• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.2
• /
• pp.666-671
• /
• 2014

Using positive temperature coefficient (PTC) heater as supplementary heating for diesel engine vehicles with low heat source is a good method to enhance the heating performance during cold start. In this study, the PTC elements were made by using screen printing process for forming ohmic contact layer, and prototype of PTC heater was designed and made for a diesel engine vehicle. In process of designing the PTC heater, the thermal flow analysis of PTC element modules was conducted for verifying the effect of the shapes of contact surface between each of the components (cooling fin, insulator, ceramic element). We also investigated the performance characteristic (heating capacity, energy efficiency, pressure drop) of the PTC heater through the experiments. Therefore, the experimental results indicated that prototype of PTC heater had satisfactory performance. This study will be basis for improving the manufacturing process and increasing the performance of the PTC element and heater.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.28-28
• /
• 2009

최근 전세계적으로 유가 상승 및 배기가스 배출 저감과 관련된 각종 환경규제에 대응하기 위하여 선진 자동차회사들은 $CO_2$ 배출 저감 기술과 기존 내연기관 차량의 연비향상을 위해 엔진성능 개선, 구동시스템의 최적화, 차량 경량화, 공기저항 감소 등에 초점을 맞춰 차량의 연비향상과 배기가스 규제에 대응하고 있다. 특히, 자동차 중량의 30%를 차지하는 차체의 경량화는 엔진효율을 높여 자동차의 성능향상을 극대화시키고, 그로 인해 연비향상을 도모할 수 있으므로 환경오염 방지와 연료절감에 가장 적합하고 효과적인 방법이다. 이에 기존의 강재에 비해 비중이 낮으면서 유사한 강도와 내식성이 뛰어난 알루미늄 합금의 차체 적용에 대한 연구가 진행되고 있다. 본 연구에서는 자동차 Door에 알루미늄 합금(Al 5052)의 적용 가능성을 판단하기 위해 반응표면분석법(Response surface methodology)을 이용하여 저입열 Pulse MIG 용접 공정변수를 최적화하였다. 첫째, 저입열 Pulse MIG 용접에서 용접 공정 변수(용접전압, 용접속도, Gap)의 변화가 비드 형상에 미치는 영향에 대해 평가하였다. 요인분석법을 이용하여 용접 공정 변수와 비드 형상 변수와의 주효과와 교호작용효과를 분석하였고, 이를 통해 비드 형상 변수에 영향을 크게 미치는 용접 공정변수를 선별하여 다중회귀분석을 통해 용접 공정 변수 변화에 따른 비드형상 예측 회귀모델을 제안하였다. 둘째, 자동차 Door 생산 현장에서 박판 알루미늄 합금 겹치기 용접 이음부의 0~1 mm 갭 발생에 대해 강건한 용접조건을 제시하기 위해 반응표면법(Response surface methodology)을 이용하여 저입열 Pulse MIG 용접 공정 변수를 최적화하였고, 그 적용 가능성을 확인하였다.

• Journal of the Korea Society of Computer and Information
• /
• v.20 no.1
• /
• pp.163-173
• /
• 2015

In this paper, it shows optimal inventory level of bicycle sharing service terminal by maintaining the lowest costs. As the interest to environment and exhaustion of resource increases globally, investment to sustainable transportation increases around advanced countries and interest to efficient transportation, managing and consuming of vehicle increases also. Vehicle sharing service is a model of rental car where customer rent cars for short periods of time often by the hour and its users are increasing for the reason that it is more convenient than car rent. In addition, bicycle sharing service is one of the major parts in vehicle sharing program and many of country are already managing it. This paper proposes optimal inventory levels of vehicle sharing service's terminal by using simulation calculating operation costs of vehicle sharing service.

• Journal of the Korean Institute of Gas
• /
• v.25 no.5
• /
• pp.19-29
• /
• 2021

Due to the climate changing, the world's countries are tightening regulations on CO2 and air pollutants emission to solve them. In addition, eco friendly vehicles is increasing to replace automobiles in internal combustion engine. Recently, the government is supporting the expansion of hydrogen refueling infrastructure and localization of core equipment in refueling facilities according to the hydrogen economy road map. In this study, design of the Excess flow limiting device in FCEV cylinder valve using by finite element analysis and performed performance tests on prototype. Major test results as hydrostatic strength, continued operation, operation, pressure impulse, leakage showed that the excess flow limiting device meets the performance requirements according to ISO 12619-2 and ISO 12619-11.

• Journal of the Korea Convergence Society
• /
• v.10 no.3
• /
• pp.177-184
• /
• 2019

The Defense Technology Security Act was enacted in 2015 to protect the defense industrial technology from being duplicated or interfering technologies being developed, which prevents its value and utility from deterioration and prevents inappropriate export. Defense industrial technology refers to technology that should be protected for national security among the national defense science and technology related to the defense industry. However, technical identification criteria of identification and management system of protection technology are not regulated. Therefore, in this study, through the Delphi survey, diesel engine core technology identification criteria related to the high efficiency internal combustion engine propulsion technology among the 141 defense industrial technologies is established to improve the identification and management system of the technology to be protected among the defense industrial technology protection system. As a result of the study, operational operability, durability, safety, sequencing and modularization were established as diesel engine core technology identification criteria.

