• 환경영향평가
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• 제11권4호
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• pp.271-280
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• 2002

The purpose of this study is to explore the hydrological impacts and soil loss variation due to the land use change of Namak New Town development area. The analysis of hydrological effects and soil loss variation has been carried out using GIS in this study. In order to estimate the peak runoff volume, the Rational Method which is the most popular technique to predict runoff amounts is used. To estimate the soil loss in the study area, Universal Soil Loss Equation(USLE), which is one of the most comprehensive and useful technique to predict soil erosion is adopted. The result of this study has shown that the peak runoff volume and the total soil loss increase according to the land use change. The peak runoff volume and the total soil loss have been increased about 2 times and about 48 times more than that of pre development. The increasing of the peak runoff volume can be effective erosion, flooding and so on. A careful city planning is the first essential step to minimize the environmental impacts and to construct the ecological city.

• 대한조선학회논문집
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• 제46권6호
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• pp.569-577
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• 2009

As the scale factor of model propellers utilized in cavitation test is about 40, it is difficult to find out practical countermeasures against the small area erosions on the blade tip region throughout model erosion tests. In this study, a partial propeller blade model was used for the observation of cavitation pattern for the eroded propeller. A partial propeller blade model was manufactured from 0.7R to tip with expanded profile and with adjustable device of angle of attack. Reynold's number of a partial propeller blade model is 7 times larger than that of a model propeller. Also, anti-singing edge and application of countermeasures to partial propeller blade model which produced in large scale can be more practical than a model propeller. For the observation of cavitation at high Reynold's number, high speed cavitation tunnel was used. To find out the most severe erosive blade position during a revolution, cavitation observation tests were carried out at 5 blade angle positions.

• 농업과학연구
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• 제49권4호
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• pp.809-819
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• 2022

This study was conducted to improve the stability of cut slopes of forest roads in granitic weathered soil areas. The study area is a national forest road (road length 28.48 km) in Pyeongchang-gun, Gangwon-do. After data collection, a statistical analysis was performed using IBM SPSS (Ver. 26.0). First, the correlation analysis showed that structure, slope position, soil erosion, slope, and aspect (N, S) were correlated with vegetation coverage (p < 0.05). Elapsed years, slope distance, and aspect (E, W) were found to have no correlation with vegetation coverage. (p > 0.05) Second, one-way ANOVA and Kruskal-Wallis test results showed that vegetation coverage was worse when the slope was located at the top or the middle of the slope than at the bottom of the slope. In addition, the site with sheathing and gabions showed good vegetation coverage when compared with the site without structures. In the case of soil erosion, areas with severe damage and moderate damage showed worse vegetation coverage. Therefore, it is necessary to strengthen the slope angle of the cut soil of the granitic weathered soil area from 1 : 0.5 - 1.2 to 1 : 0.8 - 1.5. In addition, structures such as sheathing and gabions should be installed on granitic weathered land.

• 대한조선학회논문집
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• 제50권5호
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• pp.324-333
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• 2013

Recently, rudder erosion due to cavitation has been frequently reported on a semi-spade rudder of a high-speed large ship. This problem raises economic and safety issues when operating ships. The semi-spade rudders have a gap between the horn/pintle and the movable wing part. Due to this gap, a discontinuous surface, cavitation phenomenon arises and results in unresolved problems such as rudder erosion. In this study, we made a rudder model for 2-D experiments using the NACA0020 and also manufactured gap flow blocking devices to insert to the gap of the model. In order to study the gap flow characteristics at various rudder deflection angles($5^{\circ}$, $10^{\circ}$, $35^{\circ}$) and the effect of the gap flow blocking devices, we carried out the velocity measurements using PIV(Particle Image Velocimetry) techniques and cavitation observation using high speed camera in Seoul National University cavitation tunnel. To observe the gap cavitation on a semi-spade rudder, we slowly lowered the inside pressure of the cavitation tunnel until cavitation occurred near the gap and then captured it using high-speed camera with the frame rate of 4300 fps(frame per second). During this procedure, cavitation numbers and the generated location were recorded, and these experimental data were compared with CFD results calculated by commercial code, Fluent. When we use gap flow blocking device to block the gap, it showed a different flow character compared with previous observation without the device. With the device blocking the gap, the flow velocity increases on the suction side, while it decreases on the pressure side. Therefore, we can conclude that the gap flow blocking device results in a high lift-force effect. And we can also observe that the cavitation inception is delayed.

