• Journal of the Korean Magnetics Society
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• v.14 no.1
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• pp.7-12
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• 2004

The annealing-temperature dependence of magnetic properties in compressed powder cores being composed of ball-milled F $e_{73.5}$C $u_1$N $b_3$S $i_{15.5}$ $B_{7}$ alloy powders (size 250∼850${\mu}{\textrm}{m}$) and 5 wt% of ceramic insulators has been investigated. When annealed at 5$50^{\circ}C$ for 1 h and so transformed to $\alpha$-Fe phase nanocrystalline structure with the grain size of 11 nm (electrical resistivity : 110 $\mu$Ω$.$cm), the highest effective permeability of 125 and quality factor of 53 were obtained, and the permeability persisted up to about 500 KHz. Further the core loss measured at the frequency of 50 KHz and the induction amplitude of 0.1 T was very low (230 mW/㎤). However the dc bias characteristics was not satisfactory as compared to that of conventional powder core materials(MPP, Sendust etc.). The inferior dc bias property of F $e_{73.5}$C $u_1$N $b_3$S $i_{15.5}$ $B_{7}$ alloy powder cores was attributed to the fact that the size of powder was too large for obtaining the same permeability with that of conventional materials.

• Journal of the Korean Institute of Gas
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• v.9 no.1 s.26
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• pp.1-8
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• 2005

In this study, the FE analysis has been presented for the leakage safety of $9\%$ nickel type LNG storage tank based on the thermal resistance effects between insulation panels, comer protection and prestressed concrete(PC) structures. The FEM calculated results show that the leakage safety of fiber glass blanket, perlite powder and cellular glass insulators does not guarantee any more due to a strength failure of the insulation structure. But the corner protection and PC structure of outer tank may delay or sustain the leaked LNG of 10 days even though the inner tank and insulation structure are simultaneously failed. This means that $9\%$ nickel steel type LNG storage tank may be safe because of a high strength of the corner protection and outer tank structures.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.219-226
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• 2013

Organic semiconductor-based soft electronics has potential advantages for next-generation electronics and displays, which request mobile convenience, flexibility, light-weight, large area, etc. Organic field-effect transistors (OFET) are core elements for soft electronic applications, such as e-paper, e-book, smart card, RFID tag, photovoltaics, portable computer, sensor, memory, etc. An optimal multi-layered structure of organic semiconductor, insulator, and electrodes is required to achieve high-performance OFET. Since most organic semiconductors are self-assembled structures with weak van der Waals forces during film formation, their crystalline structures and orientation are significantly affected by environmental conditions, specifically, substrate properties of surface energy and roughness, changing the corresponding OFET. Organo-compatible insulators and surface treatments can induce the crystal structure and orientation of solution- or vacuum-processable organic semiconductors preferential to the charge-carrier transport in OFET.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.319-322
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• 2003

To match the charge induced by the insulators $CeO_2$ with the remanent polarization of ferro electric SBT thin films, areas of Pt/SBT/Pt (MFM) and those of $Pt/CeO_2/Si$ (MIS) capacitors were ind ependently designed. The area $S_M$ of MIS capacitors to the area $S_F$ of MFM capacitors were varied from 1 to 10, 15, and 20. Top electrode Pt and SBT layers were etched with for various area ratios of $S_M\;/\;S_F$. Bottom electrode Pt and $CeO_2$ layers were respectively deposited by do and rf sputtering in-situ process. SBT thin film were prepared by the metal orgnic decomposition (MOD) technique. $Pt(100nm)/SBT(350nm)/Pt(300nm)/CeO_2(40nm)/p-Si$ (MFMIS) gate structures have been fabricated with the various $S_M\;/\;S_F$ ratios using inductively coupled plasma reactive ion etching (ICP-RIE). The leakage current density of MFMIS gate structures were improved to $6.32{\times}10^{-7}\;A/cm^2$ at the applied gate voltage of 10 V. It is shown that in the memory window increase with the area ratio $S_M\;/\;S_F$ of the MFMIS structures and a larger memory window of 3 V can be obtained for a voltage sweep of ${\pm}9\;V$ for MFMIS structures with an area ratio $S_M\;/\;S_F\;=\;6$ than that of 0.9 V of MFS at the same applied voltage. The maximum memory windows of MFMIS structures were 2.28 V, 3.35 V, and 3.7 V with the are a ratios 1, 2, and 6 at the applied gate voltage of 11 V, respectively. It is concluded that ferroelectric gate capacitors of MFMIS are good candidates for nondestructive readout-nonvolatile memories.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.24-24
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• 1998

