• Electrical & Electronic Materials
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• v.16 no.9
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• pp.64.2-65
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• 2003

A 4 nm layer of ZrOx (targeted x-2) was deposited on an interfacial layer(IL) of native oxide (SiO, t∼1.2 nm) surface on 200 mm Si wafers by a manufacturable atomic layer chemical vapor deposition technique at 30$0^{\circ}C$. Some as-deposited layers were subjected to a post-deposition, rapid thermal annealing at $700^{\circ}C$ for 5 min in flowing oxygen at atmospheric pressure. The experimental x-ray diffraction, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and high-resolution parallel electron energy loss spectroscopy results showed that a multiphase and heterogeneous structure evolved, which we call the Zr-O/IL/Si stack. The as-deposited Zr-O layer was amorphous $ZrO_2$-rich Zr silicate containing about 15% by volume of embedded $ZrO_2$ nanocrystals, which transformed to a glass nanoceramic (with over 90% by volume of predominantly tetragonal-$ZrO_2$(t-$ZrO_2$) and monoclinic-$ZrO_2$(m-$ZrO_2$) nanocrystals) upon annealing. The formation of disordered amorphous regions within some of the nanocrystals, as well as crystalline regions with defects, probably gave rise to lattice strains and deformations. The interfacial layer (IL) was partitioned into an upper Si $o_2$-rich Zr silicate and the lower $SiO_{x}$. The latter was sub-toichiometric and the average oxidation state increased from Si0.86$^{＋}$ in $SiO_{0.43}$ (as-deposited) to Si1.32$^{＋}$ in $SiO_{0.66}$ (annealed). This high oxygen deficiency in $SiO_{x}$ indicative of the low mobility of oxidizing specie in the Zr-O layer. The stacks were characterized for their dielectric properties in the Pt/{Zr-O/IL}/Si metal oxide-semiconductor capacitor(MOSCAP) configuration. The measured equivalent oxide thickness (EOT) was not consistent with the calculated EOT using a bilayer model of $ZrO_2$ and $SiO_2$, and the capacitance in accumulation (and therefore, EOT and kZr-O) was frequency dispersive, trends well documented in literature. This behavior is qualitatively explained in terms of the multi-layer nanostructure and nanochemistry that evolves.ves.ves.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.2
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• pp.208-219
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• 2001

To study the effect of dentin permeability on a tooth with wear from tooth brushing after application of desensitizing agent, extracted teeth free from caries were chosen. Coronal dentin discs with thickness of 1mm were prepared. Using the split chamber device developed by Pashely, hydraulic conductance, scanning electron microscope images(SEM) and atomic force microscope images(AFM) were compared and contrasted before and immediately after the application of desensitizing agent and after equivalent tooth brushing of 1 week, 2 weeks, and 6 weeks. Four commercially available desensitizing agents were used in this study ; they were Gluma, Seal & Protect, All-Bond 2 and MS Coat. The results of this study are as follows. 1. On all specimens, the hydraulic conductance decreased after the application of tooth desensitizing agent. 2. Except the specimens treated with MS Coat, the remaining specimens had an increase in dentin permeability after tooth brushing for 1 and 2 weeks but a decrease after 6 weeks. 3. The specimens treated with MS Coat had statistically significant increase in the dentin permeability regardless with the duration of tooth brushing. 4. On examination of SEM and AFM, the dentinal tubule diameter had decreased after treatment of desensitizing agents. The specimens other than those treated with MS Coat, smear layers were noted after tooth brushing. It is not always consistant but the hydraulic conductance correlated with the images from SEM and AFM.

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.181-185
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• 2005

Lithium cobalt oxide thin film cathode, having thickness of $2.9{\mu}m$ with area of $4cm^2$, was deposited on platinum patterned alumina substrate by radio frequency magnetron sputtering. Li/Co molar ratio, which is an important factor for battery performance, was measured as a function of argon working pressure and applied R.F. power. Constant current charge and discharge performances were characterized with high rate discharge and cycling behavior. Using AC impedance analysis, internal resistance of the thin film battery was measured and simulated by proposed equivalent circuit model.

