• Textile Coloration and Finishing
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• v.14 no.1
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• pp.51-57
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• 2002

In the prior study, the mechanical properties and the dyeability of the easily dyeable polyester grim(EDY) were investigated. In this study, to interpret the dyeing behavior of EDY with C. I. Disperse Violet 1, the thermodynamic parameters of dyeing, such as the standard affinity, the heat of dyeing(the enthalpy change), the entropy change, the diffusion coefficient, and the activation energy of diffusion, were obtained from adsorption isotherms and dyeing rate at various temperatures and compared to these of regular polyester (REG-PET). The heat of dyeing(the enthalpy change) and the entropy change for EDY showed smaller negative values than those for REG-PET. This means that the dye molecules in the EDY are combined more loosely than in the REG-PET and that is due to the flexibility of polymer chains of EDY. The diffusion coefficients of C. I. Disperse Violet 1 into the EDY were larger than those for REG-PET, and the activation energy of diffusion on EDY was smaller than that on REG-PET.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.4
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• pp.497-503
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• 2013

PURPOSE: The purpose of this study was to investigate the change of triceps surae activation during heel raise test in standing among knee flexion angles($0^{\circ}C$, $30^{\circ}C$, $45^{\circ}C$, $60^{\circ}C$). METHODS: Twenty healthy individuals performed unilateral plantarflexion in standing with $0^{\circ}C$, $30^{\circ}C$, $45^{\circ}C$, $60^{\circ}C$ knee flexion. Activity of medial gastrocnemius(MG), lateral gastrocnemius(LG), soleus(Sol) was recorded with surface electromyography(EMG). RESULT: The muscle activations induced the four different positions were compared and results showed that was significant difference MG and LG while the angle increase from $0^{\circ}C$ to $30^{\circ}C$, $45^{\circ}C$, $60^{\circ}C$ but Sol did not show significant differences in every angle. CONCLUSION: This study suggest that $30^{\circ}C$ knee flexion is required to induce a significant mechanical disadvantage of gastrocnemius.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.139-147
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• 2007

The aim of this study was to evaluate effects of short-tenn repetitive-bilateral excercise on the activation of motor network using functional magnetic resonance imaging (fMRI). The training program was performed at 1 hr/day, 5 days/week during 6 weeks. Fugl-Meyer Assessments (FMA) were performed every two weeks during the training. We compared cerebral and cerebellar cortical activations in two different tasks before and after the training program: (1) the only unaffected hand movement (Task 1); and (2) passive movements of affected hand by the active movement of unaffected hand (Task 2). fMRI was performed at 3T with wrist flexion-extension movement at 1 Hz during the motor tasks. All patients showed significant improvements of FMA scores in their paretic limbs after training. fMRI studies in Task 1 showed that cortical activations decreased in ipsilateral sensorimotor cortex but increased in contralateral sensorimotor cortex and ipsilateral cerebellum. Task 2 showed cortical reorganizations in bilateral sensorimotor cortex, premotor area, supplemetary motor area and cerebellum. Therefore, this study demonstrated that plastic changes of motor network occurred as a neural basis of the improvement subsequent to repetitive-bilateral excercise using the symmetrical upper-limb ann motion trainer.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.487-492
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• 2002

The growth kinetics of intermetallic compound layers formed between eutectic Sn-58Bi solder and (Cu, electroless Ni-P/Cu) substrate were investigated at temperature between 70 and 120 C for 1 to 60 days. The layer growth of intermetallic compound in the couple of the Sn-58Bi/Cu and Sn-58Bi/electroless Ni-P system satisfied the parabolic law at given temperature range. As a whole, because the values of time exponent (n) have approximately 0.5, the layer growth of the intermetallic compound was mainly controlled by volume diffusion over the temperature range studied. The apparent activation energies of Cu$_{6}$Sn$_{5}$ and Ni$_3$Sn$_4$ intermetallic compound in the couple of the Sn-58Bi/Cu and Sn-58Bi/electroless Ni-P were 127.9 and 81.6 kJ/mol, respectively.ely.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.13-18
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• 2003

Reduced activation ferritic steel, JLF-1 steel (Fe-9Cr-2W-V-Ta), is one of the promising candidate materials for fusion reactor applications. Fracture toughness ($J_IC$) and tensile tests were carried out at room temperature and elevated temperature ($400^{\circ}C$). Two types of CT specimen were prepared to examine the effect of rolling direction on the fracture toughness of JLF-1 steel. Four types of tensile specimen were also prepared to investigate the property by the rolling direction and welding. The Micro Vickers hardness was measured at various distances of a cross section of the TIG joints of JLF-1 steel according to the heating history of each position. Finally, the fracture surface was observed by scanning electron microscopy (SEM).

