기후변화로 기상 조건의 변동성이 증가함에 따라, 하수처리장 유입 부하의 변동성 또한 전반적으로 확대되고 있다. 특히 합류식 하수관거 시스템을 사용하는 도시 지역에서는 강수 및 기온 변화에 따라 유입 부하 변동이 더욱 두드러지게 나타난다. 이에 따라 기존에 활용되는 계절 기반 분류 방법은 예외적인 유입 부하 패턴을 충분히 포착하는 데 한계를 가진다. 본 연구는 기상 자료와 유입 수질 자료를 통합하여 군집화 기반으로 하수처리장 유입 부하 패턴을 분류하는 것을 목적으로 한다. 유입 부하 변동 특성을 효과적으로 나타낼 수 있는 최적의 군집화 조건을 도출하기 위해 다양한 실험 조건에서 여러 군집화 알고리즘의 성능을 비교ㆍ분석하였다. 9년간의 일 단위 기상 자료와 유입 수질 자료를 활용하여 다양한 입력 변수 및 파라미터 조건에서 4개 군집화 알고리즘의 성능을 평가하였다. 분석 결과, 학습에 활용된 특징 변수의 수가 증가할수록 군집 간 상대적 거리인 분리도는 전반적으로 감소하여 분류 성능이 저하되는 경향을 보였다. 반면, 기상 변수를 포함하면 군집 성능이 일관되게 향상되었다. 결과적으로, 강수량의 비대칭적 분포 특성으로 인해 밀도 기반 및 분포 기반 알고리즘은 군집 경계 형성을 저해하여 성능이 저하되었고, 거리 기반 알고리즘은 강수 변수를 포함할 때 분리도가 증가하며 실루엣 지수(Silhouette Index, SI) 높게 나타났다. 이러한 결과는 적절히 선택된 군집화 조건이 기존의 계절 분류를 넘어 예외적인 유입 부하 패턴을 효과적으로 구분할 수 있음을 시사한다. 본 연구는 기상 자료와 수질 자료를 통합한 유입 부하 군집화가 기존 접근법보다 정교한 분류를 가능하게 하며, 선제적 운영과 공정 수준 예측 성능 향상에 기여할 수 있는 정량적 근거를 제시한다.

Quail meat is increasingly consumed worldwide, yet information on optimal antimicrobial interventions during processing remains limited. This study evaluated the effects of chlorine concentration (0-40 ppm) in processing water and an additional 2°C overnight exposure at 40 ppm on the microbial load of quail carcasses. Total viable counts (TVC) were enumerated using standardized dilution and plating methods, and results were expressed as log10 CFU/mL. Across 0-40 ppm, no statistically significant differences were observed by one-way ANOVA (p > 0.05), although a numerical decrease was noted at 40 ppm. In contrast, carcasses treated with 40 ppm chlorine and held at 2°C overnight showed markedly lower counts compared with both the 0 ppm control and the 40 ppm immediate-processing group. These findings suggest that the antimicrobial impact of chlorine is strongly influenced by contact time and temperature, and that low-temperature holding may enhance the practical efficacy of chlorine sanitation during quail processing.

Nutrient loads in inland rivers can propagate downstream to estuaries and near-coastal waters, where water-quality conditions may affect fisheries and aquaculture. This study examines the effect of a nutrient load control program on total phosphorus in South Korea. Using a difference-in-differences approach with fixed effect models, the study constructs monitoring stations in the Nakdong, Geum, and Yeongsan rivers as the treatment group and monitoring stations in the Han River as the control group. The study leverages total phosphorus (TP) control as the policy intervention. Using monitor-by-time data from the national Total Maximum Daily Load network from 2007 to 2012, the study found that TP levels decreased by approximately 3.6% after the policy intervention. The study further examines flexible and honest DIDs and finds limited but suggestive evidence of this improvement. The findings provide suggestive evidence of load-based regulation in reducing TP and provide policy-relevant evidence on upstream nutrient control that may inform broader downstream water-quality management in connected river-estuary systems.

