• Korean Journal of Veterinary Service
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• v.37 no.3
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• pp.191-196
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• 2014

This study was conducted to compare the contents of preservatives and general composition on four different types of cheese to provide useful data and information to the consumer. We analyzed preservatives (sorbic acid, benzoic acid, dehydroacetic acid, methyl p-hydroxy benzoate, ethyl p-hydroxy benzoate, propionic acid) and general composition (moisture, protein, fat) from total 102 cheeses which are 46 sliced cheeses, 22 string cheeses, 20 cream cheeses and 14 pizza cheeses. Preservatives were detected from total 14 samples, which are suitable for the authorized limits in Korea. Sorbic acid was detected from 13 samples (197.3~1,736.1 mg/kg) and propionic acid was detected from 1 sample (362.7 mg/kg). Considering from each type of cheese, cream cheese showed the high detection rate (60%); 12 samples of cream cheese contained sorbic acid. The moisture, protein and fat contents of cheeses were in the ranges of 44.3~56.8%, 7.2~24.6% and 19.6~26.8%. Cream cheese had the highest level of moisture (56.8%) and fat (26.8%), but protein level is very low (7.2%).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.2
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• pp.230-239
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• 2018

Objective: The purpose of this study is to identify the kinds and exposure levels of health hazards in the metalworking process in relation to acute poisoning accidents caused by methanol in 2016. Methods: The number of industries, workplaces, exposed workers, regional distribution, and exposure level of health hazards in metalworking process were investigated based on employee exposure assessment database provided by KOSHA (the Korea Occupational Safety and Health Agency), which was collected from workplace hazard evaluation programs in Korea. Exposure metrics for methanol were assessed by RCR (risk characterization ratio). Results: The numbers of processes, workplaces, and exposed workers of metalworking, which include CNC (computer numerical control) were 25, 14,405, and 169,102 respectively. The numbers of samples of chemical hazards including methanol were 91,325, and it was found that workers in metalworking were exposed to 249 kinds of chemical hazards. There were 16 kinds of special controlled substances including beryllium. It is estimated that the number of workplaces involving CNC process was 2,537, and the number of exposed workers was 27,976. In CNC process, the total number of workplaces handling methanol was 36, and 298 workers were estimated to be exposed. There was no exceeded that surpassed the OEL and 49% of samples were below the limit of detection. Methanol exposure concentrations in Gyeonggido Province were statistically significantly higher than in other areas (p <0.0001). Conclusions: In the metalworking process including CNC, there is exposure to a wide variety of health hazards. There was no sample exceeding the OEL for methanol. Therefore, it is necessary to recognize the limits of the employee exposure assessment system and urgently improve measures to prevent the occurrence of events like methanol poisoning.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.4
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• pp.442-451
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• 2019

Objectives: The aim of this study was to review the reduction methods for ammonia (NH₃) and hydrogen sulfide (H₂S) exposure in livestock. Methods: By reviewing domestic and international research reports from Korea and China, reducing ammonia and hydrogen sulfide in livestock pens was analyzed in terms of ventilation, deodorant, and feed additives. In addition, exposure limits in Korea and China were examined through a comparison between 'TLV-TWA and STEL under the Industrial Safety and Health Act in Korea' and 'Management Standards for Air of Livestock Pens in China'. Results and Discussion: In order to effectively control hazardous gases and odors in livestock pens, the enhancement of natural ventilation or the addition of ventilation fans at the pollution source are being examined. Deodorants are used as adsorbents or masking deodorants. Additives to feed were zeolite powder, FeSO₄·7H₂O, enzymes, and microbial preparations. Use of feed additives was low-cost and had significant effects compared to other methods. Zeolite was the most commonly used in feed additive in Chinese cases and proved to be low-cost and effective for reducing harmful gases. Enzyme preparations were shown to stimulate the growth of livestock, but were expensive. Conclusions: This study reviewed and examined domestic and international research papers in Korea and China for reducing ammonia and hydrogen sulfide concentrations in livestock pens. More diverse research and the development of feed additives are needed.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.42-47
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• 2019

In this study, combustion characteristics were measured by selecting di-n-buthylamine, which is widely used as an emulsifier, insecticide, additive, rubber vulcanization accelerator, corrosion inhibitor, and raw material for dye production. The flash point of the di-n-buthylamine was measured by Setaflash, Pensky-Martens, Tag, and Cleveland testers. And the AIT of the di-n-buthylamine was measured by ASTM 659E. The explosion limits of the di-n-buthylamine was calculated using the measured flash points by Setaflash tester. The flash point of the di-n-buthylamine by using Setaflash and Pensky-Martens closed-cup testers were experimented at 38 ℃ and 43 ℃, respectively. The flash points of the di-n-buthylamine by Tag and Cleveland open cup testers were experimented at 48 ℃. The AIT of the di-n-buthylamine was experimented at 247 ℃. The LEL and UEL calculated by using lower and upper flash points of Setaflash tester were calculated at 0.69 vol% and 7.7 vol%, respectively. The measurement of the flash point measurement and the calculation method of the explosion limit prediction presented in this study can be used to study the fire and explosion characteristics of the other combustible liquids.

