• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.4 s.117
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• pp.17-23
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• 2006

Paper has fibers and fines network structure and it is strongly affected by interface bond-ing between fibers. Paper structural properties can be determined depending on the inter-fiber bonding. Fines play an important role in Campbell and consolidation effect through wet pressing and drying operations. The fines are essential for the formation of bonds between fibers and for the improvement of strength properties of papers. Since the fines are components of the pulp, there are always two factors to be considered: the quality and quantity of the fines. The quality of fines might be a potential variable to give a more accurate picture of the papermaking potential of the pulp. The object of this study is to investigate the effect of different types of pulp fines on the properties of paper and to access the potential of fines for controlling the bulk of paper. Refined Sw-BKP, Hw-BKP and BCTMP fines were used to investigate the fines effect. Wet-web strength, breaking length, scattering coefficient, and hydrodynamic specific volume, and drying shrinkage were measured. According to the results, chemical and morphological compositions of fines do not strongly affect to wet-web forming by their similar Campbell effect, but strongly affect to drying operation which forms hydrogen bonding among fiber-fines-fiber matrixes. Paper bulk should be controlled by the extent of hydrogen bonding between fibers during drying operation.

• Journal of Welding and Joining
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• v.22 no.2
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• pp.38-45
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• 2004

Ultrasonic signals transmitted through adhesively bonded plates were used to evaluate parameters related to attenuation and frequency in the adhesively bonded joint. The kinds of bonding materials with a different bonding thickness of constant pressure were used. And ultrasonic diagnosis was evaluated by p-wave sensor of 10MHz. FFT has been performed to determine bond-layer parameters such as effective thickness and frequency for adhesively bonded joint of A16061 plates in comparison with measured to theoretical ratios. When variable thickness exists, the ultrasonic spectrum was changed the frequency wave. The more materials thickness and the higher the frequency, the larger shift was observed. Measured ratios for cases of bond thickness and variety bonding materials are then used to determine bond parameters. The results show that the technique can be applied to the characterization of adhesively bonded joint.

• Journal of the Korean Magnetic Resonance Society
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• v.12 no.1
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• pp.51-59
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• 2008

Convection effect in liquids has been one of the main targets to be overcome in pulsed-field-gradient NMR measurements of self-diffusion coefficients since the temperature gradient along the sample tube generated by the heating and/or cooling process causes the effect, resulting in additional diffusion. It is known that the capillary is the most appropriate tube type for diffusion experiments at variable temperatures since the narrower tube suppresses convection effectively. For evaluating the properties of hydrogen bonding, diffusion coefficients of the $K^+$-complexed and free valinomycin in a micro tube have been determined at various temperatures. From the analysis of the obtained diffusion coefficient values, we could conclude that the intramolecular hydrogen bonding in both of the $K^+$ complexed and free valinomycin in a non-polar solvent is preserved over the observed temperature range, and the temperature dependence of hydrogen bonding is more pronounced in free valinomycin. It is also thought that there is no big change in the radius of the $K^+$-complexed as temperature is varied, and the ratio of overall radius, $r_{complex}/r_{free}$ is slightly decreased as temperature rises.

• Korean Journal of Optics and Photonics
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• v.7 no.1
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• pp.72-76
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• 1996

The magnetostrictive characteristics of three different forms of magnetostrictive transducers made of 2605SC and 2826MB metallic glasses were measured. In both cases, the two-end-point bonding configuration exhibited the best characteristics. With the two-end-point bonding we measured the effective magnetostrictive coefficient $C_{eff}$ of $1.2{\times}^{-5}Oe^{-2}$, the saturation magnetostriction ${\lambda}_s$ of $7.4{\times}10^{-4}$ and the minimum detectable magnetic field $H_{min}$ of $1.6{\times}10^{-7}Oe$/ √Hz for the 2605SC metallic glass ribbon. Also for the 2826MB metallic glass ribbon, Ceff and ${\lambda}_s$ were $7.6{\times}10^{-6}Oe^{-2}$ and $3.4{\times}10^{-4}$ respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.49-54
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• 1993

This paper discusses the reliability of solder joints of electronic devices on printed circuit board. Solder application is usually done by screen printing method for the bonding between outer leads of devices and thick film(Ag/Pd) pattern on Hybrid IC as wel1 as Cu lands on PCB. As result of thermal stresses generated at the solder joints due to the differences of thermal expansion coefficients between packge body and PCB, Micro cracking often occurs due to thermal fatigue failure at solder joints. The initiation and the propagate of solder joint crack depends on the environmental conditions, such as storage temperature and thermal cycling. The principal mechanisms of the cracking pheno- mana are the formation of kirkendal void caused by the differences in diffusion rate of materials, ant the thermal fatigue effect due to the differences of thermal expansion coefficient between package body and PCB. Finally, This paper experimentally shows a way to supress solder joints cracks by using low-${\alpha}$ PCB and the packages with thin lead frame, and investigates the phenomena of diffusion near the bonding interfaces.

