• Korean Journal of Food Science and Technology
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• v.12 no.1
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• pp.34-40
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• 1980

In order to establish the frozen storage method of pork and contribute to the stabilization of pork price physicochemical changes and sensory evaluation of pork, stored at $-20^{\circ}C$ up to the period of 12 months, were analyzed every three months. The drip loss of frozen meat cuts was below 1% regardless of storage months. In the course of storage, pH of frozen half carcass rose a little, while that of meat cuts remained almost the same. WHC(water holding capacity) of frozen half carcass and meat cuts was in the range of $50{\sim}60\;and\;55{\sim}62%,$ respectively and VBN (volatile basic nitrogen) was about $11{\sim}18mg%,$ all of which did considerably change during the storage. TBA(thiobarbituric acid) value was not increased up to the 6th month of storage, but represented a considerable increase after the 9th month of storage, Both tenderness and juiciness of frozen pork were decreased after the 12th month of storage but the axxrptability of frozen pork to the consumers turned out fairly good.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.153-163
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• 2020

Compared to gaeous hydrogen, liquid hydrogen has approximately 1/800 volume, 800 times higher volumetric energy density at the same pressure, and the advantage of lower explosion risk and easier transportation than gaseous hydrogen. However, hydrogen liquefaction requires larger scale facility investment than simple compression storage method. Therefore, the research on energy-saving hydrogen liquefaction processes is highly necessary. In this study, helium/neon (mole ratio 80 : 20) refrigeration cycle was investigated as the main refrigeration process for hydrogen liquefaction. Process simulation for less energy consumption were carried out using PRO/II with PROVISION V10.2 of AVEVA. For hydrogen liquefaction, energy consumption was compared in three cases: Using a helium/neon refrigerant cycle, a SMR+helium/neon refrigerant cycle, and a C3-MR+helium/neon refrigerant cycle. As a result, the total power consumptions of compressors required to liquefy 1 kg of hydrogen are 16.3, 7.03 and 6.64 kWh, respectively. Therefore, it can be deduced that energy usage is greatly reduced in the hydrogen liquefaction process when the pre-cooling is performed using the SMR process or the C3MR process, which have already been commercialized, rather than using only the helium/neon refrigeration cycle for the hydrogen liquefaction process.