• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.3
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• pp.31-39
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• 2021

In this study, the fiber blending ratio and strain rate effect on the tensile properties synergy effect of hybrid fiber reinforced cement composite was evaluated. Hooked steel fiber(HSF) and smooth steel fiber(SSF) were used for reinforcing fiber. The fiber blending ratio of HSF+SSF were 1.5+0.5, 1.0+1.0 and 0.5+1.5vol.%. As a results, in the cement composite(HSF2.0) reinforced with HSF, as the strain rate increases, the tensile stress sharply decreased after the peak stress because of the decrease in the number of straightened pull-out fibers by increase of micro cracks in the matrix around HSF. When 0.5 vol.% of SSF was mixed, the micro cracks was effectively controlled at the static rate, but it was not effective in controlling micro cracks and improving the pull-out resistance of HSF at the high rate. On the other hand, the specimen(HSF1.0SSF1.0) in which 1.0vol.% HSF and 1.0vol.% SSF were mixed, each fibers controls against micro and macro cracks, and SSF improves the pull-out resistance of HSF effectively. Thus, the fiber blending effect of the strain capacity and energy absorption capacity was significantly increased at the high rate, and it showed the highest dynamic increase factor of the tensile strength, strain capacity and peak toughness. On the other hand, the incorporation of 1.5 vol.% SSF increases the number of fibers in the matrix and improves the pull-out resistance of HSF, resulting in the highest fiber blending effect of tensile strength and softening toughness. But as a low volume fraction of HSF which controlling macro crack, it was not effective for synergy of strain capacity and peak toughness.

• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.1-10
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• 2022

Irrigation water supplied to the paddy field is consumed in the amount of evapotranspiration, underground infiltration, and natural and artificial drainage from the paddy field. Irrigation return flow is defined as the excess of irrigation water that is not consumed by evapotranspiration and crop, and which returns to an aquifer by infiltration or drainage. The research on estimating the return flow play an important part in water circulation management of agricultural watershed. However, the return flow rate calculations are needs because the result of calculating return flow is different depending on irrigation channel water loss, analysis methods, and local characteristics. In this study, the irrigation return flow rate of agricultural watershed was estimated using the monitoring and SWMM (Storm Water Management Model) modeling from 2017 to 2020 for the Heungeop reservoir located in Wonju, Gangwon-do. SWMM modeling was performed by weather data and observation data, water of supply and drainage were estimated as the result of SWMM model analysis. The applicability of the SWMM model was verified using RMSE and R-square values. The result of analysis from 2017 to 2020, the average annual quick return flow rate was 53.1%. Based on these results, the analysis of water circulation characteristics can perform, it can be provided as basic data for integrated water management.

• Journal of the Daesoon Academy of Sciences
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• v.39
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• pp.99-136
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• 2021

Grievance-resolution pursues reconciliation, mutual beneficence, and consolidation. Accordingly, the concept of grievance-resolution is a norm, a principle, as well as an ideology that aims to realize an ideal society and satisfy human desires. Such ideological thought transcended into religious doctrine and was systemized by Jeungsan, Kang Il-sun. He focused on grudges that represented the intrinsic sentiment of Korea and apprehended that grudges are the grounds and reason for the devastation of the world. Furthermore, Jeungsan was a figure who reinterpreted the concept of grievance-resolution via a religious perspective through an in-depth study which transformed into a doctrinal system. He practiced the Reordering Works of grievance-resolution on a universal dimension to religiously redeem all things. Jeungsan completely resolved all the grudges and grievances that filled up the Three Realms (Heaven, Earth, and Humanity) through the concept of grievance-resolution and emphasized that he would establish an ideal society on earth to complete the redemption of human beings. Jeungsan apprehended that the essential characteristics of grudges and grievances were the fundamental reason for the destruction of the world. In this regard, he insisted that the redemption of the world should be achieved through the grievance-resolution. Grievance-resolution is an essential aspect and principle of Jeungsan's system of thought. In addition, it is a concrete approach to establish the earthly paradise of the Later World. Jeungsan implemented a method to redeem humankind by systemizing the intrinsic sentiments common in Korea - namely, the concept of grievance-resolution- and he suggested it as a religious practice which was the principle behind the Reordering Works of Heaven and Earth. Jeungsan defined that his own era was a time of grievance-resolution. In addition, he insisted that grievances and grudges had existed from the beginning of humankind. Jeungsan also said that there were grievances and grudges in heavenly planes, human planes, and underworldly planes. It was thereby necessary to do beneficial deeds for others and reciprocate beneficence in order to resolve grievances. He emphasized that a process wherein all human desires could be satisfied was essential. Furthermore, Jeungsan stressed that this present time should focus on the process of grievance-resolution on a practical level.

