• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.4
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• pp.411-420
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• 2016

Efforts have continued in recent years to research and develop new alternative energy sources to replace coal and oil. These days interest is exploding in new pollution-free renewable energy due to the rising prices of finite energy sources. In the field of solar energy, one of new renewable energy that has been actively researched and commercialized, research efforts have been focused on solar light energy, whose efficiency has, however, reached a saturation point already. Thus, this paper proposed a solar tracking-type parabolic heat collection device to utilize solar thermal energy rather than solar light energy. The proposed device was designed in a parabolic form to collect solar heat effectively. The investigator made its prototype by incorporating a five-axis censor-based solar tracking technology in it to sense changes to the location of the sun according to the seasons and periods. In addition, an administrator interface was designed and implemented for the efficient management of heat collection device.

• Korean Journal of Plant Resources
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• v.29 no.4
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• pp.393-399
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• 2016

This study was conducted to elucidate the photosynthetic response to the environment and establish optimum cultivation conditions for the Korean endemic plant, Aster koraiensis. Photosynthetic characteristics according to growth stage, light, CO₂, and soil water potential were investigated. During the first year of transplanting, photosynthetic rates were drastically increased until June, after which they slowly declined, During the second year, photosynthetic rates declined throughout the entire growth period. The highest level of light compensation point was shown the early growth stage. Photosynthetic rates affected by intercellular CO₂ concentration were maintained or decreased over the CO₂ saturation point. The lowest CO₂ compensation point was 16.1 μmol·mol⁻¹ during March. The morphological changes of leaves were observed due to shading with chlorophyll contents increasing. Photosynthetic rates were higher at 0% and 50% shading treatments than at 75%. There were rarely any morphological changes of leaves due to soil moisture, however, changes to leaf compactness were observed. Photosynthetic rate, apparent quantum yield, and respiration rate increased, whereas water use efficiency decreased over −25 kPa of soil moisture.

• Korean Institute of Interior Design Journal
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• v.21 no.1
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• pp.40-50
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• 2012

This study aims at suggesting the applicability of color combination based upon the characteristics of environmental color perception and the nuance concept of Natural Color System(NCS). The results are summarized below: First, NCS is a scientific coloring system in consideration of the relevance between people, light and environment, to be based on a phenomenological point of view. NCS can be called a psychometric model reflecting our natural color sense. Second, the color triangle established by NCS is one of the methods of expression based on the human visual mechanism, which is classified by two attributes of hue and nuance, not by the three color attributes of hue, lightness and saturation. The nuance concept of NCS implies the impression, atmosphere and tone that are perceived in colors, which are related to lightness and saturation. Accordingly, this paper suggests that the coloring arrangement emphasizing nuance and tone is more useful than hue in color planning. Third, aesthetic impression in environmental color perception is inclusive of instantly perceptive nuance, which is connected with affordance. The affordance is revealed by the different relation of similarity. In this regard, a strong relationship is noticed between color combination and the sense of pleasantness. The hypothesis regarding the complementation and similarity of contrasting nature is judged to provide observers with aesthetic order. Finally, this paper also suggests four harmonizing methods in the NCS color triangle based upon equal blackness, equal whiteness, equal chromaticness and same nuance. At the same time, opposition and a different concept of hue, lightness and lightness are combined complementarily with the nuance value to suggest patterns of color combination.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.2
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• pp.90-96
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• 1999

Foliar and physiological characteristics of Schisandraceae plants distributed in Korea were investigated to elucidate differences in growth and the variations of inter and intra species of the plants. For this study, three species of Schisandraceae plants were used; i) Schisandra chinensis, decidious broad-leaved tree, ii) S. nigra, decidious broad-leaved tree, including monoecious, male and female types, ii) Kadsura japonica, evergreen broad-leaved tree. There were no significant differences in leaf length and width among three species, but leaves of Schisandra sp. plants were shorter and wider relative to those of K. japonica. The length of petiole of Schisandra sp. plants was greater than that of K. japonica and the difference was evident between female type of S. chinensis and K. japonica as longer as two times. Schisandra sp. trees showed larger size of stomata, but fewer numbers of stomata, compared with K. japonica. Although substantial changes in leaf morphology were not found in the Schisandraceae plants grown in different environmental conditions, the foliar length of K. japonica was seemed to be increased with increasing an altitude. Chlorophyll contents were also variable in inter and intra species and in, general K. japonica showed higher levels of chlorophyll contents relative to Schisandra sp. plants. K. japonica also showed higher light compensation point(LCP), light saturation point(LSP) and $CO_2$ assimilation rates at LSP, compared with Schisandra sp. trees. However, Schisandra sp. trees showed lower respiration per photosynthesis rates at LSP. The finding suggested that Schisandra sp. trees were acclimated to the growth conditions of lower light intensity with more effective photosynthetic activity. This was also confirmed by the fact that Schisandra sp. plants grown in shading places of a forest demonstrated the elevated rates of net $CO_2$ assimilation under the conditions of low light intensity.

