• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.251-254
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• 2009

건설 분야에서 FRP(Fiber Reinforced Polymers) 부재는 기존의 건설부재에 비해 많은 장점을 가지고 있어 여러 분야에서 연구 및 개발이 이루어지고 있다. 그중 FRP 재료를 이용한 교량 부재들이 해외 뿐만 아니라 국내에서도 연구되고 있으며, FRP 인장재 및 바닥판은 연구 및 개발이 완료돼 현재 시공 중에 있고 FRP 휨 부재 또한 연구가 활발히 진행되고 있다. 이런 FRP 부재는 외부 환경에 그대로 노출됨으로써, 온도 등의 주위 환경의 변화에 많은 영향을 받게 되며, 특히 높은 온도에 취약한 성질을 가지고 있다. 이에 본 연구에서는 FRP 부재의 온도에 따른 역학적 특성을 파악하기위한 실험적 연구로써, $-21^{\circ}C$, $100^{\circ}C$, $200^{\circ}C$에 각각 1시간씩 시험체를 보관한 뒤 내구성 실험을 실시하였다. 각각의 시험체는 FRP 모듈형 박스부재에서 4개씩 채취하였으며, 실험 실시 후 SEM촬영을 실시하여 파괴모드를 분석하였다. 실험 결과 저온일 때는 강도변화가 많이 나타나지 않았으나 고온일 때 압축 및 휨강도의 급격한 저조를 확인할 수 있었다. 고온 보관 시험체의 SEM(Scanning Electron Microscope) 촬영결과 수지의 손상으로 낮은 강도가 측정되는 것을 확인할 수 있었다.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.459-467
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• 2020

In this study, we investigated the changes in both ambient temperature and microbial contamination of fresh convenience foods (FCFs) caused by the behavior of consumers after purchase. According to consumer survey results, it took 0.5 to 3 h put the purchased FCF in a home refrigerator or consume it. Only aerobic bacteria and Staphylococcus aureus (below maximum permitted limit) were detected in FCFs obtained from a local market. During storage of FCFs in a vehicle trunk for up to 3 h. the external and internal temperatures of FCFs were found to be 19 and 18.5℃ in spring, 44 and 42℃ in summer, 31.3 and 29.2℃ in autumn, and 17.6 and 16.8℃ in winter, respectively. Changes in contamination levels of aerobic bacteria on FCFs stored in a vehicle trunk for up to 3 hours are as follows: 2.72 → 3.41 log CFU/g in spring, 3.11 → 4.32 log CFU/g in summer, 3.08 → 3.81 log CFU/g in autumn, 2.71 → 3.36 log CFU/g in winter. S. aureus exceeding the tolerance was detected even when the FCFs were stored in a vehicle trunk for 1 h in summer and autumn and 2 h in spring and winter. Among three boxes (corrugated box, styrofoam box, and corrugated box coated with an aluminum film), the styrofoam box maintained the lowest temperature and showed the lowest growth rate of microorganisms on FCF after storage for 3 h in the vehicle trunk depending on whether ice was added. These results indicated that the possibility of food poisoning occurs when FCFs are exposed to the external environment. It is necessary to provide guidelines regarding storage temperature and allowable time for safe consumption of FCFs after purchase.

• The Hankook-Saengyark Bo
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• no.226
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• pp.5-5
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• 1998

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2000.04a
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• pp.12-13
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• 2000

