Mobile QR Code QR CODE : Journal of the Korean Society of Civil Engineers

KSCE JOURNAL OF CIVIL AND
ENVIRONMENTAL ENGINEERING RESEARCH

The Journal of the Korean Society of Civil Engineers (KSCE) is a bimonthly journal, founded in December 1981, for the publication of peer-reviewed papers devoted to research and development for a wide range of civil engineering fields.

• Editors-in-Chief: Cheol Woo Park

병치된 변형률 계측치를 이용한 프리팹 PSC 거더 캠버 재구성 Camber Reconstruction for a Prefab PSC Girder Using Collocated Strain Measurements

https://doi.org/10.12652/Ksce.2022.42.2.0151

김현영(Kim, Hyun Young) ; 고도현(Ko, Do Hyeon) ; 박현우(Park, Hyun Woo)

Prefab members have attracted attention because they can be mass-produced in factories through smart construction technology. For prefab prestressed concrete girders, it is important to manage the shapes of the girders properly from production to the pre-installation stage for consistency with the prefab floor plate during the erection process. This paper presents a camber reconstruction method using collocated strain measurements from the top and bottom of the prefab girder. In particular, the camber reconstruction method is applied to measured strain data in which the time-dependent behavior of concrete is considered after the introduction of prestress. Through Monte Carlo numerical simulations, the statistical accuracy of the reconstructed camber for a limited number of sensors, measurement errors, and nonlinear time-dependent behaviors are analyzed and validated.

TiO2 적용방법에 따른 포러스 콘크리트의 질소산화물 제거성능 및 흡음특성 NOx-removal and Sound-absorption Performances of Photocatalytic Porous Concrete Prepared by Various TiO2 Application Methods

https://doi.org/10.12652/Ksce.2022.42.2.0163

윤현노(Yoon, Hyunno) ; 서준호(Seo, Joonho) ; 김선혁(Kim, Seonhyeok) ; 장대익(Jang, Daeik) ; 배진호(Bae, Jinho) ; 이행기(Lee, Haeng-Ki)

The present study investigates NOx-removal and sound-absorption performances of photocatalytic porous concrete prepared by various TiO2 application methods. Photocatalytic porous concrete samples were prepared by one of the following: 1) mechanically mixing TiO2 during casting; 2) mixing bottom ash aggregate pretreated with TiO2 during casting; and 3) spraying TiO2 solution to the normally fabricated porous concrete. The test results indicated that the mechanical mixing of TiO2 decreased the compressive strength as the added TiO2 content increased. The use of pretreated bottom ash aggregate reduced the porosity, yet the compressive strength of the concrete was similar to that measured from the former method. Porous concrete samples sprayed with the TiO2 solution exhibited enhanced compressive strength, while the porosity was analogous to those measured from other methods. The NOx-removal performance was the highest in the samples sprayed with the TiO2 solution, followed by the samples using pretreated bottom ash aggregate and mechanically mixed TiO2. The samples with mechanically mixed TiO2 identified a relationship between soundabsorption performance and porosity. However, no particular tendency was observable in the samples with other TiO2 application methods.

춘천댐 및 소양강댐 운영에 따른 의암호 조류 저감 연구 Study of the Mitigation of Algae in Lake Uiam according to the Operation of the Chuncheon Dam and the Soyang Dam

https://doi.org/10.12652/Ksce.2022.42.2.0171

이동열(Lee, Dong Yeol) ; 백경오(Baek, Kyong Oh)

In this study, the characteristics of algae mitigation according to dam operation were quantitatively analyzed for Uiam Lake, where the Chuncheon Dam is located upstream of the main stream, Uiam Dam is located downstream, and Soyang Dam is located in the tributary stream. Nine dam operation scenarios were applied to the event of the summer of 2018 (at that time an algae alert occurred) using the EFDC model, which is capable of calculating three-dimensional hydrodynamics and water quality levels such as those associated with chlorophyll-a. The dam operation scenarios were set to generate a flushing effect via discharges in the form of pulse waves from the upstream dams and by lowering the water level at the downstream dam. At Uiam Lake, the flushing effect was different depending on the operation of the dam, and the amount of algae reduction at each point was different owing to topographic characteristics and the different base water temperatures from BukHan River and Soyang River. With regard to a point located on the left bank, it was predicted that the peak level of chlorophyll-a would be reduced by approximately 50 % or more upon pulsed discharge at 50 m3/s for three days at Soyang Dam. However, for the right bank, the amount of discharge from Soyang Dam had little effect on algae mitigation. Therefore, an appropriate dam operation could be effective for algae mitigation at specific points in the water body where large dams exist upstream and downstream, such as at Uiam Lake, in an emergency situation in which algal blooms rapidly.

