, flight, topographical and maintenance information) delivered from Mission Computer (MC) during flight operation. The abnormal display of MFD such as flickering phenomenon was identified in the system development. It was solved by improving the shielding performance of the DVI cable and changing the DVI cable installation path at the first mass production. However, it was occurred again when the aircraft was operated for one or two years after delivery. It was also identified in the evaluation process of the derivative helicopters. Therefore, a comprehensive review of the aircraft system level has been performed to solve the problem of MFD malfunction at first and then a design improvement plan was derived by improving the DVI cable. In this paper, the causes of MFD anomalies are analyzed and also the process of design improvement are summarized. The validity of the improvement has been verified through the DVI cable assembly comparison test, SIL/ground/flight test.

• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.727-734
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• 2012

A new advanced safety feature of DVI+ (Direct Vessel Injection Plus) for the APR+ (Advanced Power Reactor Plus), to mitigate the ECC (Emergency Core Cooling) bypass fraction and to prevent switching an ECC outlet to a break flow inlet during a DVI line break, is presented for an advanced DVI system. In the current DVI system, the ECC water injected into the downcomer is easily shifted to the broken cold leg by a high steam cross flow which comes from the intact cold legs during the late reflood phase of a LBLOCA (Large Break Loss Of Coolant Accident)For the new DVI+ system, an ECBD (Emergency Core Barrel Duct) is installed on the outside of a core barrel cylinder. The ECBD has a gap (From the core barrel wall to the ECBD inner wall to the radial direction) of 3/25~7/25 of the downcomer annulus gap. The DVI nozzle and the ECBD are only connected by the ECC water jet, which is called a hydrodynamic water bridge, during the ECC injection period. Otherwise these two components are disconnected from each other without any pipes inside the downcomer. The ECBD is an ECC downward isolation flow sub-channel which protects the ECC water from the high speed steam crossflow in the downcomer annulus during a LOCA event. The injected ECC water flows downward into the lower downcomer through the ECBD without a strong entrainment to a steam cross flow. The outer downcomer annulus of the ECBD is the major steam flow zone coming from the intact cold leg during a LBLOCA. During a DVI line break, the separated DVI nozzle and ECBD have the effect of preventing the level of the cooling water from being lowered in the downcomer due to an inlet-outlet reverse phenomenon at the lowest position of the outlet of the ECBD.

• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.719-726
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• 2012

The object of this work is the validation and assessment of the TRACE v5.0 code using the scaled test ATLAS1 facility in the context of a DVI2 line break. In particular, the experiment selected models the 50%, 6-inch break of a DVI line. The same experiment was also adopted as a reference test in the ISP-503. The ISP-50 was proposed to, and accepted by, the OECD/NEA/CSNI due to its technical importance in the development of a best-estimate of safety analysis methodology for DVI line break accidents. In particular, the behavior of the two-phase flow in the upper annulus downcomer was expected to be complicated. What resulted was the need for relevant models to be implemented into safety analysis codes, in order to predict these thermal hydraulic phenomena correctly.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.1
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• pp.72-75
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• 2016

In this paper, we proposes a internal antenna for wireless DVI dongle device using the folded monopole structure. The proposed antenna uses a basic structure of spiral and monopole. The antenna optimized for parameters length, gap, width, and rectangle of folded monopole antenna using the spiral structure. To confirm the characteristics of the antenna parameters, HFSS from ANSYS Inc. was used for the analysis. We used an FR4 dielectric substrate with a dielectric constant of 4.4. The DVI dongle size of the proposed antenna is $50{\times}40{\times}1.6mm$, and the size of the antenna area is $10{\times}40mm$. There is a value of return loss less then -10dB in 2.4GHz and 5.8GHz, band and the maximum antenna gain is -4.13dBi. The utilization possibility of the wireless DVI Dongle antenna have a folded monopole with spiral shape could be confirmed according to compare and analyze the simulation and measurement data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1330-1335
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• 2013

In recent years, the need to simultaneously transmit a variety of signals, such as DVI(Digital Visual Interface), audio, video, USB(Universal Serial Bus), LAN from the computer is required. So the cable complexity and scalability issues have been raised. In this paper, this signal can be distributed using a single USB cable, computer, video, audio, USB, LAN, one USB multi-signal transmission system was designed and implemented. USB multi-signal transmission was implemented in order to convert a single DVI, audio, and multiple USB, LAN, USB signal converter modules. This USB DVI port supports up to 1920 * 1080 resolution. USB multi-signal transmission system by sending multiple signals into a single cable installation costs of the various cable and using the replication feature of the screen, will provide schools and institutes, etc., providing the convenience of the river, and the scalability of computer peripheral ports.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.193-193
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• 2002

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.623-625
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• 2013

This signal can be distributed using a single USB cable, computer, video, audio, USB, LAN, one USB multi-signal transmission system was designed and implemented. USB multi-signal transmission was implemented in order to convert a single DVI, audio, and multiple USB, LAN, USB signal converter modules. This USB DVI port supports up to 1920 * 1090 resolution. USB multi-signal transmission system by sending multiple signals into a single cable installation costs of the various cable and using the replication feature of the screen, will provide schools and institutes, etc., providing the convenience of the river, and the scalability of computer peripheral ports.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.283-288
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• 1996

Direct safety injection into the reactor vessel downcomer annulus(DVI) is a fundamental feature of the KNGR(Korean Next Generation Reactor) four-train safety injection system. The numerical analysis of thermal mixing of ECC(Emergency Core Cooling) water through DVI with the water in the RVDC(Reactor Vessel Downcomer) annulus has been performed, in order to study the impact of nozzle location on the pressurized thermal shock and safety analysis. The results of this study show that the thermal mixing due to the natural circulation induced by the limiting accident conditions is sufficient to prevent temperature in the RVDC from dropping to the level of concern for PTS. When the DVI nozzle is located right above the cold leg, the temperature distribution at the outlet of flow field is most uniform. The tool used for numerical analysis is CFDS-FLOW3D.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.457-462
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• 1997

현재 국내외 대부분 원자력발전소(이하 원전)의 안전주입방식은 저온관 주입방식을 채택하고 있으며, 안전주입시 노심의 온도와 압력분포가 주요 관심 대상이었다. 하지만 향후 개발될 원전의 안전주입방식은 저온관주입이 아닌 안전주입의 신뢰성을 한단계 높인 원자로용기 직접주입방식인 DVI(Direct Vessel Injection)방식을 채택하고 있는 추세인데, 이 경우 관심분야는 원자로용기 dowmcomer지역까지 확대된다. 즉 저온의 안전주입수가 고온 고압의 원자로용기 downcomer지역으로 직접 주입됨으로 인해 이 지역의 유체유동과 혼합상태 및 온도분포가 주요관심 대상이 되며 이는 원자로용기의 PTS(Pressurized Thermal Shock)해석에 연결된다. 본 연구에서는 LOCA 사고시 DVI방식을 적응한 안전주입수 유입에 의한 원자로용기 downcomer지역의 유제유동과 유체혼합상태 및 온도분포를 열유체 해석 code인 FLUENT를 이용하여 해석하였다. 해석결과에 의하면 사고시 DVI에 의해 유입되는 약55℉인 저온 안전주입수는 유입과 동시에 넓은 지역으로 퍼지면서 dowmcomer지역의 고온 원자로냉각재와 적절히 혼합되어 하향유로를 따라 흐르며 PTS의 발생 원인인 국부적 유체비혼합 현상이나 온도 급하강현상은 발생하지 않는 것으로 나타났다.