• 한국생산제조학회지
• /
• 제6권4호
• /
• pp.138-146
• /
• 1997

The optimal drill helix angle, point angle, and cutting conditions are recommended in the study so as to maximize the drilling performance by investigating the experimental reaults concerning with the state of chip formation, roundness of machined holes, and geometry of projected burr at hole exit, which are examined under the conditions of various helix angles, drill point angles of twist drill, cutting speeds, and feeds in operional parameters. In the easiness of chip escape, the helical type of chip is producted when a helix angle is 30$^{\circ}$, drill point angle 118$^{\circ}$, 140$^{\circ}$and feed is st between 0.1 and 0.15mm/rev. Roundness of machined hole is improved when the helix angle is 37$^{\circ}$, drill point angle is 118$^{\circ}$, and feed is 0.15mm/rev. The height of projected burr at the button of machined hole increases when the drill point angle and helix angle becomes large.

• 한국정밀공학회지
• /
• 제23권1호
• /
• pp.56-63
• /
• 2006

The aim of this study is to find the best cutting conditions as analyzing cutting process of paper shredder and shape of cutter. The test has been done variation of torque and cutting velocity according to load. When shape of cutter and distance between cutter and shaft are changed, The variation of cutting force according to cutting angle and load is geometrically analyzed. The result of geometrical analysis is presented that the radius and array of cutter is the method to improve torque of paper shredder. In this paper it is presented as basic method of design to improve cutting performance of paper shredder.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
• /
• pp.61.2-61.2
• /
• 2011

The spanwise aerodynamic loads of the wind turbine blade are investigated numerically. The blade shape such as twist and chord length along the blade span is obtained from the procedure of aerodynamically optimal design. The rated tip speed ratio and the rated wind velocity are set to 7 and 12m/s respectively. The BEM method is applied to obtain both the aerodynamic performance of the wind turbine (Fig.1) and the spanwise aerodynamic loads along the blade span including Prandtl's tip loss factor. The maximum running power coefficient is occurred around 90% radial position from hub (Fig.2). The distributed aerodynamic loads along the blade span can be used for structure analysis.

• 한국자동차공학회논문집
• /
• 제2권1호
• /
• pp.128-141
• /
• 1994

This roport explain the basic theory of desinging the accelerating durability test road and the role of each factors contributing to test road surface profile. Also this road is designed by considering the charactors of vehicle suspension system and condition of driving. In test road, the factors affecting to the vehicle Structural durability are correlation among surface shape of road profile, frequency of vehicle suspension system, distribution of axletwist angle and vibration profile height Road PSD magnitude and frequency delay is used to control these factors relation.

• 한국항공운항학회지
• /
• 제18권4호
• /
• pp.1-8
• /
• 2010

In the aerospace field, the study on a morphing-wing is in progress to improve flight performance and perform multi flight mission. There are many concepts of morphing-wing such as camber-change, wing-twist, variable-span, and so on. In this study, the aerodynamic characteristics and flight control of an air vehicle with a variable-span morphing wing (VSMW) have been investigated. VSMW with symmetric span control(SSC) can increase cruising range of aircraft by reducing drag in various flight condition. VSMW with anti-symmetric span control(ASSC) can be used in the roll control of an aircraft. The flight control about pure rolling dynamic system and full dynamic system have been performed about the cruise missile.

• 대한수학회보
• /
• 제36권1호
• /
• pp.147-159
• /
• 1999

Tabanov investigated the global symmetric perturbation of the integrable billiard mapping in the ellipse [3]. He showed the nonintegrability of the Birkhoff billiard in the perturbed domain by proving that the principal separatrices splitting angle is not zero.In this paper, using the exact separatrix map of an one-degree-of freedom Hamiltoniam system with time periodic perturbation, we show the existence the stochastic layer including the uniformly hyperbolic invariant set which implies the nonintegrability near the separatrices of a Birkhoff's billiard in the domain bounded by $C^2$ convex simple curve constructed by the generic global perturbation of the ellipse.

• Fibers and Polymers
• /
• 제5권1호
• /
• pp.19-24
• /
• 2004

PET yarns textured at different texturing conditions were treated with superheated steam or dry heat at different temperatures for different times. The effects of the treatment conditions on the thermomechanical and structural changes of the yarn were examined by shrinkage, X-ray diffraction and birefringence measurements. With increase in superheated steam temperature, the crystalline orientation factor and birefringence decreased, whereas crystal size increased. Dry heat treatment had a smaller effect on shrinkage and structural properties in comparison with superheated steam treatment. The additional shrinkage after texturing process was investigated. The effect of heat-setting in both media was more significant at $200^{\circ}C$. The time dependence of the properties was not linear.

• Fibers and Polymers
• /
• 제7권1호
• /
• pp.70-72
• /
• 2006

This paper discusses the inter fiber cohesion in man made and blended yarns. The fiber parameters such as fiber length and fineness influence the cohesion. Studies have been focused on polyester and viscose spun yarns. Though polyester and viscose yarns show similar trend in cohesion, viscose yarns exhibit better cohesion clue to their serrated cross section. Studies on the effect of blend proportion of polyester cotton and polyester viscose yarns reveal that increase of polyester and viscose in the respective blends improve the inter fiber cohesion.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
• /
• pp.699-702
• /
• 2006

We have developed twist nematic liquid crystal displays (TN-LCDs), of which the viewing angle can be controlled. The TN-LCDs have the function of switching between the wide viewing mode and narrow viewing angle mode using two tilted LC layers. Tilt angles of the two LC layers, $14^{\circ}$ and $60^{\circ}$ were required in both wide viewing angle and narrow viewing angle modes, respectively. In this way, the viewing angle range in terms of contrast ratio 5:1 can be switched from $120^{\circ}$ to $60^{\circ}$.

• 대한전자공학회논문지
• /
• 제21권4호
• /
• pp.1-6
• /
• 1984

본 논문에서는 시뮬레이션에 의하여 R2 MFC 디지탈 수신기의 구성을 위한 알고리즘을 선택하고 평가하였다. 이러한 알고리즘은 CCITT 규정을 만족함을 보여 준다. 또한 PCM 화한 신호를 수신하여 유효한 주파수 성분을 검출할 수 있는 개선된 회로를 디지탈 신호 처리 소자(S2811)를 이용하여 제시하였다. 마이크로컴퓨터 Altair 8800b를 이용하여 시뮬레이션한 결과, 주어진 잡음, 주파수 편이 및 진폭 왜곡 등에 대한 특성이 허용치내에 들어옴을 보여 주었다.