Journal of the Korean Society of Agricultural Engineers publishes peer-reviewed research articles in engineering to help better understand and thus solve problems in agriculture, environment, food and other biological systems. Journal of the Korean Society of Agricultural Engineers presents cutting-edge research on a broad range of topics including irrigation and drainage, soil and water conservation, rural planning and development, agricultural structure & environmental control, rural environment & natural resources management, and more.
Agricultural water shortages are intensifying with the increasing frequency of droughts under climate change. Despite ongoing infrastructure development, significant gaps remain in understanding the spatial and structural characteristics of agricultural water facilities and irrigated areas, limiting the efficiency of water management. This study develops a typology of irrigated beneficiary areas to support systematic agricultural water management. We analyzed 113 irrigation districts with main reservoirs exceeding 3 million m³ of effective storage. Spatial distribution and facility characteristics including reservoirs, pumping stations, and intake weirs were evaluated, and irrigated areas were classified using two approaches: (1) water supply systems and (2) demand-supply characteristics. The first approach identified four supply-system types, with 1 4.5% and 8 .6% covering the largest areas, particularly in the Gyeongsangbuk-do and Chungcheongnam-do regions. The second approach classified areas into four categories based on dominant water source, crop type, supply structure, and reservoir unit storage capacity. Most reservoirs were characterized by reliance on large-scale main water sources (77%) and main canal-type supply systems (90%). The results reveal distinct spatial patterns and supply characteristics across regions, highlighting the heterogeneity of irrigation systems in Korea. These findings provide essential data for systematic water resources management and the development of resilient and stable agricultural water supply systems.
Analysis of Design-Frequency Shifts in Agricultural Fill Dams Under Weighted Design Flood Discharges
소의건 So Euigeon , 주동혁 Joo Donghyuk , 나라 Na Ra , 김하영 Kim Ha-young , 유승환 Yoo Seung-hwan , 송인홍 Song Inhong , 이혁진 Lee Hyeokjin
Climate change has intensified the frequency and magnitude of extreme rainfall events, underscoring the need to revise the design flood criteria for agricultural fill dams to ensure adequate hydrological safety. Although the current KDS 67 10 20 standard applies a 200-year return period with a 1.20 weighting factor (20% increase of the design flood discharge), recent hydrological responses suggest that this criterion may not fully reflect actual hazard levels. In this study, design flood discharges were estimated using frequency-based rainfall and probable maximum precipitation (PMP), implementing the SCS-CN method, Clark unit hydrograph, and simple lag routing within the K-HAS module. Using these estimates, the applicability of the current standard was assessed, and the resulting changes in return period under different weighting factors were quantified. Applying a weighting factor of 1.20 increased the effective return period from 200 years to approximately 650-850 years, while the same factor applied to the 500-year frequency increased it to 2,000-2,400 years, revealing a strong nonlinear amplification effect. The magnitude of this amplification varied substantially with watershed characteristics: smaller catchments and shorter times of concentration exhibited higher sensitivity, whereas total storage capacity had minimal influence. These findings indicate that a uniform weighting factor does not adequately account for the hydrologic and geometric diversity of agricultural reservoirs. The results highlight the need for flexible, site-specific design-frequency criteria that incorporate key watershed characteristics to better ensure hydrological stability under future climate conditions.
Field Evaluation of Compaction Characteristics and Resilient Modulus of Subgrade Using In-situ Modulus Detector
김홍주 Kim Hong Ju , 손동건 Son Dong Geon , 변용훈 Byun Yong-hoon , 이종섭 Lee Jong-sub , 김동주 Kim Dong-ju
The resilient modulus of a subgrade is a critical parameter in pavement design, particularly under repetitive wheel loading induced by vehicle movement. In this study, an in-situ modulus detector (IMD) and a dynamic cone penetrometer (DCP) are employed to perform field tests on compacted subgrades. The subgrade is prepared at three levels of relative compaction by applying 2, 4, and 6 passes of a roller compactor. The IMD is used to estimate the in-situ resilient modulus, while the DCP is utilized to compare the penetration indices with the IMD results. Experimental results show that the in-situ resilient modulus obtained from the IMD increases with the penetration depth. In addition, the penetration depth per blow from both the IMD and DCP tests decreased with increasing relative compaction and penetration depth. A robust linear correlation is observed between the resilient modulus and relative compaction, showing a high coefficient of determination. These findings suggest that the IMD can serve as an effective tool for evaluating the in-situ resilient modulus of subgrade during site investigations, considering influencing factors such as relative compaction and penetration depth.
