• Title/Summary/Keyword: 저온조건

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Low Temperature Inducible Acid Tolerance Response in virulent Salmonella enterica serovar Typhimurium (병원성 Salmonella enterica serovar Typhimurium의 저온 유도성 산 내성 반응)

  • Song, Sang-Sun;Lee, Sun;Lee, Mi-Kyoung;Lim, Sung-Young;Cho, Min-Ho;Park, Young-Keun;Park, Kyeong-Ryang;Lee, In-Soo
    • Korean Journal of Microbiology
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    • v.37 no.3
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    • pp.228-233
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    • 2001
  • The acid tolerance response (ATR) of log-phase Salmouella enterica seroyar Typhimurium is induced by acid adaptation below pH4.5 and will protect cells against more severe acid. Two distinctive ATR systems in thisorganism are a log-phase and stationary-phase ATR in which acid adaptations trigger the synthesis of acid shockproteins (ASPs). We found that log-phase ATR system was strongly affected by environmental factor, low tem-perature, $25^{\circ}C$. Exposure to low temperature and mild acid has been shown to increase acid survival dra-matically, and this survival rate was showed higher than $37^{\circ}C$. Especially unadapted cells at $25^{\circ}C$ presented tenthousand folds survival increasing when compared with cells at $37^{\circ}C$. The degree of acid tolerance of rpoSwhich is blown to be required for acid tolerance more increase than $37^{\circ}C$. Even though AIR pattern of rpoSbetween unadapted and adapted was showed similar at pH 3.1, rpoS-dependent ATR system also has beendetected in low temperature because rpoSAp prevents sustained acid survival at $25^{\circ}C$. Therefore the resultssuggest low temperature ATR system requires rpoS-dependent and -independent both. To investigate the basisfor low temperature related ATR system, gene that was participated for low temperature acid tolerance (lat) wasscreened in virulent S. enterica serovar Typhimurium UKl Using the technique of P22- MudJ (Km, lacZ)-directed lacZ operon fusion, LF452 latA‥‥MudJ was isolated. The latA‥‥MudJ of S. enterica Typhimurium pre-vented low temperature acid tolerance response. Therefore latA is considered one of the important genes for acidadaptation.

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Performance Comparison of Fin-Tube Type Evaporator using R134a and R1234yf under the Frost Condition (착상조건에서 R134a와 R1234yf를 적용한 핀-관 형태의 증발기 성능 비교)

  • Shin, Yunchan;Kim, Jinhyun;Cho, Honghuyn
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.9
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    • pp.5795-5801
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    • 2015
  • The low temperature distribution of the refrigerated and frozen food has been increased gradually. Refrigeration industry is using R134a refrigerant, which GWP is 1300. R1234yf is an alternative refrigerant of R134a because GWP of R1234yf refrigerant is just 4. Evaporator used in refrigeration truck refrigeration system is operated on low temperature condition. Accordingly, evaporator is formed frost and the formation of frost is rapidly decreased performance of evaporator. In this study, the performance of evaporator using R134a and R1234yf refrigerant was analyzed with operating conditions under frost condition. As a result, the performance of R134a evaporator according to air inlet temperature, relative humidity and evaporating temperature was more sensitive than R1234yf evaporator. Besides, the frost growth of R134a evaporator is steeper than that of R1234yf one.

Effect of Packaging and Loading Conditions on the Quality of Late Autumn Chinese Cabbage during Cold Storage (포장 및 적입 방법이 늦가을배추의 저온저장 중 품질에 미치는 영향)

  • 김병삼;남궁배;김민정
    • Food Science and Preservation
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    • v.8 no.1
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    • pp.23-29
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    • 2001
  • To extend the freshness of late autumn Chinese cabbage, the packaging and loading effects on the quality were investigated during cold storage. Judging from overall quality during storage period, late autumn Chinese cabbage could be stored by 3 months at 0$\^{C}$ cold storage. However, late autumn Chinese cabbage was not acceptable for long-term storage because of its marketability and the storage cost. Among 3 packaging methods(PP-net, carton and plastic container) for stored Chinese cabbage, plastic container and carton were more effective than PP-net packaging for the freshness prolongation. Gas composition in the plastic bags during storage was not significantly different among packaging conditions and O$_2$ and CO$_2$ concentrations were 13∼18% and 0.75∼7.48%, respectively, MAP with plastic film was effective for the quality retention because of low oxygen composition and high humidity condition in the bags.

