• Title/Summary/Keyword: y+ 값

Search Result 43,635, Processing Time 0.074 seconds

Validation of Load Calculation Method for Greenhouse Heating Design and Analysis of the Influence of Infiltration Loss and Ground Heat Exchange (온실 난방부하 산정방법의 검증 및 틈새환기와 지중전열의 영향 분석)

  • Shin, Hyun-Ho;Nam, Sang-Woon
    • Horticultural Science & Technology
    • /
    • v.33 no.5
    • /
    • pp.647-657
    • /
    • 2015
  • To investigate a method for calculation of the heating load for environmental designs of horticultural facilities, measurements of total heating load, infiltration rate, and floor heat flux in a large-scale plastic greenhouse were analyzed comparatively with the calculation results. Effects of ground heat exchange and infiltration loss on the greenhouse heating load were examined. The ranges of the indoor and outdoor temperatures were $13.3{\pm}1.2^{\circ}C$ and $-9.4{\sim}+7.2^{\circ}C$ respectively during the experimental period. It was confirmed that the outdoor temperatures were valid in the range of the design temperatures for the greenhouse heating design in Korea. Average infiltration rate of the experimental greenhouse measured by a gas tracer method was $0.245h^{-1}$. Applying a constant ventilation heat transfer coefficient to the covering area of the greenhouse was found to have a methodological problem in the case of various sizes of greenhouses. Thus, it was considered that the method of using the volume and the infiltration rate of greenhouses was reasonable for the infiltration loss. Floor heat flux measured in the center of the greenhouse tended to increase toward negative slightly according to the differences between indoor and outdoor temperature. By contrast, floor heat flux measured at the side of the greenhouse tended to increase greatly into plus according to the temperature differences. Based on the measured results, a new calculation method for ground heat exchange was developed by adopting the concept of heat loss through the perimeter of greenhouses. The developed method coincided closely with the experimental result. Average transmission heat loss was shown to be directly proportional to the differences between indoor and outdoor temperature, but the average overall heat transfer coefficient tended to decrease. Thus, in calculating the transmission heat loss, the overall heat transfer coefficient must be selected based on design conditions. The overall heat transfer coefficient of the experimental greenhouse averaged $2.73W{\cdot}m^{-2}{\cdot}C^{-1}$, which represents a 60% heat savings rate compared with plastic greenhouses with a single covering. The total heating load included, transmission heat loss of 84.7~95.4%, infiltration loss of 4.4~9.5%, and ground heat exchange of -0.2~+6.3%. The transmission heat loss accounted for larger proportions in groups with low differences between indoor and outdoor temperature, whereas infiltration heat loss played the larger role in groups with high temperature differences. Ground heat exchange could either heighten or lessen the heating load, depending on the difference between indoor and outdoor temperature. Therefore, the selection of a reference temperature difference is important. Since infiltration loss takes on greater importance than ground heat exchange, measures for lessening the infiltration loss are required to conserve energy.

Determination of Shelf-life of Black Mini Tomato Based on Maturity and Storage Temperature (흑색 방울토마토의 숙기 및 저장온도에 따른 상품성 유지기간 구명)

  • Park, Mehea;Seo, Jeongmin;Won, Heeyeon;Seo, Jongbun;Moon, Doogyung;Kim, Wooil;Shim, Sangyoun
    • Horticultural Science & Technology
    • /
    • v.33 no.5
    • /
    • pp.687-696
    • /
    • 2015
  • Black mini tomato 'Hei-G' fruits were harvested at different stages of maturity (immature-mature green and mature-black red) and stored at different temperatures (8, 12, and $20^{\circ}C$) to investigate the quality and lycopene content during storage. Weight loss increased dramatically at higher temperature for both harvesting stages without significant differences. Firmness of immature fruits decreased below the initial level of mature fruit (8.1N) after 5, 8, and 19 days storage, when they were stored at 20, 12, and $8^{\circ}C$, respectively. Soluble solid contents of mature fruit increased at initial storage, and were higher as compared to immature fruits before deterioration at each storage temperature. Decrease in titratable acid of mature fruits depended on storage time and temperature. However, titratable acid of immature fruits showed little change during storage, and so it did not affect flavor. Hunter a value changed greatly in immature fruit stored at high temperature. Unlike ripe tomatoes, there was no significant difference in black tomato Hunter b values of immature and mature fruit at initial and 12 days storage. However, immature fruits stored at $8^{\circ}C$ did not reach full maturity and color development and ripening. High storage temperature increased lycopene production while low storage temperature blocked lycopene development. Shelf life of the immature fruits, which was evaluated by elapsed days to conventional mature stage, was 12 and 15 days when they were stored at 20 and $12^{\circ}C$, respectively. The optimum storage temperature to maintain the quality and lycopene content of mature fruits was $12^{\circ}C$. Moreover, the shelf life of mature fruits stored at $20^{\circ}C$ could reach up to 5 days.