• 한국해양환경ㆍ에너지학회지
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• 제13권4호
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• pp.263-269
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• 2010

조류발전용 HAT 임펠러에 팁 레이크를 적용하여 임펠러 성능을 고찰해 보았다. 기존의 조류발전용 임펠러는 날개 끝 보오텍스에 의해 효율 감소로 인한 전력 손실 뿐 아니라 소음 및 진동에 의한 설치해역 주변의 해양 생태계 파괴의 우려가 있다. 임펠러 날개 끝에 레이크를 적용함으로써 효율의 개선과 함께 소음 및 진동 저감 효과를 파악하고자 하였다. 향후 레이크 비율에 따른 효율증가 및 캐비테이션 성능 향상에 대한 최적화를 수행할 계획이다.

• 한국환경복원기술학회지
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• 제4권3호
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• pp.84-95
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• 2001

This study was conducted to suggest the ecological restoration methods for the decomposed granite roadside cutslopes by Natural Topsoil Restoration Methods(NTRM). Four woody species, 3 shrub species, 4 native grasses, 8 wild flowers and 2 cool-season grasses were used. The experiment was conducted with the purpose of developing ecological restoration techniques by achieving following objectives for restoration by using native woody plants, shrubs, native plants and wild flowers; (1) prevention or reduction of wind and water erosion, (2) provision of food and cover for variety of animal species, (3) improvement of the visual or aesthetic quality of disturbed sites. The main results were summarized as follows. 1. Restoring naturalness to human-altered landscapes are important to protecting the worlds biodiversity. In this study, to restore or create an ecological community use as full a complement of native species as possible. Ecological restoration means returning a specific sites to its predisturbance condition. 2. Some species which are introduced first may inhibit the germination and growth of slower-growing species, or they may prevent the growth of other species whose propagules arrive later. In this study, cool season grasses was used small amount than native plants and woody species, because and Indigofera pseudo-tintoria grows well. Tall fescue and perennial ryegrass shows quick germination, but they could not inhibit the other species growing relatively slow. Pinus thunbergii used at Gonam near the ocean was suppressed by the other plants, so it can be concluded that using container seedlings is effective than seeding. 4. Ailanthus altissima, Albizzia julibrissin, Rhus chinensis Lespedeza cyrtobotrya, and Indigofera pseudo-tinctoria were germinated. In wild flowers, Coreopsis lanceolata, Dianthus sinensis, Coreopsis tinctoria, and Lotus corniculatus var. japonicus grew well and show enough plant height which will not suppressed by shrub and woody plants. After one year, native grasses such as Arundinella hirta, Miscanthus sinensis var. purpurascens and Imperata cylindrica var. koenigii cover the slopes well. 5. 25 herbaceous plants such as Trifolium repens, Arthraxon hispidus, Barbarea orthocerae, Potentilla fragarioides, Lepidium apetalum, Chenopodium album var. centrorubrum, Glycine soja, Rubus crataegifolius and 4 woody species such as Lespedeza maximowiczii, Robinia pseudoacacia, Symplocos Chinensis, Quercus acutissma were invaded. 6. Ecological restoration works by Natural Topsoil Restoration Methods for revegetation of the decomposed granite roadside cutslopes were successfully accomplished. It prevents surface water erosion and shows diverse vegetation structure. It will be successful to restore decomposed granite cutslopes.

