• The Journal of Information Systems
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• v.27 no.3
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• pp.43-62
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• 2018

Purpose Since the Bitcoin, which was the first virtual currency, was made at 2009, almost 1,000 virtual currencies appeared onstage in the world. Even though virtual currencies have the function of money as a medium of exchange or contract, any of those has not yet entered the commercialization stage. Instead, some of the virtual currencies show the nature of investment assets. In the case of virtual money investment, users tend to use all the information of the world because information transfer is very easy and capital movement is almost free between different countries. In addition, as the transaction sizes of virtual currencies increase, a virtual currency price is no longer independent and is likely to be affected by the prices of other virtual currencies. Therefore, it is necessary to understand the influence among virtual currency markets, which helps successful implementation of investment strategies. Design/methodology/approach This study focuses on the investment product function of virtual money and conducts the analysis using the time series model used in the financial and economic areas. In this paper, we try to analyze the return and volatility transfer effect of virtual money markets through GJR-GARCH model. Findings This study is expected to find out whether we can make market forecasts through reflecting changes in other markets. In addition, we can reduce the trial and error of user decision making by using the information on the yield and volatility transition effect derived from the research results, and it is expected to reduce the opportunity cost of users.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.61-70
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• 2003

The behaviour of an earth and rock-fill dam is complicated due to reservoir water and various materials in zoned dams. Different materials with a wide range of permeability and seasonal variation of reservoir water result in the time dependent post-constructional behaviour. In aged dams it is often required to control water level to keep the dams safe. In this case information on the post-constructional dam behaviour is important. However, present geotechnical knowledge does not fully support the occasion. In this study the post-constructional behaviour of a dam is investigated using coupled finite element models for series of idealized water reservoir cases: impoundment, draw down, seasonal fluctuation with different rising and falling speeds. Numerical results were analysed in respect of geotechnical parameters such as load transfer, hydraulic fracturing potential and stress paths. It is shown that the control of water level is an important factor while operating dams.

• Journal of Environmental Science International
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• v.21 no.4
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• pp.517-533
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• 2012

This study calculated wind speed at the height of 10 m using a disaster prediction model(Florida Public Hurricane Loss Model, FPHLM) that was developed and used in the United States. Using its distributions, a usable information of surface wind was produced for the purpose of disaster prevention when the typhoon attack. The advanced research version of the WRF (Weather Research and Forecasting) was used in this study, and two domains focusing on South Korea were determined through two-way nesting. A horizontal time series and vertical profile analysis were carried out to examine whether the model provided a resonable simulation, and the meteorological factors, including potential temperature, generally showed the similar distribution with observational data. We determined through comparison of observations that data taken at 700 hPa and used as input data to calculate wind speed at the height of 10 m for the actual terrain was suitable for the simulation. Using these results, the wind speed at the height of 10 m for the actual terrain was calculated and its distributions were shown. Thus, a stronger wind occurred in coastal areas compared to inland areas showing that coastal areas are more vulnerable to strong winds.

• Journal of Environmental Science International
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• v.29 no.10
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• pp.1003-1010
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• 2020

In this study, the necessity for a village unit Automatic Weather System (AWS) was suggested to obtain correct agricultural weather information by comparing the data of AWS of the weather station with the data of AWS installed in agricultural villages 7 km away. The comparison sites are Hyogyo-ri and Hongseong weather station. The seasonal and monthly averaged and cumulative values of data were calculated and compared. The annual time series and correlation was analyzed to determine the tendency of variation in AWS data. The average values of temperature, relative humidity and wind speed were not much different in comparison with each season. The difference in precipitation was ranged from 13.2 to 91.1 mm. The difference in monthly precipitation ranged from 1.2 to 75.4 mm. The correlation coefficient between temperature, humidity and wind speed was ranged from 0.81 to 0.99 and it of temperature was the highest. The correlation coefficient of precipitation was 0.63 and the lowest among the observed elements. Through this study, precipitation at the weather station and village unit area showed the low correlation and the difference for a quantitative comparison, while the elements excluding precipitation showed the high correlation and the similar annual variation pattern.

