• Polymer(Korea)
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• v.39 no.3
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• pp.388-393
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• 2015

Low molecular weight species were extracted from PC and SAN by a solvent extraction method in order to investigate the effect of low molecular weight species on interfacial tension and affinity between PC and SAN. From the analysis of molecular weight distribution by the GPC, it was confirmed that the low molecular weight species were effectively eliminated by the solvent extraction. Interfacial tension measurements and morphological observation were carried out with the PC and SAN of which the low molecular weight species were extracted. Interfacial tension was increased and the infinity was decreased for the extracted PC and SAN pair. This result implied that the low molecular weight species play a role as a compatibilizer between two polymers. Among two polymers, low molecular weight SAN contributes more in the compatibilization. Thus, it is favorable to use SAN containing a larger amount of low molecular weight species in fabrication of PC/ABS blend.

• Korean Journal of Ichthyology
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• v.5 no.1
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• pp.85-95
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• 1993

Sexual dimorphism of the matured chum salmon, Onchorhynchus keta, have been studied based on biometrical measurements and osteological characters. Male chum salmon has an elongated and hooked upper jaw and canine-like teeth on the upper and lower jaw. The ratios of snout length (SnL) and upper jaw length (UJ) to head length of male were larger than those of the female, whereas eye diameter (ED) and postorbital part of head (CK) of the male were smaller than those of the female's. The ratios of body depth, caudal peduncle depth, anal fin length and adipose fin length to the standard length (PBL) of the male were also larger than those of the female. On sexual dimolrphism was detected in number of fin rays, gill rakers and pyloric ceaca, where as number of lateral line scales and caudal vertebrae of the female was larger than those of the male. Glossohyal and vomer bones has no sexual difference. The ratio of width to length of supraethmoid bone of the male was larger than that of the female. The ratio of frontal part to posterior part of parasphenoid bone of the male was smaller than that of the female.

• Macromolecular Research
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• v.12 no.2
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• pp.172-177
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• 2004

We have studied the lamella-level morphology of poly(ethylene terephthalate) (PET)/polycarbonate (PC) blends using small-angle X-ray scattering (SAXS). Measurements were made as a function of the holding time in the melt. We determined the morphological parameters at the lamellar level by correlation function analysis of the SAXS data. An increased amorphous layer thickness was identified in the blend, indicating that some PC was incorporated into the interlamellar regions of PET during crystallization. The blend also exhibits a larger lamella crystalline thickness (l$\sub$c/) than that of pure PET. A possible reason for the increase in l$\sub$c/ is that the inclusion of the PC molecules in the interlamellar regions causes an increase in the surface free energy of folding. At the early stage of isothermal crystallization, we observed a rapid drop in the value of l$\sub$c/ in the blend; this finding indicates that a relatively large fraction of secondary crystals form during the primary crystallization. In contrast, the value of l$\sub$c/ for the sample that underwent a prolonged holding time increased with time in the secondary crystallization-dominant regime; this observation suggests that the disruption of chain periodicity, which results from transesterification between the two polymers, favors the development of fringed micellar crystals that have larger values of l$\sub$c/ rather than the development of normal chain-folded crystals.

• Journal of Aquaculture
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• v.13 no.3
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• pp.245-251
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• 2000

Carapace width (CW) of main size class of the snow crab was 70~90 mm for females and 80~100 mm for males. The CW holds a stronger relation with body weight than that of carapace length (CL). The number of eggs attached to the pleopods was in the range of 35,000 and 114,000 eggs in crabs with 65 and 88 mm CW, respectively). The logistic maturity curve on morphometric measurements and gonad examination, defined by the presence of egg brooding in wide abdomen of the female and spermatophores inside the vasa deferentia of the male indicated that 50 % of crabs attained gonadal maturity at 54.2 mm and 58.8 mm CW for females and males, respectively. In the relationship between CW and body weight, a sharp break at 53~55 mm CW indicates that morphological changes associated with maturity have occurred.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1425_1426
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• 2009

