• 대한의용생체공학회:의공학회지
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• 제29권2호
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• pp.132-138
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• 2008

We investigated the biomechanical properties of a newly designed self-expansion type anterior cruciate ligament (ACL) anchor. The ACL anchor consists of the ring section giving the elastic force, the wedge for maintaining in contact with the femur tunnel wall and the link suspending hamstring graft or artificial ligament. The main design parameters that determine the performance of this device were the expansion angle (${\theta}$) and the thickness ($t_R$). The Ti6Al4V anchors were heated after inserting in a jig for 1 hour at $800^{\circ}C$ in a protective argon gas atmosphere and allowed to cool to room temperature in the furnace. In order to investigate the influence of the expansion angle and the thickness of the ring on the biomechanical properties of the anchor, the maximum pull-out load, stiffness and slippage of the ACL anchor were measured using the pull-out tester, and statistical analyses were also executed. The present results showed that the design parameters gave a significant effect on the performance of the self- expansion type of anchor. The pull-out load of the ACL anchors significantly increased as the thickness of the ring section was increased, having a similar trend for both expansion angles. The ACL anchor showed about 2.5 times higher values of the pull-out load than that of the minimum load (500N)required for the "accelerated rehabilitation". The optimum ${\theta}$ and $t_R$ values of this ACL anchor were suggested to have sufficient resistance against the pull-out force, high stiffness and relatively low slippage after ACL reconstruction.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 추계학술대회
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• pp.71-74
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• 1994

In cementless total hip arthroplasty(THA), an initial stability of the femoral component is mandatory to achieve bony ingrowth and secondary long term fixation. Bone ingrowth depends strongly on relative micromotion and stress distributions at the interface. Primary stability of the femoral component can be obtained by minimizing the magnitude of relative micromotions at bone-prosthesis interface, Hence an accurate evaluation of interface behavior and stress/strain fields in the bone implant system may be relevant for better understanding of clinical situations and improving THA design. However, complete evaluation of load transfer in the bone remains difficult to assess experimentally, Hence, recently finite element method (FEM) was introduced in orthopaedic research field to fill the gap due to its unique capacity to evaluate stress in structure of complex shape, loading and material behavior. The authors developed the 3-dimensional numerical finite element model which is composed of totally 1179 elements off and 8 node blick. We also analyzed the micromotions at the bone-stem interface and mechanical behavior of existing bone prosthesis for a loading condition simulating the single leg stance. The result indicates that the values of relative motion for this well fit Multilock stem were $150{\mu}m$ in maximum, $82{\mu}m$ in minimum, and the largest relative motion developed in medial region of proximal femur with anterior-posterior direction. The proximal region of the bone was much larger in motion than the distal region and the stress pattern shows high stress concentration on the cortex near the tip of the stem. These findings indicates that the loading in the proximal femoral bone in the early postoperative situation can produce micromotions on the interface and clinically cementless TEA patient should not be allowed weight bearing strictly early in the postoperative period.

• 한국산학기술학회논문지
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• 제19권1호
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• pp.63-68
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• 2018

본 논문은 이산화탄소 고정 과정이 포함된 인공 광합성 과정을 모사하기 위하여 지구상에 흔히 존재하는 촉매 재료를 이용해 개발한 광화학 반응 시스템(인공나뭇잎)과 시스템 에너지 포집 및 변환 능력에 대한 성능을 조사하기 위한 기초 연구 결과를 제시한다. 본 연구에서 개발한 시스템은 태양광 전지의 전면부에 산화코발트를 도핑 하여 물의 전기분해로 인한 산소 발생이 태양전지 표면에서 직접 발생하도록 하였고, 후면 기판 표면에는 이산화탄소 변환 반응을 위한 효율적인 촉매로 $MoS_2$를 도핑 하여, 전선이 없는 구조로 구성하였다. 직접 태양광 연료 변환 시스템은 약4.5%로 이산화탄소를 일산화탄소와 수소로 변환하여 지속 가능한 연료(합성가스)의 형태로 생산하며, 이는 음극에서 촉매 변환 효율이 75%이상이 될 수 있음을 의미한다. 본 연구는 물의 광분해뿐만 아니라 태양광에 의해 유도된 이산화탄소 전환 과정을 하나의 시스템에서 동시에 실현하여 자연적 광합성 과정을 좀 더 성공적으로 모사할 수 있는 시스템 개발에 기여하였다.

