• 한국통신학회논문지
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• 제35권1A호
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• pp.1-9
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• 2010

본 논문을 통해 i.n.d 레일리 패이딩 체널에서 서로 다른 변조/복조 기법을 사용하는 중계기들로 구성된 선택적 복호 후 재전송 네트워크의 성능평가를 보여준다. 본 논문은 i.i.d와 i.n.d 레일리 패이딩 채널 모두에서 선택적 복호 후 전송 프로토콜이 최대 다이버시티를 얻을 수 있다는 것을 보여준다. 또한 SC(selection combining)기법을 사용하는 시스템과 MRC(maximal ratio combining)기법을 사용하는 시스템의 성능을 비교하여 결합기술의 효과를 연구하였다. 높은 SNR에서 시뮬레이션 결과와 수식적 분석 결과가 정확하게 일치하는 것을 보여준다.

• 전기전자학회논문지
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• 제24권4호
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• pp.942-949
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• 2020

본 논문에서는 column-parallel readout 회로에 적합하도록 개선된 CMOS 이미지 센서용 algorithmic ADC를 제안한다. 커패시터의 비율과 무관하고 연산 증폭기의 이득에 둔감하면서 증폭기 하나로 동작 할 수 있도록 기존 algorithmic ADC를 수정하고 적응형 바이어싱을 적용한 증폭기를 사용하여 높은 변환효율을 갖도록 하였다. 제안하는 ADC는 0.18-㎛ 매그나칩 CMOS 공정으로 설계되었으며, Spectre 시뮬레이션을 통해 기존 algorithmic ADC에 비해 변환속도당 전력소모가 37% 줄어 들었음을 확인하였다.

• 한국농공학회논문집
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• 제57권5호
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• pp.89-99
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• 2015

In this research, 1,032 data of precise safety inspection from 2004 to 2013 are gathered and constructed for finding effective safety inspection systems. Items are extracted from constructed data and factors for typology are decided with statistical method such as principle component analysis and cluster analysis. For factor decision, we extruded independent characteristics such as morphological and geographical characteristic, and deleted items which can be expressed by combination of independent characteristics. Four factors such as total storage, watershed ratio, levee length ratio, and spillway length ratio are extracted in this process. In cluster analysis, levee length ratio is excluded because it is not separated as cluster. Finally nine types of agricultural reservoir are extruded by total storage, watershed ratio, and spillway length ratio with frequency analysis.

• 한국병원경영학회지
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• 제26권2호
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• pp.17-26
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• 2021

Purposes: This study aims to identify factors affecting dental university hospitals' profitability and understand recent their business condition. Methodology: Data from 2016 to 2019 was collected from financial statement, public open data in 8 dental university hospitals. For the study, multiple regression test with stepwise selection was applied. Findings: First of all, 9 out of 19 independent variables were selected by stepwise selection. As a result of multiple regression test with selected independent variables and the dependent variable(operating profit margin ratio), the factors affecting hospitals' profitability were the number of dental unit chair, hospital location, debt ratio, total capital turnover ratio, employment cost rate, material cost rate, management expense rate, the number of patient per a dentist. Practical Implication: To improve dental university hospitals' profitability, hospitals specifically analysis and manage their cost such as employment, material and management cost and seek effectiveness by managing the proper number of patient per a dentist.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.208-209
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• 2022

This study aims to analyze the risk factors caused by object damage and third-party damage loss in actual bridge construction based on past insurance premium payment data from major domestic insurers for bridge construction projects, and develop a quantitative loss prediction model. For the development of quantitative bridge construction loss model, the dependent variable was selected as the loss ratio, and the independent variable adopted 1) Technical factors: superstructure type, foundation type, construction method, and bridge length 2) Natural hazards: flood anf Typhoon, 3) Project information: total construction duration, total cost and ranking. Among the selected independent variables, superstructure type, construction method, and project period were shown to affect the ratio of bridge construction losses, while superstructure, foundation, flood and ranking were shown to affect the ratio of the third-party losses.

