• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.2
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• pp.125-137
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• 1997

We are concerned with the packing policy determines the optimal packing of products with variable sizes to minimize the penalty costs for idle space and product spliting. Optimal packing problem is closely related to the optimal packet/record sizing problem in that randomly generated data stream with variable bytes are divided into a unit of packet/record for transmitting or storing. Assuming the product size and the production period are independently determined by renewal process, we can approximate the renewal process and formulate the optimization problem that minimize the expected packing cost for a production period. The problem is divided into two cases according to whether a product is allowed to split or not. Computational results for various distributions will be given to verify the approximation procedure and the resulting optimization problem.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.875-886
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• 1994

This study is to develop an advanced storm runoff analysis program which takes geomorphological characteristics of watershed into consideration in determining model parameters. Basic concept of storm runoff modelling is based upon the kinematic wave theory. And numerical solution is obtained by the characteristic curve method. The storm runoff analysis program developed by this study is composed of multiple equivalent roughness sub-basins, each of which has two equivalent catchments on both side of a stream. Because it is based upon the stream-order of the Strahler system, the equivalent catchment-stream network reflects the stochastic geomorphological characteristics in the model parameter. Applicability and reliability of the storm runoff analysis program is evidenced by model calibration and verification process utilizing geographical and hydrological data of the Bocheong-river area which is a representative watershed of IHP projects in Korea. This study will hopefully contribute to hydrological calculation essentially required to understand water quality effect caused by regional development.

• Economic and Environmental Geology
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• v.29 no.5
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• pp.597-613
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• 1996

The tonnage of copper and tungsten produced at Dalseong mine by Taehan Tungsten Mining Company from 1961 to 1971 was 48,704 tons (M/T) of 4 wt.% Cu and 1,620 tons (S/T) of 70wt.% WO, but the mine was closed in 1974. Kyeongsan mine is a small abandoned cobalt mine with no data of production. To investigate the pollution level of the mine areas, soils, plants (Ohwi and Pampanini), stream waters and stream sediments were taken and Fe, Mn, Cu, Pb, Zn, Ni, Co, Cd and Cr were analysed by ICP. Soils are considerably contaminated by the heavy metals related to ore deposits, The heavy metal contents in plants vary with the species and parts of plants. Stream waters are anomalously high in heavy metals in the vicinity of the mines but the contents decrease downstream in the process of dilution and precipiation. However, heavy metal contents increase very high in stream sediments due to precipiation. To protect environmental damages caused by acid mine drainages wetlands must be constructed outside pits, and it is necessary to fill pits with waters, limestone chips and organic materials, which give reducing and alkaline condition to ores. Under the condition pyrite is protected from oxidation and aqueous iron sulphates precipitate to form stable secondary pyrite.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.6
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• pp.101-112
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• 2013

Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) offers opportunities to make advances in many research areas including hydrology by providing near-global scale elevation measurements at a uniform resolution. Its wide coverage and complimentary online access especially benefits researchers requiring topographic information of hard-to-access areas. However, SRTM DEM also contains inherent errors, which are subject to propagation with its manipulation into analysis outputs. Sensitivity of hydrologic analysis to the errors has not been fully understood yet. This study investigated their impact on estimation of hydrologic derivatives such as slope, stream network, and watershed boundary using Monte Carlo simulation and spatial moving average techniques. Different amount of the errors and their spatial auto-correlation structure were considered in the study. Two sub-watersheds of Geum and Deadong River areas located in South and North Korea, respectively, were selected as the study areas. The results demonstrated that the spatial presentations of stream networks and watershed boundaries and their length and area estimations could be greatly affected by the SRTM DEM errors, in particular relatively flat areas. In the Deadong River area, artifacts of the SRTM DEM created sinks even after the filling process and then closed drainage basin and short stream lines, which are not the case in the reality. These findings provided an evidence that SRTM DEM alone may not enough to accurately figure out the hydrologic feature of a watershed, suggesting need of local knowledge and complementary data.

• Journal of Integrative Natural Science
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• v.7 no.1
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• pp.57-61
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• 2014

This study measured the stream data from the several sensors, and stores the database in MapReduce framework environment, and it aims to design system with the small performance and cluster analysis error rate through the KMSVM algorithm. Through the KM-SVM algorithm, the cluster analysis effective data was used for U-health system. In the results of experiment by using 2003 data sets obtained from 52 test subjects, the k-NN algorithm showed 79.29% cluster analysis accuracy, K-means algorithm showed 87.15 cluster analysis accuracy, and SVM algorithm showed 83.72%, KM-SVM showed 90.72%. As a result, the process speed and cluster analysis effective ratio of KM-SVM algorithm was better.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.40-49
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• 2017

