• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.8-13
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• 2001

It has been well known that cross-talk canceller for 3D audio using loudspeakers depends on a listeners position called the sweet-spot. Therefore, new cross-talk canceller was proposed that increases robustness to perturbations such as head movement, reverberations, and different head shapes. It was made up 3 loudspeakers structure to be combined with symmetric and asymmetric speaker geometry. In this paper, we propose new cross-talk canceller using 2 loudspeakers having the same efficiency as existing cross-talk canceller using 3 loudspeakers. The results of the study is verified through the listening tests and also presented a cross-talk cancelling methods for improved 3-D audio production in details.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1909-1910
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• 2008

본 논문에서는 실린더 모델을 이용하여 머리의 다양한 포즈 변화와 조명 변화에 대해 강인한 얼굴 인식을 제안하고자 한다. 실린더 모델은 사람의 머리가 실린더 모양과 유사하고 그 표면은 얼굴에 해당된다고 가정한다. 실린더 모델은 6가지의 모션 파라메터를 따라 움직이며 Lucas-Kanade 알고리즘에 의해 모션 파라메터의 양을 결정한다. 강인한 동작을 위해 템플릿을 지속적으로 바꿔주는 동적 템플릿(dynamic template)방법과 그에 따른 에러가 누적되는 것을 막기 위해 re-registration방법을 사용한다. 조명 문제를 해결하기 위해 템플릿에서 조명 주성분 벡터를 추출하여 제거하는 방법으로 조명 효과를 제거한다. 실험에서는 다양한 포즈 변화와 조명 변화가 반영된 얼굴 데이터베이스를 구축하고 추출한 텍스쳐 맵(texture map image)을 SVM에 적용함으로서 포즈, 조명 변화에 강인한 얼굴인식을 보인다.

• Journal of Korea Multimedia Society
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• v.8 no.11
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• pp.1421-1431
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• 2005

There are two methods in 3-D sound reproduction: a surround system, like 3.1 channel method and a binaural system using 2-channel method. The binaural system utilizes the sound localization principle of a human using two ears. Generally, a crosstalk between each channel of 2-channel loudspeaker system should be canceled to produce a natural 3-D sound. To solve this problem, it is necessary to trace a head movement. In this paper, we propose a new algorithm to correctly trace the head movement of a listener. The Proposed algorithm is based on the detection of face and eye. The face detection uses the intensity of an image and the position of eyes is detected by a mathematical morphology. When the head of the listener moves, length of borderline between face area and eyes may change. We use this information to the tracking of head movement. A computer simulation results show That head movement is effectively estimated within +10 margin of error using the proposed algorithm.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.317-322
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• 1982

The biting behaviors of tuna were studied based on the remains of saury (Cololabis saira), which was used as bait, in the stomach contents of tuna. The saury remains were classified into four segmental groups (A-segment: Whole fish; B-segment: anterior partion with head: C-segment: middlepart without both head and tail: D-segment : posterior part without head). The tuna stomachs were independently named and grouped into three subsamples according to bait segments remaining in the stomach. The subsamples have the extra number of the stomach-naming segments and the distributions of the bait tegments are biased from tile random distribution. The distribution of the bait segments except the extra segments are hypothetically assumed to be random, and was subjected to the chi-square test of significance. The inferred conclusions are as follows:1. Most of the tuna having the B-segment had previously taken the C and/or D-segment. 2. The catchability of the yellowfin tuna having the B-segment seems higher than that of the fish having the A-segment in the stomach. 3. Tuna which had two or more bait heads should have taken the extra bait heads without being hooked detaching the head from the hook by biting the Posterior porting of tile bait.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.199-202
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• 2001

본 논문에서는 3D사운드 생성 기술 중 대표적인 방법인 원음에 HRTF(머리전달함수)를 콘볼루션(convolution)하는 방식으로 음상정위 모듈을 구현하였으며 음장감을 부여하기 위하여 잔향(reverberation) 효과를 추가하고 크로스토크 현상을 제거하기 위하여 트랜스오럴 필터를 추가하였다. 본 논문에서는 sampling rate conversion을 사용하여 decimation과 interpolation을 수행하여 44.1KHz의 sampling rate로 된 coefficient를 downsample하거나 upsample한 HRTR(머리전달함수)를 사용하여 콘볼루션(convolution)을 수행했다. 본 논문에서는 3D사운드 생성과정에서 필요한 연산과정을 최소화하여 일반 PC의 computing power로도 sampling rate conversion된 데이터를 처리하여 줄 수 있는 알고리즘을 제시하고 구현하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.02a
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• pp.139-142
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• 2008

