• IE interfaces
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• v.11 no.3
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• pp.89-101
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• 1998

The randomness of the input variables in simulation experiments produce output responses which are also realizations of random variables. The random responses make necessary the use of statistical inferences to adequately describe the stochastic nature of the output. The analysis of the simulation output of non-terminating simulations is frequently complicated by the autocorrelation of the output data and the effect of the initial conditions that produces biased estimates. The regenerative method has been developed to deal with some of the problems created by the random nature of the simulation experiments. It provides a simple solution to some tactical problems and can produce valid statistical results. However, not all processes can he modeled using the regenerative method. Other processes modeled as regenerative may not return to a given demarcating state frequently enough to allow for adequate statistical analysis. This paper shows how the state transformation concept was successfully used in a queueing model and a job shop model. Although the first example can be analyzed using the regenerative method. it has the problem of too few recurrences under certain conditions. The second model has the problem of no recurrences. In both cases, the state transformation increase the frequency of the demarcating state. It was shown that time state transformations are regenerative and produce more cycles than the best typical discrete demarcating state in a given run length.

• Journal of Korean Neurosurgical Society
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• v.29 no.10
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• pp.1383-1388
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• 2000

We report a case of 54 years old male with malignant meningioma originating in the posterior fossa with multiple recurrences, intracranial and extracranial metastases. In spite of gross total removal of tumor and conventional external radiation therapy(CERT), 2 more recurrences, 5 more intracranial metastases and 1 extracranial metastasis to the rib were developed. We tried fractionated stereotactic radiation therapy(FSRT) and CERT to the intracranial metastasis with satisfactory result. Extracranial metastasis to the rib was resected and histological finding was similar to that of original tumor.

• Imaging Science in Dentistry
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• v.38 no.2
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• pp.117-120
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• 2008

The odontogenic keratocyst (OKC) is a developmental odontogenic cyst typically occurring in the jaws. Since the first description of OKC was published in 1956, the lesion has been of particular interest because of its specific histopathologic features, high recurrence rate, and aggressive behavior. Recurrences most commonly arise within bone at the site of the original cyst. However, as lining cells may find their way into surrounding tissues either from implantation during surgery or from cortical perforation recurrences may arise at a distance from the original cyst. Here, we report a rare case of recurrent OKC which was first developed in mandible and recurred within the masticatory space.

• Advances in pediatric surgery
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• v.3 no.1
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• pp.24-31
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• 1997

Thirty-four consecutive cases of thyroglossal duct lesions in children were reviewed at the Department of Surgery, Chonbuk National University Hospital. Twenty patients were males, and the most prevalent age of discovering was 2 to 4 years (52.9%). Resection was performed within 2 years after discovering the lesions in 19 cases, but was delayed untill 4 to 10 years in 6 cases. Cystic lesions (85.3%) were 5.8 times more common than fistulas. A midline upper neck mass was found in every cystic cases, and a draining sinus at hyoid region was noticed in fistula patients. The location of the lesion was on the hyoid bone in 34 cases, at the midline in 31 cases, slightly to the left in 2 cases, and slightly to the right in 1. Two cases were misdiagnosed as lymphadenopathy, and a single case of ectopic thyroid gland was misinterpreted as a thyroglossal duct cyst. Modified Sistrunk operation was performed in twenty-three cases(67.6%), Sistrunk operation in 9(26.5%), and cyst excision in 2(5.9%). Postoperative complications occurred in 4 cases(11.8%); 2 wound infections and 2 recurrences. One of recurrences was a fistula treated by modified Sistrunk operation, and the other was a cyst treated by cyst excision.

• Korean Journal of Bronchoesophagology
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• v.6 no.2
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• pp.172-176
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• 2000

Background and Objectives： The treatment of laryngeal carcinoma is not settled to date and surgeons have used lasers for a variety of benign and malignant lesions in the larynx with good success. The aim of this study is to evaluate the potential role of laser surgery for laryngeal carcinoma. Materials and Methods : Medical records from patients who had undergone laser surgery for laryngeal carcinoma at Seoul National University Hospital between January 1988 3nd December 1998 were reviewed retrospectively. Results : A total of 47 patients were seen during that period and their mean follow-up length was 29 months. Their local control rate was 91％ (94% for glottic T1, 60% for glottic T2, 50% for supraglottic T1 and 100％ for supraglottic T2). The cure rate after laser surgery with or without postoperative radiotherapy was 87％ and 6 of 47 patients showed local or regional recurrences. For those 6 patients, neck dissection, partial or total laryngectomy with or without postoperative RT were conducted and they were all followed up without evidence of disease. All 47 patients who had undergone laser surgery for laryngeal squamous cell carcinoma were followed up with NED and their larynx preservation rate was 96%. Conclusion： This study demonstrates the oncologic validity of laser surgery to the treatment of unadvanced laryngeal carcinoma. However, strict case selection is needed to avoid locoregional recurrences and consequent salvage operations.