In this study, commercially available polyethylene terephthalate(PET), which is widely used as a substrate of flexible electronic devices, was modified by dielectric barrier discharge(DBD) method in an air condition at atmospheric pressure, and aluminium - doped zinc oxide (ZnO:Al) transparent conducting film was deposited on PET substrate by r. f. magnetron sputtering method. Surface analysis and characterization of the plasma-treated PET substrate was carried out using contact angle measurements, X-ray Photoelectron Spectroscopy(XPS) and Atomic Force Microscopy (AFM). Especially the effect of surface state of PET substrate on some important properties of ZnO:Al transparent conducting film such as electrical and morphological properties and deposition rate of the film, was studied experimentally. The results showed that the contact angle of water on PET film was reduced significantly from $62^{\circ}$ to $43^{\circ}$ by DBD surface treatment at 20 min. of treatment time. The plasma treatment also improved the deposition rate and electrical properties. The deposition rate was increased almost linearly with surface treatment time. The lowest electrical resistivity as low as $4.97{\times}10^{-3}[\Omega-cm]$ and the highest deposition rate of 234[${\AA}m$/min] were obtained in ZnO:Al film with surface treatment time of 5min. and 20min., respectively.

• Korean Journal of Pharmacognosy
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• v.31 no.1
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• pp.7-15
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• 2000

Glycyrrhizae Radix aqua-acupuncture solution (GRAS) and Glycyrrhizae Radix water-extracted solution (GRWS) were prepared and tested for organ toxicities, antitumor activities, and immunomodulatory effects. The organ-toxicity of GRAS to male ICR mice was studied by the measurements of glutamic oxaloacetic transaminase (GOT), glutamic pyruvate transaminase (GPT), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP-s) activities after injection of GRAS for 7 days. The activities of GOT, GPT, LDH, ALP-s were decreased with GRAS. It was shown to possess considerable toxicity toward various tumor cell lines. Concentration of GRAS at 1.5g/ml and 3g/ml resulted in more than 80% inhibition of growth in Ehrlich ascites tumor cells (EATC), Hepa1c1c7, and HeLa cells. Toxicity of GRAS to A549 revealed that 68% inhibition of growth. GRWS at the concentration of 3g/ml showed more than 80% inhibition of growth with EATC, Hepalclc7, A549 and HeLa. In morphological study, the number of cells were decreased, and the shape of cells was round-form in EATC, Hepalclc7, A549 and HeLa cells with GRAS. Administration of GRAS inhibited the growth of EATC in vivo. Mice given EATC at 1.5g/ml or 0.3g/ml GRAS had 16.7% to 50% survival after 21 days. GRAS increased the proliferation of T and B cells and the cytolytic activity of purified T cell. The biosyntheses of nucleic acid and protein of EATC, Hepalclc7, A549 and HeLa cells were inhibited by GRAS.

• Ocean and Polar Research
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• v.23 no.4
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• pp.389-394
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• 2001

During austral summer 1998 we examined the impacts of artificial UV-B and solar radiation on chlorophyll a content and fresh weight of four species of Antarctic red algae namely, Georgiella confluens, Iridaea cordata, Pantoneura plocamioides and Porphyra endiviifolium. These subject species were taken in consideration of clear demarcations of their vertical distribution and classified as shallow water group (Iridaea and Porphyra) and deep water group (Georgiella and Pantoneura). When irradiated with artificial UV-B at the irradiance of $2.0Wm^{-2}$ the shallow water inhabitants were much more resistant than the algae from deep water the fresh weight of which was reduced by 40-50% relative to control apart from loss of pigmentation. Direct solar radiation was lethal to the deep water group with a sign of complete bleaching whereas the shallow water group did not show any change in the physiological parameters. We were unable to discriminate difference in the algal sensitivity between UV-filtered and UV-transparent treatments since samples tested were either all unaffected or dead. Spectrophotometric measurements of methanolic extracts revealed a strong absorption peak in the UV range in the shallow water group of algae, Iridaea and Porphyra, but not in the deep water counterparts. Species difference in sensitivity to artificial UV-B and solar radiation is discussed in relation to biochemical and morphological characteristics and the role of the radiation in the algal vertical distribution is suggested from ecological perspective.

