This paper presents a novel methodology for assessing the vulnerabilities of autonomous vehicles (AVs) across diverse operational design domains (ODDs) related to road transportation infrastructure, categorized by the level of service (LOS). Unlike previous studies that primarily focused on the technical performance of AVs, this study addressed the gap in understanding the impact of dynamic ODDs on driving safety under real-world traffic conditions. To overcome these limitations, we conducted a microscopic traffic simulation experiment on the Sangam autonomous mobility testbed in Seoul. This study systematically evaluated the driving vulnerability of AVs under various traffic conditions (LOSs A–E) across multiple ODD types, including signalized intersections, unsignalized intersections, roundabouts, and pedestrian crossings. A multivariate analysis of variance (MANOVA) was employed to quantify the discriminatory power of the evaluation indicators as the traffic volume was changed by ODD. Furthermore, an autonomous driving vulnerability score (ADVS) was proposed to conduct sensitivity analyses of the vulnerability of each ODD to autonomous driving. The findings indicate that different ODDs exhibit varying levels of sensitivity to autonomous driving vulnerabilities owing to changes in traffic volume. As the LOS deteriorates, driving vulnerability significantly increases for AV–bicycle interactions and AV right turns at both signalized and unsignalized intersections. These results are expected to be valuable for developing scenarios and evaluation systems to assess the driving capabilities of AVs.

본 연구는 상록활엽수림이 존재하는 도서지역 중 제주도, 울릉도, 흑산도, 홍도, 완도 총 5개 도서를 대상으로 군집유 형을 분류하고 분류된 군집별 층위 구조와 환경 특성을 구명하고자 수행되었다. 야외조사는 2020년부터 2024년까지 식물사회학적 방법으로 총 143개의 조사구에서 식생조사를 진행하였으며, 조사된 자료는 클러스터 분석을 통해 군집유 형을 분류하였다. 그 결과, 후박나무군집, 종가시나무군집, 구실잣밤나무군집, 붉가시나무군집 총 4개의 군집유형으로 분류되었다. 분류된 군집의 중요치를 통한 층위 구조를 볼 때 모든 군집에서 현재의 구조가 당분간 유지될 것으로 판단되었으나, 아교목층과 관목층에서 후박나무, 까마귀쪽나무, 동백나무 등의 수종이 층위 경쟁을 하고 있어 상록활엽 수 임분의 천이과정을 이해하기 위해서는 경쟁 수종들의 장기 관찰이 필요할 것으로 판단되었다. 종다양도는 다른 군집에 비해 종가시나무군집에서 높게 나타났는데, 이는 종가시나무군집의 입지가 계곡성이기에 나타난 결과로 판단되 었다. 수관 계층에서는 종가시나무군집을 제외한 3개의 군집의 교목층 최저 수고가 낮게 나타났는데 이는 홍도, 흑산도 에 위치한 조사지의 입지가 해안가 급경사지에 위치하여 나타난 결과로 판단되었으며, 종가시나무군집은 수관 계층고 특징으로 인해 상대적으로 광 투과율이 높아 하층의 종다양도가 높게 나타난 것으로 판단되었다. 군집별로 해발고도, 방위, 위도 3가지의 환경인자가 통계적으로 유의미한 차이가 있었는데, 난온대지역의 상록활엽수림을 복원 또는 신규조 림 시에 해발고도, 방위, 위도를 고려하여 수종을 선택할 필요가 있다고 판단되었다.

With the electrification of mobility, various electric shuttle carts are produced as short-range transportation, and are used in golf courses, resorts, and amusement parks. The shuttle cart is driven at the low speed of 20km/h, and various passengers from 2 to 14 seats can be applied depending on the purpose of use. However, although the demand for 14-seat electric shuttle carts for short-range transportation is increasing, there are mainly imported, modified, and sold from foreign countries. In this study, the chassis frame for the 14-seat electric shuttle cart was designed, and structural stability was confirmed through CAE analysis. In addition, the frame of the chassis platform with SS400 material was manufactured. The chassis platform with powertrain, steering, braking, and suspension unit was developed and the performance test was confirmed.

