• International Journal of Precision Engineering and Manufacturing
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• v.8 no.1
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• pp.27-31
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• 2007

A rolling speed dependent spread model is proposed for predicting the exit cross sectional shape in oval-round (or round-oval) pass rod rolling process when the rolling speed is very high. The effect of rolling speed on the exit cross sectional shape is measured by performing a four-pass continuous high speed (${\sim}80m/s$) rod rolling test and is described in terms of the spread correction parameter. The validity of the model is examined by applying it to rod rolling process at POSCO No.3 Rod Mill. The cross sectional shapes of workpiece predicted by the proposed model coupled with the surface profile prediction $method^{6}$ are in good agreement with those obtained experimentally.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.9
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• pp.174-180
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• 2000

A reliable analytic model that determines the cross sectional shape of a workpiece(material) in round-oval(or oval-round) pass sequence has been developed. the cross sectional shape of an outgoing workpiece is predicted by using the linear interpolation of the radius of curvature of an incoming workpiece and that of roll groove to the roll axis direction. The requirements we placed on the choice of the weighting function were to ensure boundary conditions specified. The validity of the analytic model has been examined by hot rod rolling experiment with the roll gap and specimen size changed. The cross sectional shape and area of a workpiece predicted by the proposed analytic model were good agreement with those obtained experimentally. It was found that the analytic model has not only simplicity and accuracy for practical usage but also save a large amount of computational time compared with finite element method.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.591-596
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• 1999

Due to the development of CNC machining centers and the complexity of machined part geometry, the ball-end milling became the most widely used the cutting process. Generally, the tool runout defined as the eccentricity of a rotating tool set in the holder involved the spindle runout and the problem of tool runout generated to remove the workpiece is a main factor affecting the machining accuracy. In this paper, the relationship of tool runout(zero-to-peak, P-K) and surface shape on the change of cutting conditions is studied and it is proposed the probability of prediction of surface shape from the in-process tool runout measurements with high response displacement sensor in the ball-end milling

• Journal of the Korean Society for Precision Engineering
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• v.32 no.2
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• pp.173-178
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• 2015

Laser-assisted machining (LAM) is an effective machining method for processing difficult-to-cut materials. Prediction and estimation of preheating effect of the LAM is difficult because of moving heat source. So it is necessary to study the preheating effect of the laser heat source irradiated on the curved surfaces of workpieces of various shape. In this paper, thermal analysis of the LAM for 3-dimentional workpiece with cylindrical shape was performed. The results of this analysis can be applied to obtain the optimal preheating method and path for LAM of 3-dimensional workpiece.

• Transactions of Materials Processing
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• v.20 no.5
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• pp.350-356
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• 2011

Shape memory alloys(SMAs) exhibit pseudoelastic behavior, characterized by the recovery of an original shape even after severe deformation, during loading and unloading within appropriate temperature regimes. The distinctive mechanical behavior is associated with stress-induced transformation of austenite to martensite during loading and reverse transformation to austenite upon unloading. To develop a material model for SMAs, it is imperative to consider the difference in moduli of active phases. For example, the Young’s modulus of the martensite is one-third to one half of that of the austenite. The model proposed herein is a modification of the one proposed recently by Ho[17]. The prediction of the behavior of SMAs during unloading before the onset of reverse transformation was improved by introducing a new internal state variable incorporating the variation of the elastic modulus.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.147-152
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• 1999

The strengthening of a metal matrix composite(MMC) by the shape memory effect(SME) of dispersed TiNi particles was theoretically studied. An analytical model was constructed for the prediction of the average residual stress(<$\sigma$>/sub/m) on the base of the Eshelby's equivalent inclusion method. The analysis was performed on the TiNi particle/Al metal matrix composites with varying volume fractions and prestrains of the particle. The residual stress caused by the shape memory of predeformed fillers has been predicted to contribute significantly to the strengthening of this composite.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.53-58
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• 2003

