In this study, we aim to classify personal mobility (PM)-related traffic crash data into four categories: PM-to-vehicle, PM-to-pedestrian, PM-single, and vehicle-to-PM crashes, and analyze the factors influencing the severity of each crash type. To overcome the limitations of existing studies in explaining the impact of independent variables on ordinal dependent variables, a random forest model was combined with the Shapley additive explanation technique. This approach visualizes the influence of independent variables on a dependent variable, providing clearer insights and enhancing interpretability. The analysis of PM traffic accidents, categorized into at-fault, single-vehicle, and victim accidents, revealed distinct key factors for each type. The main contributors to the severity of crashes caused by PM are traffic violations by teenagers and collisions with elderly pedestrians. Single-vehicle accidents were predominantly caused by overturn incidents, with inadequate driving skills among PM users aged 40 years and older, and significantly increasing severity. Victim accidents primarily occur at intersections, where the behavior of the at-fault driver and age of the PM user are critical factors influencing the severity. We identified various factors influencing the severity of PM crashes by type, highlighting the need for tailored policy measures. Proposed policies include physically separating bicycle–pedestrian shared spaces and strictly regulating illegal PM sidewalk riding, introducing PM licenses for teenagers to ensure compliance with traffic rules, and implementing regular safety education programs for all age groups. Although this study applied a new analytical technique, it relied on limited crash data, thus limiting the results to estimates.

This study proposes a mathematical model to optimize the fighter aircraft-weapon combinations for the ROKAF(Republic Of Korea Air Force). With the recent emergence of the population declining issue in Republic of Korea, there is an urgent need for efficient weapon system operations in light of decreasing military personnel. In order to solve these issues, we consider to reduce the workload of pilots and maintenance personnel by operating an optimal number of weapons instead of deploying all possible armaments for each aircraft type. To achieve this, various factors for optimizing the fighter-weapon combinations were identified and quantified. A model was then constructed using goal programming, with the objective functions based on the compatibility, CEP(Circular Error Probable), and fire range of the weapons, along with the planned wartime mission-specific weapon ratios for each aircraft type. The experimental result's analysis of the proposed model indicate a significant increase in mission performance efficiency compared to the existing system in both operational and maintenance aspects. We hope that our model will be reflected to help improve the operational capabilities of Republic of Korea Air Force.

This study proposes a mathematical model to optimize the fighter aircraft-weapon combinations for the Republic of Korea Air Force. With the recent emergence of the population cliff issue due to declining birth rates in Korea, there is an urgent need for efficient weapon system operations in light of decreasing military personnel. This study aims to enhance operational environments and mission efficiency within the military. The objective is to reduce the workload of pilots and maintenance personnel by operating an optimal number of weapons instead of deploying all possible armaments for each aircraft type. To achieve this, various factors for optimizing the fighter-weapon combinations were identified and quantified. A model was then constructed using goal programming, with the objective functions based on the compatibility, Circular Error Probable (CEP), and fire range of the weapons, along with the planned wartime mission-specific weapon ratios for each aircraft type. Experimental analysis of the proposed model indicated a significant increase in mission performance efficiency compared to the existing system in both operational and maintenance aspects. It is hoped that this model will be applied in military settings.

PURPOSES : This paper presents a foundational study aimed at strengthening the competitiveness of future overseas construction engineering projects, efficiently guiding investment decisions for the government or private sectors and establishing policy suggestions for areas that need to be supplemented and linked. METHODS : The data envelopment analysis (DEA) model was used to measure the operational efficiency for individual types of work. The DEA model for measuring efficiency uses the representative Charnes, Cooper, and Rhode (CCR) and Banker, Charnes, and Cooper (BCC) models. RESULTS : By using statistics of overseas construction projects and conducting DEA, it was revealed that construction management was most needed in the energy facility sector of overseas construction projects. CONCLUSIONS : Although the capabilities of our country's companies are excellent, it was evident that the energy and industrial facilities sectors, which need to be supplemented to enhance their competitiveness, require policy support that incorporates construction management (CM). Consequently, it was confirmed that the construction management sector needs investment that should continue to be activated in the future. Additional research is needed that considers variables and environments related to overseas construction projects’ on-site conditions. To this end, the government should continue to promote research and government investment linked to CM to make progress in overseas construction sectors.

