• Journal of Power Electronics
• /
• v.12 no.2
• /
• pp.344-356
• /
• 2012

In recent years, multilevel technology has become an effective and practical solution in the field of moderate and high voltage applications. This paper discusses an APF with a three-level NPC inverter. Obviously, the application of such converter to APFs is hindered by the problem of the voltage unbalance of DC capacitors, which leads to system instability. This paper comprehensively analyzes the theoretical limitations of the neutral-point voltage balancing problem for tracking different harmonic currents utilizing current switching functions from the space vector PWM (SVPWM) point of view. The fluctuation of the neutral point caused by the load currents of certain order harmonic frequency is reported and quantified. Furthermore, this paper presents a close-loop digital control algorithm of the DC voltage for this APF. A PI controller regulates the DC voltage in the outer-loop controller. In the current-loop controller, this paper proposes a simple neutral-point voltage control method. The neutral-point voltage imbalance is restrained by selecting small vectors that will move the neutral-point voltage in the direction opposite the direction of the unbalance. The experiment results illustrate that the performance of the proposed approach is satisfactory.

• Korean Journal of Plant Tissue Culture
• /
• v.21 no.4
• /
• pp.201-206
• /
• 1994

The influx of glycine, valine, alanine, and histidine was inhibited by all tested neutral amino acids competitively and the reciprocal inhibitory studies showed the neutral amino acids possess the same transport system as neutral amino acids process to the same catalytic site of one carrier to each other, The molecules of histidine were transported actively as a neutral form through the neutral amino acid transport system but were not transported as a charged form. The Km values of the neutral amino acid transport system have been divided into three different category on basis of the affinity to the carrier, below 0.1mM, etween 0.1ImM-0.5mM and above 0.5mM. The $V_{max}$ was between $3.12{\mu}mole{\cdot}h^{-1}{\cdot}g$ fresh $weight^{-1}\;-\;15.1\;{\mu}mole{\cdot}h^{-1}{\cdot}g$ fresh $weight^{-1}$. Neutral amino acids cotransported with one $H^{+}per$ one molecule and one $K^{+}-efflux$ per one molecule for charge compensation. Histidine cotransported with proton per one molecule, however the movement of cotransported proton can't detectable because of the release of proton from the charged molecules of histidine in the medium.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.61 no.3
• /
• pp.111-115
• /
• 2012

Generally, brushless DC motor(BLDCM) driving system uses hall sensors or encoders as the mechanical position or speed sensor. It is necessary to achieve the informations of rotor position for driving trapezoidal type brushless DC motor without any position sensor. In this paper, the commutation signals are obtained without the motor neutral voltage, multistage analog filters, A/D converters, or the complex digital phase shift circuits which are indispensable in the conventional sensorless control algorithms. In the proposed method, in stead of detecting the zero crossing point of the nonexcited motor back electromagnetic force for the average motor terminal to neutral voltage, the commutation signal are extracted directly from the specific average line to line voltage with low-pass filter, adder and comparators circuit. In contrast to conventional methods, the neutral voltage is not need; therefore, the commutation signals are insensitive to the common mode noise. Moreover, the complex phase shift circuit can be eliminated. The effectiveness of the proposed method is verified through simulation results.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1790-1791
• /
• 2011

In this paper, the diagnosis system for detecting and localizing the neutral wire defect in an energized XLPE power cable is proposed. The neutral wire defect is detectd and localized by the time-frequency domain reflectometry. To extract the reflected signal from the neutral wire defect, the adaptive RLS filtering is introduced. To verify the proposed method, the experiments for detecting and localizing neutral wire defect in active XLPE power cable is conducted.

