• 한국정밀공학회지
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• 제12권11호
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• pp.82-90
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• 1995

This paper pressents a condition-based maintenance (CBM) method through bibration analysis. The well known frequency analysis is employed for performing machine fault diagnosis. The statistical control chart is also applied for analyzing the trend of the bearing wear. Vibration sensors are attached to prototype machine and signals are continuously monitored. The sampled data are utilized to evaluate how well the fast fourier transform(FFT) and the statistical control chart techniques could be used to identify defects of machine and to analyze the machine degradation. Experimental results show that the propowed approach could classify every mal-function and could be utilized for real machine diagnosis system.

• 대한족부족관절학회지
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• 제11권2호
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• pp.221-225
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• 2007

Purpose: To evaluate the clinical results of operative treatment of the intra-articular calcaneal fracture with injectable calcium sulfate ($MIIG^{TM}$). Materials and Methods: Between March 2004 and October 2006, a total 19 intra-articular calcaneal fracture (16 patients) with a large bony defect that underwent operative treatment with plate fixation and injectable calcium sulfate ($MIIG^{TM}$) with minimum follow-up of one year following. The mean age at time of surgery was 44.7 years (23 to 54). All of the cases were type 2 and 3 on the basis of Sanders classification. The lateral L shaped approach was used in all cases. Full weight bearing on the affected extremity was regained at an average 10 weeks postoperatively. Results: The mean Bohler angle was improved from $2^{\circ}$ ($-18.5{\sim}12.5^{\circ}$) preoperatively to $23.8^{\circ}$ ($12{\sim}37.5^{\circ}$) and the angle at last follow-up was $22.5^{\circ}$ ($11.5{\sim}37.5^{\circ}$), showing about 0.3 degree decline compared to postoperative Bohler angle. Only two case of whitish leakage of graft material but other complication were none. Conclusion: $MIIG^{TM}$ augumentation of displaced intra-articular calcaneal fracture with large bone defect seems to bo useful method for initial stabilized and plate fixation.

• Archives of Reconstructive Microsurgery
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• 제17권1호
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• pp.28-35
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• 2008

The purpose of this study was to present the clinical analysis of the results of lateral arm free flap for small sized and infected diabetic foot ulcer around toes. From May 2006 to December 2007, Seven patients were included in our study. Average age was 52.8 years, six were males and one was female. All had infected diabetic foot ulcer and had exposures of bone or tendon structures. Ulcers were located around great toe in four patients, 4th toe in one and 5th toe in two. Three patients had osteomyelitis of metatarsal or phalanx. After appropriate control of infection by serial wound debridement and intravenous antibiotics, lateral arm flap was applied to cover remained soft tissue defects. Posterior radial collateral artery of lateral arm flap was reanastomosed to dorsalis pedis artery of recipient foot by end to side technique in all cases in order to preserve already compromised artery of diabetic foot. All flaps were designed over lateral epicondyle to get longer pedicle and averaged pedicle length was 8 cm. Two cases were used as a sensate flap to achieve protective sensation of foot. All flaps survived and provided satisfactory coverage of soft tissue defects on diabetc foot ulcers. All patients could achieve full weight-bearing ambulation. No patients has had recurrence of infection, ulceration and further toe amputations. There were three complications, a delayed wound healing of flap with surrounding tissue, a partial peripheral loss of flap and a numbness of forearm below donor site. All patients were satisfied with their clinical results, especially preserving their toes and could return to the previous activity levels. Lateral arm free flap could be recommend for infected diabetic foot ulcers around toes, to preserve toes, coverage of soft tissue defect and control of infection with low donor site morbidity.

