• Korean Journal of Computational Design and Engineering
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• v.17 no.5
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• pp.312-323
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• 2012

Planetary gearing is a gear system consisting of one or more planet gears, revolving about a sun gear. While the planetary gear system has many advantages- for example, high power density, large reduction in a small volume, multiple kinematic combinations, pure torsional reactions, and coaxial shafting, it has not been widely used because of its high bearing loads, inaccessibility, and design complexity. It is also necessary to shift several pairs of gear profiles at a same time. Therefore, designing profile shifted planetary gear system is a difficult and know-how dependent job. This study provides a practical solution to design a profile shifted gear system by the procedural design scheme, and proposes a bearing integrated structure of the dual stage profile shifted gear system with a robust output end. A dual stage profile shifted gear system with the bearing integrated structure is manufactured by the proposed design scheme in this study. This gear system is verified that it is good enough to commercialize, because it has high performance with high gear ratio and robust output end against axial and radial directional runouts in a small space.

• Journal of Power Electronics
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• v.13 no.5
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• pp.798-805
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• 2013

This paper presents the control and implementation of the dual-stator-winding induction generator for variable frequency AC (VFAC) generating system. This generator has two sets of stator windings embedded into the stator slots. The power winding produces the VFAC power to feed the loads, and the control winding is connected to the static excitation controller to control the generator for output voltage regulation with speed and load variations. On the basis of the idea of power balance, an instantaneous slip frequency control (ISFC) strategy using the information of both the output voltage and the output power is used in this system. A series of experiments is carried out on a 15 kW prototype for verification. Results show that the system has good static and dynamic performance in a wide speed range, which demonstrates that the ISFC strategy is suitable for this system.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.168-172
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• 2003

This paper analyzes the output noise and the noise figure of common source MOSFET pair each input of which is separately driven in the different frequencies. This analysis is performed for concurrent dual band cascode CMOS LNA with double inputs and single output fabricated in $0.18{\mu}m$ CMOS process. Since both inputs and output are matched to near $50{\Omega}$ using on-chip inductors, the measured noise figures are much higher than those of usual CMOS LNA. But, the main concern of this paper is focused on the added noise features due to the other channel common source stage. The dual-band LNA results in noise figure of 4.54dB at 2.14GHz and 6.03dB at 5.25GHz for selectable operation and 7.44dB and 6.58dB for concurrent operation. The noise analysis explains why the added noise at each band shows so large difference.

• Journal of ILASS-Korea
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• v.16 no.2
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• pp.97-103
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• 2011

The electronically controlled diesel engine was converted to dual fuel engine system. Test engine was set up for investigating the power output, thermal efficiency and emissions. ND 13-mode tests were employed for the engine test cycle. The emission result of dual fuel mode meets Euro-4 (K2006) regulation and the engine performance of dual fuel engine was comparable to the performance of diesel engine. To estimate economical efficiency, test vehicles have been operated on a certain driving route repeatedly. Fuel economy, maximum driving distance per refueling and driveability were examined on the road including free ways. Developed vehicle can be operated over 500 km with dual fuel mode and shows 80% of diesel substitution ratio. Driveability of dual fuel mode is similar with that of diesel mode.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.9
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• pp.380-387
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• 1986

We have developed a dual control algorithm by means of innovations approach and established the stability of dual by introducing the pole-placement method suggested by Berger on the non-dual control. The dual controller realizing this algorithm decreases control loss sharply when compared with that of a non-dual controller, and shows the characteristics of suppressing the output deviation in transient state effectively. The total control energy and the accumulated square misdistance of this dual controller are shown to be 1-10% and 0.1-10% of those of CE control, respectively. Consequently this controller solves the non-minimum phase problem encountered when discretizing the system equation, and can be used to overcome the uncertainty of system effectively by adjusting the learning rate of the controller.

• Progress in Medical Physics
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• v.23 no.4
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• pp.229-233
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• 2012

A small water phantom (dual-window phantom) was developed to improve the output measurement efficiency of medical linacs. This phantom is suitable for determining the quality index and output dose for high-energy photon beams. The phantom has two opposite windows and two independently rotating axes. The two axes measure the tissue phantom ratio (TPR) and the percentage depth dose (PDD) simply without requiring chamber movement by rotating the phantom around its axis. High-energy photon beams from a Co-60 irradiator and a medical linac were used to evaluate the phantom. The measured quality index is in good agreement with the reference values; the measured and reference values are within 0.2% of each other for the Co-60 gamma rays and within 1.4% for 6 and 10 MV X-rays. This phantom is more practical for routine output measurements, resulting in the prevention of potential human errors.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.5
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• pp.400-409
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• 2001

A new phase-shifted parallel-input/series-output(PISO) dual converter for tush-power step-up applications has been proposed. Since the proposed converter shows a low switch turn-off voltage stress, switching devices with low conduction loss can be employed in order to improve the power conversion efficiency. Moreover, it features a low output capacitor root-mean-square(RMS) current stress, low input current and output voltage ripple contents, and fast control-to-output dynamics compared to its PWM counterpart. In this paper, the operation of the proposed converter is analyzed in detail and its mathematical models and steady-state solutions are presented. A comparative analysis with the conventional PWM PISO dual converter is also provided. To confirm the operation, features, and validity of the Proposed converter, experimental results from an 800W, 24-350Vdc prototype are presented.

• Proceedings of the KSRS Conference
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• v.2
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• pp.784-787
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• 2006

Dual-polarized transmission is one of the effective methods to transmit such a high speed data thanks to two independent channel leads to the orthogonal feature between RHCP (Right-Hand Circular Polarization) and LHCP (Left-Hand Circular Polarization). However, in practical case, the transmitted signal by RHCP polarized antenna in satellite can be occurred at the output port of LHCP polarized antenna in ground station, vice versa. XPD (Cross-Polarization Discrimination) is the ratio of the signal level at the output of a receiving antenna that is nominally co-polarized to the transmitting antenna to the output of a receiving antenna of the same gain but nominally orthogonally polarized to the transmitting antenna. In this paper, the detailed estimation of XPD within the interface between satellite and ground station is written and the influence of XPD to link performance is also described.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.1
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• pp.11-19
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• 2010

A gas-assisted hydraulic breaker uses both hydraulic and pneumatic energies and the appropriate balance between them mostly effects its performance. Mathematical modeling of the breaker is established and verified by experiment. Through sensitivity analysis using AMESim, the key design parameters are selected, which mostly affect the performance of the breaker. Taguchi method is used to optimize the key design parameters to maximize the output power for long and short strokes through simulation. As the result, the output power as well as the impact energy are increased significantly compared with the existing design. The pressure pulsation in the supply line is reduced to a tolerable level and the dynamic characteristics of the piston displacement is also improved by the optimization.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.189-192
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• 2001

A new phase-shifted parallel-input/series-output dual converter for high-power step-up applications has been proposed. It features a high efficiency due to the low switch turn-off voltage, low device stresses, low ripple contents, and a fast control-to-output dynamics compared to its PWM counterpart. To confirm the validity of the proposed converter, experimental results from an 800W, 350Vdc prototype are presented.