• Journal of the Korean Vacuum Society
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• v.15 no.2
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• pp.145-151
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• 2006

The molecular assembly of p-iodo-phenyl octadecyl ether (I-POE), p-iodo-phenyl docosyl ether (I-PDE) and a binary mixture of these two molecules on graphite has been studied using a scanning tunneling microscope. Each molecular system self-assembles on the graphite surface to form a stable monolayer with a head-to-tail configuration. For the binary system, the I-POE and I-PDE molecules do not mix on the surface, preferring instead to form isolated monolayer domains. Here, the I-POE molecules are preferentially adsorbed on the graphite surface, due to the effects of alkyl chain length and the functional group on the monolayer structure.

• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.7-15
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• 2009

Purpose: This study was to propose the clear understanding for stress distribution of supporting bone by use of staggered buccal offset tripodal placement of fixtures of posterior 3 crown implant partial dentures. We realized posterior 3 crown implant fixed partial dentures through finite element modeling and analysed stress effect of implant arrangement location to supporting bone under external load using finite element method. Method: To understand stress distribution of 3 crown implant fixed partial dentures which have 2 different arrangement by finite element analysis. In each model, for loading condition, we applied $45^{\circ}$ oblique load to occlusal surface of crown and applied 100 N for 3 crown individually(total 300 N) for imitating possible oral loading condition. at this time, we calculated Von Mises stress distribution in supporting bone through finite element method. Result: When apply $45^{\circ}$ oblique load to in-line arrangement model, maximum stress result for 100 N for each 3 crown 47.566MPa. In tripodal placement, result for 1mm buccal offset tripodal placement implant model was maximum distributed load 51.418MPa, so result was higher than in-line arrangement model. Conclusion: In stress distribution result by placement of implant fixture, the most effective structure was in-line arrangement. The tripodal placement does not effective for stress distribution, gap cause more damage to supporting bone.

• BMB Reports
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• v.32 no.4
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• pp.345-349
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• 1999

We fused the promoter region of an H3.2 chicken histone gene, whose expression is dependent on the cell cycle, to the 5' coding region of an H3.3 chicken histone gene, which is expressed constitutively at a low level throughout the cell cycle. This fusion gene showed a cell cycle-regulated pattern of expression, but in a different manner. The mRNA level of the fusion gene increase during the S phase of the cell cycle by about 3.7-fold at 6 h and 2.7-fold at 12 h after the serum stimulation. The mRNA level of the intact H3.2 gene, however, increased by an average of 3.6-fold at 6 h and 8.7-fold at 12 h. This different expression pattern might be due to the differences in their 3' end region that is responsible for mRNA stability. The 3' end of the H3.2 mRNA contains a stem-loop structure, instead of a poly(A) tail present in the H3.3 mRNA. We also constructed a similar fusion gene using a H3.3 histone gene whose introns had been eliminated to rule out the possibility of involvement of the introns in cell cycle-regulated expression. The expression of this fusion gene was almost identical to the fusion gene made previously. These results indicate that the promoter region of the H3.2 gene is only partially responsible for its expression during the S phase of the cell cycle.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.89-92
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• 2020

Polytetrafluoroethylene (PTFE) fibers are widely used in the textile industry, filter media, membrane distillation, electronic appliances, and construction. In this study, PTFE-polyethylene oxide (PEO) fibrous membranes were fabricated by emulsion electrospinning; subsequently, pure PTFE nanofibers were obtained via sintering. PTFE-PEO electrospinning solutions were prepared using different weight ratios to determine the optimized condition. As the ratio of the PEO increased, the fiber structure improved. Scanning electron microscopy and Fourier-transform infrared spectroscopy observations indicate that PEO is removed and PTFE fused gradually to form bonds among them during sintering. The obtained pristine PTFE membrane demonstrated hydrophobicity at 143.6° water contact angle and oleophilicity at 0° oil contact angle, which is known to be utilized for oil/water separation. A simple separation experiment was performed to remove oil droplets from water. The PTFE membrane exhibited good chemical stability and a high surface-area-to-volume nanofiber ratio. These excellent properties suggest that it is applicable to oil/water separation in harsh chemical environments.

