이정재 Lee Jeongjae , 한이철 Han Yicheol , 이성우 Lee Seong Woo

DOI: JKWST Vol.53(No.1) 1-7, 2011

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The nature of a network implies movement among vertices, and can be regarded as flows. Based on the flow concept which network follows the hydraulic fluid principle, we develop a spatial network model using Bernoulli equation. Then we explore the organization of spatial network and growth by the velocity of network flows. Results show that flow velocity determines network connections or influence of a vertex up to a point, and that the overall network structure is the result of pull force (pressure) and flow velocity. We demonstrate how one vertex can monopolize connections within a network.

이형진 Lee Hyungjin , 정남수 Jung Namsu , 문운경 Moon Woonkyung , 이정재 Lee Jeongjae

DOI: JKWST Vol.53(No.1) 9-15, 2011

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Highly pathogenic avian influenza could not be identified visually. It takes time to identify the symptoms by its incubation period. Without taking a quick step, the diffusion area of HPAI has dramatically increased, the extent of damage becomes bigger. In network research, the algorithm of finding the central node on the network applied to various diffusion of epidemic problems, was used in control system of tracing the diffusion path, blocking central nodes. This study tried to make the diffusion of HPAI network model for the crowded farms area, and reduce the diffusion rate to control the high-risk farms.

노재경 Noh Jaekyoung

DOI: JKWST Vol.53(No.1) 17-28, 2011

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This study was performed to ascertain the possibility of securing inflows to reservoir with low ratio of watershed to paddy field areas by outside diversion weir. The case of Maengdong reservoir and Samryong diversion weir was selected. Most of inflows to Maengdong reservoir with watershed area of 7.06 ㎢ and total storage capacity of 1,269×10⁴ ㎥ are filled with intake water from outside Samryong diversion weir. Only using water storage data in Maengdong reservoir from 1991 to 2009, the range of water intake in Samryong diversion weir to Maengdong reservoir was optimized to 0.135～30 mm/d, from which water intake to Maengdong reservoir was 1,672.9×10⁴ ㎥ (70.1 %) and downstream outflow to Weonnam reservoir was 714.4×10⁴ ㎥ (29.9 %). The parameters of DAWAST model for reservoir inflow were determined to UMAX of 313.8 mm, LMAX 20.3 mm, FC 136.8 mm, CP 0.018, and CE 0.007. Inflows to Maengdong reservoir were 427.1×10⁴ ㎥ (20.3 %) from inside watershed, and 1,672.9×10⁴ ㎥ (79.7 %) from outside. Paddy irrigation water requirements were estimated to 1,549×10⁴ ㎥ on annual average. Operation rule curve was drawn by using daily inflow and irrigation requirement data. By securing the amount of inflow to Maengdong reservoir to about 80 % from outside Samryong diversion weir, water supply capacity for irrigation of 1,549×10⁴ ㎥/yr was analyzed to be enough. Additional water supplies for instream flow were analyzed to 1,412 ㎥/d in normal reservoir operation, 36,000 ㎥/d in withdrawal limit operation by operation rule curve from October to March of non irrigation period.

서일환 Seo Il Hwan , 이인복 Lee In Bok , 문운경 Moon Oun Kyung , 홍세운 Hong Se Woon , 황현섭 Hwnag Hyun Seob , J. P. Bitog , 권경석 Kwon Kyeong Seok , 김기연 Kim Ki Youn

DOI: JKWST Vol.53(No.1) 29-36, 2011

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HPAI (High pathogenic avian influenza) which is a disease legally designated as an epidemic generally shows rapid spread of disease resulting in high mortality rate as well as severe economic damages. Because Korea is contiguous with China and southeast Asia where HPAI have occurred frequently, there is a high risk for HPAI outbreak. A prompt treatment against epidemics is most important for prevention of disease spread. The spread of HPAI should be considered by both direct and indirect contact as well as various spread factors including airborne spread. There are high risk of rapid propagation of HPAI flowing through the air because of collective farms mostly in Korea. Field experiments for the mechanism of disease spread have limitations such as unstable weather condition and difficulties in maintaining experimental conditions. In this study, therefore, computational fluid dynamics which has been actively used for mass transfer modeling were adapted. Korea has complex terrains and many livestock farms are located in the mountain regions. GIS numerical map was used to estimate spreads of virus attached aerosol by means of designing three dimensional complicated geometry including farm location, road network, related facilities. This can be used as back data in order to take preventive measures against HPAI occurrence and spread.