• Atmosphere
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• v.16 no.4
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• pp.333-342
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• 2006

The long-term trends of global solar irradiance, air temperature, specific humidity and cloudiness measured at King Sejong station, Antarctica, during the period of 1988-2004, have been investigated. A statistically insignificant decrease, -0.21 $Wm^{-2}yr^{-1}$ (-0.26 %$yr^{-1}$, P<0.5) in global solar irradiance was found in an analysis from the time series of the monthly mean values, except for the increasing trends only in two months of January and June. The trends in irradiance are directly and inversely associated with the cloudiness trends in annual and monthly means. The trends in surface air temperature show a slight warming, $0.03^{\circ}Cyr^{-1}$ (1.88 %$yr^{-1}$, P<0.5) on the annual average, with cooling trend in the summer months and the warming in the winter. The exact relationship, if any, between the irradiance and temperature trends is not known. No significant tendency was found in specific humidity for the same periods. Recent (1996-2004) erythermal ultraviolet irradiance shows decreasing trend in annual mean, -0.15 $mWm^{-2}yr^{-1}$ (-1.18 %$yr^{-1}$, P<0.1) which is about five times the trends of global solar irradiance. The ratio of erythermal ultraviolet to global solar irradiance shows remarkable seasonal variations with annual mean value of 0.01 % and a peak in October and November, showing the increase of ultraviolet irradiance resulting from the Antarctic ozone hole. The sensitivity of global solar irradiance to the change in cloudiness is roughly $13%oktas^{-1}$ which is about twice of the value at the South Pole due to the difference in the average surface reflectance between the two stations. Much more sensitive values of $59%oktas^{-1}$ was found for erythermal UV irradiance than for the global solar irradiance.

• Atmosphere
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• v.24 no.1
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• pp.29-38
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• 2014

A characteristic of snowfall and minimum temperature variability in South Korea with respect to the variability of Arctic Oscillation (AO) was investigated. The climatic snowfall regions of South Korea based on daily new fresh snowfall data of 59 Korea Meteorological Administration (KMA) stations data corresponding to the sign of AO index during December to February 1979~2011 were classified. Especially, the differences between snowfalls of eastern regions and that of western regions in South Korea were seen by each mean 1000hPa geopotential height fields, which is one of physical structure, for the selected cases over the East Asia including the Korean Peninsula. Daily minimum temperature variability of 59 KMA station data and daily AO index during the same period were investigated using Cyclo-stationary empirical orthogonal function (CSEOF) analysis. The first CSEOF of wintertime daily AO index and that of minimum temperature of 59 KMA stations explain 33% and 66% of total variability, respectively. Correlation between principal component time series corresponding to the first CSEOF of AO index and that of temperature at the period of 1990s is over about -0.7 when that of AO index leads about 40 days.

• Atmosphere
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• v.26 no.3
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• pp.373-386
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• 2016

The future variability of Wind Energy Density (WED) over the Korean Peninsula under RCP climate change scenario is projected using ensemble analysis. As for the projection of the future WED, changes between the historical period (1981~2005) and the future projection (2021~2050) are examined by analyzing annual and seasonal mean, and Coefficient of Variation (CV) of WED. The annual mean of WED in the future is expected to decrease compared to the past ones in RCP 4.5 and RCP 8.5 respectively. However, the CV is expected to increase in RCP 8.5. WEDs in spring and summer are expected to increase in both scenarios RCP 4.5 and RCP 8.5. In particular, it is predicted that the variation of CV for WED in winter is larger than other seasons. The time series of WED for three major wind farms in Korea exhibit a decrease trend over the future period (2021~2050) in Gochang for autumn, in Daegwanryeong for spring, and in Jeju for autumn. Through analyses of the relationship between changes in wind energy and pressure gradients, the fact that changes in pressure gradients would affect changes in WED is identified. Our results can be used as a background data for devising a plan to develop and operate wind farm over the Korean Peninsula.

