• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.4
• /
• pp.586-592
• /
• 2018

SRMs are difficult to design using a simple mathematical model and, consequently, numerical analysis based characteristics analysis is used including drive circuits. In this process, it is necessary to analyze the trends according to the change of the design factors, however, many of the design factors affect each other. In order to shorten the design time and achieve a proper design, a modeling technique based on the design parameters is needed. For this purpose, this paper summarizes the formulas employed for shape modeling by minimizing the number of major design factors of the SRM, and proposes a methodology for SRM design using these formulas. In particular, we propose a design method for a 6/4-pole model, one which has been studied for a long time, and showed an example of a design produced by the proposed method.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.6 no.6
• /
• pp.873-880
• /
• 2011

As environmental pollution, global warming, and exhaustion of fossil fuel become global issue recently, there has been strong research motivation to develop green energy technology. Along the same line of motivation, some research efforts have been put into the development of environment-friendly bicycle equipped with various smart energy technologies to increase the usability of the bicycle as short-distance transportation. Among the technologies related with new generation bicycle, PAS (power assist system) is one of the most important systems that are essential in efficiently integrating human power and the electrical power supplied by electric motor driven by battery. In this paper, a novel torque sensor technology which is core component for PAS is proposed. Unlike existing technologies, strain gauges are attached to rear shaft directly under the hub bearings, which eliminates the requirement of slip-ring, Furthermore, the sensor is able to not only measure the torque transmitted to driving axle by human but also estimate the position of the gear to which the chain is currently engaged.

• Journal of the Korean Academy of Clinical Electrophysiology
• /
• v.9 no.2
• /
• pp.19-24
• /
• 2011

Purpose : This study is to examine the effects of transcranial direct current stimulation on the excitability of the central neuron. Methods : This study selected 24 suitable women in their twenties. A positive electrode of transcranial direct current stimulation was placed on the primary motor area (M1) C4 and a negative electrode was placed on the left supraobital. A stimulation of 0.04mA/$cm^2$ was applied for 20 minutes. H-reflex and V wave used diagnostic electromyography. An active electrode was placed at the muscle belly of the medial gastrocnemius muscle at a prone posture. An electrical stimulation was given to the posterior tibial nerve. Measurements were made before and after the stimulation. All data were analyzed with SPSS 12.0 and between each measuring before and after the change of the H-reflex and V wave amplitude. Results : There were no significant differences in all H wave, M wave, and V wave amplitude before and after transcranial direct current stimulation. There were no significant differences in the change of H/M ratio and V/M ratio before and after transcranial direct current stimulation. Conclusion : We know that transcranial direct current stimulation cannot have an influence on a normal grown-up person's central neuron.

