• 한국융합학회논문지
• /
• 제6권5호
• /
• pp.49-54
• /
• 2015

오늘날 차량 정비에서의 기본적인 장비 중 하나인 리프트는 무거운 차량의 중량을 버틸 수 있어야 한다. 이에 따라 차량의 수리를 용이하게 해주는 튼튼한 리프트는 필수적인 장비이다. 본 연구에서는 세 가지 형상의 리프트들을 모델링하였으며, 이를 ANSYS 유한요소해석 프로그램으로 CAE를 수행하였다. 본 연구 결과값들을 바탕으로 각 형상에 따른 리프트들의 내구성을 예측할 수 있었고, 궁극적으로 안전하고 내구성이 있는 새로운 차량용리프트 개발에 기여하기 위한 데이터들을 축적할 수 있었다. 또한 디자인 면에서 융합 기술로의 접목도 가능하여 미적인 감각을 나타낼 수 있다.

• Applied Microscopy
• /
• 제46권1호
• /
• pp.14-19
• /
• 2016

Currently, focused ion beams (FIB) are widely used for specimen preparation in atom probe tomography (APT), which is a three-dimensional and atomic-scale compositional analysis tool. Specimen preparation, in which a specific region of interest is identified and a sharp needle shape created, is the first step towards successful APT analysis. The FIB technique is a powerful tool for site-specific specimen preparation because it provides a lift-out technique and a controllable manipulation function. In this paper, we demonstrate a general procedure containing the crucial points of FIB-based specimen preparation. We introduce aluminum holders with moveable pin and an axial rotation manipulator for specimen handling, which are useful for flipping and rotating the specimen to present the backside and the perpendicular direction. We also describe specimen preparation methods for nanowires and nanopowders, using a pick-up method and an embedding method by epoxy resin, respectively.

• International Journal of Aeronautical and Space Sciences
• /
• 제8권2호
• /
• pp.28-36
• /
• 2007

A multi-objective design exploration for a three-element airfoil consisted of a slat, a main wing, and a flap was carried out. The lift curve improvement is important to design high-lift system, thus design has to be performed with considered multi-angle. The objective functions considered here are to maximize the lift coefficient at landing and near stall conditions simultaneously. Kriging surrogate model which was constructed based on several sample designs is introduced. The solution space was explored based on the maximization of Expected Improvement (EI) value corresponding to objective functions on the Krigingmodels. The improvement of the model and the exploration of the optimum can be advanced at the same time by maximizing EI value. In this study, a total of 90 sample points are evaluated using the Reynolds averaged Navier-Stokes simulation(RANS) for the construction of the Kriging model. In order to obtain the information of the design space, two data mining techniques are applied to design result. One is functional Analysis of Variance(ANOVA) which can show quantitative information and the other is Self-Organizing Map(SOM) which can show qualitative information.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.325-326
• /
• 2007

SAW filter was designed by optimization technique using impulse sampling. To carry out characteristics of SAW filter the uniform IDT was adapted. And SAW filter was fabricated on $LiNbO_3$ substrates to evaluate frequency response. To apply properties of photolithography, lift off method was used. Lift off method was superior to etch method in fabrication process, frequency response property was measured by network analyzer. From a measurement of acoustic property, SAW propagation velocity was 2663.5m/sec.

• 전자공학회논문지
• /
• 제54권4호
• /
• pp.91-98
• /
• 2017

전기 임피던스 단층촬영 기법은 도메인의 표면에 부착된 전극들을 통해 주입된 전류와 측정된 전압 데이터를 기반으로, 미지의 도전율 분포를 복원하는 비파괴 기술이다. 이 논문에서는 전기 임피던스 단층촬영법에서 일반적 Tikhonov 조정을 갖는 역문제를 풀고 도전율 분포를 복원하기 위해 절단된 특이값 분해 기반의 역문제 해법을 제안하였다. 역문제 계산시간을 줄이기 위해 일반 조정행렬을 역행렬 항목에서 분리시키고 절단된 특이값 분해 방법을 적용하였다. 제안한 방법의 성능을 검증하기 위해 모의실험과 팬텀실험을 수행하고 복원결과를 비교하였다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.3080-3085
• /
• 2007

Shape optimization of the 3-dimensional WIG airfoil with 3.0-aspect ratio has been performed by using the multi-objective genetic algorithm. The WIG ship effectively floating above the surface by the ram effect and the virtual additional aspect ratio by a ground is one of next-generation and cost-effective transportations. Unlike the airplane flying out of the ground effect, a WIG ship has possibility to capsize because of unsatisfying the static stability. The WIG ship should satisfy aerodynamic properties as well as a static stability. They tend to strong contradict and it is difficult to satisfy aerodynamic properties and static stability simultaneously. It is inevitable that lift force has to scarify to obtain a static stability. Multi-objective optimization technique that the individual objectives are considered separately instead of weighting can overcome the conflict. Due to handling individual objectives, the optimum cannot be unique but a set of nondominated potential solutions: pareto optimum. There are three objectives; lift coefficient, lift-to-drag ratio and static stability. After a few evolutions, the non-dominated pareto individuals can be obtained. Pareto sets are all the set of possible and excellent solution across the design space. At any selections of the pareto set, these are no better solutions in all design space

