• 한국산업융합학회 논문집
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• 제23권3호
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• pp.499-505
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• 2020

Capacitor-run single-phase induction motor is cheaper than motors that use permanent magnets and is widely used in home appliances and industries based on relatively high durability and productivity. It can also be operated by line. However speed cannot be controlled because the line frequency is free. In this paper we dealt pole change method one of the method controlling speed of capacitor-run single-phase induction motor. The conventional pole change method is difficult to improve the power and efficiency of the motor because the composition of the pole change device is complex and do not have enough area of the windings because of windings not used according to the driving conditions. In this paper, we proposed the pole change method that is used main windings and auxiliary windings at 4 poles operation and used auxiliary windings as compensation windings at 2 poles operation. The proposed method was verified through finite element analysis.

• 한국유체기계학회 논문집
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• 제14권5호
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• pp.69-74
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• 2011

This paper deals with the detail rotordynamic analysis for the vertical rotor system as development of vertical sea water lift pump for FPSO deep well. In a vertical rotor system, since linearized stiffness and damping coefficients of fluid film bearing are no longer be valid, hence the transient response analysis considering a fluid film force for every journal position in the bearing needs to be required. In this study, the transient response analysis of the proposed vertical pump rotor system was carried out in dry-run and wet-run conditions, respectively. The results show that orbital vibration responses of the rotor system remain stable at rated speed and thereby operating reliability of the vertical rotor system is confirmed. To overcome complexity of calculation pr ocedure and time consuming calculation of transient analysis, the calculating technique of steady-state response analysis is also proposed. The results of steady-state response obtained by applying the proposed technique to the rotor system are good agreement with the reference results, that is, transient responses.

• ETRI Journal
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• 제39권3호
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• pp.301-309
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• 2017

In this paper, we propose a parallelization method for a High Efficiency Video Coding (HEVC) deblocking filter with transform unit (TU) split information. HEVC employs a deblocking filter to boost perceptual quality and coding efficiency. The deblocking filter was designed for data-level parallelism. In this paper, we demonstrate a method of distributing equal workloads to all cores or threads by anticipating the deblocking filter complexity based on the coding unit depth and TU split information. We determined that the average time saving of our proposed deblocking filter parallelization method has a speed-up factor that is 2% better than that of the uniformly distributed parallel deblocking filter, and 6% better than that of coding tree unit row distribution parallelism. In addition, we determined that the speed-up factor of our proposed deblocking filter parallelization method, in terms of percentage run-time, is up to 3.1 compared to the run-time of the HEVC test model 12.0 deblocking filter with a sequential implementation.

• 한국소음진동공학회논문집
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• 제19권6호
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• pp.614-619
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• 2009

The STW(servo track writing) system which is the process of writing servo signals on disks before assembling in drives uses the spindle motor-chuck mechanism to realize low cost because the spindle motor-chuck mechanism has merit which can simultaneously write multi-disk by piling up disks in hub. Therefore, when the spindle motor-chuck mechanism of horizontal type operates in high rotation speed it is necessary to reduce the effect of RRO(repeatable run-out) and NRRO(non-repeatable run-out) to achieve the high precision accuracy of nano-meter level during the STW process. In this paper, we analyzed that the slip in assembly surfaces can be caused by the mechanical tolerance and clamping force in hub-chuck mechanism and can affect NRRO performance. We designed springs for centering and clamping considering centrifugal force by the rotation speed and assembly condition. The experimental result showed NRRO performance improves about 30 % than case of weak clamping force. The result shows that the optimal design of the spindle motor-chuck mechanism can effectively reduce the effect of NRRO and RRO in STW process.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.769-775
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• 2021

The objective of this research was to analyze the factors influencing the farm-gate shrimp prices in Thailand using monthly time series from January 2001 to December 2019. The econometric methodology was employed to satisfy the purpose, consisting of the cointegration test for revealing the long-run relationship and equilibrium elasticity between the variables as well as the error correction model for detecting speed adjustment to shock responses. The empirical results revealed that (1) the export shrimp prices, shrimp production in the country, and shrimp export volume indicated a long-run relationship running to the farm-gate shrimp prices in Thailand with the size of equilibrium elasticity equal to 1.083%, -0.256%, and 0.123, respectively, and (2) the farm-gate shrimp prices in Thailand would adjust to the equilibrium line with a speed equal to 20.147% if there was any kind of incident or shock which caused the relationship to deviate from the equilibrium point. There was no relationship in terms of global shrimp prices and the exchange rate for farm-gate shrimp prices in Thailand. The recommendations should emphasize the varieties of shrimp products for export to other countries beyond the main trading markets nowadays to reduce risks and fluctuations in the export prices of shrimp products.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2456-2463
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• 2011

