• 한국물환경학회지
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• 제24권6호
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• pp.641-650
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• 2008

This paper reviews the infrastructure of the water supply and sewerage system in North Korea. North Korean has similar legal protection to preserve water environment that can be seen in Republic of Korea, but North Korean regulations seemed lack of detailed measures. The critical pollution problems of rivers and lakes in the northern part of peninsula is mainly due to the lack of sewage collection system and poor treatment works. It has been estimated that less than 20% of sewers are connected to the wastewater treatment plants. Although the availability of water resources seemed sufficient, North Koreans suffer the lack of the drinking water supply which needs an urgent attention. Based on the analysis, it has been suggested that the reconstruction of North Korean water and sewage infrastructure needs at least 17.5 trillion Korean Won.

• 한국양식학회지
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• 제5권1호
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• pp.81-91
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• 1992

해산동물의 종묘생산시 초기단계의 먹이로써 미세조류의 배양은 매우 중요하다. 그러나 자연으로부터 먹이생물로써 필요한 미세조류를 순수분리하여 순종을 보관하는 일은 일반 양식 업자나 이 분야에 종사하지 않는 연구자에게는 매우 어려운 일이다. 따라서 미세조류를 필요로 하는 사람들에게 순종의 미세조류 strain을 공급할 수 있는 은행의 설립이 필요하다. 본 연구에서는 capilla교 pipette법, 한천도말법, 희석법을 이용하여 한국연안에서 80종의 미세조류를 분리하였다. 현재 부산수산대학교 양식학과 실험실에서 확보 배양중인 117종의 미세조류의 배양현황을 보고하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.313-316
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• 2002

A grease filter is used to remove grease generated from a cooking appliance in a kitchen. This numerical study has been conducted to investigate the particle collection characteristics of a grease filter having nominal flowrate of $100m^{3}/h$. The flow field and particle trajectories in the grease filter with a flow chamber were simulated by using the commercial code of STAR-CD. The pressure drop of a grease filter rapidly increases with increasing the air flowrate. The numerical values of the pressure drop are slightly lower than the experimental values when the air flowrates are 50, 75, and $100m^{3}/h$. The particle collection efficiency of a grease filter increases with increasing the particle diameter and the air flowrate, which means that the inertial impaction is a dominant particle removal mechanism in a grease filter The cut-off diameter of the tested grease filter representing $50-{\%}$ collection efficiency is about $11.6{\mu}m$ for water droplets at $100m^{3}/h$.

• Journal of Microbiology and Biotechnology
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• 제24권3호
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• pp.334-336
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• 2014

A new species named Aspergillus cumulatus sp. nov. is described in Aspergillus section Aspergillus (Eurotium state). The type strain (KACC $47316^T$) of this species was isolated from rice straw used in meju fermentations in Korea, and other strains were isolated from the air in a meju fermentation room. The species is characterized by growth at a wide range of water activities and the formation of aerial hyphae on malt extract 60% sucrose agar (ME60S) that resemble a cumulus cloud. Furthermore, A. cumulatus produces yellow ascomata containing small lenticular ascospores (5.1-5.7 ${\mu}m$) with a wide furrow, low equatorial crests, and tuberculate convex surface. The species is phylogenetically distinct from the other reported Aspergillus section Aspergillus species based on multilocus sequence typing using rDNA-ITS, ${\beta}$-tubulin, calmodulin, and RNA polymerase II genes.

• 한국방재학회 논문집
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• 제8권1호
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• pp.103-108
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• 2008

Riverbed change is greatly influenced by artificial factors such as dam construction, gravel collection, and river improvement. This study simulated a long-term bed change based on the GSTARS3 model using actual data from the area downstream of the Geum River Daecheong Dam and compared the estimation with a section of the actual measurement. As a result, it was found that the section of the actual measurement was far lower than the result of the simulation in terms of long-term bed change. While the area downstream of Daecheong Dam displayed approximately an average of 2.29 m of streambed degradation on average while the upper stream area showed approximately 0.63 m of bed degradation over 24 years. In the simulation of the area downstream of Daecheong Dam based on the GSTARS3 model, similar bed degradation was observed. However, a great difference was detected between the result and the actual measurement. According to the cause analysis, the riverbed in the area downstream of Daecheong Dam has continuously degraded due to the dam construction and mass collection of gravel. The mass collection of gravel was the main cause of riverbed change. It was found that about 76% of all riverbed degradation was caused by the mass collection of gravel.