• Journal of Korea Water Resources Association
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• v.55 no.12
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• pp.1125-1135
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• 2022

Damages by heavy snow does not occur very often, but when it does, it causes damage to a wide area. To mitigate snow damage, it is necessary to know, in advance, the depth of snow that causes damage in each region. However, snow depths are measured at observatory locations, and it is difficult to understand the spatial distribution of snow depth that causes damage in a region. To understand the spatial distribution of snow depth, the point measurements are interpolated. However, estimating spatial distribution of snow depth is not easy when the number of measured snow depth is small and topographical characteristics such as altitude are not similar. To overcome this limit, satellite images such as Synthetic Aperture Radar (SAR) can be analyzed using Differential Interferometric SAR (DInSAR) method. DInSAR uses two different SAR images measured at two different times, and is generally used to track minor changes in topography. In this study, the spatial distribution of snow depth was estimated by DInSAR analysis using dual polarimetric IW mode C-band SAR data of Sentinel-1B satellite operated by the European Space Agency (ESA). In addition, snow depth was estimated using geostationary satellite Chollian-2 (GK-2A) to compare with the snow depth from DInSAR method. As a result, the accuracy of snow cover estimation in terms with grids was about 0.92% for DInSAR and about 0.71% for GK-2A, indicating high applicability of DInSAR method. Although there were cases of overestimation of the snow depth, sufficient information was provided for estimating the spatial distribution of the snow depth. And this will be helpful in understanding regional damage-causing snow depth.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.4
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• pp.20-36
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• 2022

This study aims to provide basic data for high-quality street tree management by setting reasonable management items and appropriate unit prices by reviewing the adequacy of current street tree management. Currently, street tree management items, except for street tree pruning, use general landscape tree quantity per unit for the street tree management quantity per unit. KEPCO (Korea Electric Power Corporation) applied pruning items from standard electric production infrastructure and carried out the activities at an average unit price of 51% lower for heavy pruning and 39% lower for light pruning than the standard estimate. This was judged to be a level that could not maintain or increase the quality of street tree management. It was determined that an appropriate standard unit price for street tree management was necessary. To improve the quantity per unit for the proper management of street trees, it was necessary to review costs in the field. However, due to the absence of data on actual construction costs in the domestic landscape field, detailed items of the US RSMeans Building Construction Cost Data (RSMeans) were reviewed, and the actual construction costs were calculated by applying personal domestic expenses. As a result, the standard of the estimated unit showed a good ratio of 107% for heavy pruning of street tree pruning compared to the actual construction cost, but light pruning was underestimated with a 59% ratio. Shrub pruning was 82%, weeding was 92%, tree fertilization was 87%, and windbreak wall installation was 91% under-engineered. In addition, it was also confirmed that the watering by sprinkler trucks and chemical spraying were over-designed compared to the actual construction cost at the rates of 118% and 124%, respectively. Due to the specificity of the street trees, the increase in personal expenses and the input cost of equipment, such as road safety controls, were judged to be the main cause of the underestimation of items. Therefore, it is necessary to add items related to street trees and general landscape trees to the landscape maintenance items of the standard of the estimated unit.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.6
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• pp.110-123
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• 2022