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Experimental Study on Cooling Performance of Multi-Heat Pump by Indoor-Unit Combination (실내기 조합에 따른 3실형 열펌프의 냉방성능 실험연구)

  • Kwon, Young-Chul;Chun, Chong-Keun;Park, Youn-Chang;Ko, Kok-Won;Seo, Dong-Nam
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.6
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    • pp.1487-1493
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    • 2008
  • In order to investigate the cooling capacity of multi-heat pump applying an inverter compressor, the experiment on the cooling performance characteristics of heat pump with 3 indoor units was performed under the cooling standard and cooling low-temperature conditions. The system data were measured by the psychrometric calorimeter. The operation characteristics and the behavior of the cooling cycle of the heat pump with 3 indoor units were understood from the cooling capacity, COP, and P-h diagram by indoor-unit combination. The operating load and performance of the multi-heat pump depends on the indoor-unit combination. The cooling capacity and COP of the low temperature condition were larger than those of the standard one. Also the cycle was analyzed by using P-h diagram.

Effect of Filled Hole on Strength Behavior of CFRP Composites at Cold Temperature Dry and Elevated Temperature Wet (저온건조($-55^{\circ}C$) 및 고온다습 조건($108.3^{\circ}C$)의 기계적 체결 홀이 탄소섬유강화 복합재의 강도 특성에 미치는 영향 연구)

  • Kim, Hyo-Jin
    • Composites Research
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    • v.22 no.3
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    • pp.82-88
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    • 2009
  • The effect of open and filled holes on the strength behavior of carbon fiber reinforced polymeric (CFRP) composites was investigated. The strength was measured at room temperature dry, cold temperature dry, $-55^{\circ}C$, and elevated temperature wet, $108.3^{\circ}C$ on several different laminate configurations. Based on the experimental data presented, it is shown that the filled hole tensile strength is larger than that of open hole by reducing damage around the hole due to the constraint imposed by the fastener. The tensile strength at cold temperature dry, $-55^{\circ}C$ is increased with the brittleness by the thermal expansion coefficient of fiber and matrix. The compressive strength at elevated temperature wet, $108.3^{\circ}C$ is decreased by the cause of interfacial deterioration between fiber and matrix with moisture absorption.

Effects of Soil Moisture and Chemical Application on Low Temperature Stress of Cucumber (Cucumis sativus L.) Seedling (토양수분조건 및 화학물질처리가 오이묘의 저온장해에 미치는 영향)

  • Nam, Yooun-Il;Woo, Young-Hoe;Lee, Kwan-Ho
    • Journal of Bio-Environment Control
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    • v.15 no.4
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    • pp.377-384
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    • 2006
  • This study was conducted to investigate the effects of chemical application and amout of soil moisture on low temperature stress of cucumber seedling under the greenhouse conditions. When chilling treatments ($2^{\circ}C$) were begun at 07:00AM, survival rates of seedlings of two conditions; -0.3 bar and -5.5 bar were 28.3% and 83.3% respectively. But when chilling treatments were begun at 6:00PM - even the soil moisture condition was -0.3 bar - the survival rate was above the 87%. When reducing the soil moisture from -0.3 bar to -9.0 bar, ABA content in leaf was inc.eased by 6.5fo1d. Spraying of abscisc acid (ABA) before or after the chilling significantly increased the survival rates of seedlings, decreased the amounts of leaking electrolytes and prevented the yield reductions. ABA application on the soil before the chilling appeared to be more effective than the application after the chilling with foliar spray. Spraying of ABA ($10^{-5}M$), urea (0.2%) or $KH_2PO_4$ was effective in counteracting the low temperature, which causes growth deterioration and yield reduction in cucumbers.

