• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.129-137
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• 2010

The purpose of this document is to introduce the localized development procedure for socket head cap screw used for satellite application. For localized development and verification of socket head cap screws, manufacturing process was composed of head forming, heat treatment, rolling process and surface treatment to meet aerospace hardware requirements based on MIL-B-7838, ECSS-Q-70-46A and KS W 8168 aerospace specification. In order to verify the quality and performance of localized screw, several kinds of qualification tests are successfully completed. By comparing the quality and performance for the localized screws and the same size oversea-procured screws, we can sure that localized socket head cap screws have good quality performance enough to use for aerospace application.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.368-369
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• 2008

현재 국내 중전기 시장은 시장규모에 비해 다수의 기업이 참여하고 있기 때문에, 국내 중전기 업체간 정쟁은 더욱 심화되고 있다. 따라서 국내 중전기 업체가 더욱 발전해 나아가기 위해서는 해외시장 진출 확대를 위한 수출용 전적기기의 개발이 시급하고, WTO 체제하의 시장 개방화 정책에 따른 국내외시장에서의 User의 요구에 부응하는 전력기기 개발이 절실히 요구되어 당사에서는 국책과제로써 IT 기술을 기반으로 하는 245kV Motor-drive형 초고압 GIS를 개발하게 되었다. 금번에 개발된 절연개폐장치는 변전소 자동화라는 세계적 추세에 맞추어 Bay Controller 및 전자식 변성기(NCIT)를 적용하였고, 자체 참고시험을 통해 확보된 피시품을 가지고 국제공인인증기관인 한국전기연구원(KERI)에서 IEC 국제규격에 준하여 그 성능을 검증하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.67-73
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• 1997

This paper shows the development status of attitude control thruster for KOMPSAT(Korea Multi-Purpose Satellite). Hanwha Corp. has manufactured and delivered 1.0 lbf monopropellant thrusters under the technology transfer of TRW Co. in U.S.A regarding design, analysis and manufacturing of MRE-1 thruster These thrusters will be installed to KOMPSAT which is scheduled to be launched in July 1999. Monopropellant thrusters can provide reliable and cost-effective means of propulsive control for middle class satellite and maneuvering control systems. Some information concerning with system specification, performance analysis/simulations and manufacturing process has been introduced in this paper.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.104-108
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• 2012

All of the Korean high speed train windows have been imported from abroad up to now. In this paper, the air pressure endurance test device for high speed train windows was studied and developed. This test device can create air pressure variation similar to train running real condition and carry out pressure endurance test according to international standard. Henceforward, this test device will be useful for domestic production of high speed train windows.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.843-850
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• 2020

The purpose of this study is to evaluate the structural risk and weakness of a railway tank car through nonlinear collision analysis according to overseas collision safety standards. The goal is to propose a crash safety design guideline for railway tank cars for transporting dangerous goods in Korea. We analyzed the buffer impact test procedure of railway freight cars prescribed in EN 12663-2 and the tank puncture test criteria prescribed in 49CFR179. A nonlinear finite element model according to each standard was modeled using LS-DYNA, a commercial finite element analysis solver. As a result of the buffing impact test simulation, it was predicted that plastic deformation would not occur at a collision speed of 6 km/h or less. However, plastic deformation was detected at the rear of the center sill and at the tank center supporting the structure at a collision speed of 8 km/h or more. As a result of a head-on test simulation of tank puncture, the outer tank shell was destroyed at the corner of the tank head when 4% of the kinetic energy of the impacter was absorbed. The tank shell was destroyed in the area of contact with the impacter in the test mode analysis of tank shell puncture when the kinetic energy of the moving vehicle was reduced by 30%. Therefore, the simulation results of the puncture test show that fracture at the tank shell and leakage of the internal material is expected. Consequently, protection and structural design reinforcement are required on railway tank cars in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.570-576
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• 2018

