• 대한기계학회논문집
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• 제13권4호
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• pp.764-770
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• 1989

This paper analyze the steady state performance of a self-acting air lubricated slider bearing in hard disk/head system. Modified Reynolds' equation is derived from the steady state compressible Navier-Stokes equation, under slip-flow conditions. Finite difference technique and numerical procedure are described by using Newton-Raphson iteration method to slove the non-linear equations. These techniques are applied to conventional slider bearings and the effects of molecular mean free path(MMFP) for a recording surface of hard disk are shown. The calculation procedure developed here, wide applicabilities in practical head design procedures, and converges rapidly.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제40권
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• pp.25.1-25.4
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• 2018

Background: Some of head and neck cancer patients are in compromised general condition after ablation surgery and chemoradiation therapy, which makes secondary free tissue transfer quite challenging. Elderly cancer patients also have some risk for microvascular surgery with lengthened general anesthesia. In those cases, the pedicled flap vascularized by supraclavicular artery could be considered as an alternative to free flap. Despite several authors have demonstrated the clinical reliability of supraclavicular artery island flap (SCAIF), to date, SCAIF has not been widely used among reconstructive surgeon. In this article, we clarified vascular flow pattern and introduce simple surgical technique of SCAIF with a literature review. Case presentation: Three patients who had underwent previous neck surgery and adjuvant therapy received maxillofacial reconstruction using SCAIF. It required only a few landmarks, flap harvesting was carried out, and the elapsed time gradually decreased to 15 min with experiences. There were no remarkable morbidities in both donor and recipient sites. Conclusion: SCAIF exhibited minimal anatomic variations and short learning curve of surgical techniques, which might be valuable reconstruction modality for beginning surgeon. And it can be beneficial option for the patients with vessel-depleted neck, medically compromised status for lengthened general anesthesia and failed free tissue transfer.

• 대한두경부종양학회지
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• 제1권1호
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• pp.63-74
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• 1985

Although regional and myocutaneous flaps are still the standard in head and neck reconstruction. The capacity to transfer distant tissues by microsurgical technique expands the reconstructive surgeon's ability to restore severe deformities of the head and neck. From 1981 to 1985, thirteen patients with extensive defects of the head and neck after extirpative surgery of tumor have been reconstructed utilizing the technique of microsurgical composite tissue transplantation. In this series of patients, six presented with reconstructions in the different region of the head and neck with review of literatures. The results of case analysis are summarized as follows: 1) Transplantation was successful in twelve among thirteen patients (92%). 2) Seven patients presented with malignancy and six with benign tumor. 3) Frequent sites of reconstruction were face and mandible. 4) Fourteen free composite tissue transplantations for reconstruction of thirteen patients were obtained six different tissue compositions from eight different donor sites. 5) The recipient artery and vein was most often superficial temporal or facial vessels. 6) The average time of operation was ten hours.

• 대한두경부종양학회:학술대회논문집
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• 대한두경부종양학회 2001년도 제18차 학술대회
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• pp.276-276
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• 2001

• 대한두경부종양학회지
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• 제16권1호
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• pp.26-32
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• 2000

Background and Objectives: Various flaps are using for reconstruction of hypopharyngeal and esophageal defect. However, complication and indication of each flap are not fully analyzed. Patient and Methods: Records of 52 hypopharyngeal cancer patients who had surgical treatment and 13 other head and neck cancer patients who underwent hypopharyngeal and/or esophageal reconstruction with flap were retrospectively analyzed. Eighty three percent(54 cases) of patients needed reconstruction other than primary pharyngeal closure. Five split thickness skin graft, 1 pectoralis major myocutaneous flap, 20 forearm free flap, 13 jejunal free flap, 15 gastric pull up were used. Result: Flap failure was noted in 2 cases who had subsequent gastric transposition. Wound dehiscence and fistula were most common problem of forearm free flap. Most fistulas were developed in patients with conduit type reconstruction of forearm flap while there wasn't any fistula in patient with patch type reconstruction. Stenosis of lower anastomosis was the frequent problem of jejunal transfer. Gastric pull-up has frequent com-plication of stomal stenosis. All but three patients had reached oral feeding postoperatively. Conclusion: Based on this study, forearm flap is effective in partial hypopharyngeal defect while jejunum is the choice for circumferential defect. Gastric pull-up is for combined esophageal defect.

