• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.4D
• /
• pp.587-592
• /
• 2006

The joint sealants used in the airside should resist the high temperature of the jet blast and the jet fuel oil spilled when the aircraft is maintained and filled. The material of joint sealant for the airside should be different from that for the road due to these characteristics. Three different kinds of the joint sealant materials were tested in this paper. The materials include the polysulfide, the polyurethane and the silicon. The test results show that the physical properties and the performance of the polysulfide show the high resistance to the jet blast and the jet fuel oil. When the characteristics of the airside considered, the polysulfide may apply in the both of the runway and the apron area, the polyuretane can be applied the taxiway. The use of the silicon sealant is not recommended for the airside.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.6A
• /
• pp.943-953
• /
• 2006

We investigated experimentally the static behavior of an orthotropic bridge deck which is made from glass fiber reinforced polymer (GFRP) and polyurethane foam. The bridge deck consists of many unit cells with rectangular holes which are filled with the foam to improve its structural behavior in its weak axis. It is found that although the elastic modulus of the foam compared to that of the GFRP is about the order of, the structural behaviors in the weak axis such as nominal strength, stiffness, etc. are greatly improved. Owing to the low mass density of the foam used in this study, the bridge deck is still light enough with the improved structural properties. Webs of the cells filled with the foam did not significantly contribute to the strength development of the deck. However, the propagation of a crack initiated in a cell is caught by the webs and limited to the inside of that cell only, which makes the load-displacement behavior of the foam-filled GFRP deck less brittle.

• Journal of the Korean Burn Society
• /
• v.22 no.1
• /
• pp.15-19
• /
• 2019

Purpose: Pain management in burn treatment is important in improving wound healing and quality of life. Ibuprofen is a proven pain relieving agent in patients with partial thickness burn by intraveous injection. The purpose of this study is to evaluate the efficacy of Biatain Ibu^® (polyurethane foam containing ibuprofen) in pain control for outpatients with partial thickness burns. Methods: A prospective randomized clinical trial was performed in outpatients with partial thickness burn from August 1, 2017 to July 31, 2018. Acute pain, chronic pain, complications, days for re-epithelialization and patient's satisfaction were compared between Biatain Ibu^® and Biatain^® groups. Results: A total of 20 patients (Biatain Ibu^®, n=10; Biatain^®, n=10) were assessed in the trial. On Burn days 3, 5, 7, 11, 13, and 15, the acute pain levels were significantly lower in the Biatain Ibu^® group than in the Biatain^® group. Complications, chronic pain levels and days for re-epithelialization were not significantly different between the two groups. Patient's satisfaction was not statistically significant but was higher in the Biatain Ibu^® group. Conclusion: Biatain Ibu^® is effective in relieving pain in outpatients with partial thickness burn without decreasing patient satisfaction, wound healing ability or developing any complications.

• Tribology and Lubricants
• /
• v.39 no.6
• /
• pp.235-243
• /
• 2023

This paper presents the fabrication process of water-lubricated plastic bearings. Plastic bearings require good mechanical properties and tribological properties as well as elasticity and shock resistance, especially when lubricated in dirty water conditions. In this study, sleeve-type plastic bearings are produced by winding a prepreg sheet, which primary contains nitrile rubber (NBR)-modified epoxy, self-lubricating fillers, and various types of lattice-structured reinforcing fibers such as carbon, Aramid, and polyethylene terephthalate. A thermosetting epoxy is chemically modified with NBR to impart elasticity and low-friction characteristics in water conditions. Experimental investigations are conducted to examine the mechanical and tribological characteristics of the developed bearing materials, and the results are compared with the characteristics of a commercial plastic bearing (Thordon SXL), well known as a water-lubricated bearing. A Thordon bearing (mainly composed of polyurethane) exhibits an extremely low load-bearing capacity and is thus only suitable for medium loading (1~10MPa). The tribological characteristics of the test materials are evaluated through Falex block-on-ring (LFW-1) friction and wear tests. The results indicate that friction exhibited by the carbon-fiber-reinforced NBR-10wt.%-modified epoxy composite material, incorporated with the addition of 20wt.% UHMWPE and 6wt.% paraffin wax, is lower than that of the Thorden bearings, whereas its wear resistance surpass that of Thorden ones. Because of these features, the load carrying capacity of the fabricated composite (>10MPa) is higher than that of the Thorden bearings. These results confirm the applicability of water-lubricated plastic bearing materials developed in this study.

• Journal of the Korea Institute of Building Construction
• /
• v.23 no.6
• /
• pp.761-772
• /
• 2023

The fire resistance design of timber structures involves calculating the residual section based on charring depth, which is then utilized in structural design. Charring depth is determined from fire-resistance test results in Korea, which currently do not account for the charring properties of the adhesive used in Glued Laminated Timber(GLT) production. This study fabricated GLT using various adhesives employed in domestic GLT production, comparing the charring properties by adhesive type and the fire resistance performance relative to the directionality of the laminated surface. Melamine demonstrated the most advantageous fire resistance performance, followed by resorcinol and polyurethane. Furthermore, it was established that the laminated section exhibited a higher charring rate, influenced by the adhesive, compared to the laminated surface, which significantly impacts the fire resistance performance.

