• Journal of Korea Water Resources Association
• /
• v.36 no.2
• /
• pp.223-235
• /
• 2003

An indirect or supplementary approach is proposed for determining the parameters of the Clark's model in order to improve existing defect in estimating the parameters. The gamma-distribution type function is employed to represent the Clark's model, which takes the same form as the Nash's model, so that parameter estimation is not difficult since it can be performed with a simple optimization process. Analytic forms of Clark's models parameters are introduced using parameters of the proposed methodology to give traditional form of Clark's. An application to a watershed has shown that the proposed approach can preserve the properties of observed data. Based the application, the new approach is recommended as an alternative to the existing parameter estimating methodology.

• Steel and Composite Structures
• /
• v.37 no.6
• /
• pp.695-709
• /
• 2020

The buckling properties of a single-layered graphene sheet (SLGS) are examined using nonlocal integral first shear deformation theory (FSDT) by incorporating the influence of visco-Pasternak's medium. This model contains only four variables, which is even less than the conventional FSDT. The visco-Pasternak's medium is introduced by considering the damping influence to the conventional foundation model which modeled by the linear Winkler's coefficient and Pasternak's (shear) foundation coefficient. The nanoplate under consideration is subjected to compressive in- plane edge loads per unit length. The impacts of many parameters such as scale parameter, aspect ratio, the visco-Pasternak's coefficients, damping parameter, and mode numbers on the stability investigation of the SLGSs are examined in detail. The obtained results are compared with the corresponding available in the literature.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.7 no.2
• /
• pp.41-50
• /
• 1993

This paper describes an effort to develop a microcomputer-based parameter identification system for three phase and two phase brushless DC motor. Back EMF equation is derived from back EMF waveform of three phase and two phase brushless DC motor. In this paper, a new identification algorithm for the brushless DC motor parameters by Pasek's technique is developed. It is found that Pasek's equation is valid for the brushless DC motor, too. The results obtained clearly shows that it is possible to implement the identification system for the determination of the brushless DC motor parameters. To minimize errors due to the ripple component in the measured armature current, digital averaging firis employed. The whole identification process of signal generation, measuring, parameter determination is fully automated. The use of the propod method in the parameter identifition system shows that the averaged current curve is in excellent agreement with the estimated current curve. Therefore, this close agreement confirms the validity of this technique.

• Journal of dental hygiene science
• /
• v.18 no.2
• /
• pp.130-135
• /
• 2018

The aim of this study was to investigate the role of osteal macrophages (osteomac) and osteocytes in bone remodeling using a mathematical model. We constructed the bone system with pre-osteoblasts, osteoclasts, osteocytes, and osteomac. Each link of the parameters and ordinary differential equations followed the Graham's model in 2013 except for the parameters of osteomac signaling and osteocytes signaling to link preosteoblasts and osteoblasts. We simulated the changes in each cell and bone volume according to the changes in the parameters of osteomac signaling and osteocytes signaling. The results showed bone volume was unstable and decreased gradually when the effectiveness of osteocytes and osteomac dropped below a certain level. When the parameters of osteomac signaling and osteocytes signaling to link preosteoblasts and osteoblasts had a value less than 1, bone volume increased with the increase in the parameter of osteomac signaling to link preosteoblasts and osteoblasts. Moreover, although the parameter of osteocytes signaling to link preosteoblasts and osteoblasts, increased in case of a small parameter of osteomac signaling, bone volulme decreased. If the parameters of osteomac signaling to link preosteoblasts and osteoblasts were over a certain level, bone volume was positively maintained, despite the parameter of osteocyte signaling to link preosteoblasts and osteoblasts. We suggested the osteomac may affect bone remodeling and may play an important role in bone cell network.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.7
• /
• pp.90-103
• /
• 1999

In this paper, we present an overall algorithm for real-time camera parameter extraction which is one of key elements in implementing virtual studio. The prevailing mechanical methode for tracking cameras have several disadvantage such as the price, calibration with the camera and operability. To overcome these disadvantages we calculate camera parameters directly from the input image using computer-vision technique. When using zoom lenses, it requires real time calculation of lens distortion. But in Tsai algorithm, adopted for camera calibration, it can be calculated through nonlinear optimization in triple parameter space, which usually takes long computation time. We proposed a new method, separating lens distortion parameter from the other two parameters, so that it is reduced to nonlinear optimization in one parameter space, which can be computed fast enough for real time application.

• The Korean Journal of Pain
• /
• v.33 no.1
• /
• pp.60-65
• /
• 2020

Background: Anatomic changes in the acromion have been considered a main cause of shoulder impingement syndrome (SIS). To evaluate the relationship between SIS and the acromion process, we devised a new morphological parameter called the acromion process cross-sectional area (APA). We hypothesized that the APA could be an important morphologic diagnostic parameter in SIS. Methods: We collected APA data from 95 patients with SIS and 126 control subjects who underwent shoulder magnetic resonance imaging (MRI). Then we measured the maximal cross-sectional area of the bone margin of the acromion process on MRI scans. Results: The mean of APAs were 136.50 ± 21.75 ㎟ in the male control group and 202.91 ± 31.78 ㎟ in the male SIS group; SIS patients had significantly greater APAs (P < 0.001). The average of APAs were 105.38 ± 19.07 ㎟ in the female control group and 147.62 ± 22.90 ㎟ in the female SIS group, and the SIS patients had significantly greater APAs (P < 0.001). The optimal APA cut-off in the male group was 165.14 ㎟ with 90.2% sensitivity, 91.4% specificity, and an area under the curve (AUC) of 0.968. In the female group, the optimal cut-off was 122.50 ㎟ with 85.2% sensitivity, 84.9% specificity, and an AUC of 0.928. Conclusions: The newly devised APA is a sensitive parameter for assessing SIS; greater APA is associated with a higher possibility of SIS. We think that this result will be helpful for the diagnosis of SIS.

