• Journal of Korean Neurosurgical Society
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• 제47권4호
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• pp.295-297
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• 2010

Candida is a relatively rare cause of spinal infections that commonly affects immunocompromised patients. A 70-year-old woman, who underwent a lumbar discectomy on L5-S1 two months earlier, was admitted to our department complaining of persistent back and leg pain. Magnetic resonance imaging showed irregular enhancing mass lesion in L5-S1 intervertebral space, suggest of pyogenic discitis with epidural abscess. The surgery was performed via retroperitoneal approach and the infected material at L5-S1 intervertebral space was removed. The histological examination of the specimen revealed chronic inflammation involving the bone and soft tissue, and a culture of the excised material was positive for Candida parapsilosis. The patient received intravenous fluconazole for 4 weeks after surgery and oral fluconazole 400 mg/day for 3 months after surgery. The patient made a full recovery with no symptoms 6 months after surgery. We present a rare case of spondylodiscitis after a lumbar discectomy due to Candida parapsilosis and discuss treatment option with a review of the literatures.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.423-426
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• 2001

본 논문에서는 전압 안정화 특성을 갖는 전자식 강압형 변압기가 제안된다. 제안된 전자식 변압기는 다음과 같은 특징을 갖는다. 1) 무게가 1kW 기준 일반 변압기의 40% 수준이다. 2) PWM 제어에 의하여 입력전압의 변동에 무관한 출력전압을 유지하는 전압 안정화 기능을 갖는다. 3) 전원 또는 부하단의 Emergency에 대하여 회로 차단기의 기능도 갖는다 4) 부하에 최기 전원 공급시, 낮은 전압으로부터 점진적으로 증가시켜가면서 전원을 인가하여, 전원 투입시 발생한 수 있는 돌입전류나 과도 충격을 제거할 수 있다. 그 밖에 무부하시 전원차단 기능과, 왜곡된 입력전압에 대한 보상기능을 추가 할 수 있다. 본 논문에서는 제안된 강압형 전자식 변압기의 회로 구성과 특징을 설명하고, 이를 PSPICE 시뮬레이션을 통하여 동작특성을 보인다.

• Journal of Power Electronics
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• 제16권5호
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• pp.1629-1638
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• 2016

Differential power processing (DPP) systems are among the most effective architectures for photovoltaic (PV) power systems because they are highly efficient as a result of their distributed local maximum power point tracking ability, which allows the fractional processing of the total generated power. However, DPP systems require a high-efficiency, high step-up/down bidirectional converter with broad operating ranges and galvanic isolation. This study proposes a single, magnetic, high-efficiency, high step-up/down bidirectional DC-DC converter. The proposed converter is composed of a bidirectional flyback and a bidirectional isolated switched-capacitor cell, which are competitively cheap. The output terminals of the flyback converter and switched-capacitor cell are connected in series to obtain the voltage step-up. In the reverse power flow, the converter reciprocally operates with high efficiency across a broad operating range because it uses hard switching instead of soft switching. The proposed topology achieves a genuine on-off interleaved energy transfer at the transformer core and windings, thus providing an excellent utilization ratio. The dynamic characteristics of the converter are analyzed for the controller design. Finally, a 240 W hardware prototype is constructed to demonstrate the operation of the bidirectional converter under a current feedback control loop. To improve the efficiency of a PV system, the maximum power point tracking method is applied to the proposed converter.

• Journal of Power Electronics
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• 제18권3호
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• pp.802-816
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• 2018

A digital direct phase-shift control (DDPSC) method based on the phase-shifted full-bridge LLC (PSFB-LLC) converter is presented. This work combines DDPSC with the conventional linear control to obtain a hybrid control strategy that has the advantages of linear control and DDPSC control. The strategy is easy to realize and has good dynamic responses. The PSFB-LLC circuit structure is simple and works in the fixed frequency mode, which is beneficial to magnetic component design; it can realize the ZVS of the switch and the ZCS of the rectifier diode in a wide load range. In this work, the PSFB-LLC converter resonator is analyzed in detail, and the concrete realization scheme of the hybrid control strategy is provided by analyzing the state-plane trajectory and the time-domain model. Finally, a 3 kW prototype is developed, and the feasibility and effectiveness of the DDPSC controller and the hybrid strategy are verified by experimental results.

• 한국소음진동공학회논문집
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• 제23권5호
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• pp.463-471
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• 2013

This paper presents design and control of electronic control suspension(ECS) equipped with controllable magnetorheological(MR) damper for passenger vehicle. In order to achieve this goal, a cylindrical type MR fluid damper that satisfies design specification of a middle-sized commercial passenger vehicle is proposed. After manufacturing the MR damper with design parameters, their field-dependent damping forces are experimentally evaluated and compared with those of a conventional damper. A quarter-vehicle MR ECS system consisting of sprung mass, spring, tire, controller and the MR damper is established in order to investigate the ride comfort performances. On the basis of the governing equation of motion of the suspension system, five control strategies(soft, hard, comfort, sport and optimal mode) are formulated. The proposed control strategies are then experimentally realized with the quarter-vehicle MR ECS system. Control performances such as vertical acceleration of the car body and tire deflection are evaluated in frequency domains on random road condition. In addition, performance comparison of WRMS(weighted root mean square) of the quarter-vehicle MR ECS system on random road are undertaken in order to investigate ride comfort characteristics.

