• Journal of Biosystems Engineering
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• 제25권4호
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• pp.279-286
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• 2000

Most of the domestic cold storage rooms are inefficient for agricultural products because of temperature gradients inside the storage rooms. Temperature gradients are developed mainly by improper airflow pattern inside the storage room, which is a main cause of the spoilage of the agricultural products. There proper airflow pattern is essential to minimize these temperature gradients and the spoilage. The performance and characteristics of a cold storage room were determined as a function of airflow pattern and temperature distribution in forced circulation cold storage room. A commercial CFD(computational fluid dynamics) code was used to simulate 3-D airflow in the cold storage room. Solving the flow equations for the storage room, a standard k-$\varepsilon$ turbulent model was implemented to calculate steady state turbulent velocity distribution. The CFD prediction results were compared with temperature measurements inside the cold storage room. In case of pallet storage, Temperature gradients inside pallet storage was reduced because the contact area of cold air expanded through an alley of airflow in storage. But is case of bulk storage, the last temperature of storage considerably rose more than the initial temperature of storage. The reason was that bulk storage didn't include any alley of airflow in storage.

• Journal of Biosystems Engineering
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• 제25권2호
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• pp.107-114
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• 2000

Low temperature storage method is to increase the value of agricultural products by reducing quality loss and regulate consignment time by controlling respiration rates of agricultural products. Respiration rate of agricultural products depends on several factors such as temperature, moisture, gas composition and a microbe inside the storage room. Temperature is the most important factor among these, which affects respiration rate and causes low or high temperature damage. Fuzzy logic was used to control the temperature of a storage room ,which uses information of uncertain facts and mathematical model for room temperature control . Room temperature was controlled better by using fuzzy logic control method rather than on-off control method. Refrigerant flow rates and temperature deviations were measured for on-off system using TEV(temperature expansion valve) and for fuzzy system using EEV(Electrical Expansion Valve) . Temperature of the Storage room was lowered faster by using fuzzy system than on -off system. Temperature deviation was -0.6~+0.9$^{\circ}C$ for on-off system and $\pm$0.2$^{\circ}C$ for fuzzy system developed. Temperature deviation and variation of temperature deviation were used as inout parameters for fuzzy system. The most suitable input and output value were found by experiment. Cooling rate of the storage room decreased while temperature deviation increased for the sampling time of 20 sec.

• 한국동물위생학회지
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• 제28권3호
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• pp.225-234
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• 2005

Egg has been considered as one of the most important food sources in both nutritionally and economically. However, because the hazards of egg flow chains' complexity from producers to consumers and the insufficiency of cold chain systems in Korea are still remained, preventive measures for egg safety should be established. This experiment was carried out to investigate the changes of egg qualify during storage in order to find out the proper storage condition and eggshell treatment. Eggs were stored at cold condition $(5^{\circ}C,\;relative\;humidity;\;RH:\;65\pm3\%)$ and room Condition $(1st: Sep\; 6\~Nov\; 15,\;2001,\; 10\~30^{\circ}C,\;RH\;41\~86\%,\;2nd;\; Dec\;13,\;2001\~Feb\;21,\;2002,\;4\~23^{\circ}C,\;RH\;36\~89\%)$ after eggshell treatment (unwashed, washed and coated egg) during'10 weeks and examined weight loss and interior quality periodically. Weight loss was in decreasing order room washed > room unwashed > cold washed > cold unwashed > room coated > cold coated egg. And, Haugh unit was decreasing order room washed > room unwashed > room coated > cold washed > cold unwashed > cold coated egg. Our findings show that both coated eggs and refrigeration reduces the rate of decline in Haugh units and egg weight. And, washed eggs had lower average Haugh units and a higher weight loss than any of the eggshell treatment in both storage conditions. Conclusively, for washing eggshell, 150 ppm of sodium hypochlorite, regular exchange and temperature control of water should be consistent and also eggs should be dried immediately after washing. Also, national guidelines for temperature and moisture of storage places, transportation and expiration data should be established to keep quality and weight loss of eggs. Storage temperature that is a critical factor in the quality and safety of eggs should be kept under 12'c and labelling of expiration date should be obligatory.