• Fashion & Textile Research Journal
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• v.12 no.6
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• pp.789-795
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• 2010

The purpose of this study was to examine the appropriate surplus of clothing for a jacket bodice pattern of middle-aged obese men by using the 3D virtual twin and virtual garment simulation system. The results were as follows ; 1. BMI rate of middle-aged males was 28.13 which was equivalent to mild obesity, whereas WHR(W/H ratio from waist to hips) rate was near 1.00 which was highly dangerous against their obesity. In case of middle-aged obese men, the WHR was significantly higher than the entire middle-aged men's average and the section shape in which their thickness was relatively more than width. 2. As a result of appearances evaluation through virtual garment simulation, the cut-off amount of the side seam and the center back was regulated accordingly. Hereby, the final tolerance range was set up at 21.15 cm at the hips, so that the appearances became better and the bilateral distribution of the cross section and space length was formed symmetrically. Especially in case of increasing the cross amount of hems to produce a natural silhouette of the waist-to-hips parts, the ease of buttocks was judged to be moderate, but it turned out that a wavy cross section was made and the silhouette was not good. Thus it was found to be not good that the ease of the hips became excessively increased in proportion as circumference of waist and belly were increased in obesity. The use of the virtual twin made it impossible to comprehend the appearances and ease correspondent to motions. In order to evaluate wearing fitness, therefore, the system should be improved so as to change arm positions and perform various motions.

• Composites Research
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• v.16 no.4
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• pp.29-35
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• 2003

In this paper. various tow parameters such as equivalent tow thickness, amplitude of longitudinal tow and tow intervals were investigated and compared with each other by using microscopic observation to find out the exact deformation patterns between both directions of the fabric structure(Longitudinal and Transverse Directions). And those observation results were compared with bias extension. biaxial tests results with dry fabric which has the same tow structure as the draped helmet materials and also compared with prepreg specimen which is cured by autoclave moulding without vacuum and pressure condition. Specimens for the observation were taken from draped helmet which is made of fabric composite(Five Harness Satin Weave). From the observation results, it was found that there are different deformation pattern between tow directions and effect of geometric condition on the deformation of the fabric materials during draping process was verified.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.1
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• pp.118-129
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• 1997

The purpose of this study was to evaluate the shock absorbing effect of 4 restorative materials and intramobile connector. The damping effect of four restorative materials used to veneer test crown rigidly connected to IMZ implant and subjected to an impact force was measured. These materials included a gold alloy(stabilor G) : a noble metal ceramic alloy(Degudent H) : porcelain(Duceram) : composite resin(Dentacolor). In addition, this study compared damping effect of same restoretive materials after using polyoxymethylene intramobile connector(POM IMC). The result of this study suggest that : In case of using metal IMC 1. Veneered composite resin(group IV) reduced the impact force by 75%, when compared to an equivalent thickness of porcelain(group III). Group IV reduced the impact force by 87% and 89%, respectively, when compared to Stabilor G(group I) and Degudent H(group II). 2. The impact force recorded was higher for the alloy with the higher elastic modulus.(Stabilor G, group I, Young's modulus 107 Gpa, versus Degudent H, Group II, Young's modulus 95 Gpa) 3. It took the longest time for composite resin veneered group(IV) to reach to peak force when compared group I, II, III. In case of using POM IMC 4. The mean impact force recorded were reduced by 79%(group I), 78%(group II), 69%(group III), 84%(group IV), respectively, when compared to using metal IMC. 5. The time required to reach the peak force were increased by 78%(group I, II) 87%(group III), 34%(group IV), respectively, when compared to using metal IMC>.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.25-32
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• 2006

