• 접착 및 계면
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• 제6권2호
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• pp.13-20
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• 2005

환경 친화적인 자연섬유 강화 고분자 복합재료의 계면 전단강도는 총체적인 기계적 물성을 조절하는데 매우 중요한 역할을 수행한다. Ramie와 Kenaf 섬유 강화 에폭시 복합재료의 계면 전단강도는 최종 물성을 위한 최적 조건을 찾아내기 위해 미세역학시험법과 비파괴 음향방출시험을 이용하여 평가했다. Ramie와 Kenaf 섬유의 동적 접촉각을 측정했고, 계면 접착에서 젖음성과 상호 관련시켜서 해석하였다. Ramie와 Kenaf 섬유의 기계적 물성은 단섬유 인장시험을 통해 조사했고, 통계학적으로 uni-와 bimodal Weibull 분포를 통해서 분석하였다. Ramie와 Kenaf 섬유에 대한 실제 신장율의 clamping 효과의 영향도 평가할 수 있었다. 두 가지의 다른 미세파괴 형상은 섬유다발과 단섬유 복합재료로부터 오는 축방향의 debonding과 섬유상의 fracture는 인장과 압축하중하에서 관찰할 수 있었다.

• 한국공간구조학회논문집
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• 제10권1호
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• pp.67-74
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• 2010

국내에 설치될 강구조 스타디움에 향후 신재생에너지 중 하나인 태양광 발전을 위한 PV 시스템을 적용하는 것에 따른 강재 어레이에 관한 기초 연구로 해외의 사례를 토대로 구성되었다. 연구를 진행하기 위하여 1990년대 이후 PV 시스템이 적용된 강구조 스타디움 20건을 사례 분석 대상으로 선정하였다. 선정된 20건의 강구조 스타디움을 PV 모듈을 고정하기 위하여 설치된 레일 시스템에 따라 분류해 보았다. 그 결과 격자고정방식 중 선형모듈고정방식과 지붕 통합형이 전체의 28%에 해당되는 것으로 조사되었으며 그 뒤로 레일 고정형 17%, 세로 고정방식 중 모듈그룹 고정 11% 순으로 조사되었다. 또한 스타디움 내부에는 주로 격자 고정방식 중 선형모듈 고정방식과 지붕통합형이 적용되고 있었으며 스타디움 외부나 그 외 부분에서는 앵글 브라킷으로 PV 모듈이 고정되고 있는 것으로 조사되었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1742-1749
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• 2011

The 3 way segmented Maglev switch is developed for the urban Maglev vehicle, which is scheduled to debut at the middle of 2013 in Incheon International Airport. The 3 way switch is composed of 3 moving girders, 4 fixed girders, driving units, moving units, clamping units and articulated angle relieving equipment etc. In this paper, the measured results on the interaction between vehicle and switch are discussed. The measured results are following; First, continuous moving test and natural frequency for girder and levitation rail. Second, levitation and lateral air gap of the bogies running on the curved switch. Third, noise of moving mechanical parts of the 3 way segmented switch. Forth, thermal displacement of the girder due to temperature change. With over the measured results, more reliability and stability of the 3 way segmented switch are secured.

• 대한기계학회논문집A
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• 제28권1호
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• pp.31-39
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• 2004

This paper presents design solutions for cam type transfer unit in which feeding, lifting, and clamping motions are generated by cams. In order to achieve faster transfer motion, each designed cam must satisfy the given specifications such as velocity, acceleration, jerk, pressure angle, cam thickness, and torque. To reduce absolute torque magnitude and torque variation, a conjugate cam and a torque reduction cam are used respectively. The conjugate cam eliminates the redundant pre-load by using complementary cam to avoid jumping between a cam and a follower. The torque reduction cam reduces the torque variation by applying opposite torque to a cam shaft. The experimental result shows the reductions of the absolute torque value and torque variation. The improvement of working speed and life span of cam type transfer unit can be expected.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1-6
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• 2003

In this paper, we design a wedge type rail clamp which can protect container crane from wind with constant clamping force regardless of the operating period. When we design wedge type rail clamp. it is important to determine the angle of wedge and analyze a contact condition of roller and wedge so that we might develop a rail clamp with variable capacity. Therefore, this paper suggest a process to decide wedge angles within feasible range which could be obtained using load analysis and FEA of wedge type rail clamp.

