• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.33 no.2
• /
• pp.141-148
• /
• 2009

Axial-flow compressor is one of the most important parts of gas turbine units with axial turbine and combustor. Therefore, precise prediction of performance is very important for development of new compressor or modification of existing one. Meanline analysis is a simple, fast and powerful method for performance prediction of axial-flow compressors with different geometries. So, Meanline analysis is frequently used in preliminary design stage and performance analysis for given geometry data. Much correlations for meanline analysis have been developed theoretically and experimentally for estimating various types of losses and flow deviation angle for long time. In present study, meanline analysis program was developed to estimate compressor losses, incidence angles, deviation angles, stall and surge conditions with many correlations. Performance prediction of one stage axial compressors is conducted with this meanline analysis program. The comparison between experimental and numerical results show a good agreement. This meanline analysis program can be used for various types of single stage axial-flow compressors with different geometries, as well as multistage axial-flow compressors.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.1
• /
• pp.229-240
• /
• 1991

The large camber angle theory of turbomachine blade of compressor has been developed recently for the two-dimensional flow by Hawthorn, et al. However, in the above theory it was assumed that the fluid was incompressible and inviscid, and the blades had no thickness. In this study, the flow in a blade cascade being mounted in parallel fashion with blade of arbitrary thickness is studied in order to determine the effects of the camber angle on the performance characteristic of the blade section under the consideration of compressibility and viscosity of fluid. The panel method is used for potential flow analysis. The flow in the boundary-layer is obtained by solving the integral boundary-layer structure through the laminar, transitional , and turbulent flow using the pressure field determined from the potential flow. And then the viscous-inviscid interaction scheme is used for interaction of these two flows. For the determination of the variation in the outlet fluid angle influenced by deviation in cascade flow, the superposition method which is used for single foil is introduced in this analysis. By the introduction of this method, the effects of the deviation on outlet fluid angle and the resulting fluid angle are made to adjust for oneself through the calculation. As the result of this study, the blade of large camber angle, large incidence angle, large pitch-chord ratio has large viscous and compressible effect than those of small camber angle. Lift force increase as camber angle increases, but above 60.deg. of camber angle, lift force decrease as camber angle increases. But drag force increases linearly with camber angle increases in the entire region.

• Communications for Statistical Applications and Methods
• /
• v.4 no.2
• /
• pp.507-514
• /
• 1997

Three kinds of unbiased estimators of standard deviation in a truncated arcsine distribution based on the quasi-range, the jackknife quasi-range, and the angle jackknife range are proposed and numerically compared each other in a sense of MSE.

• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.9
• /
• pp.812-817
• /
• 2002

This paper presents a development of high accuracy aligner and describes a method to find the orientation of a substantially circular disk shaped wafer with at least one flat region on an edge thereof. In the developed system, the wafer is spun one 360 degree turn on a chuck and the edge position is measured by a linear array to obtain a set of data points at various wafer orientation. The rotation axis may differ from wafer center by an unknown eccentricity. The flat angle is found by fitting a cosine curve to the actual data to obtain a deviation. The maximum deviation is then corrected for errors due to a finite number of data points and wafer eccentricity by calculating an adjustment angle from data points on the wafer fiat. After determining the flat angle the wafer is spun to the desired orientation. The wafer eccentricity can be calculated from four of the data points located away from the flat edge region. and the wafer is then centered.

