• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.705-706
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• 2008

There has been, in recent years, effort to make cast copper rotors for industrial use of induction motors. Because the incorporation of copper for the conductor bars and end rings of the induction motor in place of aluminum would result in attractive improvements in motor energy efficiency. The purpose of this method is a reducing the copper loss as using higher conductivity of copper. In this paper as the single phase induction motor is studied, the stator slots and coil turn number is designed for adjusting the slot fill factor and improving its efficiency. At this time design is basis on calculation of reducing loss. And finally this paper shows that the before and after result is compared and analyzed.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.282-287
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• 2007

Hot embossing, one of Nanoimprint Lithography(NIL) techniques, has been getting attention as an alternative candidate of next generation patterning technologies by the advantages of simplicity and low cost compared to conventional photolithographies. A typical hot embossing usually, however, takes more than ten minutes for one cycle of the process because of a long thermal cycling. Over the last few years a number of studies have been made to reduce the cycle time for hot embossing or similar patterning processes. The target of this research is to develop an induction heating apparatus for heating a metallic micro patterning mold at very high speed with the large-area uniformity of temperature distribution. It was found that a 0.5 mm-thick nickel mold can be heated from $25^{\circ}C\;to\;150^{\circ}C$ within 1.5 seconds with the temperature variation of ${\pm}5^{\circ}C$ in 4-inch diameter area, using the induction heating apparatus.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.1
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• pp.3-9
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• 2009

This paper presents the reduction of acoustic noise generated by electromagnetic force in an induction motor of the electrical forklift. After summarizing the electromagnetic excitation forces due to the interaction between the stator/rotor slot permeance and the stator winding magnetomotive force, the effects of the electromagnetic force on the noise and vibration of an induction motor are analyzed. In order to experimentally identify the noise sources of the motor, the signal analyses for noise and vibration are performed by using waterfall plots of noise and vibration spectrums. It is found that severe noise and vibration are caused by the electromagnetic force when the mode number of the excitation shape for a stator is low. Furthermore, it is verified that the motor noise is amplified if the excitation frequency of the electromagnetic force coincides with one of the natural frequencies of the stator. It is experimentally demonstrated that this severe noise can be considerably reduced by structure modifications. Finally, some design guidelines are suggested to develop an induction motor with a low level of noise.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.2
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• pp.162-172
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• 1991

In proportion to the capacity enlargement of the induction motor system controlled by current source inverter, the capacitance of the commutating capacitor is enlarged and then the spike value of output voltage is increased at the moment of charge and discharge. Moreover, the output currnet includes a number of harmonic components. Such voltage spike and harmonics generate the torque ripple and lead to bad effects on the performance of the induction motor. In this study, all the harmonics excluding 17th and 19th harmonics were mostly elimunated by adopting 18-phase Triple High Frequency Current Source Inverter(HFCSI), and the spike component of output voltage was reduced by adding the Voltage Clamping Circuit(VCC). As a result, the torque ripple and the commutation loss were reduced and the performance of the system was improved. Experiments for speed control were carried out in the tripple current source inverter system for induction motor drive. Overall system was controlled by ONE CHIP MICROCOMPUTER(INTEL 8751). Control circuits were simplified and good experimental results in the constant V/F control were obtained due to the flexibility of the microcomputer.

• Journal of Power System Engineering
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• v.10 no.1
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• pp.12-18
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• 2006

A three-degree of freedom model of intake system was contrived and investigated in various ways for the purpose of the amelioration of the volumetric efficiency in a low and transient engine speed for a multi cylinder diesel engine. The basic concept beyond this model started from the theory that each degree of freedom model has volumetric efficiency peak as many as its number of the degree of freedom. The volumetric efficiency affects significantly to the engine performance; torque characteristics, fuel economy and emission level. For commercial vehicles and stationary engines, the engine is designed so as to produce their best performance near the normal engine speeds, thus the low engine speed area has a tendency of poor volumetric efficiency. The aim of this study was highlighted on the amelioration of volumetric efficiency of low engine speed area in a multi cylinder diesel engine matched with an additional Helmholtz resonator. By the use of VIS(variable induction system) volumetric efficiency at low engine speed range was significantly improved. The availability of control by combination of VIS and CIS(conventional induction system) will be proposed as a variable induction system that would be an appropriate model for amelioration of the volumetric efficiency at low engine speed.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.30-30
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• 2019

Pea (Pisum sativum) is one of important legume crops in the world. It is commonly used as a protein source for animal and human diet, and also used as a natural nitrogen source which is produced by a symbiotic bacterium in their root nodule and helpful for terrestrial ecosystem. The successful in vitro manipulation is depended on three main factors including physiology of plant donor, in vitro manipulation approach, and stress physiology during plant cultivation. Moreover, genotype is an important for plant manipulation; different genotype gives the different response to regeneration efficiency. An efficient condition of shoot induction for pea (Pisum sativum cv. 'Sparkle') was developed by using optimum explant, plant growth regulator concentrations, and pretreatment of BA onto explant. The average shoot number per explant showed the highest on two kinds of shoot induction media (MSB5 media containing 2 mg/L BA and a combination of 2 mg/L BA and 1 mg/L TDZ) with cotyledonary node explants culture. Moreover, the pretreatment of explant in 200 mg/L BA solution was found to be more effective in shoot induction than that of non-pretreatment. The analysis of genetic stability of regenerants by using 13 ISSR markers presented that in vitro regenerated plants showed polymorphism with 8.3% compared with their mother plants.

