• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.462-467
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• 2000

The aim of this study is to provide fundamental data for acoustic design by analyzing the room acoustic characteristics according to the PA system used in the school gymnasium. The measurements were carried out accordance with the ISO 3382. The sources used in this study were four types; omni-directional, centralized, distribution, the combination of centralized and distribution sound source system. Omni-directional system is recommended by ISO for the acoustic test and the others are installed on the wall, column and ceiling in the school gymnasium for sound reinforcement.

• Journal of IKEEE
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• v.25 no.4
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• pp.591-597
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• 2021

This paper proposes an EMC-aware PCB design method to reduce electromagnetic emission, where trace length and teturn path of critical signal are shortened by changing chip location and trace layout on the PCB, while additional filters or decoupling capacitors are not required. In the proposed method, signal velocity is calculated for various signals on the PCB. Critical signal with the fastest signal velocity is determined and its return path is shortened as much as possible by placing chip location and trace routing first. Return path of critical signal should be carefully designed not to have discontinuity. Power plane and ground plane should be carefully designed not to be divided, since these planes are the reference of return path. The proposed method was applied to automotive directional Bluetooth speaker which failed to pass CISPR 32 and CISPR 25 EMC tests. Its PCB was redesigned based on the proposed method and it easily passed the EMC tests. The proposed method is useful to EMC-sensitive electronic equipments.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.643-644
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• 2022

시청각 중복 장애인은 타인과 의사소통에 어려움이 있기 때문에 이에 대한 연구가 필요하다. 본 논문에서는 시청각 중복 장애인이 타인과 실시간 의사소통이 가능한 팔목 보호대 형태의 Google Cloud Speech API 기반 점자 단말기를 제안한다. 점자 단말기에는 심박, 온도, 인바디 센서를 부착하여 착용자의 건강상태를 분석한다. 또한 타인과 실시간 소통을 위해 점자 출력 닷 셀 6 개와 점자 입력버튼을 2 × 3 형태로 배치하여 STT 를 통해 타인의 음성을 점자형태로 출력하여 읽거나 점자를 입력하여 TTS 를이용해 타인에게 스피커를 통해 의사를 전달할 수 있다. 이를 통해 시청각 중복 장애인들은 타인과 실시간 의사소통과 정보 취득에 자유로워질 수 있다.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.2
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• pp.132-136
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• 2010

Psychophysical experiment was performed to investigate how audio-visual spatial disparity affects on perceptual space in peripheral vision. In the experiment, participants were exposed to two stimuli of vision and sound which comes simultaneously from different directions, respectively. The visual stimulus was implemented by 7 white LEDs which were located at an equal distance with 7 different angles of $-70^{\circ}$, $-40^{\circ}$, $-20^{\circ}$, $0^{\circ}$, $20^{\circ}$, $40^{\circ}$, and $70^{\circ}$ from the right front. Those audial stimuli were also implemented by loudspeakers which were placed at 9 different directions equally spaced by $5^{\circ}$ ranged from $-20^{\circ}$ to $20^{\circ}$. Each participant then evaluated spatial disparity between visual and audial stimuli with 5 levels of response, in which the higher level indicates the larger gap. When the visual stimulus is applied from the right, the results show that the response level gets higher for a larger angle between visual and auditory stimuli. A similar tendency for the visual stimulus with $0^{\circ}$ orientation was also be observed. On the other hand, when the visual stimulus is applied from the left, the response level gets lower for the larger angle.

• Journal of Broadcast Engineering
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• v.27 no.1
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• pp.91-103
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• 2022

Determination of sound source characteristics such as: sound volume, direction and distance to the source is one of the important techniques for unmanned systems like autonomous vehicles, robot systems and AI speakers. There are multiple methods of determining the direction and distance to the sound source, e.g., using a radar, a rider, an ultrasonic wave and a RF signal with a sound. These methods require the transmission of signals and cannot accurately identify sound sources generated in the obstructed region due to obstacles. In this paper, we have implemented and evaluated a method of detecting and identifying the sound in the audible frequency band by a method of recognizing the volume, direction, and distance to the sound source that is generated in the periphery including the invisible region. A cross-shaped based sound source recognition algorithm, which is mainly used for identifying a sound source, can measure the volume and locate the direction of the sound source, but the method has a problem with "blind spots". In addition, a serious limitation for this type of algorithm is lack of capability to determine the distance to the sound source. In order to overcome the limitations of this existing method, we propose a QRAS-based algorithm that uses rectangular-shaped technology. This method can determine the volume, direction, and distance to the sound source, which is an improvement over the cross-shaped based algorithm. The QRAS-based algorithm for the OSSD uses 6 AITDs derived from four microphones which are deployed in a rectangular-shaped configuration. The QRAS-based algorithm can solve existing problems of the cross-shaped based algorithms like blind spots, and it can determine the distance to the sound source. Experiments have demonstrated that the proposed QRAS-based algorithm for OSSD can reliably determine sound volume along with direction and distance to the sound source, which avoiding blind spots.

