• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.42-45
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• 2007

Recrystallization behavior during ingot-breakdown process of Alloy 718 was investigated with finite element analysis and experimental approaches. In order to analyze microstructural changes during the cogging process of an Alloy 718 ingot, the side-pressing and heat treatment tests were performed at different temperatures and ram speed. From the side-pressing and heat treatment test results, it was found that microstructural changes during hot forging of Alloy 718 ingot greatly influenced on a close interaction between dynamic and static-recrystallization behaviors. A recrystallization model of Alloy 718 was used to predict the complex microstructural variation during continuous heating and forging processes of the cogging, and the predicted grain size and its distribution were compared with the actual cogged Alloy 718 billet.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.741-743
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• 2000

In this paper the relationship between the pressing force applied to rotors and the characteristics of ultrasonic motor are discussed. The characteristics of ultrasonic motor using a piezoelectric vibrator were systematically studied. And these were applied to the construction of a card forwarding device. The principle of ultrasonic motor is to use an elliptical motion generated on the side of the vibrator, and the elliptical motion of the ultrasonic motor was obtained by complex oscillation of $L_1-B_4$ mode. As the experimental results. the forwarding speed of the card increased linearly as the pressing force applied to rotors increased. The forwarding speed of the card was 16.0 cm/s when the pressing force applied to rotors was 1 N. The forwarding force of the card increased linearly as the pressing force applied to rotors increased. The forwarding force of the card was 398 mN when the pressing force applied to rotors was 1 N. Therefore, this ultrasonic motor can be expected to be used for card-forwarding device and so on.

• Transactions of Materials Processing
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• v.4 no.3
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• pp.267-281
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• 1995

Preform design is one of the critical fields in metal forming. The finite element method(FEM) has been effective in designing preforms and process sequence, for which the backward tracing scheme of the rigid-plastic FEM has been explored. In this work a program using the backward tracing scheme by the rigid-plastic FEM is developed for three-dimensional plastic deformation, which is an extension of the scheme from two-dimensional cases. The calculation of friction between workpiece and die, and handling of boundary conditions during backward tracing require sophisticated treatment. The developed program is applied to upsetting of a rectangular block and to side pressing of a cylindrical workpiece. The results of the two applications show feasibility of the program on three-dimensional plastic deformation.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.433-435
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• 2005

We have studied the realigning behavior of liquid crystal molecules in liquid crystalline polymer/liquid crystal(LCP/LC) system when they are exposed to external stimulation such as bending and pressing. The birefringence of the LCP/LC in a flexible display device was measured as a function of bending or pressing deformation. The microscopic dynamic behavior of main chain, side chain, and the LC were characterized by FTIR and polarization optical microscopy. When the device is deformed in scattering memory state, liquid crystal(LC) director is found to align from randomly oriented domain state(scattering state) to homeotropic state.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1539-1545
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• 2003

A lot of researches have been performed on the equal channel angular pressing (ECAP) which produces ultra-fine grains. Along with the experiments, the finite element method has been widely employed to investigate the deformation behavior of specimen during ECAP and the effects of process parameters of ECAP. In this paper, pure-Zirconium is considered for ECAP process by using three-dimensional finite element analysis. The results have been compared with those of previous two-dimensional analysis and with the experimental results

• Transactions of Materials Processing
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• v.20 no.2
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• pp.110-117
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• 2011

The purpose of this work is to develop of a press forming process for mobile phone battery cover as an alternative to the current manufacturing process by laser welding. This press forming process consists of a combination of bending, side pressing and side bending operations. The dimensional error for each process was investigated by finite element(FE) analysis and the Taguchi optimization method. The spreading of the cover width in the side pressing process was adjusted by modifying the blank shape with a notch. The over-bending method was adopted to compensate the spring-back which occurs after bending. Forming experiments were performed to verify the reliability of the developed press forming process. In addition, the strength of the product was evaluated to verify the suitability of the battery cover manufactured with this new press forming process. The results of the forming experiments indicate that the dimensional accuracy of the battery cover is within the required tolerance. The strength of the battery cover was evaluated to 547N which is larger than required strength of 400N.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.69-74
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• 2008

The heat generated by the brake system of vehicles results in reduction of friction force on the brake surface and vibration during a braking. To solve these problems, extensive research for the brake shape has been conducted such as drilling cooling holes on the brake disc, accommodating ventilated holes and etc. In this study, we suggest the circumferential pressing type brake disc in order to improve its cooling performance. In order to compare the cooling-down efficiency between the conventional side-pressing type and the circumferential-pressing type, we adopted the FMVSS 105-77 as thermal analysis conditions and This newly proposed concept has been verified using Thermal-structure Coupled Field Analysis along with comparative analysis with the existing ventilated disk.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.661-665
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• 2002

A lot of investigations have been made in recent years on the equal channel angular pressing (ECAP) which produces ultra-fine grains. The finite element method has been used to investigate this issue. In this paper, pure-Zirconium is considered far ECAP process by three dimensional finite element analysis. The effects of fiction on the deformation behavior have been investigated and compared with two dimensional finite element analysis.

