• Journal of Chest Surgery
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• 제43권1호
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• pp.1-10
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• 2010

배경: 심장 혈관계 수술에서 인공 조직 보철편은 주로 소나 돼지 판막, 심낭의 글루타알데하이드 고정 방법을 사용하고 있으나 중장기적으로 이식편의 석회화 및 물리-기계적인 결함이 문제시 되고 있다. 이 중 본 연구에서는 소의 심낭에 글루타알데하이드 고정, 용매, 무세포화, 항독성화 처리가 조직의 물리-기계적 장력 및 신장도에 미치는 영향을 알아보고자 하였다. 대상 및 방법: 아무런 처리를 하지 않은 신선한 소의 심낭과 여러 방법의 글루타알데하이드 고정 및 용매 첨가 그룹, 무세포화 그룹, 항독성화 처리 그룹 등으로 나누어 각 조직의 물리-기계적 장력 및 신장도 검사를 시행하였다. 심낭을 30도 각도로 달리하여 얻어낸 6가지 방향에 대하여 폭 5 mm에 대한 인장 강도를 구하여 장력을 측정하였고, 양방향으로 늘려 끊어지는 시점에서의 길이를 측정하여 늘어난 정도를 구하여 신장도를 측정하였다. 결과: 1) 상용 농도의 글루타알데하이드 고정시 장력이 감소하며(n=83, $MPa=11.47{\pm}5.40$, p=0.006) 용매를 첨가하였을 때 장력의 변화는 관찰되지 않았다. 신장도는 글루타알데하이드 고정시 늘어났으며(n=83, strain $(%)=24.55{\pm}9.81$, p=0.00), 용매 첨가시 신장도의 변화는 관찰되지 않았다. 2) 무세포화 처리시 대부분의 장력은 감소하는 경향을 보였으며(p>0.05) 장기간 저농도 용액 처리, 고농도의 세정용매 처리시 장력의 감소가 통계적으로 유의했으며(p=0.01, p=0.00), 신장도는 늘어나는 경향을 보였다. 3) 항독성화 처리 시 장력 및 신장도에 유의한 차이를 보이지 않았다. 결론: 소의 심낭에 글루타알데하이드 고정, 용매, 항독성화 처리 후에는 장력 손실이 관찰되지 않으며 신장도는 증가하는 경향을 보였다. 무세포화에 따른 장력의 손실이 뚜렷하였으나 저 농도 세정제 사용과 고농도 용액처리를 보강한 무세포화 처리에서는 장력의 손실이 향상되었다. 계속해서 더 나은 이식 보철편개발을 위한 다양한 용매의 연구 개발이 필요하다.

• Journal of Chest Surgery
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• 제50권4호
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• pp.229-234
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• 2017

Rib fractures are a common injury resulting from blunt chest trauma. The most important complications associated with rib fractures include death, pneumonia, and the need for mechanical ventilation. The development of new osteosynthesis materials has stimulated increased interest in the surgical treatment of rib fractures. Surgical stabilisation, however, is not needed for every patient with rib fractures or for every patient with flail chest. This paper presents an easy-to-use evidence-based algorithm, developed by the authors, for the treatment of patients with flail chest and isolated rib fractures.

• 한국CDE학회논문집
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• 제5권2호
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• pp.122-126
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• 2000

A major mechanical problem with total hip replacement is the loosening of the femoral component. The loss of proximal support, with firm fixation distally, has been thought to be a major caused of fatigue failure of femoral stems. While many causes have been proposed, the most frequently suggested cause of the calcar resorption is the disuse atrophy of the cortex of the calcar due to the stress shielding of the proximal bone by the metal femoral stem. In this research, the new-designed stem(modified collar stem) was considered which made a hole inside stem and had a 3 mm thickness. Using the 3-dimensional finite element methods, the common collar stem and the modified colla stem was modeled and analysed. Also, the two models was compared. The results showed that the modified collar stem decreased the stress-shielding and it made a effective load transfer at the entire femoral region.

• 한국군사과학기술학회지
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• 제17권1호
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• pp.142-148
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• 2014

The mirror which is considered in designing a MFD is off-axis primary one and its dimension is wide 556mm height 345mm. The MFD(Mirror Fixation Device) load specification is generated for the high resolution mirror. The optical WFEs for unit loads are calculated from mirror sensitivity analysis and they are compared with allocated allowable optical WFE. The parasite load for the MFD is calculated from their comparison. The MFD compliant with the parasite load is designed.

