• Journal of Power Electronics
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• v.19 no.3
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• pp.727-743
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• 2019

This paper presents a pulse-width modulation strategy to eliminate the common mode voltage (CMV) with reduced CMV spikes in multilevel inverters since a high CMV magnitude and its fast variations dv/dt result in bearing failure of motors, overvoltage at motor terminals, and electromagnetic interference (EMI). The proposed method only utilizes the zero CMV states in a space vector diagram and it is implemented by a carrier-based pulse-width modulation (CBPWM) method. This method is generalized for odd number levels of inverters including neutral-point-clamped (NPC) and cascaded H-bridge inverters. Then it is extended to the over-modulation mode. The over-modulation mode is implemented by using the two-limit trajectory principle to maintain linear control and to avoid look-up tables. Even though the CMV is eliminated, CMV spikes that can cause EMI and bearing current problems still exist due to the deadtime effect. As a result, the deadtime effect is analyzed. By taking the deadtime effect into consideration, the proposed method is capable of reducing CMV spikes. Simulation and experimental results verify the effectiveness of the proposed strategy.

• International Journal of Highway Engineering
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• v.19 no.5
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• pp.33-42
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• 2017

PURPOSES : The purpose of this study is to suggest the construction and quality control method for the re-repair of a deteriorated partial depth repair for sections of Portland cement concrete pavement. METHODS : An experimental construction was conducted to extend the repair width for removing an existing repair section. A removal method was used to ensure early performance for a deteriorated partial depth repair section. Bond strength and split tensile strength were measured at the near vertical interface layer between the existing pavement and repair material. The area was analyzed for various conditions such as the extended repair area and the removing method of the existing repair section. RESULTS : As a result of analysis of bond strength and split tensile strength, the bonding performance of a milling removed section was improved over a cutting and hand breaker removed section. The bond strength was analyzed to increase slightly as the extended repair width for removing the existing repair section increased. The split tensile strength did not show a clear relationship to an increased extended repair width of an existing removed repair section. CONCLUSIONS : The milling removal method should be applied in the removal of existing deteriorated partial depth repair sections. The extended repair width for a re-repair section should be wider than the existing partial depth repair with at least a 75-mm length and width for the bond strength and the split tensile strength.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.361-362
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• 2006

This paper presents the robust design of gripper part for a high-speed LCD (Liquid Crystal Display) transfer system. In this paper, the 1st DOE (Design of Experiment) is conducted to find out main-effect factors fur the design of gripper part. Thirty-six experiments are performed using $ANSYS^{(R)}$ and their results are statistically analyzed using $MINITAB^{(R)}$, which shows that the factors, i.e., First-width, Second-width, Rec-width, and thickness of gripper part, are more important than other factors. The main effect plots shows that the maximum deflection and mass of gripper part are minimized by increasing First-width, Second-width, Rec-width and thickness. The 2nd DOE is conducted to obtain RSM (Response Surface Method) equation. The CCD (Central Composite Design) technique with four factors is used. Optimum design is conducted using the RSM equation. Genetic algorithm is used for optimal design. Six sigma robust design is conducted to find out a guideline for control range of design parameter. To obtain six sigma level reliability, the standard deviations of design parameters are shown to be controlled within 5% of average design value.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.4
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• pp.81-90
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• 2022

In this study, for one-way concrete slabs, the flexural strength, deflection, and crack width according to the amount of reinforcing bars were compared for the cases of using steel reinforcing bars and CFRP reinforcing bars. Critical performance dominating the flexural design was investigated and how to design the CFRP-reinforced concrete slab with efficiency was also discussed. It was found that CFRP-reinforced concrete slabs could achieve greater design flexural strength with the same amount of reinforcing bars compared to those using steel rebar, while deflection and crack width were relatively much larger. In concrete slabs using CFRP reinforcing bars, it was confirmed that the maximum crack width acts as a dominant factor in the design. For more efficient flexural design, it is necessary to mitigate the allowable crack width to 0.7 mm and to apply smaller diameter reinforcing bars to control the crack width.

• Journal of Korean Neurosurgical Society
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• v.61 no.2
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• pp.243-250
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• 2018

Objective : To compare the morphometry of subaxial cervical spine between cerebral palsy (CP) and normal control. Methods : We retrospectively analyzed 72 patients with CP, as well as 72 patients from normal population. The two groups were matched for age, sex, and body mass index. Pedicle, lateral mass (LM), and vertebral foramen were evaluated using computed tomography (CT) imaging. Pedicle diameter, LM height, thickness, width and vertebral foramen asymmetry (VFA) were measured and compared between the two groups. Cervical dynamic motion, disc and facet joint degeneration were investigated. Additionally, we compared the morphology of LM between convex side and concave side with cervical scoliotic CP patients. Results : LM height was smaller in CP group. LM thickness and width were larger in CP group at mid-cervical level. In 40 CP patients with cervical scoliosis, there were no height and width differences between convex and concave side. Pedicle outer diameter was not statistically different between two groups. Pedicle inner diameter was significantly smaller in CP group. Pedicle sclerosis was more frequent in CP patients. VFA was larger in CP group at C3, C4, and C5. Disc/facet degeneration grade was higher in the CP group. Cervical motion of CP group was smaller than those of the control group. Conclusion : LM morphology of CP patients was different from normal population. Sclerotic pedicles and vertebral foramen asymmetry were more commonly identified in CP patients. CP patients were more likely to demonstrate progressive disc/facet degeneration. This data may provide useful information on cervical posterior instrumentation in CP patients.