Engineered Material Arresting System (EMAS) is a critical safety installation at the end of a runway toarrest an overrunning aircraft. Key parameters such as vertical load and wheel-EMAS interaction mode significantly influence arresting performance. Since aircraft overrun involves combinations of these parameters, understanding their coupled effect is essential for predicting arresting behavior. This study investigates the combined effects of loads and wheel-EMAS interaction modes, namely rolling, sliding, and combined rolling-sliding, on wheel velocity. A finite element model simulating the wheel’s translation across the EMAS bed was developed using LS-DYNA, a commercial software. The wheel was modeled as a rigid aluminum body, whereas the EMAS bed was represented as a glass foam. The simulation model was defined using comprehensive inputs, including geometry, material models, boundary conditions, and contact parameters, with the initial wheel entry velocity kept constant across all simulations. For each load, the various wheel-EMAS interaction modes were examined. Results indicate that both higher loads and sliding-dominated interaction significantly enhance velocity decay.Among the investigated cases, the greatest velocity decay occurs for pure sliding motion under the highest applied load, where the velocity is reduced by 99.43% of the initial velocity. In contrast, rolling motion under the reference load exhibits the least decay, with only a 29.27% of the initial velocity, while all other cases fall between these two extremes. This trend indicates that sliding-dominated motion dissipates a larger portion of kinetic energy, resultingin greater velocity decay. On the other hand, rolling motion limits energy loss, and the combined rolling-sliding mode exhibits transitional behavior between these two modes. This velocity decay is amplified under higher loads, where the increased normal force enhances energy dissipation. Hence, the combined effect of interaction mode and load is critical for the accurate evaluation and design of EMAS systems.

Brushless excitation systems are widely used in marine synchronous generators due to their high reliability and reduced maintenance requirements. In these systems, the rotating rectifier converts the three-phase AC output of the exciter into DC current for the main field winding. However, faults in the rotating rectifier, particularly a single diode open-circuit fault, can degrade excitation performance without immediately triggering protective devices, making early detection difficult. This paper experimentally investigates the effects of a single rotating rectifier diode open-circuit fault on the excitation system and voltage formation of a brushless synchronous generator under no-load operating conditions. The no-load condition minimizes the influence of armature reaction and load current, allowing fault-induced excitation behavior to be clearly isolated. A brushless excitation system was implemented using three synchronous machines of identical rating, and a single diode open-circuit fault was intentionally introduced in the rotating rectifier. Excitation-related electrical quantities related to the excitation system, including DC excitation current and voltage, exciter armature currents, and generator terminal voltage, were measured and compared before and after the fault. Experimental results demonstrate that the single diode open-circuit fault causes reduction in the average excitation current and introduces low-frequency ripple components in the excitation current waveform while the terminal voltage reduction remains limited under no-load conditions. These results indicate that excitation-related electrical signals can serve as effective indicators for the detection of rotating rectifier diode faults in brushless synchronous generators.

The design code specifies the seismic loads for non-structural components (NSC) regardless of their planar locations. Thus, structures with irregular geometry that exhibit torsional behavior may experience greater seismic loads than those specified by the design code. This study assessed the adequacy of the code-specified equivalent static loads using nonlinear dynamic analysis results from structures intentionally designed to be eccentric, and finally proposed a formula that accounts for torsional amplification effects in buildings. The analysis results indicated that the code-specified equivalent static loads were conservative in the lower stories or near the center of mass. On the other hand, the dynamic analysis-based loads exceeded the equivalent static load in the outer perimeter of the mid- and upper stories. Accordingly, a torsional amplification factor equation was proposed, which is a function of the building's eccentricity ratio and the relative distance from the center of mass. The proposed equation applies to the NSC installed in the stories above the midpoint of the total building height. For a building with zero eccentricity or NSC at the center of mass, the function was set to unity.

In this study, vision-based monitoring combined with accelerometer-based measurements was conducted in a large-scale concert hall under crowd loads. First, the dynamic characteristics of the structure were identified from ambient vibrations measured in the absence of crowds. Then, an FE model was established that exhibits dynamic attributes similar to those of the structure. Subsequently, camera footage of crowd motion at a K-pop concert was used to estimate crowd loads, which were then applied to the FE model to assess responses. The acceleration response obtained from the analysis was compared with the measured acceleration and the acceptance criteria of design guidelines, such as AISC DG11. The acceleration predicted by the vision-based estimation was approximately 67% of the estimated value based on peak values and 62% of the measured value based on root mean square (RMS) values. Overall, the vision-based estimation showed a peak response around 10 Hz, while the measurement showed a gradual increase in the frequency range above 10 Hz. This is likely because low-frequency components were underrepresented in the vision-based estimation, resulting in relatively underestimated amplitudes and lower responses in the high-frequency range.

