• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.118-123
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• 2000

Most quadruped walking robots under current research are individually controlling every joint ic make them step or walk according to an integrated strategy. Such methods are characterized by at least one pair of an actuator and a sensor installed per each 'oint so that the robots weigh execssively and move inefficiently in terms of energy expenditure. In addition, the task of controlling all the joints simultaneously is quite complex and prone to destabilize the robot motion. These respects keep the existing walking robots away from realistic applications such as transportation even if they have potentially, outstanding adaptability to swamps or uneven terrains as opposed to wheeled vehicles. So, this paper presents a new conceptual quadruped robot developed to walk and steer only with a minimal number of actuators owing to a closed-chain mechanism. To prove its actual performance including the adaptability to various types of terrains. experiments are done with the mammal-type prototype. And. it is also shown that the same concept can be easily extended to carry out different gait forms. for instance, that of spiders only with minor modifications.

• Journal of the Korean Regional Science Association
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• v.33 no.1
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• pp.29-41
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• 2017

This study proposes an integrated accessibility measurement algorithm, which is applied to the Seoul Metropolitan public transportation system consisting of bus and subway networks, and analyzes the result. We construct a public transportation network graph linking bus-subway networks and take the time distance as the link weight in the graph. We develop a time-distance algorithm to measure the time distance between each pair of transit stations based on the T-card transaction database. The average travel time between nodes has been computed via the shortest-path algorithm applied to the time-distance matrix, which is obtained from the average speed of each transit route in the T-card transaction database. Here the walking time between nodes is also taken into account if walking is involved. The integrated time-distance accessibility of each node in the Seoul Metropolitan public transportation system has been computed from the T-card data of 2013. We make a comparison between the results and those of the bus system and of the subway system, and analyze the spatial patterns. This study is the first attempt to measure the integrated time-distance accessibility for the Seoul Metropolitan public transportation system consisting of 16,277 nodes with 600 bus routes and 16 subway lines.

• Journal of Environmental Health Sciences
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• v.50 no.2
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• pp.157-167
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• 2024

Background: Several previous studies have shown that commuting is a source of stress for undergraduate students. However, few studies have investigated the effect of commuting on academic stress among undergraduate students, and there has been little awareness of the environmental impact of commuting. Objectives: To evaluate the associations between commute type and/or time and academic stress among undergraduate students in South Korea, focusing on environmental sustainability. Methods: We conducted an online survey and obtained information on commute types, commute times, and academic stress from 510 undergraduate students aged ≥19 years. Academic stress was comprised of five sub-categories of stress, and total academic stress ranged from 5 to 25 points. Multiple linear regression analysis was used to analyze the associations between commute type and commute time and academic stress. Furthermore, the students were grouped into 21 categories based on their transportation mode for commuting. CO₂ emission factors per each commuting category were calculated using the transportation type's CO₂ emission data from previous studies. Spearman's correlation analysis was used to confirm the correlation between CO₂ emission factors and total academic stress. Results: Students using home-to-school transportation without transfers (vs. walking) showed a significantly higher total academic stress of 2.19 points (95% CI: 0.58, 3.80). In contrast, students using school-to-home transportation without transfers (vs. walking) showed a significantly lower total academic stress of 1.96 points (95% CI: -3.55, -0.38). Moreover, students using transportation with lower CO₂ emission factors had lower academic stress scores (home-to-school: correlation coefficient = 0.507, p<0.001; school-to-home: correlation coefficient = 0.491, p<0.001). Conclusions: Our findings suggest that both commute type and time are significantly associated with academic stress among South Korean undergraduate students. When students select environmentally-friendly transportation, they may not only improve their mental health but also improve climate resilience.

• Journal of Urban Science
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• v.7 no.2
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• pp.1-9
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• 2018

In this study, Analysis of DRT model and contribustion based on the case of local governments adopting the Demand Responsive Transit(DRT) in order to provide transportation in public transportation service weak area. Based on the case of Yeoju Area, the contribution of the DRT was analyzed. The DRT model was established as a fixed and call type model with taxi and bus transportation. Based on the results of the happy taxi service in Yeoju Area in 2016, the contribution of DRT was analyzed. According to the happy taxi performance of Yeoju city, it was introduced to 27 villages, and operated 4,188 times. And 9,111 people used it and Yeoju Area supported about 53 million Won. The contribution of local governments was analyzed in terms of local government, users, and social aspects. On local government aspects, we analyzed the budget cuts and complaints resolution. On the user aspects, we analyzed waiting time reduction, walking time reduction, travel time reduction, comfort, punctuality, and stability. On social aspects, we analyzed taxi and regional economy activation, and convenience of mobility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.56-65
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• 2019