본 연구는 강릉 소나무 친환경벌채지 산림식생(벌채지, 산림영향권, 군상잔존구, 수림대, 대조구)을 대상으로 산림군집구조를 구명하고 조림학적 갱신 정보를 제공하고자 수행되었다. 2020년 7월 75개소의 방형구를 Braun-Blanquet 방법으로 식생조사를 실시한 후 중요치, 종다양도, 군락유사도, DCA를 분석하였다. 그 결과, 벌채지와 산림영향권에서 큰기름새의 중요치가 높은 것으로 나타났다. 종다양도는 대조구가 1.733로 가장 높게 나타났고, 벌채지가 1.237로 가장 낮게 나타났다. 군락유사도는 벌채지와 산림영향권이 0.706로 가장 높게 나타났고, 벌채지와 대조구가 0.452로 가장 낮게 나타났으며, Sørensen의 유사계수와 더불어 조사위치별 거리를 정량적으로 확인해 보고자 DCA분석을 실시한 결과 군락유사도와 유사한 결과를 나타내었다. 본 연구는 단기적인 연구결과이므로 추후 장기적인 모니터링을 통해 변화되는 친환경벌채지 산림식생에 대한 지속적인 식생 정보의 축적을 통해, 산림영향권이 포함된 친환경벌채지 산림식생의 회복과정에 대한 연구가 필요할 것으로 판단된다.

This study investigated effects of seedling age and planting density on early growth performances of Fraxinus rhynchophylla trees. Containerized F. rhynchophylla seedlings (1-year-old and 2-year-old) were planted according to two different planting densities (3,000 and 5,000 trees ha-1) in April of 2017 in Gangneung city, Gangwon province, South Korea. Survival rate, root collar diameter (RCD), and height (H) were measured from 2017 to 2022 (except for 2021). H/RCD (H/D) ratio and stem volume were then calculated. It was found that growth performances of F. rhynchophylla trees were only affected by seedling age. In 2022, mean (±standard error) RCD (mm), H (cm), and stem volume (cm3 tree-1) were the highest for 5,000 trees ha-1 of 2-year-old seedlings (at 30.7, 197.3, and 1001.8, respectively). Initial RCD and H showed relationships with stem volume (in 2017- 2020). As growth space decreased, planted trees initially showed rapid growth due to light competition. In this study, the optimal seedling age and density of planting for F. rhynchophylla were confirmed and important data were secured for preparing a plan for post-reforestation management including operations of weed removal and young tree tending.

Indoor air quality is a critical factor affecting health and quality of life, especially in spaces frequently used by sensitive populations such as adolescents. This study assessed the impact of garden ball installations and electrochemical fertilizer applications on indoor air quality in two youth centers, Center S and Center W, located in Bucheon, South Korea. PM2.5, PM10, and CO2 concentrations were monitored and analyzed based on the presence of garden balls and the use of electrochemical fertilizers. The results showed that spaces with garden balls (w/ G.B.) had significantly lower PM2.5 and PM10 concentrations compared to offices and spaces without garden balls (w/o G.B.). In Center W, the presence of garden balls alone improved air quality, highlighting the potential of vertical greening as a sustainable solution. In Center S, the application of electrochemical fertilizers during the “after + period” (when both garden balls and electrochemical fertilizers were applied) further enhanced particulate matter reduction, demonstrating the fertilizers’ ability to amplify plants’ air-purifying effects. This study provides empirical evidence that garden balls are an eco-friendly option for indoor air quality management. Combining electrochemical fertilizers with garden balls shows promise for enhancing air quality, offering a practical model for multi-use facilities such as youth centers.

