• Journal of Korea Water Resources Association
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• v.55 no.5
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• pp.345-356
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• 2022

A severe flooding occured at a small urban catchment in Daejeon-si South Korea on July 30, 2020 causing significant loss of property (inundated 78 vehicles and two apartments) and life (one casualty and 56 victims). In this study, a retrospective analysis of the inundation event was implemented using a physically-based urban flood model, H12 with high-resolution data. H12 is an integrated 1-dimensional sewer network and 2-dimensional surface flow model supported by hybrid parallel techniques to efficiently deal with high-resolution data. In addition, we evaluated the impact of the flooding barriers which were installed after the flood disaster. As a result, it was found that the inundation was affected by a combination of multiple components including the shape of the basin, the low terrain of the inundation area located in the downstream part of the basin, and lack of pipe capacity to drain discharge from the upstream during heavy rain. The impact of the flooding barriers was analyzed by modeling with and without barriers on the high-resolution terrain input data. It was evaluated that the flood barriers effectively lower the water depth in the apartment complex. This study demonstrates capability of high-resolution physically-based urban modeling to quantitatively assess the past inundation event and the impact of the reduction measures.

• Journal of Periodontal and Implant Science
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• v.54 no.1
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• pp.53-62
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• 2024

Purpose: This study aimed to evaluate the long-term cumulative survival rate (CSR) of dental implants with micro-threads in the neck over a 10-year follow-up period and to examine the factors influencing the survival rate of dental implants. Methods: This retrospective study was based on radiographic and dental records. In total, 151 patients received 490 Oneplant^® dental implants with an implant neck micro-thread design during 2006-2010 in the Department of Periodontology of Seoul National University Dental Hospital. Implant survival was evaluated using Kaplan-Meier analysis. Cox proportional hazard regression analysis was used to identify the factors influencing implant failure. Results: Ten out of 490 implants (2.04%) failed due to fixture fracture. The CSR of the implants was 97.9%, and no significant difference was observed in the CSR between external-and internal-implant types (98.2% and 97.6%, respectively, P=0.670). In Cox regression analysis, 2-stage surgery significantly increased the risk of implant failure (hazard ratio: 4.769, P=0.039). There were no significant differences in influencing factors, including sex, age, implant diameter, length, fixture type, location, surgical procedure, bone grafting, and restoration type. Conclusions: Within the limitations of this retrospective study, the micro-thread design of the implant neck was found to be favorable for implant survival, with stable clinical outcomes.

• The Korean Journal of Pain
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• v.28 no.2
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• pp.137-143
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• 2015

Background: Insomnia is becoming increasingly recognized as a clinically important symptom in patients with chronic low back pain (CLBP). In this retrospective study, we have determined risk factors associated with clinical insomnia in CLBP patients in a university hospital in Korea. Methods: Data from four-hundred and eighty one CLBP patients was analyzed in this study. The Insomnia Severity Index (ISI) was used to determine the presence of clinical insomnia (ISI score ${\geq}15$). Patients' demographics and pain-related factors were evaluated by logistic regression analysis to identify risk factors of clinical insomnia in CLBP. Results: It was found that 43% of patients reported mild to severe insomnia after the development of back pain. In addition, 20% of patients met the criteria for clinically significant insomnia (ISI score ${\geq}15$). In a stepwise multivariate analysis, high pain intensity, the presence of comorbid musculoskeletal pain and neuropathic pain components, and high level of depression were strongly associated with clinical insomnia in CLBP. Among these factors, the presence of comorbid musculoskeletal pain other than back pain was the strongest determinant, with the highest odds ratio of 8.074 (95% CI 4.250 to 15.339) for predicting clinical insomnia. Conclusions: Insomnia should be addressed as an integral part of pain management in CLBP patients with these risk factors, especially in patients suffering from CLBP with comorbid musculoskeletal pain.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.16
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• pp.6727-6732
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• 2014

