• Transactions of the Korean hydrogen and new energy society
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• v.7 no.1
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• pp.29-37
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• 1996

Alkaline water electrolysis has been commercialized as the only large-scale method for a long time to produce hydrogen and the technology is superior to other methods such as photochemical, thermochemical water splitting, and thermal decomposition method in view of efficiency and related technical problem. However, such conventional electrolyzer do not have high electric efficiency and productivity to apply to large scale hydrogen production for energy or chemical feedstocks. Solid polymer electrolyte water electrolysis using a perfluorocation exchange membrane as an $H^+$ ion conductor is considered to be a promising method, because of capability for operating at high current densities and low cell voltages. So, this is a good technology for the storage of electricity generated by photovoltaic power plants, wind generators and other energy conversion systems. One of the most important R&D topics in electrolyser is how to minimize cell voltage and maximize current density in order to increase the productivity of the electrolyzer. A commercialized technology is the hot press method which the film type electrocatalyst is hot-pressed to soild polymer membrane in order to eliminate the contact resistance. Various technologies, electrocatalyst formed over Nafion membrane surface by means of nonelectrolytic plating process, porous sintered metal(titanium powder) or titanium mesh coated with electrocatalyst, have been studied for preparation of membrane-electrocatalyst composites. In this study some experiments have been conducted at a solid polymer electrolyte water electrolyzer, which consisted of single cell stack with an electrode area of $25cm^2$ in a unipolar arrangement using titanium mesh coated with electrocatalyst.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.101-111
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• 2011

A new MAC protocol, MT-MAC(Multi-Tier Medium Access Control) by name, is proposed for dense sensor networks. Depending on the density of nodes in a virtual cluster, the cluster header performs the splitting to several tiers in nodes of virtual cluster. MT-MAC split the tiers to use modfied-SYNC message after receiving the beacon message from the cluster header. Because only the sensor nodes in the same tier communicate each other, less power is consumed and longer network life time is guaranteed. By a simulation method with NS-2, we evaluated our protocol. In dense nodes environments, MT-MAC protocol shows better results than S-MAC in terms of packet delivery rates throughput and energy consumption.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2072-2078
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• 2011

In photovoltaic(PV) system, for obtaining maximum efficiency of solar power systems, the solar tracking system must be controlled to match position of the sun. In this paper, we design the solar tracking system to track movement of the sun using CdS sensor modules and to determine direction of the sun under shadow of directions. In addition, for an intelligent computation in tracking of the sun, a fuzzy controller is allocated to space avaliable for splitting area of fuzzy part for the fuzzy input space(grid-type fuzzy partition) in which a fuzzy grid partition divides fuzzy rules bases. As well, a simple model of solar tracking system is designed by two-axis motor control systems and the 8-direction sensor module that can measure shadow from CdS sensor modules by matching of axis of CdS modules and PV panels. We demonstrate this systems is effective for fixed location and moving vessels and our fuzzy controller can track the satisfactorily.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.30-50
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• 2017

Currently, exhaust gas emitted from thermal power plants and various combustion facilities that consume large amounts of fossil fuels such as coal, oil, and natural gas contains high concentrations of $CO_2$ and is a major cause of global warming. Conventionally, as a countermeasure against this problem, research and development are being carried out from various fields, and it is considered to be one of the most promising methods for separating and recovering $CO_2$ in the exhaust gas. One of the reasons for the low use of carbon dioxide is oxidized among the carbon compounds and is present in the most stable state. From the viewpoint of $CO_2$ emissions, $CO_2$ immobilization technology, which converts $CO_2$ into chemically useful compounds, is considered to be more important.

• YAKHAK HOEJI
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• v.49 no.6
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• pp.449-458
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• 2005

There have been rapid changes in the pharmaceutical environment after the separation of Dispensing and Prescribing practice. In the early stage of this system, outpatients had few options to choose their pharmacies due to various obstacles. Under these circumstances, this study on the defection tendency of long-term care patients was performed through the analysis of outpatients who quit visiting a pharmacy nearby general hospital. PowerBuilder ver 9.0 program was used to extract significant data, and SPSS package was employed for statistic analysis. 3,308 outpatients who visited a pharmacy nearby hospital for a month (in January, 2004) were studied. Patients' sex, age and location of residence, the class of medical insurance, the characteristic type of medication (powder, split form, medication for external use/injection), waiting time, disease (department) were considered as variable factors. It turned out that the patient revisit ratio was 80.8$\%$ and the patient defection ratio was 32.4$\%$. As was expected, those factors mentioned above influenced on the revisit and defection ratio considerably. In terms of patient factors, it proved that there was no relationship among sex, location of residence, the class of medical insurance and revisit (defection) ratio. Only age factor influenced the ratio; the older, the higher revisit ratio and the less defection ratio. In respect of dispensing factors, there were obvious relationships among the factors and the ratio: bill (money they had to pay individually), waiting time, number of medications, splitting of tablets, unit price of drug and revisit (defection) ratio showed significant relationship. The result of this study revealed an aspect of outpatients' behavior and it could be used as a reference for better patient service and customer relationship management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.378-383
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• 2004

Orthogonal Frequency Division Multiplexing (OFDM) transmits high-speed data by splitting the transmission bandwidth into a number of subcarriers. The bandwidth of each subcarrier is ensured to be smaller than the coherence bandwidth. This paper presents an OFDM system incorporated with the Carrier Interferometry (CI) codes to improve the performance by enhancing frequency diversity effect. The performances of CI-OFDM with multilevel modulations are investigated in highly dispersive fading channels. For the investigation of performance improvement of CI-OFDM, a simulator has been developed using a well-known SPW simulation platform. The simulation results show that the CI-OFDM provides both performance improvement and robustness against dispersive fading channel behavior. The performance of CI-OFBM with multilevel modulations demonstrates that CI-OFDM outperforms a traditional OFDM system, particularly in highly dispersive channels. With a relatively large delay spread of 151㎱ compared to the guard interval of 800㎱, CI-OFDM provides a BER of 10$^{-3}$ if sufficient signal power is present.

