• Journal of Broadcast Engineering
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• v.19 no.6
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• pp.934-941
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• 2014

In this paper, we present a low profile 2-layered meander built-in monopole antenna for portable RFID reader using FDTD(Finite Difference Time Domain) method. The input impedance, return loss, and VSWR in the frequency domain are calculated by Fourier transforming the time domain results. The double meander 2-layer structure is used to enhance the impedance matching and increase the antenna gain. The measured bandwidth of the antenna is 0.895 GHz ~ 0.930 GHz for a S11 of less than -10dB. The measured peak gain of proposed low profile RFID built-in antenna is 2.3 dBi. And the proposed built-in antenna for portable RFID reader can offers relatively wide-bandwidth and high-gain characteristics, in respectively. Experimental data for the return loss and the gain of the antenna are also presented, and they are relatively in good agreement with the FDTD results. This antenna can be also applied to mobile communication field, energy fields, RFID, and home-network operations, broadcasting, and other low profile mobile systems.

• The Journal of the Acoustical Society of Korea
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• v.14 no.3
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• pp.61-70
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• 1995

In this paper, the PLP cepstrum which is close to human perceptual characteristics was extracted through the spread time area to get the temperal feature. Phonemes were recognized by artificial neural network similar to the learning method of human. The phoneme strings were matched by Markov models which well suited for sequence. Phoneme recognition for the continuous Korean speech had been done using speech blocks in which speech frames were gathered with unequal numbers. We parameterized the blocks using 7th order PLPs, PTP, zero crossing rate and energy, which neural network used as inputs. The 100 data composed of 10 Korean sentences which were taken from the speech two men pronounced five times for each sentence were used for the the recognition. As a result, maximum recognition rate of 94.4% was obtained. The sentence was recognized using Markov models generated by the phoneme strings recognized from earlier results the recognition for the 200 data which two men sounded 10 times for each sentence had been carried out. The sentence recognition rate of 92.5% was obtained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.2
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• pp.33-38
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• 2010

Recently, photovoltaic generator system is widely extended by energy policy of the government. Add to this, high efficiency of photocell power generation is steady needed to sun tracking method. However sun tracking method is not widely extended by insufficiency of tracking technology. As method of solving this problem, this paper applied sunlight sensor and neural network control algorithm for maximum power tracking of sun photocell. Sun tracking sensor consists of one upright square pole and form light sensor of east, west, south, north on flat board. Sun tracking dual axes control is operated respectively by two motor. Motor control input is calculated by neural network control algorithm. The function of proposed control method is verified by sun tracking experiment of photocell generation. The sun tracking method of this paper is increased 32[%] efficiency more than fixed method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.67-75
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• 1990

Performances of a total of 6 selected sediment transport formulas including Engelund & Hansen(EH)'s, Ackers & White(AW)'s, Yang(YN)'s, Brownlie(BR)'s, Karim & Kennedy (KK)'s, and Rijn(RJ)'s ones, which have been known to be relatively reliable, were tested using the 1,399 measured sediment discharge data points of the 20 rivers selected from Brownlie's compendium of sediment discharge. The calculated results were plotted with the input parameters such as the unit discharge, mean velocity, flow depth, energy slope, and median diameter respectively, and trend of each formula's performance was analyzed. These analyses revealed that, in general, EH's and RJ's formulas are more reliable, BR's, AW's, and KK's ones are moderately reliable, and YN's one is less reliable. AW's formula drastically overestimates sediment discharge for fine sediment(D<0.15mm), and YN's one under-estimates sediment discharge for streams with large water discharge(q>5 cms/m).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.207-212
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• 2016

High-frequency induction hardening (HFIH) is used in many industries and has a number of advantages, including reliability and repeatability. It is a non-contact method of providing energy-efficient heat in the minimum amount of time without using a flame. Recently, HFIH has been actively studied using the finite-element method (FEM), however, these studies only focused on the accuracy of the analysis. In this paper, we analyzed HFIH by using a variable frequency based on the conditions of the same shape and input power then comparing the analysis results to experimental results. The analysis and experimental results indicate that the hardening depths are approximately the same using the optimal frequency of 3kHz.

• Journal of KIISE:Software and Applications
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• v.37 no.9
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• pp.712-721
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• 2010

This paper proposes a new fire-flame detection method using probabilistic membership function of visual features and Fuzzy Finite Automata (FFA). First, moving regions are detected by analyzing the background subtraction and candidate flame regions then identified by applying flame color models. Since flame regions generally have continuous and an irregular pattern continuously, membership functions of variance of intensity, wavelet energy and motion orientation are generated and applied to FFA. Since FFA combines the capabilities of automata with fuzzy logic, it not only provides a systemic approach to handle uncertainty in computational systems, but also can handle continuous spaces. The proposed algorithm is successfully applied to various fire videos and shows a better detection performance when compared with other methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1797-1805
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• 2012

In this paper, Power LED(Light Emitting Diodes) is studied to driver as a new lighting system in the spotlight, replacing a large existing lighting system with fluorescent and incandescent lighting. To take advantage a variety of DC power as the boost DC-DC converter design specifications through the inductor L and capacitor C through PSPICE to calculate the best estimate of the value. Converter's switching frequency is 50[kHz], the first Duty Rate was made to increase gradually depending on the value of the detection were, 10[%] in the output voltage. As a result, the simulated Boost Power LED driver characteristics is in comparison with the design specifications, 5[%] or less as the error was approximated. So, when input 15[V] were offered, a stable output 24[V] were obtained, and Dimming Control through the adjustment of brightness and current consumption were obtained to possible result.

• The Journal of the Korea Contents Association
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• v.9 no.11
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• pp.289-296
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• 2009

In this study, I presented power control unit with potential use in the magnetic stimulation of biological systems. The effect of the magnetic stimulation depends on the geometry and orientation of the induced electric field as well as on the current pulse waveform delivered by the stimulator coil. TMS is achieved from the outside of the head using pulses of electromagnetic field that induce an electric field in the brain. There are numerous possibities in the applications TMS, such as diagnosis and therapy through the brain stimulation. These factors are very important to define the equipment requirements and characteristics in that the topology of the power supply and the size and geometry of the coil. The proposed solution is the generation of current pulses with variable amplitude and duration, according to a user defined input. Another solution is the topology that uses elements to store and transfer energy from the power source to the load. In addition to proposed topology, an adequate control strategy and right set of the power circuit parameters made possible to obtain unipolar waves and bipolar waves.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.374-376
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• 2018

In this study, we developed a mobile home robot using a face recognition method using a camera attached to a raspberry pie. It receives the real time image through the camera attached to the raspberry pie, recognizes the face of the person, and distinguishes the operation of the smart cool air temperature device according to the result. It is expected that the robot will be able to increase the energy utilization efficiency by allowing the robot to operate in cold and hot winds only where there is no human being, instead of operating the hot and cold air conditioner.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.41-48
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• 2011

Warm-Mix Asphalt(WMA) mixtures, which meet environmental protection and have high energy efficiency, are emerging as an alternative to hot-mix asphalt mixtures. The objective of this study is to evaluate WMA made with Aspha-min in the laboratory and to compare the design results accomplished by new Mechanistic-Empirical Pavement Design Guide(MEPDG) with control mixture. An asphalt mixture with a nominal maximum size of 12.5mm and PG64-28 binder was used. Resilient modulus tests for a control mixture and WMA with 0.3% and 0.5% of Aspha-min were conducted. The results obtained by MEPDG after inputting the test output into the design indicated that the predicted rut depth of WMA using Aspha-min was much lower than that of control mixture, and showed that WMA was more resistant to rutting than control mixture.