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Simulation of Mobile Robot Navigation based on Multi-Sensor Data Fusion by Probabilistic Model
Tae?seok Jin 한국산업융합학회 2018 한국산업융합학회 논문집 Vol.21 No.4
Presently, the exploration of an unknown environment is an important task for the development of mobile robots and mobile robots are navigated by means of a number of methods, using navigating systems such as the sonar-sensing system or the visual-sensing system. To fully utilize the strengths of both the sonar and visual sensing systems, In mobile robotics, multi-sensor data fusion(MSDF) became useful method for navigation and collision avoiding. Moreover, their applicability for map building and navigation has exploited in recent years. In this paper, as the preliminary step for developing a multi-purpose autonomous carrier mobile robot to transport trolleys or heavy goods and serve as robotic nursing assistant in hospital wards. The aim of this paper is to present the use of multi-sensor data fusion such as ultrasonic sensor, IR sensor for mobile robot to navigate, and presents an experimental mobile robot designed to operate autonomously within indoor environments. Simulation results with a mobile robot will demonstrate the effectiveness of the discussed methods.
Seokjin Im 한국인터넷방송통신학회 2023 International Journal of Internet, Broadcasting an Vol.15 No.2
The portable mobile devices with high performance and high speed 5G network activate and explode the demands for ubiquitous information services that remove the limitations of time for the communication and places to request for the information. NN (Nearest Neighbor) search is one of the most important types of queries to be processed efficiently in the information services. Various indexes have been proposed to support efficient NN search in the wireless broadcast system. The indexes adopting Hilbert curve, grid partition or Voronoi diagram enable the clients to search for NN quickly in the wireless broadcast channel. It is necessary that an efficient means to evaluate the performances of various indexes. In this paper, we propose an open framework that can adopt a variety of indexing schemes and evaluate and compare the performances of them. The proposed framework is organized with open and flexible structure that can adopt hybrid indexing schemes extensible to Voronoi diagram as well as simple indexing schemes. With the implemented framework, we demonstrate the efficiency and scalability and flexibility of the proposed framework by evaluating various indexing schemes for NN query.
Seokjin Woo,Jongho Hong,Kyunghee Kim 한국재정학회(구 한국재정·공공경제학회) 2019 한국재정학회 학술대회 논문집 Vol.2019 No.4
In the last five years or so, air pollution and its negative impact on people’s health and productivity have become a serious national agenda in Korea. Among diverse air pollutants, the severity of particulate matter concentration is of utmost concern. The purpose of this study is to estimate the impact of air quality, measured by PM10, on the academic outcomes of students in South Korea. We utilized a unique data set of nationwide middle school exam results and PM concentration data collected in the nearest monitoring station to the corresponding school site. We addressed the potential endogeneity problem between unobservable characteristics and air quality. We employed a set of instrumental variables such as forest area, forest depth, and precipitation. We also estimated the fixed-effect models which consider the school, district, and time fixed effects. Our estimation results show that the students, who were exposed to bad air quality, tend to show poor academic performance. We also found that the adverse impact of PM10 was larger at the low tail of the academic distribution than the high tail of the distribution.
A Study on How to Use CHILDREN S PARKS according to the Change in Population Composition
Seokjin Jung,Changjun Kim,Hyangju Lee,Wonhyeon Lim J-INSTITUTE 2021 Public Value Vol.6 No.2
Purpose: Although children s parks are easily accessible from anywhere in the vicinity, there are many children s parks that children are ignoring. This study aims to provide a variety of activities to residents by utilizing these parks. In particular, these parks can be used as an alternative to crea ting a place for active play and effective exercise for the elderly who spend free time in an aging society. This study suggested using the existing children s play space as a complex play and exercise space with the elderly. Method: This paper selected 63 children s parks in Suseong-gu, Daegu Metropolitan City, and ana-lyzed them by dividing them into three residential types. Population change trends were investigated from 2005 to 2020, when children s parks were subdivided. This paper conducted a one -way ANOVA analysis to find out the difference by park facilities in children s parks. Post-hoc analysis was performed by the Scheffe test. To conduct the above statistical analysis, this paper used the Spss Statistics 21 sta-tistics program. Results: As a result of analyzing the change in the total population composition of Suseong-gu, where the children s park is located, the population of infants and children decreased, and the popula-tion of the elderly increased. The designation of children s parks has declined since the 1990s. It was found that the number of children by housing type decreased little by little every year. This paper ana-lyzed that the park area by residential type was the largest for children s parks located in mixed housing areas. In addition, it was found that many children s play facilities were installed in mixed residential areas. Conclusion: This study propose that if we increase the utilization rate of children s parks that lack user consideration and utilize children s parks within the living area, we can solve outdoor activities for the elderly according to the rapidly progressing aging age. In particular, if the children s park is made into a multi-purpose culture, sports, and amusement park that not only the elderly but also children and young people can use, it will be of great help to the utilization of the park.
Design of a Tri-Frequency DC-DC Buck Converter using On-Chip Compensation Circuit for EMI Reduction
Seokjin Kim,Daewoong Cho,Seungchan Park,Kwangsub Yoon 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
This Paper proposes 5M/3M/1㎒ triple frequency DC-DC Buck converter for wireless mobile system which is designed in 0.35 ㎛ CMOS standard process. Triple frequency operation can minimize EMI spectrum level by scattering EMI spectrum to three frequencies. Tri-mode Type Ⅲ compensation circuit which is on-chip designed is digitally controllable and reduces chip area. Proposed DC-DC converter has less than 1.03% output ripple voltage and maximum 84.7% power efficiency.