• Journal of the Korea Society of Computer and Information
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• v.5 no.4
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• pp.62-68
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• 2000

It was designed a high-speed analog input card that is a important device of ultrasonic testing flaw detector in the middle of non-destructive testing in this Paper. The A/D Board is inquired high-speed sampling rate and fast data acquisition system. This pater shows a design that has a function of Peak- Detection for ultrasonic testing by ISA Bus type and a 50MHz of A/D converter in order to do sampling more than quadruple frequency of transducer frequency.

• Advances in nano research
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• v.10 no.3
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• pp.253-261
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• 2021

Polydimethylsiloxane (PDMS) is one of the most widely adopted silicon-based organic polymeric elastomers. Elastomeric nanostructures are normally required to accomplish an explicit mechanical role and correspondingly their mechanical properties are crucial to affect device and material performance. Despite its wide application, the mechanical properties of PDMS are yet fully understood. In particular, the time dependent mechanical response of PDMS has not been fully elucidated. Here, utilizing state-of-the-art PeakForce Quantitative Nanomechanical Mapping (PFQNM) together with Force Volume (FV) and Fast Force Volume (FFV), the elastic moduli of PDMS samples were assessed in a time-dependent fashion. Specifically, the acquisition frequency was discretely changed four orders of magnitude from 0.1 Hz up to 2 kHz. Careful calibrations were done. Force data were fitted with a linearized DMT contact mechanics model considering surface adhesion force. Increased Young's modulus was discovered with increasing acquisition frequency. It was measured 878 ± 274 kPa at 0.1 Hz and increased to 4586 ± 758 kPa at 2 kHz. The robust local probing of mechanical measurement as well as unprecedented high-resolution topography imaging open new avenues for quantitative nanomechanical mapping of soft polymers, and can be extended to soft biological systems.

• Journal of the Korean Society of Safety
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• v.31 no.3
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• pp.47-52
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• 2016

This paper describes the design and fabrication of high frequency ground impedance measuring system for assessment of grounding system for Lightning protection. The ground impedance measuring system has been designed and fabricated which makes it possible to assess the ground impedance by frequency ranges from 100 Hz to 1 MHz. The effective grounding systems having a very low impedance to electromagnetic disturbance such as lightning surges and noises in microelectronics and high-technology branches are strongly required. In order to analyze the dynamic characteristic of grounding system impedances in lightning and surge protection grounding systems, it is highly desirable to assess the ground impedances as a measure of performance of grounding system in which lightning and switching surge currents with fast rise time and high frequency flow. The measuring system is based on the variable frequency power supply and consists of signal circuit part, main control part, data acquisition and processing unit, and voltage and current probe system. The ground impedance measuring system can be used to assess grounding system during occurrence of lightning.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.729-732
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• 2005

This paper describes a time-spatial domain model for simulating raw data acquisition of space-borne SAR system. The position, velocity and attitude information of the platform at a certain time instance is used for deriving sensor-target model. Ground target is modelled by a set of point scatters with reflectivity and two-dimensional ground coordinates. The signal received by SAR is calculated for each slow and fast time instance by integrating the reflectivity and phase values from all target point scatters. Different from frequency domain simulation algorithms, the proposed time domain algorithm can provide fully physical modelling of SAR raw data simulation without any assumptions or approximations.

• Proceedings of the KSRS Conference
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• v.2
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• pp.800-803
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• 2006

The Space-borne electro-optical camera system, like KOMPSAT has panchromatic redundant image channel as well as primary channel in order to increase reliability of satellite system. In most case redundant channel never been used during the whole mission period. Staggered array configuration using redundant image channel and new operation mode proposed which operates primary and redundant channel simultaneously. Without new hardware design, fast electronics and system complexity, we can get 1.414 times more fine GSD image of original system and aliasing effect which corrupt high frequency information of image can be minimized. To get the more efficiency from staggered array configuration, we introduce masked pixel CCD.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1879-1881
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• 1996

This paper describes the fine structure of electric field waveforms produced by lightning return strokes. The electric field measuring system consists of hemisphere antenna 30 cm in diameter, integrator and data acquisition device. Its frequency bandwidth is from 200 Hz to 1.56 MHz, and the sensitivity is 0.96 mV/V/m. Electric field signals are digitized every 200 ns with the resolution of 12-bit and the length of 5 kilowords, and those are registered by a personal computer. Also data are analyzed by means of the fast Fourier transform (FFT) method.