The n-type Bi2-xSbxTe3 compounds have been of great interest due to its potential to achieve a high thermoelectric performance, comparable to that of p-type Bi2-xSbxTe3. However, a comprehensive understanding on the thermoelectric properties remains lacking. Here, we investigate the thermoelectric transport properties and band characteristics of n-type Bi2-xSbxTe3 (x = 0.1 – 1.1) based on experimental and theoretical considerations. We find that the higher power factor at lower Sb content results from the optimized balance between the density of state effective mass and nondegenerate mobility. Additionally, a higher carrier concentration at lower x suppresses bipolar conduction, thereby reducing thermal conductivity at elevated temperatures. Consequently, the highest zT of ~ 0.5 is observed at 450 K for x = 0.1 and, according to the single parabolic band model, it could be further improved by ~70 % through carrier concentration tuning.

PURPOSES : The primary objective of this study is to analyze the relationship between the factors that affect traffic incident duration in the mainline, tunnel, and ramp segments of an expressway. In addition, this study derived the most suitable statistical prediction model based on various incident duration distributions. METHODS : South Korean expressway crash data for 11 years, from 2011 to 2021, were analyzed. The incident durations on the mainline, tunnel, and ramp segments were selected using the accelerated failure time model, which is a parametric survival analysis approach. RESULTS : The mainline segment showed that the incident duration increased during accidents, including guard pipe collisions, multivehicle collisions, and snowfall. In particular, collisions in a tunnel with shoulder facilities increase the incident duration, while decreasing the time in the ramp segment. CONCLUSIONS : The incident duration model for each segment type yielded the most accurate results when applying a log-logistic distribution.

In stream ecosystem assessment, RIVPACS, which makes a simple but clear evaluation based on macroinvertebrate community, is widely used. In this study, a preliminary study was conducted to develop a RIVPACS-type model suitable for Korean streams nationwide. Reference streams were classified into two types (upstream and downstream), and a prediction model for macroinvertebrates was developed based on each family. A model for upstream was divided into 7 (train): 3 (test), and that for downstream was made using a leave-one-out method. Variables for the models were selected by non-metric multidimensional scaling, and seven variables were chosen, including elevation, slope, annual average temperature, stream width, forest ratio in land use, riffle ratio in hydrological characteristics, and boulder ratio in substrate composition. Stream order classified 3,224 sites as upstream and downstream, and community compositions of sites were predicted. The prediction was conducted for 30 macroinvertebrate families. Expected (E) and observed fauna (O) were compared using an ASPT biotic index, which is computed by dividing the BMWPK score into the number of families in a community. EQR values (i.e. O/E) for ASPT were used to assess stream condition. Lastly, we compared EQR to BMI, an index that is commonly used in the assessment. In the results, the average observed ASPT was 4.82 (±2.04 SD) and the expected one was 6.30 (±0.79 SD), and the expected ASPT was higher than the observed one. In the comparison between EQR and BMI index, EQR generally showed a higher value than the BMI index.

PURPOSES : The objective of this study is to develop an optimal placement of the overturning prevention device based on a 3D object model during the development of the girder-type overturning prevention device for the remote control construction of bridges METHODS : Based on existing construction methods and literature research, a detailed design model of a phase-optimized conduction prevention device is presented. The 3D-object model data, optimal placement, and an operating range of the equipment developed for the remote control construction of bridge girders were considered. RESULTS : The shape of the overturning prevention device was selected taking into account the dimensions and operating range of numerous devices developed for the remote control construction of the bridge. In particular, the detachable device was chosen to allow a trouble-free construction considering the spacing between the pier cap of the bridge and the girders. The overturning prevention device presented based on this 3D object model will be manufactured as a mock-up and used for a demonstration project on remote control bridge construction. CONCLUSIONS : This will enable easy and economical construction as this development will support remote control construction of bridge girders to avoid accidents such as workers falling from high places like piers.

