• Journal of the Korean Society of Industry Convergence
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• v.9 no.1
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• pp.61-66
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• 2006

In perspective of saving natural resource and energy, today's automobiles are in process of regenerating by smaller and lighter. In order to achieve the sufficiency on the consumption of the fuel, new mechanism and new assembly are required. Therefore the expectations on the new materials are very high. Especially, AI materials are widely used to reduce the weight. AI that is used in automobiles is mostly casting material, and according to the innovation of technique is in rapid development. AI Die casting is an important field as today's trend of lightweight on automobiles. One of the parts in steering system, Valve Housing plays a role of reduce the operating effort of drivers. Unfortunately, the Valve Housing which is widely reliable to the most automobiles are not developed at this moment in our automobile industry. Therefore, they are produced by casting method which cost three times or even more expensive in production. If Valve Housing, which is a part of steering system is produced by Gravity Casting, the space that manufacturing equipment will be increased, and more time and workers would be brought into service. For such reason, Die Casting would replace Gravity Casting in order to minimize cost of time, manpower, and working space.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.1
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• pp.40-45
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• 2014

This study examines the system and process of battery stored energy in vehicles and suggest the effective area for the use of V2G(vehicle-to-grid) from Jeju Smart Grid Demonstration Project. V2G means technology of electric power transmission from the battery of electric-drive vehicles to state grid. As for the increasing of effectiveness for demand-side control, V2G is a very good alternative. In the U.S., the utilization of electric vehicles is under 40% on average. In this case, we can use he battery of electric vehicle as role of frequency regulation or generator of demand-side resource. V2G, which is the element of Smart Transportation, consists of electric vehicle battery, BMS(battery management system), OBC(on-board charger), charging infrastructure, NOC(network operating center) and TOC(total operation center). V2G application has been tested for frequency regulation to secure the economical efficiency in the United States. In this case, the battery cycle life is not verified its disadvantage. On the other hand, Demand Response is required by low c-rate of battery in electric vehicle and It can be small impact on the battery cycle life. This paper concludes business area of demand response is more useful than frequency regulation in V2G application of electric vehicles in Korea. This provides the opportunity to create a new business for power grid administrator with VPP(virtual power plant).

• Journal of Korean Society of Transportation
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• v.24 no.4 s.90
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• pp.19-29
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• 2006

As the rapid increase of highway investments from Private sector the organizations of highway operator became diversified, and thus causing various unexpected problems. Highways invested by private capitals have different fare rates and managing systems. It is desirable to reduce drivers' inconvenience using more than two sections of highways spread over different jurisdictions. The main purposes of this research are i) data survey and problem statements ii) prediction of future problems and preparing appropriate countermeasures. This research are divided into two parts. They are management system and fare collection system. Major investigations of this study are as follows, optimum toll operation models depend on charging systems and interchange shapes of two interconnecting expressways. Assuming that the current payment and the new electronic payment system aye used concurrently for a while, some alternatives for the inter-operation to collect tolls ate suggested focusing on the efficiency to tollway corporations as well as convenience to drivers. The advantages and disadvantages of the alternatives, including their characteristics, are compared.

• Journal of Internet Computing and Services
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• v.18 no.5
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• pp.123-131
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• 2017

With the rapid growth of mobile services, the various charging methods for mobile data have emerged in the mobile service market. Among them, network operators have begun to provide the zero-rating without any extra charge for the data that use the specific mobile application & services. Zero-rating, the free mobile data services by the network operators provoked many platform operators to confront business opportunity and risk. Though the platform operators are in urgent need of the strategy planning that considers business environments, any research endeavors explaining zero-rating and platform does not exist. Moreover, the analyses of potential effects of zero-rating on the business acts of platform operators has not been performed. Therefore, the study aims to identify the potential business opportunity and risk to prepare the various strategic countermeasure in platform operators' shoes. The study might enable the researchers to properly understand zero-rating and platform, and be utilized as a reference in planning the business strategy of the platform operators.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.813-818
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• 2004

A systematic study of microbial fuel cells comprised of thermophilic Bacillus licheniformis and Bacillus thermoglucosidasius has been carried out under various operating conditions. Substantial amount of electricity was generated when a redox mediator was used. Being affected by operation temperature, the maximum efficiency was obtained at 50$^{\circ}C$ with an open circuit voltage of ca. 0.7 V. While a small change around the optimum temperature did not make much effect on the cell performance, the rapid decrease in performance was observed above 70$^{\circ}C$. It was noticeable that fuel cell efficiency and discharge pattern strongly depended on the kind of carbon sources used in the initial culture medium. In the case of B. thermoglucosidasius, glucose alone was utilized constitutively as a substrate in the microbial fuel cell irrespective of used carbons sources. When B. licheniformis was cultivated with lactose as a carbon source, best charging characteristics were recorded. Trehalose, in particular, showed 41.2% coulombic efficiency when B. thermoglucosidasius was cultured in a starch-containing medium. Relatively good repetitive operation was possible with B. thermoglucosidasius cells up to 12 cycles using glucose as a carbon source, when they were cultured with lactose as an initial carbon source. This study demonstrates that highly efficient thermophilic microbial fuel cells can be constructed by a pertinent modulation of the operating conditions and by carefully selecting carbon sources used in the initial culture medium.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.180-180
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• 2000

