• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.17-24
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• 2000

The peroxidase activity was localized cytochemically to get an insight into its precise function in lignin biosynthesis. In this work, cerium chloride ($CeCl_3$) was used as a trapping agent for hydrogen peroxide ($H_2O_2$) generated from peroxidase. Seasonal variation of peroxidase activities in cambial region of Populus, Pinus, and Ginkgo was investigated at subcellular levels. Under transmission electron microscopy, electron dense deposits of cerium perhydroxide formed by reaction with $H_2O_2$ were observed in cambium and its immediate derivatives. The staining with $CeCl_3$ in cambium varied with growth seasons. The strongest $H_2O_2$ accumulation, regardless of tree species, appeared in May. Staining pattern of $CeCl_3$ in the cambium of poplar indicated that the production of peroxidase started in March before the opening of buds and reached the highest in May and then declined in August. Ginkgo and Pinus showed relatively late generation of $H_2O_2$ production when compared with Populus. Although Ginkgo and Pinus are classified into gymnosperms, however, the generation of peroxidase production and its duration was different from each other. Little staining appeared in all the tree samples collected in September before falling the leaves.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.235.2-235.2
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• 2015

The front transparent conductive oxide (TCO) films must exhibit good transparency, low resistivity and excellent light scattering properties for high efficiency amorphous silicon (a-Si) thin film solar cells. The light trapping phenomenon is limited due to non-uniform and low aspect ratio of the textured glass [1]. We present the low cost electrochemically deposited uniform zinc oxide (ZnO) nanorods with various aspect ratios for a-Si thin film solar cells. Since the major drawback of the electrochemically deposited ZnO nanorods was the high sheet resistance and low transmittance that was overcome by depositing the RF magnetron sputtered AZO films as a seed layer with various thicknesses [2]. The length and diameters of the ZnO nanorods was controlled by varying the deposition conditions. The length of ZnO nanorods were varied from 400 nm to $2{\mu}m$ while diameter was kept higher than 200 nm to obtain different aspect ratios. The uniform ZnO nanorods showed higher haze ratio as compared to the commercially available FTO films. We also observed that the scattering in the longer wavelength region was favored for the high aspect ratio of ZnO nanorods and much higher aspect ratios degraded the light scattering phenomenon. Therefore, we proposed our low cost and uniform ZnO nanorods for the high efficiency of thin film solar cells.

• 한국해양학회지
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• v.20 no.3
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• pp.6-19
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• 1985

Hydrographic data and daily time series of longshore wind, sea level and sea surface temperature were used in order to explain why the upwelling effect in SST is especially prominent near Ulgi-Gampo although the sea level records along the whole southeast coast show a nearly uniform upwelling-downwelling response to wind. Regional difference in intensity of the wind-induced upwelling represented by the SST decrease is attributed to the combined influence of two factors; one is the baroclinic tilting of isotherms due to the East Korea Warm Current (EKWC) near the Ulgi-Gampo coast, the other is the topographic effects around the southeast coast. Baroclinic tilting effect of EKWC which is generally strongest near the coast of Ulgi to Gampo results in both of the shoaling of cold water and the westward trapping of the coldest bottom water over the shallower shelf rather than the deepest troough region off that coast regardless of the season. Therefore, becacse of the cold water ready for upwelling at the subsurface layer, SST responds very rapidly to the upwelling-favorable winds of summer only off the Ulgi-Gampo coast. Spreading isobaths from Pusan to Gempo can reinforce the upwelling of the cold bottom water and its westward trapping.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.122-122
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• 2012

Geosynchronous electron flux dropouts are most likely due to fast drift loss of the particles to the magnetopause (or equivalently, the "magnetopause shadowing effect"). A possible effect related to the drift loss is the radial diffusion of PSD due to gradient of PSD set by the drift loss effect at an outer L region. This possibly implies that the drift loss can affect the flux levels even inside the trapping boundary. We recently investigated the details of such diffusion process by solving the diffusion equation with a set of initial and boundary conditions set by the drift loss. Motivated by the simulation work, we have examined observationally the energy spectrum and pitch angle distribution near trapping boundary during the geosynchronous flux dropouts. For this work, we have first identified a list of geosynchronous flux dropout events for 2007-2010 from GOES satellite electron measurements and solar wind pressures observed by ACE satellite. We have then used the electron data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measurements to investigate the particle fluxes. The five THEMIS spacecraft sufficiently cover the inner magnetospheric regions near the equatorial plane and thus provide us with data of much higher spatial resolution. In this paper, we report some case studies showing energy dependence during magnetopause shadowing effect.

