• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.4
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• pp.234-246
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• 2007

The role of macropore in the hydrological processes is important at the hillslope scale. Developments and distribution of macropores have not been investigated in conjunction with the characteristics of the hillslope such as topography, soil property, and soil moisture. In this study, macropore properties, such as macropore flow and saturation hydraulic conductivity were measured at a hillslope located in Gwangneung Research Forest, Pochun-gun, Gyeonggi-do, South Korea. An intensive field survey provided a refined Digital Elevation Model (DEM) for surface and subsurface topography. Spatial distributions of upslope area and topographic index were obtained through the digital terrain analysis. The total number of monitoring points was 22, and the selected points were distributed along the transect of the digital contour map. Vertical fluxes through macropores were measured using a tension infiltrometer at the depth of 0.1 m from the surface. Spatial and temporal distributions of soil moisture were obtained using an on-line measurement system, TRASE, installed in the study area. Soil moisture for the aforementioned points was measured at 0.1 and 0.3m depths below the surface. The results from tension infiltrometer experiments present that the macropore flows ranged between 21 and 94%, and the measured macroporosities varied from 1.4 to 47%. Macropore flows and macroporosities tended to increase as the measurement location moved to downslope. The ability for water conduction through macropores becomes increasingly developed as the location approaches the outlet of the hillslope.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.927-935
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• 2019

Screw-failure accidents in small ships frequently occur in coastal waters. In particular, vessels' propulsion systems are frequently coiled due to objects such as fish-nets and ropes that float on the sea. The failure of the ship's propulsion system can cause primary accidents such as ship operation delays and drifting due to loss of power; furthermore, the possibility of secondary accidents such as those involving operators in the underwater removal of rope stuck in a propeller. Ships that do not have the proper tools to solve these problems must be either lifted onto land to be repaired or divers must dive directly under the ship to solve the problem. Accordingly, some small vessels have been equipped with rope-cutter devices on the propeller shaft to prevent ship propeller system accidents in recent years; however, they are not being applied efficiently due to the cost and time of installation. To solve these problems, this study develops an underwater rope-cutter device and controller for the removal of propeller and shaft foreign material in small vessels. This device has simple structures that use the principle of a saw. Meteor gears and crank pins were used for the straight-line rotation of saw blades of the underwater rope-cutters to allow for long strokes. Furthermore, the underwater rope-cutting machines can be operated by being connected to the ship battery. The user, a non-professional, can ensure convenience and stability by applying reverse current prevention and a speed control circuit so that it can be used more conveniently and safely.

• Economic and Environmental Geology
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• v.49 no.1
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• pp.43-52
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• 2016

The essential role of the Division of Earth Sciences(EAR) in the Directorate of Geoscience(GEO) of National Science Foundation of America(NSF) is to support basic research aimed at acquiring fundamental knowledge of the Earth system that can be directly applied to the United States' strategic needs. The 2011 Committee on New Research Opportunities in the Earth Sciences(NROES) of the National Academy of Sciences(NAS) identified specific areas of the basic earth science research scope of the EAR that were poised for rapid progress during the next decade. Quantified by interdisciplinary approaches, the Committee highlighted the following topics relating to the EAR Deep Earth Processes and Surface Earth Processes sections: (1) the early Earth; (2) thermochemical internal dynamics and volatile distribution; (3) faulting and deformation processes; (4) interactions among climate, the Earth surface processes, tectonics, and deep Earth processes; (5) co-evolution of life, environment, and climate; (6) coupled hydrogeomorphic-ecosystem response to natural and anthropogenic change; and (7) interactions of biogeochemical and water cycles in terrestrial environments. We also promote future research challenges such as the critical zone studies. In order to promote more active such a huge future research challenges, additional research support policies are needed.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.544-544
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• 2015

