• Journal of Biomedical Engineering Research
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• v.21 no.2
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• pp.181-187
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• 2000

동맥의 일부분이 팽창하는 동맥류는 파열로 인한 높은 사망률을 야기한다. 동맥류의 발생 및 파열에는 혈관벽의 구조적 약화와 혈류에 의한 응력이 중요한 역할을 하며, 혈류에 의해 혈관벽에 가해지는 전단응력은 간접적으로 혈관벽 구조를 변화시키고, 직접적으로 혈관벽에 응력을 가하므로 동맥류 파열에 영향을 미치는 중요한 혈류역학적 인자이다. 동맥류가 자주 발생하는 복부대동맥류 모델을 제작하여 정상류와 맥동류 유동에서 광색성 염료를 이용한 유동가시화 방법으로 벽 전단변형률을 측정하였다. 벽전단변형률은 동맥류 내부에서 감소하여 음의 값을 가지며, 동맥류 최대확장부 후부에서 다시 증가하여 확장부가 끝나는 위치에서 동맥 벽에 비해 약 1.5배 정도의 큰 전단변형률 값을 가졌다. 동맥류 최대확장부 후부에서는 벽전단변형률의 방향의 바뀌며, 위치에 따른 전단변형률의 변화가 크게 나타났다. 맥동류 유동에서는 동맥류의 위치에 따라 시간에 따른 벽전단형률 파형이 측정되었다. 동맥류 내부에서는 전단변형률의 크기가 작고 그 방향이 시간에 따라 변화가 심하였으므로 혈관벽의 구조변화가 발생하기 쉬운 지역으로 지목된다. 동맥류 최대 확장부 후부는 위치 및 시간에 따른 전단변형률의 변화가 심하며, 혈관벽 응력이 최대값을 갖는 지역이므로 동맥류의 파열이 발생하기 쉬운 지역으로 예측된다.

• Journal of the Korean Arthroscopy Society
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• v.5 no.2
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• pp.85-91
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• 2001

Purpose : The purpose of this study was to determine the clinical outcome of meniscal repairs according to tern location and combined injury. Materials and Methods : From 1994, 73 meniscal repairs were underwent by arthroscopy and followed more than 1 year. The locations of torn meniscus were 29 red-red Bone, 36 red-white zone, 8 white-white zone. Twenty-six patients also had combined lesion including ACL injury 17 cases and treated simultaneously. Clinical result was evaluated by OAK system. Result : Healing rates(above good) were $94\%$ in isolated injury and $88\%$ in combined injury, especially $94\%$ in ACL injury. The result according to tern location were $90\%$ in red-red zone, $91\%$ in red-white zone, all in white-white zone. Conclusion : Meniscus tear with ACL injury should be repaired by arthroscopy, simultaneously. The meniscal tear of white-white zone could be healed by arthroscopic meniscal suture.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.32-32
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• 1997

복합재 연소관의 구조적 건전성 평가 방법을 개발하기 위하여 표준 평가용 시편의 수압 시험 중, 연소관으로부터 방출되는 음향방출(acoustic emission: AE) 신호를 측정 장비를 이용하여 신호 처리함으로써 시편이 파괴되기 전, 대략적인 시편의 파열 위치 및 일정 압력 유지상태에서 hit rate 양상에 의한 건전성 평가 방법을 제시하였다. 데이터의 분석 기법 향상을 위하여 음향방출 데이터를 시간 및 센서별로 분류하는 프로그램을 개발하였다. 수압 시험을 낮은 압력 단계부터 높은 압력 단계까지 일정 압력 유지 상태(load-hold)에서 발생한 hit 수와 1분간 유지한 후 발생되는 hit rate(hit/sec)의 값의 크고 작음이 복합재 압력 용기의 결함수의 증감으로 나타났으며, 이로부터 복합재 압력 용기의 파열 압력과의 상관관계 및 건전성을 예측할 수 있었다. 복합재 압력 용기의 파열 위치는 energy rate(energy/sec) 측정값을 분석하여 예측하였으며, 파열 압력의 30∼50%에서 가능하였다.

• 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.15 no.1
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• pp.16-24
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• 2012

Purpose: This study was designed to investigate the rate of incidence, location and the clinical value of the rotator cuff retear by analyzing MRI scans, which was taken after an arthroscopic rotator cuff repair. Materials and Methods: This study included a total of 109 patients, who underwent a shoulder MRI scan after an average of 10.6 months later from the arthroscopic rotator cuff repair. We only defined the 'retear' when the Sugaya type IV and V was observed in the sagittal section of the MRI. The location of the retear was divided into the medial and lateral areas by the site, which was 1 cm medial to the anchor insertion. We investigated the incidence rate and the location of the retear, in terms of the age, sex, initial tear size and the suture method. Also, we compared the functional score of the retear group and the non-retear group, after an average of 13.9 months follow-up. Results: There were 38 of the 109 patients that showed the rotator cuff retear. Of these patients, 25 were male patients, and 13 were female patients. Of the 38 patients with the rotator cuff retear, 21 patients were included in the <3 cm retear group, and 17 were included in the ${\geqq}3$ cm retear group. At the end of the follow up period, all 109 patients showed a statistical significant improvement in the shoulder functional score. Conclusion: According to the follow up of the MRI scan, which was taken after the rotator cuff repair, the retear rate reached 34.9 %, and there were no significant differences on the age and the suture method. More rotator cuff retear occurred in male patients, and the initial tear size was positively correlated with the incidence rate of the rotator cuff retear. Also, the retear was more frequently observed at the medial side. That is because when the suture was performed, excessive tension was loaded on the medial side of the suture site.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.3
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• pp.313-318
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• 2001

To establish nondestructive test method for aerospace composite materials, various composite specimens were tested and analyzed using acoutic emission. The hit rate of acoustic emission closely was rotated with crack initiation and propagation. This report also presents defection capability of crack initiation pressure, initial crack active location, and crack propagation using acoustic emission.

