• The Journal of the Society of Korean Medicine Diagnostics
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• v.16 no.3
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• pp.33-40
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• 2012

Objectives: Existing cardiovascular simulators are used to evaluate artificial organs such as artificial hearts, prosthetic valves, and artificial blood vessels, and pulses are typically triggered using artificial hearts. However, the forms of pulse waves vary according to the location of arteries, and for precise assessment of artificial blood vessels, the development of simulators that generate diverse pressure pulse waves is necessary. This study developed a novel cardiovascular simulator that generates different forms of pulse waves. Methods: This simulator consists of a stepping motor, a slider-crank mechanism that transforms the rotation movement of a motor into the straight-line motion of a piston, a piston that generates pulsatile flows, a water tank that supplies fluids, an elastic tube made of silicon, and a device that adjusts the terminal resistance of fluids. Results & Conclusion: This study examined motor rotation and its operation under conditions similar to the physiological conditions of the heart. The simulator developed in this study produced diverse forms of waves, and the generated pressure waves well satisfied physiological conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.1997-2007
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• 2002

Composite air spindles are appropriate for the high-speed and the high-precision machining as small hole drilling of printed circuit board (PCB) or wafer cutting for manufacturing semiconductors because of the low rotational inertia, the high damping ratio and the high fundamental natural frequency of composite shaft. The axial load and stiffness of composite air spindles fur drilling operation are determined by the thrust ben ring composed of the air supply part mounted on the housing and the rotating part mounted on the rotating shaft. At high-speed rotation, the rotating part of the thrust bearing should be designed considering the stresses induced by centrifugal force as well as the axial stiffness and the natural frequency of the rotating shaft to void the shaft from failure due to the centrifugal force and resonant vibration. In this work, the air supply part of the thrust bearing was designed considering the bending stiffness of the bearing and the applied load. The rotating part of the thrust bearing was designed through finite element analysis considering the cutting forces during manufacturing as well as the static and dynamic characteristics under both the axial and con trifugal forces during high-speed rotation.

• Korean Journal of Head & Neck Oncology
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• v.32 no.2
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• pp.79-83
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• 2016

Chyle fistula is one of the complications of neck dissections. Although immediate surgical repair seems to be the best choice when chyle leakage is observed during the operation, some operators can be embarrassed when chyle leakage is heavy and not controlled during surgery. In this case, chyle leakage was occurred after extensive resection of lymph nodes in left level IV, and was not controlled in any way. The clavicular head of sternocleidomastoid muscle was dissected and inferior-based muscular flap was rotated to cover the suspected region of fistula orifice. Amount of drainage was checked less than 20 ml per day in the following days, and drain tube was taken out on the 3rd postoperative days. We present the technique using the inferior based sternocleidomastoid muscle flap for intraoperative management of chyle leakage not easily controlled.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.3
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• pp.81-86
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• 2010

Since CORDIC (COordinate Rotation DIgital Computer) is able to carry out the phase operation, such as vector to phase conversion or rotation of vectors, with adders and shifters, it is well suited for the design of the frequency synchronization unit in OFDM receivers. It is not easy, however, to fully utilize the CORDIC in the OFDM demodulator because of the non-linear characteristics of the direction sequence (DS), which is the representation of the phase in CORDIC. In this paper a new representation method is proposed to linearize the direction sequence approximately. The maximum phase error of the linearized binary direction sequence (LBDS) is also discussed. For the purpose of designing the hardware, the architectures for the binary DS (BDS) to LBDS converter and the LBDS to BDS inverse converter are illustrated. Adopting LBDS, the overall frequency synchronization hardware for OFDM receivers can be implemented fully utilizing CORDIC and general arithmetic operators, such as adders and multipliers, for the phase estimation, loop filtering of the frequency offset, derotation for the frequency offset correction. An example of the design of 22 bit LBDS for the T-DMB demodulator is also presented.

