• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.92-98
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• 2010

A new wideband bandstop filter(BSF) with a sharp roll-off characteristic is introduced in a stripline structure in this paper. The BSF consists of two sections: the first is two capacitively coupled $\lambda/4$ short-circuited lines with opposite ground positions, while the second is a capacitively coupled $\lambda/4$ short-circuited line. The BSF provides three transmission zeros within the stopband and better than 22 dB rejection over the whole wireless local area network (WLAN) band from 5.15 to 5.825 GHz. The BSF, cascaded to an U.S. ultra-wideband(UWB: 3.1~10.6 GHz) band-pass filter(BPF), is simulated with HFSS and realized with low-temperature co-fired ceramic(LTCC) green tape with a dielectric constant of 7.8. The measurement results agree well with the HFSS simulation results. The size of the UWB BPF including the BSF is $3{\times}6.3\times0.45\;mm^3$.

• 한국정밀공학회지
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• 제12권9호
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• pp.115-125
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• 1995

부품가공에 있어서 생산성향상을 위하여 버제거를 위한 고도의 기술이 더욱 중요하게 되었다. 특히 CIM 체제에서는 버제거의 자동화를 위하여 가공중에 발생하는 버형성과 파단현상을 정량적으로 예측할 필요성이 더욱 커졌다. 이미 연구된 2차원절삭에서의 버형성 모델을 실제적인 3차원절삭에 적용하기 위하여 기존의 모델을 수정하는 작업이 이루어졌다. 3차원 절삭모델로는 절삭인선에 수직한 면에서의 칩과 공구의 상대운동에 의해서 결정된다고 하는 Rubenstein의 가정이 사용되었다. 본연구에서 다루에되는 롤오버(roll-over) 버는 항상 공구진행방향으로 발생하기 때문에 3차원절삭에서의 버형성을 공구진행방향의 평면내에서의 2차원 절삭의 집합 으로 가정하였다. 공구의 기울림각(inclination angle)이 커질수록 버형성의 크기나 파단면의 크기가 감소하였다. 두종류의 파단이 버형성중에 관찰되었다. 하나는 가공물 끝면에 평행하게 파단면이 발생하였으며 다른 하나는 이에대하여 기울어진 파단이 일어났다. 가공물 끝면에 평행한 경우는 수정된 모델로부터 등가초기공구위치( equivalent initial tool distance)로부터 예측이 가능하며 기울어진 경우는 이결과와 공구의 기울림각으로부터 파단위치를 예측할 수 있다.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2011년도 제44차 학술발표회
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• pp.98-98
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• 2011

직물의 경우 드레이프성을 줄이고 KOSHI감(stiffness)을 부여하기 위해 일반적으로 나이프(knife) 코팅가공을 주로 사용한다. 하지만 니트는 워낙 신축성이 뛰어나기 때문에 큰 장력을 요구하는 일반 코팅공정을 적용할 경우 원단이 나이프에 밀리는 현상과 신장 상태에서 경화되어 니트 특유의 신축성을 완전히 읽어버리는 문제가 발생한다. 따라서 니트 코팅 가공을 위해 원단에 장력이 걸리지 않으며 니트 원단에 직접 수지를 도포하는 방식이 아닌 간접 도포가 가능한 장비를 고안하였다. 즉, 아래에 나타낸 모식도와 같이 프로팅이나 over roll 나이프 방식을 사용하여 전사에 필요한 수지를 R/F에 코팅하고 이를 니트와 붙인 후 열풍 건조기와 열실린더를 통과시켜 수지가 니트에 전사되도록 하는 것이다. 본 연구에서는 고신축성과 탁월한 포면 터치감을 가지는 니트를 겉옷 및 다양한 용도로 전개하기 위해 R/F(releas fabric)의 조건을 설정 및 코팅 조건 설정을 통해 니트 가공 직물의 성능 변화를 살펴보기로 한다.

• 동력기계공학회지
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• 제11권2호
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• pp.58-63
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• 2007

Vehicular safety and occupant injury have been of considerable interest to the public. The dynamic response of an articulated vehicle is different from that of single body vehicle due to its geometric and inertia properties. Articulated vehicles have the tendency to jackknife if they lose driving safety. Influence of factors for driving safety of an articulated vehicle(Tractor-Semitrailers) has been analysed by the EDVTS, a kinetic analysis program for an articulated vehicle. EDVTS permits an analyst to investigate the effect of many variables in a short period of time, and enables to obtain an accurate explanation of driving safety. The factors used in the analysis include the load, friction coefficient, tire flat, increase of braking force, and trailer geometry. Based on the results, the articulation angle and driving safety were influenced remarkably by the load, coefficient of friction, increase of braking force. However, trailer geometry, such as length and width, did not affect articulation angle and driving safety

• 한국소음진동공학회논문집
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• 제15권6호
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• pp.731-737
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• 2005

