• 열처리공학회지
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• 제11권4호
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• pp.315-323
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• 1998

This study has been conducted to develope the combined heat treating technique of gas carburising - gas nitriding and gas carburising to improve the hot working performance of type H3 hot work tool steel. Case depth and carbrides coarsening were increased with increasing carburising temperature and time, respectively. Surface hardness showed decreasing tendency with increasing 2nd tempering temperature after carburising treatment. After carburising, 2nd treatment at 500 to 600 was chosen according to a hardness demand of final product. High temperature tempering resistance showed more excellent quality during such carburising-nitriding or carburising than complex treatment as after conventional hardening.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1037-1038
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• 2006

The increasing demand of PM parts for automobile and aerospace applications has caused a strong development of the aluminium based metal matrix composites (MMCs).Aluminium alloys are one of most widely used materials as matrix in MMCs, both in research and development as well as in industrial applications. In the present work, the influence of the ceramic reinforcement addition to a 2xxx series aluminium alloy is studied. Several percentages of TiCN have been added to the Al-Cu alloy using PM techniques, in order to analyze its influence on the liquid phase sintering process and on the final properties of the material.

• 한국CDE학회논문집
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• 제14권3호
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• pp.197-206
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• 2009

In a finite element analysis of the metal forming processes having large plastic deformation, largely distorted elements are unstable and hence they influence upon the result toward negative way so that adaptive remeshing is required to avoid a failure in the numerical computation. Therefore automatic mesh generation and regeneration is very important to avoid a numerical failure in a finite element analysis. In case of generating quadrilateral mesh, the automation is more difficult than that of triangular mesh because of its geometric complexity. However its demand is very high due to the precision of analysis. Thus, in this study, an automatic quadrilateral mesh generation and regeneration method using grid-based approach is developed. The developed method contains decision of grid size to generate initial mesh inside a two dimensional domain, classification of boundary angles and inner boundary nodes to improve element qualities in case of concave domains, and boundary projection to construct the final mesh.

• 대한지역사회영양학회지
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• 제8권5호
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• pp.763-769
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• 2003

The food-service industry in Korea has experienced remarkable growth during the past few decades. The objectives of this study were to analyze the influence of the food-service industry upon the national economy by using an input-output analysis and to find the industrial position of the food service industry. This paper analysed the economic effect of the food-service industry using 168 items arranged in a transaction table based on producer's prices in the 1995 input-output tables. The results of this study showed that the food-service industry had a major influence on the national economy of Korea. Based on the calculation of the following five coefficients; Korea's production inducement coefficient ranked as 50, its import inducement coefficient ranked as 28, its value added inducement coefficient ranked as 32, its worker inducement coefficient ranked as 2 and its employee inducement coefficient per final demand ranked as 5 in a total of 168 industries.

• 산업경영시스템학회지
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• 제5권6호
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• pp.55-62
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• 1982

Mechanical characteristics of nodular graphite cast iron has found to tan higher utilization to the gray cast iron. So, Nodular graphite cast iron is used as a basic material in mechanical industry. Great demand of Nodular graphite cast iron is expected to increase due to the sharp development in mechanical and automobile industry. Therefore, Nodular graphite cast iron requires not only good quality product but experienced skills in manufacturing process. But there exist a lot of difficulties to manufacture nodular graphite cast iron than gray cast iron in manufacturing process. In this study, the following topics are studied for good quality product of nodular graphite cast iron. $\circled1$ Activities of managerial staff. $\circled2$ Qualite control method in manufacturing process. $\circled3$ Manufacturing process system. As a result of the study, a intensive Quality control activities should be applied and reinforced at each stage of manufacturing process rather that at the last stage of final product.

• Journal of Electrical Engineering and Technology
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• 제5권1호
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• pp.45-53
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• 2010

This paper presents an improved parallel particle swarm optimization approach (IPPSO) based decomposed network for economic power dispatch with discontinuous fuel cost functions. The range of partial power demand corresponding to the partial output powers near the global optimal solution is determined by a flexible decomposed network strategy and then the final optimal solution is obtained by parallel Particle Swarm Optimization. The proposed approach tested on 6 generating units with smooth cost function, and to 26-bus (6 generating units) with consideration of prohibited zone effect, the simulation results compared with recent global optimization methods (Bee-OPF, GA, MTS, SA, PSO). From the different case studies, it is observed that the proposed approach provides qualitative solution with less computational time compared to various methods available in the literature survey.

• Advances in Computational Design
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• 제5권1호
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• pp.13-34
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• 2020

As small size and complex metal machining components demand increases, cutting processes in microscale become necessary. Ball-end milling is a commonly used finishing process, which nowadays can be applied in the microscale size. Surface quality and dimensional accuracy are two basic parameters that affect small size components in their assembly and functionality. Thus, good quality can be achieved by optimizing the cutting conditions of the procedure. This study presents a 3D simulation model of ball-end milling in microscale developed in a commercial CAD software and its optical and computing results. These carried out results are resumed to surface topomorphy, surface roughness, chip geometry and cutting forces calculations that arising during the cutting process. A great number of simulations were performed in a milling machine centre, applying the discretized kinematics of the procedure and the final results were compared with measurements of Al7075-T651 experiments.

• Current Optics and Photonics
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• 제3권3호
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• pp.227-235
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• 2019

With slimmer, lighter and all-reflective imaging systems in high demand for consumer and military applications, coaxially folded optical image systems are widely considered because they can extend focal length and reduce track length. Most of these systems consist of multiple surfaces, and these surfaces are machined on one element or grouping processing on two elements. In this paper, we report and first experimentally demonstrate an all-aluminum all-reflective optical system which consists of two optical elements, with two high order aspherical surfaces in each element. The coaxially folded system is designed with Seidel aberration theory and advanced optimization with Zemax. The system is made of all-aluminum material processing by single point diamond turning (SPDT). On this basis, we completed the system integration and performed an imaging experiment. The final system has the advantages of short track length and long focal length and broad application prospects in the micro-unmanned aerial vehicle field.

• 전자통신동향분석
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• 제36권4호
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• pp.110-117
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• 2021

The development of core technologies in the 4th Industrial Revolution, such as artificial intelligence, big data, and the intelligent Internet of Things, promote digital transformation and intelligence of the manufacturing industry. To realize them, there is an increasing demand for materials, components, and equipment needed for final goods. In particular, the expansion of global value chain instability due to changes in the external environment, such as the U.S.-China trade dispute, Japan's export regulations, and Covid-19 pandemic, increases the importance of strengthening the materials, components, and equipment industry in the global market. Thus, this study presents a strategic direction for securing global industrial competitiveness of materials, components, and equipment using Michael Porter's diamond model approach.

• East Asian Economic Review
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• 제24권4호
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• pp.389-416
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• 2020

This paper provides empirical evidence on the reorganization of GVCs in East Asia, highlighting that structural trends explain a decrease in the fragmentation of production after 2011 but that it is not the result of rising trade costs along the value chain. Using harmonized inter-country input-output tables, the paper first analyzes the global import intensity of production to document changes in the structure of GVCs. It then calculates theory-consistent bilateral trade costs for intermediate and final products using an approach derived from the gravity literature and introduces a new index of cumulative trade costs along the value chain. These data are used to discuss whether the decrease in global imports is the consequence of shifts in demand, efficiency-enhancing strategies of firms or rising trade costs. Between 2011 and 2016, cumulative trade costs have decreased in East Asian GVCs. However, as COVID-19 is likely to intensify trade and investment uncertainties, trade costs could increase in the future. Policies aimed at reducing uncertainties and preserving the gains from trade and investment liberalization will be key in this new environment.