• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.369-372
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• 2002

This paper presents a family of continuous conduction mode with constant-switching pulse width modulator controllers. Unified implementation of quasi steady state approach for various DC-DC converters topoiogies is illustrated. The property and control low for quasi-state approach will be discussed in this paper. The different procedures will be discussed in details with different results for five commonly used DC-DC converters. Both trailing and leading edge pulse width modulation are used. Leading edge modulation can some times lead to simpler control circuitry as will be demonstrated in some circuits. These controllers do not require the multiplier in the voltage feed back loop, error amplifier in the current loop and rectified line voltage sensor, which are needed by traditional control methods. Controller examples and design arc analyzed.

• Journal of IKEEE
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• v.19 no.1
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• pp.73-79
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• 2015

In this paper, maximum boost space vector pulse-width modulation(MBSVPWM) strategy of Z-Source Inverters(ZSIs) is proposed. Conventional space vector pulse-width modulation(SVPWM) method of Voltage Source Inverters(VSIs) is modified to produce unique PWM patterns that realize the maximum boost control of ZSIs. This proposed method minimizes the switching power losses of ZSIs by reducing the numbers of the shoot-through states. Moreover, some switches keep ON state and the switching transitions do not occur during the specific sectors. An experimental system has been built and tested to verify the effectiveness of the proposed strategy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.4
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• pp.370-378
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• 1987

Wave reflection control functions of mound for the foundation of composite and perforated break-waters were investigated through the theoretical considerations. The theory developed is based on a simple summation of components of reflected waves. The applicability of the theory is assured by the comparative studies of the theoretical calculation and experimental data on the sea surface elevation in front of a breakwater. It is found that the reflection is mainly controlled by depth and width of the mound. In the design of composite type perforated breakwaters, the width of perforated part of the upright section can be decreased to less than half of the conventional design width for the same reflection by using the reflection control function of mound part and the reflection can be reduced until less than $30\%$ of that in the composite breakwaters. Using the results, a design method of mounds is proposed, by which the reduction of wave reflection is assured under the given wave conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.499-503
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• 1994

The feedback control systems of welding process using visual information can improve weld qualities. However, it is very difficult to get the visual information of weld pool since welding are is much stronger than light from weld pool. To explore the possibility of extending the capability of automatic welding machines a study of a closed loop controlled welding system consisted of a GTA welding machine, a vision system, a stepping motor system and a digital computer was undertaken. Particularly, in this system, a CCD camera with 850nm long pass filter was focused on the weld pool to give a weld pool image. Subsequently, image analysis technique has been developed to measure a weld pool width. Using this weld pool width measurement, a colsed loop control system adjusted welding speed to maintain constant weld pool width.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.20.1-20.7
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• 2019

Background: The purpose of this study was to evaluate the effects of botulinum toxin A (BTX) injection into the anterior belly of the digastric muscle on a growing rat. Methods: Ten Sprague Dawley rats were used in this study. When the rats were 13 days old, 0.5 units of BTX was injected into the anterior belly of the digastric muscle for the experimental group (n = 5). For the control, the same volume of normal saline was injected (n = 5). The rats were sacrificed at 60 days old, and the skulls were harvested for micro-computed tomography (μCT) analysis. Results: In anthropometric analysis, the zygomatic arch and mandibular bi-condylar width were significantly lower in the experimental group than those in the control group (P = 0.025 and 0.027, respectively). The maxillary point width was significantly higher in the experimental group than that in the control group (P = 0.020). Conclusion: BTX injection into the anterior belly of the digastric muscle had effects on the maxillofacial bony width in growing rats.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.9
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• pp.2760-2769
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• 1996

The feedback control systems of welding process using visual information can improve weld qualities. However, it is very difficult to get the visual information of weld pool since the light intensity of welding arc is much stronger than that of the weld pool. To explore the possibility of extending the capability of automatic welding machines, a study of a closed loop controlled welding system consisted of a GTA welding machine, a vision system, a stepping motor system and a digital computer was undertaken. Particularly, in this system, a CCD camera with a long wavelength pass filter was used to get a better weld pool image. Subsequently, an image analysis technique has been developed to measure the weld pool width. Using this weld pool width measurement, a colsed loop control system adjusted welding speed to maintain a constant weld pool width.

