• Journal of the Korean Wood Science and Technology
• /
• v.47 no.4
• /
• pp.451-458
• /
• 2019

Jabon (Anthocephalus cadamba Miq.) is a fast-growing species that exhibits a lower natural resistance than that exhibited by the timber sourced from natural forests. Jabon's resistance to termite attack can be improved by impregnating its wood structure with poisonous organic materials. This study examined jabon's resistance to termite attack when impregnated with wood vinegar and an animal adhesive. The wood specimens were impregnated using sengon wood vinegar and an animal adhesive (8% and 10%, respectively) using a vacuum pressure machine. The specimens were tested for their resistance to subterranean and dry-wood termites according to Indonesian National Standard (SNI 7207-2014). The results denoted that jabon impregnated with wood vinegar and an animal adhesive concentration of at least 8% with the addition of 4% borate was effective to resist termite attacks. The impregnated jabon exhibited a lower weight loss and higher termite mortality when compared with those exhibited by the control specimens. Thus, the resistance class improved from class IV to class I.

• Polymer(Korea)
• /
• v.32 no.1
• /
• pp.1-6
• /
• 2008

The adhesion behaviors and processability of NBR as a sealing material were investigated. In order to find the optimum formulation, the adhesive properties and processability were observed as the change of the contents of acrylonitrile (ACN) in NBR. Effects of Mooney viscosity, filler, plasticizer and crosslinking agent on the adhesion behaviors were also studied. The contents of ACN in NBR have great effects on adhesion behaviors and processability in NBR sealing. To know the optimum condition of roll mixing, degree of dispersion was investigated. It was confirmed that degree of dispersion was influenced by various factors such as mixing order, time, and temperature. The crosslinking system was studied as the observation of sulfur system, peroxide system, crosslinking density, and structure. From the variation of the dry condition and hexamine contents, the relation between adhesive and NBR was studied. These results show the adhesion properties and processability are dependent on the contents of ACN and crosslinking system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.6
• /
• pp.440-447
• /
• 2020

Masonry structures are used as bearing walls in small buildings, but they are generally considered non-bearing walls. They are used as partition walls that divide the interior spaces of the frame structures of buildings. In addition, wetting techniques that use mortar as an adhesive between blocks or bricks in construction are vulnerable to climatic conditions, especially cracks in mortar, which can cause conduction collapse of the walls in seismic loading. The purpose of this research was to propose a dry concrete block construction method that complements the weak axial shear stiffness and improves the weakness of the wet construction method as well as to investigate its structural behavior. In this study, the material properties of concrete blocks were examined, and the seismic performance of the proposed dry assembly structure was verified by structural behavior tests on horizontal cyclic loads. First, in these study results, concrete blocks can be applied to the dry block construction method instead of wet construction methods because they secure more than C-type blocks in KS regulations. Second, the structural performance of the wall against a horizontal cyclic load indicates that the resisting force of the assembly block wall is increased by increasing the horizontal length of the wall, forming several diagonal cracks. Finally, the proposed dry block wall structure requires a seismic performance assessment considering that the ratio of the shape of the wall by height and length is considered a major influence variable on the structural behavior under a horizontal load.

• Animal cells and systems
• /
• v.13 no.2
• /
• pp.153-160
• /
• 2009

The fine structural characteristics of the silk spinning apparatus in the titanoecid spiders Nurscia albofasciata have been examined by the field emission scanning electron microscopy (FESEM). This titanoecid spiders have a pair of medially divided cribella just in front of the anterior spinnerets, and the surface of the cribellum is covered by hundred of tiny spigots which produce numerous cribellate silk fibrils. The cribellar silks are produced from the spigots of the sieve-like prate. and considered as a quite different sort of catching silk with dry-adhesive properties. The other types of the silk spigots were identified as follows: ampullate, pyriform and aciniform glands. Two pairs of major ampullate glands send secretory ductules to the anterior spinnerets, and another 1-2 pairs of minor ampullate glands supply the middle spinnerets. In addition, the pyriform glands send ductules to the anterior spinnerets, and two kinds of the aciniform spigots feed silk into the middle (A type) and the posterior spinnerets (both of A & B types), respectively.

• Journal of the Korean Wood Science and Technology
• /
• v.37 no.1
• /
• pp.56-64
• /
• 2009

The purpose of this study was to investigate and develop an eco-friendly wood adhesive based on vegetable oil (especially soybean oil), the renewable and sustainable natural resources, using ozonification technology for the chemical structure modification. The soybean oil (SBO) was reacted with $O_3$ at the rate of 7.13 g/h for different times, 15 minutes, 30 minutes, 60 minutes, and 120 minutes. The investigation of the modified chemical structure of the ozonized SBOs were conducted using FT-IR, $^1H$-NMR, MALDI-TOF MS, and GC/MS. As ozonification time increased, the peak of the unsaturated double bonds was disappeared and aldehyde or carboxyl peak appeared because ozonification broke the oil into small molecules. The plywoods were made at $110^{\circ}C$ with 30 seconds/mm hot-press time using the different ozonized SBO/pMDI adhesives and were tested for the dry, wet, cyclic boil test according to the Korea Industrial Standard F3101 Ordinary plywood. The bond strengths gradually increased with increasing ozonification time. The weight ratio 1:1 (ozonized SBO/pMDI), all strengths in 15, 30 and 60 minuets, exceeded constantly the dry, wet, cyclic boiling standard requirement. The range of ozonification time and weight ratio can fulfil1 the requirment of the wet test standard were 30~60 minutes and more than 0.5 pMDI. From the comprehensive view on the results of above experiments, it could be confirmed through experiments that ozonized SBO/pMDI has characteristics of effective reactivity and wet stability showed as an excellent candidate of wood adhesive applications.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.9 no.1
• /
• pp.251-258
• /
• 2005