• 한국조경학회지
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• 제33권6호
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• pp.51-77
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• 2006

Pond management is a critical part of overall golf course management, both during growth and maintenance modes of turf care. This study investigated 48 ponds in nine 18- or 27-hole golf courses to analyze the environmental characteristics of ponds. The research process had three phases: (1) inventory and analysis of grading plans and drainage plans, (2) field verification and interviews with greenskeepers, and (3) analyses of water quality and statistics. All data were collected from May to August in 2004. The results of this study can be summarized as follows: 1. It is desirable to site a golf course in a small watershed with high watershed eccentricity to control storm water runoff efficiently and to minimize soil erosion during construction. 2. The siting and size of a pond should be determined through a land-use analysis of the watershed for the purpose of ecological management. The bigger the forest-to-golf course ratio, the better the water quality will be. 3. The size and capacity of each individual ponds varied and there were many somewhat longish rather than round ponds. 4. There were many differences among golf courses in naturalness of the ponds, and the correlation between naturalness and area of aquatic plants was very high. 5. Analyses of pond water quality indicated that the degrees of Dissolved Oxygen, Chemical Oxygen Demanded and Suspended Solids were relatively low values but Total Phosphorus and Total Nitrogen were too high. Therefore a systematic approach is needed to solve e problem. Pesticide residues were not detected in all ponds. 6. Water depth and area of hydrophyte should be considered when designing an ecological pond. 7. All ponds used storm water as a main source of water supply and added underground water. Aquatic plants and physical methods such as water aeration and spray fountains were the main choices for maintaining a healthy aquatic environment.

• 예술인문사회 융합 멀티미디어 논문지
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• 제7권3호
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• pp.339-349
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• 2017

본 논문에서는 주행 중인 차량의 차선 인식을 위해 4단계로 구성된 알고리즘을 제안한다. 첫 번째 단계에서는 관심영역 추출한다. 두 번째 단계에서는 신호 잡음을 제기하기 위해 중간 값 필터를 이용한다. 세 번째 단계에서는 입력되는 이미지의 배경과 전경의 두 클래스로 구분하기 위한 이진화 알고리즘을 수행한다. 마지막 단계에서는 이진화 과정 후에 남아 있는 노이즈나 불완전한 에지 등을 제거하여 선명한 차선을 얻기 위해 이미지 침식 알고리즘을 이용한다. 하지만 이러한 차선 인식 앍고리즘은 높은 계산량을 요구하여 실시간 처리가 어려운 실정이다. 따라서 본 논문에서는 멀티코어 아키텍처를 이용하여 실시간 차선이탈 감지 알고리즘을 병렬구현 한다. 또한, 차선이탈 감지 알고리즘을 위한 최적의 멀티코어 아키텍처의 구조를 탐색하기 위해 총 8가지의 서로 다른 프로세싱 엘리먼트 구조를 이용하여 실험하였고, 모의실험 결과 40×40의 프로세싱 엘리먼트 구조에서 최적의 성능, 에너지 효율 및 면적 효율을 보였다.

• 한국환경복원기술학회지
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• 제8권3호
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• pp.1-12
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• 2005

A study on ecological restoration of landfill slope was conducted in Nanjido to compare immediate and long time effect and supply continuous back data for ecological restoration of landfill slope. As a result, all region constructed by SF and CODRA was effective on improving soil environment and preventing slope erosion. In case of former, by adapting flowers the initial scenery was beautifully built however there was tendency that as time passes the introduced plants were being overtaken by native plants thus it was necessary to select plants which are not being overtaken by native plants. In case of latter, by introducing leguminous plants the natural adaptation of plants were moving smoothly.

• Journal of Information Technology Applications and Management
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• 제22권3호
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• pp.143-167
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• 2015

This paper addresses the issue how the total life cycle cost may be minimized and how the cost should be allocated to the acquirer and developer. This paper differentiates post life cycle change (PLCC) endeavors from PLCC activities, rigorously classifies PLCC endeavors according to the result of PLCC endeavors, and rigorously defines the life cycle cost of a software product. This paper reviews classical definitions of software 'maintenance' types and proposes a new typology of PLCC activities too. The proposed classification schemes are exhaustive and mutually exclusive, and provide a new paradigm to review existing literatures regarding software cost estimation, software 'maintenance,' software evolution, and software architecture from a new perspective. This paper argues that the long-term interest of the acquirer is not protected properly because warranty period is typically too short and because the main concern of warranty service is given to removing the defects detected easily. Based on the observation that defects are caused solely by errors the developer has committed for software while defects are often induced by using for hardware (so, this paper cautiously proposes not to use the term 'maintenance' at all for software), this paper argues that the cost to remove defects should not be borne by the acquirer for software.