• Journal of Korean Neurosurgical Society
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• 제29권1호
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• pp.58-65
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• 2000

Objective : Thoracolumbar junction is second most common level of injury next to cervical spine. The object of this study is to study the usefulness of surgical titanium mesh instead of bone graft, as well as to evaluate the correction of spinal deformity and safety of early ambulation in patients with injury at thoracolumbar junction. Patients and Methods : This review included 51 patients who were operated from July 1994 to December 1997. The injured spine is considered to be unstable, if it shows involvement of two or more columns, translatory displacement more than 3.5mm, decrease more than 35% in height of vertebral body and progression of malalignment in serial X-ray. The decision to operate was determined by (1) compression of spinal cord or cauda eguina, (2) unstable fracture, (3) malalignment and (4) fracture dislocation. The procedure consisted of anterior decompression through corpectomy and internal fixation with anterior instrument and surgical titanium mesh which was impacted with gathered bone chip from corpectomy. Results : Fifty-one patients were followed up for at least 12 months. The main causes of injury were fall and vehicle accident. The twelfth thoracic and the first and the second lumbar vertebrae were frequently involved. Complete neural decompression was possible under direct vision in all cases. Kyphotic angulation occurred in a patient. Radiologic evaluation showed correction of deformity and no distortion or loosening of surgical titanium mesh with satisfactory fixation postoperatively. Conclusions : We could obtain neurological improvement, relief of pain, immediate stabilization and early return to normal activities postoperatively. Based on these results, authors recommend anterior decompression and internal fixation with surgical titanium mesh in thoracolumbar unstable spine injuries.

• 콘크리트학회논문집
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• 제21권4호
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• pp.457-464
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• 2009

섬유는 가교작용에 의한 시멘트 복합체의 파괴를 조절할 수 있는 섬유보강 시멘트 복합체의 중요한 재료로 섬유의 혼입률에 따라 다른 파괴메커니즘을 나타내기도 한다. 일반적인 연구에서 섬유를 보강한 시멘트 매트릭스의 마 이크로 메커니즘에 대한 이해를 통하여 섬유보강 시멘트 복합체의 파괴거동을 평가할 필요가 있다. 이 연구에서는 섬 유보강 시멘트 복합체의 파괴거동을 평가하기 위하여, 반복압축, 휨하중 하에서 음향방출 기법에 의한 섬유보강 시멘트 복합체의 손상을 평가하고 분석하였다. 실험체는 PVA 섬유를 0, 1.0, 1.5, 2.0%를 치환한 총 4개의 실험체를 계획하였 다. 기존 연구의 경우 기본적인 AE 신호에 의한 분석 방법을 제시하고 있으나 이 연구에서는 이전 연구자들에 의해 제 시되었던 음향방출 기법을 이용한 정량적 손상평가를 섬유보강 시멘트 복합체에 적용하여 분석하였다. 펠리시티비에 의 한 손상평가의 경우 기존 연구 결과와 같이 모든 실험체에서 카이저 효과와 함께, 펠리시티비가 0.4~1.1로 나타나 펠리 시티비에 의한 섬유보강 시멘트 복합체의 손상 정도를 평가 할 수 있을 것으로 판단된다. 또한 휨 실험체의 경우 손상 을 평가하기 위하여 calm ratio, b-value 및 felicity ratio를 사용하였다. 이 연구의 목적은 섬유보강 시멘트 복합체의 손 상을 평가하는데 있어 음향방출 기법을 활용한 정량적 손상평가 방법의 적용 가능성을 평가하고 차후 연구를 위한 기 본 데이터를 확보하고자 한다.

• 터널과지하공간
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• 제27권2호
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• pp.77-88
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• 2017

연구지역의 지질은 주로 역암과 사암, 협재한 셰일 및 현무암류로 구성되고, 신생대 말에서 최근기간 동안 여러 번의 취성변형작용과 다양한 응력장을 거치면서 비교적 최근까지 움직임이 확인된 암반으로서 단층작용의 영향을 많이 받아 파쇄가 심한 완만한 지형을 형성한다. 비탈면은 북북동주향의 태곡단층과 서북서 주향의 북곡단층이 교차하는 지역에 위치하며, 그 구성 암반에는 여러 규모의 수많은 단층과 단층대 및 파쇄대가 발달하고 있다. 본 연구에서는 비탈면에 대한 지질특성을 파악하고 이에 따른 대책공법을 제시하고자 한다. 연구지역 비탈면에 대한 대책공법으로 시공 중 혹은 보강이 완료된 이후에도 주변도로 및 지반에 대한 안전관리를 위하여 각 구조물별 사안에 따라 계측기를 설치하여 주기적인 계측 및 분석이 꾸준히 수행되어야 할 것으로 사료된다.

