표면적 변화에 기반한 입체적 웨어러블 호흡수 센서의 가능성 탐색

이승표,반현성,이주현 한국감성과학회 2018 감성과학 Vol.21 No.1

This study suggests the sensing method of the Three-dimensional respiration rate sensor based on surface area changes, and exploring the design direction of the three-dimensional breathing sensor and the design orientation of the garment. To achieve this, two types of three-dimensional respiration rate sensor were produced, and the study of the dummy and the subjects studied. The studyⅠ investigated the possibility of measurement of the threedimensional respiration sensor by the study variables of the sensor type and speed of respiration. The studyⅡ proposes a suitable type of sensor for each of the three measuring positions in addition to the study variables in the studyⅠ. To evaluate accuracy, reproducibility, and reliability of the three-dimensional respiration rate sensor, the BIOPAC was used to measure the respiration rate simultaneously with the three-dimensional respiration rate sensor. Through all these results of the experiment, it explored the possibility of measurement of the three-dimensional respiration sensor for the dummy. It also proposed a suitable type of sensor by measuring the respiration rate for the human body. 본 연구에서는 센서의 표면적 변화에 따른 입체적 호흡수 센서의 센싱 방식을 제안하고, 직물 기반의 입체적 호흡수센서의 성능 평가 및 의복에 적용할 수 있는 디자인 방향성을 탐색하고자 한다. 이를 위해 입체적 구조의 차이에따라 2가지 유형의 입체적 호흡수 센서를 제작하고 더미와 인체 대상으로 연구를 실시하였다. 연구Ⅰ은 더미 대상실험으로 센서의 유형 및 호흡 속도의 연구변인에 의해 입체적 호흡수 센서의 측정 가능성을 탐색하였다. 연구Ⅱ는7명의 20대 남성을 대상 실험으로 연구Ⅰ의 연구변인 이외에 3개의 측정 위치별 적합한 유형의 센서를 제안하였다. 입체적 호흡수 센서의 정확도, 재현성, 신뢰도를 평가하기 위해, 의료기기 분야의 대표적 웨어러블 호흡수 센서인 BIOPAC을 사용하여 입체적 호흡수 센서와 동시에 호흡수를 측정하였다. 이상의 연구 결과를 통해 더미 대상으로입체적 호흡수 센서의 측정 가능성을 탐색하였으며, 인체 대상으로 호흡수를 측정하여 측정 위치별 적합한 유형의 센서를 제안하였다.

초탄성 및 점탄성 물성을 고려한 자동차용 휠 베어링 실의 드래그 토크 예측

이승표 한국트라이볼로지학회 2019 한국윤활학회지(윤활학회지) Vol.35 No.5

Wheel bearings are important automotive parts that bear the vehicle weight and translate rotation motion; in addition, their seals are components that prevent grease leakage and foreign material from entering from the outside of the bearings. Recently, as the need for electric vehicles and eco-friendly vehicles has been emerging, the reduction in fuel consumption and CO2 emissions are becoming the most important issues for automobile manufacturers. In the case of wheel bearings, seals are a key part of drag torque. In this study, we investigate the prediction of the drag torque taking into consideration the hyperelastic and viscoelastic material properties of automotive wheel bearing seals. Numerical analysis based on the finite element method is conducted for the deformation analyses of the seals. To improve the reliability of the rubber seal analysis, three types of rubber material properties are considered, and analysis is conducted using the hyperelastic material properties. Viscoelastic material property tests are also conducted. Deformation analysis considering the hyperelastic and viscoelastic material properties is performed, and the effects of the viscoelastic material properties are compared with the results obtained by the consideration of the hyperelastic material properties. As a result of these analyses, the drag torque is 0.29 Nm when the hyperelastic characteristics are taken into account, and the drag torque is 0.27 Nm when both the hyperelastic and viscoelastic characteristics are taken into account. Therefore, it is determined that the analysis considering both hyperelastic and viscoelastic characteristics must be performed because of its reliability in predicting the drag torque of the rubber seals.

