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        검색결과 34

        1.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aims to explore the appropriate water pressure control of water supply pipeline to reduce water losses of water supply network in Jinan-gun. The current water pressure status of each 5 blocks and the impact of optimized water pressure on improving revenue water rate were investigated. In order to obtain the flow rate and water pressure data of each small block, a smart hub is set in the pressure reducing valve chamber at the inlet of the small block, and a smart water pressure meter is installed in the fire hydrant and the faucet of the customer. For the pressure reducing valves installed for water pressure management system of each block, the diameter calculation standard and type of the pressure reducing valve are determined, and the application reasons are put forward. The analysis results of water pressure management for each small block in Jinan-gun show that the pressure control equipment and water pressure management need to be improved in four small blocks. The water flow rate in Jinan-eup and Sangjeon-myeon increases from 57.2% to 87.6% when the water pressure control is completed.
        4,000원
        3.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we investigated the effects of diesel-palm oil biodiesel-ethanol blends on combustion and emission characteristics in a 4-cylinder common rail direct injection (CRDI) diesel engine at low idling operations. The engine speed and engine load was 750 rpm and 40 Nm, while the main and pilot injection timing was respectively fixed at 2 °CA before top dead center (BTDC) and 20 °CA BTDC. The experimental results showed that the cylinder pressure increased with the increasing of palm oil biodiesel ratio from 20% to 100%. In addition, the peak value of cylinder pressure increased by 4.35% compared with pure diesel fuel when 5 vol.% ethanol oil added to diesel oil. Because the palm oil biodiesel and ethanol are the oxygenated fuel, the oxygen content played an important role in improving combustion. Based on the high oxygen content of biodiesel and ethanol, their mixing with diesel fuel effectively reduced PM emissions but increased NOx slightly, while CO and HC had no significant changes.
        4,000원
        4.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the effect of various pilot injection timings on combustion and emission characteristics were investigated in a common-rail direct injection (CRDI) diesle engine fueled with diesel-ethanol blends. The engine speed and engine load were controlled at constant 1500rpm and 70Nm, respectively. The tested fuels were DE0 (pure diesel fuel), DE5 (5 vol.% ethanol blended with 95 vol.% diesel oil), DE10 (10 vol.% ethanol blended with 90 vol.% diesel oil) and DE15 (15 vol.% ethanol blended with 85 vol.% diesel oil). The main injection timing was fixed at 0°CA TDC (top dead center), while various pilot injection timings including 25°CA BTDC (before top dead center), 20°CA BTDC and 10°CA BTDC were selected as the experimental variable. The experimental results showed that various pilot injection timings had little effect on the peak value of cylinder pressure, but had great influence on the start of combustion. The peak value of heat release rate (HHR) increased with the increase of ethanol content. However, the peak value of HRR reduced as the pilot injection is delayed. The diesel fuel containing 10% ethanol had a highest peak value of combustion pressure compared with the others, while the pilot injection timing occurred at 25°CA BTDC. On the other hand, the exhaust emissions of DE10 was also the lowest compared with the others. In addition, with the increase of ethanol content in diesel the PM and NOx emissions reduced.
        4,000원
        5.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Deicing agent refers to the substance that melts snow by exothermic or endothermic chemical reaction after spraying on snow. It also has the function of reducing the freezing point to prevent freezing. However, the long-term use of deicing agent can cause some negative problems, such as pot hole, concrete corrosion, vehicle and steel bridge parts corrosion. At present, wet salt spray deicing is a cost-effective deicing method that is being widely used. Typical deicing agents are calcium chloride and sodium chloride. Deicing equipment is placed to similar or higher corrosive environment than coastal or marine environment due to direct contact to chloride in deicing operation. Therefore, the anti-corrosion control is very important for the maintenance of deicing equipment. In this study, corrosion resistance, blistering and repairability of the deicing equipment were tested by using test standard (salt water production and spraying- KS D 9502 , evaluating degree of rusting- ASTM D 610, evaluating degree of blistering- ASTM D 714, pull-off strangth of coatings- ASTM D 4541). And an economical coating system with long-term antirust performance was constructed. The results show that the performance of the coating system has been improved than with the original coating.
        4,000원
        6.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the shrinkage at the artificial skin tissue and temperature characteristics of rubber pole were analyzed by the experimental and numerical method. A artificial skin tissue was produced by using the rigid sponge pad. The impact of tissue was applied by three types of rubber pole. The shrinkage results along the depth of tissue were measured according to the repetition count of impact. When the shape of rubber pole was sphere type, the shrinkage was greatest. The temperature around the pole was highest in the sphere type while that inside pole was greatest in the twine deep sphere type. This is because the pole temperature of twine deep sphere type was transmitted more inside. As a result, the sphere type rubber pole was the most effective because it showed the largest shrinkage and the lowest temperature gradient during impact.
        4,000원
        7.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the thermal behavior characteristics of flange case interior were analyzed by the numerical method. The boundary conditions at the inlet port of flange case were the heat flux and heat flux time. As the heat flux time at inlet of case increased, the temperature values gradually increased, and the degree of increase was very small. If the heat flux of the melted iron increases to 2,000,000 W/m2, the temperature change at the case interior will occur largely, causing heat deformation. As a result, in order to reduce thermal defects at the case interior, the heat flux and heat flux time of the melted iron should be set within 500,000 W/m2 and 5 seconds, respectively.
