• Smart Structures and Systems
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• 제2권1호
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• pp.61-80
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• 2006

The concept of structural vibration control is to absorb vibration energy of the structure by introducing auxiliary devices. Various types of structural vibration control theories and devices have been recently developed and introduced into mechanical systems. One of such devices is damper employing controllable fluids such as ElectroRheological (ER) or MagnetoRheological (MR) fluids. MagnetoRheological (MR) materials are suspensions of fine magnetizable ferromagnetic particles in a non-magnetic medium exhibiting controllable rheological behaviour in the presence of an applied magnetic field. This paper presents the modelling of an MRfluid damper. The damper model is developed based on Newtonian shear flow and Bingham plastic shear flow models. The geometric parameters are varied to get the optimised damper characteristics. The numerical analysis is carried out to estimate the damping coefficient and damping force. The analytical results are compared with the experimental results. The results confirm that MR damper is one of the most promising new semi-active devices for structural vibration control.

• 대한물리의학회지
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• 제18권3호
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• pp.73-84
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• 2023

PURPOSE: This study analyzed the impact of AI and biosensors on physical therapy, identifying the stage of customized technology development and future prospects. AI and biosensors improve the efficiency, establish customized treatment plans, and expand patient treatment opportunities. The study employed a literature review by searching databases and collecting research. METHODS: This study searched various databases related to the topic, collected existing research, papers, and reports, evaluated the literature, and summarize the results. RESULTS: Exercise therapy utilizing artificial intelligence can provide personalized and optimal exercise plans while monitoring rehabilitation progress. In addition, biosensors such as EMG sensors and accelerometers can monitor the individual progress in physical therapy, particularly in stroke patients, which can help improve physical therapy strategy and promote patient recovery. CONCLUSION: This study suggested that artificial intelligence can be applied in many areas of physical therapy, such as exercise therapy, customized treatment plans, rehabilitation and management, pain management, neuro rehabilitation, and auxiliary devices. Using AI technology, it is possible to analyze and improve exercise and posture, retrain the central nervous system, establish customized treatment plans for individual patients, predict and compare patient progress before and after treatment, and provide customized pain analysis and treatment methods. In addition, AI can provide neuro rehabilitation programs and customized auxiliary devices.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.535-538
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• 1994

In this paper, an isolated ZVS-PWM boost converter is proposed for single stage line conversion. For power factor correction, we used the half bridge topology at the primary side of isolation transformer permitting switching devices to operate under ZVS by using circuit parastics and operating at a fixed duty ratio near 50%. Thus the relatively continuous input current distortion and small size input filter are also achievable. The ZVS-PWM boost operation of the proposed converter can be achieved by using the boost inductor $L_f$, main switch $Q_3$, and simple auxiliary circuit at the secondary side of isolation transformer. The secondary side circuit differ from a conventional PWM boost converter by introduction a simple auxiliary circuit. The auxiliary circuit is actived only during a short switching transition time to create the ZVS condition for the main switch as that of the ZVT-PWM boost converter. With a single stage, it is possible to achieve a sinusoidal line current at unity power factor as well as the isolated 48V DC output. Comparing to the two stage schemes, overall effiency of the proposed converter is highly improved due to the effective ZVS of all devices as well as single stage power conversion. Thus, it can be operated at high switching frequency allowing use of small size input filter. Minimum voltage and current stress make it high power application possible.

• 치위생과학회지
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• 제16권6호
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• pp.442-448
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• 2016

본 연구는 구강보건교육에 대한 경험, 계속구강건강관리 프로그램 필요성과 참여 의향을 알아보기 위해 2016년 6월 1일부터 8월 3일까지 대전광역시에서 거주하며 치과에서 1회 이상 진료를 받은 경험이 있는 만 19세 이상 성인 중 303명을 편의추출하여 설문조사하였다. 그 결과, 3회 이상 이를 닦는 대상자는 72.6%였으며 구강보조용품을 사용하는 대상자는 55.8%였고 칫솔질 시간이 2분 이상인 대상자는 55.8%였다. 치면착색제 경험은 1일 칫솔질 횟수에 영향을 미쳤으며 치면착색제 경험, 칫솔질 교육, 구강보조용품 사용 교육, 치주질환 예방 교육은 구강보조용품 사용과 1회 칫솔질 시간에 영향을 미쳤다. 계속구강건강관리 프로그램이 필요하다고 생각하는 대상자는 93.1%였으며 계속구강건강관리 프로그램 참여의향은 68.0%였다. 계속구강건강관리 프로그램 1회 참여비용은 1만원 이상 2만원 미만이 70.3%로 가장 많았으며 관리주기는 6개월이 42.6%로 가장 많았다. 계속구강건강관리 프로그램 요구도는 구강세균검사 74.3%, 칫솔질 교육 71.6%, 구취검사 69.3%, 구강보조용품 교육 46.9%, 치면세균막검사 42.9%, 타액검사 37.6% 순이었다. 계속구강건강관리 프로그램 필요성 인지에 영향을 미치는 요인은 고졸 이하에 비해 대졸 이상 4.514배, 구강보조용품을 사용하지 않은 군에 비해 사용하는 군이 2.878배, 칫솔질 시간이 2분 미만군에 비해 2분 이상군이 3.138배 필요성 인지가 높았다. 계속구강건강관리 프로그램 참여 의향에 영향을 미치는 요인은 치주질환 예방 교육 경험이 없는 군에 비해 예방교육 경험이 있는 군이 1.915배 높았으며 구강보조용품 사용을 하지 않는 군에 비해 사용하는 군이 2.065배 높았다. 따라서, 치과에 내원하는 환자에게 지속적으로 구강보건교육을 하는 것이 계속구강건강관리 프로그램에 참여율을 높일 수 있다고 생각되었다. 또한, 구강세균검사나 구취검사 등이 성인 계속구강건강관리 프로그램에 포함되는 것이 추천되며 계속구강건강관리 프로그램이 본인이 부담할 수 있는 적정 비용 수준으로 보험 급여화될 수 있도록 제안해야 한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.223-226
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• 2003

