• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.3
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• pp.41-46
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• 2011

The tire damage classification method is researched by periodicity detection of ultrasonic envelope signals to occur at the driving vehicle tire. Because periodic signals is generated by rotations of the damaged tire, it should convert to pulse for using the density function. After time intervals of pulses are represented by the density function, the dominant periodicity is detected. The threshold to make a pulse is calculated by moving average of envelope signals. The result of time density function in case of one damage material, the first peak's time is equals to tire's rotation period, 162ms and 102ms, about the speed of 50km/h and 80km/h. In case of more than one damage material, the sum of each peak's time is equals to tire's rotation period about the speed.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.142-148
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• 2012

This study presents the assessment results of adhesive properties on the interface between a silicon wafer and nano-scale polymer thin film pattern through UAFM images by using the contact resonance frequency of the cantilever. For the experiment, we varied surface treatment processes for the silicon wafer and fabricated a 300nm polymer thin film pattern through lithography. Images from the optical microscope were used to compare the produced test specimens for adhesive condition and the critical load value from the nano scratch test was used to verify the adhesive condition of the nano pattern. Each test specimen resulted in a $1{\mu}m{\times}1{\mu}m$ surface image and subsurface adhesive image. Adhesive condition was evaluated by image contrast differences on the interface according to the changing amplitudes and phases of contact resonance frequency.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.27-30
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• 2001

Electromigration Phenomena in Al-1%Si thin film interconnections under DC and PDC conditions were investigated. Thin film interconnections with $SiO_2$ and PSG/$SiO_2$ dielectric passivation layer were formed by a standard photolithography process method and test line lengths were 100, 400, 800, 1200, and 1600 $\mu\textrm{m}$. The current density of $1.19\times10^7\textrm{A/cm}^2$ was stressed in Al-1%Si thin film interconnections under DC condition. The current density of $1.19\times10^7\textrm{A/cm}^2$ was also applied under PDC condition at the frequency of 1 Hz with the duty factor of 0.5. The electromigration resistance of PSG/SiO2 dielectric passivation test line was stronger than $SiO_2$ dielectric passivation test line. The lifetime under PDC was 2-4 times longer than DC condition. As the thin film interconnection line increased, the lifetime decreased and saturated over the critical length. Failure patterns by an electromigration were dominated by void-induced electrical open and hillock-induced electrical short.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.154-159
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• 2003

In this paper, we proposed variable threshold dual rate ADPCM coding method which adapts two coding rates of the standard ADPCM of ITU G.726 for speech quality improvement at a comparably low coding rates. The ZCR(Zero Crossing Rate) is computed for speecd data and under the noisy environment, noise data dominant region showed higher ZCR and speech data dominant region showed lower ZCR. The speech data with the higher ZCR is encoded by low coding rate for reduced coded data and the speech data with the lower ZCR is encoded by high coding rate for speech quality improvements. For coded data, 2 bits are assigned for low coding rate of 16[Kbps] and 5 bits are is assigned for high coding rate of 40[Kbps]. Through the simulation, the proposed idea is evaluated and shown that the variable dual rate ADPCM coding technique shows the qood speech quality at low coding rate.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.351-355
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• 2006

RSA 암호 시스템은 IC카드, 모바일 및 WPKI, 전자화폐, SET, SSL 시스템 등에 많이 사용된다. RSA는 모듈러 지수승 연산을 통하여 수행되며, Montgomery 곱셈기를 사용하는 것이 효율적이라고 알려져 있다. Montgomery 곱셈기에서 임계 경로 지연 시간(Critical Path Delay)은 세 피연산자의 덧셈에 의존하고 캐리 전파를 효율적으로 처리하는 문제는 Montgomery 곱셈기의 효율성에 큰 영향을 미친다. 최근 캐리 전파를 제거하는 방법으로 캐리 저장 덧셈기(Carry Save Adder, CSA)를 사용하는 연구가 계속 되고 있다. McIvor외 세 명은 지수승 연산에 최적인 CSA 3단계로 구성된 Montgomery 곱셈기와 CSA 2단계로 구성된 Montgomery 곱셈기를 제안했다. 시간 복잡도 측면에서 후자는 전자에 비해 효율적이다. 본 논문에서는 후자보다 빠른 연산을 수행하기 위해 캐리 전파 제거 특성을 가진 이진 부호 자리(Signed-Digit, SD) 수 체계를 사용한다. 두 이진 SD 수의 덧셈을 수행하는 잉여 이진 덧셈기(Redundant Binary Adder, RBA)를 새로 제안하고 Montgomery 곱셈기에 적용한다. 기존의 RBA에서 사용하는 이진 SD 덧셈 규칙 대신 새로운 덧셈 규칙을 제안하고 삼성 STD130 $0.18{\mu}m$ 1.8V 표준 셀 라이브러리에서 지원하는 게이트들을 사용하여 설계하고 시뮬레이션 하였다. 그 결과 McIvor의 2 방법과 기존의 RBA보다 최소 12.46%의 속도 향상을 보였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1342-1348
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• 2017

