• Journal of Adhesion and Interface
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• v.21 no.1
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• pp.1-5
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• 2020

Heated tool joining is a popular method for joining parts made from plastics and composite materials. The method is commonly known as butt fusion in the plastic pipe industry and this paper provides a short introduction to the basics of producing a good butt fusion joint. The function of each of the essential parts of the butt fusion equipment is described followed by a presentation of the important parameters of the bonding process in reference to a well-established interfacial pressure versus time curve. The butt fusion procedure is then outlined with good practices that detail the preparation of equipment and pipes to be joined as well as the fusion joining process.

• Journal of Korean Association for Spatial Structures
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• v.6 no.1 s.19
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• pp.55-63
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• 2006

Concrete-filled steel columns consist of circular, square or rectangular hollow sections filled concrete. Much research has studied for the behavior of concrete-filled steel structures. The advantages from structural point of view are the triaxial confinement of the concrete within the section, and the fire resistance of the column which largely depends on the residual capacity of the concrete core. The axial capacity of a concrete-filled rectangular or circular section is enhanced by the confining effect of the steel section on the concrete which depends in the magnitude on the shape of the section and the length of the column. Buckling tends to reduce the benefit of confinement on the squash load as the column slenderness increases. In circular sections it is possible to develop the cylinder strength of the concrete. When compare with reinforced concrete columns, the concrete-filled composite column possesses much better strength and ductility in shear and generally in flexure also. Many researches are being conducted about concrete filled steel column to get these advantages in building design. In this paper it is provided to the basic experimental study of compression behavior of the circular and rectangular tubular steel pipe filled with concrete.

• The Journal of Engineering Geology
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• v.29 no.4
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• pp.451-460
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• 2019

In this study, a complex behavior connector is proposed to overcome the problems that may occur when small pile pipe and micro pile is used as a friction pile concept in the lower foundation of an oil sand plant where a piloti foundation is used. The individual settlement and heaving of piles were connected in one group to allow the composite behavior. This study performed to analyze the load carrying capacity to identify a complex behavior. In addition, the shape of the composite behavior connector was examined to apply the advantages of pile-group and piled raft foundations to oil sand plants. A scale model was constructed to measure the behavior of the load. The stability and weakness of the device were selected to determine the shape of the connector using the scale model testing.

• The Korean Journal of Food And Nutrition
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• v.29 no.4
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• pp.480-485
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• 2016

This study was conducted to develop food for the elderly, which is easier to chew and swallow, using gelification. Various foods for the elderly with chewing and swallowing difficulties were used for sensory assessment. The sensory panel consisted of 10 dieticians (10 women) working in nursing care facilities. The sensory optimal composite recipes were determined by the central composite design (CCD). The optimum formulation of hot pepper paste stir fried pork calculated by the numerical and graphical method was 1.48 g of sugar and 18.97 g of hot pepper paste. The optimum formulation of seasoned spinach was 8.0 g of sesame oil and 5.41 g of soy sauce. Moisture content, hardness, and adhesiveness of hot pepper paste stir fried pork was 76.49%, 2.50, and -1.20, respectively. Moisture content, hardness, and adhesiveness of seasoned spinach was 83.48%, 2.27, and -1.17, respectively. This study provides the basic materials for the development of easily chewable and swallowable foods for the elderly, which can reduce the risk of food going down the wrong pipe, and the preference can be improved by eating solid food instead of porridge or liquid food. The development of food for the elderly, which takes the difficulties in chewing and swallowing among the elderly into consideration and reflects their preference and has sufficient amount of nutrients, is important to enable the elderly to enjoy their meals and it is one of the biggest challenges in Korea, as Korean society is aging rapidly.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.2
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• pp.139-145
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• 1998

Filament winding method is widely used for composite fabrications using low viscosity liquid for-mation and processing asymmetrical structures of pressure vessel pipe rocket motor case etc. The filament winding method is affected by several parameters such as pot life of process time viscosi-ty of resin filament winding temperature and schedules curing condition and post curing condi-tion of resin. To develope high functional composite materials the rotation(5, 15, 20, 30rpm) of the winding machine was controlled by D.C motor. And the wiper to give proper tension was equipped between strand and resin bath. The resin is hooked by the design wiper. The adequate cure schedule was found by DSC. NOL ring test is carried out to investigate the basic physical properties such as design technology. The void contents in filament winding is generally higher than that of the prepreg laminated plate. These high contents of void can make a crack in resin in spite of low deformation. These problem was solved by giving tension in processing. To improve the characteristics of fiber volume fraction void contents resin/fiber bonding the winding speedc is changed under constant tension. It was found that resin impregnation was not different from in fiber contents void contents at the range of 0.5~1kg tension but it was found that resin was not impregnated at the above of 1.5kg tension. In burst test a pure PE liner was failed at a nozzle part under the $14kg/\textrm{cm}^2$ pressure but a pressure vessel of CNG was failed at a cylinder part under the $200kg/\textrm{cm}^2$ pressure.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.331-343
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• 2017

