• 제목/요약/키워드: Fatigue frequency

검색결과 840건 처리시간 0.032초

근전도 신호를 이용한 운동 처방 장치 개발 (Development of a Excercise Prescription Device using EMG Signal)

  • 김호준;이준
    • 한국정보전자통신기술학회논문지
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    • 제5권3호
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    • pp.152-157
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    • 2012
  • 본 논문은 인체 근육의 생체 전기 분석을 통한 근육 운동 처방 시스템을 개발하고 그 처방법을 제시한 것이다. 이 시스템은 근전도(EMG)를 통한 개인별 몸 상태를 우선 진단한 후 이를 근거로 운동형태, 운동 강도, 운동시간, 운동 빈도 등을 포함하는 정확한 운동처방이 이루어지도록 설계되었다. 이에 따라 사용자가 최적의 운동 상태를 유지할 수 있도록 하여 과사용 증후군과 같은 부작용을 없애 각종 의료사고 예방하고, 틀어진 자세 측정, 근육의 근력, 근육의 경직상태, 근육의 피로한 상태, 근육의 밸런스 측정 등 여러 방법으로 활용이 가능하도록 한다. 또한, 편리한 사용방법으로 전문 의료기관이 아닌 헬스장, 스포츠센터, 복지관, 보건소, 학교, 유치원 등에서도 누구나 손쉽게 활용할 수 있도록 한 것이다.

MOCVD로 증착된 $Bi_4Ti_3O_{12}$ 박막의 미세구조와 강유전성에 Cerium 첨가가 미치는 영향 (The Effect of Ce Substitution on Microstructure and Ferroelectric Properties of $Bi_4Ti_3O_{12}$ Thin Films Prepared by MOCVD)

  • 강동균;박원태;김병호
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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    • pp.12-13
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    • 2006
  • Ferroelectric Cerium-substituted $Bi_4Ti_3O_{12}$ thin films with a thickness of 200 nm were deposited using the liquid delivery metal organic chemical vapor deposition process onto a Pt(111)/Ti/$SiO_2$/Si(100) substrate. At annealing temperature above $600^{\circ}C$, the BCT thin films became crystallized and exhibited a polycrystalline structure. The BCT thin film annealed at $720^{\circ}C$ showed a large remanent polarization ($2P_r$) of $44.56\;{\mu}C/cm^2$ at an applied voltage of 5V. The BCT thin film exhibits a good fatigue resistance up to $1{\times}10^{11}$ switching cycles at a frequency of 1 MHz with applied electric field of ${\pm}5\;V$.

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PZT 세라믹 레조네이터 무연솔더 접합부의 열-기계적 피로 가속수명 (Accelerated Thermo-Mechanical Fatigue Life of Pb-Free Solder Joints for PZT Ceramic Resonator)

  • 홍원식;박노창;오철민
    • 한국재료학회지
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    • 제19권6호
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    • pp.337-343
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    • 2009
  • In this study, we optimized Pb-free Sn/Ni plating thickness and conditions were optimized to counteract the environmental regulations, such as RoHS and ELV(End-of Life Vehicles). The $B_{10}$ life verification method was also suggested to have been successful when used with the accelerated life test(ALT) for assessing Pb-free solder joint life of piezoelectric (PZT) ceramic resonator. In order to evaluate the solder joint life, a modified Norris-Landzberg equation and a Coffin-Manson equation were utilized. Test vehicles that were composed of 2520 PZT ceramic resonator on FR-4 PCB with Sn-3.0Ag-0.5Cu for ALT were manufactured as well. Thermal shock test was conducted with 1,500 cycles from $(-40{\pm}2)^{\circ}C$ to $(120{\pm}2)^{\circ}C$, and 30 minutes dwell time at each temperature, respectively. It was discovered that the thermal shock test is a very useful method in introducing the CTE mismatch caused by thermo-mechanical stress at the solder joints. The resonance frequency of test components was measured and observed the microsection views were also observed to confirm the crack generation of the solder joints.