• Archives of Plastic Surgery
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• 제39권5호
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• pp.556-560
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• 2012

Zygomatic fractures are the second most common facial bone fractures encountered and treated by plastic surgeons. Stable fixation of fractured fragments after adequate exposure is critical for ensuring three-dimensional anatomic reduction. Between January 2008 and December 2010, 17 patients with zygomatic fractures were admitted to our hospital; there were 15 male and 2 female patients. The average age of the patients was 41 years (range, 19 to 75 years). We exposed the inferior orbital rim and zygomatic complex through a lateral brow, intraoral, and subciliary incisions, which allowed for visualization of the bone, and then the fractured parts were corrected using the Carroll-Girard T-bar screw. Postoperative complications such as malar asymmetry, diplopia, enophthalmos, and postoperative infection were not observed. Lower eyelid retraction and temporary ectropion occurred in 1 of the 17 patients. Functional and cosmetic results were excellent in nearly all of the cases. In this report, we describe using the Carroll-Girard T-bar screw for the reduction of zygomatic fractures. Because this instrument is easy to use and can rotate to any direction and vector, it can be used to correct displaced zygomatic bone more accurately and safely than other devices, without leaving facial scars.

• 한국지열·수열에너지학회논문집
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• 제8권2호
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• pp.55-60
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• 2012

In many cases, geothemal wells will not be opened up a geothermal reservoir under such conditions that an extraction of geothermal energy is economically viable without any further measures. Geothermal wells often have to be stimulated, in order to increase productivity. For the non-volcanic area, such as Korea, the hydraulic stimulation is necessary to complete geothermal power plant. The analysis of induced seismic event showed that the thermal resource might have a much wider extent and a much higher generation potential than previously assumed. In order to record compressional and shear waves emitted during fracture stimulation, three-component geophones are placed in a seismometer. The recorded data from one seismometer is the convolution of the source magnitude, the transmission media, and the sensitivity of the instrument.

• Structural Engineering and Mechanics
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• 제39권1호
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• pp.77-91
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• 2011

A simply structural damage detection software is developed to identification damage in beams. According to linear fracture mechanics theory, the localized additional flexibility in damage vicinity can be represented by a lumped parameter element. The damaged beam is modeled by wavelet-based elements to gain the first three frequencies precisely. The first three frequencies influencing functions of damage location and depth are approximated by means of surface-fitting techniques to gain damage detection database of forward problem. Then the first three measured natural frequencies are employed as inputs to solve inverse problem and the intersection of the three frequencies contour lines predict the damage location and depth. The DLL (Dynamic Linkable Library) file of damage detection method is coded by C++ and the corresponding interface of software is coded by virtual instrument software LabVIEW. Finally, the software is tested on beams and shafts in engineering. It is shown that the presented software can be used in actual engineering structures.

• Restorative Dentistry and Endodontics
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• 제46권3호
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• pp.46.1-46.9
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• 2021

The aim of this review was to evaluate the effects of different access cavity designs on endodontic treatment and tooth prognosis. Two independent reviewers conducted an unrestricted search of the relevant literature contained in the following electronic databases: PubMed, Science Direct, Scopus, Web of Science, and OpenGrey. The electronic search was supplemented by a manual search during the same time period. The reference lists of the articles that advanced to second-round screening were hand-searched to identify additional potential articles. Experts were also contacted in an effort to learn about possible unpublished or ongoing studies. The benefits of minimally invasive access (MIA) cavities are not yet fully supported by research data. There is no evidence that this approach can replace the traditional approach of straight-line access cavities. Guided endodontics is a new method for teeth with pulp canal calcification and apical infection, but there have been no cost-benefit investigations or time studies to verify these personal opinions. Although the purpose of MIA cavities is to reflect clinicians' interest in retaining a greater amount of the dental substance, traditional cavities are the safer method for effective instrument operation and the prevention of iatrogenic complications.

• 대한치과기공학회지
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• 제34권2호
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• pp.95-103
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• 2012

