• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1301-1307
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• 2011

Electrosurgical knee wand (EKW) is a high-frequency thermocautery instrument and is often used for coagulation, ablation, excision, and extirpation of knee ligaments and tissues. In order to maximize the success rate, ease, and safety of knee surgery using EKW and radiofrequency ablation, it is necessary to ensure that the EKW selectively approaches the lesion with utmost accuracy and safety. The key feature of this instrument is its excellent maneuverability. Hence, the authors constructed a tensile spring model based on a shape memory alloy (SMA), which exhibits the shape memory effect. This model can be used in knee surgery as it is considered the most biocompatible femorotibial surgical actuator. The changes in external temperature with current and the thermoelectric characteristics of the SMA were investigated. The relationship between the restoring force and the typical stroke (TS) in response to the conditions in the SMA tensile spring design were evaluated. In conclusion, as the diameter of the SMA tensile spring decreased, the maximum temperature increased. The strain in the actuator caused a stable and proportional increase in the force and induced current for up to 15s, but this increase became very unstable after 30s. Moreover, the relationship between the current and the TS was more stable than that between the current and the restoring force.

• Journal of the Korean Orthopaedic Association
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• v.55 no.6
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• pp.527-533
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• 2020

Purpose: This study compared the effects of a buprenorphine transdermal patch (BTDP) on the chest and knee for pain control after total knee arthroplasty (TKA). Materials and Methods: A retrospective case-control study was conducted from August 2018 to August 2019 on 231 patients who underwent TKA. Two hundred cases were selected considering age, sex, and body mass index. Before and after applying the BTDP, the Numeric Rating Scale (NRS), adverse effects and compliance were measured. All measurements in the chest application group (group A=100) and knee application group (group B=100) were compared. Results: NRS was similar in rest between the groups treated with BTDP, but at two days and three days afternoon, five, six, and seven days postoperatively in group B, the NRS was significantly lower than that of group A. The adverse effects of the central nervous system and gastrointestinal system after applying BTDP were significantly lower in group B than in group A. No significant differences in adverse effects of the cardiovascular system and skin were observed between the two groups. Regarding the maintenance of BTDP, group B was significantly higher than group A. Conclusion: The direct application of BTDP after TKA to painful knee joints showed excellent results in early postoperative pain control and can be a useful method for increasing patient compliance by reducing the frequency of adverse effects.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.347.2-347
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• 2002

This paper presented a design and a Vibration control of a biped walking RGO(Robotic Gait Orthosis) and walking simulation by this system. The vibration evaluation of the Knee Joint Mechanism on the biped walking RGO(Robotic Galt Orthosis) was used to access by the 3-axis accelerometer with a low frequency vibration for the spinal cord injuries. It will be expect that the spinal cord injury patients are able to recover effectively by a biped walking RGO. (omitted)

• Korean Journal of Applied Biomechanics
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• v.23 no.2
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• pp.109-116
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• 2013

The purpose of this study was to provide fundamental information for the enhancement of performance through kinematic analysis of cornering according to the radius of curve course in short track speed skating. To perform this study, six skaters: three narrow radius players(N, body mass: $56.0{\pm}7.2$ kg, height: $163.7{\pm}5.1$ cm, age: $21.3{\pm}1.5$ yrs) and three wide radius players(W, body mass: $61.0{\pm}9.5$ kg, height: $169.0{\pm}4.4$ cm, age: $20.0{\pm}1.7$ yrs). Three-dimensional motion analysis was performed on the section from the forth block starting to show the change of radius to the sixth block using eight infrared cameras(sampling frequency of 100 Hz for N and W players). The time of push-off was greater for N than for W(p<.05) while the radius of center of mass was greater for W than for N(p<.05). The flexion and extension of knee and hip joint were greater for N than for W(p<.05). The external rotation of left knee joint was greater for N than for W(p<.05). Based on the findings, a small radius by increasing the range of the flexion and extension of knee and hip joint with greater external rotation of left knee joint would be related to more efficient run at curve. It is expected that these results will be useful in developing a training program for enhancing performance of short track speed skating athletes.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.3
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• pp.103-109
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• 2004

This paper has presented, taking an example of a gas separation plant, dynamic analysis on frequency decline caused by the over-loading at the generator and the knee point causing voltage instability due to reactive power required by re-acceleration of large induction motors, resulting in phenomena of failure in the conventional frequency load shedding. In order to resolve the voltage instability problem, a design of load shedding system employing under-voltage relays has been proposed to the industrial power system containing large induction motors in addition to the conventional load shedding employing frequency relays. For the purpose of dynamic analysis, models of gas turbine and governor, synchronous generator, brushless exciter, and induction motor are introduced.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.729-734
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• 2008

Vibroarthrographic(VAG) signals, emitted by human knee joints, are non-stationary and multi-component in nature and time-frequency distributions(TFD) provide powerful means to analyze such signals. The objective of this paper is to classify VAG signals, generated during joint movement, into two groups(normal and patient group) using the characteristic parameters extracted by time-frequency transform, and to evaluate the classification accuracy. Noise within TFD was reduced by singular value decomposition and back-propagation neural network(BPNN) was used for classifying VAG signals. The characteristic parameters consist of the energy parameter, energy spread parameter, frequency parameter, frequency spread parameter by Wigner-Ville distribution and the amplitude of frequency distribution, the mean and the median frequency by fast Fourier transform. Totally 1408 segments(normal 1031, patient 377) were used for training and evaluating BPNN. As a result, the average value of the classification accuracy was 92.3(standard deviation ${\pm}0.9$)%. The proposed method was independent of clinical information, and showed good potential for non-invasive diagnosis and monitoring of joint disorders such as osteoarthritis and chondromalacia patella.

