• 한국해안해양공학회지
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• 제2권2호
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• pp.96-103
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• 1990

A local Iribarren number is suggested for the universal use of breaker type classification, which relates the bed slope to the wave steepness, both being given from the breaking point. The existing Iribarren number uses the wave length at an offshore point, while the local Iribarren number uses the wave length at the breaking point so that it can imply any influences due to current interaction and diffraction. The modified form of Miche's breaking criterion includes 고 breaking parameter which may be related to the local Iribarren number. Using the modifiedform of Miche's criterion with the local Iribarren number, the inclusion of Doppler effect seems to describe well the wave breaking mechanism in a current-interacted flow on a sloping beach without any additional effects implemented.

• 설비공학논문집
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• 제18권7호
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• pp.603-611
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• 2006

A variety of schemes were sought for a mitigation of thermal stratification phenomenon in the branch piping of domestic nuclear power plant. Several mechanisms of thermal stratification occurrence were introduced in this paper. A number of factors were selected to find out the schemes for thermal stratification mitigation and the computational analysis were performed. The length of vertical branch piping, the diameter, the radius of curvature of the elbow, the direction of connection between main piping and branch piping, the slope of branch piping, the leakage flow rate, the installation of additional valve, the change of the 1st valve position and another branch piping connected with branch piping were mentioned as factors in this paper.

• 한국수자원학회논문집
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• 제44권6호
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• pp.471-476
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• 2011

In this study, a modified dispersion-correction scheme describing tsunami propagation on variable water depths is proposed by introducing additional terms to the previous numerical scheme. The governing equations used in previous tsunami propagation models are slightly modified to consider the effects of a bottom slope. The numerical dispersion of the proposed model replaces the physical dispersion of the governing equations. Then, the modified scheme is employed to simulate tsunami propagation on variable water depths and numerical results are compared with those of the previous tsunami propagation model.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.14-19
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• 2021

Aim of this research was to investigate the effects of Digital Elevation Model (DEM) for sensitivity analysis with two types of DEMs: 1 to 24,000 and 1 to 250,000 DEM. Another emphasis was given to the development of methodology for processing DEMs to create ArcGIS Pro and GRASS layers. This was done while developing water quality system modeling using DEMs which were used to model hydrological processes and SWAT model. Sensitivity analysis with DEMs resulted in different runoff volumes in the model simulation. Runoff volume was higher for the 1:24,000 DEM than 1:250,000 DEM, probably due to the finer resolution and slope which increased the estimated runoff from the watershed. Certainly the DEMs were factors in precision of the simulations and it was obvious during sensitivity analysis that DEMs had significant effect on runoff volumes. We suggest, however, that additional comparative research could be conducted involving more parameters such as soil and hydrologic parameters to provide insight into the overall physical system which the SWAT model represents.

• 한국지열·수열에너지학회논문집
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• 제14권4호
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• pp.61-67
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• 2018

Solar energy depends on the altitude and azimuth of the sun, and the amount of energy collected on the slope depends on the latitude of the area being installed. However, since most solar heating systems are fixed to the ground, it is necessary to analyze the optimal installation angle from the early design stage. However, problems arise when energy consumption is not considered together because heating systems are not used in the summer In this study, the optimum installation angles of the solar collectors according to the latitude of the installation area are not simply determined by the amount of energy collected, but because the system is overheated due to climate change or energy usage patterns, And the amount of additional energy input.

• 한국환경복원기술학회지
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• 제15권2호
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• pp.103-115
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• 2012

To investigate the attributes of seed germination of the plants for greening of river bank slope, low-temperature treatment, chemical treatment, plant hormones treatment, and stratification were conducted using the seeds of 6 herbs growing naturally around river banks, such as Setaria glauca and faberii, Imperata cylindrica var. koenigii, Miscanthus sinensis, Pennisetum alopecuroides, Lespedeza cuneata and the seeds of 3 shrubs, such as Lespedeza bicolor., Rosa multiflora, Spiraea prunifolia for. simpliciflora. The findings are as follows. In case of herbs, Setaria glauca and faberii. have stone seeds. In the treatment with $H_2SO_4$, they were germinated through dormancy breaking, even though there were some differences depending on immersion time, and the germination rate of Setaria faberii was a bit higher than that of Setaria glauca. The germination rate of Imperata cylindrica var. koenigii was low in the treatment with $GA_3$, NAA, and the plant hormone, but the seed germination rate has improved and the germination rate of Miscanthus sinensis and Pennisetum alopecuroides showed the improved seed germination rate in low temperature treatment. In case of Lespedeza cuneata and bicolor, the leguminous plants, the treatment with $H_2SO_4$ was most effective for the improvement of seed germination and the decrease in germination time. Only Spiraea prunifolia for. simpliciflora, the rose among 3 woody plants showed the seed germination rate above 50% without any additional treatment. Thus, it was thought to be appropriate for greening. Rosa multiflora showed the attribute of germination in a dark condition at low temperature through stratification, despite its low germination rate. Based on the results as above, with respect to the greening using directly collected seeds, Miscanthus sinensis, Pennisetum alopecuroides, and Spiraea prunifolia for. simpliciflora are suitable for greening, because they do not need any additional treatment, and Lespedeza cuneata and bicolor are also suitable for greening because it is possible to improve the germination rate and reduce the germination time through the treatment on the seeds before sowing.

