• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.572-582
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• 1994

To investigate water mass structure and DO(Dissolved Oxygen) distribution in Chinhae Bay, temperature, salinity and DO were observed in the bay in summer and winter from 1990 to 1993, and two-dimensional tidal current and parameter log($H/U^3$) were computed. Shallow water fronts in the bay were formed in summer in Kaduk channel and the central part of the bay having log($H/U^3$) values of $2.0{\sim}2.5$. Oxygen deficiency at the bottom layer in summer occurred in the western and northern part of the bay with weak tidal current, where the value of log($H/U^3$) was more than about 3.5 and $M_2$ tidal current was less than about 20 cm/s. DO concentration at the bottom layer of Kaduk channel and the central channel of the bay having the strong tidal current was more than about 3.5 mg/l. The isolines of DO concentration were nearly parallel to the isovelocity, and the concentrations correlated with the frontal location. The frontal location and DO distribution were influenced by tidal range, river inflow and meteorological conditions, and also correlated with bottom slope characteristics.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.63-70
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• 2017

ZPP (Zirconium-Potassium Perchlorate) is type of primary charge initiators for PMD (Pyrotechnic Mechanical Device) system. The binder component dissolved in the solvent is precipitated to suspended particles in the granules. The LabRAM Mixer uses resonance phenomenon to transfer energy, unlike blade equipment that utilizes mechanical contact. In this study, the properties of the particles prepared by the LabRAM Mixer were evaluated with the changes of the conditions.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.4
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• pp.180-191
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• 2015

Marine environmental characteristics and primary productivity of phytoplankton were investigated in seaweed bed of northwestern coast of Jeju Island during Autumn, 2014. The trophic state based on dissolved inorganic nitrogen and phosphorus was mesotrophic. The Redfield ratio was less than 16, indicating that nitrogen was the limiting factor for the growth of phytoplankton. Dissolved organic nitrogen and phosphorus accounts for 63 and 46% of the dissolved total nitrogen and phosphorus, respectively. Light utilization efficiency (${\alpha}$) and maximum photosynthetic capacity ($P_m{^B}$) were highest in the Donggwi (third-year marine forest), followed by Gonae (one-year marine forest), Biyangdo (natural seaweed bed) and Geumneung (whitening area). The primary productivity of phytoplankton in the Donggwi, Gonae and Biyangdo also was higher than that in the Geumneung. Although nitrogen is the limiting factor, enriched dissolved organic nitrogen might play an important role to maintain primary productivity. In addition, phytoplankton community through photosynthesis could produce about 14% of phytoplankton carbon in one hour. These results will be able to use the important information for material cycle and ecological valuation of seaweed bed.

• Proceedings of the Korean Fiber Society Conference
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• 2000.04a
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• pp.41-44
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• 2000

• Journal of Korean Society of Water and Wastewater
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• v.20 no.5
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• pp.727-736
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• 2006

Granular activated carbon (GAC) has been identified as a best available technology (BAT) by the United States Environmental Protection Agency (USEPA) for removal disinfection by-product (DBP) precursors, such as dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). Rapid small-scale column test (RSSCT) were used to investigate four types of carbon (F400, Norit1240, Norit40S, and Aquasorb1500) for their affinity to absorb natural organic matter (NOM). DOC, $UV_{254}$, and Total dissolved nitrogen (TON) concentrations were measured in the column effluent to track GAC breakthrough. DOC and $UV_{254}$ breakthrough occurred at around 3500 bed volumes (BVs) of operation for all GACs investigated. The $UV_{254}$ breakthrough curves showed 33% to 48% at 8000 BVs, when the DOC was 48% to 65%. All GACs showed greater removal in DOC than $UV_{254}$. The NORIT1240 GAC was determined to have the highest adsorption capacity for DOC and $UV_{254}$. The removal of nitrate (NOTN) had not broken through over BVs. The initial TON breakthrough curves were started around 50%, when the DOC breakthrough was only 10 % at 500 BVs. The curves were gradually increased after 3500 BVs and approximately 69% through 81% of TON breakthrough occurred at 8000 BVs. All of the GACs were able to remove TON, in the case of this investigation the majority of the TON was present as DON. Because nitrate nitrogen was seldom removed and ammonium nitrogen ($NH_3-N$) was not detected in the effluent from RSSCTs even though raw water. The carbon usage rate of DOC was from 2 to 6 times less than that of TON. The NORIT1240 GAC demonstrated the best performance in terms of DOC removal, while the F400 GAC was best in terms of TON removal. Excitation emission matrix(EEM) analysis was used to show that GAC adsorption successfully removed most of Humic-like DOC and Fulvic-like DOCs. However, soluble microbial product(SMP)-like DOC in the absence of raw water were detected in the NORIT40S and Aquasorb1500 GAC. The authors assumed that this results is due probably to the part of GAC in the RSSCT which was converted into biological activated carbon(BAC). To compare with organics removal by GAC according to preloading, the virgin GACs had readily accessible sites that were adsorbed DOC more rapidly than preloaded GACs, but the TDN removal had not showed differences between those GACs.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.1
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• pp.53-64
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• 1995