Deformation analysis of rubber seal assembly considering uncertainties in mechanical properties

이승표,강기원 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7

Rubber seals are used in the assemblies of mechanical parts in automobiles and aircrafts to prevent lubricant leakage and inclusion of foreign object. Because of the recent increase in the warranty periods of mechanical parts for automobiles, there is a need for longer service lives than those of existing products, and there is an even greater need for performance-related reliability during usage. This study analyzes the deformation behavior of rubber seals, including an overmold, used in the assemblies of mechanical parts. To improve the reliability of the analysis for rubber seal, three types of static experiments on rubber were conducted to obtain rubber properties. The experimental results were used to perform a hyper-elastic analysis considering rubber seal contact. The deformation analysis for rubber seal was performed to predict the performance after the assembling process. Moreover, a Monte Carlo simulation considering the probabilistic distribution of the mechanical properties of the rubber was performed to identify the effect of uncertainties in the rubber properties on deformation behavior of rubber seal. The pre- and post-deformation distributions of the rubber seal assembly were derived from the results of the Monte Carlo simulation, and they were used to evaluate the stability of the mechanical parts during the assembling process.

Drag Torque Prediction of Automotive Wheel Bearing Seals Considering Material and Geometrical Uncertainties Using Monte Carlo Simulation

이승표,김재훈,강기원 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.6

In this study, the drag torque was predicted considering the uncertainties in geometry and material properties of automotive wheel bearing seals. For this, the deformation of the seals was firstly analyzed using numerical analysis based on the finite element method. Three types of experiments for material properties of rubber were conducted to improve the reliability of deformation analysis for the rubber seals. In addition, hyperelastic analysis was conducted using the experimental results. To consider the geometrical and material uncertainties of the seals, Monte Carlo simulation was performed considering variations in dimension and rubber properties. As Monte Carlo simulation to analyze the deformation of the seals takes a very high computational cost, a response surface was created using design of experiment (DOE) and then Monte Carlo simulation was performed using this response surface. Based on the simulation results, sensitivity analysis was conducted to analyze design variables that affect the drag torque of the rubber seal. Finally, variation in the drag torque of the automotive wheel bearing seals was evaluated using the results of Monte Carlo simulation.

시간에 따른 회전 및 하중을 고려한 강체 동역학 해석에기반한 베어링 성능 평가

이승표 한국트라이볼로지학회 2023 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.39 No.2

Bearing is a mechanical component that supports loads and transmits rotation. As the application of high-value-added products such as semiconductors, aviation, and robots have recently become diverse and more precise, an accurate bearing performance prediction and evaluation technology is required. Bearing performance evaluation can be divided into evaluations based on bearing theory and on numerical analysis. An evaluation based on numerical analysis is a technique that has been highlighted because the problems that remained unsolved owing to time problems can be solved through recent developments in computers. However, current studies have the disadvantage of not considering the essential changes over time and bearing rotation. In this study, bearing performance evaluation based on rigid body dynamic analysis considering rotation and load over time is performed. Rigid body dynamic analysis is performed for deep groove ball bearing to calculate the load applied by the ball. The reliability of the analysis is verified by comparing it with the results calculated using bearing theory. In addition, rigid body dynamic analysis is performed for automotive wheel bearings to calculate the contact angle and load applied by the ball for cases where axial load and radial load are applied, respectively. The effect of rotation and load over time is evaluated from these results.

센서의 단면적 변화에 따른 전기저항 방식 기반의 직물형 웨어러블 호흡 센서

이승표,구혜란,전동진,이주현 한국감성과학회 2016 추계학술대회 Vol.2016 No.-

Tricuspid Regurgitation, Isn’t It Time to Look Around the Valve Rather Than the Valve Itself?