• The Journal of Dong Guk Oriental Medicine
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• v.8 no.2
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• pp.155-173
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• 2000

The diagnosis in Oriental medicine is done by inspection, auscultation and olfaction, interrogation, four diagnostics of pulse feeling and palpation, and various system of identification like identification according to Qi(vital energy), Xue and body fluids, identification according to fair principles, identification according to principles of Wei, Qi, Ying and Xue, identification according to Sanjiao(the triple heater), identification according to four type physical constitution. Sometimes, symptoms and diagnosis techniques according to symptoms is selectively applied for the diagnosis. Among them the pulse feeling and palpation diagnosis technique using the sense of finger and palm of the hand is divided into feeling of pulse and palpation and pressing maneuver. Pressing maneuver is a diagnosis technique pressing and rubbing the affected part in order to attain data of identification including inside and outside condition of the body with regard to the nature, condition and relative seriousness of disease. There are palpation of the skin, palpation the hand and foot, palpation the chest and the abdomen, palpation shu points in pressing maneuver. The diagnosis of the Back Shu points is a technique to examine the change of disease condition from pressure ache, spontaneous ache, tension, relaxation, solidification revealed through channels and collaterals. I investigates starting disease and an attack of disease of twelve pulse and pulse condition through the study relative to the substance and technique of pressing maneuver, and adjusts diagnosis techniques of a region for acupuncture and matters to be attended. The conclusions are as follows. 1. The Shu or stream points in which pathogenic factors go are important to medical treatment of dormant diseases like bowels disease, cold symptom complex and insufficiency symptom complex. 2. Disease classified by system is diagnosed by the condition of process part like pro-trusion, cave-in, tension, relaxation, pressure ache through palpating the Shu or stream points, that is pressing upward or downward left and right sides of the backbone process by hands. 3. In real clinic pressing maneuver of one's back side is very important to patient's diagnosis treatment. Thus, pressing maneuver of one's back side have to be done without omission. 4. Diagnosis must be accomplished through the perception about the diversity of diagnosis technique of bowels disease, the exact knowledge about pressing maneuver of one's back side for enlargement of treatment range and rising of treatment rate, and pressing maneuver of the Shu or the stream points.

• Progress in Superconductivity and Cryogenics
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• v.19 no.3
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• pp.27-32
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• 2017

The effects of artificial holes on the trapped magnetic fields and magnetic levitation forces of very large single-grain $Y_{1.5}Ba_2Cu_3O_{7-y}$ (Y1.5) bulk superconductors were studied. Artificial holes were made for Y1.5 powder compacts by die pressing using cylindrical dies with a diameter of 30 mm or 40 m, or rectangular dies with a side length of 50 mm. The single grain Y1.5 bulk superconductors (25 mm, 33 mm in diameter and 42 mm in side length) with artificial holes were fabricated using a top-seeded melt growth (TSMG) process for the die-pressed Y1.5 powder compacts. The magnetic levitation forces at 77 K of the 25 mm single grain Y1.5 samples with one (diameters of 4.2 mm) or six artificial holes (diameters of 2.5 mm) were 10-17% higher than that of the Y1.5 sample without artificial holes. The trapped magnetic fields at 77 K of the Y1.5 samples with artificial holes were also 9.6-18% higher than that of the Y1.5 sample without artificial holes. The 33 mm and 42 mm single grain Y1.5 samples with artificial holes (2.5 mm and 4.2 mm in diameter) also showed trapped magnetic fields 10-13% higher than that of the Y1.5 samples without artificial holes in spite of the reduced superconducting volume fraction due to the presence of artificial holes. The property enhancement in the large single grain Y1.5 bulk superconductors appears to be attributed to the formation of the pore-free regions near the artificial holes and the homogeneous oxygen distribution in the large Y123 grains.