• Journal of Korean Neurosurgical Society
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• 제44권1호
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• pp.52-56
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• 2008

Objective : The purpose of this study was to introduce our surgical experiences of scoliosis and to evaluate the effectiveness of anterior correction and fusion in adolescent idiopathic scoliosis (AIS). Methods : Between August 2004 and August 2007, four patients with AIS were treated with anterior segmental fusion and fixation at our hospital. Mean follow-up period was 9 (6-12) months. The average age was 14.0 (13-15) years. According to Lenke classification, three patients showed Lenke 1 curve and one patient with Lenke 5 curve. Single rod instrumentation was performed in one patient, dual rod instrumentation in one patient and combined rod instrumentation in two patients. Coronal Cobb measurements were performed on all curves in thoracic, thoracolumbar and, lumbar spine and the angle of hump was measured by a scoliometer pre- and postoperatively. Results : The average operative time was 394 minutes (255-525) with an average intraoperative blood loss of 1,225 ml (1,000-1,700). The mean period of hospital stay was 19.3 days and there was no complication related to the surgery. The mean Cobb angle was reduced from $43.3^{\circ}$ to $14.8^{\circ}$ (65.8% correction) postoperatively and the rib hump corrected less than $5^{\circ}$. All patients and their parents were satisfied with the deformity correction. Conclusion : Anterior spinal correction and fusion of AIS with Lenke 1 and 5 curve showed excellent deformity correction without any complications. In particular, we recommend anterior dual rod instrumentation because of mechanical stability, better control of kyphosis, and a higher fusion rate.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제14권4호
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• pp.327-339
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• 1992

This study was undertaken to investigate the effect of orthognathic surgery on occlusal force. The maximum bite force was measured in 26 dentofacial deformity patients, aged 14-26(mean age 20.3) years, before surgery and at IMF removal, 3, 6, and 12months postsurgery. To grope the correlation of bite force and skeletal change after orthognathic surgery, the cephalometric headplates were measured, tabulated and statistically analyzed. The results were as follows. 1. The presurgical maximum bite force was 13.7kg in upper first molar(rt. Side 12.7kg, it. Side 14.6kg). There was remarkable difference with that of normal occlusion. 2. The recovery of bite force was very significant in according to the operation method and the duration of IMF that was 7.6kg at IMF removal, 14.2kg at 3 months, 19.7kg at 6 months. 26.1kg at 12 months postsurgery. 3. To fasten the recovery and to increase the bite force after orthognathic surgery, the long IMF time and the injury to the masticatory muscle should be avoided by the internal rigid fixation and early physical exercise. 4. The bite force was positively correlated to the changes of mandibular plane angle, the angle between platatal plane and mandibular plan, the angle between occlusal plane and mandibular plane, and negatively correlated to the changes of mandibular body length in craniofacial structure. 5. There was no correlationship between bit force and mesial inclination of tooth long axis of first molar in this subject. 6. There was no correlation between the changes of bite force and the changes of mechanical advantage of the temporal and masseter muscle.

