• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.123-124
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• 2011

• Archives of Reconstructive Microsurgery
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• v.18 no.1
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• pp.23-26
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• 2009

Purpose: Artificial dura maters are commonly used in cranioplasty, but sometimes they can result in serious postoperative infection. Once complications such as epidural abscess or chronic draining ulcer arise, they are very difficult to treat. In this case, reclosure of dura defect using artificial dura mater may give rise to recurrence of infection. We experienced a case of intractable epidural abscess caused by use of artificial dura. To avoid repeated infection, we decided to use autologous tissue for the coverage of dura and soft tissue defect. Therefore, autologous tensor fascia lata graft and anterolateral thigh free flap were harvested at the same donor site incision to cover composite defect on the scalp and dura mater. Methods: A 13 year old male patient, who underwent the decompression cranioplasty and duroplasty, suffered from the intractable infection lesion. Twice, the epidural abscess was removed, both times the infection recurred. And eventually dura mater was exposed through the infected open wound. Nine months after dura exposed, infected aritificial dura mater was removed and extensive debridement was performed. Through a surgical incision on donor thigh, first, tensor fascia lata graft was harvested in process of the anterolateral thigh flap elevation. After the fascia lata graft was fixed over the dural defect, the anterolateral thigh flap was used to fill the dead space as well as the scalp defect. Results: Postoperatively, no recurrent infection and cerebrospinal fluid leakage are observed for a year. After the surgery, on the first and second day, venous congestion of the flap was observed, this problem was solved by thrombectomy and vein reanastomosis. And partial necrosis of flap occurred, but completely healed as conservative treatment for two weeks. Conclusion: Using the autologous tensor fascia lata graft and anterolateral thigh flap, we could obtain satisfactory results as treatment for the intractable infection lesion after duroplasty. Autologous tensor fascia lata in conjunction with anterolateral thigh flap is useful method for covering composite defect of scalp and dura mater.

• Journal of the Korean Society for Heat Treatment
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• v.28 no.6
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• pp.315-321
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• 2015

Friction stir processing (FSP) was applied to fabricate AZ31/CNT (Carbon Nano Tube) surface composite for improvement of surface hardness of AZ31 Mg-based alloy. The effects of traverse speed of rotating tool and volume fraction of CNT (i.e., groove depth of 3 mm and 4 mm) on the soundness and hardness of the composite layer were investigated. Multi-walled CNTs were fully filled in a machined groove and stirring tool was rotated at the speed of 1400 rpm. Only under the tool traverse speed of 25 mm/min for the specimen with a groove depth of 3 mm, surface composite layer with no defect was successfully produced. Increased hardness of about 35% was observed in the composite layer.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.4
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• pp.30-37
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• 2015

iFLASH System is new structural floor system which consists of sandwich panels filled with nano-composite. The nano-composite has low specific gravity and high bonding strength with steel plates. The bonding strength is one of important factors for structural performance of iFLASH System and it can further be improved by surface preparation such as blast metal cleaning. However, using none blast steel plates is recommended since surface preparation generates additional fabrication time and cost. In this study, a bonding strength test and bending experiment were conducted to check feasibility of applying none blast steel plates to iFLASH System. Moreover, stress in bonding plane between steel plates and nano-composite was analytically evaluated by finite element method. Consequently, flexural capacity of the specimen was 11% higher than theoretically calibrated value and its flexural behavior was structurally efficient without defect of bonding.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.3
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• pp.246-252
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• 2004

Electronic speckle pattern interferometry (ESPI) for quantitative evaluation of delaminations inside of a composite material plate is described. Delaminations caused by the impact on composite materials are difficult to detect visual inspection and ultrasonic testing due to non-homeogenous structure. This paper proposes the quantitative evaluation technique of the defects made in the composite plates by impact load. Artificial defects are introduced inside of the composite plate for the development of a reliable ESPI inspection technique. Real defects produced by impact tester are inspected and compared with the results of visual inspection which shows a good agreement within 5% error.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.2
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• pp.130-137
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• 2016

Non-destructive testing methods for composite materials (e.g., carbon fiber-reinforced and glass fiber-reinforced plastic) have been widely used to detect damage in the overall industry. This study detects defects using optical infrared thermography. The transient heat transport in a solid body is characterized by two dynamic quantities, namely, thermal diffusivity and thermal effusivity. The first quantity describes the speed with thermal energy diffuses through a material, whereas the second one represents a type of thermal inertia. The defect detection rate is increased by utilizing a lock-in method and performing a comparison of the defect detection rates. The comparison is conducted by dividing the irradiation method into reflection and transmission methods and the irradiation time into 50 mHz and 100 mHz. The experimental results show that detecting defects at 50 mHz is easy using the transmission method. This result implies that low-frequency thermal waves penetrate a material deeper than the high-frequency waves.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.1
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• pp.27-32
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• 2013

