• 제목/요약/키워드: Variable Rate

검색결과 2,776건 처리시간 0.032초

한국형 공중 시뮬레이터 항공기 연구 (Study on Korean In-Flight Simulator Aircraft)

  • 고준수;안종민;박성수
    • 한국군사과학기술학회지
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    • 제14권6호
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    • pp.1026-1030
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    • 2011
  • This paper presented here contains development of variable stability system(VSS) control laws for the KIFS (Korean In-Flight Simulator) aircraft to simulate the dynamics of F-16 aircraft. Development of VSS Control law for pitch rate, roll rate, yaw rate simulation for three specified flight conditions using Model Following Technique with rate feedback autopilot for stability provision. The direct lift force controller was also added to the developed VSS control law to simulate the pitch rate and normal g-load simultaneously. The simulation results show high accuracy of F-16 aircraft's pitch, roll, yaw rate and g-load simulation.

샘플링율이 맥박변이도 시간 및 주파수 영역 분석에 미치는 영향 (An Effect of Sampling Rate to the Time and Frequency Domain Analysis of Pulse Rate Variability)

  • 양윤라;신항식
    • 전기학회논문지
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    • 제65권7호
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    • pp.1247-1251
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    • 2016
  • This study aims to investigate the effect of sampling frequency to the time domain and frequency domain analysis of pulse rate variability (PRV). Typical time domain variables - AVNN, SDNN, SDSD, RMSSD, NN50 count and pNN50 - and frequency domain variables - VLF, LF, HF, LF/HF, Total Power, nLF and nHF - were derived from 7 down-sampled (250 Hz, 100 Hz, 50 Hz, 25 Hz, 20 Hz, 15 Hz, 10 Hz) PRVs and compared with the result of heart rate variability of 10 kHz-sampled electrocardiogram. Result showed that every variable of time domain analysis of PRV was significant at 25 Hz or higher sampling frequency. Also, in frequency domain analysis, every variable of PRV was significant at 15 Hz or higher sampling frequency.

리버스 무단 댐퍼용 연속가변밸브의 튜닝 파라미터에 관한 연구 (A Study on the Tuning Parameter of Continuous Variable Valve for Reverse Continuous Damper)

  • 윤영환;최명진;유송민
    • 한국자동차공학회논문집
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    • 제10권3호
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    • pp.192-200
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    • 2002
  • Semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspensions for passenger cars. In this study, a continuous variable damper for a passenger car suspension is developed, which is controlled actively and exhibits high performance with light weight, low cost, and low energy consumption. To get fast response of the damper, reverse damping mechanism is adapted, and to get small pressure change rate after blow-off, a pilot controlled proportional valve is designed and analyzed. The reverse continuous variable damper is designed as a HS-SH damper that offers good body control with reduced transferred input force from tire, compared with any other type of suspension system. The damper structure is designed, so that rebound and compression damping force can be tuned independently, of which variable valve is placed externally. The rate of pressure change with respect to the flow rate after blow-off becomes smooth when the fixed orifice size increases, which means that the blow-off slope is controllable using the fixed orifice size. The damping force variance is wide and continuous, and is controlled by the spool opening, of which scheme is usually adapted in proportional valves. The reverse continuous variable damper developed in this study is expected to be utilized in the semi-active suspension systems in passenger cars after its performance and simplicity of the design is confirmed through real car test.

DEVELOPMENT OF A REVERSE CONTINUOUS VARIABLE DAMPER FOR SEMI-ACTIVE SUSPENSION

  • Yoon, Young-Hwan;Choi, Myung-Jin;Kim, Kyung-Hoon
    • International Journal of Automotive Technology
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    • 제3권1호
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    • pp.27-32
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    • 2002
  • Semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspensions fur passenger cars. In this study, a continuous variable damper for a passenger car suspension is developed. It is controlled actively and exhibits high performance with light weight, low cost, and low energy consumption. To get fast response of the damper, reverse damping mechanism is adapted, and to get small pressure change rate after blow-off, a pilot controlled proportional valve is designed and analyzed. The reverse continuous variable damper is designed as a HS-SH damper which offers good body control with reduced transferred input force from tire, compared with any other type of suspension system. The damper structure is designed, so that rebound and compression damping force can be tuned independently, of which variable valve is placed externally. The rate of pressure change with respect to the flow rate after blow-offbecomes smooth when the fixed orifice size increases. Damping forces are measured with the change of the solenoid current at the different piston velocities to confirm the maximum hysteresis of 20N, linearity, and variance of damping farce. The damping farce variance is wide and continuous, and is controlled by the spoof opening, of which scheme is usually adapted in proportional valves. The reverse continuous variable damper developed in this study is expected to be utilized in the semi-active suspension systems in passenger cars after its performance and simplicity of the design is confirmed through real car test.

