• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2013.04a
• /
• pp.115-115
• /
• 2013

최근의 분진폭발은 플라스틱, 의약품, 목재, 곡물 저장고, 고체연료, 화학제품 제조공정 등을 포함하여 성형 및 가공 공정 등에서 화재폭발사고가 발생되고 있다. 폐목재를 재활용하여 PB(Particle board)를 생산하는 국내 제조사업장에서는 화재폭발 사고가 빈번히 발생하고 있어 예방대책이 요구되고 있다. 본 연구에서는 폐목재 제조공정의 사고예방과 목재분진 취급공정에 대한 안전대책 등을 제시하기 위하여 사고원인 물질인 폐목재 부유분진의 폭발특성실험을 실시하고 실험결과를 검토하였다. 또한 폐목재 분진의 화재폭발위험성을 상세히 평가하기 위하여 해당 물질의 자연발화점, 축열저장시험, 및 최소점화에너지 등의 화재폭발위험특성값을 실험적으로 조사하였다. 본 연구에서 사용한 폐목재 시료의 비구형 입자형태를 가지는데 입도분석기의 측정 결과 평균 입경은 $15.96{\mu}m$로 조사되었다. 또한 목재 분진의 함수율은 3.88%이며 중금속함유량은 1.73%이다. 자연발화점 측정결과 $225.5^{\circ}C$로서 비교적 낮게 측정되었고 퇴적분진에 대한 화재의 위험성은 높게 나타났다. 반면에 축열저장시험 결과를 통하여 공정관리 온도 및 보관온도를 $150^{\circ}C$ 이하로 관리하면 축열에 의한 자기분해 위험성은 낮은 것으로 판단되었다. 그러므로 축열에 의한 화재폭발 등의 위험성은 낮은 것으로 사료 된다. 최대폭발압력($P_{max}$)은 8.7 bar이며 폭발하한농도 (LEL)는 $60g/m^3$으로 나타났다. 부유분진의 폭발특성실험 결과 분진폭발지수(Kst)는 폭발등급 St 1 (0$bar{\cdot}m/s$)으로 나타났으며 폭발에 의한 위험성이 약한 분진으로 판정되었다. 최소점화에너지(MIE)는 10mJ < MIE <30mJ의 범위로 측정되었으며, 계산에 의해 추정된 최소점화 에너지(Es) 값은 14 mJ로서 일반적인 발화감도(Normal ignition sensitive)로 분류되었다. 이는 실질적인 점화원만 제거하여도 분진폭발을 예방할 수 있다는 것을 의미한다. 그러나 분진 폭발사고를 예방을 위하여 MIE값이 공정운전온도 $100^{\circ}C$ 초과 시에 급격히 낮아질 수 있으므로 운전 온도 설정에 있어서 주의가 필요하다.

• Proceedings of the KAIS Fall Conference
• /
• 2008.11a
• /
• pp.465-468
• /
• 2008

현재 가장 범용적으로 사용되는 미생물 배양 용기인 Petri Dish는 배지 제조 후 냉장과 실온 보관 시수분 증발에 대한 보호 효과가 적어 세 달 이상 보관하기 어려운 단점이 있어 즉시 사용 배지(pre-plated media) 개발에 장애가 되고 있다. 본 연구는 미생물 배지의 장기 저장이 가능하도록 고안된 LOP plate의 수분 보호능에 관한 것으로, LB 배지를 표준 배지로 해서 4, 25, 32 및 $37^{\circ}C$ 네 개의 온도영역과 진공 포장 및 비 포장 조건에서 Petri Dish와 비교한 결과, 각 온도 조건별로 LOP의 탁월한 수분 보호능을 확인 할 수 있었다. 따라서 향후 LOP를 이용한 장기 저장과 즉시 사용이 가능한 pre-plated media와 관련된 제품 개발이 가능할 것으로 기대된다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.3
• /
• pp.534-544
• /
• 2017

