• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.18-18
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• 2022

하천 합류부에 있어 수체의 혼합양상을 분석은 고해상도의 자료가 필요하다. 반면에 수질환경 문제와 기존 모니터링 시스템이 고정된 측정 방식으로 이루어지기 때문에 하천 전체의 정보는 저해상도의 결과값은 나타낸다. 또한, 많은 수중 환경 문제가 1차원에서 3차원에 걸쳐 있지만, 대부분의 관측 시스템은 1차원에 머물러 있음을 확인할 수 있다. 이러한 문제를 해결하기 위해서는 보다 발전된 관찰 및 계측이 필요하다. 그에 따른 고해상도의 측정 자료를 얻기 위해서는 측정자가부담을 많이 가지며, 측정할 수 있는 영역이나 시간적으로 제한적이다. 해상도는 낮추되 광범위한 데이터를 취득하기 위해서는 적절한 보간법이 선정되어야 한다. 관련 논문을 검토한 결과, 측정 결과에 따른 2차원 횡단면 분포의 내용이 지배적이었고, 3차원 매핑 및 3차원 분석을 통한 수리학적 정보 획득에 관한 연구는 부족한 실정이였다. 특히 3차원 하천 수질 농도의 연구가 불충분했다. 그에 따라 저해상도 측정결과에서의 예측과 보간법에 대한 시각화를 통해 하천의 전체적인 수리·수질정보를 표기하였다. 각각의 보간법을 비교함으로써 하천 매핑에 있어 IDW, Natual Neighbor, Kriging 기법을 적용하여 시각화된 자료와 정량적 평가를 통해 하천매핑의 정밀성을 향상시켰다. 이를 통해 3차원화된 공간보간 자료를 이용한 하천합류부의 혼합양상을 해석하였다. 3차원 데이터를 활용하는 방법으로 측정 및 모니터링 기술의 중요한 데이터로 활용되며, 이러한 데이터는 유해물질 저감 기술 및 평가 예측 기술의 기초 데이터로 활용되고 있다. 유해화학물질 추정, 호수의 고위험 조류군 계층분석 등 다양한 수생건강 진단기술을 활용할 수 있다.

• Journal of Korea Water Resources Association
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• v.51 no.8
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• pp.655-664
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• 2018

The riverbed material survey is to investigate the particle size distribution, specific gravity, porosity, etc. as basic data necessary for river channel plan such as calculation of sediment transport and change of river bed. In principle, the survey spots are 1 km interval in the longitudinal direction of the river and 3 points or more in the 1 cross section. Therefore, depending on longitudinal length of the river to be investigated, the number of surveyed sites is very large, and the time and cost for the investigation are correspondingly required. This study is to compare the particle size analysis method with the volumetric method and the image analysis method in work efficiency and cost and to examine the applicability of the image analysis method. It was confirmed that the diameter of the equivalent circle converted by the image analysis method can be applied to the analysis of bed material particle size. In the gravel stream with a particle size of less than 10 cm and a large shape factor, the analytical result of the bed material by the image analysis method is accurate. However, when the shape factor decreases as the particle size increases, the error increases. In addition, analysis results of the work efficiency and cost of the volume method and the image analysis method showed a reduction of about 80%.

• Journal of Technology Innovation
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• v.26 no.3
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• pp.98-128
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• 2018

This study aimed to investigate the performance on technology collaboration of small and medium enterprises in Korea from the views of resource-based theory. Considering that supplementing the technical resources is stressed in a motivation of technology collaboration from the corresponding theoretical perspective, a group of corporations to be analyzed was classified into three categories such as high, medium and low technologies depending on the technology level. Moreover, technology collaboration partners were also classified into large corporation, small and medium enterprises, university and institution based on that both tangible and intangible assets that belong to a corporation semi-permanently, and the revolutionary performance was analyzed by each relationship of collaboration between parties. The study results revealed that an influence on the performance of technology collaboration varies by technology level of the small and medium enterprises in Korea and their collaboration partners. In particular, the small and medium enterprises of high-tech industry in Korea were confirmed to accomplish relatively less benefits obtaining through technology collaboration compared to the corporations with low technical skills.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.11 no.2
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• pp.17-26
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• 1993

This study aims to develop an effective model of the optimum route determination by using digital terrain model. So in this study I select testing areas and analyse comparing the usual method with the digital terrain model method. And then I present one of the optimum route determination models by analysing an anticipated view and other roads according to the development plan. In usual method, the selected area was analysed by using panoramic terrestrial and aerial photograph. But in this study I represent the present terrain by using digital terrain materials which was acquired by a check form map of the selected area, and predict the route line according to the view points by using basic development plan. As a result of using the digital terrain model method in the optimum route determination with terrestrial photograph, it is possible to explain the terrain in detail when the present conditions terrain is analysed. As we can anticipated many sided road in large scale development plan with digital terrain materials which was used in analysing the present terrain, it is possible to lead to more effective route planning, landers planning and the optimum road determination than the usual method in the basic plan.

• Journal of the Korea Concrete Institute
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• v.18 no.3 s.93
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• pp.379-388
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• 2006

This paper presents a model for evaluating the contribution by arch action to shear resistance in shear-critical reinforced concrete beams. Based on the relationship between shear and bending moment in beams subjected to combined shear and bending, the behavior of a beam is explicitly divided into two base components of the flexural action and the tied arch action. The compatibility condition of the shear deformation that deviates from Bernoulli bending plane is formulated utilizing the smeared truss idealization with an inclined compression chord. The Modified Compression Filed Theory is employed to calculate the shear deformation of the web, and the relative axial displacements of the compression and the tension chord by the shear flow are also calculated. From this shear compatibility condition in a beam, the shear contribution by the arch action is numerically decoupled. Then the validity of the model is examined by applying the model to some selected test beams in literatures. The results may confirm the rationale of the proposed behavioral model.

