• 제목/요약/키워드: High humidity

검색결과 1,706건 처리시간 0.031초

서울의 기상 조건에 따른 미세먼지와 시정의 상관성 (The Relationship of Particulate Matter and Visibility Under Different Meteorological Conditions in Seoul, South Korea)

  • 김민석;이서영;조예슬;구자호;염성수;김준
    • 대기
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    • 제30권4호
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    • pp.391-404
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    • 2020
  • To understand the characteristics of the relationship between visibility and particulate matter (PM) in different meteorological conditions, we investigated the contributions of PM and relative humidity (RH) to visibility in Seoul, South Korea. For the period from 2001 to 2018, both PM and RH show descending trends, resulting in a visibility increase. PM has little impact on the hourly variation of visibility, which could be explained more by the RH variability. Meanwhile, the daily change of PM accounts for daily visibility variation. For the monthly variation of visibility, both PM and RH showed similar influence. The correlation coefficients of PM10, PM2.5, and RH with visibility was -0.486, -0.644, and -0.556, respectively, which became higher during the high PM seasons of spring and winter. The correlation coefficient between PM2.5 and visibility was -0.454 for RH higher than 80%, and -0.780 for RH between 40% and 60%. From 2017 to 2018, there were 10 cases of extreme visibility impairment, among which five cases were incurred by high PM pollution, and two cases were by high humidity. Further analysis with PM chemical composition measurements is required to better understand the characteristics of visibility in Seoul.

국내에서 분리한 Cronobacter spp.(Enterobacter sakazakii)의 건조내성 특성 (Tolerance of Korean Cronobacter spp. (Enterobacter sakazakii) Isolates to Dessication)

  • 이은진;류태화;박종현
    • 한국식품과학회지
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    • 제41권6호
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    • pp.681-686
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    • 2009
  • Cronobacter spp.(Enterbacter sakazakii)의 건조저항성은 다른 장내 세균들보다 강한 특성을 가지고 있는 것으로 알려져 있다. 본 연구는 국내 식품으로부터 분리한 110개의 Cronobacter균주로부터 건조내성 특성을 분석하고 여러 상대습도에서의 생존특성을 연구하고자 하였다. 국내 식품에서 분리한 Cronobacter 110균주중 8시간 금속표면 건조노출에 대하여 초기균수의 약 절반정도 생존하는 고내성그룹이 30%, 대부분이 사멸하는 저내성그룹이 약 10%를 차지하여 전체 균주 중 중간정도 이상의 내성을 가지는 균주가 90% 이상을 차지하고 있었다. 15일간 장기 건조노출에 경우도 비슷한 경향을 보여 주었다. 조제분유에서 Cronobacter 건조 노출의 경우 고내성그룹과 중간내성그룹은 30일 이후에도 5 log CFU/mL에서 3 log CFU/mL 이상의 생균수를 나타내었다. 오히려 금속 표면건조 때보다 더 생존율이 높아 조제분유에서는 더 내성이 증가함을 할 수가 있었다. 따라서 국내 식품에서 분리한 대부분의 Cronobacter도 건조에 강한 내성을 가지고 있는 것으로 보인다. 건조환경에서의 biofilm 형성능력은 고내성과 중간 내성그룹 균주는 노출초기에서부터 biofilm 생성이 이루어졌다. 그러나 저내성그룹 균주의 경우에는 biofilm의 형성이 증가하지 않다가 7일 후 biofilm 생성이 많아지는 것으로 분석되었다. 따라서 Cronobacter의 biofilm 형성능은 각 그룹간 biofilm 생성의 시간적인 차이만 존재하고 대부분의 Cronobacter는 건조스트레스에서 biofilm 형성능이 비슷한 것으로 보인다. Cronobacter는 건조금속표면의 75%의 상대습도에서 24-48시간 내에 모두 사멸하는 것으로 나타났으나 40% 상대습도에서는 초기균수의 60% 생균수를 유지하여 낮은 상대습도에 강한 저항특성을 보여주었다. 대부분의 Cronobacter는 건조에 강한 내성을 가지고 있어 조제분유등의 건조식품에서 오랫동안 살아 있을 수 있으나 습도가 높은 환경에서는 사멸이 많이 일어나는 것으로 사료된다. 그러므로 식품생산현장에서 습도를 조절하여 Cronobacter를 제어할 수 있을 것으로 보인다.

