Most of steam power plant in Korea are heating the feed water system to prevent freezing water flowing in the pipe in winter time. The heating system is operated whenever the ambient temperature around the power plant area below 5 degree Centigrade. But this kind of heat supplying system cause a lot of energy consuming. If we think about the method that the temperature of the each pipe is controled by attaching the temperature measuring sensor like RTD sensor and heat is supplied only when the outer surface temperature of the pipe is under 5 degree Centigrade, then we can save a plenty of energy. In this study, the computer program package for simulation is used to compare the energy consumption load of both systems. Energy saving rate is calculated for the location of Youngweol area using the data of weather station in winter season, especially the January' severe weather data is analyzed for comparison. Various convection heat transfer coefficients for the ambient air and the flowing water inside the pipe was used for the accurate calculation. And also the various initial flowing water temperature was used for the system. Steady state analysis is done previously to approximate the result before the simulation. The result shows that the temperature control system using RTD sensor represents the high energy saving effect which is more than 90% of energy saving rate. Even in the severe January weather condition, the energy saving rate is almost 60%.

Electrical Moving system(EMS)은 제조업(주로 자동차 생산공장 및 전자제품 생산공장, 식품공장 등) 생산공장에서 사용되는 무인 자동화 운반설비를 말한다. 지금으로부터 200년전 James Ford가 개발했던 공장자동화의 역사는 산업혁명을 거치면서 발전을 거듭하였으며 최근에는 작업자의 안전 및 돌발적 사고로 인한 생산성 급감이 생산공장에서는 중요한 이슈로 떠오르고 있으며, 이를 보완하기 위한 기존 시스템의 운반설비 시스템에 더욱 스마트한 기능을 더한 자동화설비에 대한 필요성이 증대되었다. 이를 위해 먼저 현재 생산중인 제어부 전차반의 크기를 기존 대비 30 % 정도 compact하게 재설계하여 소형화함으로써 사고를 줄이며 스마트한 기능은 더욱 증대시킨 제어부 표준전차반 제작을 실시하고자 한다.

Manganese dioxide (MnO2) is one of the most important cathode materials used in both aqueous and non-aqueous batteries. The MnO2 polymorph that is used for lithium primary batteries is synthesized either by electrolytic (EMD-MnO2) or chemical methods (CMD-MnO2). Commonly, electrolytic manganese dioxide (EMD) is used as a cathode mixture material for dry-cell batteries, such as a alkaline batteries, zinc-carbon batteries, rechargeable alkaline batteries, etc. The characteristics of lithium/manganese-dioxide primary cells fabricated with EMD-MnO2 powders as cathode were compared as a function of the parameters of a manufacturing process. The flexible primary cells were prepared with EMD-MnO2, active carbon, and poly vinylidene fluoride (PVDF) binder (10 wt.%) coated on an Al foil substrate. A cathode sheet with micro-porous showed a higher discharge capacity than a cathode sheet compacted by a press process. As the amount of EMD-MnO2 increased, the electrical conductivity decreased and the electrical capacity increased. The cell subjected to heat-treatment at 200˚C for 1 hr showed a high discharge capacity. The flexible primary cell made using the optimum conditions showed a capacity and an average voltage of 220 mAh/g and 2.8 V, respectively, at 437.5μA.

In this study we aimed to examine the co-doping effects of 1/6mol% Co3O4 and 1/4mol% Cr2O3 (Co:Cr=1:1)on the reaction, microstructure, and electrical properties, such as the bulk defects and the grain boundary properties, of ZnO-Bi2O3-Sb2O3 (ZBS; Sb/Bi=0.5, 1.0, and 2.0) varistors. The sintering and electrical properties of Co,Cr-doped ZBS, ZBS(CoCr)varistors were controlled using the Sb/Bi ratio. Pyrochlore (Zn2Bi3Sb3O14), α-spinel (Zn7Sb2O12), and δ-Bi2O3 were formed inall systems. Pyrochlore was decomposed and promoted densification at lower temperature on heating in Sb/Bi=1.0 by Cr ratherthan Co. A more homogeneous microstructure was obtained in all systems affected by α-spinel. In ZBS(CoCr), the varistorcharacteristics were improved (non-linear coefficient, α=20~63), and seemed to form Zni..(0.20eV) and Vo.(0.33eV) asdominant defects. From impedance and modulus spectroscopy, the grain boundaries were found to be composed of anelectrically single barrier (0.94~1.1eV) that is, however, somewhat sensitive to ambient oxygen with temperature. The phasedevelopment, densification, and microstructure were controlled by Cr rather than by Co but the electrical and grain boundaryproperties were controlled by Co rather than by Cr.

