• Title/Summary/Keyword: Self-Contact

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Fabrication of the Superhydrophobic Surface Inspired from Lotus-Effect (연꽃잎을 모사한 초소수성 표면 제작)

  • Jung, Dae-Hwan;Lim, Hyun-Eui;Noh, Jeong-Hyun;Kim, Wan-Doo
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.409-414
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    • 2007
  • Wettability of solid surfaces with liquids is governed by the chemical properties and the microstructure of the surfaces. We report on the preparation of liquid-repellent surfaces using surface-attached monolayers of perfluorinated polymer molecules on porous silica substrates. A covalent attachment of the polymer molecules to the substrate is achieved by generation of the polymer chains through starting a surface-initiated radical-chain polymerization of a fluorinated monomer. To this, self-assembled monolayers of azo initiators are attached to silica substrates, which are used to kick off the polymerization reaction in situ. The growth of the fluorinated polymer films and the characterization of the obtained surfaces by surface plasmon spectroscopy, XPS, and contact angle measurements is described. It is shown that perfluorinated polymer films can be grown with controlled thicknesses on flat and even on porous silica surfaces, essentially without changing the surface roughness. The combination of the low surface energy coating and the surface porosity allows generation of materials which are both water and oil repellent.

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Gait analysis of Healthy Adults with External Loads on Trunk (체간에 무게 부하를 적용한 정상 성인의 보행 분석)

  • Chang, Jong-Sung;Choi, Jin-Ho;Lee, Mi-Young;Kim, Meuung-Kwon
    • Journal of the Korean Society of Physical Medicine
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    • v.7 no.1
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    • pp.69-75
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    • 2012
  • Purpose : The study was designed to investigate analysis of kinematics of lower extremity in healthy adults during walking with external loads on trunk. Methods : Fifteen healthy adults were recruited and The subjects provided written and informed consent prior to participation. They walked on a ten-meter walkway at a self-selected pace with loads of 0, 5, 10, and 15kg. They completed three trials in each condition and kinematic changes were measured. A three-dimensional motion analysis system was used to analyze lower extremity kinematic data. The data collected by each way of walking task and analyzed by One-way ANOVA. Results : There were significant differences in hip and knee joint on saggittal plane at initial contact and preswing, and significant differences in ankle joint on transverse plane at preswing. Conclusion : These findings revealed that increased external loads were changed joint angles and influenced postural strategies because of kinematic mechanism and future studies is recommended to find out prevention from damage of activities of daily living.

A Study on the Eigenmode Characteristics by Changing Damping Parameters of Secondary Suspension (Damper) on Railway Vehicles (철도차량 이차현가장치 댐퍼 매개변수 변화에 따른 고유모드 특성에 대한 연구)

  • Shin, Yu-Jeong;You, Won-Hee;Park, Joon-Hyuk;Hur, Hyun-Moo
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.7
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    • pp.796-804
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    • 2011
  • Railway vehicles are capable of indicating several types of instability. This phenomenon, which is called hunting motion, is a self excited lateral oscillation that is caused by the running velocity of the vehicle and wheel frail interactive forces. The interactive forces act to change effectively the damping characteristics of railway vehicle systems. This paper will show the impact of instability on the transfer function behavior using damping characteristics of secondary suspension. The vehicle dynamics are modeled using a 17 degree of freedom considering linear wheel/rail contact. The paper deals with certain condition of the damper characteristics that one is about various damping coefficient and another is equipped damper direction.

Vibration Analysis of Damper System in Torque Converter (토크 컨버터의 댐퍼 진동 특성)

  • Park, Tae-Jun;Kim, Myung-Sik;Jang, Jae-Duk;Joo, In-Sik
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.305-310
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    • 2007
  • This paper presents a damper system design in torque converter to minimize the vibration in powertrain of automatic transmission vehicle. The lock-up clutch in torque converter makes engine and transmission connected directly. When the lock-up clutch is engaged the torque fluctuation of engine is attenuated by the damper system. This function decides the vehicle power-train dynamic characteristics. At first, the dynamic hysteresis effect with any self and surface to surface contact problems of the damper springs in the damper system for torque converter is analyzed by using FEM. It is shown that these simulation results have a good design reference to energy dissipation operating by damper system in torque converter. And, to calculate dynamic characteristics, the vehicle model is structured by using $AMESim^{(R)}$?? that is a common use program. The vehicle model shows the frequency response of vehicle by changing the stiffness of damper spring, and these results lead the most suitable stiffness of spring. Also, new damper system is analyzed resonance frequency variation and is compared with prior damper.

