• Economic and Environmental Geology
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• v.56 no.4
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• pp.435-445
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• 2023

A delta is a depositional landform that is formed when sediment transported by a river is deposited in a relatively low-energy environment, such as a lake, sea, or a main channel. Among these, a delta formed at the confluence of rivers has a great importance in river management and research because it has a significant impact on the hydraulic and sedimentological characteristics of the river. Recently, the equilibrium state of the confluence area has been disrupted by large-scale dredging and construction of levees in the Nakdong River. However, due to the natural recovery of the river, the confluence area is returning to its pre-dredging natural state through ongoing sedimentation. The time-series data show that the confluence delta has been steadily growing since the dredging, but once it reaches a certain size, it repeats growth and retreat, and the overall size does not change significantly. In this study, we developed a model to explain the sedimentation-erosion processes in the confluence area based on the assumption that the confluence delta reaches a dynamic equilibrium. The model is based on two fundamental principles: sedimentation due to supply from the tributary and erosion due to the main channel. The erosion coefficient that represents the Nakdong River confluence areas, was obtained using data from the tributaries of the Nakdong River. Sensitivity analyses were conducted using the developed model to understand how the confluence delta responds to changes in the sediment and water discharges of the tributary and the main channel, respectively. We then used annual average discharge of the Nakdong River's tributaries to predict the dynamic equilibrium positions of the confluence deltas. Finally, we conducted a simulation experiment on the development of the Gamcheon-Nakdong River delta using recorded daily discharge. The results showed that even though it is a simple model, it accurately predicted the dynamic equilibrium positions of the confluence deltas in the Nakdong River, including the areas where the delta had not formed, and those where the delta had already formed and predicted the trend of the response of the Gamcheon-Nakdong River delta. However, the actual retreat in the Gamcheon-Nakdong River delta was not captured fully due to errors and limitations in the simplification process. The insights through this study provide basic information on the sediment supply of the Nakdong River through the confluence areas, which can be implemented as a basic model for river maintenance and management.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.216-217
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• 2022

Gulpur 수력발전 프로젝트는 전력난을 겪고 있는 파키스탄에 102 MW 규모의 수력발전소를 건설하여 30년 동안 운영 관리한 후 파키스탄 정부로 양도하는 IPP(Independent Power Producing) 형식의 투자사업이다. 남동발전과 DL E&C, 롯데건설이 Sponsor로서 출자한 자본금과, ADB, IFC, K-EXIM 등의 대주단로부터의 차입금을 재원으로 하여 소요 사업비를 조달하고 사업을 개발하였다. DL E&C와 롯데건설이 EPC(Engineering, Procurement, Construction)를 수행하였고, 이산이 Design consultant의 역할을 수행하였다. Gulpur 수력발전 프로젝트의 발전형식은 수로식(run-of-river)으로 201 m³/s의 발전유량과 102 MW의 발전 시설용량을 이용하여 연평균예상발전량은 398 GWh이다. 주요 구조물로는 설계 재현빈도 1년의 유수전환시설(가물막이댐 & 가배수터널)과 콘크리트 중력식댐(H 67 m, L 205 m), 도수터널(D 6.7 m, L 215 m, 2기), 옥외형 발전소 (H 51 m, W 60 m, L 38 m, Kaplan 2기)가 있으며, 2015년 10월 착공하여 2020년 3월 상업발전을 시작하였다. 본 프로젝트는 DL E&C의 첫 번째 EPC 해외수력발전 프로젝트이다. 따라서 프로젝트의 성공적 수행을 위한 경제적 설계, 시공의 효율성 및 안정성 확보 등을 위하여 많은 연구를 수행하는 과정에서 다양한 기술 개선을 이룰 수 있었다. 본고에서는 Gulpur 프로젝트를 통하여 도출된 성공 사례들을 소개 및 공유하고자 한다. 첫 번째로 콘크리트 중력식댐 시공을 위한 유수전환시설의 최적 설계빈도를 산정하였다. 일반적으로 유수전환시설의 규모는 설계기준에 제시된 설계 재현빈도를 이용하는데, 해외 설계기준에서는 10년, 국내 설계기준에서는 1~2년으로 다르게 제시되어 있는 문제점이 있다. 유수전환시설의 규모는 프로젝트의 경제성에 큰 영향을 미치기 때문에 최적 설계빈도의 결정이 필요하며, 위험도분석기법(Risk Analysis)과 기대화폐가치법(Expected Monetary Value)을 이용하여 유수전환시설의 최적 설계 재현빈도와 이에 영향을 미치는 인자를 분석하였다. 