• Title/Summary/Keyword: Screw motion

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Dynamic Models of Blade Pitch Control System Driven by Electro-Mechanical Actuator (전기-기계식 구동기를 이용한 블레이드 피치 조종 시스템의 동역학 모델)

  • Jin, Jaehyun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.2
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    • pp.111-118
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    • 2022
  • An electro-mechanical actuator (EMA) is an actuator that combines an electric motor with a mechanical power transmission elements, and it is suitable for urban air mobility (UAM) in terms of design freedom and maintenance. In this paper, the author presents the research results of the EMA that controls the rotor blade pitch angle of UAM. The actuator is based on an inverted roller screw and controls the blade pitch angle through a two-bar linkage. The dynamic equations for the actuator alone and the blade pitching motion with actuator were derived. For the latter, the equivalent moment of inertia is variable depending on the link angle due to the two-bar linkage. The variations of the equivalent moments of inertia are analyzed and compared in terms of the nut motion and the blade pitch motion. For an example model, the variation of the equivalent moment of inertia of the former is smaller than the latter, so it is judged that the dynamic equations derived from the point of view of the nut motion is suitable for the controller design.

Screw Fixation Techniques for Talar Neck Fractures (Anterior versus Posterior insertion) (거골 경부 골절의 나사못 고정 방향에 따른 결과 비교)

  • Shin, Dong-Eun;Yoon, Hyung-Ku;Choi, Woo-Jin;Lee, Yoon-Seok;Han, Seung-Chul
    • Journal of Korean Foot and Ankle Society
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    • v.14 no.1
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    • pp.79-83
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    • 2010
  • Purpose: To compare the clinical and radiological results between the anterior and posterior screw fixation for the treatment of talar neck fracture. Materials and Methods: Among 30 patients who received surgical treatment for talar neck fracture from 2001 to 2008. Twenty-seven patients with a follow-up period of more than 1 year were divided into two groups. Twelve patients were treated with anterior screw fixation and 15 patients with posterior approaches. We analyzed preoperative, postoperative and follow-up radiographs. Clinical results were evaluated by Hawkins criteria. Results: The posteriorly inserted screws were placed across the more central portion of the talar neck and perpendicular to the plane of fracture (p<0.05). There were no difference in clinical results, the duration of union, and complications including avascular necrosis between two groups. However, 2 patients complained of pain around the talonavicular joint in the anterior insertion group. Conclusion: Although the clinical results were good irrespective of insertion methods, the posterior approach of screw fixation for talar neck fractures allows for a better mechanical advantage than anterioly placed screws. This may allow early motion with a reduced risk of failure of fixation or of displacement of the fracture.

Comparative Study on Biomechanical Behavior of Various Cervical Stand-Alone Cage Designs (경추용 일체형 추간체 유합 보형재의 디자인 변화에 따른 생체역학적 효과 비교 연구)

  • Park, Kwang Min;Jung, Tae Gon;Jeong, Seung Jo;Lee, Sung Jae
    • 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.

Open Reduction of Acromioclavicular Joint for the Acromioclavicular Joint Dislocations (견봉 쇄골 관절 탈구에 대한 견봉 쇄골 관절의 관혈적 정복술)

