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

KSCE JOURNAL OF CIVIL AND
ENVIRONMENTAL ENGINEERING RESEARCH

The Journal of Civil and Environmental Engineering Research (KSCE J. Civ. Environ. Eng. Res.) 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.

• Editor-in-chief: Il-Moon Chung

부유식 인프라의 동요와 인간의 편안함에 대한 사용성 평가방법 연구 Research on Serviceability Evaluation Methods for Human Comfort in Relation to the Motion of Floating Structures

https://doi.org/10.12652/Ksce.2024.44.5.0595

정연주(Jeong, Youn-Ju) ; 김정수(Kim, Jeongsoo) ; 김영택(Kim, Young-Taek)

This paper analyzes serviceability guidelines and index related to the motion of floating structures concerning human comfort. The guidelines for the motion of floating structures regarding human comfort must meet requirements such as including frequency range of floating structure and providing index for vertical direction, which is a major component of human discomfort. Therefore, ISO 2631-1:1997 was found to be applicable. The evaluation of serviceability of the floating structure showed that the frequency-weighted RMS acceleration, due to the characteristics of frequency weighting function, is significantly influenced by the period of the floating structure. Additionally, the frequency-weighted RMS acceleration presented lower values compared to the general RMS acceleration. These results are expected to contribute to the establishment of reasonable guidelines for human activities to the motion of floating structures.

Analysis of the Mechanical Properties of High-Tension Performance Biochar Concrete Reinforced with PVA Fibers Based on Biochar Cement Replacement Ratio

https://doi.org/10.12652/Ksce.2024.44.5.0603

(Kim, Sangwoo) ; (Lee, Jihyeong) ; (Hong, Yeji) ; (Kim, Jinsup)

This study evaluated the mechanical properties of high-tension performance biochar concrete, focusing on the effects of varying biochar cement replacement ratios (0 %, 1 %, 2 %, 3 %, 4 %, and 5 %). Mechanical properties, including compressive strength, tensile strength, and flexural strength, were tested. The results showed a general decrease in compressive strength with increasing biochar replacement, with significant reductions at 1 % to 3 % levels. PVA fiber reinforcement improved long-term compressive strength, particularly at higher biochar levels. Tensile and flexural strength also showed initial reductions with low biochar levels but improved at higher replacement levels. PVA fibers consistently enhanced tensile and flexural strength. SEM images confirmed the integration of biochar and PVA fibers into the cement matrix, enhancing microstructural density and crack resistance.

Evaluation of the Strength Characteristics of ECC Based on Cement Replacement Ratios with Biochar

https://doi.org/10.12652/Ksce.2024.44.5.0615

(Kim, Sangwoo) ; (Gwak, Jaewon) ; (Choi, Sooncheol) ; (Kim, Jinsup)

This study presents fundamental research data on the application and utility of biochar in Engineered Cementitious Composites (ECC) for carbon sequestration. The study experimentally measures and compares the compressive strength, tensile strength, and flexural strength of high-toughness biochar-incorporated ECC (BE) and biochar-incorporated mortar (BM) with varying levels of biochar replacement. This study aims to compare BM and BE. BM shows an increase in mechanical properties at a biochar content of 1 %. BE shows an increase in mechanical properties at a biochar content of 2 %. The reason for the increase is that biochar particles fill the voids between the binder materials, acting as a filler. This helps form a denser structure. These findings suggest that incorporating biochar into mortar and ECC can enhance their mechanical properties at optimal biochar contents.

위성영상을 이용한 저수지 수체면적 변화 분석 Analysis of Water Surface Area Change in Reservoir Using Satellite Images

https://doi.org/10.12652/Ksce.2024.44.5.0629

김주훈(Kim, Joo-Hun) ; 김동필(Kim, Dong-Phil)

The purpose of this study is to monitor changes in the water surface of reservoirs in verifiable areas in Korea using satellite images and to analyze the water surface area and water storage. The target area of this study is the Daecheong dam of the Geumgang(Riv.), which supplies water to some areas in the Chungcheong area. A study was conducted to detect water surface area by using the Sentinel-1(SAR-C) image and the optical image of Sentinel-2(MSI) among the various observation sensors of satellite images. The correlation between the reservoir's water storage volume, which is ground measurement data, and the extracted water surface area was analyzed. As a result of the analysis, the coefficient of determination(R2) between water surface area and daily storage using SAR images was analyzed to be 0.9242, and in the analysis using Sentinel-2's MSI optical image, it was analyzed to be correlated at 0.8995. In addition, it is analyzed that the water storage volume of the water surface area extracted from the image using the relationship between the water storage volume and the water surface area represents a hydrograph similar to the actual water storage volume. This study is a basic study for the use of satellite images in unmeasured/non-access areas such as North Korea, and plans to conduct a study to analyze annual changes and long-term trends in major dam reservoirs in North Korea by reflecting the results obtained through this study.