위험도는 몬테카를로 시뮬레이션으로 산정된 가물막이댐 파괴확률과 재현빈도를 이용하여 산정된 가물막이댐 월류확률을 고려하였으며, 비용 및 피해액으로는 유수전환시설의 공사비, 가물막이댐 파괴시의 재건설비용과 지체보상금, 가물막이댐 월류시의 복구비용을 고려하였다. 이에 대한 연구결과로, 유수전환시설의 사용기간과 월류시의 복구비용이 유수전환시설의 설계 재현기간 결정에 가장 큰 영향을 미치는 것으로 나타났고, 특히 월류시의 복구비용이 작을수록 낮은 설계 재현빈도를 선택하는 것이 타당한 것으로 나타났다. 예를 들어, 유수전환시설의 사용기간이 3 ~ 5년, 복구비용이 0.5 ~ 1.0 mil USD 이하인 조건에서 가물막이시설의 최적 설계빈도는 1년 ~ 2년인 것으로 나타났다. 또한, 유수전환시설의 사용기간은 본댐의 규모와 시공기간 등을 고려하여 결정되는 사항으로 설계자가 임의 조정할 수 없지만, 복구비용은 시공 관리자에 따라 결정되는 부분으로, 적극적 홍수 피해 저감 및 복구방안을 마련하는 것이 프로젝트의 경제성을 향상시킬 수 있다는 것을 알 수 있었다. 두 번째로 프로젝트의 경제성 향상, 홍수기 댐 시공시의 안전성 확보를 위하여 홍수 조기경보시스템(Early Warning System)을 개발 및 활용하였다. 수로식(Run-of-river) 수력발전댐은 대부분 산악지역에 위치하기 때문에 국지성 강우 및 급한 지형 경사로 인하여 돌발홍수(flash flood)의 발생 가능성이 높다. 따라서 시공 중 홍수(월류) 발생을 미리 감지하고 현장에 전파할 수 있는, 수로식(Run-of-river) 수력발전댐 현장을 위한 홍수 조기경보시스템이 필요하며, 이를 리스크 인식, 모니터링 및 경보, 전파 및 연락, 반응 능력 향상의 4가지 부분으로 나누어 구축하였다. 리스크 인식 부분에서는 가물막이댐 월류 발생 상황에 대한 위험도, 취약성, 리스크를 제시하였으며, 모니터링 및 경보 부분에서는 상류 측정수위에서 유도된 현장 예상수위와 실제 현장 측정 수위를 대상으로 경보홍수위와 위험홍수위로 나누어 관리하였다. 전파 및 연락 부분에서는 현장 시공 조직을 활용하여 홍수시를 대비한 비상연락체계도(Emergency communication flow chart)를 운영하였으며, 반응 능력 향상을 위해 비상연락체계도의 팀별 Action plan을 상세화 하였다. 세 번째로 현장의 지질특성과 50여 차례 발파시험으로 현장 고유의 발파진동감쇄곡선을 도출하였으며, 이를 통해 현장의 시공성과 콘크리트 품질 확보를 동시에 달성할 수 있는 방안을 제시하였다. 콘크리트댐 공사에서는 제한된 공기 내에 공사를 완료하기 위해 사면부 굴착과 콘크리트 타설이 동시에 수행될 수밖에 없는 문제점을 가지고 있다. 그러나 신규 콘크리트 타설면 근처에서 발파를 수행하는 경우 발파로 발생되는 탄성파가 일정 수준을 초과하게 되면, 콘크리트 양생에 영향을 주게 된다. 따라서 다수의 현장 발파시험을 통해 발파거리와 최대진동속도의 상관관계 즉, 발파진동감쇄곡선을 도출함으로써 현장의 발파진동특성을 도출할 수 있었다. 또한, 기존 연구 논문들을 통해 콘크리트 재령기간 별 안전진동속도를 선정하고, 해당 안전진동속도를 초과하지 않는 범위에서 콘크리트 타설면과 발파위치의 거리에 따라 1회 발파 가능한 장약량을 산정하여 적용하였다. 이와 같은 체계적인 접근을 통해 콘크리트 타설과 발파 작업 동시 수행에 대한 논란을 해소할 수 있었다.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.41 no.4
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• pp.49-56
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• 2023

This study analyzes the entirety of Okhojeongdo's content found in the Punggojip, written by Kim Jo-Sun, who created Okhojeong. Through an examination of the literature confirming Okhojeong within the Punggojip, the study compares the existing research with the Okhojeongdo's content. Additionally, it clarifies the relationships between the disciple, the garden, and related historical facts. The results are as follows. First, Kim Jo-Sun, who created Okhojeong, had a strong literary inclination, which made it relatively easy to estimate the original form of the garden, as he expressed detailed content related to the design and management of the garden. Second, the historical dating of the creation of Okhojeong was previously estimated to be around 1815 based on the inscriptions on the Eulhaebyeok. However, it is more appropriate to revise this to 1804, as revealed by Lee Sung-min, who discovered records in Dongseonggyoyeojip, indicating that Kim Jo-Sun purchased the Jang's house. Third, Kim Jo-Sun's literary hobby, as depicted in Punggojip, closely followed Chinese classics. However, the part about creating the garden is supported by factual and garden archaeological records, giving it inherent value. Regarding the expansion of the garden site, it is estimated that the southern boundary of Okhojeong was extended by about half a unit(kan; 間) through a transfer from Kim saeng Saho. Various additions, stone statues, peculiar rocks, ornamental trees, and accompanying elements are found throughout the garden. Particularly noteworthy are the techniques and aesthetics of creating a stone pagoda, and there are mentions of transplanting young pine trees with professional insights. The love for harmony and elegance in the garden is woven throughout the poetry. Additionally, the process of selecting the location for Okhojeong, the understanding of the terrain and topography, the assessment of existing vegetation, the process of cutting down trees and selecting the soil, the construction of houses with tiles and thatched roofs all contribute to demonstrating the comprehensive stages of creating Okhojeong, providing insight into the location and construction process of the Sanbanru pavilion, showcasing the archaeological value of the garden. A follow-up study is needed to excavate more information about the original form of Okhojeong garden through the interpretation of the collections of the literary works of the influential figures introduced in Punggojip in the future.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.2
