• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.3
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• pp.284-291
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• 2000

A basic pulse tube refrigerator has been constructed with extensive instrumentation to study the characteristics of the heat exchanger experimentally under the oscillating pressure and the oscillating flow. This paper describes the sequential experiments with the basic pulse tube refrigerator. The experiments were performed for various cycle frequencies under the square pressure wave forms. First, the heat flux was measured through the cycle at the both cold and warm end heat exchangers without the regenerator. In order to enhance the thermal communication capability of the heat exchanger with the gas at low operating frequencies, a unique design of the triangular shape radial fin concept was applied to the heat exchangers. For the fin heat exchanger, the measured heat flux and the calculated heat flux from the two well-known oscillating heat transfer correlations were compared and discussed. Second, the regenerator was added to the pulse tube to make a basic pulse tube refrigerator configuration. The experiment showed the great impact of the regenerator on the temperature and the heat flux profiles. At the warm-end, the cyclic averaged heat flux had its maximum value at the specific operating frequency. The paper presents the explanation of the surface heat pumping effect as well as the experimental data.

• Computers and Concrete
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• v.31 no.1
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• pp.53-69
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• 2023

The rotational stiffness of a semi-rigid beam-to-column connection plays an important role in the reduction of the second-order effects in the precast concrete skeletal frames. The aim of this study is to present a detailed nonlinear finite element study to reproduce the experimental response of a semi-rigid precast beam-to-column connection composed by corbel, dowel bar and continuity tie bars available in the literature. A parametric study was carried using four arrangements of the reinforcing tie bars in the connection, including high ratio of the continuity tie bars passing around the column in the cast-in-place concrete. The results from the parametric study were compared to analytical equations proposed to evaluate the secant rotational stiffness of beam-to-column connections. The good agreement with the experimental results was obtained, demonstrating that the finite element model can accurately predict the structural behaviour of the beam-to-column connection despite its complex geometric configuration. The secant rotational stiffness of the connection was good evaluated by the analytical model available in the literature for ratio of the continuity tie bars of up to 0.69%. Precast beam-to-column connection with a ratio of the continuity tie bars higher than 1.4% had the secant stiffness overestimated. Therefore, an adjustment coefficient for the effective depth of the crack at the end of the beam was proposed for the analytical model, which is a function of the ratio of the continuity tie bars.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.7
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• pp.510-519
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• 2002

The present study addresses a computational work of the weak shock wave propagating inside an automobile exhaust muffler. Several different types of the silencer systems are employed to investigate the magnitude of the shock wave during propagating through them. The Initial shock wave Mach number $M_s$ is varied between 1.01 and 1.30, and a normal shock wave is given at the inlet of the silencer systems. The second order total variation diminishing scheme Is employed to solve the two dimensional, compressible, unsteady Euler equations. The present computational results are compared with the previous experimental ones available. The present computations predict the experimental results with a quite good accuracy. Of the four silencer systems applied. the most desirable silencer system to reduce the peak pressure at the exalt of the exhaust pipe is discussed from the Point of view of the engineering design of the silencer systems.

• Design & Manufacturing
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• v.10 no.1
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• pp.26-30
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• 2016

In this study, it was investigated by comparing the experimental hemming by the 3 steps and 2 steps in order to stabilize the quality of the hemming process. In the experimental results, the three-step hemming superior to the two-step one and the dimensional stability of part that was made by the three-step on was high. When the second stage Hemming has been found that the deflection caused by the force to the wear of the punch becomes larger plane can be folded by the hemming crimping and crimp uncertain.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.4
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• pp.91-98
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• 2014

In this study, the first and second electronically controlled cooling systems for a bimodal tram were developed. The performance characteristics of the cooling systems were assessed experimentally with actual and identical conditions, and a simulation was run using ANSYS Fluent. The results of the experimental and FEA method were standardized. In order to confirm the reliability of the experimental method, the experiment was carried out by a testing institution. The low-volume flow-rate condition was found to be better, but the cooling system performed in a minimal condition. Therefore, it is important to find the optimum performance levels. The cooling system equipment was revised to determine the optimized design parameters, after which the cooling performance levels increased at the radiation area. Specifically, with a greater fan diameter. Through this study, the newly developed cooling system will be reevaluated after being mounted on an actual bimodal tram. This will lead to a completely domestically produced bi-modal tram cooling system.

• The Journal of Industrial Distribution & Business
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• v.8 no.7
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• pp.51-61
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• 2017

Purpose - Present study investigates character identification and emotional response to character that may affect consumers' intention to purchase the character-attached products. And this study explores whether symbolic relevance and object relevance affect the character identification, and whether character attractiveness and character salience affect the emotional response to characters. Research design, data, and methodology - SNS characters, animated characters, game characters, and traditional characters were used as experimental characters. And stationery as experimental product was used. 250 college students participated in the empirical study, and structural equation model was used to verify hypotheses. Results - First, the character identification and emotional response to characters affected the intention to purchase the products positively, and the emotional response to characters also positively affected character identification; second, symbolic relevance had no positive impact upon character identification, while object relevance had positive influence on character identification; and third, character attractiveness and salience had a positive effect on the emotional response. Conclusions - Present study contributes to the progress of character theories. Marketers should find ways to increase consumers' object relevance to characters and the level of characters' attractiveness and salience in order to promote the intent to purchase the products.

