• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.58-64
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• 2003

A mechanical press joining was investigated in ender for joining A1-5052 sheets for automobile body weight reduction. Static tensile and fatigue tests were conducted using tensile-shear specimens for evaluation of fatigue strength of the joint. During Tox joining process for A1-5052 plates, using the current sheet thickness and punch diameter, the optimal applied punching force was found to be 32 kN under the current joining condition. For the static tensile-shear experiment results, the fracture mode is classified into interface fracture mode, in which the neck area fractured due to influence of neck thickness, and pull-out fracture mode due to influence of plastic deformation of the joining area. And, during fatigue tests for the A1-5052 tensile shear specimens, interface failure mode occurred in the region of low cycle. The fatigue endurance limit approached to 6 percents of the maximum applied load, considering fatigue lifetime of $2.5\times10^6$ cycles.

• Korean Journal of Head & Neck Oncology
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• v.17 no.2
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• pp.216-220
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• 2001

There are many approaches in surgery of posterior hypopharyngeal wall cancer according to location, extent, and invasion depth of primary cancer. And many reconstruction methods have been used in reconstruction of surgical defect remaining after wide resection of primary cancer. Posterior hypopharyngeal wall cancer is relatively rare, so its surgical experiences are fewer than those of pyriform sinus cancer and there have been few reports of surgical approaches and reconstruction methods of posterior hypopharyngeal wall cancer. Recently, we experienced a case of posterior hypopharyngeal wall cancer reconstructed with longus colli flap and skin graft after failure of radial forearm free flap in a 72-year -old man and report it with the review of the literatures.

• Korean Journal of Bronchoesophagology
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• v.17 no.1
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• pp.46-49
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• 2011

Background and Objectives Cervical necrotizing fasciitis is a fulminant disease associated with necrosis of connective tissue, spread along the fascial plane, and high mortality. We analyzed the clinical characteristics and treatment outcome of this rare fatal disease. Materials and Methods We retrospectively reviewed the medical records of 19 patients treated for cervical necrotizing fasciitis from January 1999 to January 2009. Mean age was 53.7 years. Results The most common predisposing illness was tonsillitis (36.8%), followed by odontogenic infection (15.7%). Diabetes mellitus was most common underlying disease. Liver cirrhosis and chronic renal failure were found in 2 patients each. All patients were treated with combination of parenteral antibiotics and wide surgical debridement by transcervical and/or thoracotomy approach. Multiple surgical debridements were performed in 7 patients. Tracheotomy was performed in most of the patients (88.8%). Period of total hospitalization and Intensive care unit was 23 days and 10.1 days. Two patients died of disease and overall survival rate was 89.4%. Conclusion Early surgical management and care in intensive care unit are essential for cervical necrotizing fasciitis. Possible complications such as respiratory failure, mediastinitis or sepsis should be carefully evaluated.

• Journal of Korean Foot and Ankle Society
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• v.14 no.1
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• pp.79-83
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• 2010

Purpose: To compare the clinical and radiological results between the anterior and posterior screw fixation for the treatment of talar neck fracture. Materials and Methods: Among 30 patients who received surgical treatment for talar neck fracture from 2001 to 2008. Twenty-seven patients with a follow-up period of more than 1 year were divided into two groups. Twelve patients were treated with anterior screw fixation and 15 patients with posterior approaches. We analyzed preoperative, postoperative and follow-up radiographs. Clinical results were evaluated by Hawkins criteria. Results: The posteriorly inserted screws were placed across the more central portion of the talar neck and perpendicular to the plane of fracture (p<0.05). There were no difference in clinical results, the duration of union, and complications including avascular necrosis between two groups. However, 2 patients complained of pain around the talonavicular joint in the anterior insertion group. Conclusion: Although the clinical results were good irrespective of insertion methods, the posterior approach of screw fixation for talar neck fractures allows for a better mechanical advantage than anterioly placed screws. This may allow early motion with a reduced risk of failure of fixation or of displacement of the fracture.

