• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.686-693
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• 2004

We have studied a method to fabricated a Surface Acoustic Waves (SAW) filter for Wide band Codeless Division Multiple Access(WCDMA) was formed on the Langasite substrate and was evaporated by Aluminum-Copper alloy and then we developed a simulator using the mathematica package. And, we can design and fabricate the Slanted finger Inter-digital Transducer (SFIT) for the purpose to decreased the ultimate rejections on side of the electrodes, and performed computer-simulation by simulator. Also, we have employed that the block weighted type Inter-digital Transduce(IDT) as input transduce of the filter and the withdrawal weighted type IDT as an output transducer of the filter in order to minimize effect of diffractions. We have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness and the width of reflector are $5000\AA$, and $1\lambda/4(\cong3.6{\mu}m)$, respectively. Also the width of IDT' finger and the space between IDT' finger and reflector are $1\lambda$/16 and 1\lambda$/8, respectively. Frequency response of the fabricated SAW bandpass filter has the property that center frequency is about 190MHz, bandwidth at the 3dB is probably 4MHz and out-band attenuation is -60dB approximately.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.931-934
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• 2006

Recently, as the problems related to agricultural product's safety occur continuously, the system with traceability that can quickly trace back the agricultural products with problems occurred and enable the analysis of causes and prohibition of distribution is required. Therefore, the recording of distribution data is important for this system and for this purpose, the RFID technology that can perceive tags from remote place through radio frequency can be effectively used. But, since the RFID is a technology that is being watched recently, the system that processes RFID tags and distribution data is trifling. Hereby, this thesis designed and implemented the RFID processing system that enables the career trace by analyzing and managing the data on recorded RFID tags and career data based on the standard of traceability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.697-700
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• 2006

A sensor and measuring system were implemented to measure two signals that uroflow and urophonography during urination for diagnose the lower urinary tract symptom. The implemented system was composed of the uroflow sensor using the load-cell, the urophonography measurement sensor so as stethoscope type, pre-processing part for sensors signal detection, amplifier and filter, system control parts and PC measurement program. A simulator of the lower urinary system that is experimental equipment implemented for evaluate the implemented system. The two signals were measured using implemented system and analyzed these signal by means of time domain and frequency domain for extraction of the characteristic parameter the most influence of effect according to occlusion of the lower urinary system. Furthermore two signals were measured and analyzed with the subject of 5 healthy adult for clinical application possibility of the implemented system. As a result, the most influence bandwidth of effect according to occlusion of the lower urinary system is $253\sim282Hz$ of the urophonography signal.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.477-480
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• 2006

To represent the accurate feature of signal and system, many researches have been done in many fields of basic and engineering science which led a great development of modem society. Even until currently, in order to acquire useful information from signals at high speed, many methods and transforms have been processed. In these methods, the Fourier transform which represents signal as the combination of the frequency component has been applied to the most fields. But as transform not to consider time information, the Fourier transform does not provide time information of the time and presents only overall features of signals. The wavelet transform, which is proposed to overcome this problem and recently expands the range of the application, presents time-frequency localization and many kinds of the wavelet can be applied according to the environment of application. In this paper, we detect the features of signals using the function which is considered as the wavelet and do research for filtering locally in the wavelet plane.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2526-2533
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• 2015

In this paper, a design method for a compact dual-band coplanar waveguide-fed slot antenna using SRR(split-ring resonator) conductor is studied. The SRR conductor is loaded inside a rectangular slot of the proposed antenna for dual-band operation. When the SRR conductor is inserted into the slot, the original rectangular slot is divided into a rectangular loop region and a rectangular slot region, and frequency bands are created by the loop and slot, separately. A prototype of the proposed dual-band slot antenna operating at 2.45 GHz WLAN band and 3.40-5.35 GHz band is fabricated on an FR4 substrate with a dimension of 30 mm by 30 mm. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.38-2.51 GHz and 3.32-5.38 GHz for a voltage standing wave < 2, and measured gain is 1.7 dBi at 2.45 GHz, and it ranges 2.4-3.2 dBi in the second band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2066-2070
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• 2009