댐체 강화 RIM부 그라우팅을 위한 지반상태 기준 결정 Determining of Ground Condition Criteria for Dam Reinforced RIM Grouting

https://doi.org/10.12652/Ksce.2022.42.2.0181

한기승(Han, Kiseung) ; 이동혁(Lee, Donghyuk) ; 박두희(Park, Duhee)

Dam slope RIM is a highly important contact interface where the main body and the base surface are connected. In general, when the grouting for the slope of the dam structure is designed, it is planned using limited data (drilling, geological map, etc.). This makes it very difficult to accurately consider the original ground characteristics of the slope RIM grouting target, In addition, when the grouting volume planned during the design is drilled and injected into the original ground where the waterstop is secured, there is a possibility that the original ground with the waterstop is disturbed and the effect of the waterstop is rather diminished. In order to overcome such problems, it is more suitable to first consider geological conditions and determine whether to perform optimal grouting on the original ground through on-site repair tests before performing RIM grouting. In this paper, to determine the grouting of the RIM unit, a pilot hole water pressure test was performed on the rock of the slope in the target section. The analysis shows grouting volume of 1 Lugeon or less, and the cement injection amount also shows the injection result of 1 kg/m or less. In this case, performing grouting is rather counterproductive. This result can be evaluated through a rock of which some degree of order of mass is secured, as it is a dam design standard of 1 Lugeon or less when analyzed, using the results of visual observation and geological map creation during slope cutting. Therefore, in conclusion, it is preferable to make the decision for using RIM grouting on the slope of the dam body structure, based on 1 Lugeon in a rock state, and the cement injection amount also at 1 kg/m.

피압 작용에 따른 DCM 개량체의 지반공학적 특성 Geotechnical Characteristics of DCM-Improved Specimen Under Artesian Pressure

https://doi.org/10.12652/Ksce.2022.42.2.0187

윤대호(Yun, Dae-Ho) ; 김윤태(Kim, Yun-Tae)

This study investigated the effect of artesian pressure on mechanical properties of deep cement mixing (DCM)-improved specimens. Various laboratory tests such as unconfined compression test and scanning electron microscope (SEM) were conducted on DCM specimens which curied in a water tank with different artesian pressures. The artesian pressure was determined in consideration of the laboratory scale and the hydraulic gradient in field conditions. Results of experimental tests indicated that unconfined compressive strength, secant modulus, and unit weight of specimen decreased and water content tended to increase as an artesian pressure increased. The stress-strain behavior changed brittle to ductile behaviors as an artesian pressure increased. The outflow water from the water tank reacted with the phenolphthalein solution due to the leaching phenomenon of the improved specimen. SEM analysis also confirmed that a small amount of ettringite was formed between soil particles in the specimens with artesian pressure.

건공화 공법의 발파 성능 평가를 위한 현장 시험에 관한 연구 A Study of a Pilot Test for a Blasting Performance Evaluation Using a Dry Hole Charged with ANFO

https://doi.org/10.12652/Ksce.2022.42.2.0197

이승훈(Lee, Seung Hun) ; 정성훈(Chong, Song-Hun) ; 최형빈(Choi, Hyung Bin)

The existence of shallow bedrock and the desire to use underground space necessitate the use of blasting methods. The standard blasting method under water after drilling is associated with certain technical difficulties, including reduced detonation power, the use of a fixed charge per delay, and decoupling. However, there is no blasting method to replace the existing blasting method. In this paper, a dry hole charged with ANFO blasting is assessed while employing a dry hole pumping system to remove water from the drill borehole. Additional standard blasting is also utilized to compare the blasting performances of the two methods. The least-squares linear regression method is adopted to analyze the blasting vibration velocity quantitatively using the measured vibration velocity for each blasting method and the vibration velocity model as a function of the scaled distance. The results show that the dry hole charged with ANFO blasting will lead to greater damping of the blasting vibration, more energy dissipation to crush the surrounding rock, and closer distances for the allowable velocity of the blasting vibration. Also, standard blasting shows much longer influencing distances and a wider range of the blasting pattern. The pilot test confirms the blasting efficiency of dry hole charged with ANFO blasting.