• Agricultural and Biosystems Engineering
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• 제3권2호
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• pp.65-72
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• 2002

Temperature is the most influential environment parameter which affects the quality change of agricultural products in cold storage. Therefore, it is essential to keep the uniform temperature distribution in the storage room. This study was performed to analyze the air movement and temperature distribution in the forced recirculating cold storage facility and to simulate optimum storage method of green groceries using 3-D CFD(three dimensional computational fluid dynamics) computer simulation which applied the standard $textsc{k}$-$\varepsilon$ turbulence model and FVM(finite volume method). The simulation was validated by the experimental results for onion storage and the simulation model was used to simulate the temperature and velocity distribution in the storage room with reference to the change of storage method such as location of storage, no stores, bulk storage, and pallet storage. In case of no stores, internal airflow was circulated without stagnation and consequently air movement and temperature distribution were uniform. In case of bulk storage, air movement was stagnated so much and temperature distribution of onion was not uniform. Furthermore, the inner temperature of onion roses more than the initial temperature of storage. In case of pallet storage, air movement and temperature distribution of onion were so uniform that the danger of quality change was decreased.

• 한국식품저장유통학회지
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• 제31권1호
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• pp.33-45
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• 2024

Three spring potato varieties (Atlantic, Chubaek, and Superior) were cultivated for 80, 90, and 100 days and compared in terms of their total and marketable yields and specific gravities. Subsequently, changes in the quality parameters (weight loss, sprouting rate, disease incidence, dry weight, and specific gravity) of potatoes cultivated for 100 days were monitored during two-month storage in improved and semi-underground warehouses at 4℃ and room temterature. The productivities of Atlantic, Superior, and Chubaek were maximized at cultivation periods of 100, 100, and >90 days, respectively. In all cases, cold storage resulted in <5.3% weight loss and no marketability loss. However, two-month room temperature storage resulted in pronounced marketability loss due to weight loss (6.2, 7.3% and 10.9% for Atlantic, Superior, and Chubaek, respectively) and sprouting (in ~13%, >75%, and 99% of Atlantic, Superior, and Chubaek tubers, respectively). The marketability of Atlantic, Superior, and Chubaek during cold storage was maintained for >2, ~2, and <2 months, respectively. All varieties were characterized by rapid sprouting, low dry weight and specific gravity, and rapid marketability loss during storage.

• 한국자원식물학회지
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• 제25권5호
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• pp.591-595
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• 2012

온실을 이용한 상온 저장시설의 실용화 가능성을 예측해보고 '창녕대고'와 '터보' 양파의 저장성을 비교해 보고자 3개월간 저온과 상온조건에서 품질변화를 조사하였다. 중량 감소율은 저장기간 동안 지속적으로 증가하였으며 저온저장시 3개월 후 약 2% 정도 감소하였고 상온저장의 경우 약 4% 감소를 나타내었다. 저장 전후의 경도를 비교한 결과 저장 조건 및 품종 간에 따른 유의한 차이는 인정되지 않았으나 수확직후의 경도에 비해 3개월 저장 후 경도가 두 품종 모두 감소하는 경향을 나타내었다. 양파 외피의 착색정도를 나타내는 Hunter a 값은 두 품종 모두 상온저장한 양파가 저온저장 처리에 비해 높은 값을 나타내었으며 이는 상온저장한 양파의 외피가 건조되면서 착색된 것으로 사료된다. Hunter L 값은 저장조건에 관계없이 저장일수에 따라 감소하는 경향을 나타내었다. 부패율은 상온저장시 창녕대고에 비해 터보 품종이 7.8%로 현저히 낮았으며, 저온 저장시 두 품종 모두 2% 미만의 부패율을 나타났다. 따라서 온실을 이용하여 상온저장 할 경우 저장 가능기간으로는 3개월 이내가 적당할 것으로 예측되며 저장성이 강한 품종을 이용할 경우 저장기간을 더 연장할 수 있을 것으로 판단된다.

• 대한약침학회지
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• 제6권2호
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• pp.105-111
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• 2003

Objective : The purpose of this study was to investigate the stability of bee venom according to the keeping method and period. Method : The author observed microbial contamination of bee venom in nutrient agar, broth, YPD agar and YPD media and antibacterial activity for S. aureus, E. coli manufactured 12, 6 and 3 months ago as the two type of room temperature and $4^{\circ}C$ cold storage. Results : 1. 1:3,000 and 1:4,000 diluted bee venom solution did not show microbial contamination both room temperature and cold storage within twelve months. 2. There was antibacterial activity of diluted bee venom for S. aureus in cold storage within twelve months and there was no antibacterial activity of diluted bee venom for S. aureus in twelve months, room temperature storage. 3. We could not observe the zone of inhibition around paper disc of all for E.coli. in 1:3,000, 1:30,000 and 1:3,000,000 diluted bee venom solution, respectively. According to results, we expect that diluted bee venom solution is stable both cold and room temperature storage within twelve months.