In an era where digital data takes on great importance, images are essential to various media. Noise is generated during the acquisition and transmission of such images, caused by a number of external factors. The removal of noise is an essential step in image processing. There are various methods used to remove noise, in accordance with the cause or form of the noise. AWGN is one of the leading methods. As such, this paper applies the edge detection method using the mean of each pixel after categorizing in detail the partial masks into nine areas as part of the preliminary process, in order to minimize noise that had been added to the image. In addition, the paper suggests an algorithm that applies different filters to the partial masks by using the critical mass value of the transfigured edge detection. To verify the competence of the suggested algorithm, it was compared with existing methods by using magnified images and PSNR(peak signal to noise ratio).

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.89-92
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• 2007

This paper describes the GIS system that enables users to look up the final destination on a map automatically by setting up a random radius of threshold under the present user position. Various information systems based on the existing GIS have disadvantage that a search is difficult when the destination location is not clear. And it is inefficient that the processing time is delay due to a complex configuration and large amount of informations based on the target of special business supports. Therefore, this paper improves these problems and proposes the customized geographic information system which is for the general user. The customized geographic information system confirms the detail items from search results, which is destinations fitting for a condition in the suitable radius of threshold from the present user position. And the user can look up the suitable final destination on a map easily using the customized information system. The result of this paper, which is based on the sample of the large unit locations, will be expected to be able to guide more detail, extensive and various informations.

• Journal of Korea Multimedia Society
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• v.16 no.12
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• pp.1385-1392
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• 2013

There is a variety of researches about recognition system using biometric data these days. In this study, we propose a new algorithm, uses simultaneous equation that made of the edge of objects, to segment an iris region without threshold values from an anterior eye image. The algorithm attempts to find a center area through calculated outskirts information of an iris, and decides the area where the most points are accumulated. To verify the proposed algorithm, we conducted comparative experiments to Hough transform and Daugman's method, based on 50 images anterior eye images. It was found that proposed algorithm is 5 and 75 times faster than on each algorithm, and showed high accuracy of detecting a center point (95.36%) more than Hough transform (92.43%). In foreseeable future, this study is expected to useful application in diverse department of human's life, such as, identification system using an iris, diagnosis a disease using an anterior image.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.163-170
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• 2017

MLAT which is an independent cooperative surveillance system is applied to increase the positon resoultin of secondary survelliance radar. MLAT uses the hyperboic or hyperboloid position mesurement algorithm. Central processing unit of MLAT calculates target position using time difference of arrival (TDOA) which can be solved from time of arrival (TOA) information of each receivers (at least 4 receivers). To increase position resolution of MLAT which use TDOA, TOA which is transfer time from tranmitter to receiver shold be calculated with precision time resolution in receiver. This paper explained the MLAT system briefly and explained ATD which is one of means of calcuating pulse position. ATD is applied to solve the deviation of pulse position due to different amplitude of signals in mulitiple receivers. In this paper, to analysis the performance of ATD, the simulation result of LAS and CDS was compared with the simulation result of basic threshold method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2259-2266
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• 2016

Recently dense wireless local area networks (WLANs) emerge as the number of WLAN cells and stations increases. In such dense WLAN environment, this paper proposes a new distributed medium access control (MAC) protocol. The proposed MAC protocol extends the previous CSMA with collision resolution (CSMA/CR) that uses a single collision detection (CD) phase and employs multiple CD phases to resolve more collisions. It checks the collision detection in each CD phase and stops the CD phase if consecutive non-detected CD phases occur more than the threshold. Therefore, the proposed protocol can control the number of CD phases adaptively according to the number of accessing stations and increase the probability of collision resolution while decreasing the packet overhead. The simulation results show that the proposed adaptive CSMA/CR protocol employs a variable number of CD phases according to the number of stations and achieves a greater throughput than the previous CSMA/CR protocol using the fixed number of CD phases.