In this study to improve stability, workability and economics of the H-Pile+Earth plate or H-Pile+Earth plate+Cutoff grouting currently in use, we had developed HCS method belonging to the retaining wall which is consisting of a combination H-Pile, Plastic Sheet Pile and Steel Square Pipe for gap maintenance and reinforcement of flexible plastic Sheet Pile, and the behavior of each member composing HCS method is investigated by three-dimensional finite element analysis. To numerically analyze the behavior of the HCS method, we have performed extensive three-dimentional finite element analysis for three kinds of plastic Sheet Pile size, two kinds of H-Pile size and three kinds of H-Pile installation interval, one kinds of Steel Square Pipe and three kinds of Steel Square Pipe installation interval. After analyzing the numerical results, we found that the combinations of $P.S.P-460{\times}131.5{\times}7t$ (PS7) and H-Pile $250{\times}250{\times}9{\times}14$ (H250), $P.S.P473{\times}133.5{\times}9t$ (PS9) and H-Pile $300{\times}200{\times}9{\times}14$ (H300) is the most economical because these combinations are considered to have a stress ratio (=applied stress/allowable stress) close to that as the stiffness of H-Pile, plastic Sheet Pile and Steel Square Pipe composite increased, the horizontal displacement of the retaining wall and the vertical displacement of the upper ground decreased. Especially, due to the arching effects caused by the difference in stiffness between H-Pile and plastic Sheet Pile, a large part of the earth pressure acting on plastic Sheet Pile caused a stress transfer to H-Pile, and the stress and displacement of plastic Sheet Pile were small. Through this study, we can confirm the behavior of each member constituting the HCS method, and based on the confirmed results of this study, it can be used to apply HCS method in reasonable, stable and economical way in the future.

• Steel and Composite Structures
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• v.24 no.1
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• pp.93-112
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• 2017

Metaheuristic algorithms in general make use of uniform random numbers in their search for optimum designs. Levy Flight (LF) is a random walk consisting of a series of consecutive random steps. The use of LF instead of uniform random numbers improves the performance of metaheuristic algorithms. In this study, three discrete optimum design algorithms are developed for steel skeletal structures each of which is based on one of the recent metaheuristic algorithms. These are biogeography-based optimization (BBO), brain storm optimization (BSO), and artificial bee colony optimization (ABC) algorithms. The optimum design problem of steel skeletal structures is formulated considering LRFD-AISC code provisions and W-sections for frames members and pipe sections for truss members are selected from available section lists. The minimum weight of steel structures is taken as the objective function. The number of steel skeletal structures is designed by using the algorithms developed and effect of LF is investigated. It is noticed that use of LF results in up to 14% lighter optimum structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.339-342
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• 2000

Recently, the importance of the conutermeasures for waste materials has pointed out. Waste glass is also one to waste materials used for the recycling in construction sites. The crushed waste glass has been used to make a glass polymer composite that can be applied for sewer, storm drain pipe and interlocking block, etc. In this study, the crushed waste glass is explored with the possibility of recycling it, as a substitute for fine aggregates. The prepose of this investigation is to improve the strengths and acid resistance of the UP mortars using crushed waste glass. The UP mortars are prepare with blast furnace slag fly ash filler. the UP-fine aggregate ratios the crushed waste glass replacements for fine aggregate are tested strengths before and after immersion(H (아래첨자2)SO(아래첨자4) 10%), weight change and acid resistance are also tested. From the test results, the relative strength or UP mortars using fly ash as filler are found to be somewhat superior to that of the UP mortars using blast furnace as filler, And a UP mortar with fly ash as a filler, a UP-fine aggregate ratio of 15% and a waste glass replacement if 50% for fine aggregate is recommended as optimal mix proportion of UP mortar using crushed waste glass. Accordingly, it is enough to assure the use of the crushed waare glass as an aggregate for the production of UP mortar.

• Structural Engineering and Mechanics
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• v.66 no.1
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• pp.97-111
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• 2018

Cracking can lead to unexpected sudden failure of normally ductile metals subjected to a tensile stress, especially at elevated temperature. This article is raised to study the application of a composite material instead of the traditional carbon steel material used in the natural gas transmission pipeline because the cracks occurs in the pipeline initiate at its internal surface which is subjected to internal high fluctuated pressure and unsteady temperature according to actual operation conditions. Functionally graded material (FGM) is proposed to benefit from the ceramics durability and its surface hardness against erosion. FGM properties are graded at the radial direction. Finite element method (FEM) is applied and solved by ABAQUS software including FORTRAN subroutines adapted for this case of study. The stress intensity factor (SIF), temperatures and stresses are discussed to obtain the optimum FGM configuration under the actual conditions of pressure and temperature. Thermoelastic analysis of a plane strain model is adopted to study SIF and material response at various crack depths.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.8
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• pp.351-356
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• 2014

Typical trouble patterns in solar thermal systems include working fluid leakage and freezing other than breakdown of pump. A fluid sensor for measuring electric resistance of fluid was developed and installed at the top of the collector piping in order to check the fault of solar system. Working fluid level in the pipe was determined by measuring electric resistance from a fluid sensor. On the base of this, it was confirmed that the fluid sensor diagnoses leakage of fluid. Electric resistance of propylene glycol aqueous solution was measured in the range of $0{\sim}70^{\circ}C$ and 0~40% of concentration. The response surface analysis was performed by using a central composite design, and the regression equation was derived from the relationship between electric resistance, temperature, and concentration. Through the experiment in a real solar system, we can estimate a concentration of working fluid when a pump is not operating and predict a possibility of freezing. Finally, an effective algorithm for trouble shooting was proposed to operate and maintain the solar system.