• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.262-267
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• 2009

Superhydrophobic $TiO_2$ thin films were successfully fabricated on a glass substrate by wet process. Layer-by-layer (LBL) deposition and liquid phase deposition (LPD) methods were used to fabricate the thin films of micro-nano complex structure with a high roughness. To fabricate superhydrophobic $TiO_2$ thin films, the (PAH/PAA) thin films were assembled on a glass substrate by LBL method and then $TiO_2$ nanoparticles were deposited on the surface of (PAH/PAA) thin film by LPD method, Subsequently, hydrophobic treatment using fluoroalkyltrimethoxysilane (FAS) was carried out on the surface of prepared $TiO_2$ thin films. The $TiO_2$ thin film fabricated with 45 minutes immersion time on $(PAH/PAA)_{10}$ showed the RMS roughness of 65.6nm, water contact angel of $155^{\circ}$ and high transmittance of above 80% (>650nm in wavelength) after the hydrophobic treatment. The Surface morphologies, optical properties and contact angel of prepared thin films with different experimental conditions were measured by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), UV-Vis spectrophotometer and contact angle meter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.519-520
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• 2006

The aim of this study was biomechanical analysis of shelf operation in patients with dysplastic hip joint by finite element contact analysis. Two dimensional CT images were used to construct the finite element models to analyze the contact pressure, and the 3D expansion of the Ninomiya's method was used in the calculation of the resultant force in the hip joint. The surgery recovered the center-edge angles to the normal anatomical range and increased the contact areas in two patients. The maximum contact pressures and von-mises stresses were decreased. The present study provides the biomechanical guideline of optimal surgical parameters to maximize the surgical efficiency and the clinical outcomes in dysplastic hip joint using the shelf operation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.821-827
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• 2001

In this study performed to identify a degradation mechanism in macromolecular insulating material, the contact angel, surface potential decay, surface resistivity, and XPS analysis were compared after exposure of FRP laminate to plasma discharge. In the case of contact angle, the surface of specimen untreated showed weak hydrophobic property of 73。. However, the contact angle was decreased to 20。in the plasma-treated specimen. In the case of chemical changes arising form plasma treatment, carboxl radicals were generated mainly in the surface treated, which was rapidly changed to the hydrophilic one. In the corona potential decay study to determine the electrical changes of the surface, positive charges were rapidly decreased when compared with negative charges, leading to negative property in the surface of specimen not treated. However, in the case of the hydrophilic surface, lots of carboxl radicals acting as positive polarity were generated, resulting in positive surface. Owing to such positive surface, charges of negative polarity applied were rapidly decreased.

• Journal of Radiation Industry
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• v.8 no.1
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• pp.43-47
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• 2014

By measuring decrease change of the contact angle after microwave plasma treatment on the glass and Al as a scintillator panel sample substrate, the adhesive performance of scintillator panel can be expected to improve. Also resolution and sensitivity of scintillator panel after microwave plasma treatment can be expected to maintain highly.

• 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.

• Journal of Oral Medicine and Pain
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• v.23 no.2
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• pp.143-155
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• 1998

This study was performed to investigate the factor that might affect mandibualr body rotation. For the study, 115 patients with temporomandibular disorders and 35 dental students without angy signs and symptoms of temporomandibular disorders were randomly selected as the patient group and the contreol group, respectively. Preferred chewing side, Angle' classification, lateral guidance pattern, and affected side were clinically recorded, and the amount of Mandibular body rotational torque movement was measured in wide opening and closure, in right and left excursion with vertical and lateral distance in frontal plane, right and left rotational angel in horizontal and in frontal plane. Masticatory muscle activity of anteriorocclusal contact pattern on maximal hard biting were also observed synchronously with BioEMG and T-Scan , respectively. The observed items were muscle activity of anterior temporalis and superficial masseter, and tooth contact status related to contact number, force, duration, and occlusal unbalance between right and left arch. The data collected were analyzed by SAS statistical program. The results of this study were as follows : 1. Mean value of vertical distance in frontal plane in wide opening and closure was more in control subjects than in patients, but there was no difference for rotational angle. In right excursion, rotational angles were greater in patient group than in control group. 2. Comparison among the subjects by preferred chewing side did not reveal any significant difference, but comparison among patients by affected side showed more rotational amount in bilaterally affected patients than in unilaterally affected patients. 3. Comparison among the subjects by Angle's classification or lateral guidance pattern revealed no difference. There was also no difference between preferred chewing side and contralateral side, and between affected side and contralateral side. 4. Positive correlation in madibular rotational torque movements were observed among vertical distance, total horizontal rotation angle, electromyographic activity of anterior temporalis, tooth contact number, and tooth contact force but total frontal rotation angle almost did not show any correlation with other variables except vertical distance.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.138-147
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• 1999