• Journal of the Korean Ceramic Society
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• v.43 no.9 s.292
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• pp.515-518
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• 2006

The microstructure of $ZrO_2$ toughened $Al_2O_3$ ceramics was carefully controlled so as to obtain dense and fine-grained ceramics, thereby improving the properties and reliability of the ceramics for capillary applications in semiconductor bonding technology. $Al_2O_3-ZrO_2(Y_2O_3)$ composite was produced via Ceramic Injection Molding (CIM) technology, followed by Sinter-HIP process. Room temperature strength, hardness, Young's modulus, thermal expansion coefficient and toughness were determined, as well as surface strengthening induced by the fine grained homogenous microstructure and the thermal treatment. The changes in alumina/zirconia grain size, sintering condition and HIP treatment were found to be correlated.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.41-62
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• 2003

In this research, we manufactured the paste opaque porcelains using Propylene Glycol (PG) and Buthylene Glycol (BG) as a solvent, and compared the composition of solvents, the coefficient of thermal expansion, the particle size distribution, the viscosity and bonding strength to metal, and the tone with those of the commercial products(Duceram Plus, Duceram GmbH; VMK 95, Vita Co.; Noritake EX-3, Noritake Co.)used in the clinical field. The results of the research were as follows: 1. The result of solvent analysis indicated that the solvents included in the paste opaque porcelains of the control group were mainly composed of Glycols. 2. From the Coefficient of thermal expansion measurement, we drew out the following results; testing group: $14.0\times10^{-6}/^{\circ}C$, Duceram Plus: $13.9\times10^{-6}/^{\circ}C$, VMK 95: $14.3\times10^{-6}/^{\circ}C$, and Noritake EX-3: $13.3\times10^{-6}/^{\circ}C$. 3. Seen from the result of particle size distribution measurement, the experimental group was similar to the control group in 1$\mu m$ below, but the experimental group marked the highest distribution of 61% in the case of between 1$\mu m$ and 5$\mu m$. Between 5$\mu m$ and 10$\mu m$, they showed relatively similar distribution, and Noritake EX-3 was turned out the highest distribution of 29% in 10$\mu m$ above. 4. From the result of viscosity measurement, Duceram plus showed the highest viscosity throughout all the measurements followed by Noritake Ex-3, experimental group and VMK 95 in decreasing order. 5. The result of bonding strength measurement was EX 35.53 $\beta\acute{A}$, DU 40.88 $\beta\acute{A}$, VM 39.43 $\beta\acute{A}$, and NO 35.39 $\beta\acute{A}$, and no significant difference was found between the experimental group and the control groups(P>0.05). 6. The measurement of the tone indicated that the $L^*$ value of the experimental group was 86.89 0.63 in average, which is higher than the control group in its brightness. In the case of the $a^*$ value, Duceram Plus, VMK 95 and EX-3 showed positive value, whereas the testing group was turned out negative value. In $b^*$ value, Duceram Plus proved the highest. From the results of this research, the paste opaque porcelains using Propylene Glycol (PG) and Buthylene Glycol (BG) as a solvent did not make differences from the commercial products that are actually used in the clinical fields. Therefore, it is possible to utilize Propylene Glycol (PG) and Buthylene Glycol (BG) for the paste opaque porcelains of P.F.M crown. It is also recommended that further researches concerning the compositions and forms of powder, the types of organic solvent components and the ratio of mixture proceeded in order to improve the level of productivity in the future.

• Journal of the Korean Wood Science and Technology
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• v.51 no.6
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• pp.470-480
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• 2023

This study aimed to develop a sound-absorbing composite using sugarcane bagasse (SB) and coffee silver skin (CS) as raw materials. The composite boards were manufactured by bonding the fibers with Melamine Urea-Formaldehyde adhesive, ensuring a consistent thickness of 30 mm. Various densities were employed, namely 380, 450, and 520 kg/m³. The samples were fabricated with different fiber ratios, including SB100%, SB75% with CS25%, and SB50% with CS50%. The sound absorption coefficient (SAC) and noise reduction coefficient (NRC) were measured using the impedance tube method within a frequency range of 63-6,300 Hz. The experimental results revealed that the mixing ratio of CS exerted a notable influence on enhancing the SAC, while the density of the composite board exhibited a significant impact on increasing both the SAC and NRC. Among the densities tested, the optimal value was observed at 520 kg/m³, yielding a SAC value of 0.65 at a frequency of 1,000 Hz and an NRC value of 0.55 for the SB50-CS50 composite plate. These findings underscore the importance of considering the CS mixing ratio and composite board density when aiming to optimize sound absorption properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.701-705
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• 2007

The incorporation of N in a-C film is able to improve the friction coefficient and the adhesion to various substrates. In this study, a-C:N films were deposited on Si and steel substrates by closed-field unbalanced magnetron (CFUBM) sputtering system in $Ar/N_2$ plasma. The lubricant characteristics was investigated for a-C:N deposited with total working pressure from 4 to 7 mTorr. We obtained high hardness up to 24GPa, friction coefficient lower than 0.1 and the smooth surface of having the extremely low roughness (0.16 nm). The physcial properties of a-C:N thin film are related to the increase of cross-linked $sp^2$ bonding clusters in the film. However, the decrease of hardness, elastic modulus and the increase of surface roughness, friction coefficient with the increase of $N_2$ partial pressrue might be due to the effect of energetic ions as a result of the increase of ion bombardment with the increase of ion density in the plasma.

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.96-100
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• 1997

Hydrogenated amorphous carbon films were deposited on silicon substrates by using an RF PECVD. The hydrogen/methane ratio was varied from 50% to 88% to study the effect of hytdrogen in the film on the tribological properties. The friction and wear behaviors of the deposited films were investigated by ball-on-disk type wear tester. FT-IR spectra were used to characterize the structure of the films. Tribological properties of carbon films were correlated with their structure such as ratio of "polymer-like" stretching type and that of sp2 bonding. The result showed that the annealing caused a decrease in the amount of wear of contacted $Si_3N_4$ balls and a increase in the coefficient of friction. Possible explanation for annealing effect was discussed by the hydrogen desorption.esorption.