• Title, Summary, Keyword: mean annual frequency

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Estimation of Design Flood by the Determination of Best Fitting Order for LH-Moments (LH-모멘트의 차수에 따른 설계홍수량 추정)

  • Maeng, Sung-Jin;Lee, Soon-Hyuk
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.233-236
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    • 2002
  • This study was conducted to estimate the design flood by the determination of best fitting order for LH-moments of the annual maximum series at fifteen watersheds. Parameters of GEV distribution and flood flows of return period n years were derived by the methods of L, L1, L2, L3 and L4-moments. Frequency analysis of flood flow data generated by Monte Carlo simulation was performed by the methods of L, L1, L2, L3 and L4-moments using GEV distribution. Relative Root Mean Square Error (RRMSE), Relative Bias (RBIAS) and Relative Efficiency (RE) using methods of L, L1, L2, L3 and L4-moments for GEV distribution were computed and compared with those resulting from Monte Carlo simulation. At almost all of the watersheds, the more the order of LH-moments and the return periods increased, the more RE became, while the less RRMSE and RBIAS became. Consequently, design floods for the applied watersheds were derived by the methods of L3 and L4-moments among LH-moments in view of high confidence efficiency.

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Computation of Areal Reduction Factor and its Regional Variability

  • Kim, Won;Yoon, Kang-Hoon
    • Korean Journal of Hydrosciences
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    • v.4
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    • pp.105-116
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    • 1993
  • Areal Reduction Factor(ARF) has been developed and used to convert point Rainfall intensity-Duration-Frequency(I-D-F) to areal I-D-F in many countries. In Korea, though ARF was estimated in Han river basin by several researchers, it has some limitations to apply to other regions due to low denisity of rainfall gauging station and shortage of data. In this study ARF has been developed in area of relatively high density of rainfall gauging station, i.e., Pyungchang river(Han river), Wi stream(Nakdong river), and Bochung stream(Guem river) basin by geographically fixed-area method. And coefficient of variation of mean annual precipitation was presented to use ARE in other areas and its applicability was analyzed.

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A Basic Study on Development of Residents Emotion Index in Apartment Community (아파트 커뮤니티에서의 거주자 감정지표 개발에 관한 기초 연구)

  • Park, Ji-Hye;Cho, Sung-Heui
    • Proceeding of Spring/Autumn Annual Conference of KHA
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    • pp.247-250
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    • 2011
  • The purpose of this study suggests the emotion of residents as indexes in Korean housing environment for providing a fundamental guideline for precise dwelling social science and indicating the view for understanding of residents in korean housing culture in korea. So this paper explores the role of residents emotion indexes in housing environment and community. For this study, survey and depth-interview methods were used for data collection. The subjects were 514 housewives living in apartments. The statistical methods for data analysis were frequency, mean, multiple linear regression and logistic regression analysis using the SPSS 18.0 program The major findings are as follows: 1)Pride of neighborhood, pride of apartment complex and sense of superiority were important factors for residental satisfaction. 2)Conspicuous image of neighbors and active contact with neighbors were import factors for their neighborship in the apartment complex. The results develop the housing environment evaluation indexes in community through the contextual understanding of space emotion society.

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Consumption Expenditure Patterns and Family Life Cycle (도시 근로자가계의 가족생활주기별 소비지출 분석)

  • 노윤주;이연숙
    • Korean Family Resource Management Association
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    • v.1 no.1
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    • pp.27-42
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    • 1997
  • The purpose of this study is to analyze consumption expenditure patterns over family life cycle. The data used in the study is the 1994 Survey data from Annual Report on the Family Income and Expenditure Survey. The study sample included 26,980 salary and wage earners’ households living in cities. The family life cycle was classified into six stages and items of expenditure were classified into 12 categories. Frequency distribution, mean, one-way ANOVA, Scheff test, and regression analysis were used to analyze the data. The major findings of this study are as follows : First, the average consumption propensity differs among family life cycle. Second, the amount and budget share of consumption expenditure for each expenditure category differ significantly among family life cycle in all expenditure categories. Third, family life cycle is found to be a significant factor on expenditure of food and education, and also on budget share of education.

