• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.162-168
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• 2009

This thesis is based on the research and experiment of the optimal efficiency generation of electric power. The research and experiment were conducted to search the optimal generation of electric power from a specific amount of solar energy from Photovoltaic Power System with a solar position tracker were used. The changes in the array angles and spacing of the PV Module were also taken into account as well. Here are the findings and the conclusions. First of all, based on experiment using the various anglers, the efficiency generation of electric power increased to a maximum of approximately $12{\sim}17$[%] more at the PV module inclination angle of 30[$^{\circ}$] than at the inclination angles of 20[$^{\circ}$] and 40[$^{\circ}$]. As a result, we have found that installing the PV module inclination at the angle of 30[$^{\circ}$] brought about the most efficient conversion effect of the Photovoltaic Power System. But, when the solar cell is installed on a roof or rooftop where snow builds up, it is the most appropriate to install the solar energy at an 35[$^{\circ}$] angle so that snow slides down and not build up on the module.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.9
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• pp.985-991
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• 2008

This paper presents a novel balanced mixer receiver front-end design based on a metamaterial structure applicable to differential-/common-mode excitation. This metamaterial structure functions as a leaky-wave antenna and provides in-trinsic common-mode suppression. Low LO leakage and high RF to LO isolation are achieved without additional filters for LO and RF paths. The metamaterial is based on a unit-cell which under a differential-mode excitation behaves like a composite right/left-handed(CRLH) metamaterial. In contrast, the metamaterial unit-cell is below cut-off under a common-mode excitation. Experimental results are used to verify the proposed metamaterial's differential-/common-mode characteristics. The metamaterial is integrated with a balanced mixer design resulting in an operation frequency range of $1.96{\sim}2.40$ GHz with an optimum mixer conversion loss of 21.1 dB at 2,4 GHz.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.5
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• pp.43-50
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• 2002

To improve the current waveform of diode rectifiers, we propose a new operating principle for the voltage -doubler diode rectifiers. In the conventional voltage-doubler rectifier circuit, relatively large capacitors are used to boost the output voltage, while the proposed circuit uses smaller ones and a small reactor not to boost the output voltage but improve the input current waveform. A high input power factor of 97[%] and an efficiency of 98[%] are also obtained. The harmonic guide lines of proposed rectifier is no interfered with inverter switching, resulting in a simple, reliable and low-cost ac-to dc converters in comparison with the boost-type current-improving circuits.It compared conventional pulse-widthmodulated(PWM)inverter with half pulse-widthmodulated (HPWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switchingloss and holding over-shooting.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.4
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• pp.26-33
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• 2010

This paper presents a multi-channel capacitive touch sensing unit for SoC applications. This unit includes a simple common processing unit and switch array to detect the touch sensing input by capacitive-time(C-T) conversion method. This touch sensor ASIC is designed based on the Capacitive-Time(C-T) conversion method to have advantages of small current and chip area, and the minimum resolution of the unit is 41 fF per count with the built-in sensing oscillator, LDO regulator and $I^2C$ for no additional external components. This unit is implemented in 0.18 um CMOS process with dual supply voltage of 1.8 V and 3.3 V. The total power consumption of the unit is 60 uA and the area is 0.26 $mm^2$.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.5
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• pp.12-19
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• 2007

This paper presents an ASIP(Application Specific Instruction Set Processor) for implementation of H.264/AVC, called VSIP(Video Specific Instruction-set Processor). The proposed VSIP has novel instructions and optimized hardware architectures for specific applications, such as intra prediction, in-loop deblocking filter, integer transform, etc. Moreover, VSIP has hardware accelerators for computation intensive parts in video signal processing, such as inter prediction and entropy coding. The VSIP has much smaller area and can dramatically reduce the number of memory access compared with commercial DSP chips, which result in low power consumption. The proposed VSIP can efficiently perform in real-time video processing and it can support various profiles and standards.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.2
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• pp.78-83
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• 2019

