• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.40-45
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• 2007

In this paper, aim to suggest the medical information wireless transmission system to provide the mobility of medical service by means of wireless area network which makes it possible, home or at a long range, to check and oversee the state of patients, and to can out a simulation. The proposed method converts medical information to digital data in an emergency and sends them to mobile terminals such as PDAs to make possible swift first aid. The simulation took advantage of the OFDM transmission method based on IEEE 802.1la in order to send reliable medical information in mobile wireless channel environment, and analyzed the system performance by applying convolution encoding to transmit reliable information in AWGN and 3-ray mobile multipath fading channel environment.

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.291-303
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• 2019

In the paper the analysis of natural vibrations of the transmission line with use of spectral elements and the laboratory experiments is performed. The purpose of the investigation is to analyze the natural vibrations of the transmission line and compare with the results obtained in the numerical simulations. Particular attention is paid to the hysteretic and aerodynamic damping analysis. Sensitivity of the wave number is performed for changing of the tension force, as well as for the different damping parameters. The numerical model is made using the Spectral Element Method. In the spectral model, for various parameters of stiffness, damping and tension force, the system response is checked and compared with the results of the accelerations obtained in the measurements. A frequency response functions (FRF) are calculated. The credibility of the model is assessed through a validation process carried out by comparing graphical plots of FRF and time history analysis and numerical values expressing differences in acceleration amplitude (MSG), phase angle differences (PSG) and differences in acceleration and phase angle total (CSG) values. The next aspect constituting the purpose of this paper is to present the wide possibilities of modelling and simulation of slender conductors using the Spectral Element Method. The obtained results show good accuracy in the range of both experimental measurements as well as simulation analysis. The paper emphasizes the ease with which the sensitivity of the conductor and its response to changes in density of spectral mesh division, tensile strength or material damping can be studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.175-176
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• 2014

• Progress in Medical Physics
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• v.19 no.1
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• pp.42-48
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• 2008

Bio-implantable devices such as heart pacers, gastric pacers and drug-delivery systems require power for carrying out their intended functions. These devices are usually powered through a battery implanted with the system or are wired to an external power source. This paper describes an inductive power transmission link, which was developed for an implantable stimulator for direct stimulation of denervated muscles. The carrier frequency is around 1MHz, the transmitter coil has a diameter of 46mm, and the implant coil is 46mm. Data transmission to the implant with amplitude shift keying (ASK) and back to the transmitter with passive telemetry can be added without major design changes. We chose the range of coil spacing (2 to 30mm) to care for lateral misalignment, as it occurs in practical use. If the transmitter coil has a well defined and reliable position in respect to the implant, a smaller working range might be sufficient. Under these conditions the link can be operated in fixed frequency mode, and reaches even higher efficiencies of up to 37%. The link transmits a current of 50 mA over a distance range of 2-15 mm with an efficiency of more than 20% in tracking frequency. The efficiency of the link was optimized with different approaches. A class E transmitter was used to minimize losses of the power stage. The geometry and material of the transmitter coil was optimized for maximum coupling. Phase lock techniques were used to achieve frequency tracking, keeping the transmitter optimally tuned at different coupling conditions caused by coil distance variations.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.146-150
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• 2001

Microwave model and high-frequency measurement of the ACF flip-chip interconnection was investigated using a microwave network analysis. S-parameters of on-chip and substrate were separately measured in the frequency range of 200 MHz to 20 GHz using a microwave network analyzer HP8510 and cascade probe. And the cascade transmission matrix conversion was performed. The same measurements and conversion techniques were conducted on the assembled test chip and substrate at the same frequency range. Then impedance values in ACF flip-chip interconnection were extracted from cascade transmission matrix. ACF flip chip interconnection has only below 0.1nH, and very stable up to 13 GHz. Over the 13 GHz, there was significant loss because of epoxy capacitance of ACF. However, the addition of SiO$_2$filler to the ACF lowered the dielectric constant of the ACF materials resulting in an increase of resonance frequency up to 15 GHz. High frequency behavior of metal Au stud bumps was investigated. The resonance frequency of the metal stud bump interconnects is higher than that of ACF flip-chip interconnects and is not observed at the microwave frequency band. The extracted model parameters of adhesive flip chip interconnects were analyzed with the considerations of the characteristics of material and the design guideline of ACA flip chip for high frequency applications was provided.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3512-3528
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• 2016