상품성 제고를 위한 고구마 수확 후 관리 및 출하기술 (Postharvest Handling and Marketing Management for Making High Salability of Sweetpotatoes)

  • Jeong, Byeong-Choon
    • 한국식품저장유통학회:학술대회논문집
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    • 한국식품저장유통학회 2001년도 임시총회 및 제18차 학술발표회 발표논문초록집
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    • pp.51-64
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    • 2001
  • The qualities including taste of sweetpotato stored during the winter which can display in the spring market in Korea are affected by availability of storage for the roots. In order to make high storage availability of sweetpotato, the postharvest handlings should be done thoroughly from the moment of harvest until shipping them to the market. A lot of procedures that must be handled carefully for improving postharvest management are as follows; digging, trimming, gathering, putting in storage containers, carrying them from field to house, curing, storing, washing, drying, selecting marketable roots, packing and shipping to the market, etc.. Sweetpotatoes have a high moisture content, and a relatively thin and delicate skin, and are sensitive to chilling, so careless postharvest handling can lead to both quantitative and qualitative losses which may be extremely high in some circumstances. From now on research has concentrated on the improvement of postharvest conditions to increase yield and lower disease rates. Storage, which makes sweetpotatoes available through out the year, benefits both the producer and the consumer. Seven very important points must be needed in order to get the best quality marketable roots in the storing of sweetpotatos : $\circled1$The storage house must be clean and sanitary, $\circled2$The crop must be harvested before the first frost to avoid low-temperature injury, $\circled3$Particular care must be taken to avoid cutting, bruising, or other injuries of the sweetpotatoes during digging, picking up, grading, placing in containers, and moving to the storage house, $\circled4$Select sound, disease-free roots for storage $\circled5$Sweetpotatoes should be stored in properly stacked containers $\circled6$Cure immediately after harvest, preferably at 32∼33$^{\circ}C$ and 90 to 95 percent relative humidity for 4 to 7 days, After curing the temperature should be reduced to 13$^{\circ}C$ to 16$^{\circ}C$ by ventilating the storage with outside air. $\circled7$Store at 12$^{\circ}C$ to 14$^{\circ}C$ and a relative humidity of 80 to 85 percent. Storage houses should be located on suitable sites and should be tightly constructed and insulated so that temperature and humidity will be uniform. Sweetpotatoes are usually not washed and graded, and lately sometimes washed, graded, waxed, before being shipped to market. Consumer packaging of sweetpotatoes in paper boxes(10-15kg) or film bags is done mainly to aid marketing. The shelf life of washed roots in consumer packs in only 1 to 2 weeks. Weight loss of roots during marketing is much less in perforated film bags than in mesh and paper bags. Perforation of 0.8 to 1kg polyethylene bags with about six 6mm holes is essential ; to lower the internal relative humidity and avoid excessive sprouting, rooting, and dampness. Development and use of better postharvest handling with good storage facilities or marketing methods can minimize sweetpotate losses and has an effect of indirectly increasing productivity and farmer’s income.

물-시멘트비에 따른 경량콘크리트 및 일반콘크리트의 수축과 습도와의 관계 (Relation Between Shrinkage and Humidity on Lightweight Concrete and Normal Concrete by Water-Cement Ratio)

  • 이창수;박종혁;정봉조;최영준
    • 대한토목학회논문집
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    • 제29권4A호
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    • pp.385-393
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    • 2009
  • 콘크리트 수축과 습도를 측정하고 기존 연구 결과와의 비교를 통해 다공성 경량골재의 사전흡수수에 따른 콘크리트의 수축과 콘크리트 내 상대습도와의 관계를 파악하였다. 물-결합재비 0.3에서 경량 콘크리트의 수축 저감효과는 7일 초기재령에서 36%, 6개월 장기재령에서 25%를 나타내었으며, 물-결합재비 0.4는 7일 초기재령에서 19%, 6개월 장기재령에서 16%의 수축 저감률을 그리고 물-결합재비 0.5에서는 각각 37%, 32%를 나타내었다. 물-결합재비에 관계없이 경량골재 사전흡수수의 습도 공급 효과는 7~10일 이내의 초기 재령에서 두드러지게 나타났다. 콘크리트 내 습도와 수축과의 관계는 물-결합재비 0.3의 경우 기존 모델식 적용 종류에 상관없이 습도 변화 전체 구간에 대하여 수축이 과소평가되었으며, 물-결합재비 0.4, 0.5의 경우 비교적 기존 모델식과 측정값이 유사한 경향을 나타내었다. 습도감소와 수축 변형률간의 관계를 고차 다항식으로 회귀분석할 수 있었으며, 콘크리트의 수분이동 해석을 통해 시간에 따른 상대습도를 고려할 경우 수분이동 해석과 부등수축 해석을 연관할 수 있는 매개변수로 적용할 수 있는 결과를 도출하였다.

