• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.115-117
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• 2002

In this paper, we obtain an explicit formula of the Laplace transform of the forward recurrence time at finite time t > 0 in an alternating renewal process, by adopting a Markovian approach. As a consequence, we obtain the first two moments of the forward recurrence time.

• Journal of the Korean Statistical Society
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• v.33 no.3
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• pp.299-302
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• 2004

A Markovian approach is introduced to find the Laplace transform of the forward recurrence time in the renewal process at finite time t > 0. Until now, most works on the forward recurrence time have been done through renewal arguments.

• International Journal of Reliability and Applications
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• v.3 no.4
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• pp.199-202
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• 2002

In this paper, we obtain an explicit formula of the Laplace transform of the forward recurrence time at finite time t > 0 in an alternating renewal process, by adopting a Markovian approach. As a consequence, we obtain the first two moments of the forward recurrence time.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2639-2642
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• 2012

Background: The patterns of gastric cancer recurrence vary across societies. We designed the current study in an attempt to evaluate and reveal the outbreak of the recurrence patterns of gastric cancer and also prediction of time to recurrence and its effected factors in Iran. Materials and Methods: This research was performed from March 2003 to February 2007. Demographic characteristics, clinical and pathological diagnosis and classification including pathologic stage, tumor grade, tumor site and tumor size in of patients with GC recurrent were collected from patients' data files. To evaluate of factors affected on the relapse of the GC patients, gender, age at diagnosis, treatment type and Hgb were included in the research. Data were analyzed using Kaplan-Meier and logistic regression models. Results: After treatment, 82 patients suffered recurrence, 42, 33 and 17 by the ends of first, second and third years. The mean ( SD) and median ( IQR) time to recurrence in patients with GC were 25.5 (20.6-30.1) and 21.5 (15.6-27.1) months, respectively. The results of multivariate analysis logistic regression showed that only pathologic stage, tumor grade and tumor site significantly affected the recurrence. Conclusions: We found that pathologic stage, tumor grade and tumor site significantly affect on the recurrence of GC which has a high positive prognostic value and might be functional for better follow-up and selecting the patients at risk. We also showed time to recurrence to be an important factor for follow-up of patients.

• The Korean Journal of Applied Statistics
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• v.26 no.5
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• pp.807-819
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• 2013

A recurrence plot can be used as a graphical exploratory data analysis tool before confirmatory time series analysis. With the recurrence plot, we can obtain the structural pattern of the time series and recognize the structural change points in a time series at a glance. Korean stock data shows the usefulness of the recurrence plot as a graphical exploratory data analysis tool for time series data.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.22 no.2
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• pp.142-151
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• 2019

Purpose: The aim of the study was to identify factors related to the recurrence of intussusception in pediatric patients. Methods: The medical charts of patients diagnosed with intussusception and treated at Dongsan Medical Center, between March 2015 to June 2017, were retrospectively reviewed. Univariate and multivariate analyses were performed. Results: Among 137 patients, 23 patients (16.8%) had a recurrent intussusception and 8 of these patients (6%) had more than 2 episodes of recurrence. The age at diagnosis was significantly different between the non-recurrence and recurrence group (p=0.026), with age >1 year at the time of diagnosis associated with a greater rate of recurrence (p=0.002). The time interval from symptom onset to the initial reduction (<48 vs. ${\geq}48$ hours) was significantly longer in the recurrence group (p=0.034) and patients in the recurrence group had higher levels of C-reactive protein (CRP) (p=0.024). Bloody stools and a history of infection were significantly more frequent in the non-recurrence group (p=0.001 and p<0.001, respectively). On stepwise regression analysis, age >1 year at the time of presentation (odds ratio [OR], 4.79; 95% confidence interval [CI], 1.56-14.06; p=0.016) and no history of infection (OR, 0.18; 95% CI, 0.06-0.58; p=0.004) were retained as predictors of recurrence. Conclusion: Patients with intussusception who are older than 1 year at diagnosis, have an elevated CRP level, a delay of ${\geq}48$ hours between symptom onset and the initial reduction, an absence of bloody stools, and no history of infection should be closely monitoring for symptoms and signs of a possible recurrence.

• Journal of Veterinary Clinics
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• v.24 no.1
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• pp.15-18
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• 2007

56 dogs that had undergone surgical excision of skin lesion tumors at Veterinary Medical Teaching Hospital in Seoul National University from 2000 to 2005 were evaluated retrospectively. The ratio of cases with benign versus malignant tumor types were 1.5:1.48 cases received surgical excision alone and 8 cases received adjuvant treatments. 42 cases were followed postoperative recurrence time and survival time (25 benign, 17 malignant). 25 cases (25/42, 60%) had no recurrence after surgical excision. In malignant tumor types, 5 cases (5/17, 29%) had recurrence and the median recurrence time was 157 days, and 8 cases (8/17, 47%) died due to tumors and survival time was 125 days. In benign tumor types, only 2 cases (2/25, 8%) had recurrence and the median recurrence time was 273 days.