A network with high mobility nodes or vehicles is vehicular ad hoc Network (VANET). For improvement in communication efficiency of VANET, many techniques have been proposed; one of these techniques is vehicular node clustering. Cluster nodes (CNs) and Cluster Heads (CHs) are elected or selected in the process of clustering. The longer the lifetime of clusters and the lesser the number of CHs attributes to efficient networking in VANETs. In this paper, a novel Clustering algorithm is proposed based on Ant Colony Optimization (ACO) for VANET named ACONET. This algorithm forms optimized clusters to offer robust communication for VANETs. For optimized clustering, parameters of transmission range, direction, speed of the nodes and load balance factor (LBF) are considered. The ACONET is compared empirically with state of the art methods, including Multi-Objective Particle Swarm Optimization (MOPSO) and Comprehensive Learning Particle Swarm Optimization (CLPSO) based clustering techniques. An extensive set of experiments is performed by varying the grid size of the network, the transmission range of nodes, and total number of nodes in network to evaluate the effectiveness of the algorithms in comparison. The results indicate that the ACONET has significantly outperformed the competitors.

• Journal of Sensor Science and Technology
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• v.25 no.4
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• pp.280-284
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• 2016

For an arc-flash protection system, the selection of arc-flash sensor in implementation is largely dependent on the coverage area and the spatial resolution. Typically, a point sensor is used to accurately measure an arc event within a very narrow region; whereas, a loop or a line sensor can cover several electrical compartment at the same time, but with a poor resolution. In this work, a novel scheme for an arc-flash sensor was developed by making use of the transmission loss of plastic optical fibers (POFs) to cover a broad range with a high spatial resolution. By relating the amplitude ratio of the arc-signals at the ends of the POF with the arc-location, arc events could be located with a resolution of ~5 cm within a spatial range of 10 m, which has not been reported yet.

• International Journal of Automotive Technology
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• v.6 no.4
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• pp.383-390
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• 2005

This study proposes an innovative design guideline to assist the evaluation and improvement of the dynamic comfort of vehicle seating. The existing evaluation method for the comfort of vehicle seating was investigated to broach problems in evaluation. It was found that the currently existing evaluation method employs the resonance frequency of the vibration system composed of the seat and the human body and the maximum vibration transmissibility. This study proposes a design guideline aimed at the enhancement of vibration transmission characteristics above the resonance range, particularly within the range of 10-18 Hz. In order to meet this guideline, a seat was constructed out of foam having a low damping coefficient. It was then installed in a vehicle for a driving test. The driving test confirmed the improvement of the dynamic comfort of the seat. The result of evaluation of the improved seat using the SEAT index, an industry standard widely used to evaluate the dynamic comfort of a seat considering the perceptivity characteristics of the human body, showed that the perceptive vibration transmission had reduced by more than $11\%$. The effect of the modification of seat foam was also verified through a subjective assessment of dynamic comfort of the seats.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.3123-3123
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• 2001

Near infrared (NIR) spectroscopy has become a widely used method in food and beverage analysis because of its speed, accuracy and the simplicity of sample preparation. One of the basic requirements of NIR instruments is a wide dynamic range if weak, or small, absorption changes or concentrations are to be measured. Thus the instrument must be sufficiently luminous, and efficient, to enable measurements to be made in a reasonably short time, as for some applications (e.g. sorting) short response times are essential. Diode lasers function the same way as lasers but linewidths are not as narrow as typical lasers. In this work an array of seven laser diodes (in the range of 750-1100 nm) with energy outputs of around hundred milliwatts each were combined with a fast diode array spectrometer (400-1100 nm, 1024 pixels, integration time from 3 ms) as detector. Measurements in transmission mode were performed in solutions of sugars in aqueous solutions and in deuteriumoxide. The feasibility of non-destructive measurements in transmission mode was investigated for different fruits and vegetables.

• Journal of Korea Multimedia Society
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• v.7 no.9
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• pp.1246-1254
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• 2004

This paper presents a image coding method that is well adaptive to close-range video transmission because of its low titrate and simple coding procedure. At first, it reduces temporal redundancies by performing image DPCM between previous frame and current frame, and makes wavelet transformed image of this difference image. Then, the coefficients are quantized selectively by using the coefficient values of base level and mid-frequency level because inter-level redundancies are widely exists in multi-resolution images. Finally quantized coefficients are made iron the function that implies the target bitrate, the average coefficient energy, and the value of the level. The proposed method shows the effective Performance in the experiments using the continuous motion images and transition images.