Purpose: Fracture strength of all-ceramic 3-unit fixed partial dentures manufactured by CAD/CAM and copy-milling systems were evaluated. Methods: Zirconia cores were made by milling the pre-sintered zirconia block by CAD/CAM or copy milling method followed by subsequent sintering. By building-up the corresponding porcelains on the core, all-ceramic bridges were fabricated, and those were evaluated in comparison with PFM fixed partial denture. Results: During the flexural test of the 3-unit PFM bridge, the porcelain started to chip or break at 507.28(${\pm}62.82$)kgf and the metal framework did not break until the maximum load level of 800kgf which was set in the testing instrument of this study. However, among all-ceramic restoration test groups, Everest(EV) group showed a peeling off or breakage of the porcelain from 365.64(${\pm}64.96$)kgf and the core was broken at 491.77(${\pm}55.62$)kgf. Those values of Zirkonzahn(ZR) were 431.03(${\pm}58.47$)kgf and 602.74(${\pm}48.44$)kgf, respectively. The break strength of the porcelain of PFM(PM) group was significantly higher than that of EV (p<0.05) group and there was no significant difference when comparing to that of ZR (p>0.05). ZR group showed higher break strength than that of EV group however there was no significant difference (p>0.05). The break strength of cores were in the increasing order of EV < ZR < PM (p<0.05). Conclusion: We could find that even though the PM group fractured at much higher value than all-ceramic cores, the breakage values of the porcelain of PM group with crack formation or delamination, which will be regarded as clinical failure, was significantly higher than that of EV group and not significantly higher than that of ZR group at p-values of 0.05. The break strength of ZR group was higher than that of EV group at an insignificant level(p>0.05).

• Journal of Korean Neurosurgical Society
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• 제44권5호
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• pp.303-307
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• 2008

Objective: The authors reviewed clinical and radiological outcomes in patients with three column injury of the cervical spine who had undergone posterior cervical fixation using Nitinol shape memory alloy loop in the anterior-posterior combined approach. Materials: Nine patients were surgically treated with anterior cervical fusion using an iliac bone graft and dynamic plate-screw system, and the posterior cervical fixation using Nitinol shape memory loop ($Davydov^{TM}$) at the same time. A retrospective review was performed. Clinical outcomes were assessed using the Frankel grading method. We reviewed the radiological parameters such as bony fusion rate, height of iliac bone graft strut, graft subsidence, cervical lordotic angle, and instrument related complication. Results: Single-level fusion was performed in five patients, and two-level fusion in four. Solid bone fusion was presented in all cases after surgery. The mean height of graft strut was significantly decreased from $20.46{\pm}9.97mm$ at immediate postoperative state to $18.87{\pm}8.60mm$ at the final follow-up period (p<0.05). The mean cervical lordotic angle decreased from $13.83{\pm}11.84^{\circ}$ to $11.37{\pm}6.03^{\circ}$ at the immediate postoperative state but then, increased to $24.39{\pm}9.83^{\circ}$ at the final follow-up period (p<0.05). There were no instrument related complications. Conclusion: We suggest that the posterior cervical fixation using Nitinol shape memory alloy loop may be a simple and useful method, and be one of treatment options in anterior-posterior combined approach for the patients with the three column injury of the cervical spine.

• Restorative Dentistry and Endodontics
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• 제30권4호
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• pp.294-302
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• 2005

본 연구는 ProFile, ProTaper 및 K-Flexofile로 근관 성형시 근관의 만곡도에 따라 근관의 형태가 어떻게 변화하는지를 비교 분석하고자 시행되었다. ISO #15 finger spreader를 15도, 30도 및 45도로 만곡시키고 에폭시 레진으로 각각도의 근관을 갖는 30개의 근관 모형을 제작하였다. 근관의 길이는 18mm로 하였고 근관의 만곡은 근관의 입구로부터 10mm 부위에서 시작하도록 제작하였다. 근관 성형에는 엔진 구동형 니켈-타이타늄 파일인 ProFile과 ProTaper, 수동형 stainless steel 파일인 K-Flexofile을 사용하였다. ProFile과 ProTaper는 제조자의 지시에 따라 크라운다운법으로 근관 성형하였고, K-Flexofile은 스텝백법으로 근관 성형하였다. 근첨부 성형은 #25파일 크기까지 시행하였다. 근관 성형 전 후 이미지를 스캐너를 이용하여 얻고 Photoshop 7.0프로그램을 이용하여 중첩하였다. 이미지 분석 프로그램을 이용하여 치근단 쪽에서부터 1, 2, 3, 4, 5, 6, 7, 8, 9및 10mm부위의 내 외측 폭경 변화와 총폭경 및 근관의 중심축에 대한 근관 변위을 측정하였다. 각 부위에서 내 외측 폭경과 총폭경 및 근관 변위의 유의성 검정을 위해 one-way ANOVA분석을 시행하였으며 각 기구간의 유의성 검정은 Scheffe's test로 사후 분석하였다. 또한 기구의 변형과 파절 여부를 평가한 결과 엔진 구동형 니켈-타이타늄 파일인 ProFile과 ProTaper를 사용하여 근관성형시 수동형 스테인레스 스틸 파일인 K-Flexofile에 비해 근관의 변위를 적게 유발하고 특히 ProFile이 근관 성형시 바람직한 기구임을 시사하였다.