• The Journal of Engineering Geology
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• v.10 no.2
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• pp.113-133
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• 2000

The role of site investigation for adequate design of civil structure begins from siting to comment on design and providing other available geotechnical data. As the scope of human's life is wider than before, civil works have become conducted at sites of worse geological condition. So, it is necessary to have more adequate comprehension on the geological condition than ever in order to solve complicated geotechnical problems. In this paper, four fault related cases are introduced. Usually faults are the most influential geological structures on civil works. And the analyses with adequate countermeasures to each case are summarized.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.14-17
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• 2007

To make use of surveying data obtained from different sensors and different techniques in a common reference frame, it is a pre-requite step to register them in a common coordinate system. For this purpose, we have developed a methodology to register IKONOS-2 Satellite Imagery using ALS data. To achieve this, conjugate features from these data should be extracted in advance. In the study, linear features are chosen as conjugate features because they can be accurately extracted from man-made structures in urban area, and more easily than point features from ALS data. Then, observation equations are established from similarity measurements of the extracted features. During the process, considering the characteristics of systematic errors in IKONOS-2 satellite imagery, the transformation function were selected and used. In addition, we also analyzed how the number of linear features and their spatial distribution used as control features affect the accuracy of registration. Finally, the results were evaluated statistically and the results clearly demonstrated that the proposed algorithms are appropriate to register these data.

• Journal of Sensor Science and Technology
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• v.15 no.1
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• pp.40-46
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• 2006

This paper presents a novel fiber optic accelerometer system for monitoring vibration of large-size structures. The system is composed of one (or multiple) sensor head, a light control unit and a signal processing unit. The sensing mechanism of the sensor head is based on a novel integration of the moire fringe phenomenon with fiber optics to achieve a robust performance in addition to its immunity to EM interference, easy cabling, and low cost. In this paper, a prototype of the fiber optic accelerometer system has been developed successfully. A low-cost light control unit has been developed to drive the system's optic and electronic components. A unique algorithm has also been developed to derive the sensor's acceleration from the raw signals of the light control unit; it is implemented via a separate signal processing unit. Finally, the shaking table tests successfully demonstrate the performance and the potential of the moire fringe fiber optic sensor system to monitor the health of civil infrastructures.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.161-164
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• 2011

본 논문에서는 MBR 공정 유출수의 화학응집에 따른 특성을 알아보고자 A2O공정 하수처리수를 대상으로 막의 공극 크기와 약품 교반시간 및 응집 침전시간에 따른 인 제거 효율을 조사하였다. 막 여과 전후의 시료에 대한 응집실험결과 막 여과 전후의 응집제 투입에 따른 인 제거효율은 막 여과 전 90%와 비교했을 때 각각 74.5, 71.2, 62.6%로 최고 37.4%까지 큰 차이를 보였으며 이것은 막 여과로 인하여 시료 내 존재하는 콜로이드성 물질들의 입자 크기가 작아져 응집반응을 위한 응집핵 형성에 영향을 주었기 때문이며 막의 공극 크기가 작을수록 인 제거 효율도 감소하는 것으로 나타났다. 완속교반과 침전시간을 길게 할수록 인 제거 효율이 증가하였다. 침전시간이 10분일 경우는 인 제거 효율이 막 여과 후의 시료에 대해서 각각 45.3, 35.1, 52.0%로 인 제거가 상당히 불안정하였고 60분일 경우에는 각각 83.4, 85.1, 80.7%로 탁월한 인 제거가 일어난 것을 알 수 있었다.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.653-656
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• 2010

개착식 구조물의 내진성능 예비평가는 설계자료나 현장조사를 토대로 지진도 그룹, 취약도 지수, 영향도 지수를 산정하여 내진성능 상세평가의 시행여부를 판단하는 근거가 되어왔다. 내진성능 예비평가를 적용했던 사례를 분석한 결과 평가항목 산정 시 근거가 미약하고, 내진성능 상세평가 대상으로 분류되지 않은 그룹에 대해 구조적 내진성능 확보가 불확실하여 내진성능 예비평가를 개정하였다. 개정한 내진성능 예비평가는 지진도 그룹, 취약도 지수, 영향도 지수를 적용하는 기존의 틀은 유지하면서 평가항목을 산정하는 근거를 명확하게 하였으며, 내진성능 상세평가를 실시하지 않는 그룹에 대해서도 간략하게 구조적 내진성능 확보여부를 검토할 수 있는 전단변형각을 도입하였다. 본 연구에서는 개정한 내진성능 예비평가를 기존 사례에 적용하여 결과를 도출하였으며, 기존의 적용 사례와 비교 분석하였다.