한국인의 기허 인식 조사 (A Survey on Understanding of Qi Deficiency in Koreans)

  • 이상재;이향숙
    • Korean Journal of Acupuncture
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    • 제26권4호
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    • pp.67-75
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    • 2009
  • Objectives : To identify whether and how Korean people understand 'qi deficiency' and related symptoms. Methods : We developed a questionnaire based on the experts' comments and modification asking understanding of 'qi deficiency' and symptoms or situations related with it. Total 128 workers at community healthcare centres across the country completed the questionnaire. They were asked if they know the meaning of the word 'qi deficiency' and to give at least three symptoms or situations that they conceive are related with 'qi deficiency'. The responses were collected and descriptive and frequency analyses were performed. Results : Approximately 79.7% of responders answered that they understand the meaning of the word 'qi deficiency' and of them, 71.6% reported that they experience 'qi deficiency' sometimes or more. Regarding somatic or condition-related responses in qi deficiency, lack of power or energy (26.6%), tiredness or fatigue (22.2%), dizziness (7.2%) or sweating (6.3%) were the most frequently reported symptoms. They related symptoms such as loss of appetite (4.3%) or easily catching colds (2.4%) with qi deficiency. Factors described in traditional pattern recognition of qi deficiency were not exactly matched with the responses from this survey. Conclusions : Korean people have rather a broad concept of qi deficiency covering a range of symptoms and this should be taken into account in developing a deficiency assessment tool.

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An integrator based wind speed estimator for wind turbine control

  • Elmaati, Younes Ait;El Bahir, Lhoussain;Faitah, Khalid
    • Wind and Structures
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    • 제21권4호
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    • pp.443-460
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    • 2015
  • In this paper, an integrator based method to estimate the effective wind speed in wind turbine systems is proposed. First, the aerodynamic torque was accurately estimated through a proportional gain based observer where the generator speed is the measured output of the system. The torque signal contains not only useful frequencies of the wind, but also high frequencies and the ones due to structural vibration. The useful information of the wind signal is low frequency. A spectral analysis permitted the determination of the useful frequencies. The high frequencies were then filtered before introducing the torque signal in the wind speed observer. The desired effective wind speed was extracted through an integrator based observer using the previously estimated aerodynamic torque. The strength of the method is to avoid numerical solutions used in literature of the wind speed estimation. The effectiveness of the proposed wind speed estimator and its use to control the generator speed has been tested under turbulent situations using the FAST software (Fatigue, Aerodynamics, Structures, and Turbulence), for large scale Megawatt turbine.

A review of two theories of motion sickness and their implications for tall building motion sway

  • Walton, D.;Lamb, S.;Kwok, Kenny C.S.
    • Wind and Structures
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    • 제14권6호
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    • pp.499-515
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    • 2011
  • Low-frequency building vibration is known to induce symptoms of motion sickness in some occupants. This paper examines how the adoption of a theory of motion sickness, in conjunction with a dose-response model might inform the real-world problem of managing and designing standards for tall building motion sway. Building designers require an understanding of human responses to low-dosage motion that is not adequately considered by research into motion sickness. The traditional framework of Sensory Conflict Theory is contrasted with Postural Instability Theory. The most severe responses to motion (i.e., vomiting) are not experienced by occupants of wind-excited buildings. It is predicted that typical response sets to low-dosage motion (sleepiness and fatigue), which has not previously been measured in occupants of tall-buildings, are experienced by building occupants. These low-dose symptoms may either be masked from observation by the activity of occupants or misattributed to the demands of a typical working day. An investigation of the real-world relationship between building motion and the observation of low-dose motion sickness symptoms and a degradation of workplace performance would quantify these effects and reveal whether a greater focus on designing for occupant comfort is needed.

탱크 내부 유체 연성 효과에 의한 보강판의 진동 특성 연구 (A Study on Vibration Characteristic of Stiffened Plates with Fluid Coupling Effect inside a Tank)

  • 정우인;권종현;김문수
    • 대한조선학회 특별논문집
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    • 대한조선학회 2015년도 특별논문집
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    • pp.56-62
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    • 2015
  • In ship structure, many parts are in contact with inner or outer fluid as stern, ballast and oil tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these tanks in contact with fluid are significantly affected by fluid coupling effect. Therefore it is important to exactly predict vibration characteristics of tank structure. In order to estimate the vibration characteristics, the fluid-structure interaction(FSI) problem should be solved precisely. But it is difficult to estimate exactly the magnitude of the fluid coupling effect because it has some problems such as a fluid-structure interaction, influence by the free surface, vibration modes of structural panels and depth of water. In this paper, with fluid coupling effect, the effect of structural constraint between panels on the vibration characteristics are investigated numerically and discussed.

