• Journal of the Korean Society for Heat Treatment
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• v.31 no.6
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• pp.290-299
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• 2018

The microstructure of a newly developed alloy tool steel (KV1) for casting cold-work press dies was analyzed using advanced scanning electron microscopy. Its mechanical properties and durability in use as piercing inserts were tested. It contained a continuous network structure which originated from the micro-segregation during solidification and was composed of retained austenite and primary carbides. However, after quenching and tempering, its continuity was destroyed due to the decomposition of austenite. The discontinuous spatial distribution and the smaller amount of primary carbide in the network presented KV1 enhanced ductility compared to the common alloy (HK700). The reduced C and Cr, the addition of V resulted in a small amount of primary carbides which primarily consisted of MC, as well as fine and uniform dispersion of precipitates. Owing to these features, KV1 exhibited delayed initiation of chipping when used for piercing inserts.

• Journal of Chest Surgery
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• v.9 no.2
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• pp.245-250
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• 1976

A 33 year-old man was admitted with chief complaints of severe sharp pain on left upper interscapular region and motor weakness of left arm for 9 days. He had a history of blunt trauma over left shoulder about 3 years ago. Physical examination showed a ping pong ball sized mass which was located at the left supraclavicular area and was firm, fixed, and nonpulsatile. No bruit or murmur was obtained over the mass. Ipsilaterally, radial, ulnar, and brachial pulse were very weak and ptosis and anhidrosis were noticed. Neurologic examination revealed moderate or severe weakness of flexion and extension of left elbow, wrist and fingers, and anesthesia of the skin in left C8-T1 dermatome and hypalgesia in left C6-C7 dermatome. Retrograde aortography demonstrated complete obstruction of left subclavian artery. An exploratory operation was performed through the left 4th intercostal space. It was found that the mass was a left subclavian aneurysm of traumatic false type. Proximal and distal ligation of the aneurysm were applied and the sac was partially removed. The continuity of the subclavain artery was established by the use of a 6mm. Dacron graft from the root of the subclavian to the axillary artery. Postoperatively the patient was improved from the circulatory and neurologic disturbances.

• Smart Structures and Systems
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• v.13 no.1
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• pp.55-80
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• 2014

The present work pays emphasis on investigating the effect of different types of debonding on the bending behaviour of active sandwich beam, consisting of both extension and shear actuators. An active sandwich beam finite element is formulated by using Timoshenko's beam theory, characterized by first order shear deformation for the core and Euler-Bernoulli's beam theory for the top and bottom faces. The problem of debondings of extension actuator and face are dealt with by employing four-region model for inner debonding and three-region model for the edge debonding respectively. Displacement based continuity conditions are enforced at the interfaces of different regions using penalty method. Firstly, piezoelectric actuation of healthy sandwich beam is assessed through deflection analysis. Then the effect of actuators' debondings with different boundary conditions on bending behavior is computationally evaluated and experimentally clamped-free case is validated. The results generated will be useful to address the damage tolerant design procedures for smart sandwich beam structures with structural control and health monitoring applications.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.351-356
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• 2000

Various transition elements are generally used for the effective analysis of a complicated mechanical structure. In this paper, a solid-to-beam transition finite element which connects a continuum element and a $c^1-continuity$ beam element each other is proposed. The shape functions of the transition finite elements, which a 8-noded hexahedral solid element fur 3D analysis and a 4-noded quadrilateral plane element fur 2D analysis are connected to a Euler's beam element, are explicitely formulated. In order to show the effectiveness and convergence characteristics of the proposed transition elements. numerical tests are performed for various examples and their results are compared with those obtained by other methods. As the result of this study. following conclusions are obtained: (1)The proposed transition finite elements show the monotonic convergence characteristics because of having used the compatible displacement folds. (2)As being used the transition element in the finite element analysis, the finite element modelings are more convenient and the analysis results are more accurate because of the formulation characteristies of the Euler's beam element.

• Wind and Structures
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• v.1 no.4
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• pp.337-349
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• 1998

A numerical and experimental study was performed for the wind flow field in one area, comprising a group of several pavilions separated by passageways, of the EXPO '98 - a World Exposition (Lisbon, Portugal). The focus of this study is the characterization of the flow field to assess pedestrian comfort. The predictions were obtained employing the Reynolds averaged Navier-Stokes equations with the turbulence effects dealt with the ${\kappa}-{\varepsilon}$ RNG model. The discretization of the differential equations was accomplished with the control volume formulation in a Cartesian coordinate system, and an advanced segregated procedure was used to achieve the link between continuity and momentum equations. The evaluation of the overall numerical model was performed by comparing its predictions against experimental data for a square cylinder placed in a channel. The predicted values, for the practical geometry studied, are in a good agreement with the experimental data, showing the performance and the reliability of the ${\kappa}-{\varepsilon}$ RNG model and suggesting that the numerical simulation is a reliable methodology to provide the required information.

