• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.219-222
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• 2005

The temperature difference between die and workpiece has frequently caused various surface defects. The non-homogeneous temperature distribution of forged part should be analyzed to prevent the generation of various defects related with the temperature. The surface temperatures were mainly affected by the coefficient of thermal contact conductance. The precise coefficient is necessary to predict accurately the temperature changes of die and workpiece. The experiment is preformed to measure the temperature distribution of die and workpiece in closed die upsetting. And then, the coefficient is classified into function of pressure and confirmed by the comparison between experiments and FE analyses using the other model. The FE analysis to predict the temperature distribution is performed by commercial software $DEFORM-3D^{TM}$. However, it might be impossible to measure directly the temperature distribution of forged part. Therefore, the comparisons between measured temperature and predicted values are performed with the hardness of Al6061-forged part.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.517-523
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• 2021

In this study, in the selection of materials for the elements of a small plant, those with high resistance to corrosion are selected and the material properties of coatings for corrosion prevention are evaluated. In addition, corrosion characteristics and material analysis were performed on the welded part, and the hardness characteristics of the welded part, heat-affected part, and the base metal were evaluated. In the case of the post-weld-heat-treated(PWHT) specimen, the corrosion resistance of STS 316 was lower than that of the specimen without the PWHT due to the formation of intergranular carbide. As a result of evaluating the distribution of the hardness of the weld before and after the PWHT, the hardness of the specimen after the PWHT increased by about 20 Hv. As a result of the corrosion test on the welded specimen, the weight loss tended to increase as the time increased. In the case of the PWHT specimen, the corrosion resistance tended to be significantly lower than that of the specimen without PWHT due to the formation of intergranular carbide.

• Journal of Advanced Engineering and Technology
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• v.11 no.4
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• pp.267-271
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• 2018

A high-frequency therapy device with improved output by modifying a high-frequency stimulator was fabricated. The details of the design include generating part design, high-frequency transformer design, large output FET installation, DC voltage input part design and gate input driver design. Based on the real test using the pork meat, the temperature distributions according to the current electric transfer method, penetration depth, electrode diameter size were measured. In the CET method, the penetration depth was 0.5 cm and in the RET method, the penetration depth was 20 cm or more. In addition, it was confirmed that the temperature rise according to the penetration depth in the RET system was substantially constant, and the temperature rise was remarkable as the electrode diameter was small. As a result, it has been confirmed that the high frequency therapy device is highly affected by various conditions of the electrode.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1997.10a
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• pp.90-93
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• 1997

This paper presents a new methodology for business process simulation modeling and analysis based on role-oriented modeling concept. The proposed methodology allows for tracking people and their roles affected by reengineering the business process. It enables one to analyze and evaluate not only work flow, but roles that are part of the flow. A simulator based on this methodology is developed to systematically construct simulation models and conduct simulations easily and efficiently.

• Korean Journal of Computational Design and Engineering
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• v.10 no.1
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• pp.17-26
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• 2005

In-line skate generally consists of four major parts: boot, frame, bearing and wheel, and the most important part among those for necessary functionality is the frame. It is the most expensive, and it also makes a decisive role in practical race skating. The functional behavior of a frame is greatly affected by external dynamic forces as well as the static weight of a skater. We are proposing a new inline speed-skating frame design that has been improved in structural strength and weight for providing optimum speed in $20\sim40km$ marathon skating.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.273-279
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• 2014

Hexagonal Ba-ferrites are widely suggested as materials for small antennas. In this paper, the sintering behavior and magneto-electric properties of $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ ($0.1{\leq}x{\leq}0.5$) ceramics were investigated for small antenna application. All samples of $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ ceramics were prepared by the solid-state reaction method and sintered at $1250^{\circ}C$. From the XRD patterns of the sintered $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ceramics, the Z-type phases were found to be the main phases. The real part of permittivity and permeability of the $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ceramics decreased with frequency. On the other hand, loss tangents of permittivity and permeability tended to behave opposite to real part of permittivity and permeability. The real part of permeability was affected by Mn additions. The real part of permittivity, the loss tangent of permittivity and the real part of permeability, the loss tangent of permeability of $Ba_3Co_{0.2}Mn_{0.8}Fe_{24}O_{41}$ ceramics were 19.774, 0.176 and 15.183, 0.073, respectively, at 510 MHz. In order to investigate the effect of magneto-dielectric ceramics on antenna, PIFA (Planar Inverted F Antenna) was simulated with CST (Computer Simulation Technology). The operating frequency of antenna was decreased without considerable change of bandwidth by using the $Ba_3Co_{0.2}Mn_{0.8}Fe_{24}O_{41}$ ceramics as the carrier.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.78-80
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• 2014