• The Korean Journal of Pain
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• v.8 no.2
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• pp.324-327
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• 1995

Central serous chorioretinopathy is a relatively benign condition of young to middle-aged men, characterized by serous detachment of central retina as a consequence of focal leakage of fluid from the choriocapillaris through a defect in the retinal pigment epithelium. Approximately 80% of central serous chorioretinopathy undergo spontaneous resolution within 6 months. However 20 to 30% of patients with central serous chorioretinopathy have one or more recurrences and undergo chronic courses. In these cases laser photocoagulation is used to burn the leakage site directly, but there is no evidence that it reduces the chance of permanent loss of visual function and recurrence. We have administered stellate ganglion blocks (SGB) on a 43 year old male patient with central serous chorioretinopathy with multiple recurrences and experienced good results. We therefore recommend SGB as an effective treatment for central serous chorioretinopathy in conjunction with other ophthalmological treatments.

• Radiation Oncology Journal
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• v.35 no.4
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• pp.359-367
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• 2017

Purpose: This study sought to identify potential candidates for adjuvant radiotherapy and patterns of regional failure in patients who underwent curative-intent surgery for gallbladder cancer. Materials and Methods: Records for 70 patients with gallbladder cancer who underwent curative resection at a single institution between 2000 and 2016 were analysed retrospectively. No patients received adjuvant radiotherapy. Initial patterns of failure were evaluated. Regional recurrence was categorized according to the definitions of lymph node stations suggested by the Japanese Society of Hepato-Biliary-Pancreatic Surgery. Results: Median follow-up was 23 months. Locoregional recurrence as any component of first failure occurred in 29 patients (41.4%), with isolated locoregional recurrence in 13 (18.6%). Regional recurrence occurred in 23 patients, and 77 regional recurrences were identified. Commonly involved regional stations were #13, #12a2, #12p2, #12b2, #16a2, #16b1, #9, and #8. Independent prognostic factors for locoregional recurrence were ${\geq}pT2$ disease (hazard ratio [HR], 5.510; 95% confidence interval [CI], 1.260-24.094; p = 0.023) and R1 resection (HR, 6.981; 95% CI, 2.378-20.491; p < 0.001). Conclusion: Patients with pT2 disease or R1 resection after curative surgery for gallbladder cancer may benefit from adjuvant radiotherapy. Our findings on regional recurrence may help physicians construct a target volume for adjuvant radiotherapy.

• Radiation Oncology Journal
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• v.6 no.2
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• pp.203-209
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• 1988

Thirty eight women with recurrent breast carcinoma involving chest wall and/or regional lymph nodes after surgery with or without systemic therapy were treated with radiation between 1979 and 1986. Among them, 5 patients were excluded from analysis because of incomplete treatment. The median follow up of survivors was 30 months (randged 1-79 months). Fifteen (45%)patients had their disease confined to the chest wall and eighteen patients had lymph node involvement as some of their locoregional recurrent disease. Within 36 months after the initial treatment, 87% of recurrences manifested themselves. All patients had radiotherapy to at least the site of involvement. In 8 patients, recurrent tumors were treated with complete excision followed by radiation. Of the remaining 25 patients,18 (72%) had complete response (CR) following radiotherapy. The actuarial 3-year survival of all patients following locoregional recurrence was 50% Three year survival was 24% in those 25 patients who had recurrences within 24 months of the initial treatment. For those 8 patients whose recurrences occurred after more than 24 month disease free interval, the 3-year survival was 100%. For those patients with recurrences confined to chest wall alone, 3-year survival was 57% The patients who had lymph node involvement as part of their locoregional recurrences had a 43% 3-year survival. The majority of them developed distant metastases. Those patients who had a CR showed 63% 3-year survival. On the other hand, 1 year survival was only 33% for those patients who had a less than CR. Three patients developed carcinoma of the contralateral breast following radiotherapy. Three year survival following locoregional recurrence was 40% for patients whose initial treatment for their primary breast carcinoma was surgery and adjuvant systemic therapy. For those patients whose primary breast carcinoma was treated by surgery alone, the 3-year survival following locoregional recurrence was 71%. In patients who had subsequent recurrence after radiotherapy, the actuarial survival was 25% at 2 years.

• Journal of applied mathematics & informatics
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• v.31 no.3_4
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• pp.327-336
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• 2013

Generalized Pareto distributions play an important role in re-liability, extreme value theory, and other branches of applied probability and statistics. This family of distribution includes exponential distribution, Pareto distribution, and Power distribution. In this paper we establish some recurrences relations satisfied by the quotient moments of the upper record values from the generalized Pareto distribution. Further a char-acterization of this distribution based on recurrence relations of quotient moments of record values is presented.

• Advances in pediatric surgery
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• v.10 no.1
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• pp.43-46
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• 2004

Two cases of trichobezoar with unusual presentation in female children are described. The first case is a 7-year-old female with a 3-day history of abdominal pain, obstipation, and emesis. She developed intestinal obstruction and showed double bezoars in the stomach and intestine respectively. She had been in a habit of biting or sucking hairs before sleeping from infancy until 5 years of age. The other patient is a 6-year-old girl referred for an epigastric mass, emotional disturbance and trichotillomania. In spite of the psychological treatment, 4 laparotomies were necessary due to repeated recurrences.