• Transactions of Materials Processing
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• v.7 no.3
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• pp.260-273
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• 1998

A new blank design method is proposed to predict the optimum initial blank shape in the sheet metal forming process. The rollback method for blank shape design takes the difference between final deformed shaped and target contour shape into account. Based on the method a computer program composed of blank design module FE-analysis program and mesh generation module is developed. The rollback method is applied to square cup drawing process with the flange of unifiorm size around its periphery to confirm its validity. The optimum initial blank shape is obtained from an arbitrary square blank after three modification. Good agreements are recognized between the numerical results and the published results for initial blank shape and thickness strain distribution. The optimum blank shape for two parts of automobile sub-frame is designed, The thickness distribution and the level of punch load is improved. Also the method is applied to design the weld line in the tailor-welded blank. It is concluded that the rollback method is an effective and convenient method for an optimum blank shape design.

• Transactions of Materials Processing
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• v.8 no.4
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• pp.374-383
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• 1999

To determine the flow stress of semi-solid materials, a new combined method has been studied by experimental and analytic technique in the current approach. Using backward extrusion experiment and its numerical analysis, the characterization scheme of semi-solid materials according to the change of initial solid volume fraction has been proposed. Because that solid volume fraction is sensitive to temperature change, it is required to precisely control the temperature setting. Model materials can guarantee the establishment of material characterization technique from the noise due to temperature change. Thus, clay mixed with bonded abrasives was used for experiment and the change of initial solid fraction was copied out through the variation of mixing ratio. Upper bound method was adapted to increase in efficiency of the calculation in numerical analysis and new kinematically admissible velocity field was employed to improve the accuracy of numerical solution. It is thought that the material characterization scheme proposed in this study can be applied to not only semi-solid materials, but also other materials that is difficult to obtain the simple stress state.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.1 s.244
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• pp.32-41
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• 2006

We analyzed the non-Newtonian and non-isothermal flow in the melt conveying zone in co-rotating and counter-rotating screw extruder system with the commercial code, STAR-CD, and compared the mixing performance with respect to screw speed and rotating direction. The viscosity of fluid was described by power-law model. The dynamics of mixing was studied numerically by tracking the motion of particles in a twin screw extruder system. The extent of mixing was characterized in terms of the residence time distribution and average strain. The results showed that high screw speed decreases the residence time but increases the shear rate. Therefore higher screw speed increases the strain and has better mixing performance. Counter-rotating screw extruder system and co-rotating screw extruder has the similar shear rate with the same screw speed in spite of different rotating direction. However, the counter-rotating screw has good mixing performance, which is resulted from longer residence time than that of co-rotating screw extruder.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.581-584
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• 2005

A district heating(DH) system supplies environmentally-friend heat and is appropriate for reduction of energy consumption and/or air pollutions. The objectives of this paper are to systematize data processing of transition temperature, investigate its effects on fatigue life of DH pipes and optimization for size of DH pipes. A relational database management system as well as reliable fatigue life evaluation procedures is established for Korean DH pipes. Also, since the prototypal evaluation results satisfied both cycle-based and stress-based fatigue criteria. Through the optimum design process, the cross section diminished 18.64% and the CUF diminished 23.35%. So, it can be used as useful information in the future for optimal design, operation and energy saving via setting of efficient condition and stabilization of water temperature.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2954-2966
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• 1994

The characteristics and good corrosion resistance at room and elevated temperatures led to increasing application of Ti-alloys such as aircraft, jet engine, turbine wheels. In forging of Ti-alloy at high temperature, die chilling and die speed should be carefully controlled because the flow stress of Ti-alloy is sensitive to temperature, strain and strain-rate. In this study, the forging of turbine disk was numerically simulated by the finite element method for hot-die forging process and isothermal forging process, respectively. The effects of the temperature changes, the die speed and the friction factor were examined. Also, local variation of process parameters, such as temperature, strain and strain-rate were traced during the simulation. It was shown that the isothermal forging with low friction condition produced defect-free disk under low forging load. Consequently, the simulational information will help industrial workers develope the forging of Ti-alloys including 'preform design' and 'processing condition design'. It is also expected that the simulation method can be used in CAE of near net-shape forging.