• 한국지형학회지
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• 제25권3호
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• pp.71-87
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• 2018

As part of further study on Gwangseungri coastal deposits which occurred at 10 ~ 15m above sea level and was analyzed as palaeo-coastal flood-type sediments, six burial ages of six additional samples from the two cross sections (KST1 and, KST2) near to the points of the past study were estimated and the geochemical analysis was performed. Further investigation on the cross section KST1 revealed a reversal of the burial age at the bottom of the section which was identified as palaeo-flooding sediments and supposed to have been buried about 350 years ago. At the lower part of the KST1, the burial age of the sediment layer was estimated to be 3,800 years. The lower part of KST2 sediments was identified as sediments that was formed about 6,600 years ago and about 20,000 years ago. Considering the inclination of the sediment layers, the coastal flooding sedimentsreported to have formed 700 years ago in the previousstudy are located at the top and the KST1 section analyzed in thisstudy seemed to be connected to the lower part. The chemical analysis showed that the relationship between these layers was not continuous but had a discontinuous characteristic influenced by a specific event, and the chemical composition also showed a rapid change. If we judge these together, the lowest part of Gwangseungrisediment layerseemed to have formed during the last glacial period but it was hard to find its origins clearly. On top of this layer, a fine sediment layer containing gravels was also formed.Itseemed thatsedimentation did not occur continuously, but was affected by temporary events in such a way that after a sediment layer was formed, it stopped. Since then, a coastal flooding event occurred about 700 years ago, and part of flooded sediments accumulated in the rear slope. After that, when a flood layer including additional granular materials about 350 years ago was formed, sedimentation along the slope seemed to have occurred.

• 한국산림과학회지
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• 제105권4호
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• pp.449-455
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• 2016

본 연구는 임도사업의 계획과 유지관리 단계에서 임도 관리자 집단의 의식성향을 파악하여 체계적인 임도 정책 수립을 위한 기초자료를 제공하기 위하여 수행하였다. 임도의 계획과 유지관리에 대한 설문조사 결과, 임도 노선의 계획시 고려사항으로는 육림작업, 산지재해 예방, 목재수확 등의 항목에서 높은 중요도를 보였으며, 간선임도에 대한 선호도가 가장 높게 나타났다. 또한 임도 유지관리 작업의 적절성에 대해서는 두 집단 모두 인력 및 예산부족으로 인한 어려움(92.9%)이 있다고 응답하였다. 임도의 개설로 우려되는 주요 피해형태로는 사면붕괴로 인한 인명피해, 사유지 통행에 대한 분쟁 등의 순으로 나타났으며, 현재 실행하고 있는 임도 유지 관리작업의 주요 내용으로는 배수시설의 정비와 노면정비가 높게 나타났다. 임도시설에 대한 주요 보완사항으로는 배수시설, 비탈면 녹화와 안정에 대한 응답이 높게 나타났다.

• 한국토양비료학회지
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• 제47권1호
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• pp.16-22
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• 2014

This study was conducted to determine the changes in soil chemical properties and the growth of seedling according to the different dredged soil improving methods at slope of Saemangeum sea dike. Undersea dredged soil was improved by five different methods. Seedlings of Ulmus davidiana var. japonica, Chionanthus retusa, Celtis sinensis, and Pinus thunbergii were planted after 9 month of experience site installation, then soil pH, NaCl concentration in soil, soil organic matter (SOM), and survival rate and height of seedling was measured. Initial soil pH was highest in the control plot but it decreased to the similar level with other soil improving plots after 35 months. There were no differences in NaCl concentration between the control and soil improving plots, and it showed decreasing tendency during the study period. In the control plot, initial SOM was lowest among that of other plots during the study period. The survival rate of 36 months after planting of P. thunbergii was highest among the species. The gap of the tree growth of P. thunbergii between the control plot and the soil improving plots was small, however, other species showed relatively higher tree height in the soil improving plots than the control plots. Creation forest with P. thunbergii might be a cost effective afforestation in coastal reclaimed land since it rarely needs additional improvement of dredged soil.

• Smart Structures and Systems
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• 제4권5호
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• pp.605-628
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• 2008

In bridge structures, damage may induce an additional deflection which may naturally contain essential information about the damage. However, inverse mapping from the damage-induced deflection to the actual damage location and severity is generally complex, particularly for statically indeterminate systems. In this paper, a new load concept, called the positive-bending-inspection-load (PBIL) is proposed to construct a simple inverse mapping from the damage-induced deflection to the actual damage location. A PBIL for an inspection region is defined as a load or a system of loads which guarantees the bending moment to be positive in the inspection region. From the theoretical investigations, it was proven that the damage-induced chord-wise deflection (DI-CD) has the maximum value with the abrupt change in its slope at the damage location under a PBIL. Hence, a novel damage localization method is proposed based on the DI-CD under a PBIL. The procedure may be summarized as: (1) identification of the modal flexibility matrices from acceleration measurements, (2) design for a PBIL for an inspection region of interest in a structure, (3) calculation of the chord-wise deflections for the PBIL using the modal flexibility matrices, and (4) damage localization by finding the location with the maximum DI-CD with the abrupt change in its slope within the inspection region. Procedures from (2)-(4) can be repeated for several inspection regions to cover the whole structure complementarily. Numerical verification studies were carried out on a simply supported beam and a three-span continuous beam model. Experimental verification study was also carried out on a two-span continuous beam structure with a steel box-girder. It was found that the proposed method can identify the damage existence and damage location for small damage cases with narrow cuts at the bottom flange.