• Transactions on Electrical and Electronic Materials
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• v.6 no.5
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• pp.233-237
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• 2005

In the device structure of ITO/hole injection layer/N, N'-biphenyl-N, N'-bis-(1-naphenyl)-[1,1'-biphenyl]4,4'-diamine(NPB)/tris(8-hydroxyquinoline) aluminum$(Alq_3)/Al$, we investigated an effect of hole-injection materials (PTFE, PVK) on the electrical characteristics and efficiency of organic light-emitting diodes. A thermal evaporation was performed to make a thickness of NPB layer with a evaporation rate of $0.5\~1.0\;\AA/s$ in a base pressure of $5\times10^{-6}$ Torr. We measured current-voltage characteristics and efficiency with a thickness variation of hole-injection layer. The PTFE and PVK hole-injection layer improve a performance of the device in several aspects, such as good mechanical junction, reducing the operating voltage and energy band adjustment. Compared with the devices without a hole-injection layer, we have obtained that an optimal thickness of NPB was 20 nm in the device structure of $ITO/NPB/Alq_3/Al$. And using the PTFE or PVK hole-injection layer, the external quantum efficiencies of the devices were improved by $24.5\%\;and\;51.3\%$, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.125-128
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• 2011

This paper describes an efficient hardware implementation of HIGHT block cipher algorithm, which was approved as standard of cryptographic algorithm by KATS(Korean Agency for Technology and Standards) and ISO/IEC. The HIGHT algorithm, which is suitable for ubiquitous computing devices such as a sensor in USN or a RFID tag, encrypts a 64-bit data block with a 128-bit cipher key to make a 64-bit cipher text, and vice versa. For area-efficient and low-power implementation, we optimize round transform block and key scheduler to share hardware resources for encryption and decryption. The HIGHT64 core synthesized using a $0.35-{\mu}m$ CMOS cell library consists of 3,226 gates, and the estimated throughput is 150-Mbps with 80-MHz@2.5-V clock.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.36-47
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• 2009

There exists RFID reader-to reader frequency which can not recognize tag in dense reader nude because the interference causes low SIR. To solve this frequency, the many algorithms based on TDM have been proposed. But the most of existing algorithms not obtain the optimal time allocation but propose heuristic scheduling algorithm. In this paper, we apply game theory which deals with interest between players of game to RFID reader-to reader interference and analyze the time allocation problem of reader based on TDM in terms of cooperative game which the players bind agreements using Nash Bargaining Solution(NBS) and non-cooperative game which the players do not bind agreements using Nash Equilibrium(NE). The applied results show that in dense reader mode, NBS of cooperative game is superior to NE of non-cooperative game and present optimal time allocation in dense reader mode.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.51-60
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• 2009

In radio frequency identification(RFID) systems, when an RFID reader uses the same or adjacent frequency with neighbor readers, the interference between the readers may occur, which causes the reader collision and errors in tag recognition. In the previous study on RFID reader anti-collision, the techniques based on Frequency Division Mutiplex(FDM) or Time Division Multiplex(TDM) are proposed. However in these paper, the problem on the condition of RFID reader-to-reader interference considering the distance between interfering readers, frequency and operating time is not define exactly. In this paper, the interference effect is analyzed through RFID reader interference model considering the TDM and FDM, and the optimization problem is defined. To solve this, genetic-resource allocation technique is proposed. Therefore the optimal resource allocation applied RFID environment faithfully is accomplished.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.8 s.111
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• pp.753-759
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• 2006

Generally, the Wheeler cap method is used to measure the efficiency of small antennas. This method often gives an unreliable efficiency when the antenna has a complicated operating principle. However, if the high-order circuit model which more closely represents the input impedance of the antenna is used in Wheeler cap method, then more accurate efficiency can be achieved. In this paper, we propose a novel method that can build the high-order circuit model using transformer circuits with the genetic algorithm(GA). To efficiently reduce the searching space in the GA and improve the convergence of the GA process, we suggest a novel scheme that finds appropriate initial values. Finally we verify the proposed method by measuring the efficiency of some passive RFID tag antennas.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.3
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• pp.209-215
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• 2006

