• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1692-1693
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• 2007

본 연구는 송수광센서를 이용하여 광막을 형성시키고 미소물체가 광막을 통과할 때 발생되는 미소변위전압을 검출하여 신호처리를 수행함으로서 미소물체의 계수장치에 이용하고 자 하는 센싱시스템의 개발에 관한 내용이다.

• Journal of Korea Foundry Society
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• v.37 no.6
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• pp.207-216
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• 2017

This study investigated the effects of the addition of Zn, Ca, and SiC on the microstructure and mechanical properties of Mg-Al alloys. The tensile properties of homogenized Mg-xAl (x = 6, 7, 8, and 9 wt.%) alloys increased with increasing Zn content by the solid-solution strengthening effect. However, when the added Zn content exceeded the solubility limit, the strength and ductility of the alloys decreased greatly owing to premature fracture caused by undissolved coarse particles or local melting. Among the Mg-xAl-yZn alloys tested in this study, the AZ74 alloy showed the best tensile properties. However, from the viewpoints of the thermal stability, castability, and tensile properties, the AZ92 alloy was deemed to be the most suitable cast alloy. Moreover, the addition of a small amount (0.17 wt.%) of SiC reduced the average grain size of the AZ91 alloy significantly, from $430{\mu}m$ to $73{\mu}m$. As a result, both the strength and the elongation of the AZ91 alloy increased considerably by the grain-boundary hardening effect and the suppression of twinning behavior, respectively. On the other hand, the addition of Ca (0.5-1.5 wt.%) and a combined addition of Ca (0.5-1.5 wt.%) and SiC (0.17 wt.%) increased the average grain size of the AZ91 alloy, which resulted in a decrease in its tensile properties. The SiC-added AZ92 alloy exhibited excellent tensile properties (YS 125 MPa, UTS 282 MPa, and EL 12.3%), which were much higher than those of commercial AZ91 alloy (YS 93 MPa, UTS 192 MPa, and EL 7.0%). The fluidity of the SiC-added AZ92 alloy was slightly lower than that of the AZ91 alloy because of the expansion of the solid-liquid coexistence region in the former. However, the SiC-added AZ92 alloy showed better hot-tearing resistance than the AZ91 alloy owing to its refined grain structure.

• Korean Journal of Environment and Ecology
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• v.22 no.3
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• pp.301-308
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• 2008

We conducted the survey about the avian fauna, population, community and correlation between avian population and densities of the fallen rice grain in Cheonsu reclaimed area(Ganwol and Bunam Lake and reclaimed land) from Oct. 2006 to Mar. 2007. Total surveyed species number was 142 species, sum of maximum count of each species was 362,797 individuals, sum of average count of each species was 84,818 individuals. Comparing with early and late wintering season, number of species was stable in each survey time, but total population was decreased as the season progressed. Dominant species were Bean Geese Anser fabalis, Baikal Teals Anas formosa, White-fronted Geese Anser albifrons, Mallards Anas platyrhynchos and Pintails Anas acuta. Population fluctuation of the Bean Geese Anser fabalis, Baikal Teals Anas formosa, Mallards Anas platyrhynchos, PintailsAnas acuta was decreasing, but population of the White-fronted Geese Anser albifrons was stable. Number of species, total population were not significantly different among Ganwol, Bunam and Cheonsu Bay. Survey period was significantly correlated with species diversity and population in each area, and most community indices of each area were shown significant correlation. The density of the fallen rice grain was significantly different between the harvested rice paddy by big harvesting machine and small harvesting machine. Density of the fallen rice grain in stubble collected area was significantly different with area of stubble not collected. Density of the fallen rice grain was drastically decreased in the middle of wintering season, but not significantly different between Dec. 2006 and Feb. 2007. Avian population was strongly correlated with number of fallen rice grain in the same period.

• The Korean Journal of Mycology
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• v.41 no.3
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• pp.142-148
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• 2013

Sorghum (Sorghum bicolor Moench) was traditionally grown on a small scale, however, at present its cultivation is getting momentum in terms of food and animal feed crop throughtout the Korea. Grain mold symptoms of the plant were frequently observed during disease surveys in Korea from 2007 to 2009. The symptoms were highly variable. Severely infected grain was fully covered with mold and partially infected grain may look normal or discolored. Ninety isolates of Fusarium species were obtained from the diseased plants collected from several locations in the country. Among the collected Fusarium isolates, 41 were identified as Fusarium thapsinum, 23 as F. proliferatum, 12 as F. graminearum, 5 as F. incarnatum, and 3 as F. equiseti based on their morphological and cultural characteristics. Elongation factor 1 alpha gene sequences of the isolates were used for phylogenetic analysis. Analyses of the sequences revealed that the isolates were confirmed to be identical with related species of NCBI GenBank. Pathogenicity tests showed that three dominant species, F. thapsinum, F. proliferatum and F. graminearum were strongly virulent to grains of sorghum. This study is the first report of sorghum grain mold caused by Fusarium species in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.4
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• pp.361-371
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• 1992

For the increase of grain yield potential in rice, a low-tillering large panicled type has been suggested as an ideotype. A low-tillering plant type may have different yield potential and needs different cultural practices from that used in a high-tillering type for the maximum yield. This study was conducted to evaluate the grain yield performances of a low-tillering large panicled rice and high-tillering small panicled rice at different plant spacings, nitrogen(N) levels and seedling numbers per hill. A low-tillering large panicled genotype, IR25588 was compared with a high-tillering small panicled IR58. The grain yield of IR25588 was significantly higher than that of IR58 under a narrow spacing with high N level. The maximum yields of IR58 and IR25588 were reached at about 35,000 and 40,000 spikelets per m$^2$, respectively. The increased grain yield in IR25588 was mainly due to the increase in spikelet number per unit area which is the most precise indicator of grain yield in rice. The optimum spacing for the maximum yield was denser for IR25588 than that for IR58 under high N level. The intra-hill competition of the low-tillering type was lower than that of the high-tillering type. The higher dry matter production and bigger leaf area and culm weight were the main factors for increased grain yield in a low-tillering panicle weight type. Based on the results, the yield potential of a low-tillering panicle weight type was higher than that of a high-tillering panicle number type, especially under a close spacing with high N level.

