• Journal of Korean Neurosurgical Society
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• 제45권2호
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• pp.67-73
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• 2009

Objective : Although endoscopic procedures for lumbar disc diseases have improved greatly, the postoperative outcomes for high grade inferior migrated discs are not satisfactory. Because of anatomic limitations, a rigid endoscope cannot reach all lesions effectively. The purpose of this study was to determine the feasibility of endoscopic transforaminal suprapedicular approach to high grade inferior-migrated lumbar disc herniations. Methods : Between May 2006 and March 2008, a suprapedicular approach was performed in 53 patients with high grade inferior-migrated lumbar disc herniations using a rigid endoscope and a semi-rigid flexible curved probe. One-to-four hours after surgery, the presence of remnant discs was checked with MRI. The outcomes were evaluated with the visual analogue scale (VAS) score and the Oswestry Disability Index (ODI) one week after surgery. Results : The L2-3 level was involved in 2 patients and the L3-4 level was involved in 14 patients, while the L4-5 level was involved in 39 patients. There were single piece-type in 34 cases and a multiple piece-type in 19 cases. Satisfactory results were obtained in all cases. The mean preoperative VAS for leg pain was $9.32{\pm}0.43$ points (range, 7-10 points), whereas the mean ODI was $79.82{\pm}4.53$ points (range, 68-92 points). At the last follow-up examination, the mean postoperative VAS for leg pain was $1.78{\pm}0.71$ points and the mean postoperative ODI improved to $15.27{\pm}3.82$ points. Conclusion : A high grade inferior migrated lumbar disc is difficult to remove sufficiently by posterolateral endoscopic lumbar dscectomy using a rigid endoscope. However, a satisfactory result can be obtained by applying a transforaminal suprapedicular approach with a flexible semi-rigid curved probe.

• 한국전산구조공학회논문집
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• 제21권4호
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• pp.347-355
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• 2008

본 연구에서는 수평하중을 받는 깊은 기초에서 나타나는 지반과 기초의 상호작용을 분석할 목적으로 전통적인 소성이론을 응용하여 개발한 단자유도의 매크로요소 모델을 제시하였다. 제시한 매크로요소 모델은 지반에 매립된 깊은 기초가 수평하중을 받을 때 지반과 기초사이에 발생하는 응력의 제 성분을 각각 모델링하고 합성함으로써 구성하였는데, 이는 기초와 지반의 상호작용을 단순 스프링으로 모델링하는 기존의 방법에 비해 상호작용에 관련한 응력을 성분별로 분리하여 제공하는 장점이 있다. 본 연구에서는 상호작용과 관련한 응력의 제 요소를 마찰력과 측압저항으로 크게 분류하고 각 요소를 소성이론을 이용하여 모델링하였으며, 최종적으로 이들을 병렬로 조합하는 방식으로 매크로요소를 구성하였다. 제시한 매크로요소를 이용하여 점성토에 매립한 깊은 기초가 수평하중을 받는 경우를 해석한 결과 기초의 전체적인 거동과 더불어 상호작용 매크로요소를 구성하는 각 요소들로부터 상호작용 음력의 제 요소들을 분석해 냄으로써 기존 모델에 비해 개선된 결과를 얻을 수 있었다.

• 항공우주시스템공학회지
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• 제15권1호
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• pp.95-101
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• 2021

현재 국내에서 구축·운영 중인 문형금속탐지장비는 제조사마다 탐지감도가 다소 상이하여 항공보안 등급에 따른 단계별 적용이 어려운 실정이다. 또한 국내 항공보안 감독기관이 승인한 점검용 시험물품(FAA 3-GUN Test)은 단일 시험물품으로 문형금속탐지장비의 항공보안 등급별 운영을 위한 복수 시편으로 구성된 시험물품이 부재한 상황이다. 본 논문에서는 국내 구축 및 운영 중인 문형금속탐지장비에 대해 상용 시험물품을 적용한 탐지감도 측정시험을 실시하였으며, 이를 바탕으로 문형금속탐지장비 탐지감도 기준을 마련하였다. 또한 항공분야 특성을 고려한 한국형 표준 시험물품(OTP) 개발 방안 제시를 통해, 국내 항공보안등급별 동일 감도를 유지 할 수 있는 제도적 방안을 제시하였다.