• Proceedings of the KIEE Conference
• /
• 1999.07b
• /
• pp.894-896
• /
• 1999

PID 제어는 50년의 역사를 갖기 때문에 현장의 사용자는 이 제어방식에 익숙해져 있으며, 제어장치의 구성이 간단하며 제어기의 최적동조가 가능하므로 많은 분야에서 사용되고 있다[1]. 그러나 PID 제어기에 의해서 얻은 결과에 대하여 만족하기 위해서는 많은 시행착오를 겪어야 한다. 또한 만족하는 결과를 얻었다고 할지라도 외란, 플랜트의 동특성이 바뀌는 경우 시스템을 추종하지 못하기 때문에 파라미터를 재조정하여야 한다. 유전 알고리즘은 자연세계의 진화 현상에 기초한 계산모델로서 John Holland에 의해서 1975년에 개발된 전역적인 최적화 알고리즘이며[1][2], 비선형 고차원, 불연속, 다중모드, 노이즈 함수 등에 대하여 강건함을 보여주고, 복잡한 탐색 공간에서 최적 값을 스스로 발견하는 학습 능력을 갖는다. 이 방법은 재생산, 교배, 돌연변이를 통하여 최적해를 찾은 방법으로 1989년에 D. E. Goldgerg에 의해서 체계적으로 정리된 후 여러 분야에서 응용되고 있다[3][4]. 그러나 유전 알고리즘은 목적함수만을 이용하여 해집단을 탐색하기 때문에 숙련운전자가 원하는 제어 특성 명세인 상승시간, 정착시간, 초과량(oveshoot) 둥을 구체적으로 명시하여 제어에 반영할 수 없다. 또한, 유전 알고리즘은 입력 값이 크게 바뀔 경우 다른 시스템으로 인식하여 새로운 탐색을 수행하는 단점을 가지고 있다. 본 논문은 첫째, 기준모델을 도입하여 플랜트의 성능을 기준모델로 표현하여 플랜트가 요구하는 성능지표를 정량적으로 규정하는 것이 가능하였다. 또한, 이것은 미지 플랜트 동특성을 식별하기 위한 신호로 사용되어, 플랜트의 정보를 얻는데 이용되었다. 즉, 기준모델과 플랜트 출력사이의 추종 오차 정보가 적응기구인 PID 유전제어기의 입력으로 사용되며, 구형파 입력의 경우에도 기준모델과 플랜트의 출력차는 크게 변하지 않는다. 따라서, 유전 알고리즘의 목적함수에 기준 모델을 제안 적용하여 안정적이고, 세밀한 제어를 수행하였다. 둘째, PID의 간단하면서 확실한 제어가 가능하다는 점과 전역적인 최적값을 찾을 수 있는 유전 알고리즘을 적용하여 고속제어를 요하는 직류 서보 모터(DC Servo Motor) 운전 시 실시간 파라미터 동조에 적용하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.48 no.6
• /
• pp.71-81
• /
• 2011

Unlike a typical internal combustion engine vehicle, the powertrain system of the pure electric vehicle, consisting of battery, inverter and motor, has direct effects on the vehicle performance and dynamics. Then, the specific modeling of such complex electro-mechanical components enables the insight into the longitudinal dynamic outputs of the vehicle and analysis of entire powertrain systems. This paper presents the dynamic model of electric vehicle powertrain systems based on theoretical approaches to predict and analyze the final output performance of electric vehicles. Additionally, the correlations between electric input signals and the final output of the mechanical system are mathematically derived. The proposed model for powertrain dynamics of electric vehicle systems are validated with a reference electric vehicle model using generic simulation platform based on Matlab/Simulink software. Consequently, the dynamic analysis results are compared with electric vehicle simulation model in some parameters such as vehicle speed/acceleration, and propulsion forces.

• Physical Therapy Korea
• /
• v.14 no.4
• /
• pp.21-27
• /
• 2007

The purposes of this study were to compare core muscle activities with and without the use of Pilates resistive equipment during bridging exercises and to investigate the efficacy of a Pilates device. Fourteen healthy individuals (6 males, 8 females) between 20 to 26 years of age were examined. They were engaged in a bridging exercise with and without a magic circle. Three consecutive repetitions of each exercise were performed. Surface electromyography (sEMG) was used to measure the electrical activities of the right side internal oblique, the adductor longus, the multifidus, and the gluteus maximus muscles. Normalized EMG activities were compared using a paired t-test and the level of significance was set at =.05. The results showed that the EMG activities of the internal oblique (p=.0078), the adductor longus (p=.0007), and the gluteus maximus (p=.0001) muscles were significantly higher when using the magic circle during the Pilates bridging exercise. Also, statistically significant change existed in the multifidus muscle (p=.0106). The bridging exercise, combined with hip adduction using the magic circle, may enhance core stabilization. Therefore, using a magic circle during hip adduction combined with bridging exercise may be recommended usefully for individuals wanting to strength the core muscles. Further research is needed to access the nature of motor control of the Pilates mat exercises and to deliver exercise intervention for lower back pain patients.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.5
• /
• pp.131-136
• /
• 2016

