• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.1
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• pp.9-17
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• 2005

We studied the characteristics of impedance and electromechanical coupling coefficient in ZnO and AIN thin films by using resonance frequency spectrum method. The response peak of impedance decreased with the decrease of thickness of piezoelectrics, the number of mode of response peak decreased with the decrease of substrate thickness. An error of Kt² estimated from input Kt² increased as the thickness of piezoelectrics decreased and the thickness of substrate increased. Also, the error was increased in case of a large acoustic impedance of substrate. It was found that the composite resonator operating in optimized condition could be designed through the resonance frequency spectrum analysis of composited resonator consisted of piezoelectric thin film and substrate.

• Journal of Advanced Navigation Technology
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• v.25 no.1
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• pp.90-95
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• 2021

In this paper, the design method for a high-sensitivity compact resonator for chipless RFID tags is proposed. Proposed high-sensitivity compact resonator uses an interdigital-capacitor structure instead of a capacitor-shaped strip structure in a conventional ELC resonator. The length of the electrode plate of the IDC structure is longer than that of the conventional capacitor-shaped structure, resulting in a larger equivalent capacitance of the resonator. This can lower the resonant peak frequency of the RCS characteristic. Two resonators with the same length of the square loop and the width of the strip are fabricated on an RF-301 substrate with a thickness of 0.8 mm. The experiment results show that the resonant peak frequency and value of the bistatic RCS for the ELC resonator were 4.305 GHz and -30.39 dBsm, whereas those of the proposed IDC resonator were 3.295 GHz and -36.91 dBsm. Therefore, the size of the resonator is reduced by 23.5% based on the measured resonant peak frequency of the RCS characteristic.

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.530-535
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• 2021

In this paper, the design method for a chipless RFID tag using ELC resonators is proposed. A four-bit chipless RFID tag is designed in a two by two array configuration using three ELC resonators with different resonant peak frequencies and one compact IDC resonator. The resonant peak frequency of the bistatic RCS for the IDC resonator is 3.125 GHz, whereas those of the three ELC resonators are adjusted to be at 4.225 GHz, 4.825 GHz, and 5.240 GHz, respectively, by using the gap between the capacitor-shaped strips in the ELC resonator. The spacing between the resonators is 1 mm. Proposed four-bit tag is fabricated on an RF-301 substrate with dimensions of 50 mm×20 mm and a thickness of 0.8 mm. It is observed from experiment results that the resonant peak frequencies of the fabricated four-bit chipless RFID tag are 3.290 GHz, 4.295 GHz, 4.835 GHz, and 5.230 GHz, respectively, which is similar to the simulation results with errors in the range between -2.3% and 0.2%.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.541-554
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• 2010

Fifteen min-microtremor data sets were collected at 136 sites from a coastal area of Kunsan and 117 sites from an inland area of Jeonju located in SW Korea, and were analyzed for the HVSR (Horizontal to Vertical Spectral Ratio) of the sites. The microtremor spectra of the coastal area have stronger energy in the lower frequency range from 1-6 Hz than those of the coastal area. This result can be attributed to the effect of the waves and tides in the Keum river and the Yellow sea. Twenty four hours of measurement of the microtremor indicated that the microtremor spectrum correlates with the human activities, but the microtremor HVSR peak was observed consistently at the characteristic frequency for the site. The HVSR peaks were grouped into 4 types -"single peak", "double peak", "broad peak" or "no peak"- based on their shapes. More than 90% of the data sets exhibit peak frequencies ($F_0$) which can be easily identified. The distribution of $F_0$ reveals a close relationship with the topography and local geology of the areas, exhibiting high F0s in the hillside areas and low $F_0s$ in the reclaimed land area. While the amplitudes of microtremor HVSR peak frequencies are less than 4 in the downstream of the inland area, those of the recently reclaimed land in the coastal area are extremely high (more than 10). The results of this study indicate that detailed HVSR studies are essential for the earthquake hazard reduction of reclaimed lands.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.452-453
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• 2006

저압 개폐기는 에어컨, 냉동기, 쇼케이스, 산업용 청소기, 전기 온수기, 건조기, 공조기, 펌프, 콤프레셔 등의 모터제어 및 히터와 조명기기의 개폐 등에 광범위하게 이용되는 개폐장치이다. 저압 전자개폐기는 수 천회에서 수백만회까지 빈번한 개폐사용조건으로 인해 시험규격에서는 개폐시험을 통해 수명을 검증하도록 되어 있다. 이 개폐시험 회로는 규정된 전압, 전류, 역률 조건을 맞추기 위해 저항과 리액터를 직렬 연결하여 구성한다. 또한 모터와 같은 리액터 부하를 개폐하는 개폐기의 경우는 전류차단 순간 과도회복전압의 피크비와 주파수를 규정하여 적용하고 있다. IEC60947-1에서는 과도회복전압의 피크비와 주파수에 대한 규정값을 제시하고 있으며 제시된 값을 제어하기 위한 회로를 제시하고 있다. 과도회복전압의 피크비와 주파수는 개폐기 접점의 절연성능과 밀접한 관계가 있으며 수명에 치명적인 영향을 미친다. 본 연구에서는 LS산전(주) 부하개폐시험 회로의 과도회복전압 조건과 영향을 설명하고 제어하기 위한 저항과 커패시터를 적용하는 방법을 제안하고자 한다.

