• Physical Therapy Korea
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• v.29 no.3
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• pp.180-186
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• 2022

Background: The craniocervical flexion test (CCFT) was developed for the activation and endurance of deep cervical flexors. However, the muscle thickness and muscle thickness changing ratio of the sternocleidomastoid (SCM) and deep cervical flexor (DCF) muscles in subjects with and without forward head posture (FHP) have not been reported. Objects: To determine the difference in thickness of the SCM and DCF muscles and the difference in the muscle thickness changing ratio between SCM, DCF, and DCF/SCM 20 mmHg and DCF/SCM 30 mmHg between subjects with and without FHP. Methods: Thirty subjects with and without FHP were enrolled. The muscle thickness of the SCM and DCF was measured when maintained at a baseline pressure of 20 mmHg and a maximum pressure of 30 mmHg using a pressure biofeedback unit during the CCFT. Ultrasonography was used to capture images of SCM and DCF muscle thickness during the CCFT, which was calculated using the picture archiving and communication system (PACS). Results: We observed a significant difference within the pressure main effect between SCM and DCF at a baseline pressure of 20 mmHg and a maximum pressure of 30 mmHg (p < 0.05). However, there was no significant difference in the muscle thickness and muscle thickness changing ratio for SCM and DCF during CCFT between subjects with and without FHP. Conclusion: There was no significant difference in the muscle thickness recruitment pattern during CCFT in posture changes between subjects with and without FHP.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.182-190
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• 1997

Recently to develope an automobile with better properties, much researches and investments are executed in many countries. In this paper, it is intended to minimize the weight of an engine block without changing the dynamic characteristics. The weight minimization is executed by the sensitivity of the natural frequency of the engine block. To decrease the engine weight, much less thickness than the original thickness of the engine is selected to initial value and the structure modification is performed to recover the dynamic characteristics of the engine. Here, the original thickness of the engine is 8mm and the initial thickness is selected to 5mm, 6mm and the number if the natural frequencies fitted are 2, 6, 7, respectively. As the results, it is found that; (1) the weight of each case could be reduced without changing the objective natural frequencies. Specially, in the case of fitting 2 natural frequencies with 5mm initial thickness the weight could be reduced to 4.21kg(23.3% for engine weight). (2) according to the driving frequency range of engine, the weight minimization could be performed choicely, (3) improving a vibration characteristics of a orignal structure, the weight minimization could be performed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.820-823
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• 2000

The characteristics of wire deflection, surface roughness and roundness were observed on changing discharge time for electrical discharge machining(EDM) of tungsten carbide in various conditions of thickness. The wire deflection was decreased as increasing discharge time and wire tension, the gap of deflection was decreased after thickness 60mm and discharge time of 6$\mu\textrm{s}$ due to the changing from fundamental mode to vibration mode. The deflection is the smallest at the water specific resistivity of 7.5 kΩ ㆍcm. The deflection is found to be decreased as increasing dwell time, and the result is due to the vibration of the pressure and the amount of the dielectric. The component of copper(Cu) and zinc(Zn), which is the main material of wire electrode, was observed for rough wire-cutting EDM of STD-11. This phenomena is found to be decreased as the number of EDM is increased. But it will be improved by changing the material and the shape of wire. The roundness of middle is found to be worse than that of upper and it is increased as the thickness of material is increased.

• Transactions on Electrical and Electronic Materials
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• v.14 no.3
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• pp.156-159
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• 2013

The electrical properties of ZnO nanowire field effect transistors (FETs) have been investigated depending on various diameters of nanowires. The ZnO nanowires were synthesized with an Au catalyst on c-plane $Al_2O_3$ substrates using hot-walled pulsed laser deposition (HW-PLD). The nanowire FETs are fabricated by conventional photo-lithography. The diameter of ZnO nanowires is simply controlled by changing the thickness of the Au catalyst metal, which is confirmed by FE-SEM. It has been clearly observed that the ZnO nanowires showed different diameters simply depending on the thickness of the Au catalyst. As the diameter of ZnO nanowires increased, the threshold voltage of ZnO nanowires shifted to the negative direction systematically. The results are attributed to the difference of conductive layer in the nanowires with different diameters of nanowires, which is simply controlled by changing the catalyst thickness. The results show the possibility for the simple method of the fabrication of nanowire logic circuits using enhanced and depleted mode.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.231-236
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• 1996

Recently to develope an automobile with better properties, much researches and investments are executed in many countries. In this paper, the weight of an engine block intend to minimize without changing the natural frequency. The weight minimization of an engine block is started from much less initial thickness than original thickness of the model and performed by using the sensitive analysis method and the optimum structural modification method. It can be considered that the weight minimization is completed through this process, because the optimum structural modification method includes the constraint of minimum changing quantity.

