• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.4
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• pp.44-48
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• 2006

Recently, demand the ultra precision product which is increasing rapidly is used extensively frontier industry field such as semi-conductor, computer, aerospace, precision machine. Ultra precision processing is the portion that is very needed to NT in the field of mechanical engineering. The latest date, together with radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts those are connected with these industrial fields. Specially, require motion accuracy of high resolution of nm order in stroke of hundreds millimeters according as diameter of processing object great and processing accuracy rises. In this case ,the response speed absolute delay because inertial mass of moving part is very large. Therefore, real time motion error compensation becomes very hardly. In this paper, we used ultra precision cutting unit(UPCU) to cope such problem. a UPCU is designed and tested to obtain sub-micrometer from accuracy in diamond turning of flat surfaces. The thermal growth spindle error is compensated for real time using a UPCU driven by piezoelectric actuator along with a laser encoder displacement sensor.

• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.109-117
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• 2018

Objective: To compare head and hand movement patterns during squash forehand motions between experts and less-skilled squash players. Method: Four experts and four less-skilled squash players participated in this study. They performed squash forehand swings and a VICON motion analysis system was used to obtain displacement and velocity data of the head and right hand during the movement. Mann-Whitney U-tests were performed to compare head and hand range of motion and peak velocity, and cross-correlation was performed to analyze the head-hand coordination pattern between groups in three movement directions. Results: In terms of head and hand kinematic data, experts had greater head range of motion during down swings than less-skilled squash players. Experts seemed to reach peak hand velocity at impact by reaching peak head velocity followed by hand peak velocity within a given temporal sequence. In terms of head-hand coordination patterns, both groups revealed high positive correlations in the medial-lateral direction, indicating a dominant allocentric coordination pattern. However, experts had uncoupled coordination patterns in the vertical direction and less-skilled squash players had high positive correlations. These results indicate that the head-hand movement pattern likely an important factor squash forehand movement. Conclusion: Analysis of head and hand movement patterns could be a key variable in squash training to reach expert-level performance.

• Physical Therapy Korea
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• v.13 no.3
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• pp.84-91
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• 2006

The purpose of this study was to investigate the effect of submerged relaxation therapy for the spasticity on the affected side in three subjects with post-stroke hemiparesis. A single-subject alternating design with multiple baselines across individuals was employed in this study. Each subject alternately participated in a range of motion exercises on the mat and in the pool, and relaxation exercises in the pool. The muscle tone of the affected side was measured using the tone assessment scale (TAS). Measurements were made immediately and one hour following the intervention. The findings showed a therapeutic effect of submerged relaxation exercise on reducing spasticity for all subjects. The effect of submerged relaxation exercise on decreasing muscle tone was maintained for one hour measurements after the submerged relaxation exercise, although the mean TAS score assessed one hour after intervention was higher than that assessed immediately. The results of this study suggest that submerged relaxation exercise has a positive effect on decreasing spasticity on the affected side in persons suffering from post-stroke hemiparesis. Future research on submerged relaxation exercise should focus on objective evaluation and functional the aspects relevant to activities of daily living.

• Physical Therapy Korea
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• v.19 no.3
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• pp.20-30
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• 2012

The purpose of this study was to determine the effect of ankle joint mobilization with movement (MWM) on the range of motion (ROM) in the ankle, on the muscle strength of lower extremities, and on spatiotemporal gait parameters in chronic hemiplegic patients. Fifteen subjects with chronic stroke were divided into two groups: an experimental group (8 subjects) and a control group (7 subjects). Both groups attended two or three sessions of physical therapy each week. The experimental group also attended additional MWM training sessions three times a week for five weeks. For both groups, the ROM of the ankle, the muscle strength of the lower extremities, and the spatiotemporal gait parameters in paretic limbs were evaluated before and after the training period. The results showed that the experimental group experienced more significant increases than did the control group in terms of passive (6.10%) and active (21.96%) ROM of the ankle, gait velocity (12.96%), and peak torque, of the knee flexor (81.39%), the knee extensor (24.88%), and the ankle plantar flexor (41.75%)(p<.05). These results suggest that MWM training in patients with chronic stroke may be beneficial in increasing ROM in the ankle, muscle strength in the lower extremities, and gait speed.

