• Restorative Dentistry and Endodontics
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• v.29 no.2
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• pp.177-184
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• 2004

Objectives : This study investigated the hypothesis that increasing light-curing time would leave the oxygen-inhibited layer (OIL) of the adhesive thinner, and in turn, result in lower shear bond strength (SBS) than those obtained by the routine curing procedures. Methods：120 human extracted posterior teeth were randomly divided into three groups for bonding with three adhesives：All Bond 2/sup (R)/, One Step/sup (R)/, and Adper Prompt/sup (R)/. They were subsequently divided into four subgourps with different light-curing time (10, 20, 30 and 60s). The assigned adhesives were applied on superficial occlusal dentin according to the manufacturer's instructions and cured with one of the four curing times. Composite resin cylinder, 2.35㎜ in diameter, were built on the cured adhesive and light-cured for 40s. SBS were measured after 24h from the bonding using a universal testing machine (crosshead speed 1.0 ㎜/min). The relative thickness of the OIL and the degree of conversion (DC) were determined from the adhesive on a slide glass using FT-NIR in an absorbance mode. Data were analysed with One-way ANOVA and Duncan's multiple test (p〈0.05), Results：With increasing cure time, although there were no significant difference in th SBS of One-step and Adper Prompt (p〉0.05), those of All Bond 2 decreased significantly (p〈0.05). The relative thicknesses of the OIL on each adhesive were not affected by the cure time (p〉0.05). Although the DC of All-Bond 2 were statistically not different with increasing cure time (p〉0.05), those of One-Step and Adper Prompt showed an increasing trends with increasing cure time (p〈0.05). Conclusions：Increasing light-curing time did not affect on the relative thickness of the OIL of the adhesives, and in turn, on the SBS to dentin.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.12
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• pp.8-13
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• 2001

Cerium oxide ($CeO_2$) thin film has been proposed as a buffer layer between the ferroelectric thin film and the Si substrate in Metal-Ferroelectric-Insulator-Silicon (MFIS) structures for ferroelectric random access memory (FRAM) applications. In this study, $CeO_2$ thin films were etched with $Cl_2$/Ar gas mixture in an inductively coupled plasma (ICP). Etch properties were measured for different gas mixing ratio of $Cl_2$($Cl_2$+Ar) while the other process conditions were fixed at RF power (600 W), dc bias voltage (-200 V), and chamber pressure (15 mTorr). The highest etch rate of $CeO_2$ thin film was 230 ${\AA}$/min and the selectivity of $CeO_2$ to $YMnO_3$ was 1.83 at $Cl_2$($Cl_2$+Ar gas mixing ratio of 0.2. The surface reaction of the etched $CeO_2$ thin films was investigated using x-ray photoelectron spectroscopy (XPS) analysis. There is a Ce-Cl bonding by chemical reaction between Ce and Cl. The results of secondary ion mass spectrometer (SIMS) analysis were compared with the results of XPS analysis and the Ce-Cl bonding was monitored at 176.15 (a.m.u). These results confirm that Ce atoms of $CeO_2$ thin films react with chlorine and a compound such as CeCl remains on the surface of etched $CeO_2$ thin films. These products can be removed by Ar ion bombardment.

• Progress in Superconductivity
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• v.9 no.1
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• pp.23-28
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• 2007

In order to have a superconductive connection between the wire-wound pickup coil and input coil, typically Nb terminal blocks with screw holes are used. Since this connection structure occupies large volume, large stray pickup area can be generated which can pickup external noise fields. Thus, SQUID and connection block are shielded inside a superconducting tube, and this SQUID module is located at some distance from the distal coil of the gradiometer to minimize the distortion or imbalance of uniform background field due to the superconducting module. To operate this conventional SQUID module, we need a higher liquid He level, resulting in shorter refill interval. To make the fabrication of gradiometers simpler and refill interval longer, we developed a novel method of connecting the pickup coil into the input coil. Gradiometer coil wound of 0.125-mm diameter NbTi wires were glued close to the input coil pads of SQUID. The superconductive connection was made using an ultrasonic bonding of annealed 0.025-mm diameter Nb wires, bonded directly on the surface of NbTi wires where insulation layer was stripped out. The reliability of the superconductive bonding was good enough to sustain several thermal cycling. The stray pickup area due to this connection structure is about $0.1\;mm^2$, much smaller than the typical stray pickup area using the conventional screw block method. By using this compact connection structure, the position of the SQUID sensor is only about 20-30 mm from the distal coil of the gradiometer. Based on this compact module, we fabricated a magnetocardiography system having 61 first-order axial gradiometers, and measured MCG signals. The gradiometers have a coil diameter of 20 mm, and the baseline is 70 mm. The 61 axial gradiometer bobbins were distributed in a hexagonal lattice structure with a sensor interval of 26 mm, measuring $dB_z/dz$ component of magnetocardiography signals.