Sounds based machine fault diagnosis recovers all the studies that aim to detect automatically abnormal sound on machines using the acoustic emission by these machines. Conventional methods that use mathematical models have been found inaccurate because of the complexity of the industry machinery systems and the obvious existence of nonlinear factors such as noises. Therefore, any fault diagnosis issue can be treated as a pattern recognition problem. We propose here an automatic fault diagnosis method of hand drills using discrete wavelet transform(DWT) and pattern recognition techniques such as artificial neural networks(ANN). We first conduct a filtering analysis based on DWT. The power spectral density(PSD) is performed on the wavelet subband except for the highest and lowest low frequency subband. The PSD of the wavelet coefficients are extracted as our features for classifier based on ANN the pattern recognition part. The results show that the proposed method can be effectively used not only to detect defects but also to various automatic diagnosis system based on sound.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.350-357
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• 2005

DSRC provides high speed radio link between Road Side Equipment and On-Board Equipment within the narrow communication area. In this paper, a 5.8 GHz up-conversion mixer for DSRC communication system was designed and fabricated using 0.8 m SiGe HBT process technology and IF/LO/RF matching circuits, IF/LO input balun circuits, and RP output balun circuit were all integrated on chip. The chip size of fabricated mixer was $2.7mm\times1.6mm$ and the measured performance was 3.5 dB conversion gain, -12.5 dBm output IP3, 42 dB LO to If isolation, 38 dB LO to RF isolation, current consumption of 29 mA for 3.0 V supply voltage.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.58-65
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• 2009

Recently, the Korea Tilting Express(TTX), "HANVIT 200", KRRI(Korea Railroad Research Institute) developed runs for test on the conventional railroad, Honam line, Center line, Chunk-buk line and Tae-baek line. In this paper, we measured the service voltage while TTX ran on the conventional railroad and analyzed the condition of voltage. For measuring voltage directly, we installed PT under the pantograph and measured the voltage of the primary winding. In addition, we record situations that other trains pass by TTX and environments while TTX ran. And then we analyzed the condition of voltage using the records and CBEMA curve. In result, over 110[%] voltage of rated voltage(25[kV]) often occurred and the voltage of some place continued over 110[%] for about 200[s]. Especially, the voltage condition of Tae-baek line is the worst. The results in this paper can help to stabilize the power device and power converter of TTX.

• Journal of KIISE:Databases
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• v.33 no.2
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• pp.163-174
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• 2006

In distributed wireless sensor network, it is difficult to transmit and analyze the entire stream data depending on limited networks, power and processor. Therefore it is suitable to use alternative stream data processing after classifying the continuous stream data. We propose a classification framework for continuous multivariate stream data. The proposed approach works in two steps. In the preprocessing step, it takes input as a sliding window of multivariate stream data and discretizes the data in the window into a string of symbols that characterize the signal changes. In the classification step, it uses a standard text classification algorithm to classify the discretized data in the window. We evaluated both supervised and unsupervised classification algorithms. For supervised, we tested Bayesian classifier and SVM, and for unsupervised, we tested Jaccard, TFIDF Jaro and Jaro Winkler. In our experiments, SVM and TFIDF outperformed other classification methods. In particular, we observed that classification accuracy is improved when the correlation of attributes is also considered along with the n-gram tokens of symbols.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1097-1108
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• 2023

Recently, demand for technology for energy economy and stable supply is increasing due to the increase in power demand of loads. The amount of DC power generation using new and renewable energy is noticeably increasing, and the use of DC power supplies is also increasing due to the increase in electric vehicles and digital loads. During parallel operation to increase the capacity of the power converter, the module bus method or the method using Can communication and serial communication has significant difficulties in smooth operation due to communication time delay for information sharing. Synchronization of information sharing of each power converter is essential for smooth parallel operation, and minimization of communication time delay is urgently needed as a way to overcome this problem. In this paper, a new communication method using pulse width information is proposed as a communication method specialized for parallel operation of power converters to compensate for the disadvantage of communication transmission delay in the existing system. The proposed communication method has the advantage of being easily implemented using the PWM and Capture function of the microcomputer. In addition, the DC/DC converter for DC distribution was verified through simulation and experiment, and it has the advantage of easy capacity expansion when applied to parallel operation of various types of power converters as well as DC/DC converters.