• 에너지공학
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• 제20권1호
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• pp.8-12
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• 2011

온실가스 감축을 위한 단기 정책으로는 기존의 고효율 에너지 기기의 보급을 촉진하고 에너지 효율을 개선하는 에너지 효율개선, 에너지 절약사업에 투자를 활성화하는 것 등이 포함된다. 장기적으로는 기술개발이 핵심정책이다. 에너지수요의 저감을 위해서는 에너지 효율이 향상된 기기와 공정이 개발되어야 한다. 에너지 공급측면에서 온실가스 감축정책은 태양광, 풍력, 지열, 바이오매스 등과 같은 신재생에너지와 원자력과 같은 온실가스를 거의 배출하지 않는 저배출 에너지원의 공급을 확대하여 화석연료를 대체하는 것이다. 에너지 소비측면에서 온실가스 감축대책은 에너지 효율향상 정책과 맥을 같이 한다. 산업과 건물부문에서 에너지 다소비사업장, 건물 등에 대한 자발적 협약을 강화하고, 에너지 절약시설에 대한 투자를 강화하는 정책을 시행해야 할 것이다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.109-116
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• 2003

국내 원자력 산업의 급속한 성장과 더불어 하나로 시설의 본격적인 가동 및 핵연료주기시험과 관련한 연구의 증가로 인하여 방사성폐기물의 발생량 및 누적량이 지속적으로 증가될 전망이며, 이에 따라 방사성폐기물의 안전성 확보 및 감용 처리를 위한 노력이 더욱 강조되고 있다. 조사후시험시설에서는 원자력발전소에서 발생하는 사용후핵연료봉의 결함원인 규명과 건전성 평가를 위한 조사후시험을 수행하고 있으며, 본 연구에서는 조사후시험시설에 설치되어 있는 방사성고체폐기물 처리설비를 활용하여 조사후시험에서 발생하는 폐기물의 압축, 파쇄, 절단기술 및 경험사례에 대하여 기술하였다. 고준위 방사성고체폐기물 처리는 특수 제작하여 핫셀에 설치되어 있는 100톤 압축기로 방사성고체폐기물을 압축하여 폐기물의 양을 1/12정도로 감용 처리하였으며, 중ㆍ저 위 방사성고체폐기물은 인터벤션에 설치된 60톤 압축기를 사용하여 가연성폐기물을 1/8정도로 압축 감용 처리하였다. 폐플라스틱 통은 파쇄기를 사용하여 절단처리 함으로써 1/5, 폐 필터는 1/6의 감용 비를 얻었으며, 비 가연성물질인 금속류 물질 또한 절단 처리하여 드럼의 양을 줄일 수 있었다.

• Corrosion Science and Technology
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• 제19권3호
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• pp.131-137
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• 2020

A number of piping components in the secondary system of nuclear power plants (NPPs) are exposed to aging mechanisms, such as flow-accelerated corrosion (FAC), cavitation, flashing, solid particle erosion, and liquid droplet impingement erosion. Those mechanisms may lead to thinning, leaking, or rupture of the components. Due to the pipe ruptures caused by wall thinning in Surry unit 2 in the USA in 1986 and Mihama unit 3 in Japan in 1994, pipe wall thinning management has emerged as one of the most important issues in the nuclear industry. To manage pipe wall thinning, a foreign program has been utilized for NPPs in Korea since 1996. As our experience and knowledge of pipe wall thinning management have accumulated, our program needs to reflect our experience, requests from users, and the result of recent experiments using Flow Accelerated Corrosion Testing System (FACTS). FACTS is the empirical experimental facility developed by Korea Atomic Energy Research Institute (KAERI) for tests. Accordingly, KEPCO-E&C developed a 3D-based pipe wall thinning management program called ToSPACE in 2016. This paper describes a comparison between the FAC analysis results using ToSPACE and the experimental results using FACTS to verify their applicability to pipe wall thinning management in NPPs.

