• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.353-357
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• 2006

One-sided and two-sided ATF for GNSS receiver are deigned, implemented and evaluated in this paper. The difference f filter characteristics such as the location of zeros and the frequency response is reviewed and examined with experiments. NLMS adaptation algorithm is adopted for updating the weighting coefficients of the 12-tap FIR filter. he performance of ATF is evaluated using real signals consisting of the signals from GPS simulator and the signal generator. The output of ATF is fed into the SDR to evaluate SNR and the position accuracy. The complexity of implementation is also compared and the effects of the time delay and the phase delay are examined. The experimental results show that one-sided and two-sided ATF give similar performance against single tone CWI.

• Journal of Computing Science and Engineering
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• v.1 no.2
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• pp.211-232
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• 2007

In this paper we investigate some issues and solutions related to the design of a Data Warehouse (DW), storing several aggregate measures about trajectories of moving objects. First we discuss the loading phase of our DW which has to deal with overwhelming streams of trajectory observations, possibly produced at different rates, and arriving in an unpredictable and unbounded way. Then, we focus on the measure presence, the most complex measure stored in our DW. Such a measure returns the number of distinct trajectories that lie in a spatial region during a given temporal interval. We devise a novel way to compute an approximate, but very accurate, presence aggregate function, which algebraically combines a bounded amount of measures stored in the base cells of the data cube. We conducted many experiments to show the effectiveness of our method to compute such an aggregate function. In addition, the feasibility of our innovative trajectory DW was validated with an implementation based on Oracle. We investigated the most challenging issues in realizing our trajectory DW using standard DW technologies: namely, the preprocessing and loading phase, and the aggregation functions to support OLAP operations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1005-1015
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• 1999

This paper is concerned with an improvement on IFFT (inverse fast Fourier transform) and FFT based baseband digital implementation algorithm for BPSK (binary phase shift keying)-modulated MC-CDMA (multicarrier-code division multiple access) systems, that is functionally equivalent to the conventional implementation algorithm, while reducing computational complexity and bandwidth requirement. We also derive an equalizer structure for the proposed implementation algorithm. The proposed algorithm is based on a variant of FFT algorithm that utilizes a N/2-point FFT/IFFT for simultaneous transformation and reconstruction of two N/2-point real signals. The computer simulations under additive white Gaussian noise channels and frequency selective fading channels using equal gain combiner and maximal ratio combiner diversities, demonstrate the performance of the proposed algorithm.

• Journal of the Korea Safety Management & Science
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• v.12 no.2
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• pp.147-152
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• 2010

Project implementation plan is a blueprint that confirms project performance activities and specifies required man-hour, period and resource imput ratio. Various figures, the results of implementation plan, are predicted through estimation, and because of superiority of objectivity and repeatability, numerical formula-based estimation model is often used overseas. COCOMO model is the representative estimation model whose theories and formulas are publicized and it predicts the total man-hour required for software system development. This model is publicized in "Software Engineering Economics" written by Professor Barry Boehm of the U.S., and is the most widely applied numerical formula-based estimation model. This study is conducted to provide a series of methods that are optimal for KTDS environment by choosing COCOMO II model among various types of COCOMO models. In establishing implementation plan, COCOMO II model alone is not sufficient, it is necessary to link with and apply standard WBS system and standard man-hour. In establishing specific implementation plan, phased standard WBS system in order of the first phase of all the activities implemented in the project, Activity, Task, and Role, and the man-hour put into this should be distributed according to standard ratio from COCOMO II model's total man-hour. This study provides explainations by establishing standard WBS system and linking with COCOMO II model.

• Journal of Korea Multimedia Society
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• v.10 no.11
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• pp.1483-1495
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• 2007

Thanks to IEEE 802.11 technique, accessing Internet through a wireless LAN(Local Area Network) is possible in the most of the places including university campuses, shopping malls, offices, hospitals, stations, and so on. Most of the APs(access points) for wireless LAN are supporting 2.4 GHz band 802.11b and 802.11g protocols. This paper is introducing a C# library function which can be used to read RSSIs(Received Signal Strength Indicator) from APs. An LBS(Location Based Service) estimates the current location of the user and provides useful user's location-based services such as navigation, points of interest, and so on. Therefore, indoor, LBS is very desirable. However, an indoor LBS cannot be realized unless indoor position ing is possible. For indoor positioning, techniques of using infrared, ultrasound, signal strength of UDP packet have been proposed. One of the disadvantages of these techniques is that they require special equipments dedicated for positioning. On the other hand, wireless LAN-based indoor positioning does not require any special equipments and more economical. A wireless LAN-based positioning cannot be realized without reading RSSIs from APs. Therefore, our C# library function will be widely used in the field of indoor positioning. In addition to providing a C# library function of reading RSSI, this paper introduces implementation of indoor positioning modules making use of the library function. The methods used in the implementation are K-NN(K Nearest Neighbors), Bayesian and trilateration. K-NN and Bayesian are kind of fingerprinting method. A fingerprint method consists of off-line phase and realtime phase. The process time of realtime phase must be fast. This paper proposes a decision tree method in order to improve the process time of realtime phase. Experimental results of comparing performances of these methods are also discussed.

