• Journal of the Institute of Convergence Signal Processing
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• v.20 no.3
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• pp.171-176
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• 2019

Drones are highly utilized because they can efficiently acquire long-distance videos. In drone operation, the speed, which is the magnitude of the velocity, can be set, but the moving direction cannot be set, so accurate information about the drone's movement should be estimated. In this paper, we estimate the velocity of the drone moving at a constant speed and direction. In order to estimate the drone's velocity, the displacement of the target frame to minimize the sum of absolute difference (SAD) of the reference frame and the target frame is obtained. The ground truth of the drone's velocity is calculated using the position of a certain matching point over all frames. In the experiments, a video was obtained from the drone moving at a constant speed at a height of 150 meters. The root mean squared error (RMSE) of the estimated velocities in x and y directions and the RMSE of the speed were obtained showing the reliability of the proposed method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.4
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• pp.808-814
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• 2007

In this paper, the measurement system of crane moving range is concerned with range recognition technology using phase and magnitude of radio wave. By the proposed technology, we design the radio transmitter and receiver and realize the measurement system, and save the data in disk that is earned from 900Mhz RF signal, middle frequency 450khz of analog signal. As a result of RF measurement, we got 9.3 dBm of RF output and 96 dBc@10khz of phase noise. Range information is earned the data through digital signal processing of IF signal. For the estimation of range measured, we analyze the difference between real range and measurement range, and also suggest the method to remove the measurement error using average processing and amplitude properties. A result is 0.12 and 0.00422 deviation in l0mn-30m and within 5m respectively, and then 2.4E-04 deviation in 4m by using compensation of level characteristics lately.

• Korean Journal of Remote Sensing
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• v.15 no.1
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• pp.21-30
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• 1999

The CLW (Cloud Liquid Water) is a parameter of vital interest in both modeling and forecasting weather. In mesoscale models, the magnitude of latent heat effects corresponds to the amount of CLW, which is important in the development of a certain weather system. The goal of this study is the estimation of CLW by GMS-5 data which is compared with that of SSM/I data and GMR(Grounded Microwave Radiometer)data. First of all, we found out the relationship of cloud albedo to cloud thickness, and caculated the CLW using the result of the relationship. The CLW amount of SSM/I or GMR and that of GMS-5 were compared, respectively. The correlation coefficient was about 0.86 and RMSE was 9.23 mg/$cm^2$ between GMS-5 data and GMR data. And also the correlation coefficient was 0.84 and RMSE was 14.02 mg/$cm^2$ between GMS-5 data and SSM/I data.

• Journal of Korea Port Economic Association
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• v.38 no.4
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• pp.13-23
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• 2022

In this study, from January 2015 to April 2020, we propose a stochastic volatility model to capture the leverage effect on daily freight yields in the dry cargo market and analyze the freight yields. Estimation involving the Bayesian Markov Chain Monte Carlo method for the leverage effect based on the negative correlation that exists between returns and volatility in stochastic volatility analysis yields similar estimates, and the statistcs indicates significant. That is, the results of the empirical analysis show that the degree of correlation between returns and volatility, and the magnitude and sign of fluctuations differ, which suggests that taking into account the leverage effect in the SV model improves the goodness of fit of the estimates. In addition to the statistical significance of the estimated model's leverage effect, the analysis by log predictive power score presents the estimated results with improved predictive power of the model considering the leveraged effect. These astatistically significant empirical results show that the stochastic volatility model considering the leverage effect is important for freight rate risk modeling in the marine industry.

• Journal of Korean Physical Therapy Science
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• v.3 no.2
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• pp.1065-1077
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• 1996

Fees for medical insurance services in Korea has not being been set based on service costing. Recently in the USA, fees for physican services are determined by developing and applying Resoure Based Relative Value Scales (RBRVS). This study attempts to develop relative value scales for personal factors of rehabilitative and physical therapeutic services. The personal factors were classified into four categories as having been done in the USA;service time, treatment technology and physical efforts, mental efforts and judgement, and stress. Input factors were measured using Magnitude Estimation Method (MEM), and relative value units were calculated for each of twenty eight rehabilitative and physical therapeutic services. Results show that service time surveyed differs from that provided in the public fee schedules in 24 services; the three personal factors but the service time are highly correlated; the physical therapists hold treatment technology and physical efforts to be the most important factor in setting the for services; and that relative values developed for noninsurance services such as Silver Spike Electrode (SSP) and Proprioceptive Neuromuscular Facilitation (PNF) are higher than those of similar insurance services. The policy implications and measures for improvement for the above findings were suggested respectively.