반도체장비를 포함하는 초고진공장비의 園훌化가 급속히 그리고 절실히 요구되고 있는 것이 현실정이다. 當面해서 실현할 국산진공장비의 대상은 廣範圍하다. 즉, 각종 진공 pump ( (rotary, dry, diffusion, cryo, ion, turbo melecular pump), 진공 chamber, 진공 line, gate valve 를 위 시 한 진공 V머ve, flange, gasket, fl않d야lU, mainpulater 퉁 진공 部品이 다. 진공계 의 핵심 은 適切하고 優良한 진공재료의 선태파 사용이다. 진공장비는 사용자가 원하는 진공도를 원하 는 시간 동안 륨空度를 유지해 주어야 한다. 진공재료 선태의 기준사항은:(1) 기체의 透過성 (2) 薰했훌 (3) 혔體放出특성 - -outgassing과 degassing- (4) 機械的 량훌度 (5) 온도 의존성 (6) 化學톡성 (7) 加I성 및 鎔接 성 (8) 課電특성 (9) 磁氣특성 (10) 高速함子 및 放射線 특성 (11) 經濟성 및 調達생 둥이 다. 우량한 초고진공계재료는 풍부하게 개발되어 왔고, 또 新材料들이 개발되고 있다. 여기에서는 주로 초고진공 내지는 극고진공계의 構造材料, 機能材料, 部品材料 일반파 몇가지 신재료의 특 성에 관해서 記述한다. M Mild SteeHSAE, 1112, 1010, 1020, 1022, etc)., S Stainless SteeHAlSI, 304, 304L, 310, 316, 321, 347): 구조재료, chamber, fl하1ges A Aluminum과 Alloys (1060, 1100, 2014, 4032, 6(뻐1): 구조재료, chamber, flanges, gaskets A AI, Al 떠loy는 SS에 代替하는 역 할올 시 작하고 있다. C Copper, Copper Alloys(C11$\alpha$)0, C26800, C61400, Cl7200): 내장인자, gasket, cryopanel, tubing T Titanium, Ziriconium, Haf띠um 및 Alloys: 특히 Ti은 10n pump 용 getter material 이 외 에 U UHV,XHV용 chamber계로서 관심올 끌고 있다. N Nickel, Nickel Alloys (200, 204, 211, monel, nichrome): 부식 방지 , 전자장치 , 자기 장치 귀 금속(Ag, Au, Pt, Pd, Rh, Ir, Os, Ru): 보조부품, gasket, filament, coating, thermocouple, 접 합부위 T TiC, SiC, zrC, HfC, TaC 둥의 탄화물과, BN, TiN, AlN 동의 질화물, 붕화물이 둥장하고 었 다. 유리: Soda Lime, Borosilicate, Potash Soda Lead: View Port, Chamber envelope C Ceramics: AlZ03, BeO, MgO, zrOz, SiOz, MgOzSiOz, 3Alz032SiOz, Z$textsc{k}$hSiOz S상N4: e electrical, thermal insulators, crucibles, boats, single crystals, sepctr려 windows 저자는 최근 저자들이 발견한 Zr-Ti-Cu-Ni-Be amorphous alloys coated cham뾰r가 radiation p proof로 이용될 수 있는 사실을 점검하고 었다 .. Z.Y. Hua 들은 Cs3Sb를 새로운 photocathode 재료로 보고하고 있다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.245-250
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• 2017

From the instant of installation and operation, power cables start deteriorating. Cable systems can be maintained not only by monitoring the insulation status of the insulation layer and oversheath, but also the insulation status of the terminal and junction in high-voltage power cables. When the cable system (the cable itself and cable junctions combined) deteriorates, fire accidents happen due to dielectric breakdowns. We have invented a device to monitor the deteriorating status of cables, and installed it at Korea Western Power Co. Ltd. located in Taean, Chungcheongnam-do Province. In this paper, we present the results obtained using our device, through analysing and calculating the standard deviation of leakage current from cable insulators attached to the cables. When the standard deviation of analysed leakage current falls below a critical value, a cable system is deemed to be operating safely. But when the standard deviation of analysed leakage current is larger than the critical value, the insulation status of the terminal and junction in the cable system is considered to have seriously deteriorated. The terminal and junction in the relevant system should then be replaced preemptively in order to prevent blackout accidents of cables caused by the suspension of power supply.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.121-141
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• 2017