• Journal of Chest Surgery
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• v.42 no.3
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• pp.355-360
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• 2009

Background: Benign teratoma is mostly asymptomatic, but this tumor rarely ruptures into the adjacent structure such as the pleural space, pericardium, lung parenchyma or tracheobronchial tree. Thus, it is important to differentiate ruptured teratoma from unruptured teratoma. This study evaluated the difference between ruptured and unruptured benign teratoma. Material and Method: Twenty-four cases of surgically resected benign teratomas were reviewed retrospectively. The clinical symptoms, chest CT findings and operative findings of the ruptured teratoma were compared with those of the unruptured teratoma. Especially, the tumor size, wall thickness, location of the mass, internal septation, homogeneity, calcification and ancillary findings were evaluated on CT. Result: Of the 24 patients, 7 patients were diagnosed with ruptured teratoma. Severe symptoms were more commonly found for ruptured teratoma than for unruptured teratoma. The ruptured teratoma had a tendency to display calcification and such ancillary findings as collapse or consolidation of the lung parenchyma. For the ruptured teratoma, the resection was performed by sternotomy or thoracotomy, and more lung resection was included. Conclusion: Calcification within the mass and changes in the lung parenchyma on the preoperative CT findings can be diagnostic signs of a ruptured teratoma. The demonstration of ruptured teratoma is important not only for making the early diagnosis, but also for the surgical planning.

• Clinics in Shoulder and Elbow
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• v.12 no.1
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• pp.38-43
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• 2009

Purpose: The purpose of this study was to assess the efficacy of MR arthrography to detect partial thickness rotator cuff tears. Materials and Methods: One hundred and seventy seven patients with a high suspicion for rotator cuff disease were studied by performing MR-arthrography and subsequent arthroscopy. The ability of MR-arthrography to detect partial thickness tears was evaluated according to the location of the tears. We determined the correspondence between the measurements of the articular side partial tears on MR arthrography and those on the arthroscopic findings. Results: The arthroscopic diagnosis of partial thickness rotator cuff tears was divided into 3 groups according to their location. There were 63 cases on the articular side, 41 cases on the bursal side and 20 cases on both sides. The sensitivity of MR-arthrography was 82% for the articular side tears and 11% for the bursal tears. The specificity was 88% for the articular side tears and 100% for the bursal tears. MR-arthrographic measurement correctly predicted 72% in 28 repaired cases of 56 articular side partial thickness tears. Conclusions: MR-arthrography may be a reliable tool for diagnosing articular side partial thickness rotator cuff tears, but it has limitations for bursal side tears.

• Journal of the Korean Institute of Gas
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• v.16 no.2
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• pp.18-24
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• 2012

This research seeks to evaluate damage on type II gas cylinder by an acoustic emission test when executing 20000 cycles fatigue test and thereafter burst test. Used gas cylinders in the experimental are three types as follows; one is sound cylinder, others are cylinders which contain longitudinal and transverse artificial defect. The size of artificial defect is a depth of 3 mm, width of 3 mm and length of 50 mm. In the case of the cylinder which artificial defect, unlike the expectation that it will burst in low pressure, the burst pressure of the cylinder did not differ much according to whether or not there were defects. However, when there was longitudinal defect, the location of burst was near the location of defect. This leads to the effect in which the thickness of the composite material becomes thinner according to the length of the longitudinal defect and this is judged to have an effect on the location of initiation and growth of crack in the liner. Also, for the acoustic emission signal, when there is longitudinal defect, the ratio of an event occurring at defect position among overall hits is more than 50 %, and the source location also accords very precisely with defect position.

• Journal of Korean Orthopaedic Sports Medicine
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• v.6 no.1
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• pp.45-49
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• 2007

Purpose: We analyzed the location and type of meniscus tear associated with ACL rupture in order to estimate and prepare whether the meniscus tear is in a repairable location. Materials and Methods: We reviewed 78 cases who had ACL reconstructive surgery due to ACL rupture. We set the period of acute injury on the basis of under 12 months after trauma. The location and type of meniscus tear was analyzed in accordance with MRI findings and arthroscopic findings. Results: The 50 cases of meniscus tear were detected out of the 78 ACL rupture;32 cases were lateral meniscus tears, 24 were medial meniscus tears and 6 cases were both menisci tears. From a total of 56 meniscus tears, 30 cases were longitudinal tears, 22 cases were red-red zone tears and 35 cases(62%) were posterior horn tears. Conclusion: The most common type of meniscus tear associated with ACL rupture war longitudinal tear at the red-red zone or meniscosynovial junction. Majority of the tears located at that place can be healed with conservative treatment, arthroscopic meniscus suture.