• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.119-120
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• 2004

Split-beam 트랜스듀서의 입력신호로써 Sweep 신호를 구동한 어군탐지기 SONAR에 대하여 기술한다. Sweep 신호의 대역폭은 트랜스듀서 공진 대역의 대역폭에서 주파수 이동 변환하였다. 목표 대상물의 방위각 추정은 각 수신 채널 사이의 크로스-스펙트럼을 사용하여 추정한다. 추정 방위각의 정확도는 제안한 시스템의 알고리듬에 관계하고 있다.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.1
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• pp.46-53
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• 2000

본 논문에서는 전원전압 센서 없는 단상 PWM 컨버터의 전류제어방법을 제안한다. 제안된 방법에서 전원전압은 슬라이딩 모드 관측기에 의해 추정되며 추정된 전원전압을 이용하여 컨버터의 입력 역률을 '1'로 하고 일정한 DC링크전압을 얻을 수 있다. 제안된 방법의 특징은 전원전압의 크기와 위상의 추정이 실제전류와 추정전류의 전류오차에 의해서 얻어질 수 있다. 제안된 방법은 DSP를 이용하여 구현하고, 실험결과는 제안된 방법의 정당성을 입증한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.11a
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• pp.139-143
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• 1997

본 논문에서는 점확산함수(point spread function; PSF)의 추정을 기반으로 한 완전한 자동초점 시스템을 제안한다. 초점이 맞지 않은 영상의 정확한 PSF의 추정을 위해서, 입력 영상을 부영상으로 분할하고, 에지를 가진 부영상들의 계수함수 응답의 평균을 취한다. 초점이 맞지 않은 열화로 발생하는 PSF는 보통 영상이 물체와 배경간에 선형의 경계를 가지고 있다는 가정하에 에지의 방향을 따라 평균되어진 계단함수 응답의 차이를 따라 추정되어진다. 이렇게 예측된 PSF를 사용하여 영상복원 필터는 제한적 최소 제곱의 접근방법을 통해 구현되어진다.

• The Journal of the Acoustical Society of Korea
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• v.13 no.3
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• pp.16-24
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• 1994

A single channel adaptive noise canceling (ANC) technique is presented for removing effects of additive noise on the speech signal. The conventional method obtains a reference signal using the pitch estimated on a frame basis from the input speech. The proposed method, however, gets the reference signal using the delay estimated recursively on a sample by sample basis. To estimate the delay, we derive recursion formula of autocorrelation function and average magnitude difference function. The performance of the proposed method is evaluated for the speech signals distorted by the additive white Gaussian noise. Experimental results with normalized least mean square (NLMS) adaptive algorithm demonstrate that the proposed method improves the perceived speech quality quite well besides the signal-to-noise ratio.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1177-1183
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• 2010

In this paper, a parallel bank of multiple adaptive unknown input observers approach suggested by D.Wang is applied to detect a single fault of control surface actuator and to estimate the actuator position of lock-in-place fault using a small fixed-wing UAV model with eight control surfaces. This paper shows that not only the fault diagnosis algorithm detects and estimates each faults of lock-in-place in 1 second by simulation but also it may be unavailable to isolate among two same-shaped rudders.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.2
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• pp.65-73
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• 2008

The characterization process for the accurate color reproduction in mobile phone with camera and LCD is popular. The camera and LCD characterization, gamut mapping process is necessary to map the camera's input color stimulus, CIEXYZ value, into the LCD's output color stimulus. Each characterization is the process estimating the relation between input and output signals. In case of LCD, because of output device, the output color stimulus for the arbitrary input signal can be measured by spectro-radiometer However, in the camera, as the input device, the characterization is an inaccurate and needs the manual works in the process obtaining the output signal because the input signal can not be generated. Moreover, after gamut mapping process, the noise is increased because the optimized gamma tone curve of camera for the noise is distorted by the characterization. Thus, this paper proposed the system of obtaining the output signal of camera and the method of gamma correction for the noise. The camera's output signal is obtained by RGB values of patches from captured the color chart image. However, besides the illumination, the error for the location of the chart in the viewfinder is generated when many camera modules are captured the chart. The method of correcting the position to correct the error from manual works. The position of camera is estimated by captured image. This process and moving of camera is accomplished repeatedly, and the optimized position can be obtained. Moreover, the lightness curve of camera output is corrected partly to reduce the noise from the characterization process.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1105-1108
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• 1998

본 논문은 VSB 전송방식의 HDTV 수신기에 입력되는 신호의 위상잡음 및 이득오차를 없애주는 위상 추적 루프를 설계하였다. 위상 추적 루프는 VSB 신호가 가지는 신호점과 입력된 I 채널의 표본화된 데이터를 이용하여 신호점들의 Q 채널 성분을 추정한 다음 복소곱셈기를 이용하여 입력신호와 곱합으로써 위상의 에러값을 보상하는 구조로 되어 잇다. 위상오차를 검출하는 알고리즘으로 시그늄 함수를 이용함으로써 하드웨어의 부담을 줄이면서 넓은 선형영역을 가질 수 있게 되어 우수한 추적 성능을 가지는 위상 추적 루프를 구현하였고 소프트웨어 심류레이션을 통하여 제시한 알고리즘의 효율성을 입증한 후 ASIC으로 구현하였다.

• ICROS
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• v.15 no.2
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• pp.17-25
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• 2009

본 고에서는 이동로봇의 동시간 위치인식 및 지도작성(Simultaneous Localizaton and Mapping;SLAM) 기술에 대하여 다룬다. 이동로봇의 SLAM을 위하여, 로봇과 랜드마크의 상태를 상태공간 영역에서 같이 기술하는 방법과 센서로부터 입력된 정보를 이용하여 로봇이 상태를 추정하는 기법을 소개한다. 실제 로봇을 통한 예제를 통하여 로봇의 상태와 특징점을 동시에 추정하는 것을 보여준다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.6
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• pp.26-35
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• 2009

In this paper, we present morphology-based step region extraction and regularized iterative point-spread-function (PSF) estimation methods. The proposed PSF estimation method uses canny edge detector to extract the edge of the input image. We extract feasible vertical and horizontal edges using morphology analysis, such as the hit-or-miss transform. Given extracted edges we estimate the optimal step-response using flattening and normalization processes. The PSF is finally characterized by solving the equation which relates the optimal step response and the 2D isotropic PSF. We shows the restored image by the estimated PSF. The proposed algorithm can be applied a fully digital auto-focusing system without using mechanical focusing parts.

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.95-104
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• 2013

In this study, a novel method is proposed for retrieving relative surface temperature from single-channel middle infra-red (MIR, 3-5 ${\mu}m$) remotely sensed data. In order to retrieve absolute temperature from MIR data, it is necessary to accommodate at least atmospheric effects, surface emissivity and reflected solar radiance. Instead of retrieving kinematic temperature of each target, we propose an alternative to retrieve the relative temperature between two targets. The core idea is to minimize atmospheric effects by assuming that the differential at-sensor radiance between two targets experiences the same atmospheric effects. To reduce effective simplify atmospheric parameters, each atmospheric parameter was examined by MODTRAN and MIR emissivity derived from ASTER spectral libraries. Simulation results provided a required accuracy of 2 K for materials with a temperature of 300 K within 0.1 emissivity errors. The algorithm was tested using MODIS band 23 MIR day time images for validation. The accuracy of retrieved relative temperature was $0.485{\pm}1.552$ K. The results demonstrated that the proposed algorithm was able to produce relative temperature with a required accuracy from only single-channel radiance data. However, this method has limitations when applied to materials having very low temperatures using day time MIR images.