문영식 Mun Young-sik , 남원호 Nam Won-ho , 전민기 Jeon Min-gi , 김태곤 Kim Taegon , 홍은미 Hong Eun-mi , Michael J. Hayes , Tsegaye Tadesse

DOI:10.5389/KSAE.2019.61.2.001 JKWST Vol.61(No.2) 1-11, 2019

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Remote sensing products have long been used to monitor and forecast natural disasters. Satellite-derived rainfall products are becoming more accurate as space and time resolution improve, and are widely used in areas where measurement is difficult because of the periodic accumulation of images in large areas. In the case of North Korea, there is a limit to the estimation of precipitation for unmeasured areas due to the limited accessibility and quality of statistical data. CHIRPS (Climate Hazards Group InfraRed Precipitation with Stations) is global satellite-derived rainfall data of 0.05 degree grid resolution. It has been available since 1981 from USAID (U.S. Agency for International Development), NASA (National Aeronautics and Space Administration), NOAA (National Oceanic and Atmospheric Administration). This study evaluates the applicability of CHIRPS rainfall products for South Korea and North Korea by comparing CHIRPS data with ground observation data, and analyzing temporal and spatial drought trends using the Standardized Precipitation Index (SPI), a meteorological drought index available through CHIRPS. The results indicate that the data set performed well in assessing drought years (1994, 2000, 2015 and 2017). Overall, this study concludes that CHIRPS is a valuable tool for using data to estimate precipitation and drought monitoring in Korea.

이영학 Lee Young Hak , 이태호 Lee Tae Ho , 이달원 Lee Dal Won

DOI:10.5389/KSAE.2019.61.2.013 JKWST Vol.61(No.2) 13-23, 2019

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In this study, an overtopping model experiments and three dimensional seepage characteristics at the deteriorated homogeneous reservoirs were performed to investigate the behavior of failure for embankment and spillway transitional zone due to overtopping. The failure pattern, pore water pressure, earth pressure and settlement by overtopping were compared and analyzed. The pattern of the failure by overtopping was gradually enlarged towards reservoirs crest from the spillway transition zone at initial stage. In the rapid stage and peak stage, the width and depth of failure gradually increased, and the pattern of the failure appeared irregular and several direction of the erosion. In the early stage, the pore water pressure at spillway transitional zone was more affected as its variation and failure width increased. In the peak stage, the pore water pressure was significantly increased in all locations due to the influence of seepage. The earth pressure increased gradually according to overtopping stage. The pore pressure by the numerical analysis was larger than the experimental value, and the analysis was more likely to increase steadily without any apparent variation. The horizontal and vertical displacements were the largest at the toe of slope and at the top of the dam crest, respectively. The results of this displacement distribution can be applied as a basis for determining the position of reinforcement at the downstream slope and the crest. The collapse in the overtopping stage began with erosion of the most vulnerable parts of the dam crest, and the embankment was completely collapsed as the overtopping stage increased.

이서로 Lee Seoro , 이관재 Lee Gwanjae , 한정호 Han Jeongho , 이동준 Lee Dongjun , 김종건 Kim Jonggun , 임경재 Lim Kyoung Jae

DOI:10.5389/KSAE.2019.61.2.025 JKWST Vol.61(No.2) 25-39, 2019

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The water pollution Accident in the South Han River is increasing due to increase of pollutants inflow from small streams from rural areas and reduced flow rate. This study predicted the change of water quality in the main stream of the South Han River due to climate change through the linkage of watershed and water quality models. Also, This study analyzed the effect of water quality improvement on Seomgang and the South Han River by securing the flow during the dry season. According to the scenarios for securing the river flow during drought season, the river flow in the Seomgang is increased up to 2.19 times, and the water quality during the drought season was improved up to BOD5 20.5%, T-N 40.8%, T-P 53.4%. Also, the water quality of the main stream of the South Han River improved to 5.22% of BOD5, 5.42% of T-N and 7.69% of T-P as the river flow was secured from the Seomgang. The result of this study confirms that securing the baseflow in the Seomgang according to the scenarios for securing the river flow during the dry season has a positive effect on the improvement of the water quality of the rivers in the main river of the Seomgang and South Han River. The results of this study will contribute to the establishment of reasonable management to improve the water quality of the main stream of the Seomgang and South Han River.

