• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.593-603
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• 2005

Passive sampler using 4-amino-3-hydrazino-5-mercapto-1, 2, 4-triazole (AHMT) was developed to determine formaldehyde in indoor environment. The chromatography paper cleaned by $3\%$ hydrogen peroxide solution was experimently determined as a optimum absorbtion filter for the collection of formaldehyde. The passive sampler with a broad cross-sectional area and a short diffusion length was quite good in sensitivity. The passive sampler and the active sampling method with an impinger were strongly correlated with a correlation coefficient of 0.9848. The limits of detection and quantification of the passive sampler for the measurement of formaldehyde in the indoor environment were 7.5 and 10.2 ppb, respectively. Temperature ($19\∼28^{circ}C$) and relative humidity ($30\∼90\%$) had slight influence on the sampling rate of the passive sampler. However, the increase of flow velocity on the surface of sampler resulted in the increase of sampling rate.

• 전자공학회논문지 IE
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• v.43 no.3
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• pp.6-12
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• 2006

This paper described an 8bit, 100Msample/s CMOS D/A converter using a glitch-time minimization technique for the high-speed sampling rate of 100MHz level. The proposed DAC was implemented in $0.35{\mu}m$ Hynix CMOS technology and adopts a current mode architecture to optimize sampling rate, resolution, chip area. The DAC linear characteristics was similar to the proposed specification and the prototype error between DNL and INL is less than $\pm$0.09LSB respectively. Also, the manufactured DAC chip was analyzed the cause of error operation and proposed the field considerations for chip test.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.3
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• pp.370-378
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• 2018

The mission data in missile systems should be quickly and reliably transmitted from a mission transmission device to a guidance control unit. The MIL-STD-1553B is one of the reliable communication standards, but its bit rate is generally limited to 1Mbps due to the intrinsic properties of its electrical design. Therefore, the bus controller needs to be optimized to efficiently transmit the mission data on the inevitably limited bit rate. This paper proposes an analytical approach based on sampling-based optimization methods to maximize the data throughput without data loss. The proposed approach was evaluated in the simulations with the data transmission model for the MIL-STD-1553B communication system. The results of the proposed methods were applied to a real-time system and showed that the proposed method was successfully performed.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2
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• pp.52-57
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• 2001

The passive ranging estimation techniques using a focused beamformer have been studied under the water. It is well known that the passive ranging estimation method using a focused beamformer is excellently evaluated. Among these, the passive ranging sonar is known to have a good performance under low signal-to-noise. ratio. However, its performance is degraded in multi-source environments. In this paper, we proposed the technique using dual focused beamformers to estimate the range. And when the sampling frequency is low, it is very difficult to steer the focused beam to the desired direction, as a result of this, the low performance occurs because of a distorted beam pattern. In this paper, we study the effect of sampling rate on passive ranging by using focused beamformer. And we verified the performance of the proposed method via computer simulation.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.101-108
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• 2020

In order to solve the contradiction between requirements of high sampling rate for acquiring accurate energy information of pulses and large amount of data to be processed timely, the method with an algorithm to correct errors caused by reducing the sampling rate is normally used in front-end read-out system, which is conductive to extract accurate energy information from digitized waveform of pulse. The functions and effects of algorithms, which mainly include polynomial fitting with different fitting times, double exponential function fitting under different sampling modes, and integral area algorithm, are analyzed and evaluated, and some meaningful results is presented in this paper. The algorithm described in the paper has been used preliminarily in a prototype system of Positron Emission Tomography (PET) for heavy-ion cancer therapy facility.

• Journal of Ecology and Environment
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• v.47 no.2
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• pp.35-41
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• 2023

Background: Several species of amphibians in agricultural areas are often infected with ranaviruses; however, the biological or ecological factors that cause this infection are not well understood. In this study, we investigated whether local tadpole density, Gosner developmental stage, and weather conditions affected ranavirus infection in Dryophytes japonicus tadpoles in rice paddies over three months. Results: During the study, eight samplings were undertaken between June 6 and August 21, 2022. No die-off of tadpoles occurred, but 20 of 110 tadpoles (18.8%) were found to be infected with ranavirus. The tadpole density at the sampling site and Gosner stage of the sampled tadpoles were not related to the daily ranavirus infection rate. The mean daily highest temperature during the two weeks prior to the sampling date and the mean daily lowest and highest temperatures during the week prior to the sampling date were negatively related to the daily infection rate. Conclusions: Our results suggest that low and extreme temperatures caused by flooding and draining of paddy fields or climate change in summer could be a significant risk factor for ranavirus infection in summer-breeding frogs in agricultural areas.

• Sleep Medicine and Psychophysiology
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• v.6 no.1
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• pp.52-60
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• 1999

Objectives: With the object of finding the appropriate conditions and algorithms for dimensional analysis of human EEG, we calculated correlation dimensions in the various condition of sampling rate and data aquisition time and improved the computation algorithm by taking advantage of bit operation instead of log operation. Methods: EEG signals from 13 scalp lead of a man were digitized with A-D converter under the condition of 12 bit resolution and 1000 Hertz of sampling rate during 32 seconds. From the original data, we made 15 time series data which have different sampling rate of 62.5, 125, 250, 500, 1000 hertz and data acqusition time of 10, 20, 30 second, respectively. New algorithm to shorten the calculation time using bit operation and the Least Trimmed Squares(LTS) estimator to get the optimal slope was applied to these data. Results: The values of the correlation dimension showed the increasing pattern as the data acquisition time becomes longer. The data with sampling rate of 62.5 Hz showed the highest value of correlation dimension regardless of sampling time but the correlation dimension at other sampling rates revealed similar values. The computation with bit operation instead of log operation had a statistically significant effect of shortening of calculation time and LTS method estimated more stably the slope of correlation dimension than the Least Squares estimator. Conclusion: The bit operation and LTS methods were successfully utilized to time-saving and efficient calculation of correlation dimension. In addition, time series of 20-sec length with sampling rate of 125 Hz was adequate to estimate the dimensional complexity of human EEG.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1C
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• pp.14-23
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• 2003

This thesis proposes a sigma-delta modulator architecture with 2 Ms/s data rate and 12 bit resolution. A sigma-delta modulate has the features of oversampling and noise shaping. With these features, it can be connected with low resolution A/D converter to achieve higher resolution A/D converter. Most previous researches have been concentrated on high resolution but low data rate applications, e.g. audio applications. But, in order to be applied to various applications such as wireless data communication, researches on sigma-delta modulator architecture for higher data rate are required. The proposed sigma-delta modulator architecture has the sampling rate of 16 times Nyquist rate to achieve high data rate, and consists of a cascade of two 2nd order sigma-delta modulator to get relatively high resolution. The experimental result shows that the proposed architecture achieves 12-bit resolution at 2 Ms/s data rate.

• Journal of Applied Reliability
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• v.1 no.2
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• pp.183-192
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• 2001

Jelinski-Moranda model and modified Jelinski-Moranda model in software reliability are studied and we consider maximum likelihood estimator and Bayes estimates of the number of faults and the fault-detection rate per fault. A gibbs sampling approach is employed to compute the Bayes estimates, future survival function is examined. Model selection based on prequential likelihood of the conditional predictive ordinates. A numerical example with simulated data set is given.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.1
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• pp.37-43
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• 2003

A faster autofocusing method is proposed. The searching speed of microscope camera is limited by the long focusing time due to too much sampled digital image data. The improvement of autofocusing speed based on the down sampling is discussed analytically and is proved by experiments. The anticipated aliasing is found negligible in shilling rate of focus measure.