이상현 Lee Sang-hyun , 오윤경 Oh Yun-gyeong

DOI: JKWST Vol.59(No.5) 1-15, 2017

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In this study, we visualized the regional migration in Korea from 2001 to 2015 using the Chord diagram which can represents amount of migration and flows at the same time. In addition, we constructed a migration network and analyzed the degree centrality of each region for identifying the main regions linking to various regions. In 2001~2005, most of population moved into Geonggi from various regions. However, the capital function was transferred to Sejong in 2011~2015, and population moving into Sejong and Chungnam was increased significantly. The main outflow of population in migration network were shown at the regions in Jeonbuk and Gyeongbuk province in 2001~2004, and recently the regions in Gyeongnam, Gyeonggi, and Seoul were identified as the main nodes in terms of outflow of population. We also focused on migration in rural area through degree centrality, and cord diagram in Chungnam, Jeonbuk, and Jeonnam where include the representative crop area. In 2015. there was the significant increase of migration from Gyeonggi to Chungnam, and internal migration within Jeonbuk increased rather than cross-border migration. In addition, migration from Jeonam to capital area decreased in 2015 but migration among cities within Jeonman increased. In particular, Yesan-gun showed the significant migration to other cities in Jeonnam. Population is necessary to develop community and sustain economic growth in rural regions. Therefore, migration is important for the transfer of manpower. The strength of this study is to approach the temporal change of migration from the viewpoint on quantitative and structural characteristics.

윤여성 Yoon Yeo Seong , 강구 Kang Ku , 박성직 Park Seong Jik , 홍성구 Hong Seong Gu

DOI: JKWST Vol.59(No.5) 17-23, 2017

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In South Korea, 25 % of annual agricultural residues (11.64 million tons) are unused. The hydrophilicity, low lower heating value (LHV), and low energy density of agricultural residues can be obstacles for efficient usage. Torrefaction, a low temperature pyrolysis process, can be a solution to overcome these disadvantage of agricultural residues. In this study, agricultural residues such as bean stem, pepper stem, perilla stem, sorghum stem, acorn shell, and ginkgo shell are torrefied at 200, 230, and 250 ℃ and evaluated energy properties, respectively. The torrefaction can increase the LHV and energy density rate of agricultural residues from 3,331~4,444 kcal/kg to 4,166~5,830 kcal/kg and 20~30 %, respectively.

한경화 Han Kyunghwa , 정강호 Jung Kangho , 조희래 Cho Heerae , 이협성 Lee Hyubsung , 옥정훈 Ok Junghun , 서미진 Seo Mijin , 장용선 Zhang Yongseon , 서영호 Seo Youngho

DOI: JKWST Vol.59(No.5) 25-30, 2017

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Hydrologic soil group is one of the important factors to determine runoff potential and curve number. This study was conducted to classify the hydrologic soil groups of Korean soils by considering saturated hydraulic conductivity and depth of impermeable layer. Saturated hydraulic conductivity of Korean soils was estimated by pedotransfer functions developed in the previous studies. Most of paddy soils were classified as D type due to shallow impermeable layer and low saturated hydraulic conductivity in B soil horizon. For upland and forest, soils classified to A and D types increased compared with former classification method because underestimated permeabilities and overestimated drainages were corrected and rock horizon in shallow depth was regarded as impermeable layer. Soils in mountainous land showed the highest distribution in A type, followed by D type. More than 60 % of soils in mountain foot-slope, fan and valley, alluvial plains, and fluvio-marine deposits were classified to D type because of land use such as paddy and upland.

신용훈 Shin Yong-hoon , 최진용 Choi Jin-yong , 이승재 Lee Seung-jae , 이성학 Lee Sung-hack

DOI: JKWST Vol.59(No.5) 31-40, 2017

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The aim of this study is to estimate net irrigation requirements for red pepper during growing period using soil moisture model. The soil moisture model based on water balance approach simulates soil moisture contents of 4 soil layers in crop root zone considering soil moisture extraction pattern. The LAMP (Land-Atmosphere Modeling Package) high resolution meteorological data provided from National Center for AgroMeteorology (NCAM) was used to simulate soil moisture as the input weather data. Study area for the LAMP data and soil moisture simulation covers 36.92°~37.40° in latitude and 127.36°~127.94° in longitude. Soil moisture was monitored using FDR (Frequency Domain Reflectometry) sensors and the data were used to validate the simulation model from May 24 to October 20 in 2016. The results showed spatially detailed soil moisture pattern under different weather conditions and soil texture. Net irrigation requirements were also different by location reflecting the spatially distributed weather condition. The average of the requirements was 470.7 mm and averages about soil texture were 466.8 mm, 482.4 mm, 456.0 mm, 481.7 mm, and 465.6 mm for clay loam, sandy loam, silty clay loam, clay, and sand respectively. This study showed spatial differences of soil moisture and the irrigation requirements of red pepper about spatially uneven weather condition and soil texture. From the results, it was demonstrated that high resolution meteorological data could provide an opportunity of spatially different crop water requirement estimation during the irrigation management.

