• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2458-2467
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• 1996

The rigid-plastic finite element analysis was performed for analysis of ofhot forging and cold sizing of a bevel gear. Two dimensional analysis was carried out to investigate the defect occurrence on vertical symmetric planes during hot forging and three dimensional analysis was to understand the filling behavior on horizontal planes during cold sizing. The involute curve of a tooth was approximated by a circle for convenience in the present analysis. In order to estimate the elastic deformation of the gear and dies during cold sizing, linear elastic finite element analysis was performed. Results of the analysis can be used to predict grain flows and strength distributions in the forged gear, and to design dies and an appropriate preform for the cold sizing.

• Korean Institute of Interior Design Journal
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• v.21 no.2
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• pp.74-83
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• 2012

This study is an historical consideration about the modern discourse of Japanese spacial tradition driven from cultural background. The purpose of this study is to establish a cartographic map of historical progress, and to shed light on the forming of identity in Japanese traditional space design on the schizo-analytical aspect. It adopts F. Guattari's psychoanalytic theory to the structural analysis of Japanese traditional space design. The process of this study is illustrated as follows: At first, it mentions Guattari's theory of Mechanical Unconscious, Schizo-analysis, Cartography, and Abstract machine as theoretical background. And, it considers the identity of Japanese traditional space constructed by various cultural sign over a long period of time as the statement of apriority. Secondly, it clarifies semiologic generation of Japanese traditional space design based on the analysis of spacial morphemes about each design stemmed from modernization process of Japan. Thirdly, it ascertains semiologic topography the representamens draw, i.e. schizo-analytic cartography from synchronic and diachronic point of view. Fourthly, it analyses traditional discourse structure in terms of generative schizo-analysis and transformational schizo-analysis with four categories- object, style, concept, strategy. Through this process, it studies the reproduction of Japanese tradition in terms of the 'social organization', and explores the way vitalized on the space-time coordinate system by the schizo-analysis of the mechanical unconscious. In conclusion, it clarifies Generative-schizo is accomplished in the level of formulating representamen, and Transformational-Schizo involves experimental mind that induce implantation of the heteromorphic elements and avant-garde experiments of abstract mechanical operation in the schizo-analysis of Japanese traditional space design. The significance of this study is to arrange an opportunity of introspection on Korean-ness seriously from inspecting logic of Japan-ness closely in traditional space design.

• Journal of the Korean Wood Science and Technology
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• v.45 no.6
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• pp.772-786
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• 2017

This study investigated the characteristics of wood tar, produced as a byproduct during the production of charcoal using oak wood by the modified traditional kiln and mechanical steel kiln. The wood tar was analyzed with a number of techniques, including Py-GC/MS, NMR, MALDI-TOF, FT-IR, TG and DSC. The Py-GC/MS analysis indicated that modified traditional kiln generated a higher hydrocarbon ratio in the wood tar than that of mechanical steel kiln. On the other hand, mechanical steel kiln resulted in a higher proportion of phenolic and aromatic hydrocarbon components than that of modified traditional kiln. Those results were also confirmed by NMR analysis. The MALDI-TOF analysis suggested that the wood tar produced in the mechanical steel kiln had a slightly higher molecular weight than the wood tar produced in the modified traditional kiln. In addition, the FT-IR analysis showed characteristic peak of symmetrical stretching vibration of $CH_3$ from the modified traditional kiln while characteristic peaks of the C-C and C-O stretching vibration were observed from the mechanical steel kiln. Moreover, TG and DSC analysis suggested that the mechanical steel kiln is more thermally stable than that of modified traditional kiln. Those findings clearly showed that the method of making charcoal greatly affects the properties of wood tar.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.1
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• pp.91-104
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• 2008

In tunnels, safety factor concept has been suggested to estimate their stability quantitatively. It is merely limited in the framework of mechanical analysis. However safety factor concept has not been applied in hydro-mechanical coupled analyses due to their modelling complexity. Recently studies on this topic are being actively made. In this study, induced drainage modelling methods for hydro-mechanical coupled analyses are compared and analyzed to estimate safety factor of a subsea tunnel exactly. To this end, methods both controlling hydraulic characteristic of shotcrete and using a drainage well are considered. Sensitivity analysis were carried out on rock class, thickness of shotcrete, and hydraulic properties of rock mass. As the results of this study, it turned out that the induced drainage modelling using a drainage well would give more reliable results than that of controlling hydraulic characteristic of shotcrete in estimating tunnel stability in hydro-mechanical coupled analyses.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1535-1542
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• 2012

