• Nuclear Engineering and Technology
• /
• v.56 no.7
• /
• pp.2576-2583
• /
• 2024

In this paper, the similarity criterion and dimensionless conversion method combined with the elasticity condition and Hooke's law are used to derive the functional relationship of the maximum effective value of the vibration velocity between the prototype pump and the model pump. The seawater circulation pump of a nuclear power plant is used as the prototype pump, and the model pump is obtained by performance conversion and choosing the appropriate scale, and the vibration state of the model pump under different flow rates is measured and analyzed. The vibration data of the model pump through the function relationship to find out the vibration parameters of the prototype model pump, and compare with the vibration data of the seawater circulation pump in reality. It can be seen that with the increase of flow rate, the maximum effective value of the vibration velocity of both model and prototype decreases and then increases, and the relative error is small, the maximum value is 7.7757%. Therefore, it can be considered that the functional relationship of model pump converted to prototype pump derived in this paper can be used to analyze the vibration of the actual seawater circulation pump of coastal nuclear power plant.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 2003.08a
• /
• pp.110-117
• /
• 2003

해수교환방파제란 방파제에 설치된 통수구를 통해 해수가 항내로 일방향으로 유입되거나 통수구에서 양방향 흐름이 발생함으로써 종국에는 항내ㆍ외간의 해수교환이 활발하게 이루어지게 하는 방파제를 말한다. 그리고 방파제를 통한 순유입유량이 클수록 해수교환의 영향은 항내의 넓은 수역까지 미친다. (중략)

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 2003.08a
• /
• pp.118-123
• /
• 2003

재래식 방파제는 투수성이 작아 항내ㆍ외간 해수유통을 저하시켜 조석간만의 차가 작은 해역의 항만에서는 오염원이 유입될 때 수질이 쉽게 악화된다. 특히 방파제 후면 수역을 매립하여 선착장으로 이용하는 경우에 이 현상은 심화된다 이를 해결하려면 육상으로부터의 오염원 유입을 저감시킴과 함께 정체된 항에 흐름이 존재하도록 하는 건설 공법을 도입할 필요가 있다. (중략)

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 2003.08a
• /
• pp.298-302
• /
• 2003

재래식 방파제를 설치하여 조성한 항내 수역은 항내ㆍ외로 해수유통이 원활하게 일어나지 않는 폐쇄성 수역이 될 수가 있다. 이런 수역에 항내의 자정능력을 초과하는 오염원이 유입되면 수질이 악화되어 항내수는 사용하지 못하게 될 뿐 아니라 항 전체가 오염되어 주민들의 폐적한 생활공간이 훼손되며, 주민의 보건도 악영향을 받는다. 이를 해결할 수 있는 1차적인 방안은 항내로의 오염원을 줄여 나가며 바닥에 가라앉은 오염물을 준설하는 것이고, 2차적으로 해수유통을 원활하게 할 수 있는 해수교환시설을 설치하는 것이다. (중략)

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 2003.08a
• /
• pp.303-306
• /
• 2003

해수교환방파제 설치로 항내의 수질개선 효과를 기대하려면 방파제를 통해 항내로 순유입량이 발생되어야 한다. 순유입량이 발생되기 위해서는 방파제 전면의 최대수위 또는 평균수위가 증대되거나 방파제의 도수로 내에서 항외측으로 발생하는 흐름을 감소시켜야 한다. (중략)