• 한국표면공학회지
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• 제34권1호
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• pp.10-16
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• 2001

Recently plasma etching research has been focused on the metal surfaces in the nuclear industry. In this study, surface etching reaction of metallic Co and Mo, principal contaminants in the spent nuclear components, in CF$_4$/O$_2$, gas plasma has been experimentally investigated to look into the applicability and the effectiveness of the technique for the surface decontamination. Experimental variables are $CF_4$/$O_2$ ratio and substrate temperature between 29$0^{\circ}C$ and 38$0^{\circ}C$. Experimental results Show that the optimum gas composition is 80%CF$_4$-20%$O_2$ and the metallic Co and Mo are etched out well enough in the temperatures range. Cobalt starts to be etched above $350^{\circ}C$ and the etching rate increases with increasing substrate temperature. Maximum rate achieved at 38$0^{\circ}C$ under 220 W r.f. plasma power is 0.06 $\mu\textrm{m}$/min. On the other hand, the metallic Mo is etched easily even at low temperature and the reaction rate drastically increases as the substrate temperature goes up. Highest rate obtained under the same conditions is $1.9\mu\textrm{m}$/min. OES (Optical Emission Spectroscopy) analysis reveals that the intensities of F atom and CO molecule reach maximum at the optimum gas composition, which demonstrates that the principal reaction mechanism is fluorination and/or carbonyl reaction. It is confirmed, therefore, that dry processing technique using reactive plasma is quite feasible and applicable for the decontamination of surface-contaminated parts or equipments.

• 분석과학
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• 제16권5호
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• pp.1041-1051
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• 2003

즉발감마선 중성자방사화법 (PGAA)은 시료내 미량 및 주원소를 빠르게 비파괴적으로 분석하는 방법으로 주로 광물, 금속, 석탄, 시멘트, 석유, 코팅, 제지 등 다양한 산업체에서 실시간 분석법으로 매우 유용하다. 이 방법은 제약과 관련된 산업체 또는 연구업무에도 활용되며, 마약 또는 폭발물과 같은 위험물질의 탐지에도 이용되고 있다. 본 총설은 즉발감마선 중성자 방사화법의 현재의 기술현황과 앞으로 연구추진 경향에 대하여 서술하였다. PGAA 시스템은 중성자 선원, 증성자 핵반응으로부터 발생하는 즉발감마선을 측정하기위한 다중채널분석기와 A/D 변환기 등의 전자모듈과 고분해능 HPGe 검출기로 구성된다. 속중성자의 콤프턴 산란에 의한 높은 바탕값은 감마-감마 동시계수장치의 도입으로 개선될 수 있다. 현재 $^{252}Cf$를 사용한 즉발감마선 중성자 방사화 장치는 수용액중에 존재하는 원소들의 실시간분석을 위해 한국원자력연구소에서 개발중에 있다. 이 장치는 다양한 마약 및 폭발물 또는 화학무기의 탐지에도 응용될 수 있다.

• Structural Engineering and Mechanics
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• 제18권3호
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• pp.343-362
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• 2004

Rocking response of rigid bodies with rectangular footprint, freely standing on horizontal rigid plane is studied analytically. Bodies are subjected to simulated single component of horizontal earthquakes. The effect of baseline correction, applied to simulated excitations, on the rocking response is first examined. The sensitiveness of rocking motion to the details of earthquakes and geometric properties of rigid bodies is investigated. Due to the demonstrated sensitivity of rocking response to these factors, prediction of rocking stability must be made in the framework of probability theory. Therefore, using a large number of simulated earthquakes, the effects of duration and shape of intensity function of simulated earthquakes on overturning probability of rigid bodies are studied. In the case when a rigid body is placed on any floor of a building, the corresponding probability is compared to that of a body placed on the ground. For this purpose, several shear frames are employed. Finally, the viability of the energy balance equation, which was introduced by Housner in 1963 and widely used by nuclear power industry to estimate the rocking stability of bodies, is evaluated. It is found that the equation is robust. Examples are also given to show how this equation can be used.