• Journal of Korean Physical Therapy Science
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• v.2 no.1
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• pp.413-422
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• 1995

The trigger point phenomenon is an extremely common syndrome in physical therapy room. The symptoms created by these syndromes may be interpreted as originating in discogneic disease, nerve entrapment syndromes, viscerosomatic pain, and certain myalgic pain of unknown etiology. Injuries, viral or bacterial infections, immobilization, psychogenic stress, and other environment factors can preciptate and perpetuate these syndromes, which may occur in any of the voluntary muscles of the human body and thus lead to a multitude of myofascial pain syndromes. Obviously symptomatic treatment can meet with only partial success. Knowledge of the trigger point phenomenon will aid the diagnostician in understanding otherwise in explicable symptom. The trigger point are $2{\sim}5mm$ in diameter, hyperirritable palpable taut in a tissue, when compressed, is locally tender, if sufficiently hypersensitive, give rise to referred pain and tenderness, and sometimes to referred automatic phenomena and distortion of proprioception. The treatment of myofascial trigger point pain syndrome is not difficult once the source of the problem has been determined. Where as many modalities may be used, two of the most effective are spray-and stretch and TP injection. These can be followed by deep massage, specific, manual resistive exercise, and an exercise program which the patient can follow at home. The goal of management is to inactivate the TPs and to restore shortened and stretch resistent muscles to their full range of motion. The purpose of this case study was to know about the pathophysiologic mechanism of the trigger point and will enable to physical therapist to direct his treatment to the real source of trouble.

• Journal of the Korean housing association
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• v.24 no.6
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• pp.123-132
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• 2013

This study covers centrality of villas after Renaissance and architectural forms corresponding to the nature in the aspect of Karl Popper and Gilles Deleuze. In addition, the researcher tries to understand the changes in architectural forms according to the changes in places. To do that, Pascal and Hans Meyer's theory was introduced as a major theory. The researcher tries to set up the standard by analyzing the architectural form related with the nature and the form of center in the housing through Villa Rotonda and Villa Emo. And with key analysis of the centrality and architectural form corresponding to the nature and the four houses that are historically and morphologically important. It is found that due to the development in modern technology and materials, a variety of architectural approach is developed and they are implemented as various architectural forms. However, due to various theories of modern architectural approach, it is found that the morphological differences of suburban housing exists by forming a universal relationship constructed by four architects. The researcher expects to be understood and realized in real life construction.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.185-195
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• 1998

A new blank design method is proposed to predict the optimum initial blank shape in the sheet metal forming process. The rollback method for blank shape design takes the difference between final deformed shape and target contour shape into account. Based on the method, a computer program composed of blank design module, FE-analysis program and mesh generation module is developed. The rollback method is applied to square cup drawing process with the flange of unifiorm size around its periphery to confirm its validity. The optimum initial blank shape is obtained from an arbitrary square blank after three modifications. Good agreements are recognized between the numerical results and the published results for initial blank shape and thickness strain distribution. The optimum blank shape for two parts of automobile sub-frame is designed. The thickness distribution and the level of punch load is improved. Also, the method is applied to design the weld line in the tailor-welded blank. It is concluded that the rollback method is an effective and convenient method for an optimum blank shape design.

• Physical Therapy Korea
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• v.6 no.3
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• pp.94-109
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• 1999

The purposes of this study were to assess the effect of therapeutic exercise and to offer an approach to the physical therapy and rehabilitation procedure of the temporomandibular joint (TMJ) following surgery. In this research, 42 patients with TMJ surgery were assigned one of two groups. The experimental group included 21 patients who performed therapeutic exercise, and the control group included 21 patients who did not perform therapeutic exercise. Conservative therapy such as an ice pack, a hot pack, and pulsed ultrasound was applied to both groups. Treatment was applied twice a day during the admission period and, after discharge, everyday for six weeks. Visual analogue scale (VAS), incisal biting force, and joint ROM were measured before surgery and at 30 days after surgery. The results were as follows: VAS (p<0.05), mouth opening (p<0.01), lateral excursion to unaffected side (p<0.05), and protrusion (p<0.05) between experimental group and control group showed statistically significant differences. Incisal biting force and lateral excursion to affected side between experimental group and control group showed no statistically significant difference.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.1
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• pp.90-100
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• 1999

The Fallingwater, one of Wright's best designs, is known as a good example of "Organic Architecture". Its landscape characteristics are harmonious relationship between architecture and landscape, adaptable siting, composition of spatial and visual structure, floating spaceness, interlocking of water and house, dramatic approach, and vernacular material use. This characteristics had begun from the Prairie architecture, but also had influenced by the culture and art of the Far East. He was open to foreign cultures. Staying in Japan for years, he had travelled China, too. In this process, he might be exposed to Korean art and culture which were under Japan at that time. Comparing the front image of the Songkwang Temple to that of the Fallingwater, their compositions between architecture, water, and landscape are so similar to each other. They are also close to each other in terms of spatial structure. Therefore the landscape characteristics found in the Fallingwater design are more similar to Korean landscape architectural characteristics than Japanese ones. Therefore we are going to suggest the hypothesis that Wright is influenced by Korean landscape design in the design of the Fallingwater. Considering his impact upon the design world, it will be significant if the concept of Korean traditional landscape design is placed behind his design of the great architecture.hitecture.