• Journal of Digital Convergence
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• v.10 no.11
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• pp.535-540
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• 2012

This study is to research the differences of tear film for young people in of a day in a restricted indoor space. The subjects are 58 eyes volunteers for twice preliminary inspection and tear test of a day. 58 healthy individuals with no eye disease, no body disease, orthophoria, corrective visual acuity more than 0.8, binocular spherical equivalence difference over 0.50 diopter, the flattest corneal curvature in horizontal meridian and the steepest corneal curvature in vertical meridian were tested. The uncorrective visual acuity, refractive error, corneal curvature, schirmer test and tear break up test were performed in the morning and afternoon. Schirmer test were $16.0{\pm}7.0mm$ in the morning and $14.1{\pm}7.1mm$ in the afternoon. TBUT were $11.3{\pm}0.6$ sec in the morning and $12.1{\pm}0.9$ sec in the afternoon. They have no significant differences.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.193-199
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• 2016

MR(magnetorheological) devices for vehicle applications requires the consistent control performance and the reliable operation. However, the corrosion of iron particles consisting the MR fluid can significantly affect on MR properties. This paper presents an effect of the MR particle corrosion on the performance of MR fluids such as shear stress magnitude which is directly concerned with control performance. As a first step, MR particles are corroded by water-calcium chloride solution. The resulting MR particles are examined by scanning electron microscope (SEM) and their molar ratios are analyzed by the energy dispersive X-ray analysis (EDAX). By dispersing the corroded MR particles into silicone oil, the corroded MR fluid is synthesized for evaluation of MR effect change. A rotational viscometer is adopted to measure shear stress magnitude. Finally, it is demonstrated how much the corrosion affect on performances by comparing the normal MR fluid to the corroded MR fluid, from which performance investigation of the MR devices containing the corroded MR particles will be studied in the second phase of this study.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.225-230
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• 2016

Dam is built to supply water necessary for life stably and reduce the damage caused by heavy rains. Recently there has been required the analysis and utilization of spatial information on the area around the dam because construction of the dam gives a great impact on the environment of the surrounding area. In this study, we build spatial information about the submerged district due to dam construction using drone and propose the effective method for analysis of the spatial information. As a result, orthoimage and DSM of study area were constructed effectively. Change of submerged district of this area was calculated according to the analysis of spatial information. Building and analyzing spatial information carried out in this study are expected to be utilized as the basis in related fields.

• Journal of the Korean Institute of Landscape Architecture
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• v.23 no.1
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• pp.51-65
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• 1995

Conservation of the natural environiment In chosun-Dynasty, Korea, is analysed on the basis of the of official records of the king's offices(Chosun-wangjo-sillok). In the popular ideologies of the dynasty, Seongleehak(philosophy of humanity arid natural laws) and Pungsu (geomancy) , the naturnal enviroment is defined as an entity con-sisting of Cheon (heaven) , San(mnountains) , Su (water), Geumsu (animals)and Chomok (plants) .the notion of Tacksi-Tackmul(being careful to take natural resources at the right time) was one of the Cheonmyung (eavenly decrees) . It was believed that violation of this principle resulted in natural disasters. Sasan(four mountains surrounding Hansungbu-, the capital city, now Seoul) , were strictly preserved according to geomancy practices. In areas other than the capital city, Sanlimcheontack (mountains, forests, rivers and ponds) were con-served for sustained production of building materials especially pinetrees for ship building, foods, firewoods, horses, and orter useful natural resources. Various conservation policy insturuments were adopted. Prunning trees was permitted only in October. Capturing fishes was allowed only after the spawning period. Protection areas were designated in Sasan, Seongjoesiplee (surroundings of the capital city) , Geumsan(protected mountains), Kangmujang(hunting and army training grounds), Sijang(firewood areas), Mokmajang(horse ranches) and Neungyuk(royal tombs) . Activities prohibited for conservation purposes included cutting timbers, burning, building houses or tombs, dumping wastes, farming and breaking up fresh land, grazing, hunting and trespassing. Positive actions for conservation were rituals to Heaven ennoblement of natural elements such as mountians or rivers, planting trees, Boto (supplementing soil on low ridges) , Josan (mounding) and making ponds. Boto, Josan and making ponds were to make ideal terrains for geomancy. Many government bodies and civil servants were engaged in the conservation activities. For example, Sanjik(forest keeper) was a special position with responsibility for forest management.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.4
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• pp.11-23
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• 2011

Mountain streams, which are major components of an entire river network, play an important role as the source of water, sediment, coarse and fine organic matter, and nutrients for lowland rivers. Therefore, dynamics and downstream linkages of each compartment of the mountain stream can be essential for watershed management in catchment scale. The dynamics and downstream linkages are understood as a development of step-pool sequences along a river course. Recently, stream restoration after flooding event often employ the development of step-pool sequences in the world. In this paper, we 1) examined the geomorphic characteristics and the role of step-pool sequences in steep mountain streams by reviewing the results of past studies, and 2) introduced the case studies of stream restoration using step-pool sequences, and finally 3) addressed design methods considering geometry and stability of artificial step-pool sequences for stream restoration. Step-pool sequences play an important role not only as roughness with energy dissipation but also as heterogeneity of stream feature for aquatic habitat. Step-pool sequences, even if they are constructed artificially along a stream, may be effective for small stream restoration considering eco-friendly torrent controls. So far the artificial step-pool sequences were employed for mountainous streams, but those would be applied to urban stream.

