• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.4
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• pp.67-74
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• 2004

As data rate was increased, the conventional burst-mode automatic power control circuit caused errors due to the effort of the mark density variation. To solve this problem we invented a new structured peak-comparator which could eliminate the effect of the mark density variation even in high date rate, and revised the conventional one using it. We proposed a burst-mode automatic power control circuit robust to mark density variations. We found that the peak-comparator in the proposed automatic power control circuit was very robust to mark density variations because it affected very little by the mark density variation in high date rate and in the wide variation range of the reference current and the difference current.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.629-637
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• 2013

Chaos communication systems have the characteristics such as non-periodic, wide-band, non-predictability of signals and easy implementation. There have been many studies about chaos communication systems because of these advantages. But, chaos communication systems have low BER(Bit Error Rate) compare to general digital communication system. Existing researches on chaos communication systems only analyze BER performance according to various chaos maps. There are no studies on analysis of BER performance according to PDF(Probability Density Function) of chaos maps. In this paper, we analyze the BER performance according to changing parameter, equation, and initial values of chaos map's PDF. In addition, we propose new chaos map to improve BER performance. Simulation results show that BER performance of CDSK(Correlation Delay Shift Keying) is changed when PDF of chaos map changed. And the proposed chaos map has a better BER performance compare to previous chaos maps such as Tent map, Logistic map, and Henon map.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.11 s.353
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• pp.98-104
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• 2006

The conventional burst-mode APC(Automatic Power Control) circuit had an effective structure that was suitable for a low power consumption and a monolithic chip. However, as data rate was increased, it caused errors due to the effect of the zero density. In this paper, we invented a new structured peak-comparator which could compensate the unbalance of the injected currents using double gated MOS and MOS diode. And we proposed a new burst-mode APC adopting it. The new peak-comparator in the proposed APC was very robust to zero density variations maintaining the correct decision point of the current comparison at high data rate. It was also suitable for a low power consumption and a monolithic chip due to lack of large capacitors.

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.144-148
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• 1998

Soil microorganisms including bacteria, fungi, and actinomycetes were seasonally isolated at depths (0.5~2, $10{\pm}1$, $50{\pm}1cm$) of field. The frequency of microbial isolates was employed for the determination of microbial population (CFU/g dry soil) and distribution ratio (%) in soil. Both bacteria (24-fold) and actinomycetes (7-fold) exhibited the biggest change at the depth of $50{\pm}1cm$, whereas fungi showed the maximum (13-fold) at $10{\pm}1cm$. On the whole, the bacterial population was high in spring soil, fungi in winter, and actinomycetes in autumn. Soil microorganisms also exhibited the seasonal variation on their distribution ratio (%). The maximum distribution ratio (85.7%) of bacteria was observed at the depth of $50{\pm}1cm$ in spring, whereas bacteria showed the minimum (35.2%) at the depth of $10{\pm}1cm$ in spring. The maximum distribution ratio (23.0%) of fungi was found at the depth of $50{\pm}1cm$ in spring, whereas its minimum (0.5%) at the depth of $10{\pm}1cm$ in spring. Actinomycetes exhibited the maximum distribution ratio (45.2%) at the depth of $10{\pm}1cm$ in spring, whereas its minimum (12.2%) was showed at the depth of $50{\pm}1cm$ in spring.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.278-279
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• 2006

저온동시소성 다층세라믹스 시트 제조시 바인더 함량과 압력 변화에 따른 적층체의 그린밀도, 적층밀도, 바인더 burn out 후 그린밀도, 소결밀도를 고찰하였다. 바인더 함량이 증가함에 따라 slurrly의 유변학적 변화는 그린시트의 유동성 및 충진율을 변화시켜 그린시트의 밀도에 영향을 주었다. 적층 압력을 5~50MPa로 변화시켰을 때 바인더 함량이 12%로 가장 많은 시트의 경우 적층 후 시트의 밀도는 상대적으로 높은 밀도값을 나타내었으나, 바인더 burn out 후에는 상대적으로 낮은 밀도값을 나타내었다. 바인더 함량 변화에 따른 소결 밀도값은 큰 차이를 보이지 않았다.

• The Journal of Engineering Geology
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• v.13 no.4
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• pp.405-418
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• 2003

Measurements of volumetric water content and saturation of porous media are very important factors in understanding the physical characteristics of soil, groundwater recharge by rainfall, pollutant movement, and slope failure. To measure such physical parameters, a permittivity method using electromagnetic wave is applied and use is made of the special permittivity response of understand to water and ethanol. In particular, the estimation is required because permittivity is influenced by the nature of the underground environment. In this study, we carried out experiments on the relative dependency of soil density, temperature and salinity of standard sand and granitic weathered soil using FDR-V system (Frequency domain reflectometry with vector network analyzer) within a frequency range of 1 - 18 GHz. The results of the study showed that the dielectric constants of standard sand and granitic weathered soil increased with increased volumetric water content of soil. However, the dependency of soil density was found to be a little low. Changes of dielectric constant with temperature appeared definitely in the real part of 1 GHz. That is, the dielectric constant of real part at 1 GHz of water and standard sand increased with the rise of temperature. However, ethanol showed decreased tendency. The study also showed that dielectric constant increased with increase in salinity at imaginary part of 1 GHz. It could be concluded from this study FDR-V system can adequately measure the physical properties of soil and the degree of salinity concentration of porous media within 1 GHz frequency range using dielectric constant.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.79-79
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• 2003

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.161-166
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• 2006

Vertical gravity gradient measurement offers greater structural resolution and detectability than gravity alone. Practical difficulties of field measurement of vertical gravity gradient have raised questions of its accuracy and utility. But, modern automated gravimeter of $1\;{\mu}Gal$ sensitivity makes it easier to measure vertical gradient with required accuracy. It is particularly effective to engineering and environmental problems which target shallow subsurface structure. This paper attempts to apply the vertical gravity gradient technique to high resolution density mapping. The method was generally reviewed and numerical inverse modeling was executed for comparing with conventional gravity. And actual vertical gravity gradient data surveyed overt karstic cavity area at Muan was analysed and interpreted.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1999.07a
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• pp.221-227
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• 1999

베일러 작업에 있어 작업시의 볏짚의 함수율은 베일러의 작업성, 저장 중에 발생하는 볏짚의 물리적, 화학적 변화 등에 있어 중요한 요소로 작용한다. 국내의 경우 가을철에 청명하고 건조한 날이 많아 볏짚이 빠르게 건조되나 일기가 고르지 못한 경우에는 높은 함수율에서도 작업을 해야할 경우가 생긴다. 높은 함수율에서 작업하는 경우 필연적으로 베일의 질적 저하가 일어나는데 이를 줄이는 방법의 하나로 밀도를 조정하는 방법이 있다. (중략)

• Korean Journal of Food Science and Technology
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• v.22 no.4
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• pp.445-450
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• 1990

Changes in weight, volume and density of petiole tissue of Chinese cabbage during salting and blanching were investigated. Rapid changes in mass and volume occurred within 4 hours during salting in 5% salt solution and the changes were nearly completed after 8h. After salting, the reduction of mass and volume ranged between $22{\sim}27%\;and\;22{\sim}35%$, respectively. Average density of the sample was found to be 0.88g/ml, and increased to 1.020g/ml after salting. Air content of the sample ranged from 0.093 to 0.120ml/ml cabbage, and about 70% of the initial content was expelled from the tissue by salting. The changes of physical properties of the cabbage during steam blanching were similar to those during salting, but their relative values were smaller. A linearization model for physical changes during salting and blanching was proposed.