• Title, Summary, Keyword: 유연 패드

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Study on Development of Flexible Pad for High Speed Train Disk Brake (고속철도 디스크 브레이크의 유연 패드 개발에 대한 연구)

  • Lee, Min-Gyu;Kim, Joo-Yong;Kim, Jae-Min;Yang, Young-Min;Kim, Sang-Ho;Cho, Chong-Du
    • Journal of the Korean Society for Railway
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    • v.14 no.2
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    • pp.100-108
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    • 2011
  • This paper investigates the structural stability and reliability on improving performance of flexible brake pad used in high speed train. To this end, an improved model of flexible pad was obtained through structural analysis. Brake pad specimens were subjected to modal, stroke and endurance tests to examine the dynamic characteristics and mechanical stability. The hot spot generation with increasing rotational speed was observed on chassis dynamometer equipment and then the structurally uniform contact between the disc and pad was achieved. The temperature distribution of flexible pad was measured using the infrared camcorder. Hence, the proposed flexible pad showed the better structural stability and thermal energy emission.

Inkjet-Printed Capacitive Touch Paper (잉크젯 프린팅 기술을 이용한 캐패스티브 터치 페이퍼)

  • Yun, Taehwa;Lee, Sak;Lim, Sungjoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.5
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    • pp.799-805
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    • 2015
  • In this paper, an inkjet-printed capacitive touch pad is proposed. This touch pad detects contacts of human finger by detecting changes in effective capacitance due to electrical impedance of human finger. A flexible, low-cost and disposable paper is used as a substrate. Inkjet printing technology makes the fabrication fast, simple and environmentally friendly. Measured capacitances of the touched and untouched states are in the range of 163 to 182pF and 218 to 272pF, respectively. The differences in the measured capacitance of each state are sufficiently large to recognize that a finger has made contact with touch pad.

안벽 방충재의 개선에 관한 연구(1)

  • Sin, Yong-Ju;Jeong, Tae-Gwon
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • pp.355-358
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    • 2011
  • 방충재(fender)는 항만에서 선박의 안전한 접이안, 계류, 안벽 보호를 하기 위하여 설치된 중요한 안벽 시설 중 하나이다. 기존의 고무 방충재는 접안력에 의한 초기 변형 28% 정도에서 가장 높은 반력이 발생하기 때문에 선박과 안벽에 지속적인 힘을 주기 때문에 안벽 및 선체에 손상을 주고 있다. 이는 잔교식이나 중력식 부두에서도 나타나는 현상이다. 또 선체의 용접 비드에 의하여 방충재 훼손으로 보수 유지비가 증가하고 안벽에 앵커로 고정된 고무 펜더는 유연성이 떨어져 선박 충격에 의한 쉽게 떨어지고 패널패드도 탈락된다. 이 연구에서는 초기 반력이 적은 에어 펜더 혹은 폼 펜더를 제안한다.

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Effect of Pad Structure and Friction Material Composition on Brake Squeal Noise (제동패드의 구조와 마찰재 조성이 제동 스킬소음에 미치는 영향)

  • Goo, Byeong Choon;Kim, Jae Chul;Lee, Beom Joo;Park, Hyoung Chul;Na, Sun Joo
    • Journal of the Korean Society for Railway
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    • v.20 no.1
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    • pp.1-10
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    • 2017
  • Brake squeal noise has been a challenging problems for a long time. It is very annoying to passengers and residents near tracks. Two methods have been applied to reduce or eliminate brake squeal noise. One is to improve frictional materials; the other is to optimize the topology and structures of brake pads. In this study, we developed two kinds of brake pads; one is a pad whose frictional material is different from the KTX brake pad friction material; the other is a flexible pad that has the same frictional material as that of the KTX brake pad, but a different structure. Squeal noise and friction coefficients were measured and analyzed using a full-scale brake dynamometer. It was found that the dynamometer test can simulate the squeal noise of KTX trains at stations. The squeal frequency of the KTX at 4500Hz was exactly reproduced; this value of 4500Hz was one of the natural frequencies of the KTX brake disc. It was also found that the squeal noise depended on the caliper pressure, initial disc temperature and braking speed. The average friction coefficient was 0.35~0.45. The new pad lowered the squeal noise by 17.3~21.6dB(A).

