• Journal of the Korean association of regional geographers
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• v.13 no.2
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• pp.119-128
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• 2007

Grain-size trend analysis is the methodology to obtain the net sediment transport pattern from the spatial trends of grain size parameters. It has the potentials to be an effective tool to address the morphological changes of the deltaic barrier islands in the Nakdoog River once we make sure net transport patterns inferred from grain size trend analysis represent the morphological evolution patterns. This research aims to investigate the applicability of the net transport patterns obtained by 'transport vector', proposed by Gao and Collins(1992), to understanding the morphological changes of the Nakdong River deltaic barrier islands. The results indicate that the net transport directions are overall in concordance with the morphological evolution patterns; however, the level of concordance is low in the island with fast growing rate. The reasons may be match or mismatch of temporal scales involved between processes represented by net transport patterns and morphological change analyzed or the rate of morphological change. Consequently, the application of grain size trend analysis in analyzing the morphological changes of deltaic barrier islands requires the careful consideration of temporal scales involved.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.4
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• pp.384-388
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• 2014

Air temperature has increased, while sunshine hour has decreased during the grain filling period of most rice cultivars (August to September) during the past 12 years from 2001 through 2012 in Korea. Climatic Productivity Index (CPI) has fallen because of the decreased sunshine hour and increased air temperature during the grain filling period, and the degree of reduction was greater with earlier heading. For stable rice production, we will need to delay the heading of rice as a cultivation measure against the future climatic trend. Grain yield showed no significant trend for past 12 years. However, the year to year change in grain yield showed a similliar pattern with that of CPI. Especially, a linear function relating rice yield to CPI explained approximately 63% of variation in grain yield with the heading date of August $11^{th}$ period.

• Journal of The Geomorphological Association of Korea
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• v.27 no.3
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• pp.53-73
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• 2020

Morphology and grain size distribution of coastal dunes should be well documented because they are critical to dune's buffering capacity and resilience against storm surges. The nationwide coastal dune survey produced the dataset, including beach-dune topographic profiles and grain size parameters for frontal beaches, foredunes, and inland dunes. This research investigated the dataset to describe geomorphic and textural properties of coastal dunes: foredune slopes, dune heights above approximately highest high water, mean size, and sorting, together with associated variables of coastal setting that influence coastal dunes. It also explores the possibility of a dune type scheme based on gran size trends. The results are as follows. First, the coast in which dunes are developed is the primary control on foredune morphology and sediment texture. Coastal dunes on the east coast were developed more alongshore rather than inland, with gentler slopes on the higher ground and out of coarser sand. The shore aspect contributes to this pattern because the east coast cannot benefit from prevailing northwesterly. Second, grain size trends from beaches through foredunes to inland dunes were little identified. Third, 12 dune types were identified from 69 dunes, showing the indicative capability for the status of beaches and dunes. We confirmed that the dataset could increase our understanding of the overall characteristics of coastal dune morphology and texture, though there is something to be improved, for example, establishing the refined and comprehensive field survey protocol.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.3
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• pp.266-272
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• 2015

High temperature impairs rice grain yield and quality. To understand the effect of high temperature on leaf physiological activity and grain filling, two cultivars of rice that Dongan and Ilpum were exposed to high temperature during ripening stage. Grain filling rate, perfect grain ratio and grain weight of high temperature ($27^{\circ}C{\pm}4^{\circ}C$) treated both rice cultivars were decreased than those of control temperature ($22^{\circ}C{\pm}4^{\circ}C$) treated. The reduction rates of grain filling ratio, perfect grain ratio and grain weight of high temperature treated to control treated rice were higher in Ilpum than Dongan. Chlorophyll contents of rice leaves under high temperature at early ripening stage were higher than those of control temperature, but those were slowly decreased with no difference between temperature treatment since at mid ripening stage. Although chlorophyll a/b ratio under high temperature was decreased from heading to 15 days after heading, that was gradually increased since 15 days after heading. Protein concentrations of rice leaves for ripening stage was a similar pattern with chlorophyll changes. The rate of photosynthesis at 14 days after heading under high temperature was higher than those of control temperature, but there was no difference at those of 7 and 34 days after heading between two temperature treatment. Free sugars under high temperature treated leaves were lower than control temperature. Consequently, these results exhibit that high temperature accelerate leaf physiological activity as chlorophyll synthesis and photosynthesis rate unlike the deterioration of grain filling.

• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.914-920
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• 2001

The grain orientation distribution and grain boundary characterization of $ZrB_2$-ZrC composites sintered by a SPS(Spark Plasma Sintering) method, a new sintering technique were analyzed by the EBSP technique and then their crystallographic results have been compared with those of a sintered specimen using a PLS(Pressureless Sintering) method. In the $ZrB_2$-ZrC composite manufactured by SPS, (0001) planes of $ZrB_2$ were oriented in the direction normal to the specimen surface. In the case of PLS, those of $ZrB_2$ were oriented normal to the electron beam. In both cases of PLS and SPS, ZrC grains had the randomly oriented grain structure. The grain boundary characterization showed that low angle grain boundaries in the PLS and SPS processed materials constituted about 10% and 8% of the total number of boundaries, respectively, represented the only slight difference between the proportion of low angle grain boundary. However, in the distribution of CSL(Coincident Site Lattice) boundaries, it was shown the higher proportion of CSL boundaries with $\Sigma$ 3,5,7,9, 11 in the SPS processed material.

