• Journal of Korea Water Resources Association
• /
• v.47 no.7
• /
• pp.643-656
• /
• 2014

The homogeneity analysis of temporal (monthly, seasonal and annual) climate aridity index trend was accomplished for 43 climate measurement stations in South Korea. Furthermore, 43 stations were grouped into 9 different regions and the temporal and regional homogeneity of climate aridity index trends in each region and entire 9 regions were analyzed. For analysis, monthly, seasonal and annual climate aridity indexes of 43 study stations were estimated using precipitation and potential evapotranspiration calculated from FAO Penman-Monteith equation. The Mann-Kendall statistical test for significant trend was accomplished using the estimated climate aridity indexes and the results of trend test (Z scores) were used to analyze the temporal and regional homogeneity of climate aridity index trends. The study results showed the temporal and regional homogeneity of climate aridity index trends for individual and entire 9 regions. However, the homogeneity and the extent of aridity index trend showed different patterns temporally and regionally.

• Journal of Wetlands Research
• /
• v.6 no.4
• /
• pp.35-43
• /
• 2004

The non-parametric Mann-Kendall(MK) statistical test has been widely used to assess the significance of trend in hydrologic time series. The test requires sample data should be serially independent. If sample data is serially correlated, the presence of serial correlation in a time series will affect the test ability for trend analysis. So, we would like to use the modified MK test which uses the effective sample size(ESS) to eliminate the effect of serial correlation in a series. This study investigates the ability of ESS to eliminate the influence of serial correlation of MK test by Monte Carlo simulation and by real series. As the results, MK test shows the increase of trend rate as the serial correlation is increased but the modified MK test shows ESS can eliminate the serial correlation for trend analysis. Therefore we confirmed the modified MK test is a very useful tool for trend analysis.

• Journal of the Korea Convergence Society
• /
• v.10 no.2
• /
• pp.113-124
• /
• 2019

This is a convergence study to investigate the relationship between cereal intake level and food and nutrient intake in 218 Chinese middle aged women aged 40 to 65 years. Data were analyzed by ${\chi}^2$ test, ANOVA, correlation analysis and Jonckheere-Terpstra trend test using SPSS 22.0 program. The results of the study were as follows. The higher the level of cereal intake in the subjects, the lower were the rate of breakfast fasting (p for trend=0.000), overeating (p for trend=0.019), and eating out (p for trend=0.003). The intake of root and tuber crops(p for trend=0.008), meat(p for trend=0.043), pulses(p for trend=0.020), and light colored vegetables(p for trend=0.015) per 1,000 kcal of energy increased when the level of cereal intake was 6 to 9 units. Therefore, it is necessary to discuss and study for continuous education and improvement through the feedback so that the middle-aged women can take the cereal appropriately.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.12 no.6
• /
• pp.1-6
• /
• 2008

This work proposes a fuzzy trend monitoring method for the fault detection of a gas turbine engine through analyzing measured performance data trend. The proposed trend monitoring technique can diagnose the engine status by monitoring major engine measured parameters such as fuel flow rate, exhaust gas temperature, rotor rotational speed and vibration, and then analyzing their time deppendent changes. In order to perform this, firstly the measured engine performance data variation is formulated using Linear Regression, and then faults are isolated and identified using fuzzy logic.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.8
• /
• pp.1811-1817
• /
• 2015

This paper analyzes domestic research trend on information security, compares its results with international trends, and studies future directions we should have on national level. This research is a successor of the work for analysis of global research trend on information security. Therefore we select the same analysis method to compare domestic and international research trends exactly. To do this, we use domestic papers presented or published from 2001 to 2014, measure temporal relationship between technologies related to information security, analyze domestic research trends, and compare the results. Finally we will suggest our future direction through considering international future markets of technologies.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.15 no.5
• /
• pp.423-432
• /
• 2022

This paper analyzes a total of 10,599 papers related to COVID-19 from January 2020 to July 2022 collected from the KCI site using LDA topic modeling so that academic researchers can understand the overall research trend. The results of LDA topic modeling are analyzed by major research categories so that academic researchers can easily figure out topics in their research fields. Then, the detailed research category information in which a lot of research is done by topic is analyzed. It is very important for academic researchers to understand the trend of research topics over time. Therefore, in this paper, the trend of topics is analyzed and presented using time series decomposition.

• International Area Studies Review
• /
• v.21 no.4
• /
• pp.159-172
• /
• 2017

In a typical trend-cycle decomposition of GDP, the trend component is usually assumed to follow a random walk process. This paper considers an ARIMA trend and assesses the validity of the ARIMA trend model. I construct univariate and bivariate unobserved-components(UC) models, allowing the ARIMA trend. Estimation results using U.S. data are favorable to the ARIMA trend models. I, also, compare the forecasting performance of the UC models. Dynamic pseudo-out-of-sample forecasting exercises are implemented with recursive estimations. I find that the bivariate model outperforms the univariate model, the smoothed estimates of trend and cycle components deliver smaller forecasting errors compared to the filtered estimates, and, most importantly, allowing for the ARIMA trend can lead to statistically significant gains in forecast accuracy, providing support for the ARIMA trend model. It is worthy of notice that trend shocks play the main source of the output fluctuation if the ARIMA trend is allowed in the UC model.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.11
• /
• pp.7957-7963
• /
• 2015

R&D trend for Auxiliary Power Supply(APU) of electric vehicle can be well understood by analyzing patents at home and abroad. Based on this trend analysis, domestic technology development direction is proposed. To get technique trend, patents of Korea, Japan, Europe and America published until February of 2014 are analyzed by WIPS DB. First, power converter and transformer two big category are classified. Power converter can be classified into resonant DC to DC converter and resonant Half bridge inverter; transformer can be classified into high frequency transformer, ferrite transformer and matching transformer. By analyzing R&D trend of different counties, companies and years, specific technology needed to be developed and trend of technology can be accurately grasped.

• Journal of the Korean Society for information Management
• /
• v.27 no.4
• /
• pp.309-328
• /
• 2010

This study has analyzed the trend of the quantitative research by analyzing domestic dissertations on information literacy that were published since 2000. The procedures, regulations, and descriptive elements of the quantitative study were compared and analyzed for this study. In addition, the study used 5 variables and criterions to measure these items. Based on the calculations, the study has examined the general characteristics of the thesis, research method, sampling method and sampling population of the dissertations. The study has also analyzed the trend of the measurement variables by categorizing the characteristics by published year and majors. Furthermore, the study has also presented the trend of the usage of statistic analysis method on research purpose by classifying the method into each purpose.

• Proceedings of the Korea Society of Design Studies Conference
• /
• 2004.10a
• /
• pp.136-137
• /
• 2004