Namsan Park in Seoul was designated as a "grand park" in 1954 and is currently operated as an 'Urban Nature Park Area' and four 'neighborhood parks.' However, despite the park's historical and cultural value as an urban park, it has been discussed mainly from a perspective revolving around notions of a mountain or a city wall. To ensure a comprehensive exploration of Namsan Park's history, this study examined public records at the Seoul Metropolitan Archives (SMA), which houses the city's permanent records for preservation and organization. To this end, documents in the SMA Database (DB) were analyzed, yielding 1,359 records concerning Namsan Park. Based on the contents, general characteristics of the urban park were identified through production periods, record types, and disclosure types. Then, essential keywords concerning organizations, people, geographical areas, subjects, and business functions were examined. Finally, the contents and characteristics of Namsan Park in public records were scrutinized, focusing on specific spaces. This research also uncovered important information, such as park drawings, photos, planting lists, plant parcel lists, and significant discussions and decisions regarding the operation and management of the park. Although the public records do not contain a comprehensive history of Namsan Park, it was possible to check the primary historical changes and deliberation processes pertaining to the park's history. Therefore, continuous research intended to interpret and describe public records is expected to identify many implications. In addition, because the public records showed heterogeneous characteristics that center on specific periods and events, an essential task is to advance collaboration and networking with various related institutions, designers, researchers, and citizens.

• Journal of the Korean Geotechnical Society
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• v.26 no.12
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• pp.19-30
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• 2010

Bentonite-based grout has been widely used to seal a borehole constructed for a closed-loop vertical ground heat exchanger in a geothermal heat pump system (GHP) because of its high swelling potential and low hydraulic conductivity. Three types of bentonites were compared one another in terms of viscosity and thermal conductivity in this paper. The viscosity and thermal conductivity of the grouts with bentonite contents of 5%, 10%, 15%, 20% and 25% by weight were examined to take into account a variable water content of bentonite grout depending on field conditions. To evaluate the effect of salinity (i.e., concentration of NaCl : 0.1M, 0.25M, and 0.5M) on swelling potential of the bentonite-based grouts, a series of volume reduction tests were performed. In addition, if the viscosity of bentonite-water mixture is relatively low, particle segregation can occur. To examine the segregation phenomenon, the degree of segregation has been evaluated for the bentonite grouts especially in case of relatively low viscosity. From the experimental results, it is found that (1) the viscosity of the bentonite mixture increased with time and/or with increasing the mixing ratio. However, the thermal conductivity of the bentonite mixture did not increase with time but increased with increasing the mixing ratio; (2) If bentonite grout has a relatively high swelling index, the volume reduction ratio in the saline condition will be low; (3) The additive, such as a silica sand, can settle down on the bottom of the borehole if the bentonite has a very low viscosity. Consequently, the thermal conductivity of the upper portion of the ground heat exchanger will be much smaller than that of the lower portion.

• Journal of Korea Water Resources Association
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• v.56 no.4
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• pp.261-272
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• 2023

In recent years, natural disasters such as heavy rainfall and typhoons have occurred more frequently, and their severity has increased due to climate change. The Korea Meteorological Administration (KMA) currently uses the same criteria for all regions in Korea for watch and warning based on the maximum cumulative rainfall with durations of 3-hour and 12-hour to reduce damage. However, KMA's criteria do not consider the regional characteristics of damages caused by heavy rainfall and typhoon events. In this regard, it is necessary to develop new criteria considering regional characteristics of damage and cumulative rainfalls in durations, establishing four stages: blue, yellow, orange, and red. A classification model, called DSCM (Disaster Severity Classification Model), for the four-stage disaster severity was developed using four machine learning models (Decision Tree, Support Vector Machine, Random Forest, and XGBoost). This study applied DSCM to local governments of Seoul, Incheon, and Gyeonggi Province province. To develop DSCM, we used data on rainfall, cumulative rainfall, maximum rainfalls for durations of 3-hour and 12-hour, and antecedent rainfall as independent variables, and a 4-class damage scale for heavy rain damage and typhoon damage for each local government as dependent variables. As a result, the Decision Tree model had the highest accuracy with an F1-Score of 0.56. We believe that this developed DSCM can help identify disaster risk at each stage and contribute to reducing damage through efficient disaster management for local governments based on specific events.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.6-7
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• 2021

