• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.667-675
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• 2021

The purpose of this study is as follows: First, to analyze the spatial structure of Jeju by analyzing the rate of parking demand and supply; Second, to determine the parking service imbalance between regions; and third, to elucidate the causes of this spatial structural parking service imbalance and provide effective measures. Due to the rapid population and tourism growth, Jeju is suffering from traffic congestion and serious parking problems. For this, the ways to efficiently utilize the existing parking spaces were identified through spatial structure analysis based on the parking demand and supply in the Jeju area. As short-term policy, the following changes were proposed: switching to small-scale eup or myeon blocks of parking space, use of shared parking system, and repairing side streets in residential areas. As mid-to-long-term policy, it is linked to other means of transportation as follows: parking demand management policy through modal share by reorganizing public transportation routes or expanding traffic facilities; securing park-and-ride lots; and different parking pricing for different time periods. To implement these policies, each area of the public sector, private sector, and private-public partnership should develop the bond of sympathy by areas and participants.

• Journal of the Korean Regional Science Association
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• v.37 no.2
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• pp.17-33
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• 2021

This study empirically analyzes the effect of the spread of COVID-19 and the implementation of social distancing on the number of park users. To this end, we analyzed the time series data on the number of users and the COVID-19 outbreak at Olympic Park, a large-scale comprehensive urban park located in Songpa-gu, Seoul, and four neighborhood parks in the same municipality. And this was compared with the effect on the change in the number of users around Jamsil Lotte World, a representative indoor complex leisure space in Seoul. The analysis results are as follows: First, in small neighborhood parks located in residential areas, the number of users increased by 3 to 6% on average due to the implementation of the social distancing measures and the increase in the number of confirmed COVID-19 cases. In particular, it was found that changes in park use were sensitive to the increase in the intensity of social distancing. On the other hand, the number of users around Jamsil Lotte World decreased by 38% on average, and in the case of Olympic Park, the number of users decreased by 1.9% on average due to the spread of COVID-19. Considering that the number of the vehicle users representing remote users of Olympic Park has decreased by 23% on average, it is estimated that there is little change in the number of users in the surrounding areas. This suggests that urban parks, especially neighborhood parks in residential areas, play a role as a major refuge and leisure space for urban people in the event of a pandemic disaster such as COVID-19, and therefore need to be properly supplied and maintained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.603-611
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• 2020

Potholes on the road directly affect drivers' safety, satisfaction, and vehicle damage. Thus, real-time detection and response are required. Increasing frequency of patrols allows for potholes to be detected and responded to quickly, but this takes much manpower, money, and time. In addition, potholes have different occurrence characteristics depending on the rain conditions, so it is necessary to consider the optimal frequency from an economic and road-service perspective. Therefore, a quantitative analysis was done on the effects of rainfall on the occurrence characteristics of potholes. Information on the persistence, impact of rainfall intensity, and weather information was collected over a long period. Based on the results, a risk-based, optimized, and changeable road-patrol strategy is presented. The analysis results show that the probability of pothole occurrence increases by 2.4 times in rainy weather. Furthermore, the impact continues for 3 days even after the rain stops. The probability of pothole occurrence increases by 0.46% per 1 mm of rainfall, and the occurrence characteristics react sensitively to even a small amount of rain of around 1 mm. It was concluded that road patrol is required at least once every three days for an effect-free period, while twice a day is needed for the "sphere of influence" period to achieve a 95% reliability level.ys for effect-free period, while twice a day for sphere of influence period to satisfy 95% reliability level.

