• Journal of the Korean Data and Information Science Society
• /
• 제23권2호
• /
• pp.257-269
• /
• 2012

최근 글로벌 금융위기와 중소기업들의 연이은 도산으로 인해 국내 중소기업들의 구조조정에 대한 논의가 활발히 진행되고 있다. 이에 본 논문에서는 신용보증기금에 등록된 중소기업 자료에 대하여 업종별 생존율 동향을 비교분석하였다. 이때 생존율의 차이는 로그순위 검정과 윌콕슨의 검정통계량을 사용하여 분석하였다. 또한 재무변수들을 이용하여 중소기업의 업종별 콕스 회귀분석을 실시하였다. 그 결과, 도소매업과 서비스업이 경공업과 중공업, 건설업에 비하여 생존율이 높았으며, 건설업의 경우 생존율이 가장 낮음을 알 수 있었다. 또한, 업종별로 유의한 재무변수를 살펴보면, 건설업은 자기자본비율, 유동비율이 커질수록 부도율이 감소하는 반면에 차입금의존도가 커질수록 부도율이 증가하였다. 경공업은 자기자본비율, 총자산 순이익률이 커질수록, 도소매업은 자기자본비율, 유동비율이 커질수록 부도율이 감소하였다. 중공업은 자기자본비율, 총자산 순이익률, 유동비율이 커질수록 부도율이 감소하였지만 결합지표가 커질수록 부도율이 증가하였다. 마지막으로, 서비스업은 유동비율이 커질수록 부도율이 감소하였다.

• 해양환경안전학회지
• /
• 제29권2호
• /
• pp.238-247
• /
• 2023

선박 연료로서 LPG는 현재의 기술과 경제성 등을 고려하였을 때 매력적인 연료이다. 하지만, 아직 LPG 연료 선박의 안전 지침을 개발 중에 있고, 국내에서는 중소형 선박에 LPG 추진 시스템을 적용한 사례가 없다. 본 연구에서는 국내 최초 개발된 해상용 LPG 엔진 시스템에 대해 보다 객관적인 위험성 평가를 수행하고 안전 운용 기준을 제안하고자 한다. 우선, 위험과 운전 분석 기법을 통해 동 엔진 시스템을 5개의 검토 구간으로 분할하고 총 58가지의 위험요소를 식별하였다. 그다음 정성적 평가인 HAZOP 기법의 주관성을 보완하기 위해 퍼지 이론을 사용하고 검출도, 민감도 등 위험 요인을 추가하여 퍼지 분석적 계층 과정을 통해 위험 요인의 상대적 가중치를 비교하였다. 그 결과, 5가지의 위험 요인 중, 위험성에 가장 큰 영향을 미치는 위험 요인은 발생 빈도와 심각도로 평가되었다. 마지막으로, 위험 요인에 대한 가중치를 고려하여 위험 순위를 세밀하게 선정하기 위해 퍼지 TOPSIS 기법을 적용하였다. 그 결과, 위험 등급은 47개 그룹으로 구분할 수 있었고, 동 엔진 시스템의 운용 중 가장 위험도가 높은 위험요소는 LPG 공급 라인 유지 보수 중 가스 누출로 분석되었다. 본 연구에 제안된 기법을 LPG 공급계통 등 다양한 설비에도 적용하여, 향후 LPG 추진 선박의 안전 기준 마련을 위한 위험성 평가의 표준절차로 활용할 수 있기를 기대한다.