Physicochemical Characteristics of Traditional Fermented Soybean Products Manufactured in Folk Villages of Sunchang Region (순창 고추장민속마을에서 생산한 전통 장류의 이화학적 특성)

  • Kim, Jong-Wook;Kim, Yong-Suk;Jeong, Pyeong-Hwa;Kim, Hyung-Eun;Shin, Dong-Hwa
    • Journal of Food Hygiene and Safety
    • /
    • v.21 no.4
    • /
    • pp.223-230
    • /
    • 2006
  • For standardization of quality of traditional fermented soybean products manufactured in Folk Villages of Sunchang Region, the physicochemical characteristics of 28 Kochujang, 28 Doenjang, and 18 Chunggukjang were compared. Moisture contents of Kochujang, Doenjang, and Chunggukjang were $46.9{\pm}3.6,\;60.6{\pm}1.9,\;and\;57.0{\pm}3.10%$, respectively. On the basis of average moisture contents, crude protein, crude fat, and crude ash contents were calculated to $6.2{\pm}0.7,\;2.0{\pm}0.5,\;and\;8.2{\pm}1.1%$ in Kochujang, $13.2{\pm}1.0,\;7.1{\pm}0.6,\;and\;15.2{\pm}1.5%$ in Doenjang, and $18.9{\pm}1.2,\;6.1{\pm}1.4,\;and\;5.1{\pm}1.7%$ in Chunggukjang, respectively. Reducing sugar, salinity, and water activities in Kochujang were $19.25{\pm}4.1%,\;7.3{\pm}1.1%,\;and\;0.790{\pm}0.003$, in Doenjang were $2.38{\pm}0.89%,\;14.2{\pm}1.4%,\;and\;0.835{\pm}0.020$, and in Chunggukjang were $0.51{\pm}0.24%,\;4.2{\pm}1.6%,\;and\;0.962{\pm}0.028$, respectively. Amino-type nitrogen contents, which affects delicate flavors of fermented soybean products, of Kochujang, Doenjang, and Chunggukjang were $114.03{\pm}19.04,\;734.32{\pm}147.70,\;and\;600{\pm}150mg%$, respectively. Lightness (l), redness (a), and yellowness (b) values in color of Kochujang were $14.49{\pm}1.44,\;15.45{\pm}1.77,\;and\;8.34{\pm}1.02$, respectively, and the redness was lower than that of other ones. Those of Doenjang were $26.69{\pm}4.33,\;7.25{\pm}1.03,\;and\;12.02{\pm}1.82$, respectively, and those of Chunggukjang were $35.62{\pm}2.05,\;6.31{\pm}0.37,\;and\;13.50{\pm}0.78$, respectively. These results indicate that the salt concentration and quality of traditional fermented soybean products manufactured in Folk Villages of Sunchang region must be lowered and standardized, respectively.

The Naturally Occurring Levels of Nitrate and Nitrite in Livestock Products (축산물 중 천연유래 질산염 및 아질산염 함유량 조사)