• Textile Coloration and Finishing
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• v.23 no.3
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• pp.201-209
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• 2011

With a new method of applying chitosan and alginate onto cellulose, multi-coated cotton fabrics with chitosan and alginate were prepared and characterized. To coat cotton with chitosan, raw cotton was dipped in chitosan solution, mangled of 1kgf/$cm^2$, neutralized in 2 wt% NaOH soluton, washed, and dried at $60^{\circ}C$ oven. The chitosan-coated fiber was dipped in sodium alginate solution, 1kgf/$cm^2$ mangled, neutralized in 2 wt% $CaCl_2$ solution, washed, and dried at $60^{\circ}C$ oven, resulting in CCAC(coated cotton with chitosan and calcium alginate skin) fiber characteristics. Excellent absorbancy of distilled water and saline solution was observed by the absorption test on cotton fabric treated with CCAC(0.5 wt% calcium alginate) and 0.5 wt% calcium alginate respectively. The SEM photograph confirmed the uniform coating on the cotton fabric surface.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.1-6
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• 2009

The temperature of exhaust gas was raised by increasing of engine movement on developing engine. Thermal of high temperature and pressure reverse in bellows, because of increasing of engine movement and the thermal performance of converter in combustion. As a result, thermal loss is increased and thermal efficiency is decreased rapidly in bellows, it can occur to damage in mechanical structure. In this study, it was necessary to analyze back pressure performance and thermal characteristic on driving condition in exhaust system. It was adapted braid type bellows and straight type exhaust pipe. It was compared with curve type exhaust pipe for lay-out on considering to design of exhaust system. It was necessary to improve thermal characteristic and back pressure performance so that expansion cavity pipe(ECP) was installed between bellows and catalyst convert. Not only decreasing back pressure was solved but also thermal characteristic problems in exhaust pipe because of increasing capacity. According to this study, the basis of data is presented when new exhaust system is designed.

• Journal of the Korean Vacuum Society
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• v.16 no.3
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• pp.215-220
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• 2007

Thin films of $SBT(SrBi_2Ta_2O_9)$ having $Pt/SBT/Seed/Pt/Ti/SiO_2/Si$ structure were fabricated using self-seed layer method by R.F. Magnetron sputter. Self-seed layers were deposited at room temperature and $600^{\circ}C$, which had 30 nm thickness. To investigate crystallization of self-seed layer we characterized by XRD after various heat treatment. And we characterized the crystallinity and electrical properties of SBT on self-seed layer after various heat treatment.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.743-751
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• 1997

A thorough literatural review of researches on the experimental prediction of scour depths caused by jets was carried out to find out a measure of scour prediction. A new experimental equation for predicting scour depths due to a vortical or an inclined jet was developed from five hundreds of experimental data which were carefully reviewed and adopted from the previous researches. The developed equation shows 0.941 statistical correlation coefficient. It was found that the parameters governing the scour depth were the size of bed material, flow rate through unit width of spillway, and head drop across structure. The predicted scour depth could be expressed as the deepest scouring depth below tail water surface with correlation coefficient ${\gamma}$ = 0.941.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.7
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• pp.547-555
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• 2002

This paper proposes a stabilizing controller for the multirate sampled-data systems, which have a periodic output measurement scheme, in case of the open-loop unstable plant. A sufficient condition for maintaining observability in the multirate sampled-data systems is derived and a design strategy for filtered disturbance rejection is proposed. We also propose a design method for the plant output estimator. It is shown that the proposed pre-stabilizing controllers can stabilize the plant through the simulations. The proposed controller has IMC structure, and can be decomposed into the pre-stabilizing controller, the plant output estimator, the filtered disturbance estimator and the inverse of the fast pre-stabilized plant model. We assume that the plant is open-loop unstable and the disturbance consists of a sum of finite number of sinusoids with different frequencies. Some examples are presented for illustrations.

• Journal of the Korean Society of Safety
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• v.21 no.3 s.75
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• pp.67-72
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• 2006

This study is to investigate the related materials such as domestic law regulation, research paper, research report, and the other material, and to suggest suitable counter measures, to find out hazard degree for its works of workers and work place through direct survey, in order to determine risk score of each hazardous work which is designated by the Government, without consideration of labour's consciousness against risk level at a site. Therefore, a new questionnaire survey related to the decision of risk level are made and distributed to find out what risk level each worker recognizes. Also, the authors tried to approach reasonable conclusions after discussing reasonability of qualification standard and improving ideas of worker at hazardous work places with worker, faculty member, H&S manager, labour union. And the results show hazard degrees by each work kind of the above: 3.75 for working with machinery, 3.7 for steel structure, 3.5 for operation of tower crane, 3.51 for retaining wall, 3.85 for form work, 3.46 for scaffolding are obtained. This quantified risk can be applied to establishing a reasonable system to keep safe against hazardous works.