• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.555-555
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• 2016

본 연구는 낙동강 유역의 대표지점별 과거 수문자료의 타당성을 검토하고, 발생된 오류에 대해서는 표준화된 방법으로 수정 보완하여 하천유량 적정관리를 위한 기초 통계자료를 구축하는데 그 목적이 있다. 따라서 수문자료의 정확성 확보와 향후 자료의 활용성을 증대하기 위하여 낙동강홍수통제소의 수문관측소를 중심으로 수위, 수위-유량관계곡선식, 유량자료를 다양한 근거자료 및 수문자료의 특성 등을 고려하여 기초적인 통계자료 구축을 위해 노력하였다. 과거자료를 검토한 결과 2000년대를 기점으로 수위자료의 정확도가 향상되는 것으로 판단하였으며, 사용자에게 신뢰성 있는 자료를 제공하기 위하여 2000년도 이후의 수위자료와 수위-유량관계곡선식을 수집하여 검토?분석하였고, 자료 보완을 통하여 신뢰성 있는 유량자료를 구축할 수 있도록 하였다. 대상지점 12개소에 대하여 취득기간별에 따른 각종 기초통계 특성에 대하여 요약 정리하였다. 자료의 취득률은 대부분 90% 이상의 양호한 결과를 나타내었지만, 몇몇 지점에서는 수위자료의 불안정으로 인하여 60% 이하를 나타내는 지점 또한 존재하였다. 연평균 손실고는 평균강수량에서 유출고를 뺀 값을 나타내고, 이에 대한 유출률을 산정하였다. 또한 취득기간 동안의 평균 풍 평 저 갈수량을 분석하였다. 치수 및 이수 측면을 고려하여 최고유량과 이에 대한 발생일을 조사하였으며, 최저유량의 경우는 7일 평균 최저유량과 이에 대한 발생일을 조사하였다. 최저유량 발생일은 7일 중 중간일을 기준으로 표시하였고 조석이나, 지속적인 배수의 영향을 받는 지점은 홍수위 및 홍수량에 대해서만 산출하였다. 비록 2000년 이전 자료에 대해서는 현실적인 한계로 인하여 검토를 실시하지 못하였으나, 최소 10년간의 자료에 대해서는 신뢰성을 확보하기 위한 노력을 기울였으며, 이러한 경험으로 다시는 재현되는 않는 자연현상에 대한 현장단위에서의 관측 및 측정뿐만 아니라 이를 바탕으로 축적된 자료의 구축, 검증을 통한 DB 구축 등에 더욱 각고의 노력이 필요할 것으로 판단된다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.5
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• pp.95-101
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• 2023

Recent persistent coastal developments have expanded recreational areas and enhanced accessibility. However, this growth has also led to a rise in safety incidents. These accident factors can be divided into human-made and natural types. The latter is comprised of dynamic factors like waves, tides, sea fogs, and winds. While institutions like the Korea Meteorological Administration and the Korea Hydrographic and Oceanographic Agency already offer data on these dynamic factors, the resolution is often insufficient for a precise assessment of localized risks. In this study, to overcome these limitations, we utilized the dynamic information from existing open systems to construct a high-resolution numerical simulation. Through this, we developed an automated module to predict dynamic factors in localized coastal activity areas. Particularly during the module's construction, we compared and reviewed the numerical prediction results for waves with observed wave heights.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.4
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• pp.243-251
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• 2012

Real-time monitoring for environmental factors(temperature, salinity, chlorophyll, etc.) and carbonate components( pH and $fCO_2$) was conducted during 5-6th of July, 2012 at a seaweeds farm in Gijang, Busan. Surface temperature and salinity were ranged from $12.5{\sim}17.6^{\circ}C$ and 33.7~34.0, respectively, with highly daily and inter-daily variations due to tide, light frequency(day and night) and currents. Surface $fCO_2$ and pH showed a range of $381{\sim}402{\mu}atm$ and 8.03~8.15, and chlorophyll-a concentration in surface seawater ranged 0.8~5.8 ${\mu}g\;L^{-1}$. Environmental and carbonate factors showed the highest/lowest values around 5 pm of 5th July when the lowest tidal height and strongest thermocline in the water column, suggesting that biological production resulted in decrease of $CO_2$ and increase of pH in the seaweed farm. Processes affecting the surface $fCO_2$ distribution were evaluated using a simple budget model. In day time, biological productions by phytoplankton and macro algae are the main factors for $CO_2$ drawdown and counteracted the amount of $CO_2$ increase by temperature and air-sea exchange. The model values were a little higher than observed values in night time due to the over-estimation of physical mixing. The model suggested that algal production accounted about 14-40% of total $CO_2$ variation in seaweed farm.