For autonomous navigation, a legged robot should be able to walk over irregular terrain and adapt itself to variation of supporting surface. Walking through slope is one of the typical tasks for such case. Robot needs not only to change foot trajectory but also to adjust its configuration to the slope angle for maintaining stability against gravity. This paper suggests such adaptation algorithm for stable walking which uses feedback of reaction forces at feet. Adjusting algorithm of foot trajectory was studied with the estimated angel of slope without visual feedback. A concept of virtual slope angle was introduced to adjust body configuration against slope change of the supporting terrain. Regeneration of foot trajectory also used this concept for maintaining its stable walking against unexpected landing point.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.9
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• pp.119-126
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• 2004

In this paper, we design a wedge type rail clamp which can protect container crane from a sudden strong blast with constant clamping force regardless of the operating period. When we design wedge type rail clamp, it is important to determine the angle of wedge and analyze a contact condition of roller and wedge so that we might develop a wedge type rail clamp for parking devices of port cargo working system with variable capacity. Therefore, this paper suggests a process to decide wedge angles within feasible range which could be obtained using load analysis and FEA of wedge type rail clamp

• Journal of the Korean Chemical Society
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• v.56 no.6
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• pp.725-730
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• 2012

HEMA (2-hydroxyethyl methacrylate), EGDMA (ethylene glycol dimethacrylate; cross-linker), MMA (methyl methacrylate) and AA (acrylic acid) were copolymerized with ethyl gallate and propyl gallate as additives in the presence of AIBN (2,2'-azobisisobutyronitrile; initiator). The measurement of physical properties of the produced copolymers exhibited that refractive index, water content, visible transmittance, tensile strength, and contact angle were in the range of 1.433-1.435, 38.71-38.99%, 85.4-88.8%, 0.2468-0.2740 kgf and $49.77-36.29^{\circ}$, respectively. The transmittances of the copolymers were measured to be in the range of 49.0-7.4% and 71.0-43.4% for UV-B and UV-A, respectively, indicating that the copolymers have UV-blocking effect. The produced copolymers containing ethyl gallate and propyl gallate satisfied the basic physical properties required for the fabrication of hydrogel contact lenses. The copolymers showed an increase of wettability and UV-blocking effects while having no significant change in water content compared to the gallate-free copolymers.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.4
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• pp.168-172
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• 2010

Superhydrophilic thin film consisted of positively charged poly (allylamine hydrochloride) (PAH) and negatively charged poly (acrylic acid) (PAA) was fabricated by a layer-by-layer (LBL) self-assembly. Glutaraldehyde (GA) was used in order to increase an adhesion hardness by amine-aldehyde reaction. The surface morphology, thickness, transmittance, water contact angle and adhesion hardness of PAH/PAA thin film with or without GA were measured. The adhesion hardness of PAH/PAA thin film with GA deposition increased over 2 times although the film thickness of PAH/GA/PAA decreased than that of PAH/PAA thin film. The increase of adhesion hardness by amine-aldehyde reaction between PAH and GA was measured by fourier transform infrared (FT-IR) spectroscopy. Fabricated PAH/PAA and PAH/GA/PAA thin films showed water contact angel under $5^{\circ}$ and high transmittance over 91.3% at 550 nm.