  • Choi, Jae-Chun;Park, So-Ra;Lim, Ho-Soo;Ko, Kyung-Yuk;Kim, Meehye
    • Journal of Food Hygiene and Safety
    • /
    • v.30 no.3
    • /
    • pp.265-271
    • /
    • 2015
  • This study was done in order to investigate the naturally occurring levels of nitrate and nitrite in livestock products. Total samples of 458 consisting of meats (n = 223), processed meat products (n = 51), raw milks (n = 30), processed milk products (n = 142), eggs (n = 5) and processed egg products (n = 7) were analyzed for contents of nitrate and nitrite by ion chromatography (IC). That methods showed good results in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ), recovery, reproducibility and uncertainty. Nitrate and nitrite were detected in 167 and 40 samples, respectively. The nitrate levels (mg/kg) were not detected (ND)~40.23 for modified milks, ND~37.97 for sauce meats, ND~32.40 for process cheeses, ND~31.50 for processed egg products, ND~27.73 for dry milks, ND~24.76 for sausages, ND~22.45 for bacons, ND~21.55 for natural cheeses, ND~20.82 for hams and fermented milks, ND~13.57 for eggs, ND~12.77 for butters, ND~9.31 for milks and ND~3.88 for meats while the nitrite levels (mg/kg) were ND~17.35 for processed egg products and ND~1.92 for meats. In conclusion, the result of this study of nitrate and nitrite in livestock products could be used as one of scientific base datum to determine whether they are naturally occurring or not, including ingredients and their percentage, manufacturing processes, other papers relating to naturally occurring levels of them, and so on.

The Analysis for Minimum Infective Dose of Foodborne Disease Pathogens by Meta-analysis (메타분석에 의한 식중독 원인 미생물들의 최소감염량 분석)

  • Park, Myoung Su;Cho, June Ill;Lee, Soon Ho;Bahk, Gyung Jin
    • Journal of Food Hygiene and Safety
    • /
    • v.29 no.4
    • /
    • pp.305-311
    • /
    • 2014
  • Minimum infective dose (MID) data has been recognized as an important and absolutely needed in quantitative microbiological assessment (QMRA). In this study, we performed a comprehensive literature review and meta-analysis to better quantify this association. The meta-analysis applied a final selection of 82 published papers for total 12 species foodborne disease pathogens (bacteria 9, virus 2, and parasite 1 species) which were identified and classified based on the dose-response models related to QMRA studies from PubMed, ScienceDirect database and internet websites during 1980-2012. The main search keywords used the combination "food", "foodborne disease pathogen", "minimum infective dose", and "quantitative microbiological risk assessment". The appropriate minimum infective dose for B. cereus, C. jejuni, Cl. perfringens, Pathogenic E. coli (EHEC, ETEC, EPEC, EIEC), L. monocytogenes, Salmonella spp., Shigella spp., S. aureus, V. parahaemolyticus, Hepatitis A virus, Noro virus, and C. pavum were $10^5cells/g$ (fi = 0.32), 500 cells/g (fi = 0.57), $10^7cells/g$ (fi = 0.56), 10 cells/g (fi = 0.47) / $10^8cells/g$ (fi = 0.71) / $10^6cells/g$ (fi = 0.70) / $10^6cells/g$ (fi = 0.60), $10^2{\sim}10^3cells/g$ (fi = 0.23), 10 cells/g (fi = 0.30), 100 cells/g (fi = 0.32), $10^5cells/g$ (fi = 0.45), $10^6cells/g$ (fi = 0.64), $10{\sim}10^2particles/g$ (fi = 0.33), 10 particles/g (fi = 0.71), and $10{\sim}10^2oocyst/g$ (fi = 0.33), respectively. Therefore, these results provide the preliminary data necessary for the development of foodborne pathogens QMRA.

A Study on Dose-Response Models for Foodborne Disease Pathogens (주요 식중독 원인 미생물들에 대한 용량-반응 모델 연구)

