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A Study on Rotor Position Detection and Securing Initial Position for Switched Reluctance Motor (SRM) (스위치드 릴럭턴스 전동기 (SRM) 회전자 위치 검출 및 초기 위치확보 연구)

  • Jeong, Sungin
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.20 no.3
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    • pp.141-146
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    • 2020
  • In brushless DC motors (BLDC), the on/off angle of the switch is determined by the optimal alignment of the stator and rotor, while switched reluctance motors (SRM) are complex parameters with many on/off angles of the switch. It appears as a function and therefore the switching angle is variable for optimal operation. Therefore, in order to operate the switched reluctance motor (SRM) optimally, the rotor position can be detected using a high resolution position sensor and a complicated additional circuit. In this paper, rotor position detection and related position detection circuits are applied and detected by using various sensors such as encoder, hall sensor and opto interrupter among several methods to drive switched reluctance motor (SRM). Also a study on securing the initial position of the rotor was conducted.

RTK Latency Estimation and Compensation Method for Vehicle Navigation System

  • Jang, Woo-Jin;Park, Chansik;Kim, Min;Lee, Seokwon;Cho, Min-Gyou
    • Journal of Positioning, Navigation, and Timing
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    • v.6 no.1
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    • pp.17-26
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    • 2017
  • Latency occurs in RTK, where the measured position actually outputs past position when compared to the measured time. This latency has an adverse effect on the navigation accuracy. In the present study, a system that estimates the latency of RTK and compensates the position error induced by the latency was implemented. To estimate the latency, the speed obtained from an odometer and the speed calculated from the position change of RTK were used. The latency was estimated with a modified correlator where the speed from odometer is shifted by a sample until to find best fit with speed from RTK. To compensate the position error induced by the latency, the current position was calculated from the speed and heading of RTK. To evaluate the performance of the implemented method, the data obtained from an actual vehicle was applied to the implemented system. The results of the experiment showed that the latency could be estimated with an error of less than 12 ms. The minimum data acquisition time for the stable estimation of the latency was up to 55 seconds. In addition, when the position was compensated based on the estimated latency, the position error decreased by at least 53.6% compared with that before the compensation.

Effect of Relative Position of Vane and Blade on Heat/Mass Transfer Characteristics on Stationary Turbine Blade Surface (베인과 블레이드 사이의 상대위치 변화에 따른 터빈 블레이드 표면에서의 열/물질전달 특성)

  • Rhee, Dong-Ho;Cho, Hyung Hee
    • The KSFM Journal of Fluid Machinery
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    • v.8 no.4 s.31
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    • pp.27-38
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    • 2005
  • The present study investigated the effect of relative position of the blade on blade surface heat transfer. The experiments were conducted in a low speed wind tunnel with a stationary annular turbine cascade. The test section has a single turbine stage composed of sixteen guide vanes and blades. The chord length of the blade is 150 mm and the mean tip clearance of the blade is $2.5\%$ of the blade chord. The Reynolds number based on blade inlet velocity and chord length is $1.5{\times}105$ and mean turbulence intensity is about $3\%$. To investigate the effect of relative position of blade, the blade at six different positions in a pitch was examined. For the detailed mass transfer measurements, a naphthalene sublimation technique was used. In general, complex heat transfer characteristics are observed on the blade surface due to various flow characteristics, such as a laminar flow separation, relaminarization, flow acceleration, transition to turbulence and tip leakage vortices. The results show that the blade relative position affects those heat transfer characteristics because the distributions of incoming flow velocity and turbulence intensity are changed. Especially, the heat transfer pattern on the near-tip region is significantly affected by the relative position of the blade because the effect of tip leakage vortex is strongly dependent on the blade position. On the pressure side, the effect of blade position is not so significant as on the suction side surface although the position and the size of the separation bubble are changed.

Study on the Error Compensation in Strain Measurement of Sheet Metal Forming (박판성형 변형률 측정 오차보정에 관한 연구)

  • 한병엽;차지혜;금영탁
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.270-273
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    • 2003
  • The strain measurement of the panel in the sheet metal forming is essential work which provides experimental data needed to die design, process design, and product inspection. To measure efficiently the complex geometry strain, the 3-dimensional automative strain measurement system, which has high accuracy in theory, but has some 3∼5% errors in practice, is often used. The object of this study is to develop the error compensation technology to eliminate the strain, errors resulted when formed panels are measured using an automated strain measurement system. To achieve the study object, the position error calibration method correcting coordinates of the grid node recognized by a camera using error functions is suggested. Then the position errors were found by calculating the difference in the position of the cube node between real coordinates and measured coordinates in toms of node coordinates and the error calibration equations were derived by regressing the position errors. In order to show the validation of the suggested position error calibration method, finite element analysis and current calibration method was performed for the initial-blankformed.

