• Tribology and Lubricants
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• 제34권5호
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• pp.197-207
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• 2018

Thermal deterioration of fuel due to long-term storage influences engine performance and causes malfunctions. Fuel stability is usually evaluated via heat resistance and thermal stability during a brief heat shock at high temperature; storage stability in this scenario means that there is very little change in the quality of the fuel during long-term storage. In addition, rubber-based products such as oil seals, O-rings, and rubber hoses can influence the quality of the fuel. When these rubber products are in contact with fuel, they can swell, mechanically weaken, and occasionally crack, thus leaking low molar weight rubber and additives including plasticizer and antioxidant into the fuel to degrade its properties and shorten its useful lifetime. This study determines the thermal stabilities of three kinds of synthetic fuels by evaluating their low temperature kinematic viscosities, chemical composition changes via GC analyses, gross heat of combustion, and color changes. We evaluate the compression set of O-rings by immersing one NBR and two FKM rubber O-rings in the three synthetic fuel samples in airtight containers at variable storage temperatures for six months; from this, we estimate the lifetimes of the O-rings using the Power law model. There were very little changes in the chemical compositions and gross heat of combustion after six months of the experiment. The lifetimes are thus dependent on the materials of the rubber products, and in particular, the FKM O-ring was calculated to have a theoretical lifetime of 200 to 5,700 years. These results indicate that the synthetic fuels maintain their physical properties even after long-term storage at high temperatures, and the FKM O-ring is suitable for long-term sealing of these fuels.

• 방사성폐기물학회지
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• 제19권2호
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• pp.205-214
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• 2021

Currently, the interim storage pools of spent fuels in South Korea are expected to become saturated from 2024. It is required to prepare an operation plan of a domestic dry storage facility during a long-term period, with the researches on safety evaluation methods. This study modified the FRAPCON code to predict the spent fuel integrity evaluation such as the axial cladding temperature, the hoop stress and hydrogen distribution in dry storage. The cladding temperature in dry storage was calculated using the COBRA-SFS code with the burnup information which was calculated using the FRAPCON code. The hoop stress was calculated using the ideal gas equation with spent fuel information such as rod internal pressure. Numerical analysis method was used to calculate the degree of hydrogen diffusion according to the hydrogen concentration and temperature distribution during a dry storage period. Before 50 years of dry storage, the cladding temperature and hoop stress decreased rapidly. However, after 50 years, they decreased gradually and the cladding temperature was below 400 K. The initial temperature distribution and hydrogen concentration showed a parabolic line, but hydrogen was transferred by the hydrogen concentration and temperature gradient over time.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1178-1182
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• 2005

Survival of thermotolerant Lactobacillus reuteri KUB-AC5 in $20\%$ (w/v) skim milk was found to be $11.3\%$ after spray drying by using a pilot scale spray dryer with inlet temperature at $170^{\circ}C$ and outlet temperature at $85^{\circ}C$. The ability of dried cell to produce antimicrobial activity was not affected by the spray drying. The model system for predicting viability of spray-dried L. reuteri KUB-AC5 during long-term storage was established, based on the Arrhenius equation, and verified by experimental data, because the viability of cells during storage can be correlated with storage temperature. The viability during storage at $30^{\circ}C$ declined more rapidly than that storage at $4^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• 제32권12호
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• pp.1599-1604
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• 2022

Storage stability of freeze-dried lactic acid bacteria is a critical factor for their cost-effectiveness. Long-term storage of lactic acid bacteria enables microbial industry to reduce distribution costs. Herein, we investigated the effect of cold adaptation under supercooling conditions at -5℃ on the viability of Leuconostoc mesenteroides WiKim32 during the freeze-drying process and subsequent storage. Cold adaptation increased the thickness of exopolysaccharides (EPS) and improved the viability of freeze-dried Leu. mesenteroides WiKim32. Compared to non-adapted cells, cold-adapted cells showed a 35.4% increase in EPS thickness under supercooling conditions. The viability of EPS-hydrolyzed cells was lower than that of untreated cells, implying that EPS plays a role in protection during the freeze-drying process. Cold adaptation increased the storage stability of freeze-dried Leu. mesenteroides WiKim32. Fifty-six days after storage, the highest viability (71.3%) was achieved with cold adaptation at -5℃. When EPS-containing broth was added prior to the freeze-drying process, the viability further increased to 82.7%. These results imply that cold adaptation by supercooling pretreatment would be a good strategy for the long-term storage of Leu. mesenteroides WiKim32.

• 방사성폐기물학회지
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• 제22권1호
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• pp.1-7
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• 2024

In this research, a detailed analysis of the decay heat contributions of both actinides and non-actinides (fission fragments) from spent nuclear fuel (SNF) was made after 50 GWd·tHM^-1 burnup of fresh uranium fuel with 4.5% enrichment lasted for 1,350 days. The calculations were made for a long storage period of 300 years divided into four sections 1, 10, 100, and 300 years so that we could study the decay heat and physical disposal ratios of radioactive waste in medium- and long-term storage periods. Fresh fuel burnup calculations were made using the code MCNP, while isotopic content and then decay heat were calculated using the built-in stiff equation solver in the MATLAB code. It is noted that only around 12 isotopes contribute more than 90% of the decay heat at all times. It is also noted that the contribution of actinides persists and is the dominant ether despite decreasing decay heat, while the effect of fission products decreases at a very rapid rate after about 40 years of storage.