The thermal analysis of an underground power conduit for electrical cables is essential to determine their current capacity with an increasing number of demands for high-voltage underground cables. The temperature rises around a buried cable, caused by excessive heat dissipation, may increase considerably the thermal resistance of the cables, leading to the danger of "thermal runaway" or damaging to insulators. It is a key design factor to develop the mechanism on thermal behavior of backfilling materials for underground power conduits. With a full-scale field test, a numerical model was developed to estimate the temperature change as well as the thermal resistance existing between an underground power conduit and backfill materials. In comparison with the field test, the numerical model for analyzing thermal behavior depending on density, moisture content and soil constituents is verified by the one-year-long field measurement.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.14-15
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• 2010

Recently there has been growing interest in topological insulators or the quantum spin Hall (QSH) phase, which are insulating materials with bulk band gaps but have metallic edge states that are formed topologically and robust against any non-magnetic impurity [1]. In a three-dimensional material, the two-dimensional surface states correspond to the edge states (topological metal) and their intriguing nature in terms of electronic and spin structures have been experimentally observed in bulk Bi1-xSbx single crystals [2,3,4]. However, if we want to know the transport properties of these topological metals, high purity samples as well as very low temperature will be needed because of the contribution from bulk states or impurity effects. In a recent report, it was also shown that an intriguing coupling between the surface and bulk states will occur [5]. A simple solution to this bothersome problem is to prepare a topological metal on an ultrathin film, in which the surface-to-bulk ratio is drastically increased. Therefore in the present study, we have investigated if there is a method to make an ultrathin Bi1-xSbx film on a semiconductor substrate. From reflection high-energy electron diffraction observation, it was found that single crystal Bi1-xSbx films (0${\sim}30\;{\AA}A$ can be prepared on Si(111)-$7{\times}7$. The transport properties of such films were characterized by in situ monolithic micro four-point probes [6]. The temperature dependence of the resistivity for the x=0.1 samples was insulating when the film thickness was $240\;{\AA}A$. However, it became metallic as the thickness was reduced down to $30\;{\AA}A$, indicating surface-state dominant electrical conduction. Figure 1 shows the Fermi surface of $40\;{\AA}A$ thick Bi0.92Sb0.08 (a) and Bi0.84Sb0.16 (b) films mapped by angle-resolved photoemission spectroscopy. The basic features of the electronic structure of these surface states were shown to be the same as those found on bulk surfaces, meaning that topological metals can be prepared at the surface of an ultrathin film. The details will be given in the presentation.

• Food Engineering Progress
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• v.23 no.4
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• pp.270-277
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• 2019

Commercial direct refrigerators have good energy efficiency, but are difficult to use for supercooled storage due to their large temperature deviation. Placing insulators and conductors inside the refrigerator could reduce these temperature deviations to within 0.3 degrees, allowing for the supercooled storage. The supercooled storage of salted Chinese cabbages during ten weeks was progressed to compare the other low temperature storages. The nucleation temperatures of salted Chinese cabbage were around -2.5℃ and the freezing points were around -0.4℃, so -2℃ was selected for the supercooled storage. The growth rate of lactic acid bacteria and yeast at -2℃ storage was lower than that at 2℃ storage. The reducing sugar was maintained higher due to the growth rate of lactic acid bacteria. The supercooled storage had an effect of delaying the fermentation of the salted Chinese cabbage, which may have the effect of delaying the fermentation of kimchi. This enhancement method of the direct refrigerator was effective for the supercooled storage and would be promising for commercial use.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.7-15
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• 2022

Since the direct and indirect damage caused by the fire in the underground utility tunnel will cause great damage to society as a whole, it is necessary to make efforts to prevent and control it in advance. The most of the fires that occur in cables are caused by short circuits, earth leakage, ignition due to over-current, overheating of conductor connections, and ignition due to sparks caused by breakdown of insulators. In order to find the cause of fire at an early stage due to the characteristics of the underground utility tunnel and to prevent disasters and safety accidents, we are constantly managing it with a detection system using image analysis and making efforts. Among them, a case of developing a fire detection system using CCTV-based deep learning image analysis technology has been reported. However, CCTV needs to be supplemented because there are blind spots. Therefore, we would like to develop a high-performance acoustic-based deep learning model that can prevent fire by detecting the spark sound before spark occurs. In this study, we propose a method that can collect sound in underground utility tunnel environments using microphone sensor through development and experiment of prototype module. After arranging an acoustic sensor in the underground utility tunnel with a lot of condensation, it verifies whether data can be collected in real time without malfunction.