시설 내 상대습도 및 온도 조건에 따른 국화 '백마'의 생육과 흰녹병 발생 (Occurrence of White Rust and Growth of Chrysanthemum 'Baekma' under Various Relative Humidity and Temperature Conditions in the Greenhouse)

  • 유용권;노용승
    • 원예과학기술지
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    • 제32권6호
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    • pp.803-811
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    • 2014
  • 본 연구는 스탠다드 국화 '백마'의 흰녹병 발생과 생육에 미치는 시설 내의 상대습도(70, 80, 90, 95%)의 영향을 조사한 후, 온도(15, 20, $25^{\circ}C$)와 상대습도(60, 70, 80, 90%)의 상호관계를 알아보고자 실시되었다. 또한 흰녹병의 발생 초기부터 동포자퇴에서 소생자가 형성될 때까지 병 발생 단계를 관찰하였다. 국화 '백마'를 시설 재배 시 상대습도를 90% 이상 조건에서 40일간 처리되었을 때, 흰녹병 발생률이 97%, 주당 발병엽수가 10개, 발병엽당 병징수가 55개 이상으로 나타났다. 그러나, 상대습도를 70% 이하로 유지하면 흰녹병 발생률을 30% 낮출 수 있고, 한 주당 1-2개의 감염된 잎에 2개의 병징만 나타나 병해를 크게 줄일 수 있었다. 생체중과 엽수와 같은 절화의 품질은 다른 처리보다 상대습도 70% 처리에서 가장 우수하였다. 상대습도 90% 처리구에서 흰녹병에 감염된 국화를 정식한 후 6일 후에 첫 병징인 흰색 반점이 나타났고 (1단계), 1일 경과 후에 동포자가 잎의 표피 조직을 뚫고 나왔으며(2단계), 1-2일 후에 동포자의 수가 증가하면서 동포자퇴가 크게 형성되었다(3단계). 동포자에서 1-2일 후에 전균사체가 발달하였고(4단계), 4-5일 경과된 후 전균사체에서 소생자가 형성되었다(5단계). 시설 내 온도를 $25^{\circ}C$로 처리했을 때, 상대습도에 관계없이 흰녹병이 전혀 발생하지 않았다. 시설 내 온도가 $20^{\circ}C$에서는 상대습도에 관계없이 소생자수가 많았으나, 60%와 70%에서는 흰녹병이 발생하지 않았다. 시설 내 온도가 $15^{\circ}C$에서는 상대습도가 높을수록 소생자수가 많았고, 흰녹병 발생률도 높아졌으나, 상대습도가 낮은 60-70% 처리에서는 흰녹병 발생률이 14% 이하로 낮았다.

에어로빅복의 소재 차이에 따른 착용감에 관한 연구 (A Study on Wearing Sensation in Accordance with difference in Materials of Aerobic Wear)

  • 이미경;류숙희
    • 한국의류학회지
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    • 제22권1호
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    • pp.116-126
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    • 1998
  • This study was conducted to examine the effect of difference in materials of aerobic wear on both human body's physiological reactions and subjective wearing sensation by comparing and analysing not only cotton sparidex A, B and C but nylon spandex D, E and F used as actually wearing materials. The rectal temperature of type A and I remained at high degree, the type C was higher from after high-speed running but dropped sharply when taking a break finally. Both skin temperature and mean skin temperature dropped sharply due to sweat occurred during physical exercise, and then rose slowly when taking a break. Type A -D and B-I showed that the mean skin temperature remained at high degree when wearing a cotton spandex. Type C's temperature within its aerobic wear was lower than type F while its relative humidity was higher than type F. Wearing sensation showed a change similar to wearing, particularly, which was remarkable in type B-E. Also, it was shown that humidity sensation, tactile sensation and comfort sensation were good when wearing the cotton spandex.