• Investigative Magnetic Resonance Imaging
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• v.21 no.1
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• pp.20-27
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• 2017

Purpose: To evaluate quantification results of single breath-hold (SBH) magnetic resonance (MR) cine imaging compared to results of conventional multiple breath-hold (MBH) technique for left ventricular (LV) function in patients with cardiac arrhythmia. Materials and Methods: MR images of patients with arrhythmia who underwent MBH and SBH cine imaging at the same time on a 1.5T MR scanner were retrospectively reviewed. Both SBH and MBH cine imaging were performed with balanced steady state free precession. SBH scans were acquired using temporal parallel acquisition technique (TPAT). Fifty patients ($65.4{\pm}12.3years$, 72% men) were included. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), myocardial mass, and LV regional wall motion were evaluated. Results: EF, myocardial mass, and regional wall motion were not significantly different between SBH and MBH acquisition techniques (all P-values > 0.05). EDV, ESV, and SV were significant difference between the two techniques. These parameters for SBH cine imaging with TPAT tended to lower than those in MBH. EF and myocardial mass of SBH cine imaging with TPAT showed good correlation with values of MBH cine imaging in Passing-Bablok regression charts and Bland-Altman plots. However, SBH imaging required significantly shorter acquisition time than MBH cine imaging ($15{\pm}7sec$ vs. $293{\pm}104sec$, P < 0.001). Conclusion: SBH cine imaging with TPAT permits shorter acquisition time with assessment results of global and regional LV function comparable to those with MBH cine imaging in patients with arrhythmia.

• Korean Journal of Applied Biomechanics
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• v.26 no.4
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• pp.333-341
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• 2016

Objective: The purpose of this study was to assess the consistency of the gliding and push-off motion for single leg skating from the first to fourteenth steps. We hypothesized that: 1) there would be no difference in stroke trajectory, step rate, and cycle rate between the left and right steps of gliding; and 2) there would be a difference in the resultant velocity of toe push-off and the horizontal velocity of the center of mass after six step push-offs. Method: The study included five male 500-m speed skaters (mean height, $1.80{\pm}0.02m$; mean weight, $76.8{\pm}3.96kg$; record, $35.83{\pm}0.30sec$; 100-m record, <9.97 sec). Data were collected from the first to fourteenth steps (40 m) and recorded using five digital JVC GR-HD1KR video cameras (Victor Co., Japan) operating at a sampling frequency of 60 fields/sec and shutter speed of 1/500 sec. For each film frame, the joint positions were digitized using the KWON3D motion analyzer. Position data were filtered with low-pass Butterworth $4^{th}$ order at the cut-off frequency of 7.4 Hz. Results: The right toe of the skating trajectories at $2^{nd}$, $5^{th}$, and $7^{th}$ strokes differed from those of the left toe. The angles of the right and left knee demonstrated unbalanced patterns from the flexion and extension legs. The step and cycle rates of the right and left leg differed from the start until 20 m. The resultant velocities of the toe at the push-off phase and of the body mass center diverged before the six push-offs. Conclusion: This study's findings indicate that the toe of skating trajectory on left and right sliding after push-off should maintain a symmetrical trajectory. The resultant velocity of toe push-off and horizontal velocity from the center of body need to be separated after about six step push-offs.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.957-964
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• 2020

T2 FLAIR sequence of MRI in Acute Ischemic Stroke patients is meaningful to those who have the diagnosis of cerebral hemorrhage and neurological deficiency, including the detection of cerebral infarction around Cerebrospinal fluid. However, because of the long acquisition time and mutative motion artifacts caused by movement, It is difficult to take the MRI image acquisition for non-cooperative patients who need to apply a rapid image acquisition. In this study, we applied the EPI-FLAIR sequence, which is one of the fastest pulse sequences in use, which is a combination of EPI sequence and T2 FLAIR sequence, to patients with acute ischemic cerebral infarction. Based on the qualitative and quantitative evaluation results of the EPI-FLAIR and T2 FLAIR image, we will evaluate the diagnostic usefulness of the EPI-FLAIR sequence.