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조혈모세포 이식 환자의 불면증 (Insomnia in Patients with Hematopoietic Stem Cell Transplantation(HSCT))

  • 이상신;김현석
    • 생물치료정신의학
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    • 제24권3호
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    • pp.142-155
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    • 2018
  • Insomnia in patients with hematopoietic stem cell transplantation(HSCT) has been underdiagnosed and undertreated. This study reviewed the frequency, characteristics, physical and psychological effects, and treatments of insomnia in HSCT patients to highlight clinical importance in this specialized population. Furthermore, the authors intended to suggest a model that would conceptualize insomnia in the context of HSCT. In the pre-transplant period, about half of patients with HSCT suffered from sleep disturbance. A substantial number of patients experienced distressing insomnia during the HSCT procedure and recovered to the level of the pre-transplant period. However, sleep disruption could be a chronic symptom in HSCT survivors and could negatively impact quality of control, cancer-related fatigue(CRF), immune function, and psychological distress. The 3P's model(Predisposing, Precipitating, Perpetuating) explains insomnia in cancer population and could be also relevant to HSCT patients with specific consideration of CRF, graft-versus-host diseases, specific properties of hematological disease, and protective isolated milieu. Effective treatment of insomnia in HSCT includes non-pharmacological(e.g., cognitive behavioral therapy, environmental modification) and pharmacological interventions. The decision of pharmacological treatment should be based on the issue of safety due to high risk of potential drug-drug interactions. Screening, treatment, and further research of insomnia in HSCT patients using validated subjective and/or objective measures are warranted.

The Disaster Preparedness and Professional Quality of Life among Nurses in Emergency Rooms of Regional Emergency Medical Center

  • Lee, Min-Hee;Kim, Kye-Ha
    • 통합자연과학논문집
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    • 제11권4호
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    • pp.184-191
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    • 2018
  • The purpose of this study was to investigate the disaster preparedness and professional quality of life among nurses in emergency departments. The participants in this study were 56 nurses in emergency departments in two cities. The data were collected by questionnaires survey from January to August 2016. All statistical analyses were performed using SPSS ver. 23.0 program. Participants' disaster preparedness was different according to position (t=-2.32, p=.004), type of working (t=-2.32, p=.004), and frequency of traumatic events (F=5.26, p=.009). There were significant differences by gender (t=2.88, p=.006), desire for continuous work in the emergency room (t=2.95, p=.005), and job satisfaction (F=10.81, p < .001) in compassion satisfaction. Burnout was different according to gender (t=-2.05, p=.045), choice of an emergency department (t=-2.37, p=.021), desire for continuous work in the emergency room (t=-2.31, p=.025), and job satisfaction (F=11.99, p < .001). Disaster preparedness and compassion satisfaction had positively significant correlations. Compassion satisfaction of nurses in emergency department was an important variable that should be considered to improve their disaster preparedness.

호남고속철도 전차선로의 이상 상태 분석 (Analysis for Catenary System with Focus on Abnomal Conditions on Honam High Speed Line)

  • 전재근;신승권;정호성;나경민;박영
    • 한국전기전자재료학회논문지
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    • 제32권1호
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    • pp.1-5
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    • 2019
  • The overhead contact line (OCL) is a key piece of equipment for transmitting electrical energy to the pantograph of rail cars. Recently, a 400 km/h OCL was applied to the Honam high-speed line, and its performance was examined by running HEMU-430X. For the study, we analyzed the current of catenary wire concurrently while running HEMU-430X in the Honam high-speed line. Specifically, this study recorded the currents for each speed during operation of the railway vehicle. The analysis of the frequency of line current showed generation of third-harmonics, 15th-harmonics, 17th-harmonics, and 19th-harmonics. The current of catenary wire is a basic technology assessment used to determine the electrical safety of electric railway systems, and it can be used as a technology for analyzing circulating currents generated in the current configuration, as well as for analyzing electric fatigue of the OCL components.