Silicone structural glazing (SSG) is a method utilizing a silicone adhesive to attach glass, metal, or other panel material to the structure of a building. Windload and other impact loads on the facade are transferred from the glass or panel through the silicone structural sealant to the systems' framework. Silicone structural glazing systems are currently a very common method of glazing throughout the world. Locally, structural silicone glazing has become very common to achieve aesthetically pleasing and high utilization of small land for both residential and commercial building. Although structural silicone glazing has been utilized for approximately thirty years in Korea, the understanding of its technology was low and limited. Consequently, Korean projects experienced many quality issues during assembly and construction, even in very recently finished buildings. Adhesion loss and water infiltration occurred on more than one project, and the time and cost to repair these issues were substantial. In general, there are two kinds of structural silicones depending on fabrication methods. 1part structural silicone is for site glazing system and 2part structural silicone is for unitized factory glazing system. In this paper, 2part structural silicone which is very common for factory fabricating curtainwall systems was evaluated with regards to various mixing ratio. Since the structural performance of 2part sealant can be affected by mixing ratios, some extra ranges of recommended mixing ratio were evaluated to see any performance differences. Besides on cure profile, comparative evaluations for mechanical properties and adhesion develop on common building substrates were conducted.

• Ocean and Polar Research
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• v.44 no.2
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• pp.127-137
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• 2022

This study examined the growth pattern and environmental factors affecting the growth of the halophyte, Suaeda japonica, which is prevalent on tidal flats in the west coast of Korea in order to calculate annual carbon production. Quantitative sampling was conducted every month for three years from 2018 to 2020 on salt marshes located on the southern coast of Ganghwa Island. In terms of annual density affected by the germination rate at first period, especially when air temperature for winter time was constantly below 0℃ for long periods of time, germination decreased and precipitation in summer also exerted an influence. In terms of annual growth with regard to length, the part below the ground grew rapidly in the beginning after budding, while the part above ground grew at a relatively steady rate at all times. With regard to biomass, the part below the ground also increased from April in a manner similar to length growth, but decreased drastically from September with leaves falling off and water loss occurring. The part above ground showed a rapid increase from the beginning of the rainy season. Size-frequency distribution revealed broader patterns after the rainy season as individual growth varied, but from September, it stopped at all year. High growth rates were recorded in the initial phase of growth after budding and growth was rapid, but growth declined in summer when biomass increased. The annual mean production based on growth rate was calculated at 352 gDWt/m²/yr, and the highest production was 519 gDWt/m²/yr in 2018, but it has decreased since 2019. Annual carbon production was at calculated 143.41 gC/m²/yr for Suaeda japonica in the vicinity of the southern coast of Ganghwa Island.

• Korean Journal of Environmental Biology
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• v.34 no.1
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• pp.30-36
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• 2016

We investigated the diversity pattern of spring moths across two regions of South Korea, Yongin city (middle part) and Muan gun (southern part) and the effects of climatic variables on moth species richness and abundance. Moths were weekly collected using UV light trap in April from 2013 to 2015. Climatic factors included growth degree day with base temperature 8 (GDD8), average temperature, precipitation, duration of sunshine, wind speed, and snow cover. The climatic effects on moth species richness and abundance were analyzed by short (0~3 weeks before collecting) and long (4~12 weeks before collecting) time periods, respectively. The diversity of spring moths showed the similar pattern of species composition at family level. However the dominant family differed depending on the region: Geometridae at middle part and Noctuidae at southern part. In addition the dominant species of Noctuidae occurred early in April and that of Geometridae moths occurred later in April. Three short-term climatic factors, GDD8, duration of sunshine, and precipitation one week before collecting were significant on moth species richness and abundance, while only one long-term climatic factor, temperature four weeks before collecting was significantly affected on moth species richness. We found that both Geometridae and Noctuidae were dominant in spring moth fauna across South Korea and they were different in the dominance and flying time in April. The occurrences of spring moths were largely affected by warmness and precipitation. The current global warming could affect the occurrence of spring moths and this should be monitored consistently.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.5
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• pp.1026-1036
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• 2014

The purpose of this research is to find the impact of multicultural awareness of pre-service secondary teachers on multicultural efficacy. Specific content of the study for achieving this purpose is as follows: First, the correlation between multicultural awareness of pre-service secondary teachers and multicultural efficacy was analyzed. Second, the effect relation between multicultural awareness of pre-service secondary teachers and multicultural efficacy was examined. As part of quantitative research, the method of study was a survey targeting 234 pre-service Secondary teachers who were sophomores, juniors and seniors at D University, P University and S University located in Busan. The study results earned from this process are as below: First, statistically significantly high positive correlation existed between multicultural awareness of pre-service secondary teachers and multicultural efficacy. The areas of acceptance, openness and respect, which are the sub-scale of multicultural awareness of pre-service secondary teachers, showed high positive correlations with all sub-scale of multicultural efficacy including general efficacy, efficacy in instructional function, efficacy in caring perspectives and efficacy in helping multicultural families. Second, the sub-scale of multicultural awareness that significantly affected general efficacy in the sub-scale of multicultural efficacy of pre-service secondary teachers was acceptance and respect. The sub-scale of multicultural awareness that significantly affected efficacy in instructional function was acceptance. The sub-scale of multicultural awareness that significantly affected efficacy in caring perspectives was acceptance and respect. The sub-scale of multicultural awareness that significantly affected efficacy in helping multicultural families was respect. It showed that openness in the sub-scale of multicultural awareness did not affect multicultural efficacy much.