구본운 Gu Bon-wun , 김문주 Kim Mun-ju , 박성직 Park Seong-jik

DOI: JKWST Vol.59(No.5) 41-49, 2017

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This study was aimed to investigate the influence of cation exchange capacity (CEC) and application amounts of zeolite on the stabilization of heavy metals (As, Ni, Pb, and Zn) in upland soils. The upland soils were sampled from field near mines located in Gyeonggi Province. The CEC of zeolite was treated at three different levels, ie, low, medium, and high, while zeolite was amended with soils at the ratio of 0.1 % and 0.5 % as to soil weight. A sequential extraction was performed for the soil sampled at 1, 2 4, and 8 week after zeolite was added to the soil. The concentrations of Pb and Zn appeared to be high in the sampled soils. The mobility of heavy metals obtained from sequential experiments was as follows: Pb > Zn > Ni >As. Addition of zeolite to contaminated soils effectively reduced exchangeable and carbonate fractions but increased organic and residual fraction, indicating that zeolite is effective for immobilizing heavy metals in soils. The influence of incubation time on the metal stabilization was rather pronounced as compared to the application amount and CEC of zeolite.

오현문 Oh Hyeonmun , 김정면 Kim Jungmeyon , 이응범 Lee Eungbeom , 임창수 Lim Changsu , 김용성 Kim Yongseong

DOI: JKWST Vol.59(No.5) 51-60, 2017

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This research is a basic study to minimize the risk of disaster (earthquakes and landslides) for rural residential houses. In this study, three-dimensional numerical analysis was performed by varying the diameter (D), thickness (T) and the spacing of longitudinal members (C.T.C) of duralumin and galvanized steel pipe as the materials of main members in order to carry out the analysis of the dimension and the applied load of shelter for disaster prevention, and to evaluate the eligibility of members that can satisfy safety and usability. From the evaluation results of the member eligibility by the above numerical analysis, it was found that duralumin has a great influence on the member diameter (D) and thickness (T), and in the case of galvanized steel pipe, its spacing of longitudinal members has a huge amount of influence over the member force, so it is considered that the duralumin and galvanized steel pipe materials can be used as materials for the main members of disaster prevention shelters in terms of safety and usability.

최현성 Choi Hyun Seong , 안세희 An Se Hee

DOI: JKWST Vol.59(No.5) 61-72, 2017

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The purpose of this study is to establish an integrated management system for the efficient management of rural water, to improve current problems, and to lay the foundations for active use of rural water information. We proposed a plan for informatization with a focus on establishing a database that can be used to provide customized services to users by applying advanced IT technology and to strengthen the management system of cities and counties with poor information. Data linkage and integration, user service development and integration system, application of IT technology, advanced decision support for rural water management, strengthening of city and county management system And the details of the implementation of the key project were presented.

유성열 Yoo Seong-yeoul , 전종찬 Jeon Jong-chan , 신형진 Shin Hyung-jin , 박찬기 Park Chan-gi

DOI: JKWST Vol.59(No.5) 73-81, 2017

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The improved movable weir supplements the advantages and disadvantages of the rubber weir and the conduction gate. It consists of a stainless steel gate, air bags, and a steel clamping plate. The stainless steel gate is the main body of the weir, and the inflatable rubber sheet serves to support the steel gate. The steel clamping plate is typically in direct continuous contact with water, but this leads to corrosion issues that can reduce the life of the entire movable weir. In this study, a panel-type glass-fiber-reinforced polymer (GFRP) clamping plate was designed and fabricated. The test results showed that the flexural load of the panel-type GFRP composite clamping plate was over twice that of the wings type GFRP clamping plate. The lowest moisture absorption value was obtained upon exposure to tap water, and exposure to other solutions showed similar values. Additionally, flexural load testing after exposure to an accelerated environment found the lowest residual loads of 80.51 % and 78.50 % at 50 and 100 days, respectively, for exposure to a CaCl₂ solution, while exposure to other environments showed residual failure loads of over 80 % at both 50 and 100 days.

김진영 Kim Jinyoung , 이성열 Lee Sungyeol , 최창호 Choi Changho , 강재모 Kang Jaemo , 강권수 Kang Kwonsoo , 정효진 Jeong Hyojin , 홍재철 Hong Jaecheol , 이재수 Lee Jaesoo , 백원진 Baek Wonjin

DOI: JKWST Vol.59(No.5) 83-91, 2017

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Recently, ground subsidence frequently occurs in downtown area. The major causes of the subsidence on the subsurface were the damages of the water supply and sewer pipelines and excavation works in adjacent areas, etc. Because of these various factors, it is not easy to analyze the tendency of occurrence of ground subsidence. The purpose of this study is to clarify the effect of ground subsidence by the change of the fine particle content and ground water level and to establish the ground subsidence mechanism. In this study, a model soil-box was manufactured to simulate the failure of the old sewer pipe which is one of the causes on ground subsidence. And a model test was conducted to investigate the effects of fine contents and ground water level on the cavity occurrence. From the test results, firstly the higher the ground water level, the faster the primary cavity is formed as the seepage stress increases. As a result, the secondary cavity and the ground subsidence rapidly progress due to the relaxation of the surrounding ground. The total amount of discharged soil was decreased as the fine content increased.

