• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.82-87
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• 2019

Recently, plastic materials have become more diversified, and the development of materials with excellent mechanical properties and plasticity has enabled wider application, miniaturization, and refinement of injection molded products. As a result, the utilization of these products in household goods, electronics, automotive parts, and aircraft parts is increasing in almost all industries. Injection molded parts are often used externally on finished commercial products. This means that the injection mold industry is very important to the value of these products. For this reason, the industry is performing research on the precision and efficiency of the injection molding process. In this study, we investigated the applicability of the core in core cooling method to the problem of product deformation due to temperature variation in existing injection mold designs. We also characterized the cooling performance of an injection mold when using this cooling method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.10
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• pp.68-74
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• 2019

In the case of a partition panel for a vehicle, it is used as a vehicle chassis component that serves to distinguish the indoor and outdoor spaces of a vehicle and is mounted on a backrest portion of the vehicle's back seat to ensure the convenience of passengers by connecting the floor and the side of the vehicle. Because it is a relatively large-sized plate material among automobile chassis parts except the moving parts and non-ferrous materials can be applied, it is considered as a part having a large light-weight effect. However, the partition panel is one of the vehicle parts that must satisfy the light-weight effect as well as various structural reliability, such as torsional rigidity, vibration, and impact characteristics, for securing the running stability of the vehicle when driving at the same time. So, In this study, the possibility of replacing the aluminum partition panel as CFRP(Carbon Fiber Reinforced Plastic) partition panel is evaluated through comparing the two partition panels by using the structural reliability(stiffness/strength analysis), vibration analysis, impact analysis.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.133-145
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• 2000

Plastic molding designers are frequently faced with optimizing multiple defects in injection molded parts. these defects are usually in conflict with each other, and thus a tradeoff needs to be made reach a final compromised solution. In this study, an automated injection molding design methodology has been developed to optimize multiple defects of injection molded parts. Two features of the proposed methodology are as follows: one is to apply the utility theory to transform the original multiple objective optimization problem into single objective optimization problem with utility as objective function, the other is an implementation of a direct search-based injection molding optimization procedure with automated consideration of process variation. The modified complex method is used as a general optimization tool in this research. The developed methodology was applied to an actual molding design and the results showed that the methodology was useful through the CAE simulation using a commercial injection molding software package. Applied to production, this study will be of immense value to industry in reducing the product development time and enhancing the product quality.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.9
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• pp.210-221
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• 2000

Plastic mold designers and frequently faced with optimizing multi-quality issues in injection molded parts. These issues are usually in conflict with each other and thus tradeoff needs to be made to reach a final compromised solution. in this study an automated injection molding design methodology has been developed to optimize multi-quality characteristics of injection molded parts. The features of the proposed methodology are as follows : first utility theory is applied to transform the original multi-objective problem into single-objective problem. Second is an implementation of a direct search-based injection molding optimization procedure with automated consideration of robustness against process variation. The modified complex method is used as a general optimization tool in this study. The developed methodology was applied to an actual mold design and the results showed that the methodology was useful through the CAE simulation using a commercial injection molding software package. Applied to production this study will be of immense value to companies in reducing the product development time and enhancing the product quality.

• Archives of Plastic Surgery
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• v.43 no.1
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• pp.59-65
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• 2016

Background In East Asia, the foot is the most common site of cutaneous melanoma. The purpose of this study was to investigate the differences between cutaneous melanoma of the foot and melanomas of other sites. Methods We studied 52 patients who underwent surgical treatment for cutaneous melanoma of the foot from September 2000 to January 2015. Through a retrospective review of their medical records, we collected data relating to their sex, age, histopathological subtype, Clark level, tumor thickness, lymph node involvement, stage, and survival rate, and we compared these parameters to those of 61 patients treated for melanoma of other sites. Moreover, we analyzed the surgical procedures, complications, and mortality rates associated with cutaneous melanoma on various parts of the foot. Results Melanoma of the foot differed from other melanomas only in the histopathological subtype. Other clinical features, including survival rate, did not differ significantly between the two groups heel was the most common site of melanoma of the foot (22 cases, 42.3%). The method of reconstruction varied depending on the region involved. Conclusions A comparison of melanoma of the foot to other melanomas showed that melanoma of the foot was associated with a significantly different distribution of histological subtypes. Consistent with previous findings, we found that the acral lentiginous subtype was the most common among melanomas of the foot. Furthermore, in contrast with previous studies, we did not find a worse prognosis or lower survival rate for melanoma of the foot in comparison with other melanomas.