국내에는 17,500여개의 농업용 저수지가 전국적으로 분포하고 있으며, 이들 저수지는 인공호소이다. 농업용 저수지의 총 유효저수량은 2,838백만$m^3$에 달하고 있으며, 전체 수리답의 약 76%에 해당하는 593천ha의 농경지에 물을 관개하고 있다(2013농업생산기반통계연보). 최근 농어촌지역의 도농복합형태 개발 및 관광지, 유원지화로 농업용 저수지 유역의 오염원이 지속적으로 증가하는 추세에 있으며, 이로 인해 농업용수 수질이 지속적으로 악화되고 있다. 특히, 늦봄에서 초가을까지 외기온도 상승 및 저수율 저하와 함께 부영양화 증가, 녹조 대발생 등으로 수질오염도가 급상승하고 있으며, 이로 인해 호 내 물고기 폐사, 악취발생 등으로 민원이 다수 발생하고 있다. 본 연구에서는 농업용 저수지의 물리적 특성을 분석하여 농업용 저수지 수질개선을 위한 기초자료로 활용하고자 하였다. 농업용 저수지 17,489개소를 수혜면적별로 분류해 보면 5ha이하가 7,808개소(44.7%), 5~10ha이하 4,277개소(24.5%), 10~20ha 2,772개소(15.9%), 20~30ha 797개소(4.6%), 30~40ha 385개소(2.2%), 40~50ha 238개소(1.4%), 50ha이상 1,201개소(6.9%)로 구성되어 있어 50ha이하가 전체의 93.1%에 이르고 있다. 유효저수량별 분포현황은 10천$m^3$이하가 7,996개소(45.7%), 10~50천$m^3$ 6,420개소(36.7%), 50~100천$m^3$ 1,003개소(5.7%), 100~300천$m^3$ 868개소(5.0%)로 전체 시설 중 50천$m^3$이하가 전체 저수지의 82.4%로 대부분이 소규모 저수지임을 알 수 있다. 농업용 저수지를 유효수심별로 구분해보면 1m이하가 전체의 26.6%, 3m이하가 전체의 77.1%, 5m이하가 전체의 91.1%로 국내 대부분의 저수지들은 수심이 5m 이하의 저류지 형태의 저수지임을 알 수 있다. 저수지를 유역배율(유역면적/만수면적)에 따라 구분해보면 유역배율 3이하가 전체의 1.2%이고, 5이상이 전체의 97.4%를 차지하고 있다. 일반적으로 유역배율이 3이상이면 부영양화에 취약한 호소로 분류되고 있다. 국내 농업용 저수지는 대부분이 수심이 낮고, 유효저수량이 소규모이며, 유역배율이 3이상인 호소가 대부분으로 태생적으로 수질오염 및 부영양화에 취약한 구조로 되어 있음을 알 수 있다. 농업용 저수지 수질개선을 위한 종합계획 수립시에는 유입수 및 호내 대책과 함께 호소의 물리적 조건을 개선시키는 방안에 대해서도 검토가 요구된다. 특히 저수지 신규 설치시에는 수량관리 뿐만 아니라 수질도 함께 고려된 물리적 인자에 대한 설계가 이루어져야 할 것으로 판단된다.

• Korean Journal of Heritage: History & Science
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• v.51 no.2
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• pp.92-107
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• 2018

In 2013~2016, gilt-bronze shoes were excavated from the ancient tombs in Jeongchon Village located at Bogam-ri, Dasi-myeon in Naju. They are estimated to have been made in the late 5th or early 6th centuries. The gilt-bronze shoes are significant in that they serve to explicate the relationship between the center of Baekje and the local forces in the Yeongsan River Basin. This study's specific focus was the gilt-bronze shoes from the ancient tombs in Jeongchon Village. Based on the findings, a restoration drawing was designed and restored products were manufactured by considering metalwork techniques used to manufacture the original ones. At first, manufacturing techniques were tested by using a scientific analysis and visual observation. The manufacturing method, structures, and patterns of the gilt-bronze shoes were closely examined. Then, a design drawing of gilt-bronze shoes was created through field measurement and they were recreated on the basis of the analysis. The original form of the restored products were manufactured through cutting out the outward form, bore carving, engraving, molding, plating, and an assembly process. In the restoration process, this study examined the formal characteristics of gilt-bronze shoes, manufacturing techniques, and archetypes during Baekje's late Hanseong era. Products restored from this study are expected to be used as achievements for more easily understanding the culture of Baekje.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.3
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• pp.110-121
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• 2021