• Analytical Science and Technology
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• v.5 no.4
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• pp.477-484
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• 1992

The mitochondrion was purified at 44% sucrose layer from pleurotus florida by using ultracentrifuge and sucrose density gradient method. Optimum pH and temperature of ATPase and ATP synthase were pH 7.4, $60^{\circ}C$ and pH 7.5, $57^{\circ}C$ respectively, also their Km values were determined as 11.6mM and 8.4mM. ATPase was activated at 5~6mM ATP substrate concentration, then ATP synthase was 5~10mM range ADP. ATPase/ATP synthase were $Mg^{2+}$-dependent enzyme, partially inhibited by their substrate, and then showed an none competitive inhibition pattern by $G_{418}$. Amino acid composition of ATPase/ATP synthase was as follows, hydrophobic amino acid residue was 50.5%, small residue, 56.1%, hydrogen bonding residue, 43.7% and helix breaking residue, 55.2%. Phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl glycerol were contained but not phosphatidyl inositol and phosphatidyl serine. Palmitate(51.31%), stearate(18.32%) and unsaturated fatty acids($C_{18:1}$, $C_{18:2}$ and $C_{16:1}$) were predominated.

• Composites Research
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• v.29 no.3
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• pp.117-124
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• 2016

The failure strength of composite single-lap joint repaired using scarf patch was investigated by test and finite element method. A total of 45 specimens were tested changing scarf ratio, stacking pattern, and defect size to study the failure strength and mode. Except for one case, all repaired specimens showed the equal or higher strength than the sound specimens and the effect of considered repair parameters was not remarkable. It was found through the failure mode inspection that the surface treatment for bonding was not enough in the case which failed at the lower load than the sound specimen. Three-dimensional finite element analysis was conducted to verify the test results. It was confirmed that the considered repair parameters do not significantly affect the stress distribution of the specimens. It was also observed that the applied tensile load is relieved passing through the overlapped region thickness of which is almost double. From this study, it is concluded that if the bonding procedure for adherends and patch including surface treatment for fabric layer is thoroughly followed, the strength of repaired single-lap joint can be restored up to the strength of sound one.

• Journal of Korean Society of Forest Science
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• v.63 no.1
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• pp.12-20
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• 1984

This research was performed to estimate the properties of particleboard based on the press time and temperature which was made of chip of larch that grows in Korea. The results in this study were as follows: 1) Even though the chips, 1:1-35 ratio between length and thickness, are relatively bad condition, the surface smoothness that can easily spread the adhesive evenly and thoroughly and bonding ability of chips can give proper physical properties. 2) It shows more mechanical properties at the press time of 10 min. in MOR (Modulus of Rupture), MOE (Modulus of Elasticity) and SHA (Screw Holding Ability). 3) It is not significant according to the press time 20 min. in MOR, IBS (Internal Bonding Strength) and SHA, for the reciprocal actions between the accelerating aging effect of chip and the softening effect of adhesion are occured. 4) IBS is rising according to the increasing temp at the press time of 10 min. Because it needs to transfer the plate heat to make the proper hardening temp. In the layer. 5) The heat treatment effects have greatly influenced the stahility of dimension by falling the absorption, anisotropy and inhomegenity. As a result of these the values of thickness and linear expansion ratio were respectively dropped by the increase of press temp and the time and so did absorption.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.39-45
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• 2012

