• 대한환경공학회지
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• 제35권6호
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• pp.415-421
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• 2013

활성탄소섬유(Activated carbon fiber, ACF)의 비표면적을 향상시키는 대표적인 방법은 알칼리금속을 이용한 화학적 활성화(Chemical activation, CA)와 산화제를 이용한 표면처리(Surface treatment, ST)방법이 있다. 알칼리금속을 이용한 CA 공정은 열처리 과정에서 알칼리금속의 화학반응에 의하여 미세기공이 발달되며, ST 공정은 산화제의 산화력에 의하여 표면의 미세기공을 발달시킨다. 본 연구에서는 대표적인 표면개질 방법인 CA 공정의 효과를 증대하기 위하여 전처리로 ST 공정을 수행하였으며, ST 공정 유무에 따라 CA된 ACF의 특성변화를 관찰하였다. ST 및 CA 유무에 따른 ACF 특성을 조사하기 위하여 무게변화, FT-IR, TGA, 원소분석을 수행하였으며, 대표적인 VOC물질인 톨루엔을 이용하여 흡착특성을 평가하였다. 실험결과 초기 raw ACF의 비표면적과 톨루엔 흡착량은 각각 1,483 $m^2/g$, 0.22 $g_{-Tol.}/g_{-ACF}$였으며, CA 처리시 1,998 $m^2/g$, 0.27 $g_{-Tol.}/g_{-ACF}$로 증가하였고, ST된 ACF를 CA 처리한 경우 2,743 $m^2/g$, 0.37 $g_{-Tol.}/g_{-ACF}$로 증가하였다. 본 연구를 통하여 ST 및 CA 결합공정을 통한 ACF의 표면특성을 증가를 확인하였다.

• 대한치과기공학회지
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• 제42권3호
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• pp.213-219
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• 2020

Purpose: This study aimed to identify the impact of physical surface roughing with a polishing tool onto the pre-sintering yttria-stabilized tetragonal zirconia polycrystals (TZP) core and liner treatment for chemical bonding on the bond strength of TZP core and veneering ceramic. Methods: Overall, 80 specimens were classified into two groups (non-liner, NL; and usingliner, UL ) depending on the use of liner, and these two groups were then subclassified into four groups depending on the polishing tool used. (1) Non-liner groups: NS, non-liner+stone point; NC, non-liner+carbide bur; NP, non-liner+paper cone point; NT, non-liner+silicon point. (2) Using-liner groups: US, using-liner+stone point; UC, using-liner+carbide bur; UP, usingliner+paper cone point; UT, using-liner+silicon point. The pre-sintering surface roughing values and shapes were observed, and after burning up the veneering ceramic, the shear bond strength was measured using a universal testing machine. For significance testing, a one-way analysis of variance and Tukey's multiple comparison test were conducted. An optical microscope was used to observe the fracture plane, and the following results were obtained. Results: Surface roughness NP (4.09±0.51 ㎛) represented a higher value than other groups (p<0.001). In shear bond strength, NS (35.21±1.44 MPa) of the NL group showed the highest bond strength (p<0.001). The UL group did not show a statistically significant difference between groups (p=0.612). Conclusion: Our study findings reveal that the bond strength of TZP core and veneering ceramic was improved by pre-sintering physical surface treatment than by chemical bonding with liner surface treatment.

• 분석과학
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• 제19권2호
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• pp.121-130
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• 2006

In this study, silver pre-treated activated carbons are transformed using sulfuric acid. From the results of adsorption, each isotherm shows a distinct knee band, which is characteristic of microporous adsorbents with capillary condensation in micropores. In order to reveal the causes of the differences in adsorption capacity and specific surface area after the samples were washed with various strengths of sulfuric acid, surface morphology and external pore structure were investigated by SEM. X-ray diffraction patterns indicated that Ag-activated carbons show better performance for silver and silver compounds removal by post-treatment with acid. The FT-IR spectra of silver-activated carbon samples show that the acid post-treatment was consequently associated with the removal of silver with an increased surface functional group containing oxygen of the activated carbon. The type and quality of oxygen groups are determined on the method proposed by Boehm. For the chemical composition microanalysis of silver-activated carbons transformed by post-treatment with sulfuric acid, samples were analyzed by EDX.