• Tribology and Lubricants
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• v.14 no.2
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• pp.63-74
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• 1998

The damage of cam/tappet surface is one of the major reasons for energy loss in an I.C. engine. High friction causes the accelerated wear of the cam/tappet surfaces which in turn changes the valve opening/closing timing. During the accelerated test evidence of both rolling fatigue and sliding abrasive wear could be found. Based on the results of the accelerated test, a scheme was devised to decrease tappet wear. Wear reduction of the tappet was achieved by using undulated surface topography in the tappet center region. The wear reduction is achieved by trapping of the wear particles in the undulations as well as by increasing the supply of lubricant to the sliding interface.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.2
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• pp.185-191
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• 1992

In this paper, it is attempted to distinguish the charged particles and to judge the polarity by the use of Thermally Stimulated Current(TSC) and Temperature Gradient Thermally Stimulated Surface Potential Measurement(TG-TSSP)with experimental insulation material XLPE-EVA for power cables which is made by blending cross-linked polyethylene(XLPE) and ethylene-vinylacetate copolymer(EVA). In addition, it is performed to investigate the effect of EVA blending. From the experimental results, it is known that for the case of XLPE-EVA blended experimental material, the generation of space charged electric field is not obtained in the high temperature region due to the obatruction of the injection of trapping carrier by the electron and the positive hole.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.505-508
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• 2006

Self-heating induced device degradation and its width/length (W/L) dimension dependence were studied in p-type polycrystalline silicon (poly-Si) thin film transistors (TFTs). Negative channel conductance was observed under high power region of output curve, which was mainly caused by hole trapping into gate oxide and also by trap state generation by self-heating effect. Self-heating effect became aggravated as W/L ratio was increased, which was understood by the differences in heat dissipation capability. By reducing applied power density normalized to TFT area, self-heating induced degradation could be reduced.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.4
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• pp.77-83
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• 1994

In this paper we numerically approximated the field-effect mobility of a-Si:H TFT. Field-effect mobility, based on the charge-trapping model and new effective capacitance model in our study, used Chebyshev approximation was approximated as the function of gate potential(gate-to-channel voltage). Even though various external factors are changed, this formula can be applied by choosing the characteristic coefficients without any change of the approximation formula corresponding to each operation region. Using new approximated field-effect mobility formula, the dependences of field-effect mobility on materials and thickness of gate insulator, thickness of a-Si bulk, and operation temperature in inverted staggered-electrode a-Si:H TFT were estimated. By this was the usefulness of new approximated mobility formula proved.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.8
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• pp.126-132
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• 1995

The electrical stress of short channel polycrystalline silicon (poly-Si) thin film transistor (TFT) has been investigated. The device characteristics of short channel poly-Si TFT with 5$\mu$m channel length has been observed to be significantly degraded such as a large shift in threshold voltage and asymmetric phenomena after the electrical stress. The dominant degradation mechanism in long channel poly-Si TFT's with 10$\mu$m and 20$\mu$m channel length respectively is charage trappling in gate oxide while that in short channel device with 5.mu.m channel length is defect creation in active poly-Si layer. We propose that the increased defect density within depletion region near drain junction due to high electric field which could be evidenced by kink effect, constitutes the important reason for this significant degradation in short channel poly-Si TFT. The proposed model is verified by comparing the amounts of the defect creation and the charge trapping from the strechout voltage.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.590-593
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• 2002

Using two- and three-dimensional fluid simulation codes, we have suggested several new plasma display panel (PDP) cell structures that have high luminous efficiency compared with conventional structure. To improve the luminance and discharge efficiency, we utilize long discharge path, lower electric field region, and reduction of power consumption by adding one auxiliary electrode or reducing the electrode area. Consequently, luminous efficiency increases about 1.8 times. Furthermore for the resonance radiation trapping effect in PDP system, we have described a self-consistent radiation transport model coupled with fluid simulation using modified Holstein's equation.