• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.659-664
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• 2000

In this paper, We have discussed on the modeling of machined outer geometry which was established for the case of round shape machining, also the effects of externally machined profile are analyzed and its modeling realiability was verified by the experiments of roundness testing, especially in lathe operation. In this study, we established harmonic geometric model with the parameter harmonic function. In general, we can calculate the theoretical roundness profile with arbitrary multilobe parameter. But in real experiments, only 2-5 lobe profile was frequently measured. the most frequently ones are 3 and 5 lobe profile in experiments. With this results, we can predict that these results may be applies to round shape machining such as turning, drilling, boring, ball screw and cylindrical grinding operation in bearing and shaft making operation with the same method. In this study, simulation and experimental work were performed to show the profile behaviors. we can apply these new modeling method in real process for the prediction of part profile behaviors machined such as in round shape machining operation.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권5호
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• pp.525-536
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• 2017

Course keeping is hard to implement under the condition of the propeller stopping or reversing at slow speed for berthing due to the ship's dynamic motion becoming highly nonlinear. To solve this problem, a practical Maneuvering Modeling Group (MMG) ship mathematic model with propeller reversing transverse forces and low speed correction is first discussed to be applied for the right-handed single-screw ship. Secondly, a novel PID-based nonlinear feedback algorithm driven by bipolar sigmoid function is proposed. The PID parameters are determined by a closed-loop gain shaping algorithm directly, while the closed-loop gain shaping theory was employed for effects analysis of this algorithm. Finally, simulation experiments were carried out on an LPG ship. It is shown that the energy consumption and the smoothness performance of the nonlinear feedback control are reduced by 4.2% and 14.6% with satisfactory control effects; the proposed algorithm has the advantages of robustness, energy saving and safety in berthing practice.

• 제어로봇시스템학회논문지
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• 제20권10호
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• pp.1067-1072
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• 2014

The ability to overcome obstacles is necessary for field robots for various applications including the ability to climb stairs. While much research has been performed focusing on overcoming obstacles, the resulting robots do not have sufficient ability to overcome obstacles such as stairs. In this research, the purpose is to overcome relatively large obstacles by flipping locomotion through the modification of the stair climbing robotic platform of the previous research. We propose two scenarios to overcome large obstacles: a rear wheel driving system and an elevation system using a ball screw. The research is performed based on static analyses on obstacle-climbing. As the simulation results indicate, we determined the optimal posture of the robot for climbing obstacles for rear wheel driving. Also, an elevation system is analyzed for obstacle climbing. Between the two scenarios an elevation system is determined to reduce the operating torque of the actuator, and the prototype was recently assembled. The climbing ability of the robotic platform is verified. We expect the application area for this robotic platform will be in accident areas of nuclear power plants.

• 한국기계가공학회지
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• 제16권5호
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• pp.19-24
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• 2017

In this research, a practical stiffness calculation method is developed and applied for modifying the height of the headstock, turret, and tailstock of a CNC lathe to enlarge the turntable diameter. The casting structure is assumed to be a rigid body and the linear motion element to be an elastic spring to simplify the turret stiffness calculation model. The stiffness of the sliding guide and ball screw of the original lathe is measured with a push tester and LVDT sensor, and the turret stiffness of the modified lathe is predicted and compared with experimental results to verify the model. The measured stiffness of the original turret is $0.17kN/{\mu}m$ and that of the modified turret is $0.11kN/{\mu}m$, i.e., an 18% difference from the predicted result. The verified stiffness calculation model can be used to develop another modified lathe.

• 로봇학회논문지
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• 제10권2호
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• pp.119-132
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• 2015

Two novel parallel mechanisms (PMs) employing two or three PaPaRR subchains are suggested. Each of those two PMs has translational 3-DOF motion and employs only revolute joints such that they could be adequate for haptic devices requiring minimal frictions. The position analyses of those two PMs are conducted. The mobility analysis, the kinematic modeling, and singularity analysis of each of two PMs are performed employing the screw theory. Then through optimal kinematic design, each of two PMs has excellent kinematic characteristics as well as useful workspace size adequate for haptic applications. In particular, by applying an additional redundantly actuated joint to the 2-PaPaRR type PM which has a closed-form position solution, it is shown that all of its parallel singularities within reachable workspace are completely removed and that its kinematic characteristics are improved.

