• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.55 no.3
• /
• pp.133-140
• /
• 2006

This paper is proposed an efficiency optimization control algorithm for a synchronous reluctance motor(SynRM) which minimizes the copper and iron losses. Also, this paper presents a speed estimated control scheme of SynRM using artificial neural network(ANN). There exists a variety of combinations of d and q-axis current which provide a specific motor torque. The objective of the efficiency optimization controller is to seek a combination of d and q-axis current components, which provides minimum losses at a certain operating point in steady state. It is shown that the current components which directly govern the torque production have been very well regulated by the efficiency optimization control scheme. The proposed algorithm allows the electromagnetic losses in variable speed and torque drives to be reduced while keeping good torque control dynamics. The control performance of ANN is evaluated by analysis for various operating conditions. Analysis results are presented to show the validity of the proposed algorithm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.99-104
• /
• 2008

The Carbon fiber epoxy composite material and aluminum have many advantages about higher specific stiffness and good fatigue characteristics. basically, the propeller shaft of automobile must satisfy high natural frequency more than 9,200 rpm to satisfy high number of rotation and high torsion torque more than 2,700Nm. In these reason, studied natural frequency and torsion torque characteristics of shaft according to parameter variations with the outdiameter and thickness. From the torsion tester and natural frequency experiments FE analyses was compared vibration and torque characteristics of hybrid shaft Designed hybrid shaft was experimented through FFT analyzer and torsion tester each and satisfied that hybrid shaft reverence 60mm and thickness 5mm by a these experiment is most suitable. Therefore, that can manufacture existent steel two piece type propeller shaft to one piece type hybrid shaft.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.3
• /
• pp.274-281
• /
• 2009

The carbon fiber epoxy composite material and aluminum have many advantages over other materials because of their high specific stiffness and good fatigue characteristics. Basically, the propeller shaft of automobile requires bending frequency of higher than 2,700 Nm and high natural frequency of higher than 9,200 rpm occurred by fast revolution. For this reason, natural frequency and torsion torque characteristics of hybrid shaft was studied in variation of its outer-diameter and thickness. Vibration and torque characteristics of hybrid shaft were compared by torsion tester, natural frequency experiments and FE analysis. Designed hybrid shaft satisfied its vibration and torque characteristics when its outer-diameter was 60 mm and thickness was 5 mm. Therefore, hybrid material enables to manufacture one piece structure hybrid propeller shaft rather than current two piece structure.

• International Journal of Aeronautical and Space Sciences
• /
• v.6 no.1
• /
• pp.89-96
• /
• 2005

Ducted fans have advantages in noise as well as operational safety aspects compared to conventional tail rotors and are used as an anti-torque system for various classes of helicopters. The final goal of this study is to develop a ducted fan anti-torque system which can replace conventional tail rotors of existing helicopters to achieve safety enhancement and low noise level. In this paper, a conceptual design process and the results are described. Initially, the design requirement and the design parameter characteristics are analysed, and then initial sizing and configuration design are performed. There are several configuration changes due to specific technical reasons in each case. Finally, the required power and the pitch link load are predicted as an initial estimation. The conceptual design technique for the ducted fan in this study can be easily applied to the design of other ducted fans such as the lift fan for unmanned aerial vehicle.

• Journal of Biosystems Engineering
• /
• v.29 no.5 s.106
• /
• pp.419-424
• /
• 2004

In this study, a series of soil bin experiment was carried out to investigate experimentally the effect of the tire inflation pressure and axle load of tire on the steering torque for the off-road condition. The experiment was performed at the three levels of off-road conditions(ground I, ground II and ground III) and on-road condition(ground IV), four levels of tire inflation pressure(120 kPa, 170 kPa, 220 kPa and 270 kPa), and four levels of axle load(1470N, 1960N, 2450N and 2940N). The results of this study are summarized as follows: 1. Steering torque at the off-road conditions were higher than that on the on-road conditions for all levels of tire inflation pressure and axle load. 2. As the axle load increased, steering torque also increased f3r all experimental ground conditions. 3. For the axle load of 1470N the biggest steering torque was measured on the ground condition I, but as the axle load increased to the value of 2940N the biggest steering torque was measured on the ground condition III. From the above results, it was found that for the low axle load, steering torque gets higher on the soft ground condition, but for the high axle load, steering torque gets higher on hard ground condition for whole range of experimental conditions. 4. As the tire inflation pressure decreased, steering torque increased on the on-road condition, but no specific trend was not found at the off-road conditions.

• The korean journal of orthodontics
• /
• v.31 no.3 s.86
• /
• pp.335-346
• /
• 2001

The purpose of this study was to investigate the ideal clinical torque(In the SWA rectangular wire, the torque by the angle between the plane part and twisted part to move the tooth) of the orthodontic rectangular wire which produce the proper labiolingual movement of the single tooth during finishing stage of the orthodontic treatment. The clinical torque is the sum of the play and the active torque which generates the moment at the bracket. The play is calculated by the formula and the active torque is calculated by the computer aided three-dimensional finite element method. The finite element model was consist of the three brackets which formed a row and 3 kinds of orthodontic rectangular wire(stainless steel, TMA, NiTi) which inserted in brackets. Both sides of the model were twisted and the moment generated in the center bracket was calculated. The sizes of seven wires which were used commonly were .016'X.022', .017'X.022', .017'X.025', .018'X.025', .019'X.025', .020'X.025', .021'X.025'. In 018' bracket, 016'X.022', .017'X.022', .017'X.025' wires were inserted and in 022' bracket, all the sizes of wires except .016'X.022' were inserted and tested. The following conclusions could be drawn from this study. 1. The moments generated on the same size of the wires by the same active torque were equal regardless of the bracket slot size. 2. The moments were increased with the size of the wires. The moment generated on the .021'X.025' wire was about 1.75 times as large as that on the .016'X.022' wire regardless of the material. 3. The moments were increased in the order of the NiTi, TMA stainless steel. The moment of the TMA wire was 0.35 times as small as that of the stainless steel wire and the moment of the NiTi was0.16 times as small as that of the stainless steel wire. 4. The moment was decreased as the interbracket distance was increased. 5. To get a desired moment with the specific size and material of the wire on the specific bracket slot, the formula and the results were displayed.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.04a
• /
• pp.149-153
• /
• 2000

