• Journal of Advanced Marine Engineering and Technology
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• 제22권4호
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• pp.538-550
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• 1998

The variable frequency and variable voltage AC source made by a conventional inverter which is composed of power semi-conductors includes much noises in sine wave due to high frequency switching of DC source. In this paper the 3rd low pass LC filter for a variable speed 3 phase induction motor driven by a full bridge inverter is introduced to solve the EMI problem by serious noise current. The utility of a modified 3rd order Butterworth LC filter is confirmed through FFT analysis of sine waves and noiseless ACsource can be obtained by the proposed LC filter. The speed of a 3 phase induction motor driven by a full bridge inverter with a LC filter is satisfactorily controlled by a digital PID controller under the condition of stepwise load and setpoint changes.

• 한국항해항만학회지
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• 제35권1호
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• pp.1-7
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• 2011

본 논문에서는 현재 건설 중인 목포대교와 선박 사이의 충돌 위험도 평가에 필요한 선박 정보와 기상 정보 수집 장치(Data Acquisition System, DAS) 개발에 관하여 기술하였다. 본 연구에서는 DAS를 통항 선박과 기상 현황 데이터를 수집하기 위한 신호 수신 및 처리 유닛과, 데이터 전송과 분배를 위한 네트워킹 유닛, 데이터 관리를 위한 유닛 등으로 구성하였다. 목포항 여객터미널과 신안군 안좌도를 왕복하는 카페리 선상에서의 현장 실험을 통해, 충돌 위기 평가에 적합한 정보를 DAS가 제공할 수 있음을 알았다. 또한 5차 버터워스 디지털 필터를 이용하여 기상 데이터에 포함된 잡음성 데이터를 충분히 억제할 수 있었다.

• 대한전기학회논문지:전력기술부문A
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• 제51권10호
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• pp.495-501
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• 2002

A difference based current transformer (CT) saturation detection algorithm uses the third difference of a secondary current to detect the instants of the beginning/end of saturation. The third difference of a secondary current contains high frequency components when a CT is saturated. Thus, an effect of an anti-aliasing lowpass filter implemented in digital protection relays on the detection algorithm should be studied. This paper describes performance analysis of a lowpass filter on the CT saturation detection algorithm. The cutoff frequency of the lowpass filter is normally set to be half of a sampling frequency. In this Paper, two sampling frequencies of 3,840 (Hz) corresponding to 64 sample/cycle (s/c) and 1,920 (Hz) corresponding to 32 (s/c) are studied; the cutoff frequencies of the lowpass filters are set to be 1,920 (Hz), 960 (Hz) and 960(Hz), 480(Hz), respectively. And the proposed algorithm is verified by experiment. A 2nd order Butterworth filter is designed as a lowpass filter. The test results and experiment results clearly indicate that the saturation detection algorithm successfully detects the instants of the beginning/end of saturation even though a secondary current is filtered by the designed lowpass filters.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 춘계 학술대회논문집
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• pp.56-61
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• 2004

As the size and dimension of target problems in the field of computational engineering including CFD gets bigger and higher, it is needed to have more efficient and flexible data visualization environment in terms of software and hardware. Even though it is still manageable to use a mouse in controlling 3-dimensional data visualization, it would be beneficial to use 3-D input device for 3-D visualization. 'Data Glove' is one of the best 3-D input devices, because human hands are best tools understanding 3-D space. Signals coming from 'Data Glove' are analog and very sensitive to finger motions, so we decided to use a digital filter. This paper describes our experience and benefits of using data glove in controlling 3-Dimensional Postprocess Software.

• 한국전산유체공학회지
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• 제11권2호
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• pp.56-61
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• 2006

As the size and dimension of target problems in the field of computational engineering including CFD gets bigger and higher, it is needed to have more efficient and flexible data visualization environment in terms of software and hardware. Even though it is still manageable to use a mouse in controlling 3-dimensional data visualization, it would be beneficial to use 3-D input device for 3-D visualization. 'Data Glove' is one of the best 3-D input devices, because human hands are best tools for understanding 3-D space and manipulating 3-D objects. Signals coming from 'Data Glove' are analog and very sensitive to finger motions, therefore signal filtering using a digital filter is applied. This paper describes our experience and benefits of using data gloves in controlling 3-dimensional postprocessing softwares.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.114-117
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• 2000

We developed a motion capture system to get angle data of human joints in walking mode. The data are used to coordinate the biped-walking robot developed in our laboratory. A pair of motion capture system is composed of three links with the ankle, knee, and pelvis joints. The system has six axes attached with potentiometers. We used an A/D converter was used to get digital data from joint angles. We filterd the data using the Butterworth 4th order digital filter, and simulated walking motion based on the data using the Matlab.