• Journal of the Korean Society of Combustion
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• v.16 no.3
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• pp.33-40
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• 2011

Combustion experiments were conducted at three different fuels ($CH_4$, $C_2H_4$ and $C_3H_8$) to investigate the effects of combustor pressure (30 ~ -30 kPa) on combustion charateristics and reaction zone structure. Regardless of the fuels, emission index of CO (EICO) increased with decreasing combustor pressure, and EICO of $C_2H_4$ was mostly affected by changing combustor pressure at subatmospheric pressure. In order to observe reaction zone, $OH^*$, $CH^*$ and ${C_2}^*$ chemiluminescence intensity were measured. The sequence of the chemiluminescence intensity peak position was affected by chemical characteristics of fuels rather than changing combustor pressure. The emission zone thickness of $C_2H_4$ and $C_3H_8$, defined by the full width at half maximum (FWHM) of $CH^*$ intensity profile, were increased with decreasing combustor pressure. however, the thickness of $C_2H_4$ exhibited the opposite tendency due to the characteristics of the fuel as the bond structure.

• Tribology and Lubricants
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• v.26 no.5
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• pp.297-302
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• 2010

This study is focused on the resin layer formation of UV imprinting process by changing imprinting pressure and period. The mold shape is made for the process of window open over the pattern transfer area and the imprinting period is assigned as the time just before the UV light curing. The residual layer is measured by changing the imprinting period and pressure magnitude, and the measured data of residual layer provides useful information for the design of the process conditions of imprinting processes.

• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.1
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• pp.13-25
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• 2014

In the current study, a drug-eluting stent coated with biodegradable polymers and sirolimus was developed by using an ultrasonic nanocoater and characterized in aspects of surface smoothness and coating thickness. In addition, in vitro release profiles of sirolimus by changing top coating layer with different biodegradable polymers were investigated. Smooth surfaces with variable thickness could be fabricated by optimizing polymer concentration, flow rate, nozzle-tip distance, gas pressure, various solvents and ultrasonic power. Smooth surface could be generated by using volatile solvents (acetone, chloroform, and methylene chloride) or post-treating with solvent vapor. Coating thickness could be controlled by varying injection volume or polymer concentration, and higher concentration could reduce the coating time while obtaining the same thickness. The thickness measurement was the most effectively performed by a conventional cutting method among three different methods that were investigated in this study. Release profiles of sirolimus were effectively controlled by changing polymers for top layer. PLGA made the release rate 3 times faster than PDLLA and PLLA and all top layers prevented burst release at the initial phase of profiles. Our results will provide useful and informative knowledge for developing drug-eluting stents, especially coated with biodegradable polymers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.139-142
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• 1994

Ceramic filter using energy trapping pheonomenon is used bandpass filter at high frequency. In this paper, we analyzed theoretically ceramic filter characteristics of TS vibrational mode and also investigated experimentally it. The ceramic plate is PZT-4 poled in the thickness direction of Valpey Fisher Co. and electroded with two pairs. We analyzed the characteristics in appling to the all constant of ceramic and electrode material each other and vibrational mode. We also measured resonant frequency and bandpass width of the ceramic filter changing the thickness of ceramic plate and electrode spacing. Comparing of falter characteristics, theoretical value nearly corresponded with experimental value. So we saw that we can expect filter characteristics changing the thickness of ceramic plate and electrode spacing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05a
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• pp.13-16
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• 2003

Magnetic and magneto-optical properties of Fe/Pt/Fe, Co/Pd/Co trilayers and also the sandwiches with wedge-shaped magnetic (Fe, Co) and nonmagnetic (Pt, Pd) layers were investigated. The oscillatory behavior of the saturation field $H_{s}$ of the studied trilayers with changing the thickness of the nonmagnetic layer (NML) $t_{NML}$ was revealed. That was explained by the exchange coupling between ferromagnetic layers (FML) through the nonmagnetic spacer. For the first time, oscillations of the transverse Kerr effect (TKE) with changing the Pt- and Pd-wedge thickness were discovered. Period of these oscillations was found to depend on the FML thickness and the photon energy of the incident light. TKE spectra of the examined samples were discovered to modify very strongly with increasing $t_{NML}$. The discovered peculiarities of magneto-optical properties of thin-film systems were explained by a concept of the spin-polarized quantum well states in the pt and Pd layers.