• Tribology and Lubricants
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• v.16 no.5
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• pp.395-402
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• 2000

The effect of particulate contamination on friction and wear between a negative-pressure picoslider and a laser-textured disk was studied. Particles of different concentrations, materials and sizes were injected to the head-disk interface (HDI), consisting of disks with various textures, at the same speed. In a contaminated environment, durability of head-disk interface gradually decreased as the particle concentration increased. Large particles caused HDI failure early and resulted in an extensive damage to the slider and disk surfaces. Hard particles also caused HDI failure earlier and damages more extensive than soft ones. Based on the test results, mechanisms of HDI failure with picoslider were presented.

• Korean Journal of Head & Neck Oncology
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• v.31 no.2
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• pp.43-45
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• 2015

Angiomyolipoma is a benign tumor that is composed of adipose tissue, blood vessels and smooth muscle. The kidney is the most common location of this tumor. In the larynx, angiomyolipoma has been rarely reported in the literature. We describe the patient of 64-year-old male with an angiomyolipoma arising from the vallecula. The tumor had a smooth surface with numerous small vessels and showed heterogeneous contrast enhancement on CT. The tumor was not adhesive to surrounding tissue and was completely removed by laryngomicrosurgery with $CO_2$ laser. Microscopically, the tumor is composed of mature adipose tissue, tortuous thick walled blood vessels and thick bundles of smooth muscle.

• Korean Journal of Head & Neck Oncology
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• v.33 no.2
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• pp.95-99
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• 2017

Schwannoma, also known as a neurilemmomas or neurinomas, is benign peripheral nerve sheath tumors arising from the Schwann cells. About 25~45 % of all schwannomas are found in the head and neck region, and the majority are found in the parapharyngeal space. Schwannoma of the larynx is very rare with an incidence of 0.1~1.5% in all benign laryngeal tumors. Recently, we experienced a case of a pedunculated schwannoma arising from the left aryepiglottic fold in a 80-year-old patient. The tumor was completely excised under direct laryngoscopy with the use of a $CO_2$ laser and subsequently confirmed as schwannoma. So, we report this case with a review of the literatures.

• Korean Journal of Head & Neck Oncology
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• v.32 no.1
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• pp.49-52
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• 2016

The lobular capillary hemangioma (LCH) was previously known to pyogenic granuloma and is benign vascular lesion which grows rapidly on skin and mucosa. It arises from whole body, but oral and nasal cavities are most predilection sites in the head and neck area. The laryngeal LCH looks like a granulomatous lesion of posterior glottis and its common etiology are tracheal intubation and laryngopharyngeal reflux disease etc. The LCH in larynx can cause blood tinged sputum and lump sense. The lesions refractory to medical therapy or causing dyspnea may require surgical excision. A 74-year-old man who presented gradually aggravated dyspnea, lump sensation and hoarseness of one month came to our hospital. The stroboscopic examination revealed large well-margined glottic mass. It was excised with $CO_2$ laser and finally diagnosed as LCH. We present a rare unique case of glottic LCH with a review of literatures.

• Korean Journal of Head & Neck Oncology
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• v.34 no.2
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• pp.77-80
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• 2018

Subglottic cysts have been reported as a relatively rare problem of pediatrics who have a history of premature birth and period of intubation. They may cause significant upper airway obstruction and many cases require tracheostomy to airway management. Endoscopic marsupialization by microinstruments or laser has been standard primary treatment but a high recurrence rate has been reported. A 19-month-old child presented with stridor who has history of ventilation via an endotracheal intubation in the newborn period for 7 days. Radiologic examinations were performed for aggravated dyspnea symptom and subglottic cystic mass was found, then it was marsupialized at operation room and tracheostomy was done at the same time. After decannulation of tracheostomy tube, there is no recurrence of cyst nor upper airway obstruction for 29 months. We report this case with a review of literature.

• Korean Journal of Head & Neck Oncology
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• v.39 no.1
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• pp.33-36
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• 2023

Malignant lymphoma rarely occurs in the larynx and hypopharynx. Few cases of malignant lymphoma in the larynx were reported in Korea. However, malignant lymphoma in the hypopharynx had been not reported in Korea. A 68-year-old woman came to the outpatient clinic with a foreign body sensation in her throat. A round, smooth margin, bright pink-colored mass was confirmed by the laryngoscopy. The patient took neck computer tomography. A small bulging of mucosa was observed, but there was no peripheral infiltration or abnormally enlarged lymph nodes. We did excision using CO2 LASER. She was finally diagnosed with mucosa-associated lymphoid tissue lymphoma (MALT lymphoma). After diagnosis, several image studies confirmed that there was no metastatic lesion. She got only radiotherapy after that and kept a complete response state for over 2 years.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.26 no.2
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• pp.137-140
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• 2015

