• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.735-737
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• 2017

An Off grid or remote solar electric systems are an energy supply to our home or to our companies without the utility of Grid at all. Off grid solar systems are very important for those who live in remote locations especially for developing countries where getting the electric grid is extremely expensive, inconvenient or for those who doesn't need to pay a monthly bill with the electric bill in general. The main critical components of any solar power system or renewable energy harvesting systems are the energy storage systems and its charge controller system. Energy storage systems are the essential integral part of a solar energy harvesting system and in general for all renewable energy harvesting systems. To provide an optimal solution of both high power density and high energy density at the same time we have to use hybrid energy storage systems (HESS), that combine two or more energy storage technologies with complementary characteristics. In this present work, design and simulation we use two storage systems supercapacitor for high power density and lithium based battery for high energy density. Here the system incorporates fast-response supercapacitors to provide power to manage solar smoothing and uses a battery for load shifting. On this paper discuss that the total energy throughout of the battery is much reduced and the typical thermal stresses caused by high discharge rate responses are mitigated by integrating supercapacitors with the battery storage system. In addition of the above discussion the off grid solar electric energy harvesting presented in this research paper includes battery and supercapacitor management system, MPPT (maximum power point tracking) system and back/boost convertors. On this present work the entire model of off grid electric energy harvesting system and all other functional blocks of that system is implemented in MATLAB Simulink.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.896-897
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• 2013

In recent years, logistics tracking Device using GSM & WCDMA to improve logistics efficiency are being extensively researched. The purpose of this paper is to examine the performance development antenna usable cargo container security transport. Antenna developed by study were optimized to match logistics environment apply to GSM & WCDMA dual frequency for monitering system. The measure of antenna have confirmation VSWR is 3:1 measured in return loss -10dB. Reliability of this antenna has been verified about GSM & WCDMA through test-operation between the south korea and Russia.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6A
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• pp.627-633
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• 2006

In spite of many advantages of Meteor Burst Communications(MBC) on its transmission channel, the fact that its duty rate is less than 10 percents is a considerable deficiency of MBC. To overcome with this deficiency without paying large cost, we use a direct sequence(DS) simple reception system. This method doesn't need to add the components for acquisition or tracking the signal so that it keeps the cost efficiency of the MBC. But it has a disadvantage that its duty rate shows a large decline by noise. For this problem we adopt the proposed system applying a transversal filter circuit. The improvement by this method is more significant when the received signal is weak Simulation results show as t1 is 100ms, then the burst length would be increased by 35% when the initial value of the received signal power increases by 3 dB, t2 is 135ms. If the power increases by 6dB the burst length would be 170ms thus increased by 70%, which shows a great enhancement. Suppose now that t1 is 50ms and the power is increased by 3dB, then t2 would be increased by 70% to 85ms, and increasing the power by 6dB it would be increased by 130% to 115ms.

• Journal of Digital Contents Society
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• v.18 no.5
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• pp.977-982
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• 2017

In this paper, we propose an AR system which enables monitoring and managing of the operation process of the construction site. In case of the conventional construction managing system, a worker takes several images of the construction site and sends them directly to the supervisory headquarter, which manages the progress of the construction process and checks weather the construction is achieved according to the architectural design or not. Due to the nature of the offline process, the conventional management system has time and monetary constraints, and there exists a disadvantage that it is impossible to make quick decision-making and real-time communication with the work site. In order to minimize these disadvantages, we proposes an AR real-time construction monitoring/management system. In particular, we aim to developed a system based on mobile device so that it can maximize usability. The efficiency of the proposed system is verified through several experiments and implementation results.

• Journal of the Korean Solar Energy Society
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• v.30 no.6
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• pp.28-33
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• 2010

Solar collectors to be applied are mainly flat-plate or vacuum tube collector which is used for hot water supply of house because of low heat value and low temperature. There are a necessity to expand applicable scope of solar collector into the industrial process heat source and air conditioner for coping with renewable energy policy of government and industrial trend. This study is to analysis the performance of PTC solar collector of concentrating type and flat-plate of non-concentrating. For this, temperature difference and heating value as insolation of air outside is measured from these two collectors mounted on 2-axial solar tracking system. It is investigated that temperature profile obtained from PTC solar collector is uniform and collecting heat per unit area is 6.8kcal/$m^2$ min which is about 3 times with compare to flat-plate collector of 2kcal/$m^2$min. Also the amount of heat to be produced from PTC solar collector is 3 Mcal/$m^2$ which is about 2 times with compare to flat-plate collector of 1.5Mcal/$m^2$ as a result of operating these two collectors during one month. Therefore, it is obtained that heat collecting performance of PTC solar collector is superior to flat-plate.