• Journal of the Korean Society of Clothing and Textiles
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• v.24 no.4
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• pp.605-615
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• 2000

This study was carried out to investigate sound characteristics including sound parameters and subjective sensation, and primary hand values related with sound of fabrics for blouse, and furthermore to predict subjective sound sensation with mechanical properties and sound parameters. Sound of specimens was analyzed by FFT. Level pressure of total sound(LPT), loudness(Z), coefficients of autoregressive(AR) functions for fitting the spectra, and sound color factors(ΔL and Δf) were obtained as sound parameters. Primary hand values for women's thin dress were calculated by using KES-FB. Subjective sensation for sound including softness, loudness, sharpness, clearness, roughness, highness, and pleasantness was evaluated by free modulus magnitude estimation. The results were as follows; 1. Fabrics for blouse showed similar spectral shapes to one another in that amplitude values were lower in most ranges of frequencies than fabrics for other uses. 2. It was found that fabrics for blouse were less louder because LPT, loudness(Z), and ARC values were lower than other fabrics. 3. Primary hand values indicated that specimens were soft-touched, flexible, and less crisp. Among primary hands related with sound, Shari values were higher for silk fabrics than for synthetic ones, while the values for Kishimi were similar, 4. Fabrics for blouse were rated more highly for softness, clearness, and pleasantness than for loudness, sharpness. roughness, and highness. Silk fabrics were evaluated more pleasant than synthetic fabrics. 5. Subjective sensation for sound of blouse fabrics were predicted with mechanical properties and physical sound parameters.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.63-64
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• 2002

In a micro-scale contact, surface forces such as capillary force and van der Waals Interaction significantly Influence the contact between asperities of rough surfaces. Little is, however, known about the variation of these surface forces as a function of chemical property of the surface (hydrophilicity), relative humidity and deformation of asperities In the real area of contact. A better understanding of these surface forces is of great necessity in order to find an optimal solution for reducing friction and adhesion of micro surfaces. We proposed an effective method to analyze capillary and van der Waals forces In nano-scale contact. In this method, Winklerian foundation model was employed to analyze the contact of rough surfaces that were obtained from atomic force microscopy (AFM) height Images. Self-mated contact of diamond-like-carbon (DLC) coatings was analyzed, as an example, by the proposed model. It was shown that the capillary force was significantly influenced by relative humidify and wet angle of the DLC surface. The deformation of asperities to a critical magnitude by external loading led to a considerable increase of both capillary and van der Waals forces.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.491-496
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• 2010

The direct design modification of problematic component is disallowed in order to sacrifice other major factors such as a stability or a major performance. So, the best design policy is to risvise the immature structural medchanism under the minimal design change as soon as possible. For this paper presents a new design sensitivity analysis based on transmissibility rtio (TR) of response acceleration to find a proper candidate for the minimal design modification. The new sensitivity analysis is based on the fact that the sensitivity of TR over a small design change is inversly proportinal to the magnitude of TR. The theory of proposed design sensitivity analysis is simulated with the variance of TR over a dynamic change. Then, new methodology is appplied for a linear elastic specimen to detect the most sensitive node over a design change using measured accleration data during uni-axial vibration test, The physical verification of the sensitivity method is conducted on the CAE model of a linear elastic specimen by adding concentration mass and the vibration fatigue of the simple specimen is analyzed to estimate the relationship between fatigue behaviors and sensitivity consequences.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.10
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• pp.895-901
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• 2013

Last blades of LP turbine in nuclear power plant are the highly damaged part and suffered from nozzle steam impulses during the turbine operation. Nozzle impulse is known as a common cause of damage or failure in the turbine blade and results from steam flow distortions due to uneven steam flow patterns between the stationary blade vanes. If impulse force was continuously acting on the blade for a long time, crack or wear will occur in weak parts such as root. So, it is important to know variation of nozzle impulse during the blade moving. But there is no way to measure and estimate the magnitude and direction of nozzle impulse. Therefore, this study was performed to know the variation of nozzle impulse force according to the positions of the blade and to obtain blade equivalent force and torque. This results can be used for blade stress estimation.

• Journal of the Ergonomics Society of Korea
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• v.24 no.2
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• pp.51-56
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• 2005

Human perceptional speed is different from its real speed. There is lack of research that the perceptional speed is different from real speed in 2-dimension, because most research of speed perception has concentrated on points and lines. This research investigates the effects of object size on speed perception. In this research, we used 2-D circular objects of the different size, 0.9, 1.8 and $3.6^{\circ}$. The objects moved 9.0, 13.5 and $18.0^{\circ}$ with three different speeds, 6.0, 9.0 and $18.0^{\circ}$/s. Six participants were exposed to the environment with standard scene(size: $1.8^{\circ}$, speed: $9.0^{\circ}$/s and travel distance: $13.5^{\circ}$). After the first scene, another scene in which the object had changed to different sizes, speeds and distances, was shown to the participants. A magnitude estimation method was used to construct a scale of the perceived speed level. The relationship between the perceived and the actual speed level was explained by Stevens's power law that the value was 0.978 with the exponent of 0.992. The size of object had an effect on the speed perception but travel distance was not. The perceptional speed of bigger object was lower than of smaller object. It showed that the degrees of perceptional speed decreased as size of object increased.