이지원 Lee Jiwon , 엄재성 Eom Jae Sung , 김범철 Kim Bomchul , 장원석 Jang Won Seok , 류지철 Ryu Ji Chul , 강현우 Kang Hyunwoo , 김기성 Kim Ki-sung , 임경재 Lim Kyoung Jae

DOI: JKWST Vol.53(No.1) 37-45, 2011

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Mandae watershed in Gangwon province has been known as one of soil erosion hot spot watersheds within Hanggang basin. Thus numerous efforts have been made to reduce soil erosion and pollutant loads into receiving watershed. However, proper best management practices have not been suggested because no monitoring flow and water quality data were available. Thus, modeling technique could not be utilized to evaluate water quality issue properly at Mandae watershed to develop and implement the best management practices. In this study, the SWAT model was applied to the Mandae watershed, Gangwon province to evaluate the SWAT prediction ability and water quality improvement with vegetated filter strip (VFS)　in this study. The Nash-Sutcliffe model efficiency (NSE) and Coefficient of determination (R²) values for flow simulation were 0.715 and 0.802, respectively, and the NSE and R² values were 0.903 and 0.920 for T-P simulation indicating the SWAT can be used to simulate flow and T-P with acceptable accuracies. The SWAT model, calibrated for flow and T-P, was used to evaluate water quality improvement with the VFS in agricultural fields. It was found that approximately 56.19 % of T-P could be reduced with vegetated filter strip of 5 m at the edge of agricultural fields within the watershed (34.86 % reduction with VFS of 1m, 48.29 % with VFS of 3 m). As shown in this study, the T-P, which plays key roles in eutrophication in the waterbodies, can be reduced with proper installation of the VFS.

은코모제피템바 Nkomozepi Temba , 정상옥 Chung Sang-ok

DOI: JKWST Vol.53(No.1) 47-55, 2011

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이주용 Lee Joo Yong , 김선주 Kim Sun Joo

DOI: JKWST Vol.53(No.1) 57-62, 2011

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Block Grants System to the agriculture sector has been started from 2010. This paper has been studied for the effective Integrated Rural Development under Block Grants System. For this, project evaluation items and indicators (PEI) were studied by internal and external example and specialist questionnaire on project evaluation. As the result of study, necessity of project, faith of project, efficiency of project, utilization of resources and operating capability were established in planning step, and most important PEI was established the necessity of project. And in enforcement step, performance result, monitering, capability, achievement and maintenance were established, and most important PEI was established performance results. Finally, monitering, capability, achievement and maintenance were established in completion step.

박기영 Park Ki Young , 임병란 Lim Byung-ran , 이기세 Lee Kisay , 이수구 Lee Soo Koo

DOI: JKWST Vol.53(No.1) 63-69, 2011

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The green algae Scenedesmus acuminatus was cultured in different media: animal wastewater and an artificial culture medium in order to evaluate potential use for tertiary treatment. The experiments were conducted with air flowrate 1～2 L/min at 28～30 °C. The nitrogen and phosphorus showed very similar removal efficiencies (68～77 % and 69～80 % for nitrogen and phosphorus respectively). The optimal fed period was estimated as three days in the semi-continuous experiment. The effects of CO₂ (4.5 %) injection on nutrient uptake from animal wastewater (biological treatment effluent) were compared to an air injection under the same conditions of light and photoperiod. The uptake rates of nutrient with air injection were observed 0.009 gN/gChl-a/day, 0.028 gN/gChl-a/day and T-P 0.003 gP/gChl-a/day for nitrate, total nitrogen and phosphorus respectively. The rates were enhanced by addition of CO₂ to 0.026 gN/gChl-a/day, 0.076 gN/gChl-a/day and T-P 0.018 gP/gChl-a/day. This study establishes that CO₂ addition during nutrient deprivation of microalgal cells may accelerate tertiary wastewater treatment.

금동혁 Kum Donghyuk , 최재완 Choi Jaewan , 김익재 Kim Ik Jae , 공동수 Kong Dong Soo , 류지철 Ryu Jichul , 강현우 Kang Hyunwoo , 임경재 Lim Kyoung Jae

DOI: JKWST Vol.53(No.1) 71-81, 2011

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Due to increased human activities and intensive rainfall events in a watershed, soil erosion and sediment transport have been hot issues in many areas of the world. To evaluate soil erosion problems spatially and temporarily, many computer models have been developed and evaluated over the years. However, it would not be reasonable to apply the model to a watershed if topography and environment are different to some degrees. Also, source codes of these models are not always public for modification. The ArcGIS model builder provides ease-of-use interface to develop model by linking several processes and input/output data together. In addition, it would be much easier to modify/enhance the model developed by others. Thus, simple model was developed to decide soil erosion hot spot areas using ArcGIS model builder tool in this study. This tool was applied to a watershed to evaluate model performance. It was found that sediment yield was estimated to be 13.7 ton/ha/yr at the most severe soil erosion hot spot area in the study watershed. As shown in this study, the ArcGIS model builder is an efficient tool to develop simple models without professional programming abilities. The model, developed in this study, is available at http://www.EnvSys.co.kr/~sateec/toolbox for free download. This tool can be easily modified for further enhancement with simple operations within ArcGIS model builder interface. Although very simple soil erosion and sediment yield were developed using model builder and applied to study watershed for soil erosion hot spot area in this study. The approaches shown in this study provides insights for model development and code sharing for the researchers in the related areas.