• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.46 no.10
• /
• pp.40-45
• /
• 2009

In this paper, we introduce a mobile-type tiny sensor device that can classify the activities of daily living based on the state-dependent motion analysis using a 3-axial accelerometer in real-time. The device consists of an accelerometer, GPS module, 32bit micro-controller for sensor data processing and activity classification, and a bluetooth module for wireless data communication. The size of device is 50*47*14(mm) and lasts about 10 hours in operation-mode and 160 hours in stand-by mode. Up to now, the device can recognize three user activities ("Upright", "Running", "Walking") based on the decision tree. This tree is constructed by the pre-learning process to activities of subjects. The accuracy rate of recognizing activities is over 90% for various subjects.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.10
• /
• pp.39-45
• /
• 2011

This paper proposes a low power current-steering 10-bit DAC selecting clock enable signal. The proposed DAC reduces the clock power by cutting the clock signal to the current-source cells in wihich the data will not be changed. The proposed DAC was implemented using a 0.13${\mu}m$ CMOS process with $V_{DD}=1.2V$. Its core area is 0.21$mm^2$. It consumes 4.46mW at 1MHz signal frequency and 200MHz sampling rate. The clock power is reduced to 30.9% and 36.2% of a conventional DAC at 1.25MHz and 10MHz signal frequencies, respectively. The measured SFDRs are 72.8dB and 56.1dB at 1MHz and 50MHz signal frequencies, respectively.

• Journal of Advanced Navigation Technology
• /
• v.16 no.2
• /
• pp.234-239
• /
• 2012

Next generation mobile communication systems have been studied and applied to support various services. In next generation mobile communication systems, the most interested research is the integration of various communication systems and the offer of various services by using high-speed data transmission. The integration of communication systems has been researched by using multi standard modem, while the high-speed data transmission for the offer of various services has been applied by using OFDM. This paper has proposed the method to reduce PAPR by using multi standard modem. with EVM, this paper has also suggested the method to compensate in-band distortion while reducing PAPR. By using the proposed methods, this paper has analyzed and simulated the decrease efficiency of PAPR, the performance of CCDF, and the performance of BER in next generation mobile communication systems. The simulation results improved the performance of next generation mobile communication system can be seen that.

• Korean Journal of Computational Design and Engineering
• /
• v.15 no.5
• /
• pp.383-392
• /
• 2010

The purpose of this study is to develop three Judo-doll systems for enhancement of Judo's performance. Traditional Judo training requires a human training partner. Unfortunately it is not always easy to find one. Multifunctional Judo-doll training system has therefore been developed, and is described here. The system consists of a dummy, a power generating mechanism, and kinematic links. The power-generating mechanism generates forces similar to those of a human, by adjusting deadweights and controlling powderbrake's forces. The powderbrake force is controlled by the microprocessor according to the exercise scenario. The kinetic links, which mimic a human training partner's motions, has been developed based on a $Vicon^{TM}$ system's analysis of the movement of human training partners. This mechanism whose name is "L link-wire" consists of L type links, wire, roller, and dead weight. This mechanism generates the force that leads the link to the neutral position regardless the link is pushed or pulled. The lifting mechanism that lifts the doll when the one-armed shoulder throw skill is applied is also developed. A 32-bit microprocessor controls the whole system; it reads the loadcell data, controls the electromagnetic force, and communicates with a PC via Bluetooth. The training history, including loadcell data, date, and training time, is stored in the PC for analysis. This training system can be used to enhance the Judo performance of any self training player.

• Journal of Navigation and Port Research
• /
• v.34 no.10
• /
• pp.769-774
• /
• 2010

The performance of underwater communication system is influenced on channel characteristic. Delay spread cause by reverberation and multi-path happen the ISI (Inter Symbol Interference) and reduces the communication performance. In this paper, we analyze the performance of acoustic communication experiment in underwater to use the OFDM (Orthogonal Frequency Division Multiplexing) technique for overcome the reverberation and multi-path. As a result, we acquired the BER of modulation techniques. The BER of 2kbps data rate is $1.22{\times}10^{-1}$ and BER of 4 kbps data rate is $2.47{\times}10^{-2}$.