• Membrane and Water Treatment
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• 제11권2호
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• pp.151-158
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• 2020

ACF preparation from different materials has been attached with great attention during these years. This study was conducted to prepare activated carbon fiber (ACF) from luffa through the processes i.e pre-treatment, pre-oxidation and carbonization activation. Besides, this study also characterizes the ACF and its effect, i.e effect of pre-oxidation time and temperature also activation time and temperature on the compressive strength of ACF were investigated. The results from SEM, BET, FTIR and XRD show that the ACF is very efficient. The products under the optimum conditions had a specific surface area of 478.441 m2 /g with an average pore diameter of 3.783nm, and a pore volume of 0.193 cm3 /g. The surface of the luffa fiber is degummed and exposed, which is beneficial to the subsequent process and the increase of product properties. The compressive strength of HP-ACF was prepared under the optimum conditions, which can reach 0.2461 MPa. ACF is rich in micro-pores and has a good application prospect in the field of environmental protection.

• 패션비즈니스
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• 제11권2호
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• pp.92-101
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• 2007

This research was carried out following the preceding research on natural cellulose fabrics dyed with extract of fresh african marigold petals. Dyeability on fabrics was tested by dyeing with wool and silk which are natural protein fibers. Dyeing tests were carried out under different pH of the dye solution and mordants, examining the changes in the surface color, K/S value, and maximum absorption wavelength. The probability of improving dyeability was investigated by pre-mordanting with pre-treated chitosan. Wool fabrics showed color tone of medium or less saturation and brightness, in dark yellow color series. An orange color of high saturation was only obtained by tin mordanting. Wool showed higher K/S value than cellulose fibers. In summary, marigold dye has more affinity for protein fibers. It showed better dye effect in wool than silk. The chitosan pre-treatment and pre-mordanting lowered the K/S value of wool, which showed that chitosan pre-treatment does not improve dye uptake. However, different from the dyeing carried out by pre-mordanting without pre-treatment with chitosan, more diversified colors could be obtained by mordants. Therefore, for the dyeing natural protein fibers with marigold extract, post-mordanting does not require chitosan pre-treatment. However, pre-mordanting with chitosan pre-treatment could implement diverse colors. Considering its dyeing behaviors which are similar in both natural cellulose and protein fibers, african marigold extracts can be evaluated as a stable and highly practical dye.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3313-3315
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• 1999

Si direct bonding(SDB) technology is very attractive for both Si-on-insulator(SOI) electric devices and MEMS applications because of its stress free structure and stability. This paper presents on pre-bonding according to HF pre-treatment conditions in Si wafer direct bonding. The characteristics of bonded sample were measured under different bonding conditions of HF concentration, and applied pressure. The bonding strength was evaluated by tensile strength method. The bonded interface and the void were analyzed by using SEM and IR camera respectively. A bond characteristic on the interface was analyzed by using IT- IR. Si-F bonds on Si surface after HF pre-treatment are replaced by Si-OH during a DI water rinse. Consequently, hydrophobic wafer was bonded by hydrogen bonding of Si $OH{\cdots}(HOH{\cdots}HOH{\cdots}HOH){\cdots}OH-Si$. The bond strength depends on the HF pre-treatment condition before pre- bonding (Min:$2.4kgf/crn^2{\sim}Max:14.9kgf/crn^2$)

• Restorative Dentistry and Endodontics
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• 제39권4호
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• pp.303-309
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• 2014

