• 한국식품위생안전성학회지
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• 제14권1호
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• pp.115-121
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• 1999

The effect of storage temperature and time on the contents of metal (Pb, Sn and Fe), vitamin C, color and pH was studied for canned pineapple juice (PJ) and pineapple slice (PS) which were stored for 120 hours at 5 and 2$0^{\circ}C$ and analyzed at 24 hours intervals. The results are as follows; 1. The metal contents of PJ and PS were in the rank of 24<48<72<96<120 hours by storage time at 5 and 2$0^{\circ}C$. These contents were increased to 44.1%/24 hrs of Ph, 18.0%/24 hrs of Sn, 34.6%/24 hrs of Fe but decreased to 6.0%/24 hrs of vitamin C in PJ and PS during 120 hrs. Storage times were correlation to contents of metal and pH but was not correlation to vitamin C contents. These were increased to 37.7%/24 hrs of Pb, 18.8%/24 hrs of Sn, 34.6%/24 hrs of Fe, but decreased to 6.0%/24 hrs of vitamin C. 2. These were increased to 10.6% of Pb, 3.7% of Sn, 11.3% of Fe in PJ and to 33.7% of Pb, 4.8% of Sn, 37.6% of Fe in PS at 2$0^{\circ}C$ than 5$^{\circ}C$ but vitamin C contents were decreased to 8.2% in PJ and 2.7% in PS at 2$0^{\circ}C$ than 5$^{\circ}C$. This fact suggests that more attention be paid in handling canned PJ and PS after opening in order to avoid the decreasing vitamin C and the hazard from Pb, Sn, Fe. 3. Changing factors in Pb, Sn, Fe and vatiamin C content were in the rank of storage temperature$0^{\circ}C$.

• 한국식품위생안전성학회지
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• 제12권1호
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• pp.15-19
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• 1997

The stability of monascin yellow pigment isolated from Monascus purpureus was determined over a period of storage for the wide range of pH, various metal ions and antioxidants. The absorption maximum of monascin pigment was 385 nm. Monascin pigment was more stable in acid solutions than in alkaline (pH 9 and pH 11) during storage period. It was also observed the reduction of absorption was occur after 3 days storage. The stability of monascin pigment was not changed by adding the various metal ions of the concentration of 10-4 M, however, it was unstable by adding the Zn2+, Al3+ and Fe3+ of 103- M concentration. The antioxidants. BHA, BHT, cysteine and L-ascorbic acid, have no effects on the stability of monascin yellow pigment. Thus, it may be concluded that the monascin pigment is stable and useful food additives as the natural colorant except for the alkaline food and food containing the Zn2+, Al3+ and Fe3+.

• 한국수소및신에너지학회논문집
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• 제23권5호
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• pp.429-436
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• 2012

Mg and Mg-based alloys are regarded as strong candidate hydrogen storage materials since their hydrogen capacity exceeds that of known metal hydrides. One of the approaches to improve kinetic is addition of metal oxide. In this paper, we tried to improve the hydrogenation properties of Mg-based hydrogen storage composites. The effect of transition metal oxides, such as $Nb_2O_5$ on the kinetics of the Magnesium hydrogen absorption kinetics was investigated. $MgH_x$-5wt.% $Nb_2O_5$ composites have been synthesized by hydrogen induced mechanical alloying. The powder fabricated was characterized by X-ray diffraction (XRD), Field Emission-Scanning Electron Microscopy (Fe-SEM), Energy Dispersive X-ray (EDX), BET and simultaneous Thermo Gravimetric Analysis / Differential Scanning Calorimetry (TG/DSC) analysis. The Absorption / desorption kinetics of $MgH_x$-5wt.% $Nb_2O_5$ (type I and II) are determined at 423, 473, 523, 573 and 623 K.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1719-1721
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• 2012

We have investigated the $H_2$ adsorption structures and binding energies of the metal (M)-doped (M = Li, Na, K, Mg, and Al) silicon complexes, $M-Si_{19}H_{11}$ and $M-Si_{24}H_{12}$, using density functional calculations. Alkali metals are preferred as doping elements because the Mg-Si and Al-$H_2$ interactions are weak. The maximum numbers of $H_2$ molecules that can be adsorbed are four and five for M=Li and K, respectively. We propose that the K-decorated silicon material might be an effective hydrogen storage material with high hydrogen capacity and high reversibility.