• Journal of the Korean Arthroscopy Society
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• v.6 no.2
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• pp.177-182
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• 2002

Purpose : To validate the arthroscopic synovectomy for the treatment of hemophilic knee. Materials and Methods: From January 1996 to January 2001, 28 arthroscopic synovectolny were performed in 26 patients with hemophilic arthropathy of the knee. The mean age was 17.8 years. The mean follow-up period was 3 years 11 months. We used six portals (two anterior, two suprapatellar and two posterior) and posterior trans-septal portal in all cases. Result : The mean frequency of hemarthrosis was 4 times per month preoperatively and 2 postoperatively. The mean amount of factor replacement was 4,633 units preoperatively and 1,505 postoperatively. The mean range of motion was $112^{\circ}$ preoperatively and $107^{\circ}$ postoperatively. On radiographic evaluation, three cases were progressed at the latest follow-up. On the subjective evaluation, significant or moderate improvement were in 19 cases $(68\%)$, and no improvement or deterioration in 9 cases $(32\%)$. Conclusion : With complete synovectomy through the appropriate arthroscopic portals, arthroscopic synovectomy of the knee in hemophilic patients is the successful method in decreasing bleeding episodes, amount of factor replacement, knee pain and preventing or delaying onset of end-stage hemophilic arthropathy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.691-700
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• 2016

This study was performed to provide data for developing a more effective and practical pilates exercise program for young women. To meet this purpose, 20 young women were assigned to both groups. The experiment was conducted according to the experimental procedure. Ten subjects in the pilates exercise group performed exercise for 60 minutes everyday at a frequency of 3 days per week for 8 weeks. The subjects in both groups were measured for their physical composition, isokinetic muscular strength in legs, and body balance before and after the experiment. After 8 weeks, the pilates exercise group's body composition showed significantly increased muscular amount (p <.01). There was a statistical increase in knee joint muscle function. For the right knee joint and left knee joint, right knee joint extensor muscle's maximum muscular strength and total work significantly increased under conditions of $60^{\circ}/sec$ (p<.05). Under conditions of $180^{\circ}/sec$, there were statistically significant increases in left knee joint flexor muscle's maximum muscular strength (p<.05). For balance, balance of both legs and right leg showed statistically increases (p<.05).

• Progress in Medical Physics
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• v.19 no.4
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• pp.269-275
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• 2008

Although MR imaging is generally applicable to depict knee joint deterioration it, is sometimes occurred to mis-read and mis-diagnose the common knee joint diseases. In this study, we employed magnetization transfer ratio (MTR) method to improve the diagnosis of the various knee joint diseases. Spin-echo (SE) T2-weighted images (TR/TE 3,400-3,500/90-100 ms) were obtained in seven cases of knee joint deterioration, FSE T2-weighted images (TR/TE 4,500-5,000/100-108 ms) were obtained in seven cases of knee joint deterioration, gradient-echo (GRE) T2-weighted images (TR/TE 9/4.56/$50^{\circ}$ flip angle, NEX 1) were obtained in 3 cases of knee joint deterioration, In six cases of knee joint deterioration, fat suppression was performed using a T2-weighted short T1/tau inverse recovery (STIR) sequence (TR/TE =2,894-3,215 ms/70 ms, NEX 3, ETL 9). Calculation of MTR for individual pixels was performed on registration of unsaturated and saturated images. After processing to make MTR images, the images were displayed in gray color. For improving diagnosis, three-dimensional isotropic volume images, the MR tristimulus color mapping and the MTR map was employed. MTR images showed diagnostic images quality to assess the patients' pathologies. The intensity difference between MTR images and conventional MRI was seen on the color bar. The profile graph on MTR imaging effect showed a quantitative measure of the relative decrease in signal intensity due to the MT pulse. To diagnose the pathologies of the knee joint, the profile graph data was shown on the image as a small cross. The present study indicated that MTR images in the knee joint were feasible. Investigation of physical change on MTR imaging enables to provide us more insight in the physical and technical basis of MTR imaging. MTR images could be useful for rapid assessment of diseases that we examine unambiguous contrast in MT images of knee disorder patients.

• Journal of the Korean Orthopaedic Association
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• v.55 no.2
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• pp.117-126
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• 2020

Total knee arthroplasty is performed widely in degenerative arthritis of the knee joint, and the frequency of use is increasing. Efforts should be made to achieve functional recovery, such as returning to daily life, and the recovery of strength and range of motion after surgery. The procedure should be approached from a range of perspectives, such as patient factors, surgical technique and rehabilitation. The patient's age, degree of obesity, sex, and strength of the quadriceps muscle can affect the functional recovery after surgery. In addition, the patient's mental state, such as expectation value and satisfaction, can also have an effect. For functional recovery, patient education, pain control, and strengthening of the quadriceps muscle can be performed prior to surgery. Postoperative physiotherapy, such as icing and compression, transcutaneous electrical nerve stimulation therapy, neuromuscular electrical stimulation therapy, low frequency low intensity magnetic field therapy, strengthening of quadriceps muscle, and range of motion exercise can also be applied. In recent years, hydrotherapy, which restores the strength and balance of the leg, is being performed increasingly. These treatments are not only performed shortly after surgery, but are also performed continuously. In addition, the surgeon should apply it appropriately considering the patient's condition, compliance, and social and psychological conditions.