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Sensing Method of the Initial Rotor Position in Switched Reluctance Motors Using Search Coils (서치 코일을 이용한 스위치드 릴럭턴스 모터의 초기 회전자 위치 검출법)

  • Song J.S.;Yang H.Y.;Ryoo Y.J.;Lim Y.C.
    • Proceedings of the KIPE Conference
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    • 2003.07b
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    • pp.681-685
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    • 2003
  • In this paper, an sensing method of initial rotor position in Switched Reluctance Motor(SRM) at standstill is proposed. In case search coils are used as a position sensor, A search coil used in a method of detecting positions of TSRM has many advantages, which is highly efficient in low cost and maintenance free, and characterized by its function and role as a position sensor. However, the initial rotor position detection is very difficult because the search coil's EMF is not exist at a standstill. In this paper, a new sensing method of initial rotor position using squared Euclidean distance at a standstill too is suggested. The simulation and experiment for the proposed method are achieved. The validity of the proposed method is verified by experimental results.

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Immediate Effect of TFL Stretching in Weight Bearing Versus Non-Weight Bearing

  • Park, Sieun;Kim, Kijong;Kim, Sunghee;Lee, Gyeonglin
    • Journal of The Korean Society of Integrative Medicine
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    • v.8 no.2
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    • pp.21-27
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    • 2020
  • Purpose : The purpose of this paper is to compare the immediate effects of tensor fascia latae (TFL) stretching with weight bearing (standing position) or non-weight bearing (side-lying position). Methods : The study was conducted on 30 adults (12 men, 18 women) in their 20s. Modified Thomas's test was conducted to find out if the TFL muscle has a tightness for current study. This study randomly divided the subjects into two groups and set the standing stretching group (n=15) or the side-lying stretching group (n=15). Both groups applied self-stretching under the therapist's supervision. TFL stretching in each positions was performed 30 seconds per set, 3 times, and 30 seconds per set could rest. The Ober test were conducted to investigate the effect of TFL stretching in each positions. Results : For the Ober test measurements within each group, both groups significantly increased after intervention compared to before (p<.05). There was no significant difference between the groups (p>.05). Conclusion : TFL stretching in standing position and side-lying position increased the range of motion of the TFL muscle. Therefore, if it is difficult to apply TFL stretching in standing position (weight bearing) due to pain or other reasons, it will be able to TFL stretching in side-lying position (non-weight bearing).

Effect of Kegel Exercise on Vital Capacity According to the Position: A Preliminary Study

  • Park, KangHui;Park, HanKyu
    • The Journal of Korean Physical Therapy
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    • v.32 no.4
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    • pp.217-221
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    • 2020
  • Purpose: This study examined the immediate effect of Kegel exercise on the vital capacity according to the position. Methods: Seventeen subjects participated in the study (male=7, female=10). The subjects performed Kegel exercise in two positions: sitting and hooklying. The order of exercise was conducted in a random order selected by the subjects to exclude the learning effect. The maximum voluntary ventilation (MVV) was measured using a spirometer. The vital capacity was measured according to the manual in the sitting position before the experiment. After each exercise, the vital capacity was also measured in the same way. One way repeated measures analysis of the variance (ANOVA) was used to compare the vital capacity according to the position, and a Bonferroni test was used for post hoc analysis. Results: Significant differences in vital capacity were observed after exercise than before exercise (p<0.05). Post-hoc analysis, however, revealed no difference in vital capacity according to the position (p>0.05). Conclusion: This study was a preliminary study to determine the vital capacity according to the Kegel exercise and two positions. Nevertheless, further study with several revisions of the number of subjects, duration, and time for intervention will be needed.

Socio-cultural position of women in Nepal and Korea: A comparative approach

  • Gadtaulaa, Swechchha;Chung, Yong Kyo
    • Journal of Contemporary Eastern Asia
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    • v.15 no.2
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    • pp.162-176
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    • 2016
  • In this study, a part of the social and the economic condition of Nepali women is introduced with a short comparison to the socio-cultural position of the women of Korea. A relative definition of the condition of the past and now: this also briefly introduces the ideas of some of the Nepali women that we have collected through the questionnaire. A comparative literature reviews about the position of women in the past as well as the review of the position of women in present is made. Various articles are used for this as the method of analysis. A quantitative analysis of the status of women (Nepal) taking 24 households through the questionnaire method was done. The answers given by the women are the base for the article. However, the answers to the questionnaire are used to compare the past and the present. Analysis of the received data and their explanation through the tables and graph are done. The charts and tables are followed by a detailed explanation. Conclusively the briefing of the condition of women in both the countries, the changes that are brought or not brought by development; in their life's status and position in society, is mentioned.