• The Journal of the Acoustical Society of Korea
• /
• v.26 no.6
• /
• pp.293-300
• /
• 2007

Turbulent boundary layer over an underwater vehicle is formed when it moves underwater and wall pressure fluctuation within the turbulent boundary layer generates flow-induced noise by exciting the elastic hull of the underwater vehicle. One of the methods to reduce this flow noise is to attach a compliant layer on the surface of the vehicle. In order to observe the possibility of noise reduction in the water when the compliant layer treatments are applied on the surface, three types of specimens those are a bare steel plate, a steel plate coated with neoprene and a steel plate with polyurethane coating material are tested at various flow speeds in a low noise cavitation tunnel. This paper presents the results of measurements and analysis of wall pressure fluctuations which is a main source of flow noise, within the turbulent boundary layer on three specimens. Its results could be shown that about 10dB reduction of wall fluctuation pressure at high frequencies was achieved due to the dissipation of turbulent energy by the compliant coating while it makes the turbulent boundary layer thicker and changes the behavior of turbulent flow in the layer.

• Journal of the Korean Wood Science and Technology
• /
• v.52 no.1
• /
• pp.58-69
• /
• 2024

To evaluate the adhesive characteristics of mixed cross-laminated timber (CLT) using domestic softwoods structural lumber proposed by KS F 3020 and yellow poplar, penetration depth of adhesive and thickness of bonding line were analyzed based on the results of boiling water soaking delamination. 3 Types of adhesives and 2 types of major layer were divided into a 5 ply CLT using yellow popular as minor layer. The bonding performance of the mixed CLT as structural members was evaluated based on the KS F 2081. The thickness of bonding line between layers of the mixed CLT was measured with a scanning electron microscope, and the adhesive penetration depth in the layer members was measured with an optical microscope. As a result of boiling water soaking delamination test of mixed CLT, the CLT specimens using PRF and PUR adhesives met the requirements of KS F 2081. It was verified that the penetration path of the adhesive in the layes was mainly through the tracheid cell in the case of Japanese larch and Korean red pine layers, and through the vessel and radial tissue in yellow popular layers. The penetration depth of the adhesive was the highest for the PRF adhesive under the same pressing time conditions, and the thickness of the bonding line was in inverse proportion to the penetration depth in the case of the PUR adhesive.

• Fashion & Textile Research Journal
• /
• v.26 no.1
• /
• pp.55-64
• /
• 2024

This study investigated the usage and product conditions of clothing companies and online dummy companies for the development of fitting dummy for South Korean women's wear in their 50s and 60s. These women-targeted apparel companies mainly used nude-sized torso type and torso crotch type made of FRP material. The frequency of use of the dummies was high, while the user satisfaction was moderate. Users expressed dissatisfaction with the inaccurate reflection of the body shape according to the KS sizing system and the measurements such as the front and back intercye, upper arms, abdomen, crotch, and waist back length. Upon survey, 73.7% of the respondents answered that development of the dummy and the appropriate age for it is 50 to 54, and they preferred the torso crotch form. In the production of online dummy companies, the torso crotch type and torso type were most widely produced, and polyurethane, FRP, and recycled paper materials were used. The size of dummy was expressed in numerical type, and 6, 7, 8, 9, 10, 12, 14, 16, 18 and 44, 55, 66, 77, 88 were being produced. Even models of the same size had significant deviation, especially in the waist circumference. Also, there was no dummy reflecting 25%~75% center interval to the KS garment sizing standards of women in their 50s and 60s. Therefore, it is desperately necessary to develop a fitting dummy for KS clothing sizing system that reflect their body sizes and shapes.

• Composites Research
• /
• v.37 no.2
• /
• pp.108-114
• /
• 2024

Due to the continuously increasing global demand for electricity, the demand for high-voltage submarine cables is also increasing. One of the issues that need to be addressed for submarine cables is the high production cost and expensive laying costs. Submarine cables exposed to the marine environment encounter external forces such as wave and current, leading to issues such as cable damage due to external factors or high maintenance costs in the event of an accident. Therefore, we are preparing for the uncertainty of the submarine environment through many protective materials and protective equipment. In this study, we examined the bending performance of piggyback clamps (PBC) and strap, which are representative protective equipment, in response to the submarine environment through analytical methods. To examine the structural performance of PBC, the bending performance were assessed under the maximum bending moment criterion of 15 kN·m for the flexible protection tube. As a result, it was confirmed that the structural performance regarding the bending moment of both PBC and straps was ensured.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.44 no.2
• /
• pp.183-190
• /
• 2024

An environmentally-friendly nanocoating method that effectively adds flame retardant(FR) and gas shielding properties to combustible polymeric construction materials such as flexible polyurethane (PU) foam was studied. Naturally-driven two-dimensional(2D) nanomaterials such as graphene oxide (GO) can exhibit liquid crystalline (LC) properties in aqueous solutions, enabling uniform coatings on the various substrates including 3D-porous foams. LC phase-assisted coating serves as 3D-scaffold, facilitating the introduction of small molecules having antioxidant capabilities such as dopamine which is to form uniformly stacked FR coating. Additionally, the structural characteristics of the 2D-materials can effectively hinder the migration of toxic gases and flammable substances in the gas phase generated during combustion. This LC phase flame retardant coating technology could be a new approach to provide environmentally friendly and effective flame retardant and gas barrier properties to various types of polymeric materials.