• Economic and Environmental Geology
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• v.39 no.3 s.178
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• pp.269-284
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• 2006

Aquifer responses to the river stage fluctuations were analyzed between the groundwater level and the river stage in an alluvial aquifer. The auto-correlation and cross-correlation as a time series analysis were applied. Study site is a floodplain in the Mangyeong river. Groundwater levels in each depth representing the silt and sand(SS), gravel and sand(GS), and weathered zone(WZ) layer were monitored. The groundwater levels were more sensitive to the river stage fluctuations than rainfall. Since the river stages are influenced by the gate operations downstream and tide, show periodic patterns, and the correlation coefficients with rainfall is low. Cross-correlation function between groundwater level in each depth do not show any delay time, then response time is very short to each depth. Cross-correlation analysis were performed to estimate the response time of groundwater levels to river stage fluctuations. Groundwater levels respond to the river stage within 30 minutes to 1 hour in wells near the stream. Short time lag between groundwater level and river stage indicates the quick response. A different response time imply the hydraulic inhomogeneity of the site, and a probable high permeability zone between river and aquifer can be inferred. Mangyeong-river in study site is a gaining stream normally, and river stage rising by gate operation or floods makes river water flow into groundwater. The auto-correlation and cross-correlation functions as a time series analysis can be a good tool to interpret the aquifer responses to stream stage fluctuation

• Journal of the Korean earth science society
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• v.22 no.6
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• pp.480-490
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• 2001

The soil-air exchange processes of Hg were investigated from the Hari area of Kang Hwa Island during the late March 2001. In the course of our study, we determined the concentration gradients of Hg and combined these gradient data with micrometeorological components to derive its fluxes. Results of our study indicate that the concentration levels of Hg in the study area are notably lower than those typically found in urbanized areas of Korea. However, the computed fluxes were seen to be significantly larger for relatively remote areas, reaching over 200 ng/m$^2$/hr. Comparison of environmental conditions shows that the concentrations of most pollutant species including NO$_X$ and PM were significantly higher during emission, while meteorological conditions were characterized by high temperature and low humidity. Results of correlation analysis also indicate that such pollutants as hydrocarbons, nitrogen oxides, and PM generally exhibit strong positive correlations with Hg-related parameters during emission events, while such relationships were reversed during dry deposition events. The results of our present study suggest the possibility that the concentrations and fluxes of total gaseous Hg observed during deposition events can be influenced by the processes that are also important for the fine, rather than coarse, size fraction of particles.

• 한국해양학회지
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• v.19 no.2
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• pp.141-152
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• 1984

In order to investigate the circulation dynamics of the Keum River estuary, 300velocity fields obtained at six sites over two tidal cycles by using instantaneous profiling technique were analyzed in detail. In this investigation, the variability of shear velocity, bottom shear stress, drag coefficient, and roughness length scale were confirmed. The measured values of the bottom boundary drag coefficient show wide range of variations, i.e., C$\_$100/=6.78${\times}$10$\^$-5/∼1.15${\times}$10$\^$-1/, and the mean of 300 measurements is 1.6${\times}$10$\^$-2/. The relationship between U* and C$\_$100/ also show the scatter in values. However, overall mean values over two tidal cycles at 6 stations show that if U* 1cm/s, C$\_$100/ is unpredictable, if U* 1cm/s, C$\_$100/ increase with U*. The values of Re$\_$100/ and C$\_$100/ have scatter. But the overall mean values over two tidal cycles show that if Re$\_$100/ 3.6${\times}$10$\^$5/, C$\_$100/ is unpredictable, if Re$\_$100/ 3.6${\times}$10$\^$5/, C$\_$100/=1.4${\times}$10$\^$-2/. Finally the flow regime of the Keum River estuary was classified as "subcritical fully turbulent" flow.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.1 no.1
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• pp.1-8
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• 1981