• Journal of the Korea Society of Computer and Information
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• v.5 no.2
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• pp.121-129
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• 2000

The fuzzy-based SAM algorithm is proposed in this thesis to reduce the idle time. to recover call truncation fast when it is handed off and to last frequency acquisition in the mobile communications. It has additive and adaptive elements. Its weight values are generated not by feedback but by input conversion values. The initial expectation value is defined and forwardㆍbackward searching is executed 4o produce the expectation value of one chip. The fuzzy-based SAM algorithm is applied to the demodulator in CDMA system, and the synchronization time is measured. Synchronization time of PN code is 1.678$\mu\textrm{s}$ by SAM algorithm. It is 993 times faster than time of the conventional systems, 1.667$\mu\textrm{s}$.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2135-2137
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• 2005

This paper describes the features of electric and magnetic fields produced by lightning discharges. The measuring system consists of fast electric field sensor, crossed-loop magnetic field sensors, signal processing circuit, A/D converter and data acquisition equipment with a 12bit resolution and 10[MS/s] sampling rate. The frequency bandwidth and responsitivity of the electric field measuring system were 40[Hz]${\sim}$2.6 [MHz] and 2.08 (V/m/mV) and those of the magnetic field measuring system were 400[Hz]${\sim}$1[MHz] and 2.78[nT/mV], respectively. The electric and magnetic fields produced by lightning discharges were observed, and the features and parameters of the waveforms were analyzed.

• Earthquakes and Structures
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• v.17 no.1
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• pp.63-73
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• 2019

This paper studies damage detection as an optimization problem. A new objective function based on changes in natural frequencies, and Natural Frequency Vector Assurance Criterion (NFVAC) was developed. Due to their easy and fast acquisition, natural frequencies were utilized to detect structural damages. Moreover, they are sensitive to stiffness reduction. The method presented here consists of two stages. Firstly, Finite Element Model (FEM) is updated. Secondly, damage severities and locations are determined. To minimize the proposed objective function, a new bio-inspired optimization algorithm called salp swarm was employed. Efficiency of the method presented here is validated by three experimental examples. The first example relates to three-story shear frame with two single damage cases in the first story. The second relates to a five-story shear frame with single and multiple damage cases in the first and third stories. The last one relates to a large-scale eight-story shear frame with minor damage case in the first and third stories. Moreover, the performance of Salp Swarm Algorithm (SSA) was compared with Particle Swarm Optimization (PSO). The results show that better accuracy is obtained using SSA than using PSO. The obtained results clearly indicate that the proposed method can be used to determine accurately and efficiently both damage location and severity in multi-story shear frames.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.59-66
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• 2005

This paper presents some features and statistics of electromagnetic pulses radiated from intracloud lightning discharges. The LabVIEW based-measurement system of time-dependent electromagnetic fields was constructed. The frequency bandwidth of the measuring system ranged from 300[Hz] to 1[MHz], and the response sensitivity was 2.78(mV/nT). The resolution and the maximum recording length of the data acquisition system were 12(bits) and 100[ms], respectively. In the electromagnetic pulses radiated from intracloud discharges, a pronounced bipolar pulse appeared with one or more fast pulses superimposed on the initial front part of the bipolar pulse. The mean duration of intracloud discharges was $1.05{\pm}0.32[ms]$, and an average of about 8 outburst pulses appeared for a period.