• Journal of the Korean Institute of Gas
• /
• v.22 no.6
• /
• pp.34-39
• /
• 2018

Natural gas is attracting attention as an alternative to existing fossil fuels. Natural gas has a high octane number. Therefore, knocking does not occur even if the compression ratio is increased, so that the thermal efficiency and the output can be improved. And it is relatively easy to apply the natural gas supply system to the internal combustion engine hardware system. In this study, a gasoline direct injection turbo engine was converted into a natural gas port injection type turbo engine. Therefore, the combustion and performance of the engine are measured and compared comprehensively in the region where the turbo operates.

• Journal of the Korean Electrochemical Society
• /
• v.22 no.1
• /
• pp.1-12
• /
• 2019

The reduction of nitrogen to produce ammonia has been attracting much attention as a renewable energy technology. Ammonia is the basis for many fertilizers and is also considered an energy carrier that can power internal combustion engines, diesel engines, gas turbines, and fuel cells. Traditionally, ammonia has been produced through the Haber-Bosch process, in which atmospheric nitrogen combines with hydrogen at high temperature ($350-550^{\circ}C$) and high pressure (150-300 bar). This process consumes 1-2% of current global energy production and relies on fossil fuels as an energy source. Reducing the energy input required for this process will reduce $CO_2$ emissions and the corresponding environmental impact. For this reason, developing electrochemical ammonia-production methods under ambient temperature and pressure conditions should significantly reduce the energy input required to produce ammonia. In this review, we introduce the electrochemical nitrogen reduction reaction at ambient condition. Numerical studies on the electrochemical nitrogen reduction mechanism have been carried out through the computation of density function theory. Electrodes such as nanowires and porous electrodes have been also actively studied for further participation in electrochemical reactions.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.32 no.1
• /
• pp.7-16
• /
• 2019

In this paper, for a seismic analysis of an offshore subsea manifold, Response Spectrum Analysis(RSA) and Time History Analysis(THA) were conducted under a various analysis conditions. Response spectrum and seismic design procedure have followed ISO19901-2 code. In case of THA, The response spectrum were converted into artificial earthquake history and both of Explicit and Implicit solvers were used to examine the characteristics of seismic analysis. For the verification, Various seismic analysis methods were applied on a single degree of freedom beam model and a simplified model of the actual manifold. The difference between the results of RSA and THA on the simplified manyfold model evaluated for the analysis of the actual manifold. Because THA is impossible in case of real complex structure such as a manifold, Safety of the actual manifold structure was accessed by using the RSA and the difference between the results of RSA and THA from the simplified model.

• Journal of architectural history
• /
• v.28 no.3
• /
• pp.29-44
• /
• 2019

A major performance stage carpenter, Jang Insang led performance stages from the 1719 Sukjong Royal Banquet and was confirmed by historical records to be the first craftsman. Lee Wandeuk led the Hwaseong Fortress performance stages of the Jeongjo period and Gichuk Jinchan performance stages of the Sunjo period. The carpenter techniques he used during the Jeongjo period were succeeded to the Sunjo period. Ahn Sungil was the head craftsman who led the performance stages of Jagyeongjeon Jinjak, Muja Jinjak, and Gichuk Jinchan of the Sujo period, under which the foundation for court palace performances was laid. The progression of major carpenters includes Jang Insang of the Sukjong period, Jeon Yoochu of the Yeongjo period, Ahn Sugil of the Sunjo period, Yoon Seoksin of the Heonjong period, Kim Yoonsik of the Gojong period, Lee Jongyoon, Kim Soongil, Seo Sangmook, and Han Sujoon. In addition, the Major Repair of Injeongjeon Hall (1857) of the Cheoljong period was the most important palace construction project for transferring the carpenters' skills. Through this project, Ahn Sungil of the Sunjo period, Kim Myeonggap, Yoon Seoksin of the Heonjong period, Kwon Deuknyang, and Kim Sungil of the Gojong period were able to interact with each other. That is, this major repair project of Injeongjeon Hall reflected the major carpenters' best techniques through performance stage construction, showing the progression of Ahn Sungil, Yoon Seokshin, and Kim Sungil, who led the constructions of Gichuk Jinchan of the Sunjo period (1829), Mushin Jinchan of the Heonjong period (1848), and Jeonghae Jinchan of the Gojong period (1887), the most impressive performance stages of the late Joseon period. The carpenters of the court performance stages participated in important construction projects of the royal palace, reflecting the superior technical skills of the carpenters in the construction of court palace performance stages. The carpenters who played a leading role in the construction of performance stages were able to interact with one another and transfer their excellent technical skills, providing the driving force that allowed court performance stages to blossom into splendid and high-quality court stages in the late Joseon Dynasty.

• The Journal of the Convergence on Culture Technology
• /
• v.5 no.1
• /
• pp.377-384
• /
• 2019

To cope with severe global warming and environmental pollution problem regulations on automobile emissions and fuel efficiency has been tightened around the world. Therefore zero emission vehicles which do not use fossil fuels such as electric vehicles have attracted attention by government and both industry and academia at developed countries. In the market, electric vehicles are being selected from more and more consumers because of technological advances and policy support. Recently another zero emission vehicle, hydrogen fuel cell vehicle, is drawing attention and is expected to become deployed widely. This paper reviews technology, current status and global trends of zero emission vehicle. The economical analysis of zero emission vehicles are also presented.