• International Journal of Fluid Machinery and Systems
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• v.2 no.1
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• pp.13-20
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• 2009

The effects of positively bowed blade on the aerodynamic performance of annular compressor cascades with large camber angle were experimentally investigated under different incidences. The distributions of the exit total pressure loss and secondary flow vectors of compressor cascades were analyzed. The static pressure was measured by tapping on the cascade surfaces, and the ink-trace flow visualizations were conducted. The results show that the value of the optimum bowed angle and optimum bowed height decrease because of the increased losses at the mid-span with the increase of the caber angle. The C-shape static pressure distribution along the radial direction exists on the suction surface of the straight cascade with large r camber angles. When bowed blade is applied, the larger bowed angle and larger bowed height will further enhance the accumulation of the low-energy fluid at the mid-span, thus deteriorate the flow behavior. Under $60^{\circ}$ camber angle, flow behavior near the end-wall region of some bowed cascades even deteriorates instead of improving because the blockage of the separated flow near the mid-span keeps the low-energy fluid near the end-walls from moving towards the mid-span region, and as a result, a rapid augmentation of the total loss is easy to take place under large bowed angle. With the increase of camber angle, the choice range of bowed angle corresponding to the best performance in different incidences become narrower.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.199-202
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• 2002

Interfacial properties and electrical sensing for fiber fracture in carbon and SiC fibers/epoxy composites were investigated by the electrical resistance measurement and fragmentation test. As fiber-embedded angle increased, interfacial shear strength (IFSS) of two-type fiber composites decreased, and the elapsed time was long to the infinity in electrical resistivity. The initial slope of electrical resistivity increased rapidly to the infinity at higher angle, whereas electrical resistivity increased gradually at small angle. Furthermore, both fiber composites with small embedded angle showed a fully-developed stress whitening pattern, whereas both composites with higher embedded angle exhibited a less developed stress whitening pattern. As embedded angle decreased, the gap between the fragments increased and the debonded length was wider for both fiber composites. Electro-micromechanical technique can be a feasible nondestructive evaluation to measure interfacial sensing properties depending on the fiber-embedded angle in conductive fiber reinforced composites.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.617-623
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• 2021

The objective of this study is to simulate valve flow coefficient and flow characteristics such as velocity and pressure distribution for butterfly valve. The size of the valve used in this study is 125A. The range of the valve opening angle was α=15°~70°, and it was changed by 5°. At the range of α=15°~30°, the valve flow coefficient K_𝜐 gradually increased, and after α=30°, it increased rapidly. In the range of α=20°~70°, the pressure change in the -2.9cm~+2.9cm region in the pipe greatly depended on the opening angle and the position within the pipe. However, after +2.9cm, the pressure at the rear end of the valve was shown to depend only on the opening angle. At α=20°, Vortex shedding occurred for the first time at time t=0.25sec and continuously occurred in rear end of the valve over time. After α=45°, in the flow pattern at the rear end of the valve, the upward flow at the lower end of the valve and the flow at the upper end met each other to form a mixed flow. This flow phenomenon was shown to form a more intense mixed flow in the rear end region as the opening angle increased. Vortex flow occurred for the first time at α=15°, and the opening angle increased, the occurrence and disappearance of this flow phenomenon occurred periodically according to the certain flow region. The pattern of the pressure distribution in the region at the rear end of the valve showed a tendency to agree well with the results of the vorticity distribution.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.67-69
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• 1999

ADD is under development for the high speed motor. This paper describes the test results for obtaining the maximum output by leading angle of encoder. So we carried out the test for obtaining the optimum leading angle of encoder. Maximum output 80[Kw] at 20,000[rpm] was obtained at leading angle of encoder at near $22^{\circ}$. We confirmed the maximum output 106[kw] of 25,000[rpm] at leading angle of encoder at $34.6^{\circ}$.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.750-753
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• 2000

ADD is under development for the high speed motor. This paper describes simulation and test results for obtaining the maximum output by leading angle of encoder. So we carried out the test for obtaining the optimum leading angle of encoder. Maximum output 80[kW] at 20,000[rpm] was obtained at leading angle of encoder at near $22^{\circ}$. We confirmed the maximum output 106[kW] of 25,000[rpm] at leading angle of encoder at $34.6^{\circ}$.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.1
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• pp.40-47
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• 2018

This study was conducted to examine changes in the muscle activity of the triceps surae, specifically the gastrocnemius and the soleus, depending on the angle of the knee joint during the manual muscle test (MMT) of the plantar flexion of the ankle. The muscle activity of the medial and lateral heads of the gastrocnemius was statistically significantly reduced when the angle of the knee joint was $15^{\circ}$, $30^{\circ}$, and $45^{\circ}$ compared to when the angle was $0^{\circ}$. However, there was no statistically significant difference in muscle activity at the angles of $15^{\circ}$ and $30^{\circ}$ or $45^{\circ}$. There was no statistically significant difference in the muscle activity of the soleus depending on the angle of the knee joint. The ratio of the muscle activity of the soleus to that of the triceps surae showed a statistically significant increase when the angle was $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$ compared to when the angle was $0^{\circ}$. However, there was no statistically significant difference in muscle activity at the angles of $15^{\circ}$ and $30^{\circ}$ or $45^{\circ}$. When the angle of the knee joint was $15^{\circ}$ or higher during the test of the isolated soleus, the muscle activity of the gastrocnemius was reduced. These results indicate that the angle is suitable for the test of the isolated soleus, but there was no statistically significant difference in the muscle activity of the gastrocnemius when the angle was higher than $15^{\circ}$. Therefore, it can be concluded that the most suitable angle of the knee joint for the isolated MMT test of the soleus is $15^{\circ}$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.12
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• pp.1013-1019
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• 2016

