• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.1
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• pp.117-125
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• 2016

Nitrite and dimethylamine (DMA) are the immediate precursors of carcinogenic N-nitrosodimethylamine (NDMA). This study investigated the effects of nitrite and nitrate contents in Chinese cabbage on changes in NDMA, nitrite, nitrate, and DMA contents during storage of kimchi. Contents of nitrite in Chinese cabbage 1 (HNC), Chinese cabbage 2 (MNC), and Chinese cabbage 3 (LNC) were $47.54{\pm}1.07$, $10.12{\pm}0.31$, and $6.10{\pm}0.09mg/kg$, respectively. Kimchi were assigned to one of the following three groups: kimchi used HNC (HNK), kimchi used MNC (MNK), and kimchi used LNC (LNK). HNK had higher levels of nitrite and nitrate than those in MNK and LNK after storage for 10 days and 20 days. DMA and NDMA contents decreased in all kimchi during the storage period. HNK had higher NDMA content than LNK until 20 days of storage. These results suggest that the contents of nitrite and nitrate in Chinese cabbage have significant effects on the formation of NDMA in kimchi.

• Archives of design research
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• v.13 no.1
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• pp.59-66
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• 2000

The more the function of Car Navigation System (CNS) is getting more various and high-grade, the more functions are necessary for a user to use simply and dearly from a user. But now the using CNS's a using circumstances is not satisfied with these requirements. In this paper, author analyzed the using circumstances composed of CNS to improve these problems and the function of a competitive company's products, extracted the necessary functions. Then author analyzed objected model and dynamic model by the objective modeling centering around Hyundai Electronic Company's HNK-1 COLD model mounted Hyundai Motor Company Equus vehide. In the Hyundai Electronic Company's HNK-1COLD model mounted Hyundai Motor Company Equus vehide, author analyzed the mental model of user used observation method the user behavior by taking video, and then studied all the functions and restructured the information structure, finally present the interface guide line of a user of CNS.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.7
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• pp.627-634
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• 2014

Machine tool vibration is well known for reducing machining accuracy. Because vibration response of a linear structure generally depends on its transfer function if the magnitude of excitation were kept constant, this study introduces a RET(Random Excitation Test) based on FRF method to evaluate stiffness of a prototype HDMTL(Heavy-Duty Multi-Tasking Lathe) for large crankshaft of marine engine. Firstly, two force loops of the lathe and corresponding structural loops were identified:1) workpiece - spindle - head stock - main bed, 2) workpiece - tool post - carriage bed. Secondly, compliances of each structural loop were measured respectively using RET with a hydraulic exciter and then converted into stiffness. Finally, the measured stiffness was compared with that obtained previously by FEM analysis. As the result, both measured and computed stiffness were closely in agreement with each other. And the prototype HDMTL has evidently sufficient rigidity above ordinary heavy-duty lathes.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.2
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• pp.129-138
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• 2012

In this study, three types of large scale multi-tasking machine tools together with core technologies involved have been developed and introduced; a multi-tasking machine tool for large scale marine engine crankshafts, a multi-tasking vertical lathe for windmill parts, and a large scale 5-axis machine tool of gantry type. Several special purpose devices has been necessarily developed for the purpose of handling and machining big and heavy workpieces accurately, such as PTD (Pin Turning Device) with revolving ring spindle for machining eccentric crankshaft pins, hydrostatic rotary table and steady rest for supporting and resting heavy workpieces, and 2-axis automatic swiveling head for high-quality free surface machining. Core technologies have been also developed and adopted on their detail design stage; 1) structural design optimization with FEM structural analysis, 2) theoretical hydrostatic analysis for the PTD and rotary table bearings, 3) box-in-box type cross-rail and octagonal ram design to secure machine rigidity and accuracy, 4) constant spindle rpm control against gravitational torque due to unbalanced workpiece.

• Molecules and Cells
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• v.38 no.3
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• pp.221-228
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• 2015

Because Schwann cells perform the triple tasks of myelination, axon guidance and neurotrophin synthesis, they are candidates for cell transplantation that might cure some types of nervous-system degenerative diseases or injuries. However, Schwann cells are difficult to obtain. As another option, ectomesenchymal stem cells (EMSCs) can be easily harvested from the nasal respiratory mucosa. Whether fibrin, an important transplantation vehicle, can improve the differentiation of EMSCs into Schwann-like cells (SLCs) deserves further research. EMSCs were isolated from rat nasal respiratory mucosa and were purified using anti-CD133 magnetic cell sorting. The purified cells strongly expressed HNK-1, nestin, $p75^{NTR}$, S-100, and vimentin. Using nuclear staining, the MTT assay and Western blotting analysis of the expression of cell-cycle markers, the proliferation rate of EMSCs on a fibrin matrix was found to be significantly higher than that of cells grown on a plastic surface but insignificantly lower than that of cells grown on fibronectin. Additionally, the EMSCs grown on the fibrin matrix expressed myelination-related molecules, including myelin basic protein (MBP), 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and galactocerebrosides (GalCer), more strongly than did those grown on fibronectin or a plastic surface. Furthermore, the EMSCs grown on the fibrin matrix synthesized more neurotrophins compared with those grown on fibronectin or a plastic surface. The expression level of integrin in EMSCs grown on fibrin was similar to that of cells grown on fibronectin but was higher than that of cells grown on a plastic surface. These results demonstrated that fibrin not only promoted EMSC proliferation but also the differentiation of EMSCs into the SLCs. Our findings suggested that fibrin has great promise as a cell transplantation vehicle for the treatment of some types of nervous system diseases or injuries.