• International journal of advanced smart convergence
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• v.12 no.4
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• pp.260-267
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• 2023

Due to the development of science and technology in the 4th Industrial Revolution, a variety of content is being developed and utilized through educational courses linked to digital textbooks. Students use smart devices to engage in realistic virtual learning experiences, interacting with the content in digital textbooks. However, while many realistic contents offer visual and auditory effects like 3D VR, AR, and holograms, olfactory content that evokes actual sensations has not yet been introduced. Therefore, in this paper, we designed and implemented 4D educational content by adding the sense of smell to existing content. This implemented content was tested in classrooms through a curriculum-based evaluation. Classes taught with olfactory-enhanced content showed a higher percentage of correct answers compared to those using traditional audio-visual materials, indicating improved understanding.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1237-1242
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• 2014

The functions of playing musics and multimedia have become essential in one device as a smart phone since the smart phone appeared. It is very convenient, but it contains controversial arguments about sound quality, so many smart phone users use the music player application. By using these music applications, people start to think about the relationship between music playing and sound quality. However, those applications are not perfect, so it is hard to choose a good application. This thesis is about the advantages of the sound quality of music player applications that are currently sold in Android Market through RightMark Audio Analyzer program, and plans to suggest android music player application system design by analyzing applications by covering disadvantages of these applications.

• Journal of Internet Computing and Services
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• v.11 no.6
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• pp.21-29
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• 2010

In this paper, we propose the system which detects the speaker, who is speaking currently, among a number of users. A proposed speaker detection system based on stereo vision and audio is mainly composed of the followings: a position estimation of speaker candidates using stereo camara and microphone, a current speaker detection, and a speaker information acquisition based on a mobile device. We use the haar-like features and the adaboost algorithm to detect the faces of speaker candidates with stereo camera, and the position of speaker candidates is estimated by a triangulation method. Next, the Time Delay Of Arrival (TDOA) is estimated by the Cross Power Spectrum Phase (CPSP) analysis to find the direction of source with two microphone. Finally we acquire the information of the speaker including his position, voice, and face by comparing the information of the stereo camera with that of two microphone. Furthermore, the proposed system includes a TCP client/server connection method for mobile service.

• Journal of the Korea Computer Industry Society
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• v.4 no.4
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• pp.547-552
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• 2003

In this thesis, interference phenomena of bluetooth networks requiring Security were minimized; strengthened security of piconet by assigning an identical PIN code to bluetooth devices, which was establishing a specific piconet during authentication stage. To establish a bluetooth piconet system. an unique ID was assigned to each bluetooth device, communication algorithms having different data formats between devices was designed, and an embedded hardware module using ARM processor and uCOS-II RTOS was implemented. About 30% of CPU efficiency in the module was increased by modifying functions including block parameters to work as nonblocking; by the increased efficiency of total piconet, the module could be used as an access point. The module could transmit maximum 10 frames of image and also audio signal by switching the packet effectively according to channel condition. By above-mentioned process, video, audio, and data could be well transmitted by the bluetooth managing program and the possibility of a commercial remote control system using bluetooth technology was suggested.

• Journal of IKEEE
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• v.24 no.4
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• pp.1122-1128
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• 2020

Bandwidth Extension refers to restoring and expanding a narrow band signal(NB) that is damaged or damaged in the encoding and decoding process due to the lack of channel capacity or the characteristics of the codec installed in the mobile communication device. It means converting to a wideband signal(WB). Bandwidth extension research mainly focuses on voice signals and converts high bands into frequency domains, such as SBR (Spectral Band Replication) and IGF (Intelligent Gap Filling), and restores disappeared or damaged high bands based on complex feature extraction processes. In this paper, we propose a model that outputs an bandwidth extended signal based on an autoencoder among deep learning models, using the residual connection of one-dimensional convolutional neural networks (CNN), the bandwidth is extended by inputting a time domain signal of a certain length without complicated pre-processing. In addition, it was confirmed that the damaged high band can be restored even by training on a dataset containing various types of sound sources including music that is not limited to the speech.

• The Journal of the Acoustical Society of Korea
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• v.28 no.7
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• pp.589-598
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• 2009

As mobile devices become multi-functional, and converge into a single platform, there is a strong need for a codec that is able to provide consistent quality for speech and music content MPEG-D USAC standardization activities started at the 82nd MPEG meeting with a CfP and approved WD3 at the 88th MPEG meeting. MPEG-D USAC is converged technology of AMR-WB+ and HE-AAC V2. Specifically, USAC utilizes three core codecs (AAC ACELP and TCX) for low frequency regions, SBR for high frequency regions and the MPEG Surround tool for stereo information. USAC can provide consistent sound quality for both speech and music content and can be applied to various applications such as multi-media download to mobile device Digital radio Mobile TV and audio books.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.358-365
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• 2011

Recently, the LED(Light Emitting Diode) replacing incandescent light bulbs and fluorescent light has great attentions as a most promising candidate for the next generation lighting source due to its environment-friendly characteristics, long life and excellent efficiency. Moreover, since it is a semiconductor device which can convert the electric energy to visible light at a very high speed, it can also used as a communication device. Therefore, the VLC(Visible Light Communication) using the LED can perform the near field communication and lighting function at the same time without additional expenses. However, since the switching device of the conventional LED driver for VLC is operated in the linear region, there exist several drawbacks such as a poor power conversion efficiency and serious heat generation. On the other hand, since the proposed driver is operated in the on/off switching region, it features a higher efficiency and more improved heat generation. To verify the validity of the proposed LED driver, experimental results from a prototype of 20W rated LED driver applied to 3MHz bps broadcasting audio system are given.