비대칭적 중방향 교통류 대응을 위한 이동식 중앙분리대 활용 버스전용차로 도입 전략 분석 Operational Strategies of a Bus-Exclusive Lane Using Barrier Transfer Systems to Control Tidal Traffic Flows

https://doi.org/10.12652/Ksce.2022.42.2.0209

김태완(Kim, Taewan) ; 정연식(Chung, Younshik) ; 전교석(Jeon, Gyo Seok) ; 김원길(Kim, Wongil)

Lane management with a central variable lane(s) (or reversible lane) where the traffic flow is temporarily reversed in one or more lanes during peak periods has been evaluated as an effective strategy to alleviate congestion caused by tidal traffic flows. However, due to traffic safety issues, such a movable barrier system can be considered as an alternative to supplement the existing its operation facilities such as static and/or dynamic signs and special pavement markings. In addition, when combined with a bus exclusive lane strategy, its effectiveness could be greatly increased. The objective of this study is to propose a feasibility analysis procedure for operational strategies of a bus-exclusive lanes using a barrier transfer system (BTS) for urban expressways. To this end, a case study was conducted on two urban expressways on the west side of the Han River in Seoul. As a result, temporary operation during rush hour in the morning was found to be most effective. The results presented in this study are expected to serve as a basis for establishing bus-exclusive lane operation strategies using similar systems in the future.

고령운전자의 운전면허증 반납 의사에 인센티브 정책이 미치는 영향 연구 Study of the Effect of Incentive Policies on the Intention to Return the Driver’s Licenses of Elderly Drivers

https://doi.org/10.12652/Ksce.2022.42.2.0219

김주영(Kim, Joo Young) ; 정헌영(Jung, Hun Young)

In Korea, as the aging phenomenon accelerates, the problem of traffic accidents related to the elderly is continuously emerging. Efforts to improve this are being implemented, but unfortunately the results of these effects are not clear. Therefore, in this study, the effect of traffic characteristics and incentive policies on the return of driver's licenses of elderly drivers was reviewed. As a result of the analysis, it was confirmed that the intention to return the driver's license was low in the case of men, older people, those with low dependence on public transportation, those who undertook long driving hours, and those who took frequent trips. On the other hand, financial incentives were found to play a positive role with regard to the intention to return the driver’s license. However, the effect is expected to be insignificant for those with a low intention to return the driver's license. As a result, under the current policy, it is predicted that there is a limit to improving the social problems caused by elderly drivers, meaning that it is necessary to review approaches that induce the return of their driver’s licenses.

개발사업(산업단지, 골프장)의 리스크 분석 및 관리방안 A Study on Risk Analysis and Management Plan for Development Projects

https://doi.org/10.12652/Ksce.2022.42.2.0229

정민영(Jeong, Min Young) ; 이민재(Lee, Min Jae)

With rapid industrialization since the 1960s, development projects have contributed to the development of the national economy. In addition to the development projects promoted by the government, private project operators are also promoting development projects for reasons such as increased public convenience, insufficient financing of SOC assets, and expansion of their own development projects other than public orders. However, as the economy has been stagnating due to several factors such as continued supply of facilities for decades and recent COVID-19, the success of the development projects are unsure these days. Therefore, this study attempted to analyze project costs through the case of such development projects, and to present a plan to judge and manage the risks of each project cost item in advance. The AHP technique, which is widely used as a risk factor selection method for existing development projects, was used, and items were determined through interviews with experts related to development projects in order to stratify the upper and lower subjects of the risk. We analyzed how the derived risk factors affect the business performance through sensitivity analysis, and finally substituted the risk factors management plan into the risk response strategy and suggested.