This paper was proposed Intelligent and wireless USN/RFID module system that can overcome disadvantage of existing RFID system with no sensing module and wire communication. The proposed USN/RFID system was designed and fabricated. After fabricating new system, we analyzed the characteristics of USN/RFID module. After design VCO block that is point circuit to develop next generation system one chip of RFID system, we were carried out simulation and verified the validity. this paper was showed that VCO system was enough usable in wireless network module. USN/RFID Reader module shows superior result that validity awareness distance corresponds to 30 M in the case of USN and to 5 M in RFID Reader's case and 900 MHz of commercial frequency does practical use enoughly in range of high frequency. The USN/RFID Reader module is considered to act big role to Ubiqitous industry offering computing surrounding of new concept that is intelligence type service and that was associated to real time location system(RTLS), environment improvement/supervision, national defense, traffic administration etc.

• Journal of Biosystems Engineering
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• v.37 no.6
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• pp.373-384
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• 2012

Purpose: In EU, the animal welfare regulations are strengthening. Also, in Korea, for strengthening of animal protection laws, animal welfare farm certification scheme is being prepared to enforce. To get the certification of animal welfare farm, especially for sows, individual specific feeding in sow group is necessary in accordance with the animal welfare regulation. Also, liquid feeding is reported to be more effective for farrowing as well as dry sow. Therefore, in this study, a electronic liquid sow feeder using RFID which could be fed to farrowing sow simultaneously is developed. Methods : We manufactured a prototype of appropriate elements which were evaluated in the preliminary test for selecting RFID tag, supply pump, mixing type, etc. With the prototype, the performance test for liquid feeding gilt was done in group raising training barn. Results : The performance test result shows the C.V.(coefficient of variation) of liquid mixing and feeding is 0.77~1.97% and 2.4~5.3%, respectively, which means the system could feed sows uniformly. The feeding time of pneumatically activated ball valve is 2 seconds per 0.9 kg of liquid feed. The eating time for gilt were 65 seconds in average. Conclusions : The prototype could feed sow uniformly, and deliver the liquid feed 9 times for a sow continuously. Also, total eating time for a sow was 18 minutes in one visit to the prototype of feeding station.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.85-94
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• 2008

When an RFID reader uses the same frequency or adjacent frequency with neighbor readers, the interference might occur. These interferences cause the RFID reader collision and errors during tag recognition. Therefore, the international standard for RFID and some papers proposed the methods to reduce the reader collision. The reader interference is closely related to the distance between the readers haying interference and used frequency band. In the previous RFID reader anti-collision algorithms, the location of readers inducing interference which is closely related to interference of readers is not considered. Only the reader collision is tried to reduce through frequency transfer after collisions occur or modification of frame size in relation to collision probability based a TDM(Time Division Multiplex). In this paper, the genetic algorithm using two-dimensional chromosome which reflect readers' location is proposed to prevent reader collision effectively. By executing evolutionary operation with two-dimensional chromosome, the location information having influence on reader interference can be used. The repair operation in the proposed algorithm makes all reader stably recognize their tags.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.581-584
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• 2006

Cellular phones have been popularized and some of them even have access to the Internet. But the utilization of mobile phones has not been for education but only focused on particular services due to the text-based low capacity. This thesis proposes a multimedia education system using cell phones with SMIL. We can decrease the size of the parser and refute the resources of CPU by designing SMIL tag only, which is needed for multimedia education. In addition, the macro method for producing information for lectures will make possible decreased transmission quantity of multimedia contents and increased transmission efficiency. This will lead to overcoming the matter of insufficient CPU and memory, which is common to most mobile phone terminals.

• Journal of Intelligence and Information Systems
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• v.11 no.2
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• pp.105-121
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• 2005

To realize a ubiquitous logistics management system using the smart object of Electronic Product Code(EPC) enabled RFID tag, the design and management of RFID Information Service is very important. RFID Information Service searches, transfers and responds to the other's PML request, but Physical Markup Language (PML) data management between trading system elements has issues of standardization of PML data description and processing, and problems of data traffic and communication time overload because of the innate distributed characteristics. As a complementary study, this research analyzes the usage patterns and data types of PML. On that analysis we provide a design of the distributed RFID Information Service architecture of PML data management that is using DB middleware. Standalone and Integrated type of RFID IS were proposed.