• 한국환경과학회지
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• 제8권2호
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• pp.189-195
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• 1999

Determining factors and temporal & spatial characteristics of COD(Chemical Oxygen Demand) at the sea surface in Jinhae bay have been examined by using seasonal data, taken at twenty six stations over the whole bay during 1989~1994 by NERDA. The data have been analyzed in terms of long term means, anomalously large values. Jinhae bay is divided into three regions based on the time mean : mouth of Jinhae bay, inner sea of Masan bay, western sea of Jinhae bay called region 1,2 and 3, respectively. The horizontal distribution of the long term mean of COD at each station is similar to those of nitrogen and phosphorus. Characteristics of whole mean variation in the year shows high range of variation in region 2. It was appear to decreases every year in whole trend. Factors determining seasonal variation in whole COD mean are relative to salinity and nutrient, affected by precipitation in summer. Spatial variation shows high range of fluctuation in region 2 compare to other region. Factors determining of spatial variation of COD was appear to nutrient, affected by pollutant load of land area and bottom sediment. The long term mean of COD at each station is closely related with thats of nutrients. The correlation coefficient between COD and nitrogen, phosphate phosphorus was found to be high as 0.75, 0.78, respectively. Anomalously large COD was observed 14 times at 6 stations. These stations are located in inner sea of Masan bay(Region 2) and Songjeong bay(Region 1). The seasonal frequency of the observed anomalous COD is large in April, and other seasons are much the same.

• 해양환경안전학회지
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• 제5권1호
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• pp.19-27
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• 1999

This paper is to estimate the long and short term variations of mean sea level in Korean coastal waters by identifying interrelations among the mean sea level, atmospheric pressure and air temperature along the coast. For this, long-term tidal data observed at tidal and weather observation stations were brought into a statistical analysis. It was noted that, in a general sense, an inverse relationship exists between the sea level and the atmospheric pressure and a positive relationship between the sea level and air temperature, respectively. The maximum difference of monthly mean sea level was in the range of 21 to 25 cm at the eastern and southeastern coasts, meanwhile more than 30 cm being in both in southern and western coasts. It was also noted that mean sea level continues to rise in a long-term basis. Long-term variation of mean sea level trends to rise 0.10 ∼ 0.44 cm per year for each region. However, the long-term variation of mean sea level in the isolated islands shows a different trend, Ullngdo being 0.41 cm fall per year and Chejudo being 0.44 cm rise per year.

• 상하수도학회지
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• 제20권2호
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• pp.187-196
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• 2006

Forecasting the long-term water demand is important in the plan of water supply system because the location and capacity of water facilities are decided according to it. To forecast the long-term water demand, the existing method based on lpcd and population has been usually used. But, these days the trend among the variation of water demand has been disappeared, so expressing other variation of it is needed to forecast correct water demand. To accomplish it, we introduced the System Dynamics method to consider total connections of water demand factor. Firstly, the factors connected with water demand were divided into three sectors(water demand, industry, and population sectors), and the connections of factors were set with multiple regression model. And it was compared to existing method. The results are as followings. The correlation efficients are 0.330 in existing model and 0.960 in SD model and MAE are 3.96% in existing model and 1.68% in SD model. So, it is proved that SD model is superior to the existing model. To forecast the long-term water demand, scenarios were made with variations of employment condition, economic condition and consumer price indexes and forecasted water demands in 2012. After all scenarios were performed, the results showed that it was not needed to increase the water supply ability in Seoul.

• 천문학회보
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• 제40권1호
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• pp.82.1-82.1
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• 2015

We investigate the long-term spatial drift of the center and the temporal variation of the shutter delay time map of Y4KCam mounted on the CTIO 1.0m telescope. We have collected shutter delay time maps for over 7 years as a part of long-term survey program. We find that the center of the shutter delay time map can drift up to $450{\mu}m$ on the CCD. This effect can result in a small amount of error unless the proper shutter delay time correction, but it does not appear to cause any significant problems in photometric measurements. We obtain the mean value of the shutter delay time of $69.1{\pm}0.9$ msec and find no temporal variation of the shutter delay time of Y4KCam for over 7 years, indicative of the mechanical stability of the shutter. We suggest that using a master shutter delay time correction frame would be sufficient to achieve high precision photometry and this does not add up errors more than ~ 2.5 mmag across the CCD frame with exposure times longer than 1 sec.