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An Empirical Research on Relation between FDI and Technology Diffusion: Using Nonstationary Panel Data (외국인 직접투자의 기술확산 효과에 대한 실증분석 : 비안정적 패널자료를 이용하여)

  • Kim Hong-Kee;Kim Jong-Woon
    • Journal of Korea Technology Innovation Society
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    • v.8 no.3
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    • pp.1225-1249
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    • 2005
  • This study aims at investigating whether foreign direct investment plays a role as a channel of international technology diffusion. We used the annual panel data from 1980 to 2002. The nonstationary panel techniques, in particular group mean panel FMOLS(fully modified OLS) was exploited as an empirical methodology in order to tackle the heterogeneity between members and low frequency. The empirical results show that inflow direct investments lead to an increase in total factor productivity and economic growth. Also outflow direct investments contribute to an higher total factor productivity and economic growth. These results confirms that both inflow and outflow direct investments are important channels for international technology diffusion or spillover.

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Characteristics of the surface ozone concentration on the occurrence of air mass thunderstorm (기단성 뇌우 발생시 지표오존농도의 변화 특성)

  • 전병일
    • Journal of Environmental Science International
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    • v.12 no.4
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    • pp.419-426
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    • 2003
  • This study was performed to research ozone concentration related to airmass thunderstorm using 12 years meteorological data(1990~2001) at Busan. The occurrence frequency of thunderstorm during 12 years was 156 days(annual mean 13days). The airmass thunderstorm frequency was 14 days, most of those occurrence at summertime(59%). In case August 4, 1996, increase of ozone concentration was simultaneous with the decrease of temperature and increase of relative humidity, In case July 23, 1997, ozone concentration of western site at Busan increased, while its of eastern site decreased as airmass thunderstorm occurred(about 1500LST). It is supposed that these ozone increases are the effect of ozone rich air that is brought down by cumulus downdrafts from height levels where the ozone mixing ratio is larger. Thunderstorms can cause downward transport of ozone from the reservoir layer in the upper troposphere into planeta교 boundary layer(PBL). This complex interaction of source and sink processes can result in large variability fer vertical and horizontal ozone distributions. Thus a variety of meteorological precesses can act to enhance vertical mixing between the earth's surface and the atmospheric in the manner described fer thunderstorm.

Characteristics of wintertime Asian Dust occurrence at Busan (부산지역의 겨울철 황사 발생 특성)

  • Jeon, Byung-Il
    • Journal of Environmental Impact Assessment
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    • v.21 no.4
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    • pp.581-591
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    • 2012
  • The purpose of this study was to analyze the characteristics of fine particles concentration and meteorological parameters, and long range transport of wintertime Asian dust at Busan. Also we studied occurrence frequency and tendency of wintertime Asian dust from 1961 to 2010 in Korea. Asian dust occurred most frequently in the spring, the next to winter in Korea. Wintertime Asian dust is steadily increasing recently. Asian dust in Busan was the most occurred in 2001 with 21 days, followed by 12 days in 2002, and 10 days in 2006. The annual mean frequency during the past 12 years(1999~2010) was 7.5 days, and it was two times more than that during the past 50 years(3.8 days). Wintertime Asian dust in Busan has occurred 6 episodes since 2008, and it all occurred in December except for 20 Feb. 2009. The highest concentration of wintertime Asian dust was recorded mostly at Hakjangdong and Jangrimdong which are industrial area. Maintenance time of Asian dust at Busan was from 1hr 30min to 9hr 20min, it was shorter than in the spring. It took from 10 to 15 hours move to Busan after Asian dust was first detected in Korea. Wintertime Asian dust originated from Gobi desert in Mongolia and inner Mongolia near China, except for 9 Dec. 2008 at Busan.