• Korean Journal of Computational Design and Engineering
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• v.19 no.3
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• pp.281-293
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• 2014

Although there have been a lot of BIM R&Ds in the civil engineering and their applications to the real projects, BIM in the field is still known to be behind the other areas. One of the reasons for this should be that the civil projects is generally too public for private participants to try new technologies, but it is mainly because the projects are so huge and complex that we still have the working environment where the systematic information sharing or exchanging is not smooth enough. In this paper, we are verifying the possibility and proposing the direction of BIM information standardization technology in civil engineering based on the integrated BIM information standard framework. For this purpose, after reviewing the introduction plan for BIM information framework, we applied it to an actual civil structure for test. The implementation result proved that the framework has possibility and effectiveness for the takeoff and construction cost calculation, which confirmed the standard framework needs to be extended consistently. This study is expected to contribute to the standard system establishment and its technology propagation for BIM development in the civil engineering.

• International Journal of Naval Architecture and Ocean Engineering
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• v.2 no.2
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• pp.68-74
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• 2010

The development of a numerical model using the fractional area/volume obstacle representation (FAVOR) method for predicting a nearshore current field bounded by complicated geometric shapes, and a three-dimensional (3D) beach evolution was described in this article. The 3D model was first tested against three cases to simulate the nearshore current fields around coastal structures, a river mouth, and a large scale cusp bathymetry. Then, the morphodynamic model tests, which are adopting the nearshore current model, were applied for the computations of beach evolution around a detached breakwater and two groins. It was confirmed that the presented model associated with the FAVOR method was useful to predict the nearshore current field in the vicinity of the complicated geometric shapes. Finally, the model was applied to a tombolo formation in a field site of Kunnui fishery port, which is located in Hokkaido, Japan.

• Environmental Engineering Research
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• v.17 no.2
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• pp.111-116
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• 2012

This study investigates the complete removal of nitrate and the recovery of valuable ammonium salt by the combination of nanoscale zero-valent iron (NZVI) and a membrane contactor system. The NZVI used for the experiments was prepared by chemical reduction without a stabilizing agent. The main end-product of nitrate reduction by NZVI was ammonia, and the solution pH was stably maintained around 10.5. Effective removal of ammonia was possible with the polytetrafluoroethylene membrane contactor system in all tested conditions. Among the various operation parameters including influent pH, concentration, temperature, and contact time, contact time and solution pH showed significant effects on the ammonia removal mechanism. Also, the osmotic distillation phenomena that deteriorate the mass transfer efficiency could be minimized by pre-heating the influent wastewater. The ammonia removal rate could be maximized by optimizing operation conditions and changing the membrane configuration. The combination of NZVI and the membrane contactor system could be a solution for nitrate removal and the recovery of valuable products.

• Journal of Environmental Science International
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• v.12 no.5
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• pp.541-549
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• 2003

Aerosol measurement were carried out to investigate the characteristics of its chemical composition directly affected by the local emissions of Jeju City, Jeju Island by using an eight-stage cascade impactor from Dec. 1999 to Aug. 2000. The ambient aerosol concentrations measured at Jeju City were generally very low but the fine particle concentrations were to be higher than the US standard of PM2.5. The majority of sulfate were non sea salt and contained in the fine particles. In the fine particles, the concentrations of Na$\^$+/, K$\^$+/, Mg$\^$2+/, Ca$\^$2+/, Cl$\^$-/ and NO$\sub$3$\^$-/ had a tendency to increase during the springtime rather than the other seasons. However, the springtime sulfate and ammonium concentrations in the fine particles were slightly lower than those during the other seasons. On the other hand, associated with the coarse particles, the concentrations of ionic species except potassium and ammonium were elevated during the springtime. The calcium concentrations in the coarse particles were increased up to 8 times relative to the other seasons.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.439-447
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• 2015

In this study, specific sections vulnerable to debris flow damage were selected, and a complete enumeration survey was performed for the sections with debris flow hazards. Based on this, the characteristics of the sections with debris flow hazards and the current status of actions against debris flow were examined, and an efficient installation plan for a debris flow damage prevention method that is required in the future was suggested. The results indicated that in the Route 56 section where the residential density is relatively higher between the two model survey sections, facilities for debris flow damage reduction were insufficient compared to those in the Route 6 section which is a mountain area. It is thought that several sites require urgent preparation of a facility for debris flow damage reduction. In addition, a numerical analysis showed that for debris barriers installed as a debris flow damage prevention method, distributed installation of a number of small-scale barriers facilities within a valley part was more effective than single installation of a large-scale debris barrier at the lower part of a valley.