• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.1
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• pp.11-18
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• 2018

An experimental study on the ultimate behaviors of the mild carbon steel (SPHC) fillet-welded connection is presented in this paper. Seven specimens were fabricated by the shielded metal arc welding (SMAW). All specimens failed by typical block shear fracture in the base metal of welded connections not weld metal. Block shear fracture observed in the base metal of welded connection is a combination of single tensile fracture transverse to the loading direction and two shear fractures longitudinal to the loading direction. Test strengths were compared with strength predictions by the current design equations and suggested equations by previous researchers. It is known that current design specifications (AISC2010 and KBC2016) and Oosterhof & Driver's equation underestimated overly the ultimate strength of the welded connection by on average 44%, 31%, respectively and prediction by Topkaya's equation was the closest to the test results. Consequently, modified equation is required to be proposed considering the stress triaxiality effect and material property difference on the block shear strength for base metal fracture in welded connections fabricated with mild carbon steel.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.5
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• pp.741-746
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• 2022

In this paper, structural analysis was conducted on the base frame for materials of the conveyor system that automatically produces nurungji. The materials of the base frame were selected as SS400, STS304, Al6063-5. Structural analysis performed Von-Mises stress and maximum displacement for 38 hot plates in real situation, and performed weight of distribution force for yield strength, and calculated safety factor. SS400 and STS304 have little displacement, but Al6063-5 is deformed to 0.149mm, which is 2.6 times greater than other materials. However, since the safety factor was calculated as 8.5, it can be applied to the applicable food processing equipment. The weight of the distributed force for the yield strength of the materials was 17.7kN for SS400, 14.7kN for STS304, and 10.2kN for Al6063-T5. When manufacturing other processed foods with a base frame of the same size, a material suitable for the corresponding weight should be selected.

• Journal of Microbiology and Biotechnology
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• v.34 no.4
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• pp.891-901
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• 2024

This study focuses on improving the 3D printability of pea protein with the help of food inks designed for jet-type 3D printers. Initially, the food ink base was formulated using nanocellulose-alginate with a gradient of native potato starch and its 3D printability was evaluated. The 3D-printed structures using only candidates for the food ink base formulated with or without potato starch exhibited dimensional accuracy exceeding 95% on both the X and Y axes. However, the accuracy of stacking on the Z-axis was significantly affected by the ink composition. Food ink with 1% potato starch closely matched the CAD design, with an accuracy of approximately 99% on the Z-axis. Potato starch enhanced the stacking of 3D-printed structures by improving the electrostatic repulsion, viscoelasticity, and thixotropic behavior of the food ink base. The 3D printability of pea protein was evaluated using the selected food ink base, showing a 46% improvement in dimensional accuracy on the Z-axis compared to the control group printed with a food ink base lacking potato starch. These findings suggest that starch can serve as an additive support for high-resolution 3D jet-type printing of food ink material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.1121-1124
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• 2002

Currently, the regulation system on controlling EMI has been strengthened throughout the world and this system has emerged as another invisible barrier from the advanced countries. Such a regulation is likely to expand in many various ways depending on the objective and type, and there has to be a fundamental EMI measure to respond this movement. This study is aimed at learning the EMI technology of communication system through the shielding material. It introduces the selection of appropriate shielding material and method of use, and it introduces the cases that resolved the actual EMI problem of the system that is manufactured by the company.

• Structural Engineering and Mechanics
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• v.53 no.1
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• pp.159-172
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• 2015

This paper is concerned with effects of the wall flexibility on the seismic behavior of ground-supported cylindrical silos. It is a well-known fact that almost all analytical approximations in the literature to determine the dynamic pressure stemming from the bulk material assume silo structure as rigid. However, it is expected that the horizontal dynamic material pressures can be modified due to varying horizontal extensional stiffness of the bulk material which depends on the wall stiffness. In this study, finite element analyses were performed for six different slenderness ratios according to both rigid and flexible wall approximations. A three dimensional numerical model, taking into account bulk material-silo wall interaction, constituted by ANSYS commercial program was used. The findings obtained from the numerical analyses were discussed comparatively for rigid and flexible wall approximations in terms of the dynamic material pressure, equivalent base shear and bending moment. The numerical results clearly show that the wall flexibility may significantly affects the characteristics behavior of the reinforced concrete (RC) cylindrical silos and magnitudes of the responses under strong ground motions.

• Corrosion Science and Technology
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• v.14 no.2
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• pp.54-58
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• 2015

A heavy oil of low quality has been mainly used in the diesel engine of the merchant ship as the oil price has been significantly jumped for several years. Thus, a combustion chamber of the engine has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of the combustion chamber has been getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the engine parts such as exhaust valve, piston crown and cylinder head surrounded with combustion chamber are more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these engine parts is very important to prolong their lifetime in a economical point of view. In this study, 1.25Cr-0.5Mo filler metal was welded with SMAW method in the forged steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected and base metal zones were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% $H_2SO_4$ solution. The weld metal and base metal zones exhibited the highest and lowest values of hardness respectively. And, the corrosion resistance of the heat affected and weld metal zones was also increased than that of the base metal zone. Furthermore, it appeared that the corrosive products with red color and local corrosion like as a pitting corrosion were more frequently observed on the surface of the base metal zone compared to the heat affected and weld metal zones. Consequently, it is suggested that the mechanical and corrosion characteristics of the piston crown can be predominantly improved by repair welding method using the 1.25Cr-0.5Mo electrode.

