• Journal of Welding and Joining
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• v.27 no.5
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• pp.88-93
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• 2009

While the pinch instability theory (PIT) has been widely employed to analyze the spray transfer mode in the gas metal arc welding (GMAW), it cannot predict the detaching drop size accurately. The PIT is modified in this work to increase the accuracy of prediction and to simulate the molten tip geometry to be more physically acceptable. Since the molten tip becomes a cone shape in the spray mode, the effective wire diameter is formulated that the effective diameter is inversely proportional to current square. Modifications are also made to consider the finite length of the liquid column and current leakage through the arc. While the effective diameter influences drop transfer significantly, the current leakage has negligible effects. The effects of modifications on drop transfer are analyzed, and the predicted drop diameters show good agreements with the experimental data of the steel wire.

• Journal of computational fluids engineering
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• v.17 no.3
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• pp.33-38
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• 2012

The droplet ejection behavior from drop-on-demand printhead are investigated numerically for Newtonian and shear-thinning fluid. The numerical simulation is performed using a volume-of-fluid model. In this study, we compare the printable range in terms of Z number and pinch-off time for Newtonian and shear-thinning fluids. The printability range are found to be 1.08 $$\leq_-$$ Z $$\leq_-$$ 12.9 for Newtonian fluid and 0.8 $$\leq_-$$ Z $$\leq_-$$ 12.9 for shear-thinning fluid. However, air entrainment is observed during merging of primary and satellite droplet within the printability range. The pinch-off time of the shear-thinning fluid is apparently shorter compared to the corresponding Newtonian fluid due to shear-thinning effects and the differences in the pinch-off time is enlarged significantly when the capillary number is larger than 0.5.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.44-44
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• 2009

While the pinch instability theory (PIT) has been widely employed to analyze the spray transfer mode in the gas metal arc welding (GMAW), it cannot predict the detaching drop size accurately. The PIT is modified in this work to increase the accuracy of prediction and to simulate the molten tip geometry to be more physically acceptable. Since the molten tip becomes a cone shape in the spray mode, the effective wire diameter is formulated that the effective diameter is inversely proportional to current square. Modifications are also made to consider the finite length of the liquid column and current leakage through the arc. While the effective diameter influences drop transfer significantly, the current leakage has negligible effects. The effects of modifications on drop transfer are analyzed, and the predicted drop diameters show good agreements with the experimental data of the steel wire.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.108-108
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• 2010

We have generated Ne-Xe plasma in dense plasma focus device with hypocycloidal pinch for extreme ultraviolet (EUV) lithography and investigated an electron temperature. We have applied an input voltage 4.5 kV to the capacitor bank of 1.53 uF and the diode chamber has been filled with Ne-Xe(30%) gas in accordance with pressure. If we assumed that the focused plasma regions satisfy the local thermodynamic equilibrium (LTE) conditions, the electron temperature of the hypocycloidal pinch plasma focus could be obtained by the optical emission spectroscopy (OES). The electron temperature has been measured by Boltzmann plot. The light intensity is proportion to the Bolzman factor. We have been measured the electron temperature by observation of relative Ne-Xe intensity. The EUV emission signal whose wavelength is about 6~16 nm has been detected by using a photo-detector (AXUV-100 Zr/C, IRD) and the line intensity has been detected by using a HR4000CG Composite-grating Spectrometer.

• Computational Structural Engineering
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• v.8 no.4
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• pp.159-171
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• 1995

The parameters describing a complete hysteresis loop include pinch force, drift offset, effective stiffness, unloading and reloading trangential stiffness. Analytical equations proposed to quantify the nonlinear, inelastic behavior of reinforced shear walls can be used to predict these parameters as a function of axial load and drift ratio. For example, drift offset, effective stiffness, and first and second unloading and reloading tangential stiffness are calculated using equations obtained from test data for a desired drift ratio or ductility level. Pinch force can also be estimated for a given drift ratio and axial load. The effective virgin stiffness at the first yield and its post yield reduction can be estimated. The load deflection response of flexural reinforced concrete shear walls can now be estimated based on the effective wall stiffness that is a function of axial force and drift ratio.

