• Journal of Environmental Health Sciences
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• v.14 no.1
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• pp.23-32
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• 1988

A study was carried out to find distribution of Legionella spp. in hot water supplying systems of buildings in Seoul. Water samples were taken from the hot water taps in three research institute buildings during the period from the 2nd to 27th February, 1987. And all of the three buildings were supplied with hot water from the same central hot water tank. GVPC BCYEa and blood agar were used for the isolation of Legionella pneurnophila and slide agglutination test (SAT) was performed to identify their strain types. Main findings were as follows 1. 44 samples taken from hot tap-water revealed 20% of positive culture and 44 samples taken from hot water spouts revealed 11% of positive culture. 2. The 78% of positive samples taken from hot water was obtained from 25.1$\circ$C~45.0$\circ$C temperature range. 3. Only, Legionella pneumophila serogroup 3 was identified and most of them has been than 2$\mu$m in length. 4. The densities of the Legionella pneurnophila isolated from hot water samples were within the range of $1.0\times 10^2$ to $1.1\times 10^3$ CFU/l and their densities isolated from hot water spouts were either 1 CFU/plate or 2 CFU/plate.

• Journal of the korean society of oceanography
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• v.39 no.1
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• pp.46-56
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• 2004

Spectral attenuation of light and upwelling radiance were measured in the western coast of Korea on board the R/V Inchon 888 of the Korean National Fisheries Research and Development Institute(NFRDI) during four seasons. The goal of these efforts was to determine the spatial and temporal distribution of the inherent and apparent optical properties of the water, and the factors that control their distribution. Our data indicate that while stratification of the water column, phytoplankton, and wind stress determined the vertical distribution of the optical parameters offshore, it was the tidal current and sediment type that controlled both the vertical and horizontal distribution in the coastal areas. These findings led to the development of a model that estimates the spectral attenuation of light with respect to depth and time for the Yellow Sea. The model integrates water leaving radiance from satellites, sediment types, current vectors, sigma-t, bathymetry, and in situ optical measurements in a learning algorithm capable of extracting optical properties with only knowledge of the environmental conditions of the Yellow Sea. The performance of the model decreases with increase in depth. The mean absolute percentage error (MAPE) of the model is 2% for the upper five meters, 8-10% between 6 and 50 meters, and 15% below 51 meters.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.7 no.1
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• pp.9-27
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• 1971

Oceanography of the Subarctic North Pacific Ocean is reviewed. The submarine topography and the current systems in the region are explained. Recent serial observation data reveals that. though the upper mixed layer of low salinity is relatively thick. the pattern of the property distribution in winter is essencially similar to that in summer. Alaskan Stream Extension Water. which influences the abundance and the location of demersal fishes. extends northward to 58${\circ}$ N Lat in the Bering Sea. A southeastward intrusion of the Bering Borcal Cold Water causes the formation of a sharp oceanic front. where the demersal fishes such as Alaska pollacks and cods arc concentrated. The Alaska pollacks seem to avoid the low salinity water of the Alaskan Coastal Water.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.7 no.1
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• pp.8-8
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• 1971

Oceanography of the Subarctic North Pacific Ocean is reviewed. The submarine topography and the current systems in the region are explained. Recent serial observation data reveals that. though the upper mixed layer of low salinity is relatively thick. the pattern of the property distribution in winter is essencially similar to that in summer. Alaskan Stream Extension Water. which influences the abundance and the location of demersal fishes. extends northward to 58${\circ}$ N Lat in the Bering Sea. A southeastward intrusion of the Bering Borcal Cold Water causes the formation of a sharp oceanic front. where the demersal fishes such as Alaska pollacks and cods arc concentrated. The Alaska pollacks seem to avoid the low salinity water of the Alaskan Coastal Water.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.1
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• pp.46-51
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• 2007

Environmental contamination creates shortages of potable water. In such situations, the leakage of water due to breakage or aging of rubber valve seats is a serious problem. Rubber is apt to break when it is placed between two materials that contact each other. One way to avoid water leakage due to rubber damage and breakdown is to replace the rubber with metal, which is currently taking place in water distribution systems. In tribology, a severe form of wear is characterized by local macroscopic material transfer or removal, or by problems with sliding protrusions when two solid surfaces experience relative sliding under load. One of the major problems when metal slides is the occurrence of galling. Experimentally, various conditions influence incipient galling, such as hardness, surface roughness, temperature, load, velocity, and the external environment. This study sought to verify the galling tendencies of metal according to its hardness, surface roughness, load, and sliding velocity, and determine the quantitative effect of each factor on the galling tendencies.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1558-1562
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• 2007

To elucidate the influence of pipe materials on the VBNC (viable but nonculturable) state and bacterial numbers in drinking water, biofilm and effluent from stainless steel, galvanized iron, and polyvinyl chloride pipe wafers were analyzed. Although no HPC (heterotrophic plate count) was detected in the chlorinated influent of the model system, a DVC (direct viable count) still existed in the range between 3- and 4-log cells/ml. Significantly high numbers of HPC and DVC were found both in biofilm and in the effluent of the model system. The pipe material, exposure time, and the season were all relevant to the concentrations of VBNC and HPC bacteria detected. These findings indicate the importance of determining the number of VBNC cells and the type of pipe materials to estimate the HPC concentration in water distribution systems and thus the need of determining a DVC in evaluating disinfection efficiency.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.296-300
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• 2006