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A Study on Analysis of Residential Living Behavior for Realizing Lifestyle-engineering (라이프스타일공학 구현을 위한 주거공간 내 생활행위 분석연구)

  • Kwak, Yoon-Jung;Kim, Kyoung-Yeon;Lee, Yeun-Sook
    • Proceedings of the Korean Institute of Interior Design Conference
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    • 2007.05a
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    • pp.125-130
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    • 2007
  • Recently, the paradigms of residential planing are changing by digitalization, diversity and globalization. Since the infortance of residential living behavior and lifestyle have been recognizing, house can be perceived as a lifestyle engineering product which realizes lifestyle in a concrete way. The purpose of this research scrutinizes lifestyles through resident's value and preference of everyday living behavior in the residential, special contact. This research was conducted through the small group workshop to housewives divided into three groups such as the age 30-40s, 45-55s, 60-70s group. The workshop consisted of three stages, such as the awareness of family and home, the satisfaction of residential space, the value and preference of everyday living behavior. This study shows that Lifestyle characterize by ages, differences of living pattern and individual traits. The 30-40s' housewives relate to foster of a preschool child and it makes load of household. their characteristic is the preference of rest as releasing stresses. The 44-55s' housewives have self-oriented traits. they pursue own space and interaction with others. The 60-70s' housewives require natural interaction with family more than private space and an open view.

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Survey of Recognition in Parturients for Vaginal Delivery Controlled by Epidural Block (경막외차단을 시행 받은 질식분만 산모들의 인식 조사)

  • Jang, Young-Ho;Park, Eun-Ji;Kim, Ae-Ra;Cheun, Jae-Kyu
    • The Korean Journal of Pain
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    • v.11 no.1
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    • pp.96-100
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    • 1998
  • Bakground: At our institution, We have controlled pain during vaginal delivery with epidural block since 1986. We designed a questionaire for parturients to analyze the degree of satisfaction of epidural block. Method: The self-questionaire were sent to parturients(N=200), who had epidural block to control labor pain during vaginal delivery. The questionaire covered topics dealing with motivation, fear, satisfaction and complications, of epidural block. Results: Motivation by an experienced person was 72.5%(145 parturients), fear of epidural block was 66%(132 parturients), and satisfactory response was 84%(168 parturients). Parturients who knew the role of anesthesiologist numbered 105(52.5%). Scarcely, 46 parturients displayed confidence for safety of fetus; 111 parturients experienced more than one complications. But special therapy for complications were not necessary. Conclusions: Publicity through mass-media and direct contact will improve the recognition and merit of epidural block by parturients as well as the role of the department of anesthesiology.

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Performance Evaluation of PTFE Oil-seal for Automotive Engine Front Part (자동차 엔진 프론트부의 PTFE 오일씰의 성능평가)

  • Choi, Hyun-Jin;Park, Chul-Woo;Lee, Jong-Cheol;Kim, Jong-Gab;Choi, Seong-Dae
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.2
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    • pp.66-71
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    • 2011
  • This study analyzed the mechanical characteristics and evaluated their subsequent performance for two types of seals which reinforced characteristics with lower friction and anti-wear functions among the foremost important features in the automotive engine seals; one with the addition of glass fiber to PTFE(Polytetrafluoro ethylene); the other with the addition of self-lubricant molybdenumin addition to the glass fiber. Based on the configuration design of seal installed to the front part in the automotive engine, this study carried out interpretations on the stress and reaction for those two types of oil seals to compare the maximum stress and contact load generated from the seal steel, rubber and PTFE lip. This study also verified the stress concentration and anti-wear performance through the coefficient of friction, torque and durability test by producing two types of PTFE seals actually.