• Korean Journal of Agricultural Science
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• v.35 no.1
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• pp.101-118
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• 2008

This paper reviews the present situation of Triticale cultivation and examines the potentiality of contribution to livestock as well as poultry sector in Bangladesh Agriculture. Triticale is a human-made cross between rye and durum wheat that has the ability to produce quality green fodder, and then re-grow after first and second cutting to produce grain. In Bangladesh, it is a non-traditional cereal that grows well during the cool and dry Rabi season (November-March) when fodder and feed scarcity is a major limiting factor for ruminant livestock. In Bangladesh Triticale was started to grow in the late Ninety's. The scientists of Bangladesh Agricultural Research Institute (BARI) were first introduced triticale in Bangladesh. Still now the situation of Triticale is grown as fooder and feed in Bangladesh within the scientists under trial. High quality grass fodder was obtained by cutting green triticale plants twice, at 35 and 50 days after seeding, while later the ratooning tillers produced grain to a yield of 1.1-2.4 t/ha of grain for poultry feed or human food. Triticale straw was twice as nutritious as rice or wheat straw and its grain contained more protein than other cereals. Researchers and farmers have also successfully made triticale hay and silage from a mixture of triticale green cuttings, rice straw and molasses. A feeding trial at Bangladesh Livestock Research Institute(BLRI), Savar station showed a large(46%) increase in cow live weight gain and a 36% increase in milk yield (but no change in milk quality or dry matter intake) in cows fed triticale silage compared with those fed rice straw over a period of nine weeks. In another feeding trial, it was found that triticale grain was a good replacement for wheat in the feed blend for chickens in Bangladesh. So it will be a good chance to alive our livestock as well as poultry sector if triticale enters to our existing cropping system as fodder cum grain. The challenge in Bangladesh is to identify fodder technologies that match existing small-scale farmer cropping patterns without needing major inputs or increasing risks. Preliminary field experiments revealed that triticale is a crop with good potential to produce quality fodder and grain for small scale farmers in Bangladesh.

• Journal of Welding and Joining
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• v.11 no.4
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• pp.79-90
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• 1993

Shielded metal arc welding, one-ploe and two-pole submerged arc welding were accomplished to investigate microstructure changes on phase transformation behavior in $60kg/mm^2$ quenched and tempered high strength steel. Microstructures were examined by optical micrograph and TEM. In shielded metal arc welding (oxygen 250ppm), the inclusions were small size (0.3-0.5$\mu\textrm{m}$)and small in number. In submerged arc welding (oxygen 430-529ppm), the inclusions were larger(0.7-2$\mu\textrm{m}$) than that of shielded metal arc welding and large in number. Microstructure mainly depends on number and distribution of inclusions in fusion zone of weld metal. It was noticed that a limited number of inclusions favors the formation of acicular ferrite.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.142-142
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• 2003

The effects of film thickness on the dipolar relaxation of ferroelectric PbTiO$_3$ films were investigated in the microwave-frequency range. The dielectric constants ($\varepsilon$) and the dielectric losses (tan $\delta$) were successfully measured up to 30 ㎓ using interdigital capacitors. The PbTiO$_3$ thin films were deposited on the quartz substrate at room temperature and postannealed in oxygen atmosphere. As the film thickness increased, its grain size and tetragonality were enhanced. And the dipolar relaxation behavior began to appear in the thin films with approximately 20 nm thickness, since ferroelectric domains could not be formed hi small grains. The observed relaxation frequency (above 10 ㎓) was higher than the previous values reported in bulk ceramics. It can be correlated with the extremely small domain size of the thinfilms as shown by TEM. And, the Rayleigh constant [1] from domain wall motions was alsoinvestigated by LCR meter at 100 KHz.

• Journal of the Korea Furniture Society
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• v.20 no.6
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• pp.575-580
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• 2009

This study was carried out to manufacture wooden vessels by small diameter wood and wasted wood of Castanea crenata Sieb. et Zucc, which has been largely planted in southern area. We made spice set, tea box set, cookie vessel set, bowl set and accessory set. With the development of edged tools, the human species has been able to fashion wood to change and enhance its environment - one only has to look at the history of all cultures to see examples of wooden artifacts and structures. Even with the development of synthetic materials and the progress of automated, mechanized production of wood and wood products, the raw material is still processed by traditional methods to meet a never-ending demand for products made from this most desirable natural material. Chestnut wood has high added value and natural color grain and is very useful for wooden vessel. Thinned low grade trees can be used to produce wooden vessel. Therefore this result can promote thinning and produce good forestation.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.109-111
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• 2006

In this study, microstructure and mechanical properties for the friction stir welded 2519Al-T87 alloy of the thickness of 38.8mm were studied using DSC, OM, SEM and micro hardness tester. DSC analysis show that GP Zone, ${\theta}'$ and $\theta$ phases in upper part and ${\theta}'$ and $\theta$ phase in lower part of the FSW zone. Recrystallized large grains are observed in HAZ, and elongated small and large grain in the TMAZ. In SZ, very small grains forms by high plastic deformation and heat from friction by tool and specimen.