• 로봇학회논문지
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• 제8권4호
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• pp.273-282
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• 2013

The purpose of this study was to investigate effect of robot-assisted hand rehabilitation(Amadeo(R)) on hand motor function in chronic stroke patients. This study used a single-subject experimental design with multiple baselines across individuals. Three chronic stroke survivors with mild to sever motor impairment took part in study. Each participants had 2 weeks interval of starting intervention. Participants received robot-assisted therapy(45min/session. 3session/wk for 6wks). Finger active range of motion(AROM) was assessed by Range of Assessment program in Amadeo(R), and test-retest reliability was verified using Pearson correlation analysis. To investigate effect of Amadeo(R), finger AROM was measured immediately after each sessions and Fugl-Meyer Assessment of Upper extremity, Motor Activity Log, Nine hole peg board test and Jebsen-Taylor hand motor function test were assessed at pre-post intervention. Results were analyzed by visual analysis and comparison of pre-post tests. The test-retest reliability of Range of Assessment was good(r=.99). After robot-assisted therapy, finger AROM of participant 1, 2, and 3 was respectively improved by 18%, 3.6%, and 6% each. Hand motor function of participant 1, 3 was improved on all four tests, but not effect in participant 2. Robot-assisted hand rehabilitation could improve finger AROM and effect on hand motor function in chronic stroke patients.

• 전력전자학회논문지
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• 제8권3호
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• pp.247-252
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• 2003

전동기 절연열화와 파괴는 전동기에 가해지는 스트레스에 영향을 받는다. 즉 절연물의 수명은 주어지는 스트레스의 심한 정도에 따라서 좌우된다. 전동차용 견인전동기에서도 과도서지에 의한 전기적인 열화를 검토하는 것은 매우 중요한 요소이다. 본 논문에서는 인버터에서 발생되는 과도서지에 의한 고정자 코일의 절연특성을 고찰해 보았다. 전동기의 절연상태, 열화진전도, 열화발생 범위 등을 측정하는 유용한 비파괴시험 방법에는 여러 가지가 이용되고 있다. 누설전류, 유전손실(tan$\delta$), 정전용량, 성극지수(PI), 부분방전 등의 방법들을 통하여 고정자 코일의 절연상태를 분석하였다. 이러한 진단 방법들은 전동차의 견인전동기에 대한 열화상태와 수명예측에 유용한 방법이 될 것으로 여겨진다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.399-405
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• 2004

Recently technology resulted in highly efficient and multiple-functional electric appliances considering environmental problems. One of the environmental problems is noise of a product in respect to its function. A vacuum cleaner is an essential electric appliance in our daily lives. However, severe noise resulted from high motor speed for improving the function of the appliance is a nuisance for the user. This noise is caused by vibration from various parts of the appliance and fluid noise during a series of intake and exhaust processes while rotating the impeller connected to the axle at a high speed of the fan motor inside the vacuum cleaner rotating around 30,000-35,000 rpm. Despite the fact that many researchers conducted studies on reducing the noise level of the fan motor in a vacuum cleaner, only few studies have been conducted considering both the theoretical and experimental aspects using fluid analysis by measuring vibration and noise. Moreover, there has not been a study that accurately compared major noise data obtained considering both of the aspects. In this study, both aspects were considered by considering the following experimental and theoretical methods to verify the major causes of noise from the fan motor in a vacuum cleaner.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.304-315
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• 2013

In this paper, analysis of cascaded H-bridge multilevel inverter in DTC-SVM (Direct Torque Control-Space Vector Modulation) based induction motor drive for FCEV (Fuel Cell Electric Vehicle) is presented. Cascaded H-bridge multilevel inverter uses multiple series units of H-bridge power cells to achieve medium-voltage operation and low harmonic distortion. In FCEV, a fuel cell stack is used as the major source of electric power moreover the battery and/or ultra-capacitor is used to assist the fuel cell. These sources are suitable for utilizing in cascaded H-bridge multilevel inverter. The drive control strategy is based on DTC-SVM technique. In this scheme, first, stator voltage vector is calculated and then realized by SVM method. Contribution of multilevel inverter to the DTC-SVM scheme is led to achieve high performance motor drive. Simulations are carried out in Matlab-Simulink. Five-level and nine-level inverters are applied in 3hp FCEV induction motor drive for analysis the multilevel inverter. Each H-bridge is implemented using one fuel cell and battery. Good dynamic control and low ripple in the torque and the flux as well as distortion decrease in voltage and current profiles, demonstrate the great performance of multilevel inverter in DTC-SVM induction motor drive for vehicle application.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.288-294
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• 2013