• Journal of the Korean Solar Energy Society
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• v.33 no.5
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• pp.69-75
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• 2013

To increase the efficiency of the photovoltaic, almost photovoltaic appliances are controlled by Maximum Power Point Tracking(MPPT). Existing most of the PV MPPT techniques have used power which multiplies sensed output current and voltage of the solar cell. However, these algorithms are unnecessarily complicated and too expensive for small and compact system. The other hand, the proposed MPPT technique is only one sensing of the MPPT converter's output current, so there is no need to insert another sensors of battery side. Therefore, this algorithm is simpler compared to the traditional approach and is suitable for low power solar system. Further, the novel proper charge/discharge algorithm for the battery with PV MPPT is developed. In this algorithm, there is CC battery charge mode and load discharge mode of the PV cell & battery dual. Also we design current control to regulate allowable current during the battery charging. The proposed algorithm will be applicable to battery included solar cell applications like solar lantern and solar remote control car. Finally, the proposed method has been verified with computer simulation.

• Journal of the Korea Society of Computer and Information
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• v.16 no.11
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• pp.163-171
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• 2011

Because RFID systems use radio frequency, they have many security problems such as eavesdropping, location tracking, spoofing attack and replay attack. So, many mutual authentication protocols and cryptography methods for RFID systems have been proposed in order to solve security problems, but previous proposed protocols using AES(Advanced Encryption Standard) have fixed key problem and security problems. In this paper, we analyze security of proposed protocols and propose our protocol using OTP(One-Time Pad) and AES to solve security problems and to reduce hardware overhead and operation. Our protocol encrypts data transferred between RFID reader and tag, and accomplishes mutual authentication by one time random number to generate in RFID reader. In addition, this paper presents that our protocol has higher security and efficiency in computation volume and process than researched protocols and S.Oh's Protocol. Therefore, our protocol is secure against various attacks and suitable for lightweight RFID tag system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.2
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• pp.126-136
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• 2020

Recently, unmanned aerial vehicles (UAV, Drone) are highly regarded for their potential in the agricultural field, and research and development are actively conducted for various purposes. Therefore, in this study, to present a framework for tracking research trends in UAV use in the agricultural field, we secured a keyword search strategy and analyzed social network, a methodology used to analyze recent research trends or technological trends as an analysis model applied. This study consists of three stages. As a first step in data acquisition, search terms and search formulas were developed for experts in accordance with the Keyword Search Strategy. Data collection was conducted based on completed search terms and search expressions. As a second step, frequency analysis was conducted by country, academic field, and journal based on the number of thesis presentations. Finally, social network analysis was performed. The analysis used the open source programming language 'Python'. Thanks to the efficiency and convenience of unmanned aerial vehicles, this field is growing rapidly and China and the United States are leading global research. Korea ranked 18th, and bold investment in this field is needed to advance agriculture. The results of this study's analysis could be used as important information in government policy making.

• Journal of the Korea Society of Computer and Information
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• v.3 no.4
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• pp.174-192
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• 1998

These day in the Quality Assurance System, it required that computer system is able to utilize SQC and ISO 9000 series, just then. However. because SQC is necessary to special branch of statistical experience, it is very hard to use and have a bound in that apply to practical business. Therefor in this paper, we proposed the software system which is control, at the same time, SQC and ISO 9000 series, in addition to avail without statistical knowledge. For the shake of this point, the substance of this study is largely separated dual part that ISO 9000 system for which is limited to use design of basic system, test, experiment, tracking incongruent part, analysis condemned goofs, and SQC system for which is to limited to use control chart, estimate, statistical testing, design of experiment(DOE) which used to commonly in Quality Control System. Expected efficiency of this paper is to set Qualify Management System, transfer qualify consciousness, satisfy the customer, increase reliability, in particular, it is expected that it is very useful to minor enterprises of manufacturing-centered.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.10
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• pp.959-965
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• 2014

This paper summarizes the previous research results of fundamental investigation done in SNU on the wireless power transfer. Firstly, the physical limitation of a wireless power transfer using the spherical modes is reviewed. It is found that wireless power transfer depends only on the radiation efficiency of the antennas and the distance between two antennas involved. Secondly, we review the characteristics of WPTS with different sources and compare the performance differences of WPTS according to the source type. In addition, the method for efficient WPTS is suggested when the distance between antennas is varied. Finally, by using the time domain solution of the coupled mode equation, we present an analytic formula which can be used to differentiate Inductive Coupling(IC) and Magnetic Resonance Coupling(MAC) which are often used ambiguously in wireless power transfer system.