• The Journal of the Korea Contents Association
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• v.8 no.5
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• pp.192-206
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• 2008

With many changes such as the increase in telemarketing, internet marketing and enforcement of bancassurance, the Korean life insurance companies have undergone a startling transformation. The purpose of this paper is to measure and analyse the static/dynamic efficiency of Korean life insurance companies employing Data Envelopment Analysis(DEA). As the result of the static efficiency analysis, we provide CCR, BCC and scale efficiency, return to scale, and reference set of Korean life insurance companies in 2004. And we also describe about the trend and stability of their efficiency for 7 years(1998-2004) in the dynamic efficiency analysis.

• Spatial Information Research
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• v.16 no.2
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• pp.219-236
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• 2008

Data stream collected from sensors contain a large amount of useful information including causality relationships. The causality join query for data stream is to retrieve a set of pairs (cause, effect) from streams of data. A part of causality pairs may however be lost from the query result, due to the delay from sensors to a data stream management system, and the limited size of sliding windows. In this paper, we first investigate spatial, temporal, and spatio-temporal aspects of the causality join query for data stream. Second, we propose several strategies for sliding window management based on these observations. The accuracy of the proposed strategies is studied by intensive experiments, and the result shows that we improve the accuracy of causality join query in data stream from simple FIFO strategy.

• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.432-440
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• 2023

This study introduces an efficient readout circuit designed for two-electrode electrocardiogram (ECG) recording, characterized by its low-noise and low-power consumption attributes. Unlike its three-electrode counterpart, the two-electrode ECG is susceptible to common-mode interference (CMI), causing signal distortion. To counter this, the proposed circuit integrates a common-mode charge pump (CMCP) with a window comparator, allowing for a CMI tolerance of up to 20 V_PP. The CMCP design prevents the activation of electrostatic discharge (ESD) diodes and becomes operational only when CMI surpasses the predetermined range set by the window comparator. This ensures power efficiency and minimizes intermodulation distortion (IMD) arising from switching noise. To maintain ECG signal accuracy, the circuit employs a chopper-stabilized instrumentation amplifier (IA) for low-noise attributes, and to achieve high input impedance, it incorporates a floating high-pass filter (HPF) and a current-feedback instrumentation amplifier (CFIA). This comprehensive design integrates various components, including a QRS peak detector and serial peripheral interface (SPI), into a single 0.18-㎛ CMOS chip occupying 0.54 mm². Experimental evaluations showed a 0.59 µV_RMS noise level within a 1-100 Hz bandwidth and a power draw of 23.83 µW at 1.8 V.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.1
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• pp.52-58
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• 2006

Single-electron transistor (SET)-based logic cells and SET/FET hybrid integrated circuits have been fabricated on SOI chips. The input-output voltage transfer characteristic of the SET-based complementary logic cell shows an inverting behavior where the output voltage gain is estimated to be about 1.2 at 4.2K. The SET/FET output driver, consisting of one SET and three FETs, yields a high voltage gain of 13 and power amplification with a wide-range output window for driving next circuit. Finally, the SET/FET literal gate for a multi-valued logic cell, comprising of an SET, an FET and a constant-current load, displays a periodic voltage output of high/low level multiple switching with a swing as high as 200mV. The multiple switching functionality of all the fabricated logic circuits could be enhanced by utilizing a side gate incorporated to each SET component to enable the phase control of Coulomb oscillations, which is one of the unique characteristics of the SET-based logic circuits.

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.758-762
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• 2011

In this paper an efficient algorithm is proposed to remove additive white Gaussian noise(AWGN) with edge preservation. A function is used to separate the filtering mask to two sets according to the direction information. Then, we calculate the mean and standard deviation of the pixels in each set. In order to preserve the details, we also compare standard deviations between the two sets to find out smaller one. Corrupted pixel is replaced by the mean of the filtering window's median value and the smaller set's mean value that the rate of change is faster than the other one. Experiment results show that the proposed algorithm outperforms with significant improvement in image quality than the conventional algorithms. The proposed method removes the Gaussian noise very effectively.

• Journal of KSNVE
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• v.4 no.3
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• pp.295-305
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• 1994

The reflection coefficient of a material at oblique incidence is measured in a free field. The sound pressure distributions are measured at discrete points on two measurement lines and then decomposed into plane wave components by using spatial Fourier transform. The inciedent and reflected plane wave components are obtained from a set of "decomposition equations" of which uses the plane wave propagation theory. Numerical simulations and experiments have been performed to see the effect of finite size of measurement area. To reduce this effect, a window fuction has been performed to see the effects of finite size of mesurement area. To reduce this effect, a window function has been proposed and its effect on the measurement of sound absorbing material property has been studied as well. The reflection coefficient obtained by this method is compared with those obtained from other methods; 2-microphone method in a duct and an expirical equation of which determines the characteristic impedance .rho.c and propagation constant k of a material from flow resistance information.formation.

• Current Photovoltaic Research
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• v.5 no.1
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• pp.28-32
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• 2017

In this paper, (Ga,Al):ZnO layers were deposited by sputtering to evaluate the device performance according to the thickness of the layer. As the thickness increased, low transmittance was observed, but the electrical resistance was improved. On the other hand, the highest efficiency was recorded at 400 nm device than a 500 nm of it. Therefore, since the critical thickness exists, it is necessary to set an adequate TCO layer thickness in consideration of the characteristics of the underlying film and the device.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2401-2408
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• 1997

The measured pulse shapes provided in the given data package demonstrated pulse distortions due to laser speckle. the distorted pulse shapes were carefully analyzed, modeled, and then applied to the DTTL(Digital-data Transition Tracking Loop)[1] bit synchronizer simulator to measure the mean time delay and its delay variation performance. The result showed that the maximum mean time delay variation with the modeled data was 12.5% when window size equals 1. All the data given were located within this modeled boundary and the maximum eman time delay variation was 7% in this case. The mean time delay variation was known to be smaller by reducing the window size [2][5][6]. The mitigated delay variation was 2.5% in the modeled case and 1.4% in the data set given when the windown size equals 0.1. With the digital DTTL insteal of analog DTTL, similar results was obtained.

• Journal of the Korean Solar Energy Society
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• v.30 no.1
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• pp.13-18
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• 2010

This research investigated the exhaust gas purification system of gaseous ozone for pigpens. This system is applied to exhaust the gas outside after purification with ozone. This is very effective for purification and simple. And because this is not set in the pigpens, this system is not influence of pollution gas. This is effected to extend the life time of this system and this system is applied for non-window pigpens which does not need the ventilation.

• 한국해양학회지
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• v.19 no.2
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• pp.133-140
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• 1984

Oceanographic applications of digital filters are studied with special emphasis on the convolution filter with Hamming window and the recursive filters. Convolution filters are simple to understand and easy to design but not efficient for a long data set. Recursive filters, despite of the complexities, have advantages on economy and filter characteristic. By means of digital filtering technique we find that the alongshore wind at Pusan and the sea surface temperature at Gampo in summers during 1973 to 1979 are negatively correlated at low frequencies (periods longer than 5 days) but not so at high frequencies.