• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1158-1166
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• 2013

SAR calculation method following the Mobi-Kids study protocol is analyzed and evaluation method of cumulative RF dose from mobile phones which have been used by a subject of case and control groups is proposed. An SAR database is built by calculating SAR distributions in 4 head models at different ages for representative phone models with the same conducted power. To obtain SAR distribution in a subject's head for a specific commercial phone which had/have been used by him/her, an SAR correction factor using SAR compliance test results is determined. Cumulative dose is calculated by considering mobile phone characteristics and use pattern such as call time and laterality(right and left).

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.4
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• pp.9-18
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• 2011

In this paper, we propose a method which recognizes human activity using model-based gaze direction estimation in an indoor environment. The method consists of two steps. First, we detect a head region and estimate its gaze direction as prior information in the human activity recognition. We use color and shape information for the detection of head region and use Bayesian Network model representing relationships between a head and a face for the estimation of gaze direction. Second, we recognize event and scenario describing the human activity. We use change of human state for the event recognition and use a rule-based method with combination of events and some constraints. We define 4 types of scenarios related to the gaze direction. We show performance of the gaze direction estimation and human activity recognition with results of experiments.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.334-337
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• 2003

입체음향을 구현하는 방법에는 5 혹은 6 개의 스피커를 사용하는 5.1 채널 음향재생 시스템과 2개의 스피커를 사용하는 방법있다. 2 채널 입체음향재생 시스템은 라우드 스피커 재생보다 헤드폰 재생에 사용되고 있다. 2 채널로 입체음향을 재생하기 위하여 사람의 머리와 귀바퀴를 FIR 필터로 모델링한 머리전달함수(HRTF, head related transfer function)을 이용한다. FIR 필터로 측정된 HRTF는 실시간 처리에 있어서 계산량이 많은 단점이 있다. 본 논문에서는 2 채널 입체 음향시스템을 효과적으로 구현하기 위하여 FIR HRTF를 HR필터로 구현하는 방법을 제안한다. FIR 필터계수로부터 IIR 필터계수를 구하는 알고리즘은 균형화 모델 감소법(balanced model reduction)을 이용한다. 본 논문에서는 IIR 필터로 차수를 줄인 HRTF로 입체음향을 재생하는 시뮬레이션을 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.711-714
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• 2000

가상현실은 현실에 구애받지 않고 상상의 세계를 현실과 같이 만들어 내어 인체의 모든 감각기관이 인위적으로 창조된 세계에 몰입됨으로써 현실에 있는 것처럼 느낄 수 있는 사이버스페이스이다. 본 논문에서는 청취자의 머리움직임에 따라 머리 추적기로부터 수신된 정보로서 음향의 방향감 간의 상관모델을 구성하여 시스템내의 S/W 모듈에 전달하는 인터페이스와 이를 토대로 머리 움직임 변화에 부합되는 실감음향을 생성하고, 영상도 함께 동기화하여 몰입감을 증대시키는 실감음향 인터페이스에 대해서 논의한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.934-938
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• 2008

To customize individual characteristics of HRTF, a spherical model has been used for structural modeling technique. A pseudo-code of prolate spheroidal HRTF caused by incident acoustic point source is already developed, and it can be used a head shadow filter for structural modeling of HRTF. In this research, to see the necessity and efficiency of spheroidal head modeling, ITD optimization is performed on CIPIC HRTF database. From given cost function, ITD-optimized spheroidal head model, whose ITD information is the most matched version of measured ITD information, is found by varying head parameters subject by subject. By comparing results of ITD-optimized spheroids and ITD-optimized spheres, we concluded that a spherical head model is more efficient way of generating head shadow effect than a spheroidal head model does.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.65-68
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• 1994

시각자극에 의해 머리표면에서 발생하는 Transient Evoked Potential을 검출하여 Source Tracing Method를 이용하여 뇌의 시각인지영역을 추정하였다. 본 과정에서 TEP검출방식은 average method를 이용하였고, 신경흥분에 대한 물리적 모델로 Single Current Dipole Model을 이용하고, 머리기하에 대한 3중구각모델을 이용하여 Forward Problem을 풀었다. Inverse Problem은 current dipole의 6개의 parameter에 대한 Least Square Error Method를 이용하여 신경흥분의 위치를 추정하였다. 이러한 결과와 생리학적으로 밝혀진 시각경로와의 비교결과 유사성이 확인되었다.

• Proceedings of the KIEE Conference
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• 1986.07a
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• pp.205-208
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• 1986

• The Journal of the Acoustical Society of Korea
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• v.23 no.1
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• pp.30-39
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• 2004

This study aims at establishing a digital signal processing technique to control 3-D sound localization, especially focusing our ores on the role of information provided by Head-Related Transfer Function (HRTF). In order to clarify the cues to control the auditory distance perception, two conventional models named Hirsch-Tahara model and auditory parallax model were examined. As a result, it was shown that both models have limitations to universally explain the auditory distance perception. Hence, the auditory parallax model was extended so as to apply in broader cases of auditory distance perception. The results of the experiment by simulating HRTFs based on the extended parallax model showed that the cues provided by the new model were almost sufficient to control the perception of auditory distance from an actual sound source located within about 2m.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.40-47
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• 2021

In this study, the structural behavior by the details of the lap region with the headed bar was estimated through finite element analysis. To solve the finite element analysis of the anchorage region with complex contact conditions and nonlinear behavior, a quasi-static analysis technique by explicit dynamic analysis was performed. The accuracy of the finite element model was verified by comparing the experimental results with the finite element analysis results. It was confirmed that the quasi-static analysis technique well reflected the behavior of enlarged headed bar connection. As a result of performing numerical analysis using 21 finite element models with various development lengths and transverse reinforcement indexes, it was confirmed that the increase of development length and transverse reinforcement index improved the maximum strength and ductility. However, to satisfy the structural performance, it should be confirmed that both design variables(development length and transverse reinforcement index) must be enough at the design criteria. In the recently revised design standard(KDS 14 20 52 :2021), a design formula of headed bar that considers both the development length and the transverse reinforcing bar index is presented. Also the results of this study confirmed that not only the development length but also transverse reinforcing bars have a very important effect.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.96-100
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• 2006

We develop the Dual Head Star Tracker (DHST) to obtain the attitude information of science and Technology Satellite2 (STSAT-2). Because most of star sensor has only one head camera, star recognition is impossible when camera point to sun or earth. We therefore considered the DHST which can obtain star images from two spots simultaneously. That is, even though we fail a star recognition from an image obtained by one camera, it is possible to recognize stars from an image obtained by the other camera. In this paper, we introduce engineer model (EM) of the DHST and propose a star recognition and a star track algorithm.