• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.468-468
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• 1991

The variable-frequency type water supply equipment, which adopts the variable-voltage and variable-frequency converter(VVVF converter) to govern automatically the rotating speed of a pump, can save 15-20% of power, as compared with a throttle-controlled pump device or an airpressurized water supply equipment, and is finding a wide application. However, it still has some disadvantages : greater pressure fluctuations during switching over the pump and prolonged low-effeciency running of the pump in the case of small consumption of water. Therefore, it is difficult to apply the equipment to the fire water supply system where the water should not be put into use unless a fire takes place, and the water pressure in pipelines should permanently remain constant. This paper introduces the automatic regulation principle of the variable-frequency type air-pressurized water supply equipment (hereafter referred to as simply BFQS equipment) for dual purposes of daily life and fire control, which combined both technologies of speed governing by a converter and air-pressurized water supplying, then discusses some problems related to automatic control, and finally gives the experimental results of an embodiment-BPQS-100-50 water supply equipment.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2098-2100
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• 1997

The present paper investigates the optimal operation of a switched reluctance motor such that overall drive efficiency is maximized under a variable supply voltage. The operation under a variable supply voltage exhibits the improved drive efficiency in the full range of operating torque and speed, and exhibits the expanded range of operating torque and speed. Furthermore a variable supply voltage may be utilized in reducing torque ripple.

• Proceedings of the KIEE Conference
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• summer
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• pp.1205-1207
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• 2004

AC plasma power supply is used to control a ozone generator and a air pollution gas. AC plasma power supply is composed of power semiconductor switch devices and control board adapted SHE(Selected Harmonic Elimination) PWM method. AC plasma power supply with sinusoidal VVVF(variable voltage and variable frequency) is realized. Its output voltage range is from 0 [V] to 20[kV] and output frequency range is from 8[kHz] to 20[kHz]. Using proposed system, AC high voltage and high frequency discharge is tested in the DBD(dieletric barrier discharge) reactor, and the space distribution of a its non-thermal plasma is observed. In spite of the increasement of voltage and frequency, the proposed system have a stable operation characteristics. It is verified by the experimental results.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1221-1226
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• 2015

This paper proposes a multiple switch mode power supply (SMPS) system based on the wireless network which controls variable load. The system enables power supply of up to 600W using 200W SMPS as a unit module and provides a controlling function of output power based on variable load and a monitoring function based on wireless network. The controlling function for output power measures the variation of output power and facilitates efficient power supply by controlling output power based on the measured variation value. The monitoring function guarantees a stable power supply by observing the multiple SMPS system in real time via wireless network. The performance of the proposed system was examined by various experiments. In addition, it was verified through standardized test of Korea Testing Certification. The results were given and discussed.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.364-368
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• 1999

This paper suggests switching regulator technique to overcome the drawback of conventional variable linear power supply. Switching regulator technique can eliminate the extremely lossy operation and reduce the size and weight of variable linear power supply and provide nearly constant output power over the majority of output voltage range. The topology of variable switched mode power supply is employed active clamp forward converter with a current doubler rectifier and by using control of variable-frequency together with control of fixed-frequency, output voltage can be controled. Equivalent circuits pertinent to each operational mode of converter are derived, and an experimental 20V, 50A converter was designed and built. The converter operates from an output voltage of zero to 25 V, under 100 kHz switching frequency.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.1
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• pp.25-31
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• 2003

This paper addresses an oil supply enhancement device to resolve a shortage of oil supply or no oil supply at all encountered at low speed operation for a variable speed reciprocating compressor used for household refrigerators. The oil supply enhancement device comprises a moving cylinder attached to the lower end of crankshaft and two of fluid diodes, each one at the inlet and outlet of the cylinder. Up-and-down movement of the cylinder against the lower end of the crankshaft together with the functioning of the two fluid diodes produces net oil flow from oil reservoir to inside the crankshaft. The experiment on the test bench has shown that enough oil supply into the oil feeding hole cu be made by using this device even at low speed range. Some analytical study has also been carried out to under-stand its oil supply mechanism.

