• Magazine of the Korea Concrete Institute
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• v.11 no.1
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• pp.129-139
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• 1999

Recently, many strengthening methods are developed and used to rehabilitate existing structures. One of the old and popular methods is strengthening with bonding steel plate. However, steel plate bonding method has a defect, which is debonding failure of steel plate before yielding of the plate due to stress concentration at the of the bonded plate. The objective of this study is the experimental verification of the improved bonding properties of a strengthening plate with notches. Two normal beams and ten strengthened beams with steel plate, which have several different notches, are tested and showed their effectiveness. Test results show that the notches of strengthening plate significantly improve post-yielding behavior, compared to normally strengthened beams. It is proved that the notches of strengthening plate increases ultimate strength 14% more than normal strengthened beam after yield strength. As for the shape of notches, arc notch is the best. and triangle notch and trapezoidal notch are the next and end welding method has no effect.

• Carbon letters
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• v.14 no.3
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• pp.186-189
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• 2013

We report a highly sensitive $NO_2$ gas sensor based on multi-layer graphene (MLG) films synthesized by a chemical vapor deposition method on a microheater-embedded flexible substrate. The MLG could detect low-concentration $NO_2$ even at sub-ppm (<200 ppb) levels. It also exhibited a high resistance change of ~6% when it was exposed to 1 ppm $NO_2$ gas at room temperature for 1 min. The exceptionally high sensitivity could be attributed to the large number of $NO_2$ molecule adsorption sites on the MLG due to its a large surface area and various defect-sites, and to the high mobility of carriers transferred between the MLG films and the adsorbed gas molecules. Although desorption of the $NO_2$ molecules was slow, it could be enhanced by an additional annealing process using an embedded Au microheater. The outstanding mechanical flexibility of the graphene film ensures the stable sensing response of the device under extreme bending stress. Our large-scale and easily reproducible MLG films can provide a proof-of-concept for future flexible $NO_2$ gas sensor devices.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.999-1006
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• 2014

$CO_2$ emission factor for earthwork equipment was made based on fuel consumption quantity using IPCC carbon emission factor. This is presented through the carbon emission estimating guideline each facilities by the Ministry of Land, Infrastructure and Transportation in 2011. However, this method has the defect which don't apply the various condition of site. Therefor it needs the new emission factor supplemented these defects. This study will tries to estimate $CO_2$ emission with the direct measurement method using concentration flow velocity measurement (C-FVM) for earth work equipment and present the new $CO_2$ emission factor for earth work equipment after compare with emission factor of the Ministry of Land, Infrastructure and Transportation.

• Progress in Superconductivity
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• v.3 no.1
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• pp.5-12
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• 2001

Our experimental research focuses on manipulating pinning deflects to alter the phase diagram of vortex matter, creating new vortex phases. Vortex matter offers a unique opportunity for creating and studying these novel phase transitions through precise control of thermal, pinning and elastic energies. The vortex melting transition in untwinned YB $a_2$C $u_3$ $O_{7-}$ $\delta$/ crystals is investigated in the presence of disorder induced by particle irradiation. We focus on the low disorder regime, where a glassy state and a lattice state can be realized in the same phase diagram. We follow the evolution of the first order vortex melting transition line into a continuous transition line as disorder is increased by irradiation. The transformation is marked by an upward shift in the lower critical point on the melting line. With columnar deflects induced by heavy ion irradiation, we find a second order Bose glass transition line separating the vortex liquid from a Bose glass below the lower critical point. Furthermore, we find an upper threshold of columnar defect concentration beyond which the lower critical point and the first order melting line disappear together. With point deflect clusters induced by proton irradiation, we find evidence for a continuous thermodynamic transition below the lower critical point..

• Korean Journal of Microbiology
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• v.22 no.3
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• pp.135-142
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• 1984

The effect of biotin on the growth and sporulation of Bacillus subtilis SNU816 was investigated. When B. subtilis SNU816 was cultured on glucose as a sole carbon source, the growth was retarded markedly and usually ceased at early log phawe. But by addition of biotin to this medium, normal, rapid growth was restored. The growth rate was increased proportionally according to the concentration of exogenous biotin until it reached to 0.05㎍/ml, at which about three fold rapid growth was achieved. Also biotin was required for optimum sporulation for it facilitated the complete utilization of both glucose(Glc) and glutamic acid(Glu). Without biotin in Glc+Glu medium, about 40% of glutamic acid was remained unutilized. The dipicolinic acid content of cells cultured in Glc+Glu medium without biotin was markedly small and sporulation was suppressed before free spore release. Since biotin could be partiallyreplaced by one of TCA cycle intermediates such as oxalacetic acid, citric acid, or glutamic acid in enhancing growth in Glc medium, it was postulated that this strain might have a defect in converting pyruvate to oxalacetate which process is known to be mediated by pyruvate carboxylase that requires biotin as a cofactor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.996-1000
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• 2005

Experimental results are presented for the degradation of 3 nm-thick gate oxide $(SiO_2)$ under both Negative-bias Temperature Instability (NBTI) and Hot-carrier-induced (HCI) stresses using P and NMOSFETS, The devices are annealed with hydrogen or deuterium gas at high-pressure $(1\~5\;atm.)$ to introduce higher concentration in the gate oxide. Both interface trap and oxide bulk trap are found to dominate the reliability of gate oxide during electrical stress. The degradation mechanism depends on the condition of electrical stress that could change the location of damage area in the gate oxide. It was found the trap generation in the gate oxide film is mainly related to the breakage of Si-H bonds in the interface or the bulk area. We suggest that deuterium bonds in $SiO_2$ film are effective in suppressing the generation of traps related to the energetic hot carriers.