KAERI has planned to carry out a series of dynamic tests using a shaking table and time-history analyses for a channel-type concrete shear wall to investigate its seismic performance because of the recently frequent occurrence of earthquakes in the south-eastern parts of Korea. The overall size of a test specimen is ×× 2500 mm×3500 mm×4500 mm, and it consists of three stories having slabs and walls with thicknesses of 140 mm and 150 mm, respectively. The system identification, FE model updating, and time-history analysis results for a test shear wall are presented herein. By applying the advanced system identification, so-called pLSCF, the improved modal parameters are extracted in the lower modes. Using three FE in-house packages, such as FEMtools, Ruaumoko, and VecTor4, the eigenanalyses are made for an initial FE model, resulting in consistency in eigenvalues. However, they exhibit relatively stiffer behavior, as much as 30 to 50% compared with those extracted from the test in the 1st and 2nd modes. The FE model updating is carried out to consider the 6-dofs spring stiffnesses at the wall base as major parameters by adopting a Bayesian type automatic updating algorithm to minimize the residuals in modal parameters. The updating results indicate that the highest sensitivity is apparent in the vertical translational springs at few locations ranging from 300 to 500% in variation. However, their changes seem to have no physical meaning because of the numerical values. Finally, using the updated FE model, the time-history responses are predicted by Ruaumoko at each floor where accelerometers are located. The accelerograms between test and analysis show an acceptable match in terms of maximum and minimum values. However, the magnitudes and patterns of floor response spectra seem somewhat different because of the slightly different input accelerograms and damping ratios involved.

해양공간 이용 수요와 중요도의 지속적인 증가에 따라 국내에서의 해양탐사 및 해양조사활동이 활발히 수행중이다. 이러한 활 동을 위해 운항되는 해양탐사조사선은 목적 및 탐사선박에 따라 특수한 운항패턴을 가지므로 해상교통위험도를 고려한 연구가 필요하다. 본 연구에서는 해양탐사·조사선의 운항이 해상교통에 미치는 영향을 각 요인별 상관관계로 파악하고자 하였다. 우리나라에서 활동중인 해양탐사·조사선 현황을 파악하였고 일부 해양물리탐사선의 특수한 운항실태를 식별하였다. 운항자부담감의 결과를 비교하기 위해서 운 항요인 중 각 2가지를 독립변수로하여 ES Model 기반의 해상교통류시뮬레이션을 수행하였다. 분석결과 교통량, 선박 길이, 속력 순으로 운항자 부담감이 두드러지게 변화하는 것을 확인하였다. 또한 인근 해상교통흐름과 선수방위(침로)가 거의 유사한 운항 침로를 설정할 경 우 운항자 부담감이 다소 감소하는 것을 확인하였다. 이에 따라 해양탐사·조사선이 운항계획을 설정할 단계에서 인근 해상교통현황을 파 악하여 운항방식에 반영한다면 운항자 부담감을 감소시키는데 기여할 것이다.

The current study identified risk factors associated with porcine circovirus type 2 (PCV2) infection on pig farms in the Republic of Korea using a multinomial logistic regression model to evaluate the PCV2 infection status of pigs at different growth stages. Compulsory disinfection of visitors (odds ratio [OR]: 0.019, 95% confidence interval [CI]: <0.001–0.378, p=0.0095), compulsory registration of visitors (OR: 0.002, 95% CI: <0.001–0.184, p=0.0070), regular blood testing (OR: 0.012, 95% CI: <0.001–0.157, p=0.0007), and running on-farm biosecurity learning programs for workers (OR: 0.156, 95% CI: 0.040–0.604, p=0.0072 and OR: 0.201, 95% CI: 0.055–0.737, p=0.0155, respectively) were identified as factors which could reduce the risk of PCV2 infection. However, visitation by a regular veterinarian (OR: 32.733, 95% CI: 3.768–284.327, p=0.0016) was associated with PCV2 infection.

