• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.18-26
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• 1997

$\beta-SiC $powder with or without the addition of 1 wt% of $\alpha-SiC$ particles (seeds) was pressureless-sintered at $1950^{\circ}C$ for 0.5, 2 and 4 h using $Y_3Al_5O_{12}$ (yttrium aluminum garnet, YAG) as a sintering aid. The introduction of $\alpha-SiC$ seeds into $\beta-SiC$ accelerated :he grain growth of elongated large grains during sintering, resulting in the coarser microstructure. The fracture toughnesses of materials with $\alpha$-SiC seeds and without $\alpha-SiC$ seeds sintered for 4 h were 7.5 and 6.1 $MPa\cdot \textrm m^{1/2}$, respectively. Higher fracture toughness of the material with seeds was due to the enhanced bridging by elongated grains, resulting from coarser microstructure.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.214-222
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• 2001

A precise echosounding system to investigate the topographical characteristics of the coastal fishing ground was composed of a public-DGPS receiver, a single beam echosounder and a survey software. To confirm the usefulness of the system, a set-net fishing ground and the distribution of artificial reefs were surveyed. The results obtained are as follows : 1. The 2-D positioning error of the public-DGPS receiver with a DGPS mode and a GPS mode was 5.47 m, 7.03 m, respectively. 2. The experimented set-net fishing ground was located on the level ground at the depth of 9-10 m, a small size valley 1-2 m deep and approximately 10 m wide was found at a distance of 120 m from the set-net to the south. 3. In the artificial reefs' water area near the Jaran Bay, it was confirmed that twenty rectangular artificial reefs were established by the piece at the depth of 15-25 m and a natural reef 5-8 m high on the sea bed was located near the group of artificial reefs. 4. It was confirmed that the precise echosounding system was a useful tool in the pre-study to choice an appropriate water area to provide the artificial reef.

• Journal of Korean Society of Forest Science
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• v.80 no.4
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• pp.351-359
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• 1991

Annual ring characteristics of pinus thunbergii grown in several air-polluted areas were investigated by soft X-ray densitometry. Ring width, maximum density and relative difference between maximum and minimum density(abbreviated to DD) were generally decreased after the beginning of operation of the factories at the vicinity of the pollution sources. Especially at the nearest areas of the industrial complex, those were distinctly decreased, and the changes, either increases or decreases, in percentage of latewood and minimum density could not be explained by the air pollution dosages. Ring width, maximum density and DD were being more apparently decreased after 5 years than those for 5 years after the beginning of operation, and also the rate of decrease was increased from after 5 years after the beginning of operation, and the rate of decrease of ring width was the highest of all. It was inferred that ring width, maximum density and DD of Pinus thunbergii could be used as indicators to detect the growth damage by air pollution.

• Journal of Life Science
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• v.12 no.5
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• pp.515-522
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• 2002

Effect of the microbial product, which consisted of Bacillus coagulans DL-1 and rice bran, on the microorganisms in soil and growth of cabbage and tomato was investigated. Bacillus congulans DL-1 was isolated form the soil and identified in this study. Total number of microorganisms in the soil treated with the microbial product was higher than the untreated soil. The growth of cabbage and tomato on the soil treated with microbial product was faster than that on the untreated soil. The treatment of microbial product in the soil resulted in the increase of useful microorganisms, which seemed to enhance the growth of cabbage and tomato. It seemed that microbial product can increase the number of certain microorganisms and change the ratio of different species of microorganisms.

• Korean Journal of Plant Resources
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• v.19 no.2
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• pp.355-359
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• 2006

This study was carried out to investigate the factors affecting seed germination of Korean native orchids, such as Habenaria radiata, Bletilla striate and Cypripedium macranthum. In general, seeds of H. radiata was effectively germinated on solid medium and the highest germination (29.6%) was achieved on Hyponex solid medium. But shoot growth was better in MS liquid medium containing $100mL\;L^{-1}$ coconut water (MSC medium). Seed germination of B. striata was effectively induced on MS solid medium. However, no seed germination was observed in all liguid medium tested. Seed germination experiments of C. macranthum were performed using 6 kinds of media and seeds harvested 90 days after cross- and self-pollination. Cross-pollinated seeds were germinated on all the media with the best germination ratio of 4.45% on MSC medium. But no germination was observed from self-pollinated seeds.

