• Korean Journal of Materials Research
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• v.21 no.3
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• pp.180-185
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• 2011

This study is aimed to increase the activity of cathodic catalysts for PEMFCs(Polymer Electrolyte Membrane Fuel Cells). we investigated the temperature effect of 20wt% Pt/C catalysts at five different temperatures. The catalysts were synthesized by using chemical reduction method. Before adding the formaldehyde as reducing agent, process was undergone for 2 hours at the room temperature (RT), $40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$ and $100^{\circ}C$, respectively. The performances of synthesize catalysts are compared. The electrochemical oxygen reduction reaction (ORR) was studied on 20wt% Pt/C catalysts by using a glassy carbon electrode through cyclic voltammetric curves (CV) in a 1M H2SO4 solution. The ORR specific activities of 20wt% Pt/C catalysts increased to give a relative ORR catalytic activity ordering of $80^{\circ}C$ > $100^{\circ}C$ > $60^{\circ}C$ > $40^{\circ}C$ > RT. Electrochemical active surface area (EAS) was calculated with cyclic voltammetry analysis. Prepared Pt/C (at $80^{\circ}C$, $100^{\circ}C$) catalysts has higher ESA than other catalysts. Physical characterization was made by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The TEM images of the carbon supported platinum electrocatalysts ($80^{\circ}C$, $100^{\circ}C$) showed homogenous particle distribution with particle size of about 2~3.5 nm. We found that a higher reaction temperature resulted in more uniform particle distribution than lower reaction temperature and then the XRD results showed that the crystalline structure of the synthesized catalysts are seen FCC structure.

• The KIPS Transactions:PartC
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• v.8C no.1
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• pp.88-96
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• 2001

Future mobile communication networks, which consist of ATM-based B-ISDN backbone networks and wireless ATM networks, will provide u user with broadband connection and QoS service. These network systems need the lossless handoff methods which support user mobility, satisfy ATM features such as ATM cell ordering and no ATM cell duplication and minimize buffer requirement for ATM cell buffering. In this paper we suggest a multicast-based handoff method to supp$\alpha$t lossless connection as well as to minimize buffer overhead. It establishes a dynamic multicast connection between source terminal and wireless member AP (access point)s. When the mobile terminal receives data packet correctly, it notifies the positive acknowledgement of the packet to all member APs. And member APs then release the MT related temporary buffer space for MT's future movement. Therefore member APs can eliminate unnecessary buffer usage and manage the buffer space efficiently. Analysis result shows that our handoff method has better performance in buffer requirement for lossless and seamless connection services over VCT (virtual connection tree) method and other dynamic multicast-based handoff methods.

• Journal of the Korea Computer Industry Society
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• v.3 no.5
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• pp.575-584
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• 2002

On-line handwritten character recognition be achieved successful results since effectively neural networks divided the letter which is the time ordering of strokes and stroke position. But off-line handwritten character recognition is in difficulty of incomplete preprocessing because has not information of motion or time and has frequently overlap of the letter and many noise occurrence. consequently off-line handwritten character recognition needs study of various methods. This paper apply watershed algorithm to preprocessing for off-line handwritten hangul character recognition. This paper presents effective method in four steps in watershed algorithm as consider execution time of watershed algorithm and quality of result image. As apply watershed algorithm with effective structure to preprocessing, can get to the good result of image enhancement and binarization. In this experiment, this paper is estimate the previous method with this paper method for execution time and quality in image. Average execution time on the previous method is 2.16 second and Average execution time on this paper method is 1.72 second. While this paper method is remove noise effectively with overlap stroke, the previous method does not seem to be remove noise effectively with overlap stroke.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.1
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• pp.10-18
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• 2007

Mobile communication devices such as PDAs, cellular phones, etc., need to perform several kinds of computation-intensive functions including H.264 encoding/decoding and 3D graphics processing. In this paper, new reconfigurable architecture is described, which can perform either motion estimation for H.264 or rendering for 3D graphics. The proposed motion estimation techniques use new efficient SAD computation ordering, DAU, and FDVS algorithms. The new approach can reduce the computation by 70% on the average than that of JM 8.2, without affecting the quality. In 3D rendering, midline traversal algorithm is used for parallel processing to increase throughput. Memories are partitioned into 8 blocks so that 2.4Mbits (47%) of memory is shared and selective power shutdown is possible during motion estimation and 3D graphics rendering. Processing elements are also shared to further reduce the chip area by 7%.

• Journal of the Korean Geographical Society
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• v.33 no.1
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• pp.109-122
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• 1998

The purpose of this study is to develop value instruction program which can deal with geographic value problem(GVP) in geographic education. This program is organized into seven stages: identification of GVP(reading of content of GVP, and categorization and description of action which involved in content), analysis of GVP(comparison and analysis of GVP, and ordering of value positions), decision making, justification of decision making and actualization. The processes of decision making and their related activities are emphasized in this program. In experimental classroom, it took effects to providing subjective experiences with students, developing decision making ability, and giving responsibility of decision making. Therefore this study suggests that this program helps students to improve their social participation ability as the democratic citizenship.