  • Song, Hyun-Seok;Choi, Nam-Yong;Han, Suk-Ku;Nah, Ki-Ho;Nam, Won-Sik;Yang, Hyuk-Jae;Park, Sung-Jin
    • Clinics in Shoulder and Elbow
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    • v.9 no.2
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    • pp.189-195
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    • 2006
  • Purpose: To analyze the result of the accurate open reduction of acromioclavicular (AC) joint and pin fixation, coracoclavicular (CC) screw fixation without CC ligament repair for AC joint injuries. Materials and Methods: Between January 2000 and December 2003, seventeen cases with at least one year follow-up among twenty-one cases underwent operation for AC-CC ligament injuries. A transverse incision approximately 5 cm in length was made over the clavicle, and the AC joint was reduced accurately. Under the image intensifier, a cannulated screw and washer were inserted for the CC ligament. Two Steinman pins were inserted for the AC joint and the AC ligament was repaired with nonabsorbable suture. Gentle passive range of motion was begun postoperative 2 weeks. The pins were removed at $6{\sim}8$ weeks and the screw was removed at $10{\sim}12$ weeks. The results were evaluated by a distance between AC and CC joints on plain films and ASES score at last follow-up. Results: At the last follow-up, there was no limitation of motion and average ASES score was 96($86{\sim}100$ points). There was no failure showing over 5 mm difference of distance compared to opposite side on the plain films. Seven cases had the skin damages and local infection due to pin migration and three cases showed the loosening of CC screw. Conclusion: We could have satisfactory results by accurate reduction of AC joint and simple pins and screw fixation for AC-CC ligament injuries.

Tenodesis of Long Head of the Biceps Brachii Tendon with Bioabsorbable Interference Screw (체내 흡수성 간섭 나사를 이용한 상완 이두건 장두건 고정술의 임상적 결과)

  • Yum, Jae-Kwang;Sin, Yong-Woon;Lee, Sang-Jin
    • Clinics in Shoulder and Elbow
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    • v.10 no.1
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    • pp.78-83
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    • 2007
  • Purpose: This study reports the clinical results of the tenodesis of long head of the Biceps brachii tendon with bioabsorbable interference screw by minimal open procedure. Materials and Methods: Ten cases of 10 patients (7 male, 3 female) were included in this study. The average age was 45.8 years old and the average period from the symptom onset to operation was 13.7 months. Average preoperative ASES score was 38.5. The causes of injury was; sports activities in 4 patients, unknown in 4 patients, industrial accident in 1 patient and traffic accident in 1 patient. The average follow up period was 12.1 months. Tenodesis with bioabsorbable interference screw by minimal open precedure was performed in all cases. Results: The ASES score improved to 87.5 at last follow up period and 6 cases had full range of motion of the shoulder. 4 cases had mild limited range of motion of the shoulder without any problem in normal daily activity. Conclusion: It was assumed that tenodesis of long head of the biceps brachii tendon with bioabsorbable interference screw by minimal open precedure was one of the good methods with good clinical results.

The Distal Metatarsal Dorsal-Wedge Osteotomy Using Bio-Compression Screw for Advanced Hallux Rigidus (진행된 무지 강직증에서 생체흡수성 압박나사를 이용한 원위 중족골의 배측 쐐기 절골술)

  • Kim, Yong-Min;Cho, Byung-Ki;Kim, Dong-Soo;Choi, Eui-Sung;Shon, Hyun-Chul;Park, Kyoung-Jin;Park, Ji-Kang;Choi, Seung-Myung
    • Journal of Korean Foot and Ankle Society
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    • v.16 no.1
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    • pp.38-46
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    • 2012
  • Purpose: This study was performed retrospectively to evaluate clinical outcomes of distal metatarsal osteotomy using bio-compression screw as the joint preservation method for advanced hallux rigidus. Materials and Methods: Eleven cases were followed up for more than 1 year after distal metatarsal dorsal wedge osteotomy for advanced hallux rigidus. The clinical evaluation was performed according to the American Orthopaedic Foot and Ankle Society (AOFAS) score and patient's satisfaction score. The range of motion, and the period to return to running exercise, tip-toeing gait, squatting, walking down the stairs were evaluated. As the radiographic evaluation, the interval of $1^{st}$ MTP (metatarsophalangeal) joint space and the period to union were measured. Results: The AOFAS hallux score had improved significantly from preoperative average 50.7 points to 87.6 points at the last follow-up (p=0.005). The subjective satisfaction score was average 90.6 points. There were no case of subsequent fusion or additional operation, and no complication associated with bio-compression screw. The period to return to running exercise, tip-toeing gait, squatting, walking down the stairs were average of 24.8 weeks, 20.4 weeks, 16.8 weeks, 18.5 weeks respectively. Dorsiflexion of $1^{st}$ MTP joint had improved significantly from preoperative average $17.5^{\circ}$ to $44^{\circ}$ (p<0.001). All cases achieved union of osteotomy site, and the period to union was average 10.4 weeks. The interval of $1^{st}$ MTP joint space had improved significantly from preoperative average 1.2 mm to 3.5 mm (p=0.014). Conclusion: Distal metatarsal osteotomy using bio-compression screw seems to be one of effective treatment methods for advanced hallux rigidus, because of restoration of the first MTP joint motion, and reliable pain relief, and needlessness of hardware removal.

