• Proceedings of the KSEEG Conference
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• 2000.04b
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• pp.146-150
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• 2000

한국자원연구소는 1998년에 영국지질조사소가 설계, 제작한 FLARE+ 지자기연속관측시스템 한 대를 한국자원연구소 내에 설치하고, 연속적인 관측을 수행하고 있으며, 이 관측소를 IAGA 에 등록하고 국제지자기관측소식별부호 DZN을 받았다. 이 시스템은 5초 간격으로 지자기장의 3 성분을, 1분 간격으로 총자기장을 측정하여, 1분 평균자료를 생산하고 있다. 지자기 관측자료? 활용 분야들 중 하나인 지역적 지자기 변동지수(local K index)를 게산하였다. 이를 위해서는 1999년 3월 2일부터 18일까지 17일 동안 관측자료를 기초자료로 하였고, 대전지역의 최대변동폭을 300 nT로 가정하였다. 그결과, 지자기의 최대 변동 지수 폭을 0~9 까지로 할 때, 사용된 자료로 계산한 지역적 지자기 변동지수는 1~6사이에 분포하였고, 최대빈도의 변동지수 3이었다. 한편, IAGA가 계산한 같은 기간의 전지구적 지자기 변동지수(planetary k index)는 0~6사이에 부포하였으며, 최도빈도의 변동지수는 역시 3이었다. 위 기간 동안의 대전의 지역적 변동지수 수열과 전지구적 지자기 변동지수 (planetary K index) 수열 사이의 상관계수(cross correlation coefficient coefficient)는 0.66563이었다. 이것은 지역적 변동지수가 전지구적 변동지수 같은 방향으로 변화하고 있음을 뜻하며, 지역적 변동지수를 해당 지역의 지자기 변동을 대표하는 값으로 쓸수 있음을 뜻한다.

• Journal of Korean Society of Transportation
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• v.20 no.6
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• pp.59-68
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• 2002

AADT(Annual Average Daily Traffic) can be obtained by using short-term counted traffic data rather than using traffic data collected for 365 days. The process is a very important in estimating AADT using short-term traffic count data. Therefore, There have been many studies about estimating AADT. In this Paper, we tried to improve the process of the AADT estimation based on the former AADT estimation researches. Firstly, we found the factor showing differences among groups. To do so, we examined hourly variables(divided to total hours, weekday hours. Saturday hours, Sunday hours, weekday and Sunday hours, and weekday and Saturday hours) every time changing the number of groups. After all, we selected the hourly variables of Sunday and weekday as the factor showing differences among groups. Secondly, we classified 200 locations into 10 groups through cluster analysis using only monthly variables. The nile of deciding the number of groups is maximizing deviation among hourly variables of each group. Thirdly, we classified 200 locations which had been used in the second step into the 10 groups by applying statistical techniques such as Discriminant analysis and Neural network. This step is for testing the rate of distinguish between the right group including each location and a wrong one. In conclusion, the result of this study's method was closer to real AADT value than that of the former method. and this study significantly contributes to improve the method of AADT estimation.

• Journal of Marine Life Science
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• v.4 no.2
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• pp.53-62
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• 2019

Heterotrophic bacteria are a major member of the microbial loop in the marine ecosystem and play an important role in the biogeochemical cycle decomposing organic matter. Therefore study of bacterial variation is important to understand the material cycle and energy flow of marine ecosystems. We investigated the monthly variations of bacteria and environmental factors in the Youngsan River estuary, and the correlation between bacteria and phytoplankton biomass (chlorophyll-a) including size-structure. As a result, bacteria of the Youngsan River estuary were higher in the surface than in the bottom layer, and higher in the summer than in winter. And the closer to the dike, the abundance increased, and it increased to the peaks in August, September, and June 2019 at the station closest to the dike. The chlorophyll-a also increases at the stations and time when the bacterial abundance was high and they correlates positively displaying no difference between size fractions. The results indicate that organic matter derived from phytoplankton has an effect on bacterial variation but no size-dependent effects. In addition, the seasonal pattern of bacteria increasing in proportion to the water temperature suggests the effect of water temperature on the growth of bacteria. No association of bacterial abundance variation with nutrient supply due to freshwater input was observed. In this study, dissolved oxygen was depleted and hypoxia was observed for a short time when a strong stratification was not developed. This may be resulted from the supply of organic matter from phytoplankton and the consumption of oxygen due to bacterial decomposition.

