• The Journal of Korean Orthopaedic Ultrasound Society
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• v.2 no.2
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• pp.62-67
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• 2009

Purpose: The purpose of this study is to find out the accuracy and usability of the three dimensional ultrasonography in measuring the size of the rotator cuff tear, especially before and after the injection of normal saline into the glenohumeral joint. Materials and Methods: 14 patients of rotator cuff tear who were diagnosed and operated from August 2007 to September 2008 were included in this study and authors compared the size of rotator cuff tear measured with three dimensional ultrasonography with the real size measured intraoperatively. In preoperative ultrasonographic evaluation, horizontal and longitudinal length of rotator cuff tear before and after injection of normal saline intraarticularly. During the arthroscopic operation the size of tear was measured by passing a Kirschner wire through a spinal needle and direct measure was performed in open surgery. Results: The average difference was 8 mm in horizontal and 1.9 mm in longitudinal length of tear without saline injection between ultrasonographic and intraoperative measure. The average difference was 4.1 mm in horizontal and 1.6 mm in longitudinal length of tear after the normal saline injection. Conclusion: In three dimensional ultrasonographic evaluation in rotator cuff tear, intraarticular normal saline injection would produce more accurate results.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.49-56
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• 2012

Rupture disks are a kind of safety device in high pressure equipment and they are used to control rupture pressure in the solid rocket motor. In this paper, a series of rupture experiments was performed using rupture disks made of AISI 316L and rupture pressure of rupture disks was calculated through various assumptions in relation between elasto-plastic material properties and true stress-strain curve. Experiment and FEA indicated rupture pressure is determined by size of rupture disks. As a result of elasto-plastic analysis, only multi-linear stress-strain curve was able to calculate meaningful estimations. Experimental results also showed rupture location are decided by the size of rupture disks. Experimental and FEA results will be applied to control rupture pressure of disks.

• Clinics in Shoulder and Elbow
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• v.16 no.1
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• pp.10-16
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• 2013

Purpose: To know if magnetic resonance image (MRI) re-examination is needed before surgery, we compared the pre-operative MRI recorded at different time points and the corresponding arthroscopic findings. Materials and Methods: Depending on the timing of evaluation, the MRI was classified into three groups: group A, MRI was taken 1 month before the surgery (44 cases, average 16 days); group B, 1-6 months before the surgery (41 cases, average 91 days); and group C, 6-12 months before the surgery (25 cases, average 230 days). The anterior to posterior tear size (length) and medial retraction size (width) of rotator cuff tear were measured for each group and they were compared with the actual arthroscopic findings. Results: Results of this study showed that arthroscopic rotator cuff tear length and width were larger than those of MRI. The difference of the rotator cuff tear size was 3.6(${\pm}1.2$) mm of length and 0.6(${\pm}0.4$) mm of width in group A, 4.2(${\pm}1.7$) mm and 2.4(${\pm}1.1$) mm in group B, and 4.5(${\pm}2.1$) mm and 3.0(${\pm}1.5$) mm in group C. There was a tendency of the larger size difference for longer pre-operative period, but it was not statistically significant. Conclusion: The rotator cuff tear size did not show remarkable differences between pre-operative MRI taken within 1 year before surgery and the actual arthroscopy. It is concluded that additional MRI evaluation is not required within 1 year.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1999.06a
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• pp.207-214
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• 1999

카세트식 이동식부탄연소기의 사고는 과열에 의한 화재뿐만 아니라 접합용기의 파열에 따른 피해가 더 큰 위험성을 내포하고 있다. 접합용기의 파열원인은 화재에 의한 파열과 접합용기 장착 불량에 의한 가스누출로 화염에 의한 파열, 그리고 과대 조리기구를 사용하여 조리기구 및 화염에서 발생되는 열이 접합용기에 전달되어 온도상승에 따른 파열로 구분된다. 현재 카세트식 이동식부탄연소기의 조리기구 크기에 따라 과열에 따른 정확한 검증이 부족하며, 사용자에게 사용장소와 조리기구외 크기만 권고하고 있어 이에 대한 자료가 필요하다. (중략)

• Clinics in Shoulder and Elbow
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• v.11 no.1
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• pp.24-28
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• 2008

