• Structural Engineering and Mechanics
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• v.18 no.2
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• pp.137-150
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• 2004

The optimization of active bars' placement and feedback gains of closed loop control system for random intelligent truss structures under non-stationary random excitation is presented. Firstly, the optimal mathematical model with the reliability constraints on the mean square value of structural dynamic displacement and stress response are built based on the maximization of dissipation energy due to control action. In which not only the randomness of the physics parameters of structural materials, geometric dimensions and structural damping are considered simultaneously, but also the applied force are considered as non-stationary random excitation. Then, the numerical characteristics of the stationary random responses of random intelligent structure are developed. Finally, the rationality and validity of the presented model are demonstrated by an engineering example and some useful conclusions are obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.117-122
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• 2018

A large-capacity three-phase system air conditioner recently includes an inverter circuit to reduce power consumption. The inverter circuit uses a DC voltage that comes from DC-link power capacitor with the function of rectifying, which means AC voltage to DC voltage using a diode. An electrolytic capacitor is generally used to satisfy the voltage ripple and current ripple conditions of a DC-link power capacitor used for rectifying. Reducing the capacitance of the capacitor decreases the size, weight, and cost of the circuit. This paper proposes an algorithm to reduce the input ripple current by combining the minimum point estimation phase locked loop (PLL) phase control and the average voltage d axis current control technique. When this algorithm was used, the input ripple current decreased by almost 90%. The current ripple of the DC-link capacitor decreased due to the decrease in input ripple current. The capacitor capacity can be reduced but the electrolytic capacitor has a heat generation problem and life-time limitations because of its large equivalent series resistance (ESR). This paper proposes a method to select a film capacitor considering the current ripple at DC-link stage instead of an electrolytic capacitor. The capacitance was selected considering the voltage limitation, RMS (Root Mean Square) current capacity, and RMS current frequency analysis. A $1680{\mu}F$ electrolytic capacitor can be reduced to a $20{\mu}F$ film capacitor, which has the benefit of size, weight and cost. These results were verified by motor operation.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.412-419
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• 1993

The transient responses of a linear system having undesired disturbances are dominantly governed by the system's left eigenstructure(eigenvalues/left eigenvectors). In control system design problem of altering the transient response of the system, both the controllability and the disturbance suppressibility, should be considered simultaneously to obtain a robust, effective controller. The controllability of the system may be degraded if the left eigenstructure is chosen to suppress the disturbance, or vice versa. In this paper, first, proposed are a modal disturbance suppressibility measure and an improved version of the modal controllability measure suggested by Hamdan and Nayfeh. Second, a simple and general left eigenstructure assignment scheme, considering both the proposed modal disturbance suppressibility measure and the improved version of modal controllability measure, is suggested. When the previous works are applied to assign the left eigenvectors may differ from the desired ones. But the proposed left eigenstructure assignment scheme makes it possible to achieve the desired colsed-loop eigenvalues exactly, provided the desired left eigenvectors reside in the achievable subspace. In case the desired left eigenvectors do not reside in the achievable subspace, the closed-loop eigenvalues are achieved exactly and the left eigenvectors are assigned to the best possible set of eigenvectors in the least square sense. Finally, a numerical example is included to confirm and demonstrate the usefulness of our propositions and to illustrate the proposed design scheme.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.6
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• pp.2853-2856
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• 2016

Background: Many studies have pointed to strategies to cope with patient anxiety in colposcopy. Evidence shows that patients experienced considerable distress with the large loop excision of transformation zone (LLETZ) procedure and suitable interventions should be introduced to reduce anxiety. This study aimed to investigate the effects of music therapy in patients undergoing LLETZ. Materials and Methods: A randomized controlled trial was conducted with patients undergoing LLETZ performed under local anesthesia in an out patient setting at Ramathibodi Hospital, Bangkok, Thailand, from February 2015 to January 2016. After informed consent and demographic data were obtained, we assessed the anxiety level using State Anxiety Inventory pre and post procedures. Music group patients listened to classical songs through headphones, while the control group received the standard care. Pain score was evaluated with a visual analog scale (VAS). Statistical analysis was conducted using Pearson Chi-square, Fisher's Exact test and T-Test and p-values less than 0.05 were considered statistically significant. Results: A total of 73 patients were enrolled and randomized, resulting in 36 women in the music group and 37 women in the non-music control group. The preoperative mean anxiety score was higher in the music group (46.8 VS 45.8 points). The postoperative mean anxiety scores in the music and the non-music groups were 38.7 and 41.3 points, respectively. VAS was lower in music group (2.55 VS 3.33). The percent change of anxiety was greater in the music group, although there was no significant difference between two groups. Conclusions: Music therapy did not significantly reduce anxiety in patients undergoing the LLETZ procedure. However, different interventions should be developed to ease the patients' apprehension during this procedure.