• Archives of Plastic Surgery
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• 제36권3호
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• pp.318-321
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• 2009

Purpose: The bony mallet finger injury is generally managed by conservative treatments, but operative treatments are needed especially when the fractures involve above 30% of articular surface or distal phalanx is accompanied by subluxation in the volar side. This is the reason they often result in chronic instability, articular subluxation and unsatisfactory cosmetic. In this report, We describe new method using the hook plate as an operative treatment of Mallet finger deformity. Methods: Among 13 patients with Mallet finger deformity who came from February 2006 to February 2008, six patient were included in surgical indication. Under local anesthesia, H or Y type incision was made at the DIP joint area. After the DIP joint extension, the hook plate was put on the fracture line, and one self tapping screw was used for fixation. 2 hole plate which was one of the holes in 1.5 mm diameter was cut in almost half and bended through approximately $100^{\circ}$. Results: In all six cases which applied the hook plate, complications such as loss of reduction or nail deformity were not seen. In only one patient, hook pate was removed due to inflammatory reaction after surgery. At 2 weeks after operation, active motion of DIP joint was performed. The result was satisfactory not only cosmetically but also functionally. At 6 weeks after operation, the range of motion of DIP joint was average $64^{\circ}$. Conclusion: The purpose of the operative treatment for mallet finger deformity using the hook plate is to provide anatomical reduction with rigid fixation and to prevent contracture at the DIP joint. While other operations take 6 weeks, the operation using the hook plate begins an active motion at 2 weeks after operation. Complication rate was low and the method is rather simple. Thus, the operation using the hook plate is recommended as a good alternative method of the mallet finger deformity treatment.

• 대한관절경학회지
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• 제9권2호
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• pp.148-153
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• 2005

목적: 소아에서 발생한 전위된 경골극 골절에 대해 관절경을 이용하여 정복 및 고정을 시행 후 임상적 결과를 분석하고 그 유용성을 문헌 고찰과 함께 보고하고자 하였다. 대상 및 방법: 2000년 12월부터 2004년 7월까지 경골극 골절로 내원한 소아 환자중 골편이 전위되어 수술적 가료가 요하였던 5예를 대상으로 하였다. 남자가 3예, 여자가 2예였으며, 평균연령은 9.1세(8.3세${\sim}$11세)였다. Movers & McKeever 분류상 5예 모두 III형이었고, 수상 후 수술일까지의 기간은 평균 4.8일($3{\sim}8$일)이었다. 수술 방법은 3예에서 관절경하 정복 및 견인 봉합술을, 나머지 2예는 관절경하 정복 및 나사못을 이용하여 고정술을 시행하였다. 평균 추시기간은 38.2개월(13개월${\sim}$56개월)이었다. 술후에는 2주간 장하지 석고 고정후 단계적 관절운동을 허용하였으며 술후 6주에 완전 체중 부하를 허용하였다. 수술 후 임상적 평가는 관절 운동 범위, Lachman 및 Pivot shift 검사 KT-1000 관절계를 이용하여 전방전위 정도를 측정하였고, 슬관절 기능평가는 Lysholm 슬관절 점수와 modified Feagin 점수를 측정하였다. 결과: 술 후 5예 모두에서 골유합을 얻었고, 최종 추시시 슬부 전방 동통이나 자각증상은 없었으며, 정상 슬관절 운동범위로 회복되었다. Lachman 검사상 1예에서 경도의 양성 소견을 보였으나 나머지 4예에서는 정상 소견을 보였다. KT-1000 관절계를 이용한 전방 전위 검사에서는 술 후 평균 1.9 mm였고, Lysholm 점수는 술 후 평균 99.4점, modified Feagin 점수는 모든 예에서 양호 이상이었다. 결론: 소아에서 발생한 전위된 경골극 골절시 관절경을 이용한 정복 및 고정으로 특별한 합병증 없이 만족할 만한 결과를 얻을 수 있었다. 견인 봉합이나 나사못을 이용한 고정술은 골편 고정에 모두 유용한 치료방법으로 사료된다.