This study proposes a wind power generation system designed to enhance energy self-sufficiency in high-rise buildings by integrating internal and external airflow sources. In such structures, external wind generated by building height and form and internal airflow induced by the stack effect coexist but move in different directions. This study introduces a system that collects and integrates five types of wind into a single, unified flow. Wind speed data were calculated using meteorological datasets and stack effect equations, and a prototype was designed using Autodesk Fusion360. CFD simulations were conducted to determine the combined wind speed at the outlet. Based on the simulated results, expected power output was calculated using wind power equations. The building energy model was created in DesignBuilder and simulated in EnergyPlus using default office building settings. The predicted annual wind energy generation is approximately 962,022.85kWh, covering 11.73% of the building’s total annual electricity use. The study demonstrates the potential for wind-integrated high-rise designs to contribute to energy autonomy.

As the web game market grows, ensuring service stability through load testing has become increasingly important. Web games comprise a variety of functions with distinct internal logic, ranging from simple data retrieval to complex transaction processing. Therefore, a comparative performance analysis of load-testing tools that accounts for these functional characteristics is crucial for achieving reliable and efficient service operation. This paper evaluates the performance of four widely used load-testing tools—JMeter, k6, Gatling, and Locust—under representative web-game workloads. To emulate realistic database read and write patterns, we implement the core server logic of the web game Pokerogue in a cloud environment rather than simply issuing HTTP requests. We classified workload patterns into write-intensive, read-intensive, and mixed types using distributed tracing, and measured request-generation capability and system resource consumption across five key game functions. Our experiments show that each tool demonstrates distinct strengths depending on the characteristics of individual web-game functions. Specifically, k6 demonstrated high request-generation performance in write-intensive scenarios, while JMeter showed strong performance in read-oriented tasks; Gatling exhibited efficient memory usage in mixed workloads, whereas Locust proved suitable for resource-constrained environments. These results indicate that the selection of a load-testing tool should be informed not only by its request-generation performance but also by the workload characteristics of the target game function. By systematically analyzing function-specific workload patterns together with the performance and resource-usage behavior of each tool, this study aims to provide empirical evidence that can be usefully applied in practical load-testing workflows for web-game services.

This study proposes empirical formulas for predicting the nonlinear behavior of GIR beam-to-column connections in timber structures to evaluate their structural performance. A database comprising 59 experimental results of GIR connections was collected, and the normality of data distribution was verified. Statistical analysis were conducted to investigate the correlations between input and output parameters. Based on input parameters with high correlation, derived variables were formulated and utilized in a multiple regression analysis to develop empirical formulas for moment capacity and rotation. The R-squared values of the proposed formulas exceeded 0.9, and the predicted initial stiffness and strength closely matched those of experimental results not used in the regression analysis. So the suggested empirical formulas exhibit excellent predictive performance for the nonlinear behavior of GIR beam-to-column connections in timber structures.

본 연구에서는 전산유체역학(Computational fluid dynamics)을 이용하여 해상풍력지원선(Service Operation Vessel, SOV)의 갑판교와 거주구의 공역학적 상호작용을 평가하였다. 풍속, 풍향 및 두 구조물 간의 상호 거리를 변경하며 공역학적 계수인 평균 항력 계수 및 양 력 변동 계수와 함께 양력 변동 주기를 확인하였으며, 주위 유동을 분석하였다. 갑판교의 경우 풍속이 증가함에 따른 하중 계수의 변화가 미비하나, 거주구의 경우 일정 풍속 이상에서 평균 항력 계수 및 양력 변동 폭이 증가한다. 또한 상호 거리의 증가에 따른 두 구조물의 평균 항력 계수와 양력 변동 계수의 증가를 확인하였다. 유동장 변화를 통해, 상호 거리가 증가함에 따라 갑판교 상부에 발생하는 양의 압력 분포가 점차 커지는 경향을 확인하였으며, 이로 인해 거주구 상류의 음의 압력 분포는 점차 커짐을 확인하였다. 본 연구 결과를 통 해 전반적으로 해상풍력지원선의 갑판교와 거주구의 하중에 지배적인 인자는 상호 거리, 풍속과 그에 따른 갑판에 의한 후류 영역임을 확인할 수 있었으며, 상호 거리를 고려한 해상풍력지원선의 설계에 도움이 될 수 있을 것으로 기대한다.