In this study, we have made the annual total phosphorus (TP) mass balance diagrams for I wastewater treatment plant by utilizing the data of flow rate and TP of each process and tried to choose the optimum unit process empirically for phosphorus recovery. For the applicability evaluation, we have suggested several quantitative indices of flow rate, TP concentration, TP load and SS. Based on the analyses of TP mass balance, it became clear for reducing TP load of the wastewater treatment plant that it is efficient to recover phosphorus from the side stream in which the amount of flow rate is just 1/16, but TP concentration and load are 78 and 4.8 times larger than those of the influent of the plant. After the detailed applicability evaluation for the side stream, it could be concluded that the unit process of waste activated sludge thickener supernatant or dehydration filtrate are appropriate. Meanwhile, we did fundamental experiments utilizing the dewatering filtrate with TP concentration of 141.5 mg/L. After adjusting pH 10 and $Ca^{2+}$ concentration 250, 500, 1000 mg/L, it was stirred slowly. As a result, the $PO_4-P$ and TP removal efficiencies were above 95 percent; the results of the experiment imply the applicability of phosphorus recovery process in a wastewater treatment plant strongly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.9
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• pp.1470-1479
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• 1997

In this study, the plastic fan with high efficiency and low noise was designed and the capacity of the wind and the wind pressure were analysed and verified by CAE. After designing the metallic mold using the metallic mold design data, and the the metallic mold design was reformed by analysing the process of the material stream and injection filling by CAE. Also the metallic mold cutting data were formed using the metallic mold design data. These cutting data was used to produce the fan electrode by a machining center and then this electrode were used to manufacture the metallic mold by cutting the fan cavity by an electrical spark machine. The purpose of this study is to find out the sub-optimal condition on the productivity and improvement in quality of the plastic fan by integrating a series of this process with a computer.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.2
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• pp.93-107
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• 2008

Recently, there have been many projects regarding restoration of streams to recover their environmental and ecological functions. For the restoration of streams, it is valuable academically and economically to evaluate the ecological condition of streams and build a plan and an object for restoring streams based on that. On the other hand, one of the methods to figure out the ecological condition of streams is to evaluate the hydromorphological structure of stream. In this study we have developed a field survey system using the stream assessment methode of LAWA (Laenderarbeitsgemeinschaft Wasser in Germany) that can assess the hydromorphological structure of small and medium streams. In addition, we constructed a GIS-based stream assesment system which can support auto mapping system and report writing, using the survey results. These systems are aimed to help people in the area of restoring streams perceive the natural and ecological condition of streams in the process of making plans and managing the projects, and they also try to help in collecting raw data to determine an ideal potential model to which an existing stream should be turned.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.670-679
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• 2011

Chlorophyll-a is a major water quality indicator for an algal bloom in streams and lakes. The purpose of the study is to estimate chlorophyll-a concentration in tributaries of the Seonakdonggang by an artificial neural network (ANN). As the tributaries are ungauged streams, a watershed runoff and quality model was used to simulate water quality parameters. The tributary watersheds include urban area and thus Storm Water Management Model (SWMM) was used to simulate TN, TP, BOD, COD, and SS. SWMM, however, can not simulate chlorophyll-a. The chlorophyll-a series data from the tributaries were estimated by the ANN and the simulation results of water quality parameters using SWMM. An assumption used is as follows: the relation between water quality parameters and chlorophyll-a in the tributaries of the Seonakdonggang would be similar to that in the mainstream of the Seonakdonggang. On the assumption, the measurement data of water quality and chlorophyll-a in the mainstream of the Seonakdonggang were used as the learning data of the ANN. Through the sensitivity analysis, the learning data combination of water quality parameters was determined. Finally, chlorophyll-a series were estimated for tributaries of the Seonakdonggang by the ANN and TN, TP, BOD, COD, and temperature data from those streams. The relative errors between the estimated and measured chlorophyll-a were approximately 40 ~ 50%. Though the errors are somewhat large, the estimation process for chlorophyll-a may be useful in ungauged streams.

• Journal of Creative Information Culture
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• v.6 no.1
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• pp.41-48
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• 2020

In order to represent and process spatial data, hierarchical data structures such as a quadtree or a bintree are used. Various approaches for linearly representing the bintree have been proposed. S-Tree has the advantage of compressing the storage space by expressing binary region image data as a linear binary bit stream, but the higher the resolution of the image, the longer the length of the binary bit stream, the longer the storage space and the lower the search performance. In this paper, we construct a hierarchical structure of multiple separated bintrees with a full binary tree structure and express each bintree as two linear binary bit streams to reduce the range required for image search. It improves the overall search performance by performing a simple number conversion instead of searching directly the binary bit string path. Through the performance evaluation by the worst-case space-time complexity analysis, it was analyzed that the proposed method has better search performance and space efficiency than the previous one.