• 해양환경안전학회지
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• 제13권4호
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• pp.15-19
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• 2007

2006년 8월 경북 연안의 우렁쉥이 앙식장에서 대량폐사가 발생하였다. 폐사 원인을 규명하기 위하여 폐사 직후 폐사가 발생한 양식장을 대상으로 수질환경 조사와 병리학적 조사를 실시하였으나 특이점을 발견하지 못하였다. 그래서 폐사가 발생하기 직전 동해에 영향을 미친 10호 태풍 '우쿵'이 우렁쉥이 폐사에 영항을 미쳤을 것으로 가정하고 태풍 '우쿵' 통과 전후의 해황 자료를 분석하였다. 태풍 우쿵의 영향을 받기 전인 8월 초 중순 동해 연안은 전반적으로 저층 냉수의 용승으로 인하여 수심 10m 이심에서는 $15^{\circ}C$ 이하의 찬물이 존재하고 있었다. 그 후 매풍 '우쿵'의 영향으로 인한 북풍이 약 5일간 지속되면서 수온이 높은 외측의 표층수가 연안으로 밀려와 침강하는 현상(에크만 효과)이 발생하여 우렁쉥이가 매달려 있는 수심 $10{\sim}20m$의 수은이 일시에 $10^{\circ}C$ 이상 상승하여 약 5일간 지속되었다. 2006년 경북 연안의 양식 우렁쉥이는 장기간 냉수에 적응되어 있다가 태풍 '우쿵'의 영향으로 수온이 급상승함에 따른 수온 스트레스로 인하여 대량폐사된 것으로 추정된다.

• Ocean and Polar Research
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• 제26권2호
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• pp.341-349
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• 2004

Hyrdography and deep currents were measured from 1997 to 1999 to investigate deep-sea environments in the KODOS (Korea Deep Ocean Study) area of the northeastern tropical Pacific. KODOS area is located meridionally from the North Equatorial Current to the boundary between the North Equatorial Current and the Equatorial Counter Current. Strong thermocline exists between 10 m and 120 m depths at the study area. Since that strong thermocline does hardly allow vertical mixing between surface and lower layer waters, vertical distributions of temperature, salinity, dissolved oxygen and nutrients drastically change near the thermocline. Salinity-minimum layer, which indicate the North Pacific Intermediate Water (NPIW) and the Antartic Intermediate Water (AAIW), vertically occupies vertically at the depths from 500 m down to 1400 m. The NPIW and the AAIW horizontally occur to the north and to the south of $7^{\circ}N$, respectively. The near-bottom water shows the physical characteristics of $1.05^{\circ}C$ and 34.70 psu at the depths of 10 m to 110 m above the bottom (approximately 4000-5000 m), which was originated from the Antarctic Circumpolar Water. It flows northeastwards for 2 to 4 months at the study area, and its mean velocity was 3.1-3.7 cm/s. Meanwhile, reverse (southwestward) currents appear for about 15 days with the average of 1.0-6.1 cm/s every 1 to 6 months. Dominant direction of the bottom currents obtained from the data for more than 6 months is northeastward with the average speeds of 1.7-2.1 cm/s. Therefore, it seems that deep waters from the Antarctica flow northwards passing through the KODOS area in the northeastern tropical Pacific.

• 한국지하수토양환경학회지:지하수토양환경
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• 제6권3호
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• pp.3-12
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• 2001