• Journal of Internet Computing and Services
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• v.23 no.4
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• pp.1-9
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• 2022

Recently, the functions of smart speakers have diversified, and the penetration rate of smart speakers is increasing. As it becomes more widespread, various techniques have been proposed to cause anomalous behavior against smart speakers. Dolphin Attack, which causes anomalous behavior against the Voice Controllable System (VCS) during various attacks, is a representative method. With this method, a third party controls VCS using ultrasonic band (f>20kHz) without the user's recognition. However, since the method uses the ultrasonic band, it is necessary to install an ultrasonic speaker or an ultrasonic dedicated device which is capable of outputting an ultrasonic signal. In this paper, a smart speaker is controlled by generating an audio signal modulated at a frequency (18 to 20) which is difficult for a person to hear although it is in the human audible frequency band without installing an additional device, that is, an ultrasonic device. As a result with the method proposed in this paper, while humans could not recognize voice commands even in the audible band, it was possible to control the smart speaker with a probability of 82 to 96%.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.5
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• pp.171-180
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• 2023

The three major sleep disorders in Korea are snoring, sleep apnea, and insomnia. Lack of sleep is the root of all diseases. Some of the most serious potential problems associated with sleep deprivation are cardiovascular problems, cognitive impairment, obesity, diabetes, colitis, prostate cancer, etc. To solve these problems, the Korean government provided low-cost national health insurance benefits for polysomnography tests in July 2018. However, insomnia patients still have problems getting treated in terms of time, space, and economic perspectives. Therefore, it would be better for insomnia patients to be allowed to test at home. The measuring device can measure six biosignals (eye movement, tossing and turning, body temperature, oxygen saturation, heart rate, and audio). A gyroscope sensor (MPU9250, InvenSense, USA) was used for eye movement, tossing, and turning. The input range of the sensor was in 258°/sec to 460°/sec, and the data range was in the input range. Body temperature, oxygen saturation range, and heart rate were measured by a sensor (MAX30102, Analog Devices, USA). The body temperature was measured in 30 ℃ to 45 ℃, and the oxygen saturation range was 0% for the unused state and 20 % to 90 % for the used state. The heart rate measurement range was in 40 bpm to 180 bpm. The measurement of audio signal was performed by an audio sensor (AMM2742-T-R, PUIaudio, USA). The was -42 dB ±1 dB frequency range was 20 Hz to 20 kHz. The measured data was successfully received in wireless network conditions. The system configuration was consisted of a PC and a mobile app for bio-signal measurement and data collection. The measured data was collected by mobile phones and desktops. The data collected can be used as preliminary data to determine the stage of sleep and perform the screening function for sleep induction and sleep disturbances. In the future, this convenient sleep measurement device could be beneficial for treating insomnia.

• Science of Emotion and Sensibility
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• v.13 no.4
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• pp.635-646
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• 2010

This article focuses on Funology and a new classified application system based on concept of language and thought which are formed by body experience. It is defined by Funology Body as that. Funology Body is classifying and searching system which are consisted of a body, world (environment), and device tool. The body is sectioned by Brain, Eyes, Ears, Nose, Mouth, Hand, Torso, Feet, and Heart according as parts of the human body. This allows intuiting and experience searching as making classified system connected to the application relationship with concept of an each part of body. The Brain of the body is sub-classified by Book, Account, Business, Memory, Education, Search, and Aphorism to imply the application with thought. The Eyes take Video, Photography, and Broadcast for visibility. The Ears is categorized as Music, Instrument, Audio, and Radio for hearing. The Nose gets Perfume, Smell for olfactory sense. The Mouth is sectioned by Food, SNS, Chatting, Email, and Blog for eating and communication. The Hand sorts into Games, Kits, and Editing to handle, create, and play. The Torso is grouped by Health, Medical, Dance, Sport, Fashion, and Testyuorself related by protecting internal and meaning of the body core. The Feet is classified by Travel, Transportation, Map, and Outdoor for moving and concept of expanding the terrain. The Heart is consisted of Fear, Anger, Joy, Sadness, Acceptance, Disgust, Expectation, and Surprise for a human feeling. Beyond that, the World takes News, Time, Weather, Map, Fortune, and Shop, and Device tool gets Interface, Utilities. The Funology Body has a unique characteristic of giving intuitive and sensuous pleasure and reflection of users' attitude and taste for changing application flexibly.