The importance of tidal flats lost due to industrialization has recently received attention, and attention is being paid to the creation of artificial tidal flats and maintenance of natural tidal flats. However, there is still a lack of understanding about the behavioral characteristics of mud, mud, and sand that form tidal flats. Although research on the movement characteristics of mixed soils such as tidal flats has been conducted through field investigations and hydraulic experiments, interest in developing a numerical model based on these results has not yet reached. In this paper, the purpose of this paper is to establish a mixed soil model that can efficiently manage the low quality of the tidal flats. In constructing a model for reproducing the surface movement of mixed soil, the numerical stability of the reproduction and movement of sand and mud constituting the mixed soil in the numerical model should be considered first, so first, the volume of sand and mud constituting the mixed soil A mixed soil model representing the relationship was proposed based on a topographical diagram representing the geometric structure of the mixed soil. In order to consider the dry bulk density of the mixed soil, it was possible to consider the dry bulk density of the mud by introducing the water content of the mud containing water. In addition, it was confirmed that the mud and sand movement calculation according to the slope collapse of the mixed soil was stably performed through the calculation of the slope collapse of the mixed soil through the numerical analysis model to which the proposed mixed soil model was applied.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.29 no.1
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• pp.1-13
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• 2011

Cheongpyeongsa Temple was originally built in the early years of Goryeo Dynasty, but its current structural framework was made by the Lord Jinrakgong Lee Ja Hyeon(1061-1125) of the middle Goryeo period based on the Zen thought after he began living in the Cheongpyeong mountain around the temple in 1089. The purpose of this study is to conceptualize, based on old documents, historical changes of the appearance and survival of man-made structures with in the Zen garden formed and developed after Lee Ja Hyeon laid the foundation for Munsuwon Zen garden. Among the eight, outside-the-temple hermitages built at the time of Lee Ja Hyeon's Munsuwon Zen garden, only three hermitages, which are Sik-am, Gyeonseong-am, Yangshin-am had been remaining thanks to restoration and repair until late Joseon Dynasty and preserved as symbolic hermitages. Also, the Yeongji Pond built at the time of Lee Ja Hyeon still remains as precious landscape relics which is meaningful as a genuine Goryeo-period pond. The nine pine trees said to be planted by Lee Ja Hyeon remained until middle 1800s through their descendant trees. When the Buddhist monk Bowoo Daesa(1509-1565)changed the name to Cheongpyeongsa Temple in middle Joseon based on the Munsuwon Zen garden built by Lee Ja Hyeon and greatly expanded it, he newly built and expanded all buildings inside the temple except for Neunginjeon(main temple building), resulting in the present temple structure. In addition, by greatly enhancing the level of scenery by reconstructing Yeongji Pond outside the temple area and transplanting garden plants from the royal court, he made Cheongpyeongsa Temple the most prosperous Zen garden in its history. But after the mid-1800s, which is late Joseon period, Cheongpyeongsa Temple failed to thrive further and began to decline, and so currently most buildings of the Zen garden have disappeared except for some parts of the temple and other facilities are neglected.