Up until now, most protection design has been concerned primarily with concrete's exterior protection from corrosion, its waterproof ability and its reparability. However, there are many cases in which service life of the concrete is shortened because suitability of the type of concrete surface has not been thoroughly investigated in the development process. According1y, this paper presents the development and test of the material for its reparability and its protection against corrosion in the case of wet surfaces (i.e. water supply facilities, sewage systems, and port facilities) in this country. From the test, both A type and B type are excellent for durability in watertightness, chemical resistance and abrasion. Test results of adhesive strength over $15kgf/cm^2$ under both wet and dry conditions, curing conditions and various temperatures conditions were also achieved in field tests.

• Restorative Dentistry and Endodontics
• /
• v.24 no.4
• /
• pp.570-577
• /
• 1999

Intuitively, higher bond strengths should result in less leakage. However, the relationship between bond strengths and microleakage value is complex and not clearly understood. The purpose of this study was to evaluate the relationship between tensile bond strengths and microleakage values in the same restorations to understand the behavior of resin bonding to tooth structure. One-hundred and twenty enamel or dentin specimens from freshly extracted bovine mandibular incisors were used. The specimen was treated with 32% phosphoric acid for 15 seconds and rinsed for 20 seconds. the teeth were divided into four groups by means of wet bonding technique or dry bonding. One-Step$^{TM}$ adhesive were applied to the specimen. The specimens were immersed in 2% methylene blue solution for 7 days, and tensile bond strength and microleakage were measured. The results were as follows: 1. Significant negative correlation was found between bond strengths and micro leakage values. Hence, higher bond strengths seem to be associated with lower microleakage, and vice versa (r=-0 50, p<0.05). 2. The Enamel/Wet group showed significantly higher bond strength than Enamel/Dry one, and Dentin/Wet group showed higher strength than Dentin/Dry one (p<0.05). 3. Microleakage was significantly less ill wet bonding than in dry one at dentin (p<0.05), however, there was no significant difference between wet and dry bonding at enamel (p>0.05).

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.2
• /
• pp.13-20
• /
• 2008

This paper describes the methods of spacer-fabrication for wafer-level CIS(CMOS Image Sensor) assembly. We propose three methods using SU-8, PDMS and Si-interposer for the spacer-fabrication. For SU-8 spacer, novel wafer rotating system is developed and for PDMS(poly-dimethyl siloxane) spacer, new fabrication-method is used to bond with alignment of glass/PDMS/glass structure. And for Si-interposer, DFR(Dry Film Resist) is used as adhesive layer. The spacer using Si-interposer has the strongest bonding strength and the strength is 32.3MPa with shear.

• Applied Microscopy
• /
• v.39 no.2
• /
• pp.149-156
• /
• 2009

Fine structure of the dry adhesion system in the tarsal appendages of the jumping spider Plexippus setipes (Araneae: Salticidae) with examined using field emission scanning electron microscope (FESEM). The jumping spiders have the distinctive attachment apparatus for adhesion on smooth dry surface without sticky fluids. They attach to rough substrates using tarsal claws, however attachment on smooth surfaces is achieved by means of a tuft-like hair called a scopula. All eight legs have the scopulae with a pair of claws on the tip of feet, and each scopula is composed of two groups of setae that are capable of dry adhesion on smooth surface. The apex of each seta is flattened pad bearing many specialized adhesive setules on one side. The cuticular sensillae are interspersed at the dorsal surface of the seta. It has been revealed by this research that the contact area of the setule is always a triangular shape, and these cuticular surfaces are connected by the elongated stalks from the underlying setae. Moreover, adhesion between the numerous setules and the setae was prevented by the microscopic hairs, since these were interspersed on the upper side of the setae.

• Journal of the Korean Wood Science and Technology
• /
• v.41 no.4
• /
• pp.293-301
• /
• 2013

This study discusses the feasibility of coffee bean residue as a raw material of medium-density fiberboard (MDF). In this relation, the effect of coffee bean residue known as an absorbent material on the physical and mechanical properties of MDF manufactured at its different addition level. Coffee bean residue which is a by-product of coffee mill and large amount of waste left over after processing for instant coffee was added at the level of 3, 6, and 9% on dry basis and urea formaldehyde resin was used as the adhesive. The MDF made with mixture of wood fiber and coffee bean residue was tested for physical and mechanical properties as well as formaldehyde emission. The bending strength and internal bonding strength of the MDF made with mixture of wood fiber-coffee bean residue were higher than that of the KS standard in randomized mat structure type, but not in layered mat structure type. Also, the physical properties of MDF made with mixture of wood fiber-coffee bean residue showed a considerable improvement in thickness swelling over the commercial MDF. More importantly, the formaldehyde emission rate of MDF made with mixture of wood fiber-coffee bean residue met the KS standard and was close to that of commercial MDF. These results showed the feasibility of coffee bean residue as a raw material for the production of environmentally-friendly MDF. Additional works on adhesive-coffee bean compatibility, improvement of moisture absorption effect and reduction the formaldehyde emission rate by carbonization of coffee bean residue may be required.