• The Korean Journal of Applied Statistics
• /
• v.29 no.4
• /
• pp.741-752
• /
• 2016

Numerous studies have shown that normal inverse Gaussian (NIG) distribution adequately fits the empirical return distribution of financial securities. The estimation of parameters can also be done relatively easily, which makes the NIG distribution more useful in financial markets. The maximum likelihood estimation and the method of moments estimation are easy to implement; however, we may encounter a problem in practice when a relationship among the moments is violated. In this paper, we investigate this problem in the parameter estimation and try to find a simple solution through simulations. We examine the effect of our adjusted estimation method with real data: daily log returns of KOSPI, S&P500, FTSE and HANG SENG. We also checked the performance of our method by computing the value at risk of daily log return data. The results show that our method improves the stability of parameter estimation, while it retains a comparable performance in goodness-of-fit.

• Current Optics and Photonics
• /
• v.6 no.5
• /
• pp.445-452
• /
• 2022

We developed an adaptive optics test bench using an optical simulator and two rotating phase plates that mimicked the atmospheric turbulence at Bohyunsan Observatory. The observatory was reported to have a Fried parameter with a mean value of 85 mm and standard deviation of 13 mm, often expressed as 85 ± 13 mm. First, we fabricated several phase plates to generate realistic atmospheric-like turbulence. Then, we selected a pair from among the fabricated phase plates to emulate the atmospheric turbulence at the site. The result was 83 ± 11 mm. To address dynamic behavior, we emulated the atmospheric disturbance produced by a wind flow of 8.3 m/s by controlling the rotational speed of the phase plates. Finally, we investigated how closely the atmospheric disturbance simulation emulated reality with an investigation of the measurements on the optical table. The verification confirmed that the simulator showed a Fried parameter of 87 ± 15 mm as designed, but a little slower wind velocity (7.5 ± 2.5 m/s) than expected. This was because of the nonlinear motion of the phase plates. In conclusion, we successfully mimicked the atmospheric disturbance of Bohyunsan Observatory with an error of less than 10% in terms of Fried parameter and wind velocity.

• Elastomers and Composites
• /
• v.58 no.4
• /
• pp.179-190
• /
• 2023

The effect of the particle size and silica structure on the wear behavior of Silica/Styrene-Butadiene Rubber (SBR) compounds was investigated using a blade-type abrader and the findings were compared with those obtained with an Akron abrader. The compensated characteristic parameter (Ψ_c), which was the contributory factor of the combined effect of the particle size and filler structure, was introduced. This parameter was found to exhibit a linear relationship with the Young's modulus. The Young's modulus correlated more with Ψ_c than the uncompensated characteristic parameter (Ψ) modeled for carbon black. The wear rate and volume loss measured using a blade-type abrader and Akron abrader were respectively observed to be inversely proportional to Ψ_c, that is, the wear resistance of Silica/SBR compound improved as the particle size became smaller and the silica structure became intricate. The coefficient of determination (R²) obtained from the linear relationship between Ψ_c and wear rate was higher than those between Ψ_c and volume loss for the Silica/SBR compound. Thus, the blade-type abrader exhibited high potential to be used for accurately evaluating the effect of particle size and structural properties of silica on the wear behavior of SBR compounds.

• Korean Journal of Acupuncture
• /
• v.29 no.2
• /
• pp.200-215
• /
• 2012

Objectives : The purpose of this study is to investigate the differences of pulse wave parameter between the non delivery group (single women with no childbirth experience) and the delivery group (married women who gave birth(s) in delivery). Methods : Sixty one healthy (non delivery) nulliparous women and fifty three delivery women participated in this study. We used 3 dimensional pulse analyser(3D MAC, DAEYOMEDI co., Korea), which measures radial pulse waveform non-invasively by way of tonometry method at 5 different applied pressure levels. From 114 subjects enrolled, pulse wave parameters were measured on the six locations of Chon, Kwan and Cheok of each hands. Results : Delivery group's pulse showed larger values in the following pulse wave parameters (Energy, Ap, RAI, As, Aw, h1, h2, h4, h4/h1, t, t1, t2, t4, Wm, Wm/t). Non delivery group's pulse indicated larger values in the pulse wave parameters such as Energy of left Chon, difference pulse energy between left and right hand, Ad, h5, h5/h1, t5. Conclusions : According to the analysis result, delivery group's pulse has bigger values in most part of pulse wave parameters, especially in Kwan and Cheok which correspond to Liver, Kidney, and Myeong-mun. We interpret these results that delivery women are more mature and stable in reproductive organs than non delivery group, as they have experienced delivery(deliveries) and child-caring through married life.