A study was made to characterize the microstructures and mechanical properties of the base metal and the heat-affected zone(HAZ) in Cu-bearing HSLA-100 steel. The Gleeble thermal/mechanical simulator was used to simulated the weld HAZ. The relationship between microstructure and toughness of HAZ was studied by impact test, O. M, SEM, TEM, and DSC. The toughness requirement of military specification value was met in all test temperatures for the base metal. The decrease of HAZ toughness comparing to base plate is ascribed to the coarsed-grain and the formation of bainite. Obliquely sectioned Charpy specimens show that secondary crack propagate easily along bainite lath. Improved toughness(240J) at HAZ of $Tp_2=950^{\circ}C$ is due to the fine grain, and reasonable toughness(160~00J) in the intercritical reheated HZA is achieved by the addition of small amount of carbon which affects the formation of "M-A". Cu precipitated during ageing for increasing the strength of base metal is dissolved during single thermal cycle to $1,350^{\circ}C$ and is precipitated little on cooling and heating during subsequent weld thermal cycle. Thus, the decrease of toughness does not occur owing to the precipitation of Cu.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.4
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• pp.439-455
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• 2020

Numerical model was developed that simulates radionuclide (3H and 14C) transport modeling at the 2nd phase facility at the Wolsong LILW Disposal Center. Four scenarios were simulated with different assumptions about the integrity of the components of the barrier system. For the design case, the multi-barrier system was shown to be effective in diverting infiltration water around the vaults containing radioactive waste. Nevertheless, the volatile radionuclide 14C migrates outside the containment system and through the unsaturated zone, driven by gas diffusion. 3H is largely contained within the vaults where it decays, with small amounts being flushed out in the liquid state. Various scenarios were examined in which the integrity of the cover barrier system or that of the concrete were compromised. In the absence of any engineered barriers, 3H is washed out to the water table within the first 20 years. The release of 14C by gas diffusion is suppressed if percolation fluxes through the facility are high after a cover failure. However, the high fluxes lead to advective transport of 14C dissolved in the liquid state. The concrete container is an effective barrier, with approximately the same effectiveness as the cover.

• Journal of Soil and Groundwater Environment
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• v.22 no.3
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• pp.10-17
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• 2017

In this study, the evolution and origin of major dissolved constituents of crystalline bedrock groundwater in a coastal area were evaluated using multivariate statistical and groundwater quality analyses. The groundwater types mostly belonged to the $Na(Ca)-HCO_3$ and $Ca-HCO_3$ types, indicating the effect of cation exchange. Stable isotopes of water showed two areas divided by first and secondary evaporative effects, indicating a pattern of rapid hydrological cycling. Saturation indices of minerals showed undersaturation states. Thus, the degree of evolution of groundwater is suggested as in the low to intermediate stage, based on field and laboratory analytical conditions. According to the principal component analysis (PCA) results, the chemical components of EC, $Ca^{2+}$, $Mg^{2+}$, $K^+$, $HCO_3{^-}$, $SO{_4}^{2-}$ (PCA 1), $F^-$ (PCA 3), $SiO_2$ (PCA 4), and $Fe^{2+}$ (PCA 5) are derived from various water-rock interactions. However, $NO_3{^-}$, $Na^+$, and $Cl^-$ (PCA 2) represented the chemical characteristics of both anthropogenic sources and natural sea spray.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.893-899
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• 2024

In a secondary cooling system of a sodium-cooled fast reactor (SFR), rapid detection of hydrogen due to sodium-water reaction (SWR) caused by water leakage from a heat exchanger tube of a steam generator (SG) is important in terms of safety and property protection of the SFR. For hydrogen detection, the hydrogen detectors using atomic transmission phenomenon of hydrogen within Ni-membrane were used in Japanese proto-type SFR "Monju". However, during the plant operation, detection signals of water leakage were observed even in the situation without SWR concerning temperature up and down in the cooling system. For this reason, the study of a new hydrogen detector has been carried out to improve stability, accuracy and reliability. In this research, the authors focus on the difference in composition of hydrogen and the difference between the background hydrogen under normal plant operation and the one generated by SWR and theoretically estimate the hydrogen behavior in liquid sodium by using ultra-accelerated quantum chemical molecular dynamics (UA-QCMD). Based on the estimation, dissolved H or NaH, rather than molecular hydrogen (H₂), is the predominant form of the background hydrogen in liquid sodium in terms of energetical stability. On the other hand, it was found that hydrogen molecules produced by the sodium-water reaction can exist stably as a form of a fine bubble concerning some confinement mechanism such as a NaH layer on their surface. At the same time, we observed experimentally that the fine H₂ bubbles exist stably in the liquid sodium, longer than previously expected. This paper describes the comparison between the theoretical estimation and experimental results based on hydrogen form in sodium in the development of the new hydrogen detector in Japan.

• The Korean Journal of Archival Studies
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• no.51
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• pp.5-44
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• 2017

The institution, which was temporarily run, has not registered and has neglected records due to its temporality. In this regard, many related experts have pointed out their risk of loss. Therefore, the objective of this study is to analyze the problems of the temporary institution's records management system by investigating the current situation, and to suggest solutions, thereby arousing the necessity of managing the records produced by dissolved agencies. To specifically review this, first, this paper analyzes the records management system of abolished institutions, focusing on the working environment, related laws, and guidelines. Moreover, it indicates the problem with regard to the effectiveness of legal systems, the lack of professionalism and infrastructure for records management services in temporary agencies, and National Archives of Korea's passive response. With regard to these problems, there are some solutions presented such as the complementation of related laws and guidelines, the strengthening of professionalism in relevant agencies in relation to managing records properly, and the establishment of cooperative networks between related institutions.