• Nuclear Engineering and Technology
• /
• 제32권3호
• /
• pp.235-243
• /
• 2000

A one-dimensional neutronics formulation is established within the framework of the nonlinear analytic nodal method such that it can result in consistent one-dimensional models that produce the same axial information as their corresponding reference three-dimension81 models. Consistency is achieved by conserving axial interface currents as well as the planar reaction rates of the three-dimensional case. For current conservation, flux discontinuity is introduced in the solution of the two-node problem. The degree of discontinuity, named the current conservation factor, is determined such that the surface averaged axial current of the reference three-dimensional case can be retrieved from the two-node calculation involving the radially collapsed group constants and the discontinuity factor. The current conservation factors are derived from the analytic nodal method and various core configurations are analyzed to show that the errors in K-eff and power distributions can be reduced by a order of magnitude by the use of the current conservation factor with no significant computational overhead.

• Nuclear Engineering and Technology
• /
• 제53권3호
• /
• pp.732-740
• /
• 2021

Scattering resonance of medium mass nuclides leads complex spectrum in the fast reactor, which requires thousands of energy groups in the spectrum calculation. When the broad-group cross sections are collapsed, reaction rate cannot be completely conserved. To eliminate the error from energy collapsing, the Super-homogenization method in energy collapsing (ESPH) was employed in the fast reactor code SARAX. An ESPH factor was derived based on the ESPH-corrected SN transport equation. By applying the factor in problems with reflective boundary condition, both the effective multiplication factor and reaction rate were conserved. The fixed-source iteration was used to ensure the stability of ESPH iteration. However, in the energy collapsing process of SARAX, the vacuum boundary condition was adopted, which was necessary for fast reactors with strong heterogeneity. To further reduce the error caused by leakage, an additional conservation factor was proposed to correct the neutron current in energy collapsing. To evaluate the performance of ESPH with conservation factor, numerical benchmarks of fast reactors were calculated. The results of broad-group calculation agreed well with the direct full-core Monte-Carlo calculation, including the effective multiplication factor, radial power distribution, total control rod worth and sodium void worth.

• 환경영향평가
• /
• 제7권2호
• /
• pp.37-51
• /
• 1998

This study was carried out to lead the scientific management of the urban forest by estimating the forest environment. Forest environmental information was constructed using IDRISI system based on survey data, soil, plant, and digital elevation data. Forest environmental information was consisted of soil depth, soil organic content, soil hardness and parent rock as a soil environmental factor, and forest community, tree age, crown density as a plant environmental factor. Plant activity and topographic environment also were analyzed by using remote sensing data and digital elevation data. Environmental function of urban forest was estimated based on results of soil conservation and forest productivity. 70% of urban forest is located in elevation of lower than 200m and 55% of forest area have the slope of lower than 15 degree. Analyzed soil conservation status and forest productivity were almost the same as the soil chemical properties of collected soil sample and the vegetation index estimated using remote sensing data, respectively. Thus, the constructed forest environmental information could be useful to give some ideas for management of urban forest ecosystem and establishment of environmental conservation planning, including forests, in Taejon. The best forest environmental function was appeared at the natural ecology preservation zone. Current natural parks and urban parks were appeared to establish the environmental conservation plan for further development. The worst forest environmental function was appeared at the forest near to the industrial area and an overall and systematic plan was required for the soil management and high forest productivity because these forest was developing a severe soil acidification and having a low forest productivity.