• 한국정밀공학회지
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• 제23권9호
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• pp.76-83
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• 2006

Machining accuracy is closely related with tool deflection induced by cutting forces. In this research, cutting forces and tool deflection in end milling are expressed as a closed form of tool rotational angle and cutting conditions. The discrete cutting fores caused by periodic tool entry and exit are represented as a continuous function using the Fourier series expansion. Tool deflection is predicted by direct integration of the distributed loads on cutting edges. Cutting conditions, tool geometry, run-outs and the stiffness of tool clamping part are considered together far cutting forces and tool deflection estimation. Compared with numerical methods, the presented method has advantages in prediction time reduction and the effects of feeding and run-outs on cutting forces and tool deflection can be analyzed quantitatively. This research can be effectively used in real time machining error estimation and cutting condition selection for error minimization since the form accuracy is easily predicted from tool deflection curve.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.781-785
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• 2005

Cutting forces and tool deflection in end milling are represented as the closed form of tool rotational angle and cutting conditions. The discrete cutting forces caused by tool entry and exit are continued using the Fourier series expansion. Tool deflection is predicted by direct integration of the distributed loads on cutting edges. Cutting conditions, tool geometry, run-outs and the stiffness of tool clamping pan are considered for cutting forces and tool deflection estimation. Compared to numerical methods, the presented method has advantages in short prediction time and the effects of feeding and run-outs on cutting forces and tool deflection can be analyzed quantitatively. This research can be effectively used in real time machining error estimation and cutting condition selection for error minimization since the ferm accuracy is easily predicted by tool deflect ion curve.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.321-325
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• 2005

Bipolar plate is the main part with MEA in automotive PEMFC. It must have a good electrical conductivity and excellent corrosion resistance, be cost effective. Therefore, stainless steels have been studied by many researchers because of its corrosion resistance and cost benefits. But their properties are not sufficient for the application to bipolar plate for automotive PEMFC. In this work, we have performed stamping using various commercial stainless steels to select candidate material for biploar plate and to derive design parameters for stamping simulation. The results showed that a small curvature at the corner of flow field is more favorable due to easier a plastic deformation. Stamping process was simulated by changing surface condition, and the size and angle of channel. The optimum shape and spring back phenomena were evaluated. Surface coating was applied to increase the corrosion resistance and electrical conductivity of stainless steel. The electrical interfacial resistance was 10 to $15m{\Omega}cm^2$ under clamping force of 150psi. But corrosion resistance of coating on the stainless steel was not good due to the unstableness of microstructure.

• Journal of Power Electronics
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• 제17권5호
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• pp.1244-1255
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• 2017

The space vector pulse width modulation (SVPWM) technique is a popular PWM method for medium voltage drive applications. Conventional SVPWM (CSVPWM) and bus clamped SVPWM (BCSVPWM) are the most common SVPWM techniques. This paper evaluates the performance of various advanced BCSVPWM strategies in terms of their harmonic distortion and switching loss based on a uniform frame work. A uniform frame work, pulse number captures the performance parameter variations of different SVPWM strategies for various number of samples with heterogeneous pulse numbers. This work compares different advanced BCSVPWM techniques based on the modulation index and location of the clamping position (zero vector changing angle ) of a phase in a line cycle. The frame work provides a fixed fundamental frequency of 50Hz. The different BCSVPWM switching strategies are implemented and compared experimentally on a 415V, 2.2kW, 50Hz, 3-phase induction motor drive which is fed from an IGBT based 2 KVA voltage source inverter (VSI) with a DC bus voltage of 400 V. A low cost PIC microcontroller (PIC18F452) is used as the controller platform.

• 대한치과기공학회지
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• 제37권3호
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• pp.115-120
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• 2015

Purpose: The purpose of this study is a finite element analysis of supporting bone according to custom abutment angle. Methods: Implant fixture was selected with a diameter of 4 mm and the length of 13 mm. The fixture and abutment was designed by a combination of the abutment screw clamping force to produce a custom abutment model of $0^{\circ}$, $15^{\circ}$, $25^{\circ}$ and $35^{\circ}$. The loading condition of 176 N was applied to the lingual surface of the crown, near to the incisor edge, and horizontal load. An oblique load of $90^{\circ}$ was applied long axis of the implant fixture analyze the stress of supporting bone. Results: The result of mechanical analysis was observed that the supporting bone stress analysis of the horizontal load, the von Mises stress values (MPa) are given in the order of TH00 (432.6) > TH25 (418.0) > TH15 (417.4) > TH35 (415.8), the oblique load, the von Mises stress values are given in the order of TO00 (459.3) > TO15 (399.6) > TO25 (374.8) > TO35 (343.4) Conclusion: The $35^{\circ}$ abutment over the current clinical tolerance limits will be available for clinical application.