• Korean Journal of Food Science and Technology
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• v.10 no.1
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• pp.57-62
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• 1978

The morphology and chemical properties of bracken (Pteridium aquilinum) root starch were investigated. The starch granules were mainly sphere and cocoon with the diameter of $5-12\mu$. Polarized micrograph indicated that the starch granule had a hilum at the center of granule, showing a crossed-birefringence. X-ray diffraction pattern demonstrated that the granules showed B-type. The density of the starch was 1.49 and the amylose content was 22%. The ferricyanide number and alkali number were 0.292 and 11.03, respectively. Proximate analysis showed that the starch contained 0.52% lipid, 0.63% ash and 150ppm phosphorus of which over 80% were found in the amylopectin fraction. The iodine affinity and molecular weight of amylose were 16.1 and 83,000 respectively. The degree of branching and glucose units per segment of amylopectin were 3.7% and 27, respectively.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.05a
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• pp.8-8
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• 2010

자원식물을 소재로 이용하는 생물산업은 21세기 경제성장을 주도할 핵심기간산업이며, 미래형 고부가가치산업이다. 현재 지구상에는 약 55만종의 식물이 존재하는 것으로 알려져 있으나, 인간의 손길이 닿지 않은 천연 강우림 등의 미개척지가 상당수 존재하고 있어 더욱 많은 종들이 존재할 것으로 추정된다. 자원식물들 중에는 작물로의 개발이 가능하거나, 개발할 필요성이 높은 식물들이 많이 있다. 자원식물들은 예로부터 식용, 약용, 관상용, 유지용, 기호용, 밀원용, 섬유용, 향신료용, 향료용, 당료용, 호료용, 염색용, 수지용, 탄닌용 등으로 구분되어 이용되어 왔다. 자원식물은 종에 따라 꽃, 줄기, 잎, 뿌리 및 종자 등 부위별로 다양하게 산업적 소재로 활용되어 왔다. 최근에는 건강에 관한 관심이 급증하면서 다양한 건강 기능성 상품이 개발되고 있으며, 관련 시장이 급속하게 성장하고 있다. 특히 자원식물 등 천연물을 소재로 한 건강 기능성 상품은 안전성이 보장되며 우수한 생리활성이 있는 것으로 밝혀지면서, 자원식물을 소재로 한 건강 기능성 상품의 개발에 대한 수요가 증가하고 있는 실정이다. 따라서 다양한 자원식물을 대상으로 이들의 활용가치를 분석하여 상품화할 수 있는 방법의 개발이 절실히 필요하다. 또한 주 5일제 실시 및 여가활용에 관한 관심이 급증하면서 농촌 경관산업에 대한 수요가 증가하고 있다. 농촌 경관산업은 국민의 여가선용 및 복지향상에 효과적일 뿐 아니라 지역주민과 관광객이 함께 즐길 수 있는 관광산업으로써 지역 이미지 강화를 통한 지역 홍보, 지역 내 일자리 창출 및 경관산업에 사용된 생물소재를 이용한 바이오산업의 활성화 등의 장점을 지니고 있다. 또한 농촌 경관산업은 자연과 농촌을 활용한 자연 친화형 관광단지를 조성하여 친환경, 고부가가치형 종합산업을 추구하는 추세이다. 그러므로 경관산업 및 이를 활용한 바이오산업의 소재로써 자원식물의 역할은 매우 클 것으로 생각된다. 특히 각 지역에 자생하는 고유의 자원식물을 활용하면 지역 특화 경관산업 및 바이오산업의 발전에 크게 이바지 할 수 있으며, 이로 인하여 지역 경제 활성화 및 친환경 건강 기능성 상품에 대한 수요를 충족시킬 수 있을 것으로 기대된다. 따라서 친환경 건강 기능성 소재 개발과 농촌 경관산업을 활용한 생물산업에 적용할 수 있는 산업적 가치가 우수한 자원식물의 다양한 기능을 분석하고, 각 자원식물별로 특성에 맞는 개발 방안을 구축하여 다양한 산업화의 소재로 활용하여야 할 것으로 생각된다.

• Journal of Technologic Dentistry
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• v.34 no.3
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• pp.227-235
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• 2012

Purpose: This study compared the surface hardness (Vickers) and microstructural characteristics between a type IV stone with and without die hardening treatment, a polyurethane die material. Methods: Materials used were a type IV stone(MG Crystal Rock), two die hardeners (Hardening bath, Epox-it), and a polyurethane resin material(Polyluck). Six specimens per group were prepared according to manufacturer's directions. The prepared specimens were tested by means of hardness test, one-way ANOVA analysis, scanning electron microscopic(SEM) observations and energy dispersive spectroscopic(EDS) analysis. Results: In the hardness test and its statistical analysis, there was no significant difference in the surface hardness between a type IV stone and type IV stone with die hardener coating, type IV stone mixed with an epoxy like material instead of water. In contrast, polyurethane resin material exhibited significantly greater surface hardness than other specimen groups (p<0.05). Conclusion: By considering the results of the hardness test, SEM observations and EDS analysis, although the die hardeners on type IV stone did not show remarkable improvement in surface hardness, the die hardener coating on the surface of type IV stone material did show decrease of microporous and improvement of surface defects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.8
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• pp.847-853
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• 2011