• 한국지반공학회논문집
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• 제33권10호
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• pp.59-69
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• 2017

지반내 근입된 앵커의 인장력은 시간이 경과하면서 점차 변화하게 되는데 이때 초기 인장력의 변화는 보통 정착헤드의 정착조건과 인장자재의 기계적 특성에 의해 1차적으로 감소하게 되며, 이후 추가적인 인장력의 변화는 대부분 정착장의 정착조건과 주변 지반특성에 기인한 시간의존적인 정착거동에 좌우된다. 따라서 본 논문에서는 이러한 인장력 변화를 비교적 쉽게 측정 및 분석할 수 있는 상대변위측정기를 이용한 측정시스템에 대해서 연구하였다. 검토결과 실규모 모형시험을 통해서 본 측정시스템의 적용성을 확인 하였으며, 또한 풍화암에 정착된 지반앵커를 대상으로 실시한 현장 시험결과와도 유사함을 확인함에 따라 본 측정시스템의 적용성을 확인하였다. 그리고 초기인장력이 비교적 크게 감소된 시험앵커를 대상으로 추가적인 인발시험을 실시하였으며 이를 통해 인장형 앵커의 인발거동을 확인하였다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 춘계학술대회
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• pp.19-22
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• 1995

A biomechanical study was made to demonstrate the superior mechanical performance of the newly designed Miniplate staple to the conventional Coventry staple in high tibial osteotomy(HTO). Using twenty fresh porcine tibiae, the fixational strengh of the two different types of staple in HTO was compared. To minimize the error due to the specimen-to-specimen individuality, the bone mineral density of the tibiae was measured with a bone densitometry (Dual photon absorptionometer, Luner, USA) and those with $0.8\;{\sim}\;1.2\;gm/cm^2$ at the proximal tibia was used in the biomechanical test. Testing was performed on a material testing system (Autogram ET-5, Shimatzu, Japan) with aid of a commercial data processor (IBM 80386/ ASYST). Using two differant loading modes, 'pull-out' and 'push-out', the maximum resistant force required to release the staple from the substrate bone was recorded. In the pull-out test, ten non-osteotomized specimens were used and the staple was pullout by subjecting an axial tension on the head of the staple inserted. While in the pull-out test where ten tibiae osteotomized in the usual way of HTO were used, the staple was not directly loaded. In this testing, as a mimic condition of the natural knee, the distal part of the specimen tibia was pushed horizontally in order for the staple to be pulled out while the proximal tibia was fixed. The pull-out strength of Coventry staple and miniplate staple were found to be $27.88\;{\pm}\;5.12\;kgf$ and $182.47\;{\pm}\;32.75\;kgf$, respectively. The push-out strength of Coventry staple and miniplate staple were $18.40\;{\pm}\;4.47\;kgf$ and $119.95\;{\pm}\;19.06\;kgf$, respectively. The result revealed that miniplate staple had the pull-out/ push-out strength at least fivetimes higher than Coventry staple. Based on the measured data, it was believed that the newly designed miniplate staple could provide much better postoperative fixation in HTO. The postoerative application of long leg casting may not be needed after HTO surgery.

• 대한정형외과학회지
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• 제55권3호
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• pp.193-199
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• 2020

골수강 내 금속정(골수정)은 1988년부터 대퇴골 전자간 골절을 치료하는 데 사용되어 왔다. 골수정은 활강고나사와 같은 골수강 외 고정 장치에 비하여 기계적 이점이 있으나 대퇴 전자간 골절 Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) 31-A1 및 31-A2 골절 치료에 활강고나사보다 유리한 고정 기구인지에 대해서는 논란이 계속되고 있다. 지난 30년 동안 여러 시행 착오가 극복되었고 새로운 유형의 대퇴 골수정이 개발되어 임상에서 사용되고 있다. 새로 개발된 골수정은 삽입 과정이 쉬워지고 지연나사를 사용한 대퇴 골두의 고정 능력이 향상되어 왔다. 그러나 고정 실패율은 여전히 정형외과 의사의 수술 술기에 달려 있다고 할 수 있다. 이 종설에서 우리는 골수정을 이용하여 대퇴 전자간 골절을 치료하는 동안 내측 지지대 복원의 중요성에 대해 초점을 맞추고 그 기본 원칙에 대하여 논의해 보고자 한다.

