• Korean Journal of Remote Sensing
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• v.33 no.6_3
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• pp.1223-1232
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• 2017

This paper presents an approach to detect changes caused by urban development over a large area using KOMPSAT optical images. In order to minimize the radiometric dissimilarities between the images acquired at different times, we apply the grid-based rough radiometric correction as a preprocessing to detect changes in a large area. To improve the accuracy of the change detection results for urban development, we mask-out non-interest areas such as water and forest regions by the use of land-cover map provided by the Ministry of Environment. The Change Vector Analysis(CVA) technique is applied to detect changes caused by urban development. To confirm the effectiveness of the proposed approach, a total of three study sites from Sejong City is constructed by combining KOMPSAT-2 images acquired on May 2007 and May 2016 and a KOMPSAT-3 image acquired on March 2014. As a result of the change detection accuracy evaluation for the study site generated from the KOMPSAT-2 image acquired on May 2007 and the KOMPSAT-3 image acquired on March 2014, the overall accuracy of change detection was about 91.00%. It is demonstrated that the proposed method is able to effectively detect urban development changes in a large area.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.6
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• pp.374-378
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• 2008

For the standard method of collecting the run-off, it is consumed the high cost and much effort to install and to manage this instrument. Because the all the soil and water from reservoir tank must be eliminate after their measurement of amount of soil loss and run-off and installed the reservoir tank at regular size in the experimental field. Therefore, objective of this study was to compare its efficacy between the standard method and a flow rotate divider for ontinuously collecting and measuring the soil loss and run-off in order to conveniently conduct the field experiment of the lysimeters. For collecting the sampling of soil loss and run-off from agricultural land with invariable ratio, a flow rotate divider was consisted with a 8 blades of round plate sloped in order to collect the invariable ratio of soil and water at lowest part from round plate by the law of gravity. For comparing its accuracy in the batch scale experiment, it shown that there was significantly a positive linear corelation ($r=0.997^{***}$) between flowing and sampling amounts with adjusting the range from 1 to $10L\;min^{-1}$ with flowing rate. In collecting ratio in the field experiment, it observed that the more its accuracy had, the more soil loss and run-off.

• Journal of Korea Water Resources Association
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• v.44 no.11
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• pp.863-873
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• 2011

It has been known that soil erosion caused by water has been a serious problem worldwide. Thus various modeling techniques for conservationists, farmers, and other land users have been developed and utilized to estimate effects of numerous site-specific Best Management Practices on soil erosion reduction. The physical process-based WEPP model would provide both temporal and spatial estimates of soil loss within small watersheds and for hillslope profiles within small watersheds. Thus, the WEPP watershed version was applied to study watershed, located at Jawoon-ri, Gangwon to simulate diversion ditch and vegetated swale with detailed input data set. The sediment yield and runoff reduction rates reduced by 5.8% and 29.6% with diversion ditch and 9.8% and 14.5% with vegetated swale. With vegetated diversion ditch, runoff and sediment yield could be reduced by 11.8% and 40.4%, respectively. Based on the results obtained in this study, the WEPP model would be an useful tool to measure runoff and sediment yield reduction and establish site-specific sediment reduction best management plan.

• Journal of Korea Water Resources Association
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• v.45 no.11
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• pp.1169-1186
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• 2012

Storage function method has been used for flood forecasting in the major rivers in Korea, however, the researches on the relationship between the parameters and runoff characteristics was not sufficient. In addition, there has been a controversy about the optimized parameters without the consideration of the physical characteristics of the basin. Therefore, in this study, the SCE-UA method is used to optimize the parameters and the proposed method was applied with two stage optimization in the Jeongseon and Yeongwol watersheds located in the most upstream in the South Han river. The contour map was developed to investigate parameters and the error surface calculated from the runoff. The proposed parameters is to provide a range of the possible parameter set in a watershed, rather than a specific value. However, the applicability is examined using the average value of the proposed ranged parameters. In this study, the criticism about the optimization technique to find an optimal value having no physical meaning on a watershed is tried to avoid. The objective of this study is to provide a range of parameters for the flood forecasting model and the intuition about the behavior of the parameters, so the efficiency of flood forecasting is increased.