A Hydrological Study on Rainfall Frequency Atlas in Korea (한국 확률강우량도 작성을 위한 수문학적 연구)

  • 이원환
    • Water for future
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    • v.10 no.1
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    • pp.39-51
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    • 1977
  • The purpose of this study is to make "The Rainfall Frequency Atlas in Korea" by the analytical method with new hydrological concepts. In this study, all of the rainfall datas in Korea was used for surveying of the basic data, and so we can get 103 sites for annual rainfall data and 100 sites for the max. in a day that are suitable to the purpose of the study. The above data groups are possible to estimate the normal standard period by the moving average method with $\pm$5% of significance level of variance ratio between the max. and min. moving average and arithmetic mean, but it may be impossible to study until 1990's for the short duration under 18-hr because the sites, having the short duration data, are only 12. The results of this study are as follows; 1. The normal standard period estimated by the moving average method is 20 year with $\pm$5% of significance level of variance ratio, and 30 year with$\pm$2-3%. 2. For the annual and max. rainfall in a day, it is possible to make the rainfall frequency atlas with 30normal standard period, but it may be impossible until 1990's for short duration. 3. "Y-k method" developed by writer is best suitable in the rainfal frequency analysis in Korea because of its convenience and reduction in the amount of calculation compared with other methods. 4. To improve the utilization of the rainfall frequency atlas, the larger-sized and the more detailed iso-precipitation atlas must be drawn.atlas must be drawn.

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Trends of the PM2.5 concentrations and high PM2.5 concentration cases by region in Korea (우리나라 지역별 초미세먼지(PM2.5) 농도 추이와 고농도 발생 현황)

  • Yeo, Minju;Kim, Yongpyo
    • Particle and aerosol research
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    • v.15 no.2
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    • pp.45-56
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    • 2019
  • The public's concern on ambient $PM_{2.5}$ has been increasing in Korea. We have estimated (1) the annual and monthly mean $PM_{2.5}$ concentrations, (2) the frequency by the $PM_{2.5}$ concentration interval, and (3) the high concentration occurrence duration time between 2015 and 2018 at 16 administration regions. We found that there have been differences in all three above parameters' trends among the studied 16 regions in Korea. Still, Jeonbuk showed the highest rank in all three parameters' trends. In Jeonbuk, the average $PM_{2.5}$ concentration and the sum of the frequency fraction when the $PM_{2.5}$ concentration being over $75{\mu}g/m^3$ between 2016 and 2018 was $28.4{\mu}g/m^3$ and 9.0%, respectively. And the days when the $PM_{2.5}$ concentration is over $50{\mu}g/m^3$ between 2015 and 2018 were 149. Chungbuk was the only region with the increasing trend of $PM_{2.5}$ concentration between 2016 and 2018. And in Seoul and Gyeonggi, the average $PM_{2.5}$ concentrations decreased whereas the high concentration frequency fraction increased between 2016 and 2018. Also, it is found that there have been differences in the trends of the frequency by the $PM_{2.5}$ concentration interval and the high concentration occurrence duration time between $PM_{10}$ and $PM_{2.5}$.

A study on bulk deposition flux of dustfall and insoluble components by the wind intensity in Busan, Korea (바람의 강도에 따른 강하먼지와 불용성 성분의 조성특성)

  • 황용식;김유근;박종길;문덕환
    • Journal of Environmental Science International
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    • v.11 no.7
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    • pp.651-662
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    • 2002
  • Weather elements were observed by the AWS (Automatic Weather System) and dustfall particles were collected by the modified American dust jar (wide inlet bottle type) at 4 sampling sites in Busan area from March. 1999 to February, 2000. Thirteen chemical species (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Si, and Zn) were analyzed by AAS and ICP. The purposes of this study were to estimate qualitatively various bulk deposition flux of dustfall and insoluble components by applying regional and seasonal wind intensity. Frequency of wind speed were found in order of low(1-3m/s), very low(<1m/s), medium(3-8m/s) and high(>8m/s), and annual mean had higher range at low(1-3m/s) for 56.3%. Strong negative linear correlation were observed between dustfall and wind direction (northeastern and eastern), but strong positive linear correlation were observed between dustfall and wind direction (western and northwestern) at industrial, commercial and coastal zone(p<0.05). While a negative correlation were observed between wind speed frequency of very low(<1 m/s) and dustfall, and positive correlation were observed between wind speed frequency of low(1-3m/s) and dustfall in coastal zone(p<0.05). The correlation coefficient was observed 0.556 between wind speed frequency of low(1-3m/s) and Ni by commercial zone(p<0.05). The correlation coeffcient show well-defined insoluble trace metals (Al, Ca, Cr, Cu, Fe, Pb, and Zn) and wind speed frequency of low(1-3m/s) at coastal zone, which was found significant difference(p<0.01).