• The korean journal of orthodontics
• /
• v.30 no.5 s.82
• /
• pp.535-542
• /
• 2000

The purpose of this study was to find the characteristics of the frontal natural head position(NHP) of patients with facial asymmetry, and to contribute to the diagnosis of facial asymmetry in the clinical examination of orthodontic patients. Twenty adult patients who had apparent facial asymmetry and no severe sagittal skeletal discrepancy were selected as the asymmetry group, and 21 young adults who had symmetric faces were selected as the symmetry group. Frontal cephalograms were obtained in the state of NHP using a pivot-mounted fluid level device. The degree of the menton deviation was defined as the angle between the line drawn through crista galli and anterior nasal spine and the line drawn through crista galli and menton. The following angles were measured and each of them was compared with the degree of the menton deviation one is the angle between the true vertical line and the supra-orbital line which is a tangent line to the extreme cranial point on the supra-orbital margin, and the other is the angle between the true vertical line and the cervical line drawn through the midpoint of atlas and the 4th cervical vertebra. Through the statistical analysis, following results were obtained. 1. The angle between the supra-orbital line and the true vertical line was much mote deviated from the right angle in the asymmetry group than in the symmetry group. 2. The angle between the cervical line and the true vertical line in the asymmetry group showed greater tendency than in the symmetry group, but the difference was not statistically significant. 3. In the asymmetry group, the degree of the menton deviation was positively correlated with the angle between the supraorbital line and the true vertical line. The above results suggest that racial asymmetry patients show the tendency to have the tilted NHP to compensate the deviation of menton position.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.28 no.2
• /
• pp.471-489
• /
• 1998

For the successful endodontic treatment, root canal should be cleaned thoroughly by accurate mechanical and chemical canal preparation and sealed completely with canal filling material without damaging the periapical tissues. The accuracy of the root canal length measurement is a prerequisite for the success of the endodontic treatment, and the root canal length is often determined by the standard periapical radiographs and digital tactile sense. In this study, the accuracy and the clinical usefulness of Digora/sup (R)/, an intraoral digital imaging processor and the conventional standard radiographs were compared by measuring the length from the top of the file to the root apex. 30 single rooted premolars were invested in a uniformly sized blocks and No.25 K-file was inserted into and fixed in each canal. Each block was placed in equal distance and position to satisfy the principle of the bisecting angle and paralleling techniques and Digora/sup (R)/ system's image and standard periapical radiographs were taken. Each radiograph was examined by 3 different observers by measuring the length from top of the file to the root apex and each data was compared and analyzed. The results were as follows; 1. In the bisecting angle technique, the average difference between the Digora/sup (R)/ system and standard periapical radiograph was 0.002 mm and the standard deviation was 0.341 mm which showed no statistically significant difference between the two systems(p>0.05). Also, in the paralleling technique, the average difference between these two system was 0.007 mm and the standard deviation was 0.323 mm which showed no statistically significant difference between the two systems(p>0.05). 2. In Digora/sup (R)/ system, the average difference between the bisecting angle and paralleling technique was -0.336 mm and the standard deviation was 0.472 mm which showed a statistically significant difference between the two techniques(p<0.05). Also, in the standard periapical radiographs, the average difference between the bisecting angle and paralleling technique was 0.328 mm and the standard deviation was 0.517 mm which showed a statistically significant difference between these two techniques(p<0.05). 3. In Digora/sup (R)/ system and the standard periapical radiographs. there was a statistically significant difference between the measurement using the bisecting angle technique and the actual length(p<0.05), But there was no statistically significant difference between the measurement using the paralleling technique and the actuallength(p>0.05). In conclusion. the determination of the root canal length by using the Digora/sup (R)/ system can give us as good an image as the standard periapical radiograph and using the paralleling technique instead of the bisecting angle technique can give a measurement closer to the actual canal length. thereby contributing to a successful result. Also. considering the advantages of the digital imaging processor such as decreasing the amount of exposure to the patient. immediate use of the image. magnification of image size. control of the contrast and brightness and the ability of storing the image can give us good reason to replace the standard periapical radiographs.

