• 대한조선학회논문집
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• 제42권2호
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• pp.124-128
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• 2005

This paper describes motion stability of a spar platform with and without a damping plate in regular waves. The heave and pitch motion equation is derived in terms of Mathieu equation and the stability diagram is obtained. It is shown that the spar platform with damping plate has smaller unstable region than that without damping plate in the stability diagram. Model tests are carried out to verify the mathematical analysis. Under the condition that the pitch natural period is approximately double the heave natural period and the heave motion is amplified at heave resonance, unstable pitch motions are evoked. However the unstable motion is stabilized in cases of spar platform with damping plate. Therefore the damping plate is an effective device to stabilize the motion of spar platform.

• 대한수의학회지
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• 제59권2호
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• pp.113-117
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• 2019

A 6-year-old intact male Maltese dog presented with a history of blindness and ataxia. Neuro-ophthalmic examination revealed dilated pupils with absent pupillary light reflexes and menace response in both eyes. Mild peripapillary edema was noted in the fundus of the right eye. After magnetic resonance imaging, the dog was provisionally diagnosed with meningoencephalitis of unknown etiology. Follow-up funduscopy was performed to monitor the condition of the optic discs for three years. Despite of the treatment with prednisolone, the optic nerve progressed to atrophy and the dog couldn't restore vision.

• 한국가시화정보학회지
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• 제18권3호
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• pp.14-22
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• 2020

An experiment, in the cases that satisfies deep water condition, has been performed to observe the strongly nonlinear sloshing flow in a rectangular tank. A variety of parametric study on oscillating frequency and amplitude was conducted and we found that two types of wave motions, sloshing wave and Faraday wave, could be persisting simultaneously even in horizontal sloshing problem. Moreover, it is observed both of symmetric and skewed symmetric Faraday wave exist. A comprehensive explanation is given to the generation mechanism of those waves and how to interact among them.

• Journal of Oral Medicine and Pain
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• 제45권4호
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• pp.115-119
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• 2020

Infectious myositis, an infection of the skeletal muscles, is a rare condition and potentially life-threatening if not detected and treated in the early stages. This clinical entity may arise from various pathogens, such as bacteria, fungi, parasites, and viruses. A propagation of contiguous infection, penetrating trauma, vascular insufficiency, or hematogenous spreading of microorganisms can cause infectious myositis. Though several cases have been reported in large muscle groups in the lower extremities, there are only a few reports on infectious myositis of the masticatory muscles. We report three cases of infectious myositis presenting jaw pain and trismus. Unlike a common head and neck infection caused by the spreading of odontogenic origin, the early diagnosis of infectious myositis was difficult because no specific lesion suspected to be the infection source was observed in the physical examination and the plain radiographs. Advanced imaging modalities such as computed tomography and magnetic resonance imaging, and laboratory evaluation is useful for the early detection of infectious myositis.

• Structural Engineering and Mechanics
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• 제77권6호
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• pp.809-817
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• 2021

In this study, the dynamic behavior of a three-span hybrid continuous arch bridge under vehicle loading is investigated. The natural vibration characteristics of the bridge were analyzed through pulsation test. In the dynamic loading test, the vibrations of the bridge under different truck speeds and different pavement conditions were tested, and time histories of deflection and acceleration of the bridge were measured. Based on the dynamic loading test, the impact coefficient was analyzed. The results indicate that the pavement smoothness had more impacts on the vibration of the bridge than the truck's speed. The vertical damping of the bridge under the excitation of the trucks is larger than the transverse damping. Resonance occurs at the side span of the bridge under a truck at 10 km/h.

• 대한영상의학회지
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• 제82권6호
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• pp.1355-1365
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• 2021

견관절의 유착성 관절낭염은 '오십견'이라 불리며 견관절의 동통과 운동제한을 주된 증상으로 한다. 대부분 임상양상으로 진단되지만 유착성 관절낭염의 병태생리와 일치하는 다양한 영상 소견들이 초음파, 자기공명영상, 자기공명영상 관절조영술에서 보고되고 있으며, 진단에 이용되고 있다. 이 종설은 견관절 유착성관절낭염의 다양한 영상의학적 진단과 관련 해부학을 다루었다.