CFRP is the composite material manufactured by the hybrid resin on the basis of carbon fiber. As this material has the high specific strength and the light weight, it has been widely used at various fields. Particularly, the unidirectional carbon fiber can be applied with the layer angle. CFRP made with layer angle has the strength higher than with no layer angle. In this paper, the property of crack growth due to each layer angle was investigated on the crack propagation and fracture behavior of the CFRP compact tension specimen due to the change of layer angle. The value of maximum stress is shown to be decreased and the crack propagation is slowed down as the layer angle is increased. But the limit according to the layer angle is shown as the stress is increased again from the base point of the layer angle of $60^{\circ}$. This study result is thought to be utilized with the data which verify the probability of fatigue fracture when the defect inside the structure at using CFRP of mechanical structure happens.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.8 no.1
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• pp.39-47
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• 2013

Objectives : The purpose of this study is to find out the relationship between hip internal rotation angle and the level of herniation of lumbar intervertebral disc(HIVD) in single-segment. Methods : We investigated 314 patients (158 male, 156 female) who were diagnosed as herniation of lumbar intervertebral disc(HIVD) in single-segment. We measured 314 patients' hip internal rotation angle and analysed the relationship between the hip internal rotation angle and the level of herniation of lumbar intervertebral disc(HIVD). Results : 1. Among 314 cases, the hip internal rotation angle was different between male and female. Hip internal rotation angle of male was mainly limited and that of female was mainly excessive. 2. Among 314 cases, the normal group, defined as patients who have specific range of hip internal rotation angle(male : $35^{\circ}{\pm}10^{\circ}$, female : $45^{\circ}{\pm}10^{\circ}$), tends to be occurred HIVD at L4/5 level. The limited group, defined as patients who have less angle than normal group, the excessive group, defined as patients who have more angle than normal group, and the complex group, defined as patients who have more angle of one leg and less angle of the other leg than normal group, tend to be occurred HIVD at L5/S1 level(p<0.05). Conclusions : In single-segment lumbar HIVD patients, The normal hip internal rotation angle mainly leads to L4/5 HIVD, while the limited and excessive hip internal rotation angle mainly lead to L5/S1 HIVD.

• The korean journal of orthodontics
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• v.32 no.6 s.95
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• pp.413-424
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• 2002

Preadolescent children with deficient maxillae are suitable candidates for the maxillary protraction appliance(MPA). The theoretical effect of the MPA is protraction or anterior displacement of the maxilla. However, it is known that complex effects such as anterior displacement of the maxillary teeth, downward and backward rotation of the mandible, linguoversion of the mandibular anterior incisors, are known to play a role in improving the Cl III malocclusion. There have been much studies with regard to maxillary protraction, but the different effects of MPAs depending on the vertical facial pattern are not known precisely. This study was based on 67 patients (31 males, 36 females) aged from 6 years 6 months to 13 years 3months, who visited the Dept. of Orthodontics at Yonsei Univ., Dental Hospital and diagnosed as skeletal Class III with maxillary deficiency. They were divided into 3 groups (low, average, high angle groups) depending on genial angle and the SNMP (Go-Gn) angle, respectively. Pretreatment and post-treatment lateral cephalograms were used to compare the effects of MPA and the following conclusions were obtained: 1) A significantly large amount of backward movement of the B point was observed in patients with a low SNMP angle. Those with a high SNMP angle had significant forward movement at A point. 2) The patients with low genial angle had the least forward movement at the A point, and those with a high angle had more forward movement. 3) In comparing the arcTan of the A point, the high angle group showed more horizontal movement while the low angle group showed more vertical movement. 4) There was no significance between the treatment duration of the SNMP and the Genial angle groups.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.147-154
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• 1997

The main purpose of this study is to investigate the failure surface in a soil mass by a excavation of the model ground. The failure mechanism of an earth structure is usually determined from field failure observations or from laboratory model tests at failure. To study the failure surface for the excavated slope, laboratory model tests were performed by changing the angle of the excavated slope and the ground condition. Results of the laboratory model tests were compared with those obtained with theoretical solutions using limit equilibrium analysis method. The results of model tests show that, there is a failure to create a straight line in the low angle of excavated surface and a create a circle as the angle increases. As the angle of excavated surface is increasing, the angle of the failure surface increases too. In the angle of the failure surface, the submerged ground is less than the dry ground at $3.2^{\circ}$.