Vegetation development in rivers is one of the important issues not only in academic fields such as geomorphology, ecology, hydraulics, etc., but also in river management practices. The problem of river vegetation is directly connected to the harmony of conflicting values of flood management and ecosystem conservation. In Korea, since the 2000s, the issue of river vegetation and land formation has been continuously raised under various conditions, such as the regulating rivers downstream of the dams, the small eutrophicated tributary rivers, and the floodplain sites for the four major river projects. In this background, this study proposes a method for classifying the distribution of vegetation in rivers based on remote sensing data, and presents the results of applying this to the Naeseong Stream. The Naeseong Stream is a representative example of the river landscape that has changed due to vegetation development from 2014 to the latest. The remote sensing data used in the study are images of Sentinel 1 and 2 satellites, which is operated by the European Aerospace Administration (ESA), and provided by Google Earth Engine. For the ground truth, manually classified dataset on the surface of the Naeseong Stream in 2016 were used, where the area is divided into eight types including water, sand and herbaceous and woody vegetation. The classification method used a random forest classification technique, one of the machine learning algorithms. 1,000 samples were extracted from 10 pre-selected polygon regions, each half of them were used as training and verification data. The accuracy based on the verification data was found to be 82~85%. The model established through training was also applied to images from 2016 to 2020, and the process of changes in vegetation zones according to the year was presented. The technical limitations and improvement measures of this paper were considered. By providing quantitative information of the vegetation distribution, this technique is expected to be useful in practical management of vegetation such as thinning and rejuvenation of river vegetation as well as technical fields such as flood level calculation and flow-vegetation coupled modeling in rivers.

• Journal of the Daesoon Academy of Sciences
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• v.21
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• pp.323-367
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• 2013