이승표 한국심초음파학회 2015 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.23 No.3

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Association of Myocardial Angiogenesis with Structural and Functional Ventricular Remodeling in Aortic Stenosis Patients with Normal Ejection Fraction

이승표,김형관,김용진,오세일,손대원 한국심초음파학회 2014 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.22 No.2

Background: Although rarefaction of myocardial angiogenesis has been shown to be associated with left ventricular (LV)systolic dysfunction in animal models of ventricular hypertrophy, this relationship has not been investigated in depth norvalidated in humans. We aimed to analyze the relationship of myocardial angiogenesis with various functional and structuralventricular remodeling parameters in moderate to severe aortic stenosis (AS) patients with normal LV ejection fraction (LVEF). Methods: A total of 38 moderate or severe AS patients with LVEF > 50% were enrolled for the current study and all patientsunderwent LV endomyocardial biopsy at the septum during aortic valve replacement. The biopsy specimens were stained forplatelet endothelial cell adhesion molecule-1 (CD31) to analyze the density of blood vessels in the myocardium. Results: The degree of myocardial angiogenesis tended to increase with worse myocardial systolic function, LV filling pressure andprogressed ventricular hypertrophy (Spearman’s ρ = -0.388, p = 0.016 for LVEF; Spearman’s ρ = 0.442, p = 0.007 for E/e’; Spearman’sρ = 0.424, p = 0.008 for LV mass index). The degree of myocardial angiogenesis was also significantly associated with the degree ofaortic valve stenosis (Spearman’s ρ = -0.368, p = 0.023). There was significant difference in the degree of myocardial angiogenesisaccording to the LV geometry (p = 0.016 for mean difference between different LV geometry groups by analysis of variance). Significant predictors of myocardial blood vessel density were LV mass index (β = 0.398, p = 0.010) and LVEF (β = -0.313, p = 0.028). Conclusion: There is a close relationship between myocardial angiogenesis and LV remodeling in moderate to severe ASpatients with normal LVEF, with angiogenesis increasing with LV hypertrophy. Further studies to demonstrate the mechanismunderlying this phenomenon is warranted.

심장판막질환 치료의 최신 지견

이승표 대한내과학회 2019 대한내과학회 추계학술대회 Vol.2019 No.2

항공기 이륙중량 추정을 위한 관련 요인 분석 (B737-800을 중심으로)

이승표,구성관 한국항행학회 2023 韓國航行學會論文誌 Vol.27 No.5

이륙중량은 항공기의 탄소 배출량과 연료 소모량을 추정할 때 정확도를 향상시킬수 있는 중요한 열쇠이다. 하지만 이륙중량은 항공사의 경영전략을 유추할 수 있는 민감한 유상하중 정보가 포함되어 있어 외부 유출이 불가능하다. 선행연구에서 이륙중량을 추정할 수 있는 몇 가지 모델이 제시되었지만, 연구자는 알 수 없는 조종사가 설정하는 변수들에 의해 연구의 한계가 존재한다고 지적한다. 본 연구에서는 이러한 한계를 통제할수 있는 방법을 제시하기 위해 이륙중량과 연관된 여러 변수를 확인하였다. 그중 이륙중량의 정확도를 향상시킬수 있는 변수를 선별하였고 이를 상용화된 ADS-B 정보에 적용하여 추정 방법을 제시한다. 제시하는 추정 식은 평균적인 이륙중량을 추정하는 것이 아니라 이륙중량 범위 내의 모든 구간에서 추정을 할 수 있다. Take-off weight is a key factor for improving accuracy when estimating an aircraft's carbon emissions and fuel consumption. However, the takeoff weight contains sensitive payload information that can infer the airline's management strategy, making it impossible to leak it outside. Although several models for estimating takeoff weight have been presented in previous studies, the researcher points out that there are limitations of the study caused by variables at the pilot’s discretion. In this paper, several variables related to takeoff weight are identified to suggest a way to control these limits. Among them, variables that can improve the accuracy of takeoff weight are selected and an estimation equation is presented by applying them to ADS-B information. The proposed estimation does not estimate the average takeoff weight but has the advantage of being able to estimate all ranges of the takeoff weight.