• Journal of Plant Biology
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• v.38 no.2
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• pp.181-193
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• 1995

Cuticle micromorphology of four families of Korean gymnosperms, Cycadaceae, Ginkgoaceae, Taxaceae, and Cephalotaxaceae, were studied with scanning electron microscopy. The outer and inner features of abaxial and adaxial cuticles were described in details; the absent or present of Florin ring, orifice, trichome, and plug and their shape, the shape and periclinal and anticlinal wall sculpture of epidermal cells, the shape of cuticular flange of epidermal cell, guard cell, and subsidiary cell, the number of stomatal bands and rows, and stomatal apparatus including the shape of polar extension, number of subsidiary cells, the sculpture of guard cell and subsidiary cell. Most of these features have not been sufficiently substantiated by the previous reprots. Furthermore, all the species investigated showed distinctive cuticle morphology with morphological and taxonomical informations.

• Journal of Photoscience
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• v.4 no.2
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• pp.35-40
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• 1997

The sensory transduction processes of blue light in guard cells have been suggested the involvement of Ca$^{2+}$/calmodulin-dependent myosin light chain kinase (MLCK) or MLCK-like proteins. The source of Ca$^{2+}$ required for the signal transduction process was investigated in guard cell protoplasts (GCPs). The GCPs showed the typical H$^+$ pumping activity by blue light (200 $\mu$mol m$^{-2}$ s$^{-1}$) and fusicoccin (10 $\mu$M) under background red light (600 $\mu$mol m$^{-2}$ s$^{-1}$). The blue light-dependent H$^+$ pumping was not significantly affected by the externally changed Ca$^{2+}$ concentrations. The addition of 1 mM Ca$^{2+}$ in the bathing medium ratherly inhibited the H$^+$ pumping. In contrast, the blue light-dependent H$^+$ pumping was inhibited by caffeine and 2,5-di-(tert-butyl)-1,4-benzohydroquinone (BHQ), inhibitor of C$^{2+}$-ATPase in endoplasmic reticulum (ER) without inhibiting the H $^+$ pump. The inhibition by caffeine and BHQ was fully reversible. The extent of inhibition by caffeine and BHQ was larger when they were added together than when added separately. The results suggest that Ca$^{2+}$ required for the blue light-dependent H$^+$ pumping may be released from the intracellular Ca$^{2+}$ stores, probably ER in guard cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.482-483
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• 2007

For measurement of dielectric constants, the commercial parallel plate electrodes system with guard-ring electrode have been widely used up to now. The capacitance derived from the parallel plate electrodes capacitor with guard-ring electrode is calculated by the equation of ($C={\epsilon}\;{\cdot}\;\frac{area\;of\;electrod}{distance\;between\;electrodes}$). Therefore, in parallel plate electrode capacitor, the diameter of the guarded electrode, the gap size between guarded electrode and guard ring, and distance between two active electrode should be measured precisely to calculate dielectric constants from the measured capacitance. Consequently their mechanical measurement uncertainties are directly contributed. Especially the air-gap between the electrodes and dielectric specimen at the system must be existed and the measurement error derived from the air-gap is impossible to evaluate as measurement uncertainties. In this study, we analyze the uncertainty of the commercial dielectric constant test cell using 3 kinds CRMs.

• Korean Journal of Environmental Biology
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• v.23 no.3 s.59
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• pp.221-227
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• 2005

The effects of light and $CO_2$ on the electrophysiological characteristics of guard cells in the intact leaf and isolated epidermis have been investigated. Fast hyperpolarization of guard cell apoplastic PD in the intact leaf was recorded reaching up to around 7 mV and 20 mV in response to light and $CO_2$. Whenever the experiments were attempted with isolated epidermis, there was no response to light and $CO_2$. In order to determine the influence of the mesophyll cells, the apoplastic PD of guard cells in isolated epidermis was measured in the presence of the mesophyll supernatant or the control medium. The apoplastic PD in isolated epidermis was hyperpolarized to -7mV, changing from -22mV to -29mV at 40 min. But, when isolated epidermis was incubated with the supernatant from mesophyll cells incubated in the light, the apoplastic PD in isolated epidermis was hyperpolarized to -19 mV, changing from -22 mV to -40.5 mV. $CO_2$ also caused a change of 0.1 to 0.3 pH unit in the intact leaf. However, this change was absent in isolated epidermis. A vibrating probe was used to detect the change in electrical currents at the surface of excised intact leaves and isolated epidermis. The reading of excised intact leaves in the dark was $0.5\muA\;cm^{-2},$ remaining steady until illuminated. Light increased the current on the surface of excised leaves to about $0.8\muA\;cm^{-2},$. However, light had no effect in the current on the surface of isolated epidermis. Apoplastic pH changes across the stomatal complex in response to light and dark were measured both in the intact leaves and isolated epidermis over the same time period using pH micro-electrodes. The guard cell wall of intact leaf was acidified to 2.5 pH unit, falling from pH 7.5 to pH 5.0 in the first 10 min. in the light. At the same time the guard cell wall pH of isolated epidermis fell from pH 7.5 to pH 7.0 at 10 min. The guard cell wall pH of isolated epidermis incubated in the mesophyll supernatant fell from pH 7.6 to pH 6.7 at 10 min. Likewise, It could be imagined that an electrical signal, chemicals and hormones propagated from the mesophyll in response to light and $CO_2$ could control a fast stomatal response.