Unlike civilian logistics systems, which primarily focus on efficiency, military logistics emphasizes operational stability. To achieve this, the establishment of a dedicated support system and balanced inventory management are essential. However, the current Army logistics system requires improvements in the support rate through the dedicated support framework. Although long-term improvement is possible through procurement process optimization, short-term enhancement is difficult due to the military’s annual procurement cycle. As a short-term improvement, inventory adjustment between supply points could be effective, but this strategy has not been fully utilized. This is due to the lack of recognition that, while inventory adjustment may increase costs in the short term, it contributes to improved logistics efficiency and stability in the long term. This study proposes a cost-minimizing plan that includes inventory adjustment between supply points in military logistics and aims to verify the effectiveness of inventory adjustment. To this end, a mathematical model for optimizing transportation planning was developed. Additionally, the effectiveness of inventory adjustment was demonstrated through a case study reflecting actual Army logistics conditions. The results of the study confirmed the positive effects of inventory adjustment. Inventory adjustment is expected to enhance the dedicated support rate and promote procurement process optimization, contributing to the advancement of the Army logistics system.

본 연구는 쇄빙연구선 아라온호의 국부 빙하중을 정확하게 추정하기 위해, 국제선급협회(IACS) Polar Class에 따른 실제 설계 하중(Design Ice Load)과 빙하중 면적(Load Patch)을 활용하여 영향계수행렬을 산정하였다. 기존 연구에서는 단위하중 또는 집중하중 형태 로 구조해석을 수행하여 영향계수행렬을 구했으나, 본 연구에서는 아라온호의 설계하중을 기반으로 실제 빙 충돌 상황과 유사한 면적 에 하중을 부여함으로써 보다 현실적인 해석 결과를 얻고자 하였다. 해석에는 선급 규칙으로부터 도출한 직사각형 형태의 빙하중 패치 와 평균 압력을 적용하였으며, 아라온호 선수부에 총 21개의 스트레인 게이지 위치에 대해 각각 해석을 진행하였다. 이후, 각 하중 조건 에서의 변형량을 토대로 21×21 행렬 형태의 영향계수행렬을 도출하였다. 본 연구의 결과로 도출된 영향계수행렬을 사용하면 실제 계측 된 스트레인 값을 기반으로 빙하중을 보다 정밀하게 추정할 수 있을 것으로 기대된다. 이는 기존 방식 대비 얼음 충돌 시 발생하는 면 적 효과를 고려했다는 점에서 의미가 있으며, 향후 쇄빙선 설계 및 운항 과정에서의 빙하중 평가 정확도를 높이는 데 기여할 것으로 판단된다.

본 연구에서는 구조물의 응답 데이터를 기반으로 고유진동수, 감쇠비 등 동특성과 풍하중 모델의 파라미터를 동시에 추정할 수 있는 스펙트럼 백색화 기반 식별 기법을 제안하고, 이를 실제 40층 고층 구조물에 적용하여 실용성과 정확도를 평가하였다. 기존 연 구에서는 본 기법을 수치 시뮬레이션 및 풍동 실험에 적용하여 그 타당성을 입증한 바 있으나, 실계측 응답 데이터를 활용한 실구조물 적용에 대해서는 검증이 이루어지지 않았다. 본 연구는 이를 확장하여, 장기간 계측된 고층 건축물의 진동 응답을 분석하고, 각 주요 모드에 대해 백색화 처리를 수행함으로써 구조물 전달함수 및 풍하중 전달함수의 파라미터를 최적화 기반으로 동시 추정하였다. 특히 백색 잡음의 누적 파워 스펙트럼 길이를 목적함수로 설정함으로써, 기존 커브 피팅 기반 기법 대비 감쇠비 추정의 정확도와 안정성을 향상시켰다. 분석 결과는 전통적인 모달 식별 기법(예: SSI)과의 비교를 통해 제안 기법의 유효성을 입증하였으며, 풍하중 모델 파라미 터까지 포함하는 통합적 구조 해석 프레임워크로서의 가능성을 제시하였다. 본 연구는 향후 구조물의 풍응답 예측, 하중 생성 모델 구 축, 구조 건전도모니터링(SHM) 및 디지털 트윈 기반 해석 등 다양한 실무 응용에 기여할 수 있을 것으로 기대된다.

