• 한국초전도ㆍ저온공학회논문지
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• 제24권3호
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• pp.57-61
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• 2022

One of the major applications of REBCO coated conductor (CC) tapes is in superconducting magnets or coils that are designed for high magnet fields. For such applications, the CC tapes were exposed to a high level of stresses which includes uniaxial tensile or transverse compressive stresses resulting from a large magnetic field. Thus, CC tapes should endure such mechanical load or deformation that can influence their electromechanical performance during manufacturing, cool-down, and operation. It has been reported that the main cause of critical current (I_c) degradation in CC tapes utilized in coil windings for superconducting magnets was the delamination due to transversely applied stresses. In most high-magnetic-field applications, the operating limits of the CC tapes will likely be imposed by the electromechanical properties together with its I_c dependence on temperature and magnetic field. In this study, we examined the influence of the transverse compressive stress on the I_c degradation behaviors in various commercially available CC tapes which is important for magnet design Four differently processed REBCO CC tapes were adopted to examine their I_c degradation behaviors under transverse compression using an anvil test method and a newly developed instantaneous I_c measurement system. As a result, all REBCO CC tapes adopted showed robustness against transverse compressive stresses for REBCO coils, notably at transverse compressive stresses until 250 MPa. When the applied stress further increased, different Ic degradation behaviors were observed depending on the sample. Among them, the one that was fabricated by the IBAD/MOCVD process showed the highest compressive stress tolerance.

• 한국가스학회지
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• 제25권2호
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• pp.42-51
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• 2021

반도체 제조에 사용하는 특수가스를 공급하는 설비는 인화성·독성·부식성을 지닌 유해·위험물질을 주로 취급하는데, 이러한 공급설비로는 주로 가스캐비닛이 사용되고 있다. 가스캐비닛 내 파열판을 통한 누출, 누출 개구부의 확대가 가능한 누출, 누출 개구부가 확대되지 않는 누출의 케이스별로 공급장치 내부 상태 및 외부로의 확산 영향을 누출 원인별로 분석하였다. 이 경우 누출 단면적에 따라 공급장치 외부로 가스가 누출되는 경우가 발생함을 확인하였다. 외부로 누출되는 가스의 농도에 따라 폭발분위기 형성 등 위험성이 존재하는 요인으로 작용하며, 위험에 따라 공급설비의 안전운전절차 등 제반 조치사항을 다시 검토할 필요가 있음을 확인하였다.

• Design & Manufacturing
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• 제16권1호
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• pp.55-61
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• 2022

As meters become digital and smart, energy data such as electricity, gas, heat, and water can be accurately and efficiently measured with a smart meter, providing consumers with data on energy used, so that real-time demand response and energy management services can be utilized. Although it is developing from a simple metering system to a smart metering industry to create a high value-added industry fused with ICT, illegal counterfeiting of electronic meters is causing problems in intelligent crimes such as manipulation and hacking of SW. The meter not only allows forgery of the meter data through arbitrary manipulation of the SW, but also leaves a fatal error in the metering performance, so that the OIML requires the validation of the SW from the authorized institution. In order to solve this problem, a quantitative confirmation device was developed in order to eradicate the act of cheating the fuel oil quantity through encoder pulse operation and program modulation, etc. In order to prevent the act of deceiving the lubricator, a device capable of checking pulse forgery was developed, manufactured, and verified. In addition, the performance of the device was verified by conducting an experiment on the meter being used in the actual field. It is judged that the developed quantitative confirmation device can be applied to other flow meters other than lubricators, and in this case, accurate measurement can be induced.

• 한국산업융합학회 논문집
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• 제25권6_2호
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• pp.1071-1081
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• 2022

