• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.589-591
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• 2004

In this paper, we developed a laser distance measurement(LDM) system based on DSP. We applied PPD(Pulsed Phase Detection) algorithm to the LDM system. The PPD algorithm calculate the distance from the LDM system to the object by using phase detection. Reference waveform at a fixed frequency is sampled by both the inner-loop and outer-loop pulse signal. The LDM system detects the difference of phase between the sampled signals. We obtained an accuracy of ${\sigma}=25.5mm$ from the LDM system.

• Journal of Creative Information Culture
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• v.7 no.3
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• pp.167-176
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• 2021

In this paper, from the pervious studies investigating the current status of distance learning due to COVID-19, the needs of teachers for effective distance learning were analyzed. As a result, it was found that support related to distance learning contents was necessary. Specifically, it is necessary to establish a platform specialized for content production for distance learning, expand teacher training related to content production and operation, and improve the copyright system related to content production. In addition, since distance classes differ from those of back-to-school classes in system and characteristics, it is necessary to supplement the institutional aspects for distance classes. It is judged that it is necessary to support the evaluation method suitable for distance learning, the authority to operate the curriculum, and the learning management system. In addition, it was analyzed that it is necessary to expand the infrastructure for distance learning, and a structure and platform for self-directed improvement programs and self-directed distance learning are needed to prevent the learning gap problem from repeating due to distance learning.

• Journal of Information Processing Systems
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• v.16 no.5
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• pp.1158-1168
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• 2020

The distance vector-hop wireless sensor node location method is one of typical range-free location methods. In distance vector-hop location method, if a wireless node A can directly communicate with wireless sensor network nodes B and C at its communication range, the hop count from wireless sensor nodes A to B is considered to be the same as that form wireless sensor nodes A to C. However, the real distance between wireless sensor nodes A and B may be dissimilar to that between wireless sensor nodes A and C. Therefore, there may be a discrepancy between the real distance and the estimated hop count distance, and this will affect wireless sensor node location error of distance vector-hop method. To overcome this problem, it proposes a wireless sensor network node location method by modifying the method of distance estimation in the distance vector-hop method. Firstly, we set three different communication powers for each node. Different hop counts correspond to different communication powers; and so this makes the corresponding relationship between the real distance and hop count more accurate, and also reduces the distance error between the real and estimated distance in wireless sensor network. Secondly, distance difference between the estimated distance between wireless sensor network anchor nodes and their corresponding real distance is computed. The average value of distance errors that is computed in the second step is used to modify the estimated distance from the wireless sensor network anchor node to the unknown sensor node. The improved node location method has smaller node location error than the distance vector-hop algorithm and other improved location methods, which is proved by simulations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.747-750
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• 1995

As railway trains run faster high performance braking system are necessary because more energy needs to be dissipated due to increased kinetic energy. In this work a portable computer based prediction system for emergency braking distance has been developed. The algorithm for the system is based on braking theory and empirical results of actual braking test. The computer is connected to the sensors to measure the velocity and the braking pressure in real train. It is expected that this system will be utilized to predict emergency braking distance during actual operation of the train

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.729-732
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• 1999

In this paper. we propose a system model and the associated control method for long distance connection using the High Performance Serial Bus, IEEE 1394. Though IEEE 1394-1995 Standard has connection distance limit of 4.5m, our proposed system can extend the limit further even without degrading network performance. And the current systems using IEEE 1394 don't have to make any change to use the proposed system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.848-860
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• 1994

Generally, to get the minimum distance between two arbitrary shapes that are composed of circular arcs and lines, we must calculate distances for all the possible pairs of the components from two given shapes. In this paper, we propose an efficient method for the minimum distance problem between two shapes by using their structural features after extracting the reduced component lists which are essential to calculate the minimum distance considering the relationship of shape location. Even though the reduced component lists may contain all the components of the shapes in the worst case, in the average we can reduce the required computation much by using the reduced component lists. This method may be efectively applied to calculating the minimum distance between two shapes which are generated by the CAD tool, like in the nesting system.