In reinforced concrete structures, the joints of ordinary rebars are usually lap joints, which are bound by binding wires with rebars, and mechanical joints by couplers. In domestic design standards (concrete design code), welded lap joints are restricted for ordinary rebars, but overseas standards allow welded lap joints of ordinary rebars through pre-heating. This study investigated the domestic and international standards/criteria and evaluated the fracture strength by performing the tensile test on the lap welded joint of SD400 grade rebars, which is used the most in the construction sites. The weld length of the specimen for weld lap joints is based on the minimum weld length (8d) given in the KS standard (KS B ISO 17660-1). According to AWS D1.4, the preheating temperature was set to $150^{\circ}C$ for D19 and below, and $260^{\circ}C$ for D22 and above. In the test results, the tensile strength of rebars with welded lap joints exceeded the required strength (125% of the yield strength) according to the concrete design code. To analyze the effect of preheating, the tensile strength of the welded rebars after preheating was not significantly different from that of the welded rebars without preheating. The carbon equivalent content (Ceq) of the rebars used in the test was 0.45% or less. Under AWS D1.4, no preheating is required if the carbon equivalent is less than 0.45%. All specimens with a welded lap length of 8d failed by a bar fracture. The effect of preheating was confirmed to be insignificant due to the low carbon equivalent of the rebar.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.6
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• pp.45-52
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• 2019

As international criteria and standards are required in the fields of design and construction, landscape performance must also be considered not only for the value of the landscape but also for providing quality assurance and sustainability. Given the lack of research on landscape performance, the present research was purposed to analyze the importance of potential assessment categories and items using an analytical network process. A list of assessment items, which is composed of 20 items and 6 categories, was derived through a literature review and a preliminary survey of 11 landscape professionals. An ANP model was established and a survey was conducted among 30 landscape practitioners to determine the weight of priorities considering the criteria. The results of ANP showed that the categories of site selection, preservation and health, and convenience had high priorities while materials had the lowest importance score. For the assessment items, a monitoring plan was the highest importance, followed by cultural/ historic preservation, management cost reduction, and natural ground areas. Despite the difficulties in quantifying landscape achievements, most respondents agreed that there needs to be an evaluation system for landscape performance in order to assure the quality and sustainability of landscape development. More research and discussion are needed to develop an assessment system for landscape performance that is applicable to Korean context.

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.124-132
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• 2018

The supply of renewable energy has become more vigorous due to Paris Agreement. In Korea, supply policies of renewable energy is being promoted with priority given to public buildings, so, the supply of fuel cell system that are relatively easy to install in buildings is expected to expand, so it is important that study on anti-islanding evaluation of grid-connected power conditioning system(PCS) for fuel cell. In this study, we consider that KGS AB934 PC53 in domestic certification standard of PCS for fuel cell correspond with abroad standard and analyze anti-islanding evaluation that important safety performance when connected grid. Additionally, we constructed a prototype for anti-islanding evaluation of PCS for fuel cell connected in parallel and carried out the demonstration evaluation, so, we have conducted ways that ensure safety performance in accordance with the circumstances where several fuel cell systems are installed.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2006.09a
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• pp.59-79
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• 2006

The successful execution of shield tunnelling depends on the cutting ability of cutter. So the selection of shape, size and material of cutter according to geology condition is important work. Since shield tunnelling method was first invented in 1881, the cutting tool for rock has been developed owing to various experiments and researches, the study for soil, however, is insufficient. This paper introduces the shield tunnelling that will be carried out on weathered rock section (920m) of Seoul Subway Line 7 Extension C703. The shape and the material of cutter are discussed required for execution without replacement of cutter tool as well as for advance of excavation efficiency. In addition the estimation method of cutter abrasion in case of excavation on weathered soil is proposed and verified. Specially, the coefficient of abrasion for different soil and cutter is proposed by means of investigation into construction example of foreign country.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.6
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• pp.625-635
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• 2013

Although the TBM method is mainly adopted in overseas market including the Europe, etc, the method scarcely adopted in domestic market. For highly enhancing applications of the TBM method for railway, It is needed to select the optimal cross-section considering design elements of civil engineering and aerodynamic effects. Also, it is needed to establish plan of proper section as well as reviewing aerodynamic effects and consideration about civil engineering elements such as length of tunnel, speed of railway, height of whole lines and size of utility tunnel, etc. Even though it should be recently considered high-speed railway tunnels and required to be standard establishments in aerodynamic reviews, it is being applied to be criteria of inconsistent pneumatic analysis owing to be not related with domestic standards. In this study, therefore, we are willing to establishment of domestic and foreign aerodynamic standards and investigate correlation between optimal cross-section and aerodynamic effects of TBM railway tunnels.