• The Korean Journal of Financial Management
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• v.22 no.2
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• pp.43-69
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• 2005

This study provides empirical evidence that the stochastic beta model based on Bayesian analysis outperforms the existing conditional beta model and GARCH model in terms of the estimation accuracy and the explanatory power in the cross-section of stock returns in Korea. Betas estimated by the stochastic beta model explain $30{\sim}50%$ of the cross-sectional variation in stock-returns, whereas other time-varying beta models account for less than 3%. Such a difference in explanatory power across models turns out to come from the fact that the stochastic beta model absorbs the variation due to the market anomalies such as size, BE/ME, and idiosyncratic volatility. These results support the rational asset pricing model in that market anomalies are closely related to the variation of expected returns generated by time-varying betas.

• Composites Research
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• v.28 no.6
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• pp.372-377
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• 2015

In this study, we analyzed process numerically when a bogie frame skin is manufactured by applying resin transfer molding process using composite material instead of steel. Processing time was compared based on the various thickness of bogie frame skin and the weight variation of a skin was also considered. As a result, RTM processing time decreases and the weight of a bogie reduces as the thickness of frame skin increases with the assumption that fiber volume is constant inside the skin. By considering these results as the information to estimate the production cost, trade-off between two fields, processing time and structural properties, can be performed in design optimization to produce bogie frame.

• Journal of Korea Water Resources Association
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• v.35 no.6
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• pp.693-701
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• 2002

In this study, one dimensional sediment movement numerical model(HEC-6) and semi-two dimensional sediment movement numerical model(GSTARS 2.1) were applied to solve the change of channel geometry in Bocheong stream. GSTARS 2.1 model was applied for the three selected sediment transport formulas(Ackers and White's, Engelund and Hanson, Yang formula) from 1993 to 2000 measured data on each section. The simulation results of Ackers and White formula for long -term bed changes are good when compared to the measured data. The HEC-6 model was applied for the simulation of one dimensional sediment movement for the same period. Comparison of the long-term simulations by GSTARS 2.1 and HEC-6 models with measured data shows that simulations by both models are in fair agreement with measured data in overall trend of the river bed changes. Comparisons of simulated cross sectional bed-elevations with measured data shows that GSTARS 2.1 model gives better agreement with than simulated results bed changes on the HEC-6 model.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.5
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• pp.485-491
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• 2010

Acquisition of information on failure slope, which may cause apprehension of second hand damage, requires acquisition of fast and accurate topographical data and efficient expression in indirect surveying method without accessing as needed. Therefore, in this study, the images on the intended area were photographed through hovering in the air by approaching collapsed road cut slope with the use of unmanned helicopter photography system. As a result of comparing the points observed by no prism total station and the 10 coordinate points analyzed through image analysis, the averages of absolute values were shown to be 0.056m in X axis direction, 0.082m in Y axis direction and 0.066m Z axis direction. In addition, the RMSE of the error for 10 points of test points were 0.015636m in X axis direction, 0.021319m in Y axis direction and 0.018734m in Z axis direction. Therefore, this method can determine the range of slope and longitudinal and cross sections of each slope in dangerous area that cannot be approached in relational image matching method for the terrains of such collapsed cut slope.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.377-377
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• 2015

부유사 자료는 유사이송해석에 필수적인 요소로 하천의 흐름 변화 및 하상 변동을 발생시키고, 하천 구조물의 설계, 수자원 개발 및 관리를 위한 하천계획의 전반에 있어 매우 중요한 자료이다. 부유사 농도는 수자원의 이용뿐만 아니라 하천 생태계에까지 피해를 미친다는 점에서 하천의 유지 관리 및 보수와도 밀접한 관련이 있다. 부유사량을 산정하는 방법에는 수리량 및 하상토 특성 자료를 유사량 공식에 대입하여 계산하는 간접적인 방법과 유사량을 직접 측정하는 방법으로 나뉜다. 현재 국내에서는 유사량 채집기를 사용하여 실제 하천의 유사량을 채집하는 방식으로 많이 사용되고 있으나, 많은 인력과 시간이 소모되기 때문에 다지점 계측과 지속적인 계측이 힘들다는 한계점를 보이고 있다. 또한 국내 하천에서는 홍수기를 거치면서 하천의 수리학적 특성이 변화하는 경향을 보여주고 있어 유량-부유사 관계식을 자주 갱신해야 한다는 어려움이 있다. 이에 본 연구에서는 현재 국내에서 사용하고 있는 직접적인 측정 방법의 한계점을 보완하고자 직접적인 측정 방법 중 초음파를 이용하여 횡단면 전체의 유사량 측정을 연속적으로 할 수 있는 수평초음파도플러유속계(H-ADCP)를 활용하여 유사량을 추정할 수 있는 기법을 개발하고자 한다. 본 연구의 연구는 건설기술연구원 하천실험센터의 직선수로에서 수행되었다. H-ADCP (SonTek SL3000, 셀 크기 4 cm)를 사용하여 자연상태 흐름조건 (유속 0.7 m/s)에서 초음파산란도(Backscatter, 혹은 신호대잡음비 SNR) 및 유속자료를 2분 간격으로 확보하였다. 그리고 부유사 농도(SSC)의 측정 정확도가 높다고 평가되고 있는 레이저부유사측정기(LISST-100)를 활용하여 부유사 농도를 실측하여 초음파산란도와 실측 SSC의 관계를 도출하고 그 경향을 분석하였다. 또한 초음파산란도의 흡수 등을 보정하고 실측 부유사자료와의 관계식을 기반으로 H-ADCP를 활용하여 실시간으로 부유사 농도를 산정할 수 있는 소프트웨어를 개발하였다.