• Journal of the Korea Society of Computer and Information
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• v.26 no.7
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• pp.119-126
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• 2021

Due to the prolonged COVID-19, distance lectures are expected to continue for a considerable period of time. Research on factors affecting distance lecture quality and learner satisfaction is essential. The purpose of this study is to examine the relationship between distance lecture quality (system quality, information quality, service quality, interaction quality), self-efficacy, and learner satisfaction, and to suggest theoretical and practical implications for the effective operation of distance lectures. A survey was conducted for university students taking distance lectures, and 197 questionnaires were used for empirical analysis. The collected data were analyzed by SPSS 25.0 and AMOS 21.0. As a result; First, distance lecture quality (system quality, information quality, service quality, interaction quality) was found to have a positive effect on self-efficacy. Second, distance lecture quality (system quality, information quality, service quality, interaction quality) was found to have a positive effect on learner satisfaction. Third, self-efficacy was found to have a positive effect on learner satisfaction. Based on the analysis results, the implications and limitations of this study are presented.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.711-717
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• 2007

Location information will become increasingly important for future Pervasive Computing applications. Location tracking system of a moving device can be classified into two types of architectures: an active mobile architecture and a passive mobile architecture. In the former, a mobile device actively transmits signals for estimating distances to listeners. In the latter, a mobile device listens signals from beacons passively. Although the passive architecture such as Cricket location system is inexpensive, easy to set up, and safe, it is less precise than the active one. In this paper, we present a passive location system using Cricket Mote sensors which use RF and ultrasonic signals to estimate distances. In order to improve accuracy of the passive system, the transmission speed of ultrasound was compensated according to air temperature at the moment. Upper and lower bounds of a distance estimation were set up through measuring minimum and maximum distances that ultrasonic signal can reach to. Distance estimations beyond the upper and the lower bounds were filtered off as errors in our scheme. With collecting distance estimation data at various locations and comparing each distance estimation with real distance respectively, we proposed an equation to compensate the deviation at each point. Equations for proposed algorithm were derived to calculate relative coordinates of a moving device. At indoor and outdoor tests, average location error and average location tracking period were 3.5 cm and 0.5 second, respectively, which outperformed Cricket location system of MIT.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.14 no.2
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• pp.75-84
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• 2010

Objectives: The objective of the current study is to determine whether an ultrasound device system is adequate for measuring distance from Sangwan (CV13) to pancreas. Methods: We recruited 3 healthy young male subjects and 2 sonographers. The each sonographer measured vertical shortest distance from CV13 to pancreas with a ultrasound device three times in random order. Because the total variation could be divided into repeatability, reproducibility and subject-to-subject variation in Gage R&R method, we compared the sources of variation associated with the measurement system with an analysis of variance model. Results & Conclusions: Number of distinct categories is calculated on the basis of standard deviation of subject-to-subject divided by standard deviation of total Gage R&R. If the number of categories is five or more, the measurement system may be acceptable for the analysis of the process. The number of distinct categories of the ultrasound device system for measuring distance from CV13 to pancreas was 6.29. So we concluded that repeatability and reproducibility of the ultrasound device system for measuring distance from CV13 to pancreas was acceptable.

• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.462-470
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• 2009

As the learning space has expanded, the distance education has become a recent scholarship in teaching-learning method, and also a great type of media, technologies and strategies to support distance education are attracting a fair amount of attention. However in order to manage a distance education system, it is necessary to be endowed user with technical ability and operational expenses. On the other hand, although a web-based system that makes simple may cut cost, it is difficult to analyze learner's behaviors. Therefore, in this paper, we developed a interactive distance system based on individualized questioning, which relies upon learner's knowledge state and applies a efficient individualized learning method. Additionally, this study is instrument to reduce users' technical ability and operational expenses.