This paper presents a high-frequency ZVS-PWM boost chopper-fed DC-DC converter with a single active auxiliary edge-resonant snubber which is used for power conditioner such as solar photovoltaic generation and fuel cell generation. The experimental results of boost chopper fed ZVS-PWM DC-DC converter are evaluated. In audition to its switching voltage and current waveforms, and the switching v-i trajectory of the power devices are discussed and compared with the conventional hard switching DC-DC converter treated here. The temperature performance of IGBT module,, efficiency, and EMI noise characteristics of this ZVS-PWM DC-DC converter using IGBTs are measured and evaluated from an experimental point of view.

• 전력전자학회논문지
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• 제23권3호
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• pp.168-173
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• 2018

In this paper, an auxiliary power supply (APS) for railroad cars is proposed. The APS can reduce the number of devices required to supply power through structural modification and operates at a high switching frequency by application of a SiC device. The voltage stress on the device in the proposed circuit can be reduced to less than half of the input voltage of the system; thus, a device with low breakdown voltage can be designed. By adapting a SiC device instead of an IGBT device, the proposed circuit can reduce switching and conduction losses and operate at a high switching frequency, thereby reducing output voltage and inductor current ripples in the proposed circuit. The theoretical analysis results of the proposed APS are verified with a 40 kW computer-based simulation and a 2 kW experiment.

• 제어로봇시스템학회논문지
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• 제4권4호
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• pp.448-457
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• 1998

A neural network based control algorithm with fuzzy compensation is proposed for the automated adjustment in the production of electronic end-products. The process of adjustment is to tune the variable devices in order to examine the specified performances of the products ready prior to packing. Camcorder is considered as a target product. The required test and adjustment system is developed. The adjustment system consists of a NNC(neural network controller), a sub-NNC, and an auxiliary algorithm utilizing the fuzzy logic. The neural network is trained by means of errors between the outputs of the real system and the network, as well as on the errors between the changing rate of the outputs. Control algorithm is derived to speed up the learning dynamics and to avoid the local minima at higher energy level, and is able to converge to the global minimum at lower energy level. Many unexpected problems in the application of the real system are resolved by the auxiliary algorithms. As the adjustments of multiple items are related to each other, but the significant effect of performance by any specific item is not observed. The experimental result shows that the proposed method performs very effectively and are advantageous in simple architecture, extracting easily the training data without expertise, adapting to the unstable system that the input-output properties of each products are slightly different, with a wide application to other similar adjustment processes.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.153-158
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• 1998

In this paper, a prototype of the auxiliary resonant commutated snubber circuit(ARCS) with a high frequency transformer power regeneration loop is described for voltage source type sinewave inverter system. This is a new soft switching topology developed for three phase voltage source soft-switching inverter, active power filter and reactive power compensator has significant advantage of current rating reduction for auxiliary active switching devices. In addition, this paper presents a novel prototype of voltage-source soft switching space vector-modulated inverter with ARCS mentioned above, which is more suitable and acceptable for high-power utility interactive power conditioning, along with a digital control scheme. The steady-state operating analysis of ARCS has the remarkable features and the practical design procedure of this resonant snubber are illustrated on the basis of computer simulation analysis. The operating performance evaluations in the steady-state of this three phase voltage source soft switching inverter are discussed and compared with the three phase voltage source hard switching inverter.

• Journal of Power Electronics
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• 제19권2호
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• pp.380-393
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• 2019

Traditional boost converters have difficulty realizing high efficiency and high voltage gain conversion due to 1) extremely large duty cycles, 2) high voltage and current stresses on devices, and 3) low conversion efficiency. Therefore, a function decoupling high voltage gain DC/DC converter composed of a DC transformer (DCX) and an auxiliary converter is proposed. The role of DCX is to realize fixed gain conversion with high efficiency, whereas the role of the auxiliary converter is to regulate the output voltage. In this study, different forms of combined high voltage gain converters are compared and analyzed, and a structure is selected for the function decoupling high voltage gain converter. Then, topologies and control strategies for the DCX and auxiliary converter are discussed. On the basis of the discussion, an optimal design method for circuit parameters is proposed, and design procedures for the DCX are described in detail. Finally, a 400 W experimental prototype based on the proposed optimal design method is built to verify the accuracy of the theoretical analysis. The measured maximum conversion efficiency at rated power is 95.56%.

• Journal of Korean Society for Atmospheric Environment
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• 제19권E1호
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• pp.21-28
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• 2003

An auxiliary device, called Post Cyclone (PoC). had been introduced and primarily examined in earlier works which proved the reduction of the emission of fine dust from the gas-solid cyclones without incurring significant increase of cost and pressure drop. It has been known that the PoC has some advantages over other secondary dust treatment devices such as (a) simple design, (b) low cost of manufacture, (c) minimum additional pressure drop, (d) high recoverbility of the product dust, and (e) simplicity of operation. Despite the potential advantage, however, lack of practical data confined its plausible application in wide areas. Thus, in this work, a few serial experiments were conducted in terms of a few operation conditions, and the particle trajectories throughout the cyclone set-up were visually analyzed by using a commercial computer simulation program (FLUENT).