• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.304-304
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• 2007

고주파 모률에서 사용되는 기판소재는 저유전율과 낮은 loss 특성을 요구함으로 지속적인 연구를 필요로 한다. 지금까지의 ceramic/glass composite 에서 주로 사용된 ceramic filler는 Al2O3로 낮은 유전률을 구현에 한계가 있었다. Cordierite는 낮은 유전율 (${\varepsilon}_r$ < 4)을 나타내는 filler로서 그 가능성이 높지만 아직까지 보고된 결과들이 미흡한 실정이다. 따라서 본 연구에서는 cordierite filler와 SiO2-B2O3-Al2O3-RO (R : Zn, Sr, Ba, Ca)계의 glass를 혼합하여 LTCC용 기판소재로서의 가능성을 확인하고자 저온 동시소성이 가능한 소결온도인 $850^{\circ}C{\sim}1.000^{\circ}C$ 사이에서 소재의 소결실험을 진행하였다. 소결온도에 따른 상변화, 유전특성을 확인한 결과 filler로 사용된 cordierite상만이 관찰 되었으며 소결조건에 따라 5.0~5.5의 낮은 유전율과 1.000~1,500의 Q를 나타내는 것을 확인 하였다.

• Elastomers and Composites
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• v.56 no.4
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• pp.234-242
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• 2021

The demand for truck bus radial (TBR) tires with enhanced fuel efficiency and wear resistance have grown in recent years. In addition, as the issue of particulate matter and air pollution increases, efforts are being made to reduce the generation of particulate matter. In this study, the properties of epoxidized natural rubber (ENR) containing a silica-friendly functional group were evaluated by considering it as a base rubber and varying the silica ratio in this binary filler system. The results showed that the wear resistance of the NR/BR blend compound decreased as the silica ratio increased. In contrast, the ENR/BR blend compound exhibited an increase in wear resistance as the silica ratio was increased. In particular, the ENR-50/BR blend compound showed the best wear resistance due to the presence of several epoxide groups. Furthermore, we observed that for tan 𝛿 at 60℃, higher epoxide content resulted in the higher T_g of the rubber, indicating a higher tan 𝛿 at 60℃. On the other hand, it was confirmed that increasing the silica ratio decreased the value of tan 𝛿 at 60℃ in all compounds. In addition, we measured the amount of wear particulate matters generated from the compound wear. These measurements confirmed that in the binary filler system, regardless of the filler type, the quantity of the generated wear particulate matters as the filler-rubber interaction increased. In conclusion, the silica filled ENR/BR blend compound exhibited the lowest generation of wear particulate matters.

• Journal of the Korean Society of Safety
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• v.19 no.4 s.68
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• pp.80-85
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• 2004

Electromagnetic interference(EMI) shielding characteristics of composite filled with Cu flake and carbon brush powder as hybrid conductive filler and EAF slag have been studied. The coaxial transmission line method of ASTM D4935-99 was used to measure the EMI Shielding effectiveness of composites as formulation in frequency rage $100\~1,000MHz$ The SE also increases with the increase in flier loading. The hybrid filler filled composites show higher SE compared to that of only Cu flake. The correlation between SE and conductivity of the various composites is also discussed. The results indicate that the composites having higher filler loading$({\geq}40wt.\%)$ can be used for the purpose of safety materials to protect hazardous electromagnetic interference.

• International Journal of Ocean System Engineering
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• v.2 no.4
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• pp.209-213
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• 2012

Recently, the fuel using in the diesel engines of marine ships has been changed to a low quality of heavy oil because of the steady increase in the price of oil. Therefore, the wear and corrosion in all parts of the engine such as the cylinder liner, piston crown, and spindle and seat ring of exhaust valves has correspondingly increased. The repair welding of a piston crown is a unique method for prolonging its lifetime from an economic point of view. In this case, filler metals with a high corrosion and wear resistance are mainly being used for repair welding. However, often at a job site on a ship, a piston crown is actually welded with mild filler metals. Therefore, in this study, mild filler metals such as CSF350H, E8000B2, and 435 were welded to SS401 steel as the base metal, and the corrosion properties of the weld metals with and without post weld heat treatment were investigated using some electrochemical methods in a 0.1% $H_2SO_4$ solution. The weld metal welded with CSF350H filler metal exhibited the best corrosion resistance among these filler metals, irrespective of the heat treatment. However, the weld metal zones of the E8000B2 and 435 filler metals exhibited better and worse corrosion resistance with the heat treatment, respectively. As a result, it is suggested that in the case of repair welding with CSF350H and 435 filler metals, no heat treatment is advisable, while heat treatment is desirable if E8000B2filler metal is used with repair welding.