Behavior of concrete pavement due to temperature gradient was investigated for 48 hours at test road using Falling Weight Deflectometer. The deflections at slab center changed similarly to those of ambient temperature and temperature gradients in the slab. And rapid variations in the deflections were observed between 8 to 12 in the morning. However, dynamic modulus of subgrade reaction and joint deflections showed reverse trends to the ambient temperature and temperature gradients. The dynamic modulus of subgrade reaction was significantly affected by temperature gradient when its value got higher. Backcalculated elastic moduli were obtained using AREA method and Method of Equivalent Thickness. The trends of the backcalculated elastic modulus were similar to those of dynamic modulus of subgrade reaction. Measured load transfer efficiencies showed maximum peak in the morning due to dowel locking. However, additional effort is necessary to verify the result.

• Magazine of the Korea Concrete Institute
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• v.5 no.2
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• pp.181-188
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• 1993

In this study, a numerical method for the material nonlinear analysis of reinforced concrete shell structures including the time dependent effects due to creep and shrinkage is developed. Degenerate shell elements with the layered approach are used. The perfect or strain hardening plasticity model in compression and the linearly elastic model in tension until cracking for concrete are employed. The reinforcing bars are considered as a steel layer of equivalent thickness. Each :steel layer has an uniaxial behaviour resisting only the axial force in the bar direction. A bilinear idealization is adopted to model elasto-plastic stress-strain relationships. For the nonlinear anaysis, incremental load method combined with unbalanced load iterations for each load increment is used. To include time dependent effects of concrete, time domain is divided into several time steps which may have different length. Some numerical examples are presented to study the validity and applicability of the present method. The results are compared with experimental and numerical results obtained by other investigator.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.155-160
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• 2002

Metal matrix composites had generated a lot of interest in recent times because of significant in specific properties. It was also highlighted as the materials of frontier industry because strength, heat-resistant, corrosion-resistant, wear-resistant were superiored. In this study the strength properties of $Al_{18}B_4O_{33}/AC4CH$ were represented mixing the binder of $Al_2O_3$ and $TiO_2$. It was also fabricated by squeeze casting. $Al_{18}B_4O_{33}/AC4CH$ was fabricated at the melt temperature of $760^{\circ}C$ the perform temperature of $700^{\circ}C$ and mold temperature of $200^{\circ}C$ under the pressure of 83.4MPa and observed SEM. Fatigue crack growth rate tests on compact tension specimen(half-size) of thickness 12.5mm were conducted by using sinusoidal waveform. Compact tension specimens(half-size) were used and fatigue crack growth rate da/dN and stress intensity factor range ${\Delta}K$ were analyzed concerning to the R value of 0.1 and 0.05. In order to find out the value of ${\Delta}K$, load amplitude constant method was applied by the standard fatigue testing method describes in ASTM E647-95a. As the results of this study, Fatigue crack growth rate increased with in creasing the load ratio, Consequently, At equivalent stress intensity factors, the fatigue crack growth rates in MMC were faster than those of AC4CH alloy. then the fatigue life and the fatigue crack growth rate was investigated using scanning election microscopy(SEM)

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.204-210
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• 2004

Most auto-body members fabricated by the sheet metal forming process. During this process the thickness and material properties of the sheet metal are changed with the residual stress and plastic strain. This paper deals with the material properties of the sheet metal at the high strain rate considering the pre-strain effect. Specimens are selected from sheet metals for outer panels and inner members, such as SPCEN, SPRC45E, SPRC35R and EZNCD. The specimens are prepared with the pre-strain of 2, 5 and 10 % by tensile elongation in Instron 5583, which could be equivalent to the plastic strain in sheet metal forming. High speed tensile tests are then carried out with the pre-stained specimens at the strain rate of 1 to 100/sec. The experimental result informs that the material properties are noticeably influenced by the pre-strain when the yield stress of the specimens is moderate as SPCEN, SPRC35R and EZNCD. The result also demonstrates that the ultimate tensile strength as well as the yield stress is increased as the amount of the pre-strain is increased.