Along with the increase in the number of vehicles in circulation, the indoor air quality in automobiles is attracting attention as another possible health concern. However compared to data regarding indoor air quality in other spaces, there are insufficient data on indoor air quality in automobiles. In addition, there is no standard for the evaluation method. In this study, the change in the concentration of particulate matter in the vehicle while driving under real road conditions was analyzed in order to use it as basic data for a method to evaluate vehicle indoor air quality. Through the selection of measurement target materials and test vehicles and the preparation of test methodologies, evaluation was performed on vehicle, route, and HVAC modes. The concentration of particulate matter in the vehicle was the lowest in the RC (In-vehicle recirculation) condition, and it was confirmed that it decreased with time. The highest average concentration was confirmed in the OA (Outside air ventilation) condition, and the concentration change according to the changing HVAC mode was observed in the Auto condition. The concentration of pollutants inside the vehicle showed a significant correlation with factors such as season, external concentration, and HVAC conditions, along with a weak correlation to powertrain type. The results of this study can be used as basic data for developing methods for evaluating vehicle interior air quality in future work.

Objectives: The main purpose of this study was to identify problems such as cooking fumes and lack of ventilation in school cafeterias and evaluate the improvement in the reduction of indoor pollutants in the cooking rooms through renovation. Methods: Three schools were selected for renovation and the spatial structures and air conditioning system of the cafeterias and cooking rooms wre investigated after renovation. The air conditioning systems were improved by the renovation work according to the characteristics of each school, and the concentration of indoor pollutants was measured and evaluated through CFD analysis. Results: The concentration of indoor pollutants in the cafeterias and cafe rooms was decreased after renovation. Conclusion: Air conditioning systems in the schools cafeterias and cooking rooms were improved in order to solve the problems of ventilation, and the indoor air quality improvement rate ranged from a minimum of 11% to a maximum of 40%. The renovation of cafeterias and cooking rooms was conducted to optimize the ventilation systems and this contributed to indoor air quality improvement by preventing the inflow of pollutants.

Driving Resistance is calculated for emission test defines total vehicle resistance forces. Resistance factors of running vehicle are sum of rolling resistance, transmission loss and aerodynamic drag force. To measure this resistance, Coastdown test is conventional method and it needs a long level driving road. In this study coastdown test is executed on short driving road. And also each resistance factors are calculated. This test is based on S(Distance)-Time Method. From the result, it is shown that this method is reliable and can be used for initial vehicle test.

One of the efficient method for DPF(Diesel Particulate Filter) regeneration of diesel engines is using post fuel injection, which is injected into the combustion chamber during the expansion stroke. This method generates a heat for DPF regeneration by oxidation of HC with Pt coated on DOC(Diesel Oxidation Catalyst). This study investigates heat generation of DOC using post fuel injection.

PURPOSES : This study aimed to derive the factors that contribute to crash severity in mixed traffic situations and suggest policy implications for enhancing traffic safety related to these contributing factors. METHODS : California autonomous vehicle (AV) accident reports and Google Maps based on accident location were used to identify potential accident severity-contributing factors. A decision tree analysis was adopted to derive the crash severity analyses. The 24 candidate variables that affected crash severity were used as the decision tree input variables, with the output being the crash severity categorized as high, medium, and low. RESULTS : The crash severity contributing factor results showed that the number of lanes, speed limit, bus stop, AV traveling straight, AV turning left, rightmost dedicated lane, and nighttime conditions are variables that affect crash severity. In particular, the speed limit was found to be a factor that caused serious crashes, suggesting that the AV driving speed is closely related to crash severity. Therefore, a speed management strategy for mixed traffic situations is proposed to decrease crash severity and enhance traffic safety. CONCLUSIONS : This paper presents policy implications for reducing accidents caused by autonomous and manual vehicle interactions in terms of engineering, education, enforcement, and governance. The findings of this study are expected to serve as a basis for preparing preventive measures against AV-related accidents.

