• Journal of the Korean Orthopaedic Association
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• v.54 no.6
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• pp.519-527
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• 2019

Purpose: To evaluate the treatment result in polyostotic fibrous dysplasia classified according to the involvement of the femoral head. Materials and Methods: Twenty-three patients from March 1987 to March 2014 were reviewed retrospectively. Patients with no involvement of the physeal scar in the femoral head were classified as Type I, and those with involvement of the physeal scar were classified as Type II. A plain radiograph was used to measure the femoral neck shaft angle, articulo-trochanteric distance (ATD), and anterior bowing through the lateral view. A teleoroentgenogram of the lower limb was used to measure the leg length discrepancy and lower extremity mechanical axis. The pre- and postoperative femoral neck-shaft angle and ATD were compared to assess the degree of correction of the deformity. Results: Among a total of 46 cases (23 patients), 28 cases (23 patients) had lesions in the proximal femur. Type I were 16/28 cases (15/23 patients) and Type II were 12/28 cases (9/23 patients). The preoperative proximal femoral neck-shaft angle was 116.8° in Type I and 95.3° in Type II. The ATD was 12.08 mm in Type I and -5.54 mm in Type II. The deformity correction showed significant improvement immediately after surgery, the deformity correction was lost in Type II (neck shaft angle Type I: 133.8°-130.8°, Type II: 128.6°-116.9°, and ATD Type I: 17.66-15.72 mm, Type II: 7.44-4.16 mm). The extent of anterior bowing was 12.74° in Type I and 20.19° in Type II. The mean differences of 12 mm between the 9 patients who showed a leg length discrepancy and the lower extremity mechanical axis showed 4 cases of lateral deviation and 7 cases of medial deviation. Conclusion: In polyostotic fibrous dysplasia, when the femur head is involved, the femur neck shaft angle, ATD, and anterior bowing of the femur had more deformity, and the postoperative correction of deformity was lost, suggesting that the involvement of the femoral head was an important factor in the prognosis of the disease.

• Proceedings of the Korean Fiber Society Conference
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• 1997.04a
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• pp.127-133
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• 1997

Authors measured the apparent contact angle in a yarn using microscope because it gives a useful information in the evaluation of comfort factors in fabrics. The mechanical stage of microscope was designed and built to facilitate this measurement. Variables examined were the fiber type, the twisting number, and the fluid type. All produced significant effect most of which could be rationalized based on the known concepts. The methodology used and the results obtained are discussed in detail.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.101-105
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• 2000

In cold forging die the shrink fitting is generally used to decrease stress and increase die life. In this paper we have studied about the effect of fitting type, When the die insert is splitted into several pieces the maximum stress could be decreased as much as 50~70% The fitting angle could be selected to minimize the maximum stress and the variation of stress on loading and unloading, . In F, E.M result in case 3。 fitting angle the maximum and variation of stress may be minimized.

• Imaging Science in Dentistry
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• v.44 no.3
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• pp.229-236
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• 2014

Purpose: To investigate the prevalence of bifid and trifid mandibular canals using cone-beam computed tomography (CBCT) images, and to measure their length, diameter, and angle. Materials and Methods: CBCT images of 500 patients, involving 755 hemi-mandibles, were used for this study. The presence and type of bifid mandibular canal was evaluated according to a modified classification of Naitoh et al. Prevalence rates were determined according to age group, gender, and type. Further, their diameter, length, and angles were measured using PACSPLUS Viewer and ImageJ 1.46r. Statistical analysis with chi-squared and analysis of variance (ANOVA) tests was performed. Results: Bifid and trifid mandibular canals were found in 22.6% of the 500 patients and 16.2% of the 755 sides. There was no significant difference between genders and among age groups. The retromolar canal type accounted for 71.3% of the identified canals; the dental canal type, 18.8%; the forward canal type, 4.1%; and the trifid canal type, 5.8%. Interestingly, seven cases of the trifid canal type, which has been rarely reported, were observed. The mean diameter of the bifid and trifid mandibular canals was 2.2 mm and that of the main mandibular canal was 4.3 mm. Their mean length was 16.9 mm; the mean superior angle was $149.2^{\circ}$, and the mean inferior angle was $37.7^{\circ}$. Conclusion: Bifid and trifid mandibular canals in the Korean population were observed at a relatively high rate through a CBCT evaluation, and the most common type was the retromolar canal. CBCT is suggested for a detailed evaluation of bifid and trifid mandibular canals before mandibular surgery.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.9
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• pp.658-664
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• 2019