• Korean Journal of Head & Neck Oncology
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• v.15 no.1
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• pp.29-34
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• 1999

Objectives: This study was carried out to analyze the clinical profile and the results of treatment of a series of patients with extramedullary plasmacytoma(EMP) of the head and neck. Materials and Methods: The clinical features, treatment and survival of 14 patients with EMP seen at Yonsei Medical Center between 1970 and 1998 were carefully reviewed. Results: The median age was 48 years(range 15-75) and there was a male predominance(M:F 1.8:1). Nasal cavities and paranasal sinuses account for 50% of the primary sites and the most common symptom was airway obstruction(50%). Five patients(36%) showed evidence of adjacent bone destruction, one patient had lymph node involvement and one patient had an IgG monoclonal gammopathy at the time of diagnosis. All 5 patients treated with radiotherapy alone achieved local control. Of 5 patients treated with surgery alone, 2 patients(40%) had local failure. Of 3 patient treated with a combination of surgery and radiotherapy, one patient had local recurrence. A total of7 patients(54%) had local, distant or nodal relapses after primary treatment. Six of them received salvage treatment. With salvage treatment of surgery and/or radiotherapy, local control was achieved in 4 of 6 patients. Conversion to multiple myeloma was seen in one patient. Conclusion: Radiotherapy should be recommanded as treatment of choice for EMP of the head and neck. Surgery should be reserved for radioresistant or recurrent tumors, but tumors that are localized and can be removed relatively easily with little morbidity may be treated by primary surgery.

• Korean Journal of Bronchoesophagology
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• v.10 no.1 s.19
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• pp.41-45
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• 2004

Tracheostomy and endotracheal intubation are often performed in patients with acute and chronic respiratory failure. Recently, the incidence of iatrogenic tracheal stenosis has increased. Tracheal resection and end-to-end anastomosis would be one of the most physiologic treatment options for severe tracheal stenosis. Also, this treatment can be applied to the management of trachea invaded by thyroid cancer and tracheal neoplasm. The authors aimed to analyze the outcomes of end-to-end anastomosis of trachea following segmental resection in tracheal stenosis and tracheal invasion of cancer that we have recently experienced. Materials and methods Authors retrospectively studied 19 cases treated by tracheal resection with end-to-end anastomosis between Feburuary 1996 and January 2003. 12 patients had tracheal stenosis, 6 patients had tracheal invasion by thryroid cancer and 1 patient had tracheal cancer. We analyzed the direct causes of tracheal stenosis, preoperative vocal cord function, operation technique, early and delayed postoperative complications, and the outcome of end-to-end anastomois. Result Decannulation without significant aspiration was achieved in 16 cases($89.5\%$). A 27 year-old man could not be decannulated because of restenosis. A 62 year-old woman could not be decannulated because of bilateral vocal cord palsy. Conclusion End-to-end anastomosis is a safe and effective surgical method for tracheal stenosis. Case selection for end-to-end anastomosis and preservation of recurrent laryngeal nerve during operation is very important.

• Archives of Craniofacial Surgery
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• v.22 no.5
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• pp.247-253
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• 2021

Background: Radiation therapy (RT) is frequently used for supportive treatment and management of advanced head and neck cancers. This study performed a retrospective review of the treatment methods that were used for intractable draining fistulas in seven patients who had received RT for head and neck cancers. Treatment methods used for two of the seven patients are presented in detail. Methods: From 2009 to 2020, seven patients underwent reconstructive surgery for intractable fistulas which occurred after RT for head and neck cancers. Patient characteristics, medical history, treatment method, and treatment outcome were reviewed for each case. The type of surgery performed, failure rate, and treatment period were also analyzed. Results: In this study, a total of seven patients received additional management for radiation-induced fistulas. Patients underwent a mean of 3.3±1.4 surgeries (maximum: six surgeries) to resolve their fistulas. The mean time interval from the first surgery to the last surgery for the patients to achieve resolution of the fistula was 8.7 months. Loco-regional flaps have performed an average of 1.9±1.5 times. However, all loco-regional flaps failed. Instead, the patients' intractable fistulas were resolved with the use of distant flaps or free tissue transfers. Conclusion: Fistulas that develop after head and neck cancer treatment following RT are difficult to treat with simple loco-regional flap procedures. Therefore, more aggressive treatment techniques, such as distant flap or free tissue transfer, may be needed to shorten patients' treatment periods and avoid unnecessary surgeries.