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• pp.27-41
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• 2014

This study aims to investigate the history, cultural values prototype through literature analysis, characteristics of construction, location, space structure and landscape characteristics by Arc-GIS on the Munam pavilion(聞巖亭) in Changnyeong. The results were as follows. First, Shin-cho((辛礎, 1549~1618) is the builder of the Munam pavilion and builder's view of nature is to go back to nature. The period of formation of Munam pavilion is between 1608-1618 as referred from document of retire from politics and build a pavilion. Secondly, Munam pavilion is surrounded by mountains and located at the top of steep slope. Pavilion was known as scenic site of the area. But damaged in a past landscape is caused by near the bridge, agricultural facilities, town, the Kye-sung stream of masonry and beams. Thirdly, Munam pavilion is divided into the main space, which is located on the pavilion, space in located on the pavilion east and west and the orient space, which is located on the Youngjeonggak. Of these, original form of Munam pavilion is a simple structure composed of pavilion and Munam rock, thus at the time of the composition seems to be a direct entry is possible, unlike the current entrance. Fourth, Spatial composition of Munam pavilion is divided into vegetation such as Lagerstroemia indica trees in Sa-ri in Changnyeong, ornament such as letters carved on the rocks and pavilion containing structure. The vegetation around the building is classified as precincts and outside of the premises. Planting of precincts was limited. Outside of area consists of front on the pavilion, which is covered with Lagerstroemia Indica forest and Pinus densiflora forest at the back of the pavilion. Ofthese,LargeLagerstroemiaIndicaforestcorrespondstothenaturalheritageasHistoricalrecordsofrarespeciesresourcesthatareassociated withbuilder. Letterscarvedontherocksrepresenttheboundaryof space, which is close to the location of the Munam pavilion and those associated with the builder as ornaments. Letters carved on the rocks front on the pavilion are rare cases that are made sequentially with a constant direction and rules as act of record for families to honor the achievements. Fifth, 'The eight famous spots of Munam' is divided into landscape elements that have nothing to do with bearing 4 places and landscape elements that have to do with bearing 4 places. Unrelated bearings of landscape elements are Lagerstroemia indica trees in Sa-ri in Changnyeong, Pinus densiflora forest at the back of the pavilion, Okcheon valley, Gwanryongsa temple and Daeheungsa temple. Bearing that related element of absolute orientation, which is corresponding to the elements are Daeheungsa temple, Hwawangsan mountain, Kye-sung stream and Yeongchwisan mountain. Relative bearing is Gwanryongsa temple, Yeongchwisan mountain and Kye-sung stream Gongjigi hill. At Lagerstroemia indica trees in Sa-ri in Changnyeong, Pinus densiflora forest at the back of the pavilion, Kye-sung stream and Okcheon valley, elements are exsting. Currently, it is difficult to confirm the rest of the landscape elements. Because, it is a generic element that reliable estimate of the target and locations are impossible for element. Munam pavilion is made for turn to nature by Shin-cho(辛礎). That was remained a record such as Munamzip(聞巖集) and Munamchungueirok(聞巖忠義錄) that is relating to construction of pavilion. Munam pavilion located in a unique form, archival culture through the letters carved on the rocks and Large Lagerstroemia indica forest and through eight famous spots, cultural landscape elements can be assumed that those elements are remained.