• Journal of Periodontal and Implant Science
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• v.33 no.3
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• pp.533-542
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• 2003

The purpose of this study is to evaluate histologic result of bone substituting material on defects followed tooth extraction. We compare the histologic findings control, DFDBA, Bio-Oss(R), and $Regenafil^{TM}$, Briefly, mandibular premolar teeth were extracted available for bone filling. All alveolar sites were checked after extraction and thoroughly debrided with a dental curet to remove the periodontal ligament. Extraction sites were prepared dehiscence on buccal side 7mm height from alveolar crest. The graft materials were filled into the extraction socket and dehiscenc defects. The animals were sacrificed 12 weeks after implantation. Both treated and control mandibular sites were histologically evaluated with light microscopy. Histologic observation at 12 weeks revealed that control and experimental sites were healed uneventfully and directly apposed to new bone without any adverse tissue reaction. DFDBA and Bio-Ossn(R)sites maintain width of alveolar crest but were not fully resorbed. $Regenafil^{TM}$ sites also maintain width and particles were resorbed more than other graft materials. From this results, it was suggested that $Regenafil^{TM}$ is promising boen substituting materials maintaining the width of alveolar crest and height follewed tooth extraction.

• Archives of Plastic Surgery
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• v.42 no.2
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• pp.207-213
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• 2015

Background Pincer nail deformity is a transverse overcurvature of the nail. This study aimed to define the anatomical characteristics of pincer nail deformity and to evaluate the surgical outcomes. Methods A retrospective review was conducted on 20 cases of pincer nail deformity of the great toe. Thirty subjects without pincer nail deformity or history of trauma of the feet were selected as the control group. Width and height indices were calculated, and interphalangeal angles and base widths of the distal phalanx were measured with radiography. We chose the surgical treatment methods considering perfusion-related factors such as age, diabetes mellitus, kidney disease, and peripheral vascular disease. The zigzag nail bed flap method (n=9) and the inverted T incision method (n=11) were used to repair deformities. The outcomes were evaluated 6 months after surgery. Results The interphalangeal angle was significantly greater in the preoperative patient group ($14.0^{\circ}{\pm}3.6^{\circ}$) than in the control group ($7.9^{\circ}{\pm}3.0^{\circ}$) (P<0.05). The postoperative width and height indices were very close to the measurements in the control group, and most patients were satisfied with the outcomes. Conclusions We believe that the width and height indices are useful for evaluating the deformity and outcomes of surgical treatments. We used two different surgical methods for the two patient groups with respect to the perfusion-related factors and found that the outcomes were all satisfactory. Consequently, we recommend taking into consideration the circulatory condition of the foot when deciding upon the surgical method for pincer nail deformity.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.1
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• pp.101-109
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• 2016

This is the fundamental research on restoring damaged vegetation areas in the vicinity of DMZ using local native plant species. This research is aimed at identifying effective plant growth regulators (PGR) for seed germination and seedling growth of mountain mulberry, and developing effective methods for managing its germination and growth. Mountain mulberry seeds were collected from the regions in the DMZ vicinity, and tests with seven treatments using four PGRs including $GA_3$, kinetin, ABA and NAA, were conducted. The germination rate was calculated in two different ways of both in a growth chamber and in a greenhouse after seven days observation, and the growth characters such as leaf width/length, seedling width/length and fresh/dry weight, have been surveyed in a greenhouse for three months. Although in the growth chamber the highest germination rate was shown at a group with the kinetin treatment, it was not significantly different to that of the control group. Groups with ABA or NAA presented relatively low germination rates. As for the greenhouse test, the germination rates of all groups ranged 20~30% without significant difference each other, the reason of which might be due to low absorption by the effect of a soil drench method used in this study. The entire growth characters with the treatments of $2.15mg{\cdot}L^{-1}$ of kinetin and $10mg{\cdot}L^{-1}$ of $GA_3$ were significantly different to the control. NAA treatment only showed better growth of seedling width compared to the control. Consequently, the most effective PGRs for the germination and growth of mountain mulberry near the DMZ was kinetin. Further research on examining the most effective concentration of them was needed.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.1
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• pp.43-51
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• 2010

This paper proposes an analysis of voltage delay and compensation for current control in H-Bridge Multi-Level (HBML) inverters for a medium voltage motor drive with vector control. It is shown that the expansion and modularization capability of the HBML inverter is improved in case of using Phase-Shifted Pulse Width Modulation (PSPWM) since individual inverter modules operate more independently. But, the PSPWM of HBML has a phase difference between reference voltage and real voltage, which can cause instability in the current regulator at high speed where the ratio of the sampling frequency to the output frequency is insufficient. This instability of the current regulator is removed by adding a proposed method which compensate a phase difference between reference voltage and real voltage. The proposed method is suitable for HBML inverter controlled by PSPWM with low switching frequency and high speed motor drive. The validity of the proposed method is verified experimentally on 6,600[V] 1,400[kW] induction motor fed by an 13-level HBML inverter.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.6
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• pp.37-42
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• 2004

It is necessary for what just keep a living body balance be devoted to it being varied with acidity serious trouble, and constitution of a study person about the density (ph) change that an alkaline ion necessary for a living body is numerical to supply a human body with number alkali by PWM voltage control. Works in the water which included the calcium (Ca), kalium (K), magnesium (Mg), natrium (Na) back who is helpful for a human body, and there is Alkaline. It is done this alkaline electrolysis to ask in order to create a number, and minerals are gathered through isolated layer (isolated special layer) to a - electrode direction, and is created. of course, prominent derelicts gather, and the acidity capital is happened, and -ion of a chlorine (Cl), phosphorus(P), sulfur (S) back is usable unfavorably in water of different use to a + electrode direction. Microprocessor was used with a - pole and a + pole with a PWM(pulse width modulation) voltage in this electrolysis process, and four kinds of PWM voltages were implemented, and a voltage every ph density change tried to be considered. It is expected by getting exactly if number alkaline ion of ph density value necessary is done with setting value if PWM control is used thus.