As the demand for high-rise buildings increases, the demand for high-speed elevators is also increasing. In order to make a high-speed elevator, a method is needed to reduce the weight of the elevator's components, which is a constraint on the increase in speed. As a measure to reduce the weight, it is possible to remove the traveling cable for power and signal supply. Since the weight of the traveling cable varies depending on the position of the carriage, it is difficult to compensate the weight using the counter weight. The power supply is a structure in which a brush-rail type power input terminal is installed in the elevator hoistway to receive power in a contact-type manner while the carriage is moving. If a small-capacity ESS is installed in a passenger car, power can be supplied uninterruptedly inside the passenger car. A small-capacity ESS charging system to be applied to such an elevator system is required to perform several functions. First, the passenger Car must be able to charge as much as possible even during high-speed operation. A control algorithm with high responsiveness is required because charging starts and ends repeatedly by the partially installed input power stage. In addition, if the input-side line impedance is large due to the structure of the system and the response characteristic is increased, the stability of the system may be lowered. Accordingly, in this paper, we propose a control algorithm that has a stable steady-state output while having a fast response in a transient state. To verify the proposed control algorithm, simulation was conducted using PSIM, and the performance of the controller was verified by manufacturing a prototype buck conveter charger.

• 한국환경보건학회지
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• 제48권3호
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• pp.183-194
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• 2022

Background: No study has examined the regulatory factors associated with fatal health problems due to the use of humidified disinfectants (HD) in South Korea. Objectives: This study aimed to identify and discuss the deficiencies and limitations found in the Toxic Chemical Control Acts (TCCA) that failed to prevent the health risk of chemicals in HD products. Methods: The South Korean TCCA was reviewed focusing on acts in operation from 1994 through the end of 2011, the period when HD was allowed in manufacturing and marketing. Results: The TCCA was the act intended to regulate the toxicity of chemicals in HD products. We found the TCCA to lack three key legal clauses which would have been essential to controlling the health risk of HD. First, there was the exemption of toxic and hazard testing for existing chemicals, including chloromethylisothiazolinone (CMIT), methylisothiazolinone (MIT), and benzalkonium chloride (BKC). Secondly, there were no articles requiring industry to provide animal inhalation test result for polymers such as polyhexamethylene guanidine (PHMG) and Oligo(2-)ethoxyethoxyethyl guanidine chloride (PGH). Finally, there was a lack of articles on examining the risk of products as well as on addressing changes in the usage of products. These articles were found to be generally provided in the US Toxic Substance Chemical Act (TSCA) and the EU Registration, Evaluation and Authorization of Chemicals (REACH). Conclusions: In conclusion, the Ministry of Environment of South Korea had not updated key articles for regulating hazardous chemicals, causing large-scale health problems due to HD which had been fundamentally addressed in chemical-related acts in other countries.

• 한국전기전자재료학회논문지
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• 제35권6호
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• pp.594-602
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• 2022

Cast-resin transformers are widely installed in various electrical power systems because of their low operating cost and low influence on external environmental factors. However, when they have an internal defect during the manufacturing process or operation, a partial discharge (PD) occurs, and eventually destroys the insulation. In this paper, a Rogowski-type PD sensor was studied to replace commercial PD sensors used for the insulation diagnosis of power apparatus. The proposed PD sensor was manufactured with four different types of PCB-based winding structures, and it was analyzed in terms of the detection characteristics for standard calibration pulses and the changes of the output voltage according to the distance. The output increased linearly in accordance with the applied discharge amount. It was confirmed that the hexagon structure sensor had the highest sensitivity, because the winding cross-sectional area of the sensor was larger than others. In addition, as the distance from the defect increased, the output voltage of the sensors decreased by 7.32% on average. It was also confirmed that the attenuation rate according to the distance decreased as the input discharge amount increased. For the application of this new type sensor, PD electrode system was designed to simulate the void defect. Waveforms and PRPD patterns measured by the proposed PD sensors at DIV and 120% of DIV were the same as the results measured by MPD 600 based on IEC 60270. The proposed PD sensors can be installed on the inner wall of the transformer tank by coating its surfaces with a non-conductive material; therefore, it is possible to detect internal defects more effectively at a closer distance from the defect than the conventional sensors.

• 한국산업정보학회논문지
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• 제14권4호
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• pp.1-7
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• 2009

이 논문은 다목적 공정순서계획 알고리즘을 소개한다. 공정순서계획이란 가용한 기계들을 이용하여 원재료를 가공 완료된 부품으로 변형해주는 최적 공정순서들을 결정하는 일이다. 어느 컴퓨터 지원 공정계획 시스템에서나, 가공작업 순서의 결정은 부품 가공이나 부품 도면상의 기술적인 요구사항들을 충족시켜주기 위한 가장 중요한 활동 중의 하나이다. 여기서, 목표는 생산시간, 생산비용, 기계가동률 또는 이들을 복합적으로 만족시켜주는 최적 가공순서를 생성하는 일일 것이다. 파레토 스트라튬 니치 큐비클 (PS NC) 유전 알고리즘이 두 가지 상호 배타적인 기준인 생산비용과 생산품질을 동시에 최적화 시켜주는 가공순서들을 찾는데 이용되었다. 예제에 의한 검증은 제안된 PS NC 유전자 알고리즘이 공정계획문제에 있어서 효과적이며 효율적인 결과를 가져오는 것을 보여준다.