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Effects of Key Operating Parameters on the Efficiency of Two Types of PEM Fuel Cell Systems (High-Pressure and Low-Pressure Operating) for Automotive Applications

  • Kim Han-Sang;Lee Dong-Hun;Min Kyoungdoug;Kim Minsoo
    • Journal of Mechanical Science and Technology
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    • 제19권4호
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    • pp.1018-1026
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    • 2005
  • The proton exchange membrane (PEM) fuel cell system consisting of stack and balance of plant (BOP) was modeled in a MATLAB/Simulink environment. High-pressure operating (compressor type) and low-pressure operating (air blower type) fuel cell systems were con­sidered. The effects of two main operating parameters (humidity and the pressure of the supplied gas) on the power distribution characteristics of BOP and the net system efficiency of the two systems mentioned above were compared and discussed. The simulation determines an optimum condition regarding parameters such as the cathode air pressure and the relative humidity for maximum net system efficiency for the operating fuel cell systems. This study contributes to get a basic insight into the fuel cell stack and BOP component sizing. Further research using muli­object variable optimization packages and the approach developed by this study can effectively contribute to an operating strategy for the practical use of fuel cell systems for vehicles.

납축전지의 심방전용 극판에 관한 연구 (A Study on the Plate for Deep Discharge in Lead Acid Battery)

  • 정순욱;구본근
    • 한국응용과학기술학회지
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    • 제31권2호
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    • pp.197-202
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    • 2014
  • Positive plate was composed of lead hydroxide via reaction between lead oxide and $H_2O$ and lead sulfate was formed of the reaction of lead hydroxide with sulfuric acid. And its density is $3.8g/cm^3$, $4.0g/cm^3$, $4.2g/cm^3$ and $4.4g/cm^3$ by controlling volume of refined water. Curing of positive plate is done for low ($45^{\circ}C$, 40hr, over 95% of relative humidity) & high ($80^{\circ}C$, 40hr, over 95% of relative humidity) temperature, which created 3BS & 4BS active materials. Experimental result of DOD with 100% life cycle test shows that it was not related to the density of active materials but to the low & high temperature aging of active materials. The test makes us to understand that the crystallization which is made by curing of active materials is a more of a main factor than density of active materials under the deep cycle using circumstances. The active materials which were from the high temperature curing are better for deep cycle performance.

온·습도 조건이 전자 복사용지의 물리적 특성에 미치는 영향 (Effects of Temperature and Relative Humidity on the Physical Properties of Electronic Copying Paper)

  • 강광호;김형진
    • 펄프종이기술
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    • 제44권3호
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    • pp.70-78
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    • 2012
  • For evaluating the printing suitability of electronic copying papers in the aspect of climate conditions, 12 samples of copying papers being generally used in Korea and worldwide were collected. The copying papers were controlled by various temperature and humidity options in conditioning equipment in order to simulate the specific circumstances of dry, temperate or tropical climate, and the pre-heating system of photocopying machines during printing. As results, some copying papers showed several physical problems, especially in recycled copying papers and a normal paper with original printing faulty. These problems of copying papers were mostly resulted in extremely high moisture circumstance, and in lower levels of tensile strength and tensile stiffness. The moisture contents of copying papers during passing through the pre-heater system of photocopying machine could be rapidly decreased because paper is exposed to high temperature around the pre-heating zone. The copying paper, for example of XR3 sample, containing low moisture contents below 2% had high exfoliating possibility of toner transfer from copying paper.

고온형 고분자 전해질막 연료전지(HT-PEMFC) 구동환경에 따른 탄소 담지체 부식 평가 (Effect of operating conditions on carbon corrosion in High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs))

  • 이진희;김한성
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2011년도 추계학술대회 초록집
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    • pp.89.1-89.1
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    • 2011
  • The influence of potential and humidity on the electrochemical carbon corrosion in high temperature polymer electrolyte membrane fuel cells(HT-PEMFCs) is investigated by measuring $CO_2$ emission at different potentials for 30 min using on-line mass spectrometry. These results are compared with low tempterature polymer electrolyte membrane fuel cells(LT-PEMFCs) operated at lower temperature and higher humidity condition. Although the HT-PEMFC is operated at non humidified condition, the emitted $CO_2$ in the condition of HT-PEMFC is more than LT-PEMFC at the same potential in carbon corrosion test. Thus, carbon corrosion shows a stronger positive correlation with the cell temperature. In addition, the presence of a little amount of water activate electrochemical carbon corrosion considerably in HT-PEMFC. With increased carbon corrosion, changes in fuel cell electrochemical characteristics become more noticeable and thereby indicate that such corrosion considerably affects fuel cell durability.

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