• International journal of advanced smart convergence
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• v.11 no.4
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• pp.129-140
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• 2022

The purpose of this study to improve the shoulder wheel that is used frequently during shoulder circumduction exercise in a park, to link the shoulder wheel to a game application comprising various shoulder circumduction exercise and shoulder ROM exercise, and to enjoy the game during the exercises. A step motor was added to the shoulder wheel, and the rotating speed and rotating angle, and rotating direction can be controlled. The shoulder height, different for different people, can be controlled as well, so that any user can use this device. The developed application content includes the game elements, to enjoy the repetitive and boring exercise with fun and interest, and the control to adjust the degree of difficulty. This was to help users heighten their desire to rehabilitate by inducing active participation during repetitive shoulder rehabilitation exercise because the game vests users with intrinsic motivation and immersion. If the shoulder wheel and application contents proposed in this study are used, shoulder diseases can be prevented in advance by performing muscle strengthening exercises required in an aging society. This study is expected to contribute to the field of research related to serious games and rehabilitation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.245-249
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• 2002

Tungsten carbide microshaft is used as various micro-tools in MEMS because it has high hardness and good rigidity. In this study, experiments were performed to produce tungsten carbide microshaft using electrochemical machining. $H_2SO_4$solution was used as electrolyte because it can dissolve tungsten and cobalt simultaneously. Optimal electrolyte concentration and machining voltage satisfying uniform shape and large MRR of workpiece were found. For one-step machining, the immersion depth over 1 mm was selected for avoidance of concentration of electric charge at the tip of the microshaft. The limit diameter with good straightness was shown and an empirical formula for WC-microshaft machining was suggested. By controlling the various machining parameters, a straight microshaft with 30 $\mu\textrm{m}$ diameter, over 1 mm length and under 0.5$^{\circ}$ taper angle was obtained.

• Corrosion Science and Technology
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• v.15 no.2
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• pp.92-107
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• 2016

Graphene was coated on austenitic and martensitic stainless steels to simulate the metallic bipolar plate of proton exchange membrane fuel cell (PEMFC). Graphene oxide (GO) was synthesized and was reduced to reduced graphene oxide (rGO) via a hydrazine process. rGO was confirmed by FE-SEM, Raman spectroscopy and XPS. Interfacial contact resistance (ICR) between the bipolar plate and the gas diffusion layer (GDL) was measured to confirm the electrical conductivity. Both ICR and corrosion current density decreased on graphene coated stainless steels. Corrosion resistance was also improved with immersion time in cathodic environments and satisfied the criteria of the Department of Energy (DOE), USA. The total concentrations of metal ions dissolved from graphene coated stainless steels were reduced. Furthermore hydrophobicity was improved by increasing the contact angle.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.3
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• pp.225-231
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• 2011

In this paper, a new end-milling force modelling technique was suggested by considering runout, and its result was compared with real measured force. The specific cutting force is the multiplication of cutting force coefficient and uncut chip thickness. This parameter was used for experimental modelling and prediction of theoretical force. These coefficients, which can be obtained by fitting measured average forces in several conditions, were used for the formulation of theoretical force. The mechanism of end-milling force with runout was developed in this research and its result was verified by comparing the fluctuating theoretical force and its measured one. The fluctuation of force was incurred by a geometric shape of workpiece and its runout in holding. The result of suggested force considering runout shows a good consistency with measured one. So this modelling method can be used effectively for a prediction of end-milling force with runout effect.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.1-10
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• 1999

In this paper, we have investigated the effects of the environmental factors on Low Molecular Weight (LMW) silicone fluid contents existing in high temperature vulcanized (HTV) silicone rubber sample, using dipping method and contact angle, current measurement. Artificial treatments such as immersion in water, elevated temperature, UV irradiation and dry band arcing under salt-fog condition are selected as the environmental factors. This results will be helpful to investigate the degradation with time and to expect a life time, because the LMW silicone content, which is important to recovery the hydrophobicity of silicone rubber surface, show different results by each environmental factors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.947-954
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• 2014

In general, Fracture of the material is not occurring of the maximum normal stress or the maximum shear stress failure in the state. Maximum normal stress and maximum shear stress in the state of Critical coupling from being destroyed based on the Mohr-Coulomb theory. Couple of different mixtures, including permeable asphalt pavement, SMA and dense-graded asphalt mixture, were used for compression triaxial test at $45^{\circ}C$ and $60^{\circ}C$. Mohr-Coulomb theory to the analysis of compression triaxial test result of the internal friction angle $38.9^{\circ}{\sim}46.9^{\circ}$ measured somewhat irregularly, but in the case of cohesion, depending on whether the temperature and immersion of the specimen appeared differently. In addition, Indirect tensile test and compression triaxial test of the asphalt mixture to determine the correlation between compression triaxial test results assessed as cohesion and internal friction angle calculated using the theoretical Indirect tensile strength and measured indirectly tensile strength were analyzed. The Measured & Predicted IDT St values tended to be proportional.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.192-192
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• 1999

