• Journal of the Korean Society of Safety
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• 제20권1호
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• pp.68-74
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• 2005

The objective of the present work is to examine the evaporation shape of deposited droplet on the hot surface. this paper performed the experiments as following conditions: (a) the surface temperature is within the range between $80^{\circ}C$ and $95^{\circ}C$ in the conduction and radiation, (b) droplet diameter is 3.0mm. The results are as follows; while droplet evaporates, droplet's radius is kept changelessly to $70\%$ evaporation time and droplet's shape is kept changelessly after. In case use Constant radius model, about $10\%$ is appearing high than value that time-averaged heat flux applies Inverse heat conduction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제31권5호
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• pp.278-282
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• 2018

We propose a SPICE model of drain-induced barrier lowering (DIBL) for a junctionless cylindrical surrounding gate (JLCSG) MOSFETs. To this end, the potential distribution in the channel is obtained via the Poisson equation, and the threshold voltage model is presented for the JLCSG MOSFET. In a JLCSG nano-structured MOSFET, a channel radius affects the carrier transfer as well as the channel length and oxide thickness; therefore, DIBL should be expressed as a function of channel length, channel radius, and oxide thickness. Consequently, it can be seen that DIBLs are proportional to the power of -3 for the channel length, 2 for the channel radius, 1 for the thickness of the oxide film, and the constant of proportionality is 18.5 when the SPICE parameter, the static feedback coefficient ${\eta}$, is between 0.2 and 1.0. In particular, as the channel radius and the oxide film thickness increase, the value of ${\eta}$ remains nearly constant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.654-657
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• 2000

In the winding system, the constant tension control is too important. In this study, we've used a variable PID system as a function of a radius of winding roll. As a result, it was possible to measure a winding roll radius in the real time by making a mathematical model for measuring a winding roll radius. Finally, we've compared PID parameters as a function of winding roll radius after getting PID parameters in terms of the Ziegler & Nichols(ZN) method.

• Particle and aerosol research
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• 제8권2호
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• pp.75-81
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• 2012

The strength of lumped cokes can be represented by some index numbers. Although some indexes are suggested, these indexes are not enough to enlighten fracture mechanism. To find essential mechanism, a computational way, discrete element method, is applied to the uniaxial compression test for cylindrical specimen. The cylindrical specimen is a kind of lumped particle mass with parallel bonding that will be broken when the normal stress and shear stress is over a critical value. It is revealed that the primary factors for cokes fracture are parallel spring constant, parallel bond strength, bonding radius and packing ratio the parallel bond strength and radius of the parallel combination the packing density. Especially, parallel spring constant is directly related with elastic constant and yield strength.

• Journal of Environmental Science International
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• 제12권6호
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• pp.615-626
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• 2003

The applied model for this study area is WINFLOW using mite element method, It is thought that the simulation result by WINFLOW model under the steady flow state reflects well the ground water distribution within the reliability level which shows the error range of 1.1% to 8.0% from the comparison between the computed values and the observed, and analyzed that the constant head distribution is shown along the east-west direction and gentle and stable head gradient along the north-south direction. Ground water of the study area shows stable movement from the south to the stream area, and the particle trace for each location shows relatively linear shape from the upstream to the pumping location while the radius of influence according to the pumping amount shows a significant difference at the down stream area from the pumping location. The simultaneous pumping from P and P1 shows more complicated appearance, not the increase of the radius of influence than pumping from a single well P or P1, and it is analyzed that the particle path takes nearly linear form. It is known that the flow direction of the ground water and the velocity of the flow affect on the magnitude of the radius of influence of the wells from the fact that the more decreasing pattern of the ground water head is observed at the side of the well and the down stream area than the upstream area when the ground water moves from south to north regarding the radius of influence according to the pumping amount. Satisfactory results in analyses of ground water movement are obtained through the significant reduction of the physical uncertainties in the flow system as well as the relatively convenient model application using WINFLOW model which is proposed in this study.

• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.637-640
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• 2011

The hybrid neural networks have characteristics such as fast learning times, generality, and simplicity, and are mainly used to classify learning data and to model non-linear systems. The middle layer of a hybrid neural network clusters the learning vectors by grouping homogenous vectors in the same cluster. In the clustering procedure, the homogeneity between learning vectors is represented as the distance between the vectors. Therefore, if the distances between a learning vector and all vectors in a cluster are smaller than a given constant radius, the learning vector is added to the cluster. However, the usage of a constant radius in clustering is the primary source of errors and therefore decreases the recognition success rate. To improve the recognition success rate, we proposed the enhanced hybrid network that organizes the middle layer effectively by using the enhanced ART1 network adjusting the vigilance parameter dynamically according to the similarity between patterns. The results of experiments on a large number of calling card images showed that the proposed algorithm greatly improves the character extraction and recognition compared with conventional recognition algorithms.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.435-438
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• 1990

A new robust stabilizing method of uncertain system is proposed. The model uncertainty is considered to be the system matrix perturbations. The region of perturbed system eigenvalues are estimated by union of the disks which have the constant radius. Full state feedback control matrix which satisfies the new stabilization condition can be obtained by weighted LQ regulator or pole assignment technique.

• Korean Journal of Optics and Photonics
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• 제35권4호
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• pp.143-149
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• 2024

We analyze the effect of atmospheric fluctuation on laser beam propagation, using a single-phase screen model and a multi-phase screen model. When a laser beam (wavelength 1064 nm, radius 10 mm, collimated by 25.4 mm optics) propagates 3 km, atmospheric fluctuation with structure constant C_n² in the range of 10^-17 to 10^-14 is generated by the single- and multi-phase screen models. The results of short-term and long-term exposures are analyzed in terms of the beam profile, power in the bucket, and beam radius at the receiver plane. The power in the bucket and beam radius increase as the structure constant increases. When the structure constant is less than 2×10^-15, the results of the single- and multi-phase screen models are similar, within a difference of 1.5 %. However, when the structure constant is greater than 2×10^-15, the difference between the two models increases, and the multi-phase screen model is appropriate under this condition.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제18권10호
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• pp.75-82
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• 2019

Few studies have been conducted regarding theoretical turning force modelling while considering cutting constant. In this paper, a new cutting force modelling technique was suggested which considers the specific cutting force coefficients for turning. The specific cutting force is the multiplication of the cutting force coefficient and uncut chip thickness. This parameter was used for experimental modelling and prediction of theoretical cutting force. These coefficients, which can be obtained by fitting measured average forces in several conditions, were used for the formulation of three theoretical cutting forces for turning. The cutting force mechanism was verified in this research and its results were compared with each of the experimental and theoretical forces. The deviation of force was incurred by a small amount in this model and the predicted force considering feed rate, nose radius, and radial depth shows a physical behavior in main force, normal force, and feeding force, respectively. Therefore, this modelling technique can be used to effectively predict three turning forces with different tool geometries considering cutting force coefficients.

• Wind and Structures
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• 제32권4호
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• pp.371-391
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• 2021

Tornadoes are the most devastating meteorological natural hazards. Many empirical and theoretical numerical models of tornado vortex have been proposed, because it is difficult to carry out direct measurements of tornado velocity components. However, most of existing numerical models fail to explain the physical structure of tornado vortices. The present paper proposes a new empirical numerical model for a tornado vortex, and its load effects on a low-rise and a tall building are calculated and compared with those for existing numerical models. The velocity components of the proposed model show clear variations with radius and height, showing good agreement with the results of field measurements, wind tunnel experiments and computational fluid dynamics. Normal stresses in the columns of a low-rise building obtained from the proposed model show intermediate values when compared with those obtained from existing numerical models. Local forces on a tall building show clear variation with height and the largest local forces show similar values to most existing numerical models. Local forces increase with increasing turbulence intensity and are found to depend mainly on reference velocity Uref and moving velocity Umov. However, they collapse to one curve for the same normalized velocity Uref / Umov. The effects of reference radius and reference height are found to be small. Resultant fluctuating force of generalized forces obtained from the modified Rankine model is considered to be larger than those obtained from the proposed model. Fluctuating force increases as the integral length scale increases for the modified Rankine model, while they remain almost constant regardless of the integral length scale for the proposed model.