• Particle and aerosol research
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• v.11 no.1
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• pp.9-19
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• 2015

This study investigated the effects of ball mill operation condition on the morphology of raw powders in the dry-type milling process using three types of ball mills traditional ball mill, stirred ball mill and planetary ball mill. Furthermore, since spherical powders offer the best combination of high hardness and high density, the optimum milling condition to produce sphere-shaped powders was studied. The applied rotation speed ranged from 200rpm (low rotation speed) to 700rpm (high rotation speed). The used ball size ranged from 1mm to 5mm. The metal powder morphology was studied using SEM, XRD and PSA. The aimed spherical powders could be obtained under the optimum experimental conditions: traditional ball mill(200rpm, 1mm ball), planetary ball mill (500rpm, 1mm ball) and also planetary ball mill (700rpm, 1 and 3 mm ball). The results show to the development of new material using spherical type copper powder/CNT composites for air-craft and automotive applications.

• Korean Journal of Applied Biomechanics
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• v.23 no.1
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• pp.85-90
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• 2013

Efficient gait is compensate for a lack of exercise, but the wrong walking can cause disease that joints, muscles, brain and body structure(Scott & Winter, 1990). Also many researchers has been studied gait of positive mechanism using analytical methods kinetic, kinematic. This study is to identify nature of knee adduction moment, depending on different foot progression angle and the movement of rotation of pelvis and body. Health study subject conducted intended walking with three different angles. The subjects of this study classified three types of walking; walk erect, pigeon-toed walk and an out-toed gait. Ten university students of K without previous operation and disease record selected for this study. For accuracy of this study, three types of walking carried out five times with 3D image analysis and using analysis of ground reaction force to analyze nature of knee adduction moment and the movement of rotation of pelvis and body. Firstly, the HC(heel contact) section value of intended walk erect, pigeon-toed walk and an out-toed gait was not shown statistically significant difference but TO(toe off) section value was shown that the pigeon-toed walk statistically significant. The value of pigeon-toed walk was smallest knee adduction moment(p< 0.005). Secondly, X axis was the change of rotation movement body and pelvis when walk erect, pigeon-toed walk and an out-toed gait. Shown statistically Y axis was not shown statistically significant but Z axis statistically significant(p<0.05). These result show the significant differences on TO section when walking moment reaches HC, it decides the walking types and rotates the foot.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.1-10
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• 2002

This paper presents the new template based human face recognition methods to improve the recognition performance against scale and in-plane rotation variations of face images. To enhance the recognition performance, the templates are generated by linear or nonlinear operation on multiple images including different scales and rotations of faces. As the invariant features to allow for scale and rotation variations of face images, we adopt the affine transformation, the log-polar mapping, and the log-polar image based FFT. The proposed recognition methods are evaluated in terms of the recognition rate and the processing time. Experimental results show that the proposed template based methods lead to higher recognition rate than the single image based one. The affine transformation based face recognition method shows marginally higher recognition rate than those of the log-polar mapping based method and the log-polar image based FFT, while, in the aspect of processing time, the log-polar mapping based method is the fastest one.

• Clinics in Shoulder and Elbow
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• v.22 no.3
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• pp.135-138
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• 2019

