• International Journal of Internet, Broadcasting and Communication
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• 제14권3호
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• pp.249-257
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• 2022

In recent years, if we order food by easily accessing the online market with our smartphone, we can receive the product in a fresh state at dawn the next day. Cold chain is an industry that can create high added value because it has both the characteristics of general logistics and sensitivity to temperature. Based on the electrical specifications derived from the reefer container capacity requirement investigation, we proved that power supply to up to 33 reefer containers can be made by using three additional auxiliary power supplies which are applied for freight trains in Korea. In this paper, we conducted a research on a design of power supply system for freight train reefer container based on simulation as a basic research necessary for low-temperature distribution and cold chain construction based on the reefer container railroad. Consequently, the simulation was conducted using the three-phase inverter diagram in PSIM and the SVPWM (3-harmonic injection method) control technique, and it was verified that the required power voltage was satisfied with 622V_dc, which is lower than the input voltage of general SPWM of 718V_dc. The details of this paper could be used as a foundational study for constructing cold chains based on a reefer container dedicated to freight trains in the future.

• 한국산학기술학회논문지
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• 제15권6호
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• pp.3389-3395
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• 2014

제상제어 수단으로 사용하고 있는 일정 시간 제어방식, 온도차 제어방식 등은 종종 제상 오작동과 에너지 낭비를 가져오므로 좀 더 정확하게 제상을 제어할 수 있는 방법이 요구되고 있다. 수광부와 발광부로 구성된 광센서를 실외 열교환기 전방에 설치하여 서리의 유무에 따른 출력전압의 변화를 관찰함으로서 정확하게 제상제어를 할 수 있다. 본 연구에서는 기존의 일정시간 제상 방법을 사용하는 경우 나타나는 시스템 성능 및 특성 곡선을 광센서를 사용하여 재현가능한지 판단하기 위해 KS C 9306에 따른 난방 제상능력 시험조건(건구온도 $2^{\circ}C$/습구온도 $1^{\circ}C$)에서 실험을 수행하였다. 실험을 통해 측정한 난방능력, 소비전력, 열교환기 표면온도와 광센서 수광부 출력전압을 비교, 분석한 결과 제상 제어수단으로 광센서의 사용가능성을 확인하였다. 일정시간 제상방법을 통해 구한 제상 제어 단속 주기는 광센서를 통해 측정한 출력 전압의 단속 주기와 잘 일치하였다.

• 한국지능시스템학회논문지
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• 제23권2호
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• pp.107-112
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• 2013

본 논문에서는 고압용 정지형 무효전력 보상장치의 스위칭 모듈의 속도 제어 및 온도 제어 기법을 제안한다. 지속적인 전력 수요의 증가에 따른 발전 설비 및 송 배전설비의 신규 건설이 요구되고 있으며, 전력수송설비의 신 증설로 전력수송로의 병목현상에 따른 문제점이 나타나고 있다. 따라서 기존설비의 이용률을 극대화하고, 신규건설 없이 송전용량을 증대시키는 방안이 연구 되고 있다. 기존의 정지형 무효전력 보상장치 제어 방식에서는 전원입력회로에서 전위 검출하여 SCR를 직접 스위칭 동작하게 되어 있어서 노이즈가 발생하게 된다. 제안한 방법은 SCR 양단의 전위차를 바탕으로 스위칭 제어하여 스위칭 속도가 향상되고 노이즈가 감소하게 된다. 또한 스위칭 속도 증가로 발생하는 발열을 실시간 온도 제어함으로 안정성을 향상하였다. 실제 실험 환경을 구성하여 제안한 고압용 정지형 무효전력 보상장치의 속도 및 온도 제어를 실험하고, 실제 현장에서 성능을 검증하였다. 제안한 고압용 정지형 무효전력 보상장치의 스위칭 모듈을 통한 온도 제어를 실험하고, 실제 현장에서 성능을 검증하였다.

