• The Journal of the Acoustical Society of Korea
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• v.28 no.2
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• pp.127-134
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• 2009

In this study, possibility of the laser eavesdropping is investigated on the window glasses with various thicknesses, Glass windows are excited by maximum length sequency (MLS) signal and the vibration sound is detected by a laser doppler vibrometer. From the detected sound, speech intelligibility is objectively estimated. Speech transmission index (STI), which is based on the modulation transfer function (MTF). is calculated for the estimation. Finally, disturbing wave effect on the speech intelligibility is analysed by using an outside speaker and a window shaker attached on the glass window. The purpose of the study is to estimate the possibility of remote eavesdropping by the laser sensor and to evaluate the performance of the homemade window shaker to protect from the remote eavesdropping.

• The Journal of the Korea Contents Association
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• v.22 no.2
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• pp.35-43
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• 2022

The 2020 Gwangju Media Art Festival (2020 GMAF) was held in the area of the National Asian Cultural Center. Under the slogan "The entire Gwangju shines under the theme of "Aesthetics of Light and Coexistence," the media festival demonstrated projection mapping to Jeonnam (former) Provincial Office at the DATA+ Research Institute of Chung-Ang University's Graduate School of Advanced Video. This paper focuses on explaining the overall production process and content development of projection mapping demonstrated in the Jeollanam-do Provincial Government, which is a symbol of Korean democratization and is located in the center of Gwangju, Jeolla-do. It was intended to faithfully express the history of the 2020 GMAF and Jeonnam (former) provincial government, Gwangju's history, and democratization records. It was intended to show images, background sounds, sound effects, and visual effects using various special effects and high-power laser devices using unique characteristics of projection mapping. To this end, about 5 minutes and 30 seconds of content were planned, and it was divided into parts and topics, and one individual story was developed for each chapter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.551-556
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• 2008

Possibility of the remote eavesdropping through window glass is investigated using a laser sensor. Various thicknesses and types of glass windows are excited by maximum length sequency (MLS) signal and the vibration sound is detected by a laser doppler vibrometer. Intelligibility of the detected sound is evaluated using the speech transmission index (STI), which is based on the modulation transfer function (MTF). In order to identify the disturbing effect, different level of disturbing wave is generated by an outside speaker and a window shaker attached on the glass window. On the different thickness of glass windows, decrease effect of the speech intelligibility is analysed.

• The Science & Technology
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• v.30 no.9 s.340
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• pp.16-17
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• 1997

감시장치가 보편화되어 이제는 은행 등 공공시설이나 가정에서 CCTV를 통해 범죄예방과 범인정체 파악에 활용되고 있으며 교통위반과 고용인 생산활동감시수단으로도 이용되고 있다. 이 CCTV는 유선과 무선 2종이 있는데 흑백은 15~30만원, 컬러는 30~1백만원이며 구입할 수 있다. 그런데 가장 발전된 도청은 장치없이 레이저광선을 쏘아서 대화내용을 잡아내는 방법으로 개발되어 실용화되고 있다.

• The Journal of the Acoustical Society of Korea
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• v.26 no.1
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• pp.8-15
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• 2007

Speech intelligibility of the eavesdropping sound is investigated on a acoustic cavity - glass window coupled system. Using MLS (Maximum Length Sequency) signal as a sound source, acceleration and velocity responses of the glass window are measured by accelerometer and laser doppler vibrometer. MTF (Modulation Transfer Function) is used to identify tile speech transmission characteristics of the cavity and window system. STI (Speech Transmission Index) based upon MTF is calculated and speech intelligibility of the vibration sound of the glass window is estimated. Speech intelligibilities by the acceleration signal and the velocity signal are compared. Finally, intelligibility of the conversation sound is confirmed by the subjective test.