• 한국산학기술학회논문지
• /
• 제17권6호
• /
• pp.650-655
• /
• 2016

본 논문에서는 요소수를 적용하는 SCR 인젝터의 내부유동에 대한 전산 유동해석을 수행하였다. 유동해석에 적용된 인젝터는 경사진 노즐과 스월디스크를 갖는 스월타입의 단홀 인젝터이다. 인젝터 니들의 최대 리프트 및 열림 속도를 인젝터의 설계 변수로 선정하였다. 비정상 상태로 작동하는 노즐 내부의 유동 특성을 해석하기 위하여, 움직이는 물체에 적용이 가능한 Moving Grid 기법을 적용하여 정밀한 인젝터 니들의 움직임을 모사하였다. 유동해석 결과, 인젝터 니들의 속도가 증가할수록 출구를 통한 요소수 유량은 감소하는 것으로 나타났다. 이는 인젝터 니들의 속도가 빨라질수록, 인젝터 니들 하부의 빈 공간을 채우려는 유량이 증가하고, 이러한 요소수 유량의 증가가 노즐 출구로 방출되는 유량의 감소를 유발하게 된다. 요소수 유동이 인젝터 노즐에서 출구 쪽으로 진행할수록, 스월 유동은 감소하였다. 이는 유동과 노즐 벽면과의 마찰에 기인한 것으로 사료된다. 또한, 최대 리프트 유지기간에서, 니들 리프트가 높을수록 스월 계수와 평균 스월 계수가 증가하는 경향을 보였다. 본 연구의 결과는 관련된 Urea-SCR 인젝터의 기본 설계 자료로 활용될 수 있을 것이다.

• 한국유체기계학회 논문집
• /
• 제14권5호
• /
• pp.69-74
• /
• 2011

This paper deals with the detail rotordynamic analysis for the vertical rotor system as development of vertical sea water lift pump for FPSO deep well. In a vertical rotor system, since linearized stiffness and damping coefficients of fluid film bearing are no longer be valid, hence the transient response analysis considering a fluid film force for every journal position in the bearing needs to be required. In this study, the transient response analysis of the proposed vertical pump rotor system was carried out in dry-run and wet-run conditions, respectively. The results show that orbital vibration responses of the rotor system remain stable at rated speed and thereby operating reliability of the vertical rotor system is confirmed. To overcome complexity of calculation pr ocedure and time consuming calculation of transient analysis, the calculating technique of steady-state response analysis is also proposed. The results of steady-state response obtained by applying the proposed technique to the rotor system are good agreement with the reference results, that is, transient responses.

• Journal of Periodontal and Implant Science
• /
• 제40권1호
• /
• pp.25-32
• /
• 2010

Purpose: The performance of implant surgery in the posterior maxilla often poses a challenge due to insufficient available bone. Sinus floor elevation was developed to increase the needed vertical height to overcome this problem. However, grafting materials used for the sinus lift technique eventually show resorption. The present study radiographically compared and evaluated the changes in height of the grafting materials after carrying out maxillary sinus elevation with a window opening procedure. This study also evaluated the difference between two xenogenic bone materials when being used for the sinus lifting procedure. Methods: Twenty-one patients were recruited for this study and underwent a sinus lift procedure. All sites were treated with either bovine bone (Bio-$Oss^{(R)}$) with platelet-rich plasma (PRP) or bovine bone (OCS-$B^{(R)}$)/PRP. A total of 69 implants were placed equally 6-8 months after the sinus lift. All sites were clinically and radiographically evaluated right after the implant surgery, 7-12 months, 13-24 months, and 25-48 months after their prosthetic loading. Results: Changes of implant length/bone length with time showed a statistically significant decreasing tendency (P<0.05). There was no significant change in the Bio-$Oss^{(R)}$ group (P>0.05). In contrast, the OCS-$B^{(R)}$ group showed a significant decrease with time (P<0.05). However, no significant difference was observed between the two groups (P>0.05). Conclusions: The results showed that there was significant reduction in comparison with data right after placement, after 7 to 12 months, 13 to 24 months, and over 25 months; however, reduction rates between each period have shown to be without significance. No significant difference in height change was observed between the Bio-$Oss^{(R)}$ and the OCS-$B^{(R)}$ groups.

• 전자공학회논문지A
• /
• 제28A권12호
• /
• pp.46-52
• /
• 1991

A new signal process circuit using two ISFETs as the input devices of the MOS differential amplifier stage for an ISFET biosensor has been developed. One chip integration of the newly developed signal process circuit, ISFETs and a Pt quasi-reference electrode has been carried out according to modified LOCOS p-well CMOS process. The fabricated chip showed gains of 0.8 and 1.6, good liniarity in the input-output relationship and very small power dissipation, 4mW. The chip was applied to realize a urea sensor by forming an immobilized urease membrane, using lift-off technique. on the gate of an ISFET. The urea sensor chip showed stable responses in a wide range of urea concentrations.