• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.599-602
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• 1999

In this paper, we attempt to control the pressure between two specimens using a servo gun in the resistance spot welding process. Servo guns have some advantages over pneumatic guns in that the fast response, the precise position control, and the accurate torque control are assured by virtue of the servo motor control. To demonstrate the practical significance of our results, we present some experimental results..

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2009.03a
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• pp.189-190
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• 2009

• Clinics in Shoulder and Elbow
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• v.9 no.2
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• pp.216-221
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• 2006

Avulsion of the triceps brachii is an uncommon injury. The usual mechanism of injury is fall onto an outstretched hand but can occur after direct contact injuries. Diagnosis is critical and dependent on history, physical examination, and radiological findings. Rupture of triceps brachii occurs most frequently at the tendo-osseous insertion and may be complete or partial, and could be associated with radial head fracture. Treatments include surgical repair of the complete rupture and immobilization of partial triceps rupture. We report 3 cases of triceps avulsion fractures treated by open surgical repair with literature reviews.

• Journal of Welding and Joining
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• v.23 no.3
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• pp.40-46
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• 2005

Air gun has been one of the good tools to press two sheet metals. However, it is not easy to control the acting force precisely. A Servo-gun is a good tool to control the acting force on the workpiece comparing with the air gun. Servo-gun has a higher tensile shear strength and lower indentation depth as well as smaller spatter. Dynamic resistance was obtained according to the acting force and welding current. As the acting force was changed during welding, the welding quality was increased.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.85-88
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• 2002

저항 스폿용접은 두 개의 금속판을 서로 겹쳐서 양쪽에 전극으로 압력을 가하면서 대전류를 흘려보낼 때 재료의 접촉면의 저항에 의해 발생하는 줄울열을 이용하여 재료를 용융시켜 두 모재를 접합시키는 방법이다 산업현장의 자동 용접라인에서 로봇암의 끝단에 부착하여 사용하던 기존의 공압건은 시편에 주어지는 압력이 일정하여 실시간 가압력 변화가 어렵고, 전극벌림의 임의 조정이 불가능하였다. 본 연구에서는 서보 모터를 채용한 서보건 시스템의 실시간 가압력제어와 용접도중 일정한 파우어를 공급하는 정전력 제어방식을 이용하여 용접 품질을 향상시키고자 한다.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.252-252
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• 2000

The Resistance Spot Welding (RSW) has been considered as an inherently safe and reliable method far joining metals, and has been widely employed, especially in automobile body assembly shops, as a manufacturing process. In recent years, the requirement for more sophisticated quality control procedures has considerably grown in the mass production industries. The object of the application of servo control to spot welding gun is the improvement of quality control in the spot welding, one of conventional industrial areas. The important factors affecting welding qualities (shear strength, nuggest size, indentation depth) are welding current, welding time, and gun press force. Welding current and welding time are controlled by welding timer. But, the conventional welding guns using compressed air are out of control in changing gun press forces in welding process. In this paper, a servo gun welding system having a AC servo motor and a PC control system is presented. The main object of this paper is to estimate the influence of gun press force changes in the welding process (press time -> welding time -> hold time) to welding qualities, and to evaluate welding qualities in real time, by recognizing the patterns of gun press forces changed in the welding process and comparing with the standard patterns.

• Journal of Welding and Joining
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• v.22 no.4
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• pp.43-49
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• 2004

Conventional method for electrode force application in resistance spot welding(RSW) processes is to use pneumatic cylinder. However, due to its inherent problems in pneumatic power system such as compressibility of air and poor transient response characteristics, new electrode force system with servo control are recently introduced in RSW machine. This machine is called “servogun”. The purpose of this study is to evaluate performance of servogun in case of spot welding of aluminum alloy. Aluminum alloy(A5052) sheets are spot welded using pneumatic gun and servogun. Both results are compared by means of macro cross-section etching test and tensile shear strength test. Numerous previous research have reported nugget with many voids and cracks are not uncommon defects in spot welds with aluminum alloy. The experimental results show similar defects in case of pneumatic gun. In contrast, use of servogun considerably reduced generation of voids and cracks. In case of step-wise increased forging force at the end of welding cycle with servogun, crack-free and void-free nuggets have been observed. The performance of servogun has been also verified by series of tensile shear test. Higher strength values have been achieved with servogun in comparison to that of pneumatic gun.