• 한국분말재료학회지
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• 제14권5호
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• pp.303-308
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• 2007

The oxidation of $Fe_{73}Si_{16}B_7Nb_3Cu_1$ nanocrystalline powder has been conducted to investigate its influence on the electromagnetic wave absorption characteristics of the soft magnetic material. Oxidation occurred primarily on the surface of nanocrystals. Oxidation reduced the real part of complex permeability due to the reduction of the relative volume of the powder, which otherwise contributes to the permeability. Oxidation reduced the absorption efficiency of the sheet at frequencies over 1GHz, indicating that the relative contribution of skin depth increments to the absorption was not significant. The pulverization and milling process lowered the optimum crystallization temperature of the material by $40{\sim}50^{\circ}C$ because of the internal energy accumulated during the fragmentation and powder thinning processes.

• Clinics in Shoulder and Elbow
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• 제8권2호
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• pp.154-157
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• 2005

Elastofibroma dorsi is a benign soft tissue mass, not well-known because of its low incidence, and usually located between the chest wall and the inferomedial aspect of the scapula. This lesion is not true neoplasm but rather reactive hyperplasia of elastic fibers. It is mostly nontender mass, but occasionally causes snapping symptom. This tumor should be considered as a differential diagnosis of snapping scapula. The clinical diagnosis is made by magnetic resonance imaging and confirmed by pathologic findings. We present a case report of a female with elastofibroma dorsi, who had that the chief complaint was snapping scapula and palpable mass. We emphasize that snapping lesions located deep beneath the inferior tip of the scapula on the chest wall should arouse suspicion of an elastofibroma dorsi.

• Journal of Chest Surgery
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• 제34권8호
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• pp.644-647
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• 2001

Lemierre 증후군은 원발성 구인두 감염증으로 인하여 내경정맥의 패혈성 혈전정맥염과 원격전이성 감염증이 발생하는 드물고도 진행이 빠른 임상적 상태로 특징지워진다. 심한 흉부 외상으로 기관 절개하에서 기계호흡 치료 중이던 40세 남자 환자가 우측 경부의 현저한 종창과 폐렴증상이 나타나면서 전신적인 패혈증상이 동반되었다. 경부 전산화 단층촬영과 자기공명 혈관조영술에서 우측 내경정맥이 큰 중심 괴사성 혈전에 의해 완전히 폐쇄되어 있었으며, 주위로의 염증파급이 매우 심한 혈전정맥염의 소견을 보였다. Clindamycin과 haparin의 투여에도 불구하고 염증소견은 더욱 악화되었다. 즉각적인 내경정맥 혈전제거술 및 절제술을 시행하였으며, 이후 환자의 전신적인 패혈증상과 폐렴 그리고 국소적인 염증소견이 소실되었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.804-805
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• 2006

Electric scroll-compressor drives are commonly used for e.g. home appliance cooling units. The recent development of hybrid cars with internal combustion engine in combination with electrical propulsion requires new solutions to be able to cool the passenger compartment of cars at stand-still. Both application areas demand efficient motor drives to reach good economy and efficient use of limited battery power as well as competitive volume/weight for a given output. The BLDC motor is a controllable and efficient solution. A major part of the motor is the soft-magnetic core. The powder based $Somaloy^{(R)}$ material shows high resistivity and induction as the result of engineered iron particles with in-organic coating. The unique features of compacted $Somaloy^{(R)}$ components can be utilized to enhance the shape and total volume of the BLDC motor with at least maintained efficiency compared to the use of traditional laminated steel sheet cores. A careful design of the $Somaloy^{(R)}$ components can also simplify assembly and positively influence the coil configuration. This study shows a comparison between a typical laminated BLDC motor and a redesigned, $Somaloy^{(R)}$ based version adapted for a scroll-compressor application.

• Imaging Science in Dentistry
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• 제31권2호
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• pp.109-115
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• 2001

The ameloblastic carcinoma is an extremely rare, aggressive odontogenic neoplasm of the jaws. It is described as an ameloblastoma in which there is histologic evidence of malignancy in the primary or recurrent tumors, regardless of whether it has metastasized. We report an aggressive case of ameloblastic carcinoma of the mandible. A 68-year-old man with the complaint of the left facial swelling and intermittent pain was referred to our hospital. Serial images of panoramic radiograph, computed tomograph, and magnetic resonance imaging showed an ill-defined destructive radiolucent lesion of the left mandible. The lesion had typically aggressive behavior with extensive local destruction of bone and extended to the adjacent soft tissues. Bone scan revealed increased uptakes in the left mandibular body and ramus regions. Histological features were generally resembled with those of an ameloblastoma but with cytologic features of epithelial malignancy.