• 전기의세계
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• v.31 no.1
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• pp.50-58
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• 1982

As a method for improving the power factor and the waveform of ac line current drawn by ac to dc converters, converters of pulse-width control type with forced commutation circuits have been developed in recent years. However, these converters have rather complex commutation circuits which contain auxiliary thyristors in addition to the main thyristors, and their performance is not satisfactory. This paper proposes a new pulse-width controlled ac to dc converter, and analyses its commutation mechanism and its input and output characteristics. The proposed converter circuit consists of a usual thyristor bridge circuit with series diodes to which reactors and diodes are added. This circuit dose not contain auxiliary thyristors, and in this sense it is simpler than the previous converter circuits of pulse-width control type. Since the main thyristors of the converter can be forcedly turned off several times in a half cycle of source voltage, a pulse-width modulation control is possible in order to improve the current waveform as well as the power factor on ac line side. As to dc output side it is shown that the adjustable range of output voltage is wide and the voltage regulation is good due to a rapid reversal of voltage across the commutating capacitors by LC resonance during commutation period. It is also shown that the regenerative operation of the converter is possible.

• Journal of Power Electronics
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• v.18 no.1
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• pp.34-44
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• 2018

This paper presents a pulse-width adjustment (PWA) strategy for a novel bidirectional DC-DC boost converter to improve the performance of the dynamic inductor current response. This novel converter consists of three main components: a full-bridge converter (FBC), a high-frequency isolated transformer with large leakage inductance, and a three-level voltage-doubler rectifier (VDR). A number of scholars have analyzed the principles, such as the soft-switching performance and high-efficiency characteristic, of this converter based on pulse-width modulation plus phase-shift (PPS) control. It turns out that this converter is suitable for energy storage applications and exhibits good performance. However, the dynamic inductor current response processes of control variable adjustment is not analyzed in this converter. In fact, dc component may occur in the inductor current during its dynamic response process, which can influence the stability and reliability of the converter system. The dynamic responses under different operating modes of a conventional feedforward control are discussed in this paper. And a PWA strategy is proposed to enhance the dynamic inductor current response performance of the converter. This paper gives a detailed design and implementation of the PWA strategy. The proposed strategy is verified through a series of simulation and experimental results.

• Structural Engineering and Mechanics
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• v.82 no.6
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• pp.757-770
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• 2022

For the design of flexural and shear crack control for reinforced concrete (RC) beams related to serviceability and reparability ensuring, eight simply-supported normal-strength reinforced concrete (NSRC) beam specimens are tested and the existing high-strength reinforced concrete (HSRC) experimental data are included in the investigation of this work. According to the investigation results of flexural and shear cracks, this works modifies the existing design formulas to determine the spacing of the tensile reinforcement for the flexural crack control of a HSRC/NSRC beam design. Additionally, for a specified shear crack width of 0.4 mm, the allowable stresses of the shear reinforcement are also identified. For the serviceability and reparability ensuring of HSRC/NSRC beams, this works proposes the relationship curves between the maximum flexural width and allowable stress of the tensile reinforcement, and the relationship curves between the shear crack width and allowable shear force that can be used to do the crack width control directly.

• Journal of the Korea Fashion and Costume Design Association
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• v.14 no.4
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• pp.127-137
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• 2012

The purpose of this study is to recognize the differences of visual evaluation by variations in width of hem line and waistline position of the flare pants. The stimuli are 9 samples: One control group, 3 variations of the width of hem line and 3 variations of the waistline position. The data has been obtained from 44 fashion students. The data has been analyzed by Factor Analysis, Anova, Scheffe's Test and the MCA method. The results of the study are as follows: The visual evaluation by the width of hem line and waistline position of flare pants are composed of 5 factors : physical characteristics, elegance, originality, comfort, and stiffness. Among these factors, the physical characteristic is evaluated to be the most important factor. As a v isual evaluation result o f changes in the width o f hern l ine, 8 4 cm in width (the narrowest width) was highly evaluated in physical characteristics, elegance, and originality factors. For the result of changes in the waistline position, high-waisted flare pants were highly effective in physical characteristics, and also evaluated well in elegance, originality and stiffness factors. The flare pants did not show any interaction between the width of hem line and waistline position. The waistline position had more influence on visual evaluation in physical characteristics, originality and comfort factors while elegance and stiffness factors were affected by the width of hem line.