한국의 대순진리회는 증산 성사의 가르침을 숭신하는 종교단체로서, 한국 사회에 상당한 영향력을 가지고 있다. 1969년 창설된 대순진리회는 포덕·교화·수도를 삼대 기본사업으로, '음양합덕·신인조화·해원상생·도통진경'을 종지로, '안심·안신·경천·수도'를 사강령으로, '성·경·신'을 수도의 삼요체로 삼고 있다. 또한 인간개조와 포덕천하·구제창생·보국안민을 통하여 지상천국을 건설하는 것을 목표로 한다. 대순진리회는 사상적 측면에서 무(巫)와 유(儒)·불(佛)·도(道)를 포용하고 있다. 이러한 대순사상을 바탕으로 대순진리회의 도인들은 근엄하고 세밀한 실천수도를 수행하는데, 그 내용을 살펴보면 중국 유·불·도의 양생문화와 많은 공통점이 있는 동시에, 또한 뚜렷한 한국 문화의 특색을 띠는 부분도 있다. 이런 면들은 모두 개인적 수도와 사회적 안정을 실현하는 데 큰 도움이 되고 있다. '안심·안신·경천·수도'의 사강령은 대순진리회의 도인들이 지켜야 할 가장 기본적인 행위규범이다. '성·경·신'의 삼요체는 사강령을 실천하기 위한 내면적 수양으로서 모든 수도활동의 근본이 되는 것이다. 삼요체 중에서 '성'을 가장 근본적인 것으로 생각하는데, 그 이유는 오직 '성'을 갖춘 사람만이 '경'과 '신'을 논할 수 있기 때문이다. 반대로 마음속에 망념이 있거나 경거망동을 하는 사람들은 상제에 대한 '경'과 '신'을 잃게 된다. '성실함'이라는 내면적 도덕 품성은 인간으로 하여금 더욱 정직하고 안정되며 오래 지속되게 한다. 뿐만 아니라 '성'은 수도자들로 하여금 더욱 순수해지고, 어리석음을 버리게 한다. 크나큰 도를 성취하려면 먼저 이렇게 얼핏 보기에는 어리석지만 끈기 있는 마음이 필요하다. '성'하면 기운이 솟구쳐 내면이 더욱 안정되고 번뇌는 사라진다. 성심을 수련하면 마음이 안정되고, 마음이 안정되면 정신이 안정되는데, 정신이 안정되면 걱정이 사라지기에 몸도 건강해진다. 삼요체중 '경'과 '신'에 있는 큰 의미 가운데 하나는 상제님에 대한 경배와 믿음을 끝까지 가지라는 것이다. '해원상생·보은상생'은 대순사상의 가장 중요한 대도(大道) 윤리로서 도인들의 수도를 인도하는 기본적인 법칙이다. 대순진리회에서 말하는 해원은 단지 개인 한 사람의 해원이 아니라 우주의 질서를 바로잡는 해원이라는 점에서 중요하다. 그렇기 때문에 대순진리회 도인들은 개개인으로 시작하여 자신의 원한을 해결할 뿐만 아니라, 땅의 원한, 천민의 원한, 여인의 원한 등 모든 원을 해결해 주고자 한다. 즉 삼계의 모든 불평등을 해소하고 불합리한 부분을 바로잡는 것이다. 해원의 다른 측면은 보은이라 할 수 있다. 해원과 보은은 상보상조의 관계에 있는데, 이는 곧 도인들이 행하는 수도의 양 날개라 생각된다. 해원을 통하여 과거의 장애를 제거하고, 보은을 통하여 현재의 덕을 쌓는 것이다. 보은을 하려면 항상 감사의 마음을 간직해야 한다. 그 의미는 인간관계에 있어서 다른 사람이 베푼 은혜를 항상 고맙게 생각해야 한다는 것이며, 더 나아가 천지가 우리에게 베푼 은혜도 감사하게 생각해야 한다는 것이다. 모든 원한이 풀어지고, 모든 은혜를 다 갚았을 때 삼계가 조화롭고 통하게 될 것이다. 대순진리회에서는 도인들의 실천수도 면에서 두 가지 측면을 강조하는데, 즉 포덕교화와 근언신행이다. 근언신행은 자아발전을 위한 도인들의 내적 수련이며, 포덕교화는 도인들이 외부 세상에 대순사상을 알리고 가르치는 것을 말한다. 양자는 동전의 양면과 같이 떨어질 수 없는 관계에 있다. 다른 사람을 포덕·교화 하려면 도인들 스스로가 먼저 말과 행동에 조심해야 한다. 왜냐하면 말과 행동을 조심하는 것 자체가 곧 포덕교화에서 다른 사람의 모범이 되기 때문이다. 인생을 살면서 추구해야 할 가장 높은 목표는 덕(德)을 세우는 것이고, 그 다음은 공(功)을 세우는 것이며, 그 다음은 언(言)을 세우는 것이다. 덕·공·언은 세월이 지나도 그 가치가 빛을 바래지 않는다. 이 세 가지 중 한 가지를 이룬 사람이면 불후하다고 할 수 있다. 성인들이 성인으로 칭송 받았던 이유는 모두 육체를 초월한 덕·공·언으로 세상을 풍요롭게 했기 때문이다. 그렇기 때문에 비록 그들이 세상을 떠났다 하더라도 마치 살아있는 것처럼 영원히 추앙되니, 이것을 통하여 영생을 얻는 것이다. '영생(永生)' 만큼 높은 경지에 도달하는 '양생'이 또 어디에 있겠는가? 대순진리회 실천수도의 최고목표는 바로 인간 내면의 수양을 최고의 경지로 끌어올리는 것으로서 이는 곧 음양합덕·도통진경이다. 다시 말해서 영원히 불후한 경지에 이르고 만세(萬歲)토록 영생하는 것이며 신(神) 그리고 성인이 되는 것이다.