An Exploratory Study on Late Schooler′s Health Concept and Health Behavior (학령후기 아동의 건강개념 및 건강행위에 관한 서술적 연구)

  • Lee Ji Won
    • Child Health Nursing Research
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    • v.5 no.1
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    • pp.18-26
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    • 1999
  • The purpose of this study was to explore the late schooler's health concept and health behavior. The research was a descriptive method using a self-report questionaire which include semi open-ended questions. the subjects were 458 late schooler's from 4 to 6 grade. The results were as follows : 1. Perceived health concepts were ‘having no illness’ ‘having normal physical feature and strength’ ‘eating food well’ ‘take exercise’ ‘having a bright mind’ ‘having good interpersonal relationships’‘having strong will’ ‘recovering well’. 2. Perceived health behaviors to maintain health were ‘taking proper exercise’ ‘eating proper food’ ‘maintaining cleanliness’ ‘taking sufficient rest and sleep’ ‘having a vigor life and positive thought’ ‘having good interterpersonal relationships’ ‘receiving health check and immunization’. 3. Health behaviors carried out at present were ‘taking proper exercise’ ‘eating proper food’ ‘having a vigor life and positive thought’ ‘receiving health check an immunization’ ‘taking supplementary drugs’ ‘having a regular life’ ‘maintaining cleanliness’ ‘maintaining warmth’. 4. Perceived causes of illness were ‘taking inproper food’ ‘uncleanliness’ ‘insufficient warmth or environment’ ‘lack of exercise or overexertion’ ‘irregular life habits’ ‘contact with germs’ ‘mental stress’. 5. Perceived treatments of illness were ‘having sufficient rest and sleep’ ‘mental relaxation’ ‘eating food’ ‘ maintinging cleanliness’ ‘ maintaining warmth’ ‘taking supplementary drug’ ‘receiving medical treatment’.

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Quaternary Ammonium-Based Room Temperature Ionic Liquids as Components of Carbonate Electrolytes for Li-ion Batteries: Electrochemical Performance and Thermal Properties

  • Chernyshov, Denis V.;Shin, Woo Cheol
    • Journal of Electrochemical Science and Technology
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    • v.5 no.4
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    • pp.95-104
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    • 2014
  • Electrochemical performance of Li-ion cells with $LiMn_2O_4$ cathodes and graphite anodes with carbonates electrolytes containing quaternary ammonium-based room temperature ionic liquids (ILs) is investigated. Eight different ILs based on tetraalkylammonium, pyrrolidinium or piperidinium cations paired with bis(trifluoromethylsulfonyl)imide or tris(pentafluoroethyl)trifluorophosphate anions are examined in combination with dimethyl carbonate as a main solvent and fluoroethylene carbonate as a solid electrolyte interface forming agent. It is shown that cycling properties of the cells are strongly affected by the content of ILs in the electrolyte mixtures and its increase corresponds to lower discharge capacity retention. Since viscosity and conductivity of ILs are of a great importance for the electrolytes formulation, some kind of combined parameter should be used for the assessment of IL applicability and calculated values of Walden products for neat ILs represent one of the possible options. Besides, positive effect of ILs on reduction of flammability and enhancement of thermal stability of electrolytes in contact with charged electrodes have been demonstrated by means of self-extinguishing time test and differential scanning calorimetry respectively.

Development of a Finite Element Model for Frontal Crash Analysis of a Large-Sized Truck (대형트럭의 정면 충돌 특성해석을 위한 유한요소모델의 개발)

  • Kim, Hak-Duck;Song, Ju-Hyun;Oh, Chae-Youn
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.489-494
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    • 2001
  • This paper develops a finite element model for frontal crash analysis of a large-sized truck. It is composed of 220 parts, 70,041 nodes and 69,073 elements. This paper explains only major parts' models in detail such as frame, cab, floor, and bumper which affect on crash analysis a lot. In order to prevent penetration not only at a part itself but also between parts, all contact areas are defined using type-36, self-impact type. The developed model's reliability is validated by comparing simulation and crash test results. The results used for model validation are vehicle pulses at B-pillar, and frame and deformation of frame and cab. The frontal crash simulation is performed with the same conditions as crash test. And, it is performed using PAM-CRASH installed in super-computer SP2. The developed model whose reliability is verified may be used as a base to develop a finite element model for occupant behavior and injury coefficient analysis.

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