• 동력기계공학회지
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• 제15권1호
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• pp.24-31
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• 2011

Rectangular box type structures are used in many fields of civil, mechanical and marine engineering. Especially, Most ship structures are often in contact with inner or outer fluid, like ballast, fuel and stem tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine and propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tanks. Many authors have studied vibration of rectangular tanks containing fluid. Few research on dynamic interaction among tank walls filled with fluid are reported in the vibration of rectangular tanks recently. In case of rectangular tanks, structural coupling between adjacent panels and effect of vibration modes of multiple panels on added mass of water have to be considered. In the previous report, a numerical analysis is performed for the coupling effect between panels of a tank on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region, and mode characteristics in accordance with changing breadth of the plates by using finite element method for plates and boundary element method for fluid region. In this paper, the coupling effect between panels of a tank on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region, and mode characteristics in accordance with changing length, thickness, and boundary condition of the plates are investigated numerically and discussed.

• Journal of the Korean Wood Science and Technology
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• 제30권3호
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• pp.1-11
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• 2002

This study was conducted to investigate the effects of reaction pH conditions and hardener types on the reactivity, chemical structure and adhesion performance of UF resins. Three different reaction pH conditions, such as traditional alkaline-acid (7.5 → 4.5), weak acid (4.5), and strong acid (1.0), were used to synthesize UF resins which were cured by adding three different hardeners (ammonium chloride, ammonium citrate, and zinc nitrate) to measure adhesion strength. Fourier transform infrared (FT-IR) and carbon-13 nuclear magnetic resonance (¹³C-NMR) spectroscopies were employed to study chemical structure of the resin prepared under three different reaction pH conditions. Adhesion strength of the resins cured with three different hardeners was determined with lap shear specimens in tension. The gel time of UF resins decreased with an increasing in the amount of both ammonium chloride and ammonium citrate added in the resins. However, the gel time increased for zinc nitrate. Both FT-IR and ¹³C-NMR spectroscopies showed that the strong reaction pH condition produce uronic structures in UF resin, while both alkaline-acid and weak acid conditions produce quite similar chemical species in the resins. The maximum adhesion strength was occurred with the resin prepared under strong acid pH condition. However, this study indicated that the weak acid reaction condition provide a balance between increasing resin reactivity and improving adhesion strength of UF resin. The measurement of formaldehyde emission from the panels bonded with the UF resins prepared is planned for future work.

• 대한영상의학회지
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• 제83권4호
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• pp.931-937
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• 2022

금속성 임플란트 삽입과 관련된 만성 염증 상태는 미만성 거대 B세포 림프종 발생의 위험 요소이다. 금속 이온은 림프종의 발병에 중요한 역할을 하는 것으로 알려져 있다. 저자들은 15개월 동안 근위 경골에 금속성 임플란트가 삽입된 환자에서 발생한 드문 미만성 거대 B세포 림프종 증례를 보고하고자 한다. 초음파 및 자기공명영상을 촬영하였으며 현저한 골 파괴 없이 불균형적으로 큰 골외 연조직 종괴와 골수 침범이 관찰되었다. 금속성 임플란트 삽입과 관련된 여러 합병증들이 있으며 오진하면 잘못된 치료로 이어질 수 있다. 따라서 금속성 임플란트로 인한 만성 염증 상태와 연관된 림프종과 임플란트 주위에 발생할 수 있는 다른 양성 병변 및 악성 연조직 종괴를 감별하는 것은 어렵지만 매우 중요하다.

• 한국항공우주학회지
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• 제41권1호
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• pp.40-47
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• 2013

하이브리드 로켓은 고체로켓과 매우 흡사한 내부유동 특성을 가지고 있으므로 와류흘림(vortex shedding)은 하이브리드 로켓에서도 연소안정성에 영향을 미치는 중요한 인자로 판단된다. 본 연구에서는 예연소실에서 와류를 발생시켜 연료 표면와류와의 간섭과 연소특성 변화를 관찰하였다. 기본 형상과 디스크를 장착한 실험 결과, 5개의 주파수 특성이 관찰되었으며 이들은 각각 추진제의 열적지연에 의한 주파수, 디스크, 연료 단면, 후연소실 단면 변화에 의한 와류흘림과 관련된 주파수임을 확인하였다. 특히 디스크 1과 3의 결과를 비교해 보면 디스크 위치에 따라 변화하는 와류흘림이 연소실의 특정 주파수 특성과 상호 간섭하여 공진이 발생하기도 하지만, 또 다른 경우에는 어떠한 간섭도 일어나지 않는 것을 확인하였다. 이러한 선택적 공진현상은 하이브리드 로켓의 비선형 연소안정성 발생을 설명할 수 있는 중요한 메카니즘으로 판단된다.