• Journal of Korean Foot and Ankle Society
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• v.17 no.3
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• pp.220-224
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• 2013

Purpose: When medial protrusion in the base of proximal phalanx is severe from removing metatarsal bunion during the hallux valgus surgery, it could lead to skin irritation and medial pain after the surgery. The purpose of this paper was to report our clinical and radiographic results with transarticular fixation of Akin osteotomy for the treatment of patients with hallux valgus after resection of the medial protrusion of base of the proximal phalanx. Materials and Methods: Our study is subject to 34 cases of 30 patients who went through proximal phalanx medial corticectomy among patients undergone both hallux valgus surgery and Akin osteotomy at our institution from March 2006 to March 2012. In all cases, we used absorbable suture material through the articular surface for Akin osteotomy after resection of the medial protrusion in proximal phalanx. Radiographs were reviewed to assess the union and displacement of osteotomy site at the time of postoperative 6 months. The clinical results were assessed by using AOFAS score and complication such as skin irritation and pain. Results: AOFAS score was improved from average 44 points(36-58), before operation and average 87 points(74-96), 12 months after operation. In two cases, partial union was suspected in radiological perspective, however, complete union on the osteotomy site was observed in all cases, 12 months after the operation. No patients was dissatisfied with pain, joint discomfort, skin irritation and inflammation from the knot. Conclusion: When medial protrusion in the base of proximal phalanx is severe from removing metatarsal bunion during the hallux valgus surgery, We have good results by transarticular fixation of Akin osteotomy using absorbable suture material.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.3
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• pp.236-245
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• 2002

The acrylic resin was first introduced as denture base materials in 1937 and it is commonly used for denture base fabrication nowadays. Three different curing cycles (Conventional curing cycle, short curing cycle and long curing cycle) and three commercially available heat-activated acrylic resins (Vertex RS, Lucitone 199 and ProBase Hot) were investigated to find the curing cycle and material that showed the minimum shrinkage of the resin during polymerization process. A brass master mold was fabricated and duplicated by additional silicone impression material. Stone molds were made by pouring of type III dental stone (SILKY-ROCK YELLOW, Whip-Mix, Louisville, Kentucky). It was embedded in the flask. Strain gauge and thermocouple were embedded in the specimen. Strain gauge and thermocouple were connected to signal conditioning amplifier and data was recorded by pre-programmed software. The parameters ESmax (Maximum expansion strain), Sb (Strain measured just before deflasking procedure), Sa (Strain measured just after deflasking procedure) and Sf (Strain measured at the end of the experiment) were measured. ${\Delta}$S was calculated from Sb and Sa (${\Delta}$S=Sb-Sa). In the experiment concerned about materials, the parameters 90-ESmax (Maximum expansion strain measured during early 90 minutes of curing procedure), 180-ESmax (Maximum expansion strain measured from 90 minutes to 180 minutes), Sb, Sa, ${\Delta}$S and Sf were measured and the following conclusions were made. 1. The ESmax value of conventional curing cycle showed the largest value and the 180-ESmax value of Lucitone 199 showed the smallest value. 90-ESmax values showed no significant difference (p<0.05). 2. ${\Delta}$S values of conventional curing cycle showed the positive values. ${\Delta}$S values of short curing cycle and long curing cycle showed the negative values. All three materials cured by conventional curing cycle showed the positive values. 3. The Sf values of long curing cycle and ProBase Hot (cured by conventional curing cycle) showed the smallest values.

• Journal of Welding and Joining
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• v.21 no.3
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• pp.78-84
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• 2003

The changes of microstructure and hardness of TLP bonds of directionally solidified Ni base superalloy, GTD-111, with variation of homogenizing and aging treatment were investigated. The specimens were bonded at 1403K for 7.2ks using different insert metals such as MBF-50, MBF-80 and MBF-90 and they were homogenized at 1393K with various holding time. At center of bonded interlayer homogenized for hold time 30h, the contents of aluminum and titanium were approximately 90% and 95% of base metal, respectively. In this study, aging was performed at three different kinds : one step aging ; 1113K $\times$ 16h, two step aging ; 1113K $\times$ 10h ⇒ 1103K $\times$ 10h, three step aging ; 1113K $\times$ 10h ⇒ 1103K $\times$ 8h ⇒ 922K $\times$ 24h. ${\gamma}$' volume fraction and hardness of joints were high in the sequence of one step, two step and three step aging, whereas ${\gamma}$' volume fraction and hardness of joints obtained by three step aging treatment were higher than those of raw material. Tensile properties of joints bonded with MBF-80 and MBF-90, homogenized at 1393K for 30h and then three step aged became excellent than those of raw material, however, joint bonded with MBF-50 was poor.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.4
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• pp.665-674
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• 1996

This study was designed to evaluate the effect of processing method and surface design on the transverse strength of repaired denture base resin. Three heat-cured denture base resins(Vertex, Lucitone, Lang), one cold-cured resin(Lang), and one light-cured resin(Dentacolor gingiva material) were used for repair purpose. The specimens for 3-point flexure test were fabricated by five processing methods such as self-curing, pressure pot, boiling water, processing, and light curing. Finally to evaluate the effect of surface designs for repaired resin, three surface designs(butt, bevel, inverse bevel) were tested. Within the limit of this study, following conclusions were drawn. 1. Lucitone denture base material showed highest flexural strength of $131.37{\pm}2.15MPa$, and there were significant differences in stength between Lucitone and other resins. 2. Between two different self curing methods, self curing repair resin, Lang, cured by pressure pot method showed highest flexural strength, $58.49{\pm}4.89MPa$. 3. Among the heat cured repair resins, maximum transverse strength value of $88.69{\pm}16.60MPa$ was recorded in Lucitone group cured by processing method. 4. Inverse bevel joint design showed significantly higher bond strength than butt joint group, Maximum bond strength was $59.36{\pm}1.33MPa$ in inverse bevel joint design group.