EmXJ : A Framework of Configurable XML Processor for Flexible Embedding (EmXJ : 유연한 임베딩을 위한 XML 처리기 구성 프레임워크)

  • Chung, Won-Ho;Kang, Mi-Yeon
    • The KIPS Transactions:PartA
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    • v.9A no.4
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    • pp.467-478
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    • 2002
  • With the rapid development of wired or wireless Internet, various kinds of resource constrained mobile devices, such as cellular phone, PDA, homepad, smart phone, handhold PC, and so on, have been emerging into personal or commercial usages. Most software to be embedded into those devices has been forced to have the characteristic of flexibility rather than the fixedness which was an inherent property of embedded system. It means that recent technologies require the flexible embedding into the variety of resource constrained mobile devices. A document processor for XML which has been positioned as a standard mark-up language for information representation on the Web, is one of the essential software to be embedded into those devices for browsing the information. In this paper, a framework for configurable XML processor called EmXJ is designed and implemented for flexible embedding into various types of resource constrained mobile devices, and its advantages are compared to conventional XML processors.

Development of Keypad Test System using PIC Controller (PIC Controller를 이용한 키패드 검사 시스템 개발)

  • Choi Kwang-Hoon;Lee Young-Choon;Kwon Tae-Kyu;Lee Seong-Cheol
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.10
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    • pp.94-101
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    • 2004
  • This paper presents the development of a keypad test system for the improvement of working environment and productivity using PTC 16F877 microprocessor. In order to detect the fault of keypad products, hardware and software design is performed in this system. Keypad fault detection system is controlled by the 8 bit one chip PIC microcontroller for the exactness and speed. Developed panel of the keypad test system is comprised of the sub-panel for selecting in the inspected keypad types and the main panel f3r displaying the working order and fault position. Furthermore, all data from keypad inspection are stored in main memory of personal computer for the database. All these functions lead to the improvement of working speed and environment.

Study on Design of ZnO-Based Thin-Film Transistors With Optimal Mechanical Stability (ZnO 기반 박막트랜지스터의 기계적 안정성 확보에 관한 연구)

  • Lee, Deok-Kyu;Park, Kyung-Yea;Ahn, Jong-Hyun;Lee, Nae-Eung;Kim, Youn-Jea
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.1
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    • pp.17-22
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    • 2011
  • ZnO-based thin-film transistors (TFTs) have been fabricated and the mechanical characteristics of electric circuits, such as stress, strain, and deformation are analyzed by the finite element method (FEM). In this study, a mechanical-stability design guide for such systems is proposed; this design takes into account the stress and deformation of the bridge to estimate the stress distribution in an $SiO_2$ film with 0 to 5% stretched on 0.5-${\mu}m$-thick. The predicted buckle amplitude of $SiO_2$ bridges agrees well with experimental results within 0.5% error. The stress and strain at the contact point between bridges and a pad were measured in a previous structural analysis. These structural analysis suggest that the numerical measurement of deformation, SU-8 coating thickness for Neutral Mechanical Plane (NMP) and ITO electrode size on a dielectric layer was useful in enhancing the structural and electrical stabilities.

Study of Flexible Forming Process Involving the Use of Sectional Flexible Die for Sheet Material (분할가변금형을 이용한 박판의 가변성형공정 연구)

  • Heo, Seong-Chan;Ku, Tae-Wan;Song, Woo-Jin;Kim, Jeong;Kang, Beom-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.3
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    • pp.299-305
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    • 2010
  • In general, the flexible forming die that has been used in the flexible forming process has the identical punch size; hence, its flexibility is relatively low because the range of allowable curvature radii is limited due to the uniform punch tip radius. Hence, a conceptual design of a sectional flexible die is presented for enhancing the flexibility of the forming process. Two punches of different sizes are used to configure the arbitrary forming surface. For a forming region with a relatively large curvature radius, a large punch array block is used; on the other hand, for the forming regions with small curvature radii, a small punch block is used. The cross-sectional profiles are compared with the target shape for evaluating the effectiveness of the process. Consequently, it is confirmed that the sectional flexible die can be used along with a combination of punch blocks of different sizes for manufacturing objective surfaces of complex shapes.

