• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.107-115
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• 2001

It is required more precise analysis for practical load because of complexities and varieties of vehicle structure. To establish the numerical model, many researchers have been developed designing tools for linking F.E. Analysis results and experimental results. There studies have generally focused on each experimental method or analytical method separately. There are few studies based on both methods. This paper conceives new procedure for the determination of the load direction and magnitude applied on mechanical structures. New procedure is the combination of the analytical and empirical method with analyzed strain by F.E. Analysis under unit load and with measured principal stress by strain gages under driving load, respectively. In this paper, we theorize the procedure of practical load determination and make the validity and the practicality of the procedure with the application to T-shape jointed structure. F.E. Analysis is conducted to get the principal stress on arbitrary points in the F.E. model of T-shape joint under unit load. Then experiment is carried out to get the principal stress on the same points of F.E. model. To demonstrate the actual driving condition, the load conditions are bending and torsion. From these two data sets, the magnitude, the direction and the position of load can be obtained. Theory and practice do not always coincide; since there are some errors such as ill-poseness, measuring error and modeling error in experimental data, we examine the proper method of error minimization.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.6
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• pp.642-648
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• 2016

This paper deals with an analytical and experimental investigation to predict the axial thrust load that results from turbocharger operating conditions. The Axial forces acting on the turbocharger thrust bearing are caused by the unbalance between turbine wheel gas forces and compressor wheel air forces. It has a great influence on the friction losses, which reduces the efficiency and performance of high-speed turbocharger. This paper presents the calculation procedure for the axial thrust forces under operating conditions in a turbocharger. The first step is to determine the relationship between thrust forces and strains by experimental and numerical methods. The analysis results were verified by measuring the strains on a thrust bearing with the specially designed test device. And then, the operating strains and temperatures were measured to inversely calculate the thrust strains which were compensated the thermal effects. Therefore it's possible to calculate the magnitudes of the thrust forces under operating turbocharger by comparing the regenerated strains with the rig test results. It will possible to optimize the design of a thrust bearing for reducing the mechanical friction losses using the results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.22-30
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• 2006

In this paper, a systematic design method on an IPMC(ionic polymer-metal composite)-driven ZNMF(zero-net-mass-flux) pump is introduced for the flow control of an MAV's (micro air vehicle) wing. Since the IPMC is able to generate a large deformation under a low input voltage along with its ability to operate in air, and is easier to be manufactured in a small size, it is considered to be an ideal material of the actuating diaphragm. Through the numerical methods, an optimal shape of the IPMC　diaphragm was found for maximizing the stroke volume. Based on the optimal IPMC diaphragm, a proto-type ZNMF pump with a slot, was designed. By using the flight speed of the MAV considered in this work, the driving frequencies(~ 40 Hz) of IPMC diaphragm, and the flow velocity through the pump's slot, the calculated non-dimensional frequency and the momentum coefficient ensure the feasibility of the designed ZNMF pump as a flow control device.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.10
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• pp.859-867
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• 2015

This study proposes a robust formation flight control technique of multiple unmanned aerial vehicles(UAVs) using behavior-based decentralized approach. The behavior-based decentralized method has various advantages because it utilizes information of neighboring UAVs only instead of information of whole UAVs in the formation maneuvering. The controllers in this paper are divided into two methods: first one is based on position and velocity of neighboring UAVs, and the other one is based on position of neighboring UAVs and passivity technique. The proposed controllers assure uniformly ultimate boundedness of closed-loops system under time varying bounded disturbances. Numerical simulations are performed to validate the effectiveness of the proposed method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.848-857
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• 2011

Vision-based collision avoidance system for air traffic management requires a excellent multiple target detection algorithm under low signal-to-noise ratio (SNR) levels. The track-before-detect (TBD) approaches have significant applications such as detection of small and dim targets from an image sequence. In this paper, two detection algorithms with the TBD approaches are proposed to satisfy the multiple target detection requirements. The first algorithm, based on a dynamic programming approach, is designed to classify multiple targets by using a k-means clustering algorithm. In the second approach, a hidden Markov model (HMM) is slightly modified for detecting multiple targets sequentially. Both of the proposed approaches are used in numerical simulations with variations in target appearance properties to provide satisfactory performance as multiple target detection methods.

• The Korean Journal of Pain
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• v.10 no.2
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• pp.214-219
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• 1997

Background: Epidural neural blockade with local anesthetics combined with steroids has been in clinical trials for patients with low back pain. But pain treatment of low back pain remains somewhat problematic. Many patients with low back pain have epidural fibrosis and adhesions proved with magnetic resonance imaging(MRI) examination. These findings might play an important role in the origin of back pain. Present study was aims to investigate the effect of epidural adhesiolysis in patients with low back pain. Methods: We investigated 76 patients suspected with epidural fibrosis and adhesion was suspected. Nerve pathology was demonstrated and epidural fibrosis suspected or proved with MRI examination. 17G needle specially designed by Racz was inserted at sacral hiatus and catheter was inserted untill its tip was located at lesion site under fluoroscopic guidance. Injection of contrast dye was achieved and prospected spread of agents. Injection of 0.25% bupivacaine, triamcinolone, and 10% hypertonic saline via catheter were carried out daily for 3 days. Evaluation included assessment of pain relief (Numerical Rating Scale; NRS) post-epidural adhesiolysis 3 days, 1 week, and 3 months. We also looked for complication of epidural adhesiolysis. Results: Statistical analysis(Friedman nonparametric repeated measures test and Dune's multiple comparison test) demonstrated NRS was significantly less during 3 months after epidural adhesiolysis(P<0.05). Especially, there is a extremely significance in post-epidural adhesiolysis 3 days (P<0.001). Only four patients reported any complications the most common symptom among three persistent headache but disappeared after a few months without residual sequelae. Conclusion: We conclude epidural adhesiolysis is a safe and effective method of pain therapy for low back pain with proven lumbo-sacral fibrosis and adhesion. A direct visualization by epiduroscopy may be more useful to the resulting functional changes after epidural adhesiolysis.

