• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.245-251
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• 2007

The performance of fuel cell is enhanced with increasing reaction surface. Narrow flow channels in flow plate cause increased pumping power. Therefore it is very important to consider the pressure drops in the flow channel of fuel cell. Previous research for pressure drop for micro channel of fuel cell was focused on effects of various configuration of flow channel without electrochemical reaction. It is very important to know pressure loss of micro flow channel with electrochemical reaction because fluid density in micro channel is changed due to chemical reaction. In this paper, it is investigated that the pressure drops in micro channel of various geometries at anode and cathode with electrochemical reaction and compared them to friction coefficient (fRe), velocity, pressure losses for corresponding non reacting flow channel. The results show that friction factors for cold flow channel could be used for parallel and bended flow channel for flow channel design of fuel cell. In the other hand, pressure drop for serpentine flow channel is the lowest among flow channels due to bypass flow across gas diffusion layer under reacting flow condition although its pressure drop is highest for cold flow condition.

• Journal of the Korea Society of Computer and Information
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• v.18 no.5
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• pp.1-8
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• 2013

Smartphone enables diverse applications to be used in mobile environments. In spite of the high performance of smartphones, battery life has become one of the major constraints in mobility. Therefore, power efficiency of the smartphone is one of the most important factors in determining the efficiency of the smartphone. In this paper, in order to analyze the power efficiency of the smartphone, we have various experiments according to several configuration parameters such as processor, display and OS. We also use diverse applications. As a result, power consumption is dependent on the processor complexity and display size. However, power consumption shows the unpredictable pattern according to the OS. Smartphone using android OS consumes high power when internet and image processing applications are executed, but It consumes low power when music and camera applications are executed. In contrary, smartphone based on iOS consumes high power when game and internet applications are executed but it consumes low power when camera and processing applications are executed. In general, smartphone using iOS is more power efficient than smartphone based on android OS, because smartphone using iOS is optimized in the perspective of the hardware and OS.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.431-439
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• 2013

This thesis is to research the before and after changes of physical configurations, blood components and physical strength for normal and geriatric diseased senior citizens at the end of 24 week of combined exercises constructed of aerobic and muscular strength training to create most suitable and effective complex exercise program for geriatric diseased patients. For this experiment 20 normal and 20 geriatric diseased patients in the age of 65 residing in "K" city were selected to carry out the 24 weeks of combined exercises in regularly. The result of the research showed that geriatric patients increased significantly in everything, but normal group showed significant change in only WHR. There was a slight improvement in the blood components for the average participants but it only differed slightly from the diseased participants so there were no major changes reflecting the outcomes from both before and after. After concluding the program both groups displayed positive improvements in stamina but no significant alterations in physical strength., agility, muscle endurance and balance. The positive factors for each groups could be that the norms were able to maintain their health and enhancement in stamina and diseased were able to prevent their condition from worsening. Additionally, over 50 percent of all senior citizens have one or more geriatric diseases but the participation of any physical activity is in the decrease. Henceforth, this is a field that still needs a lot of work and combined exercise programs should be created and followed through so it may enhance in the improvement of health and quality of life as well.

• Journal of the Korean Chemical Society
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• v.18 no.4
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• pp.223-238
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• 1974

CNDO/2 MO theoretical studies and kinetic studies of halide exchange reactions for alkylchloroformates have been carried out in order to investigate structure-reactivity relationship of alkylchloroformates. From the result of energetics, it was concluded that the most stable configuration of alkylchloroformate is that in which alkyl group and chlorine are trans to each other, and that the hindered rotation about the bond between the carbonyl carbon and alkoxy-oxygen bond is attributed to the ${\pi}-$electron delocalization. It has been found that the large charge separation is due to -M effect of carbonyl and alkoxy oxygens and-I effect of chlorine. The order of rates in solvents studied was $(CH_3)_2 > CO > CH_3CN{\gg}MeOH.$$I^->Br^->Cl^-$ in protic solvent, and of Cl^->Br^- >I^-$ in dipolar aprotic solvents. Alkyl group contribution has the decreasing order of $CH_3-> C_2H-{\gg}i-C_3H_7-.$ The solvent effect has been interpreted on the basis of initial and final state contribution. A transition state model has been suggested, and it has been proposed that the most favorable mechanism is the addition-elimination. From the results of activation parameters and electronic properties, an energy profile has been proposed. Structural factors determining reactivities of alkylchloroformates have been shown to be charge, energy level of ${\alpha}^*LUMO$ to C-Cl bond and ${\alpha}^{\ast} $antibonding strength with respect to C-Cl bond in this MO. Charge and polarizability of nucleophile, and the interaction of these effects with solvent structures are also found to be important.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.479-486
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• 2009

In natural environments, manganese (Mn) exists in the valence of +2, +3, and +4 and plays a pivotal role as a strong oxidant or reductant in the geochemical cycles of elements. Especially, Mn forms varying (oxyhydr)oxides. The oxidation state of structural Mn is characteristic to each oxide and is one of the most important factors controlling its geochemical behaviors such as solubility, sorption capacity, and redox potential. Therefore, it is important to elucidate processes governing Mn oxidation state in predicting the fate and transport of many redox sensitive elements in the environment. X-ray photoelectron spectroscopy (XPS) is a very useful method to determine the oxidation state of various elements in solid phases. In this study, the oxidation states of structural Mn in MnO, $Mn_2O_3$, $MnO_2$ were assessed based on the binding energy spectra of $Mn2p_{3/2}$ and Mn3s using XPS and were compared with those reported elsewhere. $Mn2p_{3/2}$ binding energies were determined as 640.9, 641.5, 641.8 eV for MnO, $Mn_2O_3$, $MnO_2$, respectively, which indicates that the binding energy increased with increasing Mn oxidation state. It was also noted that Ar etching may cause changes in electronic structure configuration on surface of the original sample.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1063-1069
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• 2012

