• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1411-1421
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• 1995

A rigid visco-plastic finite element method has been developed for modeling superplastic forming processes. The optimum pressure-time relationship for a target strain rate and thickness distributions was predicted using two-node line element based on membrane approximation for plane strain and axisymmetric condition. Analysis of superplastic forming was carried out using the developed program and the numerical results were compared to the values available in the literature for plane strain problems. For description of the contact between the dies and sheet, the direct projection method was applied to the complicated problem and the validity of the scheme was tested. Experiments for the various geometries such as hemisphere and cone were performed with the developed forming machine using the calculated optimum pressure-time curves. Comparison between analysis and experiments showed good agreement.

• Knowledge Management Research
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• v.20 no.2
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• pp.137-153
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• 2019

This study aim to identifying important determinants of happiness from university students' view point. To identify the determinants of happiness, focus group interviews were conducted. After carrying content analysis, five main categories were identified: 'Enjoying the present(enjoy the hobby, group activities and trivial things)', 'Self-regulation not dictated by anyone', 'Pursuing self-generated personal goals(goal-oriented, process-oriented)', 'Enjoying hassle-free moment(physical comport, psychological comforts being alone), 'Forming a good relationships (wide range of relationships, quality of relationships). This result is expected to provide deep understanding of students' happiness in planning programs and policies.

• Transactions of Materials Processing
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• v.21 no.6
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• pp.378-383
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• 2012

Laser forming is an advanced process in sheet metal forming in which a laser heat source is used to shape the metal sheet. This is a new manufacturing technique that forms the metal sheet only by a thermal stress. Analyses of the temperature and stress fields are very important to identify the deformation mechanism in laser forming. In this paper, temperature distributions and deformation behaviors of DP980 steel sheets are investigated numerically and experimentally. FE simulations are first conducted to evaluate the response of a square sheet in bending. The effects of process parameters such as laser power and scanning speed are then analyzed numerically and experimentally. It is observed that experimental and numerical results are in good agreement. These results provide a relationship between the line energy and the angles for laser bending of DP980 steel sheets.

• Journal of Korea Foundry Society
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• v.18 no.5
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• pp.481-487
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• 1998

Shell sand is widely used to make a complex shape castings due to its good collapsibility. When molten metal is poured into the mold, various gases are generated by the thermal decomposition of binder in the shell core. Casting defects such as blow hole and blister come from these gases. If it is possible to predict the evolution of gas quantitatively, it may provide effective solutions for minimizing the casting defects. To examine the gas evolution by shell core quantitatively, casting experiment and calculation were carried out. Gas pressure and gas volume evolved by shell core were measured in the experiment, and temperature distribution in the shell core was obtained by heat transfer analysis. From the result above, prediction on the gas volume evolved during pouring was tried. As forming pressure of the shell core increased and forming temperature decreased, the gas evolution increased. There was a close relationship between the calculated gas volume evolved and the measured one.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.1
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• pp.40-48
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• 1990

Bake hardenability of batch annealed steel sheets is investigated in connection with the amount of tensile deformation and the bake hardening condition. This study associates with the method for producing bake hardening materials by means of batch annealing process and for measuring bake hardenability which is not yet fully established. The experimental result demonstrates the relationship between strain distribution and bake hardening behavior in various bake hardening conditions, which provides an essential information for automobile design and related sheet metal forming in a press shop. The result also shows the bake hardenability of the tested material increases as the baking temperature is increased from 150.deg. C. The result assures the bake hardening materials can guarantee reasonably high strength as well as good uniformity in yield strength for the automobile body by sheet metal forming process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.2
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• pp.111-118
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• 1984