In this study, a hybrid powder-extrusion process involving the control of temperature dwelling time for improving the formability of Zn-22Al powder was developed and the effect of dwelling time on the mechanical properties of a spur gear with a pitch circle having a diameter of 1.8 mm was investigated. General extrusion experiments were carried out at different temperatures such as 290, 300, and $310^{\circ}C$. Spur gears with good qualities and without any surface defects were obtained in the case of extrusion temperature of $310^{\circ}C$ and ball-milling duration of 32 h. The Vickers hardness distribution was non-uniform, and after the sintering process, an internal crack was generated because of the different deformation energy between gear central part and teeth. To overcome the abovementioned problems, research on controlling the dwelling time of the extrusion temperature in the powder-extrusion process was carried out. Good-quality spur gears were obtained when the dwelling time was 15 min.

• The Journal of the Acoustical Society of Korea
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• v.29 no.4
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• pp.223-228
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• 2010

High-frequency bottom loss measurements for grazing angle of $82^{\circ}$ in frequency range 17-40 kHz were made in Jinhae bay in the southern part of Korea. Observations of bottom loss showed the strong variation as a function of frequency, which were compared to the predicted values using two-layered sediment reflection model. The geoacoustic parameters including sound speed, density and attenuation coefficient for the second sediment layer were predicted from the empirical relations with the mean grain size obtained from sediment core analysis. The geoacoustic parameters for the surficial sediment layer were inverted using Monte Carlo inversion algorithm. A sensitivity study for the geoacoustic parameters showed that the thickness of surficial sediment layer was most sensitive to the variation of the bottom loss.

• The Korean Journal of Malacology
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• v.1 no.1
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• pp.24-50
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• 1985

Five different populations of Parafossarulus manchouricus (Chongpyung, Chinju and Kunsan, Korea; and Japan and Taiwan), a population of Bitbynia (Gabbia) misella (Gongju, Korea) and two different populations of Bithynta tentaculata (Michigan, U.S.A. and Bodensee, Germany) were compared in regard to eff-laying characteristics, morphology, chromosome cytology, natural infections of parasites and ecology of habitats. A satisfactory culture method was devised for laboratory rearing of the snails. Tropical fish food (Terra SML) and powdered green leaves (Ceralife) were used as the main food sources for the snails. Benthic diatoms such as Navicula and Gomphonema from the periphyton were also essential for satisfactory growth, especially for the baby snails. The aquaria were stabilized with small stones from a local stream. Young P. manchouricus snails grew to adult size in about 54 days after hatching. They laid eggs 150-156 days after hatching. The whole cycle (birth to egg-laying) took approximately 5 months. The three species of bithyniid snails are iteroparous and lay eggs once a year. There were no major morphological differences in the shells of genera or subgenera studied here. They did exhibit the following rather minor differences. The shell of Parafossarulus has spirally raised ridges, and its apex is usually eroded; the other two genera lack these characteristics. The shell of B. (Gabbia) misella is small, nor exceeding 7.5 mm in length, while the shells of the other two species are larger, being more than 10 mm in length. Scanning electron microscopy (SEM) of the protoconch of P. manchouricus reveals nearly smooth sculpture with small, low, spiral wrinkles. This sculpture is quite different from that of the Hydrobiidae, a family to which the bithyniids are frequently assigned. Scanning electron microscopy of the radulae of the three bithyniid species showed that their radular morphologies are very similar, but there are some small differences, which may be species-specific. There were some statistical differences in shell heights between the Korean and the other populations of P. manchouricus, and between this species and the other two bithyniids as well. The shell differences between the several populations of Korean P. manchouricus may be related to environment. Edtails of the chromosome cycle of these bithyniid snails are similar to those reported for other snails. No specific differences were observed in the chromosome cycle between the various species and populations of snails employed in this study. Reporred for the first time in molluscs are two darkly stained "nucleolar organizers" during pachyterne stages of meiosis. Two different chromosome numbers were observed in the three bithyniid species: n=17 in B. tentaculata and P. manchouricus, and n=18 in B. (G.) misella. no sex chromosomes or supernumerary chromosomes were seen. There were no morphological differences in karyotypes of three Korean strains of P. manchouricus. The infection rates of cercariae of Clonorchis sinensis in Chinju and Kunsan strains of P. manchouricus were 0.14% and 1.25%, respectively. However, Clonorchis cercariae were found in Chongpyung strain of P. manchouriceu and Gongju strain of B. (G.) misella. The habitats of P. manchouricus around Jinyang Lake were relatively clean without any heavy pollution of aquatic microorganisms and organic materials during the period of this study. The levels of dissolved oxygen (D.O.) and biochemical oxygen demand (B.O.D.) of the water specimens sampled from the study areas ranged from 6.0 to 9.6 ppm and from 0.4 to 1.6 ppm, respectively. Eight metalic constituents from the water samples were also assayed, and all metalic ions detercted were remarkably low below the legal criteria. However, calcium ion in the water samples from the habitats of P. manchouricus was considerably higher than others.