국내에서 ECOSTRESS 지표면 온도 및 증발산(PT-JPL) 자료의 검증 Validation of ECOSTRESS Based Land Surface Temperature and Evapotranspiration (PT-JPL) Data Across Korea

https://doi.org/10.12652/Ksce.2024.44.5.0637

박기진(Park, Ki Jin) ; 김기영(Kim, Ki Young) ; 김찬영(Kim, Chan Young) ; 박종민(Park, Jong Min)

The frequency of extreme weather events such as heavy and extreme rainfall has been increasing due to global climate change. Accordingly, it is essential to quantify hydrometeorological variables for efficient water resource management. Among the various hydro-meteorological variables, Land Surface Temperature (LST) and Evapotranspiration (ET) play key roles in understanding the interaction between the surface and the atmosphere. In Korea, LST and ET are mainly observed through ground-based stations, which also have limitation in obtaining data from ungauged watersheds, and thus, it hinders to estimate spatial behavior of LST and ET. Alternatively, remote sensing-based methods have been used to overcome the limitation of ground-based stations. In this study, we evaluated the applicability of the National Aeronautics and Space Administration's (NASA) ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) LST and ET data estimated across Korea (from July 1, 2018 to December 31, 2022). For validation, we utilized NASA's MODerate Resolution Imaging Spectroradiometer (MODIS) data and eddy covariance flux tower observations managed by agencies under the Ministry of Environment of South Korea. Overall, results indicated that ECOSTRESS-based LSTs showed similar temporal trends (R: 0.47~0.73) to MODIS and ground-based observations. The index of agreement also showed a good agreement of ECOSTRESS-based LST with reference datasets (ranging from 0.82 to 0.91), although it also revealed distinctive uncertainties depending on the season. The ECOSTRESS-based ET demonstrated the capability to capture the temporal trends observed in MODIS and ground-based ET data, but higher Mean Absolute Error and Root Mean Square Error were also exhibited. This is likely due to the low acquisition rate of the ECOSTRESS data and environmental factors such as cooling effect of evapotranspiration, overestimation during the morning. This study suggests conducting additional validation of ECOSTRESS-based LST and ET, particularly in topographical and hydrological aspects. Such validation efforts could enhance the practical application of ECOSTRESS for estimating basin-scale LST and ET in Korea.

물수지 분석을 통한 한강유역 발전용댐 유입량의 수원별 기여도 평가 Evaluation of the Contribution of Inflow by Water Sources into Hydropower Dam in the Han River basin through Water Balance Analysis

https://doi.org/10.12652/Ksce.2024.44.5.0649

최시중(Choi, Sijung) ; 강성규(Kang, Seongkyu) ; 노희성(Noh, Huiseong) ; 안정환(Ahn, Jeonghwan)

Recently, the need for water supply from hydropower dams has been increasing due to drought. In order to supply water through hydropower dam, the inflow into hydropower dam should be evaluated first. Some of the hydropower dams in the Han River basin are located downstream of multipurpose dam, so it is important to analyze its own inflow of the hydropower dam. The purpose of this study is to evaluate the contribution of inflow by water source to the hydropower dam located in the Han River basin. Water use-related data provided by various domestic institutions were investigated and collected, and a location-based water supply and demand network was constructed. Unlike the existing domestic water balance analysis method, the simulation was conducted in consideration of the amount of transmission loss. The applicability of the analysis method was confirmed through the results of the fitness evaluation (NSE 0.95~0.99 and correlation coefficient 0.98~0.99) comparing the simulated flow with the observed flow at the representative point. Based on the water intake method of the facility and the release method of the remaining multipurpose dam water, a water balance analysis was performed assuming four cases, and the contribution of inflow by water sources into each hydropower dam was evaluated and presented. The research results are expected to provide various information for evaluating the water supply capacity of hydropower dams in the future.