Currently, an EDM tapping procedure has comprised some parts of the engraving discharge process for the press die. Usually, tapping has been used in cases where we are unable to mechanically machine using steelwork processes due to an increase in the hardness of a material after heat treatment in relation to a design change or missing process. Here, we analyze the influence of discharge tap shape on discharge time, discharge current, and the number of repetition conditions when a cold-work tool steel (STD11) has been treated with a discharge tapped by a screw-shaped cu electrode. The most important influence on processing condition has been determined to be the number of discharge repetitions. As this number increases, the angle reduction of a thread closes to an angle of the electrode via a power generation reduction. The optimal combination of conditions has been determined to be three discharge repetitions, $180{\mu}s$ of discharge time (same as existing regulations), and 25.4A of peak current. A 0.2749db advantage has emerged after comparing between this combination of optimal conditions and the SN rate of existing regulations.

• The Journal of Korean Physical Therapy
• /
• v.18 no.1
• /
• pp.65-73
• /
• 2006

Purpose: The purpose of this study was to identify the effect of electroacupuncture(EA) and transcutaneous electric nerve stimulation(TENS) after sciatic nerve crush injury in rats. Methods: The EA for experimental group I (Exp I, n=15) and TENS for experimental group II (Exp II, n=15) was applied from post-injury day(PD) 1 to PD 14 after sciatic nerve injury using low frequency stimulator that gave electrical stimulation(15min/60Hz). In order observe the effect of EA and TENS, this study examined GAP-43 expression in rat lumbar spinal cord at the PD 1, PD 7 and PD 14. In addition, the stride length(SL) and toe out angle(TOA) were measured at the PD 7 and PD 4. Results; Exp I and Exp II had higher GAP-43 immunoreactivity than control group(PD 1, 7, 14). The SL of Exp I and Exp II were significantly higher than control group(PD 7, 14). The TOA of Exp I and Exp II were significantly lower than control group(PD 7, 14). Conclusion: EA and TENS application increased motor nerve recovery and expression of GAP-43 immunoreactivity after sciatic nerve crush injury. Therefore effect of TENS and EA had similar effect on nerve regeneration and functional recovery.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.10
• /
• pp.60-65
• /
• 2003

An experimental study was performed to understand ignition characteristics of gas turbine combustor with rotating fuel injection system. Liquid fuel applied to the inner surface of rotating fuel nozzle which was driven by high speed electrical motor is flung away by centrifugal forces. The real scale combustor and test rig was manufactured and tested under atmospheric condition in KARl combustion test facility. From the test results, this combustor ignition characteristics are highly dependent upon fuel nozzle rotating speed. Futhermore, combustor exit gas temperature was rapidly changed by increasing or decreasing the fuel nozzle rotating speed.

• The Journal of Internal Korean Medicine
• /
• v.20 no.1
• /
• pp.244-260
• /
• 1999

This study was to investigate diagnosis of shoulder pain on cerebrovascular attack patients and treatment effects by using physical treatment and orienatal diagnosis aparatus, as oriental diagnosis equipments, these were used thermography, maegzin and yangdorag machine. as physical treatment equipments, these were used Hot pack, TENS (Transcutaneous electrical nerve stimulation), ICT(Interferential current therapy) the results were followed 1. In Sex and Age distribution on cerebrovascular attack patients with shoulder pain, male(51.7%)had many than female(48.3%) and 60s were the top, next 70s 50s 40s. 2. In the reason of cerebrovascular attack and the type of motor paresis, cerebrovascular infarction(73.3%) had many than hemorrhage(26.7%) 3. In hospitalizied period of cerebrovascular attack patients with shoulder pain, the period from 11 to 60 days had almost occupied. 4. Oriental medical diagnositic propriety of shoulder pain by using maegzin and yangdorag machine were not recognized. 5. In measuring passive range of motion of pre and post treatment, improvement effect on Hot pack was not showed, but effects on TENS, ICT were showed. 6. In measuring temperature of painful shouler joint of pre and post treatment by using thermography, the effect of Hot pack was not recognized but the effects of TENS, ICT were recognized.