• Journal of Navigation and Port Research
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• v.28 no.8
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• pp.667-671
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• 2004

This paper describes an development of digital power supply for ship's emergency lighting system(SELS). Proposed system is composed of emergency power supply system(EPSS), half bridge(HB) inverter, fluorescent lamp(FL) starting circuit and microprocessor control system. Experimental works using proposed system confirm that speedy and stable power to be supplied when main power source cut-off, compared with conventional analog type, and control input power up to 35.0［%］ by adjusting pulse frequency of the HB inverter.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.5
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• pp.517-523
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• 1999

The Start-up transformers or on-site stand-by transformers are installed for the start-up and shut-down of generator and emergency status in unclear power plant. The on-site power supply configuration using these transformers must be detemined by considering configuration requirements, site characteristics, reliability and availability severely because it is remarkably important for safety and benefit of plant. The start-up or stand-by power supply configuration has been determined considering only safety requirements and construction cost up to now in Korea. I study various reliability estimating methods for the prediction of availability, and estimate the unavailability for the start-up power supply system of two 1,000㎿ unclear power plants. I also detemine the reliability and unavailability and unavailavility of equipment, system and configuration using FTA method.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.3
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• pp.51-58
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• 2008

This paper is a study of a prevention of power folding controller's thermal degradation. Power folding technology has been applied for many fields such as side rear vision mirror of vehicles, windshield wiper, antenna, power window. These controllers have been comprised with traditional DC moors, Switching electronic devices, and relays. But this methods have a limitation to overcome such problems of product reliability, endurance, noise margins. Therefore on this paper, to detect the movement of motor, sensing motor brush noise on a load sensing part has been used and controlling a precise RC timing control minimizes the thermal deterioration of motor. And using MOS FETs as a electronic switching device increases life-time and liability of control circuit. After testing such circuit and control method, repetition of operating time, cut-off time, wide operation voltage, power noise margin ware increased over eleven-fold.

• Journal of Distribution Research
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• v.12 no.3
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• pp.91-109
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• 2007

This paper intends to examine the antecedents to the ex-post supply price cut which is typical retailer's unfair trade practices from three perspectives such as market power, efficiency, and retailer's tendency. For the empirical research, we analyzed manufacturer's 79 key account managers who have traded with domestic discount stores. As a result, the harder a retailer tries to increase sales and margin simultaneously, the more the retailer tends to use the ex-post supply price cut against manufacturers. In addition, the most frequent pattern of ex-post supply price cut occurs after retailer's discount at discretion. Finally, we suggest this research's implications, limitations of this research with future research directions.

• Food Science and Preservation
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• v.30 no.3
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• pp.369-382
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• 2023

We examined the changes in the physicochemical quality characteristics and antioxidant activity of fresh-cut Fuji apples (Malus pumila) during processing and storage after treatment with browning inhibitors. The primary aim was to elucidate processing suitability and storability. We observed that in the processing stage of slicing fresh Fuji apples, there were no significant differences in 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging ability and ferric-reducing antioxidant power (FRAP). However, after NaClO treatment, total flavonoid and total polyphenol contents decreased. When freshcut Fuji apples were treated with browning inhibitors and stored at 4℃, the L value and hardness decreased; however, the weight loss rate increased based on the storage period of all fruit groups treated with Citrus unshiu Markovich (CuM), calcium ascorbate (CA), and ascorbic acid (AA). The pH increased after 2 days of storage in 1% CuM and after 6 days of storage in 1% CA; however, no changes in pH were observed during the storage period in 1% AA. The DPPH radical scavenging activity was generally good under storage conditions of 1% AA at 4℃ and 1% CA at 20℃. Furthermore, FRAP remained relatively constant under storage conditions of 1% CA. The quality characteristics and antioxidant activity of fresh-cut fruits during processing and storage can be used as basic data for industries. Furthermore, we can gain confidence in quality improvements by improving the production and distribution environment of fresh-cut agricultural products.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.101-107
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• 2023

Machine tools are widely used in mechanical manufacturing corporations, as well as in engineering courses at universities in Vietnam. The PINACHO S-90/200 lathe is particularly popular. This paper aims to research and select an optimal cutting depth to minimize power costs and ensure surface roughness quality when machining upper plain cylindrical turning products with the PINACHO S-90/200 lathe on C45 steel material.

• Journal of Power System Engineering
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• v.4 no.3
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• pp.55-61
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• 2000

In this study, a new design of an one-body type of an unbalanced-fixed- displacement type vane pump combined with an induction type electric motor was suggested. By the application of the new design scheme, it was possible to reduce the number of parts of the pump system and to cut down the volume of power package than that of already-used products. The case in this study enabled efficient heat transfer and electricity insulation of hydraulic fluid. Thus oil moves through the inside of the package for cooling and returns to the reservoir. Because of this design, it was difficult to measure the shaft-input torque. Therefore the package overall efficiency in the paper was evaluated with a ratio of hydraulic power and electric power.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.3
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• pp.12-18
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• 2001

Frequency domain has been used to detect chatter vibration and to decide commencing point of chatter for the milling processes. For this, power spectrum of accelerations signal is analyzed in the frequency domain. Also, the power spectrum and surface roughness are measured, compared, and evaluated according to the depth of cut by experimental works. As a results, it is known that the commencing point of chatter can be decided the behavior of the maximum amplitude of the power spectrum of acceleration signal and there is a correlation between the power spectrum of acceleration signal and the surface roughness. In conclusion, the power spectrum of acceleration signal can be used as a useful information for detec-tion and estimation of chatter vibration in machining.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.12
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• pp.136-141
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• 1995

GaAs power MESFETs with 1 .mu.m gate length and an undoped GaAs surface layer on the doped GaAs channel are fabricated using IR(image reversal) and air-birdge processes. And then We have measured and calculated DC and RF characteristics. We have obtained saturation current 107-500 mA (197-255 mA/mm), maximum linear RF output power 111-518.8 mW (204-270 mW/mm), current gain cut-off frequency 7-10 GHz, maximum unilateral transducer power gain 5.7-12.7, and power added efficiencies 37.9-41.2 % from the devices with gate width 0.45-2.2 mm, at 6 GHz.

• Journal of Power Electronics
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• v.13 no.3
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• pp.497-506
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• 2013

This paper proposes a new method to improve the available battery capacity in electric vehicles by connecting lead-acid batteries with lithium-ion battery in parallel to supply power. In addition, this method combines the discharge characteristics of batteries to improve their efficiency and lower their cost for electric vehicles. A lithium-ion battery set is used to connect with N sets of lead-acid batteries in parallel. The lead-acid battery supplies the initial power. When the lead-acid battery is discharged by the load current until its output voltage drops to the cut-off voltage, the power management unit controls the lead-acid battery and changes it to discharge continuously with a small current. This discharge can be achieved by connecting the lead-acid battery to a lithium-ion battery in parallel to supply the load power or to discharge its current to another lead-acid or lithium-ion battery. Experimental results demonstrates that the available capacity can be improved by up to 30% of the rated capacity of the lead-acid batteries.