• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.524-524
• /
• 2016

본 연구에서는 홍천 자운지구 고랭지 농업지역을 대상으로 장기간의 유역조사와 하천 모니터링을 통해 관측된 축척 데이터를 이용하여 비점오염저감 효과를 정량화하고 추후 모니터링 자료로서 탁수와 비점오염원 저감시설의 저감효과와 비점오염원의 효율적인 관리를 위한 기초자료를 제공하고자 하였다. 모니터링 결과 소양호 유역의 오염부하(1차 강우사상) 중 홍천군 자운지구의 유역단위 비점오염 저감효과의 분석에는 강우량과 단위면적당 오염부하를 이용하였으며, 자운천은 SS 5,396,761 kg, COD 82,261 kg, BOD 57,329 kg, T-N 68,711 kg, T-P 3,091 kg이었으며, 오염부하(2차 강우사상)는 SS 320,293 kg, COD 34,588 kg, BOD 22,350 kg, T-N 48,954 kg, T-P 640 kg으로 나타났다. 또한 소양호 유역의 EMC(1차 강우사상) 중 자운천은 SS 829.9 mg/L, COD 12.7 mg/L, BOD 8.8 mg/L, T-N 10.567 mg/L, T-P 0.475 mg/L 이었으며, EMC(2차 강우사상)는 SS 68.6 mg/L, COD 7.4 mg/L, BOD 4.8 mg/L, T-N 10.487 mg/L, T-P 0.137 mg/L로 나타났다. 소양호 유역의 단위면적당 오염부하(1차 강우사상) 중 자운천은 SS 402.0 kg/ha/event, COD 6.1 kg/ha/event, BOD 4.3 kg/ha/event, T-N 5.118 kg/ha/event, T-P 0.230 kg/ha/event 이었으며, 오염부하(2차 강우사상)는 SS 23.9 kg/ha/event, COD 2.6 kg/ha/event, BOD 1.7 kg/ha/event, T-N 3.646 kg/ha/event, T-P 0.048 kg/ha/event로 나타났다. 오염부하에서는 1차 강우에 비해 2차 강우에서는 SS 5,076,468 mg/L, COD 47,673 mg/L, BOD 34,979 mg/L, T-N 19,757 mg/L, T-P 2451 mg/L로 1차 강우사상에 비해 오염부하가 낮은 것으로 나타났다. 또한 EMC에서는 1차 강우에 비해 2차 강우에서는 SS 761.3 mg/L, COD 5.3 mg/L, BOD 4.0 mg/L, T-N 0.080 mg/L, T-P 0.338 mg/L로 1차 강우사상에 비해 EMC가 저감되었다. 단위면적당 오염부하는 1차 강우에 비해 2차 강우에서는 SS 378.1 mg/L, COD 3.5 mg/L, BOD 2.6 mg/L, T-N 1.472 mg/L, T-P 0.182 mg/L로 1차 강우사상에 비해 EMC가 저감되었다. 강우량과 강우강도 그리고 영농활동의 시기에 따른 EMC와 단위면적당 오염부하는 큰 차이를 보였으며, 예년에 비해 적은 강수량으로 인해 탁수와 비점오염부하의 배출이 상대적으로 적었던 것으로 판단된다. 소양호 유역과 같은 넓은 유역에서 시행되는 비점오염원의 저감연구는 오랜 시간 동안 자료를 축적해야 유의미한 평가가 이루어질 수 있으므로 장기적이고 지속적인 모니터링을 통한 유량 데이터 자료구축과 수질분석뿐만 아니라, 발생되는 비점오염 물질의 관리를 위한 체계적인 연구가 지속되어야하며, 아울러 농민의 인식도 변화 등을 포함하는 많은 인자들을 정밀히 조사하고 다각도로 분석하여 저감효과에 대한 지속적인 연구가 필요하다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.1
• /
• pp.93-100
• /
• 2013

The objective of present study is to investigate the sensitivity of aerostatic force coefficients of twin box girder of Yi Sun-sin Bridge according to the Reynolds numbers. This paper presents the 1:30 scale sectional model tests conducted at high speed wind tunnel in Korea Air Force Academy. Comparison with results at low Reynolds number obtained in KOCED Wind Tunnel Center in Chonbuk National University is also provide. The Reynolds number dependency of aerodynamic force coefficients were observed at present streamlined twin box girder. The drag coefficient revealed significant decrease of nearby 23% at supercritical region. The boundary layer trip strip was found to reduce the Reynolds number dependency of aerodynamic forces by fixing the location of flow transition.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.8 no.3
• /
• pp.129-141
• /
• 2005

It is difficult to edit large-scale digital maps because of problems of cost and process and it is carried out by aerial photogrammetry in renewal periods. Five years of update period cannot provide exact data required in the fast-moving age. This study is to analyze applicability and impact for editing digital map of road system using the GPS-Van. Results are compared with accuracy of the data acquisition with GPS-Van positioning. INS data are affected by the barrier to receive GPS data. But high accuracy were achieved by thorough plans according to work order. By using GPS Van and fieldwork at the same time for editing and renewal of digital map, it is expected that this method can be used to reduce costs in the economic and temporal aspects, and provide rapid and accurate digital map of road system.