• Advances in materials Research
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• v.12 no.1
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• pp.43-65
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• 2023

Free vibration analysis of power law and sigmoidal sandwich plates made up of functionally graded materials (FGMs) has been carried out using finite element based higher-order zigzag theory. The present model satisfies all-important conditions such as transverse shear stress-free conditions at the plate's top and bottom surface along with continuity condition for transverse stresses at the interface. A Nine-noded C0 finite element having eleven degrees of freedom per node is used during the study. The present model is free from the requirement of any penalty function or post-processing technique and hence is computationally efficient. The present model's effectiveness is demonstrated by comparing the present results with available results in the literature. Several new results have been proposed in the present work, which will serve as a benchmark for future works. It has been observed that the material variation law, power-law exponent, skew angle, and boundary condition of the plate widely determines the free vibration behavior of sandwich functionally graded (FG) plate.

• The Journal of Korean Physical Therapy
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• v.35 no.1
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• pp.31-35
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• 2023

Purpose: This study sought to identify whether fascial therapy using myofascial release (MFR) and Fascial Distortion Model (FDM) techniques affected not only the area where treatment was being given but also remote areas connected to the treatment area by fascial continuity through comparison of the pain pressure threshold (PPT). Methods: The subjects were 16 healthy normal adults in their 20s and 30s who were divided into the MFR and FDM groups before the experiment. The PPT was measured at 4 different points on the body of the subjects. C7, T7, L5, and gastrocnemius along the superficial back line (SBL) before and after the intervention. Results: Only the FDM group subjects showed a significant increase in the PPT at T7 after the intervention. (p<0.05). In addition, the FDM group demonstrated significantly increased PPT at L5 compared to the MFR group. However, neither the FDM nor the MFR group showed a meaningful change in the PPT at the remote area in the lower leg. Conclusion: These findings showed that FDM can affect PPT more and has a positive effect on the pain threshold compared to MFR. However, neither FDM nor MFR showed any effect on the PPT in a remote area.

• The Korean Journal of Pain
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• v.26 no.1
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• pp.57-61
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• 2013

Background: Olfactory dysfunction, including anosmia and hyposmia is difficult to treat. Although the mechanism is not well known, stellate ganglion block (SGB) is used to treat olfactory dysfunction. There are no prior studies on the long-term effects of SGB on olfactory dysfunction. The purpose of this study was to evaluate the continuity of therapeutic effects and patient satisfaction with SGB treatment. Methods: This was a follow-up study carried out via a telephonic survey. The olfactory function of the patient was evaluated using a visual analog scale (VAS). We checked VAS three times: VAS-I (pre-treatment VAS), VAS-A (post-treatment VAS), and VAS-C (VAS at follow up telephone survey). We divided the subjects into 2 groups according to their responsiveness to SGB: the responsive (R group) and the unresponsive groups (UR group). Patient satisfaction was evaluated using a Likert scale. Results: Out of the 40 subjects, 37 responded to the telephone survey. In the UR group, there was difference in the olfactory function. However, in the R group, there were significant VAS differences; VAS-I was $9.6{\pm}0.7$, VAS-A was $5.1{\pm}4.2$, and VAS-C was $2.7{\pm}$2.7 (P < 0.05). On the Likert scale, patient satisfaction was as follows: grade 1, 17 patients (45.9%); grade 2, 6 patients (16.2%); grade 3, 6 patients (16.2%); and grade 4, 8 patients (21.6%). Conclusions: SGB is a safe, long-lasting, and effective therapeutic modality for olfactory dysfunction treatment.

• Journal of Korean Society of Steel Construction
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• v.23 no.4
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• pp.475-481
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• 2011

In this study, a simplified method of improving not only transverse shear stress but also shear strain based on the first-order shear deformation theory was developed. Unlike many established methods, such as the higher-order shear deformation and layerwise theories, this method can easily apply to finite elements as only $C^0$ continuity is necessary and the formulation of equations is very simple. The basic concept in this method, however, must be corrected:the distribution of the transverse shear stresses and shear strains through the thickness from the formulation based on the higher-order shear deformation theory. Therefore, the shear correction factors are no longer required, based on the first-order shear deformation theory. Numerical analyses were conducted to verify the validity of the proposed formulations. The solutions based on the simplified method were in very good agreement with the results considering the higher-order shear deformation theory.

• Water for future
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• v.24 no.4
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• pp.41-48
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• 1991

This paper describes the characteristics of tidal currents in the Gamag Bay by using the two-dimensional nonlinear hydrodynamic euation. The basic equations are derived by Navier-Stokes momentum equation and continuity equation and its characteristics critically are reviewed, and they are analysed by the implicit finite difference method. The numerical model is constructed two-dimensional(depth-averaged) simple layer model. This paper investigates the stability of solution and convergence of solution in application of the method to Gamag Bay, and the reproducibility of the simulation is also discussed in comparison with the results of field survey. The following items are clarifide through the numerical investigation; i)the reproduc-ibility of tidal range and currents are quite acceptable, comparing with the results of model tests and field data, and ii) tidal cycle for convergent solution is four tidal cycle, also, iii) bottom friction is successfully represented as c=(1/n))$h^{1/6}$.