We aimed to examine the co-doping effects of 1/6mol% Mn3O4 and 1/4mol% Cr2O3 (Mn:Cr=1:1) on the reaction,microstructure, and electrical properties, such as the bulk defects and grain boundary properties, of ZnO-Bi2O3-Sb2O3 (ZBS;Sb/Bi=0.5, 1.0, and 2.0) varistors. The sintering and electrical properties of Mn,Cr-doped ZBS, ZBS(MnCr) varistors werecontrolled using the Sb/Bi ratio. Pyrochlore (Zn2Bi3Sb3O14), α-spinel (Zn7Sb2O12), and δ-Bi2O3 (also β-Bi2O3 at Sb/Bi≤1.0)were detected for all of the systems. Mn and Cr are involved in the development of each phase. Pyrochlore was decomposedand promoted densification at lower temperature on heating in Sb/Bi=1.0 system by Mn rather than Cr doping. A morehomogeneous microstructure was obtained in all systems affected by α-spinel. In ZBS(MnCr), the varistor characteristics wereimproved dramatically (non-linear coefficient, α=40~78), and seemed to form Vo.(0.33eV) as a dominant defect. Fromimpedance and modulus spectroscopy, the grain boundaries can be seen to have divided into two types, i.e. one is tentativelyassigned to ZnO/Bi2O3 (Mn,Cr)/ZnO (0.64~1.1eV) and the other is assigned to the ZnO/ZnO (1.0~1.3eV) homojunction.

ZnO nanorods were successfully fabricated on Zn foil by chemical bath deposition (CBD) method. The ZnO precursor concentration and immersion time affected the surface morphologies, structure, and electrical properties of the ZnO nanorods. As the precursor concentration increased, the diameter of the ZnO nanorods increased from ca. 50 nm to ca. 150 nm. The thicknesses of the ZnO nanorods were from ca. 1.98μm to ca. 2.08μm. ZnO crystalline phases of (100), (002), and (101) planes of hexagonal wurtzite structure were confirmed by XRD measurement. The fabricated ZnO nanorods showed a photoluminescene property at 380 nm. Especially, the ZnO nanorods deposited for 6 h in solution with a concentration of 0.005M showed a stronger (101) peak than they did (100) or (002) peaks. In addition, these ZnO nanorods showed a good electrical property, with the lowest resistance among the four samples, because the nanorods were densely in contact and relatively without pores. Therefore, a ZnO nanorod substrate is useful as a highly sensitive biochip substrate to detect biomolecules using an electrochemical method.

A fabrication method to improve the processability of thermoplastic carbon nanotube (CNT) mat composites was investigated by using in-situ polymerizable and low viscous cyclic butylene terephthalate oligomers. The electrical conductivity of the CNT mat composites strongly depended on the compression pressure, and the trend can be explained in terms of two cases, low and high compression pressure, respectively. High CNT mat content in the CNT mat composites and the surface of the CNT mat composites with fully contacted CNTs was achieved under high compression pressure, and direct contact between four probes and the surface of the CNT mat composites with fully contacted CNTs gave resistance of 2.1Ω. In this study the maximum electrical conductivity of the CNT mat composites, obtained under a maximum applied compression pressure of 27 MPa, was 11 904 S m-1, where the weight fraction of the CNT mat was 36.5%.

Graphite oxide (GO) was produced using the modified Hummer's method. Poly(p-phenylene sulfide) (PPS)/reduced graphite oxide (RGO) composites were prepared by in situ polymerization method. The electrical conductivity of the PPS/RGO composites was no more than 82 S/m. It was found that as GO content increased in the PPS/RGO composites, the crystallization temperature and electrical conductivity of the composites increased and the percolation threshold value was at 5-8 wt% of GO content.

Nickel oxide was doped with a wide range of concentrations (mol%) of Aluminum (Al) by solvothermal synthesis;single-phased nano powder of nickel oxide was generated after calcination at 900oC. When the concentration of Al dopant wasincreased, the reduced intensity was confirmed through XRD analysis. Lattice parameters of the synthesized NiO powder weredecreased after treatment of the dopant; parameters were increased when the concentration of Al was over the doping limit(5mol% Al). The binding energy of Ni2+ was chemically shifted to Ni3+ by doping Al3+ ion, as confirmed by the XPS analysis.The tilted structure of the synthesized NiO with 5mol% Al dopant and the polycrystalline structure of the Ni0.75Al0.25O wereobserved by HR-TEM analysis. The electrical conductivity of the newly synthesized NiO was highly improved by Al dopingin the conductivity test. The electrical conductivity values of the commercial NiO and the synthesized NiO with 5mol% Aldopant (Ni0.95Al0.05O) were 1,400s/cm and 2,230s/cm at 750oC, respectively. However, the electrical conductivity of thesynthesized NiO with 10mol% Al dopant (Ni0.9Al0.1O) decreased due to the scattering of free-electrons caused by the largenumber of impurity atoms; the electrical conductivity of Ni0.9Al0.1O was 545s/cm at 750oC.