• Journal of Wetlands Research
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• v.23 no.1
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• pp.44-53
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• 2021

Urban stormwater runoff contains heavy metals that accumulate in on-site treatment systems, thus resulting to facility deterioration and maintenance problems. In order to resolve these problems, low impact development (LID) technologies that promote natural materials circulation are widely used. LID facilities are capable of treating heavy metals in the runoff by means of plant uptake; however, the uptake or phytoremediation capabilities of plants have not been studied extensively, making it difficult to select the most suitable plant species for a certain LID design. This study investigated the vegetative components of an LID facility, roadside plants, and plants in landscape areas with different heavy metal exposure and frequency to determine the uptake capabilities of different plant species. The plants harvested inside the LID facilities and roadsides with high vehicular traffic exhibited greater heavy metal concentrations in their tissues as compared with the plants in landscape areas. Generally, the accumulation of heavy metals in the plant tissues were found to be influenced by the environmental characteristics (i.e. influent water quality, air pollution level, etc.). Dianthus, Metasequoia, Rhododendron lateritium, and Mugwort were found to be effective in removing Zn in the urban stormwater runoff. Additionally, Dianthus, Metasequoia, Mugwort, and Ginkgo Biloba exhibited excellent removal of Cu. Cherry Tree, Metasequoia, and mugwort efficiently removed Pb, whereas Dianthus was also found to be effective in treating As, Cr, and Cd in stormwater. Overall, different plant species showed varying heavy metal uptake capabilities. The results of this study can be used as an effective tool in selecting suitable plant species for removing heavy metals in the runoff from different land use types.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.363-370
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• 2022

In this paper, an estimation algorithm for state of charge (SOC) was applied using an equivalent circuit model (ECM) and an Extended Kalman Filter (EKF) to improve the estimation accuracy of the battery system states. In particular, an observer was designed to estimate SOC along with the aged capacity. In the case of the fresh battery, when SOC was estimated by Kalman Filter (KF), the mean absolute percentage error (MAPE) was 0.27% which was smaller than MAPE of 1.43% when the SOC was calculated by the model without the observer. In the driving mode of the vehicle, the general KF or EKF algorithm cannot be used to estimate both SOC and capacity. Considering that the battery aging does not occur in a short period of time, a strategy of periodically estimating the battery capacity during charging was proposed. In the charging mode, since the current is fixed at some intervals, a strategy for estimating the capacity along with the SOC in this situation was suggested. When the current was fixed, MAPE of SOC estimation was 0.54%, and the MAPE of capacity estimation was 2.24%. Since the current is fixed when charging, it is feasible to estimate the battery capacity and SOC simultaneously using the general EKF. This method can be used to periodically perform battery capacity correction when charging the battery. When driving, the SOC can be estimated using EKF with the corrected capacity.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.20-37
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• 2023

Although traffic signal installations are continuously expanding, the effect of preventing traffic accidents remains unverified. Totally, 7,045 traffic accident data (such as signal violations) registered with TCS were manually searched for a 7-year period from 2013 to 2019 for 1,602 traffic signals in Daejeon Metropolitan City. The top 20 traffic accident intersections were identified, the traffic accident investigation records and field maps were viewed to compare the driving direction and signal phase of the violated vehicle, and the cause of the traffic accident was divided into insufficient signal operation design (operation) and driver negligence (intentional). Results of the analysis revealed that 75% of traffic accidents occurred in thru-left-turn traffic signals and overlap; moreover, extending the yellow time or operating all red signals due to countermeasures against traffic accidents occurring in yellow signals resulted in reduced traffic accidents. Data indicated that Permissive Left Turn requires improvement with the signal operation. In addition, since The Korean National Police Agency is not computerized for traffic accident sites and signal-related data, the lack of manpower necessitates improvement and utilization of TCS when establishing traffic accident prevention measures. It is believed that it will contribute to signal operation by analyzing vast amounts of data collected in the field and presenting improvement measures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5D
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• pp.821-829
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• 2006

Traffic load comprise primary input to pavement design causing pavement damage. therefore it should be proceeded suitable traffic load distribution modeling for pavement design and analysis. Traffic load have been represented by equivalent single axle loads (ESALs) which convert mixed traffic stream into one value for design purposes. But there are some limit to apply ESALs to other roads because it is empirical value developed as part of the original AASHO(American Association of State Highway Officials) road test. There have been many efforts to solve these problems. Several leading country have implemented M-E(Mechanistic-Empirical) design procedures based on mechanical concept. As a result, they established traffic load quantification method using load distribution model known as Axle Load Spectra. This paper details Axle Load Spectra and presents axle load distribution model based on normal mixture distribution function using truck load data collected by WIM system installed in national highway. Axle load spectra and axle load distribution model presented in this paper could be useful for basic data when making traffic load quantification plan for pavement design, overweight vehicle permit plan and pavement maintenance cost plan.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.71-80
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• 2010

