• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.7
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• pp.340-347
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• 2001

In this Paper, we proposed a new voltage stability analysis algorithm. Using $ $ calculated by the optimal load How method(OLF), it rapidly and correctly calculates a PV curve with voltage collapse point in the stable region. OLF can calculates voltage collapse point as well as the operating point in the stable region. Specially, $ $ indicates the relative distance between voltage collapse point and the solution in the unstable region. In the study of a sample system, we verified the superiority of proposed algorithm.

• Journal of the Korean Society of Industry Convergence
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• v.13 no.4
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• pp.205-209
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• 2010

Even the domestically small-and medium-sized companies progressed development in the monitoring equipment of inspecting run out in steel wheel aiming to supply and generalize through developing the monitoring equipment for securing quality technology and enhancing quality-test level. Run-Out value in vehicle wheel was measured with Computer & Servo system by using Low-Point marking machine control system, which is this development product. Low-Point value was operated and calculated. It marked by revolving wheel as much as the demanded measurement value based on 1ST harmony curve. Thus, the shipment of inferior product, which occurs in the measurement by the existing worker, could be blocked in advance. In the existing case, 60 sec. was required for inspecting 1 product. However, it came to bring about a rise in production volume through shortening inspection time to 8 seconds and improving workers' operating environment.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.2
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• pp.129-139
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• 1987

In this paper the programming language for Hero-1 robot is developed using Apple II micro computer. The language is composed of main monitor mode, editing mode, execution mode, and debugging mode. The main monitor mode is a main flow of the whole language system and controls starting and terminating procedures of operating the controller, and monitors the others. The editing mode has capability to make a user's maniqulation program. Trajectory planning algorithms(point-to-point motion and linear approximate motion)have been realized in the robot language, and in the case of point-to-point motion, inverse kinematics have been solved for the desired point.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.134-136
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• 1993

This paper presents a novel and efficient method to calculate the critical point of voltage collapse. Conjugate gradient and modified Newton-Raphson methods are employed to calculate two pairs of multiple load flow solutions for two operating conditions, i.e., both +mode and -mode voltages for two loading conditions respectively. Then these four voltage magnitude-load data sets of the bus which is most susceptible to voltage collapse, are fitted to third order polynomial using Lagrangian interpolation in order to represent approximate nose curve (P-V curve). This nose curve locates first estimate of the critical point of voltage collapse. The procedure described above is repeated near the critical point and the new estimate will be very close to the critical point. The proposed method is tested for the eleven bus Klos-Kerner system, with good accuracy and fast computation time.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.6
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• pp.497-505
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• 2016

Operating wind turbine generators at maximum power point requires maximum power point tracking (MPPT) control methods. However, conventional methods cannot track the appropriate maximum power point in situations involving wind turbine systems based on a series operation strategy. These systems comprise one or more local maximum power points, and conventional methods can detect only one local maximum power point closed by a current operation point. This study proposes an advanced MPPT method for the series operation strategy of a small, grid-connected wind turbine system. In determining the appropriate maximum point, operations at certain local maximum power points are analyzed. The results show one appropriate point, which is tracked by the proposed MPPT method. The effectiveness of the proposed method is verified by the experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.5
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• pp.385-393
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• 2020

This study introduces an analysis and control method for the variation of neutral point current in a grid-tied three-level neutral point clamped (NPC) converter under various grid imbalance operating conditions. Various fault cases with unbalanced amplitude and phase are systematically categorized and described using a unified metric called the imbalance factor. The fundamental component of neutral point current is generated under grid imbalance cases. The pattern and behavior of this fundamental component of neutral point current highly depend on the imbalance factor regardless of the particular type of grid fault cases. The control scheme for regulating the negative sequential component of AC input current effectively reduces the size of the fundamental component of neutral point current under a wide range of grid imbalance cases. The control scheme will enable a grid-tied three-level NPC converter to operate reliably and stably under various types of grid faults.

• Journal of Korean Academy of Nursing Administration
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• v.14 no.3
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• pp.297-310
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• 2008

Purpose: The aim of this study was to investigate the attitude of job transfer and job satisfaction in operating rooms, and to use this data towards efficient human resource management. Method: One hundred and seven nurses in operating rooms in a general hospital in Seoul, Korea were surveyed using a questionnaire. Data was collected and analyzed using SPSS/PC program. Results: The attitude toward the job transfer was generally favorable with a mean of 3.32 out of a 5 point scale in rating the need for job transfer. Among the five domains of attitudes toward job transfer, individual development scored the highest(mean, 3.75). The mean score of job satisfaction in the study participants was rated in a 5 point scale with a mean of 3.12. Among the seven domains of job satisfaction, networking(3.37) scored the highest, followed by the perspective of professional position(3.32). Therefore, it can be said that mutual interaction and professional position are the most important factors for job satisfaction. The correlation between the attitude toward job transfer and job satisfaction showed a positive relationship with a coefficient of 0.210, implying that job satisfaction was higher when the attitude toward transfer was more favorable. Conclusion: From the attitude toward job transfer, individual development and professional improvement was favorable, implying the need for such program. Therefore, it is recommended that an official policy should be provided to achieve these goals in perioperative nursing.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.83-88
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• 2004

In this study, the flow and thermal performance of the heat sink and fan-sink were experimentally studied to predict the operating condition of the fan-sink. The experiments of the flow and thermal resistance of the heat sink with various inlet blockage, which were occurred by the shapes of the axial fans, were conducted for the proof of the effects of the inlet blockages. The greater the inlet blockage of the heat sink, the higher the pressure drop and lower the thermal resistance of the heat sink will be. The operating point of the fan-sink was predicted by the pressure drop curve with the inlet blockage, which was corresponded to the selected fan and the fan performance curve, and verified by the performance test of the fan-sink. The predicted operating point of the fan-sink had good agreement with the result of the performance test of the fan-sink within $0.7\%$ of the volume flow rates. Measured thermal resistance of the fan-sink was equivalent to that of the heat sink with the same inlet blockage of the fan-sink. It was shown that the heat transfer characteristics of the heat sink were influenced by the flow interaction between the selected fan and the heat sink. To improve the thermal resistance of the heat sink, it is necessary to consider appropriate flow patterns of the fan outlet entering into the heat sink.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.894-896
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• 1997

This paper presents the continuation power flow system that is under development. The continuation power flow system provides robust solutions of power flow equations at any operating point. The robust convergency enables one to find solutions even at the point where power flow jacobian becomes singular. Basic concept of an algorithm and its application to static voltage stability analysis are presented.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.315-317
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• 2007

This paper proposes a loss minimization algorithm for doubly-fed induction generator (DFIG) by controlling the stator reactive power. The proposed strategy directly controls the rotor current to achieve the operating point of minimum generator loss and maximum power point tracking. The maximum power is obtained by tracking the q-axis rotor current with generator speed variation and the minimum generator loss is achieved by controlling the d-axis rotor current. Experimental results are shown to verify the validity of the proposed scheme.