This study empirically analyzes the effect of weather on pedestrian volume in an urban space. We used data from the 2009 Seoul Flow Population Survey and constructed a model with the pedestrian volume as a dependent variable and the weather and physical environment as independent variables. We constructed 28 models and compared the results to determine the effects of weather on pedestrian volume by season, land use, and time zone. A negative binomial regression model was used because the dependent variable did not have a normal distribution. The results show that weather affects the volume of walking. Rain reduced walking volume in most models, and snow and thunderstorms reduced the volume in a small number of models. The effects of the weather depended on the season and land use, and the effects of environmental factors depended on the season. The results have various policy implications. First, it is necessary to provide semi-outdoor urban spaces that can cope with snow or rain. Second, it is necessary to have different policies to encourage walking for each season.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1D
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• pp.21-27
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• 2008

To respond to years-long economic decline in the downtown Seoul, it is necessary to lay out a scheme revitalizing downtown economy. It is called Wanavi and Shonavi system. When customers do shopping, it is the "Shonavi" that provides shopping information such as popular shop name, location, and commodity price to walkers in a real-time base. In addition, the walking navigation system called "Wanavi" is designed to provide access information for walking shoppers, the function of which is similar to car navigation system. The "Wanavi" can help walkers find the fastest, comfortable and attractive pedestrian route and public transportation information reaching to the destination in the downtown. In this study, we propose GPA & RFID mixed system as a communication technique to activate "Shonavi" and "Wanavi" system. The "Shonavi" and "Wanavi" system will be one of the ways to revitalize depressed downtown economy in Seoul.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1046-1048
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• 2003

Recently, various researches in respect of the positioning technologies using satellites and the other sensors have made location-based services (LBS) more common and accurate. Consequently, concern about position information has been increasing. However, since these positioning systems only focus on user's position, it is difficult to know the user's attitude or detailed behaviors at the specific position. It is worthy to study on how to acquire such human attitude or behavior, because those information is useful to know the context of the user. In this paper, the sensor unit consisting of three dimensional accelerometer was attached to human body, and autonomously measured the perpendicular acceleration of ordinary human behaviors including activity modes such as walking, running, and transportation mode using transportation such as a train, a bus, and an elevator. Subsequently, using the classified measurement results, the method to identify the human activity modes was proposed.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.3
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• pp.23-33
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• 2016

This study identified the factors that affect travel time budget by mode for traveler in Seoul using the SUR model. Individual, household and TAZ characteristics were selected as the explanatory variables. Transportation modes are summarized from 18 types to 6 types(walking, personal car, bus, subway, rail and bicycle). The results showed a distinct difference between personal transportation and public transportation. First of all, People who owned a car and driver's licence tend to prefer personal transportation. In addition, we can confirm the relationship between the bus and the subway which are most typical public transportation. Passengers who can available a personal mode preferred the subway than the bus. It is expected to suggest various implications related to the public transportation policy for Seoul metropolitan area.

• Journal of Korean Society of Transportation
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• v.26 no.3
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• pp.129-141
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• 2008

Portable navigation markets grew up to 95% last year. This study aims to develop a business model for pedestrian-oriented portable navigator for street shoppers. Related previous studies developed successfully the alogrithm for a portable navigator, and the current study seeks for diverse ways to turn this system into a new type of on & off line-based LBS business. The business model proposed in this study adopted two different approaches of benefit yields based on the structural analysis of so-called Wanavi navigation system. One is segmented approach seeking for benefits from each individual system component such as communication network, contents, and platform. The other approach is to run the business by integrating relevant system componts in every possible way to attract customers to this portable navigator. The purpose of this proposal is not limited to activate emerging walking navigator markets, but to aim at creating idealistic free market system where all the shoppers are furnished complete market information to the fullest extent when they go on shopping.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.4
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• pp.366-372
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• 2016

This paper advances the software, hardware and mechanical design that the visually impaired can recognize the position and distance of the obstacle while walking. The first software implementation is proposed a method to implement the algorithm graph for the ratio of the distance measuring ultrasonic sensors for voltage. And it was extracted by the precise distance measuring parameter values from simulation to measure the precise distance. Second hardware implementation was designed to be able to detect obstacles in a relatively simple sensor-based walking aid for the visually impaired. In addition, using the switching regulator IC of high performance it was designed to be used to boost the Li-ion battery 3.7V to 5V. The third mechanism was developed by analyzing the sensor angle and the cane angle.