• The korean journal of orthodontics
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• v.16 no.1
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• pp.7-34
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• 1986

본 연구목적은 여자성인교정을 위한 치료목표를 수립하기 위한 기준을 설정하는데 있다. 이용된 연구자료는 96명의 한국인 TV탈랜트와 영화배우 또는 패션모델중 교합과 안모를 평가하여 선정된 30명의 측모두부X선규격사진이었으며 선정된 표본의 평균연령은 20.16세였다. 연구방법은 측모경조직분석을 위해 Downs분석, Northwestern분석, Steiner분석, Wylie분석, Tweed분석, Dimensional linear분석법이 이용되었고 측모연조직분석을 위해 Holdaway연조직분석법이 적용되었다. 조사된 계측치들은 Apple II 48K system을 이용하여 각항목에 대한 평균치와 표준편차를 산출하였으며 백인, 한국인, 일본인의 기존계측치와 비교하였다. 그 연구결과는 다음과 같다. I. 경조직분석 (1) 본 연구와 백인과의 비교 본 연구에서는 백인에 비해 하악이 후퇴되었고 상${\cdot}$하악절치는 순측경사를 보였다. 또한 하악하연경사가 심했다. (2) 본 연구와 한국인정상성인여자(이 연구)의 계측치 비교 이의 연구계측치에 비해서 상악이 후퇴되어있고 상${\cdot}$하악절치는 설측경사를 보였다. 따라서 본 연구의 안모형태는 이의 한국인정상성인여자에 비해서 직선형안모를 보였다. (3) 본 연구와 일본정상인의 계측치 비교 일본정상인에 비해 하악이 돌출되었고 상${\cdot}$하절치는 설측경사를 보였다. 또한 안모의 상부고경과 하악크기는 일본정상인에 비해 크게 나타났다. II. 연조직분석 연조직분석의 11항목중 H-선에 대한 연조직 subnasal과 하순의 계측치가 Holdaway의 acceptable range를 벗어났다. 그 이유는 본연구에서 하악이 상대적으로 후퇴양상을 보였기 때문이라고 사료된다. 이외항목의 계측치들이 acceptable range내에 있다는 것은 연조직이 경조직의 이동에 따라 움직이고 있음을 의미한다. III. Downs분석, Northwestern분석, Steiner분석, Wylie분석, Tweed분석, Dimensional linear measurements분석을 위한 평균치, 표준편차, Polygon도표를 작성함으로써 한국성인여자교정의 진단과 치료목표를 정하는데 지침이 된다고 사료된다.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1613-1618
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• 2014

Perovskite-type oxides are promising oxygen carriers in producing oxygen-enriched $CO_2$ gas stream for oxyfuel combustion. In this study, a new series of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ (x = 0.2, 0.4, 0.6, 0.8) was prepared and used to produce $O_2/CO_2$ mixture gas. The phase, crystal structure, and morphological properties of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ were investigated through X-ray diffraction, specific surface area measurements, and environmental scanning electron microscopy. The oxygen desorption performance of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ was studied in a fixed-bed reactor system. Results showed that the different x values of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ have no obvious effects on crystalline structure. However, the oxygen desorption performance of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ is improved by Co doping. Moreover, $SrCo_{0.8}Fe_{0.2}O_{3-{\delta}}$ synthesized via a new EDTA method has a larger BET surface area ($40.396m^2/g$), smaller particle size (48.3 nm), and better oxygen production performance compared with that synthesized through a liquid citrate method.

• The korean journal of orthodontics
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• v.47 no.4
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• pp.238-247
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• 2017

Objective: The aim of this study was to compare recycled and unused orthodontic miniscrews to determine the feasibility of reuse. The comparisons included both miniscrews with machined surfaces (MS), and those with etched surfaces (ES). Methods: Retrieved MS and ES were further divided into three subgroups according to the assigned recycling procedure: group A, air-water spray; group B, mechanical cleaning; and group C, mechanical and chemical cleaning. Unused screws were used as controls. Scanning electron microscopy, energy-dispersive X-ray spectrometry, insertion time and maximum insertion torque measurements in artificial bone, and biological responses in the form of periotest values (PTV), bone-implant contact ratio (BIC), and bone volume ratio (BV) were assessed. Results: Morphological changes after recycling mainly occurred at the screw tip, and the cortical bone penetration success rate of recycled screws was lower than that of unused screws. Retrieved ES needed more thorough cleaning than retrieved MS to produce a surface composition similar to that of unused screws. There were no significant differences in PTV or BIC between recycled and unused screws, while the BV of the former was significantly lower than that of the latter (p < 0.05). Conclusions: These results indicate that reuse of recycled orthodontic miniscrews may not be feasible from the biomechanical aspect.