• 주택과사람들
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• s.196
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• pp.50-51
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• 2006

8월 뜨거운 여름이 지속된 가운데 주택 시장은 한산한 분위기를 보였다. 계절적 비수기로 거래가 뜸한 가운데 서울에서는 종로구, 강서구, 성동구 등 재개발 주변 지역, 경기도는 고양시, 파주시의 주택 시장이 강세를 보였다.

• 주택과사람들
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• s.203
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• pp.98-99
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• 2007

봄철 이사철 시즌이 도래해도 매매 및 전세 가격이 움직이지 않는다. 정부의 각종 규제책이 부동산 시장 곳곳에 영향을 미치기 때문이다. 침체될 조짐까지 보이는 가운데, 3월 부동산 시장을 들춰보았다.

• 주택과사람들
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• s.202
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• pp.90-91
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• 2007

'1.11 대책' 이후 부동산 시장은 실수요자 위주로 빠르게 재편되면서 안정세를 보이고 있다. 하락을 주도한 재건축 아파트를 중심으로 매매, 전세 등 전체적인 부동산 가격은 약보합세를 띠었다. 2007년 2월 주택 시장을 돌아보았다.

• 주택과사람들
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• s.197
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• pp.46-47
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• 2006

지난 9월은 판교 청약 열기와 함께 주택을 구입하려는 매매ㆍ전세 수요가 몰려 집값이 강세를 보였다. 택지지구에 분양하는 아파트의 고분양가 논란 등으로 주변의 집값도 함께 오를 것으로 보여 당분간 주택 가격은 강보합세를 유지할 것으로 예상된다.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.69-74
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• 2016

Bathymetric changes were studied in the southern sea off the Jinwoo-do Island, which is one of the deltaic barrier islands surrounding the Nakddong river estuary. In this study, 16 bathymetry data sets were obtained from June 2006 to April 2015. Two narrow channels, the one lying between Jinwoo-do and Shinja-do, and the other one lying between Nulcha-do and Jinwoo-do extended into the eastern and western parts of the study area, respectively. The eastern extension of the channel contained a passage of mixed estuarine waters of seawater and river water discharged from the Nakdong river barrier and the west Nakdong River. The western channel connected the Nakdong River estuary with the Busan New Port via a connecting pier. Total volumetric changes of sediments in study area and discharge flow of the Nakdong river barrier were analyzed. Bottom topographical changes occurred mainly in the eastern extension of the channel. These changes were initially characterized by gradual erosion or deposition followed by rapid restoration. The total volume of sediment gradually increased from June 2006 to March 2013, but experienced a sudden decrease in October 2013 because of typhoon Danas. Few fluctuations were observed from October 2013 to April 2015. Analysis of the cross-sectional bathymetry of the north-south direction showed that the deepest point of the eastern channel moved 100-130 m westward and 200 m northward between June 2006 and April 2015.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.328-338
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• 2019

This paper presents the numerical simulations of future river bed changes using CCHE2D, a two-dimensional numerical model, for river confluences at the confluences of the Nakdong River and Gamcheon as well as Geum River and Mihocheon. The numerical simulations of future river bed changes were conducted for three years using hydrological data from August 30, 2012, to August 29, 2015 after the Four Major River Restoration Project. The simulation results demonstrated that river bed changes occurred actively near the confluence where sediment deposition was concentrated, resulting in the possibility of point bar formation. Through the numerical simulations, the characteristics of future river bed change was evaluated by investigating the characteristics of bed changes, average bed elevation changes, and the difference between deposition and erosion in the target section. The two-dimensional numerical model is expected to be used in the future to prepare effective stabilization plans for the tributary confluence.

• Journal of Korea Port Economic Association
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• v.38 no.4
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• pp.13-23
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• 2022

In this study, from January 2015 to April 2020, we propose a stochastic volatility model to capture the leverage effect on daily freight yields in the dry cargo market and analyze the freight yields. Estimation involving the Bayesian Markov Chain Monte Carlo method for the leverage effect based on the negative correlation that exists between returns and volatility in stochastic volatility analysis yields similar estimates, and the statistcs indicates significant. That is, the results of the empirical analysis show that the degree of correlation between returns and volatility, and the magnitude and sign of fluctuations differ, which suggests that taking into account the leverage effect in the SV model improves the goodness of fit of the estimates. In addition to the statistical significance of the estimated model's leverage effect, the analysis by log predictive power score presents the estimated results with improved predictive power of the model considering the leveraged effect. These astatistically significant empirical results show that the stochastic volatility model considering the leverage effect is important for freight rate risk modeling in the marine industry.