• Corrosion Science and Technology
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• v.14 no.2
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• pp.47-53
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• 2015

Recently, the bending process is greatly applied to fabricate the pipe line. Bending process can reduce welding joints and then decrease the number of inspection. Thus, the maintenance cost will be reduced. Induction heat bending process is composed of bending deformation by repeated local heat and cooling. By this thermal process, corrosion properties and microstructure can be affected. This work focused on the effect of induction heating bending process on the properties of ASME SA106 Gr. C low carbon steel pipes. Microstructure analysis, hardness measurements, and immersion corrosion test were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. Hardness was measured using a Rockwell B scale. Induction heat bending process has influenced upon the size and distribution of ferrite and pearlite phases which were transformed into finer structure than those of base metal. Even though the fine microstructure, every bent area showed a little lower hardness than that of base metal. It is considered that softening by the bending process may be arisen. Except of I2, intrados area, the others showed a similar corrosion rate to that of base metal. But even relatively high rate of intrados area was very low and acceptable. Therefore, it is judged that induction heat bending process didn't affect boric acid corrosion behaviour of carbon steel.

• Journal of Practical Agriculture & Fisheries Research
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• v.25 no.4
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• pp.111-117
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• 2024

Reproductive research such as artificial insemination and embryo transfer is necessary to produce high-quality riding horses. In this study, we investigated the effects of estrus synchronization and ovulation induction methods, which can be considered the basis of artificial insemination in horses, on the hormone concentration and artificial insemination pregnancy rate of mares. For the purpose of synchronization of estrus in horses, Cidr-plus insertion method, Regumate feeding method, and 150mg progesterone + 10mg estradiol mixed administration method were used. In the Cidr-plus insertion method and the Regumate feeding method, the progesterone concentration reached the appropriate level for ovulation induction on the 8th day of administration. The mixed administration method of 150mg progesterone + 10mg estradiol maintained the progesterone concentration at an appropriate level immediately after administration. With the administration of PGF2a and hCG, progesterone concentration decreased rapidly, making ovulation induction possible. As a result of comparing the pregnancy rate between natural estrus and estrus synchronization, the pregnancy rate was found to be higher in estrus synchronization and ovulation induction. From the results of this study, it is insufficient to judge the effect of the pregnancy rate due to the small number of tests, but in terms of usability, estrus synchronization and ovulation induction were useful. Therefore, it is expected to contribute to improving the efficiency of future roadster production.

• The Journal of the Acoustical Society of Korea
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• v.30 no.8
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• pp.446-460
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• 2011

The use of induction motors has been recently increasing with automation in aeronautical and automotive industries, and it playes a significant role. This has motivated that many researchers have studied on developing fault detection and classification systems of an induction motor in order to minimize economical damage caused by its fault. With this reason, this paper proposed feature vector extraction methods based on STE (short-time energy)+SVD (singular value decomposition) and DCT (discrete cosine transform)+SVD techniques to early detect and diagnose faults of induction motors, and classified faults of an induction motor into different types of them by using extracted features as inputs of BPNN (back propagation neural network) and multi-layer SVM (support vector machine). When BPNN and multi-lay SVM are used as classifiers for fault classification, there are many settings that affect classification performance: the number of input layers, the number of hidden layers and learning algorithms for BPNN, and standard deviation values of Gaussian radial basis function for multi-layer SVM. Therefore, this paper quantitatively simulated to find appropriate settings for those classifiers yielding higher classification performance than others.

• Journal of Korean Society of Forest Science
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• v.100 no.4
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• pp.693-697
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• 2011

This study was conducted to examine effects of concentrations of abscisic acid (ABA) or /kinds of osmotica on induction of somatic embryos (SEs), germination and plantlet regeneration in Japanese larch (Larix kaempferi). In comparison of duration of culture, concentrations of ABA and osmoticum, the highest induction number (191/g tissue) of the SE was showed in $60{\mu}M$ ABA+0.2 M sucrose for 4 weeks culture. However, the lowest number (3.5~23.5) of SEs was induced from $4{\mu}M$ ABA+0.1 M sucrose, regardless of culture duration for SEs induction. In comparison of germination efficiency of SEs, the highest induction frequencies of cotyledon (90.9%), hypocotyl (95.8%) and root (96.5%), respectively, were obtained from the SEs that cultured from the treatment of $60{\mu}M$ ABA+0.2 M sucrose with 5 weeks culture. In contrast, the lowest germination response was showed in SEs that induced from the treatment of $4{\mu}M$ ABA+0.1 M sucrose. In comparison of effect of different kinds/concentrations of osmotica for germination and plantlet regeneration, the best response was obtained from the treatment of 0.2 M sucrose with induction of cotyledon (98.3%), hypocotyl (78.4%), root (57.5%) and plantlet regeneration (54.8%), respectively.