• 산업기술연구
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• 제24권A호
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• pp.139-155
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• 2004

A room and pillar mining method has been adopting at the Jeungsun limestone mine. To check stability of pillar with multiple and irregular openings, the size, shape and spacing of rib pillar were first designed using some empirical suggestions. The Finite Difference Method(FDM)was used to analyze the pillar stability. Twelve different cases with the variation of K(horizontal/vertical stress)values, different height and different spacing of pillar were used in this study. Finally Mohr-Coulomb criterion was adopted to calculate the safety factors. Horizontal and vertical displacement, maximum and minimum principal stresses, range of plastic zone and safety factors were calculated at each case. As a result of analysis, the size of one block is 160m long, 70m wide, 40m high with 20m wide rib pillar and 20m square column pillar. The overall recovery at this case can be estimated about 40%.

• 연구논문집
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• 통권33호
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• pp.81-88
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• 2003

A metal jet printing system based on ink jet printing technique is one of the effective equipments for manufacturing elements of display devices, electrical devices, information processing systems, and so on. In order to develop an actuator of the metal jet printing system, bimorph type PZT actuator(length 25.2mm, width 7.2mm, thickness 0.5mm, shim thickness 0.2mm) and its controller(voltage range $\pm24v$, built-in fast recovery diode) were suggested and investigated. Performance tests and characteristic analysis, such as displacement, force, hysteresis and frequency, were carried out. The results show that the suggested actuator and controller are suitable for the metal jet printing system.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제16권2호
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• pp.215-220
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• 1994

In the case of the trauma on the maxillofacial region occurred, we think that one of the most important thing is recovery of the function as well as reconstruction of the anatomical form. Especially, it has been that the structure of the surrounded temporomandibular joint has a great possibility to cause mouth opening limitation when a bit of displacement is caused. Therefore, in the case of the trauma on mid-face we think that we treat it after complete evaluate condition of soft and hard tissue surrounding the articular disc as well as fracture site. We report results of our study, since we obtained good results from our study concerning the refixation of the zygomatic arch, high condylectomy, coronoidectomy and myotomy for the patient being suffered from the arthrosis of the temporomandibular joint caused by insufficient fracture treatment of zygomatic arch and coronoid process.

• Journal of Dental Anesthesia and Pain Medicine
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• 제18권2호
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• pp.115-117
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• 2018

Lingual nerve injury is a rare complication of general anesthesia. The causes of lingual nerve injury following general anesthesia are multifactorial; possible mechanisms may include difficult laryngoscopy, prolonged anterior mandibular displacement, improper placement of the oropharyngeal airway, macroglossia and tongue compression. In this report, we have described a case of bilateral lingual nerve injury that was associated with orotracheal intubation for open reduction and internal fixation of the left distal radius fracture in a 61-year-old woman. In this case, early treatment with dexamethasone effectively aided the recovery of the injured lingual nerve.

• 한국전산구조공학회논문집
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• 제31권4호
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• pp.183-190
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• 2018

본 논문에서는 보의 대변형 및 비틀림 변형을 고려한 인간동력항공기 주익 main spar 질량 최적화 과정을 소개한다. 순차적 이차 프로그래밍 기법(sequential quadratic programming)을 최적화 기법으로 선정해 구조 최적설계에 적절한 최적화 알고리즘을 수행하였다. Main spar 내부 직경, 적층 두께 등을 설계변수로 설정하였다. 목적함수에는 질량 최소화, 굽힘 변형 변위 일정, 그리고 비틀림 변형 각도 일정 등의 요소를 포함하였다. 굽힘과 비틀림 변형 계산엔 대변형 해석에 적합한 기하학적 정밀 보 모델을 도입하였으며, 기하학적 정밀 보 모델에 필요한 단면 물성은 Variational Asymptotic Beam Sectional Analysis(VABS) 단면 해석프로그램를 통해 계산하였다. 그 결과 main spar의 굽힘 변형 및 비틀림 변형을 최대 1.45% 이내로 유지한 채로 7.88%의 질량 감소를 이루는 최적설계를 도출하였다, 이후 응력복원 및 변형률 복원을 통해 최적설계의 구조적 안정성과 최적화 과정의 타당성을 검증하였다.

• 센서학회지
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• 제19권5호
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• pp.361-368
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• 2010

ACROSS device, which is composed of an implantable microphone, a signal processor, and a vibrating transducer, is a fullyimplantable middle ear hearing device(F-IMEHD) for the recovery of patients with hearing loss. And since a microphone is implanted under skin and tissue at the temporal bones, the amplitude of the sound wave is attenuated by absorption and scattering. And the vibrating transducer attached to the ossicular chain caused also the different displacement from characteristic of the stapes. For the gain control of auditory signals, most of implantable hearing devices with the digital audio signal processor still apply to fitting rules of conventional hearing aid without regard to the effect of the implanted microphone and the vibrating transducer. So it should be taken into account the effect of the implantable microphone and the vibrating transducer to use the conventional audio fitting rule. The aim of this study was to measure gain characteristics caused by the implanted microphone and the vibrating transducer attached to the ossicle chains for the gain compensation of ACROSS device. Differential floating mass transducers (DFMT) of ACROSS device were clipped on four cadaver temporal bones. And after placing the DFMT on them, displacements of the ossicle chain with the DFMT operated by 1 $mA_{peak}$ current was measured using laser Doppler vibrometer. And the sensitivity of microphones under the sampled pig skin and the skin of 3 rat back were measured by stimulus of pure tones in frequency from 0.1 to 8.9 kHz. And we confirmed that the microphone implanted under skin showed poorer frequency response in the acoustic high-frequency band than it in the low- to mid- frequency band, and the resonant frequency of the stapes vibration was changed by attaching the DFMT on the incus, the displacement of the DFMT driven with 1 $mA_{rms}$ was higher by the amount of about 20 dB than that of cadaver's stapes driven by the sound presssure of 94 dB SPL in resonance frequency range.