• Journal of Korean Society of Forest Science
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• v.95 no.5
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• pp.539-542
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• 2006

This study confirmed econometrically the causality of forest inventory and roundwood supply using Korean data. In general, forest inventory is included as explanatory variable in roundwood supply function. We checked whether each series is stationary or not before using it in the model, and determined whether the combination of the series is comtegrated. The relationship between forest inventory and roundwood supply was represented by bivariate vector autoregressive model. The causality of forest evidence of the causal relationship between change in forest inventory and change in roundwood supply in Korea. That is, change in forest inventory does not cause change in roundwood supply in Korea. It seems reasonable not to include forest inventory as explanatory variable in roundwood supply function in Korea.

• Journal of Distribution Science
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• v.11 no.4
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• pp.51-60
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• 2013

Purpose - The objective of this paper is to investigate the effect of asset specificity, the level of information sharing, the importance of information sharing, and an integrated collaborative environment on supply chain performance. Research design, data, and methodology - Data collection was implemented as follows: questionnaires were distributed to 250 companies that have business ties with Halla Climate Control Corporation. The empirical study to test our hypothesis was based on statistical analysis (using SPSS 18.0 and AMOS 18.0). The hypothesis of this paper is that the asset specificity variable has positive effects on the following variables: Level of information sharing, the importance of information sharing, and integrated collaborative environment. Moreover the variables, the level of information sharing, and the importance of information sharing are strongly influenced by the variable integrated collaborative environment, and these when combined, have an effect on the dependent variable, supply chain performance. We tested our hypothesized model utilizing path analysis with latent variables. Results - According to the results of our analysis, hypothesis H1, which tests whether there is a relationship between asset specificity and the integrated collaborative environment, is supported at the 0.01 level. Hypotheses H2 and H3 were also confirmed, and asset specificity had positive effects (+) on the level of information sharing variable. The importance of the information sharing variable was statistically significant at the 0.01 level. Hypotheses H4 and H5 posited that the integrated collaborative environment variable would have a positive effect on the level of information sharing; the importance of information sharing variable was strongly supported statistically, with a significant p-value below. Moreover, the level of information sharing (H6), and the importance of information sharing (H7) variables also had a statistically relevant influence on supply chain performance. As a result, existence of a collaborative system between companies would influence supply chain performance by strengthening real-time information access and information sharing. Thus, it is important to construct a collaborative environment where information sharing among companies and cooperation is possible. Conclusions - First, with rapid changes in the business environment, it becomes necessary for enterprises to acquire the right information in order to properly implement SCM. For successful SCM, firms should understand the importance of collaboration with supply chain partners and an internally built collaboration system, which in turn will better promote a partnership commitment with suppliers as well as collaborative integration with buyers. A collaborative system, as we suggest in this paper, facilitates the maintenance of a long-term relationship of trust, and can help reinforce information sharing. Second, it is necessary to increase information sharing over time via a collaborative system so that employees of the suppliers become aware of the system. The more proactive and positive attitudes are towards such a collaborative system by the managerial group, the higher the level of information sharing will be among the users. Successful SCM performance is achieved by information sharing through a collaborative environment rather than by investing only in setting up an information system.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.114-118
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• 1994

A comprehensive analytical study of frequency-modulated supply of the dynamic instability in a variable-reluctance stepping motor, is described. It is shown that stability can be achieved by frequency modulation provided that the phase displacement between the modulating signal and the rotor velocity oscillation lies between certain limits. A simplified expression is derived. based on the assumption of high inertia. This model is used to obtain a qualitative understanding of how frequency modulation influences the dynamic stability of the variable-reluctance motor.

• Information Systems Review
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• v.17 no.1
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• pp.199-215
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• 2015

Supply chain integration is the degree to which a firm strategically collaborates with its supply chain partners. We study the relationship between supply chain integration and corporate performance and the role of information sharing between them. When the information sharing is used as a mediating factor between supply chain integration and performance, supply chain integration should be focused to enhance the performance because of their causal relationship among them. On the contrary, when the information sharing is used as a moderating factor, situational approach to improve performance is needed. This study collected 199 questionnaires from the manufacturing companies and used Amos 21 to analyze the measurement model and structural model. The study found that supply chain integration positively influences corporate performance and information sharing acts as a mediating variable between supply chain integration and corporate performance. Therefore the firm should pay additional attention on supply chain integration to improve the corporate performance.