• Archives of Plastic Surgery
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• v.40 no.4
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• pp.374-379
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• 2013

Background To date, various types of acellular dermal matrix (ADM) have been developed for clinical use. AlloDerm is the most familiar type of ADM to most surgeons in breast reconstruction. It is prepared by freeze-drying. CG CryoDerm is the first form of ADM that requires no drying process. Therefore, theoretically, it has a higher degree of preservation of the dermal structures than AlloDerm. We conducted this study to compare the clinical course and postoperative outcomes of patients who underwent direct-to-implant breast reconstructions using AlloDerm and those who did using CG CryoDerm. Methods We performed a retrospective analysis of the medical records in a consecutive series of 50 patients who underwent direct-to-implant breast reconstruction using AlloDerm (n=31) or CryoDerm (n=19). We then compared the clinical course and postoperative outcomes of the two groups based on the overall incidence of complications and the duration of drainage. Results The mean follow-up period was 16 months. There were no significant differences in the overall incidence of complications (seroma, infection, skin flap necrosis, capsular contracture, and implant loss) between the two groups. Nor was there any significant difference in the duration of drainage. Conclusions CG CryoDerm has the merits of short preparation time and easy handling during surgery. Our results indicate that CG CryoDerm might be an alternative allograft material to AlloDerm in direct-to-implant breast reconstruction.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7991-7995
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• 2015

Background: To identify the epidemiological characteristics of colorectal cancer mortality in China during the period of 1991-2011, and forecast the future five-year trend. Materials and Methods: Mortality data for colorectal cancer in China from 1991 to 2011 was used to describe epidemiological characteristics in terms of age group, gender, and rural/urban residence. Trend surface analysis was performed to analyze the geographical distribution of colorectal cancer. Four models including curve estimation, time series modeling, gray modeling and joinpoint regression were applied to forecast the trends for the future five years. Results: Since 1991 the colorectal cancer mortality rate increased yearly, and our results showed that the trend would continue to increase in the ensuing 5 years. The mortality rate in males was higher than that of females and the rate in urban areas was higher than in rural areas. The mortality rate was relatively low for individuals less than 60 years of age, but increased dramatically afterwards. People living in the northeastern China provinces or in eastern China had a higher mortality rate for colorectal cancer than those living in middle or western China provinces. Conclusions: The steadily increasing mortality of colorectal cancer in China will become a substantial public health burden in the foreseeable future. For this increasing trend to be controlled, further efforts should concentrate on educating the general public to increase prevention and early detection by screening. More effective prevention and management strategies are needed in higher mortality areas (Eastern parts of China) and high-risk populations (60+ years old).

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.4
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• pp.1783-1789
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• 2014

Background: The EMSY gene encodes a BRCA2-binding partner protein that represses the DNA repair function of BRCA2 in non-hereditary breast cancer. Although amplification of EMSY gene has been proposed to have prognostic value in breast cancer, no data have been available concerning EMSY tissue expression patterns and its associations with clinicopathological features. Materials and Methods: In the current study, we examined the expression and localization pattern of EMSY protein by immunohistochemistry and assessed its prognostic value in a well-characterized series of 116 unselected breast carcinomas with a mean follow up of 47 months using tissue microarray technique. Results: Immunohistochemical expression of EMSY protein was detected in 76% of primary breast tumors, localized in nuclear (18%), cytoplasmic (35%) or both cytoplasmic and nuclear sites (23%). Univariate analysis revealed a significant positive association between EMSY expression and lymph node metastasis (p value=0.045) and larger tumor size (p value=0.027), as well as a non-significant relation with increased risk of recurrence (p value=0.088), whereas no association with patients' survival (log rank test, p value=0.482), tumor grade or type was observed. Conclusions: Herein, we demonstrated for the first time the immunostaining pattern of EMSY protein in breast tumors. Our data imply that EMSY protein may have impact on clinicipathological parameters and could be considered as a potential target for breast cancer treatment.