The Production of Traditional Alcoholic Beverage in Containing Medicinal Herb (한약재를 첨가한 전통주개발에 관한 연구)

  • Kim, Young-Sook;Park, Young-Sook
    • Food Science and Industry
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    • v.40 no.2
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    • pp.83-89
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    • 2007
  • 저온발효와 고온발효에 의하여 만들어진 민속주를 증류하여 알콜돗를 45%로 같이 맞추어 성분함량을 비교하였다. 발효온도에 따른 환원당의 함량을 나타내고 있으며 저온발효 민속주는 15 mg/100 mL, 고온발효 민속주는 5 mg/100 mL로 나타났다. 즉 저온 발효에서 환원당의 양이 많았으며, 그러나 시중에 판매되고 있는 소주보다는 낮은 경향을 보였다. 향기 성분에 생성과정에 영향을 주는 Fusel alcohol을 볼 때 반적으로는 발효액에 아미노산이 없는 것보다는 많을 수록 많은 양의 fusel alcohol을 생성되기는 하지만, fusel alcohol을 생성하기위한 조건은 효모의 종류, 발효조건, 발효온도, 발효액의 조성 등의 복잡한 인자가 관련된다. 본 연구에 제조한 발효주를 소주의 아미노산과 비교할 때 아미노산 함량이 전반적으로 20-100도 낮은 함량치로 나타났다. 한약재 첨가로 인하여 면역증강, 살세포 반응 억제효과, 기능성 전통주로 좋은 발효주로 인정되지만 한약재특유의 강한 향기를 약화시키는 연구가 금후에 보완되어야 한다고 본다. 발효온도에 따른 아미노산의 함량은 저온발효 조미주에서 cysteine, valine, mrthionine, isoleucine, phenylalanine이 많았으며, 고온발효 조미주에서는 serine, glycine, leucine이 많았다. 한 alanine, tyrisine, lysine은 고온발효주에는 있으나, 저온발효주에서는 나타나지 않았다. 그러나 저온발효주와 고온 발효주 모두 시중에 판매되고 있는 소주보다는 아주 낮은 경향을 보였다. 저온발효와 고온발효에 의하여 만들어진 민속주를 증류하여 알콜 도수를 45%로 같이 맞추어 성분함량을 비교하였다. 발효온도에 따른 환원당의 함량을 나타내고 있으며 저온발효 민속주는 15 mg/100 mL, 고온발효 민속주는 5 mg/100 mL로 나타났다. 즉 저온 발효에서 환원당의 양이 많았으며, 그러나 시중에 판매되고 있는 소주보다는 낮은 경향을 보였다. 아미노산 실험에서는 소주와 45% 고온 발효주를 비교 할 때 serine, glycine, cysteine, methionine, phenylalanine 등은 100배, alanine, valine, isoleucine 80배, ammonia 20배 낮은 수치를 나타냈다. OD 측정의 실험결과 또한 control과 비교시 40% 발효주에서는 10배, 45% 고은 발효주에서는 100배 낮은 측정치가 나타났으므로 한약재의 색소성분을 휘발시키는 기술이 요구된다고 본다. 항균성실험에서 항균성 측정은 06 cm paper disk agar diffusion법을 이용하였으며, 43%의 발효주와, 45% 고온 발효주가 항균력이 가장 강력한 0.95 cm의 영향을 나타냈다. 사용한 사용한 Gram 양성, Gram 음성 균주는 Escherichia coli KCCM 11591를 제외하고는 0.8 - 0.95 cm로 항균력이 강했으며, Gram negitive의 Pseudomonas aeruginosa KCTC 1750 에서는 43% 발효주에는 0.95 cm, 45% 고은 발효주에는 0.95 cm의 항균성을 나타냈으며 관능평가에서도 가장 높게 났다. 관능평가에서는 45% 고온 발효주가 가장 높게 나타났으며, 항산화성 실험에 나타난 저온 45%의 갈색도의 측정과는 항산화성에서는 좀 다른 결과를 나타낸다. 그러나 항균성이 가장 높게 나타난 43-45%와 관능평가에서 가장 높게 나타난 45% 고온 발효주를 볼 때 본 연구에서는 고온 발효주 45%가 가장 우수한 전통주로 조사되었다. 발효주를 소주의 아미노산과 비교할 때 아미노산 함량이 전반적으로 100배 정도 낮은 함량치로 나타났으므로, 한약재 첨가로 인하여 면역증강, 살세포반응 억제효과, 기능성전통주로 좋은 발효주로 인정되지만 한약재특유의 강한 향기를 약화시켜서 부드럽고 은은한 전통발효주의 연구가 금후에 보완되어야 한다고 본다.

