• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.55-55
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• 2020

개수로 흐름에서 유체특성을 파악하는 것은 매우 중요하다. 특히 홍수가 발생하거나 유속의 증가에 따라 유체의 거동은 복잡하고 예측하기 어려워진다. 이러한 복잡한 유체거동은 하천시설물 설계, 시공 및 관리에 있어서 구성재료의 보호능력에 따라 예상하지 못한 조건에서 쉽게 파손될 수 있다. 국내 하천의 경우 한계유속과 한계소류력에 의해 하천설계에 적용되고 있다. 한계 유속의 경우 간단한 수식에 의해 산정될 수 있지만 실제 하천의 보호능력을 대표하기는 힘들기 때문에 한계소류력이 동시에 고려되어야 한다. 한계소류력은 개수로 흐름에서 복잡하게 발생하는 이차류나, 난류 특성에 의해 산정하거나 예측하기는 매우 어렵다. 한계 소류력 뿐만 아니라 하천을 구성하는 재질의 조도계수 역시 균일하지 못하고 매우 예측하기 어렵다. 따라서 본 연구에서는 이러한 복잡한 양상을 나타내는 수리학적 요소에 대해 표준화된 실험수로에서 실험을 통해 평가하고, 체계화된 설계지침이 되고자 연구를 진행하였다. 본 연구에서는 자연하천과 유사한 조건의 경사를 가지는 경사수로와 경사의 영향에서 자유롭게 평가를 진행하고자 무경사수로에서 실험연구를 통해 제방 재료의 안정성 평가방법을 제시하고, 재체의 안정성 평가를 위한 실험진행은 기 개발된 바닥응력을 직접측정하는 장치와 PIV시스템을 이용하여 수리특성을 측정하였다.(Park J.H. et al. 2016, Flow Measurment and instrumentation.) 하천의 설계나 평가에 적용되는 평균 소류력 개념은 복잡한 난류흐름에서 평가지표로써 대표하기 힘들기 때문에 바닥에서 발생하는 소류력을 직접 측정하고, 측정된 소류력을 검증하고자 난류유속 u', v'을 이용하여 Reynolds stress산정하여 Total shear stress를 추정하는 기법을 사용하여 검증하고자 한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.73-80
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• 2008

Experimental study has been performed in order to construct the standard test methods and appraisal criteria by investigating the influence of specimen types(property, width, layers) and loading rate on the tensile characteristics of FRP used in strengthening RC structures. The FRP composite tested in this study are the unidirectional CFRP sheet/strip and the bidirectional GFRP sheet. Test variables consist of the various width ranging from 10mm to 25mm and number of CFRP sheets plied up to 5 layers. Test results indicated that maximum tensile strength and minimum coefficient of variation are recorded at each different width according to the fiber types and weaving directions. Also, the average tensile strengths of CFRP sheets are decreased as the number of layer of CFRP sheet are increased.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.5
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• pp.589-597
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• 2024

The chub mackerel Scomber japonicus is the most important commercial species caught primarily by large purse seine fisheries. The effective management of chub mackerel resources requires a thorough understanding of the current stock status and the factors driving its fluctuations. The catch per unit effort (CPUE) is a crucial index representing the relative abundance of resources, and CPUE standardization was applied using a generalized linear model and generalized linear mixed model (GLMM). This study adopted various explanatory variables including spatiotemporal factors of Year, Month and Area (spatial clustering), and environmental factors of seawater temperature at a depth 50 m ((T50) and Tsushima Warm Current transport (TWC) and catch ratio of chub mackerel (Ratio). The GLMM, which incorporates random effects, was identified as the optimal model. Ratio had the most significant effect on the CPUE, and environmental and spatio-temporal factors had significant influences. Although the nominal CPUE showed an increasing trend across different areas, the standardized CPUE either decreased or exhibited a decreasing rate of increase. These findings serve as fundamental data for stock assessment and contribute to the spatiotemporal and environmentally informed management of chub mackerel resources in Korean waters.

• The Journal of Engineering Geology
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• v.29 no.4
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• pp.509-529
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• 2019

This study performs to evaluate the role of filter material at alluvial well for intake of riverbank filtration and the applicability and improvement effect of dual filter well. To achieve this objective, dual filter intake well and single filter intake well were installed with different filter conditions at riverbank free surface aquifer in soil layer then we evaluated filter material condition, permeability, optimum yield and well efficiency according to yield in drawdown test. As a results, we assumed forming dual filter layer minimizes sudden speed changes at boundary between aquifer and filter layer by cushioning of groundwater flow. This suppresses warm current then intake groundwater efficiently, therefore it seems decreasing peripheral groundwater level changes in spite of higher intake water amount than single filter intake well. Furthermore, we confirmed by test, installing dual filter improves permeability, optimum yield and well efficiency. The result will be used by combining with former study to set up standard of design/construction of dual filter intake well at alluvial aquifer layer. Furthermore, we expect this result will be used to prove application effect of dual filter intake well compared to single filter one and radial collector well which are mainly applied on riverbank filtration.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.35-41
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• 2002

This research introduces the development of a project-level cash flow forecasting model in construction stage based on the planned earned value and the cost from a general contractors view on a jobsite. Most previous models have been developed to assist contractors in their pre-tendering or planning stage cash flow forecasts. The critical key to cash flow forecasting at the project level is how to build a cash-out model. The basic concept is to use moving weights of cost categories in a budget over project duration. The cost categories are classified to compile resources with almost the same time lags that are based on contracting payment conditions and credit times given by suppliers or venders. For cash-in, net planned monthly-earned values are simply transferred to the cash-in forecast, to be applied there with billing time and retention money. Validation of the model involves applying data from on-going 4 projects in progress for 12 months. Based on the results of the comparative analyses through the simulation of the proposed model and the existing models, the proposed model is more accurate, flexible and simpler than traditional models to the employee of construction jobsite who is not oriented financial knowledge.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.957-967
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• 2013