Bridge deck is directly influenced by environment and vehicle load, it is easily damaged so that it requires an appropriate repair and retrofit. Therefore, developing a bridge deck with high durability is necessary in order to minimize the maintenance of bridge deck and use it to its design life. In this study, static test was carried out to evaluate a fatigue capacity of steel-concrete composite deck, which was newly developed by supplementing problems of existing reinforced concrete deck. Based on results from the static test, fatigue load was decided, and fatigue test was conducted under the constant amplitude repeated load. From the fatigue tests, the S-N curve regarding principle structural details of composite deck was made, and characteristics of fatigue behavior was estimated by comparing and evaluating it with fatigue design criteria. In addition, fatigue design guideline was presented. As a result, it is found that each structural details of composite deck proposed by this study, such as upper flange of corrugated steel plate and middle section of it, shear connector and lower flange of corrugated steel plate, is satisfying the fatigue strength.

• 한국노년학
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• v.30 no.4
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• pp.1163-1177
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• 2010

This study was conducted to establish the appropriate facilities criteria of the Korean welfare devices center. We e-mail surveyed 194 welfare devices centers and analysed 13 blueprints of them. We established the following proper principles of facilities. First, consist type and area of room should depend on the type of welfare devices centers. Second, The flow of human and welfare devices should be simple. Third, the area calculated on the base of intent of center owner and the size of beds, wheelchairs, etc. Fourth, exhibit room facing with roadside may obtain advertising effect. Fifth, the storage and disinfecting room should use different entrance, and avoid the intersection of flow to prevent cross-contamination. Sixth, the access road to the exhibition and consulting room should be able to approach by the wheelchair. seventh, office room should be invisible to keep customer's privacy. Direct Cleaning-disinfecting type center on the premise that the maximum 165m², middle 150m², intermediate 140m², display at least Consultation, Cleaning-disinfecting room, storage (clean, contaminated), the office, equipped with a parking space. Entrust Cleaning-disinfecting type center on the premise that a maximum 134m², middle 119m², intermediate 109m² exhibited minimal activity room, consultation room, office, equipped with a parking space, collecting welfare when importing equipment warehouse (clean, pollution) have been proposed to equip up to.

• Journal of Service Research and Studies
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• v.14 no.3
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• pp.188-205
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• 2024

The food truck business, which involves selling various types of food from mobile vehicles, has gained significant popularity in urban centers and at events. These food trucks have rapidly expanded due to their relatively low initial investment and high flexibility, attracting customers with unique menus and personalized services. However, as competition increases, the need to manage service quality to boost customer satisfaction and encourage repeat visits has become more critical. Despite this growing importance, there has been limited empirical research on the topic. This study aims to analyze customer experiences with food truck services to gain strategic insights for improving service quality. By applying structural topic modeling to customer review data, the study identified 50 key topics. The process included a comprehensive evaluation of model diagnostics and interpretability to determine the optimal number of topics, ultimately selecting the most relevant ones related to service experiences. The impact of these identified topics on overall customer satisfaction was empirically tested using regression analysis. The results showed that aspects such as "Food Taste," "Friendly Staff," and "Positive Emotion" had a positive influence on customer satisfaction, whereas "Delayed Service," "Negative Emotion," and "Beverage Service" had a negative impact. Based on this analysis, the study proposes concrete methods for food truck operators to systematically analyze customer feedback and use it to drive service improvements and innovation. This research highlights the importance of data-driven decision-making in small business environments like food trucks and contributes to expanding the application of topic modeling in the service industry.