• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.661-669
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• 2007

Eyer since the Prandtl's experiment in 1934 and X-21 airjet test in 1950 both attempting to reduce drag, it was found that controlling the velocities of surface for extremely fast-moving object in the air through suction or injection was highly effective and active method. To obtain the right amount of suction or injection, however, repetitive trial-and error parameter test has been still used up to now. This study started from an attempt to decide optimal amount of suction and injection of incompressible Navier-Stokes by employing optimization techniques. However, optimization with traditional methods are very limited, especially when Reynolds number gets high and many unexpected variables emerges. In earlier study, we have proposed an algorithm to solve this problem by using step by step method in analysis and introducing SQP method in optimization. In this study, we propose more effective and robust algorithm and techniques in solving flow optimization problem.

• Investigative Magnetic Resonance Imaging
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• v.15 no.1
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• pp.41-47
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• 2011

Purpose : To evaluate the cause of internal jugular vein (IJV) obstruction on contrast enhanced 3D MR angiography (CE-MRA) using contrast enhanced computed tomography (CE-CT). Materials and Methods : A total number of 30 patients were enrolled, who underwent both head and neck CE-MRA and CE-CT from 2005 to 2008. We defined obstruction group which had IJV obstruction and control group which had no IJV obstruction on CE-MRA. The following parameters were measured from axial images of CE-CT: 1) diameter of IJV; 2) distance between the styloid process and ipsilateral lateral mass of the atlas; 3) maximum area of lateral mass of the atlas. Each parameter was compared between obstruction group and control group. Results : The diameter of IJV and distance between the styloid process and lateral mass of the atlas at IJV obstruction side in obstruction group were $1.6{\pm}1.0\;mm$ and $4.1{\pm}2.1\;mm$ respectively, which resulted in statistical significance (p<0.01). The maximum area of lateral mass of the atlas at IJV obstruction side in obstruction group was $103.4{\pm}25.3\;mm^2$ which is significantly larger than in control group (p<0.05). Conclusion : We found that the cause of IJV obstruction on CE-MRA could be narrow space between the styloid process and the lateral mass of the atlas, which was related with asymmetric larger area of lateral mass of atlas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.133-144
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• 2020

The purpose of this study was to examine the effects of an elderly people's health promotion program performed in a senior center located in J-si. Most interesting were the effects on the physical, physiological, and psychological parameters for senior center participation of the elderly. A nonequivalent control group pre-posttest design was employed. A total of 41 people living in J-si were assigned to either an experimental group (n=21) or control group (n=20). The experimental group was provided with the eight-week elderly people's health promotion program from May 1 to September 2 in 2019. The data were analyzed using SPSS/WIN 24.0 using descriptive statistics, 𝒙²-test, Fisher's exact test, and t-test. The results indicated a significant difference between the experimental group and control group with respect to the scores of the physical parameters, including right grip strength (t=-3.01, p=.004) and flexibility of the waist (t=-2.11, p=.09); the physiological parameters, including the systolic blood pressure (t=-3.02, p=.004); and psychological, including depression (t=2.42, p=.020), hopelessness (t=5.22, p<.001), and quality of life (t=4.28, p<.001). Therefore, the elderly people's health promotion program with senior center participation of the elderly is a useful nursing intervention program that can improve the right grip strength, flexibility waist, reduce the systolic blood pressure, depression and hopelessness, and improve the quality of life.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1255-1262
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• 2012

Look into the nuclear power plant of Wolsong currently, it is controlled in order to required operating pressure with PI controller. PI controller has a simple structure and satisfy design requirements to gain setting. However, It is difficult to control without changing the gain from produce changes in parameters such as loss of the valves and the pipes. To solve these problems, the dynamic change of the PI controller gain, or to compensate for the PI controller output is desirable to configure the controller. The aim of this research and development in the parameter variations can be controlled to a stable controller design which is reduced an error and a vibration. Proposed PI/NN control techniques is the PI controller and the neural network controller that combines a parallel and the neural network controller part is compensated output of the controller for changes in the parameters were designed to be robust. To directly evaluate the controller performance can be difficult to test in real processes to reflect the characteristics of the process. Therefore, we develope the simulator model using the real process data and simulation results when compared with the simulated process characteristics that showed changes in the parameters. As a result the PI/NN controller error and was confirmed to reduce vibrations.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.6
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• pp.64-72
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• 2010