• Journal of IKEEE
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• v.26 no.1
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• pp.43-49
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• 2022

This paper compares the sensorless control performance according to the applied voltage waveform by injecting sinusoidal, triangular, and square waveform in the harmonic injection sensorless control method. By injecting various voltage shape waveform with a frequency of 1kHz, the error amount of the estimated angle for each waveform is compared and analyzed. For the experiment, the HILS(hardware in the loop simulation) system was used. The hardware is the control board, and the inverter and motor models implemented in Simulik are located in the real-time simulator. The control algorithm is implemented by the FPGA control board, which includes a PWM interrupt service routine with a frequency of 10 kHz, harmonic injection and position detection sensorless algorithm.

• Journal of Korean Dental Science
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• v.16 no.2
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• pp.149-155
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• 2023

Purpose: The purpose of this study was to evaluate whether the presence of a space maintainer affects the accuracy of an intraoral scanner. Materials and Methods: The maxillary primary first molar typodont tooth was removed from the primary dentition typodont model and a band and loop type space maintainer was delivered. After the model was connected to a dental phantom, intraoral scan was performed using TRIOS 4 (3Shape A/S, Copenhagen, Denmark). The scan was repeated with the same technique without the space maintainer. Each scan was performed 10 times. All scan files into a GOM inspect 2018 software and evaluated the accuracy. The accuracy was evaluated on trueness and precision, and calculated using the root mean square value. Result: When there was a space maintainer in the oral cavity, the trueness value was 0.10±0.02 mm and the precision value was 0.15±0.03 mm. In the absence of the space maintainer, the trueness value was 0.12±0.03 mm and the precision value was 0.16±0.04 mm. There were no significant differences depending on the presence of a space maintainer (P>0.05). Conclusion: Within the limits of this study, the accuracy of the intraoral scanner was not influenced by the presence of space maintainer.

• The Research Journal of the Costume Culture
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• v.21 no.6
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• pp.860-876
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• 2013

The pattern cases for Korean traditional socks are named "beoseonbongip" which means a pouch to keep patterns for making "beoseon". "Beoseon" is Korean traditional socks. This study is to identify characteristics of the pattern cases and to develop cultural products based on the unique characteristics of the pattern cases. One hundred fifty one photos of "beosonbongip" were collected and quantitatively and qualitatively analyzed. Seventy percent of them were made between Joseon Dynasty and 1960s. As a result, most of the collected pattern cases are rectangular and square shapes, red color, and silk fabrics, and sizes of them are from 9cm to 15cm. A few pattern cases with different sizes and colors were also observed. Most pattern cases were made by fixing two among four triangle pieces which made by folding four tips of a rectangular or square cloth and then puting a not or a loop on the remaining triangle pieces in order to open and close the pattern cases. In a small number of the pattern cases, three of the four pieces were fixed and a button, a bead, a broach, or two nots or two loops were put on the other piece for opening and closing. Products such as apparels, bags, pouches, frames, and key holders were made using "beoseonbongip" form and construction method. This shows that "beoseonbongip" is a useful motive for creative product development.

• Journal of Power Electronics
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• v.18 no.2
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• pp.558-572
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• 2018

In addition to its modular nature, a Hybrid Modular Multilevel Converter (HMMC) assembled from half-bridge and full-bridge sub-modules, is able to block DC faults with a minimum number of switching devices, which makes it attractive for high power applications. This paper introduces a control strategy based on the Root-Least Square (RLS) algorithm to estimate the capacitor voltages instead of using direct measurements. This action eliminates the need for voltage transducers in the HMMC sub-modules and the associated communication link with the central controller. In addition to capacitor voltage balancing and suppression of circulating currents, a fault tolerant control unit (FTCU) is integrated into the proposed strategy to modify the parameters of the HMMC controller. On advantage of the proposed FTCU is that it does not need extra components. Furthermore, a fault detection unit is adapted by utilizing a hybrid estimation scheme to detect sub-module faults. The behavior of the suggested technique is assessed using PSCAD offline simulations. In addition, it is validated using a real-time digital simulator connected to a real time controller under various normal and fault conditions. The proposed strategy shows robust performance in terms of accuracy and time response since it succeeds in stabilizing the HMMC under faults.

• Composites Research
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• v.24 no.1
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• pp.37-44
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• 2011

In this paper, Particle Swarm Optimization(PSO) is applied to the design of the Frequency Selective Surface(FSS) and residual stresses of hybrid radome is predicted. An equivalent circuit model with Square Loops arrays was derived and then PSO was applied for acquiring the optimized geometrical parameters with proper resonant frequency. Residual stresses occur in the FSS embedded composite structures after cocuring and have a great influence on the strength of the FSS embedded composite structures. They also effect transmission quality because of delamination. Therefore, the thermal residual stresses of FSS embedded composite structures were analyzed using finite element analysis with considering the effects of FSS pattern, and composite stacking sequence.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.6
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• pp.55-65
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• 1998

In industrial fields, RTP(rapid thermal processing) system is widely used for improving the oxidation and the annealing in semiconductor manufacturing process. The main control factors are temperature control of wafer and uniformity in the wafer. In this paper, we propose an $H^{\infty}$ controller design of RTP system satisfying robust stability and performance using weighted mixed sensitivity miniimization and loop shaping technique. And we need reduction technique because of the difficulty of implementation with the obtained high order controller for original model and reduced models, namely, Hankel, square-root balanced, and Schur balanced methods. An example is proposed to show the validity of the proposed method.