• Korean Journal of Radiology
• /
• 제21권6호
• /
• pp.707-716
• /
• 2020

Objective: To evaluate pharmacokinetic variables from contrast-enhancing lesions (CELs) and non-enhancing T2 high signal intensity lesions (NE-T2HSILs) on dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging for predicting progression-free survival (PFS) in glioblastoma (GBM) patients. Materials and Methods: Sixty-four GBM patients who had undergone preoperative DCE MR imaging and received standard treatment were retrospectively included. We analyzed the pharmacokinetic variables of the volume transfer constant (Ktrans) and volume fraction of extravascular extracellular space within the CEL and NE-T2HSIL of the entire tumor. Univariate and multivariate Cox regression analyses were performed using preoperative clinical characteristics, pharmacokinetic variables of DCE MR imaging, and postoperative molecular biomarkers to predict PFS. Results: The increased mean Ktrans of the CEL, increased 95th percentile Ktrans of the CELs, and absence of methylated O⁶-methylguanine-DNA methyltransferase promoter were relevant adverse variables for PFS in the univariate analysis (p = 0.041, p = 0.032, and p = 0.083, respectively). The Kaplan-Meier survival curves demonstrated that PFS was significantly shorter in patients with a mean Ktrans of the CEL > 0.068 and 95th percentile Ktrans of the CEL > 0.223 (log-rank p = 0.038 and p = 0.041, respectively). However, only mean Ktrans of the CEL was significantly associated with PFS (p = 0.024; hazard ratio, 553.08; 95% confidence interval, 2.27-134756.74) in the multivariate Cox proportional hazard analysis. None of the pharmacokinetic variables from NE-T2HSILs were significantly related to PFS. Conclusion: Among the pharmacokinetic variables extracted from CELs and NE-T2HSILs on preoperative DCE MR imaging, the mean Ktrans of CELs exhibits potential as a useful imaging predictor of PFS in GBM patients.

• Korean Journal of Radiology
• /
• 제22권9호
• /
• pp.1514-1524
• /
• 2021

Objective: To develop a radiomics risk score based on dynamic contrast-enhanced (DCE) MRI for prognosis prediction in patients with glioblastoma. Materials and Methods: One hundred and fifty patients (92 male [61.3%]; mean age ± standard deviation, 60.5 ± 13.5 years) with glioblastoma who underwent preoperative MRI were enrolled in the study. Six hundred and forty-two radiomic features were extracted from volume transfer constant (K^trans), fractional volume of vascular plasma space (V_p), and fractional volume of extravascular extracellular space (V_e) maps of DCE MRI, wherein the regions of interest were based on both T1-weighted contrast-enhancing areas and non-enhancing T2 hyperintense areas. Using feature selection algorithms, salient radiomic features were selected from the 642 features. Next, a radiomics risk score was developed using a weighted combination of the selected features in the discovery set (n = 105); the risk score was validated in the validation set (n = 45) by investigating the difference in prognosis between the "radiomics risk score" groups. Finally, multivariable Cox regression analysis for progression-free survival was performed using the radiomics risk score and clinical variables as covariates. Results: 16 radiomic features obtained from non-enhancing T2 hyperintense areas were selected among the 642 features identified. The radiomics risk score was used to stratify high- and low-risk groups in both the discovery and validation sets (both p < 0.001 by the log-rank test). The radiomics risk score and presence of isocitrate dehydrogenase (IDH) mutation showed independent associations with progression-free survival in opposite directions (hazard ratio, 3.56; p = 0.004 and hazard ratio, 0.34; p = 0.022, respectively). Conclusion: We developed and validated the "radiomics risk score" from the features of DCE MRI based on non-enhancing T2 hyperintense areas for risk stratification of patients with glioblastoma. It was associated with progression-free survival independently of IDH mutation status.

• 응용통계연구
• /
• 제27권1호
• /
• pp.21-30
• /
• 2014

치유율 모형(cure rate model)은 위험 그룹의 단조 감소에 대한 가정이 부적절한 경우에 적용될 수 있다. 예를 들어, 생존 분석에서 위험 그룹은 시간이 경과함에 따라 점점 감소하여 무한대의 시간대에는 영으로 수렴하며 이는 곧 생존 함수가 영으로 수렴함을 의미한다. 하지만 이러한 가정이 적합하지 못한 자료가 의약학, 사회학, 경제학 등에서 종종 발생된다. 즉, 어느 시점에 이르러 더 이상의 생존함수는 감소하지 않고 평행선을 보여주는 경우에 로그 순위검정(log rank test)과 Cox's 비례위험모형(proportional hazard model)의 적용은 바람직하지 못한 결론을 가져오게 된다. 이러한 자료에 대해 치유율 모형(cure rate model)에서는 사건 발생 취약 그룹(susceptible group)과 비취약 그룹(insusceptible group)으로 나누어 취약그룹에 대해서만 일반적인 생존 분석 방법을 적용하는 혼합 모형(mixture model)을 적용해왔다 (Berkson과 Gage, 1952). 본 연구에서는 이러한 치유율 모형을 군집화 구간 중도 절단 자료(clustered interval censored data)에 적용해 보고자 한다. 최근에 Kim과 Jhun (2008)은 구간 중도 절단자료에 대해 치유율 모형을 적용하였으며 본 연구에서는 그들의 방법을 군집화 자료로 확장할 것이다. 실제 자료 분석의 예로 금연자료를 분석할 것이다.

