• Journal of the Korean Chemical Society
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• v.23 no.6
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• pp.358-367
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• 1979

EHT and CNDO/2 calculations have been performed to determine conformations of acetamides and diacetamides, and of their protonated forms. Results show that: protonation is always favored on the cis position with respect to N due to greater attractive potential between $H^+$ and N; the trans-trans conformer of diacetamides gives the most preferred protonated form although the cis-trans conformer is the most stable one for the unprotonated diacetamides. Protonation on a carbonyl oxygen is predicted to increase both charge and orbital controlled $S_N$SN reactivities of the protonated carbonyl carbon due to increases in positive charge and AO coefficient of ${\pi}$-LUMO of the carbon atom. In the acid catalyzed hydrolysis of diacetamides therefore it appears highly probable that the rate determining attack by a water molecule occurs at the carbon of the protonated carbonyl group and the carbonyl carbon-nitrogen bond scission follows subsequently. This mechanism is consistent with that generally accepted for the hydrolysis of amides in dilute acid solution but disagrees with that proposed by Laureut et al., for acid hydrolysis of N-acetyl-lactams.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.31-36
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• 1994

The bonding behavior of $SiO_{2}$ thin film and glass during VCR head fabrication was investigated, varying the surface roughness of substrate and the sputtering parameter. Insufficient fillings of grooves In the $SiO_{2}$ film with glass was postulated to give rise to the generation of bubble in the glass. The surface roughness of $SiO_{2}$ film was found to depend on that of substrate. The lower the deposition rate, the smoother the surface of film. The bubble free glass after bonding could be obtained using substrate polished with 0.05$\mu\textrm{m}$ $Al_2O_3$ powder under the sputtering condition of 10% oxygen pressure.

• Journal of the Korean Chemical Society
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• v.18 no.3
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• pp.180-188
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• 1974

Adsorption mechanism of alkyl aldehydes, acetaldehyde, acrolein, and crotonaldehyde on cations supported by layer silicates was studied by means of IR spectroscopy and X-ray. An analysis of four characteristic split bands in the region of $1720∼1580㎝^{-1}$ was made. The carbonyl stretching band which shifted about $130㎝^{-1}$ to lower frequencies was observed only for $Ni^{2+}$ and Al^{3+}$ but slightly with $Ca^{2+}$ at high sample temperature and was attributed to >C=O…M complex formation. A sharp band which appeared as a shoulder at 1722 for acetaldehyde and 1690 for acrolein and crotonaldehyde was responsible for the interaction of carbonyl with surface hydroxyl. The second broad band which appeared at about 1710~1660 was responsible for hydrogen bonding between carbonyl oxygen and cationic hydroxyl group. The third band which appeared at about 1640~1660 was attributed to induced >C=C< double bond due to the strong carbonyl interaction. This was supported by the interlamellar spacings obtained by X-ray diffractometry.

• Korean Parent-Child Health Journal
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• v.1
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• pp.56-74
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• 1998

The language of the newborn, like that of adults, is one of gesture, posture, and expression(Lewis, 1980). Helping parents understand and respond to their newborn's cues will make caring for their baby more enjoyable and may well provide the foundation for a communicative bond that will last lifetime. Infant state provides a dynamic pattern reflecting the full behavioral repertoire of the healthy infant(Brazelton, 1973, 1984). States are organized in a predictable emporal sequence and provide a basic classification of conditions that occur over and over again(Wolff, 1987). They are recognized by characteristic behavioral patterns, physiological changes, and infants' level of responsiveness. Most inportantly, however, states provide caregivers a framework for observing and understanding infants' behavior. When parents know how to determine whether their infant is sleep, awake, or drowsy, and they know the implications, recognition of states has for both the infant's behavior and for their caregiving, then a lot of hings about taking care of a newborn become much easier and more rewarding. Most parents have the skills and desire to do what is best for their infant. The skills 7373parents bring to the interaction are: the ability to read their infant's cues: to stimulate the baby through touch, movement, talking, and looking at: and to respond in a contingent manner to the infant's signals. Among the crucial skills infants bring to the interaction are perceptual abilities: hearing and seeing, the capacity to look at another for a period of time, the ability to smile, be consoled, adapt their body to holding or movement, and be regular and predictable in responding. Research demonstrates that the absence of these skills by either partner adversely affects parent-infant interaction and later development. Observing early parent-infant interactions during the hospital stay is important in order to identify parent-infant pairs in need of continued monitoring(Barnard, et al., 1989).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1431-1434
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• 2014