The present study purposed to examine the effects of transcutaneous electrical nerve stimulation, self-stretching and functional massage on the recovery of muscle contraction force for muscle fatigue caused by sustained isotonic contraction. The subjects of this study were 45 healthy students. They were divided into transcutaneous electrical nerve stimulation group(n=15), self-stretching group(n=15) and functional massage group(n=15), and using Primus RS. We observed the pattern of changes in maximal voluntary isometric contraction force(MVIC) after causing muscle fatigue in quadriceps femoris muscle through sustained isotonic contraction. Maximal voluntary isometric contraction force(MVIC) were greatly increased after transcutaneous electrical nerve stimulation, self-stretching and functional massage. In the comparison of recovery rate of muscle contraction force for muscle fatigue caused by sustained isotonic contraction among the treatment groups, it did not show any significant differences. However, it showed that each treatment may be effective in recovery of muscle fatigue caused by sustained isotonic contraction.

목적 : 본 연구는 뇌경색으로 인한 연하장애 환자를 운동자극군과 감각자극군으로 나누어 전기자극치료를 적용하였을 때에 각각의 치료 효과를 확인하고 두 치료간의 효과 차이를 비교해보고자 하였다. 연구방법 : 본 연구는 뇌경색으로 연하장애가 발생하였고, 전기 자극의 강도를 결정하기 위하여 의사표현이 가능한 사람 을 대상으로 하였다. 전기자극치료는 1일 1회, 30분 동안, 일주일에 5회, 4주간 실시하였으며 전기자극치료 전에 운동 자극군과 감각자극군 모두에게 구강운동치료를 30분씩 적용하였다. 전기자극치료의 효과를 알아보기 위해 전기자극 치료 전과 4주 간의 치료 후에 비디오투시검사를 실시하였으며, 기능적 연하곤란 척도, 침습-흡인 척도, 미국언어청 각협회 연하척도를 이용하여 평가하였다. 결과 : 전기자극치료 전에 두군 사이에서 삼킴 기능에는 차이가 없었고(p>.05), 4주간의 전기자극치료 후에 두군 모두에 서 기능적 연하곤란 척도의 인두기 총점, 미국언어청각협회 연하 척도에서 삼킴 기능의 유의한 향상을 보였으며 (p<.05), 삼킴 후 잔여물이 유의하게 감소하였다(p<.05). 침습-흡인 척도는 운동자극군은 연식에서만 유의하게 향상 되었으나(p<.05), 감각자극군에서는 모든 검사식에서 유의하게 향상되었다(p<.05). 자극 강도에 따른 치료 효과를 비 교하였을 때에는 두군 사이에 삼킴 기능의 향상 정도는 유의한 차이가 없었다(p>.05). 결론 : 본 연구를 통해 연하장애의 치료를 위한 전기자극치료 시에 감각자극만으로도 삼킴 기능의 향상에 효과가 있으며 감각자극이 침습과 흡인의 감소에 효과적이라는 것을 알 수 있으므로 임상에서 전기 자극 강도를 조절하여 적용할 수 있을 것이라 기대한다.

In the present work, exfoliated graphite nanoplatelets (EGN) of 1 μm in average particle size, which were prepared by heating at 900℃ and then subjected to ultrasonic, ball-milling, and vibratory ball-milling techniques, were uniformly incorporated into phenylethynyl-terminated polyimide (PETI-5) resin. The fracture surface morphology and the electrical resistivity of the EGN/PETI-5 composites were investigated. The results showed that the fracture surfaces and the electrical resistivity strongly depended on the EGN content. The fracture surfaces became more ductile and roughened with increasing EGN and the electrical resistivity was gradually decreased with increased EGN loading, indicating the percolation threshold at 5 wt% EGN.

유기 박막 트랜지스터 (organic thin-film transistors; OTFTs)는 유기 반도체 그리고 디스플레이와 같은 분야에 그들의 잠재적인 응용 가능성 때문에 많은 주목을 받고 있다. 하지만 급격한 산화 혹은 낮은 전기 이동도와 같은 단점으로 인하여 n-형 물질은 p-형 물질에 비해서 상대적으로 많은 연구가 진행되지 못한 실정이다. 따라서 본 논문에서는 n-형 반도체 물질인 [6,6]-phenyl-C61-butyricacidmethylester (PCBM)과 Poly(4-vinylphenol) (PVP)을 유기 절연막으로 이용하여 o-dichlorobenzene, toluene and chloroform과 같은 다양한 유기 용매를 사용한 플라스틱 기판에 유기트랜지스터를 제작하였고 유기 용매가 ODCB 경우 전계 효과 이동도는 약 0.034 cm2/Vs 그리고 점멸비(on/off ratio)는 ~1.3×105 으로 향상 되었다. 다양한 유기 용매의 휘발성에 따라서 PCBM TFT의 전기적 특성에 미치는 영향을 규명하였다.