• Economic and Environmental Geology
• /
• v.36 no.5
• /
• pp.365-374
• /
• 2003

Various deleterious chemicals can be introduced to existing concrete structures from various external sources. The deterioration of concrete by seawater attack is involved in complex processes due to various elements contained in seawater. In the present study, attention was paid to the formation of secondary minerals and characteristics of mineralogical and micro-structural changes involved in concrete deterioration caused by the influence of major seawater composition. The characteristics of deterioration occurred in existing concrete structures was carefully observed and samples were collected at many locations of coastal areas in Busan-Kyungnam. The petrographic, XRD, SEM/EDAX analyses were conducted to determine chemical, mineralogical and micro-structural changes in the aggregate and cement paste of samples. The experimental concrete deteriorations were performed using various chloride solutions (NaCl, CaCl, $MgCl_2$ and $Na_2SO_4$ solution. The experimental results were compared with the observation results in order to determine the effect of major elements in seawater on the deterioration. The alkalies in seawater appear to accelerate alkali-silica reaction (ASR). The gel formed by ASR is alkali-calcium-silica gel which known to cause severe expansion and cracking in concrete. Carbonation causes the formation of abundant less-cementitious calcite and weaken the cement paste. Progressive carbonation significantly affects on the composition and stability of some secondary minerals. Abundant gypsum generally occurs in concretes subjected to significant carbonation, but thaumasite ({$Ca_6/[Si(OH)_6]_2{\cdot}24H_2O$}${\cdot}[(SO_4)_2]{\cdot}[(CO_3))2]$) occurs as ettringite-thaumasite solid solution in concretes subjected to less significant carbonation. Experimentally, ettringite can be transformed to trichloroaluminate or decomposed by chloride ingress under controlled pH conditions. Mg ions in seawater cause cement paste deterioration by forming non-cementitious brucite and magnesium silicate hydrate (MSH).

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.30 no.6
• /
• pp.253-262
• /
• 2018

Oscillating Water Column (OWC) Wave Energy Converters (WEC) harness electricity through a Power-Take-Off (PTO) system from the induced-airflow by seawater oscillating inside a chamber. In general, an air chamber with a relatively small cross-sectional area is required compared to seawater chamber to obtain high-velocity air in the PTO system, and in order to simulate an accurate air flow rate in the air chamber, a three-dimensional study is required. In this study, the dynamic response of OWC-WEC that is equipped with the channel of seawater exchange for the case of irregular waves has been numerically studied. The open source CFD software, OLAFLOW for the simulation of wave dynamics to the openFOAM and FOAM-extend communities, was used to simulate the interaction between the device and irregular waves. Based on the numerical simulation results, we discussed the fluctuation characteristics of three dimensional air flow in the air-chamber, wave deformation around the structure and the seawater flow inside the channel of seawater exchange. The numerical results the maximum air flow velocity in the air-chamber increases as the Ursell value of the significant wave increases, and the velocity of airflow flowing out from the inside of air chamber to the outside is greater than the speed of flowing into the air chamber from the outside.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.26 no.1
• /
• pp.1-10
• /
• 2021

In this study, Information for the case of seawater flooding and observation data over a period of 10 years (2009~2018) was collected. Using machine learning algorithms, the characteristics of the types of seawater flooding and observations by type were classified. Information for the case of seawater flooding was collected from the reports of the Korea Hydrographic and Oceanographic Agency (KHOA) and the Korea Land and Geospatial Informatics Corporation. Observation data for ocean and meteorological were collected from the KHOA and the Korea Meteorological Agency (KMA). The classification of seawater flooding incidence types is largely categorized into four types, and into 5 development types through combination of 4 types. These types were able to distinguish the types of seawater flooding according to the marine weather environment. The main characteristics of each was classified into the following groups: tidal movement, low pressure system, strong wind, and typhoon. Besides, in consideration of the geographical characteristics of the ocean, the thresholds of ocean factors for seawater flooding by region and type were derived.

• Journal of Microbiology
• /
• v.45 no.1
• /
• pp.64-68
• /
• 2007

In this study we examined the multi-drug resistance profiles of the tetracycline (TC) resistant genus Vibrio to determine its susceptibility to two ${\beta}-lactams$, ampicillin (ABPC), and mecillinam (MPC), as well as to macrolide, erythromycin (EM). The results showed various patterns of resistance among strains that were isolated from very close geographical areas during the same year, suggesting diverse patterns of drug resistance in environmental bacteria from this area. In addition, the cross-resistance patterns suggested that the resistance determinants among Vibrio spp. are acquired differently within the sediment and seawater environments.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.6
• /
• pp.1098-1102
• /
• 2016

A green microalga, Tetraselmis sp., was cultivated in the coastal seawater of Young-Heung Island using semi-permeable membrane photobioreactors (SPM-PBRs) in different seasons. The microalgae in the SPM-PBRs were able to grow on nutrients diffused into the PBRs from the surrounding seawater through SPMs. The biomass productivity varied depending on the ion permeabilities of the SPMs and environmental conditions, whereas the quality and quantity of fatty acids were constant. The temperature of seawater had a greater influence than solar radiation did on productivity of Tetraselmis sp. in SPM-PBRs. SPM-PBRs could provide technologies for concurrent algal biomass and fatty acids production, and eutrophication reduction in the ocean.