• Journal of Gastric Cancer
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• 제12권4호
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• pp.210-216
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• 2012

Purpose: To assess independent prognostic factors for lymph node-negative metastatic gastric cancer patients following curative resection is valuable for more effective follow-up strategies. Materials and Methods: Among 1,874 gastric cancer patients who received curative resection, 967 patients were lymph node-negative. Independent prognostic factors for overall survival in lymph node-negative gastric cancer patients grouped by tumor invasion depth (early gastric cancer versus advanced gastric cancer) were explored with univariate and multivariate analyses. Results: There was a significant difference in the distribution of recurrence pattern between lymph node-negative and lymph nodepositive group. In the lymph node-negative group, the recurrence pattern differed by the depth of tumor invasion. In univariate analysis for overall survival of the early gastric cancer group, age, macroscopic appearance, histologic type, venous invasion, lymphatic invasion, and carcinoembryonic antigen level were significant prognostic factors. Multivariate analysis for these factors showed that venous invasion (hazard ratio, 6.695), age (${\geq}59$, hazard ratio, 2.882), and carcinoembryonic antigen level (${\geq}5$ ng/dl, hazard ratio, 3.938) were significant prognostic factors. Multivariate analysis of advanced gastric cancer group showed that depth of tumor invasion (T2 versus T3, hazard ratio, 2.809), and age (hazard ratio, 2.319) were prognostic factors on overall survival. Conclusions: Based on our results, independent prognostic factors such as venous permeation, carcinoembryonic antigen level, and age, depth of tumor invasion on overall survival were different between early gastric cancer and advanced gastric cancer group in lymph node-negative gastric cancer patients. Therefore, we are confident that our results will contribute to planning follow-up strategies.

• Journal of the Korean Data and Information Science Society
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• 제18권4호
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• pp.1171-1177
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• 2007

We consider estimation of the right-tail probability in a log-Laplace random variable, As we derive the density of ratio of two independent log-Laplace random variables, the k-th moment of the ratio is represented by a special mathematical function. and hence variance of the ratio can be represented by a psi-function.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2005년도 춘계학술대회
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• pp.127-134
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• 2005

A suitable representation for the conceptual simplicity of the data in statistics and signal processing is essential for a subsequent analysis such as prediction, pattern recognition, and spatial analysis. Independent component analysis (ICA) is a statistical method for transforming an observed high-dimensional multivariate data into statistically independent components. ICA has been applied increasingly in wide fields of spectrum application since ICA is able to extract unknown components of a mixture from spectra. We focus on application of ICA for separating independent sources and predicting each composition using extracted components. The theory of ICA is introduced and an application to a metal surface spectra data will be described, where subsequent analysis using non-negative least square method is performed to predict composition ratio of each sample. Furthermore, some simulation experiments are performed to demonstrate the performance of the proposed approach.

• 한국지반공학회논문집
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• 제29권1호
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• pp.149-159
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• 2013

본고는 암석 코아에 함수비가 증가함에 따라 포아송비 거동형태를 구명하기 위하여 일축압축강도시험을 시행하였다. 현장에서 출토빈도가 높은 퇴적암, 화성암 및 변성암 시료 307개를 대상으로 포아송비의 함수거동을 관찰하였다. 포아송비는 암석의 역학적, 물리적 parameter와는 상관성이 전혀 표출되지 않는 독립적인 거동을 하고 있다. 포아송비의 함수거동은 감소, 증가 및 자유거동을 표출하고 있다. 감소거동을 나타내는 시료는 전체의 약 70%이상이며 이것은 포아송비의 함수거동 중 절대적으로 우세한 것이다. 포아송비는 독립거동을 하기 때문에 간접적인 방법으로는 추정이 불가능하다. 따라서 설계, 시공 및 감리과정에서 현장암에 대한 실험 결과를 적용하여야 할 것이다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권9호
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• pp.3703-3708
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• 2015

Background: The neutrophil-to-lymphocyte ratio (NLR) is a strong predictor of mortality in patients with colorectal, lung, gastric cancer, pancreatic and metastatic renal cell carcinoma. We here evaluated whether preoperative NLR is an independent prognostic factor for non-metastatic renal cell carcinoma (RCC). Materials and Methods: Data from 327 patients who underwent curative or palliative nephrectomy were evaluated retrospectively. In preoperative blood routine examination, neutrophils and lymphocytes were obtained. The predictive value of NLR for non-metastatic RCC was analyzed. Results: The NLR of 327 patients was $2.72{\pm}2.25$. NLR <1.7 and NLR ${\geq}1.7$ were classified as low and high NLR groups, respectively. Chi-square test showed that the preoperative NLR was significantly correlated with the tumor size (P=0.025), but not with the histological subtype (P=0.095)and the pT stage (P=0.283). Overall survival (OS) and disease-free survival (DFS) were assessed using the Kaplan-Meier method. Effects of NLR on OS (P=0.007) and DFS (P=0.011) were significant. To evaluate the independent prognostic significance of NLR, multivariate COX regression models were applied and identified increased NLR as an independent prognostic factor for OS (P=0.015), and DFS (P=0.019). Conclusions: Regarding patient survival, an increased NLR represented an independent risk factor, which might reflect a higher risk for severe cardiovascular and other comorbidities. An elevated blood NLR may be a biomarker of poor OS and DFS in patients with non-metastatic RCC.