• Progress in Medical Physics
• /
• v.26 no.1
• /
• pp.36-41
• /
• 2015

The Monte Carlo based dose calculation program for stereotactic body radiotherapy was developed in this study. The Geant4 toolkit widely used in the radiotherapy was used for this study. The photon energy spectrum of the medical linac studied in the previous research was applied for the patient dose calculations. The geometry of the radiation fields defined by multi-leaf collimators were taken into account in the PrimaryGeneratorAction class of the Geant4 code. The total of 8 fields were demonstrated in the patient dose calculations, where rotation matrix as a function of gantry angle was used for the determination of the source positions. The DicomHandler class converted the binary file format of the DICOM data containing the matrix number, pixel size, endian type, HU number, bit size, padding value and high bits order to the ASCII file format. The patient phantom was constructed using the converted ASCII file. The EGSnrc code was used to compare the calculation efficiency of the material data.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.7
• /
• pp.1618-1626
• /
• 2013

Virtualization service processes all operation including the data creation, storing, and disposal in a server and transmits processed data as the streaming media form. Therefore, client can use the same environment as the traditional desktop environment without considering the type of device. Virtualization service should consider not only the video quality but also the delay bounds and continuity of video playback for improving the user perceived Quality of Service(QoS) of streaming service. In this paper, we propose a network-adaptive transmission architecture that focuses on guaranteeing QoS requirements for virtualization service. In order to provide those, the proposed architecture have the transmission rate adaptation function based on available bandwidth and the content bit-rate control function based on sender buffer state. Through each function, proposed architecture guarantee the delay bounds and continuity of virtualization contents playback. The simulation results show that proposed network-adaptive transmission architecture provides a improve performance of throughput and transmission delay.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.12 no.4
• /
• pp.309-324
• /
• 1987

In recent years has been an increasing interest with respect to using the discrete cosine transform(DCT) of which performance is found close to that of the Karhumen-Loeve transform, known to be optimal in the area of digital image processing for tha purpose of the image data compression. Among most of reported algorithms aimed at lowering the coputation complexity. Chen's algorithm is is found to be most popular, Recently, Lee proposed a now algorithm of which the computational complexity is lower than that of Chen's. but its performance is significantly degraded by FWL(Finite-Word-Lenght) effects as a result of employinga a fixed-poing arithmetic. In this paper performance evaluation of these two algorithms and error analysis of FWL effect are described. Also a scaling technique which we call Up & Down-scaling is proposed to allevaiate a performance degradation due to fixed-point arithmetic. When the 16x16point 2DCT is applied on image data and a 16-bit fixed-point arithmetic is employed, both the analysis and simulation show that is colse to that of Chen's.

• Korean Institute of Interior Design Journal
• /
• v.19 no.3
• /
• pp.214-223
• /
• 2010

Information & Communication Technology(ICT), called ubiquitous computing, changes our environment in many ways. It also acts on educational environment in concert with new pedagogy. Korean Government gives an efforts to set up the u-School as the educational environment supported by ICT. This study aims to find efficient uses of ICT to cope with the changing education environment and emerging needs of users. The survey research follows the pilot study on the model of future school. The students and teachers in six schools located in Busan answered the questionnaire and 752 individuals were analyzed by the statistical method including frequencies, crosstabs, ANOVA, and factor analysis. The conclusions are as follows: (1) Highly demanded were the u-School facilities to provide pleasant environment as the teachers and students have to spend most of time in classroom, or school premises. In addition, the infrastructures were so desperately required that students are able to control their textbooks and belongings, and efficiently utilize a variety of data. (2) The classroom volume should be planned a bit smaller than the current number of students so that teachers are relieved from the burden of too many student. The needs of students to interact with more students can be bolstered by utilization of ICT. (3) The respondents feel the high needs of computer for student, electronic blackboard, electronic lecture desk, microphone and computer for teacher as the teaching and learning facilities. This showed high needs for teaching and learning facilities enabling the active and individual learning through the use of ICT at education environment. In conclusion, the study proposes the fundamental data to combine u-School elements proper to the current learning and school environment, from the analysis on the use of school facilities, with the subjects, the users of education environment.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.7A
• /
• pp.512-521
• /
• 2012

In this paper, we propose feasible combining rules for a decoding scheme of product codes to apply finite soft decision. Since the decoding scheme of product codes are based on complex tanh calculation with infinite soft decision, it requires high decoding complexity and is hard to practically implement. Thus, simple methods to construct look-up tables for finite soft decision are derived by analyzing the operations of the scheme. Moreover, we focus on using convolutional codes, which is popular for easy application of finite soft decision, as the horizontal codes of product codes so that the proposed decoding scheme can be properly implemented. Numerical results show that the performance of the product codes with convolutional codes using 4-bit soft decision approaches to that of same codes using infinite soft decision.