• Journal of Digital Convergence
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• v.17 no.3
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• pp.205-213
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• 2019

In a construction site, excavation work has a close relation with temporary earth retaining structure. In order to build the underground structure most effectively in a narrow space, prevent soil relaxation of the external behind ground in excavation work, and maintain a ground water level, it is required to install a temporary earth retaining structure that secures safety. To prevent soil washoff in underground excavation work, the conventional method of temporary earth retaining structure is to make a temporary wall and build the internal support with the use of earth anchor, raker, and struct for excavation work. RSB method that improves the problem of the conventional method is to remove the internal support, make use of two-row soldier piles and bracing, and thereby to resist earth pressure independently for underground excavation. This study revealed that through the field application cases of RSB method and the measurement result, the applicability of the method for installing a temporary earth retaining structure, the assessment result, and displacement all met allowable values of measurement, and that the RSB method, compared to the conventional method, improved constructability and economy.

• Journal of Soil and Groundwater Environment
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• v.26 no.4
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• pp.8-19
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• 2021

In this study, the evaluation standard for nitrate nitrogen contamination degree (WELCUP) was established using six factors that influence the groundwater quality in Jeju Island. To do this, weightings, ranges, and ratings were assigned for each factor and the relative possibility of nitrate nitrogen contamination degree was evaluated using WELCUP index for each well. As a result of calculating the WELCUP index using groundwater quality data of 5,112 wells in Jeju Island for 27 years (1993-2019), all 61 wells with the WELCUP index value higher than 100 are distributed in Daejung and Hangyung watershed with relatively large area of farmland in Jeju Island. In particular, as the ratio of private wells is more than 64%, it is necessary that systematic management is needed for private wells in terms of nitrate nitrogen contamination. Consequently, based on the results of applying the WELCUP evaluation standard, it is necessary to select the prioritization of nitrate nitrogen contamination pathways project for groundwater wells in Jeju Island.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.4
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• pp.1-15
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• 2024

In recent years, climate change has been responsible for unusual weather patterns on a global scale. Droughts, natural disasters triggered by insufficient rainfall, can inflict significant social and economic consequences on the entire agricultural sector due to their widespread occurrence and the challenge in accurately predicting their onset. The frequency of drought occurrences in South Korea has been rapidly increasing since 2000, with notably severe droughts hitting regions such as Incheon, Gyeonggi, Gangwon, Chungbuk, and Gyeongbuk in 2015, resulting in significant agricultural and social damage. To prepare for future drought occurrences resulting from climate change, it is essential to develop long-term drought predictions and implement corresponding measures for areas prone to drought. The Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report outlines a climate change scenario under the Shared Socioeconomic Pathways (SSPs), which integrates projected future socio-economic changes and climate change mitigation efforts derived from the Coupled Model Intercomparison Project 6 (CMIP6). SSPs encompass a range of factors including demographics, economic development, ecosystems, institutions, technological advancements, and policy frameworks. In this study, various drought indices were calculated using SSP scenarios derived from 18 CMIP6 global climate models. The SSP5-8.5 scenario was employed as the climate change scenario, and meteorological drought indices such as the Standardized Precipitation Index (SPI), Self-Calibrating Effective Drought Index (scEDI), and Standardized Precipitation Evapotranspiration Index (SPEI) were utilized to analyze the prediction and variability of future drought occurrences in South Korea.

• Journal of the Korean Geographical Society
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• v.40 no.6 s.111
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• pp.694-715
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• 2005

I examine in this paper the change of land use and the development of desertification in Horqin desert, east Inner Mongolia, China. The change of land use in this area can be summarized as the increase of agricultural field and intensive livestock farming. The agriculture and livestock farming in semi-arid area such as Horqin desert raised the problem in the management and use of water and vegetation. This problem led to desertification. The types of development of desertification in this area could be classified as follows: the mobile sand dune extension, the riverside shifting sand flat extension, the shifting sand speck extension around settlements, and the shifting sand speck extension in agricultural Held and grassland. There have been political or social movements such as the Great Leap Forward, the Cultural Revolution and the Reform and Open Policy in the background of land use change and desertification. Specially, the Great Leap Forward and the Cultural Revolution played an important role in the land use change and desertification in this area. Since 1990s, there has been some kind of policy in the control of desertification. However, it is necessary for the controling desertification of this area to consider the globalization and marketization, the survival and profit of peasants and livestock farmers, and the disturbrd and fixed population and land use structure in this area since 1949.

• Spatial Information Research
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• v.14 no.3 s.38
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• pp.349-361
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• 2006

New directions on rural policy have been discussed due to the domestic and international environmental changes such as the price degradation of agricultural products, maintenance of rural landscape, and so on. Development of amenity in rural areas has been come out as the one of new policy directions. Amenity defines as, in a very broad way, the public benefits accruing from the condition of a place, such as aesthetic beauty, clean air and water, or good street lighting. Amenity in rural area is referred as a resource with a potential possibility for development. Among them rural landscape is regarded as the one of major resources. In Jeju, particularly, stone wall retains the most esthetic landscape in rural regions. In addition, the Ministry of Culture and Tourism appointed stone wall as the one of important components in rural landscape and one of the 100 national historic symbols. Stone wall in Jeju has its intrinsic and real value and is widespread in rural regions. However, in spite of it's popularity, the landscape of stone wall has been degraded without any concerns and has been partly destroyed. Landscape of stonewall should be maintained and the depth of concerns and systematic management measures for protection should be discussed. In this sense, the purpose of this paper, first of all, is to examine the status of stone wall and to evaluate the landscape of stone wall in Jeju. GIS is used as an analysis tool. Several areas such as Hankyung, Namyeup, and so on in Jeju are selected as the case areas for this study.