• 대한전자공학회논문지
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• 제20권6호
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• pp.6-10
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• 1983

본 논문에서는 레지듀 연산(residue arithmetic)을 사용하여 디지탈 필터를 실현하는 한 가지 방법을 제시 하였다. 기존의 레지듀 디지탈 필터가 비교적 적은 비트 수를 갖는 신호만을 처리할 수 있었던 것에 비해, 여기서는 비트 슬라이스 알고리즘[1]의 원리를 적용함으로써 보다 많은 비트 수를 갖는 신호를 처리할 수 있도록 했으며, 또한 레지듀 가감산 및 승산은 연산표에 의해서 고속으로 수행될 수 있으므로 이를 이용하여 비트 슬라이스 알고리즘의 단점인 융통성 (flexibility)의 문제를 해결하였다. 실제로 종속 접속형 4차 버터워즈 저역통과 디지탈 필터를 구성하여 실험함으로써 이와 같은 사실들을 입증할 수 있었다.

• 한국멀티미디어학회논문지
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• 제14권11호
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• pp.1392-1400
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• 2011

최근 대부분의 디지털 이미지 응용분야에서는 영상 처리 및 분석을 위해 고해상도 이미지나 비디오가 요구되고 있다. 한편, 일반적인 영상획득시스템으로부터 획득한 영상신호는 획득하는 과정에서 물리적 영향, 제조 기술의 한계 및 환경적인 영향 등으로 인하여 영상의 화질 저하를 가져온다. 이러한 문제를 해결하기위해 연구되고 있는 방법 중 하나인 초해상도 복원 기술은 동일한 물체를 촬영한 다수의 저해상도 영상으로 고해상도 영상을 만들어내는 영상복원기술이다. 본 논문에서는 S&A (Shift & Add) 방법에 POCS (Projection onto Convex Sets) 이론을 적용하여 기존의 방법보다 개선된 알고리즘을 제안한다. 기존의 알고리즘은 잡음에 약하다는 문제점이 있다. 이를 해결하기 위해 제안한 방법에서는 복원단계에 사용되는 참조영상을 POCS이론에 적용하여 기존의 S&A방법과 결합하였다. 또한 광학적 왜곡에 해당하는 카메라 블러(blur) 연산자로 주파수 영역에서 BLPF (Butterworth Low-pass Filter)를 사용하여 기존방법의 문제점인 링잉현상을 해결하였다. 실험결과를 통해 잡음에 강하고 영상의 고주파영역을 향상시킨 제안한 초해상도 방법의 우수성을 확인하였고, 객관적 평가를 위해 기존의 방법과 PSNR (peak signal to noise ratio)을 비교하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.79-82
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• 1999

In this paper, STATCOH(static synchronous compensator : one of the custom power equipment) is proposed for balancing unbalanced loads. Compensation current references are given by the analysis of the unbalanced 3-phase currents. And for detecting negative-sequence components, digital Butterworth LPF(low pass filter) is used. The predicted current controller in the synchronous rotating coordinates is also proposed. Finally, the effectiveness of STATCOM is verified by the simulations for unbalanced loads.

• 제어로봇시스템학회논문지
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• 제21권6호
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• pp.583-588
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• 2015

Flexible tactile sensors can provide valuable feedback to intelligent robots regarding the environment around them. This is especially important when robots such as, service robots share a workspace with humans. This paper presents a contact force measurement algorithm of a flexible tactile sensor. This sensor is manufactured by a direct-writing technique, which is one 3D printing method, using multi-walled carbon nano-tubes. An analog signal processing circuit has been designed and implemented to reduce noise contained in the sensor output. In addition, a digital version of the Butterworth filter was implemented by software running on a microcontroller. Through various experiments, characteristics of the sensor system have been identified. Based on three traits, an algorithm to detect the contact and measure the contact force has been developed. The entire system showed a promising prospect to detect the contact over a large and curved area.