• Land and Housing Review
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• v.14 no.1
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• pp.83-97
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• 2023

The study aims to provide an academic basis for the preservation and restoration of abandoned paddy wetland and the enhancement of its carbon accumulation function. First, the temporal change of the wetlands was analysed, and a typological classification system for wetlands was attempted with the goal of carbon reduction. The types of wetland were classified based on three variables: hydrological environment, vegetation, and carbon accumulation, with a special attention on the function of carbon accumulation. The types of abandoned paddy wetlands were classified into 12 categories based on hydrologic variables- either high or low levels of water inflow potential-, vegetation variables with either dominance of aquatic plants or terrestrial plants, and three carbon accumulation variables including organic matter production, soil organic carbon accumulation, and decomposition. It was found that the development period of abandoned paddy analyzed with aerial photographs provided by the National Geographic Information Institute happened between 2010 and 2015. In the case of the wetland in Daejeon 1 (DJMN01) farming stopped by 1990 and it appeared to be a similar structure to natural wetlands after 2010 . Over the past 40 years the abandoned paddy wetland changed to a high proportion of forests and agricultural lands. As time went by, such forests and agricultural lands tended to decrease rapidly and the lands were covered by artificial grass and other types of forests.

• The Journal of Engineering Geology
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• v.33 no.2
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• pp.257-273
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• 2023

Hydrochemical characteristics and microbial communities of spring (Samtong), surface water, and groundwater in Cheorwon, Korea, were analyzed. Field surveys and water quality analyses were undertaken at 10 sampling points for five spring, two surface, and three groundwater samples on 15 December 2022. Hydrochemical analysis revealed that most water samples were Ca-HCO₃ type and that water-rock interactions were the predominant mineral source. Radon concentrations were <1 kBq m^-3 for surface water, 1~10 kBq m^-3 for spring water, and 1~1,000 kq m^-3 for groundwater. Microbial cluster analysis showed that the main phyla were Proteobacteria, Planctomyceta, Verrucomicrobia, Acidobacteria, and Actinomycetota.Non-metric multidimensional scaling (NMDS) analysis indicated that water temperature, pH, and Si content were closely related to microorganism content. NMDS and canonical correspondence analysis results revealed that environmental factors affecting spring water were temperature, and Mg and Si concentrations, particularly for Acidobacteria and Proteobacteria, and Pseudomonas brenneri. Both hydrochemical and microbial community analyses yielded similar results at some spring and groundwater sampling points, likely due to the effects of a basalt aquifer.

• Journal of Environmental Policy
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• v.8 no.1
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• pp.73-95
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• 2009

The fact that soil loss causing to increase muddy water and devastate an ecosystem has been appearing upon a hot social and environmental issues which should be solved. Soil losses are occurring in most agricultural areas with rainfall-induced runoff. It makes hydraulic structure unstable, causing environmental and economical problems because muddy water destroys ecosystem and causes intake water deterioration. One of three severe muddy water source areas in Soyanggang-dam watershed is Jawoon-ri region, located in Hongcheon county. In this area, many cash-crops are planted at illegally cultivated agricultural fields, which were virgin forest areas. The purpose of this study is to estimate soil loss with current land uses(including illegal cash-crop cultivation) and soil loss reduction with land use conversion from illegal cultivation back to forest. In this study, the Sediment Assessment Tool for Effective Erosion Control(SATEEC) ArcView GIS was utilized to assess soil erosion. If the illegally cultivated agricultural areas are converted back to forest, it would be expected to 17.42% reduction in soil loss. At the Jawoon-ri region, illegally cultivated agricultural areas located at over 30% and 15% slopes take 47.48 ha(30.83%) and 103.64 ha(67.29%) of illegally cultivated agricultural fields respectively. If all illegally cultivated agricultural fields are converted back to forest, it would be expected that 17.41% of soil erosion and sediment reduction, 10.86% reduction with forest conversion from 30% sloping illegally agricultural fields, and 16.15% reduction with forest conversion from 15% sloping illegally agricultural fields. Therefore, illegally cultivated agricultural fields located at these sloping areas need to be first converted back to forest to maximize reductions in soil loss reduction and muddy water outflow from the Jawoon-ri regions.