오우라비압둘하메드바바툰데 Abdulhameed B. Owolabi , 이종원 Jong W Lee , 메쓰캄카남즈사니카닐란가니자야세카라 Shanika N. Jayasekara , 이현우 Hyun W. Lee

DOI: JKWST Vol.59(No.5) 93-99, 2017

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A model was developed using Artificial Neural Networks (ANNs) based on Principal Component Analysis (PCA), to accurately predict the air humidity inside an experimental greenhouse located in Daegu (latitude 35.53°N, longitude 128.36°E, and altitude 48 m), South Korea. The weather parameters, air temperature, relative humidity, solar radiation, and carbon dioxide inside and outside the greenhouse were monitored and measured by mounted sensors. Through the PCA of the data samples, three main components were used as the input data, and the measured inside humidity was used as the output data for the ALYUDA forecaster software of the ANN model. The Nash-Sutcliff Model Efficiency Coefficient (NSE) was used to analyze the difference between the experimental and the simulated results, in order to determine the predictive power of the ANN software. The results obtained revealed the variables that affect the inside air humidity through a sensitivity analysis graph. The measured humidity agreed well with the predicted humidity, which signifies that the model has a very high accuracy and can be used for predictions based on the computed R² and NSE values for the training and validation samples.

박성용 Park Sung-yong , 정희돈 Jung Hee-don , 김영주 Kim Young-ju , 김용성 Kim Yong-seong

DOI: JKWST Vol.59(No.5) 101-108, 2017

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Recently, the occurrence of landslides has been increasing over the years due to the extreme weather event. Developments of landslides monitoring technology that reduce damage caused by landslide are urgently needed. Therefore, in this study, a strain ratio sensor was developed to predict the ground behavior during the slope failure, and the change in surface ground displacement was observed as slope failed on the field model experiment. As a result, in the slope failure, the ground displacement process increases the risk of collapse as the inverse displacement approaches zero. It is closely related to the prediction of precursor. In all cases, increase in displacement and reverse speed of inverse displacement with time was observed during the slope failure, and it is very important event for monitoring collapse phenomenon of risky slopes. In the future, it can be used as disaster prevention technology to contribute in reduction of landslide damage and activation of measurement industry.

유나영 Yu Na Young , 신민환 Shin Min Hwan , 김종건 Kim Jonggun , 박윤식 Park Youn Shik

DOI: JKWST Vol.59(No.5) 109-126, 2017

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Universal soil loss equation (USLE) is used to estimate soil loss solely or employed in any hydrologic models. Since soil erosion has been an issue in South Korea for decades, the Ministry of Environment enacted a law to regulate soil erosion in 2012, which is the Notification of topsoil erosion status. The notification is composed of preliminary and field investigations, the preliminary investigation suggests to use USLE and provides USLE factors. However, the USLE factors provided in the notification was prepared at least 10 years ago, therefore it is limited to reflect recent climate changes. Moreover the current yearly USLE approach does not provide an opportunity to consider seasonal variation of soil erosion in South Korea. A GIS-based model was therefore applied to evaluate the yearly USLE approach in the notification. The GIS-based model employs USLE to estimate soil loss, providing an opportunity to estimate monthly soil loss with monthly USLE factor databases. Soil loss was compared in five watersheds, which were Geumgang, Hangang, Nakdonggang, Seomjingang, and Yeongsangang watersheds. The minimum difference was found at Seomjingang watershed, the yearly potential soil loss were 40.15 Mg/ha/yr by the notification approach and 34.42 Mg/ha/yr by the GIS-based model using monthly approach. And, the maximum difference was found at Nakdonggang watershed, the yearly potential soil loss were 27.01 Mg/ha/yr by the notification approach and 10.67 Mg/ha/yr by the GIS-based model using monthly approach. As a part of the study result, it was found that the potential soil loss can be overestimated in the notification approach.

박민우 Park Min Woo , 김선주 Kim Sun Joo , 권형중 Kwon Hyung Joong , 김필식 Kim Phil Shik , 강승묵 Kang Seung Mook , 이재혁 Lee Jae Hyuk

DOI: JKWST Vol.59(No.5) 127-136, 2017

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The object of this study was to assess availability of meteorological drought index for agricultural dorught estimation in ungauged area of agricultural drought parameters which are reservoir water level and soil moisture. The IADI (Integrated Agricultural Drought Index) and the SPI (Standard Precipitation Index), which are the criteria for determining agricultural drought and meteorological drought, were calculated and compared. For this purpose, the droughts that occurred in the Baeksan reservoir in Gimje and the Edong reservoir in Suwon were evaluated by using the IADI and SPI drought indecies. In addition, we compared and analyzed the depth of drought based on the two drought indices. Evaluations derived form the IADI and SPI showed that the standard precipitation index tended to indicate the occurrence of drought earlier than the integrated agricultural drought index. However, the integrated agricultural drought index was better than the standard precipitation index at evaluating the severity of drought during the period of irrigation. The relationship between these two drought indices seems to be useful for decision making in the case of drought, and it is considered that more studies are needed to examine the applicability of these drought indexes.