• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.1001-1012
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• 2018

Regarding the small- and medium-sized enterprises in Korea that manufacture the railway vehicle parts, there are over 250 related companies. And they have been surviving in the form of producing and delivering the parts of the railway vehicles by importing the technologies and the products of the foreign countries rather than possessing their own technological abilities. Due to this, regarding the industry of the core components of the railroads, the dependence on the overseas has been high. As such, although, for supporting the small- and medium-sized enterprises that manufacture the railway vehicle parts, the government has been strengthening the diverse policy supports, it is a fact that the effectiveness of the support is not high. And, in order to effectively support these, there is a need to understand clearly and definitely what the important promotion factors are in the process of the technology commercialization. Accordingly, through the precedent researches regarding the factors that promote the technology commercializations of the small- and medium-sized enterprises that manufacture the railway vehicle parts, this research had extracted 10 main items. And the level of the importance of these indices was analyzed by using the AHP (Analytic Hierarchy Process). As a result of the AHP analysis, the factors within a corporation appeared to be the most important factor. And, as for the lower-ranking item, the commercialization capability was analyzed to be the most important item. It is highly expected that the contents and the results of this research will be usefully used when formulating the planning of the support program and the support policy for the technology commercializations by the public research organizations and the railroad management organization, which is an organization that supports the small- and medium-sized enterprises that manufacture the railway vehicle parts.

• International Journal of Railway
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• v.5 no.4
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• pp.152-155
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• 2012

The essential element of brake device for railway vehicle is in demand for higher performance along side the trend of railway vehicle size and speed. Essential element of brake device for high speed train is composed of metallic friction material and brake disc. Thus, brake distance, duration and brake stability shall be determined due to friction materials and friction characteristics. Also friction characteristics are influenced by metallic friction material's properties of matter, manufacturing process and component parts. Various materials and configurations of metallic friction materials are currently being implemented to railway vehicles, For this reason study of friction characteristics in accordance with materials is necessary, but study of these important elements are not actively being accomplished. Therefore, in this study, wished to study the graphite's friction characteristic comprised in friction material in accordance with particle size and amount of volume through lab-scale test.

• Journal of the Korea Society for Simulation
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• v.31 no.3
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• pp.23-34
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• 2022

Due to the characteristics of the railway system, a fleet consists of multiple railway vehicles, and a project contract is made by supplying multiple fleets to the customer. If the project fails to meet the due date, the manufacturer must compensate for the delay to the customer. In this paper, we analyze the operation strategies of the railway vehicle manufacturing factory using simulation, in which the layout adopts the concept of the flow lines, and when shortages of parts are considered. If there is a shortage of parts, the subsequent assembly process cannot proceed due to the nature of the assembly process. Thus, in order to overcome this problem, three strategies for performing assembly work are presented when the events of shortages are occurred. We also compare the strategies with respect to reduce the total cost which includes labor costs and compensation costs for delay.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.802-809
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• 2017

3D printing technology is a manufacturing process for products, in which polymer and metal materials are laminated to form structures. It is advantageous for manufacturing parts requiring a high degree of design freedom and functionality. In addition, it would be a suitable technology for the production of parts for railway vehicles in the future, due to the need to produce parts in small quantities. In order to fully exploit the advantages of 3D printing technology, it is necessary to consider the process characteristics during the design of the product. In this study, the redesign and manufacturing technology of the product considering the performance and process conditions were studied for the heat exchanger in the air compressor of railway vehicles, as a trial application of the 3D printing technique. First of all, the design concept to improve the performance of the heat exchanger was defined, and the design range was specified to satisfy the performance of the present heat exchanger analyzed experimentally. Then, the detailed design was revised considering the characteristics of the metal 3D printing process, such as the manufacturing restrictions and production time. Based on the final design, the product was fabricated by the 3D printing process using aluminum material, and it was confirmed that the dimensional accuracy was satisfied. The weight of the final product was reduced by 41% compared with the existing products. The results of this study will make it possible to develop an efficient product design process for 3D printing technology.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.657-665
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• 2019