Background: The aims of this study were (1) to examine the footprint of the subscapularis tendon using the traditional posterior portal and $30^{\circ}$ arthroscope by simple internal rotation of the arm during surgery, and (2) to classify the pattern of a subscapularis partial-thickness tear. Methods: This study analyzed a total of 231 patients with a partial-thickness subscapularis tear from 550 consecutive patients undergoing an arthroscopic operation who had a visualization of the subscapularis tendon footprint by internal rotation of the arm. First, the patients were classified into four categories according to the tear pattern: (1) stable lamination, (2) unstable lamination, (3) avulsion, and (4) laminated avulsion. Randomized arthroscopic videos were reviewed blindly by two independent orthopedic surgeons. The pattern of the tear of the subscapularis at the neutral position and after internal rotating the arm were assessed and compared with the treatment decision (level IV case series). Results: Stable lamination, unstable lamination, avulsion, and laminated avulsion were observed in 9.1% (n=21), 20.8% (n=48), 41.1% (n=95), and 29.0% (n=67) of cases, respectively. In 145 out of 231 cases (62.8%), the decision was changed after inspecting the footprint after internal rotation of the arm, and the treatment method was changed in 116 (50.2%) cases. Conclusions: In a subscapularis tendon partial-thickness tear, inspecting the footprint of the subscapularis tendon is essential to diagnosing and deciding on the appropriate treatment. In addition, simply internal rotating the arm during surgery when using the traditional posterior portal and $30^{\circ}$ arthroscope can be a valuable method.

• Geomechanics and Engineering
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• v.37 no.4
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• pp.383-393
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• 2024

Monopile foundations of offshore wind turbines embedded in soft clay are subjected to the long-term cyclic lateral loads induced by winds, currents, and waves, the vibration of monopile leads to the accumulation of pore pressure and cyclic strains in the soil in its vicinity, which poses a threat to the safety operation of monopile. The researchers mainly focused on the hysteretic stress-strain relationship of soft clay and kinds of stiffness degradation models have been adopted, which may consume considerable computing resources and is not applicable for the long-term bearing performance analysis of monopile. In this study, a modified cyclic stiffness degradation model considering the effect of plastic strain and pore pressure change has been proposed and validated by comparing with the triaxial test results. Subsequently, the effects of cyclic load ratio, pile aspect ratio, number of load cycles, and length to embedded depth ratio on the accumulated rotation angle and pore pressure are presented. The results indicate the number of load cycles can significantly affect the accumulated rotation angle of monopile, whereas the accumulated pore pressure distribution along the pile merely changes with pile diameter, embedded length, and the number of load cycles, the stiffness of monopile can be significantly weakened by decreasing the embedded depth ratio L/H of monopile. The stiffness degradation of soil is more significant in the passive earth pressure zone, in which soil liquefaction is likely to occur. Furthermore, the suitability of the "accumulated rotation angle" and "accumulated pore pressure" design criteria for determining the required cyclic load ratio are discussed.

• Journal of Korean Neurosurgical Society
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• v.30 no.2
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• pp.194-200
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• 2001

Object : Anterior cervical discectomy and fusion is accepted as appropriate surgical intervention for disease processes of the ventral cervical spine. In some cases, however, improvement of symptom following operation develop myelopathy or rhizopathy at longterm follow-up. We studied to clarify the correlation between clinical results and plain radiologic findings at long term follow-up. Methods : A total of 86 patients who underwent anterior cervical discectomy and fusion were grouped into deteriorated and good recovery group. These two groups were compared in lateral functional roentgenograms on the cervical kyphosis and disc height at fused level, sagittal plane rotation and dynamic sagittal canal diameter at adjacent level. Results : The presence of cervical kyphosis and disc height at fused level do not correlate with long term followup results. Sagittal plane rotation of more than 20 degrees were identified in 36% of the cases in deteriorated group, whereas the same findings were identified in 15% of the cases in good group. Sagittal diameter of less than 12mm were identified in 48% of the cases in deteriorated group, whereas the same finding were identified in 8% of the cases in good group. Preoperatively, sagittal plane rotation of more than 20 degrees at adjacent level were identified in 28% of the cases in deteriorated group, whereas the same findings were identified in 13% of the cases in good group. Preoperatively sagittal diameter of less than 12mm at adjacent level were identified in 40% of the cases in deteriorated group, whereas the same finding were identified in 7% of the cases in good group. Conclusion : Large sagittal plane rotation and small dynamic sagittal diameter at adjacent level were factors that might be associated with later clinical deterioration after cervical anterior fusion.