This study investigated the impact of soil-structure interaction on multi-degree-of-freedom structures using the shallow-foundation Winkler model, known as the BNWF model. The model’s period was determined through eigenvalue analysis and compared to results obtained from FEMA’s formula. Results indicated that considering the soil, the structure’s period increased by up to 8.7% compared to the fixed-base model, aligning with FEMA’s calculations. Furthermore, with adequate ground acceleration, roof displacement increased by 3.4% to 3.8%, while base shear decreased by 4% to 10%. However, roof displacement and base shear increased in some earthquake scenarios due to spectral shape effects in regions with extended structural periods. Foundation damping effects, determined through the foundation’s moment-rotation history, grew with higher ground acceleration. This suggests that accounting for period elongation and foundation damping can enhance the seismic design of multi-degree-of-freedom structures.

In this paper, a shot peening was conducted to improve fatigue life by increasing resistance to hydrogen embrittlement of STS316 steel, which is widely used in hydrogen environments. First, considering the efficiency of the shot peening process, an effective Almen intensity was selected and applied to the specimen surface. Second, the specimen was hydrogen embrittled at room temperature (25°C) and high temperature (60°C) using electrochemical hydrogen charging. Third, the mechanical property tests (tensile, hardness, roughness) and 4-points rotational bending fatigue tests of the specimen were performed. All mechanical properties decreased, but the fatigue life of the shot peened specimens improved at the both temperature conditions. Ultimately, the fatigue characteristics against hydrogen embrittlement of STS316 steel, which is used in various industrial fields, are improved through an effective shot peening process, and the effect is believed to be very significant.

본 연구에서는 지구과학 교육 연구 논문들을 대상으로 질적 메타 분석을 통해 집단적 PCK (cPCK) 중 ‘특정 과 학 주제(온실 효과, 지구 온난화, 기후변화)에 대한 학생 이해 지식’을 도출하고자 하였다. 이를 위해 온실 효과, 지구 온난화, 기후변화에 대한 학생 대체 개념(오개념)과 관련된 지구과학 교육 연구 논문 22편을 선정하여 각각의 정의, 원 인(매커니즘), 그리고 영향에 대하여 분석하였다. 분석 결과를 종합하기 위해 언어 네트워크 분석, 정신모형틀을 적용하 였다. 연구 결과는 다음과 같다; (1) 온실 효과에 대한 학생들의 개념 이해를 메타 분석한 결과, 온실 효과와 지구 온난 화를 같은 의미로 사용하는 것으로 분석되었으며, 온실 기체의 종류를 제한적으로 알고 있고, 온실 기체의 역할을 이해 하지 못하는 것으로 나타났다. 또한 온실 효과의 발생을 환경오염이나 오존층의 변화와 관련지어 생각하고, 지표-대기의 열수지 평형과 온실 효과를 관련짓지 못하는 것으로 분석되었다. (2) 지구 온난화에 대한 학생들의 개념 이해를 메타 분석한 결과, 지구 온난화를 해수면 상승과 같은 의미로 사용하는 것으로 분석되었으며, 지구 온난화의 발생을 환경오 염, 오존층의 변화, 빙하의 융해와 관련지어 생각하고, 지표-대기의 열수지 평형이 깨져 지구 온난화가 나타나는 것으로 이해하고 있었다. 또한 지구 온난화가 환경에 미치는 영향을 잘못 알고 있는 것으로 분석되었다. (3) 기후변화에 대한 학생들의 개념 이해를 메타 분석한 결과, 기후변화를 지구 온난화, 기상 변화, 기상 이변과 같은 의미로 사용하는 것으 로 분석되었으며, 기후변화의 발생을 대기오염, 오존층의 파괴와 관련지어 생각하는 것으로 분석되었다. 또한 기후변화 가 우리 생활과 환경에 미치는 영향을 잘못 알고 있는 것으로 분석되었다. 이에 대한 분석 결과를 언어 네트워크 분석 을 통해 종합한 결과, 집단적 PCK로서 3가지 정신모형(범주적 오해, 기제적 오해, 위계적 오해)을 표현할 수 있었다. 이 와 같은 연구 결과를 바탕으로 지구과학 교사 PCK 개발을 위한 함의를 논의하였다.