지표수-지하수 상호작용에서 질산성질소의 반응성 이동 연구 Reactive Transport of Nitrate in Surface-Groundwater Interactions

https://doi.org/10.12652/Ksce.2024.44.5.0663

장선우(Chang, Sun Woo) ; 우소영(Woo, Soyoung) ; 정일문(Chung, Il-Moon)

Nitrate contamination primarily results from agricultural activities and wastewater inputs, potentially leading to groundwater pollution. This study analyzed the reactive transport of nitrate in surface-groundwater interactions in the Gadeok-myeon, Cheongwon-gun, using integrated SWAT, MODFLOW, and RT3D models. The study used SWAT to simulate hydrological cycles, MODFLOW for groundwater flow analysis, and RT3D to model the reactive transport of nitrate. SWAT was used to estimate daily groundwater recharge and nitrate concentrations, which were then input into MODFLOW and RT3D models. The results showed that groundwater flow and reactive transport of nitrate were effectively simulated, providing insights into improving predictive models for groundwater and surface water interactions.

위성영상을 이용한 2024년 압록강 홍수량 및 침수범위 추정 Estimation of Flood Flow and Inundation Range of the Aprokgang(Riv.) in 2024 using Satellite Images

https://doi.org/10.12652/Ksce.2024.44.5.0673

김주훈(Kim, Joo-Hun) ; 최윤석(Choi, Yun-Seok) ; 김동필(Kim, Dong-Phil)

The purpose of this study was to estimate the flood flow and the range of inundation in the downstream area of the Aprokgang(Riv.) that occurred in 2024 using satellite images. The study area was the Aprokgang(Riv.) watershed, the longest river in North Korea. Satellite image Sentinel-1A(SAR-C) data was used for flood analysis before and after the flood. As a result of the analysis of the inundation range using satellite images, it was confirmed that there was a change in the water surface before and after the flood. However, the image after the flood was taken six days after the peak discharge of the flood, so there are limitations in extracting the accurate extent of the flooding. As a result of the analysis using satellite precipitation and ground observed rainfall, the rainfall exceeded 500-year rainfall amount, and the peak-flow was simulated as 85,102 m3/s. As a result of analyzing the inundation range by using the contour lines from AW3D30, it was determined that the inundation occurred around the 15 m contour line. In the future, it is need to conduct a study that can extract more scientifically the inundation range through the use of the inundation analysis model.

구조적 및 비구조적 대책을 결합한 섬진강유역 홍수조절능력 제고 방안 Strategy for Enhancing Flood Control Capacity of Seomjin River Basin Using Both Structural and Non-structuralMeasures

https://doi.org/10.12652/Ksce.2024.44.5.0683

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

Flood control capacity enhancement measures in watersheds can be broadly categorized into structural and non-structural approaches. In this study, we propose the improvement of the flood control capacity in the Seomjin River basin through non-structural measures by optimizing the operation of the Seomjin River Dam, specifically by introducing a flexible flood season restricted water level (FSRWL). The flexible operation of FSRWL involves setting lower restricted water levels at the beginning of the flood season to increase flood control capacity and gradually raising them as the season progresses to manage flood control more effectively. As a structural measure, we examined the installation of riverside storage areas, a representative technique of nature-based solutions (NbS). Using the 2020 flood event as a case study, we analyzed the flood level reduction effects of implementing structural and non-structural measures both separately and simultaneously to identify the most effective and economical approach. The results indicate that the optimal flood prevention strategy for the main stream of the Seomjin River during the 2020 flood event involves operating the Seomjin River Dam FSRWL at EL. 190 m during the mid-flood season as a non-structural measure and installing a riverside storage area downstream of Godalgyo Bridge in Daepyeong-ri, Gokseong-gun as a structural measure.

이중모드 함수특성곡선을 이용한 포항 산사태에 대한 불포화 비탈면의 침투 및 안정해석 Infiltration and Stability Analysis Using Double Modal Water Retention Curves for Unsaturated Slopes in Pohang

https://doi.org/10.12652/Ksce.2024.44.5.0695

오세붕(Oh, Seboong) ; 장준혁(Jang, Junhyuk) ; 윤석용(Yoon, Seokyong)

As a result of Typhoon Hinnamnoh, several slope failures occurred in the Pohang region, it is necessary to perform infiltration and slope stability analyses due to the actual rainfall. In the failed sites, samples were collected, and the hydro-mechanical properties of unsaturated soil were examined. Modeling the actual behavior using a single-mode function characteristic curve was found to be inadequate, leading to the adoption of a dual-mode function characteristic curve. The dual-mode function showed better agreement with the water retention test data. We calculated the unsaturated hydraulic conductivity for single and dual modes and performed rainfall-induced infiltration analysis. The variations in saturation and pore water pressure were calculated due to rainfall for three landslide-prone areas, Stability analysis based on effective stress of unsaturated soil was conducted, and safety factors were computed over time steps. The dual-mode model successfully reproduced landslides triggered by Typhoon Hinnamnoh, while the single-mode model exhibited a minimum safety factor of 1.2-1.3, making slope failure unpredictable. The dual-mode model accurately predicted instability in the slope by appropriately accounting for pore water pressure variations during Typhoon.

