• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.506-512
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• 2006

시각적인 정보전달이 어려운 상황에서의 대상인식, 혹은 시각장애인의 대상인식에 있어서 소리는 어느 정도의 역할을 할 수 있을까? 이 연구는 소리를 통해 대상의 형태정보를 전달하기 위해 진행되었다. 하나의 음(musical tone)을 음높이와 음색, 지속시간을 조정한 후, 머리전달함수(Head-Related Transfer Function: HRTF)를 이용하여 수평선, 수직선, 대각선, 곡선의 형태로 운동하는 3-D 사운드 형태소로 만들었다. 그리고 이들의 연속적인 조합을 통해 단순한 도형에서부터 복잡한 도형, 이들 2차원상의 도형을 단면으로 하는 3차원상의 도형들까지 그려내는 소리자극을 구성하였다. 성인 대학생을 대상으로 한 실험에서, 이렇게 만들어진 청각이미지(auditory image)를 듣고 표상된 형태를 여러 개의 시각적인 이미지들(visual images) 중에서 선택하는 과제를 실시하였는데, 실험 결과는 평균 78%의 정확율을 보였다. 이는 소리를 이용한 형태정보 전달의 가능성이 있음을 시사하는 것이며, 이러한 시도는 청각 인터페이스의 응용범위를 확장하는데 도움이 될 것이다.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.705-713
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• 2021

The modulation transfer function (MTF) is calculated to analyze the resolution of the spatial frequency of the image acquired from the x-ray imaging system. In general, the response function of the detector acquires a line spread function (LSF) using a slit-camera, and derives a modulation transfer function through a Fourier transform. Because of the fact that the x-ray must always be incident on the center of the slit-camera, the tilt of the detector and slit-camera caused by the experimenter will affect the detector performance. In addition, if the tilt increases, the performance evaluation of the x-ray image system will be problematic. In this study, we analyzed the experimental and analytical models in the modulation transfer function, ie, the Fourier domain, based on the experimental error and analyzed the effect on the spatial frequency. Furthermore, performance evaluation is being carried out for various x-ray imaging systems, and experimental errors are indispensable, and the extent to which they can be tolerated should be reviewed.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.1
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• pp.56-61
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• 2011

Many control techniques have been proposed in order to improve the control performance of the control system. The degree of freedom on control in the control system is decided by the number of the closed-loop transfer function which can adjust independently. The controller design scheme with two degrees of freedom(TDOF) is extensively used for securing the good control performance to trace a desired value and reject disturbance. In this paper, PID controller is used by controller with TDOF and the design method for control system with TDOF is proposed by the normal method. Using the coefficients of the transfer function of the plant, the transfer function of the control system is normalized by the proposed design method and the parameters of the controller are determined. The control system with the TDOF is constructed by using this method. Through the simulation results, the usefulness of the proposed algorithm is proved.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.5
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• pp.533-540
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• 2013

Prime movers in engine rooms inherently are much affected by the adjustment of their governors for the steady state and transient properties, consequently requiring that marine engineers shall be well familiar with the way to manage governor dials for normal operation. The hydro-mechanical governors basically have different control characteristics and adjustment parameters of stability from digital governors. The former include compensation mechanism using dash pot while the control algorithm of the latter is usually based on the PID action. This study is for configuring a simulation module to let trainees practice how to adjust dials for stability on hydraulic governors in the view that the practice by real governors and engines is time consuming and high cost for operation. The governor module includes the adjusting points such as speed set, speed droop, needle valve and compensation pointer with engine module of $2^{nd}$ order coupled. The results of simulation showed satisfactory responses as a training tool for the adjustment of control parameters.

• The Journal of the Acoustical Society of Korea
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• v.17 no.4
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• pp.82-87
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• 1998