The domestic railway parts and equipment manufacturing industry is mainly focused on SMEs, and the majority of them are suffering from profitability because they cannot build economies of scale. Besides, they have survived in the form of importing technology products from overseas advanced countries and delivering them to domestic railway operators rather than having in-house technology. Therefore it is necessary to study whether the problems of the current railway industry can be identified and improved and at the same time, whether the government's railway industry development policy is properly reflected. literature studies related to technology commercialization, and conduct surveys of AHP questionnaires on the experts of the manufacturing industry of SMEs, academics / research institutes of the railway industry. After that, the Level 3 activation method AHP analysis was additionally performed on the important factors of Level 2 that have the highest importance and priority in Level 1. As a result of the AHP analysis, 'Technical Connectivity' was the most important method in the technical factor, and SME experts and academic and research institute experts were highly evaluated for 'commercialization ability' Competence in terms of importance. As for external support factors, it was analyzed that SME experts "support for manpower development" was important, while the other two group experts research and development support was important. In this study, the priority of the government support and policy priorities are suggested according to the capabilities of the railway manufacturing SMEs before the future R&D support.

• Composites Research
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• v.36 no.3
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• pp.186-192
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• 2023

Recently, in the field of railway vehicles, interest in the use of composite materials for weight reduction and transportation efficiency is increasing. Accordingly, research and commercialization development to apply composite materials to various vehicle parts are being actively conducted, and evaluation is conducted centering on post-measurement such as mechanical performance evaluation of finished products to verify quality when composite materials are applied. However, the analysis of heat and stress generated during the molding process of composite materials, which are factors that greatly affect manufacturing quality, is insufficient. Therefore, in this study, in order to verify the molding quality of composite parts for railway vehicles, the molding quality analysis was conducted for the two types of composite interior panels (laminate panel and sandwich panel) that are most actively used. To this end, temperature and strain changes were monitored during the molding process by using an FBG fiber optic sensor, which is easy to apply to the inside of the composite, and the residual strain value generated after molding was completed was measured. As a result, it was confirmed that overheating and excessive residual stress did not occur, thereby verifying the excellent molding quality of the composite interior panel for railway vehicles.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.2
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• pp.331-336
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• 2018

In this paper, the life cycle cost of the auxiliary power unit in the conventional 8200 series electric locomotive is evaluated and an effective life cycle cost reduction method is sought. For this, a life cycle cost evaluation model was proposed using IEC 60300-3-3 standard. As a result of analysis, material cost which accounted for a large percentage of preventive maintenance cost, accounted for 64% of total cost, and breakdown maintenance cost was as high as 27%. Except for the cost of preventive maintenance, the breakdown maintenance cost ratio was the highest. In order to reduce the LCC of the auxiliary power unit(APU) of the 8200 series in the future, it is necessary to reduce the material cost in case of development and to secure the high reliability according to the parts manufacturing so as to minimize the maintenance cost.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.270-276
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• 2020

3D printing is an additive manufacturing technology that can produce complex shapes in a single process for a range of materials, such as polymers, ceramics, and metals. Recent 3D printing technology has developed to a level that enables the mass-production through an improvement of the printing speed and the continuous development of applicable materials. In this study, 3D printing technology using a laser was applied to manufacture a heat exchanger for an air compressor in a railway vehicle. First, the optimal design of the heat exchanger was carried out by focusing on weight reduction and compactness as a shape suitable for 3D printing. Based on the design derived, heat exchanger prototypes were made of AlSi10Mg alloy material by applying the SLM technique. Moreover, the manufactured prototypes were attached to an existing air compressor, and the heat exchange performance of the compressed air was tested. The test results of the 3D printed prototypes showed a heat exchange performance of approximately 80% and 85% at low and high-pressure, respectively, compared to the existing heat exchanger. From the 𝓔-NTU method results with an external cooling air condition similar to that of the existing heat exchanger, the calculated heat transfer amount of 3D printed parts showed similar performance compared to the existing heat exchanger. As a result, the 3D printed heat exchanger is lightweight with good performance.