Since the estuary is a very complex place in which the sea water and the fresh water meet, it is very difficult to make a general analytical description of salinity distribution in the estuary. As an attempt to investigate the characteristics of salinity variation in the estuary of the Geum River, the field observations were continuously carried out at three points near the Gunsan New Harbor at the time intervals 1 to 1.5 hours during one tidal cycle and the data were analysed. The following results were obtained; 1. It was reconfirmed that most of the ratios of the salinity to the conductivity were widely distributed between the range of 0.5 to 1.0. 2. The salinity showed the peak at the high water, and then it began to decrease gradually and had the lowest value 0 to 2 hours after the low water. 3. The density current was generally the intense mixing type and when the river discharge was very large it was of the moderate type. 4. The vertical salinity distribution was not significantly affected by the wave height. 5. The maximum vertical salinity differences were generally less than 10 g/l and the time of the occurrence of the minimum value was 0 to 3 hours after the low water when in the spring tide and in the neap tide it occurred 2 to 3 hours after the high water.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.365-373
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• 2013

Representative tidal gauging (TG) stations are selected to cover the tidal characteristics of the Korean peninsula coastal seas, and the statistical parameters of the data are analysed from the perspective of the probability distribution at that TG station. The shape of the distribution in the Incheon and Gunsan TG stations, which are tide-dominated areas, shows two clear modes at HWONT and LWONT in the distributions, and in the Mokpo station, shows an asymmetric double peak distribution. In contrast, the frequency distribution shape shows a smoothed flat peak in the Jeju, Yeosu and Busan TG stations, and a single peak in the Pohang and Sokcho TG stations. The emersion and submersion equations suggested as the 6-parameter Gaussian mixture models in this study are accurate, and well fitted to the observed tidal elevation data. The ${\mu}_1$, ${\mu}_2$ parameters are highly correlated to the LWONT and HWONT, and the ${\sigma}_1$ and ${\sigma}_2$ parameters are also closely correlated to the mean tidal range. The ${\mu}_1$ and ${\mu}_2$ parameters coincide with the modes of the suggested probability distribution of the hourly tidal level data.

• Journal of Aquaculture
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• v.13 no.1
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• pp.87-99
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• 2000

Field survey on the variational characteristics of water quality and chlorophyll a concentraion were carried out at the 25 stations for four seasons in Kogum-sudo(Straits) southern coast of Korean Peninsula from Feburuary to October in 1993. We made an analysis on biological factor as chlorophyll a concentraion as well as physicio-chemical factors such as water temperature salinity sigma-t transparency dissolved oxygen(DO) chemical oxygen demand(COD) nutrients (ammonia, nitrite, nitrate, phosphate, and silicate) N/P ratio and suspended solid(SS). The waters in the Kogum-sudo were not stratified due to the tidal mixing. And the high productivity in photic layer were supported by high nutrients concentration from bottom waters. The high concen-trations of suspended solid in straits had a bad influence upon marine biology of nature and cultivations. In Kogum-sudo had a sufficient nutrients for primary productivity during a year. Especially phosphate and inorganic nitrogen were high the other side silicate was very low. The source of nutrients supply depend on rather mineralization of organic matters and input of seawater from outside than input of freshwaters from lands. Phytoplankton biomass as measured by chlorphyll a concentratiion was very high all the year round and it was controlled by the combination o f several environmental factors especially of phosphate in summer and dissolved nitrogen in other seasons.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.637-644
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• 2015

In order to estimate harbor tranquility, it is needed to simulate wave propagation in a harbor by using both methods under abnormal wave condition and normal wave condition. The problem is the latter case was not simulated in the statement for the Sea Area Utilization Conference. As harbor calmness about normal wave condition has the same meaning as harbor serviceability, in order to assess harbor tranquility, it is needed to survey wave data for long periods but the survey was not done by reason of a lack of budget and shortage of time for plan. It is more important to make a plan for minimizing environmental impact and to assess an improvement of fisherman's living environmental as the assessment of the harbor serviceability is related with the propriety of the plan. In order to assess it, it is needed to understand it clearly, survey for long period of wave data, and clarify the procedure for computation of it. And also providing wave data like tide and tidal current data from KHOA (Korea Hydro graphic and Oceanographic Agency) and making a guideline for assessing it are needed.