• 한국농공학회논문집
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• 제61권1호
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• pp.21-29
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• 2019

This study analyzed the variability of drought risk based on trend analysis of dry-seasonal dam inflow located in upper river basins. To this, we used areal averaged precipitation and dam inflow of three upper river dams such as Soyang dam, Chungju dam, and Andong dam. We employed Mann-Kendall trend analysis and change point detection method to identify the significant trends and changing point in time series. Our results showed that significant decreasing trends (95% confidence interval) in dry-seasonal runoff rates (= dam inflow/precipitation) in three-dam basins. We investigated potential causes of decreasing runoff rates trends using changes in potential evapotranspiration (PET) and precipitation indices. However, there were no clear relation among changes in runoff rates, PET, and precipitation indices. Runoff rate reduction in the three dams may increase the risk of dam operational management and long-term water resource planning. Therefore, it will be necessary to perform a multilateral analysis to better understand decreasing runoff rates.

• 제어로봇시스템학회논문지
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• 제18권11호
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• pp.997-1004
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• 2012

In enterprise software projects, performance issues have become more critical during recent decades. While developing software products, many performance tests are executed in the earlier development phase against the newly added code pieces to detect possible performance regressions. In our previous research, we introduced the framework to enable automated performance anomaly detection and reduce the analysis overhead for identifying the root causes, and showed Statistical Process Control (SPC) can be successfully applied to anomaly detection. In this paper, we explain the special performance trend in which the existing anomaly detection system can hardly detect the noticeable performance change especially when a performance regression is introduced and recovered again a while later. Within the fixed number of sampling period, the fluctuation gets aggravated and the lower and upper control limit get relaxed so that sometimes the existing system hardly detect the noticeable performance change. To resolve the issue, we apply dynamically tuned sampling window size based on the performance trend, and Fuzzy theory to find an appropriate size of the moving window.

• 대한원격탐사학회지
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• 제33권1호
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• pp.25-35
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• 2017

Spatial downscaling with fine resolution auxiliary variables has been widely applied to predict precipitation at fine resolution from coarse resolution satellite-based precipitation products. The spatial downscaling framework is usually based on the decomposition of precipitation values into trend and residual components. The fine resolution auxiliary variables contribute to the estimation of the trend components. The main focus of this study is on quantitative analysis of impacts of trend component estimates on predictive performance in spatial downscaling. Two regression models were considered to estimate the trend components: multiple linear regression (MLR) and geographically weighted regression (GWR). After estimating the trend components using the two models,residual components were predicted at fine resolution grids using area-to-point kriging. Finally, the sum of the trend and residual components were considered as downscaling results. From the downscaling experiments with time-series Tropical Rainfall Measuring Mission (TRMM) 3B43 precipitation data, MLR-based downscaling showed the similar or even better predictive performance, compared with GWR-based downscaling with very high explanatory power. Despite very high explanatory power of GWR, the relationships quantified from TRMM precipitation data with errors and the auxiliary variables at coarse resolution may exaggerate the errors in the trend components at fine resolution. As a result, the errors attached to the trend estimates greatly affected the predictive performance. These results indicate that any regression model with high explanatory power does not always improve predictive performance due to intrinsic errors of the input coarse resolution data. Thus, it is suggested that the explanatory power of trend estimation models alone cannot be always used for the selection of an optimal model in spatial downscaling with fine resolution auxiliary variables.

• 디지털융복합연구
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• 제20권3호
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• pp.275-281
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• 2022

본 논문은 스타트업의 경영성과(생존과 성장)에 대한 보다 효과적인 이해를 제공하고 향후 스타트업과 관련된 실증적 연구에 적용할 수 있는 방법을 제시하고자 한다. 따라서 본 연구에서는 기업가 정신, 트랜드분석, 정부지원이 경영성과(비재무적 및 재무적)에 미치는 영향을 연구한다. 총 220개의 설문을 수령하였고 불성실한 설문 5개를 제외하고 215개를 채택하였다. 그리하여, 스타트업 관계자가 설문한 215개사를 대상으로 한 통계자료를 토대로 평가했다. 설문 조사는 SPSS 28.0 통계 프로그램을 사용하여 분석하였다. 연구 결과는 가설의 3가지 항목 모두 스타트업의 정부 지원, 기업가 정신, 트랜드분석은 재무 및 비재무의 경영성과의 차이와 상관없이 모두 긍정적인 역할을 한다는 것을 확인하였다.

