• Journal of the Korea Society of Computer and Information
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• v.20 no.8
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• pp.7-13
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• 2015

Recently, there are serviced user customized advertisement of various type using smart device. Representative services are advertisement service using light of smart TV screen or audible sound of smart TV to transmit advertisement information. However, those services have to do a specific action of smart device user for advertisement information or need audible audio information of TV contents. To overcome those weakness, therefore, we propose an advertisement method using inaudible sound of speaker based on smart device. This method supports the transfer of advertising content to the smart device user with no additional action or TV audio signal required to access that content. The proposed method used two high frequencies among 18kHz ~ 22kHz of audible frequency range which smart TV can send out. And it generates those frequencies synthesized with audio of TV contents as trigger signal which can send advertisements to smart device. Next, smart device analysis the trigger signal and request advertisement contents related to the signal to server. After then, smart device can show the downloaded contents to user. Because the proposed method uses the high frequencies of sound signals via the inner speaker of the smart device, its main advantage is that it does not affect the audio signal of TV content. To evaluate the efficacy of the proposed method, we developed an application to implement it and subsequently carried out an advertisement transmission experiment. The success rate of the transmission experiment was approximately 97%. Based on this result, we believe the proposed method will be a useful technique in introducing a customized user advertising service.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.191-197
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• 2017

According to the ubiquitous usage of smartphone, so many smartphone applications have been developed, and especially data communications and position measurement technologies without additional equipments have been developed using acoustic signal. But there is a limitation to select the frequency of the acoustic signal due to the smartphone hardware, and there is non-linearity in the electronic circuits in a sound generation devices, the audible sound generated from the speaker is not avoidable. And it causes critical difficulty to the commercial system deployment. In this paper, a simulation technique to calculate the power of the audible acoustic signal by human is applied to several types of acoustic signals to evaluate the loudness. These could be referred when the acoustic communications or positioning systems are designed, for the purposed of inaudible sounding to human.

• Language and Information
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• v.10 no.1
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• pp.1-20
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• 2006

We can distinguish two different groups of 'fusion expressions' depending on whether the verb (-ko) ha- 'do' can be recovered from the contracted expression concerned or not: recoverable and unrecoverable fusion expressions. Many expressions belonging to the former group show alternations between the [da]-type and the [dae]-type: e.g., o-nta-nta and o-ntae-nta '...says... is coming.' On the other hand, some expressions like ka-ntae can only be realized as the [dae]-type. The main purpose of this paper is to account for these [dae]-type expressions. First, we assume that they have an inaudible/invisible quotation $verb\;{\phi}-$, which takes as its complement a verb phrase with a neutral speech-level ending. This quotation verb is derived from the quotation verb ha-. Second, we assume that the quotation $verbs\;{\phi}-$ and ha- have the [j] sound as their stem-final element, which means that these verbs are actually represented as ${\phi}-j-$ and ha-j-, respectively. In this system, the [tae]-type expressions come out naturally from the behavior of the [j] sound. We do not employ any ad hoc phonological rules to derive the [dae]-type expressions from the corresponding [da]-type expressions.

• Journal of the Society of Disaster Information
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• v.13 no.1
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• pp.51-58
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• 2017

This paper proposes a direction estimation scheme with directional speaker and smart device for evacuation guidance. When there is worst disaster environment filled with smoke and noisy sound, evacuee can not get any information about evacuation routes. The proposed scheme can be used for detecting evacuation routes with audible and inaudible signal from directional speaker. At this point, evacuee can get evacuee guidance by using smartphone application that the proposed scheme is applied. The performance of the proposed scheme is evaluated by experiment with three different types of smart devices in large indoor environment. The purpose of experiment is to detect the direction of transmitted signal from directional speaker. Therefore, The experiment is conducted by analyzing the strength of transmitted signal by distance. The experimental results show that even if the smart device is located up to 20m away from the speaker, it is possible to detect the sending direction of the signal. We confirmed the possibility of the proposed technology in 8kHz and 20kHz signal detection by smart device.