This paper evaluates dynamic performance of a cab over type large-sized truck for estimating the effects of frame's torsional characteristics using a computer model. The computer model considers two mounting methods of frame, flange mounting and web mounting. Frame is modeled by finite elements using MSC/NASTRAN In order to consider the flexibility of frame. The torsional test of the frame is conducted In order to validate the modeled finite element model. A load cell is used to measure the load applied to the frame. An angle sensor is used to measure the torsional angle. An actuator is used to apply a load to the frame. To estimate the effects of frame's torsional characteristics on dynamic performance, simulations are performed with the flange mounting and web mounting frame. Simulation results show that the web mounting frame's variations of roll angle, lateral acceleration, and yaw rate are larger than the flange mounting frame's variations, especially in the high velocity and the second part of the double lane course.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2012년도 제46차 학술발표회
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• pp.105-105
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• 2012

기능성 아웃도어 제품을 제조하기 위해서 사용되어지는 멤브레인은 크게 미세다공형과 친수무공형으로 구분할 수 있다. 최근에는 소비자들이 기능성 아웃도어에 쾌적성을 요구하고 있으며, 그 측면에서 본다면 미세다공형 멤브레인이 친수무공형보다 유리하다. 기존의 미세다공형 멤브레인은 고가이며, casting이 불가능한 단점을 가지고 있다. 본 연구에서는 분자구조 및 유화제 첨가에 따른 casting이 가능한 미세다공형 폴리우레탄 멤브레인의 특성에 대하여 연구하였다. Casting용 미세다공형 폴리우레탄은 soft segment와 hard segment의 비가 1/2일 때, 그리고 사용되는 용제가 MEK 단독일 때 안정적인 반응성과 이상적인 필름의 물성을 보이는 것을 확인 하였으며, 수지에 첨가되는 분산유화제의 양이 10%이상일 때 상분리 현상이 발생하지 않음을 확인 할 수 있었다. 개발된 수지의 적용성을 평가한 결과, J-knife를 이용하여 knife over roll 방식으로 25~35$g/m^2$ (dry add on)를 도포하여 $80/120/140^{\circ}C{\times}10m/min$의 다단건조 공정으로 진행했을 때 최적의 물성을 얻을 수 있었다.

• Ocean and Polar Research
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• 제33권spc3호
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• pp.397-407
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• 2011

To understand the vertical structure of ocean currents from raw data observed by lowered-ADCP (LADCP), these data require post-processing. Data were processed using Krahman's version 10.8 processing software based on Matlab. It is estimated the influence of auxiliary data affecting the processed current structure. The bottom-tracked velocities and the GPS information significantly contribute the offset on reference velocities in the bottom layer and barotropic ones in the middle layer, respectively. Good quality data can be obtained when LADCP is least tilted in pitch and roll during observation. In situ application of LADCP to the (northward) volume transports of Kuroshio in the East China Sea proved to be 24.8. Sv (= $1{\times}10^6m^3s^{-1}$) in October 2007, and 28.2 Sv in June 2008, respectively. The volume transport is relatively large over the continental slope when compared to the shelf or the deep sea.

• 한국주조공학회지
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• 제29권1호
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• pp.45-51
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• 2009

Conventionally, Al-Sn bearing manufacturing involves casting the Al-Sn alloy and roll-bonding to a steel backing strip. This article will describe the microstructural control of Al-Sn metal bearing alloy following heat treatment. When the pure aluminum rod dipped in the melt of tin maintained below the melting point of aluminum, the melting of aluminum was accelerated with penetration of tin along the grain boundary of aluminum. The length of plate-shaped eutectic tin was decreased with heat treatment time. With even longer heat treatment time over 1 hour the length of eutectic tin didn't decrease any more, while resulting in coarsening of aluminum matrix. Exuded liquid of eutectic tin was formed at the surface of Al-Sn alloy after heat treatment even at below eutectic temperature.

• 아동학회지
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• 제31권1호
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• pp.267-282
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• 2010

The purpose of this study was to examine the usability of a robot in kindergartens and the children's perceptions of that robot. In order to answer these questions, a field study, picture drawing and interviews were conducted over twelve days in a kindergarten located in Seoul. Our results indicated that children were likely to use the robot in a group and girls tended to use it more than boys. Children's affection towards the robot was positive and they perceived the robot mostly in terms of a friend. Finally, the picture drawing activity differed according to the usability level. Children who were in the high usability level grouping engaged more with educational content and storytelling while the low usability level grouping utilized the robot for singing in a large group.

• 산업기술연구
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• 제24권A호
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• pp.29-35
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• 2004

Fine blanking can be considered as a manufacturing process capable of producing sheet metal parts with completely smooth edges that may be hardly obtained by conventional shear-cutting procedures. This fact, together with the considerable economic advantages offered by this process, has been responsible for the rapid acceptance of fine blanking throughout the manufacturing industry all over the world, and the discovery of many new applications. This study was performed to investigate the effect of clearance and V-ring shape on the quality of sheared surface in a fine blanking process. The critical value needed to apply the normalized Cockcroft-Latham fracture criterion to the simulation of fine blanking is obtained by correlating the result of finite element analysis and that of experiment for the uniaxial tensile test. From finite element analysis of an axisymmetric fine blanking process, it has been found that punch load, die-roll depth, burnish zone size and shape of sheared surface are considerably influenced by clearance and V-ring shape.