• Journal of Power Electronics
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• v.9 no.5
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• pp.691-699
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• 2009

This paper presents the analysis of series active power filter for reactive power compensation, load balancing, harmonic elimination, and neutral current eradication in three-phase four-wire power systems. Generally, the three-phase four-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. In such systems, the third harmonic and its 3rd harmonics are termed as triple and zero sequence components that do not cancel each other in the system neutral. Consequently, the triple harmonics add together creating a primary source of excessive neutral current. Regarding this concern, this paper presents a new control algorithm for a series hybrid active system, whereas the control approach it adopts directly influence its compensation characteristics. Hence, the advantage of this control algorithm is the direct extraction of compensation voltage reference without phase transformations and multiplying harmonic current value by gain and the required rating of the series active filter is much smaller than that of a conventional shunt active power filter. In order to show the effectiveness of the proposed control algorithm, experiments have been carried out.

• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.67-75
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• 2009

The growing need for the mobility supportable networks induces the IP-based mobility management protocols. Though HMIPv6 which manages the micro-mobility of mobile nodes using MAPs suggests an effective method for mobility-support for mobile nodes within the domain that is managed by MAP. There is a problem that traffic may be concentrated on MAPs. In this paper, therefore, we proposed a method that can effectively distribute the traffic which is concentrated on a MAP under phased Mobile IPv6. In our proposed method, two or more MAPs are required and classified as an 'Active MAP' or a 'Passive MAP'. In addition, we defined the state of transition events between Active MAP and Passive MAP and the operations among MAPs for load distribution when an overload condition is occurred at some MAPs by traffic congestion. We compared the performance of our proposed method with its phased Mobile IPv6 to prove the propriety of our proposed method. As a result, we showed that our proposed method can provide an enhanced performance by about 12 percentages in view of packet throughput at the node.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.21-36
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• 1999

Recently resistivity survey is widely used for site investigations in the field of civil engineering. Since such application area requires accurate interpretation tools especially in the area of complicated geology and rough terrain topography, we developed a three-dimensional (3-D) resistivity inversion code, which can reconstruct real earth structures. Furthermore, the inversion code gives resolution-enhanced images by applying the ACB(Active Constraint Balancing) method. With the help of this inversion code, 3-D resistivity survey is now used as new techniques for site investigations in civil engineering problem. By imaging the 3-D resistivity distribution, we could get useful informations such as depth distribution of basement rock, distribution of weak zone, fractures and cavities which is crucial to civil engineers.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1625-1636
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• 2017

A power electronic transformer (PET) based on the cascaded H-bridge (CHB) and the isolated bidirectional DC/DC converter (IBDC) is capable of accommodating a large scale battery energy storage system (BESS) in the medium-voltage grid, and is referred to as a power electronic transformer based battery energy storage system (PET-BESS). This paper investigates the PET-BESS and proposes a coordinative control strategy for it. In the proposed method, the CHB controls the power flow and the battery state-of-charge (SOC) balancing, while the IBDC maintains the dc-link voltages with feedforward implementation of the power reference and the switch status of the CHB. State-feedback and linear quadratic Riccati (LQR) methods have been adopted in the CHB to control the grid current, active power and reactive power. A hybrid PWM modulating method is utilized to achieve SOC balancing, where battery SOC sorting is involved. The feedforward path of the power reference and the CHB switch status substantially reduces the dc-link voltage fluctuations under dynamic power variations. The effectiveness of the proposed control has been verified both by simulation and experimental results. The performance of the PET-BESS under bidirectional power flow has been improved, and the battery SOC values have been adjusted to converge.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.4
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• pp.217-222
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• 2001

We propose a new two-degree of freedom parallel mechanism for a haptic device and will refer to the mechanism as the SenSation. The SenSation is designed in order to improve the kinematic performanced and to achieve static balance. We use the panto graph mechanisms in order to change the location of active joints, which leads to transform a direct kinematic singularity into a nonsingularity. The direct kinematic singular configurations of the SenSation occur near the workspace boundary. Using the property that position vector of rigid body rotating about a fixed point is normal to the velocity vector, Jacobian matrix is derived. Using the vector method, two different types of singularities of the SenSation can be identified and we discuss the physical significance of each of the three types of singularities. We will compare the kinematic performances(force manipulability ellipsoid, kinematic isotropy) of the SenSation with those of five-var parallel mechanism. By specifying that the potential energy be fixed, the conditions for the static balancing of the SenSation is derived. The static balancing is accomplished by changing the center of mass of the links.