• Ocean and Polar Research
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• 제35권2호
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• pp.171-179
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• 2013

The long-term variability of sea surface temperature in the East China Sea was reviewed based mainly on published literatures. Though the quantitative results are not the same, it is generally shown that sea surface temperature is increasing especially in recent years with the rate of increase about $0.03^{\circ}C$/year. Other meaningful results presented in the literatures is that the difference of water properties between layers upper and lower than the thermocline in summer shows an increasing trend both in temperature and salinity, suggesting that the stratification has been intensified. As a mechanism by which to evaluate the wintertime warming trend in the region, the weakening of wind strength, which is related to the variation of sea level pressure and atmospheric circulation in the western North Pacific and northern Asian continent, is suggested in the most of related studies.

• Fisheries and Aquatic Sciences
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• 제2권2호
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• pp.199-209
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• 1999

Before investigating the long-term variations in macrobenthic communities sampled in the Chokchon macrotidal flat in Inchon, Korea, from 1989 to 1996, we need to understand how environmental factors in the area vary. As potential governing agents of tidal flat communities, abiotic factors such as mean sea level, seawater, air temperature, and precipitation were considered. Data for these factors were collected at equal intervals from 1976 or 1980 to 1996, and were analyzed using a decomposition method. In this analysis, all the above variables showed strong seasonal nature, and yielded a significant trend and cyclical variation. Positive trends were seen in the seawater and air temperatures, and based upon this relationship, it was found that the biological sampling period of our program has been carried out during warmer periods in succession. This paper puts forth some hypotheses concerning the response of tidal flat macrobenthos communities to the changing environment including mild winters in succession.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2003년도 학술발표회논문집(1)
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• pp.151-158
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• 2003

Recently, there has been considerable interest in the influence of El Nino/Southern Oscillation (ENSO) on a global scale. ENSO has been measured by a simple index called Southern Oscillation Index (SOI). The statistical characteristics of SOI have been also focused to reveal the influence of ENSO. The SOI trend shows that El Nino events are generally getting stronger and more frequently occurring than La Nina events. However, the variation of SOI has varied significantly in a long-term. The SOI values are computed using the mean value and its standard deviation of the base period from 1951 to 1980. In the present study, the different base periods are applied to compute the SOI values and the influence of the different base periods is investigated in detail to reveal the long-term variation of SOI From the results, we could conclude that the present SOI should be carefully considered as a criterion to judge whether the El Nino and La Nina events are occurring.

• Environmental Engineering Research
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• 제17권2호
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• pp.103-110
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• 2012

This study was performed mainly to examine whether a city with a metal industrial presence presents different characteristics in ambient volatile organic compound (VOC) concentrations compared to residential (RES) and commercial/residential combined (CRC) areas of another city by using long-term monitoring data (from January 2006 to February 2009). For most target VOCs, ambient concentrations in the metal-industrialized city were lower than for the RES and CRC areas. Aromatic compounds were the predominant VOC groups for the metal industry city as well as for other land uses. The ambient concentrations of aromatic VOCs were higher in the winter and spring seasons than in the summer and fall seasons, whereas those of chlorinated VOCs did not show any distinctive variations. In addition, higher concentrations were observed during daytime hours. The correlations between the ambient target compounds were statistically significant, except for the correlation between benzene and ozone.

• 한국방재학회 논문집
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• 제1권2호
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• pp.93-101
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• 2001

본 연구에서는 계절에 따른 온도 변화를 고려한 건조수축의 예측모델을 제시하여, 실제구조물에서의 계절에 따른 온도변화에 대한 장기 거동 특성을 보다 향상된 방법으로 파악할 수 있는 방법을 제시하였다. 본 연구에서 사용된 건조수축 보정계수식은 계절에 따른 온도변화를 포함한 건조수축의 실제 실험적 데이터들을 사용하여 제안되었으며, FCM 교량의 장기 거동 조사는 현장에서 건조수축의 수치해석 결과를 적용할 수 있는지 없는지를 결정하기 위해 수행되었다. 본 연구에서 채택된 수치해석 방법은 실제 변형율과 차이가 발생하는 일반적인 방법과는 달리 실제 구조물의 거동특성을 매우 유사하게 모사할 수 있는 것으로 나타났다. 결과적으로 본 연구에서 제안된 방법은 FCM 교량의 장기 처짐에 대한 예측을 향상 시킬 것이다.

• 천문학논총
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• 제30권2호
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• pp.193-195
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• 2015

The Palomar Transient Factory is a project making use of a Schmidt 48 inch telescope located on the Palomar Mountain, which is surveying the sky with dynamical cadences. It was deployed in 2009 and the observed sky region is over 1200 square degrees. We have studied the long-term periodic variabilities of the known galactic cataclysmic variables (CVs). More than 20 of the sources had been found to have long term periodic signals, ranging from several tens of days to several hundreds of days. Some possible scenarios are proposed to explain the results, such as a magnetic field change of the companion star, precession of the accretion disk, triple systems and superoutburst cycles. Some preliminary discussion will be presented in this article.