• 한국임상수의학회지
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• 제33권5호
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• pp.300-303
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• 2016

An age-unknown, 4.8 kg, male, wild, domestic short-hair cat was presented for left hindlimb lameness. A physical examination revealed a draining tract which was suspected of bite on left calcaneal bone. The left tarsal joint was markedly swollen and exudates were observed around the draining tract. Sequestrum at left calcaneus bone, and osteolysis were identified by radiography. The sequestrum and its surrounding exudative tissue were debrided during surgery and the tissue was submitted for bacterial culture and sensitivity test. The debridement caused a bone defect ($1.5cm{\times}0.5cm{\times}0.5cm$) on the medial left calcaneal bone. Plate and screw fixation was performed to the calcaneus bone as buttress plate. Recombinant human bone morphogenetic protein-2 (rhBMP-2) loaded hydroxyapatite was implanted in the bone defect. Furthermore, Amikacin-impregnated collagen sponges were also placed around bone plate to deliver local antibiotics. A systemic antibiotic treatment regimen based on bacterial culture and sensitivity test results was administered for 4 weeks. The wound properly healed without any signs of infection, and the bone healing was confirmed by radiography. The patient showed normal weight bearing ambulation at 18 weeks after surgery. The use of rhBMP-2 and local antibiotic delivery system is a good surgical option for the one-stage treatment of chronic osteomyelitis.

• 구강회복응용과학지
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• 제34권4호
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• pp.331-337
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• 2018

상악골 결손을 갖고 있는 무치악 환자를 폐쇄장치로 수복할 때 임상가들은 많은 어려움을 겪게 된다. 결손부를 통한 공기의 누출, 안정성과 지지의 부족, 감소된 의치 피개 면적은 의치의 흡착과 변연 폐쇄를 어렵게 한다. 본 증례는 편평상피암에 이환된 우측 상악동 부위에 상악골 절제술을 받은 무치악 환자로 술전 치과 검진, 수술용 폐쇄장치, 이행 폐쇄장치, 그리고 최종 폐쇄장치에 이르는 단계적 치료 과정을 통해 보철적 재건을 완료하였다. 본 증례의 환자는 전상악골 및 양측 상악 결절이 온전하며 한정된 크기의 결손부를 가져 적절한 유지와 지지를 갖는 폐쇄장치를 제작할 수 있었으며 심미 및 기능면에서 양호한 예후를 보였기에 이를 보고하는 바이다.

• Advances in nano research
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• 제12권3호
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• pp.301-317
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• 2022

Many studies have shown that Mg-Nd-Zn-Zr (abbreviated as JDBM) alloy has good biocompatibility and biodegradability as well as promotion of cell adhesion, proliferation and differentiation, and Wnt/β-catenin signaling pathway may play a unique role in joint tissue by controlling the function of chondrocytes, osteoblasts and synoviocytes. However, it is not clear whether the JDBM alloy induces osteochondral repair through Wnt/β-catenin signaling pathway. This study aims to verify that JDBM alloy can repair osteochondral defects in rats, which is realized by Wnt/β-catenin signaling pathway. In this study, the osteochondral defect model of the right femoral condyle non-weight-bearing area in rats was established and randomly divided into three groups: Control group, JDBM alloy implantation group and JDBM alloy implantation combined with signaling pathway inhibitor drug ICRT3 injection. It was found that after JDBM alloy implantation, the bone volume fraction (BVF) became larger, the bone trabeculae were increased, the relative expression of osteogenesis gene Runx2, Bmp2, Opn, Ocn and chondrogenesis gene Collagen II, Aggrecan were increased, and the tissue repair was obvious by HE and Masson staining, which could be inhibited by ICRT3.

• Tribology and Lubricants
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• 제31권3호
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• pp.125-140
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• 2015

In this paper, we present the results of the wear analysis of journal bearings on a stripped-down single-cylinder engine during start-up and coast-down by motoring. We calculate journal bearing wear by using a modified specific wear rate considering the fractional film defect coefficient and load-sharing ratio for the asperity portion of a mixed elastohydrodynamic lubrication (EHL) regime coupled with previously presented graphical data of experimental lifetime linear wear in radial journal bearings. Based on the calculated wear depth, we obtain a new oil film thickness for every crank angle. By examination of the oil film thickness, we determine whether the oil film thickness at the wear scar region is in a mixed lubrication regime by comparing dimensionless oil film thickness, h/σ, to 3.0 at every crank angle. We present the lift-off speed and the crank angles involved with the wear calculation for bearings #1 and #2. The dimensionless oil film thickness, h/σ, illustrates whether the lubrication region between the two surfaces is still within the bounds of the mixed lubrication regime after scarring of the surface by wear. In addition, we present in tables the asperity contact pressure, the real minimum film thickness at the wear scar region, the modified specific wear rate, and the wear angle, α, for bearings #1 & #2. To show the real shape of the oil film at wear scar region, we depict the actual oil film thickness in graphs. We also tabulated the ranges of bearing angles related with wear scar. We present the wear volume for bearings #1 and #2 after one turn-on and turn-off of the engine ignition switch for five kinds of equivalent surface roughness. We show that the accumulated wear volume after a single turn-on and turn-off of an ignition switch normally increases with increasing surface roughness, with a few exceptions.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.247-250
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• 2005