Addressing Class Imbalance in Semantic Segmentation of Rural Watershed Point Clouds Using Loss Re-Weighting
김민재 Kim Minjae , 이종혁 Lee Jonghyuk , 서병훈 Seo Byunghun , 김동수 Kim Dongsu , 서예진 Seo Yejin , 김동우 Kim Dongwoo , 조예림 Jo Yerim , 심지민 Shim Jimin , 최원 Choi Won
This study addresses the challenge of severe class imbalance in semantic segmentation of rural watershed point clouds. Due to the dominance of a few classes and the scarcity of minority classes, segmentation performance can degrade significantly. To mitigate this issue, we investigated loss function strategies based on class weighting and focal loss using the Point Transformer V3 architecture. The dataset, collected via LiDAR from Sanyang Reservoir watershed in Icheon, South Korea, was labeled into ten semantic classes and preprocessed using sub-sampling. Four loss function configurations were evaluated: baseline cross entropy, class-weighted cross entropy loss, focal loss, and a combination of focal loss with class weighting. Experimental r esults s how that c ombining class weighting and focal loss a chieves the best p erformance (mIoU = 0 .3222; O A = 0.7464), outperforming the baseline, with clear IoU improvements in several minority classes such as Road, Water, and House, while Bridge and Reservoir remain challenging due to extreme data scarcity. Hyperparameter tuning further indicates optimal focal loss parameters of γ = 3.0 without class weighting (mIoU = 0.3311) and γ = 2.0 with class weighting (mIoU = 0.3222). These findings highlight the effectiveness and limitations of tailored loss re-weighting for addressing class imbalance in rural watershed point cloud segmentation.
A Study on the Improvement of Design Flood Criteria for Agricultural Reservoirs through a Comparative Analysis of Domestic and International Standards
In recent years, the increasing uncertainty of rainfall patterns due to climate change and the frequent occurrence of localized heavy rain have raised significant concerns about the flood safety of agricultural reservoirs in Korea. Most of these reservoirs were constructed more than 50 years ago and are now facing structural limitations in responding to extreme hydrological events. Despite this, the design flood for agricultural reservoirs in Korea is still primarily based on fixed frequency standards, typically the 1/200 year flood, as outlined in the “Design Criteria for Agricultural Infrastructure - Fill Dam Section” In some high risk cases, the application of the PMF (Probable Maximum Flood) is being attempted, but the criteria for such applications remain qualitatively defined and lack a systematic risk-informed approach. In contrast, countries such as the United States, Australia, and New Zealand have adopted risk based frameworks that consider downstream consequences, potential loss of life, and societal tolerable risk levels when selecting inflow design floods. These international standards are characterized by flexible and quantitative criteria that respond to diverse hazard levels. This study aims to analyze the limitations fo Korea’s current design flood standards for agricultural reservoirs and compare them with international practices. Through this comparative analysis, the study proposes directions for improving Korea’s design flood criteria by incorporating risk-informed methodologies. The results are expected to contribute to the development of safer and more scientifically grounded flood design standards under future climate conditions.
Uplift Resistance Characteristics Analysis of a Disaster-Resistant Greenhouse Continuous Pipe Foundation Using 3D Numerical Analysis
조상범 Jo Sangbeom , 손영환 Son Younghwan , 전지훈 Jeon Jihun , 김태진 Kim Taejin , 이원영 Lee Wonyoung , 봉태호 Bong Taeho , 유석철 Yu Seokcheol
Given the lightweight nature of single-span greenhouses, foundation design to withstand uplift loads from strong winds or typhoons is imperative. However, current disaster-resistant design standards lack methods to evaluate the stability of continuous pipe foundations used in single-span greenhouses. Therefore, this study aimed to evaluate the ultimate uplift resistance of continuous pipe foundations and elucidate their uplift behavior using 3D finite element analysis. To achieve this, a finite element analysis model was constructed and validated based on model test data from prior research. Based on the analysis results, the uplift resistance mechanism was confirmed through analysis of nearby ground displacement, effective stress, and plastic failure zones when uplift force was applied. Furthermore, a parameter analysis was performed using the unit weight, internal friction angle, and cohesion of soil as variables, based on representative domestic field soil types. The developed model showed a high correlation with an R² = 0.862. Analysis of the uplift resistance behavior revealed that the uplift resistance of the continuous pipe foundation is primarily influenced by the cohesion of the soil. Parameter analysis similarly confirmed that the increase in cohesion had the greatest influence on the increase in ultimate uplift resistance. The model developed in this study is expected to be utilized for estimating uplift resistance during the design of disaster-resistant greenhouses.
Prediction of Reservoir Embankment-Breach Outflow Hydrographs Using the DTW-KNN Algorithm
심지민 Shim Jimin , 이종혁 Lee Jonghyuk , 서병훈 Seo Byunghun , 김동수 Kim Dongsu , 김동우 Kim Dongwoo , 조예림 Jo Yerim , 최원 Choi Won
As climate change intensifies extreme rainfall events, the risk of dam breaches in aging agricultural reservoirs is increasing. In Korea, Emergency Action Plan (EAP) is typically initiated using one-dimensional models such as DAMBRK, followed by high-resolution simulations for detailed analysis. This study proposes a method for predicting reservoir outflow hydrographs by integrating a Dynamic Time Warping-K-Nearest Neighbors (DTW-KNN) algorithm with reservoir outflow hydrographs generated by DAMBRK and FLOW-3D. After applying DTW-KNN, peak flow errors were generally reduced to within approximately 10%, and substantial improvements in peak timing accuracy were achieved, while the average Nash-Sutcliffe efficiency (NSE) increased from 0.34 to 0.93. Acceptable performance was also maintained at an extrapolated elevation of EL. 12.43 m, indicating that the trained model preserves reasonable generalization capability beyond the training range. These results demonstrate that the proposed DTW-KNN approach provides a practical, data-driven linkage between DAMBRK and FLOW-3D hydrographs, offering a reliable framework for rapid dam breach assessments under limited data conditions.