• Nuclear Engineering and Technology
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• 제45권6호
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• pp.731-744
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• 2013

Energy security is a topic of high importance to many countries throughout the world. Countries with access to vast energy supplies enjoy all of the economic and political benefits that come with controlling a highly sought after commodity. Given the desire to diversify away from fossil fuels due to rising environmental and economic concerns, there are limited technology options available for baseload electricity generation. Further complicating this issue is the desire for energy sources to be sustainable and globally scalable in addition to being economic and environmentally benign. Nuclear energy in its current form meets many but not all of these attributes. In order to address these limitations, TerraPower, LLC has developed the Traveling Wave Reactor (TWR) which is a near-term deployable and truly sustainable energy solution that is globally scalable for the indefinite future. The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared to conventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowest cost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferation concerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generation infrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need to be built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costs and 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel. With advanced technological development and added cost, TWRs are also capable of reusing both their own used fuel and used fuel from LWRs, thereby eliminating the need for enrichment in the longer term and reducing the overall societal waste burden. This paper describes the origins and current status of the TWR development program at TerraPower, LLC. Some of the areas covered include the key TWR design challenges and brief descriptions of TWR-Prototype (TWR-P) reactor. Selected information on the TWR-P core designs are also provided in the areas of neutronic, thermal hydraulic and fuel performance. The TWR-P plant design is also described in such areas as; system design descriptions, mechanical design, and safety performance.

• Journal of Radiation Protection and Research
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• 제21권4호
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• pp.313-327
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• 1996

원전부지내(AR) 사용후핵연료 건식저장방식으로 횡형콘크리트 모듈방식, 금속 저장용기 방식, 콘크리트 저장용기 방식, 수송저장 겸용용기 방식 및 다목적용기 방식 등이 있다. 이중다목적용기 방식을 제외한 다른 방식들은 각각 운영인허가를 받아 이미 세계 각 국에서 사용후핵연료 AR 건식저장에 사용되고 있으며 다목적용기 방식도 최근 개발을 활발히 진행하고 있는 상태이다. AR 건식저장 시설을 운영하고 있거나 추진중인 나라는 미국, 일본, 독일, 캐나다, 스페인, 체코, 스위스 등으로 AR 건식저장을 거쳐 중간저장이나 재처리시설로 수송하는 방식을 채택하고 있다. 우리나라의 경우 월성에서 콘크리트 Silo 건식저장을 이미 사용하고 있으며 일부 다른 원자로도 사용후핵연료 저장능력이 한계에 도달하고 있는 현실을 감안할 때 AR 임시 저장은 불가피한 것으로 여겨진다. 본 보고서에서는 고리를 비롯한 국내원전에 적용 가능한 외국의 AR 저장 시스템 각각에 대하여 설계특성, 설계요건, 기술기준 및 현황 등을 논의하였다. 대부분의 경우 저장용기 인허가 기간은 20년으로 제한하고 있으며 전 수명기간동안 재질의 건전성, 밀봉유지 등이 중요하게 요구되고 있다.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.967-974
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• 2022

It is no news that Nigeria's infrastructure challenge is enormous. In the global ranking, Nigeria ranked low in quantity and quality of its infrastructural provision which has a great impact on the ease of business transaction. Low investments in transportation have brought about the current infrastructural deficit. Recently, the Nigerian government has made effort to address at least to some extent the infrastructural deficit through Public-Private Partnership, but this has not yielded the desired result. Moreover, the sustainability issues relating to railway projects such as, emissions, noise pollution, ecosystem, and other environmental issues calls for urgent attention. Hence, this necessitated consideration on sustainability appraisal for the Chinese rail project in Nigeria. This study reviews sustainability of railway projects built by the Chinese firm in Nigeria with particular emphasis on the environmental and social impact of these projects. The study further identified issues and challenges in project implementation with a particular focus on civil dialogue and community engagements. A detailed literature search was conducted on railway projects and infrastructure by systematically reviewing selected published articles.The analysis of the selected articles identified sustainability issues and potential for improvement of Chinese railway projects and how they contribute to or inhibit competitiveness in the Nigerian railway market. From the literature searched, some of the projects constructed by Chinese firm revealed that there is economic and social impact of railway projects delivered by the Chinese firm in terms of capacity development and knowledge transfer potentiality. For instance, in the just concluded Lagos-Ibadan railway projects, the study gathered that the project brought about 5000 jobs and local staff were trained by the Chinese company, this will boost man power and local content capability. Also, it will significantly improve Nigeria's infrastructure and boost its economic development. The study suggests that Nigerian government should ensure and provide an enabling environment that is conducive for investment on the continent. Peace, improved security, and decent governance are the best conditions for sustainable transportation growth.

