• 신재생에너지
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• 제1권2호
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• pp.53-59
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a green-house culture facility for reducing healing cost, Increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex In Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely Investigated by changing the control condition based on the temperature difference which Is the most important operating parameter For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, It is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• Journal of Ecology and Environment
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• 제33권2호
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• pp.105-114
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• 2010

The principal objective of this study was to characterize the relationships between geographical conditions (e.g., island area, distance to mainland) and landscape structures of uninhabited islands, and to evaluate the effects of islands and their landscape structures on species richness. One hundred randomly selected islands and 5,000 m buffered areas derived from the boundaries of each island were used to summarize the number of observed bird species, and landscape pattern indices, particularly patch density, edge density, shape index, and mean nearest neighboring distance. Spatial arrangements of individual patch type at the class level, which are markedly affected by the distance from an island to the mainland, have a superior ability to explain the variances in species richness, as compared to the geographical conditions and landscape pattern indices at the landscape level. The results demonstrate that the patch type landscape structure is the primary factor affecting species richness, as well as the distance to the mainland. In particular, landscape pattern indices of cropland/pasture and woody cover are statistically significant in terms of explaining species richness, which suggests that food resources and appropriate conditions in landscape structures of habitat types are assumed as important elements in attracting bird species. This study also proposes the importance of evaluation on the landscape structure of each island, in order to designate protected areas and to establish a management plan for species conservation in uninhabited islands.

• Corrosion Science and Technology
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• 제7권5호
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• pp.274-282
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• 2008

Ships' hull is typically protected by a combination of protective coating system and electrical cathodic protection system, which has been an economical and effective measure for ship's hull to date. However, ships' rudder and adjacent hull areas are known to be subjected to premature corrosion damages, which require more frequent coating repair than other hull areas. Conventional organic coating system for ship's hull has been known only to remain intact just for 2~3 months on the rudder and adjacent area, especially for the fast-going ships such as container carriers or naval vessels. In this study, special organic/inorganic coating materials, which are commercially available, were tested in terms of cavitation resistance as an alternative to existing rudder & hull protection system. Both standard ultrasonic tester and in-house developed ultra water jet test method were employed as a means to evaluate their performance against cavitation induced damages. Additionally, the overall cost evaluation and workability at actual shipyard were discussed.

• Nuclear Engineering and Technology
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• 제37권3호
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• pp.259-264
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• 2005

This paper presents a vital area identification (VAI) method based on the current fault tree analysis (FTA) and probabilistic safety assessment (PSA) techniques for the physical protection of nuclear power plants. A structured framework of a top event prevention set analysis (TEPA) application to the VAI of nuclear power plants is also delineated. One of the important processes for physical protection in a nuclear power plant is VAI that is a process for identifying areas containing nuclear materials, structures, systems or components (SSCs) to be protected from sabotage, which could directly or indirectly lead to core damage and unacceptable radiological consequences. A software VIP (Vital area Identification Package based on the PSA method) is being developed by KAERI for the VAI of nuclear power plants. Furthermore, the KAERI fault tree solver FTREX (Fault Tree Reliability Evaluation eXpert) is specialized for the VIP to generate the candidates of the vital areas. FTREX can generate numerous MCSs for a huge fault tree with the lowest truncation limit and all possible prevention sets.

• ETRI Journal
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• 제38권1호
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• pp.112-122
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• 2016

This paper presents a set of candidate regulatory requirements for TV band devices (TVBDs) in the Rep. of Korea. To guarantee the protection of incumbent services, especially digital TV (DTV) and wireless microphones, in TV frequency bands, we suggest minimum separation distances of TVBDs from the noise-limited contour according to incumbent users and TVBD types. This paper also deals with multiple sets of separation distances of a co-channel TVBD network from a DTV protected contour on the basis of the radio propagation characteristics of different geographic areas to make good use of TV white space (TVWS) and safely protect the DTV service. We present a low-power transmission mode of TVBDs and the relevant separation distances for small-cell deployment. The service coverage reduction ratio of a TVBD network is investigated in the presence of DTV interference in four geographic areas. The TVWS field verification results, conducted on the island of Jeju (Rep. of Korea), show that incumbent services operate well without harmful interference from neighboring TVBDs with the proposed separation distances.

• 한국환경복원기술학회지
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• 제19권3호
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• pp.59-69
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• 2016

This study was conducted to develope an evaluation system for sustainable conservation of old trees with historic and traditional values in rural areas. Existing evaluation system was modified through field application of 10 old trees and expert research twice for development of new evaluation system. 4 evaluation items in 10 evaluation items were deleted by first expert research. Some items are proposed to offer a figure explanation by second expert research. End-developed evaluation items are consisted of 6 items ((1) Ground State, (2) Blight, Harmful Insects, (3) Tree Form, (4) Canopy Vitality, (5) Bark, (6) Damage) reflecting the order of importance evaluation. Old trees evaluation system developed in this study is expected to be utilized continuously to conserve the old trees in the rural areas and gradually help to increases the historic and traditional values.