• Asia-Pacific Journal of Business
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• v.11 no.4
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• pp.21-36
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• 2020

Purpose - This study analyzes the effect of sellers' dishonesty on various market outcomes such as seller profit, buyer profit, and market welfare, through precisely measuring the level of sellers' information disclosure and its economic impacts. As an explicit observation of sellers' dishonesty is not easy in most other settings, this study is expected to suggest unique and meaningful implications on the effect of sellers' incomplete information disclosure to researchers, managers, and policy makers. Design/methodology/approach - In order to precisely measure the level of sellers' dishonesty under information asymmetry, this study analyzes the data from an incentive-based economic experiment using z-Tree software. This experimental method enables us to focus on the strategic interactions among participants, observe the integrity of seller's information disclosure, and reproduce real market situations. Findings - The analysis of sellers' dishonesty has provided the following important and counterintuitive findings about the reality of buyer-seller interactions under information asymmetry. First, sellers' lies do not affect seller profit even when they are very intensive. Second, sellers' dishonesty negatively affects buyer profit and the entire market welfare. Third, a seller's quality claim has a positive effect on the seller profit only when a seller is being honest. Research implications or Originality - This study analyzes sellers' dishonesty using incentive-based economic experiment using z-Tree software which provides a straightforward examination on dishonest behavior of sellers, that is not readily available with other types of observational or experimental data.

• Advances in materials Research
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• v.13 no.1
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• pp.1-18
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• 2024

The present experimental investigation focuses on finding optimal parametric data-set of laser micro-drilling operation with minimum taper and Heat-affected zone during laser micro-drilling of Carbon Nanotube/Epoxy-based composite materials. Experiments have been conducted as per Box-Behnken design (BBD) techniques considering cutting speed, lamp current, pulse frequency and air pressure as input process parameters. Then, the relationship between control parameters and output responses is developed using second-order nonlinear regression models. The analysis of variance test has also been performed to check the adequacy of the developed mathematical model. Using the Response Surface Methodology (RSM) and an Accelerated particle swarm optimization (APSO) technique, optimum process parameters are evaluated and compared. Moreover, confirmation tests are conducted with the optimal parameter settings obtained from RSM and APSO and improvement in performance parameter is noticed in each case. The optimal process parameter setting obtained from predictive RSM based APSO techniques are speed=150 (m/s), current=22 (amp), pulse frequency (3 kHz), Air pressure (1 kg/cm²) for Taper and speed=150 (m/s), current=22 (amp), pulse frequency (3 kHz), air pressure (3 kg/cm²) for HAZ. From the confirmatory experimental result, it is observed that the APSO metaheuristic algorithm performs efficiently for optimizing the responses during laser micro-drilling process of nanocomposites both in individual and multi-objective optimization.

• Advances in Computational Design
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• v.2 no.4
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• pp.333-348
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• 2017

Inspections of ancient metallic bridges have illustrated fatigue cracking in riveted connections. This paper presents a comparison between two alternative finite element (FE) models proposed to predict the fatigue strength of a single shear and single rivet connection. The first model is based on solid finite elements as well as on contact elements, to simulate contact between the components of the connection. The second model is built using shell finite elements in order to model the plates of the riveted connection. Fatigue life predictions are carried out for the shear splice, integrating both crack initiation and crack propagation lives, resulting from the two alternative FE models. Global fatigue results, taking into account several clamping stresses on rivet, are compared with available experimental results. Proposed comparisons between predictions and experimental data illustrated that the proposed two-stage model yields consistent results.

• Journal of Korean Elementary Science Education
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• v.34 no.1
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• pp.1-14
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• 2015

The variety of learners include students with disabilities and general students, and an ongoing focus of inclusive education research is non-discrimination. As part of integrated education, UDL (Universal Design for Learning) for students with disabilities supports a practical approach, participation, and advancement to improve learning opportunities for all students. The purpose of this study was to examine the effects of using UDL in science classes. The dependent variables of this study were academic achievement in science, scientific attitude, and scientific motivation. In this study, the experimental groups were 9 people in the 5th grade and 11 people in 6th grade. The experimental groups were taught science class using UDL. In order to analyze the learning outcomes, the structure equation model was performed. The results of this study were as follows: First, the science achievement of learning outcomes of the science class applying UDL directly affected both scientific attitude and scientific motivation. Second, the scientific attitude of learning outcomes of the science class applying UDL directly did not affect scientific motivation. According to these results, learning outcomes for science achievement of the science class applying UDL showed that UDL affected both general students and students with disabilities. To summarize the analysis of learning outcomes, science achievement directly affected both scientific attitude and scientific motivation while scientific attitude did not affect scientific motivation. This study offered a specific implementation method for integrated education. Using the structure equation model for analyzing the effect has more significance.