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.622-627
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• 2003

A numerical study is made of a flow in a cylinder with a rotating grooved endwall disk. The aim is to describe differences in the flow fields when there is concentrically-grooved obstacle characterized by amplitude(a) and wave number(N). The Reynolds number(Re) is varied from $10^{3}$ to $10^{4}$ and the aspect ratio(Ar) fixed to 1.0 for the most part of the simulation. For the various cases of amplitude(a) and wave number(N), numerical results are acquired. As the endwall groove roughness increases until certain limit, the interior azimuthal velocity component(v) increases drastically. But over the limit, the swirl motion chararcterized by velocity v decreases and finally it approaches much alike Ar=1.0-a case. The reason of activating swirl motion is based on increasing of torque transported by endwall disk. Torque coefficients($C_{T}$) are aquired for the various (a,N,Re) combinations and the limiting phenomena of swirl motion activation is explained.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1240-1245
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• 2003

Reduced activation ferritic steel (JLF-1) is considered as a promising candidate material for blanket or first-wall structure of D-T fusion reactors. The fracture tests of fracture resistance curve (J-R curve) and $J_{IC}$ are desirable to investigate the exact fracture toughness of JLF-1 steel, since it has a high ductility. The fracture toughness of JLF-1 steel is affected by the configuration of test specimen such side groove, specimen thickness or specimen size. In this study, the fracture toughness tests were performed with various size(plane size and thickness) and various side groove of specimens. The test results showed the standard specimen with the side groove of 40 % represented a valid fracture toughness. The fracture resistance curve increased with increasing plane size and decreased with increasing thickness. However, the fracture resistance curve of half size specimen was similar to that of the standard specimen.

• Corrosion Science and Technology
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• v.10 no.6
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• pp.212-217
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• 2011

In this study, corrosion characteristics of TiN and ZrN film on the abutment screw by arc-ion plating were investigated using a potentiodynamic anodic polarization test in deaerated 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The surface morphologies of the coating layers before and after corrosion test were investigated by a field-emission scanning electron microscope (FE-SEM) and a energy dispersive x-ray spectroscopy (EDS). The surfaces of the TiN and ZrN coated abutment screws showed the smooth surfaces without mechanical defects like scratches which can be formed during the manufacturing process, compared with those of the non-coated abutment screw. The corrosion and passive current densities of TiN and ZrN coated abutment screws were lower than those of the non-coated abutment screw.

• Journal of Industrial Technology
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• v.39 no.1
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• pp.7-14
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• 2019

Carbon nanotubes (CNT) on metal substrates are definitely beneficial because they can maintain robust mechanical stability and high conductivity between CNT and metal interfaces. Here, we report direct growth of CNT on Ni-based superalloy, Inconel 600, using thermal chemical vapor deposition (CVD) with acetylene feedstock in the growth temperature range of $400-725^{\circ}C$. Furthermore, we studied the effect of substrate pretreatment on the growth yield enhancement and growth temperature decrease of CNT on Inconel 600. Activation energy (AE) for CNT growth was estimated from the CNT height change with respect to the growth temperature. The AE values significantly decreased from 205.03 to 24.35 kJ/mol by the pretreatment of thermal oxidation of Inconel substrate at $725^{\circ}C$ under ambient. Higher oxidation temperature tends to have lower activation energy. The results have shown the importance of pretreatment temperature on CNT growth yield and growth temperature decrease.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.569-575
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• 2017

One of the important requirements for the application of reduced-activation ferritic/martensitic (RAFM) steel is to retain proper mechanical properties under irradiation and high-temperature conditions. To simulate the yield strength and stress-strain curve of steels during high-temperature and irradiation conditions, a multiscale simulation method consisting of both microstructure and strengthening simulations was established. The simulation results of microstructure parameters were added to a superposition strengthening model, which consisted of constitutive models of different strengthening methods. Based on the simulation results, the strength contribution for different strengthening methods at both room temperature and high-temperature conditions was analyzed. The simulation results of the yield strength in irradiation and high-temperature conditions were mainly consistent with the experimental results. The optimal application field of this multiscale model was 9Cr series (7-9 wt.%Cr) RAFM steels in a condition characterized by 0.1-5 dpa (or 0 dpa) and a temperature range of $25-500^{\circ}C$.