헤드폰 또는 이어폰으로 오디오 청취 시 흔히 음상이 머리 내부에 맺히는 현상이 발생하게 되며, 이러한 현상을 음상 내재화(Inside Head Localization; IHL)라 한다. 오디오의 음상이 머리 주변 혹은 머리 내부에 맺히게 되면 공간감이나 입체감이 떨어지게 되어 음향의 현실감을 저하시키게 되며 또한 청취에 따른 피로도가 증가하게 된다. 이러한 음상 내재화 현상을 제거하여, 헤드폰/이어폰을 통해 오디오 청취 시 음상이 머리의 외부에 맺히도록(Out of Head Localization; OHL) 하는 기술을 음상 외재화(Sound Externalization) 기술이라 한다. 룸 임펄스 응답이 방향 큐와 연계하여 생성되었을 경우 외재화가 가능하다는 실험적 사실을 바탕으로 기존의 음상 외재화 방법은 일반적인 HRTF (Head Related Transfer Function)를 이용하여 외재화 필터를 구성해왔다. 본 논문에서는 구체마이크로폰을 이용하여 녹음한 멀티채널 룸 임펄스 응답을 기반으로 모델링 된 외재화 필터를 이용한 음원 외재화 방법을 제안한다. 또한 실험 및 결과 분석을 통하여 본 알고리즘의 전방 음원 외재화 성능의 우수성을 입증하고, 외재화 알고리즘 적용 후의원 신호 음상 보존 성능을 확인한다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.11a
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• pp.163-167
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• 1998

스테레오로 생성된 음향을 헤드폰을 사용하면 좌,우의 소리는 각각 좌,우의 귀로 상호 혼선 없이 전달된다. 그러나 2개의 스피커를 사용한다면 좌,우의 소리가 혼합되어 들린다. 이러한. 혼합현상을 크로스톡이라 하며, 이 경우 본래의 소리는 변질되어 들린다. 이러한 현상을 방지차기 위해 스피커로 재생하기 전 신호를 크로스톡 제거기를 통해 한번 더 처리하는 방법을 사용한다. 여기에 사용되는 크로스톡 제거기는 2개의 스피커와 청취자간의 상대 위치, 그리고 스피커와 청취자가 있는 방의 음향특성에 의해서 적절히 변화되어야 한다. 본 연구에서는 방의 음향특성이 무향실과 같다고 가정하고 2개의 스피커와 청취자간의 상대적인 위치가 주어졌을 때 효과적으로 크로스톡 제거기률 생성해주는 알고리듬을 제시하였다. 제안된 방법은 머리전달함수를 기반으로 하여 스피커가 청취자로부터 표준반경에 위치하였을 때의 크로스톡 제거기률 데이터 베이스화 하여 일반적인 거리에 위치하였을 경우에도 실시간으로 확장 적용할 수 있다.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.387-392
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• 2017

When an infant has visited a hospital due to skull fracture, the rupture of a blood vessel, or skin wounds on the head resulted from an incident, accident, traffic accident, or disease, he/she becomes to undergo anterior/posterior and lateral skull imaging, which is a head test at the department of radiology. In the head test, if the adult skull imaging grid is applied to the imaging, the secondary radiation will be removed to enhance the contrast of the image. However, among the radiation exposure conditions, the tube voltage should be enhanced by 8~10 kVp leading to an increase in the patient exposure. The present study was conducted under assumption that if the same images can be obtained from infant skull imaging without using the skull imaging grid, the exposure dose will be reduced and the artifacts due to grid cut off can be prevented. The researcher measured the radiation dosage using a radiation meter and conducted the subjective evaluation (ROC, receiver operating characteristic) among medical image evaluation methods. Based on the results, when the images were taken without using the grid, the exposure dose was reduced by 0.019 mGy in the anterior/posterior imaging and by 0.02 mGy in the lateral imaging and the image evaluation score was higher by 4 points. In conclusion, if the images of the skulls of infants that visited the hospital are taken with out using the grid, the exposure dose can be reduced, the image artifacts due to grid cut off can be prevented, and the lifespan of the X-ray tube will be extended.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.1
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• pp.51-56
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• 2019

This paper proposes an improved heartbeat signal extraction method for ballistocardiography(BCG)-based heart-rate measurement on mobile environment. First, from a mobile facial video, a handshake-free head motion signal is extracted by tracking facial features and background features at the same time. Then, a novel signal periodicity computation method is proposed to accurately separate out the heartbeat signal from the head motion signal. The proposed method could robustly extract heartbeat signals from mobile facial videos, and enabled more accurate heart rate measurement (measurement errors were reduced by 3-4 bpm) compared to the existing method.

• The Journal of the Acoustical Society of Korea
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• v.24 no.3
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• pp.133-140
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• 2005

Crosstalk canceller in stereo channel audio reproduction system has the purpose to deliver desired signals exactly at the listener's ear. Generally. it has a Poor performance in low frequency bands. Frequency-warped Otters are used to provide improved performance in crosstalk canceller for these problems. However. such filters are more complex to implement than conventional filters. This paper presents an efficient method for low-order IIR approximation of frequency warped crosstalk cancellation filters using Pole-zero dewarping. The method preserves the advantages of frequency warping, but has a computational complexity that is similar to the conventional method. This Paper also presents a series of experiments that validate the method of crosstalk canceller.