• Korean Journal of Computational Design and Engineering
• /
• v.14 no.2
• /
• pp.96-104
• /
• 2009

It gradually becomes important to study on how to efficiently integrate and manage plant lifecycle data such as 2D schematic and 3D solid data, logical configuration data, and equipment specifications data. From this point of view, converting plant design data from various systems into neutral data independent from any commercial systems is one of important technologies for the operation and management of plants which usually have a very long period of life. In order to achieve this goal, a neutral model for efficient integration and management of plant data was defined. After schema mapping between one of specification-driven plant design systems and the neutral model was performed, a plant data translator is also implemented according to the mapping result. Finally, by experiments with nuclear power plant design, the feasibility of the translator was demonstrated.

• Nuclear Engineering and Technology
• /
• v.37 no.3
• /
• pp.221-230
• /
• 2005

This paper reviews the pivotal phases of the evolution of the current technology-dependent nuclear power safety regulation in the United States. Understanding of this evolution is essential to the development of any future regulatory paradigm, including the technology-neutral regulatory approach that the U.S. Nuclear Regulatory Commission (NRC) has recently embarked on to develop. The paper proposes and examines the implications of a predominately rationalist and best-estimate probabilistic regulatory framework called safety goals-driven performance-based regulation. This framework relies on continuous assessment of performance of a set of time-dependent safety-critical systems, structures and components that assure attainment of a broad set of technology-neutral protective, mitigative, and preventive goals. Finally, the paper discusses the steps needed to develop a corresponding technology-neutral regulatory system from the proposed framework.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.19 no.2
• /
• pp.174-179
• /
• 2009

We consider the stabilization problem for a class of networked control systems with neutral type of time delays. The neutral type of time-delays occur in controller-to-actuator and sensor-to-controller. The Takagi-Sugeno (T-S) fuzzy model is employed to represent a nonlinear system with neutral type of time-delays. The stabilization via state-feedback is first addressed, and delay-range-dependent stabilization conditions are proposed in terms of linear matrix inequalities (LMIs). Finally, an application example will be given to show the merits and design a procedure of the proposed approach.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.17 no.4
• /
• pp.483-487
• /
• 2007

This paper is concerned with the observer design problem for linear neutral systems with time-varying delays. The problem addressed is that of designing a full-order observer that guarantees the exponential stability of the error system. An effective algebraic matrix equation approach is developed to solve this problem. In particular, both observer analysis and design problems are investigated. Sufficient conditions for a linear neutral system to be stable are first established. Furthermore, an illustrative example is used to demonstrate the validity of the proposed design procedure.

• Journal of the Ergonomics Society of Korea
• /
• v.29 no.5
• /
• pp.727-734
• /
• 2010

The objective of this study was to evaluate the resting postures of the fingers and wrist based on the biomechanical model in term of hand posture (neutral, pronation, and supination) and gender (male and female). The finger and wrist joint angles were measured with VICON motion system. The EMG system was used to examine the muscle activity in the resting condition. The participants consisted of twenty male and twenty female students. The angles of the fingers and wrist were analyzed by means of the coordinate system associated with the International Society of Biomechanics. Hand posture was significant for all the joints. The finger and wrist joint flexed in supination more than in neutral and pronation. The hand posture and gender were not significant for the results of muscle activity, but it had larger muscle activities in supination more than in neutral and pronation.

• Journal of Power Electronics
• /
• v.8 no.3
• /
• pp.259-267
• /
• 2008

Power quality improvement in a three-phase four-wire system is achieved using a new topology of DSTATCOM (distribution static compensator) consisting of a star/delta transformer with a tertiary winding and a three-leg VSC (voltage source converter). This new topology of DSTATCOM is proposed for power factor correction or voltage regulation along with harmonic elimination, load balancing and neutral current compensation. A tertiary winding is introduced in each phase for a delta connected secondary in addition to the star-star windings and this delta connected winding is responsible for neutral current compensation. The dynamic performance of the proposed DSTATCOM system is demonstrated using MATLAB with its Simulink and Power System Blockset (PSB) toolboxes under varying loads. The capacitor supported DC bus of the DSTATCOM is regulated to the reference voltage under varying loads.