• Women's Health Nursing
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• v.16 no.1
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• pp.10-19
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• 2010

Purpose: The purpose of this study was to investigate the relationship among family support, stress and quality of life according to the phases of illness in breast cancer patients. Methods: A descriptive correlational study was employed with 121 breast cancer patients. The data was collected by using self reported questionnaire. Self reported data was collected by using the Family support scale, Perceived Stress Scale (PSS), and EORTC QLQ-BR23. Phases of illness consisted 1st phase, 2nd phase, 3rd phase. Results: The score of family supporting, stress and quality of life showed a statically differences according to the phase of illness. Family supporting and stress had negative relation in the first, second and third phase. Family supporting and quality of life in function area had positive relation in the first, second phase. There was no relation between family supporting and quality of life in symptom area. Stress, quality of life in symptom area and quality of life in function area had correlation in the first, third phase. Conclusion: This study suggest that the new nursing implementation should be considered according to the phase of illness in order to improve the family supporting and quality of life and reduce the stress in breast cancer patients through this study results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1663-1668
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• 2017

A BLDC motor with higher number of phases has several advantages, compared to the conventional three-phase BLDC motors. It can reduce the commutation torque ripple and the iron loss without increasing the voltage per phase and increase the reliability and power density. Higher number of phases increase the torque-per-ampere ratio for the same machine volume and output power by widening the electrical conduction period. In this paper, the proposed seven-phase BLDC motor drive system is made into several functional modular blocks, so that it can be easily extended to other ac motor applications: back-EMF block, hysteresis current control block, pwm inverter block, phase current block, and speed/torque control block. Also in a system of BLDC motor drive, the PI controller has been widely used in the speed controller because of the simple implementation. To obtain a good speed response in a general drive system using the PI controller, the high bandwidth of a controller is established. therefore, in this paper, a Fuzzy controller is applied to the 7-phase BLDC motor drive system in order to improve the speed control performance. The Fuzzy controller is compared with a conventional PI controller through the experiment with respect to speed dynamic responses. These experimental results show that the Fuzzy controller of the 7-phase BLDC motor drive system is superior over the conventional PI controller. The algorithm using the Fuzzy controller can improve a comfortable ride in the field of high performance 7-phase BLDC motor drive applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.15-23
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• 2007

A simple six-port direct conversion QPSK receiver which is made up of a six-port phase correlator, a signal power detector, and I/Q channel signal de-modulator is designed and implemented in this paper. The output phase signals of six-port phase correlator are also analysed. On the basis of $90^{\circ}C$ phase relation among the six-port phase correlator output signals, the QPSK de-modulation circuit is designed by a simple circuit. The six-port phase correlator is made up of $90^{\circ}$ hybrid branch line and power detector. The six-port phase correlator, which is designed in frequency range of 11.7 to 12.0 GHz, gets the phase error characteristics less than $5^{\circ}$. By considering matching network and amplitude balance in the designed fiequency range, the designed six-port direct conversion QPSK receiver demodulates the I and Q signals with performance less than $5^{\circ}$ phase error.

• Journal of Power Electronics
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• v.14 no.1
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• pp.61-73
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• 2014

Multiphase machines are characterized by high power density, enhanced fault-tolerant capacity, and low torque pulsation. For a voltage source inverter supplied multiphase machine, the probability of load imbalances becomes greater and unwanted low-order stator voltage harmonics occur. This paper deals with the PWM control of multiphase inverters under unbalanced load conditions and it proposes a novel near-five-vector SVPWM algorithm based on the five-phase six-leg inverter. The proposed algorithm can output symmetrical phase voltages under unbalanced load conditions, which is not possible for the conventional SVPWM algorithms based on the five-phase five-leg inverters. The cause of extra harmonics in the phase voltages is analyzed, and an xy coordinate system orthogonal to the ${\alpha}{\beta}z$ coordinate system is introduced to eliminate low-order harmonics in the output phase voltages. Moreover, the digital implementation of the near-five-vector SVPWM algorithm is discussed, and the optimal approach with reduced complexity and low execution time is elaborated. A comparison of the proposed algorithm and other existing PWM algorithms is provided, and the pros and cons of the proposed algorithm are concluded. Simulation and experimental results are also given. It is shown that the proposed algorithm works well under unbalanced load conditions. However, its maximum modulation index is reduced by 5.15% in the linear modulation region, and its algorithm complexity and memory requirement increase. The basic principle in this paper can be easily extended to other inverters with different phase numbers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.7
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• pp.540-549
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• 2017

A phase frequency detector(PFD) composed of logic circuits is widely used in a phase locked loop(PLL) due to the easy implementation for integrated circuits. A frequency locked loop(FLL) removes the reference oscillator in the PLL, and the resonator serves as a reference oscillator. A frequency detector(FD) is indispensable for the FLL configuration, and a FD, which is usually composed of a mixer is used to build an FLL. In this paper, instead of FD using mixer, a FD is constructed by using 1.175 GHz resonator composed of microstrip and PFD taking the versatility of PFD into consideration. Using the designed FD, FLL oscillating at a frequency of 1.175 GHz is composed. As a result of comparison with the FLL composed of FD using mixer, it was confirmed that the proposed FLL has better phase noise performance than FLL using mixer FD with FLL bandwidth.