• 한국자원식물학회지
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• 제11권2호
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• pp.136-141
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• 1998

To give some information on the harvest and storage of Chinese yam (Dioscorea opposita), the experiment was done to examine the effect of its harvesting date and storage method on tuber weight, tuberrelated characters during the storageor at the end of storage. The yam tubers harvested 4 times at 20 days interval from Oct. 15 were stored with different storage methods(pit, room and cold temperature) and on Mar.15. all the characters were measured. Fresh weight of the tuber harvestedafter Nov. 5 and stored were greater than that done on Oct. 15 while dry tuber weight did not have any difference between the harvesting dates. The fresh weigth done directly from the field on Mar. 15 was higher compared to the other harvesting dates owing to its higher moisture content. The rate of sound tuber stored at room or cold temperature condition was higher than that at the field at which the rate was greater at the harvest after late nov. compared to the earlier harvests. Although the two storages were similar at sound tuber rates and marketable yield, the tuber weight was more reduced when stored at room temperature than when done at cold temperature . Brightness and value 'b' of chromaticaity realted to the tuber coloring and sugar content were higher but moisture content was lowerwhen harvested on Oct. 15 than the other havesting dates. All the characteristics realted to the marketability after storage were nearly same when stored at room and cold temperature. Value 'a' of chromaticity and sugar content were higher when harvest on Mar. 15 than when harvested before Dec. 15 but the 'b' value and mositure content were reverse results.

• 한국초전도ㆍ저온공학회논문지
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• 제22권4호
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• pp.45-50
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• 2020

In this research, the variation of round-trip efficiency in a liquid air energy storage system (LAES) is calculated and an optimal configuration is found. The multiple stages of cold energy storage are simulated with several materials that process latent heat at different temperature ranges. The effectiveness in the charging and discharging processes of LAES is newly defined, and its relationship with the round-trip efficiency is examined. According to defined correlation, the effectiveness of the discharging process significantly affects the overall system performance. The round-trip efficiency is calculated for the combined cold energy storage materials of aqueous dimethyl sulfoxide (DMSO) solution, ethanol, and pentane theoretically. The performance of LAES varies depending on the freezing point of the cold storage materials. In particular, when the LAES uses several cold storage materials, those materials whose freezing points are close to room temperature and liquid air temperature should be included in the cold storage materials. In this paper, it is assumed that only latent heat is used for cold energy storage, but for more realistic analyzes, the additional consideration of the transient thermal situation to utilize sensible heat is required. In the case of such a dynamic system, since there is certainly more increased heat capacity of the entire storage system, the volume of the cold energy storage system will be greatly reduced.

• 한국균학회지
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• 제19권4호
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• pp.292-298
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• 1991

Simultaneous distillation-extration method에 의해 국내에서 인공재배되고 있는 여름 느타리 버섯(Pleurotus sajor-caju)을 실온과 냉장하에서 저장하면서 휘발성 향기성분을 분리한 다음 GC-MS 및 GC에 의한 표준품과의 머무름시간 비교에 의해 향기성분의 변화를 검토하여 보았다. 총 aroma contentrates의 함량은 냉장 저장시는 큰차이를 보이지 않았으나 실온 저장시는 큰 감소의 경향을 보였다. 확인된 38종의 휘발성 화합물중 실온 저장시 ${\delta}-decalactone$만 약간증가하였으나 기타의 성분들은 현저히 감소한 반면 냉장 저장시는 2-methyl butanal, 1-octen-3-ol, cis,cis-1,5-octadien-3-ol, pentadecanoic acid등은 감소추세를 보였지만 3-octanone, 1-octen-3-one, 3-octanol, 5-undecanol등은 오히려 증가되는 경향을 보였다. 또한 중량 감소와 관능적 특성은 실온 저장시 냉장 저장보다 심한 변화를 보였다.