도시에 매설된 상수관망의 노후화와 매설된 주변 환경의 변화로 관 보수와 파괴가 자주 발생하게 된다. 이때 보수 또는 교체를 위하여 상수관망의 일부를 격리하여야 하며 이를 위해서 제수밸브를 차폐해야 한다. 그러나 제수밸브가 격리하고자 하는 영역 주변에 적절히 배치되어 있지 않은 경우 필요한 부분보다 많은 영역이 격리되게 되며, 이는 격리로 인한 피해범위를 증가시키게 된다. 이와 함께 적절치 못한 제수밸브 관리로 인해 제수밸브가 차폐되지 않는 경우 해당 제수밸브 주변에 위치한 제수밸브를 추가로 차폐해야 하는 경우가 발생하게 되며 추가적인 상수관의 격리로 인하여 처음의 상수관 격리에 의한 피해를 증가시키는 결과를 야기한다. 이러한 문제는 제수밸브의 효율적 배치로 감소할 수 있으나 효율적 배치를 위한 선행과제로 현재 설치되어 있는 제수밸브 배치의 적정성을 평가하는 것이 필요하다. 이를 위하여 본 연구에서는 상수관 격리와 제수밸브가 차폐되지 않는 경우를 동시에 고려한 모의방법(simulation)을 제안하였다. 상수관망 전체 대한 상수관 파괴당 평균적인 단수인구로 제수밸브의 적정 분포를 정량화하여 다양한 제수밸브 분포사이의 적정성을 비교할 수게 하였다. 이러한 비교를 바탕으로 새로운 상수관망에서 효율적인 제수밸브 분포가 가능하며 기존 상수관망에 제수밸브를 추가할 경우에도 유용한 결과를 얻을 수 있다.

• Journal of ILASS-Korea
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• v.8 no.2
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• pp.38-45
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• 2003

This study was carried on the combustion characteristics of a pure light oil and emulsified fuels at high-pressure injection in a spray combustion installation, The volume fractions of water in an emulsion were varied up to 30% and the injection pressures were 7.5, 100, 200, and $300kg_f/cm^2$. The concentrations of NOx and the average temperatures of flame were measured. And Images of OH radical using ICCD camera and instantaneous schlieren photography of flames were photographed. It was found that the temperature distribution of axial distance in the emulsified fuels was increased in the upstream and decreased in the down stream. The temperature distribution of radial distance was high at the peripheral regions of the spray in the upstream and at the central regions of spray in the downstream, The intensity of OH radical was denser at the water content 10% than at the pure light oil over the injection pressure $200kg_f/cm^2$.

• International Journal of Fluid Machinery and Systems
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• v.9 no.4
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• pp.287-299
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• 2016

In China, agricultural irrigation water often contains a lot of suspended sediment which may cause the nozzle wear. In this study, a new numerical simulation combing the Discrete Phase Model and a remeshing algorithm was conducted. The geometric boundary deformation caused by the erosion wear, was considered. The weight loss of the nozzle, the node displacement and the flow field were investigated and discussed. The timestep sensitivity analysis showed that the timestep is very critical in the erosion modeling due to the randomness and the discreteness of the erosion behavior. Based on the simulation results, the major deformation of the boundary wall due to the erosion was found at the corners between outlet portion and contraction portion. Based on this remeshing algorithm, the simulated erosion weight loss of the nozzle is 4.62% less compared with the case without boundary deformation. The boundary deformation changes the pressure and velocity distribution, and eventually changes the sediment distribution inside the nozzle. The average turbulence kinetic energy at the outlet orifice is found to decrease with the erosion time, which is believed to change the nozzle's spray performance eventually.

• Journal of Korea Water Resources Association
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• v.39 no.8 s.169
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• pp.669-676
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• 2006

Hydrological factors, especially the spatial distribution of interpretation on precipitation is often topic of interest in studying of water resource. The popular methods such as Thiessen method, inverse distance method, and isohyetal method are limited in calculating the spatial continuity and geographical characteristics. This study was intended to overcome those limitations with improved method that will yield higher accuracy. The monthly and yearly precipitation data were produced and compared with the observed daily precipitation to find correlation between them. They were then used as secondary variables in Co-kriging method, and the result was compared with the outcome of existing methods like inverse distance method and kriging method. The comparison of the data showed that the daily precipitation had high correlation with corresponding year's average monthly amounts of precipitation and the observed average monthly amounts of precipitation. Then the result from the application of these data for a Co-kriging method confirmed increased accuracy in the modeling of spatial distribution of precipitation, thus indirectly reducing inconsistency of the spatial distribution of hydrological factors other than precipitation.