• Journal of the Korean institute of surface engineering
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• v.53 no.4
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• pp.169-181
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• 2020

The ferroelectricity in emerging fluorite-structure oxides such as HfO₂ and ZrO₂ has attracted increasing interest since 2011. Different from conventional ferroelectrics, the fluorite-structure ferroelectrics could be reliably scaled down below 10 nm thickness with established atomic layer deposition technique. However, defects such as carbon, hydrogen, and nitrogen atoms in fluorite-structure ferroelectrics are reported to strongly affect the nanoscale polymorphism and resulting ferroelectricity. The characteristic nanoscale polymorphism and resulting ferroelectricity in fluorite-structure oxides have been reported to be influenced by defect concentration. Moreover, the conduction of charge carriers through fluorite-structure ferroelectrics is affected by impurities. In this review, the origin and effects of various kinds of defects are reviewed based on existing literature.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.160-166
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• 1998

The field emission characteristics of defective diamond films grown by microwave plasma enhanced chemical vapor deposition (MPECVD) have been studied. X-ray diffraction, the poor crystal quality and/or small grain sizes of the diamond phase and the inclusion of the non-diamond carbon phases in these films have been condirmed by raman spectroscopy, scanning electron microscopy, atomic force microscopy, and the reflectance measurements. The degrees of the film defectiveness and the emission characteristics were dependent on the methane concentration. Current-versus-voltage measurements have demonstrated that the defective diamond films have good electron emission characteristics. characteristics strongly suggests the defect-related electron-emission mechanism. The defective diamond films deposited on Si substrates show the field emission current density of 1$\mu\textrm{A}/\textrm{cm}^2$ and 1mA/$\textrm{cm}^2$ have been measured at electric fields as low as 4.5V/$\mu\textrm{m}$ and 7.6V/$\mu\textrm{m}$, respectively. We also observed the similar emission characteristics from the defective diamond film deposited on Cr/Si substrate and could decrease the deposition temperature to $600^{\circ}C$.

• The korean journal of orthodontics
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• v.15 no.1
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• pp.55-66
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• 1985

The study was undertaken to ascertain the speech defect of patients with malocclusion, especially of openbite patients, by means of the spectral analysis method. The experimental group was composed of ten female openbite patients and their mean age was 13.8 yrs. The control group was also composed of ten female girls and their mean age was 13.7 yrs. As for the speech material, eight Korean monophthrongs and two Korean fricatives and two affricatives were used. Speeches were recorded and then analyzed by a Kay 7800 digital sonagraph. Formant frequency level or range was used as a phonemic parameter. The results were as follows: 1. Among Vowels /a:/ : $F_1,\;F_3\;and\;F_1/F_2$ showed abnormality. /o:/ and $/w:/:F_2,\;F_2-F_1\;and\;F_1/F_2$ showed abnormality. 2. Among Consonants /S/ and /h/ : The upper and lower borders of the frequency range showed abnormality. (equation omitted) : The lower border of the frequency range showed abnormality. $/C^{h}/$ : The upper and lower borders of the frequency range and concentration point showed abnormality.

• Structural Engineering and Mechanics
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• v.61 no.1
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• pp.1-13
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• 2017

The effectiveness of the repair scheme for the damaged captive-columns with CFRPs (Carbon Fiber Reinforced Polymer) was investigated in terms of response quantities such as strength, ductility, dissipated energy and stiffness degradation. Two 1/3 scale, one-story one-bay RC (Reinforced Concrete) frames were designed to represent the substandard RC buildings in Turkish building stock. The first one, which is the reference specimen, is the bare frame without infill wall. Partial infill wall with opening was constructed between the columns of the second frame and this caused captive column defect. Severe damage was observed with the concentration of shear cracks in the second specimen columns. Then, the damaged members were repaired by CFRP wrapping and retested. For the three test series, similar reversed cyclic lateral displacement under combined effect of axial load was applied to the top of the columns. Overall response of the bare frame was dominated by flexural cracks. Brittle type of shear failure in the column top ends was observed in the specimen with partial infill wall. It was observed that former capacity of damaged members of the second frame was recovered by the applied repair scheme. Moreover, ultimate displacement capacity of the damaged frame was improved considerably by CFRP wrapping.