최근 플라스틱제 식품 포장재에 대한 환경학적 문제가 제기됨으로 인하여 다양한 곡류 단백질의 필름 형성능력에 많은 관심이 모아지고 있다. 단백질 필름으로서 soy protein, wheat gluten, rice bran, corn zein, glatin 및 colloagen 등의 소재들이 많은 관심을 모으고 있으며, 비교적 필름 형성력이 뛰어나고, 저렴한 가격으로 구입할 수 있는 대두 단백질에 커다란 관심이 모아지고 있는 실정이다. 이들 물질로부터 제조된 가식성 필름 및 코팅제들은 식품의 보존기간을 연장시킬 뿐만 아니라 수분 및 용질의 이동을 방지하여 식품의 품질을 개선시킬 수 있다. 또한 이들 필름 및 코팅제들은 산소 및 이산화탄소의 이동, 이로 인한 지방 산화 그리고 휘발성 향기성분들의 감소 등을 조절할 수 있다. 대두 단백질 필름의 사과 코팅제로서의 이용은 개별적 포장이 용이하지 않는 제품들의 코팅제로서 활용하여 대두 단백질 필름 및 코팅제의 잠재적 시장성을 확인하는 하나의 응용분야이다. 본 실험의 목적은 대두 단백질 코팅제를 후지와 golden delicious 사과에 코팅하여 상온 (22$^{\circ}C$)과 냉장온도(2-4$^{\circ}C$)에서 60일동안 보관하여 색도, 경도 및 산도 변화 등을 측정하여 저장 중 사과의 품질에 미치는 영향을 조사하였다. 대두 단백질 코팅제는 대두 단백 용액들 (5g, 8g, 10g/100mL water)에 glycerin (50% w/w의 단백질)을 가소재로 첨가한 후 알칼리 용액으로 pH 9.0에 맞추었다. 그런후 85$^{\circ}C$에서 30분간 가열하여 코팅제를 준비하였다. 후지 사과(붉은색)와 golden delicious 사과 (초록색)를 dipping 방법으로 코팅하여 60일도안 실온과 냉장온도에 저자하여 보존기간의 연장을 확인하였다. 사과품질의 결정인자는 Hunter L, a, b 색도값과 사과의 조직의 강도 (외부 및 내부) 그리고 산도 등을 측정하였다. 코팅된 후지 및 golden delicious 사과의 표피 및 내부 경도는 control과 비교하여 높은 경도를 유지하였다. 또한 냉장온도에서 30일 동안 보관하였을 때, control 사과와 거의 비슷한 경도를 유지하였다. 식품의 색도를 소비자의 기호를 결정하는 중요한 인자이다. 대두 단백질로 코팅된 후지 사과는 상온에서 20일 동안은 control에 비하여 약간의 색도의 증가를 보였으나, 그 후 60일 동안은 색도의 증가를 보이지 않았다. 그러나 냉장 보관한 control 후지 사과에 비하여 색도의 증가가 관찰되었다. 대두 단백질 코팅제가 사과의 색도 변화를 방지하는 효과를 가졌으나, 저장 온도가 색도의 변화에 더욱 큰 영향을 미침을 알 수 있었다. 대두 단백질로 코팅된 golden delicious는 상온에서60일 동안 보관하였을 경우, 사과표피의 색도 변화를 현저히 지연시킴을 확인하였다. 또한 control과 비교하여 성공적으로 사과에 코팅하였으며, 상온에서 보관하여을 때 사과의 품질을 30일 이상 연장하는 효과를 관찰하였다. 이들 결과로부터 대두단백질 필름이 과일 등의 포장제로서 이용할 가능성을 확인하였다.

• Korean Journal of Food Science and Technology
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• v.29 no.6
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• pp.1213-1221
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• 1997

Effects of the addition of three commercial oligosaccharide syrups into a Korean rice cake (Karedduk) on the textural characteristics and retrogradation of the rice cake were examined during the storage for 5 days at $25^{\circ}C$ and $4^{\circ}C$. Each syrups contained maltose (M75), isomaltose and panose (HL), or maltotetraose (G4) as major sugars. The increment (rates) in gumminess, hardness and chewiness during the storage were significantly reduced by replacing rice flour (up to 10%) with the oligosaccharides. The retardation in the textural changes by the oilgosaccharides was more significant when the rice cake was stored at $25^{\circ}C$ than at $4^{\circ}C$. Among the three types, HL exhibited most effective in retarding the textural changes. Thermograms by a differential scanning calorimeter (DSC) showed that the oligosaccharide increased the onset temperatures and enthalpy for the starch melting, but the recrystallinity measured from the enthalpy ratio before and after the storage was significantly reduced by the presence of the oligosaccharide. Especially with 5% HL, the recrystallinity was significantly low (72.7%) compared to rice cake without HL (88.1%). Therefore, HL had great efficiency in retarding starch retrogradation as well as textural changes of the rice cake during the storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.582-587
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• 1997

The changes of ascorbic acid(AsA) and dehydroascorbic acid(DHAA) contents in distilled water, carrot juice, and carrot+vegetable juices under different incubation time and temperature were determined by using high performance liquid chromatography. AsA in carrot juice was more stable than that in distilled water. AsA contents in distilled water and carrot juice were gradually reduced in a time and temperature dependent manner. AsA contents in carrot juice and carrot+ vegetable juices stored in refrigerator(4$^{\circ}C$) for 2 and 24 hours appeared to decrease, but the DHAA contents in all samples increased. Total vitamin C(AsA+DHAA) contents in carrot juice and carrot +vegetable juices remained with the high residue values of 90~97% after incubating at 4$^{\circ}C$ for 2 and 24 hours.

• Food Science and Preservation
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• v.18 no.1
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• pp.7-12
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• 2011

Paprika is a major export of Korea, but biosafety is important if exports are to grow. To date, few paprika biosafety data are available. We evaluated microbiological contamination of paprika, and determined bacterial levels with respect to storage temperature. Mean counts of total aerobic bacteria were $2.3{\pm}0.3\;log_{10}\;CFU/g$, but coliforms were not isolated. Staphylococcus aureus, Salmonella spp., Listeria spp., and Escherichia coli O157 were also not detected. When bacterial contamination of paprika stored at room temperature or $4^{\circ}C$ for 20 days was evaluated, the numbers of total aerobic bacteria peaked at 14-16 days at room temperature (4 times more than those of $4^{\circ}C$). However, aerobic bacteria grew slowly at $4^{\circ}C$. Coliforms were also detected twice at room temperature, but not upon storage at $4^{\circ}C$. The results indicate that the paprika exported from Korea is relatively biosafe. However, food hygiene issues must be addressed to reduce contamination during storage and distribution.