The thermal barrier coating (TBC) applied to a gas turbine can be damaged by repeated thermal fatigue during operation, so an evaluation of its durability is needed. Thermally grown oxide (TGO) is generated inside the TBC in a high-temperature environment. The growth of TGO is known to be the main cause of damage to the TBC. Therefore, the durability of TBC should be evaluated according to the growth of TGO. In this research, Kim et al.'s work on the growth of TGO with aging was used as a basis for finite element analysis. The relationship between stress and aging was derived from the finite element analysis results. The durability of the TBC with aging was evaluated through a comparison between the results of the finite element analysis and a bond strength test.

• Journal of Surface Science and Engineering
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• v.32 no.2
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• pp.144-156
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• 1999

Thermal Barrier Coating with Functional Gradient Materials (FGM-TBC) can play an important role to protect the parts from harmful environments in high temperatures such as oxidation, corrosion, and wear and to improve the efficiency of aircraft engine by lowering the surface temperature on turbine blade. FGM-TBC can increase the life spans of product and improve the operating properties. Therfore, in this study the evaluations of mechanical and thermal properties of FGM-TBC such as fatigue, oxidation and wear-resistance at high temperatures have been conducted. The samples of both the TBC with 2, 3, 5 layers (YSZ/NiCrAlY) to be produced by Air Plasma Spray method (APS) and the bulk TBC with 6 layers to be produced by Plasma Assisted Sintering method (PAS) were used. Furthermore, residual stress, bond strength, and thermal conductivity were evaluated. The average thickness of the APS was 500$\mu\textrm{m}$ to 600$\mu\textrm{m}$ and the average thickness of the PAS was 3mm. The hardness number of the top layer of APS was 750 Hv to 810Hv and that of PAS was 950 Hv to 1440Hv. The $ZrO_2$ coating layer of APS was composed of tetragonal structure after spraying as the result of XRD analysis. As shown in the results of the high temperature wear test, the 3 layer coating of APS had the best wear resistance at $800^{\circ}C$ and the 5 layer coating of APS had the best wear resistance at $600^{\circ}C$. But, these coatings had the tendency of the low-temperature softening at $300^{\circ}C$. The main mechanism of wear was the adhesive wear and the friction coefficient of coatings was increased as increasing the test temperatures. A s results of thermal conductivity test, the ${\Delta}T$ of the APS coating was increased as number of layer and the range of thermal conductivity of the PAS was $800^{\circ}C$ to $1000^{\circ}C$.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.54-56
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• 2005

Ultrasonic soldering using of Si-wafer to FR-4 PCB atroom temperature was investigated. Sn3.5Ag foil rolled $100{\mu}m$ was used for solder. The UBM of Si-die was Cu/ Ni/ Al from top to bottom and its thickness was $0.4{\mu}m$, $0.4{\mu}m$, $0.3{\mu}m$ respectively. Pad on FR-4 PCB comprised of Au/ Ni/ Cu from top to bottom and its thickness was $0.05{\mu}m$, $5{\mu}m$, $18{\mu}m$ respectively. The ultrasonic soldering time was changed from 0.5sec to 3.0sec and its power 1400W. As experimental result, reliable bond joint by ultrasonic at room temperature was obtained. The shear strength increased with soldering time up to 2.5 sec. That means at 2.5sec, the shear strength showed maximum rate of 65.23N. The strength decreased to 33.90N at 3.0 sec because the cracks generated along the intermetallic compound between Si-wafer and Sn-3.5mass%Ag solder. intermetallic compound produced by ultrasonic between the solder and the Si-die was $(Cu, Ni)_{6}Sn_{5}$ and the intermetallic compound between solder and pad on FR-4 was $(Ni, Cu)_{3}Sn_{4}$.