Wear debris can be collected from the lubricants of operating machinery and its morphology is directly related to the fiction condition of the interacting materials from which the wear particles originated in lubricated machinery. But in order to predict and estimate working conditions, it is need to analyze the shape characteristics of wear debris and to identify. Therefore, if the shape characteristics of wear debris is identified by computer image analysis and the neural network, The four parameter (50% volumetric diameter, aspect, roundness and reflectivity) of wear debris are used as inputs to the network and learned the friction. It is shown that identification results depend on the ranges of these shape parameters learned. The three kinds of the wear debris had a different pattern characteristic and recognized the friction condition and materials very well by neural network. We resented how the neural network recognize wear debris on driving condition.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.659-670
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• 2004

Handoff is one of the most important features for the user's mobility in a wireless cellular communication system. It is related to resource reservation at nearby cells. Resource reservation to the new connection point should occur prior to handoff to enable the user to receive the data or services at the new location, at the same level of service as at the previous location. For the efficient resource reservation, mobility prediction has been reported as an effective means to decrease the call dropping probability and to shorten the handoff latency in a wireless cellular environment. A recently proposed algorithm, ZMHB, makes use of the history of the user's positions within the current cell to predict the next cell. But, the prediction of the ZMHB algorithm is found to be 80∼85% accurate for regular and random movements. In this paper, we propose a new improved ZMHB mobility prediction algorithm, which is called Detailed-ZMHB that uses detailed-zone-based tracking of mo-bile users to predict user movements. The effectiveness of the proposed algorithm is then demonstrated through a simulation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.23-34
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• 2004

In this paper we propose a feature point tracking algorithm using optical flow under non-prior taming active feature model (NPT-AFM). The proposed algorithm mainly focuses on analysis non-rigid objects[1], and provides real-time, robust tracking by NPT-AFM. NPT-AFM algorithm can be divided into two steps: (i) localization of an object-of-interest and (ii) prediction and correction of the object position by utilizing the inter-frame information. The localization step was realized by using a modified Shi-Tomasi's feature tracking algoriam[2] after motion-based segmentation. In the prediction-correction step, given feature points are continuously tracked by using optical flow method[3] and if a feature point cannot be properly tracked, temporal and spatial prediction schemes can be employed for that point until it becomes uncovered again. Feature points inside an object are estimated instead of its shape boundary, and are updated an element of the training set for AFH Experimental results, show that the proposed NPT-AFM-based algerian can robustly track non-rigid objects in real-time.

• Journal of Sasang Constitutional Medicine
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• v.34 no.2
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• pp.1-14
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• 2022

Objectives The aim of this study was to investigate the change in Sasang constitution prediction value in 2 years and find the factors associated with it. Methods Cohort data from Korean medicine data center was used. Using Korean Sasang Constitutional Diagnostic Questionnaire (KS-15) which consist of questions related to body shape, temperament, and symptoms, participants were categorized into Tae-Yang (TY), Tae-Eum (TE), So-Yang (SY), and So-Eum (SE). Sasang constitution was assessed on the baseline and after two years. Result Total 5,784 participants were analyzed. (TE 3, 341; SE 911; SY 1,532). Among them, 1,402 participants (24.2%) showed different prediction value in KS-15 after two years. The proportion of participants showing different prediction value in two years was the highest in SY, and the lowest in TE group. The factors associated with the change in Sasang constitution prediction value were different by constitution type. The change in feeling after sweating was significantly associated with the change in prediction value in TE and SY groups, not in SE group. Although temperament was not significantly associated with the change in prediction value from TE to SE, it was significantly associated with that in the change from TE to SY. The change in BMI and appetite were associated with the change in constitution prediction value in all three constitution types. Conclusion Although the factors associated with the change in prediction value of Sasang constitution were different by each constitution type, BMI and appetite were significant in all three types. These factors could be useful for developing Sasang constitution questionnaire and deciding re-prediction needs of Sasang constitution. Further research about the factors related to Sasang constitution diagnosis need to be conducted.