Neurofibroma is characterized as a benign, slow growing neoplasm, originating from Schwann cells or fibroblast in peripheral nerve sheaths. It may appear as a solitary tumor or have multiple localizations in von Recklinghausen disease. They are commonly found in the gastrointestinal tract and laryngeal neurofibromas are extremely rare, accounting for only 0.03 to 0.1% of benign tumors of the larynx. The aryepiglottic fold and arytenoid are the common site of occurrence for laryngeal neurofibroma, because the branch of the superior laryngeal nerve is involved. We present a case of solitary plexiform neurofibroma arising from the laryngeal surface of epiglottis in a 55-year old female who found the lesion incidentally. We removed the tumor completely by transoral laser surgery and no recurrence was found after 7 months. The case of solitary neurofibroma arising from laryngeal surface of epiglottis has not been reported in Korea. We report this case regarding the diagnosis and treatment with review of literatures.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.849-855
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• 2017

The development of a staged combustion cycle engine with higher perfomance is essential to provide higher transport capability of space launch vehicles. The combustor head of engine has a cone-shaped head and its manifold of combustor has a very complicated structure. The head and manifold have been manufactured by casting or machining methode. Metal 3D printing technologies are recently known as one of promising methods to improve manufacturing process for them because they are possible to over come limitations of the two methods. In this paper, a selective laser sintering method is used to make test materials and their physical properties are studying by changing its operation parameters to establish the better processing conditions. It is found that the 3D printing method is acceptable to manufacturing the head or manifold of combustor for staged combustion cycle engine.

• Korean Journal of Bronchoesophagology
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• v.16 no.2
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• pp.145-148
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• 2010

Background: Laryngeal papillomatosis, which is cased by human papillomavirus, is the most common benign neoplasm of the larynx. However, the prognosis of this disease remains really unpredictable. The aim of this paper is to determine whether any clinical features at the time of diagnosis could predict its course. Material and Method: Eighty-six patients treated at our institution during the last 20 years were analyzed retrospectively. All patients had microsurgery under general anesthesia. All patients' follow-up period was more than 1 year. We divided the patients into 1) Juvenile versus adult group based on their age 20, 2) single surgical method with laser versus dual surgical method with laser and microdebrider group, and 3) single subsite versus multiple subsites group. And we compared the therapeutic outcome. Results: The recurrence rate was 100% (15 patients) in the JP group and 56% (40 patients) in the AP group. Juvenile versus adult group was the only independent prognostic factor by univariate, and multivariate analysis. Microdebrider resection technique and multiple subsites were not associated with treatment result. Time period from the first surgery to recurrence detection was different statistically only for the age group. The number of surgery in the JP group ranged from 1 to 31 (mean 8.8). In the AP group the number of surgery ranged from 1 to 25 (mean 3.7). It was statistically different. Conclusion: Prognosis for the laryngeal papillomatosis remains unpredictable. Only patients' age was the only independent prognostic factor.

• Archives of Craniofacial Surgery
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• v.20 no.2
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• pp.84-88
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• 2019

Background: Epidermal cysts are benign, slow growing cysts that often develop on the head, neck, chest, and back of adults. The most common method of surgical excision involves the use of a scalpel and often leaves a scar proportional to the size of the cyst. Therefore, minimally invasive techniques are required. Among these techniques, the $CO_2$ laser-based technique is minimally invasive and has lower complication rate, shorter recovery times, and lesser scarring. This paper aimed to compare the results and postoperative complications associated with a $CO_2$ laser-based excision against conventional surgical excision for epidermal cysts. Methods: We surveyed 120 patients, aged 16 to 65 years, with epidermal cysts on the face measuring 0.5 to 2.2 cm in diameter. Twelve months later, we compared the scar length, recurrence rate, patient satisfaction, and complications between patients treated with $CO_2$ laser excision versus surgical excision. Results: The mean scar length (12 months postoperative) after $CO_2$ laser excision was $0.30{\pm}0.15cm$, and that following surgical excision was $1.23{\pm}0.43cm$ (p= 0.001). The procedure time (time from incision after local anesthesia to the end of repair) was $16.15{\pm}5.96minutes$ for $CO_2$ laser excision versus $22.38{\pm}6.05minutes$ for surgical excision (p= 0.001). The recurrence rates in the surgical excision group and $CO_2$ laser excision group were 3.3% and 8.3%, respectively; this difference was not statistically significant (p= 0.648). Conclusion: The cosmetic outcome of $CO_2$ laser excision is excellent. For epidermal cysts measuring 2.2 cm or smaller, $CO_2$ laser excision is recommended, especially when aesthetic outcome is considered important.