In order to use the sea flowering plant, Zostera marina, as a cosmetic ingredient, this study was conducted to evaluate its antioxidant effect. We confirmed the formulation stability of the emulsion containing Zostera marina extracts. We studied the antioxidant activity of the dissolved Zostera marina extracts through the DPPH (1,1-Diphenyl-2-picrylhydrazy) radical scavenging activity assay and SOD (superoxide dismutase)-like activity assay. Also, the pH, viscosity and particle dispersion of the emulsion containing Zostera marina extracts were measured using a Turbiscan LAB. The emulsions were measured at one-week intervals in a thermostat chamber ($25^{\circ}C{\pm}1^{\circ}C$, $40^{\circ}C{\pm}1^{\circ}C$) for 28 days. The extracts of Zostera marina showed a DPPH radical scavenging rate of 86.21% and SOD-like activity of 99.24% at 5.00 mg/ml and exhibited a dose-dependent increase in their antioxidant activity. We measured the stability of the pH, viscosity and emulsion particles using the Turbiscan LAB in a thermostat chamber for 28 days. The formulations to which the Zostera marina extracts were added were considered to be stable, due to their negligible physical property changes over time during storage. The results suggest that the Zostera marina extracts with 70% ethanol (v/v) could be used in cosmetics as an antioxidant for the anti-aging of skin.

• Journal of Fisheries and Marine Sciences Education
• /
• v.28 no.4
• /
• pp.1006-1013
• /
• 2016

The observed external injury, movement and survival rate according to storage and recovery of the juvenile sea cucumber, Apostichopus japonicus(wet weight $1.0{\pm}0.2g$). The investigated application possibility of external injury(grade I~IV) and movement variation(buccal tentacle, motion, obversion, movement) for estimate of survival rate. The survival rate was observed through the recovery after storage of the sea cucumber in various water temperature(10, 15, 20, $25^{\circ}C$) and hours(3, 6, 12, 24 hour). Grade of external injury lower in the 24 hour experiment group of $20^{\circ}C$ water temperature and 12 hour experiment group of $25^{\circ}C$ water temperature. Buccal tentacle and movement strong related survival rate and external injury. In the case of $20^{\circ}C$ water temperature, survival rate was observed decrease 24 hours experiment. $25^{\circ}C$ water temperature was high to 6 hours but 12 hours experiment group observed decrease of the survival rate. The lethal time(LT10) of the juvenile sea cucumber was 15.73 hours($20^{\circ}C$) and 5.57 hours($25^{\circ}C$). The results of this study provided various measurement method of survival rate according to transportation of the juvenile sea cucumber for release.

• Korean Journal of Food Science and Technology
• /
• v.52 no.6
• /
• pp.661-669
• /
• 2020

Samgak-Kimbap is a popular ready-to-eat (RTE) food at convenience stores, in Korea. Although Samgak-Kimbap is distributed through the cold chain supply system, inappropriate temperature storage conditions prior to consumption are a cause of concern. The objective of this study was to evaluate the risk of Staphylococcus aureus growth in Samgak-Kimbap in the retail market. The prevalence and contamination levels of S. aureus in Samgak-Kimbap (n=170) were monitored, and the predictive growth model of a five-strain cocktail of enterotoxin-producing S. aureus (SEA, SEB, SEC, SED, and SEE) was developed in Samgak-Kimbap as a function of temperature (4, 10, 11, 20, 25, and 37℃). We could not observe the growth of S. aureus and enterotoxin-producing S. aureus in Samgak-Kimbap at temperatures below 10℃. The probability of illness with S. aureus per serving of Samgak-Kimbap was 1.44×10-10 per day. The most influential factor in increasing the risk of foodborne illnesses was the contamination level of S. aureus in Samgak-Kimbap.

• Journal of Food Hygiene and Safety
• /
• v.35 no.2
• /
• pp.170-176
• /
• 2020

We investigated the pH, volatile basic nitrogen (VBN), microbial changes and dominant microbes in raw beef, wet-aging beef, and dry-aging beef after the meat had been stored in a refrigerator. The count of mesophilic bacteria was 3.3-3.9 log CFU/g in raw beef and dry-aging beef, and 5.4 log CFU/g in wet-aging meat. After 18 days of refrigeration, the mesophilic bacterial count in raw and aging beef increased to 6.1-6.4 log CFU/g. In wet-aging beef, the number of lactic acid bacteria increased from 4.5 log CFU/g to 6.0 log CFU/g at refrigeration temperature. However, lactic acid bacteria were not detected in dry aging beef. Major foodborne pathogens such as Salmonella spp, Listeria monocytogenes, and Escherichia coli (EHEC) were not detected. Based on the legal standard for mesophilic bacteria count, the estimated shelf-life of aged beef was less than 12 days and the average VBN was 15 mg%. The dominant microorganisms varied between the different types of meat. In raw meat, Staphylococcus saprophyticus was the dominant microorganism, and as the VBN increased, Carnobacterium divergens dominated. In wet-aging beef, Carnobacterium divergens dominated during the initial days of refrigeration after which the number of Lactobacillus sakei increased. Dermacoccus nishinomiyaensis was initially the dominant microbe in dry-aging beef, after which Pseudomonas fragi dominated. In addition to the role of specific bacteria in the early stage of decay, it is thought that microorganisms can be utilized for safe distribution and storage of matured meats by conducting research on changes in rot, fragrance analysis, and changes of ingredients in matured meats.

