• ETRI Journal
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• v.28 no.2
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• pp.250-252
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• 2006

In this letter, a discrete state, discrete time chaotic pseudo random number generator (CPRNG) is presented for stream ciphering of text, audio, or image data. The CPRNG is treated as a finite state machine, and its state is modulated according to the input bit sequence of the signal to be encrypted. The modulated state sequence obtained can be transmitted as a spread spectrum or encrypted data.

• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.97-100
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• 2009

홈네트워크 환경에서 정보가전기기를 제어하는데 PLC(전력선통신)나 IR컬트롤러가 사용된다. PLC의 경우 가전기기동작이 명확하지만 IR컨트롤러 같은 경우에는 방향이나 여러 조건에 따라 가전기기동작이 불분명하여 사용자의 명령대로 수행되지 못하는 경우가 발생한다. 본 논문에서는 이러한 상황을 해결하기 위해 가전기가의 상태를 모니터링하여 사용자에게 알려주는 방법을 제안하였다. 동작 상태와 대기 상태의 전류량이 다른점을 이용하여 동작 여부를 판별한다. 제안된 방법을 사용하면 IR 컨트롤러로 동작하는 가전기기의 상태 신뢰성 을 높일 수 있다.

• Transactions on Electrical and Electronic Materials
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• v.12 no.2
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• pp.43-50
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• 2011

Carbon-nanotube metal oxide semiconductor field effect transistor (CN-MOSFET) is a promising future device candidate. The electrical characteristics of 16 nm N-type CN-MOSFETs are explored in this paper. The optimum N-type CN-MOSFET device profiles with different number of tubes are identified for achieving the highest on-state to off-state current ratio ($I_{on}/I_{off}$). The influence of substrate voltage on device performance is also investigated in this paper. Tradeoffs between subthreshold leakage current and overall switch quality are evaluated with different substrate bias voltages. Technology development guidelines for achieving high-speed, low-leakage, area efficient, and manufacturable carbon nanotube integrated circuits are provided.

• Journal of Biosystems Engineering
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• v.33 no.5
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• pp.333-339
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• 2008

The purpose of this study was to develop a portable electronic nose system to measure volatile components of agricultural and food products. Also, a graphical operating software to control the electronic nose system and to acquire signals through the Internet was developed. An array of five commercial metal oxide gas sensors was used to detect various volatile gas components of target samples. Transient and steady state signals were analyzed to extract variables related to sample states, To find optimal operating conditions of the system, several experiments were performed with different gas chambers, vacuum pumps, gas sampling temperatures, and sample container sizes. The patterns of gas sensor signals were analysed to find effects of the various conditions.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.2
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• pp.95-105
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• 2001

In this paper, in order to control uncertain chaotic system, an adaptive fuzzy control(AFC) scheme is developed for the multi-input/multi-output plants represented by the Takagi-Sugeno(T-S) fuzzy models. The proposed AFC scheme provides robust tracking of a desired signal for the T-S fuzzy systems with uncertain parameters. The developed control law and adaptive law guarantee the boundedness of all signals in the closed-loop system. In addition, the chaotic state tracks the state of the stable reference model(SRM) asymptotically with time for any bounded reference input signal. The suggested AFC design technique is applied for the control of an uncertain Lorenz system based on T-S fuzzy model such as stabilization, synchronization and chaotic model following control(CMFC).

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.3
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• pp.140-146
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• 2003

In this paper, we suggested electronic ballast with the half bridge inverter for the automotive HID lamp. The electronic ballast for the automotive HID lamp should be supplied by the low-frequency square wave avoiding the acoustic resonance. When the HID lamp is hot state, the electronic ballast should supply the sufficient current to the take over to the lamp at the re-strike ignition state for a few milli-second. We have introduced the new take-over current control method that could have control operating frequency and minimize circuits to the take over current circuits.

• Transactions on Electrical and Electronic Materials
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• v.9 no.1
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• pp.24-27
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• 2008

ZnO has intensively attracted interest for the next generation of short wavelength LEDs and semiconductor lasers. However, for the development and application of the devices based on this material, the fabrication of p-type ZnO thin films is pivotal. Generally, the process of preparation of ZnO is unavoidably accompanied by the natural donor ions such as interstitial Zn ions and oxygen vacancy ions that show n-type electrical property and make fabrication of p-type ZnO to be a hard problem. On this study, to realize stable high-quality p-type ZnO thin films, the undoped ZnO thin films were diffused with P in vapor state. The ZnO:P thin films showed high-quality p-type properties electrically and optically.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.163-165
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• 2004

A low-cost electronic ballast using a conventional HID controller IC is proposed. The proposed ballast consists of high frequency DC-DC converter, low frequency DC-AC inverter, and igniter circuit. This ballast shows hot-restrike, suitable operation at each stage of various lamp state and stable operation in steady-state.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.7
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• pp.370-376
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• 2004

The metal halide lamps are now widely used in the application and commercial lighting due to their attracting properties such as good color rendering and high efficiency. But, they have the serious problem of acoustic resonance for high frequency operation and they need the high voltage to ignite. So, they have not been applied to indoors. Over the past few years, a considerable number of studies have been conducted on the electronic ballast together with hot restarting and resonance phenomenon. But, Very few attempts have been made with the adaptive ignition method according to the lamp state. In this paper, electronic ballast is proposed for metal halide lamps with an igniter for adaptive ignition. The proposed electronic ballast can generate different ignition voltages according to the arc tube state.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1072-1079
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• 2014

This paper introduces a coordinated droop control for the stand-alone DC micro-grid, which is composed of photo-voltaic generator, wind power generator, engine generator, and battery storage with SOC (state of charge) management system. The operation of stand-alone DC micro-grid with the coordinated droop control was analyzed with computer simulation. Based on simulation results, a hardware simulator was built and tested to analyze the performance of proposed system. The developed simulation model and hardware simulator can be utilized to design the actual stand-alone DC micro-grid and to analyze its performance. The coordinated droop control can improve the reliability and efficiency of the stand-alone DC micro-grid.