On the basis of plasticity theory for porous metal, an analysis of ring compression is carried out, employing the upper bound approach. The plastic flowability and the neutral radius of porous metal ring are calculated and deformation characteristics of power forging are obtained from this result. The experiments on ring compression are carried out for sintered iron porous metal with various relative densities under various friction conditions. A good agreement is observed between the shapes of the calculated curves and the experimental results from the ring compression test. The friction factor for powder metal forming can be determined not only from the relationship between reduction in height and reduction in internal diameter but independently from the relationship between reduction in height and relative density, if the initial relative density is known.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1613-1624
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• 2007

First impression is flexible that in a relationship it can be decided within four to ten seconds Therefore, to change the fixed image that has been formed at first impression requires lots of time and effect. Forming Rapo is one of a very important element in customer managing that form curiosity and credibility at first sight. This thesis is researched on Forming Rapo, which is important due to demand of change in business environment, to apply in the real market and increase the sale. The study applied on Enneagram that is proven to be the most effective tool for teach required passion and leadership within human personality system, and it explains nine different type of human personality. The used methodology was to set the hypothesis from selecting features that can be judged to apply on the sales field in the nine different type of personality. In addition, to support and prove the appliance of the hypothesis, one conduct the survey to 375 people, who found their personality type at KESI (Korea Enneagram Spiritual Institution).

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.12
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• pp.46-52
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• 1991

A new signal process circuit using two ISFETs as the input devices of the MOS differential amplifier stage for an ISFET biosensor has been developed. One chip integration of the newly developed signal process circuit, ISFETs and a Pt quasi-reference electrode has been carried out according to modified LOCOS p-well CMOS process. The fabricated chip showed gains of 0.8 and 1.6, good liniarity in the input-output relationship and very small power dissipation, 4mW. The chip was applied to realize a urea sensor by forming an immobilized urease membrane, using lift-off technique. on the gate of an ISFET. The urea sensor chip showed stable responses in a wide range of urea concentrations.

• Archives of Pharmacal Research
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• v.15 no.2
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• pp.169-175
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• 1992

Anti-inflammatory glucocorticoid (GC) derivatives have been clinically used in immune-malfunctional diseases for their immunosuppressive activity. However, there is still a lack of knowledge on the relationship between anti-inflammatory and immunosuppressive activities. In order to compare immunosuppressive activities with the known anti-inflammatory activities of the GC derivatives, eight clinically used GC derivatives including hydrocortisone, prednislone, 6$\alpha$-methyl prednisolone, triamcinolone, dexamethasone, betamethasone, triamcinolone acetonide and fluocinolone acetonide were selected, and lymphoblastosis inhibition and plaque-forming cell (PFC) response in mice were studied as immunological parameters. In Con A-induced lymphoblatosis inhibition invitro, all derivatives showed potent inhibition $IC_{50}$ values of the derivaties except methyl prednisolone and triamcinolone were less than $10^{-7}$M and good dose dependency was obtained. This result was well correlated with that of their anti-inflammatory potencies obtained. This result was well correlated with that of their anti-inflammatory potencies and their receptor binding affinities. However, in PFC response, consistent result were not obtained. Total numbers of PFCs per spleen were decreased by some derivatives, but numbers of PFCs per $10^6$ cells were not decreased by systemic administration of but numbers of PFCs per $10^6$ cells were not decreased by systemic administration of GC at the dose of 0.05 mg/mouse. Furthermore, at the dose of 0.1 mg/mouse, numbers of PFCs per $10^6$ cells were found to be increased, although total PFCs per spleen were decreased.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.199-202
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• 2004

In this present study, an attempt was made to determine the deformation mode of the Zr-Ti-Cu-Ni-Be bulk metallic glass by compression test over a wide range of temperatures and strain rates. From the results, empirical deformation map could be constructed including the boundaries of different deformation modes. Considering power dissipation map and instability map developed on the basis of the Dynamic Materials Model (DMM), the processing map for extrusion could also be constructed. In addition, the macroscopic formability of this BMG alloy has also been examined through the extrusion in laboratory scale within undercooled liquid state. From the results of macroscopic extrusion formability, both deformation map and processing map present good criteria to determine optimal forming conditions.