• Journal of Electrical Engineering and Technology
• /
• 제9권3호
• /
• pp.782-788
• /
• 2014

Wind power generation has been viewed as a promising renewable energy to meet challenge of climate change. However, wind power is susceptible to climate change because previous investigation shows there are declining trends of the land surface wind speeds over middle and lower latitudes. Since long term variation trends is notably different from inter-annual random variation and could have notable impact on wind farm from planning perspective, observed meteorological data of Taiwan is investigated to find out long term variation trends of wind speed and its impact on wind power generation. It is discovered that wind speed in majority of stations in west coast of Taiwan have ascending trends while that of all investigated stations in east coast have descending trends. Since east of Taiwan is not suitable for wind power development for its higher likelihood suffering Typhoons and most of established wind farm locate in west coast of Taiwan, it is speculated that long term variation trend of wind do not have notable negative impact on wind power generation in Taiwan.

• Communications for Statistical Applications and Methods
• /
• 제30권2호
• /
• pp.149-162
• /
• 2023

The ℓ₁-trend filtering method is one of the most widely used methods for extracting underlying trends from noisy observations. Contrary to the Hodrick-Prescott filtering, the ℓ₁-trend filtering gives piecewise linear trends. One of the advantages of the ℓ₁-trend filtering is that it can be used for identifying change points in piecewise linear trends. However, since the ℓ₁-trend filtering employs total variation as a penalty term, estimated piecewise linear trends tend to be biased. In this study, we demonstrate the biasedness of the ℓ₁-trend filtering in trend level estimation and propose a two-stage bias-reduction procedure. The newly suggested estimator is based on the estimated change points of the ℓ₁-trend filtering. Numerical examples illustrate that the proposed method yields less biased estimates for piecewise linear trends.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 A
• /
• pp.165-167
• /
• 2004

End-user electric power consumption trends shows various load curves dependant on industry, contract, season, day and time. Analysis of end-user electric power consumption trends has a key role to efficiently meet electricity demand. There are several factors of change in electricity demand such as the change of weather, international conflict, and industrial trends during summer. This paper has analyzed the analysis the end-user electric power consumption trends using the load curve during international conflict. We observed that international conflict decreased electric demand by $5.4\%$. This increase is not significant, and therefore we conclude that the international conflict has not greatly affected Korea's electricity demands. This paper provides useful information so as to mon: efficiently perform demand side management.

• 대기
• /
• 제17권2호
• /
• pp.171-183
• /
• 2007

Trends of daily maximum and minimum temperatures in major cities of South Korea (Seoul, Busan, Incheon, Daegu, and Ulsan) during the past 40 years (1961-2000) were investigated. Temperature records for the Chupungryeong station were compared with those of the large cities because of the rural environment of the station. There were distinct warming trends at all stations, although the warming rates depend on each station's local climate and environment. The warming rates in Korea are much greater than the global warming trends, by a factor of 3 to 4. The most increasing rate in daily maximum temperature was at Busan with $0.43^{\circ}C$ per decade, the most increasing rate in daily minimum temperature was at Daegu with $0.44^{\circ}C$ per decade. In general, the warming trends of the cities were most pronounced in winter season with an increasing rate of $0.5^{\circ}C$/decade at least. Diurnal temperature range shows positive or negative trends according to the regional climate and environmental change. The frequency distribution of the daily temperatures for the past 40 years at Seoul and Chupungryeong shows that there have been reductions in cold day frequencies at both stations. The results imply that the impacts on human health might be positive in winter and adverse in summer if the regional warming scenario by the current regional climate model reflects future climate change in Korea.

• 한국의류산업학회지
• /
• 제19권1호
• /
• pp.49-60
• /
• 2017

In this study, change trends and specific times for change in body size were sought to be identified by using manual measurements for Korean adult women at 20 to 89 of age, along with examinations of change trends and specific times of change in body shape based on body index values. The examinations of means, deviations, and variation coefficients revealed that there was a tendency of most height related measures to decrease. In addition, combined with decrease in height, growth in weight led to increased BMI, thus resulting in increase in measures of circumference, thickness, and breadth in the torso area. The BMI trends showed that with increasing age, BMI increased, reaching the peak between the ages of 55 and 59 and then decreasing from 64 of age, with the steepest increase in BMI at ages from 50 to 54. The examination of differences in the body flatness ratio for different parts of body found that with increasing age the ratio decreased, indicating a tendency for gradual change to round body shapes. The analysis of 3D body shape found that there were more back-bends and lowered shoulder levels with age, accompanied with a tendency for more bended legs and more inclined-forward necks. The key trends in changes in body measurements by age and detailed estimates of 3D standard body shape drawn out from this study are expected to significantly contribute to establishing a basic database for generating patterns reflecting age features of Korean adult females.