중국 해양오염의 증대가 중국 수산물 수출에 미치는 영향에 관한 연구 (A Study on the Effect of Chinese Marine Pollution on Chinese Fisheries Export)

  • 임설매;김기수
    • 수산경영론집
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    • 제46권1호
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    • pp.75-91
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    • 2015
  • With the increasing improvement of living standard, people pay more attention to the quality and security of their food. There is an increase in the consumption of aquatic products and a vast prospect of its trade. Fisheries as a major one of the traditional industries in China have significant price advantages and natural resources. However, marine pollution in China is more and more serious and the expecting of aquatic products has been seriously influenced by green barriers in the recent years. This paper tries to examine the effect of Chinese marine pollution on export of aquatic products in China. This paper utilizes cointegration test to estimate long-run equilibrium between marine pollution and fisheries products export. The results indicate that real exchange rate and income variable have positive effects and fish price has negative effect on China's fisheries export to Korea. However, marine pollution variable has no statistically significant effect on dependant variable. And according to the result of China's fisheries export to Japan, exchange rate has positive effect and both fish price and marine pollution variable have negative effects on export. Lastly, marine pollution and income level have effects on dependant variable in the case of Hong Kong, but exchange rate and price variable have no significant effect on aquatic products export from China to Hong Kong. In a word, marine pollution of China is a serious problem and it has negative effect on Chinese export of aquatic products.

STEADY NONLINEAR HYDROMAGNETIC FLOW OVER A STRETCHING SHEET WITH VARIABLE THICKNESS AND VARIABLE SURFACE TEMPERATURE

  • Anjali Devi, S.P.;Prakash, M.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • 제18권3호
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    • pp.245-256
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    • 2014
  • This work is focused on the boundary layer and heat transfer characteristics of hydromagnetic flow over a stretching sheet with variable thickness. Steady, two dimensional, nonlinear, laminar flow of an incompressible, viscous and electrically conducting fluid over a stretching sheet with variable thickness and power law velocity in the presence of variable magnetic field and variable temperature is considered. Governing equations of the problem are converted into ordinary differential equations utilizing similarity transformations. The resulting non-linear differential equations are solved numerically by utilizing Nachtsheim-Swigert shooting iterative scheme for satisfaction of asymptotic boundary conditions along with fourth order Runge-Kutta integration method. Numerical computations are carried out for various values of the physical parameters and the effects over the velocity and temperature are analyzed. Numerical values of dimensionless skin friction coefficient and non-dimensional rate of heat transfer are also obtained.

혈압 판별 분석 -위험요인을 중심으로- (The Discriminant Analysis of Blood Pressure - Including the Risk Factors -)

  • 오현수;서화숙
    • 대한간호학회지
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    • 제28권2호
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    • pp.256-269
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    • 1998
  • The purpose of this study was to evaluate the usefulness of variables which were known to be related to blood pressure for discriminating between hypertensive and normotensive groups. Variables were obesity, serum lipids, life style-related variables such as smoking, alcohol, exercise, and stress, and demographic variables such as age, economical status, and education. The data were collected from 400 male clients who visited one university hospital located in Incheon, Republic of Korea, from May 1996 to December 1996 for a regular physical examination. Variables which showed significance for discriminating systolic blood pressure in this study were age, serum lipids, education, HDL, exercise, total cholesterol, body fat percent, alcohol, stress, and smoking(in order of significance). By using the combination of these variables, the possibility of proper prediction for a high-systolic pressure group was 2%, predicting a normal-systolic pressure group was 70.3%, and total Hit Ratio was 70%. Variables which showed significance for discriminating diastolic blood pressure were exercise, triglyceride, alcohol, smoking, economical status, age, and BMI (in order of significance). By using the combination of these variables, the possibility of proper prediction for a high-diastolic pressure group was 71.2%, predicting a normal-diastolic pressure group was 71.3%, and total Hit Ratio was 71.3%. Multiple regression analysis was performed to examine the association of systolic blood pressure with life style-related variables after adjustment for obesity, serum lipids, and demographic variables. First, the effect of demographic variable alone on the systolic blood pressure was statistically significant (p=.000) and adjusted $R^2$was 0.09. Adding the variable obesity on demographic variables resulted in raising adjusted $R^2$to 0.11 (p=.000) : therefore, the contribution rate of obesity on the systolic blood pressure was 2.0%. On the next step, adding the variable serum lipids on the obesity and demographic variables resulted in raising adjusted R2 to 0.12(P=.000) : therefore, the contribution rate of serum lipid on the systolic pressure was 1.0%. Finally, adding life style-related variables on all other variables resulted in raising the adjusted $R^2$to 0.18(p=.000) ; therefore, the contribution rate of life style-related variables on the systolic blood pressure after adjustment for obesity, serum lipids, and demographic variables was 6.0%. Multiple regression analysis was also performed to examine the association of diastolic blood pressure with life style-related variables after adjustment for obesity, serum lipids, and demographic variables. First, the effect of demographic variable alone on the diastolic blood pressure was statistically significant (p=.01) and adjusted $R^2$was 0.03. Adding the variable obesity on demographic variables resulted in raising adjusted $R^2$to 0.06 (p=.000) ; therefore, the contribution rate of obesity on the diastolic blood pressure was 3.0%. On the next step, adding the variable serum lipids on the obesity and demographic variables resulted in raising the adjusted $R^2$ to 0.09(p=.000) ; therefore, the contribution rate of serum lipid on the diastolic pressure was 3.0%. Finally, adding life style-related variables on all other variables resulted in raising the adjusted $R^2$ to 0.12 (p=.000) : therefore, the contribution rate of life style-related variables on the systolic blood pressure after adjustment for obesity, serum lipids, and demographic variables was 3.0%.