COMPARISON OF SCREW-IN EFFECT FOR SEVERAL NICKEL-TITANIUM ROTARY INSTRUMENTS IN SIMULATED RESIN ROOT CANAL (모형 레진 근관에서 수종의 전동 니켈-티타늄 파일에 대한 screw-in effect 비교)

  • Ha, Jung-Hong;Jin, Myoung-Uk;Kim, Young-Kyung;Kim, Sung-Kyo
    • Restorative Dentistry and Endodontics
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    • v.35 no.4
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    • pp.267-272
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    • 2010
  • Screw-in effect is one of the unintended phenomena that occurs during the root canal preparation with nickel-titanium rotary files. The aim of this study was to compare the screw-in effect among various nickel-titanium rotary file systems. Six different nickel-titanium rotary instruments (ISO 20/.06 taper) were used: $K3^{TM}$ (SybronEndo, Glendora, CA, USA), $M_{two}$ (VDW GmbH, Munchen, Germany), NRT with safe-tip and with active tip (Mani Inc., Shioya-gun, Japan), ProFile$^{(R)}$ (Dentsply-Maillefer, Ballaigues, Switzerland) and ProTaper$^{(R)}$ (Dentsply-Maillefer, Ballaigues, Switzerland). For ProTaper$^{(R)}$, S2 was selected because it has size 20. Root canal instrumentations were done in sixty simulated single-curved resin root canals with a rotational speed of 300 rpm and single pecking motion. A special device was designed to measure the force of screw-in effect. A dynamometer of the device recorded the screw-in force during simulated canal preparation and the recorded data was stored in a computer with designed software (LCV-USE-VS, Lorenz Messtechnik GmbH, Alfdorf, Germany). The data were subjected to one-way ANOVA and Tukey's multiple range test for post-hoc test. P value of less than 0.05 was regarded significant. ProTaper$^{(R)}$ produced significantly more screw-in effects than any other instruments in the study (p < 0.001). $K3^{TM}$ produced significantly more screw-in effects than $M_{two}$, and ProFile$^{(R)}$ (p < 0.001). There was no significant difference among $M_{two}$, NRT, and ProFile$^{(R)}$ (p > 0.05), and between NRT with active tip and NRT with safe one neither (p > 0.05). From the result of the present study, it was concluded, therefore, that there seems significant differences of screw-in effect among the tested nickel-titanium rotary instruments. The radial lands and rake angle of nickel-titanium rotary instrument might be the cause of the difference.

Evaluation of manual workload in repetitive wrist and finger motion (반복적인 손목 및 손가락 작업에서의 수작업 부하 평가)