Objectives: Hydrogen peroxide ($H_2O_2$) surface treatment of fiber posts has been reported to increase bond strength of fiber posts to resin cements. However, residual oxygen radicals might jeopardize the bonding procedure. This study examined the effect of three antioxidant agents on the bond strength of fiber posts to conventional and self-adhesive resin cements. Materials and Methods: Post spaces were prepared in forty human maxillary second premolars. Posts were divided into five groups of 8 each: G1 (control), no pre-treatment; G2, 10% $H_2O_2$ pre-treatment; G3, G4 and G5. After $H_2O_2$ application, Hesperidin (HES), Sodium Ascorbate (SA) or Rosmarinic acid (RA) was applied on each group respectively. In each group four posts were cemented with Duo-Link conventional resin cement and the others with self-adhesive BisCem cement. Push-out test was performed and data were analyzed using 2-way ANOVA and tukey's post-hoc test (${\alpha}=0.05$). Results: There was a statistically significant interaction between the cement type and post surface treatment on push-out bond strength of fiber posts (p < 0.001, F = 16). Also it was shown that different posts' surface treatments significantly affect the push-out bond strength of fiber posts (p = 0.001). $H_2O_2$ treated posts (G2) and control posts (G1) cemented with Duo-link showed the highest ($15.96{\pm}5.07MPa$) and lowest bond strengths ($6.79{\pm}3.94$) respectively. Conclusions: It was concluded that $H_2O_2$ surface treatment might enhance the bond strength of fiber posts cemented with conventional resin cements. The effect of antioxidants as post's surface treatment agents depends on the characteristics of resin cements used for bonding procedure.

• Nano
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• 제13권10호
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• pp.1850120.1-1850120.9
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• 2018

Two-dimensional poly(dimethylsiloxane) (PDMS) films with wavy patterns were studied in order to investigate reversible and irreversible wetting effects. Pre-strained, surface oxidized layers of PDMS were used to form relieved wavy geometries, on which hydrophobic functionalization was carried out in order to produce irreversible wetting effects. Wavy-patterned PDMS films showed time-dependent reversible wetting effects. The degree of surface wettability could be tuned by the choice of wavy groove geometries. And the groove geometries were controlled via $O_2$ plasma treatment and mechanical pre-straining. The pre-strained, buckled PDMS films were applied to the fabrication of hydrophobic polystyrene nano-patterns using colloidal self-assembly, where the colloids were arrayed in two-dimensional way. The wavy polystyrene films were found to be more hydrophobic relative to flat polystyrene films. The grooving methodology used in this study could be applied to enhancing the hydrophobicity of other types of polymeric thin films, eliminating the need for chemical treatment.

• 대한금속재료학회지
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• 제47권1호
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• pp.26-31
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• 2009

The effects of $Ar/O_2$ ion-beam pre-treatment conditions on the interfacial adhesion energy of sputterdeposited Cu thin film to FR-4 substrate were systematically investigated in order to understand the interfacial bonding mechanism for practical application to advanced chip-in-substrate package systems. Measured peel strength increases from $45.8{\pm}5.7g/mm$ to $61.3{\pm}2.4g/mm$ by $Ar/O_2$ ion-beam pre-treatment with anode voltage of 64 V. Interfacial bonding mechanism between sputter-deposited Cu film and FR-4 substrate seems to be dominated by chemical bonding effect rather than mechanical interlocking effect. It is found that chemical bonding intensity between carbon and oxygen at FR-4 surface increases due to $Ar/O_2$ ion-beam pretreatment, which seems to be related to the strong adhesion energy between sputter-deposited Cu film and FR-4 substrate.

• 한국의상디자인학회지
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• 제9권2호
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• pp.85-92
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• 2007

This study focused on bean-juice treatment method which have dyeing property to indigo, yellow soil, sappan wood, cochineal and also on the possibility of applying to mordanting. This is different from the active mordanting using chemicals. Natural mordants with development of dyeing are not harmful, also are the medicines for disease. Limestone and ash neutralize the acidic soil. bean-juice protein adhere to cellulose surface and change the physical properties of protein so that coloring of dye is better than before and film non-soluble in water is made. Therefore the color made from bean-juice process lasts after washing. This study try to show one of the ways to improve the current method using the heavy metal which can have bad effects for environment and human being. Bean-juice(raw bean, heated bean) treatment method can be the way to fix the natural dyeing problem of bad dyeing. Bean-juice had been treated under various condition with pre-treatment, post-treatment and raw bean, heated bean. Following results are obtained in this study. In the case of Indigo dyeing, pre-treatment of heated bean shows the biggest difference of color. In the case of yellow soil dyeing, pre-treatment of raw bean-juice shows the biggest gap of color. Pre-treatment of heated bean in sappan wood dyeing case and post-treatment of raw bean show bigger color difference than pre-treatment of raw bean. In cochineal dyeing, raw bean pre-treatment shows the biggest color difference.