• 보존과학회지
• /
• 제7권1호
• /
• pp.31-41
• /
• 1998

전쟁기념관내 문화재 보존을 위한 환경요인으로서 미생물 분포를 낙하법과 공기포집기를 사용하여 조사하였다. 기념관내의 전시실 입구와 내부 그리고 수장고의 공중진균류 분포는 관람객 출입에 의한 공기의 유통이 심한 전시실이 관람객의 출입이 없는 수장고내보다 높게 나타났다. 전시실에서의 관람객이 많은 관람기간 동안의 미생물의 분포는 휴관일보다 높게 나타났다. 이 결과는 미생물은 관람객의 이동에 따라 전시실내로 공기의 흐름과 함께 유입되어 들어온다는 것을 알 수 있었다. 기념관내에서 분리된 진균류는 19종이었으며, 고온성 진균은 1종인 Neurospors crassa로 동정되었다. 분리된 진균류의 대부분은 섬유소 문화재에 손상을 줄 수 있는 것으로 확인되었다.

• 한국환경복원기술학회지
• /
• 제13권5호
• /
• pp.123-134
• /
• 2010

Environmental conservation planning as set forth in the "Framework Act for Environmental Policy" is a representative planning that demands linkages with spatial development planning like urban master plan. However, despite the intentions and efforts of government (including revision of relevant guidelines etc.), controversy still continues regarding the efficacy of environmental conservation planning in respect of its linkages to spatial development planning. Accordingly, this study was devised to examine existing issues and produce proposals for improvement in ensuring the efficacy of environmental conservation planning by local governments. This study focused in particular on the establishment of spatial environmental plans as suggested in the guidelines of the Ministry of Environment for the purposes of strengthening the efficacy of environmental conservation planning. Based of questionnaires for relevant officials of local governments, the study found that although local governments with established current spatial environmental plans are not numerous, the need for establishment of spatial environmental plans were high in terms of the applicability of environmental conservation and spatial plans. Furthermore, this study also confirmed through analysis of questionnaires data, archival research and case study research that there were a number of salient issues including an overly access and program centered planning method based on individual pollution sources and individual post factor measures in the planning aspect, a lack of usable spatial information in the application of spatial environmental information, and inadequate connections with spatial development planning in respect of linkages with other plans. Under these circumstances, various proposals for improvement were presented including the establishment of contents in environmental conservation planning for each urban master planning item from the standpoint of planning, strengthening of basic environmental surveys for spatial planning and preparation of applicable proposals from the perspective of leveraging of spatial environmental information, and systematic improvements that can enable mutual consideration through feedback between environmental conservation planning and urban master planning from the perspective of connections with spatial planning.

• Animal cells and systems
• /
• 제3권1호
• /
• pp.29-39
• /
• 1999

Current data on reproductive characters of endemic and native species are essential to provide a strategy for the conservation of these species. Red pine (Pinus densiflora Sieb. & Zucc.) is one of the dominant, native tree species in Korea, but its reproductive ecology is not well-known. In 1997, the pattern of variation in cone and seed yields contributing to the conservation of declining populations of red pines was examined. Plant height and dbh were measured, and several new cones were collected from each tagged tree after counting the number of cones on each tree. For a subset of cones sampled, the number of fertile scales, the number of seeds at three development stages (early/late aborted, and filled seed), seed wing size, wing color, and individual filled seed mass were measured. The three sites which differed significantly in mean plant size also differed in mean cone and seed production per plant. However further analyses showed that most variation in characters examined occurred among plants within sites, but not among sites. An average of 90% of the potential seeds on the cones aborted at an early developmental stage, demonstrating that early abortion is a major factor affecting the number of filled seeds per cone. Individual seed mass was the only character which exhibited significant variations among sites as well as among trees within sites. Individual seed mass was overall negatively correlated with both the percentage of late abortion and the number of old cones per plant, suggesting that both the past and current years' reproductive activities have caused variations in seed mass. The potential dispersal distance of red pine seeds is quite large. However, wing loading was correlated with seed mass and number in a complex pattern across the sites. Distribution of seeds with varied colored wings differed among sites and among trees within sites. These results suggest that red pines at different sites might possess different strategies to cope with selection pressures acting during the final phase of reproduction, from seed dispersal to establishment. Then the ‘fitted’ red pine trees at each site should be identified and managed to conserve or restore populations.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
• /
• pp.359-361
• /
• 1987