• Journal of Intelligence and Information Systems
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• v.24 no.1
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• pp.101-124
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• 2018

Recently, most of the technologies have been developed in various forms through the advancement of single technology or interaction with other technologies. Particularly, these technologies have the characteristic of the convergence caused by the interaction between two or more techniques. In addition, efforts in responding to technological changes by advance are continuously increasing through forecasting promising convergence technologies that will emerge in the near future. According to this phenomenon, many researchers are attempting to perform various analyses about forecasting promising convergence technologies. A convergence technology has characteristics of various technologies according to the principle of generation. Therefore, forecasting promising convergence technologies is much more difficult than forecasting general technologies with high growth potential. Nevertheless, some achievements have been confirmed in an attempt to forecasting promising technologies using big data analysis and social network analysis. Studies of convergence technology through data analysis are actively conducted with the theme of discovering new convergence technologies and analyzing their trends. According that, information about new convergence technologies is being provided more abundantly than in the past. However, existing methods in analyzing convergence technology have some limitations. Firstly, most studies deal with convergence technology analyze data through predefined technology classifications. The technologies appearing recently tend to have characteristics of convergence and thus consist of technologies from various fields. In other words, the new convergence technologies may not belong to the defined classification. Therefore, the existing method does not properly reflect the dynamic change of the convergence phenomenon. Secondly, in order to forecast the promising convergence technologies, most of the existing analysis method use the general purpose indicators in process. This method does not fully utilize the specificity of convergence phenomenon. The new convergence technology is highly dependent on the existing technology, which is the origin of that technology. Based on that, it can grow into the independent field or disappear rapidly, according to the change of the dependent technology. In the existing analysis, the potential growth of convergence technology is judged through the traditional indicators designed from the general purpose. However, these indicators do not reflect the principle of convergence. In other words, these indicators do not reflect the characteristics of convergence technology, which brings the meaning of new technologies emerge through two or more mature technologies and grown technologies affect the creation of another technology. Thirdly, previous studies do not provide objective methods for evaluating the accuracy of models in forecasting promising convergence technologies. In the studies of convergence technology, the subject of forecasting promising technologies was relatively insufficient due to the complexity of the field. Therefore, it is difficult to find a method to evaluate the accuracy of the model that forecasting promising convergence technologies. In order to activate the field of forecasting promising convergence technology, it is important to establish a method for objectively verifying and evaluating the accuracy of the model proposed by each study. To overcome these limitations, we propose a new method for analysis of convergence technologies. First of all, through topic modeling, we derive a new technology classification in terms of text content. It reflects the dynamic change of the actual technology market, not the existing fixed classification standard. In addition, we identify the influence relationships between technologies through the topic correspondence weights of each document, and structuralize them into a network. In addition, we devise a centrality indicator (PGC, potential growth centrality) to forecast the future growth of technology by utilizing the centrality information of each technology. It reflects the convergence characteristics of each technology, according to technology maturity and interdependence between technologies. Along with this, we propose a method to evaluate the accuracy of forecasting model by measuring the growth rate of promising technology. It is based on the variation of potential growth centrality by period. In this paper, we conduct experiments with 13,477 patent documents dealing with technical contents to evaluate the performance and practical applicability of the proposed method. As a result, it is confirmed that the forecast model based on a centrality indicator of the proposed method has a maximum forecast accuracy of about 2.88 times higher than the accuracy of the forecast model based on the currently used network indicators.