• 공연문화연구
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• 제37호
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• pp.437-464
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• 2018

본 연구는 공연문화분야의 학문적 정체성과 특성을 파악하고 변화과정을 살펴보기 위해 의미연결망 분석을 활용하여 연구동향을 파악하였다. 이를 위해 우리나라 공연분야 연구의 대표적 학회지인 한국공연문화학회에서 발행하는 <공연문화연구>에 수록된 455편의 논문을 대상으로 공연문화분야의 연구동향과 추세를 분석하였다. 세부연구과제로는 2000년부터 2017년까지 학회지에 수록된 논문명을 대상으로 <고전희곡연구>에서 <공연문화연구>로 제호변경 전후의 연구수요 변화현상을 파악하였다. 다음으로 2005년부터 2017년까지<공연문화연구>의 논문명, 주제어, 초록을 대상으로 <공연문화연구>의 시기별 연구동향을 파악하여 공연문화분야의 변화현상을 파악하고 미래예측을 통한 발전방향을 제시하였다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2002년도 학술대회지
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• pp.456-459
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• 2002

오늘날 건설공사의 효율화를 위한 EVMS(Earned Value Management System)도입의 중요성을 인식하고 많은 연구가 발표되고 있다. 그러나 EVMS를 도입한 공정에 대한 경험부족과 국내 건설의 제도적${\cdot}$환경적 요인으로 인해서, 기술적인 분석이나 사례분석에 대한 관한 연구는 아직 미흡한 실정이다. 본 연구에서는 EVMS를 도입한 공정상에 성과지수(SPI : Schedule Performance Index, CPI : Cost Performance Index)를 산정하여, 여러 통계적 분석방법을 적용해서 프로젝트 관리상에 일정, 비용상의 추세(Trend) 및 문제의 원인을 분석${\cdot}$연구하고자 한다.

• Communications for Statistical Applications and Methods
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• 제7권3호
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• pp.789-798
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• 2000

The mean residual function is the expected remaining life of an item at age x. The problem of trend change in the mean residual life is great interest in the reliability and survival analysis. In this paper, we develop a family of test statistics for testing whether or not the mean residual life changes its trend. The asymptotic normality of the test statistics is established. Monte Carlo simulations are conducted to study the performance of our test statistics.

• Earthquakes and Structures
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• 제25권5호
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• pp.369-383
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• 2023

Seismic resilience (SR) plays a vital role in evaluating and improving performance losses along with saving repair costs of structures from potential earthquakes. To further explore the developments, hotspots, and trend directions of SR, a total of 901 articles are obtained from the Web of Science (WoS) database. CiteSpace software is used to conduct a bibliometric analysis, which indicates an upward trend of publications in SR and explores the relationship of countries, journals, cited references, and keywords based on visual maps and detailed tables. Then, based on the results of the bibliometric analysis, a state-of-the-art review is conducted to further explore the current challenges and trend directions of SR. The trend directions can be divided into five categories: (a) SR assessments of infrastructure structures, (b) multi-hazard quantifications of SR, (c) seismic resilient structures, (d) refining and calibrating analytical models, and (e) multi-criteria decision-making frameworks for sustainability and SR.

• International Journal of Advanced Culture Technology
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• 제8권3호
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• pp.216-222
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• 2020

The purpose of this study was to predict the performance of female weightlifters using time series analysis. Based on this purpose, a time series analysis was used to calculate the performance prediction model for women(58kg) among the domestic women weightlifters who participated in the Olympics. As a result of creating time series data based on 10 years of record and then evaluating the sequential charts of each athlete group, the female athletes' records did not show any seasonality or difference. In addition, after examining the independence of the data through the creation of a time series model, it was shown that the models produced conformed to the criteria for compliance and that there was no difference in the data, but there was a trend. Accordingly, Holt linear trend analysis of the exponential smoothing model was applied. As a result of deriving the prediction model of the athletes through this process, it was found that the women (58kg) who participated in the Olympics continued to improve within the range of 166.11kg to 184.1kg.

• The Journal of Asian Finance, Economics and Business
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• 제7권7호
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• pp.105-112
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• 2020

The study investigates and measures the impact of capital structure, profitability and financial performance on the success of the business organization. Capital structure of the business organization refers to the proportion of external funds and internal funds, i.e., debt and equity. In Saudi Arabia, petrochemicals companies are working on equity, but financial performance reflects negative trend for the period 2004 to 2016. The research is based upon secondary data available on the websites of petrochemicals companies of Saudi Arabia. Financial Ratio variability analysis and Trend Indices of financial ratios (TI_CBI) measure and compare the financial variability and sensitivity of financial ratios of the business organization. Correlation between Trend Indices (TI_CBI) of independent variable and dependent variables are to be calculated to know the impact of changes in debt equity on other dependent variables. The results reveal the unexpected performance of petrochemicals companies due to under-utilization of the resources caused by low demand and lower prices of the products governed by some internal and external factors. The study finds that size, demand, cost of production, profitable streams of products, and low cost capital in external funds are the factors responsible for overall growth development of the petrochemicals industry of Saudi Arabia.