While a vast number of cad drawings are produced in the life cycle of construction projects from the planning, design, and construction phases to the maintenance and control phases, the creation and distribution of non-standard drawings make it difficult for the construction parties to communicate with one another and to recycle, maintain, and control drawings by project phase. The Korea standard of CAD drawing in construction CALS/EC, which stipulates the standard for construction CAD drawings, is based on roads, rivers, and railways in line- and unit-based structures, allowing the creation of standardized CAD drawings. Such standard, however, cannot be easily applied to construction projects with multiple facilities like harbors, housing sites, or lands consisting of surface forms. In particular, port field consist of complex docks and amenities located in a certain coastal area based on multiple objectives. They also contain the concept of housing sites, like background land, and are composed of various civil engineering facilities, construction facilities, and port field, so that the existing CAD drawing standard cannot be easily implemented. Therefore, the purpose of this study is to maximize the efficiency of the information related to drawing information and to ultimately support smooth information exchanges in construction design by conducting a development research on the expansion of the CAD drawing standard that meets the needs of port field.

• Tunnel and Underground Space
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• v.30 no.3
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• pp.214-225
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• 2020

Uniaxial compressive strength (UCS) of rock is one of the important factors to determine the advance speed during shield TBM tunnel excavation. UCS can be obtained through the Geotechnical Data Report (GDR), and it is difficult to measure UCS for all tunneling alignment. Therefore, the purpose of this study is to predict UCS by utilizing TBM machine driving data and machine learning technique. Several machine learning techniques were compared to predict UCS, and it was confirmed the stacking model has the most successful prediction performance. TBM machine data and UCS used in the analysis were obtained from the excavation of rock strata with slurry shield TBMs. The data were divided into 8:2 for training and test and pre-processed including feature selection, scaling, and outlier removal. After completing the hyper-parameter tuning, the stacking model was evaluated with the root-mean-square error (RMSE) and the determination coefficient (R²), and it was found to be 5.556 and 0.943, respectively. Based on the results, the sacking models are considered useful in predicting rock strength with TBM excavation data.

• Journal of Bio-Environment Control
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• v.12 no.3
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• pp.114-120
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• 2003

In order to provide fundamental data for development of controlled environment facilities in Korean ginseng (Panax ginseng C.A. Meyer) cultivation, field survey and analysis of structural and environmental engineering characteristics on the shading structures in ginseng fields (the ginseng houses) were carried out. In this study shading structures for ginseng cultivation were classified according to their structural materials, connection types, and detailed structures. That is they were classified into wood or steel frames, single or multi spans, and frame or cable types. As a result of the investigation, standardization of structural materials, fabrication and construction methods arc required. And it was considered that a reinforced design and a countermeasure for heavy snow are the most important matters for structural improvement. In parts of the environmental management, researches for setting up the irrigation standard are required in the first place. And it was investigated that an installation of the shading structures is a work being the most hard, taking a lot of time, and having need for automation. So controlled environment ginseng houses, with a low cost, a structural safety and a satisfactory workability, should be developed.

• Korean Journal of Construction Engineering and Management
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• v.9 no.5
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• pp.149-158
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• 2008

Plant construction is being a motive power of national economic growth, because it is a higher value-added business which has enormous influence through other industry. But, plant projects management of the domestic company was poor. So, the development of EPC Business Process Management method has been encouraged. Therefore, this paper performed several researches for setting up the EPC Business Process Management Model for improving plant project management. And the details are as follows. First of all, this study collected the work procedure manuals of 12 large-sized international construction companies. Secondly, from the analyzing gathered EPC work procedure manuals, issues of work procedure manuals were analyzed and improvement plans were drawn out. Basis on this, This study presents a method to improve project management for EPC plant project. 'The Work Procedure Matrix for EPC Management' and 'Key Unit Works for EPC Management' were drawn out by using overseas construction management theories and international regulations. In addition, 'The EPC Business Process Management Models' reformed to the Business process method, that is the set of specifications, documents and procedures used to manage the EPC plant project. And it describes how the EPC work procedure manuals will be used. Finally, this study suggests the model of EPC Business Process Management System. The framework of Plant project management can be clarified by using 'The Work Procedure Matrix'. And 'Key Unit Works' are used to organize the work procedure needed to improve plant projects management. The results of this study will help to improve in project management efficiency for plant construction.

• Korean Journal of Construction Engineering and Management
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• v.17 no.4
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• pp.3-11
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• 2016

Recently, overseas plant orders of domestic enterprises are steadily increased, and the amount of orders in the first half of 2014 were 93% increased compared to the previous year. In addition, now which is the third quarter of 2015, overseas plant orders are already over 249.8 billion dollars so the interests of plant industry research has been increased. In the life cycle of the plant project, CM before the construction stage is to complement the uncertainties that are inherent in the early stages of the project, and from the viewpoint of supporting the rational decision-making, the importance of its role is on the rise. Among them, excavating and investing participation plan in the planning stage is an important work that has a large impact force to influence the success and failure of future project. However, the work has become a problem with frequent consultations due to decision-making, continuous modification, and inefficient repetitive tasks. Therefore, it is needed that work process should be changed to effectively accommodate. The purpose of this paper is to derive the major work items for excavating and investing participation plan in the planning stage of the plant project, and establish a standardized work process through the Delphi analysis. The result of this study is expected to be utilized for EPC companies in ensuring the technical competitiveness in planning on overseas markets, and improve the efficiency of work.