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.151-155
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• 1983

Photosynthetic activity of two rice varieties "Suweon 318, Nagdongbyeo" and two species of grass weeds, two species of sedge weeds, and four species of broadleaf weeds was measured at 5, 10, 20, 30, 40, 50 Klux light intensity. Relative photosynthetic activity of weed species was high in the decreasing order in Cyperus serotinus, Echinochloa grusgalli var caudata, Bidens tripartita, Monochoria vaginalis, and Ludwigia prostrata, while respiration rate was high in Bidens tripartite, Monochoria vaginalis and Cyperus serotinus. Light saturation point of Monochoria vaginalis and Sagittaria pygrnaea may be considered as at 30 klux and photosynthetic rate of other weed species increased with increasing light intensity. Photosynthetic activity of weed species was generally two times higher than rice at the light intensity of 50 klux and increased more than rice as light intensity increased. Photosynthetic activity per leaf dry weight and specific leaf area was higher in broadleaf weeds than in grass and sedge weed species.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1551-1564
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• 2016

The high penetration level of inverter-based distributed generation (DG) power plants is challenging the low-voltage ride-through requirements, especially under unbalanced voltage sags. Recently, a flexible injection of both positive- (PS) and negative-sequence (NS) reactive currents has been suggested for the next generation of grid codes. This can enhance the ancillary services for voltage support at the point of common coupling (PCC). In light of this, considering distant grid faults that occur in a mainly inductive grid, this paper proposes a complete voltage support control scheme for the interface inverters of medium or high-rated DG power plants. The first contribution is the development of a reactive current reference generator combining PS and NS, with a feature to increase the PS voltage and simultaneously decrease the NS voltage, to mitigate voltage imbalance. The second contribution is the design of a voltage support control loop with two flexible PCC voltage set points, which can ensure continuous operation within the limits required in grid codes. In addition, a current saturation strategy is also considered for deep voltage sags to avoid overcurrent protection. Finally, simulation and experimental results are presented to validate the effectiveness of the proposed control scheme.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.1
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• pp.25-30
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• 2003

This research was conducted to compare the dry matter production and the yield productivity among nine soybean cultivars by measuring the photosynthetic ability of the middle and lower leaves at the flowering and the seed development stages. The leaf greenness(SPAD value) were ranged as 32-42 at the flowering stage. Also, They were ranged as 25-40 and 38-51 at the fifth leaf and the seventh leaf, respectively. The photosynthetic ability at the flowering and the seed development stage showed significant differences among soybean cultivars, and the photosynthetic ability at the seed development stage showed higher difference among cultivars than the flowering stage. The variation of the photosynthetic ability at the flowering and the seed development stage also was significant among cultivars. The light saturation point at the flowering stage was about 1500 $\mu$mol $m^{-2}$ $s^{-1}$ PAR, and the seed development stage was about 1000 $\mu$mol $m^{-2}$ $s^{-1}$ PAR. The photosynthesis showed the high negative correlation with the leaf area and the positive correlation with the leaf area ratio. Also, photosynthesis at seed development stage showed positive correlation with grain yields but there was not significant between photosynthesis and yields at flowering stage..

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.2
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• pp.100-104
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• 2004

This study was conducted to investigate the effect of the salinity on growth, inorganic ion content, and photosynthetic rate ($\textrm{P}^{N}$) in Korean ginseng (Panax ginseng C.A. Meyer) with complex fertilizer (CF) and NaCl concentrations. The salinity was applied to plant using NaCl and CF, and controlled an EC as 0.0, 1.0, 2.0 and 3.0 dS $\textrm{m}^{-1}$. The salinity treated three times at 35, 42 and 49 d after transplanting. The leaf area in different electrical conductivity (EC) decreased only the higher NaCl 1.0 dS $\textrm{m}^{-1}$. The root growth increased with CF and especially, it was two times higher at 3.0 dS $\textrm{m}^{-1}$ than that of control. But the root growth sharply decreased with NaCl compared to CF. The light saturation point of Korean ginseng was around 100 $\mu\textrm{mol}\;\textrm{m}^{-2}\textrm{s}^{-1}$ photosynthetically active radiation (PAR), and $\textrm{P}^{N}$ increased as CF increased but decreased with NaCl especially at the late growth stage. The $\textrm{Na}^{+}$ content in Korean ginseng increased sharply with NaCl.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.1
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• pp.46-50
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• 1984

Four rice cultivars (two japonicas and two japonica x indica hybrids) were grown in the hydroponic medium in order to investigate the photorespiration rate and ribulose-1, 5-bisphorphate carboxylase (EC 4, 1, 1;39) activity. The results were as follows: 1. Photorespiration rate was increased by the increasing light intensity as well as photosynthesis until light saturation point. Hangangchalbyeo of a hybrid variety had higher photorespiration rate than two japonicas(Jiniubyeo and Seolakbyeo) and one hybrid(Nampungbyeo) tested at ear formation stage. 2. Ribulose-1, 5-bisphosphate carborylase of hybrids were very sensitive to temperature showing lower activities at low temperature and much higher activities at high temperature than that of japonicas.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.103-107
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• 2000

Traditionally, EPT and thermal tests were used as diagnostic methods for pulp vitality test. The thermal and electrical stimulation tests are the methods to determine the vitality of a tooth based on its neuronal response. These have certain limitations, one of them is the difficulty of approaching the correct result in case of treatment of children. The reason is management problem caused by the unpleasant stimulation. Also, the response from patients are not objective, and false positive or false negative could be happened. Recently, laser doppler flowmetry and pulse oximeter which evaluate vascular integrity are introduced in an effort of overcoming to limitation of traditional methods. The principle of pulse oximeter is to and out level of oxygen saturation by ratio of the two pulses between emitted light and detected light penetrating them to the termination of body, such as ears or fingers. From this point of view, it can be applied to a tooth to determine its vitality. The objective of this study lies mainly on varifying pulse oximeter as a method of determining tooth vitality and providing basic data of its clinical implementation. The result of the research showed that level of oxygen saturation in vital teeth was average of 96.3% and 0.0% in pulpless teeth. As a comprehensive result, pulse oximeter could be an useful diagnostic equipment in determining of tooth vitality.