• Journal of the Korean Wood Science and Technology
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• v.21 no.2
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• pp.15-22
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• 1993

This study was carried out to investigate the fracture criterion of glulam. The mixed mode fracture of glulam was investigated by means of single edge notched specimens with various crack inclination in the longitudinal-radial plane. While fracture of wood is not completely understood, the study on linear-elastic fracture mechanics is a rational and valuable tool for studying the strength behavior of glulam. The results are summarized as follows : 1. Glue line has no effect on fracture strength. 2. There is a definite interaction between fracture toughness $K_I$ and $K_{II}$ during the mixed mode fracture of glulam. Several criterions for mixed mode failure were compared. The criterion was expressed in the following form: $(\frac{K_I}{K_{IC}})^2+(\frac{K_{II}}{K_{IIC}})^2=1$ 3. As crack inclination increases, $K_{IC}$ value and $K_{IIC}$ value decreases. The equations relating crack angle to $K_{IC}$ and $K_{IIC}$, respectively, were obtained as follows; $K_{IC}$ = -77.42${\gamma}$+153.72 ($R^2$ = 0.78) $K_{IIC}$ = -9.17${\gamma}$+34.90 ($R^2$ = 0.48)

• Carbon letters
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• v.1 no.1
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• pp.36-40
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• 2000

The initial irreversible capacity (IIC) of a hard carbon during the charge/discharge reaction is strongly affected by both the initial irreversible capacity on the carbon surface $(IIC_S)$ and the initial irreversible lithium insertion into carbon $(IIC_B)$. The initial coulombic efficiency of the insertion and the desertion of lithium (IIE) can be used as a performance to classify $IIC_B$ of the carbon. The $IIC_B$ was proportional to the specific discharge capacity with a slope, $IIE^{-1}$ - 1. The IIE of hard carbon had four regions. $IIE_A$ for the region of 0~95 mAh/g of $Q_{D1}$ was 60.2%. $IIE_B$ and $IIE_C$ for the regions of 95~172 mAh/g and 172~308 mAh/g had 84.9% and 91.5%, respectively. $IIE_D$ was appeared above 308 mAh/g. But, the $IIE_D$ was reduced to 82.1% compared with $IIE_C$. These IIE might be corresponding to lithium desertion from carbon at the region of 0~172 mAh/g range, lithium desertion from the micropore of carbon at the region of 172~308 mAh/g range, and to the lithium stripping of the plated lithium for the region above 308 mAh/g, respectively.

• Journal of the Korean Wood Science and Technology
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• v.20 no.2
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• pp.61-72
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• 1992

This study was carried out to investigate the fracture behavior and the fracture criterion of yellow lauan(Shorea spp.), when has used for furniture and wood structures, and to offer a reliability for wood structure and basic data for wood fracture criterion in experiments which are fracture tested under mode I, mode II and mixed mode loading condition. The results were summarized as follows; 1. Fractures in specimens which have inclined grain in yellow lauan procedeed from crack tip in the radial direction along the grain. 2. In yellow lauan, $K_{IC}RL$ was 42.1kg/$cm^{3/2}$ and $K_{IIC}RL$ was 15.8kg/$cm^{3/2}$. 3. The fracture criteria of lauan were; ($K_I/K_{IC}$)+($K_{II}/K_{IIC}$)=1 in RL system with inclined grain at $45^{\circ}$, ($K_I/K_{IC}$)+$(K_{II}/K_{IIC})^2$=1 with inclined grain at $15^{\circ}$ and $(K_I/K_{IC})^2$+$(K_{II}/K_{IIC})^2$=1 with inclined grain at $30^{\circ}$, $60^{\circ}$, $75^{\circ}$ and $90^{\circ}$, respectively. 4. The fracture criterion of wood could vary with the species, and the load applying condition. In order to measure the fracture criterion strictly, along with standardization of specimen geometry a large amount of experimental data is needed. 5. $K_{IC}$(critical stress intensity factor) can be predicted by grain angle. As the grain inclined angle increased, $K_{IC}$ and $K_{IIC}$ are increased.

• Journal of Adhesion and Interface
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• v.6 no.4
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• pp.1-6
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• 2005

In this work, the effect of chemical treatments on surface properties of SiC was investigated in crack resistance properties of SiC/epoxy composites. The surface properties of SiC were determined by acid/base values and FT-IR measurements. Also the crack resistance properties of the composites were studied in critical strain energy release rate mode II ($G_{IIC}$) measurements. As a result, the acidically treated SiC had higher acid value than that of untreated SiC or basically treated SiC. The crack resistance properties of the composites had been improved in the specimens treated by acidic solution. These results were could be attributed to the acide-base intermolecular interaction between SiC and epoxy resin, resulting in increase of the degree of adhesion at interfaces.