• 국제지역연구
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• 제13권1호
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• pp.309-340
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• 2009

다국적기업은 새로운 제조 및 기술을 협업에 의해 개발하기 위하여 점차로 전 세계에 걸쳐 연구개발(R&D)센터를 설치하고 있다. 이러한 범세계적인 현상은 기업의 글로벌 전략과 맞물려 신흥 공업국을 포함하는 추세다. 이는 다국적기업의 전략과 신흥공업국의 개발전략 양자에 있어 더욱 더 그 중요성이 커지고 있다. 본 연구에서는 다국적기업의 R&D이전에 따른 운영활동의 구체적인 요인들을 살펴보고 다국적기업들이 다른 국가에 비해 R&D센터 설립을 선호하는 중국과 한국에서의 R&D센터 운영을 둘러싼 각 요인을 비교 분석한다. 본 연구에서는 다국적기업의 R&D이전과 관련된 8가지 차원을 통하여 특히 입지결정 요인, 시장특성, 정부의 지원정책, R&D네트워킹에 있어 중국과 한국이 큰 차이를 보이고 있음을 밝혀냈다. 또한 다국적기업의 R&D센터 운영과 관련하여 한국보다는 중국이 긍정적인 요인이 많은 것도 비교연구로 나타났다. 본 연구의 결과는 다국적기업의 R&D센터 운영자들과 한국의 다국적기업의 유치와 관련된 정책결정자들에게 많은 시사점을 제공 할 수 있을 것이다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2021년도 추계학술대회
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• pp.132-133
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• 2021

In recent years, energy harvesting from natural sources and waste heat has been attracting more attention from researchers in response to ever-growing energy demands, high energy prices, and climate-change-mitigation purposes. It is also an important step towards future sustainable energy usages. In thermal dynamic cycles, expanders are playing as the most important equipment for waste heat recovery and energy harvesting as well. As a kind of expander, the bladeless turbine has a promising future and more widely using owning its advantages on relatively long life, good off-design performance, easy operation cleaning and maintenance, a simple structure, no blade corrosion, and low manufacturing costs. There are numerous studies about using the Tesla Turbine as a key technology for energy harvesting in a wide range of applications and conditions. They are presented to help identify technologies that have sufficient potential for applicating to our life and marine industrial engineering. This review paper, initially, presents an overview of current studies both theoretical and experimental of Tesla Turbine usage for waste heat recovery alongside its challenges and investigation on the effect of its configuration, working fluid selection as well. To conclude, future perspectives besides possible ways of transforming waste heat energy to electricity or work, which leads to circular energy, are discussed. The ambition of this paper is to act as a first-hand reference, through the well-defined possible directions, to the young researchers and senior scientists.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.673-681
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• 2023

Hydrocarbon-based polymer membranes to replace perfluorinated polymer membranes are being continuously researched. However, hydrocarbon-based membranes have a problem in that they are less durable than fluorine-based membranes. In this study, we sought to compare the annealing effect to improve the durability of sulfonated poly(ether ether ketone) (SPEEK). After membranes formation, thermogravimetric analysis and tensile strength were measured to compare changes in membranes properties due to annealing. After manufacturing the membrane and electrode assembly (MEA), the initial performance and chemical durability was compared with unit cell operation. During the 24-hour annealing process, the strength increased due to the increase in-S-O-S-crosslinking, and the sulfonic acid group decreased, leading to a decrease in I-V performance. By annealing, the hydrogen permeability was reduced to less than 1/10 of that of the nafion membrane, and as a result, open circuit voltage (OCV) and durability was improved. The SPEEK membranes annealed for 24 hours showed higher durability than the nafion 211 membranes of the same thickness.