• Asian Journal of Turfgrass Science
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• v.11 no.1
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• pp.23-31
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• 1997

The K+ and Na+ contents in the guard cells of Agave which had a characteristic of CAM plant were measured by using "Rolling technique". That results were correspond with the change of the stomatal aperture width. That is to say, stomatal movement of Agave is due to the change of K+and Na+ concentration in the guard cells. As Agave which was used in this experiment showed two peaks of which one was at 3 hour and the other was at 24 hour in stomatal aperture width, it was seemed that Agave had both characteristics of CAM and $C_3$pattern.

• Journal of Photoscience
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• v.9 no.2
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• pp.335-337
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• 2002

Blue light (BL) induces stomatal opening through activation of H$^{+}$ pump, which creates electrical gradient across the plasma membrane for $K^{+}$ uptake into guard cells. The pump is the plasma membrane H$^{+}$ -ATPase and is activated via phosphorylation of the C-terminus with concomitant binding of the 14-3-3 protein. The opening is initiated by the perception of BL through phototropin (phot), which are recently identified as BL receptors in stomatal guard cells. In this study, we provide the biochemical evidence for phots as BL receptors in stomatal guard cells. vfphot was phosphorylated reversibly by BL, and phosphorylation levels of vfphot increased earlier than those of the plasma membrane W-ATPase. BL-dependent phosphorylations of vfphot and H$^{+}$-ATPase showed similar fluence dependency. Staurosporin, an inhibitor of serine/threonine protein kinase, and diphenyleneiodonium chloride (DPI), an inhibitor of flavoprotein, inhibited BL-dependent phosphorylations of vfphot and H$^{+}$ -ATPase. These results indicate that vfphot acts as a BL-receptor mediating stomatal opening.l opening.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.417-425
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• 2007

While the cyclic prefix lengths of downlink OFDMA(Orthogonal Frequency Division Multiple Access) systems are determined based on the maximum delay spreads encountered in cellular environments, the guard interval of uplink OFDMA systems should consider the timing offsets of uplink signals as well as the delay spread lengths. Especially in the cases of initial accesses, handovers, and considerable time elapsed without data transmissions between base and mobile stations in a large cell, uplink timing offsets can be large and a very long guard interval length may be required. In order to keep the small size of the cyclic prefix in uplink OFDMA systems, the systems require a method of extending the guard intervals for users with large timing offsets without affecting the cyclic prefix length of the system. This paper proposes a method extending the guard intervals of individual users in uplink OFDMA systems.

• Journal of Navigation and Port Research
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• v.38 no.1
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• pp.53-57
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• 2014

This thesis, concentrates on marine collision risks of the area divided by cells. Using a gas molecular collision calculation model, a collision risk model is proposed. Collision risk is estimated by relative angle, relative speed, and ship's density in the cell. For one week, Automatic Identification System (AIS) data was collected and analyzed on the Busan North Port area. The results indicate a high-risk area at the sea route connection point in Busan North Port. It also shows that twilight is the time of day when most collisions occur. This means that the area is high risk due to the number of collisions and other dangerous factors related to twilight. Although there is still need to consider other risks such as grounding risks, the results of this study are useful to for plotting a risk map for the port.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.129-132
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• 2004

A guard lamp system has been installed at the PV positive center, located at Gwangju in Korea. Digital environment that is represented to internet is displacing business way of industry and business achievement way with the fast speed being giving great change on life whole, improve existence business process utilizing internet and Web connection technology, information superhighway to tradition industrialist manufacture and e-transformation's propulsion that wish to maximize productivity and administration efficiency is spread vigorously. In this paper, we wish to accomplish generation equipment's heighten stability and believability through remote monitoring and control of guard lamp system. This paper describes the design of the monitoring system for the sensing data and indirect controlling of the guard lamp system. Most of the conventional monitoring systems depend on the special hardware and software. The essential design of monitoring system is to provide the convenience for the user and the portability for the system. In order for the system to fulfill its requirements, it was designed using Labview GUI facility based on the Windows 2000 environment of IBM PC compatible and Add-oncard based on the TCP/IP protocol. Advantage of the monitoring system are a personnel expenses curtailment effect, of the place restriction and unmanned system of the generationplants, etc..

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.4 s.334
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• pp.21-28
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• 2005

SC-FDE (Single Carrier with Frequency-Domain Equalization), one of physical layers of IEEE802.16, is less sensitive to nonlinear power amplifiers than OFDM while its complexity and performance is comparable. The guard interval length in SC-FDE should be greater than the maximal delay spread. While a delay spread is small in most wireless communication environments, a very large delay spread can be possibly encountered in the mountain areas or due to the repeaters. This paper proposes SC-FDE with variable-length guard intervals. In the proposed method the guard interval length can be determined per each cell or per each subscriber stations.