        4,000원
        9.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the characteristics of muscle relaxation were analyzed by the experimental and numerical method. A skin tissue was produced by imitational biological tissue using the agar powder, saline solution and sugar. The tissue was exposed to three types of wavelength-blue visible radiation(410 nm), red visible radiation(635 nm), and infrared ray(830 nm). The temperature results along the depth of tissue were measured according to the variation of light wavelength and irradiation time. The temperature change of the tissue shown up similar pattern regardless of the light wavelength kinds. The wavelength of infrared ray penetrated strongly into tissue between 3.2 mm and 11.4 mm. Also, the temperature change with the irradiation time was small, and the temperature value of the infrared ray was the largest. As a result, the muscle relaxation will occur mainly at the infrared wavelength.
        4,000원
        10.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the thermal behavior of adaptor housing was analyzed by the numerical method. The boundary conditions used to die casting process were the temperature of molten metal and injection time. As the temperature of the molten metal increased, the tensile strength of the product decreased by the blow hole generated in the molten metal, and the decreasing tendency was gradually decreased. As the injection time of the molten metal increased, the heat flux rose, but the degree of the increase was very small. So, the injection time of the molten metal had little effect on the thermal behavior and diffusion of the adapter housing. As a result, the heat of the molten metal was transferred into the housing and the thermal behavior spread widely.
        4,000원
        14.
        2018.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, the performance of the Refrigerator is improved by controlling the fan speed on the condenser side or subcooling/superheating degree by superimposing the refrigerant on the inlet side of the compressor to the outlet side pipe. However, these methods may have the effect of lowering the performance due to operation of the severe condition of the main parts and may not achieve the intended performance. The Peltier Module was used to improve the performance of the refrigerator and increase the durability of the main parts through an artificial subcooling device.
        4,000원
        15.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Since the encoder and resolver are expensive, it is difficult to apply it as a position sensor of a motor in a real industrial field. Optical position sensors, such as encoders and resolvers, are also difficult to mount because of their size and durability. Therefore, in order to solve these problems, we propose a system that uses a linear motor as a stator and a magnet plate as a mover, and a system that excludes a separate linear scale and uses two linear Hall sensors and permanent magnets to generate a conventional sine wave, A linear motor capable of detecting an absolute position and a movement position of a magnet, a control method thereof, and a technology development that can reduce a production cost by developing a position control system using a magnet mover that can improve stability and reliability.
        4,000원
        16.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we analyzed the radiant heat performance of ballast fin when the aspect ratio of the fin of ballast was changed. The minimum size of the mesh was 0.02 mm, and the grid number was about more than 11 thousand. In order to analyze the radiant heat performance of ballast fin, the aspect ratio of fin was 1.00(2 mm:2 mm), 1.80(1.5 mm:2.7 mm), and 0.56(2.7 mm:1.5 mm) respectively; that the heat transfer area was constantly 0.4 mm 2 . The numerical condition was that heat flux was constantly 1×10 5 W/m 2 , and measuring times were 0.1 second, 0.2 second, 0.5 second, 2 seconds, 5 seconds and 10 seconds respectively. The temperature values of fin at the 1.00 and 1.80 of aspect ratios were extremely large when heat flux time was 10 seconds. As a result, the maximum value of radiant heat performance of ballast fin appeared to the aspect ratio of 1.80.
        4,000원
        17.
        2017.10 구독 인증기관·개인회원 무료
        We report here one species, Ampelodesmus cf. granulosus myrmecophilus millipede (Pyrgodesmidae) collected fromcolonies of Brachyponera chinensis (Formicidae: Hymenopera). The family Pyrgodesmidae contained over 500 speciesdistribute mainly in tropics (Shear, 2011). Some species are found only in ant colonies, and are considered obligate myrmecophiles(Stoev et al. 2005). Myrmecophilus pyrgodesmid millipedes are known to scavenger as they feed on debris of host ants.Largely unknown is how millipedes can avoid from aggression of host ants, but host ants completely ignoring their invader(Komatsu, unpublished data). Two genera and four species of family Pyrgodesmidae were known from Japan which werecompletely unknown from South Korea. In this study, we provide description, especially gonopods of male, host informationand breeding records of Ampelodesmus cf. granulosus.
        20.
        2017.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was to develop the products that the Lamp and Ballast are combined for the purpose of easy installation to complement the difficulty of the installation process due to the structure of existing product which the lamp and the Ballast are separated, and that have 8-wavelengths dual-lamp structure such as solar, an advantage of more than 3 times longer life than fluorescent lamp and immediately lighting. This study developed the commercialized products that can prevent the environmental pollution caused by low efficiency and short life time of existing Lamps, and can replace the LED Lighting products which has high Glare index with high price, has also developed the variety of application for industrial, commercial, indoor and military. The applied product are Street lights, Security lights, Flood lights, Indoor lights and lights for fishing. This study solved the optimum distribution and placement of components considering the lightest weight first and thermal interference caused by combination of lamp and ballast by thermal release through applying the double bulkhead design of ballast box, and implemented the high efficiency Eco-friendly products with excellent visibility which can be applied and used for indoor and outdoor both place through high temperature and high humidity test, which has an advantage of 8-wavelengths of same spectrum of solar through the initial trial production.
        4,000원
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