  • Park, Myoung Su;Cho, June Ill;Lee, Soon Ho;Bahk, Gyung Jin
    • Journal of Food Hygiene and Safety
    • /
    • v.29 no.4
    • /
    • pp.299-304
    • /
    • 2014
  • The dose-response models are important for the quantitative microbiological risk assessment (QMRA) because they would enable prediction of infection risk to humans from foodborne pathogens. In this study, we performed a comprehensive literature review and meta-analysis to better quantify this association. The meta-analysis applied a final selection of 193 published papers for total 43 species foodborne disease pathogens (bacteria 26, virus 9, and parasite 8 species) which were identified and classified based on the dose-response models related to QMRA studies from PubMed, ScienceDirect database and internet websites during 1980-2012. The main search keywords used the combination "food", "foodborne disease pathogen", "dose-response model", and "quantitative microbiological risk assessment". The appropriate dose-response models for Campylobacter jejuni, pathogenic E. coli O157:H7 (EHEC / EPEC / ETEC), Listeria monocytogenes, Salmonella spp., Shigella spp., Staphylococcus aureus, Vibrio parahaemolyticus, Vibrio cholera, Rota virus, and Cryptosporidium pavum were beta-poisson (${\alpha}=0.15$, ${\beta}=7.59$, fi = 0.72), beta-poisson (${\alpha}=0.49$, ${\beta}=1.81{\times}10^5$, fi = 0.67) / beta-poisson (${\alpha}=0.22$, ${\beta}=8.70{\times}10^3$, fi = 0.40) / beta-poisson (${\alpha}=0.18$, ${\beta}=8.60{\times}10^7$, fi = 0.60), exponential (r=$1.18{\times}10^{-10}$, fi = 0.14), beta-poisson (${\alpha}=0.11$, ${\beta}=6,097$, fi = 0.09), beta-poisson (${\alpha}=0.21$, ${\beta}=1,120$, fi = 0.15), exponential ($r=7.64{\times}10^{-8}$, fi = 1.00), betapoisson (${\alpha}=0.17$, ${\beta}=1.18{\times}10^5$, fi = 1.00), beta-poisson (${\alpha}=0.25$, ${\beta}=16.2$, fi = 0.57), exponential ($r=1.73{\times}10{-2}$, fi = 1.00), and exponential ($r=1.73{\times}10^{-2}$, fi = 0.17), respectively. Therefore, these results provide the preliminary data necessary for the development of foodborne pathogens QMRA.

The Design of Broadband Ultrasonic Transducers for Fish Species Identification - Dual Resonance Design of a Ultrasonic Transducer Using a Single Acoustic Matching Layer - (어종식별을 위한 광대역 초음파 변환기의 설계 II - 단일음향정합층을 이용한 이중공진형 변환기의 설계 -)

  • 이대재
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.34 no.1
    • /
    • pp.74-84
    • /
    • 1998
  • A doubly resonant ultrasonic transducer has been designed as an attempt to increase the bandwidth of underwater transducers. The dual resonance conditions were accomplished by attaching a single acoustic matching layer on the front face of a Tonpilz transducer consisted of an aluminum head, a piezoelectric ring, a brass tail and a prestress bolt. A modified Mason's model was used for the performance analysis and the design of transducers, and the constructed transducers were tested experimentally and numerically by changing the impedances and thicknesses of the head, tail and matching layers in the water tank. Two distinct resonance peaks in the transmitting voltage response(TVR) of a developed transducer were observed at 34.3 and 40.4 kHz, respectively, with the difference frequency of 6.1kHz and the center frequency of 37.2kHz. The values of TVR at these frequencies were 136.5 dB re $1\;\muPa/V$ at 34.3 kHz and 136.8 dB re $1\;\muPa/V$ at 40.4 kHz, respectively. Reasonable agreement between the experimental results and the numerical results was achieved. From this result, it is expected that the generation of the distinct resonances at any two desired frequencies can be achieved through the proper choice of the matching layer to provide the impedance transformation between the transducer and the medium.

  • PDF

Effects of Hemicellulase on Purple Sweet Potato Bread (헤미셀룰레이즈 첨가가 자색고구마 식빵의 품질에 미치는 영향)

  • Kim, Yeon-Ok;Kim, Mun-Yong;Bing, Dong-Joo;Yoon, Eun-Ju;Lee, Young-Ju;Chun, Soon-Sil
    • The Korean Journal of Food And Nutrition
    • /
    • v.27 no.1
    • /
    • pp.22-30
    • /
    • 2014
  • In this study, purple sweet potato bread was prepared by the addition of 0.005%, 0.010%, 0.015% and 0.020% hemicellulase. It's effect on product quality and consumer evaluation were examined. The results showed that the dough pH and total titratable acidity were not significantly different between samples. In the fermentation power of dough expansion, a 0.015% addition sample was the highest between the samples. The bread pH decreased significantly as hemicellulase was increased, whereas. Bread total titratable acidity was significantly decreased. The addition of hemicellulase samples were significantly higher in specific volume and baking loss than the control sample. The moisture content was not significantly different between samples. In colors, the lightness of the control sample was the highest, the redness of the 0.020% addition sample was the lowest while the yellowness of the control was the lowest. The hardness and the fracturability decreased significantly as hemicellulase was increased. The resilience indicated reverse effects. In consumer evaluation, the color and softness were not significantly different between samples. And the hemicellulase addition of samples was higher in flavor than that of the control sample. The overall acceptability was the highest at 5.67 with a 0.010% addition sample. According to these results, the addition of 0.010% hemicellulase in purple sweet potato bread would be the optimum level.

