• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2684-2690
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• 2009

The existing mobile learning service is the method that provides data packets in real time. It has some problems of much data packet cost and delay to provide the mobile learning service. In this paper, to solve the problems, we suggest to implementation of the mobile learning system of the new method using serial communication.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.8
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• pp.836-844
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• 1991

PLC(programmable logic controller) system is widely used for the control of factory. PLC system receives ladder diagram which is drawn by the user to implement hardware logic, converts the ladder diagram into sequence program which is executable in the PLC system, and executes the sequence program indefinitely unless user breaks. The sequence program processes the data of on/off signal, and endures 1 scan delay and missing of pulse-type signal shorter than a scan time. So, data dependency doesn't exist. By applying theis characteristics to multiprocessor architecture, we design parellel PLC functionally and evaluate performance upgrade. Parallel PLC consists of central processing module, N general processing unit, and a shared memory by master-slave type. Each module executes allocated sequence program by the control of central processing module. We can expect performance upgrade by parallel processing, and reliability by relocation of sequence program when error occurs in processing module.

• Journal of The Korean Association For Science Education
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• v.11 no.2
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• pp.133-142
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• 1991

The purpose of this study is to develop a data base system for the information on research and development of science education. As the first step of this study and development, a classification system for the research and development materials was devised after discussing the process of science education and the research and development of science education. The classification system has nine main categories : 1. area, 2. subject, 3. behavior, 4. skill, 5. support, 6. type, 7. materials, 8. language, and 9. the others, each of which has one or two levels of subcategory. This classification system was revised and supplemented through the theoretical analysis by speci.diSts and the practical classification of master's theses and doctoral dissertations from the Department of Science Education, Seoul National University. But it still needs more revision and enlargement through the continuous application and analysis.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.4 no.2
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• pp.21-58
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• 2009

The Purpose of this study is working out of the scientific-theoretical and practical recommendations directed on perfection of strategic planning of development of the enterprises of mining and gold mining branch. The methodological basis of research is based on the economic theory developed by a domestic and foreign science. At processing, generalisation and a writing of materials of the master's thesis following methods were applied: - supervision, - comparison, - the analysis and synthesis, - methods of an induction and deduction, - statistical groupings, - average and relative sizes, - the system approach. Finally, the theoretical and practical importance of this research consists that results of research will allow generating a basis of statement of effective system of strategic planning of a long-term sustainable development of the gold mining enterprises reducing risk of acceptance of inefficient strategic decisions. I would like to express many thanks to the NGO "Semey- My Home" and "EastGeoResources" LLP for their help and support in providing the data collection and data analysis stages of my research from 2006.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.2
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• pp.56-63
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• 2001

The objective of this research is to develop a measurement error compensation method for On-Machine Measurement (OMM) process based on a closed-loop configuration. Geometric errors of vertical machining center are measured using ball-bar system, and probing errors are measured using master ball. The errors are represented using homogeneous trans-formation matrices and the closed-loop configuration method is applied to calculate 3-dimensional errors. To verify the effectiveness of the method proposed in this research, compensated results are compared to the data using CMM process, and the results are analyzed. The results show the proposed method can be applied in OMM process to make the measured data more reliable.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.744-749
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• 2005

The train configuration is based on one unit like basic 4 cars to multiple unit operation. Each unit has unique node such as train formation number. Some equipments(TC, CC) of TCMS are connected to the master TC through the LonWorks network. When the train is consist of multiple unit, TCMS has to implement quick network for data communication overall train. But a variable time delay is generated when it is performed communication with point to point type using train formation number. In this paper we propose new method to know the node information of adjacent unit. that is to add digital input signals notifying cab direction at any cabin. Also, we provide the optimized screen design that all collected information via network is displayed by each unit.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.101-101
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• 2000

MSC(Multispectral Camera), which will be a unique payload on KOMPSAT-II, is designed to collect panchromatic and multi-spectral imagery with a ground sample distance of 1m and a swath width of 15km at 685km altitude in sun-synchronous orbit. The instrument is designed to have an orbit operation duty cycle of 20% over the mission life time of 3 years. MSC electronics consists of three main subsystems; PMU(Payload Management Unit), CEU(Camera Electronics Unit) and PDTS(Payload Data Transmission Subsystem). PMU performs all the interface between spacecraft and MSC, and manages all the other subsystems by sending commands to them and receiving telemetry from them with software protocol through RS-422 interface. CEU controls FPA(Focal Plane Assembly) which contains TDI(Timc Delay Integration) CCD(Charge Coupled Device) and its clock drivers. PMU provides a Master Clock to synchronize panchromatic and multispectral camera. PDTS performs compression, storage and encryption of image data and transmits them to the ground station through x-band.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.132-140
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• 1999

This paper treats the estimation of human impedance and their application to human-robot collaboration work. Initially, we perform an experiment at which the human becomes a slave and the robot behaves like a master having F/T sensor on its end. The human impedance expressed in terms of mass, damping, and stiffness properties are estimated based on the force data measured by F/T sensor and the commanded position data of the robot. To show the effectiveness of the estimated human impedance, we perform the second experiment at which the roles of the human and the robot are reversed. It is shown that the robot using the estimated human impedance follows the trajectory commanded by human very smoothly.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.4
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• pp.57-63
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• 2003

Machining information such as form accuracy and surface roughness is an important factor for manufacturing precise parts. To this regard, OMM (On the Machine Measurement) has been researched for last several decades to alternate CMM (Coordinate Measurement Machine) process. In this research, the OMM system with a laser displacement sensor was developed for measuring form accuracy and surface roughness of the machined workpiece on the machine tool. The surface roughness was estimated comparing the sensory signal with the reference data measured from master specimen. Also, form accuracy was determined from the moving averaged raw data. In addition, the geometric error map constructed beforehand using the geometric errors of the machine tool was used to compensate the obtained form accuracy. The overall performance was compared with CMM result, and verified the feasibility of the measurement system.

• Journal of Information Technology Applications and Management
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• v.24 no.1
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• pp.143-156
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• 2017

As the number of people going aboard is growing and technology is developed rapidly, Chinese customers are also getting better understanding about overseas products, and they hope to get less expensive and better ones, which leads to the growth of the online overseas purchasing agent service. In this paper, we tried to analyze the factors that impact the usage of online overseas purchasing agent service using the survey data. We found that customers pursue not only the reasonable prices but also enjoyment of shopping in the online overseas purchasing agent service. In addition, product scarcity and the information literacy of a customer were positively related with the use of online overseas purchasing agent service.