• Asian Pacific Journal of Cancer Prevention
• /
• 제14권6호
• /
• pp.3769-3772
• /
• 2013

Background: To investigate the impact of the lymph node ratio (LNR) on the prognosis of patients with locally advanced rectal cancer undergoing pre-operative chemoradiation. Methods: Clinicopathologic and follow up data of 128 patients with stage III rectal cancer who underwent curative resection from 1996 to 2007 were reviewed. The patients were divided into two groups according to the lymph node ratio: LNR ${\leq}$ 0.2 (n=28), and >0.2 (n=100). Kaplan-Meier and the Cox proportional hazard regression models were used to evaluate the prognostic effects according to LNR. Results: Median numbers of lymph nodes examined and lymph nodes involved by tumour were 10.3 (range 2-28) and 5.8 (range 1-25), respectively, and the median LNR was 0.5 (range, 0-1.6). The 5-year survival rate significantly differed by LNR (${\leq}$ 0.2, 69%; >0.2, 19%; Log-rank p value < 0.001). LNR was also a significant prognostic factor of survival adjusted for age, sex, post-operative chemotherapy, total number of examined lymph nodes, metastasis and local recurrence (${\leq}$ 0.2, HR=1; >0.2, HR=4.8, 95%CI=2.1-11.1) and a significant predictor of local recurrence and distant metastasis during follow-up independently of total number of examined lymph node. Conclusions: Total number of examined lymph nodes and LNR were significant prognostic factors for survival in patients with stage III rectal cancer undergoing pre-operative chemoradiotherapy.

• Tuberculosis and Respiratory Diseases
• /
• 제80권2호
• /
• pp.179-186
• /
• 2017

Background: Although the World Health Organization (WHO) classification of lung squamous cell carcinoma (SCC) was revised in 2015, its clinical implications for lung SCC subsets remain unclear. We investigated whether the morphologic characteristics of lung SCC, including keratinization, were associated with clinical parameters and clinical outcome of patients. Methods: A total of 81 patients who underwent curative surgical resection of diagnosed lung SCC, were enrolled in this study. Attributes such as keratinization, tumor budding, single cell invasion, and nuclear size within the tumor, as well as immunohistochemistry of Bcl-xL and pS6 expressions, were evaluated. Results: The keratinizing and nonkeratinizing subtypes did not differ with respect to age, sex, TNM stage, and morphologic parameters such as nuclear diameter, tumor budding, and single cell invasion at the tumor edge. Most patients with the keratinizing subtype (98.0%) had a history of smoking, whereas the nonkeratinizing group had a relatively higher proportion of never-smokers relative to the keratinizing group (24.0% vs. 2.0%; p=0.008, chi-square test). Expression of pS6 (a surrogate marker of mammalian target of rapamycin complex 1 [mTORC1] signaling that regulates keratinocyte differentiation), and Bcl-xL (a key anti-apoptotic molecule that may inhibit keratinization), did not correlate significantly with the presence of keratinization. Patients with the keratinizing subtype had a significantly shorter overall survival (85.2 months vs. 135.7 months, p=0.010, log-rank test), and a multivariate analysis showed that keratinization was an independent, poor prognostic factor (hazard ratio, 2.389; 95% confidence interval, 1.090-5.233; p=0.030). Conclusion: In lung SCC, keratinization is associated with a poor prognosis, and might be associated with smoking.