• 한국수소및신에너지학회논문집
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• 제19권5호
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• pp.377-385
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• 2008

최근 수소 저장물질로서 금속-유기 골격체(metal-organic frameworks; MOFs)가 주목을 받고 있으나 상온에서의 수소 저장성능이 낮은 문제점을 가지고 있어 이를 개선하기 위한 노력들이 필요하다. 본 연구에서는 MOF-5 및 제올라이트 Y로부터 합성된 마이크로다공성 카본을 합성하여 상온 및 약 80 bar에서 수소 저장성능을 측정하였으며, 그 결과 이들의 수소 저장성능은 각각 0.77 및 0.59 wt%였다. 이에 두 물질의 수소 저장성능을 향상시키기 위하여 5 wt% 백금을 각각의 물질에 담지시켜 백금이 없는 물질에 비하여 1.21 내지 1.25배의 개선 효과를 얻을 수 있었다. 한편 수소 spillover 현상을 활용하기 위하여 MOF-5 및 Pt/마이크로다공성 카본을 sucrose와 함께 탄화시킨 결과, 최종 하이브리드 물질이 상온 및 약 82 bar에서 0.93 wt%의 수소 저장성능을 보였으며, 이는 백금에 의하여 흡착된 수소 원자가 MOF-5 및 마이크로다공성 카본으로 이동하여 저장되는 것으로 해석된다.

• 생약학회지
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• 제44권2호
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• pp.200-208
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• 2013

The aim of this study was to evaluate the shelf-life of Bojungikgi-tang (Buzhongyiqi-tang in Chinese) by long-term storage test. Experiments were performed to evaluate the stability such as the selected physicochemical, pH, identification, heavy metal, microbiological experiment, and amount of marker compounds under a long-term storage test of Bojungikgi-tang decoction. The significant change was not showed in pH, heavy metal, microbiological, and identification test based on long-term storage test. Furthermore, the HPLC analysis was performed for the determinations of liquiritin, glycyrrhizin, nodakenin, and hesperidin in Bojungikgi-tang by long-term storage test. We were calculated shelf-life of Bojungikgi-tang decoction based on the amount change of four constituents. Consequently, Shelf-life by four compounds at room temperature was predicted 23 month. The suggested shelf-life would be helpful on the storage and distribution of herbal medicine.

• Advances in Energy Research
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• 제4권2호
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• pp.177-187
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• 2016

Ammonia borane $NH_3BH_3$ solubilized in organic solvent is a potential liquid-state chemical hydrogen storage material. In this study, metal acetylacetonates like $Fe(O_2C_5H_7)_3$, $Co(O_2C_5H_7)_2$, $Ni(O_2C_5H_7)_2$, $Pd(O_2C_5H_7)_2$, $Pt(O_2C_5H_7)_2$ and $Ru(O_2C_5H_7)_3$ are considered for assisting dehydrocoupling of ammonia borane in diglyme (0.135 M) at $50^{\circ}C$. The molar ratio between ammonia borane and metal acetylacetonate is fixed at 100. A protocol for the separation of the soluble and insoluble fractions present in the slurry is proposed; it consists in using acetonitrile to make the precipitation of metal-based compounds easier and to solubilize boron-based intermediates/products. The nature of the metal does not affect the dehydrocoupling mechanisms, the $^{11}B\{^1H\}$ NMR spectra showing the formation of the same reaction intermediates. The aforementioned metal acetylacetonates do mainly have effect on the kinetics of dehydrocoupling. Dehydrocoupling takes place heterogeneously and dehydrogenation of ammonia borane in these conditions leads to the formation of polyborazylene via intermediates like e.g., B-(cyclodiborazanyl) amine-borane and borazine. Our main results are reported and discussed herein.