• Archives of Plastic Surgery
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• v.37 no.3
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• pp.309-312
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• 2010

Purpose: An osteoma is one of the common benign tumors that penetrate the nasal portion, paranasal and frontal sinus. This tumor is mostly found by radiation test accidentally, however in rare cases; it can be found to be touched or with its symptoms as the tumor grows. We report this case since we found and healed the benign tumor which was affecting orbit and the both sides of fronal sinus. Methods: A 19 year old female patient visited to our hospital due to the mass on her forehead. The symptoms began 3 years ago but no special symptom was found except for touchable mass. She was diagnosed as the osteoma of superior orbital parts and both sides of frontal sinus using X-ray and CT scanning. The size of osteoma was $5{\times}2.5{\times}3.5\;cm$ and indicated the patterns penetrated to the right side of orbital region. The osteoma excision was conducted with coronal incision and wide area of defect part in frontal sinus and superior orbital part were reconstructed by cranial bone graft and resorbable fixation plates. Results: The patient recovered without any postoperative infections or complications and symptoms. Dysaesthesia was found on her frontal area but improved in 1 month after the surgery. Conclusion: The occurrences of osteoma in frontal sinus are rare and can be treated with conservative methods if there are no infections and symptoms. We report this case since we found the benign tumor, which was affecting orbit and the both sides of fronal sinus and healed it with coronal resectomy without any complications.

• Archives of Plastic Surgery
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• v.38 no.6
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• pp.829-835
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• 2011

Purpose: The two major concerns in skin grafting are poor color match in the recipient site and the donor site morbidity. And, glabrous skin on the palmar aspect of the hands and plantar aspect of the feet attributes define the skin on the palm and fingers sole as functionally and aesthetically different from skin on other parts of the body. When there is a glabrous skin defect, it should be replaced with similar skin to restore function and aesthetics. The palmar crease areas were used to minimize these problems. The purpose of this study is to present the precise surgical technique of the full thickness skin graft using distal palmar and midpalmar creases for aesthetic better outcome for hand injuries. Methods: From May 2006 to April 2010, 10 patients with 11 defects underwent glabrous full thickness skin grafting of finger defects. Causes included seven machinery injuries, two secondary burn reconstructions, and one knife injury. Donor sites included ten glabrous full thickness skin graft from the distal palmar crease and one from the midpalmar crease. Results: Follow-up ranged from 3 months to 24 months. All glabrous skin grafts demonstrated complete taking the recipient sites and no incidence of the complete or partial loss. The donor site healed without complications, and there were no incidences of significant hypopigmantation, hyperpigmentation, or hypertrophic scarring. Conclusion: The important aspects of this method involve immediate return of glabrous skin to the defect site and restoration of the recipient site's crease by simple primary closure from adjacent skin. The glabrous skin of the palm provides the best tissue match for the reconstruction of the hands, but only a limited amount of tissue is available for this purpose. Full thickness skin grafting using palmar crease of the defects is the ideal way of reconstructing glabrous skin to restore both function and aesthetics and minimize donor site morbidity.