Conventional railways are less competitive than other land transportation means in term of speed, and thus users preference and transportation share for rail system are relatively lower than others. For example, most of the conventional lines except the Seoul~Busan corridor run at an average speed of 70 km/h or less, which imposes certain constraints on roles and functions as the trunk lines. In this regard, the speed of the conventional lines should be improved up to 200 km/h to gain competitiveness, promote balanced regional development and lead the era of low carbon green growth. As track system is one of the most important elements for the speed-up, it is critical to come up with optimum technical solutions. Improvement of ballast track structure with efficient track installation can provide structural stability for higher speed and ensure operational safety with lower maintenance efforts. Thus, this study focuses on consequences followed by the speed-up including increase of load imposed on the track and impacts on track components, and provide solutions for track maintenance by analyzing impact on the track structure by speed. Also, it compares ballast and concrete tracks under designing and construction and considers how to meet needs for passengers comfort and environmental requirements as a strategic approach.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1749-1752
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• 2005

High speed machining has become the main issue of metal cutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evaluation of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.

• 한국정밀공학회지
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• 제23권3호
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• pp.147-155
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• 2006

High speed machining has become the main issue of metal rutting. Due to increase of the rotational speed of the spindle, problems, such as the run-out errors, reduced stiffness, must be overcome to improve the machining accuracy. In order to solve the problems, it is important to determine the appropriate clamping unit and tooling system. This paper presents an investigation into an evolution of contact interval which is the interface between spindle taper hole and tool holder shank of the spindle. Finite element analysis is performed by using a commercial code ANSYS according to variation of clamping forces and rotational speeds. This paper proposed fit tolerance in order to evaluate the effects of clamping force and rotational speed on the contact interval in the spindle interface. From the finite element results, it has been shown that the rotational speed rather than clamping force mostly influence on the variation of the contact interval.

• 한국운동역학회지
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• 제22권1호
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• pp.35-42
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• 2012

The aim of the present study was to investigate effect of running speed conditions on the kinematic pattern of the metatarsus, mid-foot, calcaneus. Twenty-two healthy young adults were made to run on treadmill at three different running speeds(normal speed, 9.2; slow speed, 7.4; fast speed, 11.1km/hr.) and the trajectories of the 10 reflective markers for each subject were recorded by an eight-camera motion capture system at 200 Hz. Three-dimensional angles for the foot segment in the support phase during running were calculated according to Euler's technique. Results showed that running speed did not affect the peak of the dorsi/plantar flexion, inversion/eversion, and adduction/abduction or their range of motion for each foot segment. However, when the running speed was fast, significant differences were found in the peak of the plantar flexion, eversion, and adduction and ROM(range of motion) of the dorsi/plantar flexion, inversion/eversion, and adduction/abduction between the foot segments, metatarsus, mid-foot, and calcaneus. It was proposed that the foot segment should be analyzed from a multi-segment system point of view on the basis of anatomical reference during locomotion.

• Journal of Power Electronics
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• 제14권5호
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• pp.967-979
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• 2014

This paper focuses on speed and current sensor fault detection and isolation (FDI) for induction motor (IM) drives. A new, accurate and high-efficiency FDI approach is proposed so that a system can continue operating with good performance even in the presence of speed sensor faults, current sensor faults or both. The proposed three paralleled adaptive observers are capable of current sensor fault detection and localization. By using observers, the rotor flux and rotor speed can be estimated which allows the system to run under the speed sensorless vector control mode when a speed sensor fault occurs. In order to detect speed sensor faults, a threshold-based scheme is proposed. To verify the feasibility and effectiveness of the proposed FDI strategy, experiments are carried out under different conditions based on a dSPACE DS1104 induction motor drive platform.