• Elastomers and Composites
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• v.56 no.1
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• pp.20-31
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• 2021

There is an increasing demand for the rolling resistance reduction in truck bus radial (TBR) tires in the tire industry. In TBR tires, natural rubber is used as a base polymer to prevent wear and satisfy required physical properties (cut and chip). A binary filler system (silica and carbon black) is used to balance the durability of the tire and rolling resistance performance. In this study, natural rubber (NR) compounds applied with a binary filler system were manufactured at different cure temperatures for vulcanizate structure analysis. The vulcanizate structures were categorized into carbon black bound rubber, silica silane rubber network, and chemical crosslink density by sulfur. Regardless of the cure temperature, the cross-link density per unit content of carbon black had a greater effect on the properties than silica due to affinity with NR. The relationship analysis between the mechanical, viscoelastic properties with vulcanizate structure could be a guideline for manufacturing practical TBR compounds.

• Korean Journal of Materials Research
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• v.17 no.3
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• pp.179-183
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• 2007

A plate heat exchanger (PHE) normally uses vacuum brazing technology for connecting plates and fins. However, the reliability of high temperature brazing, especially with nickel-based filler metals containing boron the formation of brittle intermetallic compounds (IMCs) in brazed joints is of major concern. since they considerably degrade the mechanical properties. This research was examined the vacuum brazing of commercially SUS304 stainless steel with BNi-2 (Ni-Cr-B-Si) filler metal, and discussed to determine the influence of brazing temperatures on the microstructure and mechanical strength of brazed joints. In the metallographic analysis it is observed that considerable large area of Cr-B intermetallic compound phases at the brazing layer and the brazing tensile strength is related to removal of this brittle phase greatly. The mechanical properties of brazing layer could be stabilized through increasing the brazing temperature over $100^{\circ}C$ more than melting temperature of filler metals, and diffusing enough the brittle intermetallic compound formed in the brazing layer to the base metal.

• Korean Journal of Materials Research
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• v.17 no.3
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• pp.142-146
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• 2007

Vacuum brazing method has been coming to an important process as one of the new fabricating techniques of metals and alloys. In this study, a vacuum brazing of SUS304 stainless steel with BNi-2 filler metal was carried out in $1{\times}10^{4}$ Torr of vacuum atmosphere. The formation of brittle intermetallic compounds in brazed joints between SUS304 stainless steel and BNi-2 filler metal is a major concern, since they considerably degrade the mechanical properties of joints. To obtain enough stable joining strength, it is necessary to understand the unique properties of brazing process with Ni-based filler metals containing boron. So, in this research we investigated the performance of SUS304/BNi-2 brazed system and the brazed joint properties were evaluated at room temperature by using tensile test. Metallurgical and fractographic analysis were used to characterize the microstructure, the mechanisms of brazing, and joint failure modes.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.226-234
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• 2009

The purpose of this study was to investigate the melting phenomenon of filler wire in detail and to obtain the precise temperature distribution of filler wire during GTA welding under the ultra-high welding speed condition in order to develop the ultra-high-speed GTA welding process with the pulse-heated hot-wire system by using three kinds of materials. The melting phenomenon of filler wire was observed using a high-speed camera and the temperature distribution of filler wire was measured using a radiation thermometer. From the above result, the adequate welding conditions of each material to make the GTA welding process with the ultra-high welding speed could be obtained. The ultra-high-speed GTA welding process needed the adequate wire current in order to obtain the adequate temperature distribution and the adequate melting position of filler wire. Moreover, the temperature distributions of three kinds of filler wire could be estimated by using the proposed simple estimation method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.93-97
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• 2007

In this paper a new clock generation scheme for TDM-CDM converter in the Gap Filler for satellite DMB systems has been proposed. The scheme uses the frame sync signal from the Ku band TDM receiver to lock the VCXO which provides the system clock for the TDM-CDM converter. The locking algorithm can be easily implemented in the FPGA, so that no separate circuitry is needed as in conventional PLL. With a stable OCXO, The scheme can be used to generate the reference clock to the local oscillator for RF parts.

• Elastomers and Composites
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• v.30 no.3
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• pp.218-228
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• 1995

To make filler loaded conducting rubber which has excellent electronical and physical properties, CR and NBR were mixed with barium ferrite(BaO.6Fe2O3). From the result of this study, vulcanization characteristics shows that curve is upgraded as the filler concentration increases and CR has higher torque than NBR. In physical properties, elongation being higher, modulus comes to decrease. Tear strength gradually decrease after showing the maximum point when is in the 100phr in CR. Resilience is not good to cause the increase in filler concentration. In electrical properties, conductivity becomes low when filler concentration increase. The increase of voltage makes a conductivity grown, but the rate change is weak. The influence of temperature hardly changes on increasing temperature. The morphology and the dispersion of a conductivity filler in vulcanizates through SEM were good. The more filler concentration increases, the shorter the particle interval is.