• 한국수소및신에너지학회논문집
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• 제35권2호
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• pp.195-204
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• 2024

The study involves a finite element analysis to evaluate the structural integrity of the neck mount block for a type 4 hydrogen storage vessel, with the aim of enhancing its strength and rigidity. The existing neck mount block consists of a fixed part and a sliding part, each comprising a body block for load support, a screw part for neck boss fixation, and bolts. To analyze the vulnerabilities of the neck mount block under bolt fastening and load conditions relative to vehicle travel directions, a structural analysis process was developed. Comparative analysis between the enhanced design and the existing model was performed, resulting in improved strength and rigidity. The objective is to provide guidance for the current product development and to offer fundamental data for the design and structural analysis of future development projects.

• Journal of Korean Neurosurgical Society
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• 제62권4호
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• pp.422-431
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• 2019

Objective : In an aging society, the number of patients with symptomatic degenerative spondylolisthesis (DS) is increasing and there is an emerging need for fusion surgery. However, few studies have compared transforaminal lumbar interbody fusion (TLIF) and lateral lumbar interbody fusion (LLIF) for the treatment of patients with DS. The purpose of this study was to investigate the clinical and radiological outcomes between TLIF and LLIF in DS. Methods : We enrolled patients with symptomatic DS at L4-5 who underwent TLIF with open pedicle screw fixation (TLIF group, n=41) or minimally invasive LLIF with percutaneous pedicle screw fixation (LLIF group, n=39) and were followed-up for more than one year. Clinical (visual analog scale and Oswestry disability index) and radiological outcomes (spondylolisthesis rate, segmental sagittal angle [SSA], mean disc height [MDH], intervertebral foramen height [FH], cage subsidence, and fusion rate) were assessed. And we assessed the changes in radiological parameters between the postoperative and the last follow-up periods. Results : Preoperative radiological parameters were not significantly different between the two groups. LLIF was significantly superior to TLIF in immediate postoperative radiological results, including reduction of spondylolisthesis rate (3.8% and 7.2%), increase in MDH (13.9 mm and 10.3 mm) and FH (21.9 mm and 19.4 mm), and correction of SSA ($18.9^{\circ}$ and $15.6^{\circ}$) (p<0.01), and the changes were more stable from the postoperative period to the last follow-up (p<0.01). Cage subsidence was observed significantly less in LLIF (n=6) than TLIF (n=21). Fusion rate was not different between the two groups. The clinical outcomes did not differ significantly at any time point between the two groups. Complications were not statistically significant. However, TLIF showed chronic mechanical problems with screw loosening in four patients and LLIF showed temporary symptoms associated with the surgical approach, such as psoas and ileus muscle symptoms in three and two cases, respectively. Conclusion : LLIF was more effective than TLIF for spondylolisthesis reduction, likely due to the higher profile cage and ligamentotactic effect. In addition, LLIF showed mechanical stability of the reduction level by using a cage with a larger footprint. Therefore, LLIF should be considered a surgical option before TLIF for patients with unstable DS.

• 한국결정성장학회지
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• 제22권5호
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• pp.254-259
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• 2012

순환유동층 연소방식의 화력발전소에서 석탄을 연소시킨 후 발생하는 석탄재 중 탄산화 반응 인자인 Ca 성분을 다량 포함한 비산회를 시멘트에 일정량 치환하여 제조한 인공경량 경화체를 초임계상태에서 이산화탄소($CO_2$)를 고정화하여 골재의 기계적 물성향상을 도모하였다. 초임계 분위기 $40^{\circ}C$ 조건에서 비산회의 치환량을 변화시켜 재령일수별 탄산화를 시행하였다. 비산회 치환량에 따른 탄산화 반응시킨 인공경량골재 경화체의 무게변화율, TG/DTA 분석, 1 % 페놀프탈레인 알칼리성 측정을 통하여 탄산화 진행여부를 확인하였으며 28일까지의 재령 이후 경화체의 압축강도 측정과 비중측정을 통하여 골재의 기계적 물성향상과 인공경량골재의 기준 비중치인 2.0 이하의 비중값을 갖는 탄소고정 인공경량골재 경화체를 얻는 것이 가능할 것으로 판단되었다.