• 방사성폐기물학회지
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• 제21권4호
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• pp.531-541
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• 2023

The Wolsong Nuclear Power Plant (NPP) operates an on-site spent fuel dry storage facility using concrete silo and vertical module systems. This facility must be safely maintained until the spent nuclear fuel (SNF) is transferred to an external interim or final disposal facility, aligning with national policies on spent nuclear fuel management. The concrete silo system, operational since 1992, requires an aging management review for its long-term operation and potential license renewal. This involves comparing aging management programs of different dry storage systems against the U.S. NRC's guidelines for license renewal of spent nuclear fuel dry storage facilities and the U.S. DOE's program for long-term storage. Based on this comparison, a specific aging management program for the silo system was developed. Furthermore, the facility's current practices-periodic checks of surface dose rate, contamination, weld integrity, leakage, surface and groundwater, cumulative dose, and concrete structure-were evaluated for their suitability in managing the silo system's aging. Based on this review, several improvements were proposed.

• 한국기록관리학회지
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• 제14권2호
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• pp.117-128
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• 2014

최근에는 소셜 네트워크 서비스(SNS)가 큰 인기를 얻고 있으며, SNS중에서도 페이스북이 가장 활발히 사용되고 있다. 페이스북의 경우는 대한민국 모든 정부 부처에서 페이스북 페이지로서 운영되고 있으며, 정책 방향을 알리거나, 이에 대한 국민들의 의견들을 수렴하는데 이용하고 있다. 이러한 정보들은 향후 정책에 반영되거나 국민들의 여론을 파악하는 데 매우 중요한 가치를 지니고 있으며, 역사적으로도 매우 주요한 정보로서 장기보존을 해야 할 가치를 가진다. 해외의 경우에는 페이스북 기록물들을 장기보존하기 위한 도구들이 개발되고 있다. 그러나 이들 도구들은 페이스북내의 모든 데이터를 저장하지 못하며, 장기보존을 위한 원칙들을 무시함으로서 단순한 백업에 그친다. 따라서 본 논문에서는 정부부처의 페이스북 페이지에 대해 OAIS 참조 모델에 기반을 두어 수집 보존 재현 방법에 대해 연구하려 한다.

• Nuclear Engineering and Technology
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• 제45권4호
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• pp.421-426
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• 2013

The need for extended storage of used nuclear fuel is increasing globally as disposition schedules for used fuel are pushed further into the future. This is creating a situation where dry storage of used fuel may need to be extended beyond normal regulatory licensing periods. While it is generally accepted that used fuel in dry storage will remain in a safe condition, there is little data that demonstrate used fuel performance in dry storage environments for long periods of time. This is especially true for high burnup used fuel. This paper discusses a technical approach that defines a process that develops the technical basis for demonstrating the safety of used fuel over extended periods of time.

• 한국버섯학회지
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• 제12권1호
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• pp.29-34
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• 2014

본 연구는 다양한 조건에서 장기 보존한 느티만가닥버섯 균주의 균사 생존력과 재배성능 검증을 수행하였다. 균사 생존력은 장기 보존된 균주를 9, 21, 33, 45개월 단위로 해동하여 PDA 평판배지에 접종한 다음 1, 2, 3, 4, 5차 계대배양에 따른 균사 생장길이를 측정하여 검증하였다. 액체질소에 보존한 균사를 해동 직후 실시한 1차 계대배양에서는 동결보호제로써 Glycerol 10%를 단용으로 처리한 실험구에서 균사생장이 저조한 결과를 나타내었으나, 5차 계대배양에서는 버섯 균사의 생장력이 다른 실험구와 동일한 수준으로 회복되어, 저장방법에 따른 균사의 생존력에는 큰 영향이 없는것으로 판단된다. 그러나 느티만가닥버섯을 액체 질소에 장기간 보존하고자 할 때는 동결보호제로 사용되는 Glycerol 10%에 Trehalose 5%를 첨가하여 보존해야 균사의 생존력을 유지하는데 도움이 된다. 장기 저장에 따른 느티만가닥버섯 균주의 재배 성능 시험에서는 $4^{\circ}C$ 사면배지에 보호제로써 mineral oil을 사용하는 것이 사면배지 자체로 보존하는 것에 비해 수확량이 감소하는 결과를 나타내므로 장기 저장시에 mineral oil을 사용하는 것은 지양해야 할 것으로 판단된다.

• 한국연초학회지
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• 제14권1호
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• pp.57-65
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• 1992

The quality of cut tobacco will be deteriorated due to weather conditions such as temperature and relative humidity, when shipping and long term storaging. The change of equilibrium moisture contents in cut tobacco were under influence of relative humidity and temperature but not humectants. Therefore internal packing materials are necessary for cut tobacco to maintain initial quality, including taste, flavour and musty smell during shipping or storaging. When packing cut tobacco for shipping or long term storaging, desiralbe packing density was 200/$m^2$, For the long term storage under R.H 90% and 3$0^{\circ}C$, polyethylene film thickness suitable for packing material are above 100$\mu$, which resulted in 42days of shelf life.