• 한국수소및신에너지학회논문집
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• 제31권1호
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• pp.33-40
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• 2020

As hydrogen utilization becomes more active recently, a large amount of hydrogen should be supplied safely. Among the three supply methods, liquefied hydrogen, which is an optimal method of storage and transportation convenience and high safety, has a low temperature of -253℃, which is complicated by the liquefaction process and consumes a lot of electricity, resulting in high operating costs. In order to reduce the electrical energy required for liquefaction and to raise the efficiency, hydrogen is cooled by using a mixed refrigerant in a precooling step. The electricity required for the precooling process of the mixed refrigerant can be reduced by using the cold energy of LNG. Actually, LNG cold energy is used in refrigeration warehouse and air liquefaction separation process, and a lot of power reduction is achieved. The purpose of this study is to replace the electric power by using LNG cold energy instead of the electric air-cooler to lower the temperature of the hydrogen and refrigerant that are increased due to the compression in the hydrogen liquefaction process. The required energy was obtained by simulating mixed refrigerant (MR) hydrogen liquefaction system with LNG cold heat and electric system. In addition, the power replacement rate of the electric process were obtained with the pressure, the temperature of LNG, the rate of latent heat utilization, and the hydrogen liquefaction capacity, Therefore, optimization of the hydrogen liquefaction system using LNG cold energy was carried out.

• 한국산학기술학회논문지
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• 제12권11호
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• pp.5156-5163
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• 2011

전기 구동 이륜차는 우수한 연비 및 환경공해 능력 때문에 가장 유망한 미래 교통수단 중의 하나이다. 실제 전기 이륜차 시제품을 제작하기 전에 신뢰성이 확보된 시뮬레이션 프로그램을 통하여 전기 이륜차의 설계인자 최적화와 동력원의 능력을 평가할 필요가 있다. 이 같은 과정을 통하여 전기 이륜차 시스템 설계 과정에서의 소요비용을 줄일 수 있다. 본 논문에서는 수월하게 Simulink와 PSAT을 이용하여 구동 및 동력 시스템을 모델링할 수 있는 Matlab 기반의 전기 이륜차 해석 프로그램을 제시하였다. 전기 이륜차의 최대 출력, 에너지 능력, 충전 상태, 등판각도와 같은 설계 인자 해석을 실험과 시뮬레이션을 병행하였다. 본 연구에서 개발된 모델에 의해서 예측된 해석결과는 실험에 의해서 얻어진 결과와 양호하게 일치하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.65-72
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• 2001

Since Pyoungtaek thermal power plant began using natural gas in 1986, the annual using volume has rapidly increased and reached 12.7 million tons in 1999. When the natural gas is cooled to a temperature of approximately -162$^{\circ}$C at atmospheric pressure, it condenses to a liquid called liquefied natural gas(LNG). LNG has a special characters such as odorless, colorless, non-corrosive, and non-toxic. So, LNG storage tank, tanker ship, transfer pipelines are required the special storage and transportation systems and technology. The presently operating LNG terminals are Pyongtaek and Inchon terminals. A total of 19 above-ground LNG storage tanks(100 thousand ㎘ grade) are currently in operation with a sendout capacity of 4,360tons/hour. To meet the growing domestic demand of LNG supply, the Inchon receiving terminal is expanding(six in-ground tank) and constructing a third LNG terminal at Tongyong. In this paper, case study on seepage analysis and countermeasure against increasing the seepage volume of in-ground LNG storage tank excavation work is reported. The results of an additional seepage analysis are presented to verify the design seepage volume of assumption section and seepage volume after curtain-grouting in the slurry wall.

• 조명전기설비학회논문지
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• 제26권10호
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• pp.111-117
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• 2012

Electric vehicles (EVs) are the most promising alternative substitute to a significant amount of gasoline vehicles for climate friendly transportation. This paper conducted an EV consumer survey through the telephone for 200 residents living in apartments to predict the EV penetration level in the year 2020. The results of EV consumer survey revealed that EV will be penetrated to 10% of the total vehicles in rental apartments and to 23.6% of the total vehicles in apartments for sale(condominium) until 2020. High EV penetration level, however, will lead to an increase of power consumption and over loading of electrical installations. Integrating more electric vehicles, the capacity of transformer related in apartments should be checked to prevent the over loading of the transformer. This paper checked the possibility of over loading at transformer and suggested the load control system as one of the solutions to reduce the over loading of transformers in apartments. Also this paper reviewed other components that should be checked in the designing of EV recharging infrastructure in apartments.