• 전자통신동향분석
• /
• 제37권4호
• /
• pp.1-10
• /
• 2022

As the response to climate change becomes a more pressing global issue, so do expectations for climate change in the green information and communication technology (ICT) industry and the possibility of solving environmental problems through ICT. However, because the green ICT industry is still in its early stages, there is little research on it. Understanding the startup ecosystem in the industry is helpful for recognizing innovation trends in emerging technologies such as green ICT. In this regard, this paper investigates the current state and characteristics of the green ICT ecosystem and presents implications based on an examination of startup venture capital investment trends and submarket identification in the green ICT industry as emphasized by the carbon neutrality paradigm shift. The analysis included 4,807 companies and 3,990 funding records, as well as exploratory data analysis and "k-means" clustering techniques.

• 한국철도학회논문집
• /
• 제9권6호
• /
• pp.705-710
• /
• 2006

The railway has been developed largely by the characteristic factors of the railway through change of the society and culture. The railway trends has been changing from instinctive methods to settle the mass transport of the early days, to sensitive methods to pursue the railway culture centering around human being. As dividing by period according to the changes of railway trends into the external nation, there are to analyze the development history of the railway design. Accordingly each nation (United Kingdom, Germany, France, Japan) and the style's change, to confirm the changes into the design applied in society and culture needs, and to analyze by a year in changes of the environment and the railway history from the 1800's to 2005, so there contribute in the development of railway design to present the paradigm of the future railway by analyzing the trend according to the changes of railway design and the life environment in this paper.

• 대한토목학회논문집
• /
• 제44권4호
• /
• pp.465-482
• /
• 2024

The global use of groundwater in coastal areas has increased. Events such as seawater intrusion (SWI) are expected to increase along with the acceleration of natural disasters owing to environmental changes such as climate change, resulting in large-scale damage worldwide. Current trends in the research of coastal groundwater and related natural disasters include testing and verifying technologies using major case studies from individual countries. We identified global research trends in coastal groundwater, related these trends to changing environments and climate, and confirmed the qualitative and quantitative growth of these studies. This study describes the theoretical background and techniques for coastal groundwater analysis and details regional-scale SWI indicators based on analytical and numerical studies. This review highlights recent technologies that consider uncertainty and promotes discussions on field data obtained using new technologies. Finally, the research findings and trends for a regional coastal aquifer in Korea are discussed to describe recent SWI approaches for groundwater resources.

• 한국환경과학회지
• /
• 제17권8호
• /
• pp.907-918
• /
• 2008

In order to monitor the impact of high temperature which is seen frequently with climate change, we investigated the monthly change in globe temperature, air temperature, mean radiant temperature and effective radiant heat flow, because the four well reflect thermal radiation from bio-meteorological aspect. Both globe temperature and air temperature showed an increasing trend every month. Compared to air temperature, globe temperature had a wider range of temperature change and was more influenced by meteorological element such as precipitation. Diurnal trends of air temperature, globe temperature and the difference between their temperature had the lowest value before the sunrise and the highest around $1300{\sim}1500$ LST, showing the typical diurnal trends. Globe temperature and the difference between their temperature had a sharp increase around $1000{\sim}1100$ LST, maintained high value until 1700 LST and then reclined, though varied by month. The difference between globe temperature and air temperature was highly dependent on the amount of precipitation and clouds. The duration in which globe temperature was higher than air temperature was the lowest in July. Therefore the amount of precipitation was the most affecting, followed by the amount of clouds and wind. In order to find out the diurnal trends of temperature in city center and city outskirts, we assumed the roof of a concrete build ing as a city center, and the grass-covered observatory of the Gimhae International Airport as city outskirts. The diurnal trends of temperature in the two sites showed a strong correlation. The highest and lowest temperature also had the same trend.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.1115-1122
• /
• 2006

The railway design trends has been developed by the change of the society and culture through the consideration of the history of railway. The railway design trends is as the vehicles in the external form of railways, instantly means to plan and create the value added something like the form of the exterior design. The railway design has been changing form instinctive methods to settle the mass transport of the early days, to sensitive methods to pursue the railway culture centering around human being. As dividing by the style's change of railway in image scale aspects between 1800's and 2005 according to the life environment into the external nation, there are big differences so that is to study the development history of the railway design accordingly each nation (United Kingdom, Germany, France, Japan) and the style's change, to confirm into the design applied in society and culture needs, and to analyze by a year in changes of the environment and the railway design history. This paper analyzed railway introduced as railway models by top 4 nation (United Kingdom, Germany, France, Japan) in the past years(1800-2005) for their railway design trends by image scale positioning.