• Journal of Korea Water Resources Association
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• v.42 no.6
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• pp.493-503
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• 2009

Estimation of the mean-field bias of radar rainfall is to determine the difference between the areal means of radar and rain gauge rainfall, where the rain gauge rainfall is assumed to be the truth. To exactly determine this bias, the variance of the difference between two observations must be small enough, thus, enough number of observations is indispensible. So, the problem becomes to determine the number of rain gauges to satisfy the level of variance of the difference between two observations. Especially, this study focuses on the case when the rain gauges are disproportionate spatially. This is the problem for the Ganghwa rain radar for the observation of rainfall within the Imjin river basin and the same problem also occurs when a radar is located in between land and ocean. This study considered the Imjin river basin, and compared two cases when rain gauges are available only within the downstream part, about one third of the whole basin, and over the whole basin. Based on the results derived, the rain gauge density within the downstream part of the Imjin river basin was proposed to secure the same accuracy obtained when the rain gauges are available over the whole Imjin river basin.

• Journal of Korea Water Resources Association
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• v.49 no.12
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• pp.1027-1034
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• 2016

One of the most important purpose of multi-purpose reservoir is storing a large amount of water for utilization in a dry season. However, multi-purpose reservoirs that were constructed according to the limited hydrologic information available at the time of construction may encounter problems such as decreased water inflow due to climate change and an inability to cope with a water shortage. To solve these problems, in 2015, the Ministry of Land, Infrastructure and Transport suggested a revised water supply standard in case of water shortage for reservoirs. However, the revised standard has not been sufficiently discussed to determine its effectiveness. In addition, multi-purpose reservoirs in South Korea have secured and stored water for emergencies, but there is currently no way to utilize the stored water. Determining how to utilize the stored water effectively may be a useful method for preparing drought. Therefore, this article discusses the revised water supply standard as it relates to a water shortage in reservoirs and a method of utilizing the water stored for emergencies in multi-purpose reservoirs. The options for utilizing the water storage were evaluated using a water shortage safety degree index, and the results showed that the options may slightly and limitedly increase the water supply capacity. However, the evaluation also showed that a complex application of two options may overcome the exisiting problem and to supply water more effectively.

• Journal of Cadastre & Land InformatiX
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• v.46 no.2
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• pp.183-196
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• 2016

Ground control points are needed for precision geometric correction of satellite images, and the coordinates of a high-quality ground control point can be obtained from the GPS measurement. However, considering the GPS measurement requires an excessive amount o f t ime a nd e fforts, there is a need for coming up with an alternative solution to replace it. Therefore, we examined the possibility of replacing the existing GPS measurement with coordinates available at online maps to acquire the coordinates of ground control points. To this end, we examined error amounts between the coordinates of ground control points obtained through Daum Map API, and them compared the accuracies between three types of coordinate transformation equations which were used for geometric correction of satellite images. In addition, we used the coordinate transformation equation with the highest accuracy, the coordinates of ground control point obtained through the GPS measurement and those acquired through D aum M ap A PI, and conducted geometric correction on them to compare their accuracy and evaluate their effectiveness. According to the results, the 3rd order polynomial transformation equation showed the highest accuracy among three types of coordinates transformation equations. In the case of using mid-resolution satellite images such as those taken by Landsat-8, it seems that it is possible to use geometrically corrected images that have been obtained after acquiring the coordinates of ground control points through Daum Map API.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.91-91
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• 2011