• The Korean Journal of Pain
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• v.8 no.1
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• pp.37-42
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• 1995

The intermittent injection of analgesics is a inadquate method for postoperative pain control. Recently a non-electroic, disposable and portable infusor (Boxter Two Day $Infusor^R$) has been developed which can deliver analgesics with 2 ml/h speed continuousely. The present study examined the effects of three methods of pain management on recovery in 306 patients undergoing elective surgery in Wonkwang University Hospital. Group 1 (n=106) received i.m. $Valentac^R$ on a PRN basis. Group 2 (n=100), initial 2 mg of bolus morphine was followed by 48 mg of continuous infusion. Group 3 (n=100), initial 2 mg of morphine followed by morphine 18 mg-ketorolac 120 mg. We evaluated an analgesic efficacy with NRS (numerical rating scale) at 12, 24, 36, 48, 60 and 72 hours after the operation. The side effects (nausea, vomiting, pruritus, sedation and respiratory depression) were evaluated. In group 1, we asked major concern before operation and efficacy of pain control with pain severity (no pain, mild pain, moderate pain, sever pain). The results were as follows: 1) Major concern before operation is pain (40%). 2) 53% of patients suffered pain in group 1. 3) Morphine and morphine-ketorolac infusion groups were superior to the i. m. ($Valentac^R$) group with respect to postoperative analgesia. 4) In group 3 (morphine-ketorolac), there was no pruritus and mild nausea and vomiting.

• The Korean Journal of Pain
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• v.12 no.1
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• pp.54-58
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• 1999

Background: We studied 150 patients who received intravenous patient controlled analgesia (PCA) after total abdominal hysterectomy to evaluate pain relief, analgesic consumption, patient's satisfaction and side effects. Methods: We made total 40 ml of analgesic mixture with morphine 40 mg, ketorolac 120 mg, droperidol 3 mg and normal saline. Loading/bolus/basal infusion dose and lockout interval was 2 ml, 1.5 ml, 0.5 ml/hr and 10 min, respectively. Numerical rating scale (NRS) pain score, cumulative analgesic consumption, degree of satisfaction, and incidence of side effects were evaluated. Also, correlation of age and edu ion with analgesic consumption were evaluated. Results: The average pain scores using NRS were $3.1{\pm}1.7$ (6 h), $2.1{\pm}1.5$ (24 h), $1.7{\pm}1.5$ (48 h). The average cumulative analgesic consumption were $11.7{\pm}5.0$ ml (6 h), $23.0{\pm}6.7$ ml (24 h), $32.1{\pm}3.7$ ml (48 h). The degree of satisfaction in postoperative pain control was good in 94% of patients. There was no correlation between degree of satisfaction and analgesic consumption. Also age and level of edu ion did not correlated with analgesic consumption. Conclusions: Intravenous PCA with morphine, ketorolac, and droperidol is an effective method of postoperative pain control because it provides adequate pain relief and a few side effects with high patient's satisfaction. However, age and level of education did not correlated with analgesic consumption.

• Explosives and Blasting
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• v.27 no.2
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• pp.12-18
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• 2009

Recently, several cases of destruction of old cylindrical silos by explosive demolition method have been reported. This study deals with the subject concerning the pre-weakening of a cylindrical concrete silo for the application of overturning explosive demolition method. In the past, the pre-weakening operation of structure in explosive demolition has been done by use of some empirical methods. These empirical approaches, however, have possibilities of unexpected accidents. In order to provide a guideline for the pre-weakening of cylindrical silos and similar structures, this paper shows the result of a case study, in which the instability of a silo due to pre-weakening is investigated by a numerical structural analysis before actually conducting pre-weakening and demolition operations.

• Journal of the Korean Society of Food Culture
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• v.28 no.5
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• pp.512-524
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• 2013

The purpose of this study was to investigate the antioxidative effects of Mori Cortex Radicis powder and to determine the optimal mixing ratio of Mori Cortex Radicis powder and water in the preparation of bread. The optimal sensory composite recipe was determined by producing bread with different levels of Mori Cortex Radicis powder and water. The analysis was performed using response surface methodology and a sensory evaluation was performed with the data. Ten experimental recipes, including two with reference points in the composition, were selected. In terms of the antioxidative effects of Mori Cortex Radicis powder, the $IC_{50}$ for total phenolic content and DPPH free radical scavenging activity were 149.56 GAE/g dry powder and 137.77 /mL respectively. Measurement results of the mechanical properties showed differences in volume (p<0.05), baking loss (p<0.05), yellowness (p<0.01), lightness (p<0.01), redness (p<0.01), hardness (p<0.01) and springiness (p<0.05). The sensory measurements showed significant values for color (p<0.05), appearance (p<0.05), flavor (p<0.01), taste (p<0.01), and overall quality (p<0.01). Overall, based on numerical and graphical methods, the optimal formulation was determined to be 21.16 g of Mori Cortex Radicis powder and 372.47 g of water.