• 대한치과의사협회지
• /
• 제55권2호
• /
• pp.116-127
• /
• 2017

Objectives : The aim of this study was to evaluate the cumulative survival rates of the implants placed into grafted sinus and determine the effect of age, gender, smoking, and systemic disease on the implant cumulative survival rates. Materials and Methods : The retrospective study was performed on 51 implants placed in 26 patients by one dentist at the Dental Implant Center, Seoul National University Dental Hospital in the years 2000-2010. The cumulative survival rates were calculated by the Kaplan-Meier method. The differences within the factors were analyzed using log-rank test and the correlations between the factors and implant survival rates were analyzed using Cox proportional hazard model. Results : 1. Among the total of 51 implants placed in 26 patients, 7 implants failed and 44 implants remained stable. The 1-year, 5-year, and 10-year cumulative survival rates were 92%, 88%, and 85%, respectively. 2. Patients in their 50s and in their 70s showed statistically significant difference in the cumulative survival rates (P < 0.05). Gender and the existence of systemic disease did not show significant results. 3. In the implant treatment, smokers showed 7.5 times higher risk of implant failure than non-smokers (P < 0.05). Conclusion: Implants installed in combination with sinus elevation can be considered as a reliable treatment method.

• Journal of Gastric Cancer
• /
• 제18권3호
• /
• pp.242-252
• /
• 2018

Purpose: Surgical resection for gastric adenocarcinoma is associated with significant post-operative morbidity and mortality. The aim of this study was to assess the prognostic significance of sarcopenia in patients undergoing resection for gastric adenocarcinoma with respect to post-operative morbidity and survival. Materials and Methods: A retrospective analysis was conducted on a cohort of consecutive patients who underwent surgical resection for gastric adenocarcinoma between 2008 and 2014. Patient demographics, radiological parameters, and pathological data were collected. OsiriX software (Pixmeo) was used to measure skeletal muscle area, which was normalized for height to calculate skeletal muscle index. Results: A total of 56 patients (41 male, 15 female; mean age, $68.4{\pm}11.9years$) met the inclusion criteria. Of these, 36% (20 of 56) of the patients were sarcopenic pre-operatively. Both sarcopenic and non-sarcopenic patient groups were equally matched with the exception of weight and body mass index (P=0.036 and 0.001, respectively). Sarcopenia was associated with a decreased overall survival (log-rank P=0.003) and was an adverse prognostic predictor of overall survival in multivariate analysis (hazard ratio, 10.915; P=0.001). Sarcopenia was a predictor of serious in-hospital complications in multivariate analysis (odds ratio, 3.508; P=0.042). Conclusions: In patients undergoing curative resection for gastric cancer, there was a statistically significant association between sarcopenia and both decreased overall survival and serious post-operative complications. The measurement and reporting of skeletal muscle index on pre-operative computed tomography should be considered.

• Journal of Korean Neurosurgical Society
• /
• 제57권2호
• /
• pp.108-113
• /
• 2015

Objective : Although the L5-S1 has distinct structural features in comparison with other lumbar spine segments, not much is known about adjacent segment degeneration (ASD) at the L5-S1 segment. The aim of study was to compare the incidence and character of ASD of the cephalad and L5-S1 segments after L5 floating lumbar fusion. Methods : From 2005 to 2010, 115 patients who underwent L5 floating lumber fusion were investigated. The mean follow-up period was 46.1 months. The incidence of radiological and clinical ASD of the cephalad and the L5-S1 segments was compared using survival analysis. Risk factors affecting ASD were analyzed using a log rank test and the Cox proportional hazard model. Results : Radiological ASD of the L5-S1 segment had a statistically significant higher survival rate than that of the cephalad segment (p=0.001). However, clinical ASD of the L5-S1 segment was significantly lower survival rates than that of the cephalad segment (p=0.038). Risk factor analysis showed that disc degeneration of the cephalad segment and preoperative spinal stenosis of the L5-S1 segment were risk factors. Conclusion : In L5 floating fusion, radiological ASD was more common in the cephalad segment and clinical ASD was more common in the L5-S1 segment. At the L5-S1 segment, the degree of spinal stenosis appears to be the most influential risk factor in ASD incidences, unlike the cephalad segment.