This study aimed to provide ecological information by identifying the stand characteristics of Larix kaempferi forest vegetation (deforestation, forest influence, patch, forest) for aggregated retention harvest in Mt. Nambyeongsan, Pyeongchang- Gun. Data were collected using the Braun-Blanquet vegetation survey method from July 2020, with 54 quadrats analyzed for importance value, species diversity, similarity index, and detrended correspondence analysis (DCA). The results showed that vine species had a higher importance value in the deforestation area and forest influence area. Forest regions had the highest species diversity (2.419), while the forest influence area had the lowest (2.171). The similarity index was highest between the forest region and patch area (0.723), and lowest between the patch area and forest influence area (0.658), which was consistent with the DCA results. In conclusion, although species diversity temporarily showed higher values in the initial stage after aggregated retention harvest, it was difficult to assign ecologically specific meanings to these values. Long-term monitoring is therefore necessary to accumulate ecological information on aggregated retention harvests.

The objective of this study is to analyze the indoor air quality of multi-use facilities using an IoT-based monitoring and control system. Thise study aims to identify effective management strategies and propose policy improvements. This research focused on 50 multi-use facilities, including daycare centers, medical centers, and libraries. Data on PM10, PM2.5, CO2, temperature, and humidity were collected 24 hours a day from June 2019 to April 2020. The analysis included variations in indoor air quality by season, hour, and day of the week (including both weekdays and weekends). Additionally, ways to utilize IoT monitoring systems using big data were propsed. The reliability analysis of the IoT monitoring network showed an accuracy of 81.0% for PM10 and 76.1% for PM2.5. Indoor air quality varied significantly by season, with higher particulate matter levels in winter and spring, and slightly higher levels on weekends compared to weekdays. There was a positive correlation found between outdoor and indoor pollutant levels. Indoor air quality management in multi-use facilities requires season-specific strategies, particularly during the winter and spring. Furhtermore, enhanced management is necessary during weekends due to higher pollutant levels.

Phayathonzu temple in Myanmar was made of masonry bricks, and so it was vulnerable to lateral load such as earthquake. Especially, it has many difficulties in structural modeling and dynamic analysis because the discontinuous characteristics of masonry structure should be considered. So, it is necessary to provide the seismic performance evaluation technology through the inelastic dynamic modeling and analysis under earthquake loads for the safety security of masonry brick temple. Therefore, this study analyzes the seismic behavior characteristics and evaluates the seismic performance for the 479 structure with many cracks and deformations. Through the evaluation results, we found out the structural weak parts on earthquake loads.

1990년대 이후 급증한 탄소 배출량은 지구 온도 상승을 가속화하고 있으며, 도시는 온실가스 배출의 주요 원인으로서 약 70%의 배출량을 차지하고 있다. 이에 탄소중립 노력이 중요해지면서 도시 내 유일 한 탄소흡수원인 녹색공간의 효과적인 활용이 필수적이다. 본 연구는 탄소중립 녹색공간 평가를 위한 지표와 산정기준을 개발하기 위해 사례분석과 델파이 기법을 활용한 전문가 자문을 진행하였다. 그 결 과 총 45개의 평가지표가 구축되었으며, 5개 근린공원에 적용하여 지표의 적용 가능성을 검토하였다. 사례평가 결과 SCOPE 1, 2단계에 속하는 바이오매스 격리, 저탄소 공법 및 자재사용, 원형보존 유형이 탄소중립에 기여하는 정도가 높았으며, 탄소 특화공원이 일반 근린공원에 비해 강점을 보이는 것을 확 인하였다. 본 연구는 탄소중립 녹색공간 인증제 실현을 위한 도구를 제공하고 평가 프레임워크 구축에 중요한 기반 마련에 기여할 것으로 기대한다.