• Computers and Concrete
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• v.29 no.2
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• pp.107-115
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• 2022

With the improvements in computer technologies, utilization of image processing techniques has increased in many areas (such as medicine, defence industry, other industries etc.) Many different image processing techniques are used for surface analysis, detection of manufacturing defects, and determination of physical and mechanical characteristics of composite materials. In this study, cementitious composites were obtained by addition of Grounded Granulated Blast-Furnace Slag (GGBFS), Styrene Butadiene polymer (SBR), and Grounded Granulated Blast-Furnace Slag and Styrene Butadiene polymer together (GGBFS+SBR). Expanded Polystyrene (EPS) beads were added to these cementitious composites in different ratios (20%, 40% and 60%). The mechanical and physical characteristics of the composites were determined, and homogeneity indexes of the composites were determined by image processing techniques to determine EPS distribution forms in them. Physical and mechanical characteristics of the produced samples were obtained by applying consistency, density, water absorption, compressive strength (7 and 28 days), flexural strength (7 and 28 days) and tensile splitting strength (7 and 28 days) tests on them. Also, visual examination by using digital microscope, and image analysis by using image processing techniques with open source coded ImageJ program were performed. As a result of the study, it is determined that GGBFS and SBR addition strengthens the adhesion sites formed as it increases the adhesion power of the mixture and helps to get rid of the segregation problem caused by EPS. As a result of the image processing analysis it is demonstrated that GGBFS and SBR addition has positive contribution on homogeneity index.

• Journal of English Language & Literature
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• v.56 no.2
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• pp.187-217
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• 2010

By reading the main character, Rene Gallimard, in M. Butterfly as a spatial metaphor of America, this article examines how homogeneous American national identity of heterosexuality and white masculinity has been reinforced since the cold war and has constituted a crisis of hegemony with the decline of imperialism and how its pathological symptom is shown through the melancholic suicide of Gallimard. This article also argues how the feminine attributes implied in race, gender and sexuality in M. Butterfly are designated and allegorized as an impure, contaminated and ahistorical marker of national integrity in pthe social and material status of the heterosexual American white male. To develop my argument, I read M. Butterfly from a psychoanalytic point of view. Therefore I depend on Freud, Lacan, and Bhabha's psychoanalysis as the theoretical basis. In this paper, I also argue that the homogenized and fixed national identity is splitted and collapsed from within as shown in the Gallimard's melancholy and in the process of splitting the "Third Space" of hybrid subjects for the marginal and the emergent like Song Liling, a homosexual Asian man, can be built "from a space in-between." Therefore Hwang calls into questions conventions of fixed, essentialist identities through the shifting gender identities between Song and Gallimard in M. Butterfly and how identities in the plural are constructed variously in throughly historicized, politicized situations, and these constructions can be complicated by relations of power.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.106-113
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• 1987

The Alaska pollack longline operations, which consist of baiting, shooting, hauling and arrangement of hooks, are dependant on manual labour up to the present. The automation against this traditional way is necessary to eliminate the manual operations and to reduce crew. We have developed a prototype longline system suitable for Alaska pollack longline gear, which is composed of an automatic baiting machine, an automatic line hauler, a hook cleaner and storage rails. The automatic bailing machine driven by hydraulic power is precise baiting method controlled sequentially, and the automatic line hauler is to haul up the mainline by means of hydraulic power and at the same time to split every hook and to carry it onto storage rail automatically. A series functioning tests on shooting and hauling apparatus were carried out in the laboratory and at sea. The results obtained are as follows ; 1. As for the baiting machine, the exciting time of solenoid which operates a directional valve, bait feeding and cutting time, is shortened according to the increase of pressure, and also, after cutting the bait, the over-rotated angle of the blade increased in accordance with the increase of pressure. 2. The baiting efficiency is about $90\%$ when using sand lance (Hypoptychus dybowskii), and the most proper pressure of the hydraulic circuit in feeding and cutting the bait is between $13\;kgf/cm^2\;and\;20\;kgf/cm^2$. 3. The hook splitting rate of the automatic line hauler is about $95.5\%$ regardless of hauling speed and materials of snood. 4. The case of unseparating hook is appeared when the snood gets entangled or the hook is sticked in the mainline.

• Korean journal of communication and information
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• v.43
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• pp.314-358
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• 2008

This study examined how the meaning of news stories covering the split of national opinion was constructed in the media to represent social conflicts. To clarify the function of the term 'split of national opinion' as an ultimate term, this study examined the meaning of the term in the context of both text and society. Ten newspapers were included in the content analysis. The frequency of words used for the purpose of metaphor and equivalent in describing the split of national opinion was calculated to determine their meaning in the textual context. The frequency of incidents and subjects involved in allegedly causing the split of national opinion was calculated to determine their meaning in the social context. The results of this study are summarized as follows: First, the term 'split of national opinion' was coined by the newspapers as a metaphor of disease, disaster, and cost. The attitudes or the ways in which the split of national opinion was dealt with were generally negative and passive. Second, the term 'split of national opinion' was dealt with an equivalent status of such terms as national policy, national loss, societal problems, and ideology. Third, each newspaper reported that the split of national opinion had been caused by certain subjects, which indicates that each newspaper had its own position of viewing who was the key player in splitting the national opinion. The implication was also discussed that the use of the ultimate term would incur the unbalance of power between participants and the existing players, which would make individuals or groups who were involved in the social actions excluded and make the newspapers exercise the rhetorical power as news media.