• Journal of Korean Biological Nursing Science
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• v.16 no.1
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• pp.1-7
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• 2014

Purpose: This research was implemented for men in their thirties who have lower back pain to observe general activity disorder patterns during pinch lift and rubbing manual therapy (PMT) and stretching application. Methods: Participants were divided into three groups: The PMT Group used applied pinch lift and rubbing manual therapy; the STR Group used applied stretching; and the CON Group was the control group. Participants for each group received treatments that were conducted three times a week for a total five weeks. Measures of pain utilized Visual Analogue Scale (VAS) [INCOMPLETE SENTENCE]. Results: There were significant differences between the PMT Group and the CON Group as well as the STR Group and the CON Group for pain, muscle strength and flexibility. There was a significant difference in pain between the PMT Group and the STR Group. Conclusion: As a result, it is inferred that PMT and stretching positively influenced recovery with regards to pain, muscle strength and flexibility relief; however PMT is more effective for pain relief than stretching.

• Tuberculosis and Respiratory Diseases
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• v.63 no.5
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• pp.449-453
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• 2007

Totally implanted central venous access devices for chemotherapy (chemoport) are being used increasingly in lung cancer patients. Vascular catheters are associated with various complications including infection, thrombosis as well as spontaneous fractures and embolization of the catheter, which is known as 'pinch-off syndrome'. 'Pinch-off syndrome' refers to the compression of a subclavian central venous catheter between the clavicle and first rib resulting in an intermittent or permanent obstruction, which can lead to tears, transection, or embolization. We report two cases of fractured and embolized implanted subclavian venous catheters in which the fragments were removed percutaneously. A 62-year-old man presented with back pain with a duration of a few weeks. The chest radiograph revealed complete transsection and embolization of the catheter into the right atrium. In addition, a 47-year-old woman with a chemoport had a grade 3 pinch-off sign in a chest radiograph demonstrating complete transsection and embolization of the catheter into the pulmonary artery. Both cases were managed by retrieving the embolized distal fragment percutaneously and removing the proximal section of the catheter.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.9
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• pp.961-976
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• 2006

Designing water-reuse network which can reduce the fresh water within the process and increase the water-use efficiency by scientific and systematic analysis is recently interested in the industries. Water systems often allow efficient water uses via water reuse and recirculation in the paper, petrochemical, and steel industries which necessitate a lot of freshwater within the process. Defining network layout connecting water-using process is frequently accomplished by using water pinch technology which optimizes freshwater entering the process and also reduces the wastewater. In this review, recent researches and case studies of water pinch technology which can find the bottleneck of the water stream at the water reuse designing stage are introduced. Necessity of water pinch technology is illustrated by examples of real industries. Recent studies on simultaneous energy and water minimization and water-reuse network among industries in eco-industrial park(EIP) are also introduced.

• Korea-Australia Rheology Journal
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• v.18 no.2
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• pp.41-49
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• 2006

A modified Volume-of-Fluid (VOF) numerical method is used to predict the dynamics of a liquid drop of a low viscosity dilute polymer solution, forming in air from a circular nozzle. Viscoelastic effects are rep-resented using an Oldroyd-B model. Predicted drop shapes are compared with experimental observations. The main features, including the timing of the shape evolution and the 'bead-on-a-string' effect, are well reproduced by the simulations. The results confirm published conclusions of the third author, that the deformation is effectively Newtonian until near the time of Newtonian pinch-off and that the elastic stress becomes large in the pinch region due to the higher extensional flow there.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.376-379
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• 1996

Synthesis for qualitative analysis in connection with quantitative analysis from the pinch design method, EVOP and Operations Research is proposed for the optimal synthesis of heat exchanger networks, that is through of the transportation model of the linear programming for synthesizing chemical processing systems, to determine the location of pinch points, the stream matches and the corresponding heat flowrate exchanged at each match. In the second place, according to the optimization, the optimal design of heat transfer enhancement is carried on a fixed optimum heat exchanger network structure, in which this design determines optimal operational parameters and the chosen type of heat exchangers as well. Finally, the method of this paper is applied to the study of the optimal synthetic design of heat exchanger network of constant-decompress distillation plants.