• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.515-520
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• 2009

According to the operating characteristics of pump applications, they should exhibit high efficiency and energy saving capabilities throughout the whole operating process. A novel efficiency optimization control strategy is presented here to meet the high efficiency demand of a variable speed Permanent Magnet Synchronous Motor (PMSM). The core of this strategy is the excellent integration of mended maximum torque to the current control algorithm, based on the losses model during the dynamic and the grade search method with changed step by fuzzy logic during the steady. The performance experiments for the control system of a variable speed high efficiency PMSM have been completed. The test results verified that the system can reliably operate with a different control strategy during dynamic and steady operation, and the system exhibits better performance when using the efficiency-optimization control.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.6 s.154
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• pp.961-970
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• 2006

This study attempted to understand post-purchase consumer return experiences which had not received much attention in consumer behavior research. As a first step to understand return experiences from consumers' viewpoint, the study took an exploratory approach and identified themes and patterns from subjective consumer experiences. Whenever possible, attribution theory was applied to interpret the identified patterns. A total of 99 cases were collected from an open-ended questionnaire and analyzed based on a qualitative method. The reasons of product return was classified into five groups: changing mind; product defects; unsuitable products; products not expected; and for a better deal. External attribution was observed for return decisions caused by consumers' changed mind as well as by product defects. Dissatisfaction with defected products seemed to be intensified or reduced by service failure or success in the post-purchase service encounter. Consumer expectation and situations seemed to affect this process. Overall, the study supported attribution theory in the post-purchase return experience, and insights for research questions were proposed.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.4
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• pp.24-33
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• 1991

The effects of thermomechanical treatments on microstructure and fatigue properties of 7050 Al alloy were investigated. The precipitation kinetics changed to a faster rate due to cold deformation employed in this special TAHA thermomechanical treatments including pre-aging, plastic deformation and two step final-aging. The G.P. zones in the under-aged condition were cut by dislocations and dissolved during the plastic deformation. During the low cycle fatigue, the T6' condition showed cyclic hardening behavior whereas the TMT5, TMT27 and T76 conditions showed cyclic softening at above 0.7% total strain amplitudes. The ${\Delta}K_{th}$ value of TMT27 was improved more than two times, compared with that of T76 condition. The T6' with small shearable precipitates resulted in the markedly high ${\Delta}K_{th}$ value. This is thought to be resulted from dislocation reversibility and roughness-induced crack closure due to planarity of slip.

• Journal of the Korea Computer Industry Society
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• v.4 no.4
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• pp.517-522
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• 2003

As the Software development condition is changed into enlargement and complex, requirements generated in each step of Software development life cycle has important effects on the technique and management area. In this thesis, We propose so engineering approach for effective and systematic process and activities including Requirements acquisition and management based on activities proposed with Requirements Engineering and CMM that my special emphasis is putted on Software qualify improvement through the reduction of software development cost and danger.

• Journal of architectural history
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• v.5 no.2 s.10
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• pp.40-52
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• 1996

From the early 1980's, when Chinese government decided to take an Open-Policy. Chinese society faced a new turning point to be changed from traditional-society to modern-society. As a result her outstanding phenomena of civilization is to be seen in many points, like the oid styled traditional street is rapidly replaced by the modernized high-rise buildings. Like the other cities in China, Beijing(北京) also is on the step of modernization, and it's changing speed is faster time by time. In this paper, I'll discuss about Beijing's policy of reservation of Old castles(古城), some problems what they have though the procedure of China's Movement of Old Castle Reservation(古城保護運動). And through this case study, I'd like to focus on the way how we solve some problems what we have now concerning to the reservation and development of traditional cities.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.715-718
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• 2000

The character of a recombinant bioluminescent bacteria's light emission enables us to monitor toxicity in water, soil and air. In this study, various bioluminescent responses to water samples containing toxic chemicals, such as phenol and mitomycin C, were obtained and analysed through the use of a multi-channel two-stage minibioreactor system. The bioluminescent pattern from each channel can be used as a standard for identifying the degree of toxicity in field samples. When various concentrations of toxic chemicals were injected in a step manner, different bioluminescent patterns were obtained. Also this system showed variation in its bioluminescent pattern as the injection manner was changed, i.e. using a modified version of the bell-curve type injection. In conclusion, the toxicity was shown to be related with the bioluminescent response when using these standard bioluminescent patterns. Comparing this standard with a bioluminescent response from a field sample, we can estimate the degree of which the sample is toxic.

• Journal of the Korean Ceramic Society
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• v.28 no.7
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• pp.517-524
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• 1991

The CVD process of BPSG (BoroPhosphoSilicate Glass) and its thin film properties were studied. B2H6, PH3, SiH4 and O2 gases were reacted in a AP (Atmospheric Pressure) CVD system in the temperature range of 300℃ and 460℃. The interaction of B2H6 and PH3 was studied from the deposition rate and dopant incorporation change point of view. The dependency of BPSG step coverage on the temperature was changed with different O2/(B2H6+PH3+SiH4) ratio. Finally, the boundary which distinguishes the stable BPSG's from the ones that react with Di (Deionized) water or cleaning chemicals such as H2SO4, HCl, H2O2, NH4OH etc could be defined.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.249-249
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• 2010

We investigated novel surface treatment and its impact on silicon photovoltaic cells. Using 2-step etching methods, we have changed the nanostructure on pyramid surface so that less light is reflected. This work proposes an improved texturing technique of mono crystalline silicon surface for solar cells with sub-nanotexturing process. The nanotextured silicon surface exhibits a lower average reflectivity (~4%) in the wavelength range of 300-1100nm without antireflection coating layer. It is worth mentioning that the surface of pyramids may also affect the surface reflectance and carrier lifetime. In one word, we believe nanotextruing is a promising guide for texturization of monocrystalline silicon surface.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1-6
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• 1991

This paper is concerned with the design of a robust tracking controller using a state observer on a robotic manipulator under the disturbance. The controller is designed to follow a step or ramp reference input without steady state error in the presence of a disturbance and a system parameter variation. In most cases, since all the state vectors are not measured, unmeasurable state vectors must be estimated or reconstructed. A reduced order observer is proposed to estimate unmeasurable state vectors of the non-linear system. Some problems are caused by the Coulomb friction, the disturbance, and the spring effect of a link between the drive motor and the manipulator arm. The state variables, directly measured and estimated by the reduced order observer, are fed back to the controller. When the robot system exhibits the 'limit cycle, the feedback gains initially obtained by optimal control theory are changed. As a result, the limit cycle is eliminated by the new controller gains,

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.6
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• pp.104-110
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• 1995

In this paper, an effective method for the minimization of two-level Reed-muller expressions by cube selection whcih considers functional complexity is presented. In contrast to the previous methods which use Xlinking operations to join two cubes for minimizatio, the cube selection method tries to select cubes one at a time until they cover the ON-set of the given function. This method works for most benchmark circuits, but for parity-type functions it shows power performance. To solve this problem, a cost function which computes the functional complexity instead of only the size of ON-set of the function is used. Therefore the optimization is performed considering how the trun minterms are grouped together so that they can be realized by only a small number of cubes. In other words, it considers how the function is changed and how the change affects the next optimization step. Experimental results shows better performance in many cases including parity-type functions compared to pervious results.