• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.855-860
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• 2014

Background: The purpose of this study was to assess the relationship between different sonographic features of papillary thyroid carcinoma (PTC) on high-frequency ultrasound and cervical lymph node metastasis (CLNM). Materials and Methods: We enrolled 548 patients who underwent initial surgery for PTC between May 2011 and December 2012 in our hospital at diagnosis. The sonographic features of 513 PTC nodules in 513 eligible patients, who had single PTC nodules in their thyroid glands, were retrospectively investigated. All patients with a suspect malignant nodule (d<0.5cm) among multiple nodules were initially diagnosed by fine-needle aspiration biopsy (FNAB) to ascertain if the suspect nodule was PTC. The final diagnosis of all the thyroid nodules and existence of CLNM were based on postoperative pathology. Patients were divided into two groups: a positive group with CLNM (224 nodules) and a negative group without CLNM (289 nodules). The following factors were investigated: gender, age, echogenicity, echotexture, size, shape, location, margin, contour, calcification morphology, distance between the nodule and pre- or post-border of the thyroid capsule, vascularity and the differences between the two groups. Results: Correlation analysis showed that shorter distances between the nodule and pre- or postborder of thyroid capsule resulted in greater risk of CLNM (Spearman correlation coefficient=-0.22, p<0.0001). The significant factors in multivariate analysis were age<45yrs, larger size (d>1cm), "wider than tall" shape, extrathyroid extension and mixed flow (internal and peripheral) (p<0.05, OR=0.406, 2.093, 0.461, 1.610, 1.322). Conclusions: Significant sonographic features of PTC nodules in preoperative high-frequency ultrasound are crucial for predicting CLNM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.583-591
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• 2008

OFDM (orthogonal frequency division multiplexing) has serious problem of high PAPR (peak-to-average power ratio). Recently, CI/OFDM (carrier interferometry OFDM) system has been proposed for the low PAPR. However, CI/OFDM system shows another problem of ICI because of phase offset mismatch due to the phase noise. In this paper, to simultaneously reduce the PAPR and ICI effects, we propose an A-CI/OFDM (advanced-CT/OFDM). This method improves the BER performance by use of the margin of phase offset at CI codes. Propose system to reduce the effect the phase noise, even though it shows a little bit higher PAPR than conventional CI/OFDM, so we apply the PTS among the PAPR reduction techniques to proposed system to mitigate this problem. Therefore, it improves the total BER performance because the proposed method can decrease the effect of phase noise and get the gain in PAPR reduction performance. From the simulation results, we can show the performance comparison between the conventional OFDM, CI/OFDM and A-CI/OFDM.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.59-67
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• 1993

The variations of the natural frequencies and the peak response acceleration at the top of prestressed concrete reactor building due to random variability and/or model uncertainty of structural parameters are studied. The results may be used as essential input parameters in seismic probabilistic risk assessment or seismic margin assessment of the reactor building. The sensitivity test of each structural parameter is first performed to determine the most influential parameter upon the natural frequency of structure model. Then Monte Carlo simulation technique is applied to evaluate the effect of parameter variation on the natural frequencies and the peak response acceleration. The acceleration time history is obtained by direct integration scheme. As the study results, it is found that the fundamental natural frequency and the peak response acceleration at the top of the building are most strongly affected by Young's modulus among the structural parameters, in which the value of mean plus one standard deviation obtained by probabilistic approach deviates up to about (+)12% from the result of deterministic method. Considering the uncertainty of flexural rigidity, the structural responses vary in range of (-)4%~(+)14%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.45-53
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• 2002

This paper presents an algorithm for the appropriate parameter selection of a power system stabilizer and power converters in two-area power systems with a series HVDC links. The method for PSS is one of the classical techniques by allocating properly poly-zero positions to fit as closely as desired the ideal phase lead and by changing the gain to produce a necessary damping torque. Proper parameter of power converters are obtained in order to have sufficient speed and stability margin to cope with changing reference values and disturbances based on the Root-locus technique. The small signal and transient stability studies using the PSS and power converters parameters obtained from these methods show that a natural oscillation frequency of the study case system is adequately damped. The simulation used in the paper was performed by the Power System Toolbox software program based on MATLAB.

• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.105-112
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• 2002

In this paper, a servo filter design for the gimbal engine actuator system of KSR-III(Korea Sounding Rocket-III) is considered. A reasonable filter structure is determined based on the actuator analytic models. The servo filter consists of a 2-nd order lowpass filter and a 1-st order compensator. The lowpass filter is required to protect the actuator from high frequency vibration, and the compensator to enhance the resulting stability. A Butterworth type servo filter is considered as the simplest one. The final servo filter type is determined by evaluating simultaneously both high frequency gain reduction performance and the corresponding KSR-III stability margin. Consequently it is revealed that a notch type servo filter located on the error between command signal and feedback signal in the control loop is very effective. Later, based on the proposed servo filter type, an onboard servo filter hardware of KSR-III will be designed and tested.