• 전자통신동향분석
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• 제39권1호
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• pp.83-94
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• 2024

There have been continuous requirements for developing more reliable energy storage systems that could address unsolved problems in conventional lithium-ion batteries (LIBs) and thus be a proper option for large-scale applications like energy storage system (ESS). As a promising solution, aqueous metal-ion batteries (AMIBs) where water is used as a primary electrolyte solvent, have been emerging owing to excellent safety, cost-effectiveness, and eco-friendly feature. Particularly, AMIBs adopting mutivalence metal ions (Ca²⁺, Mg²⁺, Zn²⁺, and Al³⁺) as mobile charge carriers has been paid much attention because of their abundance on globe and high volumetric capacity. In this research trend review, one of the most popular AMIBs, zinc-ion batteries (ZIBs), will be discussed. Since it is well-known that ZIBs suffer from various (electro) chemical/physical side reactions, we introduce the challenges and recent advances in the study of ZIBs mainly focusing on widening the electrochemical window of aqueous electrolytes as well as improving electrochemical properties of cathode, and anode materials.

• 한국재료학회지
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• 제22권3호
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• pp.159-167
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• 2012

Hydrogen is in the spotlight as an alternative next generation energy source for the replacement of fossil fuels because it has high specific energy density and emits almost no pollution, with zero $CO_2$ emission. In order to use hydrogen safely, reliable storage and transportation methods are required. Recently, solid hydrogen storage systems using metal hydrides have been under extensive development for application to fuel cell vehicles and fuel cells of MCFC and SOFC. For the practical use of hydrogen on a commercial basis, hydrogen storage materials should satisfy several requirements such as 1) hydrogen storage capacity of more than 6.5wt.% $H_2$, moderate hydrogen release temperature below $100^{\circ}C$, 3) cyclic reversibility of hydrogen absorption/desorption, 4) non toxicity and low price. Among the candidate materials, Li based metal hydrides are known to be promising materials with high practical potential in view of the above requirements. This paper reviews the characteristics and recent R&D trends of Li based complex hydrides, Li-alanates, Li-borohydrides, and Li-amides/imides.

• Nuclear Engineering and Technology
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• 제46권4호
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• pp.547-556
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• 2014

Korea expects a shortage in storage capacity for spent fuels at reactor sites. Therefore, a need for more metal and/or concrete casks for storage systems is anticipated for either the reactor site or away from the reactor for interim storage. For the purpose of interim storage and transportation, a dual purpose metal cask that can load 21 spent fuel assemblies is being developed by Korea Radioactive Waste Management Corporation (KRMC) in Korea. At first the gamma and neutron flux for the design basis fuel were determined assuming in-core environment (the temperature, pressure, etc. of the moderator, boron, cladding, $UO_2$ pellets) in which the design basis fuel is loaded, as input data. The evaluation simulated burnup up to 45,000 MWD/MTU and decay during ten years of cooling using the SAS2H/OGIGEN-S module of the SCALE5.1 system. The results from the source term evaluation were used as input data for the final shielding evaluation utilizing the MCNP Code, which yielded the effective dose rate. The design of the cask is based on the safety requirements for normal storage conditions under 10 CFR Part 72. A radiation shielding analysis of the metal storage cask optimized for loading 21 design basis fuels was performed for two cases; one for a single cask and the other for a $2{\times}10$ cask array. For the single cask, dose rates at the external surface of the metal cask, 1m and 2m away from the cask surface, were evaluated. For the $2{\times}10$ cask array, dose rates at the center point of the array and at the center of the casks' height were evaluated. The results of the shielding analysis for the single cask show that dose rates were considerably higher at the lower side (from the bottom of the cask to the bottom of the neutron shielding) of the cask, at over 2mSv/hr at the external surface of the cask. However, this is not considered to be a significant issue since additional shielding will be installed at the storage facility. The shielding analysis results for the $2{\times}10$ cask array showed exponential decrease with distance off the sources. The controlled area boundary was calculated to be approximately 280m from the array, with a dose rate of 25mrem/yr. Actual dose rates within the controlled area boundary will be lower than 25mrem/yr, due to the decay of radioactivity of spent fuel in storage.