본 시험은 제주지역 화산회토에서 pressure-vacuum soil water sampler를 이용하여 시비 양분의 토양깊이별 이동상태를 조사하기 위하여 실시하였다. lysimeter(single chamber : model SW-071)를 각각 20, 40, 60, 80, 100, 120cm의 깊이에 매설한 후 전작물로는 옥수수, 후작물로는 감자를 재배하면서 강우시 침투수를 채수하여 pH및 양, 음이온의 농도를 조사하였다. 시비량은 질소-인산-가리를 옥수수는 36-30-30kg씩, 감자는 28-22-24kg씩 각각 파종전에 시용하였다. 채취한 침투수중 Cl, $NO_3$-N, $Ca^{+2}$, $K^{+}$의 평균농도는 시비 1개월 후에 20~40cm 깊이에서 급격하게 높아진 후 농도가 점차 낮아지면서 심토층으로의 하향 이동이 계속되어 5개월 후에는 시험 전 토양과 비슷한 수준이 되었다. 심토층(120cm)에서의 $NO_3$-N은 시비 1~l.5개월 후 그 농도가 가장 높았고, 다른 양이온도 비슷한 경향을 보였다. 용탈수의 PH와 $NO_3$-N은 부의 상관을 보였고, $NO_3$-N과 양이온간에는 고도의 정의 상관을 보여 $NO_3$-N이 표토에서 심토층으로 하향이동시 $Ca^{+2}$, $K^{+}$, $Mg^{+2}$ 등의 양이온도 동반용탈되는 것으로 조사되었다.

• 한국환경보건학회지
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• 제31권6호
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• pp.489-497
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• 2005

A numerical method for the mathematical water modeling in 2-dimensional flow has been developed. The model based on a split operator technique, in which, the advection term is calculated using the upwind scheme. The diffusion term is one- dimensionalized and calculated using Crank-Nicholson's implicit finite difference scheme to reduce the numerical errors from large time steps and variable spacings. It also provides a relatively simple and economic method for more accurate simulation of pollutant dispersion. Water depths and flow velocities in the Boreyong reservoir during the normal water periods were predicted by numerical experiments with a 2-dimensional flow model so as to provide current field data for the study of advection and diffusion of pollutants. Developed 2-dimensional water quality model is applied to Boreyong reservoir to simulate a spatial and periodical changes of water quality.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.475-482
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• 2005

Many public facilities including roadway, railway, and embedded pipe lines in this country have been damaged by the repeated freezing and thawing of the soil during winter and spring every year. However, there are only few research results in field of frozen ground in this country. Also, there are no the formulation of the reasonable equation for frost penetration depths and of the criterion for identifing potentially frost-susceptible soil in design manual of pavement yet. Through this study it is anticipated to asses the frost action problem in roadway, railway, and water suppply lines and to establish the design criterion about pavement in seasonal cold region.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.324-327
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• 2006

The high Fe and Mn contents in riverbank filtered groundwater often provoke problems on the water quality, We analyzed the mineral and chemical compositions of the soil samples taken from the different depths of the fluvial deposits at various locations in the riverbank filtration area, Daesan-Myeon. The groundwater chemistry data were also collected from the equivalent depths with the soil samples at the boreholes in July and December, 2005. The relationships between the enrichment characteristics of Fe and Mn in the groundwater and the mineralogical and physicochemical properties of the fluvial deposits were carefully analyzed. The results indicate that the Fe and Mn contents in the groundwater vary with seasonally and show different enrichment behaviors.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.370-378
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• 2003

Continuous seismic refraction, reflection and echo-sounder surveys conducted at Koyna Project site provided geotechnical information which helped in choosing the alignment for Head race tunnel and in designing and choosing the site for Lake Tap. Seismic refraction survey both on land and in shallow water determined depths to bedrock and helped in inferring the bedrock quality. Seismic reflection survey mapped the subsurface stratigraphy with high resolution. Reservoir-bed and bedrock contours drawn from the results of the survey helped in choosing the tunnel alignment and the lake tap position cost effectively. It was inferred from the results of the survey that the geology and the quality of rock do not change unexpectedly around the site for extension of Head race tunnel and the lake tapping. The bedrock levels evaluated by seismic survey agreed remarkably well with those inferred in boreholes having Rock Quality Designation 90 percent or more.