In general, due to the interactions among subsystems, it is difficult to design an decentralized controller for nonlinear interconnected systems. In this study, the model of nonlinear interconnected systems is studied via decentralized fuzzy control method with time delay and polytopic uncertainty. First, the nonlinear interconnected system is represented by an equivalent Takagi-Sugeno type fuzzy model. And the represented model can be rewritten as Parameterized Linear Matrix Inequalities(PLMIs), that is, LMIs whose coefficients are functions of a parameter confined to a compact set. We show that the resulting fuzzy controller guarantees the asymptotic stability and disturbance attenuation of the closed-loop system in spite of controller gain variations within a resulted polytopic region by example and simulations.

• Clinical and Experimental Pediatrics
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• v.53 no.1
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• pp.41-47
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• 2010

Purpose : Adiponectin is an endogenous modulator of vascular remodeling that suppresses vascular inflammation. However, the role of adiponectin in Kawasaki disease (KD) has not been elucidated. The purpose of this study is to investigate the correlation between serum adiponectin level and several parameters, such as interleukin (IL)-6, tumor necrosis factor $(TNF)-{\alpha}$, lipid profile, and C reactive protein (CRP), and to clarify the association between adiponectin and cardiac function. Methods : Twenty-two KD patients (22 patients in acute phase and 20 patients in subacute phase) were enrolled in the study group. The control group consisted of 31 subjects (13 febrile patients and 18 healthy children). Both groups underwent blood sampling and tissue Doppler imaging (TDI). Results : CRP was significantly increased in the KD group compared with the control group. There were no significant differences in serum $TNF-{\alpha}$, IL-6, and adiponectin levels between groups. However, a negative correlation was found between adiponectin level and CRP level or platelet count. Systolic myocardial velocity and A myocardial velocity measured by TDI were decreased significantly in the acute KD group compared with the subacute KD group and control group. Positive correlations were found between adiponectin level and systolic myocardial velocity or A myocardial velocity. Conclusion : In acute KD patients, low adiponectin level was related to severe inflammatory reactions and decreased left ventricular functions.

• Smart Structures and Systems
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• v.26 no.5
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• pp.575-589
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• 2020

For vibration control of stay cables in cable-stayed bridges, viscous dampers are frequently used, and they are regularly installed between the cable and the bridge deck. In practice, neoprene rubber bushings (or of other types) are also widely installed inside the cable guide pipe, mainly for reducing the bending stresses of the cable near its anchorages. Therefore, it is important to understand the effect of the bushings on the performance of the external damper. Besides, for long cables, external dampers installed at a single position near a cable end can no longer provide enough damping due to the sag effect and the limited installation distance. It is thus of interest to improve cable damping by additionally installing dampers inside the guide pipe. This paper hence studies the combined effects of an external damper and an internal damper (which can also model the bushings) on a stay cable. The internal damper is assumed to be a High Damping Rubber (HDR) damper, and the external damper is considered to be a viscous damper with intrinsic stiffness, and the cable sag is also considered. Both the cases when the two dampers are installed close to one cable end and respectively close to the two cable ends are studied. Asymptotic design formulas are derived for both cases considering that the dampers are close to the cable ends. It is shown that when the two dampers are placed close to different cable ends, their combined damping effects are approximately the sum of their separate contributions, regardless of small cable sag and damper intrinsic stiffness. When the two dampers are installed close to the same end, maximum damping that can be achieved by the external damper is generally degraded, regardless of properties of the HDR damper. Field tests on an existing cable-stayed bridge have further validated the influence of the internal damper on the performance of the external damper. The results suggest that the HDR is optimally placed in the guide pipe of the cable-pylon anchorage when installing viscous dampers at one position is insufficient. When an HDR damper or the bushing has to be installed near the external damper, their combined damping effects need to be evaluated using the presented methods.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.7
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• pp.1032-1037
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• 2009