• Clinics in Shoulder and Elbow
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• v.14 no.1
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• pp.89-93
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• 2011

Purpose: We want to report on one patient who presented with lateral forearm pain caused by compression neuropathy of the lateral antebrachial cutaneous nerve. Materials and Methods: A female patient was managed by operative treatment (biceps tenoplasty) after failure with conservative treatment for 6 weeks. One year later, we evaluated the clinical symptoms and biceps tendon problems such as supination weakness or rupture after the tenoplasty. Results: Her symptom completely subsided immediately at the first postoperative day and her recovery was uneventful. Supination weakness and rupture of the distal biceps tendon were not found after the operation. Conclusion: We have reported here on a case of successful management of lateral antebrachial cutaneous neuropathy by performing biceps tenoplasty, along with a review of the previously published articles.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.150-157
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• 2008

Purpose: We wanted to evaluate the results of surgical treatment for fracture of the scapular body. Materials and methods: The subjects of this study were seven patients with fracture of the scapular body and all these patients were managed surgically. We considered the operative indications as being 100% translation of the lateral border, or $25^{\circ}$ of angular deformity of the glenoid, or 1cm medialization or the variant of the double disruption of the superior scapular suspensory complex. There were five males and two females, and their ages ranged between 40 and 58 years (mean age: 49) with average follow up of 11 months (6~24 months). Two patients sustained multiple fractures of the ribs and spines. The surgical results were evaluated according to the subjective satisfaction, the UCLA score and the Korean shoulder score. Results: The mean UCLA score was 29 (17~33) and the mean Korean shoulder score was 86 (63~94). The self assessment for subjective satisfaction was 7.7 (4~9). There were two complications; one case of screw pull-out without the loss of the fracture fixation and the other case with screw penetration of the glenoid cavity. Conclusion: Surgical treatment may be effective for the management of severely displaced fracture of the scapular body in order to prevent the impairment of the shoulder function caused by the altered glenohumeral and scapulothoracic kinematics.

• Clinics in Shoulder and Elbow
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• v.12 no.2
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• pp.159-166
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• 2009

Purpose: We wanted to evaluate the surgical results of early mobilization after rigid fixation of small coronoid fracture using the tension band technique Materials and Methods: Eight cases of coronoid fracture were fixed with the tension band technique and using K-wire and wire through the medial approach. All the cases were Regan-Morrey type 2. According to O'Driscoll, they were classified as 5 cases of the tip type (subtype 2) and 3 cases of the anteromedial type (1 case of subtype 2, and 2 case of subtype 3). The associated collateral ligament injuries (6 cases) and radial head/neck fractures (4 cases) were managed simultaneously. After immobilization for 5~7 days, active ROM exercise with a fitted hinge brace started and continued till postoperative 6 weeks. The patients were assessed for pain, ROM and functional disability using the Mayo elbow performance score (MEPS) at an average of 11 months (range: 6~28 months). The ulnar nerve symptoms were also investigated. Results: We observed solid union in all the coronoid fractures without hardware failure. An average of 2.2 wires (range: 2~4) were used. The mean extension was $3^{\circ}$(range: $0^{\circ}\sim25^{\circ}$), the mean flexion was $137^{\circ}$(range: $130^{\circ}\sim140^{\circ}$), the mean pronation was $69^{\circ}$(range: $45^{\circ}\sim90^{\circ}$) and the mean supination was $78^{\circ}$(range: $45^{\circ}\sim90^{\circ}$). The mean MEPS was 96 (range: 65~100). Ulnar nerve symptoms occurred at postoperative one day and persisted in one patient with the terrible triad of taking radial head excision and residual medial instability. Conclusion: The tension band technique uses easily obtained, economic K-wires and the wire was strong enough to permit early elbow ROM exercise and the technique might improve the elbow function. It was especially useful for fixation of multiple small fragments.