• Journal of Korean Society of Water and Wastewater
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• v.22 no.2
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• pp.239-243
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• 2008

The fluctuation of inlet flow to a water treatment plant makes a serious problem that it can change the outlet flow-rate from each process abruptly, and ultimately occur the detachment of the attached particles inside each unit process. Also, since it takes very short time for the surface wave occurred from the fluctuation of inlet flow to reach the latter processes, it is impossible for operators to cope with that stably. Therefore this study was conducted to suggest the methodology for accurately predicting the travel time of surface wave occurred from the fluctuation of inlet flow to reach the latter process. Through the experiment, which was carried out for the full-scale water treatment plants(capacity : 2,000m3/d), it could be confirmed that the flow rate fluctuation from equalization tank produce the surface wave. And the wave transfer velocity is a function of the hydraulic radius and the length of each open type tanks which are comprised in the latter processes.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.663-671
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• 2008

This paper presents a real-time haptic rendering method for multi-contact interaction with virtual environments. Haptic systems often employ physics-based deformation models such as finite-element models and mass-spring models which demand heavy computational overhead. The haptic system can be designed to have two sampling times, T and JT, for the haptic loop and the graphic loop, respectively. A multi-rate output-estimation with an exponential forgetting factor is proposed to implement real-time haptic rendering for the haptic systems with two sampling rates. The computational burden of the output-estimation increases rapidly as the number of contact points increases. To reduce the computation of the estimation, the multi-rate output-estimation with reduced parameters is developed in this paper. Performance of the new output-estimation with reduced parameters is compared with the original output-estimation with full parameters and an exponential forgetting factor. Estimated outputs are computed from the estimated input-output model at a high rate, and trace the analytical outputs computed from the deformation model. The performance is demonstrated by simulation with a linear tensor-mass model.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.668-670
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• 1999

We have developed a automatic surface inspection system for cold Rolled strips in steel making process for several years. We have experienced the various kinds of surface inspection systems, including linear CCD camera type and the laser type inspection system which was installed in cold rolled strips production lines. But, we did not satisfied with these inspection systems owing to insufficient detection and classification rate, real time processing performance and limited line speed of real production lines. In order to increase detection and computing power, we have used the Dark Field illumination with Infra_Red LED, Bright Field illumination with Xenon Lamp, Parallel Computing Processor with Area typed CCD camera and full software based image processing technique for the ease up_grading and maintenance. In this paper, we introduced the automatic inspection system and real time image processing technique using the Object Detection, Defect Detection, Classification algorithms. As a result of experiment, under the situation of the high speed processed line(max 1000 meter per minute) defect detection is above 90% for all occurred defects in real line, defect name classification rate is about 80% for most frequently occurred 8 defect, and defect grade classification rate is 84% for name classified defect.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1491-1496
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• 2009

Fluid flow and structural analyses of an electronic expansion valve (EEV) using CO2 as a working refrigerant are carried out to estimate the mass flow rate and maximum stress. An engineering sample EEV that the orifice diameter is 1.8 mm was fabricated. The mass flow rates were measured at various EEV inlet temperatures and pressures for several EEV openings using experimental heat pump system. The sample EEV has over 35 MPa burst pressure and the maximum mass flow rate of CO2 through the EEV increased to 100 g/s at full opening condition.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.73-88
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• 2014

Various studies on the critical flow models for sub-cooled and/or saturated water were reviewed, especially on Fauske, Moody, and Henry for basic theoretical models; Zaloudek for insight into physical phenomena for a critical flow in an orifice type flow path; Sozzi & Sutherland for a critical flow test of saturated and sub-cooled water at high pressure for orifice and nozzles; and a Marviken test on a full-scale critical flow test. In addition, critical flow tests of sub-cooled water for the break simulators in integral effect test (IET) facilities were also investigated, and a hybrid concept using Moody's and Fauske's models was considered by the authors. In the comparison of the models for the selected test data, discussions of the effect of the diameters, predictions of the critical flow models, and design aspects of break simulator for SBLOCA scenarios in the IET facilities were presented. In the effect of diameter on the critical flow rate with respect to all dimensional scales, it was concluded that the effect of diameter was found irrespective of diameter sizes. In addition, the diameter effect on slip ratio affecting the critical flow rate was suggested. From a comparison of the critical flow models and selected test data, the Henry-Fauske model of the MARS-KS code was found to be the best model predicting the critical flow rate for the selected test data under study.