• Journal of Multimedia Information System
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• v.9 no.2
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• pp.145-154
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• 2022

The authors are making a prototype flexible board of a radio-frequency transmitter for measuring an electromyogram (EMG) of a flying moth and plan to apply for an experimental station license from the Ministry of Internal Affairs and Communications of Japan in the summer of 2022. The goal is to create a continuous low-dose exposure standard that incorporates scientific and physiological functional assessments to replace the current standard based on lethal dose 50. This paper describes the technical evaluation of the hardware. The signal of a bipolar EMG electrode is amplified by an operational amplifier. This potential is added to a voltage-controlled crystal oscillator (27 MHz, bandwidth: 4 kHz), frequency-converted, and transmitted from an antenna about 10 cm long (diameter: 0.03 mm). The power source is a 1.55-V wristwatch battery that has a total weight of about 0.3 g (one dry battery and analog circuit) and an expected operating time of 20 minutes. The output power is -7 dBm and the effective isotropic radiated power is -40 dBm. The signal is received by a dual-whip antenna (2.15 dBi) at a distance of about 100 m from the moth. The link margin of the communication circuit is above 30 dB within 100 m. The concepts of this hardware and the measurement data are presented in this paper. This will be the first biological data transmission from a moth with an official license. In future, this telemetry system will improve the detection of physiological abnormalities of moths.

• Journal of Astronomy and Space Sciences
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• v.37 no.2
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• pp.117-129
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• 2020

In a Satellite communication system, a link budget analysis is the detailed investigation of signal gains and losses moving through a channel from a sender to receiver. It inspects the fading of passed on data signal waves due to the process of spreading or propagation, including transmitter and receiver antenna gains, feeder cables, and related losses. The extent of the proposed tool is to make an effective, efficient, and user-friendly approach to calculate link budget analysis. It is also related to the satellite communication correlation framework by building up a graphical interface link analysis tool utilizing STK^® software with the interface of C# programming. It provides better kinds of graphical display techniques, exporting and importing data files, printing link information, access data, azimuth-elevation-range (AER), and simulation is also possible at once. The components of the link budget analysis tool include transmitter gain, effective isotropic radiated power (EIRP), free space loss, propagation loss, frequency Doppler shift, flux density, link margin, elevation plot, etc. This tool can be useful for amateur users (e.g., CubeSat developers in the universities) or nanosat developers who may not know about the RF communication system of the satellite and the orbital mechanics (e.g., orbit propagators) principle used in the satellite link analysis.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.711-714
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• 2005

We propose floating point arithmetic units for geometry operation of mobile 3D graphic processor. The proposed arithmetic units conform to the single precision format of IEEE standard 754-1985 that is a standard of floating point arithmetic. The rounding algorithm applies the nearest toward zero form. The proposed adder/subtraction unit and multiplier have one clock cycle latency, and the inversion unit has three clock cycle latency. We estimate the required numbers of arithmetic operation for Viewing transformation. The first stage of geometry operation is composed with translation, rotation and scaling operation. The translation operation requires three addition and the rotation operation needs three addition and six multiplication. The scaling operation requires three multiplication. The viewing transformation is performed in 15 clock cycles. If the adder and the multiplier have their own in/out ports, the viewing transformation can be done in 9 clock cycles. The error margin of proposed arithmetic units is smaller than $10^{-5}$ that is the request in the OpenGL standard. The proposed arithmetic units carry out operations in 100MHz clock frequency.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.3
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• pp.9-14
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• 2012

Robust power delivery and distribution are considered one of the major challenges in electronic devices today. As a technology develops (i.e. frequency and complexity, increase and size decreases), both power density and power supply noise increase, and voltage supply margin decreases. In addition, thermal problem is induced due to high power and poor power distribution. Until now most of studies to improve power delivery and distribution have been focused on device circuit or system architecture designs. Interconnect process technologies to resolve power delivery issues have not greatly been explored so far, but recently it becomes of great interest as power increases and voltage specification decreases in a smaller chip size.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.774-778
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• 2010

In this paper, the preliminary EMC analysis process between the Communication, Ocean and Meteorological Satellite (COMS) and the Geostationary Earth Orbit (GEO) launch vehicles in the frequency range is described. The considered launch vehicles are Arian Ⅴ, Sea Launch, Land Launch, Atlas III&Ⅴ, Delta IV, Proton M/breeze M, Soyuz, H II-Aa. The launch vehicle Radiated Susceptibility (RS) specifications have been compared to COMS satellite Radiated Emission (RE) limits. The COMS Radiated Emission (RE) level is determined by calculating the radiated field equal to the quadratic sum of radiated emissions of each equipment switched "ON" during launch. As a result, The RS requirements of Arian V, Atlas III&V and Delta IV lauchers are compliant with COMS RE limits. The negative margins appear between the others launch vehicle RS (Sea Launch, Land Launch, Proton M/Breeze M, Soyuz and H II-A) and COMS RE. Then, if the launchers that have negative margin were chosen by the customer, The EMC tests should be performed at satellite level in order to demonstrate the compatibility with respect to launch vehicles requirements.