  • Gwon, O-Chae;Yun, Myeong-Hwan
    • Journal of the Ergonomics Society of Korea
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    • v.18 no.2
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    • pp.103-120
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    • 1999
  • The purpose of this study was to evaluate the manual workload in repetitive wrist and finger motion. To evaluate manual workload, angular displacement of the joint, EMG of the muscle and subjective rating were studied. Both wrist motion and finger motion were studied. A screw-driving task was used for the wrist motion experiment. A keyboard typing task was used for the finger motion experiment. All finger joint angles and wrist angles were measured by an angle-measuring glove($CyberGlove^{TM}$, Virtual Technologies, Inc.). Surface EMG was recorded from FCU muscle and FDS muscle simultaneously with the angle measurement. Subjective ratings of exertion were also recorded using the modified Borg's CR-10 scale. Repetition rates of 0.5, 1, 2 motions per second were used with each task. As a result, manual workload increased with increasing repetitiveness. Peak spectral magnitude and frequency components corresponded closely with joint angular displacement amplitudes and repetition rates. Results of the correlation analysis showed that there were significant correlation among EMG, frequency-weighted motion and subjective measurement. Both EMG and frequency-weighted filtering showed consistent workload estimation with increasing task frequency. Subjective ratings showed slight over-estimation of the workload as the task frequency is increased.

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Influence of taper on the screw-in effect of nickel-titanium rotary files in simulated resin root canal (모형 레진근관에서 니켈-티타늄 전동 파일의 경사도가 screw-in effect에 미치는 영향)

  • Sung, Hye-Jin;Ha, Jung-Hong;Kim, Sung-Kyo
    • Restorative Dentistry and Endodontics
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    • v.35 no.5
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    • pp.380-386
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    • 2010
  • Objectives: The introduction of nickel-titanium alloy endodontic instruments has greatly simplified shaping the root canal systems. However, these new instruments have several unexpected disadvantages. One of these is tendency to screw into the canal. In this study, the influence of taper on the screw-in effect of the Ni-Ti rotary instrument were evaluated. Materials and Methods: A total of 20 simulated root canals with an S-shaped curvature in clear resin blocks were divided into two groups. ProFile .02, .04, .06 (Dentsply-Maillefer) and GT rotary files .08, .10, .12 (Dentsply) were used in Profile group, and K3 .04, .06, .08, .10, and .12 (SybronEndo, Glendora) were used in K3 group. Files were used with a single pecking motion at a constant speed of 300 rpm. A special device was made to measure the force of screw-in effect. A dynamometer of the device recorded the screwin force during simulated canal preparation and the recorded data was stored in computer with designed software. The data were subjected to one-way ANOVA and Tukey's multiple range test for post-hoc test. p value of less than 0.05 was regarded significant. Results: The more tapered instruments generated more screw-in forces in Profile group (p < 0.05). In K3 group, 0.08, 0.10. and 0.12 tapered instruments showed more screw-in force than 0.04 tapered one, and 0.08 and 0.12 tapered instruments showed more screw-in force than 0.06 tapered one (p < 0.05). Conclusions: The more tapered instruments seems to produce more screw-in force. To avoid this screw-in force during instrumentation, more attention may be needed when using more tapered instruments.

Surgical Treatment of Type II Talar Neck Fractures (제 2형 거골 경부 골절의 수술적 치료)

  • Jeon, Taek-Soo;Kim, Sang-Bum;Kim, Sung-Hun;Kim, Tae-Kyun;Kim, Seung-Hwan
    • Journal of Korean Foot and Ankle Society
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    • v.11 no.1
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    • pp.91-96
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    • 2007
  • Purpose: To evaluate the clinical results and determine appropriate methods of surgical treatment about type II talar neck fracture. Materials and Methods: Among nineteen patients who received surgical treatment for type II talar neck fracture from May 2000 to May 2005. Fourteen patients with a follow-up period of more than 1 year were divided into two groups. Six patients reduced by closed reduction (Group A) with screw fixation and eight patients reduced by open reduction with screw fixation. We analyzed preoperative, postoperative and follow-up simple radiographs and reviewed patient hospital records retrospectively. Clinical results were evaluated by Hawkins scoring system. We analyzed pain, limp, range of motion of ankle and subtalar joint. Results: Five patients (83.3%) in group A and seven patients (87.7%) in group B had excellent and good clinical results. There were no complications including avascular necrosis, delayed union, nonunion. Conclusion: Closed reduction with screw fixation of talar neck fracture shows correct reduction and satisfactory results. But because of short term period of follow-up, we need long term results.

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