• Archives of Plastic Surgery
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• v.35 no.5
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• pp.615-618
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• 2008

Purpose: Pyoderma gangrenosum is a rare cutaneous ulcerative disease. First described in 1930, the condition is characterized by progressive ulceration with deeply undermined purple-red edge. The lower extremities are most commonly affected but other parts of the skin and mucous membranes may also be involved. Although medical treatments with topical wound therapy are commonly used, surgical intervention is still controversial. In this paper, we report an atypical case of pyoderma gangrenosum which was characterized by extensive soft tissue breakdown. Methods: A 27-year-old male patient was referred to our institution with a $7{\times}8cm$ sized deeply undermined ulceration with pus-like discharge and fever. Incision and drainage was performed at another clinic 3 days prior to admission to our institution. After a thorough physical examination and the MRI review, a diagnosis of necrotizing faciitis was made. Accordingly, fasciotomy and debridement was performed. However, the wound enlarged progressively and the patient remained highly febrile for 9 days after the treatment. Septic screening did not reveal any occult infection. After a secondary review of the case, the initial diagnosis of necrotizing fasciitis was rejected and changed to pyoderma gangrenosum. With the use of dexamethasone intravenously, the wound improved dramatically and the fever was eliminated. Steroid mediation was tapered with duration of 1 month. The wound was stabilized and subsequently covered with split-thickness skin graft. Results: Split-thickness skin grafting with 1 : 1.5 mesh was successfully taken. Conclusion: Initial clinical features of pyoderma gangrenosum are very similar to that of necrotizing fasciitis. High fever and progressive ulceration with severe pain could invite earlier surgical approach. The advancing wound margins (the well defined violaceous, undermined border and necrotic ulcer base) and lack of isolation of pathogenic organism was used to make the correct diagnosis of pyoderma gangrenosum. We achieved a good result with proper medication and split-thickness skin graft.

• Archives of Plastic Surgery
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• v.40 no.3
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• pp.220-225
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• 2013

Background A recent advancement in microsurgery, the free flap is widely used in the reconstruction of the lower leg and foot. The simple and effective methods of local flaps, including transposition and advancement flaps, have been considered for patients with chronic debilitation who are unable to endure long surgical procedures or general anesthesia. However, the location and size of the wound may restrict the clinical application of a local flap. Under these circumstances, a sural flap can be an excellent alternative, rendering satisfying clinical outcomes in chronically debilitated patients. Methods Between 2008 and 2012, 39 patients underwent soft tissue defect treatment by sural artery flap as a final method. All of the patients had at least one chronic disease or more (diabetes, hypertension, vascular disease, etc.). Also, all of the patients had a history of chronic lower extremity ulceration, which revealed no response to several months of conservative treatment. Results The results of the 39 cases had a success rate of 100% with 39 complete recoveries. Nine cases suffered complications: partial necrosis (n=4), wound dehiscence without necrosis (n=3), hematoma (n=1), and infection (n=1). Conclusions The sural artery flap is not only useful for the lower leg but also for the heel, and other various parts. Furthermore, it is a relatively simple surgical technique for reconstructing the defect area for patients with various chronic conditions with a high surgical risk or contraindications to surgery.

• Archives of Plastic Surgery
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• v.35 no.4
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• pp.446-449
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• 2008

Purpose: Pilonidal sinus is a frequent disease that occurs mostly in hairy young men, defined as chronic inflammation and infection of the postsacral sinuses. Wide excision of the affected area is the treatment of choice. Many techniques have been described to cover the defect. However none appears to be the ideal procedure to prevent infection, recurrence, and delayed wound healing. We present the results of an alternative technique that we performed by using partial deepithelized gluteal transposition flap for reconstruction of the defect following wide excision. Methods: From October 2004 to September 2007, we performed the partial deepithelized gluteal transposition flap method on 6 patients. We modified the transposition flap techniques by deepithelialising the medial parts of the flap and burying them under the opposing edge of the flap. The results were compared with previous studies and evaluated regarding duration of surgery, size of defect, hospitalization periods, and complications. Results: All the flaps were healed well with no partial or complete loss of the flap. Hospitalization and immobilization periods were acceptably shortened. Recurrence was not seen. The aesthetic outcome was also satisfactory and all patients were satisfied with the results. Conclusion: The main advantage of our techniques is using healthy tissues to obliterate the dead space, to provide an extra-cushion, and to prevent deep dehiscence. We believe that the partial deepithelized gluteal transposition flap is a good alternative method for treatment of pilonidal sinus.