• Journal of TMJ Balancing Medicine
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• v.12 no.1
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• pp.7-14
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• 2022

Objectives: Dementia is a disease in which a person maintains a normal intellectual level during the growth period, but has acquired cognitive impairment and personality change. In this study, we tried to check whether the network pharmacology analysis method is useful in the search for herbal medicine resources for the treatment of dementia. Methods: The Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) database is a database frequently used in Chinese medicine research. We used the TCMSP to identify herbal medicines and their molecular targets that can be used for dementia by using network pharmacology research methods. Results: It was possible to select 28 types of components that are expected to be active by applying them to the living body, and 75 types of targets that these components act on were secured. In addition, 16 kinds of drugs were identified by checking the drugs containing 28 kinds of ingredients, and it was found that Radix Salviae contained 2 kinds of the selected 28 kinds of ingredients. Conclusions: Through this study, we were able to identify ingredients, drugs, and targets that can be used for basic and clinical research on dementia.

• Journal of Biomedical Engineering Research
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• v.19 no.4
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• pp.385-391
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• 1998

A new balancing method of atrial pressures balancing for the moving actuator total artificial heart(TAH) without an extra compliance chamber was developed. The asymmetric operation of the pendulous moving actuator have made it possible to compensate the left and right pump output difference by utilizing the interventricular air space as an internal compliance chamber in a pump housing. Furthermore, the balancing performance between left and right pump outputs is increased through the improvement of the flexibility of part of the polyurethane housing. However, the increase of the flexibility of the pump housing causes a little loss of the cardiac output due to the reduction of active filling property. In this paper., a good condition between the balance and pump output performance is evaluated by adjusting the air volume in the interventricular space through a series of in vitro experiments. This new pump was implanted in a sheep weighting 63kg, and it survived for 3 days and the average cardiac output during postoperative days was about 4.2 L/mim with the atrial pressures under 15 mmHg.

• Geophysics and Geophysical Exploration
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• v.2 no.4
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• pp.191-201
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• 1999

The interpretation of resistivity data has, so far, mainly been made under the assumption that the earth is of relatively simple structure and then using one or two-dimensional inversion scheme. Since real earth structure and topography are fully three-dimensional and very complicated In nature, however, such assumptions often lead to misinterpretation of the earth structures. In such situations, three-dimensional inversion is probably the only way to get correct image of the earth. In this study, we have developed a three-dimensional inversion code using the finite element solution for the forward problem. The forward modeling algorithm simulates the real field situation with irregular topography. The inverse problem is solved iteratively using the least-squares method with smoothness constraint. Our inversion scheme employs ACB (Active Constraint Balancing) to enhance the resolving power of the inversion. Including Irregular surface topography in the inversion, we can accurately define the earth structures without artifact in the numerical tests. We could get reasonable image of earth structure by Inverting the real field data sets taken over highway bridge construction site.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.11
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• pp.216-218
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• 1995

A new atrial pressures balancing method for moving actuator total artificial heart(TAH) without an extra compliance chamber is developed. The structural characteristics of the pendulous moving actuator have made it possible to compensate the left and right pump output difference by utilizing the interventricular air space as an internal compliance chamber in a pump housing. Furthermore, the balancing performance is increased through the improvement of the flexibility of part of the polyurathane housing. However, the increase of the flexibility of the housing causes a little loss of the cardiac output due to the reduction of active filling performance. In this paper, a good condition between the balance and pump output performance is evaluated by adjusting the air volume in the interventricular space through a series of in vitro experiment.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.2
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• pp.91-99
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• 2023

Participation in power trading using surplus power is considered a business model active in the domestic energy trade market, but it is limited only if the legal requirements according to the type, capacity, and use of the facilities to be applied for are satisfied. The hydrogen residential demonstration model presented in this paper includes solar power, energy storage system (ESS), fuel cell, and water electrolysis facilities in electrical facilities for private use with low-voltage power receiving system. The concept of operations strategy for this model focuses on securing the energy self-sufficiency ratio of the entire system, securing economic feasibility through the optimal operation module installed in the energy management system (EMS), and securing the stability of the internal power balancing issue during the stand-alone mode. An electric facility configuration method of a hydrogen residential complex demonstrated to achieve this operational goal has a structure in which individual energy sources are electrically connected to the main bus, and ESS is also directly connected to the main bus instead of a renewable connection type to perform charging/discharging operation for energy balancing management in the complex. If surplus power exists after scheduling, participation in power trading through reverse transmission parallel operation can be considered to solve the energy balancing problem and ensure profitability. Consequentially, this paper reviews the legal regulations on participation in electric power trading using surplus power from hydrogen residential models that can produce and consume power, gas, and thermal energy including hybrid distributed power sources, and suggests action plans.