• Steel and Composite Structures
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• v.26 no.2
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• pp.241-253
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• 2018

Mode II fracture toughness, $K_{IIC}$, of single-ply triaxially woven fabric (TWF) composite due to tow waviness and anisotropy effects were numerically and experimentally studied. The numerical wavy beam network model with anisotropic material description denoted as TWF anisotropic was first validated with experimental Mode II fracture toughness test employing the modified compact tensile shear specimen configuration. 2D planar Kagome and TWF isotropic models were additionally constructed for various relative densities, crack lengths, and cell size parameters for examining effects due to tow waviness and anisotropy. $K_{IIC}$ generally increased with relative density, the inverse of cell size, and crack length. It was found that both the waviness and anisotropy of tow inflict a drop in $K_{IIC}$ of TWF. These effects were more adverse due to the waviness of tow compared to anisotropy.

• IT SoC Magazine
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• s.24
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• pp.22-28
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• 2008

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.397-400
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• 2007

For mapping the distribution of heavy metals in the mining area, field spectroscopy and hyperspectral remote sensing were used in this study. Although heavy metals are spectrally featureless from the visible to the short wave infrared range, possible variations in spectral signal due to heavy metals bound onto minerals can be explained with the metal binding reaction onto the mineral surface. Variations in the spectral absorption shapes of lattice OH and oxygen on the mineral surface due to the combination of heavy metals were surveyed over the range from 420 to 2400 nm. Spectral parameters such as peak ratio and peak area were derived and statistically linked to metal concentration levels in the streambed samples collected from the dry stream channels. The spatial relationships between spectral parameters and concentrations of heavy metals were yielded as well. Based on the observation at a ground level for the relationship between spectral signal and metal concentration levels, the spectral parameters were classified in a hyperspectral image and the spatial distribution patterns of classified pixels were compared with the product of analysis at the ground level. The degree of similarity between ground dataset and image dataset was statistically validated. These techniques are expected to support assessment of dispersion of heavy metal contamination and decision on optimal sampling point.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.214-219
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• 2014

In this paper, a new robot system is designed and manufactured to improve the educational robot. The main processor is realized using the ARM Cortex-M3 and the co-processor is implemented by AVR ATMega2560 to deal with data coming from sensor modules. The processor of sensor modules was developed by the AVR ATMega8. The communication system is composed with IIC communication to alleviate the load of main processor. We have developed the educational robot system adopting the hub module for extension characteristics.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.5
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• pp.189-193
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• 2003

Initial irreversible capacity (IIC) can be defined by means of the initial intercalation Ah efficiency (IIE) and the initial irreversible specific capacity at the surface (IICs) with the linear-fit range of the intercalation so as to precisely express the irreversibility of an electrode-electrolyte system. Their relationship was IIC = Qc - Q$_{D}$ = (IIE$^{-1}$ - 1) Q$_{D}$ + IICs in the linear-fit range of IIE. Here, Qc and Qd signify charge and discharge capacity, respectively, based on a complete lithium ion battery cell. Charge indicates lithium insertion to carbon anode. Two terms of IIE and IICs depended on the types of active materials and compositions of the electrode and electrolyte but did not change with charging state. In an ideal electrode-electrolyte system, IIE and IICs would be 100%, 0 mAh/g for the electrode and mAh for the cell, respectively. These properties can be easily obtained by the Gradual Increasing of State of Charge (GISOC).OC).

• The Korean Journal of Ecology
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• v.16 no.3
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• pp.365-374
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• 1993

Pollen analysis on a 320cm core collected from paengsung area (36°56′50"N, 127°03′10"E) in southwesterm korea was carried out to investigate the changes in past climate and vegetation in that area. In this research it was found that pollen zones are divided into two layers of substage IIb and IIc. Pollen zone IIb, the lower layer, was dominated by high percentages of deciduous broadleaved trees such as alnus, Quercus, Corylus, Betula, Carpinus and Salix. Trapa, Typhaceae and Nymphaceae growing in wet habitat and Chenpodiaceae were pornounced amont the nonrboreal pollens. At that time, it seems that it was warmer and more humid than present. In pollen zone IIc, the upper layer, pollen of Pinun was dominant and those of Artemisia, Gramineae, Compositae, Cyperaceae and spore increased while of Quercus, Betula and Nymphaceae decreased. It is supposed that the climate of this zone was drier that the lower laywer.