• Journal of Climate Change Research
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• v.6 no.4
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• pp.283-290
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• 2015

This study was carried out a trend analysis for analyzing change of meteorological elements in the main producing areas of Chinese cabbage, radish, pepper, garlic and onion. As meteorological elements, we selected air temperature (maximum, minimum), precipitation and duration of sunshine. We used monthly data of meteorological elements obtained from the main producing areas of vegetables for 30 years from 1981 to 2010. Mann-Kendall test used for significance test of trend and Sen's estimator of slope for computing the variance of meteorological elements. The study results showed that air temperature tended to increase, but duration of sunshine tended to decrease in most regions.

• International Journal of Reliability and Applications
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• v.1 no.2
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• pp.115-121
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• 2000

The trend change in aging properties, such as failure rate and mean residual life, of a life distribution is important to engineers and reliability analysts. In this paper we develop a test statistic for testing whether or not the failure rate changes its trend using censored data. The asymptotic normality of the test statistics is established. We discuss the efficiency values of loss due to censoring.

• The Korean Journal of Applied Statistics
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• v.35 no.3
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• pp.371-384
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• 2022

The fused LASSO signal approximator (FLSA) can be applied to find change points from the data having piecewise constant mean structure. It is well-known that the FLSA is inconsistent in change points detection. This inconsistency is due to a total-variation denoising penalty of the FLSA. ℓ₁ trend filter, one of the popular tools for finding an underlying trend from data, can be used to identify change points of piecewise linear trends. Since the ℓ₁ trend filter applies the sum of absolute values of slope differences, it can be inconsistent for change points recovery as the FLSA. However, there are few studies on the inconsistency of the ℓ₁ trend filtering. In this paper, we demonstrate the inconsistency of the ℓ₁ trend filtering with a numerical study.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.4
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• pp.115-127
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• 2009

Recently, Natural disasters are increasing the damage according to the influence of the abnormal climate and climate change. This study analyzed change characteristic of Design Rainfall according to the different data periods. First, 14 observatories were selected at Meteorological Administration. Second, frequency analysis carried out 5 cases by different data periods. At the results of the frequency analysis, the design rainfall could confirm the increase in most areas of Korea. Also, the change and trend analysis carried out for characteristic analysis by design rainfall and observed rainfall. The change and trend analysis of observed annual maximum rainfall did not appeared, but the change and trend analysis of design rainfall significantly appeared using statistic methods. The result of the change and trend analysis, design rainfall increased in most areas of Korea. Although, it could be the necessity for reestimating defense ability of flood, existing river systems, and new establishment of structure about the change characteristic.

• Journal of the Korea Fashion and Costume Design Association
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• v.15 no.4
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• pp.83-99
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• 2013

This research is a follow-up study about analysis on the many different customer groups and their various culture trend, which intends to realize diverse values depending on the sense. The purpose of this study was to develop direction forecast for the future fashion industry through consideration about the characteristics of contemporary fashion industry by the change of different customer's culture trend. And also try to find solution to survival strategy of fashion fields able to evolve with customer. Change of the customer's cultural trend draws a shift in policy in the 21st fashion industry as follows : 1) mash-up 2) complexation through decentering and blurring 3) invisible and immaterial value oriented 4) expansion of minor small market. Moreover, this shows sociocultural meaning as follows. First is spread of flexible and horizontal relationship through collaborative consumption and collaboration. Second is concentration on floating and indeterminate chance through dismantling of various different fashion categories. Third is formation of the permanent difference by selection and focus. Last is expansion of understanding about cultural-ecology. Customer cultural trend is 'meme' of cultural gene in fashion field, so it intends to co-evolute with customer by continuous change.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1345-1362
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• 2019

Most active queue management algorithms manage network congestion based on the size of the queue but ignore the network environment which makes queue size change. It seriously affects the response speed of the algorithm. In this paper, a new AQM algorithm named CT-AQM (Change Trend-Adaptive Queue Management) is proposed. CT-AQM predicts the change trend of queue size in the soon future based on the change rate of queue size and the network environment, and optimizes its dropping function. Simulation results indicate that CT-AQM scheme has a significant improvement in loss-rate and throughput.