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변동예금보험료율의 부과에 관한 실증연구 (An Empirical Study on the Variable Rate Deposit Insurance Premium in Korea)

  • 김대호
    • 재무관리연구
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    • 제20권1호
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    • pp.279-304
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    • 2003
  • 예금보험료는 각 금융기관의 위험정도에 상응해서 부과되어야 하지만 우리나라는 현재 금융 업종별로만 차등화되어 있고 같은 업종 금융기관간에는 동일 예금보험료율이 적용되고 있다. 고정예금 보험료율 부과방식에 비하여 변동예금 보험료율 부과방식은 논리적 타당성을 지니고 있지만 실제 적용가능한 객관적이고 측정이 용이한 기준마련이 어렵다. 본 연구에서는 옵션평가모형(option pricing model)을 이용하여 1995년부터 2001년까지 개별금융기관 및 전체 금융업종별로 예금보험료율을 추정하고 분석하였다. 금융업종별로 상호비교한 다음 연도별 추세분석과 분포분석을 하였다. 다음으로 추정 예금보험료율과 은행의 자본적정성, 수익성 및 자산건전성을 나타내는 관련 변수들과의 상관관계를 분석하였다. 연구 결과 개별 금융기관에 따라, 그리고 금융업종 및 표본기간에 따라 예금보험료율의 추정치가 상당한 차이를 보였다. 이는 금융업종에 따라 예금보험료율을 차등부과하고 개별은행의 위험을 반영하는 위험반영 차등 예금보험료율 제도의 타당성을 뒷받침한다고 할 수 있다. 은행보고자료와 감독기관의 검사자료가 지니고 있는 주관적 요소라는 단점을 극복하는 자료인 시장자료를 이용하는 본 연구의 추정결과는 예금보험료 부과에 보완적으로 사용할 수 있을 것이다.

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Estimating Exchange Rate Exposure over Various Return Horizons: Focusing on Major Countries in East Asia

  • Lee, Jeong Wook;Ahn, Sunghee;Kang, Sammo
    • East Asian Economic Review
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    • 제20권4호
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    • pp.469-491
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    • 2016
  • In this paper, we estimate the exchange rate exposure, indicating the effect of exchange rate movements on firm values, for a sample of 1,400 firms in seven East Asian countries. The exposure estimates based on various exchange rate variables, return horizons and a control variable are compared. A key result from our analysis is that the long term effect of exchange rate movements on firm values is greater than the short term effect. And we find very similar results from using other exchange rate variables such as the U.S. dollar exchange rate, etc. Second, we add exchange rate volatility as a control variable and find that the extent of exposure is not much changed. Third, we examine the changes in exposure to exchange rate volatility with an increase in return horizon. Consequently the ratio of firms with significant exposures increases with the return horizons. Interestingly, the increase of exposure with the return horizons is faster for exposure to volatility than for exposure to exchange rate itself. Taken as a whole, our findings suggest that the socalled "exposure puzzle" may be a matter of the methodology used to measure exposure.

속도 모드 양방향 원격 제어의 안정화 에너지 제한 방법의 실험 결과 (Experimental Results on the Energy-bounding Approach to Robustly Stable Rate-mode Bilateral Teleoperation Systems)

  • 박성준;서창훈;류제하
    • 제어로봇시스템학회논문지
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    • 제17권6호
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    • pp.552-557
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    • 2011
  • This paper presents experimental results on the energy-bounding approach to a rate-mode bilateral teleoperation control that can guarantee the robust system stability in variable time-delayed telecommunication environments. Previously, rate-mode energy bounding approach [15] was proposed and verified with experimental results using the simulated remote slave model. In this paper, a real experimental setup using an industrial robot (Denso) as a remote slave robot composed and conducted similar experiments with previous paper. In order to guarantee stability of the Denso when contacting with high impedance wall, velocity based impedance control modified by position based is used. Experimental results show that the rate-mode energy bounding approach can guarantee stable bilateral teleoperation system in the free and contact motion with variable time delay.