Objectives: Advanced gastric cancer (AGC) patients have a poor prognosis. The best benefit of chemotherapy is usually achieved by first line setting. Very few studies have compared combination regimens. This study was designed to compare two combination regimens. Methods: Patients with advanced gastric cancer receiving first line chemotherapy were retrospectively collected, and divided into two groups, receiving DCF (docetaxel, cisplatin and fluorouracil) or ECF (epirubicin, cisplatin and fluorouracil) regimens. Data were collected for the retrospective analysis in a single center. Results: Eighty-six patients were eligible for analysis. Median overall survival (OS) was 10.0 months in the ECF group and 11.0 months in the DCF group (p=0.31). Median progression free survival (PFS) for ECF and DCF was equal at 6.0 months. Second line chemotherapy were administered in more than one third of patients. Both regimens had similar toxicity. Conclusions: This is the first study investigating the outcomes of gastric cancer chemotherapy in this region. ECF and DCF regimens have similar efficacy and a similar tolerability profile for first line treatment of advanced gastric cancer. The decision of the first line chemotherapy in advanced gastric cancer could be improved with patient selection according to clinical parameters and molecular markers.

• The Journal of Korean Medicine
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• v.41 no.2
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• pp.107-121
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• 2020

Objectives: The purpose of this study was to identify the characteristics of patients who visited the emergency room (ER) of a Korean medicine (KM) hospital and to provide basic data for further research. Methods: We conducted a retrospective analysis using electronic medical records of 263 patients who visited the ER of OO University Oriental Hospital from January 1 to December 31, 2019. Results: Of the 263 patients' medical records, 245 were included in this analysis. The male-to-female ratio was 1.09:1. The average age was 52 years, with patients in their 40s having the largest distribution. The district where the hospital was located had the largest number of patients. The distribution by visit time was the lowest in the early morning. Most patients visited on Sunday, in September, and on the day of onset. The admission rate was 39.18%, and largest number of patients was admitted to the Department of Acupuncture and Moxibustion. The percentage of patients who revisited the KM hospital as an outpatient were 26.17%. The diagnosis for most patients was musculoskeletal disease. Acupuncture was the most common treatment, accounting for 62.45% of the cases, followed by herbal medicines, accounting for 54.69% of the cases. National health insurance was the most common type of insurance registered. Most patients visited the ER of the KM hospital via the ER of the hospital. Conclusions: This clinical analysis helped us identify the characteristics of patients visiting the ER of a KM hospital. Continuous data accumulation is required in relation to this for further studies.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.1
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• pp.381-386
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• 2013

Aims: The aim of this study was to investigate the effects of adjuvant chemotherapy cycles on the prognosis of patients with post-operative stomach cancer through retrospective analysis. Methods: A total of 128 patients with gastric cancer who underwent gastrectomy, followed by adjuvant chemotherapy consisting of epirubicin, cisplatin or oxaliplatin, leucovorin, and 5-fluorouracil, according to a defined schedule, were divided into three groups according to the number of chemotherapy cycles: Group I (<6 cycles); Group II (6 cycles); and Group III (>6 cycles). Results: The 5-year overall survival (OS) was 20.8% in Group I, 45.0% in Group II, and 42.9% in Group III, with a median follow-up of 43 months. The 5-year relapse-free survival (RFS) was 15.1% in Group I, 40% in Group II, and 40% in Group III. The OS and RFS in Groups II and III were significantly better than in Group I (OS, p = 0.002 and p=0.003; RFS, P<0.001 and P=0.002). There was no difference in OS (p = 0.970) or in RFS (p = 0.722) between Groups II and III. Multivariate Cox hazard analysis determined that the number of adjuvant chemotherapy cycles was an independent factor that influenced OS and RFS. Conclusion: Six cycles of adjuvant chemotherapy gave encouraging outcomes in patients with resectable gastric cancer. Further prospective randomized controlled investigations are warranted in a multi-center setting.

• Journal of the Korea Convergence Society
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• v.6 no.6
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• pp.263-270
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• 2015

L2 learners deal with communication problems encountered during the course of their oral communication by employing what are known as communication strategies(CSs). As CSs play a significant role in communication and language learning, identifying CSs that facilitate communication has become important in L2 research. However, there have been some controversies about how to identify CSs, especially about data sources: conversation data, retrospective interview data, or combining two types of data. Drawing on the advantages of converged data, this study aimed to identify CSs that L2 learners use in their English communication through a convergence analysis of data. In this qualitative case study, the data were collected from Korean L2 learners' conversations and retrospective verbal reports in stimulated recall interviews. Using a data convergence approach, various CSs were identified: definition replacement CSs, message change CSs, time-gaining CSs, and comprehension CSs. This study suggests the effectiveness of CSs in handling L2 communication problems and the usefulness of data convergence in L2 CS research.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.1841-1844
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• 2012