교각 무인시공 자동화 거푸집 시스템 구성을 위한 기초 연구 A Fundamental Study on the Automated Formwork System for Bridge Pier Unmanned Construction

https://doi.org/10.12652/Ksce.2024.44.5.0707

이재흔(Lee, Jae Heun) ; 윤혜진(Yoon, Hyejin) ; 김영진(Kim, Young Jin) ; 진원종(Chin, Won Jong) ; 이상윤(Lee, Sang Yoon)

Recently, the implementation of unmanned and automated technologies has been actively considered as a solution to reduce safety accidents in industrial sites. However, bridge construction sites are recognized as a more challenging area for research and development compared to other industries due to the complexity of the site, such as weather and terrain, and the fact that the work is not repetitive or standardized. In this paper, a formwork system for unmanned and automated construction of bridge piers, which are considered high-risk work environments due to tasks such as rebar assembly, concrete pouring, and formwork dismantling and assembly at high altitudes, was developed. To achieve this, the formwork was equipped with motorized spindles and an automated lifting system to replace the manual dismantling and assembly process. Additionally, manipulators were installed on the upper work platform to replace workers in tasks such as rebar assembly and concrete pouring. To verify the proposed technology, we aimed to demonstrate the feasibility of the automated formwork system for unmanned pier construction through an assembly test.

인공지능 자연어 처리 기법을 이용한 개선된 내역코드 탐색방법 Advanced CBS (Cost Breakdown Structure) Code Search Technology Applying NLP (Natural Language Processing) of Artificial Intelligence

https://doi.org/10.12652/Ksce.2024.44.5.0719

김한도(Kim, HanDo) ; 남정용(Nam, JeongYong)

For efficient construction management, linking BIM with schedule and cost is essential, but there are limits to the application of 5D BIM due to the difficulty in disassembling thousands of WBS and CBS. To solve this problem, a standardized WBS-CBS set is configured in advance, and when a new construction project occurs, the CBS in the BOQ is automatically linked to the WBS when a text most similar to it is found among the standard CBS (Public Procurement Service standard construction code) of the already linked set. A method was used to compare the text similarity of CBS more efficiently using artificial intelligence natural language processing techniques. Firstly, we created a civil term dictionary (CTD) that organized the words used in civil projects and assigned numerical values, tokenized the text of all CBS into words defined in the dictionary, converted them into TF-IDF vectors, and determined them by cosine similarity. Additionally, the search success rate increased to nearly 70 % by considering CBS' hierarchical structure and changing keywords. The threshold value for judging similarity was 0.62 (1: perfect match, 0: no match).

Optimal UAM Route Planning with Digital Twin : Casestudy of Gangneung City

https://doi.org/10.12652/Ksce.2024.44.5.0733

(Ahn, Seunghyo) ; (Kim, Changyoon) ; (Kim, Gihong)

Urban Air Mobility is gaining attention as a solution to traffic congestion and air pollution in large cities, but Gangneung, the case area of this study, is a medium-sized city focusing on tourism and connectivity with other public transport rather than congested traffic. Introducing UAM here focuses on integrating aircraft that carry people, vertiports for vertical take-off and landing, and corridors through which UAM can fly. While research on aircraft and vertiports is actively conducted, studies on corridors are still lacking. Thus, this study selected a route in Gangneung, a medium-sized city in Gangwon Special Self-Governing Province, that allows UAM flights with minimal risk. For this, a safety distance specific to building heights was determined, and the damage radius in case of aircraft crashes was calculated to select the route with the least possible damage during crash or collision incidents. For analysis, aerial photos and digital maps of Gangneung City, along with building information data, were used to create high-resolution orthophotos and digital elevation models. Based on the created data, GIS-based spatial analysis and three-dimensional visualization were conducted, and a suitable UAM route for Gangneung City was determined.