• Journal of the Korean Wood Science and Technology
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• 제51권2호
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• pp.133-144
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• 2023

Densification is an effective method for improving the physical and mechanical properties of low-density wood. However, the set-recovery of dimensions was found to be the problem of densified wood due to low fixation during the densification process. Alkali pretreatment before densification is thought to be a modification process to improve the dimensional stability of densified wood. In this research, the wood samples used were boiled in a 1.25 N sodium hydroxide (NaOH) solution at different times, followed by densification for 5 h at 100℃. The alkali pretreatment for 1, 3, and 5 h of boiling increased the dimensional stability of densified woods and anti-swelling efficiency values were 8.52%, 63.24%, and 48.94%, respectively. The boiling of wood in NaOH solution decreased the holocellulose content, as well as lignin to a lesser degree, and a lower crystallinity index was observed. The lower hydroxyl groups and a higher proportion of lignin in treated samples seem to have contributed to the high dimensional stability detected.

• Journal of Chest Surgery
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• 제41권2호
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• pp.170-176
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• 2008

배경: 지금까지 심장 및 혈관 등의 결손을 교정하기 위해 자기 조직이 아닌 다른 보철편의 필요가 늘어나 그에 따른 다양한 대체제가 연구 개발, 이용되고 있다. 본 연구는 새로운 조직의 처리방법을 개발하기 위하여 이미 상용화되고 있는 기존의 이종이식 보철편들과, 여러 가지 조건들에서 제조되는 돼지 심낭의 보철편들이 임상적용 전에 기계적, 물리적 조건들로서 이종이식 보철편의 적절한 두께, 장력 등의 관계와 변화를 알아보고자 하였다. 대상 및 방법: 1) 돼지 심낭을 0.625% 혹은 1.5%, 3%의 glutaraldehyde 용액에 고정하여 각각의 장력과 두께를 측정하였다. 2) 아무런 처치하지 않은 돼지 심낭과 사람 심낭, 그리고 상용화되고 있는 기존의 이종이식 보철편들의 장력과 두께를 측정하였다. 3) 0.625% glutaraldehyde 고정 전과 고정 후 80% Ethanol 처리한 군과, sodium dodecylsulfate (SDS) 처리로 무세포화만 시행한 군, 무세포화과정 후에 0.625% glutaraldehyde 고정한 군, 80% ethanol 처리 후 다시 무세포화과정을 한 후 0.625% glutaraldehyde 고정한 군, 무세포화 한 후 다시 ethanol 처리 후 0.625% glutaraldehyde 고정한 군으로 나누어 각각의 장력과 두께를 측정하였다. 결과: 1) 일반적으로 사용 돼지심낭의 두께와 장력과의 상관관계가 있었으며, GA 농도를 올릴수록 두께의 증가와 함께 장력도 커졌으며, 아무런 처리를 하지 않은 돼지 심낭의 경우도 GA 처리한 심낭과 비슷한 두께와 장력을 보여 주었다. 이식편의 두께가 0.1 mm 이상에서 두께-장력간에 유의한 상관관계가 있었다 (상관계수 0.514, 유의확률 <0.001). 2) 기존의 이종이식 보철편 간에는 두께나 장력에서는 차이가 없었다. 3) GA, ethanol, SDS 무세포화 처리효과는 심낭의 두께에 통계적인 차이는 있었지만 그 영향은 크지 않았으며, 이러한 여러 처리과정 중 심낭조직의 손상으로 인한 장력의 손실은 없는 것으로 생각되며, SDS를 사용하여 무세포화 처리만 하고 GA 고정치 않은 심낭의 장력이 가장 작았다. 결론: 이종이식 돼지심낭 보철편의 적절한 두께는 적어도 0.1 mm 이상이어야 사용하기 적절하고 장력에도 유려하며, 여러 조건하의 심낭조직 고정 방법들에 따라 두께나 장력의 확연한 차이를 보이지 않아, GA를 이용한 각종 조직 처리과정 중 조직손상에 의한 구조적, 기계적 손실은 없는 것으로 생각되며, 그러나 먼저 무세포화한 후 24시간 ethanol 처리 후 다시 0.625% glutaraldehyde 고정용액에 추가 2주간 고정한 심낭이 두께와 높은 장력을 보여 주었다.