• Journal of Yeungnam Medical Science
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• 제3권1호
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• pp.361-366
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• 1986

1985년 3월부터 1986년 6월까지 영남대학교 의과대학 정형외과학교실에서 10예의 주상골 골절환자에 나사를 사용하여 치료하였으며 그 결과를 요약하면 다음과 같다. 10예중 신선골절이 2예였고 불유합 골절이 8예이었다. 불유합 골절의 경우 수상후 수술시까지 기간이 최단 5개월에서 5년이었다. 수술후 고정기간은 평균 4주였으며 4주후 능동적 운동을 시행하여 고정기간의 단축으로 관절운동 회복은 매우 양호하였다. 골유합을 보인 사기는 8예에서 3개월에서 9개월 사이였으며 2예에서는 9개월 후에도 방사선상 골절선은 볼 수 있었다. 골절선이 남아있는 경우도 임상적으로는 증세의 호전(동통, 관절 운동)을 나타내었다.

• 대한족부족관절학회지
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• 제21권4호
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• pp.144-150
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• 2017

Purpose: To assess the clinical and radiographic results and complications of arthroscopy-assisted reduction and percutaneous fixation for patients with tongue-type Sanders type II calcaneal fractures. Materials and Methods: Between August 2014 and December 2015, 10 patients who underwent surgery using subtalar arthroscopic assisted reduction and percutaneous fixation for tongue-type Sanders type II calcaneal fractures were reviewed. The mean age was 50.8 years (36~62 years), and the mean follow-up period was 24 months (12~40 months). The clinical results were evaluated using the visual analogue scale (VAS) and American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score at the regular follow-ups, and the foot function index (FFI) at the last follow-up. The subtalar range of motion (ROM) was evaluated and compared with the uninjured limb at the last follow-up. The radiographic results were assessed using the Bohler's angle from the plain radiographs and the reduction of the posterior calcaneal facet using computed tomography (CT). The postoperative complications were assessed by a chart review. Results: The VAS and AOFAS ankle-hindfoot score improved until 12 months after surgery. The FFI was 15 (1.8~25.9) and subtalar ROM was 75.5% (60%~100%) compared to the uninjured limb at the last follow-up. The $B{\ddot{o}}hler^{\prime}s$ angle was increased significantly from $2^{\circ}$ ($-14^{\circ}{\sim}18^{\circ}$) preoperatively to $21.8^{\circ}$ ($20^{\circ}{\sim}28^{\circ}$) at the last follow-up. The reduction of the posterior facet was graded as excellent in five feet (50.0%) and good in five (50.0%) on CT obtained at 12 months after surgery. One foot (10.0%) had subfibular pain due to a prominent screw head. One foot (10.0%) had pain due to a longitudinal tear of the peroneal tendon that occurred during screw insertion. Conclusion: Subtalar arthroscopic-assisted reduction of the posterior calcaneal facet of the subtalar joint and percutaneous fixation is a useful surgical method for tongue-type Sanders type II calcaneal fractures.

• Clinics in Shoulder and Elbow
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• 제20권4호
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• pp.217-221
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• 2017

Background: The purpose of this study was to evaluate the clinical and radiographic outcomes of internal fixation with locking T-plates for osteoporotic fractures of the proximal humerus in patients aged 65 years and older. Methods: From January 2007 through to December 2015, we recruited 47 patients aged 65 years and older with osteoporotic fractures of the proximal humerus. All fractures had been treated using open reduction and internal fixation with a locking T-plate. We classified the fractures in accordance to the Neer classification system; At the final follow-up, the indicators of clinical outcome-the range of motion of the shoulder (flexion, internal rotation, and external rotation) and the presence of postoperative complications-and the indicators of radiographic outcome-the time-to-union and the neck-shaft angle of the proximal humerus-were evaluated. The Paavolainen method was used to grade the level of radiological outcome in the patients. Results: The mean flexion was $155.0^{\circ}$ (range, $90^{\circ}-180^{\circ}$), the mean internal rotation was T8 (range, T6-L2), and the mean external rotation was $66.8^{\circ}$ (range, $30^{\circ}-80^{\circ}$). Postoperative complications, such as plate impingement, screw loosening, and varus malunion were observed in five patient. We found that all patients achieved bone union, and the mean time-to-union was 13.5 weeks of the treatment. The mean neck-shaft angle was $131.4^{\circ}$ at the 6-month follow-up. According to the Paavolainen method, "good" and "fair" radiographic results each accounted for 38 and 9 of the total patients, respectively. Conclusions: We concluded that locking T-plate fixation leads to satisfactory clinical and radiological outcomes in elderly patients with proximal humeral fractures by providing a larger surface area of contact with the fracture and a more rigid fixation.