• Journal of Korean Foot and Ankle Society
• /
• v.1 no.1
• /
• pp.11-14
• /
• 1997

Hallux valgus is a complex deformity which contains static subluxation of the first metatarsophalangeal joint with lateral deviation of the great toe and medial deviation of the first metatarsal bone. Among the several parameters, radiographic indices are the important ones in the choice of the treatment method. Even though, the normal values of the western peoples are already estabilished, there was no standard values for Korean who has different genetics, and cultural background, till now. So, we tried to estimate the noraml values of the HVA (hallux valgus angle ), IMA ( Intermetatarsal angle) and DMAA (Distal Metatarsal Articular surface Angle) in a normal adult. Fifty normal adult (each 25 male and female) were chosen and took 100 cases of foot radiograph and radiologic indices of the hallux valgus were measured. Average age at the investigation was 34.5 years old. The average HVA is $13.3^{\circ}$, IMA is $8.5^{\circ}$ and DMAA is $34.6^{\circ}$.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.16 no.1
• /
• pp.71-78
• /
• 2011

In this paper, the effect of parameter errors to the estimation of the rotor angle in sensorless operation of a permanent magnet synchronous motor is analyzed. The angle error information which is utilized to estimate the rotor position can be classified into two factors, namely, the sign factor and the gain factor. This paper particularly focuses on parameter errors reflected in the sign factor of the angle error information which causes a deviation in the angle estimation. In this paper, mathematical expressions describing the deviation of the angle estimation due to the inductance error and the resistance error in the sensorless control are derived. The validity of the expression is verified by the computer simulations and the experimental results.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 1972.03a
• /
• pp.2.3-2
• /
• 1972

The vestibular function test reveals the objective findings of the impairment of the vestibular labyrinth. It's purpose is based on the analysis of the findings and detect the location and etiology of the labyrinthine impairment. In the vestibular function test, the vestibulo-spinal reflex has the clinical significance upon the tonus of the striated muscles by the labyrithine stimulation and contribute to regulating the posture and the position, at rest as well as in motion. The vestibulo-spinal reflex must performe as one of the routine vestivular function test because it can be evoked in man by such weak stimuli to the labyrinth as cannot induce vestibulo-ocular reflex. Authors performed the vestibular function test such as one leg test, gait test, stepping test and vertical writing test to one hundred of healthy and young male adult and received the following results. Results 1. One leg test: In 30 seconds, the frequency of dropping the leg on the ground was between 0 to 3 times in Rt., and 0 to 5 times in Lt. The mean frequency was 0.48 times in Rt., and 0.68 times in Lt. 2. Gait test: In forward gait; the range of the deviation was distributed 0 to 100 cm and mean range was 22.5cm to the Rt., 26.1cm to the Lt. In backward gait; the range deviation was distributed 0 to 140cm and mean range was 35.4cm to the Rt., 33.0cm to the Lt. 3. Stepping test: In normal head position; forward movement war 93% and backward 5%. The angle of displacement deviated to the Rt. side in 36%, and Lt. in 50%. The angle of rotation deviated to the Rt. side in 53 %, and Lt. in 36%. The mean values: angle of displacement was 22.05 degrees, angle of rotation was 24.40 degrees, distance of displacement was 48.95cm. In backward head position; Forward movement was 94% and backward was 3%. The angle of displacement deviated in 34%, and Rt. in 55%, to the Rt. side The angle of rotation deviated to the Rt. side in 50%, and Lt. in 42%. The mean values; angle of displacement was 29.72 degrees, angle of rotation was 39.53 degrees, distance of displacement was 44.17cm. 44.17cm. 4. Vertical writing test: The angle of deviation was between 0 to 16 degrees in all cases, and was between 0 to 12 degrees in the cases of normal head position. The mean angle of deviation was between 4.15 to 5.76 degrees on each side. The direction of deviation to the Rt. side was 54~69%, Lt. was 25~40% and 3~7% was vertical without deviation.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1496-1500
• /
• 2008

Less than 1 % directional error in the range of 5 meters in the green could cause a stroke or more. Although there are several reasons offsetting the direction of the golf ball, lie angle and sidespin effect are the most crucial factors of the putting game. Simple equation is conformed to the experimental results of the deviation of the directional error in all distance. Also, the experimental results of the putting robot show that there are significant side spin effects.