김동주 Kim Dong-ju , 변용훈 Byun Yong-hoon

DOI:10.5389/KSAE.2019.61.2.041 JKWST Vol.61(No.2) 41-50, 2019

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Stiffness characteristic of subgrade is one of the most important aspects for the design and evaluation of pavement and railway. However, adequate field testing methods for evaluating the stiffness characteristics of the subgrade have not been developed yet. In this study, an in-situ dynamic stiffness analyzer (IDSA) is developed to evaluate the characteristics of subgrade stiffness along the depth, and its performance is evaluated in elastic materials and a compacted soil. The IDSA consists of a falling hammer system, a connecting rod, and a tip module. Four strain gauges and an accelerometer are installed at the tip of the rod to analyze the dynamic response of the tip generated by the drop of hammer. Based on the Boussinesq’s method, the stiffness and Young’s modulus of the specimens can be calculated. The performance of IDSA was tested on three elastic materials with different hardness and a compacted soil. For the repeatability of test performance, the dynamic signals for force and displacement of the tip are averaged from the hammer impact tests performed five times at the same drop height. The experimental results show that the peak force, peak displacement, and the duration depend on the hardness of the elastic materials. After calculating the stiffness and elastic modulus, it is revealed that as the drop height of hammer increases, the stiffness and elastic moduli of MC nylon and the compacted soil rapidly increase, while those of urethanes less increase.

김종봉 Kim Jongbong , 박주석 Park Jooseok , 정남수 Jung Namsu

DOI:10.5389/KSAE.2019.61.2.051 JKWST Vol.61(No.2) 51-61, 2019

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In this study, interest in rural life of good natural environment rather than busy life is increasing as human life is extended by scientific and medical technology and society has improved. The reckless development of rural villages has caused social problems as the natural environment has been damaged, failing to function as a pleasant home. To address these problems, the government has implemented a rural village development project, but if the site is selected incorrectly, the residents may not be recruited, or applicants may lose their status, or the portion of the infrastructure building fee may increase. In order to prepare objective and clear assessment methods for the target site not to cause such problems, a layering analysis method (AHP: Analytic Method) was used to identify the current status of the rural village formation project, draw assessment items, and determine the importance of each item.

김석현 Kim Seokhyeon , 김계웅 Kim Kyeung , 황순호 Hwang Soonho , 박지훈 Park Jihoon , 이재남 Lee Jaenam , 강문성 Kang Moonseong

DOI:10.5389/KSAE.2019.61.2.063 JKWST Vol.61(No.2) 63-74, 2019

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The objective of this study was to evaluate the influence of rainfall observation network on daily dam inflow using artificial neural networks(ANNs). Chungju Dam and Soyangriver Dam were selected for the study watershed. Rainfall and dam inflow data were collected as input data for construction of ANNs models. Five ANNs models, represented by Model 1 (In watershed, point rainfall), Model 2 (All in the Thiessen network, point rainfall), Model 3 (Out of watershed in the Thiessen network, point rainfall), Model 1-T (In watershed, area mean rainfall), Model 2-T (All in the Thiessen network, area mean rainfall), were adopted to evaluate the influence of rainfall observation network. As a result of the study, the models that used all station in the Thiessen network performed better than the models that used station only in the watershed or out of the watershed. The models that used point rainfall data performed better than the models that used area mean rainfall. Model 2 achieved the highest level of performance. The model performance for the ANNs model 2 in Chungju dam resulted in the R² value of 0.94, NSE of 0.94 NSEln of 0.88 and PBIAS of -0.04 respectively. The model-2 predictions of Soyangriver Dam with the R² and NSE values greater than 0.94 were reasonably well agreed with the observations. The results of this study are expected to be used as a reference for rainfall data utilization in forecasting dam inflow using artificial neural networks.

김솔희 Solhee Kim , 서교 Kyo Suh , 김유안 Yooan Kim , 김찬우 Chanwoo Kim , 정찬훈 Chanhoon Jung

DOI:10.5389/KSAE.2019.61.2.075 JKWST Vol.61(No.2) 75-83, 2019

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Using geographical indication, a type of source identification, can effectively promote local specialty agricultural products of superior quality, by identifying the specific geographic location or origin of the produce. Agricultural products can be registered using the geographical indication by describing the product’s relation to its geographical origin including the reputation and quality. However, this indication has no objective standards to qualify goods as agricultural specialty products. The purpose of this study is to suggest basic criteria to define the characteristics and criteria of agricultural specialties based on a quantitative evaluation method. To propose this basic standard, we used the proportion of arable land to denote the major production areas and the location quotient (LQ) index to grasp the extent of the specialty of a product. The results show that the average LQ values of registered agricultural products, particularly apples, pears, and garlic, are 3.26, 8.01, and 2.82, respectively. This indicates that they are more specialized than produce from other areas that have not registered for a geographical indication. Low LQ values were found in some areas with registered rice geographical indications, which are also more focused on their historical reputation as the main rice producing areas. Considering the agricultural specialty of products, the recommendation is that the producing proportion should be over 1% of the national scale and over 10% of the province scale, and the LQ value should be over 2.0. This recommendation is not a requirement, but the criteria can prove to be useful in identifying a higher range of specialized agricultural products.