The diagnosis of motor failures using an on-line method has been the aim of many researchers and studies. Several spectral analysis techniques have been developed and are used to facilitate on-line diagnosis methods in industry. This paper discusses the first application of a motor flux spectral analysis to the identification of broken rotor bar (BRB) faults in induction motors using a multiple signal classification (MUSIC) technique as an on-line diagnosis method. The proposed method measures the leakage flux in the radial direction using a radial flux sensor which is designed as a search coil and is installed between stator slots. The MUSIC technique, which requires fewer number of data samples and has a higher detection accuracy than the traditional fast Fourier transform (FFT) method, then calculates the motor load condition and extracts any abnormal signals related to motor failures in order to identify BRB faults. Experimental results clearly demonstrate that the proposed method is a promising candidate for an on-line diagnosis method to detect motor failures.

• Journal of Power Electronics
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• 제15권1호
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• pp.131-145
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• 2015

The voltage-source inverters (VSI) supplying a motor drive are prone to open transistor faults. To address this issue in fault-tolerant drives applicable to electric vehicles, a new open transistor fault diagnosis (FD) method is presented in this paper. According to the proposed method, in order to define the FD index, the phase angle of the converter output current is estimated by a simple trigonometric function. The proposed FD method is adaptable, simple, capable of detecting multiple open switch faults and robust to load operational variations. Keeping the FD in mind as a mandatory part of the fault tolerant control algorithm, the FD block is applied to a five-phase converter supplying a multiphase fault-tolerant PM motor drive with non-sinusoidal unbalanced current waveforms. To investigate the performance of the FD technique, the fault-tolerant sliding mode control (SMC) of a five-phase brushless direct current (BLDC) motor is developed in this paper with the embedded FD block. Once the theory is explained, experimental waveforms are obtained from a five-phase BLDC motor to show the effectiveness of the proposed FD method. The FD algorithm is implemented on a field programmable gate array (FPGA).

• 대한전기학회논문지
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• 제34권2호
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• pp.47-55
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• 1985

In this paper, a multiple pulse-width modulated ac chopper mode power controller using power transistor is described. The controller is capable of handling up to 1/2 hp of power at any lagging load power factor angle and getting the optimal efficiency operating characteristics. The development, study, and experimental evaluation of the controller with induction motor load is described.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.1028-1034
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• 1989

A method of analysis of the steady-state performance of induction motor with supply voltage controlled by cyclically-triggered inline thyristors is presented. Phase-variable model and asymmetrical components are not used in this analysis. Instead, Fast Fourier Transform technique and the method of multiple reference frames are employed to obtain the constant-speed performance of I.M. easily.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1614-1622
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• 2018

The research related to fault diagnosis in permanent magnet synchronous motors (PMSMs) has attracted considerable attention in recent years because various faults such as permanent magnet demagnetization and short-circuited turns can occur and result in unexpected failure of motor related system. Several conventional current and back electromotive force (BEMF) analysis techniques were proposed to detect certain faults in PMSMs; however, they generally deal with a single fault only. On the contrary, cases of multiple faults are common in PMSMs. We propose a fault diagnosis method for PMSMs with single and multiple combined faults. Our method uses three phase BEMF voltages based on the fast Fourier transform (FFT), support vector machine(SVM), and visualization tools for identifying fault types and severities in PMSMs. Principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE) are used to visualize the high-dimensional data into two-dimensional space. Experimental results show good visualization performance and high classification accuracy to identify fault types and severities for single and multiple faults in PMSMs.

• Journal of Trauma and Injury
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• 제36권4호
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• pp.447-450
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• 2023

Traumatic abdominal wall hernia is a rare presentation, most commonly reported in the context of motor vehicle accidents and associated with blunt abdominal injuries and handlebar injuries in the pediatric population. A 13-year-old boy presented with multiple traumatic injuries and hemodynamic instability after a high-speed motor vehicle accident. His injuries consisted of massive traumatic abdominal wall hernia (grade 4) with bowel injury and perforation, blunt aortic injury, a Chance fracture, hemopneumothorax, and a humeral shaft fracture. Initial surgical management included partial resection of the terminal ileum, sigmoid colon, and descending colon. Laparostomy was managed with negative pressure wound therapy. The patient underwent skin-only primary closure of the abdominal wall and required multiple returns to theatre for debridement, dressing changes, and repair of other injuries. Various surgical management options for abdominal wall closure were considered. In total, he underwent 36 procedures. The multiple injuries had competing management aims, which required close collaboration between specialist clinicians to form an individualized management plan. The severity and complexity of this injury was of a scale not previously experienced by many clinicians and benefited from intrahospital and interhospital specialist collaboration. The ideal aim of primary surgical repair was not possible in this case of a giant abdominal wall defect.