Development of Polymer Elastic Bump Formation Process and Bump Deformation Behavior Analysis for Flexible Semiconductor Package Assembly (유연 반도체 패키지 접속을 위한 폴리머 탄성범프 범핑 공정 개발 및 범프 변형 거동 분석)

  • Lee, Jae Hak;Song, Jun-Yeob;Kim, Seung Man;Kim, Yong Jin;Park, Ah-Young
    • Journal of the Microelectronics and Packaging Society
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    • v.26 no.2
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    • pp.31-43
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    • 2019
  • In this study, polymer elastic bumps were fabricated for the flexible electronic package flip chip bonding and the viscoelastic and viscoplastic behavior of the polymer elastic bumps according to the temperature and load were analyzed using FEM and experiments. The polymer elastic bump is easy to deform by the bonding load, and it is confirmed that the bump height flatness problem is easily compensated and the stress concentration on thin chip is reduced remarkably. We also develop a spiral cap type and spoke cap type polymer elastic bump of $200{\mu}m$ diameter to complement Au metal cap crack phenomenon caused by excessive deformation of polymer elastic bump. The proposed polymer elastic bumps could reduce stress of metal wiring during bump deformation compared to metal cap bump, which is completely covered with metal wiring because the metal wiring on these bumps is partially patterned and easily deformable pattern. The spoke cap bump shows the lowest stress concentration in the metal wiring while maintaining the low contact resistance because the contact area between bump and pad was wider than that of the spiral cap bump.

Inorganic Electro-luminescence Device Fabricated with $BaTiO_3$-PVDF Composite Film ($BaTiO_3$-PVDF 복합체로 제작한 무기 EL 소자)

  • Son, Yong-Ho;Jeong, Joon-Seok;Jo, Chan-Woo;Woo, Duck-Hyun;Kim, Young-Min;Kim, Sung-Jin;Yoon, Man-Soon;Ryu, Sung-Lim;Kweon, Soon-Yong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.299-299
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    • 2007
  • 후막형 무기 EL (electro-luminescence) 소자는 제조공정이 간단하고, 얇고, 가볍고, 유연한 동의 많은 장점들 때문에 휴대폰의 키패드 (key-pad) 및 광고용 back-light용으로 사용되고 있다. 이 무기 EL 소자는 비교적 손쉬운 스크린 프린팅 (screen-printing) 법으로 대면적을 제작할 수 있지만, LED (light emitting diode) 등과 비교하여 밝기가 낮아서 그 응용 분야가 제한되고 있다. EL 소자의 형광층은 전면 전극과 후면 전극 사이에 위치한다. EL은 이 형광층에 고 전기장이 걸릴 때, 전기장에 의해 가속된 전자가 형광층 내부에 첨가된 발광 중심의 전자를 여기시키고, 여기된 전자가 다시 바닥상태로 완화될 때 빛이 방출되는 현상이다. 즉, EL 소자는 이러한 전자 발광 현상을 이용한 소자로서, 전압 인가 시 발광 면 전체가 균일하게 발팡하는 평면 광원이다. 이러한 EL 소자에서 휘도의 증가는 후면 전극과 형광층 사이에 삽입되는 유전체 층의 특성과 밀접한 연관성이 있다. 본 연구에서는 고휘도 무기 EL 소자를 제작하기 위하여 이 유전체 층의 특성과 소자의 성능 사이의 관계를 알아보고자 하였다. 유전체 층에 사용하기 위해서 $BaTiO_3$-PVDF (polyvinylidene fluoride)의 복합체 필름을 제조하였다. 먼저 이 복합체 필름을 스크린 프린팅 (screen printing) 법으로 코팅하기 위한 페이스트 제작을 위해서, PVDF 수지를 용제에 녹였다. 그 다음, 일반 혼합기 및 삼단 롤밀 혼합기 (3-roll milling mixer) 등을 이용하여 $BaTiO_3$ 분말과 PVDF 용액을 다양한 비율로 혼합하여 페이스트를 제조하였다. ITO가 증착된 PET Film에 스크린 프린팅 법을 사용하여 형광층, 유전층, 배면 전극 등을 차례로 코팅하였다. $BaTiO_3$ (BT) 분말과 복합체 필름의 XRD 분석 결과, 분말 시료와 복합체 시료 모두 페로브스카이트 구조의 BT 회절선만 관찰되었다. 복합체의 단면 SEM 관찰에서는, BT 분말의 무게비가 증가할수록 더 치밀한 구조를 보여줌을 확인하였다. 또 EL소자의 유전상수와 휘도도 BT 분말의 혼합비가 증가할수록 증가하였다. 본 연구에서 제작한 무기 EL 소자의 최대 휘도는 약 $130\;cd/m^2$ 정도로 측정되었는데, 이는 휴대폰 키패드의 back-light용 광원으로 사용하기 충분하다고 판단되어진다.

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