• 동의생리병리학회지
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• 제18권3호
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• pp.924-929
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• 2004

Pigmented villonodular synovitis is a rare proliferating process of the synovium, tendon sheaths and bursae usually affecting the bone and joints. The disease can be localized or diffuse. Patients with this condition typically present with symptoms of mild discomfort and associated swelling of the involved joint. However, the spectrum of presentations is broad. Diagnosis of Pigmented villonodular synovitis can be clinically difficult, and plain radiographs are usually nonspecific. Magnetic resonance imaging is a highly diagnostic modality in characterizing pigmented villonodular synovitis when it contains hemosiderin deposits exhibiting low signal intensity on all pulse sequences. Magnetic resonance imaging is recommended for accurate preoperative staging of the disease and for follow up after treatment. I report a case of pigmented nodular synovitis in the knee joint, with review of literatures.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.477-480
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• 2004

We studied the characteristics of impedance and electromechanical coupling coefficient in ZnO and AIN thin films by using resonance frequency spectrum method. The response peak of impedance decreased with the decrease of thickness of piezoelectrics, the number of mode of response peak increased with the increase of substrate thickness. An error of $k_{t}^{2}$ estimated from input $k_{t}^{2}$ increased as the thickness of piezoelectrics decreased and the thickness of substrate increased. Also, the error was increased in case of a large acoustic impedance of substrate. It was found that the composite resonator operating in optimized condition could be designed through the resonance frequency spectrum analysis of composited resonator consisted of piezoelectric thin film and substrate.

• 마이크로전자및패키징학회지
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• 제7권4호
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• pp.43-47
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• 2000

Electron cyclotron resonance플라즈마 식자 장비를 이용하여 순수 chlorine플라즈마로 Ta박 막의 식각 특성에 관해 조사하였다. Ta박막의 시각 기구를 연구하기 위해 Optical emission actinometry (OEA)를 사용하였고 OEA조사를 통하여 최적의 공정 조건을 얻었다. 이것에 기초하여 2단계 식각을 수행하였고 마이크로 로딩 철상을 성공적으로 제어하면서 0.15 $\mu\textrm{m}$ L & S 의 우수한 단면을 얻었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.601-606
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• 2004

Vibration spectrums of the test loop according to flow conditions were analyzed in order to identify the sources of vibration at peak frequencies. While a flow condition of the sweep test was changed by varying pump rotational speed from 450 rpm to 1500 rpm by the step 150 rpm, midspan acceleration of the test section in width-direction and dynamic pressure perturbation in the test section were measured. Other sources of vibration due to the flow structure interactions, such as acoustic resonance, blade pulsing frequency and bellows wrinkles, were investigated. Pressure perturbation in the section and acoustic resonance due to branch pipe give major effects to the vibration of the test section in high frequency range of 1.5 kHz to 2.8 kHz.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.215-218
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• 2005

We have investigated on the development of 2-2 piezocomposites that have better piezoelectric activity and lower acoustic impedance than those of conventional piezoceramics. In this study, we have investigated the piezoelectric and acoustic properties of 2-2 piezocomposites sensor which were fabricated using dice-and-fill technique for the different volume fraction of PZT. The resonance characteristics measured by an impedance analyzer were similar to the analysis of finite element method. The resonance characteristics and the electromechanical coupling factor were the best when the volume fraction PZT was 0.6. It also showed the highest result from the standpoint of sensitivity, bandwidth and ring-down property and so on at the same condition. The specific characteristics shows that the 2-2 piezocomposites turned out to be superior to the ultrasonic sensor composed by single phase PZT.

• 전기학회논문지P
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• 제58권3호
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• pp.257-262
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• 2009

Capacitor is basically used for the power-factor compensation and sometimes as the passive filter to reduce harmonics of nonlinear load. Since the impedance of capacitor is inversely proportional to the frequency. The harmonic current may result in the problems of voltage distortion and resonance. Capacitor has easily fall under by two harmonic components, a nonlinear load and a distorted utility voltage. The amplified harmonic current and voltage may damage power capacitor. Hence the pre-investigation of harmonic is needed before designing and application the power factor for reducing fault rate. In this paper, we analyzed that voltage and current with harmonics components act on the capacitor under the resonance condition. we concluded that both voltage and current harmonics have an bad effect on the capacitor and current harmonics is a bitter rather than effect by voltage harmonics.

• The Korean Journal of Pain
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• 제23권3호
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• pp.202-206
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• 2010

Magnetic resonance image (MRI) is the most sensitive imaging test of the spine in routine clinical practice. Unlike conventional x-ray examinations and computed tomography scans, high-quality magnetic resonance images can be assured only if patients are able to remain perfectly still. However, some patients find it uncomfortable to remain still because of pain. In that condition, interlaminar cervical epidural injections can reduce pain and allow the procedure. When using air with the "loss of resistance" technique in epidural injections to identify the epidural space, there is the possibility of injected excessive air epidurally to mimic a herniated disc. We describe a case report of epidural air artifact in a cervical MRI after cervical epidural injections.

• 산업기술연구
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• 제24권B호
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• pp.83-87
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• 2004

A reduced structure model of a wind turbine generator is designed and manufactured. Mode data are obtained by modal testing and analytical method. Vibration response is measured and investigated under various speed condition by using a waterfall plot. Possibility of severe resonance is observed and the mechanism is explained by using the mode data. Simplified theoretical model gives the 1st resonance frequency of wind turbine structure model. The theoretical model can be applied in the design stage of the wind turbine structure to avoid the severe resonance problem.

• 대한전기학회논문지:전력기술부문A
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• 제51권11호
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• pp.535-543
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• 2002

Modern power grids are becoming more and more stressed with the load demands increasing continually. Therefore large stressed power systems exhibit complicated dynamic behavior when subjected to small disturbance. Especially, it is needed to analyze special conditions which make small signal stability structure varied according to operating conditions. This paper shows that the relation between small signal stability structure varied according to operating conditions. This paper shows that the relation between small signal stability and operating conditions can be identified well using node-focus point and 1:1 resonance point. Also, the weak point which limits operating range is found by the analysis of resonance condition, and it is shown that reactive power compensation may solve the problem in the weak points. The proposed method is applied to test systems, and the results illustrate its capabilities.

• Investigative Magnetic Resonance Imaging
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• 제11권1호
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• pp.54-57
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• 2007

국소성 소결절성 활막염은 무릎관절에 발생하는 드문 양성종양으로, 색소 융모결절성 활막염과 감별이 필요하다. 저자들은 자기공명영상에서 경 (pedicle)을 가지며 특징적인 MR 영상소견을 보이고 병리조직학적으로 확진된, 무릎에서 발생한 국소성 소결절성 활막염 1예를 보고한다.