Background: The majority of patients with pancreatic cancer present with advanced disease. Systemic chemotherapy has limited impact on overall survival (OS) so that eligible patients should be selected carefully. The aim of this study was to analyze prognostic factors for survival in Turkish advanced pancreatic cancer patients who survived more than one year from the diagnosis of recurrent and/or metastatic disease and receiving gemcitabine (Gem) alone or gemcitabine plus cisplatin (GemCis). Methods: This retrospective evaluation was performed for patients who survived more than one year from the diagnosis of recurrent and/or metastatic disease and who received gemcitabine between December 2005 and August 2011. Twenty-seven potential prognostic variables were chosen for univariate and multivariate analyses to identify prognostic factors associated with survival. Results: Among the 27 variables in univariate analysis, three were identified to have prognostic significance: sex (p = 0.04), peritoneal dissemination (p =0.02) and serum creatinine level (p=0.05). Multivariate analysis by Cox proportional hazard model showed only peritoneal dissemination to be an independent prognostic factor for survival. Conclusion: In conclusion, peritoneal metastasis was identified as an important prognostic factor in metastatic pancreatic cancer patients who survived more than one year from the diagnosis of recurrent and/or metastatic disease and receiving Gem or GemCis. The findings should facilitate pretreatment prediction of survival and can be used for selecting patients for treatment.

• Journal of Environmental Policy
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• v.10 no.2
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• pp.61-92
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• 2011

We analyzed the efficiency of environment investments by taking examples of central government's environmental investment (CGEI hereafter) and investment in prevention of environmental pollution (IPEP hereafter). We expanded the scope of existing studies by decomposing the internal rate of return (IRR hereafter) and present value of benefit (Bpv hereafter) into variable cost (VC hereafter) reduction, investment cost reduction (STC-VC hereafter), and rent. And we found that Bpv checks only the magnitude of benefit, while IRR indicates the existence of efficiency by investigating short-run total cost (STC hereafter) reduction and rent. Finally, by analyzing investment efficiency and changing benefit with respect to CGEI and IPEP through the investment efficiency methodology that compares IRR with market interest rate, we executed retrospective benefit-cost analysis. Accordingly, CGEI and IPEP are not efficient. However, IPEP is even more inefficient than CGEI.

• Journal of Periodontal and Implant Science
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• v.49 no.5
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• pp.287-298
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• 2019

Purpose: The aim of this retrospective study was to determine the prevalence of early implant failure using a single implant system and to identify the factors contributing to early implant failure. Methods: Patients who received implant treatment with a single implant system ($Luna^{(R)}$, Shinhung, Seoul, Korea) at Dankook University Dental Hospital from 2015 to 2017 were enrolled. The following data were collected for analysis: sex and age of the patient, seniority of the surgeon, diameter and length of the implant, position in the dental arch, access approach for sinus-floor elevation, and type of guided bone regeneration (GBR) procedure. The effect of each predictor was evaluated using the crude hazard ratio and the adjusted hazard ratio (aHR) in univariate and multivariate Cox regression analyses, respectively. Results: This study analyzed 1,031 implants in 409 patients, who comprised 169 females and 240 males with a median age of 54 years (interquartile range [IQR], 47-61 years) and were followed up for a median of 7.2 months (IQR, 5.6-9.9 months) after implant placement. Thirty-five implants were removed prior to final prosthesis delivery, and the cumulative survival rate in the early phase at the implant level was 95.6%. Multivariate regression analysis revealed that seniority of the surgeon (residents: aHR=2.86; 95% confidence interval [CI], 1.37-5.94) and the jaw in which the implant was placed (mandible: aHR=2.31; 95% CI, 1.12-4.76) exerted statistically significant effects on early implant failure after adjusting for sex, age, dimensions of the implant, and type of GBR procedure (preoperative and/or simultaneous) (P<0.05). Conclusions: Prospective studies are warranted to further elucidate the factors contributing to early implant failure. In the meantime, surgeons should receive appropriate training and carefully select the bone bed in order to minimize the risk of early implant failure.