When manufacturing a square plate with a pinhole, the following conclusions were obtained as a result of analyzing the effect of changes in the size of the grid filling the inside of the plate and the presence or absence of a pinhole on the stress concentration factors. 1. It can be seen that in the case where there is a pinhole, the overall stress concentration factors is twice as high as in the case where there is no pinhole. In addition, in the case where there is no pinhole, it can be seen that the stress concentration factors fluctuates at a certain standard depending on the position of the pinhole and the internal grid, and in the case where there is a pinhole, it decreases at a certain point and then increases again. 2. In the case where there is no pinhole, when the L/H ratio increases from 0.1 to 0.3, the Kt value increases from 1.8 to 2.7, an increase rate of approximately 50%. Similarly, in the case of a pinhole, when the L/H ratio increases from 0.1 to 0.4, the Kt value increases from 2.0 to 3.0, an increase rate of about 50%.

식량 운송 과정에서 발생하는 온실가스는 전 세계 온실가스 배출량의 15분의 1 수준이다. 식량이 이동하는 거리를 줄여 푸드 마일리지를 절감하는 것은 도시의 지속 가능성과 회복력 을 향상시킬 수 있다. 옥상 온실은 푸드 마일리지를 감소시키 고 에너지를 절감하는 도시농업의 한 형태로 주목받고 있다. 온실과 건물 모두 실내 환경을 유지하기 위해 냉난방이 요구 된다. 건물과 온실의 통합 시스템 운영은 설비 공유로 인한 비 용 절감, 건물과 온실 간 에너지 이동으로 인한 에너지 활용이 가능하다. 건물 에너지 시뮬레이션을 이용해 다양한 통합 시 스템 에너지 성능 평가 연구가 수행되었지만, 실제 통합 시스 템에 대한 검증과 설계변수 분석은 미흡한 실정이다. 본 연구 에서는 건물 에너지 시뮬레이션을 통해 옥상온실의 설치 유 무, 옥상의 단열 성능 및 설치 면적에 따른 에너지 절감을 평가 하고자 하였다. 현장 실험은 서울특별시 성동구 성수동의 옥 상온실에서 수행되었다. 측정한 실내 온도를 통해 건물 에너 지 시뮬레이션의 모델을 검증하였고 R2 = 0.91의 결과를 보였 다. 이후 설계변수가 에너지 부하에 미치는 영향을 정량적으로 분석하였다. 통합 시스템을 운영하는 경우, 독립적으로 운 영하는 경우보다 에너지 부하량이 감소하는 경향을 보였다. 통합 시스템 설치 시 에너지 부하 절감 효과가 있으며, 효율적 인 에너지 이용을 하는 도시농업이 될 수 있다고 사료된다. 건 물 옥상의 열관류율을 0.251W/m2·K에서 1.535W/m2·K로 증가시켜 단열 성능을 약화시킨 경우, 옥상온실과 건물 최상 층의 에너지 부하는 감소하는 경향을 보였다. 통합 시스템 설 치 시 경계면의 열 교환이 증가하도록 설계하는 것이 에너지 부하 절감에 유리하다고 판단된다. 옥상온실 면적을 2.53배 증가시켰을 때 단위면적당 에너지 부하는 감소하는 경향을 보 였다. 온실 면적 증가로 인해 에너지 부하량은 증가하지만, 건 물과 온실의 열 교환이 증가하여 통합 시스템의 에너지 부하 절감이 가능하다고 판단된다. 본 연구의 결과는 통합 시스템 을 통한 에너지 부하 절감을 위한 자료로 활용될 수 있을 것으 로 판단된다. 향후 연구에서는 기후 변화에 따른 에너지, 식량 문제의 해결 대책으로 옥상온실을 활용하기 위해서 추가적인 방안이 필요할 것으로 판단된다.