• 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.

• 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.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.11 no.17
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• pp.25-37
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• 1988

Joint inventory 방법을 다룬 기존의 연구는 생산비용이 일정하다는 조건만을 고려하였다. 본 논문은 기존의 연구에다 새로운 변수(learning curve ratio and learning retension)를 제조업자 측면에서 고려하여 보다 확장된 모델을 다룬다. Joint inventory 모델은 첫째 단일구매자와 둘째 학습곡선비율과 learning retention의 정도에 있어서 그 범위를 결합시키는데 이용되기 위해 개발되어 졌다. 구매자와 제조업자를 위한 로트 사이즈를 결정하기 위하여 증분비용접근방법 (Incremental Cost Approach, ICA)을 쓴다. 총결합비용은 기존모델보다 현저하게 적은데 그 이유는 학습과 learning retention 효과로 인한 제조업자의 생산비 절감과 재고유지 비용의 감소 때문이다. 학습과 learning retention이 현격한 경우, 총결합비용은 제조업자와 구매자의 개별적인 최적정책에서의 비용합(합)보다 적다. 소개된 모델의 효과를 보이기 위해 수치예제를 이용하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.43.2-43.2
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• 2009

Al-Mg 알루미늄 합금은 강도가 높고 성형성이 우수하여 수송기기 경량화용 소재로서 사용량이 증가하고 있다. 특히고강도 특성을 보이는 Al-Mg-Mn합금은 자동차, 선박및 철도차량등의 형재 및 판재로 그 사용량이 증가하고 있다. 또한 결정립을 미세화 시킨 Al-Mg-Mn합금판재의 경우에는 온간성형으로 복잡한 형상의 판재부품제조에 사용되고 있다. 연속주조공정인 Twin roll strip casting(TRC)은용탕으로부터 직접 판재를 생산할 수 있는 공정으로 주로 순알루미늄계열의 판재 생산에 사용되고 있으나 최근에는 고강도 판재의 저비용 생산을 위하여 고합금계 판재에 적용하는 연구가 수행되고 있다. 합금량이 높은 고강도Al-Mg계 합금의 TRC 주조시 고액공존구간이 커서 더욱 정밀한 공정제어가 필요하다. 또한 기존의 슬라브주조방식보다 높은 냉각속도로 주조가 가능하기 때문에 결정립 및 정출상의 미세화공정으로 응용되기도한다. 본 연구에서는 TRC공정을 기초로 주조시 열간 압연의효과를 동시에 부여하는 용탕직접압연공정을 개발하였으며 상용 고강도 알루미늄 합금인 5083합금 판재를제조하였다. 또한 기존 Al-Mg 합금에 Mn을 첨가하여 용탕직접압연함으로서 정출상의 크기 및 밀도를 제어하여 강도가 우수한 Al-Mg-Mn 합금판재를 제조하는 기술을 개발하였다. 용탕직접압연된 Al-Mg-Mn계 합금의 경우에 주조시 높은 냉각속도로 인하여 결정립이 미세하고 Al6Mn과 같은 미세한 정출상이 다량 형성되었으며, 최종압연 및 열처리에 의하여 높은 강도를 갖는 고강도 알루미늄 합금 판재의 제조가 가능하였다.

• 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.

• Computational Structural Engineering
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• v.5 no.3
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• pp.97-103
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• 1992

Since many design problems in the railroad, aerospace and machine structures involve considerations of the effect of cyclic loading, manufacturing and quality control processes much fully account for fatigue of critical components. Due to the sensitivity of the Paris law, it is very important to calculate .DELTA.K numerically to minimize the error of predicted fatigue life in cycles. However, it is shown that the p-version of FEM based on LEFM analysis is far better suited for computing the stress intensity factors than the conventional h-version. To demonstrate the proficiency of the proposed scheme, the welded T-joint with crack problems of box car body bolster assembly and a crack problem emanating from a circular hole in finite strip have been solved.