Substituting composite structures for conventional metallic structures has many advantages because of higher specific stiffness and specific strength of composite materials. In this work, one-piece propeller shafts composed of carbonfepoxy and glass/epoxy composites were designed and manufactured for a rear wheel drive automobile satisfying three design specifications, such as static torque transmission capability, torsional buckling and the fundamental natural bending frequency. Single lap adhesively bonded joint was employed to join the composite shaft and the aluminum yoke. For the optimal adhesive joining of the composite propeller shaft to the aluminum yoke, the torque transmission capability of the adhesively bonded composite shaft was calculated with respect to bonding length and yoke thickness by finite element method and compared with the experimental result. Then an optimal design method was proposed based on the failure model which incorporated the nonlinear mechanical behavior of aluminum yoke and epoxy adhesive. From the experiments and FEM analyses, it was found that the static torque transmission capability of composite propeller shaft was maximum at the critical yoke thickness, and it saturated beyond the critical length. Also, it was found that the one-piece composite propeller shaft had 40% weight saving effect compared with a two-piece steel propeller shaft.

• Korean Journal of Applied Biomechanics
• /
• v.25 no.3
• /
• pp.275-281
• /
• 2015

Objective : In order for Taekwondo athletes to perform destructive kicking performance, they are expected to have Taekwondo-specific muscle properties such as high muscle strength and power. The purpose of this study was to investigate the joint angle-dependent force-producing property of Taekwondo athletes' knee extensor muscles, which is one of the primary muscle groups involved in kicking performance. Method : Ten Taekwondo male athletes (age: $19.9{\pm}0.7yrs$, height: $180.6{\pm}6.2cm$, body mass: $75.9{\pm}8.9kg$, career: $9.2{\pm}2.9yrs$.) and 10 healthy male non-athletes (age: $26.3{\pm}2.6yrs$, height: $174.2{\pm}4.8cm$, body mass: $72.8{\pm}7.7kg$) participated in this study. Subjects performed maximum isometric knee extension at knee joint angles of $40^{\circ}$, $60^{\circ}$, $80^{\circ}$, and $100^{\circ}$ (the full knee extension was set to $0^{\circ}$) with the hip joint angles of $0^{\circ}$ and $80^{\circ}$ (the full extension was set to $0^{\circ}$). During the contractions, knee extension torque using an isokinetic dynamometer simultaneously with muscle activities of the rectus femoris (RF), and the vastus lateralis (VL) and vastus medialis (VM) using surface electromyography were recorded. Based on the torque values at systematically different knee-hip joint angles, the joint torque-angle relationships were established and then the optimal joint angle for the knee extensor was estimated. Results : The results of this study showed that the isometric knee extension torque values were greater for the Taekwondo athletes compared with the non-athlete group at all hip-knee joint angle combinations (p<.05). When the hip joint was set at $80^{\circ}$, the peak isometric torque was greater for the Taekwondo athletes compared with the non-athlete group ($313.61{\pm}36.79Nm$ and $221.43{\pm}35.92Nm$, respectively; p<.05) but the estimated optimum knee joint angles were similar ($62.33{\pm}5.71^{\circ}$ and $62.30{\pm}4.67^{\circ}$ for the Taekwondo athletes and non-athlete group, respectively). When the hip joint was set at $0^{\circ}$, the peak isometric torque was greater for the Taekwondo athletes compared with the non-athlete group ($296.29{\pm}45.13Nm$ and $199.58{\pm}25.23Nm$, respectively; p<.05) and the estimated optimum knee joint angle was larger for the Taekwondo athletes compared with the non-athlete group ($78.47{\pm}5.14^{\circ}$ and $67.54{\pm}5.77^{\circ}$, respectively; p<.05). Conclusion : The results of this study suggests that, compared with non-athletes, Taekwondo athletes have stronger knee extensor strength at all hip-knee joint angle combinations as well as longer optimum muscle length, which might be optimized for the event-specific required performance through prolonged training period.

• The Korean Journal of Ceramics
• /
• v.2 no.4
• /
• pp.226-230
• /
• 1996

A small amount of fine particle graphite was added to $\alpha$-SiC and $\beta$-SiC having certain particle distributions, and they were mixed clay and frit. After forming, they were sintered at 140$0^{\circ}C$ for 3 hours. Tribological properties of sintered $\alpha$-SiC-$\beta$-SiC-graphite-clay (frit) system showed that kinetic friction coefficient was 0.108, specific wear rate was 1.3${\times}10^-8\;mm^2$.$kgf^1$, and torque was 0.01kgf.cm at the wrench torque of 100 kgf.cm.

• Proceedings of the KIEE Conference
• /
• 1989.11a
• /
• pp.5-9
• /
• 1989

In this paper, while 2-or 3-phase induction motor is driven with balance and no noise driving at dynamic and steady state condition. Single-phase induction motor is driven with pulsating torque except specific driving point. So we analyze the reason of producing pulsating torque with the view of unsymmetring concept. These results are applied to the design of high efficincy, high quality single-phase induction motor.