Kano 모델 기반 건설프로젝트 핵심 리스크관리 요인 도출 Estimation of Key Risk Management Factors for Construction Projects Based on Kano Mode

https://doi.org/10.12652/Ksce.2022.42.2.0239

조진호(Cho, Jin-ho) ; 김병수(Kim, Byung-Soo)

Risks in construction projects are increasing remarkably due to recent changes in the construction environment. Active risk management is required to recognize risks as opportunities. The purpose of this study is to propose a risk management model of the importance determination method through comparative analysis using Kano model, Timko CSC (Customer Satisfaction Coefficient), and ASC (Average Satisfaction Coefficient). Based on previous studies, the validity of risk management factor determination is reviewed through a questionnaire modified Kano model through interviews with working-level workers using the Delphi technique. Through this, a suitable risk management model is presented by selecting key risk management factors recognized by domestic construction project practitioners. As a result of the study, the Kano model developed to verify risk management of construction projects was evaluated to be effective in verifying the risk management of practitioners. It is expected that the Kano model presented in this study will be actively used to verify the importance of risk management for construction projects.

증강현실 시각화를 위해 K-최근접 이웃을 사용한 BIM 메쉬 경량화 알고리즘 BIM Mesh Optimization Algorithm Using K-Nearest Neighbors for Augmented Reality Visualization

https://doi.org/10.12652/Ksce.2022.42.2.0249

빠빠윈아웅(Pa Pa Win Aung) ; 이동환(Lee, Donghwan) ; 박주영(Park, Jooyoung) ; 조민건(Cho, Mingeon) ; 박승희(Park, Seunghee)

Various studies are being actively conducted to show that the real-time visualization technology that combines BIM (Building Information Modeling) and AR (Augmented Reality) helps to increase construction management decision-making and processing efficiency. However, when large-capacity BIM data is projected into AR, there are various limitations such as data transmission and connection problems and the image cut-off issue. To improve the high efficiency of visualizing, a mesh optimization algorithm based on the k-nearest neighbors (KNN) classification framework to reconstruct BIM data is proposed in place of existing mesh optimization methods that are complicated and cannot adequately handle meshes with numerous boundaries of the 3D models. In the proposed algorithm, our target BIM model is optimized with the Unity C# code based on triangle centroid concepts and classified using the KNN. As a result, the algorithm can check the number of mesh vertices and triangles before and after optimization of the entire model and each structure. In addition, it is able to optimize the mesh vertices of the original model by approximately 56 % and the triangles by about 42 %. Moreover, compared to the original model, the optimized model shows no visual differences in the model elements and information, meaning that high-performance visualization can be expected when using AR devices.

시공표면평탄에 따른 3D 프린팅 적층형상 정량분석 Quantitative Analysis of 3D Printing Layered Shape according to the Flatness of Construction Surface

https://doi.org/10.12652/Ksce.2022.42.2.0257

박진수(Park, Jin Su) ; 김경택(Kim, Kyung Taek)

Additive manufacturing (AM, also known as 3D printing) applied to the construction industry is implemented and verified for various effects since advantages such as high design freedom, improving worker safety, and predictable construction period. However, due to the low maturity compared to the existing technology, studies are underway to solve new problems that occur in the overall of AM technology. In this paper, we confirm the effect of low construction surface flatness on the stacked features in the process of on-site AM construction. In particular, unstable AM features are determined through quantitative analysis by laser scanning, and a construction strategy is proposed for the surface flattening.

인공위성영상과 딥러닝을 이용한 건설공사현장 폭염취약지역 분석 Heatwave Vulnerability Analysis of Construction Sites Using Satellite Imagery Data and Deep Learning

https://doi.org/10.12652/Ksce.2022.42.2.0263

김슬기(Kim, Seulgi) ; 박승희(Park, Seunghee)

As a result of climate change, the heatwave and urban heat island phenomena have become more common, and the frequency of heatwaves is expected to increase by two to six times by the year 2050. In particular, the heat sensation index felt by workers at construction sites during a heatwave is very high, and the sensation index becomes even higher if the urban heat island phenomenon is considered. The construction site environment and the situations of construction workers vulnerable to heat are not improving, and it is now imperative to respond effectively to reduce such damage. In this study, satellite imagery, land surface temperatures (LST), and long short-term memory (LSTM) were applied to analyze areas above 33 °C, with the most vulnerable areas with increased synergistic damage from heat waves and the urban heat island phenomena then predicted. It is expected that the prediction results will ensure the safety of construction workers and will serve as the basis for a construction site early-warning system.

