전기 절연용 EPDM Compouynds

김진국,김인환,황성혁 韓國고무學會 1999 엘라스토머 및 콤포지트 Vol.34 No.5

Non-ceramic composite insulator has been interested in the power industry because of its good characteristics in mechanical properties, mass product and design availability. Also it is lighter, and less unexplosive, compared to a ceramic insulator. Especially, EPDM rubber composite insulator can be used for long-term in contaminated environments because of its hydrophobicity. This paper showed the rheological properties, the electrical properties, and contact angles to check the hydrophobicity and the recoverability of the EPDM compounds. Also, we investigated surface morphology of the compound by SEM.

12Cr-1MoVW 강의 열처리에 따른 탄화물의 화학조성 변화

김성호,유우석,국일현,송병준 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.3

Dissolution and precipitation reactions of the carbides occurred during heat treatment of 12Cr-1MoVW steel were studied. Transmission electron microscopy and energy dispersive X-ray spectroscopy were used to determine types and chemical compositions of precipitates. The dissolution of the M_(23)C_6 carbide took place during normalizing treatment through the diffusion of chromium atoms. Upon tempering, types of M₃C and M_(23)C_6 precipitates were formed depending on the tempering conditions. The chemical composition of M₃C formed at low tempering temperature is similar to the base material, but the enrichment of chromium and depletion of iron in M₃C occur with increasing the tempering time and temperature. On the other hand chromium content decreases and iron content increases in M_(23)C_6 carbide with increasing the tempering temperature. M_(23)C_6 forms at the δ-ferrite/tempered martensite interface regardless of tempering temperatures. The chromium content of M_(23)C_6 formed at low temperature is low, but chromium content increases and iron content decrease in M_(23)C_6 with increasing the tempering time and temperature.

원자력용 HT9 강과 HT9M 강의 미세조직과 기계적 특성 변화

김성호,박순동,류우석,국일현,송병준 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.12

Microstructure and mechanical properties of HT9 and HT9M steels for liquid metal reactor(LMR) core materials have been investigated. The tempering temperature at which cell structure was formed by rearrangement of dislocations was same in two steels. More carbides were precipitated in HT9 steel due to high carbon content and precipitation of carbides was delayed in HT9M steel. Thus the decrease of hardness with tempering temperature in HT9M steel was lower than that of HT9 steel. The yield strength was decreased, the fine prior austenite grain was formed, and the formation of δ-ferrite was restricted in HT9M steel by decreasing the Cr and carbon content and increasing the Nb content. Thus the impact property of HT9M steel was improved.

외국문 요약

Kuk,Min-Ho 동양사회사상학회 2002 사회사상과 문화 Vol.5 No.-

6G-LEGO: A framework for 6G network slices

Slawomir Kukliński,Lechosław Tomaszews,Robert Kołakowski,Prosper Chemouil 한국통신학회 2021 Journal of communications and networks Vol.23 No.6

Network slicing is a relatively recent paradigmthat has become a subject of intensive research. Most of theexisting approaches follow the ETSI NFV MANO model withsome extensions related to multi-domain slicing, slice selection,etc. The framework is a part of the standalone variant ofthe 5G network standardized by 3GPP. However, the currentimplementation of network slicing in 5G has several limitations,especially regarding management and orchestration: The isolationof slice management is not appropriately addressed, the slicetenant management capabilities are limited, and the managementand orchestration centralization raises serious scalability andreliability issues. Moreover, the slice-level operations are notwell-separated from other processes due to a lack of properseparation of concerns. As a result, the overall network slicingarchitecture has complex interactions with many components ofthe 5G network. In this paper, we describe a new framework thatuses an approach to sustain self-managed and self-orchestratedslices. To that end, we propose a modular architecture in whichslices have embedded (in-slice) management and orchestrationsupport, and multi-domain slices rely on multiple slice-agnosticorchestrators. The framework enables the composition of newslices as a combination of single domain-slices in a relativelyeasy, technology-independent manner.