• Korean Journal of Acupuncture
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• v.25 no.2
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• pp.125-141
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• 2008

Objective : The aim of this study is to investigate the curative effect of Bee Venom Acupuncture Therapy for pain and limited R.O.M (range of motion) of shoulder in stroke patients. Methods : The subjects of this study were 6 patients with shoulder pain in stroke sequelae. Routine Oriental Medical programs (Acupunture, moxibustion, herbal medicine and physical therapy) were maintained for each subject throughout this study. Single subject ABABAB design was adopted. Each period was 4 days as a rule. Only during the treatment period, Bee Venom Acupuncture Therapy was provided as intervention at the acupoints of LI15(Gyeonu),　TE14(Gyeollyo), GB21(Gyeonjeong), LI14(Bino). The change of pain was measured with a Visual Analogue Scale(VAS). The pain threshold was measured using pressure algometer at the same acupoints where Bee Venom Acupuncture Therapy was provided. And the R.O.M of shoulder joint (flexion, extension, abduction, adduction, external rotation, internal rotation) was measured as well. Analysis was performed by Bayesian analysis using WinBUGS for the comparison of treatment(Bee Venom Acupuncture Therapy) and non-treatment. Results : The median overall improvement for difference in VAS was -2.219(-3.213, -1.175), for difference in external rotation of shoulder R.O.M was 9.992(-2.298, 18.49), for difference in tenderness score of LI14(Bino) by pressure algometer was 5.05(0.6283, 7.762). 95% credibility intervals being shown in brackets. However, the median overall improvement for difference in the other measurements was not significant. Conclusion : This study suggests that Bee Venom Therapy may be applicable to decrease pain and improve R.O.M of shoulder in hemiplegia patients with stroke. Further elaborated single subject designs need to be accumulated to confirm the effects of Bee Venom Acupunture Therapy on shoulder pain in patients with stroke sequelae.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5867-5874
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• 2012

The aim of this study was to find on muscle architectural and tissue compliance of biceps brachii in stroke patient based on elbow joint angle. The subjects of this study were twelve hemiplegic adults after stroke with passive range of motion in the elbow from $10^{\circ}$ to $90^{\circ}$ and Modified Ashworth Scale score 1 to 3 were recruited. Ultrasonography and Myotonometer was used to measure biceps brachii muscle pennation angle, fascicle length, and tissue compliance at the rest condition and pennation angle, fascicle length, and tissue compliance of the biceps brachii muscle were measured in the affected and unaffected sides of people after stroke at 9 different elbow angles ranging from $10^{\circ}$ to $90^{\circ}$ at the rest condition. The results of this study, comparisons found that the pennation angles of the affected biceps brachii muscle were significantly larger(p<.05) than the unaffected muscle in the most extended positions($<40^{\circ}$), whereas the affected fascicle lengths were significantly shorter(p<.05) than the unaffected muscle in most flexed positions($>20^{\circ}$), and the affected tissue compliance were significantly lower(p<.05) than the unaffected muscle in most extended positions($<50^{\circ}$) Therefore, pennation angles, fascicle lengths, and tissue compliance were found to be joint-angle-dependent in both the affected and unaffected sides at the rest condition. Suggest that, the results data can be used as a muscle architectural changes and clinical treatment research in stroke patients.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.217-226
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• 2007

Putting score counts about 43 % of the golf score. The dominant idea of the putting motion to amateur golfers as well as to many professional golfers is a pendulum-like motion. If a golfer's putting stroke motion is a pendulum-like motion, the putting motion should be straight-back-and-through, the same backswing, downswing, and follow through length and period, and a swing with a fixed hinge joint. If the putting motions of the human are different from the pendulum motion, there could be confusion in understanding and teaching golf putting. The purpose of this study was to examine the center of rotation(COR) of the putter head to reveal whether professional golfers really putt like a pendulum. Thirteen male professional golfers were recruited for the study. Each golfers executed 10.94 m putts six times on an artificial grass mat. Putter head position data were collected through a 60 Hz three-dimensional motion analysis system and low pass filtered with cut-off frequency of 6 Hz. COR of the putter head was mathematically acquired. Each golfer's last five putting motions were considered. The results show that the COR of the putter head was neither fixed nor located inside of the golfer. The medio-lateral directional component of the COR of the putter head fluctuated in the range of 10 cm during downswing and follow through. The anterior-posterior directional component of the COR of the putter head was fixed from the beginning of the downswing through impact. Just after impact, however, it moved to the target up to 60 cm. The superior-inferior directional component of COR of the putter head moved in a superior direction with the beginning of the downswing and showed peak height just prior to impact. During the follow through, it moved back in an inferior direction. The height-normalized peak value of the COR of the putter head was $1.4{\pm}0.3$ height. Technically speaking, male professional golfers' 10.94 m putting motion is not a pendulum-like motion. The dominating idea of a pendulum-like motion in putting might come from the image of the flawless, smooth motion of a pendulum.