Purpose: We wanted to determine if preoperative three dimensional (3D) ultrasonographic evaluation for rotator cuff tear is useful to measure the real size of a torn rotator cuff for performing an operation Materials and Methods: This study included 15 cases (7 males and 8 female), and these patients were confirmed to have a full thickness tear of the rotator cuff by 3D ultrasonography and the operative findings, as well as on the magnetic resonance imaging (MRI). The average age of the patients was 55.4yrs. Results: The average difference between the 3D ultrasonographic and operative measurements of the full thickness tear of the rotator cuff was 0.7 mm in the transverse length and 2.0 mm in the longitudinal length. Conclusion: The low error between the 3D ultrasonographic and intraoperative measurements of rotator cuff tear shows the usefulness of preoperative 3D ultrasonographic evaluation for rotator cuff tear.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.96-103
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• 2008

Purpose: This study investigated the rate of retear and related factors after arthroscopic repair of rotator cuff tears involving more than one tendon. Materials & Methods: Arthroscopic repair of 22 rotator cuff tears (average size 3.2cm: average age 58 years old) involving the supraspinatus and part or all of the infraspinatus were investigated using MRI on average 10 months after repair. The status of the repaired cuff was investigated using Sugaya's classification, and the change in muscle was evaluated with Goutallier's classification. Results: Retear (Sugaya grade IV, V) was found in 7cases(32%). Tears larger than 3cm had a higher retear rate(67%) than smaller tears(8%). Retear cases had Goutallier grade II or higher muscle changes preoperatively and showed aggravation of muscle atrophy postoperatively. Even without retear, reversal of muscle change was not seen Conclusion: Rotator cuff tears not confined to the supraspinatus had a 32% retear rate after arthroscopic repair. The size of the tear was the most crucial factor influencing retear. Retear was frequent in tear over 3cm. Atrophy of the cuff muscle worsened when the repair failed but did not improve even without retear.

• Clinics in Shoulder and Elbow
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• v.11 no.1
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• pp.29-36
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• 2008

Purpose: We wanted to evaluate the relationship between the clinical outcomes and cuff integrity after open rotator cuff repair and we wanted to analyze the causes of rotator cuff retear. Materials and Methods: 78 patients who underwent open rotator cuff repair were enrolled from 2004 to 2006. All the patients were observed for a minimum follow-up of 12 months and they were evaluated by magnetic resonance imaging (MRI). The clinical outcomes were accessed by dividing the patients into the retear group and the intact group. The groups were also compared to analyze the cause of rotator cuff retear according to the preoperative tear size, the symptom duration, and so on. Results: The clinical outcome of the retear group (n=22) was improved significantly after operation (p<0.001, p<0.001), but the muscle power was not improved significantly (p=0.099, p=0.243). More retears were found in the patients who had a larger preoperative tear (p<0.001) and the symptom duration of the retear group was longer (p=0.027). Conclusion: Although there were retear after rotator cuff repair, the clinical outcomes were improved. Yet the muscle power of the supraspinatus and external rotator were not improved significantly. There were more retears for the cases that had a larger preoperative tear size and a longer duration of symptoms.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.5
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• pp.101-110
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• 2010

Dual pulse rocket motor is a solid motor with two grains separated by a bulkhead and rupture disc. The elasto-plastic explicit dynamic analysis for the rupture disc was conducted by finite element method. The effect of the slit geometry of a rupture disc was parametrically analyzed in terms of rupture time and shape. The results can be used to control the rupture pressure by changing the slit geometry of rupture disc.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.261-264
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• 2010

Dual Pulse Rocket Motor is a solid rocket motor with two grains separated by a bulkhead and rupture disc. The elasto-plastic explicit dynamic analysis of rupture disc was conducted by the finite element method. The effect of the slit geometry of rupture disc with radial slit was parametrically analyzed in terms of rupture time and shape. The results can be used to control the rupture pressure by changing the slit geometry of rupture disc.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.105-112
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• 2010

Dual Pulse Rocket Motor is a solid rocket motor with two grains separated by a bulkhead and rupture disc. The elasto-plastic explicit dynamic analysis of rupture disc was conducted by finite element method. The effect of the slit geometry of a rupture disc was analyzed for rupture time and shape by the parametric study. The results can be used to control the rupture pressure by the change the slit geometry of a rupture disc.