• 한국항공우주학회지
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• 제31권4호
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• pp.44-52
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• 2003

형상기억합금은 스마트 구조물에서 작동기로 널리 쓰인다. 형상기억합금은 초기변위를 부고 열을 가하게 되면 단위 부피당 큰 회복력과 변위를 발생한다. 형상기억합금의 이론 특성은 인공근육, 작동기, 소음 및 진동감쇠, 형상의 변형 제어 등에 응용될 수 있다. 본 논문에서는 형상기억합금의 3차원 비선형 구성방정식을 이용하여 재료의 거동특성을 해석하고, 형상기억합금이 부착된 스마트구조로 응용될 수 있는 공기 흡입 덕트, 항공기 및 잠수함 동체 등의 구조를 압력이 존재하는 원형 및 복원을 해석하였다. 수치해석결과, 형상기억합금 엑츄에이터가 내압 하에서 작동하자 단면은 변형전의 모습(낮은 응력상태)으로 회복되었다.

• 한국가스학회지
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• 제19권3호
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• pp.54-59
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• 2015

가스하이드레이트(GH: Gas Hydrate)는 전 세계적으로 약 10조 톤에 이르는 엄청난 양이 대부분 해양의 대륙사면에 부존되어 있으나(동토 지역 : 2 %, 해양 대륙사면 98 %), 현재까지 가스하이드레이트 저류층으로부터 상업화할 수 있을 만큼 가스를 회수하는 기술이 개발되어 있지 않은 실정이다. 일반적으로 회수하는 방법은 감압법, 열자극법, 억제재 주입법 및 치환법 등으로 크게 나누어 볼 수 있으며, 본 연구에서는 가스하이드레이트 포화율과 감압률에 따라서 가스하이드레이트 해리시간 및 가스생산이 어떻게 달라지는 지, 그에 대한 특성을 분석하고자 하였다. 연구분석 결과 감압률과 해리시간의 상관 관계식을 도출($Y=0.0004X^2-0.499X+176.86$)할 수 있었고, 또한 감압률이 클수록 메탄생산량이 좋다는 것을 알 수 있었지만(감압률 40% 대비 50%에서 메탄가스생산량이 46.2% 향상), 감압률이 60%에서는 오히려 생산량이 줄어드는데, 이는 가스하이드레이트 재형성에 기인한 것으로 판단된다.

• 센서학회지
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• 제14권2호
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• pp.78-84
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• 2005

A contactless recharging device for totally implantable middle ear systems has been designed as a pillow type that the user can recharge the implanted battery with taking a rest. The proposed device uses the electromagnetic coupling between the transmitting coil and the receiving coil. To supply sufficient power for the implanted circuits, each coil uses LC resonance and the implanted device uses voltage doubler. A power MOSFET is used for switching the DC voltage of LC parallel circuit and the switching frequency demands on a programmable frequency generator which is controlled by microcontroller. In order to improve the electromagnetic coupling efficiency at specific positions of coil which may vary with the displacement of head, the optimal location of receiving coil was studied, and the 5 transmitting coils in a pillow for recharging the implant module was designed. From such a recharging experiment, it was found that the proposed device could provide the sufficient operating voltage within the distance of 4 cm between pillow and the implanted device.

• 대한토목학회논문집
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• 제44권2호
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• pp.133-139
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• 2024

본 연구는 현재 내진 구조 분야에서 압축부재로 사용되고 있는 폴리우레탄의 한계를 극복하기 위해 폴리케톤이라는 신소재 제안을 목적으로 한다. 기존 폴리우레탄은 우수한 탄성 특성을 지녔음에도 불구하고 구조물에 발생하는 변위를 회복하기에는 부족한 경향이 있다. 반면, 폴리케톤은 뛰어난 강도 성능을 보유함과 동시에 친환경 소재로 주목받고 있다. 이러한 장점을 가진 폴리케톤의 압축특성 평가를 위하여 기존에 사용되고 있던 폴리우레탄과의 비교실험을 진행하고자 한다. 단순압축실험과 반복 하중 조건에서의 실험 속도 변화를 통해 폴리케톤의 속도 의존성을 파악하고, 추가적으로 선행압축을 적용하여 압축거동 특성을 확인하였다. 폴리케톤은 폴리우레탄에 비하여 약 10배가량 높은 압축강도를 나타내었으며 비교적 작은 변위에서는 14배가량 높은 변형 회복능력으로 폴리케톤의 우수한 회복특성을 입증하였다.