It is known that the reactive component of AC power in the Power system gives no energy to outside and causes enlargement of power apparatus, voltage fluctuation and unstability of power system. The power conversion system and control system which are composed of power semiconductor devices such as Thyrisor, transistor, GTO and so on have been appeared as new sources of Harmonics. So the reduction of harmonics in power semiconductor system is one of impending problems on the point of energy conservation and improvement of power factor. This paper treates the fundamental review of the harmonics reduction by Current type PWM-Inverter. This Inverter-detects not only the fundamental wave but also that of all harmonics created in the power semiconductor system and is scheduled to control by sampled value.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.2283-2286
• /
• 2003

This paper presents conservation of electrical energy in building with harmonics analysis and compensation which occur in electrical system. We use load controlling and management system in order to adjust load factor of system.The maximum demand limiting and controlling are used ,then the system can acquire the prediction and compare it to the maximum demand set point.The electrical signal analysis based on FFT technique. The harmonics are compensated by using harmonic filters.This system consists computer which works as controller, processor , analysis and database unit together with digital power meter in form of multidrop network through serial communication via RS-485.The load control system uses PLC to control load via serial communication RS-485. The A/D converter is used for sampling the electrical signals via parallel port of computer.The harmonic filters are controlled by a computer.The data of measurement such as voltage, current, power, power factor, total harmonic distortion, energy, etc., can be saved as database and analysis. The load factor is adjusted by limiting and controlling maximum demand. The load factor adjustment can reduce the cost of electric consumption and energy generation together with harmonics compensation in order to increase high efficiency of electrical system.

• 한국조경학회지
• /
• 제28권4호
• /
• pp.117-124
• /
• 2000

This paper presents a design of urban waterfront park using agricultural reservoir in urban fringe area to meet increasing leisure demand for urban resident and to improve resident's quality of life through preventing the reservoir from urban use after reclamation. The site, Unam-Ji, is located on northern part of Taegu metropolitan area, having 17,791 square meters. We had designed this park from 1997 to 1998. After analyzed such factor as accessibility, current land uses, topography, hydrology, vegetation and landscape, climate, and soil, we constructed basic design scheme and principes such as conservation of natural resources, meeting user's recreation demands, providing opportunities for experiencing natural process, integrating naturalness and amenity of the site, and comfortable place with natural dynamism. Based on these principles, we have designed Unam-Ji waterfront park having intrinsic characteristics of the site, maintaining water quality and ecological restoration and improving water-based recreation opportunities. After evaluation of such criteria of design alternative as land use and circulation, spatial organization, convenience for use of and maintenance, conservation of natural environment, and degree of achieving planning and design goals, and maintaining landscape, we have visualized and formalized waterfront park in design process, which is consisted of four squares-- green square for multiple uses, water-based recreation square, pedestrian roads and decks near waterfront, performance square and fords near waterfront. In conclusion, this waterfront park design contributes to improve quality of urban development through preserving agricultural as an important component of urban water system and provide important planning and design implications in urban open space planning.

• 한국환경복원기술학회지
• /
• 제24권3호
• /
• pp.99-114
• /
• 2021

We examined a current status of damage in biodiversity and its causing factors in Hasidong Anin coastal dune, Gangneung-si, Gangwon province which is designated as ecological and landscape conservation area. In this study, we found that ecosystem and biodiversity have been primarily damaged by anthropogenic factors such as the construction of surrounding area, military facilities illegally dumped garbage and the expansion of windbreak forest. These factors occur to damage the landscape, ecosystem and biodiversity etc. There is a significant lack of basic data needed for preservation and restoration due to the lack of prior research and value assessment. In order to establish solutions for preservation and restoration, it is critical to collect fundamental data and implement value assessments. Therefore, further studies such as ecosystem services assessment, increasing biodiversity, spatial analysis and monitoring of various items related to coastal dunes are needed.