• Geomechanics and Engineering
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• 제6권5호
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• pp.419-436
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• 2014

Soil improvement by preloading with PVD in combination with vacuum is helpful when a considerable load is required to meet the desired rate of settlement in a relative short time. To facilitate the vacuum propagation, vertical drains are usually employed in conjunction. This ground improvement method is more and more applied in the Mekong delta of Vietnam to meet the needs of fast infrastructure development. This paper reports on a pilot test that was carried out to investigate the effect of ground improvement by vacuum and PVD on the rate of consolidation at the site of Saigon International Terminals Vietnam (SITV) in Ba Ria-Vung Tau Province, Viet Nam. Three main aspects of the test will be presented, and namely, instrumentation and field monitoring program, calculation of consolidation settlement and back-analysis of soil properties to see the difference before and after ground improvement.

• 오토저널
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• 제12권3호
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• pp.30-40
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• 1990

The computer program for the prediction of the volumetric efficiency of 4-cycle single cylinder diesel engine was developed using the characteristic method which considers the effects of friction, heat transfer and specific heat. The results of calculation by this program are as follows; 1. The back flowing was arised at the beginning and the closing stage of inlet valve, and the back flowing mass and velocity decrease as the engine speed increases. 2. The volumetric efficiency varies with the engine speed and the length of inlet manifold. There was an optimum length of inlet manifold for each specified engine speed. 3. The pressure fluctuation and friction effect in the inlet manifold became very important factors for the determination of the volumetric efficiency.

• 전기학회논문지
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• 제56권3호
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• pp.519-523
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• 2007

In this paper, we propose a precise parameter extraction of interior permanent magnet (IPM) motors based on finite element analysis. For the calculation of the two-axis inductances Ld and Lq, the slotting effect and cross magnetization due to torque angle are considered. It is examined that back electro-motive force (BEMF) constant is affected by the magnetic saturation in different ways dependent on motor types. Numerical analyses and some measurements are performed for a spoke type and a flux barrier type IPM motors

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1172-1175
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• 1992

The conventional adaptive hysteresis band current control technique has disadvantages such that on-line calculation of the hysteresis band is very complex, therefore, the adaptive hysteresis band must be stored in the look-up table. In this paper, a new simplified adaptive hysteresis band current control technique with phase decoupling is presented. The adaptive band is independent of the back EMFs. Using this adaptive band and the phase decoupled current error, the modulation frequency is fixed at nearly constant and the PWM inverter has optimal switching pattern.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.147-149
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• 2000

This paper describes a power flow method for distribution systems, applying the method of symmetrical component to back/forward sweep method. The proposed algorithm is effective for unbalanced radial distribution system, with process of distributed resource(PQ & PV node), AVR(Auto Voltage Regulator), shunt capacitor. This proposed method compared conventional back/forward sweep method with the using three phase unbalanced distribution systems with 34 nodes.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.235-242
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• 2001

Hydraulic performance of LCH4 fuel inducer in turbopump system was predicted by 3-D Wavier-stokes calculation. The inducer was designed initially using 1-D method. Different parameters with blade angle and flow coefficient were set from the initial design one, md computation was fulfilled to assess the redesigned models. Especially, influence of inlet back flow on inducer performance and its effective control were explored. The numerical results showed that through reducing inlet back flow strength., the hydraulic efficiency of inducer could be improved up to about $20\%$ compared to that of the initial design one.

• Journal of Radiation Protection and Research
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• 제28권4호
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• pp.361-368
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• 2003

The economic and environmental friendliness analysis of the nuclear fuel cycle options that can be expected in Korea were performed. Options considered are direct disposal, reprocessing and DUPIC (Direct Use of Spent PWR Fuel In CANDU Reactors). By considering the result of calculation of the annual uranium requirement and nuclear spent fuel generation by analysis of nuclear fuel material flows in the nuclear fuel cycle options, we decided the time of back-end nuclear fuel cycle processes and the volume. Then we can analyze the economic and environmental friendliness by applying the unit cost and unit value of each process, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.401-403
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• 2001

This paper describes a power flow method for distribution systems, applying the method of symmetrical component to back/forward sweep method. The proposed algorithm is effective for unbalanced radial distribution system, with process of AVR(Auto Voltage Regulator), shunt capacitor. The proposed method was compared with the conventional Back/forward sweep method by using three phase unbalanced distribution systems of 123 nodes.

• 전기학회논문지
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• 제64권4호
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• pp.523-528
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• 2015

A new algorithm for a coordinative control method is proposed with respect to voltage control and system stabilization of local substations. This is accomplished using control cooperation between a static synchronous compensator (STATCOM) and the existing voltage compensation equipment in the steady state and emergency state of a power system. A real-time system analysis was developed by combining a system analysis program with InTouch, which has primarily been used in factory automation for verification. PSS/E was used for the load flow calculation software, Python for language, Intouch as an HMI program, and MS SQL for the database. To test this system, the system in the vicinity of the Migeum and the Migeum substations was modeled and simulated.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.213-214
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• 2014

This paper compares two instantaneous reactive power definitions in DFIG wind turbine with a back-to-back three-level neutral-point clamped voltage source converter under unbalanced grid conditions. In general, conventional definition of instantaneous reactive power is obtained by taking an imaginary component of complex power. The other definition of instantaneous reactive power can be developed based on a set of voltages lagging the grid input voltages by 90 degree. A complex quantity referred as a quadrature complex power is defined. Proposed definition of instantaneous reactive power is derived by taking a real component of quadrature complex power. The characteristics of two instantaneous reactive power definitions are compared using the ripple-free stator active power control algorithm in DFIG. Instantaneous reactive power definition based on quadrature complex power has a simpler current reference calculation control block. Ripple of instantaneous active and reactive power has the same magnitude unlike in conventional definition under grid unbalance. Comparison results of two instantaneous reactive power definitions are verified through simulation.