• Journal of Arbitration Studies
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• v.21 no.1
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• pp.87-107
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• 2011

There are two methods to resolve conflicts related to constructions which are through lawsuits and ADR (Alternative Dispute Resolution) just like any other conflicts. Along with the special characteristics pertaining to the conflicts related to constructions, the advantages that ADR is in possession of such as its cost, duration and professionalism, resolving conflicts through ADR has been considered to be more logical than any other options recently. In Korea's case at present, the resolution of conflicts regarding constructions through ADR is mostly dependent on administrative mediation or through arbitration. However, in the case of the administrative mediation, its usage rate is very low due to problems caused by problems in its running and effectiveness. In the case of arbitration, the services of the Korean Commercial Arbitration Board is comparatively used more but because of the fact that arbitration relies on a single trial system and the fact that its executive powers while having the same effectiveness as the final ruling does not get acknowledged leads to the phenomena of avoiding its usage. In addition, in relation to the selective arbitration clause, the problem of effectiveness of the arbitrative agreement is becoming a hindrance to the activation and promotion of the arbitration process. Furthermore, in the case where the ordering body is the government, the public servant involved in the case avoiding the arbitration process because of concerns of being penalized by the internal and external audit within the institution is becoming a problem as well. These problems are not only limited to conflicts regarding constructions and there needs to be actions taken to promote the activation of ADR by enacting a basic law. The more important issue at hand however is offering a resolution measure that would be the most appropriate for users and this could probably be done only through actions such as implementing the American partnering system or the dispute adjudication board system so that they can supervise the resolution of conflicts through mediation, arbitration, and assistance as well as offering consultations regarding conflicts related to constructions.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.345-352
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• 2012

Purpose: The age-hardening mechanism of an Au-Ag-Cu-Pt-Zn alloy for crown and bridge fabrication was investigated by means of hardness test, X-ray diffraction study and field emission scanning electron microscopic observation. Methods: Before hardness testing, the specimens were solution treated and then were rapidly quenched into ice brine, and were subsequently aged isothermally at $400-450^{\circ}C$ for various periods of time in a molten salt bath and then quenched into ice brain. Hardness measurements were made using a Vickers microhardness tester. The specimens were examined at 15 kV using a field emission scanning electron microscope. Results: By the isothermal aging of the solution-treated specimen at $450^{\circ}C$, the hardness increased rapidly in the early stage of aging process and reached a maximum hardness value. After that, the hardness decreased slowly with prolonged aging. However, the relatively high hardness value was obtained even with 20,000 min aging. By aging the solution-treated specimen, the f.c.c. Au-Ag-rich ${\alpha}_0$ phase was transformed into the Au-Ag-rich ${\alpha}_1$ phase and the AuCu I ordered phase. Conclusion: The hardness increase in the early stage of aging process was attributed to the formation of lattice strains by the precipitation of the Cu-rich phase and then subsequent ordering into the AuCu I-type phase. The decrease in hardness in the later stage of aging process was due to the release of coherency strains by the coarsening of tweed structure in the grain interior and by the growth and coarsening of the lamellar structure in the grain boundary. The increase of inter-lamellar space contributed slightly to the softening compared to the growth of lamellar structure toward the grain interior.

• Culinary science and hospitality research
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• v.16 no.3
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• pp.94-113
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• 2010

Despite a number of previous studies about cultural tourism festivals, studies on food menus in the cultural tourism festival setting have often been neglected. Considering the importance of food menus, identifying major selection attributes that satisfy visitors in a festival setting is vital. Using conjoint analysis, this study demonstrated that price was the most influential selection attributes to attract visitors. The time required between ordering and receiving food was found to be the second important selection attribute, followed by menu and place. Cluster analysis identified two distinct segments that take different sets of elements into account when making their selection decision. Conjoint simulation estimated the most preferred foodservice form in cultural tourism festivals setting would have 21.18% potential market share. The implications gained from this study provided an important starting point for determining key selection attributes in establishing strategies to enhance visitors' level of satisfaction.

• Journal of Korea Port Economic Association
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• v.31 no.3
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• pp.1-14
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• 2015

This study utilizes Monte Carlo simulation to forecast the time charter rate of vessels, the three-month Libor interest rate, and the ship demolition price, to mitigate future uncertainties involving these factors. The simulation was performed 10,000 times to obtain an exact result. For the empirical analysis - based on considerations in ordering ships in 2010-a comparison between the Monte Carlo simulation-based stochastic discounted cash flow (DCF) method and traditional DCF methods was made. The analysis revealed that the net present value obtained through Monte Carlo simulation was lower than that obtained via regular DCF methods, alerting the owners to risks and preventing them from placing injudicious orders for ships. This research has implications in reducing the uncertainties that future shipping markets face, through the use of a stochastic DCF approach with relevant variables and probability methods.

• Journal of Digital Convergence
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• v.13 no.3
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• pp.11-18
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• 2015

After entering a convergence era, South Korea Government has enacted and announced the Standard Contract on the e-Learning Content Development Project, a year and eight months has passed. Nevertheless, there has been continued still the unjust and unreasonable contract practices issues raised by project owner in the e-Learning industry. This study investigated application status of the Standard Contract via FGI and questionnaires and suggested its improvement alternative. This study analyzed that the Standard Contract has not taken root at all in ordering of the e-Learning content development project and not reaped the effect. This study presented alternatives such as mandatory application of the Standard Contract, education and outreach, introduction of the monitoring system, certification system implementation, granting of additional points in the evaluation of agencies and CEO and etc. to that standard contract is settled as the government's intentions and objectives in the e-Learning industry field.