• Korean Journal Plant Pathology
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• v.3 no.2
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• pp.100-107
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• 1987

Pre-pentration activity of Pyricularia oryzae Cav. from the stage of conidia germination to appressorium formation was examined on rice leaf epidermis under light and scanning electron microscopes to determine the causes· for differences in blast susceptibility between plants grown under three different soil moisture conditions in the greenhouse. No significant differences were found in the external shape of leaf epidermal cells including bulliform cells between plants grown under different soil moisture conditions. Growth and orientation of germ tube and morphology and size of appressorium of P. oryzae did not vary with soil moisture treatment. Site of appressorium formation was consistent over soil moisture treatment with the highest frequency of bulliform cell $(35\~48\%)$, followed by short cell $(19\~27\%)$, and long and guard cells $(13\~20\%)$. No appressorium was formed on trichome. This result suggests that the observed differences in blast susceptibility between plants grown under different soil moisture conditions were not due to the differences in the pre-pentration activity of P. oryzae on those plants.

• Korean Journal of Weed Science
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• v.16 no.4
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• pp.346-353
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• 1996

To study the effects of metal ions on the activities of antioxidative enzymes, the activities of superoxide dismutase(SOD), peroxidase(POD), catalase(CAT) of Persicaria vulgaris has been studied after treating with Cd, Cu, Zn and Al. 1. The activities of SOD in leaf and stem were decreased, but that in root was increased. Among the metal ions studied in this report, Al gave the highest increase in SOD activity in root. 2. The activities of POD after treating with Cd or Cu did not show any significant differences. POD activities after treating with Zn and Al has been decreased, however, that in root showed increased activities after treating with Zn 5,000 ppm or Al 500 ppm. 3. The activity of CAT in leaf was decreased with every metals studied. The CAT activity in root was increased with increased concentration. The root treated with Al showed highest activity. 4. The presence of isozymes after treated metal ions has been studied in gel electrophoresis. The POD treated plant did not show any new isozymes, but the intensity of one of pre-existent band was increased. The SOD treated plant showed the several new isozymes.

• Journal of Life Science
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• v.18 no.6
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• pp.897-901
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• 2008

Deep seawater (DSW; deep ocean water) is pure, rich in inorganic materials which have attracted attention for various applications. In this study we investigated the effects of the DSW upwelled from the East Sea, offshore Yang Yang (Korea) on the morphological differentiation of cultured rat hippocampal neurons, which were grown in the minimal essential medium containing 10% (v/v) fetal bovine serum and 25% (v/v) DSW with various hardness. DSW had no effect on initial morphological differentiation (17 hr post-plating). When observed on DIV3, 7, 14, and 17, low hardness (0 and 200) DSW reduced dendritic branching. However, dendritic branches within $80\;{\mu}m$ diameter from the center of soma nearly doubled in neurons grown in hardness 1,000 DSW-containing media. DSW with hardness 600 was more or less same as control groups. These results indicate that DSW with appropriate hardness ameliorates neuronal health.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.5
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• pp.558-562
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• 1996

The growth and yield of Job's tears (Coix lacryma-jobi L.) under the flooded paddy and upland (dry paddy) field conditions were compared at three sowing dates and two planting densities. Job's tears grown under flooded paddy field was much shorter in plant height, but greater in number of tillers than those grown under upland. Photosynthesis rate of Job's tears grown under flooded paddy field was higher and the weight of dry roots heavier but the damages of pest and leaf blight disease smaller than those grown under upland. For the above mentioned reasons, the grain yield of Job's tears grown under flooded paddy field was higher by up to 85% than that grown under upland. There was no significant difference in grain yield between the planting densities. The earlier sowing brought about the less grain yield in upland field condition, while sowing plot on the 15th of May showed the highest grain yield in the flooded paddy field condition.

• Korean Journal of Weed Science
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• v.18 no.1
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• pp.42-47
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• 1998

The experiment was conducted to study the growth, developmental pattern, and seed production of Commelina benghalensis L. grown from four seed types; large and small aerial seeds, and large and small underground seeds. Plants from the four seed types differed in growth rate. Based on dry weight and leaf area, plants from large underground seeds emerged and grew faster in the first 2-4 weeks after seeding(WAS) but plants from small aerial seeds grew faster during the 4-6 WAS; thereafter, there was no significant difference in growth rate among plants from the four seed types. Based on seed production, plants from large aerial seed produced more seeds(1473) than those from small seeds(1006). Small aerial types represented 75-77% of the total seed production, large aerial seed 21-23%; only 2-4% were underground seeds. The results suggest that the plants from large underground seeds might have better competitive ability Than those of small aerial seeds during the early growth stage due to faster germination and higher dry matter production.