• 한국해양공학회지
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• 제22권5호
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• pp.100-105
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• 2008

A106 Carbon Steel has recently been used as the material for pipes, nozzles, and tank shells in nuclear power plants. Its corrosion resistance gives the steel many advantages for use in structures under high temperature and high pressure. This steel is also expected to be used as a structural material in the shipbuilding industry for applications involving severe conditions, such as high temperature and pressure. In this study, the mechanical properties of A106 carbon steel were evaluated in regard to its corrosion times. The tensile and yielding strengths decreased as the corrosion time increased. In particular, the tensile strength was influenced by corrosion. In addition, an acoustic emission (AE) technique was used to clarify the microscopic damage to specimens that had undergone corrosion for a certain period. It was found that AE parameters, such as events, energy, duration time, and amplitude were useful for evaluating the degree of damage and remaining life of the corroded specimen. Various properties of the waveform and frequency range were also seen, based on the degree of damage to the specimen from the corrosion time.

• 한국생산제조학회지
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• 제21권4호
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• pp.658-665
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• 2012

Micro-EDM is widely used in metallic pattern, electronics, nuclear power and industry in the form of precision process. The improvement of Electro Discharge Machining has been on a steady progress since $19^{th}$ century. The technology has overcome the limits of the traditional precision process, enabling micro-EDM, micro electrolytic machining, micro drilling, micro punching and laser beam machining, which create versatile products with smaller sizes. What have been known about the major feature of Micro-EDM is high thermal energy so that their products are free from the hardness of their products as long as they are electrical conductor. However, each metal is suspected to have different features and natures even if they are created through the same procedure. In this thesis, the methodology of Micro-EDM and how to categorize them are explained. Also, the nature of the examined materials with surface shape and surface roughnes are analyzed. The results of the experiments are expected to understand surface roughness and workability of other materials for Micro-EDM.

• 대한산업공학회지
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• 제41권3호
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• pp.259-266
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• 2015

Among many energy resources, natural gas has recently received a remarkable amount of attention, particularly from the electrical generation industry. This is in part due to increasing shale gas production, providing an environment-friendly fossil fuel, and high risk of nuclear power. Because South Korea, the world's second largest LNG importing nation after Japan, has no international natural gas pipelines and relies on imports in the form of LNG, the natural gas has been traditionally procured by long term LNG contracts at relatively high price. Thus, there is a need of developing an Asian LNG trading hub, where LNG can be traded at more competitive spot prices. In a natural gas spot market, the amount of natural gas to be bought should be carefully determined considering a limited storage capacity and future pricing dynamics. In this work, the problem to find the optimal amount of natural gas in a spot market is formulated as a Markov decision process (MDP) in risk neutral environment and the optimal base stock policy which depends on a stage and price is established. Taking into account price and demand uncertainties, the basestock target levels are simply approximated from dynamic programming. The simulation results show that the basestock policy can be one of effective ways for procurement of LNG in a spot market.

• 한국자원식물학회지
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• 제24권3호
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• pp.330-336
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• 2011

The recent disaster of earthquake and tsunami on March 11, 2011 severely attacked East Japanese cities and people, and in addition, the accident of nuclear power station will inevitably damage the agricultural activities there. The economical depression influences on the horticulture and floriculture industry as well, through the reluctant consumption all over the country. Such a situation reflects a conventional perception that the garden plants or ornamental plants have been regarded as a symbol of capitalism, representing the success, luxury, beauty or other metaphors indicating the winners of business war. But as the word "culture" means "cultivation" originally, horti "culture" or flori "culture" should have played some roles in cultivating lands as well as cultivation of human minds, leading to develop a modern "culture" which may lay emphases on personality, originality, partnership, cooperation, diversity and so forth. In this article, a brief history of garden plants in Japan, as well as some current movements in Japanese horticulture and floriculture, is reviewed with some commodities which possess messages on creating a new humane culture.