SIMS(Secondary Ion Mass Spectrometry)는 다른 표면 분석장비와 비교하여^g , pp m,^g , pp b 단위의 미량분석이 가능한 장비로서, 특히 depth Profiling을 위한 dynamic SIMS는 Mass Spectrometer의 종류에 따라 Quadrupole SIMS (Q-SIMS)와, Magnetic Sector SIMS (M-SIMS)로 분류된다. 한편, Q-SIMS와 달리 M-SIMS의 경우, Transmission을 높여 주기 위해 Sample Holder에 수 keV의 bias를 걸어 주는데, 이로 인하여 분석 원소에 대한 Sensitivity가 향상되어 지는 반면, RSF의 변화와 같은 분석상의 Artifact가 발생하게 된다. 일반적으로 Q-SIMS의 경우에는 RSF의 RSD(Relative Standard Deviation)가 1%이내에서 보고되고 있지만 M-SIMS에 있어서는 이러한 Deviation이 M-SIMS보다 크게 나타난다. 이 차이는 주로 Sample Holder와 Immersion Lens 사이에 형성되는 Magnetic Field의 왜곡과 Spectrometer의 문제로부터 발생한다. 본 논문에서는 Sample Holder의 종류 및 holder so window 위치에 따라 RSF의 차이를 측정하고 그 data를 RS/1 통계 Package를 이용하여 계량적으로 검증하였으며, 그 차이의 원인과 대책을 제시하고자 한다. 실험에 사용된 Sample은 Si(100) p-type Wafer에 Boron을 이온 주입하여 제작하였다. 이온 주입 장비는 Varian E-500HP이며, 5.0E13 ions/cm2의 dose양을 80keV의 Energy로 각각 7도와 22도의 Tilt와 Twist Angle로 이온 주입을 하였다. SIMS분석에 사용된 Sample Holder는 각각 3 Hole, 9 Hole Type HOlder이며, 분석은 Cameca IMS-6f를 사용하여 B에 대한 Matrix Peak으로 28Si++를 얻었다. 실험 결과 3 Hole Type Sample Holder의 경우 RSF의 RSD는 5.84%, 9Hle Type Sample Holder의 경우는 14.3%로 나타났으나 분석 Window의 위치에 따르는 Grouping을 실시한 결과, 3 Hole Type Sample Holder의 경우 1.2%, 9Hole Type Sample Holder의 경우 9.8%로 RSF의 변화가 감소하였다. 이러한 Deviation은 Sample Holder를 Mount시킬 때 세 개의 Screw를 이용하여 Immersion Lens와의 평형을 잡아주기 때문에 발생하며, 이 Munting을 정확히 해줌으로써 RSF의 변화를 줄일 수 있으나, 실제로 완벽한 Mounting이 불가능하기 때문에 RSF를 일정하게 하기 위해서는 Sample Holder so Window의 취치를 일정하게 설정한 후 분석을 실시해야 한다고 판단된다.

• Transactions of the Society of Information Storage Systems
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• v.2 no.4
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• pp.224-229
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• 2006

There has been studied flow to minimize the spot size to increase data capacity. Optical data storage devices are being developed near practical limits with wavelength and NA of 405nm and 0.85. There has been studied many types of next generation storage devices such as blu-ray multilayer system, probe based data storage and holographic data storage. Among these data storage devices, solid immersion lens(SIL) based near field recording (NFR) has been widely studied. In this system, SIL is the key component that focuses the laser beam with a very small size which enables ultra high data capacity. Therefore, optical performance evaluation system is required for SIL assembly. In this dissertation, a simple and accurate SIL assembly measurement method is proposed with wedge plate lateral shearing interferometer(LSI). Wedge plate LSI is cheaper than commercialized interferometer, robust to the vibration and the moving distance for phase shifting is large that is order of micrometer. We designed the thickness, wedge angle, material, surface quality and wavelength of wedge plate as 1mm, 0.02degree, fused silica, lamda/10(10-5) and 405nm, respectively. Also, we confirmed simulation and experimental results with quantitative analysis. This simple wedge plate LSI can be applied to different types of SIL such as solid immersion mirror(SIM), hemispherical, super-hemispherical and elliptical SIL.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.227-231
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• 2010

Super hydrophilic $TiO_2$ thin films with photocatalytic property were successfully fabricated on a glass substrate by liquid phase deposition (LPD). The $TiO_2$ thin film formed nano particles on a surface at $70^{\circ}C$. As an immersion time in $TiF_4$ solution increased, the thickness of thin films gradually increased. $TiO_2$ thin film showed a water contact angel of below ca. $5^{\circ}$ and the transmittance of ca. 75~90 % in visible range. In addition, $TiO_2$ thin film showed the photocatalytic property to decompose methyl orange solution by the illumination of UV light. The surface morphologies, optical properties and contact angel of prepared thin films with a different immersion time were measured by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), UV-Vis spectrophotometer and contact angle meter.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.809-814
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• 2005

In this work, the thermal properties of epoxy coating system on the liner plate in the containment structure of nuclear power plants had been examined by irradiation and design basis accident (DBA) conditions. The effect of immersion in hot water on adhesion strength of the coating system had been also studied. The glass transition temperature ($T_g$) and thermal stability of ET-5290/carbon steel A 32 epoxy coating systems were measured by DSC and TGA analyses, respectively. Contact angle measurements were used to determine the effect of immersion on the surface energetics of epoxy coating system, with a viewpoint of surface free energy. Adhesion tests were also executed to evaluate the adhesion strength at interfaces between carbon steel plate and epoxy resins. As a result, it was found that the irradiation led to an improvement of internal crosslinked structure in cured epoxy systems, resulting in significantly increasing the thermal stability, as well as the $T_g$. Also, the immersion in hot water made a role in the post-curing of epoxy resins and increased the mechanical interlocking of the network system, resulting in increasing the adhesion strength of the epoxy coating system.