• Journal of Korea Multimedia Society
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• v.9 no.3
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• pp.279-286
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• 2006

Classification method used in this paper is applied for the first time to Korean traditional music. Among the frequency distribution vectors, average peak value is suggested and proved effective comparing to previous classification success rate. Mean, variance, spectral centroid, average peak value and ZCR are used to classify Korean traditional musical instruments. To achieve Korean traditional instruments automatic classification, Spectral analysis is used. For the spectral domain, Various functions are introduced to extract features from the data files. k-NN classification algorithm is applied to experiments. Taegum, gayagum and violin are classified in accuracy of 94.44% which is higher than previous success rate 87%.

• Journal of IKEEE
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• v.22 no.4
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• pp.1158-1162
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• 2018

A fast-lock multiplying delay-locked loop (MDLL)-based digital clock frequency multiplier with an anti-harmonic lock capability is presented. The proposed digital frequency multiplier utilizes a new most-significant bit (MSB)-interval search algorithm to achieve fast-locking time without harmonic lock problems. The proposed digital MDLL frequency multiplier is designed in a 65nm CMOS process, and the operating output frequency range is from 1 GHz to 3 GHz. The digital MDLL provides a programmable fractional-ratio frequency multiplication ratios of N/M, where N = 1, 4, 5, 8, 10 and M = 1, 2, 3, respectively. The proposed MDLL consumes 3.52 mW at 1GHz and achieves a peak-to-peak (p-p) output clock jitter of 14.07 ps.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.462-465
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• 2011

본 논문에서는 다중 반송파, 특히 OFDM 시스템의 PAPR 을 감소시킬 수 있는 CFR 알고리즘을 다룬다. 기존의 피크 윈도윙 기법이 윈도우 길이 내에 피크들이 여러 개 있을 경우, 과도 clipping 으로 인하여 성능이 열화되는 현상을 개선하기 위하여 포락선 기반 피크 윈도윙 기법을 적용한다. 뿐만 아니라, 피크 윈도윙이 가지고 있는 EVM 열화를 완화하기 위하여 기존의 단순 clipping 기법과 혼합하여 시스템에서 요구하는 EVM 성능뿐 아니라 ACLR 성능까지도 만족하도록 한다. MATLAB 을 이용하여 알고리즘을 검증하고, 하드웨어 구현을 위하여 Xilinx Virtex5 를 이용하여 검증하여 제안하는 기법의 복잡도는 높지만 EVM 과 ACLR 성능이 우수함을 알 수 있다. 효율적인 주파수 이용과 수신 성능 측면에서 우수한 성능을 보인다. 따라서 DVB-T 나 LTE, IEEE 802.16m 등의 차세대 방송 및 통신의 전송에 이용되는 OFDM 신호의 PAPR 을 효과적으로 줄일 수 있는 기법으로 적용될 수 있다.

• The Journal of the Acoustical Society of Korea
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• v.19 no.5
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• pp.35-40
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• 2000

In this paper, the relation between the radiated sound and the vibration due to piezoelectric ESWL(Extracorporeal Shock Wave Lithotripter) is examined and the results of the experiments are represented. Next, the relation between the focal point and the vibration of the objects is examined. The same experiments with the objects that can be broken are done and the relation between the vibration and the break efficiency of the phantom is experimentally investigated. These results show that the relativity between the power of the peak frequency and the break efficiency can be confirmed.

• The Journal of the Acoustical Society of Korea
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• v.38 no.1
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• pp.56-65
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• 2019

The Indo-Pacific bottlenose dolphins (Tursiops aduncus) are a toothed whale using echolocation clicks and have been studied continuously abroad. However, most studies on this whale's clicks were performed about captive animals and, in Korea, only the studies of the whistle sounds of this animal were done. In this paper, acoustic characteristics of clicks were analyzed about the free-ranging Indo-Pacific bottlenose dolphins living in the coast of the Jeju Island. Acoustic parameters such as signal duration, 1st and 2nd peak frequency, 3 dB and 10 dB bandwidth for acoustic characteristics were calculated and compared with those of Australian species. As a result, the signal durations had average of $38{\mu}s$ and most clicks were within range of $20{\mu}s-60{\mu}s$. The two types of bandwidths showed both narrowband and broadband characteristics, and bimodal signal characteristics were confirmed through the 1st peak frequencies(average of $96kHz{\pm}18kHz$) and the 2nd peak frequencies(average of $69kHz{\pm}19kHz$).