• Journal of the Korea Society of Computer and Information
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• v.20 no.12
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• pp.83-90
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• 2015

In this paper, we propose a new method for multi transmission method of data among near smart devices. Existing methods require the use of an extra application service where the operating system differs between smart devices. In contrast, the proposed method makes use of the smart device's inner speaker and microphone to confirm the transmission signal. Then, real sharing data is transmitted via WiFi or LTE. Therefore, the proposed method overcomes operating system issues with existing methods. Besides, BUMP technology works in a similar way to the method we propose, it only supports one-to-one transmission. To evaluate the efficacy of the new method, we tested one-to-many data transmission in an experiment: the results showed a 96% success rate. As a result, we believe that the proposed method is an effective multi transmission method of data among near smart devices.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.109-110
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• 2019

사물인터넷(IoT: Internet of Things)과 스마트 홈은 사용자의 명령 없이 사물에 다양한 센서를 부착해 실시간으로 네트워크상에서 데이터를 상호교환하는 기술로 발전하고 있다. 특히 각종 기기들이 개발됨에 따라 데이터 공유와 강화된 서비스 기술이 요구되고, 기기들을 연결하기 위한 간단한 무선통신 기술이 중요하다. 본 논문에서는 스피커와 마이크를 이용하여 기기 간 비가청 음파통신방법을 제안한다. 사용자의 귀에는 잘 들리지 않으며, 통신이 자유롭게 이루어지기 위해 16kHz~21kHz 주파수대역의 비가청 음파를 사용하여 송·수신한다. 또한, 다른 신호들의 충돌과 잡음, 간섭을 대비하기 위해 이중주파수를 사용한다. 본 시스템은 단일주파수와 비교하여 더 많은 기기 간 통신이 가능하게 해주며, 3m 안에서 높은 통신 속도와 정확도를 제공한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.343-344
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• 2015

본 논문에서는 비가청주파수 소리신호를 사용하는 데이터 전송 기법을 제안한다. 제안하는 방법은 각 비트에 매핑된 특정 주파수를 혼합하여 신호를 전송함으로써 동시에 여러 비트를 전송할 수 있다. 그리고 인접한 주파수 신호의 간섭으로 인한 데이터 에러를 검출하기 위해 순환 중복 검사 기법을 사용함으로써 데이터 전송 정확도를 높인다. 이 기법은 기존 전송 속도의 한계로 제한된 분야에서만 사용했던 비가청주파수 무선 통신 기법을 더 다양한 분야에 활용할 수 있을 것이다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1193-1197
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• 2005

The low frequency noise below 200 Hz, including inaudible infra-sound, is known to affect human physiology ; circulation, respiration, nerve, endocrine, etc. Legislation has been introduced in several countries regarding evaluation guideline and measurement method of low frequency noise. In this work, low frequency characteristics of the Seoul subway transportation system was investigated in terms of the noise level and spectrum in the interior of running passenger car and the subway station. The interior sound pressure level of the passenger car was between 60 and 105 dB in the frequency range of $1{\sim}200\;Hz$ and varied with car speed. The marked sound pressure level peak at 8 Hz, infra-sound, observed for the most of Lines is shown to correspond to the resonance frequency of passenger car. The level of station platform noise was lower than the interior noise of running car because of the lower speed at arriving/departure. The results indicated that the interior noise level of running passenger car was inside the oppressive feeling region, proposed by Ochiai, in the frequency range of $20{\sim}80\;Hz$ which makes a little concern.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.1
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• pp.68-77
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• 2020

The shipbuilding and offshore industry is a large and complex assembly industry, which causes many safety accidents. The major accidents in the shipbuilding and offshore industry workplaces are stenosis, falling objects, dust, fire, explosions, and gas poisoning. The accident by worker in this industry mainly has three factors: frequent movement, narrow work space, and increased use of subcontractors. To control these factors, it is necessary to monitor the worker's location and work status. In this paper, a worker location monitoring system using inaudible sound wave was designd that can be used in environments with many metal barriers. The process included deriving stakeholder requirements, transforming to system requirements, designing system architecture, and developing prototype. The prototype was validated by third-party testing agency. As a result, it satisfied the designed performance and verified its feasibility.

• Economic and Environmental Geology
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• v.39 no.4 s.179
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• pp.495-505
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• 2006

Atmospheric infrasound is defined as low frequency inaudible sound waves generated from natural phenomena and human activities. One property of long-distance travelling of infrasound makes it possible to detect the wave propagated from remote sound sources and to understand many geophysical phenomena generating it. Recently, advanced global infrasound sensor arrays are being deployed to monitor the clandestine nuclear test and to study geophysical phenomena in the world. In Korea, five seismo-acoustic arrays consisting of co-located seismometer and micro-barometer have been operated to discriminate the artificial explosions from the natural earthquakes in and around the Korean Peninsula. In addition to the discrimination purpose, these ways also record distinct infrasonic signals from natural phenomena on global scale such as large earthquake, bolide event, volcanic explosion, typhoon, and so on. As a new frontier in monitoring the earth, infrasound is being applied to understand various phenomena in and above the earth's surface.