A voltage controlled attenuator using a PIN diode and two resistors of the $\pi$-type fixed attenuator is described in this paper. The proposed variable attenuator operating for a fixed attenuation range has a good input VSWR and a low intermodulation signal. For the low phase shift, a PIN diode is connected with open stub for the purpose of phase compensation. The stub for phase compensation is calculated by the Deloach method and the related circuit theory. This attenuator is easily fabricated on the microstrip and can be normally used in fine control circuits within small attenuation range. The fabricated attenuator for 2110~2170 MHz frequency band has about 4 dB of an attenuation range, $2^{\circ}$ of phase variance, and -20 dB of S11 according to the input voltage from 0 to 2.7 V.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.3
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• pp.542-547
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• 2018

Various countries around the world are conducting various studies to apply information and communication technology to marine safety. Based on this, the International Maritime Organization (IMO) has established the e-Navigation standard to apply the latest information and communication technology to marine services. In Korea, the Ministry of Maritime Affairs and Fisheries is promoting Korean e-navigation considering domestic marine environment and is trying to apply LTE communication method as a high-speed wireless communication method at sea. In this paper, we describe the development of an LTE based marine router system supporting 700Mhz frequency band allocated for high speed maritime wireless communication service. Experiments on the possibility of 100km distance communication from base station using LTE based ship router are shown. LTE - based high - speed maritime wireless communication router system can provide communication infrastructure necessary to develop various accident prevention technologies that may occur at sea.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.65-73
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• 2007

This paper presents an on-line correction method of current measurement errors for a pure-integration-based flux estimation down to 1-Hz stator frequency. An observer-based approach is taken as one possible solution of eliminating the dc offset and the negative sequence component of unbalanced gains in the synchronous coordinate. At the same time, the positive sequence component estimation is performed by creating an error signal between a motor model reference and an estimated q-axis rotor flux established by a permanent magnet (PM) in the synchronous coordinate. The compensator utilizes a PI controller that controls the error signal to zero. The proposed technique further contains a residual error compensator to completely eliminate miscellaneous disturbances in the estimated flux. The developed algorithm has been implemented on a 1.1-kW permanent magnet synchronous motor (PMSM) drive to confirm the effectiveness of the proposed scheme.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.457-465
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• 2011

The fault analysis and detecting algorithm for a 3 phase diode rectifier is proposed. The 3 phase dioderectifier is used for the AC power rectifier of the PWM inverter. The input power or diode faults cause theripples of the DC voltage, degradation of the control performance and life shortening of the DC link capacitor.In this paper, the ripple of the DC voltage is mathematically analyzed for the earth fault of input power andopen circuit fault of the diode, respectively. The fault detection and type of fault can be obtained by comparingthe average DC voltage and the instant DC voltage which is sampled with 6 times of grid frequency. Theproposed method can be easily applicable and doesn't require additional circuit. The experimental and simulationresults are presented to verify the validity of the proposed method.

• Journal of the Korean Institute of Gas
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• v.7 no.2 s.19
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• pp.48-53
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• 2003

This study is to look at the effect for deformation of carbon steel for high-presure pipe, on the AE signals produced by tensile test. Acoustic emission(AE) has been widely used in various fields because of its extreme sensitivity, dynamic detection ability and location of growing defects. We investigated a relationship failure mode and AE signals by tensile test, From the tensile test, we could divide into four ranges of the failure modes of elastic range, yield range, plastic range before $\sigma$u, plastic range after $\sigma$u. And failure behaviors of elastic range, yield range, plastic range before $\sigma$u, plastic range after $\sigma$u could be evaluated in tensile test by AE counts, accumulation counts and time frequency analysis. It is expected to be basic data that can protect a risk according to tensile test and bending of pipe material for pressure vessel, as a real time test of AE.