• 대한두경부종양학회지
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• 제11권1호
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• pp.47-55
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• 1995

A large lateral facial defects especially a through and through defect of the cheek remains as challenging field of reconstruction for the head and neck surgeons. Closure of these wounds is technically troublesome due to the magnitude and location of the soft tissue and skin defect, functional and aesthetic consideration. optimal cancer surveillance, and desire for good nourishment. Most traditional methods dealing with these defects, including split-thickness skin graft, local and regional flaps as well as musculocutaneous flaps have their limitations. We applied four different methods for these reconstruction in four cases. We utilized temporal muscle flap, forearm free flap and secondary healing for repair of mucosal defects, and medial base cervicopectoral flap, pectoralis major myocutaneous flap and cervicofacial flap for the reconstruction of external skin defects. In one case, both sides were reconstructed with single forearm free flap. In our experiences, secondary healing could be one of the useful method for mucosal repair in the defect between upper and lower gingivobuccal sulcus. However, forearm free flap was thought to be more ideal for the cases with mandibulectomy. For the external repair, the regional skin flap was considered to be superior to pectoralis major myocutaneous flap or forearm free flap especially on color matching.

• 한국수소및신에너지학회논문집
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• 제19권3호
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• pp.182-188
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• 2008

In order to improve scavenging performance of free piston hydrogen fueled engine, this study estimate compatibility of uni-flow scavenging. The scavenging flow characteristics in the cylinder is investigated by flow visualization and PIV method. Consequently it has been found that the scavenging performance decreased with abnormal expansion of piston and delay of the exhaust valve opening timing. And the scavenging performance of exhaust valve located center in cylinder head is better than that of exhaust valve located side in cylinder head.

• 한국초전도ㆍ저온공학회논문지
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• 제15권4호
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• pp.59-62
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• 2013

The conductive link is used as a cooling medium between a cryocooler and magnet in a cryogen-free superconducting magnet system. The low temperature superconducting (LTS) magnet has one solenoidal configuration with a metal former which has a 52 mm room temperature bore. The superconducting coil is installed in the cryostat maintaining high vacuum and cooled by a two-stage cryocooler. In order to maintain the operating temperature of magnet at the designed level, the cold head temperature of the cryocooler must be lower so that heat can be removed from the superconducting coil. Also, temperature difference is occurred between the magnet and cryocooler and its magnitude is dependent upon the contact resistance at the interfacial surface between metals in the conductive link. In the paper, the performance of the LTS magnet is investigated with respect to the conductive link between the magnet former and the cold head of the cryocooler. The effects of the contact pressure and interfacial materials on the temperature distribution along the conductive link are also presented.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제22권1호
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• pp.98-104
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• 2000

Expansion in the scope and technique of head and neck tumor resection during the past two decades has paralleled precise tumor localization with advanced radiographic imaging and the availability of microvascular free tissue transfer. Especially, the defect reconstruction utilizing free flap results in improvement of patient survival due to decrease of local recurrence by wide resection of cancer. The rectus abdominis free flap has been used widely in reconstruction of the breast and extremities. However, the report of cases on its applications in the head and neck, based on the deep inferior epigastric artery and vein, is rare. This flap is one of the most versatile soft-tissue flaps. The deep inferior epigastric artery and vein are long and large-diameter vessels that are ideal for microvascular anastomosis. The skin area that can be transferred is probably the largest of all flaps presently in use. The versatility of the donor site is due to the ability to transfer large areas of skin with various thickness and amounts of underlying muscle. This article is to report reconstruction of midface defects utilizing the rectus abdominis free flap in 2 patients with maxillary squamous cell carcinoma and discuss briefly considerations in flap design and orbital exenteration, and healing of irradiated recipient site by hyperbaric oxygen therapy with literature review.

• 대한두경부종양학회지
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• 제26권2호
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• pp.212-215
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• 2010

Objectives：There are various reports for incidence and risk factors of hypothyroidism after hemithyroidectomy for benign thyroid disease. The reported incidence rate varies from 5.0 to 41.9%. Moreover, there are few reports about this in Korea. So, our objective is to identify the incidence and possible factors contributing to hypothyroidism after hemithyroidectomy in Korea. Subjectives and Methods：We reviewed medical records of patients who underwent hemithyroidectomy between 1999 and 2007 years. We enrolled 80 patients. The incidence of postoperative hypothyroidism was based on thyrotropin values and clinical symptoms. And all patients were evaluated for age, gender, serum thyrotropin(TSH) levels, serum free T4, weight of resected thyroid tissue and associated thyroiditis. Results：Nine of 80 patients(11.3%) became biochemically hypothyroid postoperatively. Six of 9 hypothyroid patients were diagnosed within 2 months of operation. The mean preoperative TSH level was $2.12{\pm}0.96mIU/L$ in hypothyroid and significantly different from $1.33{\pm}0.77mIU/L$ in euthyroid patients(p<0.05). There were no significant differences in age, gender, weight of resected thyroid tissue, preoperative free T4 and associated thyroiditis. Conclusion：A minority of patients became hypothyroid after hemithyroidectomy. Hypothyroidism following hemithyroidectomy occurred in patients with higher preoperative TSH levels.. The screening test for postoperative hypothyroidism should be performed from month to year after operation.