• Journal of Environmental Impact Assessment
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• v.12 no.1
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• pp.45-54
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• 2003

The purpose of this paper is to examine the trend on the change of the cherry blossom flowering time due to the temperature change by selecting regions that have long periods of cherry blossom flowering time data as cases. With the flowering time data, the distribution of cherry blossom flowering time, time series change and change rate of cherry blossom flowering time were analyzed. Also, the correlation between the cherry blossom flowering time and the temperature was analyzed. The flowering of cherry blossom is earlier in metropolitan areas, and in the east coastal region than the west coastal region. The trend on the change of the cherry blossom flowering time is very similar to change the temperature. The change rate of the cherry blossom flowering time is rising up in the whole regions under study, and is relatively high in metropolitan areas. Especially, the cherry blossom flowering time festinated greatly in Pohang that is one of the heavily industrialized cities. From the analysis of correlation analysis between cherry blossom flowering time and temperature elements, the cherry blossom flowering time is highly related with mean temperature of March, which the month is just before the beginning of flowering.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.999-1009
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• 2021

As the frequency and intensity of extreme weather events due to climate change are increasing in recent years, it is very important to evaluate and analyze climate conditions to manage and respond to the negative effects of climate change in advance. In this study, the trends and characteristics of regional climate change were analyzed by calculating the climate indices for the Chungcheong Province. Annual and monthly UNEP-MP, UNEP-PM and MDM indices were calculated using daily data from 1973-2020 collected from 10 synoptic meteorological stations operated by the Korea Meteorological Administration. The normality of climate data was analyzed through the KS test, and the climate change trend was analyzed by applying the Spearman and Pearson methods. The Chungcheongnam-do region had a relatively humid climate than the Chungcheongbuk-do region, and the annual climate indices showed a dry climate trend in Cheongju and Chungju, while the climate of Seosan and Buyeo was becoming humid. Based on the monthly trend change analysis, a humid climate trend was observed in summer and autumn, while a dry climate trend was observed in spring and winter. Comparison of climate indices during the past (2001-2010) and the recent (2011-2020) years showed a higher decrease in the average climate indices during the last 10 years and a gradually drying climate change trend was recorded.

• Atmosphere
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• v.31 no.1
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• pp.101-112
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• 2021

The long-term trend of surface wind speed in Korea is examined for 31 KMA weather stations from 1985 to 2019. Most stations, except Daegwallyeong, have several times of anemometer height changes from tens of centimeters to several meters. To minimize such height change effect on long-term wind trend, the present study adjusts anemometer height in each station to the standard height of 10 m using the power-law wind profile. This adjustment results in non-negligible trend change. For instance, the increasing surface wind speed at Suwon station, which has six times of anemometer height changes in a range of 0.8 m to 20 m, is weakened up to 67% and becomes statistically insignificant. Likewise, the decreasing trend at Andong station, with three times of anemometer height changes in a range of 10 m to 15.5 m, is weakened up to 66%. A similar weakening in long-term trend is observed in most stations regardless of positive and negative trends. However, due to the cancellation between weakened negative trends and weakened positive trends, the station-averaged wind speed trend in Korea does not change much. This result suggests that anemometer height adjustment is crucial for evaluating local wind speed trend but its impact on nation-wide wind speed trend is rather minor.

• Journal of Applied Reliability
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• v.9 no.2
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• pp.121-130
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• 2009

The power law process model the Rate of occurrence of failures(ROCOF) with monotonic trend during the operating time. However, the power law process is inappropriate when a non-monotonic trend in the failure data is observed. In this paper we deals with the reliability modeling of the failure process of large and complex repairable system whose rate of occurrence of failures shows the non-monotonic trend. We suggest a sectional model and a change-point test based on the Schwarz information criterion(SIC) to describe the non-monotonic trend. Maximum likelihood is also suggested to estimate parameters of sectional model. The suggested methods are applied to field data from an repairable system.