Study on the Qualitative Discrimination of White, Red, and Black Ginseng Extract (백삼,홍삼과 흑삼 추출물의 정성적 구별법에 관한 연구)

  • Lee, Young-Sang;Im, Deok-Ho;Yang, Jin-Chul;Noh, Deok-Soo;Kim, Kwang-Il;Oh, Soo-Kyo;Choi, Kyo-Chan;Cha, Yun-Hwan
    • The Korean Journal of Food And Nutrition
    • /
    • v.24 no.1
    • /
    • pp.138-143
    • /
    • 2011
  • This study analyzed the maltol quality, composition ratio of fatty acids, and contents of phenolic compounds in white ginseng extracts(four types), red ginseng extracts(five types), black ginseng extracts(two types), and Chinese ginseng extracts(nine types). By examining patterns in these measurements, we determined the characteristic factors of the extracts and measured the possibility of qualitative analysis. In the analysis of maltol using TLC, white ginseng extracts were not detected while red and black ginseng extracts were detected, so the possibility of detection was considered as a characteristic factor for qualitative analysis. Regarding the composition of fatty acids, palmitic and linoleic acids were the main fatty acids in the ginseng extracts palmitic acid was high in white ginseng extracts while linoleic was low in red ginseng extracts. Regarding the ratio(Pal/Lin) of the two fatty acids, there was a large difference between white ginseng extracts(56.7~64.3%) and red ginseng extracts(32.0~38.5%), and these figures seemed to be characteristic factors for the analysis. For the phenolic compounds, extracts contained maltol, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, and cinnamic acid. White ginseng extracts contained similar percentages of phenolic compounds while red ginseng extracts had high maltol content. According to the measurement results of the percentages of maltol and cinnamic acid, white ginseng extracts showed values below five, whereas red and black ginseng extracts showed 53~289, which was also a characteristic factor for qualitative analysis. Consequently, we found that we can differentiate between ginseng extracts using characteristic factors that we analyzed in an experiment on white ginseng extracts from China.

Degree of Retrogradation of Non-Waxy and Waxy Rice Cakes during Storage determined by DSC and Enzymatic Methods (DSC와 효소법을 이용한 멥쌀 밑 찹쌀떡의 노화도에 관한 연구)

  • 김창순
    • Korean journal of food and cookery science
    • /
    • v.12 no.2
    • /
    • pp.186-192
    • /
    • 1996
  • Retrogradation of non-waxy rice (NWR) and waxy rice (WR) cakes (45% moisture) stored at 5$^{\circ}C$, $25^{\circ}C$ and -2$0^{\circ}C$ was studied by differential scanning calorimetry (DSC) and enzymatic ($\beta$-amylase-puuulanase) method. With DSC, endotherms did not appear with rice cakes stored at room ($25^{\circ}C$) and deep freezing (-2$0^{\circ}C$) temperatures but did with samples stored at low temperature (5$^{\circ}C$), showing accelerated retrogradation by low temperature. Onset temperature (To) and peak temperature (Tp) did not change under 14 days at 5$^{\circ}C$ but enthalpy values ($\Delta$H) increased rapidly within one day and increased steadily until 5th day of storage, then equilibrated. Higher $\Delta$H were obtained with WR cakes than NWR cakes. It was suggested that more amylopectin recrystallization occured with WR than NWR. Degrees of gelatinization of rice cakes determined by enzymatic method increased in the following order: 5$^{\circ}C$ < $25^{\circ}C$ < -2$0^{\circ}C$. In contrast with DSC results, dogrees of gelatinization of NWR cakes, were relatively lower than that of WR cakes. However, increased retrogradation extents (melting enthalpies) caused reduced enzyme susceptibilities to $\beta$-amylase-pullulanase system, among NWR or WR cakes stored at 5$^{\circ}C$. The degrees of retrogradation of rice cakes stored at 5$^{\circ}C$ were higher than those stored at $25^{\circ}C$ and -2$0^{\circ}C$ without regard to the kind of rice. The higher sensitivity of the enzymatic method was obtained than that of DSC method when the degrees of retrogradation of rice cakes were determined during storage under this experiment conditions.

  • PDF