• Science of Emotion and Sensibility
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• v.10 no.3
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• pp.331-342
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• 2007

This study focused on developing MP3 smart clothing products and usability evaluation. MP3 smart clothing which was developed in this study contains e-textile keypad and a kit. The kit consists of MP3 Player, remote controller module and ear phone, and are easy to assemble and dismantle. And usability evaluation about MP3 smart Clothing which was developed in this study contains e-textile keypad and a kit. For making the MP3 Smart clothing, e-textile signal line and keypad was developed and a metal connection ring also was manufactured to adhere closely e-textile signal line to keypad. The last products are two kinds of MP3 smart clothing, jacket style of MP3-YSJ(Yonsei Smart Jacket) and safari style of MP3-YSS(Yonsei Smart Safari). Then usability evaluation conducted two times about MP3 smart clothing developed. Usability evaluation is classified by a module evaluation and an item evaluation. The module evaluation measured external appearance, material, a music controller, an ear phone(or a mini speaker) and connector. The item evaluation measured social acceptance, feeling of wearing, utility, easiness of maintenance and safety. The module evaluation described totally positive results in the first usability evaluation about MP3-YSJ 1.0 and MP3-YSS 1.0. The item evaluation shows a lower score in the social acceptance, especially the easiness of connector maintenance and the social acceptance of music-controller in MP3-YSJ 1.0 and MP3-YSS 1.0. The second usability evaluation conducted with improved products by the first usability test results. Results from second item evaluation indicated needs to improve the easiness of connector & music-controller maintenance and the social acceptance of music-controller in MP3-YSJ 2.0. In MP3-YSS 2.0, the easiness of material management and the social acceptance of music controller & connector needed to improvement. In particular, users felt inconvenience in the social acceptance because of e-textile keypad arrangement. To outweigh this disadvantage, further study is needed about keypad interface of the music controller.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.3
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• pp.215-221
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• 1976

In this study, noise arresting effect of the noise control room from the transmission of surrounding noise was tested when the packing noise control rooms were set up in the test room in which the prerecorded noise from an engine room was reradiated at the same level as the original pressure. The inner space of control room A is $3.389m^3(1.19\times1.19\times2.14m)$ having walls furnished with plywood board 9mm in thickness and noise control room door$(60\times45cm) $ and illumination lamp are placed. In case of the control room B, noise absorption board(10mm fiber board which holds the corntype concavity with diameter of 5mm, depth 5mm, space 15mm) is adhered to the internal ceiling and styrol foam boards(20mm) to the walls. The other struction is same as the control room A. Type C is the same as B except wool board(Glass Fiber, 33mm) on the walls. Type D is same as type A except that the thickness of wall is 12mm and wood pyramid type cone$(5\times5\times13cm)$ is adhered to the ceiling ana walls(Fig. 1). When the recorded noise and vibrated noise were controlled in various levels. The noise pressure which passed through the control rooms was measured by sound level meter(Bruel & Kjar 2205, measuring range 37-140dB). In order to calculate the absorption rate in the control rooms the noise pressure was measured at different distances when the recorded noise pressure was radiated. The followings are the results obtained from the experiment. 1. When the noise pressure of the test room was 60dB, transmission rate of type A was $69.7\%$ and increased $3.3\%$ per 10dB. At the same condition, the rate was $53.9\%$ and increased $4.5\%$ per 10dB in type D. Type D was the most effective in noise arresting of the four and the effect was D,C,B and A in order(Fig.2). 2. When the oscillator sound and vessels noise were radiated in 1,000Hz, at one meter distance to the type A and D, the oscillator sound pressure were 77dB and 73dB, while the vessels noise pressure were 73.3dB and 66.2dB respectivley(Fig.3). 3. Refering to the influence of the frequency to the lower oscillator sound(1,000Hz) pressure, both type C and D were almost same at 140cm but type C was 0.3dB lower than type D at 20cm distance(Fig.4).