• The Journal of Advanced Prosthodontics
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• 제13권6호
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• pp.396-407
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• 2021

PURPOSE. Zirconia has exceptional biocompatibility and good mechanical properties in clinical situations. However, finite element analysis (FEA) studies on the biomechanical stability of two-piece zirconia implant systems are limited. Therefore, the aim of this study was to compare the biomechanical properties of the two-piece zirconia and titanium implants using FEA. MATERIALS AND METHODS. Two groups of finite element (FE) models, the zirconia (Zircon) and titanium (Titan) models, were generated for the exam. Oblique (175 N) and vertical (175 N) loads were applied to the FE model generated for FEA simulation, and the stress levels and distributions were investigated. RESULTS. In oblique loading, von Mises stress values were the highest in the abutment of the Zircon model. The von Mises stress values of the Titan model for the abutment screw and implant fixture were slightly higher than those of the Zircon model. Minimum principal stress in the cortical bone was higher in the Titan model than Zircon model under oblique and vertical loading. Under both vertical and oblique loads, stress concentrations in the implant components and bone occurred in the same area. Because the material itself has high stiffness and elastic modulus, the Zircon model exhibited a higher von Mises stress value in the abutments than the Titan model, but at a level lower than the fracture strength of the material. CONCLUSION. Owing to the good esthetics and stress controllability of the Zircon model, it can be considered for clinical use.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 추계학술대회 논문집
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• pp.23-24
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• 2013

In recent years, ISG (Integrated Starter and Generator) system receives a great attention for electric electrification of normal gasoline vehicle. As a cost-effect machine design, an ISG without a permanent magnet is considered. A 12slot-10pole field-excitation flux-switching synchronous machine (FEFSSM) is designed and analyzed via JMAG. The active parts such as the field excitation coil and armature coil are located on the stator. The rotor part consisting of single piece iron makes it more robust and suitable to apply for high speed motor drive system application coupled with reduction belt. The design target is the motor with a maximum torque of 40Nm, a maximum power of 10kW and a maximum speed of 14000 rpm. In this paper, design optimization method is proposed for high torque capability.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.568-572
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• 1998

This paper defines Fuzzy Logic Units(FLUs) which are piece wise finite elements in multidimension Euclidean space, and redefines triangular membership functions which are different from those defined in traditional literature. By analyzing FLUs, this paper gives a constructive method of fuzzy rules in fuzzy logic systems based on finite element method. The simulation results of single machine to infinite bus system show the effectiveness of the proposed method in this paper.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.13-16
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• 2005

The mechanical properties of composite materials may degrade severely in the presence of damage. Especially, the high-velocity impact such as bird strike, a hailstorm, and a small piece of tire or stone during high taxing, can cause sever damage to the structures and sub-system in spite of a very small mass. However, it is not easy to detect the damage in composite plates using a single technique or any conventional methods. In this paper, the PYDF(polyvinylidene fluoride) film sensors and strain gages were used for monitoring impact damage initiation and propagation in composite laminates. The WT(wavelet transform) and STFT(short time Fourier transform) are used to decompose the sensor signals. A ultrasonic C-scan and a digital microscope are also used to examine the extent of the damage in each case. This research demonstrate how various sensing techniques, PVDF sensor in particular, can be used to characterize high-velocity impact damage in advanced composites.

• 한국기계가공학회지
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• 제6권2호
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• pp.47-51
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• 2007

Special quality of automobile clutch master cylinder(CMC) and analyzed aluminum, plastic material comparison. Efficiency of plastic master cylinder can modularize higher, light weight anger of parts, several piece parts by single parts, prove NVH(Noise, Vibration, Harshness) than aluminum master cylinder as analysis result. Also, structure is easy simplicity, exchange, maintenance costs can be reduced and decrease environmental pollution because recycling is superior. According as content of glass fiber increases, mechanical properties of matter of material increase equally and glass fiber changed variously by condition on manufacturing process. Through comparison analysis with Plastic Body development connection site, did verification.

• 한국산업융합학회 논문집
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• 제10권4호
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• pp.235-240
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• 2007

Special quality of automobile CMC(clutch master cylinder) and analyzed aluminum, plastic material comparison. Efficiency of plastic master cylinder can modularize higher, light weight anger of parts, several piece parts by single parts, prove NVH(Noise, Vibration, Harshness) than aluminum master cylinder as analysis result. Also, structure is easy simplicity, exchange, maintenance costs can be reduced and decrease environmental pollution because recycling is superior.

• 한국기계가공학회지
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• 제6권1호
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• pp.57-61
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• 2007

Special quality of automobile clutch master cylinder(CMC) and analyzed aluminum, plastic material comparison. Efficiency of plastic master cylinder can modularize higher, light weight anger of parts, several piece parts by single parts, prove NVH(Noise, Vibration, Harshness) than aluminum master cylinder as analysis result. Also, structure is easy simplicity, exchange, maintenance costs can be reduced and decrease environmental pollution because recycling is superior. According as content of glass fiber increases, mechanical properties of matter of material increase equally and glass fiber changed variously by condition on manufacturing process. Through comparison analysis with Plastic body development connection site, did verification.