In this paper, an experimental study was carried out for vibration control of cable bridges with structurally flexible characteristics. For the experiment on vibration control, a model bridge was constructed by reducing the Seohae Grand Bridge and the shear type MR damper was designed using the wind load response measured at Seohae Grand Bridge. The shear type MR damper was installed in the vertical direction at the middle span of the model bridge, and dynamic modeling was performed using the power model. The tests of the vibration control were carried out by non-control, passive on/off control and Lyapunov control method on model bridge with scaled wind load response. The performance of the vibration control was evaluated by calculating absolute maximum displacement, RMS displacement, absolute maximum acceleration, RMS acceleration, and size of applied power using the response (displacement, acceleration, etc.) from the model bridge. As a result, the power model was effective in simulating the nonlinear behavior of the MR damper, and the Lyapunov control method using the MR damper was able to control the vibration of the structure and reduce the size of the power supply.

As the fourth industry revolution is starting, most of the fields including education are rapidly being changed. In parituclar, research on IT or SW fusion in each field is being performed. This paper discusses novel approaches to improve previous education services through IT fusion. First, I propose a way to converge IT into global education, which focuses on students of the college of education who are interested in becoming teachers. Due to internationalization demands in the field of education, the necessity of global education is increasing rapidly. However, a general consensus of the definition and model for global education is not clear yet and the actual performance falls short of our expectations owing to high cost, low effectiveness, and lack of persistence in the process of global education. To overcome the limits of global education and develop an efficient education system, this research suggests an IT-fusion-based education system for training global teachers. Second, it is difficult for an instructor to grasp instantly how much learners understand learning content in class in a typical education environment. In case of a class, which consists of possibly dozens of students at various levels ; trying to understand degree and learning achievement of the learners in a broad spectrum, depending on the learning contents. Therefore, it is almost impossible for an instructor to let all of the learners reach a specific learning objective. In this paper, I propose an approach that enables the arbitrary rate of learners, who reach a learning goal, to be set by an instructor. I describe an instruction support system combined with an instant response system, dynamic formative evaluation scheme, and confidence level. I expect that this approach can make an instructor set the ratio of learners, who reach the learning objective, as the instructor wants, and brings about effective instruction. Third, this study proposes a new learning model for improving problem solving and programming skills. To solve a real world problem using IT, problem solving and programming skills are important. In this study, I describe a learning model that can help to improve problem solving and programming skills, based on computational thinking. The feature of the learning model proposed is to offer learners challenges and spur interest by presenting the questions into learning games of an intercompetition type after developing the questions that improve problem solving and programming skills. Another feature is to present the questions about algorithms and programming in various forms and generate them dynamically. Especially, by providing an inter-competition game type, due to increase of competition between learners, learners will feel relatively less difficulty in problem solving and programming, and enable them to naturally improve problem solving abilities and programming skills through the competition.

The purpose of this study is to make a generalized analytical based on the proposed experiments on reinforced concrete(RC) partially infilled frames by U-type precast concrete(PC) wall panels with openings. RC frame and PC wall panels were connected with different strengths. Therefore, we developed modified strut-tie model(STM) with two seismic retrofitting specimens and conducted a nonlinear analysis by using a computer analysis program. Based on the test results, truss member of modified STM was designed, applying the strut-tie model theory of ACI 318M-11 Appendix- A. As a result, the modified STM analysis results were very similar to the experimental results. As a result of the load-displacement curve comparison, the failure load were similar within 5∼17% of error range. In particular, the experimental results and the results of modified STM analysis show that the failure behavior almost matched.