• Korean journal of food and cookery science
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• v.26 no.3
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• pp.335-345
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• 2010

The objective of this study was to model the kinetics of S. aureus survival on high risk foods in school foodservice operations. After inoculating S. aureus ATCC25923 onto the various high risk foods, the effects of competitive microorganism, storage temperatures($25^{\circ}C$, $35^{\circ}C$), and initial contamination levels ($1.0{\times}10^2\;CFU/g$, $1.0{\times}10^5\;CFU/g$) on the growth of S. aureus were investigated. Lag time decreased and specific growth rate increased with a storage temperature ($25^{\circ}C$<$35^{\circ}C$) and with a higher initial inoculation level ($1.0{\times}10^2\;CFU/g$<$1.0{\times}10^5\;CFU/g$). Previously it was shown that S. aureus is a weaker competitor than other organisms, but it proliferates aggressively in a noncompetitive environment. However, in our study, when S. aureus was used to inoculate japchae (glass noodles with sauteed vegetables) and meat ball, the growth of S. aureus was similar and more active with competitive organisms than that without competitive organisms. Regardless of other factors, the initial level of S. aureus was a more significant factor of the growth. High inoculation levels of S. aureus were reached at 6 log CFU/g within 3 hours. An incubation temperature of $35^{\circ}C$ and the animal protein component of menu items also were identified as significant factors influencing the growth of S. aureus. Therefore, the duration of time meals are stored before serving should be considered a critical control point. Food service providers must control time and temperature to insure the safety of cooked foods.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.2
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• pp.105-112
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• 2017

The mixing of rice and brown rice produced in different years is banned in Korea by the grain management act. However, there has been no reported method for discriminating the production year of rice. The objective of this study was to develop a method for discriminating the production year of rice and brown rice based on their phospholipids content. One hundred rice samples and 130 brown rice samples produced between 2012 and 2015 were collected. Twelve phosphatidylcholine components were analyzed by liquid chromatography-tandem mass spectrometry. Phosphatidylcholine was used as an internal standard to calculate the peak intensity of the samples. A statistical analysis of the results showed that the centroid distance between the stale and new rice was 4.16 and the classification ratio was 97%. To verify the calculated discriminant, 61 and 40 rice samples were collected. The accuracy of discrimination was 82% by primary verification and 80% by secondary verification. The statistical analysis of brown rice showed that the centroid distance between the stale and new brown rice was 3.14 and the classification ratio was 96%. To verify the calculated discriminant, 10 samples of new rice and 30 samples of stale rice were collected and the accuracy of discrimination was 93%. The accuracy of discrimination for rice stored at room temperature was 57.9-92.1% and that for rice stored at a low temperature was 86.8-94.7%, depending on the storage period. For brown rice, the detection accuracy was 94.7-100% at room temperature and 92.1-100% at a low temperature, depending on the storage period. The accuracy of discrimination for rice was affected by the storage temperature and time, while that for brown rice was more than 92% regardless of the storage conditions. These results suggest that the developed discriminant analysis method could be utilized to determine the production year of rice and brown rice.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.277-284
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• 2012

The objective of this study was to investigate and evaluate microbial contamination levels of leafy greens (perilla leaf and lettuce) and its distributing conditions at different seasons (Feb, May, Aug, and Nov of the year 2011) in order to provide insight into any potential health hazards associated with consumption of these commodities. Leafy greens were collected from a farm located in Geumsan, Chungnam and wholesale markets (WM) and traditional markets (TM) located in Suwon. At the same time, temperature and relative humidity fluctuations experienced by the leafy greens during distribution from the farm to the distribution center were measured by a data logger. The contamination levels of perilla leaf and lettuce were determined by analyzing total plate count. Coliform groups, Bacillus cereus, Escherichia coli, Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes and Staphylococcus aureus were determined. The contamination levels of total aerobic bacteria, coliform groups and B. cereus in both vegetables sampled during May and August found to be higher than those sampled during February and November. E. coli O157:H7, Salmonella spp., L. monocytogenes were not detected in the vegetables analyzed in this study. There were no significant trends between samples at WM and TM in the contamination levels. Relative humidity of vegetables distributed from the farm to the distribution center showed over 90% during distribution regardless of measured seasons. In the case of background microflora on leafy greens, the density was significantly increased at 20, 30 and $37^{\circ}C$ during storage of 24h. E. coli O157:H7 and B. cereus inoculated on the leaves also showed similar increases in the storage tests. The microbial contamination levels determined in this study may be used as the fundamental data for microbial risk assessment.