• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.878-888
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• 2016

Cogging torque has a negative impact on the operation of permanent magnet machines by increasing torque ripple, speed ripple, acoustic noise and vibration. In this paper Magnet Shifting Method has been used as a tool to reduce the cogging torque in inset Line Start Permanent Magnet Synchronous Motor (LSPMSM). It has been shown that Magnet Shifting Method can effectively eliminate several lower-order harmonics of cogging torque. In order to implement the method, first the expression of cogging torque is studied based on the Fourier analysis. An analytical expression is then introduced based on Permanent Magnet Shifting to reduce cogging torque of LSPMS motors. The method is applied to some existing machine designs and their performances are obtained using Finite Element Analysis (FEA). The effect of magnet shifting on pole mmf (magneto motive force) distribution in air gap is discussed. The side effects of magnet shifting on back-EMF, core losses and torque profile distortion are taken into account in this investigation. Finally the experimental results on two prototypes 24 slot 4 pole inset LSPMS motors have been used to validate the theoretical analysis.

• Journal of IKEEE
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• v.22 no.3
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• pp.759-766
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• 2018

This paper presents a high-speed axial-flux machine which utilizes the idea of sinusoidal shaped pole combined with a consequent iron-pole. The target of the proposed machine is the cost reduction of the relatively expensive Samarium-Cobalt (SmCo) permanent magnet (PM) material and the torque per PM volume improvement by using sinusoidal consequent-pole rotor. The effectiveness of the proposed machine is validated by comparing it with conventional consequent-pole and with conventional PM machines using 3-D finite element method (FEM) simulations. The comparison and analysis is done in terms of back electro-motive force (back-EMF) harmonic contents, torque per PM volume and torque ripple characteristics. The simulation results show that the proposed machine is suitable and cost-effective for high-speed and high torque per PM volume applications. Furthermore, due to the consequent pole, the magnetic flux saturation and the overload current torque-capability are also presented and discussed in the paper.

• Journal of Korean Physical Therapy Science
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• v.18 no.3
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• pp.63-69
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• 2011

Purpose : The purpose of study is activation of lumbar multifidus muscle by needle EMG during shoulder flexion in chronic low back pain patients. The subject were consisted of 10 women patients with chronic low back pain and healthy asymtomatic subject 10 women. Methods : 10 women patients with chronic low back pain and healthy asymptomatic subject 10 women is voluntary participated for the research. Subjects were positioned in standing. The needle EMG were measured activation of multifidus. Needle electrode was used to 28 gauge. The shoulder flexion movement used to activate the multifidus was then measured. Results : Results of the analysis showed that asymptomatic subjects had significantly larger multifidus muscle activation compared with CLBP subjects during shoulder flexion. Conclusion : This study will be used as multifidus measurement method of patient with chronic LBP. The multifidus muscle in chronic LBP patient clinical significance. Most of chronic LBP patients have multifidus contraction pattern. Therefore chronic LBP patients necessary multifidus activation measurement with needle EMG.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2208-2212
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• 2008

This paper deals with the cost reduction design of a single-phase line-start permanent magnet(LSPM) motor. Due to high cost of the permanent magnet(PM), cost reduction can be effectively achieved by reducing PM volume. Therefore, motor characteristics according to the PM volume are calculated by using d-q axis equivalent circuit analysis, and the characteristic map is made. In the characteristic map, maximum torque and efficiency are shown according to motor parameters such as back electromotive force(back emf) and inductances; back emf represents the PM volume. Minimum back emf and inductances satisfying output performance are determined in the characteristic map. Then, motor geometry based on the prototype motor is optimized to get the determined parameters using response surface methodology(RSM) and finite element method(FEM). Through the presented cost reduction design, total PM volume is reduced to 32% of prototype model.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.3
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• pp.349-361
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• 2008

The purpose of this study was to develop bodice basic patterns fitted on different body types of adult women. To meet this purpose, first, human bodies were measured using tight fitting technique and classified based on the shapes of upper trunk. The subjects were 214 women $20{\sim}39$ years of age. For the measurement of female upper trunk, tight fitting technique was utilized. The development of figures of upper trunks were obtained from women. These development of figures were then digitized and analysed using the PAD system. A total of 155 measurements were taken from each of the development of figures. then, 32 measurements were selected for the further analysis. As complimentary data, 22 direct body measurements using an anthropometric method and 23 body measurements using a photographic method from the side view pictures of the participants were also obtained. The results and discussions of this study are as follows: Using the body measurements from the development of figures, a factor analysis and a cluster analysis were conducted. As a result, the body types were classified into 5 different types, which differ in terms of bust volumes, shoulder slopes, shoulder tilts, back silhouettes, body axises. The prominent characteristics of each type are as follows: The first type has a large bust volume. The second type has a right figure. The third type has a rounded back silhouette. The fourth type has a back silhouette of scapular coming backward. Finally the fifth type has a shoulder tilted forward.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.121-129
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• 2008