• ETRI Journal
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• v.31 no.6
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• pp.660-666
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• 2009

We investigate the effects of interfacial dielectric layers (IDLs) on the electrical properties of top-gate In-Ga-Zn-oxide (IGZO) thin film transistors (TFTs) fabricated at low temperatures below $200^{\circ}C$, using a target composition of In:Ga:Zn = 2:1:2 (atomic ratio). Using four types of TFT structures combined with such dielectric materials as $Si_3N_4$ and $Al_2O_3$, the electrical properties are analyzed. After post-annealing at $200^{\circ}C$ for 1 hour in an $O_2$ ambient, the sub-threshold swing is improved in all TFT types, which indicates a reduction of the interfacial trap sites. During negative-bias stress tests on TFTs with a $Si_3N_4$ IDL, the degradation sources are closely related to unstable bond states, such as Si-based broken bonds and hydrogen-based bonds. From constant-current stress tests of $I_d$ = 3 ${\mu}A$, an IGZO-TFT with heat-treated $Si_3N_4$ IDL shows a good stability performance, which is attributed to the compensation effect of the original charge-injection and electron-trapping behavior.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.3
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• pp.431-437
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• 2000

Traumatic intrusive luxation, an occurrence common in the primary dentition but one that occurs rarely in the permanent dentition, has a poor prognosis. There have been many treatment approaches such as allowing the tooth to reerupt spontaneously, surgical repositioning and immediate luxation, surgical luxation, and orthodontic repositioning; but all have their own drawbacks. Meanwhile, Turley et al. (1987) have proposed surgical and orthodontic combination therapy to treat intrusion. Surgical and orthodontic combination therapy means to apply the orthodontic traction force immediately after surgical luxation. If ankylosis occurs, orthodontic force may be applied after re-luxation repeatedly. But in cases of complete intrusive luxation, it would be not feasible to bond an orthodontic button or bracket on the tooth directly. Thus, in this case, traction of the tooth was attempted after surgically repositioning it close to the probable original socket site to promote better healing.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.5
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• pp.185-190
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• 2002

Capacitor material utilized in the downsizing passive devices and dynamic random access memory(DRAM) requires the physical and electrical properties at given area such as capacitor thickness reduction, relative dielectric constant increase, low leakage current and thermal stability. Common capacitor materials, $SiO_2$, $Si_3N_4$, $SiO_2$/$Si_3N_4$,TaN and et al., used until recently have reached their physical limits in their application to several hundred angstrom scale capacitor. $Ta_2O_{5}$ is known to be a good alternative to the existing materials for the capacitor application because of its high dielectric constant (25 ~35), low leakage current and high breakdown strength. Despite the numerous investigations of $Ta_2O_{5}$ material, there have little been established the clear understanding of the annealing effect on capacitance characteristic and conduction mechanism, design and fabrication for $Ta_2O_{5}$ film capacitor. This study presents the structure-property relationship of reactive-sputtered $Ta_2O_{5}$ MIM capacitor structure processed by annealing in a vacuum. X-ray diffraction patterns skewed the existence of amorphous phase in as-deposited condition and the formation of preferentially oriented-$Ta_2O_{5}$ in 670, $700^{\circ}C$ annealing. On 670, $700^{\circ}C$ annealing under the vacuum, the leakage current decrease and the enhanced temperature-capacitance characteristic stability. and the leakage current behavior is stable irrespective of applied electric field. The results states that keeping $Ta_2O_{5}$ annealed at vacuum gives rise to improvement of electrical characteristics in the capacitor by reducing oxygen-vacancy and the broken bond between Ta and O.