• Korean Journal of Plant Taxonomy
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• v.37 no.2
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• pp.87-108
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• 2007

The pollen morphology of 31 taxa, representing all woody species from 12 genera of Fabaceae in Korea, was examined by light microscope and scanning electron microscope. The pollen grains were monad and prolate spheroidal or rarely subprolate in equatorial view. The pollen grain aperture was trizonocolporate or rarely trizonooperculate, which does not occur in the other families of Fabales in Korea. The exine showed a great variety of sculpture pattern, i.e. psilate, microperforate, densely microperforate, perforate, polygonal perforate, macroperforate, macroperforate with granules in holes, polygonal macroperforate, verrucate with pitted perforate striae, verrucate-perforate, granulate, rugulate, reticulate or refined reticulate. The pollen morphological data supported the idea that the genera Echinosophora and Sophora were congeneric. Caragana (Galegeae) was quite close to the Sophora group (Maackia, Sophora and Echinosophora) of the Sophoreae in each measured pollen parameter and exine sculpture pattern. Eleven genera of Fabaceae were recognized based on differences in aperture type, pollen grain shape and exine pattern, and a generic pollen key of the woody Fabaceae in Korea was developed. A key to pollen types of Lespedeza was also suggested. The examined taxa of Coronilla and Wisteria were recognized by their exine patterns.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.182-182
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• 2009

The effect of Re-oxidation on the PTCR properties of Sm-doped barium titanate ceramics was investigated by means of impedance spectroscopy. Electrical properties such as resistance vs. temperature, I-V curve were measured and microstructure was observed with SEM photography. Sample was fabricated with thick film process such as tape casting of green sheet, screen printing of electrode pattern, stacking, firing in reduced atmosphere and re-oxidation, etc. As the temperature of re-oxidation increases, resistance jump as a function of temperature enhances but resistance at room temperature increases. These behavior of resistance as a function of temperature, dependent on the re-oxidation condition, is analyzed with Cole-Cole impedance plot and is shown to be related with the degree of oxidation of grain boundary regardless of grain core during re-oxidation process of sample.

• Journal of the Korean Ceramic Society
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• v.22 no.1
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• pp.40-46
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• 1985

The effect of calcining temperature ranged from $700^{\circ}C$ to 110$0^{\circ}C$ on sintering characteristics of morphotropic $Pb(Zr_{0.53}Ti_{0.47})O_3 doped with $Nb_2O_5$ has been investigated. The ratio of sintered grain size to calcined grain size decreased as the calcining temperature increased. The hardness as well as the sintered density of the samples reached a maximum at about 90$0^{\circ}C$. The X-ray diffraction pattern of the sintered sample showed both tetragonal and rhombohedral phases. The tetragonal phases intensity increased with the calcining temperature going through a maximum at about 90$0^{\circ}C$ while the rhombohedral phase intensity remained uneffected. The both intensity were about the same at 90$0^{\circ}C$ The dielectric constant of the sintered samples reached a maximum um while the dielectric dissipation factor showed a minimum at the calcining temperature of about 100$0^{\circ}C$.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.213-217
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• 2004

Laboratory scale study for an area of influence and flowing aspect of groundwater saturated zone was conducted for three sediment grains. On the AMG(Average Modal diameter Grains) 0.34, 1.38, 3.89mm diameter samples, the affected area of the aquifer were 15.2, 37.0, 30.0%/m2 each. Air flow for AMG 0.34mm diameter grain size provides indication of pattern of channelized air flow in saturated zone and expansion state in above saturated zone. For AMG of 1.38, 3.89mm diameter grains, air flow are pervasive air flow, forming a symmetrical cone of influence around the injection point. And also AMG 1.38, 3.89mm diameter samples show onset of collapse and approach to steady state in above saturated zone, respectively. In this study, optimal sites for in situ air sparging, may be grain diameters between about AMC 1.5～2.5mm diameter.

• Journal of Powder Materials
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• v.17 no.2
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• pp.154-159
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• 2010

In this study, the sintering behavior of (Nd, Dy)-Fe-B powder which fabricated by strip-casting was investigated with various sintering temperatures and holding times. The relative density over 99% could be obtained by both sintering at $1070^{\circ}C$ for 1h and sintering at $970^{\circ}C$ for 20h. The grain growth was observed in sintered specimen at $1050^{\circ}C$ compared to one at $970^{\circ}C$. The isothermal sintering process below $1000^{\circ}C$ led to suppress grain growth showing the improved magnetic properties. The phase transformation of Nd-rich was confirmed by X-ray diffraction pattern.