According to the composition of LTCC material, though it was thought that bulk defect which was made in forming process effects on the densification during the sintering, it was not reported systemically. In this study, we evaluated crystal structure, 3 point bending strength, hardness and microstructure of the samples by uniaxial pressing and tape casting using the commercial powders of the crystallizing glass and the glass/ceramic composite. In the case of glass/ceramic composite, Viox-001 powder with residual glass in the sintering, 3 point bending strength was similar regardless of forming process due to fill the bulk defect by residual glass. In the case of crystallizing glass, MLS-22, because glass phase was small in the sintering, glass did not fill the pore in the sample by uniaxial pressing process, therefore, the 3 point bending strength of it was 167 MPa. However, the 3 point bending strength of the sample by tape casting was 352 MPa and much higher. Meanwhile, crystal structure and hardness were similar regardless of forming process.

• Archives of Plastic Surgery
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• v.32 no.2
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• pp.199-204
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• 2005

The nose is the most prominent area of the face, therefore susceptible to trauma and skin cancer. When small sized defect is in nasal tip, it results in disturbance of the facial harmony even if replantation, composite graft, skin graft or median forehead flap has been used for the reconstruction. So it is needed that the best method reconstruction is performed according to the degree of defect or deformity. And at the same time the physiology and anatomy of nose were clarified and its aesthetic subunits were employed. How can we cover the about 3 cm sized nasal defect in nasal tip with cartilage exposure? At first, we can think forehead island flap is most appropriate. We performed 7 cases of the forehead island flap for reconstruction of the defect in nasal tip(4 cases: cancer, 3 cases: trauma) from March, 2001 to August, 2004. This result was satisfactory in the point of texture, color, donor scar, and there were no complication such as wound disruption, infection, flap atrophy, and hematoma. The advantages of forehead island flap are: 1) No injury of deep vessel and nerve, 2) control of shape and volume, 3) Short operation time, 4) primary closure of donor site, 5) one stage operation. Also, forehead island flap can cover the defect in nose where skin graft and local flap can not cover. But, operator always must take care for flap congestion and donor site scar. We thought forehead island flap is one of the best option of reconstruction of nasal tip defect.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.451-457
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• 2011

Purpose: As a central feature of the face, the nose has considerable significance in appearance and expression. Reconstruction of full thickness defects of the nasal ala has always been a challenge because of the 3-dimensional structure. For reconstruction of post burn defects of ala, skin graft, local or pedicled flap and composite graft are optionally available. We have reconstructed the ala defects using adiposocutaneous graft and observed the outcome. Methods: From March 2003 to December 2010, 19 cases in 11 patients with scar contracture and defect on ala portion were performed operation using adiposocutaneous graft. As a donor site, we used the inguinal crease and posterior auricular area and the donor site was primarily closed. We made incision through the superior rim of ala and released fully. A graft is applied to recipient site with larger size than recipient volume. Results: The mean age of the patient was 38.6 years (16~51), males are seven patients and females are four patients. The operation was performed bilaterally in 5 patients and unilaterally in 6 patients. Composite grafts were harvested from inguinal area in 13 cases and posterior auricular area in 6 cases. In one case, we did 4 times of operation to get enough volume. All the grafts were well taken. The mean size of the graft was 3.63 $cm^2$. Conclusion: For reconstruction of post burn defects of ala, it's not easy to use local flap or pedicled flap because of hardness and fibrosis of surrounding tissue. So, we choose adiposocutaneous graft for ala deformity reconstruction, got satisfactory outcome in color matching and texture.

• Transactions of Materials Processing
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• v.12 no.2
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• pp.102-109
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• 2003

In the manufacturing process of metal matrix composites parts, thixoforging is one of the most effective forming processes. The major purpose of the current study is to provide the proper conditions such as the die shape, the forging velocity, the forging time, the forging pressure and reinforcement injection velocity and pressure on various defects in thixoforged cylinder liner, filling tests were performed by MAGMA S/W. In order to evaluate the effectiveness of the calculated conditions which is given by computer aided engineering, A357, A380 and SiC$_{p}$/A380 cylind~5$mu extrm{m}$r liner were fabricated under the calculated conditions. SiC$_{p}$/A380 composite billets were fabricated by both the mechanical stirring and electrical magnetic stirring process. Incase fo SiC$_{p}$/A380 composite cylinder liner, reinforcement distribution and effect of reinforcement(SiC$_{p}$) content(10~20 vol. %)and size(5.5~14${\mu}{\textrm}{m}$) on the mechanical properties were investigatedstigated.