• 설비공학논문집
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• 제15권8호
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• pp.619-629
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• 2003

A grease filter is used to remove grease generated from a cooking appliance in a kitchen. Since the inertial impaction is a dominant particle removal mechanism of the grease filter, the performance of the filter is greatly affected by the geometry. This numerical study has been conducted to investigate the effect of geometry on the performance of grease filters for four models having nominal flowrate of 100 m$^3$/h. Four models were designed by changing the shape of impaction surface, the length of eyelid, and the number of eyelids of the grease filter. The flow field and particle trajectories in the grease filter with a flow chamber were simulated using the commercial code of STAR-CD. The difference of air velocity and pressure distributions among four models was discussed in detail. The collection efficiency curves and the pressure drops of four models were also compared. It was found that the grease filter model with flat top surfaces shows highest performance among four models, having high particle collection efficiency and relatively low pressure drop. The cutoff diameter of this model representing 50-% collection efficiency is about 7.1 ${\mu}{\textrm}{m}$ for water droplets at 100 m$^3$/h.

• ALGAE
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• 제26권2호
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• pp.181-192
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• 2011

Ballasting and deballasting of shipping vessels in foreign ports have been reported worldwide as a vector of introduction of non-native aquatic plants and animals. Recently, attention has turned to ballast water as a factor in the global increase of harmful algal blooms (HABs). Many species of microalgae, including harmful dinoflagellate species, can remain viable for months in dormant benthic stages (cysts) in ballast sediments. Over a period of four years, we surveyed ballast water and sediment of ships docked in two ports of Tampa Bay, Florida, USA. Sampling conditions encountered while sampling ballast water and sediments were vastly different between vessels. Since no single sample collection protocol could be applied, existing methods for sampling ballast were modified and new methods created to reduce time and labor necessary for the collection of high-quality, qualitative samples. Five methods were refined or developed, including one that allowed for a directed intake of water and sediments. From 63 samples, 1,633 dinoflagellate cysts and cyst-like cells were recovered. A native, cyst-forming, harmful dinoflagellate, Alexandrium balechii (Steidinger) F. J. R. Taylor, was collected, isolated, and cultured from the same vessel six months apart, indicating that ships exchanging ballast water in Tampa Bay have the potential to transport HAB species to other ports with similar ecologies, exposing them to non-native, potentially toxic blooms.

• 설비공학논문집
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• 제19권6호
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• pp.464-469
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• 2007

The case study aims to propose the green remodeling strategies of water system in Jeju international airport facilities considering the environmental conditions of Jeju Island. The rain water was proposed as an alternative water source to conserve of under ground water resources. Computations of daily precipitation, rain collection, runoff and water usage was conducted to investigated the feasibility of the rain water system design.

• 한국초지조사료학회지
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• 제38권4호
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• pp.349-356
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• 2018

The objective of this study was to determine the effect of goat grazing on the surface water quality of the alpine grasslands. Seven sites were selected across the goat farm for water sample collection and analysis. Samples were analyzed for BOD (Biological oxygen demand), total nitrogen, total phosphorous, electrical conductivity and water turbidity. All the above-mentioned parameters remained below the standard limit of Korean government at the end site. Puddles showed higher values, but below standard, as stagnant water has lower physico-chemical properties as of flowing water. The present study clearly showed that goat grazing doesn't affect water quality in grasslands if grazing is according to carrying capacity of grassland and fertilizer application is judicious.

• 상하수도학회지
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• 제37권4호
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• pp.215-229
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• 2023

In this study, non-destructive technologies that can be applied to evaluate the integrity of valve materials, safety against internal pressure caused by corrosion, and the blocking function of large-diameter water valves during operation without requiring specimen collection or manpower entering the inside of the valve were tested to assess the reliability of the technologies and their suitability for field application. The results showed that the condition of the graphite structure inside the valve body can be evaluated directly through the optical microscope in the field without specimen collection for large-diameter water butterfly valves, and the depth of corrosion inside the valve body can be determined by array ultrasound and the tensile strength can be measured by instrumented indentation test. The reliability of each of these non-destructive techniques is high, and they can be widely used to evaluate the condition of steel or cast iron pipes that are significantly smaller in thickness than valves. Evaluation of blocking function of the valves with mixed gas showed that it can be detected even when a very low flow rate of mixed gas passes through the disk along with the water flow. Finally, as a result of evaluating the field applicability of non-destructive technologies for three old butterfly valves installed in the US industrial water pipeline, it was found that it is possible to check the material and determine the suitability of large-diameter water valves without taking samples, and to determine the corrosion state and mechanical strength. In addition, it was possible to evaluate safety through the measurement results, and it is judged that the evaluation of the blocking function using mixed gas will help strengthen preventive response in the event of an accident.