• Korean Journal of Materials Research
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• v.12 no.6
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• pp.508-512
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• 2002

$2000{\AA}-SiO_2/Si(100)$ and $560{\AA}-Si_3N_4/Si(100)$ wafers, which are 10 cm in diameter, were directly bonded using a rapid thermal annealing method. We fixed the anneal time of 30 second and varied the anneal temperatures from 600 to $1200^{\circ}C$. The bond strength of bonded wafer pairs at given anneal temperature were evaluated by a razor blade crack opening method and a four-point bonding method, respectively. The results clearly slow that the four-point bending method is more suitable for evaluating the small bond strength of 80~430 mJ/$\m^2$ compared to the razor blade crack opening method, which shows no anneal temperature dependence in small bond strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.99-100
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• 2019

Water repellent and waterproofing agents fail to act work properly if cracks or detachment occurs outside. The method of making mortar was tested by classifying it into two methods: direct water-repellent put in concrete and water-repellent spray to sand method. It was found that the compressive strength was decreased as the amount of water repellent was increased. As a result of measuring the contact angle, all of the specimens were hydrophobic. The spray method showed greater water repellent effect than the direct mixing method.

• Transactions of Materials Processing
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• v.6 no.5
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• pp.435-445
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• 1997

In order to study the manufacturing possibility of connecting rod by direct quenching method, the difference between connecting rod by direct quenching and that by general heat treatment were investigated by observing microstructure, by measuring mechanical properties, by conducting fatigue testing, and by measuring the amount of tool wear in actual cutting. Connecting rod manufactured by direct quenching had better fatigue life than that by general heat treatment, which was due to homogeneous microstructure, and higher strength. The amount of cutting tool wear of connecting rod by direct quenching was higher than that by general heat treatment, which was due to low machinability and high toughness of tempered martensite microstructure. Therefore it will be added the study of heat treatment and cutting condition for manufacturing by direct quenching.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.79-82
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• 2008

It has been reported that destruction test by core collection is the most reliable of the structural concrete strength in present building construction field. But it causes low efficiency by damage and cutting in structure due to the core collection. It also has some problems in repairing. Additionally in case of strength test with management specimen, different environment compared to the structure environment cause problems about estimation precise structure strength. Therefore, it is required to develop structure direct strength test that has test values and credibility above the ones obtained by core specimen collection strength test and seasonal specimen test to suggest a reasonable and practical management method of structural concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1153-1163
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• 2013

Bonded concrete overlay is a favorable maintenance method since the material properties are similar to existing concrete pavements. In addition, bonded concrete overlay has advantage of structural performance based on being bonded together, both for the overlay layer and the existing pavement which perform as one monolithic layer. Therefore, it is important to have a suitable bond strength criteria for long term performance of bonded concrete overlay. This study aimed to investigate the affecting of bond strength on various bond characteristics, and to compare the bond strength between direct tensile test and indirect tensile test due to various conditions such as overlay materials, compressive and flexure strength of existing pavement, and deterioration status of existing pavement. As a result of this study, bond strength occurred by both of direct and indirect tensile test due to monotonic load is highly correlated such as coefficient of determination of 0.75 and P-value of 0.002. However, bond strength by indirect tensile test was relatively higher than bond strength by direct tensile test. It was known that correlation between direct and indirect tensile test was possible to use the characteristics analysis of bond fatigue behavior based on bond strength due to cyclic load which can simulate real field behavior of bonded concrete overlay.

• Computers and Concrete
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• v.29 no.6
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• pp.407-418
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• 2022

This paper numerically investigates the effect of changes in the mechanical properties (displacement, strain, and stress) of the ultra-high-performance concrete (UHPC) without rebar and the reinforced concrete (RC) using steel re-bars. This reinforced concrete is mostly used in the concrete bridge decks. A mixture of sand, gravel, cement, water, steel fiber, superplasticizer, and micro silica was used to fabricate UHPC specimens. The extended finite element method as used in the ABAQUS software is applied for considering the mechanical properties of UHPC, RC, and ordinary concrete specimens. To calibrate the ABAQUS, some experimental tests have been carried out in the laboratory to measure the direct tensile strength of UHPC by the compressive-to-tensile load converting (CTLC) device. This device contains a concrete specimen and is mounted on a universal tensile testing apparatus. In the experiments, three types of mixed concrete were used for UHPC specimens. The tensile strength of these specimens ranges from 9.24 to 11.4 MPa, which is relatively high compared with ordinary concrete specimens, which have a tensile strength ranging from 2 to 5 MPa. In the experimental tests, the UHPC specimen of size 150×60×190 mm with a central hole of 75 mm (in diameter)×60 mm (in thickness) was specially made in the laboratory, and its direct tensile strength was measured by the CTLC device. However, the numerical simulation results for the tensile strength and failure mechanism of the UHPC were very close to those measured experimentally. From comparing the numerical and experimental results obtained in this study, it has been concluded that UHPC can be effectively used for bridge decks.