오병욱 Oh Byung-wook , 이성원 Lee Seong-won , 김효철 Kim Hyo-cher , 서일환 Seo Il-hwan

DOI:10.5389/KSAE.2019.61.2.085 JKWST Vol.61(No.2) 85-95, 2019

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The internal environment in pig house is closely related to the animal productivity. In addition, it is important to consider a working environment inside the pig house due to high gas and dust concentrations. The poor working environment inside the pig house can cause health problems including respiratory diseases. To analyze the working environment, it is important to evaluate the ventilation efficiency to effectively remove harmful gases and dust. The purpose of this study is to develop a 3D CFD model to analyze the working environment in the pig house. CFD model was validated by comparing air temperature distributions between CFD computed and field measured data. The average air flow rate at the pig height was 40.1 % lower than the working height when incoming air was concentrated on upper layer by the installed ventilation system on the experimental pig house. Using the validated CFD model, the regional ventilation efficiency was computed by the TGD(tracer gas decay) method at the pig and working heights. There was a difference of ventilation efficiency on 14 % between the air stagnated section and the rest sections. Stagnated gas concentration can be effected by animal and human health.

조현경 Hyun Kyung Cho , 김상민 Sang Min Kim

DOI:10.5389/KSAE.2019.61.2.097 JKWST Vol.61(No.2) 97-104, 2019

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The purpose of this study was to establish the estimation method of irrigation water amount for sewage treated water reuse for agricultural purpose. To calculate the irrigation water amount, we adopted Penman-Monteith for potential evapotranspiration estimation and applied crop coefficient and irrigation efficiency factor. We developed the irrigation water amount calculation program using C language in Xcode environment. The target district for calculation is having 259 ha of agricultural land located near the Jinyeong Clear Water Circulation Center in Hanrim-myeon, Gimhae city. The meteorological data of the study area were obtained from Changwon weather station from 1986 to 2017. Calculated average and maximum of annual mean potential evapotranspiration were 2.72 mm/day and 6.22 mm/day, respectively. We used K-S (Kolmogorov-Smirnov) for goodness-of-fit test to find optimal probability distribution of annual mean and maximum evapotranspiration. As a result, the normal distribution was selected for the appropriate distribution. The annual mean and maximum potential evapotranspiration for 10-year return period by applying normal distribution were 2.88 mm/day and 6.76 mm/day, respectively. Assuming that the irrigation efficiency is 80%, the irrigation water requirement was calculated as 36.05 ㎥/ day/ha and 84.45 ㎥/day/ha, respectively, when annual mean and maximum potential evapotranspiration were applied. The actual irrigation water amount can be calculated by applying the crop coefficient and cropping days for the study area based on the developed irrigation water amount estimation program in this study.

장중석 Jang Jung Seok

DOI:10.5389/KSAE.2019.61.2.105 JKWST Vol.61(No.2) 105-115, 2019

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For 159 administrative areas, SPI(Standardized Precipitation Index), ARDI(Agricultural Reservoir Drought Index) and ARDIs(Agricultural Reservoir Drought Index Simulated) were developed and applied to analyze the characteristics of agricultural drought index and agricultural droughts. In order to identify hydrometeorological characteristics of agricultural droughts, SPI, ARDI and ARDIs were calculated nationwide, and the applicability was compared and examined. SPI and ARDI showed significant differences in time and depth of drought in both spatial and temporal. ARDI and ARDIs showed similar tendency of change, and ARDIs were considered to be more representative of agricultural drought characteristics. The results of this study suggest that agricultural drought is a problem to be solved in the medium and long term rather than short term due to various forms of development, complexity of development, and difficulty in forecasting. Therefore, it is concluded that a preliminary and systematic approach is needed in consideration of meteorological, hydrological and hydrometeorological characteristics rather than a fragmentary approach, and that an agricultural drought index is needed to quantitatively evaluate agricultural drought.