A Study on the Establishment of Environmental Test Procedures for the UAV (무인항공기 운용 환경조건 시험절차 수립)

  • Yun, Sanguk
    • Journal of Aerospace System Engineering
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    • v.13 no.3
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    • pp.87-94
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    • 2019
  • In this paper, we test procedures to demonstrate operating environmental conditions that can be exposed to UAV during its life-cycle are proposed. They are set up to be used in a large-sized climate chamber, one of the facilities of the Agency for Defense Development corresponding with the system requirements. The test steps and profile details were more specifically suggested for rainfall, humidity, and temperature (low-temperature storage and operation, high-temperature operation and solar radiation), and MIL-STD-810G w/Change-1-based.

Analysis of the Change of Polyamine during the Cold Treatment in Spring Radish Young Cotyledons and Hypocotyls (봄무우 유식물의 자엽과 하배축에서 저온처리동안 Polyamine 농도 변화의 분석)

  • Lee, Sung Chang;Park, Jae Won;Cho, Bong-Heuy
    • Analytical Science and Technology
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    • v.12 no.1
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    • pp.75-79
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    • 1999
  • The concentration of polyamine and the relationship between the concentration of PA and cold resistance were analysed during the cold stress in the cotyledons and hypocotyls of young spring radishes. The concentration of PUT was increased during the cold stress in the cotyledons and the concentration of PUT and SPD was changed significantly all the stress time. From the results, we suggested that PUT and SPD were synthesized against cold stress or separated from the bound PA during the cold stress. But, the concentration of SPM was not significantly changed during the cold stress. Only SPD existed in the control hypocotyls. The concentration of SPD was increased during the cold stress, but was decreased dramatically during continusly cold stress. The reactivity against stress of hypocotyls was generally more sensitive during the cold treatment than that of the cotyledons because of the lower concentration of PA in the hypocotyls. PUT and SPD were responsible for the resistance of cold stress in the cotyledons and PA did not play an important role on the resistance of cold stress in the hypocotyls. In this study we suggest that PUT and SPD were responsible for the increase of the resistance against the cold stress.

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A study on the emission characteristics of greenhouse gases according to the vehicle technology, fuel oil type and test mode (차량기술, 연료 유종 및 시험모드 특성에 따른 온실가스의 배출특성 연구)

  • Lee, Jung-Cheon;Lee, Min-Ho;Kim, Ki-Ho;Park, An-Young
    • Journal of the Korean Applied Science and Technology
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    • v.34 no.4
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    • pp.962-973
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    • 2017
  • Concerns about an air pollution are gradually increasing at home and abroad. The automotive and fuel researchers are trying to reduce emissions and greenhouse gases of vehicles through a research on new engine designs and innovative after-treatment systems using clean fuels (eco-alternative fuel) and fuel quality improvements. In this paper, we stduy the emission characteristics of greenhouse gases on seven vehicles using gasoline, diesel, and LPG by legal test mode in domestic and abroad.(Urban mode, Highway mode, rapidly acceleration and deceleration, using air conditioner, low temperature condition) Regardless of fuels, most of the greenhouse gases tend to show the worst results in cold FTP-75 mode. In the case of A vehicles (2.0 MPI) and B vehicles (2.4 GDI) using a gasoline fuel, the factors that increase greenhouse gases are in order of a rapidly acceleration and deceleration, using air conditioner, low temperature condition. But G vehicles(LPLi) have different emission characteristics from another vehicles. In the case of A vehicles (2.0 w/o DPF) and B vehicles (2.2 with DPF) using a diesel fuel, the factors that increase greenhouse gases are in order of a rapidly acceleration and deceleration, using air conditioner, low temperature condition. However, the factor of F vehicles are in order of low temperature condition, using air conditioner, rapidly acceleration and deceleration. In conclusion, it will be an effective method to apply different technologies of emission reduction for each fuel.