Plasma source ion implantation is a new doping technique for the formation of shallow junction with the merits of high dose rate, low-cost and minimal wafer charging damage. In plasma source ion implantation process, the wafer is placed directly in the plasma of the appropriate dopant ions. Negative pulse bias is applied to the wafer, causing the dopant ions to be accelerated toward the wafer and implanted below the surface. In this work, inductively couples plasma was generated by anodized Al antenna that was located inside the vacuum chamber. The outside wall of Al chamber was surrounded by Nd-Fe-B permanent magnets to confine the plasma and to enhance the uniformity. Before implantation, the wafer was pre-sputtered using DC bias of 300B in Ar plasma in order to eliminate the native oxide. After cleaning, B2H6 (5%)/H2 plasma and negative pulse bias of -1kV to 5 kV were used to form shallow p+/n junction at the boron dose of 1$\times$1015 to 5$\times$1016 #/cm2. The as-implanted samples were annealed at 90$0^{\circ}C$, 95$0^{\circ}C$ and 100$0^{\circ}C$during various annealing time with rapid thermal process. After annealing, the sheet resistance and the junction depth were measured with four point probe and secondary ion mass spectroscopy, respectively. The doping uniformity was also investigated. In addition, the electrical characteristics were measured for Schottky diode with a current-voltage meter.

• Explosives and Blasting
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• v.39 no.1
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• pp.1-9
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• 2021

As the national economic growth and the rapid increase in industrial structures are aging, the demand for removing steel structures is increasing, and research on improving the penetration performance of the linear shape charge explosives. In the study, numerical analyses were performed on the effect of the type of explosive used in the self-made shape charging container and the initiation method on the cutting performance of the steel plate and the effect on the shaped explosive installed close to it. ANSYS LS-DYNA, which can analyze the large deformation problem of materials due to explosion, was used, and an ALE(Arbitrary-Lagrange-Eulerian) model was applied that enables interlocking analysis of gases, liquids, and solid.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.4
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• pp.132-144
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• 2023

European and American countries are actively promoting eco-friendly cars to reduce exhaust emissions from internal combustion engines. In Korea, the "4th Basic Plan for Eco-Friendly Vehicles" aims to promote eco-friendly cars by improving charging infrastructure, expanding incentive systems, and targeting the supply of 1.13 million eco-friendly cars by 2025. As rapid growth in the number of electric vehicles sold is expected, estimates are required of this growth and corresponding power demands. In this study, the authors used a growth model to predict future growth in the electric vehicle market and a previously derived electricity generation model to estimate corresponding power demands up to 2036, the target year of the "10th Basic Plan for Power Supply and Demand". The results obtained provide useful basic research data for future electric vehicle infrastructure planning.

• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.365-372
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• 2024

As the energy density of lithium-ion batteries (LIBs) continues to increase, various separators are being developed to with the aim of improving the safety performance. Although poly(imide) (PI)-based separators are widely used, it is difficult to control their pore size and distribution, and this may further increase the risk associated. Herein, a melamine phosphonic acid (MP)-coated PI separator that can effectively control the pore structure of the substrate is suggested as a remedy. After the MP material is embedded into the PI separator with a simple one-step casting process, it effectively clogs the large pores of the PI separator, preventing the occurrence of internal short circuits during charging. It is anticipated that the MP material can also suppress rapid thermal runaway upon cycling due to its ability to reduce the internal temperature of the LIB cell caused by the desirable endothermic behavior around 300℃. According to experiments, the MP-coated PI separator not only decreases the thermal shrinkage rate better than commercial poly(ethylene) (PE) separators but also exhibits a desirable Gurley number (109.6 s/100 cc) and electrolyte uptake rate (240%), which is unique. The proposed separator is electrochemically stable in the range 0.0-5.0 V (vs. Li/Li⁺), which is the typical working potential of conventional electrode materials. In practice, the MP-coated PI separator exhibits stable cycling performance in a graphite-LiNi_0.83Co_0.10Mn_0.07O₂ full cell without an internal short circuit (retention: 90.3%).

• Korean Journal of Materials Research
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• v.8 no.3
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• pp.268-273
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• 1998

Standard Zircaloy-4 sheets, charged with 230-250ppm hydrogen by the gas-charging method and homogenized at $400^{\circ}C$ for 72hrs in a vacuum, were corroded in pure water and aqueous LiOH solutions using static autoclaves at $350^{\circ}C$. Their corrosion behaviors were characterized by measuring their weight gains with the corrosion time and observing their microstructures using an optical microscope and a scanning electron microscope. The elemental depth profiles for hydrogen and lithium were measured using a secondary ion mass spectrometry(S1MS) to confirm their distributions at the oxidelmetal interface. The normal Zircaloy-4 specimens corroded abruptly and heavily at the concentration of Li ions more than 30ppm in the aqueous solution. This is due to accelerations by the rapid oxidation of many Zr- hydrides formed by the large amount of absorbed hydrogen, resulting from the increased substitution of $Li^{+}$ ions with $Zr^{4+}$-sites in the oxide as the Li ion concentration increased. The specimens that had been charged with amounts of hydrogen greater than its solubility corroded early with a more rapid acceleration than normal specimens, regardless of the corrosion solutions. At longer corrosion times. however, normal specimens showed a rather accelerated corrosion rate compared to the hydrogen-charged specimens. These slower corrosion rates of the hydrogen-charged specimens at the longer corrosion times would be due to the pre-existent Zr-hydride in the matrix, which causes the hydrogen pick- up into the specimen to be depressed, when the oxide with an appropriate thickness formed.