• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.10
• /
• pp.1087-1094
• /
• 2014

In general, a speaker generates nonlinear distortions owing to a design principle, manufacturing process, and so on, which decreases and changes a sound quality. So, if the speaker is linearized by compensating these nonlinear distortions, the sound quality and satisfaction can be increased. In this paper, a new adaptive controller was proposed to be applied for compensating nonlinear distortions of a speaker. Through computer simulations as well as the analytical analysis, it could be shown that it is possible for both conventional adaptive controller and proposed adaptive controller, to be applied for linearizing the speaker with nonlinear distortions. Also, the simulations results demonstrated that the proposed adaptive controller may have faster convergence speed and better capability of compensating the nonlinear distortion than the conventional adaptive controller with nearly equal computation complexity.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.4
• /
• pp.701-706
• /
• 2017

In this study, existing remote control or the cradle manually drives to recognize the voice of the way and through the app the Cradle to work with a motor. In addition, the temperature and humidity sensor was mounted in the cradle, the temperature and humidity of the cradle can be checked through the LCD. Depending on the sound size of the sound sensor, the resulting value was used to indicate a value of a, b, c, and the sum of the results over 1150, the cradle was recognized as the baby's crying, then, notificate and alarm on app.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.2
• /
• pp.203-208
• /
• 2016

This paper presents a fault detection and data processing algorithm for acoustic sensor systems using the multiple sensor algorithm that has originally developed for the wireless sensor nodes. The multiple sensor algorithm can increase the reliability of the sensor systems by utilizing and comparing the measurements of the multiple sensors. In the acoustic sensor system, the equivalent sound level($L_{eq}$) is used to detect the faulty sensor. The experiment was conducted to demonstrate the feasibility of the multiple acoustic sensor algorithm, and the results show that the algorithm can detect the faulty sensor and validate the data.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.141-146
• /
• 1999

This study aims at establishing an digital signal processing technique to control 3-D sound localization, especially focusing our eyes 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 extented 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 2 m.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.6
• /
• pp.141-146
• /
• 2015

In order to classify and analyze variously compounded sound and voice signal from FPGA microphone, there are numerous systems to detect abnormality signal, however, they have a lot of problems to implement the abnormality signal detection efficiently and effectively. Therefore, we proposed a method that implements classifying the signal effectively and outputting the detection efficiently based on the algorithm applied FIFO structure (First-in First-out) by using microphone sensor which able to input the sound signal, and statistical variance and coefficient of variation (CV). The result showed 96.3% detection when the experiment was performed more than 100 times with the proposed algorithm applied system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.12 no.1
• /
• pp.78-82
• /
• 2019

This paper addressed the spectrum of ultrasonic waves produced by arc and/or coronal discharge inside the switchboard. Portable ultrasound sensors are useful for detecting discharge phenomena, such as coronal means in electrical systems. However, a typical handheld ultrasound detector has a disadvantage of determining the type of problem by listening to the sound characteristics and predicting the results, as a result of the determination of whether a discharge is present. Therefore, a new method of analysis is required to distinguish ultrasonic characteristics. In this paper, we published an ultrasound analysis case study to visualize the sound of ultrasonic waves measured with ultrasonic sensors. From the results of the experiment, it was possible to detect coronal discharge and serial arc discharge without interference by the ultrasonic detection system.

• International Journal of Internet, Broadcasting and Communication
• /
• v.13 no.1
• /
• pp.161-167
• /
• 2021

This paper proposes a new personalized HRTF estimation method which is based on a deep neural network (DNN) model and improved elevation reproduction using a notch filter. In the previous study, a DNN model was proposed that estimates the magnitude of HRTF by using anthropometric measurements [1]. However, since this method uses zero-phase without estimating the phase, it causes the internalization (i.e., the inside-the-head localization) of sound when listening the spatial sound. We devise a method to estimate both the magnitude and phase of HRTF based on the DNN model. Personalized HRIR was estimated using the anthropometric measurements including detailed data of the head, torso, shoulders and ears as inputs for the DNN model. After that, the estimated HRIR was filtered with an appropriate notch filter to improve elevation reproduction. In order to evaluate the performance, both of the objective and subjective evaluations are conducted. For the objective evaluation, the root mean square error (RMSE) and the log spectral distance (LSD) between the reference HRTF and the estimated HRTF are measured. For subjective evaluation, the MUSHRA test and preference test are conducted. As a result, the proposed method can make listeners experience more immersive audio than the previous methods.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.4
• /
• pp.103-109
• /
• 2022

This significance of the infant care system has emerged due to sudden infant death during sleeping. This paper presented a design and implementation of a prototype model, which is a infant care device controlled by a smartphone using Bluetooth technology. Prototype Device Model consists of MCU(microcontroller unit), Accelerometer Sensor, Temperature Measuring Sensor, Sound Measuring Sensor, Bluetooth Module, and Camera Module. The proposed application transfers the information to the parent's smartphone and computers, such as infant's falling, crying, and fever detection. A test verified the availability of a prototype infant care system model using Bluetooth Low Energy with operating the low power driving.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.3
• /
• pp.111-116
• /
• 2022

In the paper, A prototype Fetal Heart Monitor, mini - size, was designed and produced for pre-mothers to measure the rate and rhythm of their features's heart at home.Pre-mothers could listen fetal heart rhythm through an inner bluetooth speaker ant the monitor. LED colors show the frequency of fetal heart rate variability on the monitor. All measured health information, by ultrasonic resonator and bluetooth speaker, is linked to a mother's smart phone. A test verified this simple measuring device helps users discover the symptoms of fetal health. Patients using at home devices usefully prevent sudden cardiac death and myocardial infraction by discovering symptoms.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.4
• /
• pp.403-410
• /
• 2016

Materials made of metals have their own manifest resonant frequencies. Using this property, the quality test of products from the factory can be performed. An impact is applied to the product and the frequencies of the sound and/or vibration are measured using high-end equipments. They use a general purpose computer or a DSP(: Digital Signal Processor)-based stand-alone system which is usually too large in-size to carry and expensive to build. In this paper, we introduce a system that is developed based on a MSP430 MCU(:Micro-Controller Unit) from TI(: Texas Instruments). The ultra-low power MSP430 MCUs make it possible to make a frequency analyzer in a very small size without the need of using a large-size battery. The proposed system can be used in situations where the frequency analyzer should be carried easily with an investigator and should be built at low cost sacrificing some accuracy. We implemented the system using a launchpad supplied by TI and could confirm that the proposed system could identify with a high-accuracy the frequencies of various artificial and natural sounds.