The present experiment was conducted to study the effects of partial replacement of spray-dried porcine protein (SDPP) or fish meal with soybean and shrimp protein hydrolysate (SSPH) on growth performance, nutrient digestibility and serum biochemical parameters in weaned pigs. Two hundred and forty 21${\pm}$2 d old pigs ((Pietrain${\times}$Duroc)${\times}$(Landrace${\times}$Large Yorkshire)) with initial weight of 6.9${\pm}$0.5 kg were randomly allocated to five dietary treatments with six replicates per treatment and eight piglets per replicate. The control diet (T1) contained 2% SDPP and 6% fishmeal, and SDPP for experimental diets T2 and T3 was replaced with 1% and 2% SSPH, respectively, on an iso-nitrogenous basis. The fishmeal for experimental diets T4 and T5 was replaced with 1% and 2% SSPH, respectively, also on an iso-nitrogenous basis. The experimental period was 21 days. The results showed that weaned piglets fed the diets containing 1% and 2% SSPH as a replacement for SDPP had similar average daily gain (ADG), average daily feed intake (ADFI), feed/gain (F/G), diarrhea rate and serum biochemical indices e.g. blood urea nitrogen (BUN), total serum protein (TP), albumin to globulin ratio (A/G), globulin (GLO), serum glucose (GLU), and immunoglobulin G (IgG) to those fed the control diet during 0-10 d and 0-21 d of the experiment. The substitution of 1% SSPH on an iso-nitrogenous basis for fish meal appeared to be beneficial for ADG (p = 0.59) and ADFI (p = 0.23) of piglets during the overall period. The digestibility of calcium was higher (p<0.01) in pigs fed diets containing SSPH than on the control diet. Addition of 1% SSPH on an iso-nitrogenous basis for fish meal could increase the digestibilities of dry matter and energy of the diet. Dietary replacement of fish meal with 1% and 2% SSPH had no effect on the concentrations of BUN, TP, A/G, GLO, GLU, and IgG. In conclusion, dietary SDPP or fish meal could partially replace SSPH without any adverse effect on growth performance, nutrient digestibility and serum biochemical parameters in weaned piglets.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.590-597
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• 1985

A recursive geometric adaptive control method to compensate for machining straightness error in the finished surface due to tool deflection and guideway error generated by end milling process is developed. The relationship between the tool deflection and the feedrate is modeled by a modified Taylor's tool life equation. Without a priori knowledge on the variations off cutting parameters, time varying parameters are then estimated by an exponentially windowed recursive least squares method with only post-process measurements of the straightness error. The location error is controlled by shifting the milling bed in the direction perpendicular to the finished surface and adding a certain amount of feedrate with respect to the tool deflection model before cutting. The waviness error is compensated by adjusting the feedrate during machining. Experimental results show that location error is controlled within a range of fixturing error of the bed on the guideway and that about 60% reduction in the waviness error can be achieved within a few steps of parameter adaption under wide operating ranges of cutting conditions even if the parameters do not converge to fixed values.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.9
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• pp.1719-1729
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• 1994

In this paper, an adaptive CAC(Connection Admission Control) method is proposed. The adaptive CAC uses traffic estimates derived from both traffic parameter specified by user and cell flow measurements. Traffic estimation using user-specified parameters is performed at every moment of connection request or connection release by recursive formula which makes real-time calculation possible. Traffic estimation using cell flow measurement is carried out when the number of connected calls does not change during a measurement reflection period-renewal period. The most import ant thing for the traffic estimation using cell flow measurement is the determination of the length of a renewal period to trace a real traffic flow with an allowable time lag and the measurement reflection ratio(MRR) both to reduce the portion of overestimation and to avoid underestimation of real traffic flow. To solve these problems, the adaptive CAC updates renewal period and MRR adaptively according to the number of connections and the elapsed time after last connection or release respectively. Performance analysis for the proposed method is evaluated in several aspects for the cases of both homogeneous and heterogeneous bursty traffic. Numerical examples show the adaptive CAC method has the better performance compared with conventional CAC method based on burst model from the both utilization and QOS point of view.