In the development of the liquid rocket engine using the pintle injector, spray characteristics such as spray angle, droplet size, and distribution of the droplets are dominant parameters. Three different kind of multi hole type pintle tip and a continuous type pintle tip were designed. In the case of multi hole pintle tip, SMD result did not have a significant difference depending on the number of holes. In analysis with visualization images, however, the droplets were uniformly distributed as the number of holes increased. Liquid droplets from continuous type pintle tip were finely atomized and dispersed uniformly than those from multi-hole type pintle tip. In addition, the thrust control by adjusting the liquid injection area of the pintle is suitable for the continuous type, which is easier to face-shutoff rather than the multi hole type. The spray angle of each pintle tip according to TMR was measured to derive a specific tendency and corresponding empirical formula.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.3
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• pp.80-87
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• 1995

In this paper, we design the microcontroller-based optimal lead angle control system on the basis of the presented maximum average torque formula of the permanent-type stepping motor with respect to the inductance. We confirm that optimal lead angle enlarges the operating range twice as much and increases the torque over all of the operating range in the case of presented formula as well as experimental results.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.37.2-38
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• 2015

According to the unified model of AGNs, type 1 and 2 AGNs are intrinsically the same objects but seem different due to an obscuring matter which can block lights from the central engine of the AGN depending on the viewing angle. The obscuring object is thought to be shaped in a toroidal form and thus the geometry of tori of AGNs is an important factor to determine the fraction of type 1 (or type 2) AGNs. Oh et al. (2015) provides a new catalog of type 1 AGNs from SDSS DR7 in the nearby universe (z < 0.2) and it contains nearly 50% more type 1 AGNs than previously known. Using this new catalog, we test the fraction of type 1 AGNs along the black hole mass (MBH) and the bolometric luminosity of AGNs (Lbol), which are regarded as key parameters of the AGNs. First of all, because the methods to derive the black hole mass and the bolometric luminosity bear uncertainties, we test how the different methods lead to different values of type 1 fraction. We found that the fraction of type 1 AGNs varies with both MBH and Lbol. The extensively-studied, "receding torus model" can only explain the trend along Lbol and hence fails to explain the trend. To understand the new trend, we test the geometry of the torus based on the "clumpy torus model". We present our results on the basic properties of the torus such as a column density or opening angle and compare with those from previous studies based on other wavelengths (e.g. Infrared or X-ray).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.898-906
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• 2008

A tested turbine consists of two stages, and an axial-type and a radial-type turbine are applied to the first and second stage, respectively. The mean diameter of the axial-type turbine rotor is 70 mm, and the outer diameter of the radial-type turbine is 68mm at the inlet. In this experiment, an axial-type turbine, two different radial-type turbines, and three different nozzle flow angles are applied to find the optimal design parameters. To compare the turbine performance, the net specific output torque is evaluated. The test results show that the nozzle flow angle on the first stage is a more important parameter than other design parameters for partially admitted small turbines to obtain high operating torque. For a 3.4% partial admission rate, the net specific output torque is increased by 13% with the addition of a radial-type rotor to the second stage when the turbine operates at $75^{\circ}$ nozzle flow angle.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.11
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• pp.943-950
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• 2016

The purpose of this study was to evaluate and compare by finite element analysis the biomechanical performance, in terms of cervical stand-alone cage screw insert angle (Type 3 - 5: 2 Screws) and screw arrangement (Type 6 and 7: 3 Screws / Type 8 and 9: 4 Screws), and the range of motion (ROM) of traditional anterior cervical discectomy of a fusion device (Type 1: Cage / Type 2: Cage + ACP). Our study suggests that the biomechanical behavior of a postoperative cervical spine could indeed be influenced by design features, such as screw angle and number of screws. In particular, ROM and the risk of subsidence were more sensitive during extension about type 5 (Insert Angle $20^{\circ}$). Our study also suggested that the number of screw asymmetries between up and down for type 6 and 7 could result in differences in the risk of screw fracture manifesting in different clinical aspects.

• Korean Journal of Optics and Photonics
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• v.19 no.4
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• pp.276-286
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• 2008

The representative alignments for taking a stereo image by using a stereoscopic camera are the toed-in and the parallel alignment. In this paper, we tried to find important factors in the process that captures the stereo image by modifying parallel type 3D camera alignment to take the same object information as, for instance, when toed-in type was used. The modified parallel type 3D camera has merits in both types. As a result, three important factors are found by simulation to be inter-camera distance, field of view and convergence angle for both types. And the change of the convergence angle is known to be the most important factor at the stereo fusible area in processing. The effective ranges of these factors to simulate perfectly toed-in type by modified parallel type are strongly dependent on a user's circumstances such as mobile, official, theater and so on. Additionally, the error of the simulation is reduced when the focal length of the stereo camera is short and the convergence angle becomes smaller.