• Journal of the Korean Wood Science and Technology
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• v.23 no.4
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• pp.33-38
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• 1995

The rates of fixation of CCA-Type B and CCFZ in blocks of radiata pine sapwood were compared at various temperatures and conditioning methods (drying and nondrying conditioning). Also the time required to proper fixation of preservative components in the treated wood was estimated. Fixation was monitored by the rates of depletion of free hexavalent chromium in the cell lumens in the teated blocks. The rate of preservative fixation in wood was highly temperature dependent. The fixation rate was considerably accelerated by means of heating and complete fixation of hexavalent chromium was achieved within about 12 hours by heating at $60^{\circ}C$. The moisture content of treated wood during fixation apparently played an important role in the fixation process. The fixation rate of treated wood conditioned in nondrying conditions was much more faster than that of treated wood conditioned in drying conditions. particularly when the moisture content of treated wood was below fiber saturation point. Time required to full fixation could be predicted successfully using the fixation temperatures applied since the correlation between the fixation temperature and the fixation time was excellent. regardless of conditioning methods.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.12
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• pp.9-24
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• 1995

In this paper, we proposed and analysed two kinds of priority control mechanism to archive the cell loss rate requirement and the delay requirement of each class. The service classes of our concern are the high time priority class(class 1) and the high loss priority class(class 2). Two kinds of priority control mechanism is divided by the method of storing the arriving class 2 cell in buffer on case of buffer full. The first one is the method which discarding the arriving class 2 cell, the second one is the mothod which storing the arriving class 2 cell on behalf of pushing out the class 1 cell in buffer. In the proposed priority schemes, one cell of the class 1 is transmitted whenever the maximum K cells of the class 2 is transmitted on case of transmitting the class 1 cell and the class 2 cell sequentially. In this paper, we analysed the cell loss rate and the mean cell delay for each class of the proposed priority scheme by using the Markov chain. The analytical results show that the characteristic of the mean cell delay becomes better for the class 1 cell and that of the cell loss rate becomes better for the class 2 cell by selecting properly the cell transfer ratio according to the condition of input traffic.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.102-107
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• 2001

Interfacial cracks between an isotropic and orthotropic material, subjected to static far field tensile loading are analyzed using the technique of photoelasticity. The fracture parameters are extracted from the full-field isochromatic data and the same are compared with that obtained using boundary collocation method. Dynamic Photoelasticity combined with high-speed digital photography is employed for capturing the isochromatics in the case of propagating interfacial cracks. The normalized stress intensity factors for static crack is greater when $\alpha=90^{\circ}C$ (fibers perpendicular to the interface) than when $\alpha=0^{\circ}C$ (fiber parallel to the interface) and those when $\alpha=90^{\circ}C$ are similar to ones of isotropic material. The dynamic stress intensity factors for interfacial propagating crack are greater when $\alpha=0^{\circ}C$ than $\alpha=90^{\circ}C$. The relationship between complex dynamic stress intensity factor $|K_D|$ and crack speed C is similar to that for isotropic homogeneous materials, the rate of increase of energy release rate G or $|K_D|$ with crack speed is not as drastic as that reported for homogeneous materials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.1-5
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• 2005

A new model of plasma etch process was constructed by using a radial basis function network (RBFN). This technique was applied to an etching of silicon carbide films in a NF$_3$ inductively coupled plasma. Experimental data to train RBFN were systematically collected by means of a 2$^4$ full factorial experiment. Appropriateness of prediction models was tested with test data consisted of 16 experiments not pertaining to the training data. Prediction performance was optimized with variations in three training factors, the number of pattern units, width of radial basis function, and initial weight distribution between the pattern and output layers. The etch responses to model were an etch rate and a surface roughness measured by atomic force microscopy. Optimized models had the root mean-squared errors of 26.1 nm/min and 0.103 nm for the etch rate and surface roughness, respectively. Compared to statistical regression models, RBFN models demonstrated an improvement of more than 20 % and 50 % for the etch rate and surface roughness, respectively. It is therefore expected that RBFN can be effectively used to construct prediction models of plasma processes.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.769-772
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• 2010

The objective of the current research work is to investigate the usage of biodiesel combined with the use of EGR in order to reduce the emission of all regulated pollutants from diesel engines. A single cylinder, air cooled, constant speed direct injection diesel engine was used for the experimental work and a cold EGR system was developed and fitted to the engine. Concentrations of HCs, NOx, and CO from the exhaust gas along with the smoke opacity were measured. Engine performance parameters such as the brake thermal efficiency (BTE) and the brake specific energy consumption (BSEC) were also calculated from the measured data. The results from the present investigation suggest that 25-30% EGR rate could give excellent NOx reduction without any significance penalty on smoke opacity or BSEC under the engine load of up to 40%. Under the full load condition, 15% EGR rate was found to be an option while higher EGR rate resulted in inferior performance and heavy smoke.