• Archives of Plastic Surgery
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• v.48 no.1
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• pp.49-54
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• 2021

Background Reconstruction after removal of a malignant tumor in the head and neck region is crucial for restoring tissue integrity, function, and aesthetics. We retrospectively analyzed patients who underwent intraoral reconstruction surgery using radial forearm free flaps (RFFF) and anterolateral thigh free flaps (ALT) at a single institution to provide more information supporting the choice of a reconstruction method after removal of head and neck cancer. Methods The charts of 708 patients who underwent head and neck reconstruction between 1998 and 2018 at the Department of Plastic and Reconstructive Surgery at our institution were retrospectively reviewed. Patients' age, sex, and history of radiation therapy, diabetes mellitus, and smoking were retrieved. The primary cancer site, types of defects, and complications were investigated. Results Overall, 473 and 95 patients underwent reconstruction surgery with RFFF and ALT, respectively. RFFF was more often used in patients with cancers of the pharynx, larynx, esophagus, or tonsil, while ALT was more frequently used in patients with cancers of the mouth floor with tonsil or tongue involvement. The proportion of patients undergoing ALT increased gradually. Flap failure and donor site morbidities did not show significant differences between the two groups. Conclusions RFFF and ALT flaps resulted in similar outcomes in terms of flap survival and donor site morbidity. ALT can be an option for head and neck reconstruction surgery in patients with large and complex defects or for young patients who want to hide their donor site scars.

• Journal of Audiology & Otology
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• v.23 no.2
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• pp.112-117
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• 2019

Background and Objectives: The purpose of this study was to evaluate the efficacy of revision cochlear implant (CI) surgery for better speech comprehension targeting patients with low satisfaction after first CI surgery. Subjects and Methods: Eight patients who could not upgrade speech processors because of an too early CI model and who wanted to change the whole system were included. After revision CI surgery, we compared speech comprehension before and after revision CI surgery. Categoies of Auditory Performance (CAP) score, vowel and consonant confusion test, Ling 6 sounds, word and sentence identification test were done. Results: The interval between surgeries ranged from eight years to 19 years. Same manufacturer's latest product was used for revision surgery in six cases of eight cases. Full insertion of electrode was possible in most of cases (seven of eight). CAP score (p-value=0.01), vowel confusion test (p-value=0.041), one syllable word identification test (p-value=0.026), two syllable identification test (p-value=0.028), sentence identification test (p-value=0.028) had significant improvement. Consonant confusion test (p-value=0.063), Ling 6 sound test (p-value=0.066) had improvement but it is not significant. Conclusions: Although there are some limitations of our study design, we could identify the effect of revision (upgrade) CI surgery indirectly. So we concluded that if patient complain low functional gain or low satisfaction after first CI surgery, revision (device upgrade) CI surgery is meaningful even if there is no device failure.

• Korean Journal of Audiology
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• v.23 no.2
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• pp.112-117
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• 2019

Background and Objectives: The purpose of this study was to evaluate the efficacy of revision cochlear implant (CI) surgery for better speech comprehension targeting patients with low satisfaction after first CI surgery. Subjects and Methods: Eight patients who could not upgrade speech processors because of an too early CI model and who wanted to change the whole system were included. After revision CI surgery, we compared speech comprehension before and after revision CI surgery. Categoies of Auditory Performance (CAP) score, vowel and consonant confusion test, Ling 6 sounds, word and sentence identification test were done. Results: The interval between surgeries ranged from eight years to 19 years. Same manufacturer's latest product was used for revision surgery in six cases of eight cases. Full insertion of electrode was possible in most of cases (seven of eight). CAP score (p-value=0.01), vowel confusion test (p-value=0.041), one syllable word identification test (p-value=0.026), two syllable identification test (p-value=0.028), sentence identification test (p-value=0.028) had significant improvement. Consonant confusion test (p-value=0.063), Ling 6 sound test (p-value=0.066) had improvement but it is not significant. Conclusions: Although there are some limitations of our study design, we could identify the effect of revision (upgrade) CI surgery indirectly. So we concluded that if patient complain low functional gain or low satisfaction after first CI surgery, revision (device upgrade) CI surgery is meaningful even if there is no device failure.