The need for improved fuel efficiency, weight reduction has motivated the automotive industry to focus on aluminum alloys as a replacement for steel-based alloy. To cope with the needs for high structural rigidity with low weight, it is forecasted that substantial amount of cast components will be replaced by tubular parts which are mainly manufactured by the extruded aluminum tubes. The extrusion process is utilized to produce tubes and hollow sections. Because there is no weld seam, the circumferential mechanical properties may be uniform and advantageous for hydroforming. However the possibility of the occurrence of a surface defect is very high, especially due to the temperature increase from forming at high pressure when it comes out of the bearing and the roughness of the bearing, which cause the surface defects such as the dies line and pick-up. And when forming a extruded aluminum tube, the free surface of the tube becomes rough with increasing plastic strain. This is well known as orange peel phenomena and has a great effect not only on the surface quality of a product but also on the forming limit. In an attempt to increase the forming limit of the tubular specimen, in the present paper, surface asperities generated during the hydroforming process are polished to eliminate the weak positions of the tube which lead to a localized necking. It is shown that the forming limit of the tube can be considerably improved by simple method of polishing the surface roughness during hydroforming. And also the extent of the crack propagation caused by dies lines generated during the extrusion process is evaluated according to the deformed shape of the tube.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.287-290
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• 2005

Once hot forgings for automotive parts such as wheel bearing flange to which cyclic asymmetric bending stress is continuously applied are produced, it is necessary to control their microstructure to obtain superior mechanical properties. It is however hard to control the microstructure uniformly because the strength is reduced as coarsening of ferrite grains. To investigate the microstructural alteration according to process variables during hot working, the variation of the ferrite grain size was studied by utilizing of the computer aided servo-hydraulic Gleeble tester which is hot deformation behavior reproduction equipment. In addition, the effect of the ferrite grain size of raw material on the austenite grain behavior of hot forgings was also examined. The rolling contact fatigue resistance of the induction hardened SAE 1055 steel was compared with the occasion of the same condition of SAE52100 bearing steel. As a result, it was confirmed that the ferrite grain sizes of the forgings depend on the heating temperature and cooling start temperature during hot forging and cooling processes. The induction hardened SAE1055 steel showed a superior rolling contact fatigue resistance to the induction hardened SAE52100 steel. The reason is that SAE1055 steel is freer from the material defect such as segregation than the comparative steel.

• 대한족부족관절학회지
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• 제25권4호
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• pp.185-189
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• 2021

An aneurysmal bone cyst (ABC) can occur in many parts of the human body, but a primary ABC of the talus is extremely rare. ABCs are benign, but aggressively growing tumors that usually occur in the first two decades of life. Patients mainly complain of pain, limited movement of the involved joint or a palpable mass. Pain may worsen suddenly because of pathological fractures. If not treated properly, ABC has a risk of local recurrence, followed by the destruction of the joint and a significant functional deficit. While the complete removal of the bone tumor is essential, it is also important to treat the resultant bone defect after removal. The talus has an important part to play in weight-bearing. Therefore, an appropriate bone graft is required for large bone defects that occur after an ABC removal from the talus. We report a primary ABC of the talus in a 28-year-old male that was treated by curettage and a bone pillar pattern graft of autologous tricortical iliac crest bone. The patient had an excellent functional outcome with early weight-bearing, and there was no recurrence at 16 months of follow-up.