In present paper, we used magnesium alloy having a lower density and higher electrical conductivity for bipolar plate to reduce the weight of PEM fuel cell. The silver was coated to prevent corrosion and form passivation film on the metal surface with sputtering. In acid proof evaluation for setting optimal coating conditions, the homogeneity of coating thickness was improved by coating with the thickness of 3 ${\mu}m$ which not indicated any micro cracks and the temperature $180^{\circ}C$. The performance test and evaluation based on the clamping pressure and channel depth to determine the configuration of bipolar plate for assembling single cell was implemented. And then we assembled single cell with this bipolar plate and implemented the performance test to ensure and compare the current-voltage performance followed as several factors such as coating or non-coating, the change of clamping pressure, the change of channel depth, etc. As these results, the maximum power density of single cell with the coated bipolar plate was 192 $mW/cm^2$ and it was confirmed that the power density per unit mass was better than existing metal bipolar plate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.359-368
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• 2016

In the 21st century, the Korean university education system is focused on innovation and change, including cooperation between industry and universities. It should be a goal to foster an industry-university ecosystem through interactions between universities and industry. Therefore, it is important to measure their relationships and to find advisable ways to measure the final results of industry-university cooperation. This paper sets out the achievements in cooperation and the satisfaction from such enterprises and measures mutual relationships influencing satisfaction from industry-university cooperation as to adherence and cooperation. Therefore, this research focuses on regression equation analysis in order to analyze the influence from satisfaction with industry-university cooperation based on factors in the relations between industry and universities. Also, as we examined the multicollinearity problem, before analyzing multiple regression, the multicollinearity problem appeared to be relatively irrelevant. In particular, the satisfaction variable, which can also be set as a subordinate variable, was in this research constructed as a high-dimensional subordinate variable composed of five individual variables. We then analyzed how the adherence construct factor and degree of cooperation construct factor influences the respective and subordinate satisfaction variables. As a result, the degree of realization of local customized programs was shown by the most significant variables. The biggest factor influencing satisfaction with industry-university cooperation proves the degree of realization for appropriate programs under local conditions, such as education, research, and technique guidance.

• Journal of the Korean Society for Computer Game
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• v.31 no.4
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• pp.197-203
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• 2018

As people's interest in Virtual Reality has recently increased, peripherals have also made many progress. There is a lot of research being done from VR environment to VR configuration through scanning at room level with various interface devices that can interact with objects in the environment. According to current VR research Home VR uses multiple haptic interfaces to interact with objects configured in the VR environment, the method uses room scanning to some extent is beyond the spatial constraints and may use tracking equipment to interact with real objects. And advances in 3D printers have enabled the distribution of commercial 3D printers and home 3D printers, and made it easy for 3D printers to create models of their choice at home or at home. Considering the above two factors, We think it is necessary to study the difference between a model's object that people feel when interacting directly with an easy-to-create model in a VR environment. Therefore, in this paper, we are going to implement objects produced by 3D printers in VR space and study the differences between using real objects and other general interaction equipment through user testing with those that are actually implemented.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.129-134
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• 2021

Recently, the demand for electricity is gradually increasing due to the rapid industrial development and the improvement of living standards. In the case of Korea, which is highly dependent on fossil fuels due to such a surge in electricity demand, reduction and freezing of greenhouse gas emissions due to international environmental regulations will immediately lead to a contraction in industrial activities. Accordingly, there are many difficulties in competition with advanced countries that want to link the environment with the country's industrial production activities, and the development of alternative energy as a countermeasure is of great interest around the world. Among these new power generation methods, small-scale power generation facilities with relatively small capacity include photovoltaic generation, wind power generation, and fuel cell generation. Among them, the fuel cell attracts the most attention in consideration of continuous operation, high power generation efficiency, and long-term durability, which are important factors for practical use. Therefore, in this paper, the fuel cell power generation system was researched and constructed by designing the power conversion circuit necessary to finally obtain the AC power used in our daily life by using the DC power generated from the fuel cell as an input.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.4
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• pp.257-268
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• 2021

As the variety and scale of facilities increase due to industrialization and urbanization, blind spots for facility safety management have occurred, resulting in numerous casualties.To meet safety and security needs of citizens living in smart cities, we present a procedure for establishing an integrated platform for facility safety management by combining 5G and digital twin technologies. It can be used to perform inspection according to risk factors and aging of facilities. In this paper, the current status of facility management and application directions of new 5G digital twin-based smart city technologies are reviewed and digital twin implementation procedures are presented. Five cities were selected as target areas: Osan, Gwangmyeong, Guri, Uijeongbu, and Anyang. Old and emergency facilities of each local government were selected. A total of 33 digital twin facilities reflecting policy directions of each city were selected. Focusing on facilities determined by each city, the purpose of this study was to define information technology infrastructure elements for the application of the 5G digital twin facility safety management integrated platform, define categories of implementation services, and suggest a concrete integrated platform configuration plan.