• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.10
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• pp.1489-1497
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• 2003

Aerosol charge neutralizers with various radioactive sources have been used to apply an equilibrium charge distribution to aerosols of unknown charge distribution. However, the performance of aerosol charge neutralizers is not well known, especially for highly charged particles. Measurements of highly charged particles are needed in air cleaning devices, e.g. electrostatic precipitator, bag filter with a pre-charger, and electrical cyclone. In this study, the particle charging characteristics of two different aerosol charge neutralizers were experimentally investigated for singly charged monodisperse particles and highly charged polydisperse particles. One has radioactive source of $^{85}$ Kr (beta source, 2 mCi) and the other has $^{210}$ Po (alpha source, 0,5 mCi). The air flow rate passing through each aerosol charge neutralizer was changed from 0.2 to 2.5 L/min. The results show that the charge distribution of singly charged monodisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer is well agreed with the Boltzmann equilibrium charge distribution at an air flow rate of 0.3 L/min, However, it deviates from the equilibrium charge distribution when the air flow rates are 0.6, 1,0, and 1,5 L/min, On the other hands, the effect of air flow rate is insignificant for the $^{210}$ Po aerosol charge neutralizer. The non-equilibrium character in charge distribution of highly charged polydisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer greatly depends on the air flow rate, however it is insensitive to the air flow rate for the $^{210}$ Po aerosol charge neutralizer.

• Journal of the Korean Operations Research and Management Science Society
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• v.27 no.1
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• pp.19-32
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• 2002

This paper examines the effect of the producer-supplier quality contract parameters and the magnitude of the quality related variables on the quality of the final products. Our analysis focuses on the parties' equilibrium behavior In a quality game environment where the supplier should choose among the two production technologies, one requiring high cost but producing high quality Parts and the other requiring low cost but producing low quality parts and where the producer should decide whether to do the inspection of the parts. The game framework is employed to depict the potential conflicts existing between the Producer and the supplier because the Producer can not observe the supplier's choice and each party wants the other to bear the cost of producing high quality products. In our model, we specifically consider the competitive situation where the producer competes with a firm producing the same product. We employ the market share attraction model to Incorporate the competitive situation and completely characterize the equilibrium by using the Nash equilibrium concept for the game solution. Our results show that the equilibrium depends on the contract terms and the magnitude of the quality related variables. Compared to the non-competitive situation, the probability of producer's Inspection and the probability of supplier's choosing the high quality technology increases in a competitive situation. This is true even when the competitor's quality is lower than the producer's lowest. As a result, the quality of the final product increases In a competitive situation. And as the failure cost borne by the supplier increases, the probability of choosing the high quality technology Increases and the probability of inspection decreases. The net effect of this results in the decrease of the final product quality.

• Proceedings of the Korean Fiber Society Conference
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• 1992.06a
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• pp.46-46
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• 1992

• Smart Structures and Systems
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• v.14 no.2
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• pp.225-246
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• 2014

The present paper develops piezo-thermo-elastic analysis of a thick spherical shell for generalized functionally graded piezoelectric material. The assumed structure is loaded under thermal, electrical and mechanical loads. The mechanical, thermal and electrical properties are graded along the radial direction based on a power function with three different non homogenous indexes. Primarily, the non homogenous heat transfer equation is solved by applying the general boundary conditions, individually. Substitution of stress, strain, electrical displacement and material properties in equilibrium and Maxwell equations present two non homogenous differential equation of order two. The main objective of the present study is to improve the relations between mechanical and electrical loads in hollow spherical shells especially for functionally graded piezoelectric materials. The obtained results can evaluate the effect of every non homogenous parameter on the mechanical and electrical components.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4B
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• pp.353-360
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• 2011

The objectives of this study were to analyzes temporal variation of local scour depth in the downstream of weir with shapes. Prediction of maximum or equilibrium scour depth was the main focus of engineers and researchers in the downstream of weir. However, it is necessary to analyzes temporal variation of local scour depth in the downstream of weir to predict real time scour depth. Experiment were performed with various weir shapes like sharp crest and inclined stepped with time variation and non-dimensional scourhole shapes, scour depths were proposed. A formula for predicting scour depths with temporal variation for weir were proposed through non-linear regression analysis. Temporal variation of scour depths could be estimated with suggested formula and 4 input data (Equilibrium scour depth, weir height, overflow depths, and water depth downstream). Suggested formula could make it possible to design a apron and bed protection economically in the downstream of a weir by considering flood duration time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.s02
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• pp.96-114
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• 1989

There are several meterorolgical stresses in the winter cereal crops. Among these stresses, cold injury is one of the most important stresses for wheat and barley production in Korea. The reduction in grain yield of the wheat and barley due to cold injury has occurred almost every year in Korea. The objective of the study was to get the basic information in relation to the cold injury and to detect the method minimizing the damage of cold injury. When the air temperature was the ranges of -13$^{\circ}C$ to -15$^{\circ}C$, the soil temperature at the crown part of the plant was very stable, whereas in the ranges of -2$^{\circ}C$ to -3$^{\circ}C$ the soil surface temperature was more unstable and cold than air and subterranean temperatures. The different parts of the plant in wheat and barley possess the different levels of cold hardiness. In comparison to the cold hardiness of plant parts, the leaf and crown are the less sensitive to cold injury than root and vascular transitional zone. The type and extent of stress is determined by the redistribution pattern of water during freezing. These types from freezing processes were three types: a) Equilibrium freezing pattern b) Non -equilibrium freezing pattern, c) Non-equilibrium freezing pattern typical of tender tissues. Cold hardiness in wheat plants were more harder than barley plants at vegitative stage, but inverted at the reproductive stage. Injuries by low temperature during the seasons of barley cultivation in Korea were occured mainly in four stage; in the first and third stage, frost injury occurs, the second stage, freezing injury, and the fourth stage, chilling injury.

• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.563-574
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• 2009

This paper briefly describes the fundamental strategies--path-tracing, pin-pointing, and path-switching--in the computational elastic bifurcation theory of geometrically non-linear single-load-parameter conservative elastic spatial structures. The stability points in the non-linear elasticity may be classified into limit points and bifurcation points. For the limit points, the path tracing scheme that successively computes the regular equilibrium points on the equilibrium path, and the pinpointing scheme that precisely locates the singular equilibrium points were sufficient for the computational stability analysis. For the bifurcation points, however, a specific procedure for path-switching was also necessary to detect the branching paths to be traced in the post-buckling region. After the introduction, a general theory of elastic stability based on the energy concept was given. Then path tracing, an indirect method of detecting multiple bifurcation points, and path switching strategies were described. Next, some numerical examples of bifurcation analysis were carried out for a trussed stardome, and a pin-supported plane circular arch was described. Finally, concluding remarks were given.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2286-2309
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• 2016

Overlay networks have been widely deployed upon the Internet by Service Providers (SPs) to provide improved network services. However, the interaction between each overlay and traffic engineering (TE) as well as the interaction among co-existing overlays may occur. In this paper, we adopt both non-cooperative and cooperative game theory to analyze these interactions, which are collectively called hybrid interaction. Firstly, we model a situation of the hybrid interaction as an n+1-player non-cooperative game, in which overlays and TE are of equal status, and prove the existence of Nash equilibrium (NE) for this game. Secondly, we model another situation of the hybrid interaction as a 1-leader-n-follower Stackelberg-Nash game, in which TE is the leader and co-existing overlays are followers, and prove that the cost at Stackelberg-Nash equilibrium (SNE) is at least as good as that at NE for TE. Thirdly, we propose a cooperative coalition mechanism based on Shapley value to overcome the inherent inefficiency of NE and SNE, in which players can improve their performance and form stable coalitions. Finally, we apply distinct genetic algorithms (GA) to calculate the values for NE, SNE and the assigned cost for each player in each coalition, respectively. Analytical results are confirmed by the simulation on complex network topologies.

• Journal of Korea Foundry Society
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• v.11 no.3
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• pp.208-216
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• 1991

The solidification behavior of the squeeze cast composites of aluminum alloys reinforced with boron fiber($100{\mu}m$) and silicon carbide fibers($140{\mu}m$ and $15{\mu}m$) were investigated. Al-4.5wt%Cu and Al-l0wt%Mg were chosen for the matrix phase of the composites. In the squeeze cast specimen with high thermal difference between fiber and melt, the average secondary dendrite arm spacing(DAS) in reinforced alloy is smaller than that in unreinforced alloy. It was also observed that primary ${\alpha}$ and non-equilibrium eutectic, which seems to be penetrated and solidified at the final stage of the solidification of the matrix, are irregularly distributed around fibers. It is considered that cold fibers serve as heterogeneous nucleation site. While in the remelted and resolidified specimen without temperature difference, the DAS was not changed with reinforcement and microstructure reveals non-equilibrium eutectic with relatively uniform thickness around fibers. It might be evident the nucleation starts at interfiber region. Microsegregation decreases with the decrease in cooling rate and with reinforcement in the as-squeeze cast specimen. Al-10wt% Mg alloy shows less microsegregation than Al-4.5wt%Cu alloy.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.395-402
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• 2001

An induction thermal plasma system have been newly designed for advanced operation with a pulse modulated mode to control the plasma power in time domain and to create non-equilibrium effects such as fast quenching of the plasma to produce new functional materials in high rate. The system consists of MOSFET power supply with a maximum power of 50 kW with a frequency of 460 kHz, an induction plasma torch with a 10-turns coil of 80 mm diameter and 150 mm length and a vacuum chamber. The pulse modulated plasma was successfully generated at a plasma power of 30 kW and a high pressure of 100 kPa, with taking the on and off time as 10 ms, respectively. Measurements were carried out on the time-dependent spectral lines emitted from Ar species. The dynamic behavior of plasma temperature in a pulse cycle was estimated by the Boltzmann plot and the excitation temperature of Ar atom was found to be changed periodically from around 0.5 to 1.7 eV during the cycle. Two application regions of the induction thermal plasma newly generated were introduced to material processing with high rate synthesis based on non equilibrium effects, and to the finding of new arc quenching gases coming necessary for power circuit breaker, which is friendly with earth circumstance alternative to SF6 gas.