study proposes a new key-segment closing method using thermal effect as a substitute to the process of set-back and reset-back for the FCM construction of a partially earth-anchored cable-stayed bridge. The proposed method is to artificially heat up the inside of girders located in the main span before closing the key-segment in a cantilever state. Then, the heat is removed after finishing the closure in a continuous bridge state. Using the changes in boundary conditions and structural systems, the proposed method can generate new member forces that reflect the advantage of the partially earth-anchored cable system. From the construction sequence analysis, it is found that the proposed method increases the efficiency of a partially earth-anchored cable-stayed bridge by reducing the compressive axial forces on the girders.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.319-322
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• 2003

For the analysis of leveling process by the 3-dimensional elastic-plastic finite element method, a finite element analysis program modeling large deformation of shell has been developed. This program fur analyzing large deformation of sheet during leveling includes spring-back analysis as well as efficient contact treatment between sheet and rolls of leveler. This is verified by the simple leveling experiment with 5 rolls at laboratory. Besides the leveling examples, problems within the category of large strain and rotation, such as 3-dimensional roll-up and gutter occurrence at continuous bending-unbending process are also tested for verification of the program. The residual curvatures of strip predicted by finite element analysis are within 20% error range of the experiment. The formation and direction of anticlastic curvature or gutter during bending-unbending under tension is predicted and this agrees with the experimental results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.3
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• pp.156-163
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• 2009

In this study, comparative analysis on the back-layer phenomena in the tunnel-fire driven flow is performed using numerical simulation with LES and RANS. FDS(Fire Dynamics Simulator) code is employed to calculate the fire-driven turbulent flow for LES and Smartfire code is used for RANS. Hwang and Wargo's data of scaling tunnel fire experiment are employed to compare with the present numerical simulation. The modeled tunnel is 5.4m(L) ${\times}$ 0.4m(W) ${\times}$ 0.3m(H). Heat Release Rate (HRR) of fire is 3.3kW and ventilation-velocity is 0.33m/s in the main stream. The various grid-distributions are systematically tested with FDS code to analyze the effects of grid size. The LES method with FDS provides an improved back-layer flow behavior in comparison with the RANS (${\kappa}-{\epsilon}$) method by Smartfire. The FDS solvers, however, overpredict the velocity in the center region of flow which is caused by the defects in the tunnel-entrance turbulence strength and in the near-wall turbulent flow in FDS code.

• The Korean Journal of Rehabilitation Nursing
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• v.18 no.1
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• pp.38-45
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• 2015

Purpose: This study was attempted in order to verify the effects of moxibustion on aged back pain and activities of daily living. Methods: A research design is quasi-experiment with pre-post test design in nonequivalent control group. As for data collection and experimental treatment, it accidentally sampled totally 50 people with 24 people for the experimental group and 26 people for the control group who appeal for chronic back pain aged over 60 who visited 4 senior centers where are located in N city from November 7, 2012 to December 3, 2012. Experimental treatment was carried out moxibustion totally 12 times by 3 times for 4 weeks in the experimental group. Data analysis was made by using SPSS program. As an analytical technique, the experimental group and the control group were analyzed the homogeneity verification with t-test, Fisher's exact test and $x^2$ test and the hypothesis verification with t-test. Results: The back pain level was reduced in the experimental group than the control group. The disability of daily living activities was reduced in the experimental group than in the control group. Conclusion: Moxibustion was considered to be likely useful therapeutic method for effects of chronic back pain and disability of daily living activities in aged.

• PNF and Movement
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• v.18 no.2
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• pp.223-231
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• 2020

Purpose: The purpose of the study was to compare the effects of different methods of pelvic control on abdominal muscle activity and lumbopelvic rotation angle during active straight leg raising (ASLR) in patients with chronic back pain. Methods: The study participants were patients with low back pain (n = 30). They were instructed to perform ASLR with pelvic control, ASLR with pelvic belt, and ASLR only. Surface electromyography data were collected from the ipsilateral rectus femoris (IRF), ipsilateral internal oblique (IIO), contralateral external oblique (CEO), and ipsilateral rectus abdominal (IRA) muscles, and lumbopelvic rotation angle was measured using a motion analysis device. Results: Activation of all abdominal muscles was greater in the ASLR with pelvic control group than in the ASLR with pelvic belt and ASLR groups. The lumbopelvic rotation angle was lower in the ASLR with pelvic control group than in the other two groups (p < 0.05). Conclusion: These results suggest that ALSR with pelvic control is an effective means of increasing abdominal muscle activity and reducing unwanted lumbopelvic rotation in patients with chronic low back pain. Controlling the pelvis using the opposite leg is an effective form of ASLR exercise for patients with chronic low back pain.