• Korean Journal of Food Science and Technology
• /
• v.30 no.6
• /
• pp.1480-1483
• /
• 1998

To know the probable storage conditions for commercially prepared ‘baked egg’ and ‘rolled egg’ products, microbes and quality changes for samples immediately after the production and stored under the several conditions were tested. Sealed samples were stored at 5, 10, 15, $20^{\circ}C$, respectively and tested at 1 or 2-days intervals, opened samples were stored at 15, 20, 30, $37^{\circ}C$, respectively and tested at 6-hr intervals. Coliform bacteria, E. coli, Salmonella, Staphylococci were not detected, and viable cell counts level was under $10^2\;CFU/g$ for samples immediately after the production. The higher the storage temperature and baked eggs rether than rolled eggs showed more rapid microbial growth for both samples. For sealed condition, 14-days at $5^{\circ}C$ for both samples, 7-days for rolled eggs and 5-days for baked eggs at $10^{\circ}C$ were kept their initial microbial level and favorable flavor. For opened condition, it showed remarkable microbial increase after $18{\sim}24\;hr$ for $15{\sim}20^{\circ}C$ and 12 hr for $30{\sim}37^{\circ}C$. From these results, used egg products samples are able to be stored more than 1-week at below $5^{\circ}C$ and opened samples need to be stored at cold storage. At room temperature, it egg products.

• Korean Journal of Environmental Agriculture
• /
• v.30 no.3
• /
• pp.281-287
• /
• 2011

BACKGROUND: According to Korean regulations, bottled waters (BWs) can not be treated with chemical disinfectants like chlorine, so UV and ozone disinfection is applied. During the past several years, chemicals were detected in some BWs, and the public was concerned about the safety of BWs. METHODS AND RESULTS: Mineral waters were stored for 180 days at $25^{\circ}C$ and $50^{\circ}C$, tested acetaldehyde and formaldehyde by HPLC. When mineral waters were put in a PET bottles, the formaldehyde level ranged from 5 to $66{\mu}g/L$ during 180 days at $50^{\circ}C$. While the acetaldehyde level ranged from 31 to $221{\mu}g/L$, it was low than $16{\mu}g/L$ in glass bottle. CONCLUSION(s): This result showed that formaldehyde and acetaldehyde were detected higher in PET bottles than glass bottles, these also increased depending on the time of storage. Concentration of formaldehyde and acetaldehyde could be significantly influenced by the time of storage and temperature.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.3
• /
• pp.268-274
• /
• 2007

In general, rocket or satellite circuit designers focus on reducing temperature of electronic devices in order to enhance electronic unit's reliability. This paper describes the quantitative analysis result of activation energy as well as device temperature effects to the system reliabilities. The quantitative analysis result shows that activation energy of device has more effects on system reliability than temperature does. And this paper suggests a strategy for enhancement of reliability during devices placement on PCB with simulation results.

• Food Science and Preservation
• /
• v.23 no.2
• /
• pp.155-161
• /
• 2016

This study aimed to investigate the effects of pretreatments blanching, roasting, drying, and storage temperatures ($25^{\circ}C$, $4^{\circ}C$ and $-10^{\circ}C$) on their quality of lotus leaves. As a result, the lotus leaves retained a good appearance when stored at $25^{\circ}C$ for 5 days, $4^{\circ}C$ for 30 days, and $-10^{\circ}C$ for 90 days, regardless of the pretreatment used. At the same storage temperatures, pH, soluble solids, total acid content, polyphenols, and microorganisms were significantly different among the pretreatments (p<0.05). Soluble solids, pH, and total acid contents were not significantly different for the same pretreatments at different storage temperatures. However, the polyphenol, oxalic acid, and tartaric acid contents of lotus leaves were significantly different after drying and blanching treatments. In particular, it was shown that polyphenol content of the lotus leaf was affected by both pretreatment and storage temperature. In conclusion, the lotus leaves appeared in good condition until 5 days at $25^{\circ}C$, 30 days at $4^{\circ}C$, and 90 days at $-10^{\circ}C$, regardless of the pretreatment while influenced by storage temperature.