여러 음원들에 의해 형성된 파동장내에서 각 신호음의 주파수 특성과 시간 지연 (time delay)을 추정할 수 있는 알고리즘을 개발하였다. 이 알고리즘의 관련 수식은 두 개의 상호 간섭하는 신호가 입사하고 여기에 주변 환경에 의한 랜덤 잡음이 첨가된다고 가정하여 유도되었으며 두 개 이상의 신호음이 있는 상황에 대해 확장이 가능하다. 본 논문에서 시간 지연이 일정한 수신 신호 영역에 등간격으로 놓여진 수신기로부터 각 센서에 수신된 신호의 스펙트럼은 M개의 센서에 대해 K개의 음원 스펙트럼과 K개의 조정 벡터(steering vector) 의 선형 조합(linear combination)으로 주파수에서 모델된다. 각 음원의 주파수 특성과 음원 으로 들어오는 신호의 입사각을 결정하기 위하여 본 알고리즘은 전달 행렬(transfer matrix) 을 계산하고 그 전달 행렬의 고유값(eigenvalue)과 고유벡터(eigenvector)를 분석한다. 이 고 유값들은 복소수이며 그 크기는 진폭 변환 계수를 결정한다. 위상은 수신기의 간격으로부터 시간 지연을 결정하는 기울기를 갖는 주파수의 선형 함수이다. 전달 행렬에의 입력 자료들 은 동일 간격 소자간의 cross-power spectra이다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.11
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• pp.50-55
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• 2009

In this paper, a distributed amplifier is designed using distributed network synthesis that provides the optimum absorption capability of a capacitance. Transfer functions of filters, which consist of the amplifier, are synthesized by a low-pass Chebyshev approximation. Capacitances that a filter network can absorb are calculated as a function of its minimum insertion loss(MIL) and ripple. Active devices in a distributed amplifier are modeled as equivalent circuits by using their S-parameters, and their equivalent capacitances are absorbed into filter structures by properly adjusting the MIL and ripple of a transfer function. As an application example, a distributed amplifier with the gain of about 12.5dB is designed that operates over the frequency range between 0.1 and 7.5GHz. Experimental results prove that distributed network synthesis, which considers capacitance absorption capability, is useful to the design of distributed amplifiers.

• Journal of the Korean Society for Railway
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• v.13 no.3
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• pp.304-308
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• 2010

This paper presents a methodology for identifying track irregularity using a wavelet transfer function. An equivalent wavelet SISO (single-input single-output) transfer function is defined by the measured track geometry and the acceleration data measured at a bogie of a train. All the measured data with various sampling frequencies were rearranged according to the constant 25cm reference recording distance of the track recording vehicle used in the field. Before applying the wavelet transform, measured data were regressed by eliminating those out of the range. The inverse wavelet transfer function is also formulated to estimate track geometry. The closeness of the estimated track geometry to the actual one is evaluated by the coherence function and also by FRF (frequency response function). A track irregularity index is defined by comparing the variance of the estimation error from the intact condition and that from the current condition. A simulation study has been carried out to examine the proposed algorithm.

• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.5
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• pp.6-11
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• 1972

A general active RC network synthesis procedure which realizes any stable transfer function is described. The network elements are only R's, C's and OA's, and the network configuration are well suited for construction using thin-film RC networks and integrated cil'suit operational amplifiers. Poles and transmission zeros can be adjusted independently to each other and are qu;te insensitive to element variations.

• Journal of Korea Multimedia Society
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• v.13 no.5
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• pp.641-650
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• 2010

Color image sensors (CIS) output color images through image sensors and image signal processing. Image sensors that convert light to electrical signal are divided into CMOS image sensor and CCD image sensor according to transferring method of signal charge. In general, a CIS has RGB output signals from tri-stimulus XYZ of the scene through image signal processing. This paper presents an adaptive colorimetric analysis method to obtain chromaticity and luminance using CIS under various environments. An image sensor for the use of colorimeter is characterized based on the CIE standard colorimetric observer. We use the method of least squares to derive a colorimetric characterization matrix between camera RGB output signals and CIE XYZ tristimulus values. We first survey the camera characterization in the standard environment then derive a SGL(shutter-gain-level) function which is relationship between luminance and auto exposure (AE) characteristic of CIS, and read the status of an AWB(auto white balance) function. Then we can apply CIS to measure luminance and chromaticity from camera outputs and AE resister values without any preprocessing. Camera RGB outputs, register values, and camera photoelectric characteristic are used to analyze the colorimetric results for real scenes such as chromaticity and luminance. Experimental results show that the proposed method is valid in the measuring performance. The proposed method can apply to various fields like surveillant systems of the display or security systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.31-37
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• 2010

This study was developed the home network system for the home stay care by bio-sensor system to translate the physical signal algorithm. The composition algorithm has five functions for a input function, frequency variable, displacement point input function, axial Variable, axial Sway Displacement to search a max and min point with adjustment of 0.01 unit in the reference level. There were checked physical condition of body balance to compounded a measurement such as a heart rate, temperature, weight. The algorithm of home network system can be used to support health care management system through health assistants in health care center and central health care system. It was expected to monitor a physical parameter for health management system.