Detecting outdoor coexistence as a proxy of infectious contact through magnetometer traces

Kuk, S.,Jeon, Y.,Kim, H. IET 2017 Electronics letters Vol.53 No.19

<P>If epidemic contact detection using smartphones can be done with sufficiently fine resolution in outdoor environments, so that those who were within the transmissible distance from an infected person may be identified as a potential infected is explored. The smartphone GPS, at least in its current capacity, is not useful to determine the coexistence within a couple meters that is critical for infectious disease transmission is shown. As an alternative, the usage of magnetometers is proposed, which enables the coexistence determination with the required precision, with much less energy consumption than GPS, and with an added bonus of indoor usability.</P>

Numerical Study on Onaf Type Radiator for Power Transformer Effect of Fan Arrangement

Kuk-kyeom Kim,Yong Kweon Suh,Sangmo Kang 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.10

Due to the trend of miniaturization and high-efficiency requirement, the life and reliability of power transformers depend on the amount of heat generation per unit volume and the quality of insulation. Excessive heat generation in the winding degrades the insulation. These problems can be solved by enhancing the cooling performance of the radiator connected to the transformer. In this study, by using a commercial software CFX, ANSYS Inc., we have found that the positions of fans affect the forced-convection in ONAF (Oil Natural Air Forced) flow type transformer. In the simulation, radiator fans of simple shape were used. To improve the reliability of numerical solutions, combined grids consisting of tetrahedral and hexagonal mesh were applied. To implement this fan, at the inlet the standard design flow-rate was applied for each fan taken to be the same regardless of its position. The numerical results of the flow analysis show that modified arrangement of fans can yield stronger forced-convection effect than the original arrangement, leading to a better cooling performance.

Development of Confocal Imaging System for Wafer Inspection

Kuk-Won Ko,Cong Dai Nguyen,Kyung Cheol Koh 한국산학기술학회 2010 한국산학기술학회 학술대회 Vol.- No.-

Confocal Imaging System is an essential machine for a wide range of inspection wafer. For concurrent and fast acquiring the image data of four channels, the new image acquisition system used the protocol of camera-link standard with the full mode of configuration in interconnection with a frame grabber integrated in a computer , which is popularly used for many cameras, so the programming environment of image processing is optional such as Visual C++, Matlab. In addition, many conventional methods were coordinately used for contribution to build the high quality of images for precise processing analog signals of PhotoMutiplier Tubes(PMTs), accurate control of scanning device, sensitivity of PMTs, and laser source. The prototype of new image acquisition system, could meet the goal of development, it is used in LSCM for high content screening to investigation the processes of elements of living specimens at the same time by simultaneous grab image data on 4 PMTs channels.

Car-level co-location detection on trains for infectious disease epidemic monitoring

Kuk, S.,Park, Y.,Han, S.,Kim, H. IET 2017 Electronics letters Vol.53 No.1

<P>On the brink of an infectious disease epidemic, contact tracing must be precisely focused on those most likely to have made contacts with the confirmed cases. This explores if the tracing can be made fine-grained enough for train riders, so that those sharing the same car are identified as higher priority contact tracing targets, over those on different cars.</P>

Geometric Modeling and Radioactive Modeling of RVI Using MAVRIC Code

Kuk-hyun Son,Chang-Lak Kim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

In 2017, the permanent shutdown of Kori Unit 1 was decided, marking the initiation of preparations for the decontamination and decommissioning of Kori Unit 1. The dismantling of radiologically contaminated equipment and concrete structures such as the Reactor Vessel (RV), Reactor Vessel Internals (RVI), and the Bio shield is crucial in the nuclear decommissioning process. These components became radiologically contaminated due to nuclear fission reactions occurring in the reactor during its operational period. The RVI dismantling at Spain’s Jose Cabrera Nuclear Power Plant involved the use of mechanical saws and disk cutters to divide it into approximately 430 pieces, taking 16 months to complete. Germany’s Stade Nuclear Power Plant employed mechanical circular saws to segment their RVI into about 170 pieces, which took 30 months to accomplish. Meanwhile, the RVI at Germany’s Wurgassen Nuclear Power Plant was subdivided into approximately 1,200 pieces using a combination of mechanical saws and abrasive water jets, requiring 61 months for completion. Due to the radioactivity in Kori Unit 1’s Reactor Vessel (RV) and Reactor Vessel Internals (RVI), remote-controlled systems were developed for cutting within the cavity to reduce radiation exposure. Specialized equipment was developed for underwater cutting operations. This paper focuses on modeling related to RVI operations using the MAVRIC code. The upper and lower parts of the RVI are classified as low-level radioactive waste, while the sides of the RVI that come into contact with fuel are classified as intermediate-level radioactive waste. Therefore, the modeling presented in this paper only considers the RVI sides since the upper and lower parts have a minimal impact on radiation exposure. Accurate calculations were performed through geometric modeling and radiation dose modeling. These research findings are anticipated to contribute to enhancing the efficiency and safety of nuclear reactor decommissioning operations