• Spatial Information Research
• /
• v.10 no.3
• /
• pp.469-480
• /
• 2002

Nowadays, digital maps of 1:5,000 scale are used to plan and review far road alignment design. However, the updating and modifying period of digital maps is not so harmonious as topographical changes caused by rapid developments can be reflected in digital maps, the different areas between real surface and digital map can be found easily. This research is aimed to suggest that the use of high resolution satellite image is effective way to get latest topographical information for road alignment design about wide region. IKONOS satellite images were geometrically corrected, and the road alignment data previously designed by traditional procedure were overlapped on the satellite images. As a result, the satellite image maps clearly described wrong road alignment, and modification of road alignment could be accomplished adequately By these procedures, road alignment design was Improved in quality, and could be reasonable and economic design to prevent modification that would be happened in the next step of practical plan. For the geometric correction method of IKONOS images, Thin Plate Spline(TPS) transformation with large number of ground control points, as well as ortho rectification, was effective.

• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.2
• /
• pp.83-93
• /
• 1998

The twin aims of the present study are to develop a PC program for the statistical analysis of the measured cohesion data and to suggest a probabilistic corrosion rate estimation model for longitudinal members of tanker structures. A data analysis for the corrosion rate statistics(i.e., mean, standard deviation) as a function of the corrosion parameters is established for various structural member categories/locations of interest. Development of the computer program is focused on possible operation together with future addition of more corrosion data as they become available. To investigate the influence of the corrosion protection scheme a series of the corrosion analysis varying the life of coating are carried out and several different corrosion models as a function of time are suggested depending on the coating life.

• Water for future
• /
• v.25 no.3
• /
• pp.87-96
• /
• 1992

Hydraulic characteristics such as velocity, surface level and flow pattern in the curved channel are analyzed by model experiment, where model is scaled down by 1:20 for prototype channel containing side branch and curved section. The withdrawal of channel flow from channel is analyzed to find the effect on the curve section. The numerical scheme for shallow water equation using ADI method is verified through the comparison of hydrauric characteristics by experiment with that by numerical analysis in the side section of model channel. The comparison of numerical results with experimental data shows that velocity, surface level and flow pattern agree well for overall channel. Because fo the relative contraction of cross section in the curved section caused by rectangular system, the velocity calculated by numerical analysis is faster in curved section than that from experiment, which can be improved using finer spatial grid in curved section. The characteristics of the curved section such that the surface level is higher in the outer zone of curved section and the velocity is faster in the inner zone are well simulated by both experiment and numerical analysis. The effect of side branch reaches within the zone of the curved section.

• Journal of the Korean Geotechnical Society
• /
• v.34 no.4
• /
• pp.49-55
• /
• 2018

A pre-load of bracing was imposed to prevent the horizontal displacement on the strut of the braced wall adjacent to the building during the ground excavation. For this purpose, large scale model tests were conducted, without and with pre-load on braced wall. Adjacent building load was also imposed in different locations, that were 0 m, 1D, 2D on ground surface. In this study, model tests in 1:10 scale were performed in real construction sequences, and adjacent building was 12 m in width and the size of model test pit was 2 m in width, 6 m in height, and 4 m in length. As a result, it was found that the stability of the existing building adjacent to the braced wall within Rankine's active zone could be greatly enhanced when the horizontal displacement of the braced wall was reduced by applying a pre-load. which was larger than the designated axial force on the strut of the braced wall.

• Journal of Convergence for Information Technology
• /
• v.7 no.3
• /
• pp.73-81
• /
• 2017

The generalized Hough transform (GHough) is a useful technique for detecting and locating 2-D model. However, GHough requires a 4-D parameter array and a large amount of time to detect objects of unknown scale and orientation because it enumerates all possible parameter values into a 4-D parameter space. Several n-to-1 mapping algorithms were proposed to reduce the parameter space from 4-D to 2-D. However, these algorithms are very likely to fail due to the random votes cast into the 2-D parameter space. This paper proposes to use internal gradient information in addition to the model boundary points to reduce the number of random votes cast into 2-D parameter space. Experimental result shows that our proposed method can reduce both the number of random votes cast into the parameter space and the execution time effectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.18 no.1
• /
• pp.1-9
• /
• 2000

In the recent day, the necessity and the effective usage are increased rapidly, and it is applied in many other fields as well as in the field of ortho-photo map. In this study, we extract each objects on the aerial image and automatically classify graphic information to produce digital map using only digital ortho-image without particular drawing devices for producing digital map. For this purpose, we have applied a lot of the image processing techniques and fuzzy theory, classified outline and lane of road and building, and had each layer according to each feature. Especially, in the case of the building, the outer vector lines extracted by pixel unit at the building were very complex, but we have developed the program to be expressed by I-dimensional linear type between building corners. In the result of this study, we could not extract and recognize all of the object on the image all together, but we have got the error within 50cm using semi-automatic technique. Therefore, this method will be used effectively in producing 1/5,000 digital map.

• Membrane Journal
• /
• v.25 no.3
• /
• pp.276-286
• /
• 2015

The effects of relaxation and backwashing on fouling in ultrafiltration were investigated using full-scale membrane bioreactors (MBRs) which operated at a constant flux of 30 LMH. This paper also estimated the feasibility of using intermittent aeration strategies for minimizing the hydraulic resistance to filtration in comparison with the continuous aeration for running MBRs. Multiple cycles of filtration (14.5 min each) and relaxation (0.5 min each) were repeated. Similarly, a backwash was conducted by replacing a relaxation after each filtration cycle for the comparative performance test. The attached cake thickness on the membrane rapidly increased, caused by subsequent no aeration leading to easier combining with gel layer and the formation of heterogeneous layer on the membrane surface. During periodic backwashing, it is expected that gel and thin cake layer might sufficiently be removed by heterogeneous layer. After periodic backwashing, subsequent cake layer formation during time of no aeration was rapid than frequent no aeration, acting as a prefilter and preventing further irreversible fouling. Based on the Pearson correlation analysis, overall period fouling (dTMP/min) and average of all cycles (dTMP/min) were strongly correlated with the on-off period of aeration for operating MBRs.