• 한국환경복원기술학회지
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• 제27권2호
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• pp.29-42
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• 2024

As a global response to climate and biodiversity challenges, there is an emphasis on the conservation and restoration of ecosystems that can simultaneously reduce carbon emissions and enhance biodiversity. This study comprised a text analysis and keyword extraction of 1,100 research papers addressing nature restoration in Korea, aiming to provide a quantative and systematic evaluation of domestic research trends in this field. To discern the major research topics of these papers, topic modeling was applied and correlations were established through network analysis. Research on nature restoration exhibited a mainly upward trend in 2002-2022 but with a slight recent decline. The most common keywords were "species," "forest," and "water". Research topics were broadly classified into (1) predictions of habitat size and species distribution, (2) the conservation and utilization of natural resources in urban areas, (3) ecosystems and landscape managements in protected areas, (4) the planting and growth of vegetation, and (5) habitat formation methods. The number of studies on nature restoration are increasing across various domains in Korea, with each domain experiencing professional development.

• 한국환경생태학회지
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• 제16권1호
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• pp.104-123
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• 2002

1998년 6월부터 2000년 4월까지 모두 총 6차례에 걸쳐 축령산과 서리산 일대의 관속식물조사를 수행한 결과 모두 112과 415속 688종 1아종 116변종 12품종으로 817종류의 식물이 조사되었다. 임상은 주로 신갈나무를 비롯한 참나무류가 우점한 가운데 다양한 낙엽활엽수종이 분포하고, 잣나무, 낙엽송 조림지가 일부지역을 대표한다. 산림청 지정 희귀식물은 모두 16종류가 분포했는데. 그 중 10종류가 새롭게 확인되었으며 특히, 북방계 식물로 너도바람꽃의 분포와 주요 약용식물인 백부자, 백작약, 미치광이풀, 가시오갈피 등과 남부지방에 주로 분포하는 것으로 알려진 개족도리의 출현은 이 지역이 식물분포학상으로 매우 중요한 지역임을 알 수 있다. 특산식물은 모두 35종류로 왕느릅나무, 점현호색, 토현삼, 고려엉겅퀴 등 22종류가 새롭게 추가 되었다. 귀화식물은 모두 39종류로 확인되었는데, 이 중 30종류가 새롭게 출현한 종류이며. 주변지역에 비해 낮은 귀화율(Nl)과 높은 자연파괴도(Ul)가 나타나는 것으로 산출되었다. 대상지역은 보존가치가 많은 식물자원이 분포하고 있으나 많은 탐방객의 출입과 주변 개발 등으로 자연파괴가 가속화될 우려가 있으므로 방문객 수 제한이나 자연휴식년제를 통한 생태계 보존이 필요하다고 하겠다.

• 한국환경복원기술학회지
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• 제26권6호
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• pp.67-84
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• 2023

In some areas of the Republic of Korea, the designation and management of conservation areas do not adequately reflect regional characteristics and often impose behavioral regulations without considering the local context. One prominent example is the Busan EDC area. As a result, conflicts may arise, including large-scale civil complaints, regarding the conservation and utilization of these areas. Therefore, for the efficient designation and management of protected areas, it is necessary to consider various ecosystem factors, changes in land use, and regional characteristics. In this study, we specifically focused on the Busan EDC area and applied machine learning techniques to analyze the habitat of regional species. Additionally, we employed Explainable Artificial Intelligence techniques to interpret the results of our analysis. To analyze the regional characteristics of the waterfront area in the Busan EDC district and the habitat of migratory birds, we used bird observations as dependent variables, distinguishing between presence and absence. The independent variables were constructed using land cover, elevation, slope, bridges, and river depth data. We utilized the XGBoost (eXtreme Gradient Boosting) model, known for its excellent performance in various fields, to predict the habitat probabilities of 11 bird species. Furthermore, we employed the SHapley Additive exPlanations technique, one of the representative methodologies of XAI, to analyze the relative importance and impact of the variables used in the model. The analysis results showed that in the EDC business district, as one moves closer to the river from the waterfront, the likelihood of bird habitat increases based on the overlapping habitat probabilities of the analyzed bird species. By synthesizing the major variables influencing the habitat of each species, key variables such as rivers, rice fields, fields, pastures, inland wetlands, tidal flats, orchards, cultivated lands, cliffs & rocks, elevation, lakes, and deciduous forests were identified as areas that can serve as habitats, shelters, resting places, and feeding grounds for birds. On the other hand, artificial structures such as bridges, railways, and other public facilities were found to have a negative impact on bird habitat. The development of a management plan for conservation areas based on the objective analysis presented in this study is expected to be extensively utilized in the future. It will provide diverse evidential materials for establishing effective conservation area management strategies.

• 한국컴퓨터정보학회논문지
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• 제22권4호
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• pp.75-82
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• 2017

While the internet has evolved in terms of information sharing and efficiency, it is still prone to security attacks and remains vulnerable even when equipped with a security mechanism. Repeated patching against hacks involves excessive wear of system equipment and high costs. Methods of improving network security include the introduction of security equipment and network partitions, but they have not been fully effective. A fundamental solution is the Operation Content Network (OCN), which enables the strengthening of authentication. In this paper, Instead of following the existing TCP/IP system, OCN establishes an immunity-based security system through content-centric communications. Data transmission occurs over a Content Centric Network (CCN), which is provided with a protocol verified by the CCNx group. Areas protected by OCN rely only on CCN for communication without using any IP. As such, it defends the system against unknown attacks, including zero-day attacks.