• Journal of Chest Surgery
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• v.56 no.6
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• pp.403-411
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• 2023

Background: The concept of oligo-recurrence has not been generally applied in esophageal cancer. This study aimed to determine the prognostic significance of the number of recurrences in esophageal cancer. Methods: Patients with squamous cell carcinoma who underwent curative esophagectomy with R0 or R1 resection and who experienced a confirmed recurrence were included. The study included 321 eligible participants from March 2001 to December 2019. The relationship between the number of recurrences and post-recurrence survival was investigated. Results: The mean age was 63.8±8.1 years, and the majority of the participants (97.5%) were men. The median time to recurrence was 10.7 months, and the median survival time after recurrence was 8.8 months. Multiple recurrences with simultaneous local, regional, and distant locations were common (38%). In terms of the number of recurrences, single recurrences were the most common (38.3%) and had the best post-recurrence survival rate (median, 17.1 months; p<0.001). Patients with 2 or 3 recurrences showed equivalent survival to each other and longer survival than those with 4 or more (median, 9.4 months; p<0.001). In the multivariable analysis, the significant predictors of post-recurrence survival were body mass index, minimally invasive esophagectomy, N stage, R0 resection, post-recurrence treatment, and the number of recurrences (p<0.05). Conclusion: After esophagectomy, the number of recurrences was the most significant risk factor influencing post-recurrence survival in patients with esophageal cancer. In esophageal cancer, oligo-recurrence can be defined as a recurrence with three or fewer metastases. More intensive treatment might be recommended if oligo-recurrence occurs.

• Journal of Korean Neurosurgical Society
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• v.59 no.5
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• pp.498-504
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• 2016

Objective : Although subdural hematoma (SDH) is commonly treatable by burr hole surgery in the late subacute or chronic stage, there is no clear consensus regarding appropriate management and exact predictive factors for postoperative recurrence also remain unclear. The aim of this study was to evaluate risk factors associated with recurrence of SDH that requires burr hole surgery in the late subacute or chronic stage. We also identified the appropriate timing of surgery for reducing the recurrence. Methods : We retrospectively reviewed 274 patients with SDH in the late subacute or chronic stage treated with burr hole surgery in our hospital between January 2007 and December 2014. Excluding patients with acute intracranial complications or unknown time of trauma onset left 216 patients included in the study. Results : Of 216 patients with SDH in the late subacute or chronic stage, recurrence was observed in 36 patients (16.7%). The timing of the operation in patients with late subacute stage (15-28 days) resulted in a significant decrease in recurrence (RR, 0.33; 95% CI, 0.17-0.65; p=0.001) compared to chronic stage (>28 days). Otherwise, no significant risk factors were associated with recurrences including comorbidities and surgical details. Conclusion : The results indicated that time from trauma onset to burr hole surgery may be important for decreasing the risk of recurrence. Therefore, unless patients can be treated conservatively without surgery, prompt surgical management is recommended in patients diagnosed as having late subacute or chronic subdural hematoma treatable by burr hole surgery, even when neurological deficits are unclear.

• Journal of Gastric Cancer
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• v.1 no.2
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• pp.106-112
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• 2001

Purpose: Even with excellent surgical outcome, recurrence of early gastric cancer (EGC) after a curative resection is not declining because the incidence of EGC is increasing. The aim of this study was to propose an appropriate treatment strategy by assessing the risk factors for recurrence of curatively resected early gastric cancer. Materials and Methods: Of 3662 patients who had undergone gastric resections for gastric cancer from 1987 to 1996, the cases of 1050 curatively resected EGC patients were reviewed retrospectively. Among those 1050 patients, 50 patients ($4.8\%$) were diagnosed as having recurrent cancer, which was confirmed by clinico-radiological examination or re-operation. The risk factors that determined the recurrence patterns were investigated by using univariate and multivariate analyses. Results: The mean time to recurrence was 30.9 months, and hematogenous recurrence was the most frequent type ($32.0\%$). Among the 50 recurred patients, peritoneal recurrence showed the shortest mean time to recurrence ($18.5\pm17.7$months). Between the recurred and the non-recurred patients, there was no statistically significant difference with respect to age, sex, operation type, tumor size, tumor location, gross appearance, or histological differentiation. However, depth of invasion (submucosal invasion) and nodal involvement were significantly different (P<0.001) between the two groups. Using logistic regression analyses, nodal involvement was the only significant risk factor for recurrence in early gastric cancer (P<0.001). The median survival after the recurrence had been diagnosed was 4 months. Conclusion: Although the prognosis for EGC patients is excellent and recurrence of EGC after a curative resection is rare, the time to recurrence and the patterns of recurrence in EGC patients were diverse and unpredictable, and the result after recurrence is dismal. Considering the impact of lymph node metastasis on recurrence of EGC, a systematic lymphadenectomy, rather than limited surgery, should be performed if lymph node involvement is confirmed pre- or intraoperatively. Also if the postoperative pathologic findings reveal lymph node involvement, adjuvant chemotherapy is recommended.