A Heat Recovery Steam Generator(HRSG) is the main component of a Combined Cycle Power Plant(CCPP). It is a very large structure that is made from relatively thin metal sheets. Therefore, the structural integrity of an HRSG is very important to ensure safe operation during plant lifetime. In particular, thermal deformation and thermal fatigue have been revealed as the main causes of the mechanical degradation of an HRSG. In order to prevent unexpected damage, safety evaluation based on a large-scale analysis is necessary. Therefore, this study aims to improve the safety of HRSG by using Finite Element Analysis(FEA) results derived from large-scale analysis. Furthermore, the modified design is verified by comparing it with the original one. This result will be used as basic data for improving the safety of a vertical-type HRSG.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.5
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• pp.529-535
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• 2012

This paper deals with the determination of mechanical properties of various galvanized steel sheets that are used for fabricating automobile bodies; the instrumented indentation technique and finite element analysis were used for the determination. First, tensile tests were conducted to obtain the true stress-true strain curves of galvanized steel sheets with various thicknesses. Load-deformation curves were then obtained by using the instrumented indentation testing machine, and they were compared with load-deformation curves obtained by finite element analysis. Further, true stress-true strain curves were obtained at the optimal observation point by finite element analysis.

• Journal of Hydrogen and New Energy
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• v.28 no.5
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• pp.521-530
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• 2017

Improving the microstructure of NiO/YSZ is one of several approaches used to enhance the electrical and mechanical properties of an anode support in Solid Oxide Fuel Cells (SOFCs). The aim of the work reported in this paper was to predict the relationship between these microstructural changes and the resulting properties. To this end, modification of the anode microstructure was carried out using different sizes of Poly (Methyl Methacrylate) (PMMA) beads as a pore former. The electrical conductivity and mechanical strength of these samples were measured using four-probe DC, and three-point bend-test methods, respectively. Thermal etching followed by high resolution SEM imaging was performed for sintered samples to distinguish between the three phases (NiO, YSZ, and pores). Recently developed image analysis techniques were modified and used to calculate the porosity and the contiguity of different phases of the anode support. Image analysis results were verified by comparison with the porosity values determined from mercury porosimetry measurements. Contiguity of the three phases was then compared with data from electrical and mechanical measurements. A linear relationship was obtained between the contiguity data determined from image analysis, and the electrical and mechanical properties found experimentally. Based upon these relationships we can predict the electrical and mechanical properties of SOFC support from the SEM images.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1361-1370
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• 2006

An electronic beam mis-landing phenomenon on the RGB (red/green/blue) -fluorescent surface has been considered as one of serious problems to be solved in cathode-ray tube (CRT), which is generally caused by mechanical shock and vibration. In this work, structural design concepts on the major parts of the CRT, such as a frame, a shadow mask, and a spring, are studied to improve the mechanical shockproof character of a CRT by FEM-analyses and experimental approaches ; a frame is newly designed to have strength employing the double-corner-beads which reduces considerably the distortion of the frame and the shadow mask : the edge-bead of a shadow-mask is redesigned to maintain the wide curved surface of a shadow-mask after mechanical shock : finally, a spring supporting the frame and the shadow-mask is designed to have enough flexibility along drop-direction. As an example, a conventional type of a 15inch CRT was utilized to demonstrate the feasibility and usefulness of this work. Overall, some favorable information on the structural design of the CRT is achieved, and the mechanical shockproof character of a 15-inch CRT is improved in the degree of 3G $(1G=9.81m/s^2)$ as an average-value.

• Journal of Magnetics
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• v.19 no.3
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• pp.300-308
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• 2014

This paper develops a moving-magnet electromagnetic actuator for fast steering mirror (FSM). The actuator achieves a reasonable compromise between voice coil actuator and piezoelectric actuator. The stroke of the actuator is between the strokes of a piezoelectric actuator and a voice coil actuator, and its force output is a linear function of air gap and excitation current within our FSM travel range. Additionally, the actuator is more reliable than voice coil actuator as the electrical connection in the actuator is static. Analytically modeling the actuator is difficult and time-consuming. Alternatively, numerous finite element simulations are carried out for the actuator analysis and design. According to the design results, a real prototype of the actuator is fabricated. An experimental test system is then built. Using the test system, the force output of the fabricated actuator is evaluated. The test results validate the actuator analysis and design.

• Journal of Magnetics
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• v.19 no.2
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• pp.130-139
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• 2014

This paper focuses on the modeling and analysis a novel two-axis rotary normal-stress electromagnetic actuator with compact structure for fast steering mirror (FSM). The actuator has high force density similar to a solenoid, but its torque output is nearly a linear function of both its driving current and rotation angle, showing that the actuator is ideal for FSM. In addition, the actuator is designed with a new cross topology armature and no additional axial force is generated when the actuator works. With flux leakage being involved in the actuator modeling properly, an accurate analytical model of the actuator, which shows the actuator's linear characteristics, is obtained via the commonly used equivalent magnetic circuit method. Finally, numerical simulation is presented to validate the analytical actuator model. It is shown that the analytical results are in a good agreement with the simulation results.