대학의 폐교지정이 주변 지역 공동주택 가격에 미치는 영향 -동부산대학교를 중심으로- Effect of University Closure on the Prices of Nearby Apartments -In the Case of Dong-Pusan College-

https://doi.org/10.12652/Ksce.2022.42.2.0273

김민규(Kim, Min Kyu) ; 김현수(Kim, Hyunsoo) ; 최열(Choi, Yeol)

In a recent decade, university closures have been a critical regional issue as a total of 17 universities have been closed while many more are facing closure in Korea. The local impact of university closures in the regions with declining populations has been far more detrimental and considered as one of the significant factors of the declining local economy, especially in the neighboring residential sectors. This study has taken an empirical approach to investigate the local impact of university closure on the housing market through a case of Dong-Pusan College in Busan, Korea. The study utilized Difference-in-Difference (DiD) to analyze the housing prices in proximity to the university and identified several factors associated with the local decline in the housing market in relation to university closure.

드론 활용 교량 안전점검을 위한 표준절차 정립 Establishment of a Standard Procedure for Safety Inspections of Bridges Using Drones

https://doi.org/10.12652/Ksce.2022.42.2.0281

이석배(Lee, Suk Bae) ; 이기홍(Lee, Kihong) ; 최현민(Choi, Hyun Min) ; 임치성(Lim, Chi Sung)

In Korea, the number of national facilities for which a safety inspection is mandatory is increasing, and a safer safety inspection method is needed. This study aimed to increase the efficiency of the bridge safety inspection by enabling rapid exterior inspection while securing the safety of inspectors by using drones to perform the safety inspections of bridges, which had mainly relied on visual inspections. For the research, the Youngjong Grand Bridge in Incheon was selected as a test bed and was divided into four parts: the warren truss, suspension bridge main cable, main tower, and pier. It was possible to establish a five-step standard procedure for drone safety inspections. The step-by-step contents of the standard procedure obtained as a result of this research are: Step 1, facility information collection and analysis, Step 2, analysis of vulnerable parts and drone flight planning, Step 3, drone photography and data processing, Step 4, condition evaluation by external inspection, Step 5, building of external inspection diagram and database. Therefore, if the safety inspections of civil engineering facilities including bridges are performed according to this standard procedure, it is expected that these inspection can be carried out more systematically and efficiently.

저가형 드론의 외부표정요소에 따른 위치결정 정확도 분석 Positional Accuracy Analysis According to the Exterior Orientation Parameters of Low-Cost Drone

https://doi.org/10.12652/Ksce.2022.42.2.0291

김두표(Kim, Doo Pyo) ; 이재원(Lee, Jae One)

Recently developed drones are inexpensive and very convenient to operate. As a result, the production and utilization of spatial information using drones are increasing. However, most drones acquire images with a low-cost global navigation satellite system (GNSS) and an inertial measurement unit (IMU). Accordingly, the accuracy of the initial location and rotation angle elements of the image is low. In addition, because these drones are small and light, they can be greatly affected by wind, making it difficult to maintain a certain overlap, which degrades the positioning accuracy. Therefore, in this study, images are taken at different times in order to analyze the positioning accuracy according to changes in certain exterior orientation parameters. To do this, image processing was performed with Pix4D Mapper and the accuracy of the results was analyzed. In order to analyze the variation of the accuracy according to the exterior orientation parameters in detail, the exterior orientation parameters of the first processing result were used as meta-data for the second processing. Subsequently, the amount of change in the exterior orientation parameters was analyzed by in a strip-by-strip manner. As a result, it was proved that the changes of the Omega and Phi values among the rotation elements were related to a decrease in the height accuracy, while changes in Kappa were linked to the horizontal accuracy.