폴리프로필렌(PP)은 고결정성 범용수지로서 염색성, 내열성, 촉감 등의 문제로 의류용 소재로는 부적합하여 초기에는 카펫용 섬유로서 가염형 폴리프로필렌 섬유가 상업화 되었지만 성공하지는 못하였다. 그 후, 섬유 산업도 의류용 외의 산업자재, 생활 자재 분야 등이 성장함에 따라, 폴리프로필렌 섬유의 수요가 확대되었다. 최근들어 스포츠 액티브 의류가 일반의류 트렌드로 들어오면서 기능성 섬유가 요구되고 이 분위기에 맞춰 다시 한번 폴리프로필렌 섬유의 의류화가 요구되는 시점이 되었으며 섬유중 에너지 소비량이 가장 적고, 쉽게 재용해할 수 있으며 소각시 유해 가스발생량이 매우 적은 특징등이 있기 때문에 지구 환경보호의 입장에서 폴리프로필렌 섬유가 재검토되고 있다. 이번 실험은 분산염료를 이용하여 농도별, 온도별, 시간별, 후처리시 시간과 온도의 변화로 가염 PP/PET 섬유의 염색특성을 알아보기 위해 실험 진행하였다. 실험에 사용되는 시약은 1급으로, $CH_3COOH$, NaOH, $Na_2S_2O_4$이며, 조제는 분산제, 정련제를 사용하였다. 먼저 온도별 실험에서 $40^{\circ}C$에서 승온하여 각각 $100^{\circ}C$, $110^{\circ}C$, $120^{\circ}C$, $130^{\circ}C$에서 온도에 따라 염색되는 정도를 알아보았다. 가장 높은 흡진을 보이는 온도에서 각각 40min, 50min, 60min, 70min 염색 유지시간 실험을 하여 염색이 안정되는 시간을 측정하였다. 위의 실험 결과 최적의 조건으로 염색농도에 따른 Build up 실험을 진행하였다. 가염 PP/PET 섬유는 일반 Polyester처럼 $120{\sim}130^{\circ}C$에서 가장 높은 염색농도 값(K/S)을 보인다. 또한 $130^{\circ}C$에서의 유지시간에서는 50 min 이상 진행시 더 이상의 흡진이 없거나, 염료의 탈락이 있음을 알수 있다. Build up 실험에서는 8.0%까지 실험하였지만, 결과는 그 이상농도를 사용하여도 염색은 가능함을 알 수 있었다. 후처리에 대한 실험에서 염료에 따라 차이가 있지만 크게 영향을 받지 않는 것으로 보이며, 제품성 평가 결과를 보면 후처리를 했을 경우 견뢰도가 우수한 것을 알 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.155-160
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• 2018

The unmanned aerial vehicle (UAV) is used in various fields, such as land surveying, facility management, and disaster monitoring and restoration because it has low operational costs, fast data acquisition, and can generate a digital surface model (DSM). Recently, the UAV has been applied to process management in construction projects. Construction projects are widely distributed not only in urban areas but also in mountainous areas and rural areas where people are rarely in traffic or in vehicles. Projects range from a few hundred meters to several kilometers long. In order to perform a reconnaissance survey, a surveying method using a global positioning system (GPS) or a total station has mainly been used. However, these methods have a disadvantage in that a lot of time is required for data acquisition. This study's purpose is to evaluate the usability of a UAV DSM for surveying a construction area. Data was acquired using the UAV and a three-dimensional (3D) laser scanner, and the DSM of the construction site was created through data processing. The UAV DSM showed accuracy to within 30 cm based on the 3D laser scanner data, and a process comparison between the two work methods was able to present the usability of the UAV DSM in the field of construction surveying. Future utilization of the UAV DSM is expected to greatly improve the efficiency of work in construction projects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.634-640
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• 2020

Failure analysis and heat-resistant were performed for an electric fuel pump that is installed in the fuel tank to transfer fuel to the engine of combat vehicles. The fuel pump with a DC motor was disassembled and inspected to determine the cause of failure. The failure phenomenon was classified into three categories based on observations of the inside of the housing: burnt winding, quick brush abrasion, and fuel leak into the pump. Based on the inspection results, it was estimated that overheating was the main cause of failure. The thermal test was conducted under the no-load condition in 24 hours, and the thermal sensor was installed on the stator surface and the brush holder to check the possibility of damage to the winding due to overheating. When the ambient temperature of the fuel pump was set to 68 ℃, the stator temperature increased to 135.9 ℃, and the winding of the motor was almost damaged. The test results confirmed the lack of heat resistance of fuel pump windings, and suggested that the type F of insulation class (below 155 ℃) of the windings and varnish should be replaced with type C or higher that can be used above 180 ℃.