• Clinics in Shoulder and Elbow
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• 제17권1호
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• pp.10-17
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• 2014

Background: The aim of this study was to assess the clinical outcomes after treatment of proximal humeral fractures with locking plates, and to determine which factors influence the clinical and radiological outcomes. Methods: Fifty six patients who were treated with locking plates for proximal humeral fractures and had been followed for more than 1 year were enrolled in this study. We performed functional evaluation using the Constant score and analyzed radiographic results. The following factors that may potentially influence the clinical outcomes were assessed: age, gender, type of fracture, presence of medial metaphyseal comminution, bone mineral density, anatomical reduction, restoration of medial mechanical support, and postoperative complications. Results: The mean Constant score was 70.1 points at the final follow-up. Female gender, 4-part fractures, AO type-C fractures, and fractures with medial metaphyseal comminution were associated with a poor clinical outcome. On the other hand, restoration of medial mechanical support and accurate anatomical reduction had a positive influence on clinical outcomes. Postoperative complications resulted in 3 patients (intra-articular screw perforation: 1 patient, varus deformity with screw loosening: 1 patient, nonunion: 1 patient). Conclusions: When treating proximal humeral fractures with locking plate fixation, following factors: a female gender, Neer type 4-part fracture, AO type C fracture, and medial metaphyseal comminution are important risk factors that surgeons should take into consideration. Factors that contribute to better clinical outcomes of operative treatment for humeral fractures are accurate anatomical reduction and restoration of medial mechanical support.

• 대한의용생체공학회:의공학회지
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• 제17권1호
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• pp.61-70
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• 1996

In cementless total hip arthroplasty(THA), an initial stability of the femoral component is mandatory to achieve bony inyowth and secondary long term fixation. Primary stability of the femoral component can be obtained by minimizing the magnitude of relative micromotions at bone stem interface. An accurate evaluation of interf'ace micromotion and stress/strain fields in the bone-implant system may be relevant for better understanding of clinical situations and improving THA design. Recently finite element method(FEM) was introduced in'orthopaedic research field due to its unique capacity to evaluate stress in structure of complex shape, loading and material behavior. The authors developed the 3-dimensional finite element model of proximal femur with $Multilock^{TM}$ stem of 1179 blick elements to analyse the micromotions and mechanical behaviors at the bone-stem inteface in early post-operative period for the load simulating single leg stance. The results indicates that the values of relative motion for this well fit stem were $150{\mu}m$ in maximum $82{\mu}m$ in minimum and the largest relative motion was developed in medial region of Proximal femur and in anterior-posterior direction. The motion in the proximal bone was much greater than in the distal bone and the stress pattern showed high stress concentration on the cortex near the tip of the stem. These findings indicate that the loading on the hip joint in the early postoperative situation before achieving bony ingrowth could produce large micromotion of $150{\mu}m$ and clinicaly non-cemented THA patient should not be allowed weight bearing strictly early in the postoperative period.

• 대한의용생체공학회:의공학회지
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• 제26권2호
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• pp.123-127
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• 2005

Compression Hip Screw (CHS) is one of the most widely-used prostheses for the treatment of intertrochanteric fractures because of its strong fixation capability. Fractures at the neck and screw holes are frequently noted as some of its clinical drawbacks, which warrant more in-depth biomechanical analysis on its design variables. The purpose of this study was to evaluate changes in the strength with respect to the changes in design such as the plate thickness and the number of screw holes. Both mechanical test and FEM analysis were used to systematically investigate the sensitivities of the above-mentioned design variables. For the first part of the mechanical test, CHS (n=20) were tested until failure. The CHS specimens were classified into four groups: Group Ⅰ was the control group with the neck thickness of 6-㎜ and 5 screw holes on the side plate, Group Ⅱ 6-㎜ thick and 8 holes, Group Ⅲ 7.5-㎜ thick and 5 holes, and Group Ⅳ 7.5-㎜ thick and 8 holes. Then, the fatigue test was done for each group by imparting 50% and 75% of the failure loads for one million cycles. For the FEM analysis, FE models were made for each group. Appropriate loading and boundary conditions were applied based on the failure test results. Stresses were assessed. Mechanical test results indicated that the failure strength increased dramatically by 80% with thicker plate. However, the strength remained unchanged or decreased slightly despite the increase in number of holes. These results indicated the higher sensitivity of plate thickness to the implant strength. No fatigue failures were observed which suggested the implant could withstand at least one million cycles of fatigue load regardless of the design changes. Our FEM results also supported the above results by showing a similar trend in stress as those of mechanical test. In summary, our biomechanical results were able to show that plate thickness could be a more important variable in design for reinforcing the strength of CHS than the number of screw holes.