Utilization of the Route Table for the Agent's Move in the Game Map (게임지도에서 에이젼트 이동을 위한 경로표 활용)

  • Shim, Dong-Hee;Kang, Hyuk
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.10
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    • pp.3164-3170
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    • 2000
  • The use of the A' for the path search of the agent in the game map give the overhead of computing time in real time game processing. The other heuristic search algorithms do not guarantee the optical path. The route table of which the row is defined by current position, goal position, visiting position is presented in this paper. This route table is made in the game development phase and tilized in game playing. The visiting position which is contatined in the optimal path to the goal position from the current position can guarantee the optical path, and this mothod has no overhead on computing time. But the memory space is requred too much. This problem can also be solved using the data compression by skipping the duplicated route table.

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CORRELATIONS BETWEEN ORBICULARIS ORIS AND MENTALIS MUSCLE ACTIVITY AND CRANIOFACIAL MORPHOLOGY IN NORMAL OCCLUSION AND CLASS III MALOCCLUSION (정상교합자와 3급 부정교합자에서 구륜근과 턱끝근의 활성과 안면골격 사이의 상관성에 관한 연구)

  • Chang, Chun Sil;Lee, Ki Soo
    • The korean journal of orthodontics
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    • v.22 no.1
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    • pp.253-271
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    • 1992
  • The purpose of this study was to investigate the difference of EMG activity of the Orbicularis oris and Mentalis muscle between normal occlusion and class III malocclusion group during various lip position and to find out whether any correlations exist between the muscular activity and craniofacial morphology. In this study, 50 subjects with a mean age of 22.9 Years (range 20.0-26.0) were investigated (25 subjects were normal occlusion, and 25 subjects were class III malocclusion). EMG data were recorded from the Orbicularis oris and Mentalis muscle during rest lip posture, lip position at maximum biting, lip position at maximum sealing effort, lip position at chewing, swallowing and phonation with the Medelec MS-25 electromyographic machine. Lateral cephalometric radiographs was taken with the mandible in intercuspal position on all subjects. All data were recorded and statistically processed. The findings of this study can be summerized as follows: 1. In normal occlusion, the maximal mean amplitude of upper lip during the lip position at chewing was lower than that of lower lip and mentalis muscle. But the maximal mean amplitude of orbicularis oris and mentalis muscle during the other lip position was not statistically different. 2. In Class III malocclusion, the maximal mean amplitude of upper lip during the lip position at chewing, swallowing and phonation was lower than that of lower lip and mentalis muscle. But the maximal mean amplitude of orbicularis oris and mentalis muscle during the other lip position was not statistically different. 3. Compare to normal occlusion, the Class III malocclusion was showed low maximal mean amplitude of upper lip during rest lip posture and the lip position at swallowing of saliva, and showed great maximal mean amplitude of lower lip and meantalis muscle during the lip position at chewing and phonation. 4. In normal occlusion, the maximal mean amplitude of upper lip during various lip position was not correlated with the length and thickness of upper lip, but the maximal mean amplitude of lower lip during the lip position at chewing and swallowing was positively correlated with the thickness of lower lip. 5. In Class III malocclusion, the maximal mean amplitude of upper lip during rest lip posture was negatively correlated with the thickness of upper lip, and the maximal mean amplitude of lower lip and mentalis muscle during the lip position at chewing and swallowing was positively correlated with the thickness of lower lip and mentalis muscle. But the maximal mean amplitude of orbicularis oris and mentalis muscle during the other lip position was not correlated with the cephalometric measurements of soft tissue. 6. The correlation between the maximal mean amplitude of orbicularis oris and mentalis muscle and cephalometric measurements of incisors was not nearly present. 7. In normal occlusion, the maximal mean amplitude of lower lip and mentalis muscle during the lip position at maximum biting was negatively correlated with the angle between palatal plane and mandibular plane. In Class III malocclusion, the maximal mean amplitude of upper lip, lower lip and mentalis muscle during function was negatively correlated with the length of maxilla, the maximal mean amplitude of upper lip and lower lip during function was negatively correlated with the SNA and SNPo, and the maximal mean amplitude of lower lip during the lip position at chewing was negatively correlated with the ANB.

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