• Nuclear Engineering and Technology
• /
• 제51권5호
• /
• pp.1451-1469
• /
• 2019

This paper proposes a residual stress mitigation of a nuclear safety-related austenitic stainless steel TP304 pipe bended by local induction heating process via performing elastic-plastic finite element analysis. Residual stress distributions of the pipe bend were calculated by performing finite element analysis. Validity of the finite element analysis procedure was verified via comparing with temperature histories measured by using thermocouples, ultrasonic thickness measurement results, and residual stress measurement results by a hole-drilling method. Parametric finite element stress analysis was performed to investigate effects of the process and geometric shape variables on the residual stresses on inner surfaces of the pipe by applying the verified procedure. As a result of the parametric analysis, it was found that it is difficult to considerably reduce the inner surface residual stresses by changing the existing process and geometric shape variables. So, in order to mitigate the residual stresses, effect of an additional process such as cooling after the bending on the residual stresses was investigated. Finally, it was identified that the additional heating after the bending can significantly reduce the residual stresses while other variables have insignificant effect.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제19권2호
• /
• pp.149-155
• /
• 1997

Ridge expansion osteotomy(REO) technique is a simple and more conservation method to widen a narrow alveolar ridge in the maxilla. This method is superior to drilling method in soft and narrow maxillary alveolar ridge and allows the surgeon to widen the ridge in routine office procedure. Therefore, it is the treatment of choice to implant the maxilla with narrow alveolar ridge. This article presents clinical cases and discusses the advantages, rationale and surgical protocol of REO technique.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.445-456
• /
• 2005

The research concentrates on improving the in-hole seismic probe, which has been developed in past five years, to be used in stiffness measurements of tunnel-face materials. The probe was down-sized to be fit in 45-mm diameter holes(or BX) drilled by a jumbo-drill, which is used to drill holes to install explosives for tunneling. Also trigger system was improved by using a down-speeding motor for operating convenience and air packing system was replaced with a set of plate-springs to eliminate supply of compressed air. These modifications are to adjust the probe for the unfavourable environment inside of tunnels and to test without any further drilling cost. The probe and testing procedure were successfully adopted with horizontal holes drilled by a jumbo-drill at a tunnel-face to evaluate the stiffness of rock mass. The measured shear wave velocities can be used to estimate deformation properties of rock mass for tunnel analyses.

• 대한산업공학회지
• /
• 제26권2호
• /
• pp.165-170
• /
• 2000

In order to perform a successful material cutting process, the operators are to select the suitable machining tools and cutting conditions for the cutting environment. Up to now, this has been a complicated procedure done by the data in the tool manufacturers' paper catalog and the operator's experiencial knowledge, so called heuristics. This research is motivated by the fact that using computer techniques in processing vast amount of data and information, the operator can determine the tool and cutting condition easily. In the developed program, the selection of milling cutter, insert, and components are combined to provide optimal cutting speed, depth of cut, feed rate, rpm, and power. This program also provides the selection routine for end mill, drilling, turning, and grinding where the suitable tools are selected by workpiece, holder type, cut type, and insert shape.

• 대한관절경학회지
• /
• 제13권3호
• /
• pp.235-241
• /
• 2009

The development of good quality small-diametered arthroscopes and refined arthroscopic techniques has contributed to the improvement of the subtalar arthroscopy. The therapeutic indications are synovectomy, removal of loose bodies, debridement and drilling of osteochondritis dissecans, excision of subtalar impingement lesions and osteophytes, lysis of adhesions for post-traumatic arthrofibrosis, removal of a symptomatic os trigonum, calcaneal fracture assessment and reduction, and arthroscopic arthrodesis of the subtalar joint. The subtalar arthroscopy can be done in supine position using thigh holder or in lateral decubitus position. The arthroscope generally used is a 2.7-mm 30 degrees short arthroscope. Noninvasive distraction with a strap around the hindfoot can be helpful. Usually anterolateral, middle and posterolateral portals are utilized for inspection and instrumentation within the joint. Twoportal posterior subtalar arthroscopy in prone position can be performed as well with 4.0-mm 30 degrees arthroscope, depending on the type and location of the subtalar pathology. The subtalar arthroscopy is a technically demanding procedure, which requires proper instrumentation and careful operative technique. Possible complications are nerve damage and persistent wound drainage.

• 한국지진공학회논문집
• /
• 제5권6호
• /
• pp.21-27
• /
• 2001

이 논문에서는 철근콘크리트 쉘구조의 동적해석을 위한 비선형 유한요소 해법을 제시하였다. 사용된 프로그램은 철근콘크리트 구조물의 해석을 위한 RCAHEST이다. 유한요소로서는 면내회전강성도를 갖는 4절점 평면 쉘요소가 사용되었다. 두께방향에 대한 철근과 콘크리트의 재료성질을 고려하기 위하여 층상화기법이 도입되었다. 재료적 비선형성에 대해서는 균열콘크리트에 대한 인장, 압축, 전단모델과 콘크리트 속에 있는 철근모델을 조합하여 고려하였다. 이에 대한 콘크리트의 균열모델로서는 분산균열모델을 사용하였다. 동적 평형방정식의 해는 HHT법에 의한 수치적분으로 구하였다. 신뢰성 있는 해석결과와 비교를 통하여 이 논문의 제안방법이 철근 콘트리트 쉘구조의 비선형 동적해석에 적합한 방법임을 입증하고자 한다.