Three-dimensional integrated circuit(3D IC) technology has become increasingly important due to the demand for high system performance and functionality. In this work, BOE and HF wet etching of Cu line surfaces after CMP were conducted for Cu-Cu pattern direct bonding. Step height of Cu and $SiO_2$ as well as Cu dishing after Cu CMP were analyzed by the 3D-Profiler. Step height increased and Cu dishing decreased with increasing BOE and HF wet etching times. XPS analysis of Cu surface revealed that Cu surface oxide layer was partially removed by BOE and HF wet etching treatment. BOE treatment showed not only the effective $SiO_2$ etching but also reduced dishing and Cu surface oxide rather than HF treatment, which can be used as an meaningful process data for reliable Cu-Cu pattern bonding characteristics.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.545-553
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• 2003

To achieve good dentin bonding, we must obtain proper wet dentin surface. The purpose of this study was to compare dentin surface according to different wetness degree by AFM image as studying how to obtaining proper wet dentin surface. Intact recently extracted primary teeth were used in the study. The extracted teeth were stored in distilled water at $4^{\circ}C$ until prepared. The teeth were used to prepare 1mm thick dentin disks with exposed surfaces parallel to the occlusal surfaces. The surface of the dentin were polished with polishing disk. The sample were ultrasonically cleaned with distilled water. The sample of each group were treated by different ways. We compared dentin surface of each group by AFM image. From the experiment, the following results were obtained. 1. Acid etching in the dentin surface of primary teeth, resulted in the removal of the smear layer, which opened dentinal tubules, caused the demineralization of peritubular and intertubular dentin, and exposed a collagen-rich transition zone. 2. If the etched dentin was so dehydrated, the intertubular dentin surfaces deceased in height and the diameters of the dentinal tubules decreased slightly. 3. In the group dried with compressed air for 20 seconds at 2 cm, the dentin surfaces were too excessive dried and dehydrated. 4. In the group dried with compressed air for 3 seconds at 2 cm, dry cotton, wet cotton, microbrush and absorbent tissue paper, the dentin surfaces were properly wet.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.57-68
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• 2002

The purpose of this study was to evaluate microleakage of etched and non-etched amalgam restorations lined with dentin bonding system primer and adhesives. Class V amalgam preparations were made in 100 extracted human premolars divided into 10 groups with 10 teeth each. SEM was taken to assess the dentin/amalgam interface. The results were as follows; 1. At the occlusal and gingival margins, all experimental groups showed lower leakage value than unlined group(p<0.05) The $Copalite^{(R)}-lined$ group showed higher leakage value than other experimental groups(p<0.05). 2. In all experimental groups, the gingival margin showed higher leakage value than the occlusal margin. 3. There were no significant difference between non-etching and etching groups, primer only and primer & adhesive groups, primer & adhesive and self-priming adhesive groups(p>0.05). 4. On the SEM observation, continuous gaps were observed in the unlined and $Copalite^{(R)}-lined$ groups, but the gaps were filled with primer or adhesive layer in other experimental groups.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.429-429
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• 2007

For various applications of liquid crystal displays (LCDs), the uniform alignment of liquid crystal (LC) molecules on treated surfaces is significantly important. Generally, a rubbing method has been widely used to align the LC molecules on polyimide (PI) surfaces. Rubbed PI surfaces have suitable characteristics, such as uniform alignment. However, the rubbing method has some drawbacks, such as the generation of electrostatic charges and the creation of contaminating particles. Thus, we strongly recommend a non contact alignment technique for future generations of large high-resolution LCDs. Most recently, the LC aligning capabilities achieved by ultraviolet and ion-beam exposures which are non contact methods, on diamond-like carbon (DLC) inorganic thin film layers have been successfully studied because DLC thin films have a high mechanical hardness, a high electrical resistivity, optical transparency, and chemical inertness. In addition, nitrogen-doped DLC (NDLC) thin films exhibit properties similar to those of the DLC thin films and a higher thermal stability than the DLC thin films because C:N bonding in the NDLC thin filmsis stronger against thermal stress than C:H bonding in the DLC thin films. Our research group has already studied the NDLC thin films by an ion-beam alignment method. The $SiN_x$ thin films deposited by plasma-enhanced chemical vapor deposition are widely used as an insulation layer for a thin film transistor, which has characteristics similar to those of DLC inorganic thin films. Therefore, in this paper, we report on LC alignment effects and pretilt angle generation on a $SiN_x$, thin film treated by ion-beam irradiation for various N ratios