• Structural Engineering and Mechanics
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• v.64 no.5
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• pp.621-640
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• 2017

This paper reports the numerical investigation conducted to study the influence of Local-Distortional (L-D) interaction mode buckling on post buckling strength erosion in fixed ended lipped channel cold formed steel columns. This investigation comprises of 81 column sections with various geometries and yield stresses that are carefully chosen to cover wide range of strength related parametric ratios like (i) distortional to local critical buckling stress ratio ($0.91{\leq}F_{CRD}/F_{CRL}{\leq}4.05$) (ii) non dimensional local slenderness ratio ($0.88{\leq}{\lambda}_L{\leq}3.54$) (iii) non-dimensional distortional slenderness ratio ($0.68{\leq}{\lambda}_D{\leq}3.23$) and (iv) yield to non-critical buckling stress ratio (0.45 to 10.4). The numerical investigation is carried out by conducting linear and non-linear shell finite element analysis (SFEA) using ABAQUS software. The non-linear SFEA includes both geometry and material non-linearity. The numerical results obtained are deeply analysed to understand the post buckling mechanics, failure modes and ultimate strength that are influenced by L-D interaction with respect to strength related parametric ratios. The ultimate strength data obtained from numerical analysis are compared with (i) the experimental tests data concerning L-D interaction mode buckling reported by other researchers (ii) column strength predicted by Direct Strength Method (DSM) column strength curves for local and distortional buckling specified in AISI S-100 (iii) strength predicted by available DSM based approaches that includes L-D interaction mode failure. The role of flange width to web depth ratio on post buckling strength erosion is reported. Then the paper concludes with merits and limitations of codified DSM and available DSM based approaches on accurate failure strength prediction.

• Fashion & Textile Research Journal
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• v.3 no.2
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• pp.168-173
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• 2001

In order to overcome the disadvantage of the conventional two bath dyeing method of wool/cotton blends, it had prompted significant effort to the development of the one bath dyeing method which can accomplish savings in energy, water usage and time. To improve the dyeability of cotton toward direct dyes in a non-electrolytic and acidic dyebath, cotton component was pretreated with cationizing agent containing chlorohydrine group in aqueous solution of sodium hydroxide. This study was carried out to investigate almost equal color strength between wool component and cationized cotton component when wool/cationized cotton blends was dyed with acid dye/direct dye by the one bath two step method in a non-electrolytic and acidic dyebath.

• Journal of the Korean institute of surface engineering
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• v.33 no.2
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• pp.101-106
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• 2000

SOI (Silicon-On-Insulator) substrates were fabricated with varying annealing temperature of $25-660^{\circ}C$ by a linear annealing method, which was modified RTA process using a linear shape heat source. The annealing method was applied to Si ∥ $SiO_2$/Si pair pre-contacted at room temperature after wet cleaning process. The bonding strength of SOI substrates was measured by two methods of Razor-blade crack opening and direct tensile test. The fractured surfaces after direct tensile test were also investigated by the optical microscope as well as $\alpha$-STEP gauge. The interface bonding energy was 1140mJ/m$^2$ at the annealing temperature of $430^{\circ}C$. The fracture strength was about 21MPa at the temperature of $430^{\circ}C$. These mechanical properties were not reported with the conventional furnace annealing or rapid thermal annealing method at the temperature below $500^{\circ}C$. Our results imply that the bonded wafer pair could endure CMP (Chemo-Mechanical Polishing) or Lapping process without debonding, fracture or dopant redistribution.

• Textile Coloration and Finishing
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• v.12 no.1
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• pp.44-51
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• 2000

The conventional one bath exhaust dyeing system of nylon]/cotton blends with acid dye/direct dye involves a lot of neutral salt which affect dyeability of acid dyes. Because of conventional one bath exhaust dyeing system of nylonl/cotton blends with acid dye/direct dye needs acid dyes adjusted at a neutral liquor, suitable acid dye is limited. To improve dyeing property of nylon/cotton blends, cotton component was pretreated with cationizing agent containing chlorohydrine group in aqueous solution of sodium hydroxide. This study was carried out to investigate dyeing possibilities of nylon/cationized cotton blends with acid dye/direct dye in a non-neutral salt dyebath by one bath two step method. The concentration of direct dye was 1.0%, 0.7%, 0.3%o.w.f. respectively at a non, 1%, 3%owf of reserving agent for being almost equal color strength between nylon and 3% cationized cotton when nylon/3% cationized cotton blends was dyed with acid dye/direct dye at concentration of acid dye(1%o.w.f.) by one bath two step method.