• Advances in aircraft and spacecraft science
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• v.3 no.4
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• pp.367-378
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• 2016

Thrust Vectoring is a dynamic feature that offers many benefits in terms of maneuverability and control effectiveness. Thrust vectoring capabilities make the satisfaction of take-off and landing requirements easier. Moreover, it can be a valuable control effector at low dynamic pressures, where traditional aerodynamic controls are less effective. A numerical investigation of Fluidic Thrust Vectoring (FTV) is completed to evaluate the use of fluidic injection to manipulate flow separation and cause thrust vectoring of the primary jet thrust. The methodology presented is general and can be used to study different techniques of fluidic thrust vectoring like shock-vector control, sonic-plane skewing and counterflow methods. For validation purposes the method will focus on the dual-throat nozzle concept. Internal nozzle performances and thrust vector angles were computed for several range of nozzle pressure ratios and fluidic injection flow rate. The numerical results obtained are compared with the analogues experimental data reported in the scientific literature. The model is integrated using a finite volume discretization of the compressible URANS equations coupled with a Spalart-Allmaras turbulence model. Second order accuracy in space and time is achieved using an ENO scheme.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.3
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• pp.29-35
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• 1997

The megastructure combined with the modular concept is an effcient structural system adequate for ultra-tail buildings for the future. An ingeneous structural control system can be developed by separating the internal subframe in one or many modules from the external megaframe, thus taking advantage of the effect of tuned mass dampers without adding any aditional mass. This so called mega-subcontrol system is generally modeled by a 20DF system for parametric study and for finding optimal values of the parameters. In this study the equation of motion for the system is obtained frist and the preconditions for the simplified modeling are investigated. Finally the optimal value for the subsreucture strffness is fomputed with given mass and damping ratios and transfer functions for responses are abtained for white noise ground exitation to verify the effectiveness of the mega-subcontrol system.

• Nuclear Engineering and Technology
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• v.50 no.4
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• pp.570-581
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• 2018

Recently, a software program has been used in nuclear power plants (NPPs) to digitalize many instrumentation and control systems. To guarantee NPP safety, the reliability of the software used in safetycritical instrumentation and control systems must be quantified and verified with proper test cases and test environment. In this study, a software testing method using a simulation-based software test bed is proposed. The test bed is developed by emulating the microprocessor architecture of the programmable logic controller used in NPP safety-critical applications and capturing its behavior at each machine instruction. The effectiveness of the proposed method is demonstrated via a case study. To represent the possible states of software input and the internal variables that contribute to generating a dedicated safety signal, the software test cases are developed in consideration of the digital characteristics of the target system and the plant dynamics. The method provides a practical way to conduct exhaustive software testing, which can prove the software to be error free and minimize the uncertainty in software reliability quantification. Compared with existing testing methods, it can effectively reduce the software testing effort by emulating the programmable logic controller behavior at the machine level.

• Journal of applied mathematics & informatics
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• v.40 no.1_2
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• pp.351-370
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• 2022

The design of mechanical structures aims to meet criteria, together with the safety of operators and lives in the vicinity of the equipment. Thus, there are several cases that meeting the desired specification causes the mechanical device to perform unstable and, sometimes, chaotic behavior. In these cases, control methods are applied in order to stabilize the device when in operation, aiming at the physical integrity of the component and the device operators. In this work, we will develop a study about the influence of a controller applied in a non-ideal capsule system operating with uncertain parameters, being non-existent in the literature. For this, two initial conditions were used: one that the capsule starts from rest and another that it is already in motion. Thus, the effectiveness of the controller can be assessed in both initial conditions, restricting the movement of the internal vibration-impact system to the capsule.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1103-1111
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• 2014

The results of control law design for a tilt-rotor unmanned aerial vehicle that has a nacelle mounted wing extension (WE) are presented in this paper. It consists of a control surface mixer, stability and control augmentation system (SCAS), hold mode for altitude / speed / heading, and a guidance mode for preprogram and point navigation which includes automatic take-off and landing. The conversion corridor and the control moments derivatives between the original tilt-rotor and its variant of the nacelle mounted WE were compared to show the effectiveness of the WE. The nacelle conversion of the original tilt-rotor starts when the airspeed is greater than 30 km/h but its WE variant starts at 0 km/h in order to reduce the drag caused by the high incidence angle of the WE. The stability margins of the inner loop are presented with the optimization approach. The outer loops for the hold mode are designed with trial and error methods with linear and nonlinear simulation. The main control parameter for altitude control of the helicopter mode is thrust command and it is transferred to the pitch attitude command in airplane mode. Otherwise, the control parameter for the speed of the helicopter mode is the pitch attitude command and it is transferred to the thrust command in airplane mode. Therefore the speed and altitude hold mode are coupled to each other and are engaged at the same time when an internal pilot engages any of the altitude or speed hold modes. The nonlinear simulation results of the guidance control for the preprogrammed mode and point navigation are also presented including automatic take-off and landing in order to prove the full control law.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.313-323
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• 2018

This study was conducted to develop an individualized upper extremity exercise program for patients after mastectomy and evaluate its effectiveness. A nonequivalent control-group pretest-posttest design was used for this investigation. Research participants were patients with breast cancer who underwent mastectomy at two university hospitals (experimental group, n=17; control group, n=16). The experimental group received an individualized upper extremity exercise program three times a week for 7 weeks. Data were analyzed by the ${\chi}^2-test$, Fisher's exact test, Mann-Whitney U-test and Wilcoxon Signed Rank test using SPSS WIN 21.0. Inter-group comparison revealed significant differences between pre-test and post-test in hands behind the back, flexion, abduction, external rotation, internal rotation, and grip strength. Moreover, the experimental group showed significant improvements in hands behind the back, flexion, abduction, external rotation, internal rotation, and grip strength relative to the control. In conclusion, the individualized upper extremity exercise program was shown to be an effective intervention to improve physical functions in upper limbs and shoulders. Therefore, this program should be applied to patients after mastectomy in clinics since many patients have suffered from decreased physical functions in upper extremities.

• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.185-196
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• 2007

The aim of this research is to develop a signal control algorithm using internal metering to minimize total delay that vehicles go through, in case a network is oversaturated. To calculate total delay on the network, the authors first detect vehicles' arrivals and departures in the network through the detecting system, and chase the vehicles' flow in the links with a platoon dispersion model. Following these, the authors calculate the queue length in all the inks of the network through the chase of vehicles, deduce the stopped time delay, and finally convert the stopped time delay to the approach delay with a time-space diagram. Based on this calculated delay, an algorithm that calculates the level of the internal metering necessary to minimize the deduced approach delay is suggested. To verify effectiveness of this suggested algorithm, the authors also conduct simulation with the micro-simulator VISSIM. The result of the simulation shows that the average delay per vehicle is 82.3 sec/veh and this delay is lower than COSMOS (89.9sec/veh) and TOD (99.1sec/veh). It is concluded that this new signal control algorithm suggested in this paper is more effective in controlling an oversaturated network.

• Journal of Korean Medicine for Obesity Research
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• v.15 no.1
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• pp.1-8
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• 2015

Objectives: The aim of this study was to evaluate the effectiveness and safety of electroacupuncture for non-alcoholic fatty liver disease (NAFLD). Methods: A randomized, controlled pilot trial was conducted. Twenty-two participants were randomized into one of the two groups: an acupuncture group (n=11) and wait-list group (n=11). The treatment group received 8 sessions of electroacupuncture over 8 weeks. Twenty points (CV4, CV12, both LR14, GB26, ST25, ST34, ST40, ST36, SP4, SP6, LR3) were selected for needling. The control group did not receive acupuncture treatment during study period and followup were done in the 4th and 8th weeks after randomization in both groups. The primary outcome was body fat computed tomography and the secondary outcomes included blood test (aspartate aminotransferase, alanine transferase, triglyceride, total cholesterol, high density lipoproteincholesterol, low density lipoprotein-cholesterol, blood sugar test, ${\gamma}$-guanosine triphosphate) and body composition test (body mass index, weight, body fat mass, body fat rate, waist hip ratio). Safety was assessed at every visit. Results: There was no significant differences in between the experimental group and control group. There were no adverse events. Conclusions: The results suggest that In patients with NAFLD, electroacupuncture treatment did not induce worsening of liver disease and liver function, but it was no improvement symptoms of fatty liver. Study of herb medicine treatments and other acupuncture therapy of NAFLD are required later.

• The Journal of Internal Korean Medicine
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• v.44 no.3
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• pp.485-505
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• 2023

Objective: The purpose of this study is to assess the effectiveness and safety of using Taeksa-tang for dyslipidemia through a systematic review and meta-analysis of randomized controlled trials (RCTs). Methods: The search was conducted using keywords such as "dyslipidemia", "hyperlipidemia", "taeksa tang", "zexie tang", and "takusha to" in 12 databases (Pubmed, Cochrane, Embase, ScienceDirect, CNKI, Wanfang, CiNii, RISS, KISS, ScienceON, OASIS, and DBpia) on April 13, 2023. There were no limits on the publication period and language. Cochrane's risk of bias (RoB) was used to evaluate the quality of the studies. A meta-analysis was conducted according to the outcome measurements such as total effective rate (TER), total cholesterol (TC), triglyceride (TG), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), and adverse effects, using the Review Manager web. Results: A total of 9 RCTs were selected. In evaluating the RoB, 2 studies mentioning the random sequence generation, 1 study conducting double blindness, and 8 studies without missing values were evaluated as low risk, while 1 study without mentioning the random sequence generation was evaluated as high risk. All other parts were evaluated as unclear risk. The treatment group (Taeksa-tang or Taeksa-tang-gagam) showed more statistically significant effects compared to the control group (Western medicine or Chinese patent medicine) in TER (RR : 1.24, 95% CI 1.15 to 1.34, P<0.00001), TC (MD : -1.12, 95% CI -1.68 to -0.56, P<0.0001), TG (MD : -1.08, 95% CI -1.65 to -0.51, P=0.0002), HDL-C (MD : 0.63, 95% CI 0.34 to 0.93, P<0.0001), LDL-C (MD : -0.81, 95% CI -1.10 to -0.53, P<0.00001). In addition, the treatment group showed lower adverse effects compared to the control group (RR : 0.30, 95% CI 0.12 to 0.74, P=0.008). Conclusion: This study suggests that Taeksa-tang is effective and safe to use for treating dyslipidemia. However, due to the low quality of the included studies, more clinical studies need to be conducted in the future to increase the possibility of clinical use.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.63-71
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• 2003

This paper presents a robust slewing control of a flexible space structure based on sliding surface design. A sliding surface is designed for a single-axis rest-to-rest slewing in view of target angle, target angular velocity, and root monent of the flexible appendage. In comparison with the Lypunov control law, both controllers guarantee the stability and command tracking capabilities for nominal system. It is also shown that the designed control law provides further robustness to internal/external uncertainties. Extending the results of a single-axis maneuver, a sliding mode control law was sought for an arbitrary three-axis maneuver. Quaternion was used to determine the attitude of a space structure and sliding surfaces were designed for each axis, thereby a robust control law was derived considering the coupling effects between each rotational axis during the maneuver. Several numerical examples were demonstrated to show the effectiveness of the designed control law.