In this work, expanded graphite (EG)-reinforced poly(ethylene terephthalate) (PET) nanocomposites were prepared by the melt mixing method and the content of the EG was fixed as 2 wt%. The effect of multi-walled carbon nanotubes (MWCNTs) as a co-carbon filler on the electrical and mechanical properties of the EG/PET was investigated. The results showed that the electrical and mechanical properties of the EG/PET were significantly increased with the addition of MWCNTs, showing an improvement over those of PET prepared with EG alone. This was most likely caused by the interconnections in the MWCNTs between the EG layers in the PET matrix. It was found that the addition of the MWCNTs into EG/PET led to dense conductive networks for easy electron transfers, indicating a bridge effect of the MWCNTs.

Graphene is an attractive material for device applications, but device characteristics are very unstable because the graphene is very sensitive to environmental factors such as charges nearby the graphene, metal contacts, defects, contaminants and other adsorbates. Since the interactions between graphene and environmental factors affect the electrical characteristics of graphene devices, the interpretation of electrical characteristics as simple as current-voltage curves is non-trivial, despite the common practice of using well known electrical characterization methods that have been used in silicon MOSFET. This paper addresses major obstacles in the electrical characterization of graphene devices and offers countermeasures to improve the accuracy of electrical characterization methods.

This study was performed to investigate the exposure levels of magnetic field (MF) in residences near electrical transformer rooms in apartment buildings in Korea. We determined that the location of transformer rooms in apartment buildings in Korea is not same as in other countries. In particular, in Korea, the transformer on the pole near buildings serves residential buildings of less than 5 floors. In the buildings taller than 5 floors transformers are often placed below the parking lots in the basement. We estimated that there were, however, about 85,000 with transformer room adjacent to an apartment and had identified about 1,600 apartment buildings with transformers that can be included in the TransExpos study. The mean value of measured MFs was 1.17 mG in apartments above transformer room and 0.97 mG in other floors from transformer room. This study was concluded that apartments in building with transformer room can be classified into high-exposure category based on their location in relation to transformer room.

Tungsten nanopowders were produced by the method of wires electrical explosion in the different gases. The study of phase and dispersed composition of the powders was carried out. The influence of electrical parameters such as the value of energy input in wire and the arc stage of the explosion was discussed. The factors that make for decreasing the particles size are the lower pressure of surrounding gas and the use of addition of chemically reactive gas.

A Li2O-2SiO2 (LS2) glass was investigated as a lithium-ion conducting oxide glass, which is applicable to a fast ionic conductor even at low temperature due to its high mechanical strength and chemical stability. The Li2O-2SiO2 glass is likely to be broken into small pieces when quenched; thus, it is difficult to fabricate a specifically sized sample. The production of properly sized glass samples is necessary for device applications. In this study, we applied spark plasma sintering (SPS) to fabricate LS2 glass samples which have a particular size as well as high transparency. The sintered samples, 15mmφ×2mmT in size, (LS2-s) were produced by SPS between 480˚C and 500˚C at 45MPa for 3~5mim, after which the thermal and dielectric properties of the LS2-s samples were compared with those of quenched glass (LS2-q) samples. Thermal behavior, crystalline structure, and electrical conductivity of both samples were analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and an impedance/gain-phase analyzer, respectively. The results showed that the LS2-s had an amorphous structure, like the LS2-q sample, and that both samples took on the lithium disilicate structure after the heat treatment at 800˚C. We observed similar dielectric peaks in both of the samples between room temperature and 700˚C. The DC activation energies of the LS2-q and LS2-s samples were 0.48±0.05eV and 0.66±0.04eV, while the AC activation energies were 0.48±0.05eV and 0.68±0.04eV, respectively.

In this present work, the effect of additional heat-treatment (AHT) in the range from 1800℃ to 2400℃ on the chemical composition, morphology, microstructure, tensile properties, electrical resistivity, and thermal stability of commercial polyacrylonitrile (PAN)-based carbon fibers was explored by means of elemental analysis, electron microscopy, X-ray diffraction analysis, single fiber tensile testing, two-probe electrical resistivity testing, and thermogravimetric analysis (TGA). The characterization results were in agreement with each other. The results clearly demonstrated that AHTs up to 2400℃ played a significant role in further contributing not only to the enhancement of carbon content, fiber morphology, and tensile modulus, but also to the reduction of fiber diameter, inter-graphene layer distance, and electrical resistivity of "as-received" carbon fibers without AHT. The present study suggests that key properties of commercial PAN-based carbon fibers of an intermediate grade can be further improved by proprietarily adding heat-treatment without applying tension in a batch process.