• Journal of Korean Neurosurgical Society
• /
• 제49권4호
• /
• pp.248-251
• /
• 2011

Objective : In the field of spinal surgery, a few laboratory results or clinical cases about robotic spinal surgery have been reported. In vivo trials and development of related surgical instruments for spinal surgery are required before its clinical application. We investigated the use of the da $Vinci^{(R)}$ Surgical System in spinal surgery at the craniovertebral junction in a human cadaver to demonstrate the efficacy and pitfalls of robotic surgery. Methods : Dissection of pharyngeal wall to the exposure of C1 and odontoid process was performed with full robotic procedure. Although assistance of another surgeon was necessary for drilling and removal of odontoid process due to the lack of appropriate end-effectors, successful robotic procedures for dural sutures and exposing spinal cord proved its safety and dexterity. Results : Robot-assisted odontoidectomy was successfully performed in a human cadaver using the da $Vinci^{(R)}$ Surgical System with few robotic arm collisions and minimal soft tissue damages. Da $Vinci^{(R)}$ Surgical System manifested more dexterous movement than human hands in the deep and narrow oral cavity. Furthermore, sutures with robotic procedure in the oral cavity demonstrated the advantage over conventional procedure. Conclusion : Presenting cadaveric study proved the probability of robot-assisted transoral approach. However, the development of robotic instruments specific to spinal surgery must first precede its clinical application.

• 대한족부족관절학회지
• /
• 제8권1호
• /
• pp.76-80
• /
• 2004

Purpose: We assessed the results of open treatment of anterior impingement syndrome of the ankle in elite level soccer players and concomitant injuries were idenfied. Materials and Methods: We retrospectively reviewed twenty one elite level soccer players diagnosed with anterior impingement syndrome who underwent open debridement between January 1997 and January 2002. All were men and the mean age at the operation was 21 years (range 16 to 27). The mean follow-up duration was 31 months (13 to 71). Concomitant abnormalities were idenfied through physical examination, bone scan and MRI. On a preoperative lateral radiograph, patients were classified according to McDermott's stage. Anteromedial or anterolateral approach was used at the operation and osteophyte was removed with osteotome and rongeur. When chronic ankle instability was accompanying, we performed Modified Brostrom-Gould procedure and for osteochondral lesion, multiple drilling was applied. The Ogilvie-Harris scoring system was used as a clinical scale to evaluate pain, swelling, stiffness and limitation of activity. The results were scored as excellent (15 to 16 points), good (13 to 14) and otherwise unsatisfactory. The time to return to full activity including sports activity was determined. Results: Eighteen of twenty one patients had an excellent outcome. Three patients were graded unsatisfactory and two of them abandoned their career due to the persistence of residual pain. Concomitant abnormalities were found including twelve cases of chronic ankle instability, three cases of osteochondral lesion and two cases of flexor hallucis longus tendinitis. Conclusion: Open debridement was successfully applied to the elite level soccer player with anterior impingement syndrome of the ankle. Considerable coexistence of other abnormalities such as chronic ankle instability may encourage us to consider additional operative procedure.

• Journal of Korean Neurosurgical Society
• /
• 제61권3호
• /
• pp.407-414
• /
• 2018

Objective : The purpose of the present study was to describe an OrBitoZygomatic (OBZ) surgical variant that implies the drilling of the orbital roof and lateral wall of the orbit without orbitotomy. Methods : Design : cross-sectional study. Between January 2010 and December 2014, 18 patients with middle fossa lesions underwent the previously mentioned OBZ surgical variant. Gender, age, histopathological diagnosis, complications, and percentage of resection were registered. The detailed surgical technique is described. Results : Of the 18 cases listed in the study, nine were males and nine females. Seventeen cases (94.5%) were diagnosed as primary tumoral lesions, one case (5.5%) presented with metastasis of a carcinoma, and an additional one had a fibrous dysplasia. Age ranged between 27 and 73 years. Early complications were developed in four cases, but all of these were completely resolved. None developed enophthalmos. Conclusion : The present study illustrates a novel surgical OBZ approach that allows for the performance of a simpler and faster procedure with fewer complications, and without increasing surgical time or cerebral manipulation, for reaching lesions of the middle fossa. Thorough knowledge of the anatomy and surgical technique is essential for successful completion of the procedure.

• Journal of Periodontal and Implant Science
• /
• 제43권6호
• /
• pp.308-314
• /
• 2013

Purpose: The purposes of this study were to assess the dentists' subjective satisfaction with the crestal approach sinus (CAS) kit, a device for maxillary sinus membrane elevation by the crestal approach using a special drilling system and hydraulic pressure, and to summarize the subjective satisfaction of dental implants placed after a sinus lift procedure with the CAS kit. Methods: Thirty dental clinicians who had experience with dental implant placement after a sinus lift procedure with the CAS kit from June 2010 to May 2012 were included in this study. The questionnaire for the evaluation of the dentists' subjective satisfaction with the CAS kit was sent to the respondents and returned. The questionnaire was composed of two main parts. The first part was related to the sinus membrane perforation rate. The second part was related to the dentists' subjective satisfaction with the CAS kit. Results: A total of 28 dentists answered the questionnaire. Among 924 implant cases, sinus membrane perforation occurred in 38 cases (4.1%). Among the 28 dentists, 26 dentists (92.9%) were satisfied or very satisfied with the CAS kit. In particular, 24 dentists (85.7%) reported that safety, cutting performance, and user-friendliness of the CAS drill were advantages of the CAS kit. However, 7 dentists (25%) did not routinely use the hydraulic lifter for sinus membrane elevation. Conclusions: From the survey, it was shown that the respondents were generally satisfied with the CAS kit and that the cutting performance and safety of the drill component were considered strengths of the CAS kit.