• 한국환경과학회지
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• 제23권6호
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• pp.1101-1109
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• 2014

In this study we followed biofilm formation and development in a granular activated carbon (GAC) filter on pilot-scale during the 12 months of operation. GAC particles and water samples were sampled from four different depths (-5, -25, -50 and -90 cm from surface of GAC bed) and attached biomass were measured with adenosine tri-phosphate (ATP) analysis and heterotrophic plate count (HPC) method. The attached biomass accumulated rapidly on the GAC particles of top layer throughout all levels in the filter during the 160 days (BV 23,000) of operation and maintained a steady-state afterward. During steady-state, biomass (ATP and HPC) concentrations of top layer in the BAC filer were $2.1{\mu}g{\cdot}ATP/g{\cdot}GAC$ and $3.3{\times}10^8cells/g{\cdot}GAC$, and 85%, 83% and 99% of the influent total biodegradable dissolved organic carbon ($BDOC_{total}$), $BDOC_{slow}$ and $BDOC_{rapid}$ were removed, respectively. During steady-state process, biomass (ATP and HPC) concentrations of middle layer (-50 cm) and bottom layer (-90 cm) in the BAC filter were increased consistently. Biofilm development (growth rate) proceed highest rate in the top layer of filter (${\mu}_{ATP}=0.73day^{-1}$; ${\mu}_{HPC}=1,74day^{-1}$) and 78%~87% slower in the bottom layer (${\mu}_{ATP}=0.14day^{-1}$; ${\mu}_{HPC}=0.34day^{-1}$). This study shows that the combination of different analytical methods allows detailed quantification of the microbiological activity in drinking water biofilter.

• 한국음향학회지
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• 제37권1호
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• pp.21-30
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• 2018

수동 시역전 기법은 시공간적인 집속효과를 통해 다중경로 채널응답에 의한 인접 심볼간 간섭의 영향을 줄임으로써 수중통신 시스템의 오류 성능을 향상시킬 수 있는 방법이다. 이러한 수동 시역전 기법은 일반적으로 시역전 결합에 사용되는 수신신호가 많을수록 큰 공간 다이버시티 이득을 얻기 때문에 많은 수의 수신기를 사용할 때 우수한 통신 성능을 얻을 수 있다. 본 논문에서는 제한된 개수의 수신기를 사용하더라도 많은 수의 수신기를 사용할 때와 근접한 통신 성능을 얻을 수 있는 수신기의 개수와 조합에 대해 분석한다. 분석을 위해 2015년 5월에 제주 남서쪽 해역에서 수행된 SAVEX15(Shallow-water Acoustic Variability Experiment 2015) 실험 데이터를 활용한다. 음향채널이 존재하는 채널 특성 때문에 에너지가 집중되는 수심이 존재하였고 에너지가 집중되는 수심에 존재하는 수신기를 포함하여 수동 시역전 결합을 할 때, 일부의 수신기만을 사용하여 최적에 가까운 통신 성능을 도출할 수 있음을 보인다.

• Journal of Radiation Protection and Research
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• 제34권2호
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• pp.43-48
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• 2009

When the PDD (percentage depth dose) in the megavoltage beams is measured in the water phantom, the polarity and ion recombination effects of ionization chambers with depth in water are not usually taken into consideration. We try to investigate if those variations with depth should be taken into consideration or could be ignored for the thimble type semiflex ionization chamber (PTW $31010^{TM}$, SN 1551). According to the recommendation of IAEA TRS-398, the 4 representative depths of $d_s$, $d_{max}$, $d_{90}$ and $d_{50}$ were used for the electron beams. For the photon beams, the 4 depths were arbitrarily chosen for the photon beams, which were $d_s$, $d_{max}$, $d_{10}$ and $d_{20}$. For the high energy photon beam both polarity and ion recombination factors of the chamber with depth in water gives the good agreements within the maximum $\pm$0.2%, while the $C_{polS}$ with depth came within the maximum $\pm$ 0.4% and the $C_{IRS}$ within the maximum $\pm$0.6% in every electron beam used. This study shows that PDI (percentage depth ionization) could be a good approximation to PDD for the chamber used.