• Progress in Superconductivity and Cryogenics
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• v.16 no.4
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• pp.66-70
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• 2014

The superconducting fault current limiter (SFCL) is an electrical power system device that detects the fault current automatically and limits the magnitude of the current below a certain safety level. The SFCL module does not have any electrical resistance below the critical temperature, which facilitates lossless power transmission in the electric power system. Once given the fault current, however, the superconducting conductor exhibits extremely high electrical resistance, and the magnitude of the current is accordingly limited to a low value. Therefore, SFCL should be maintained at a temperature below the critical temperature, which justifies the cryogenic cooling system as a mandatory component. This report is a study which reported on the cooling system for the 154 kV-class hybrid SFCL owned by Korea Electric Power Corporation (KEPCO). Using the cryocooler, the temperature of liquid nitrogen (LN2) was lowered to 71 K. The cryostat was pressurized to 5 bars to improve the dielectric strength of nitrogen and suppress nitrogen bubble foaming during operation of SFCL. The SFCL module was immersed in the liquid nitrogen of the cryostat to maintain the superconducting state. The performance test results of the key components such as cryocooler, LN2 circulation pump, cold box, and pressure builder are shown in this paper.

• Journal of the Korean Dietetic Association
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• v.12 no.2
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• pp.157-171
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• 2006

This study was intended to suggest HACCP-based standard recipe for bellflower roots, classified as no thermal cooking process, served in a university foodservice operation. The time-temperature and microbial contamination level in each cooking step were analyzed. The temperatures of bellflower root, peeled garlic and green onion at receiving were at 13.8$\pm$2.8, 12.6$\pm$2.9 and 13.7$\pm$$0.8^\circC$ respectively, which were above the temperature limit. The time consumed for pre-preparation was up to 90 min at room temperature having high microbial growth potential. The levels of total plate counts (TPC) of bellflower root and garlic were over the limit of $10^6$ CFU/g as were the numbers of coliforms in bellflower roots. There were no microbial reductions in pre-preparation and cooking, which resulted in over $10^5$- $10^6$ CFU/g of TPC at service step. Two CCPs identified were washing/sanitation at pre-preparation and service steps. The control measures were washing/sanitation and temperature control. It was verified that CCPs for no cooking process developed in preceding studies were applicable for the microbiological food safety of this menu item. The HACCP-based standard recipe was developed to produce a quantity for 100 servings by observing the critical limits established for CCPs. These results suggest that the selection of proper provider is imperative to control the microbial contamination of raw materials at purchasing step. Also, the sanitary education program should be developed for the employees to understand and comply the HACCP plan and standard recipe.

• Journal of Digital Contents Society
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• v.18 no.4
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• pp.733-738
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• 2017

This study is to find out empirically how the fear of crime is affected by the level of recognition of people. CPTED elements including natural surveillance, access control, utilization enhancement, territoriality securement, etc. Safety of residents could be considered and then increased when we plan, design, and operate a city. In Korea, CPTED is currently being applied to every town. However, it is not systemized and neither efficient, for there are no constraint provisions, and the foreign cases are not specifically customized to the current situation of the country. This study, therefore, aims to find the limits from analyzing related laws and regimes, administrative regulations, and applied cases, and to deduct improvement plans based on examined foreign cases.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.73-73
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• 2012

Modern technology-driven society largely relies on hybrid electric vehicles or electric vehicles for eco-friendly transportation and the use of high technology devices. Lithium rechargeable batteries are the most promising power sources because of its high energy density but still have a challenge. Graphite is the most widely used anode material in the field of lithium rechargeable batteries due to its many advantages such as good cyclic performances, and high charge/discharge efficiency in the initial cycle. However, it has an important safety issue associated with the dendritic lithium growth on the anode surface at high charging current because the conventional graphite approaches almost 0 V vs $Li/Li^+$ at the end of lithium insertion. Therefore, a fundamental solution is to use an electrochemical redox couple with higher equilibrium potentials, which suppresses lithium metal formation on the anode surface. Among the candidates, $Li_4Ti_5O_{12}$ is a very interesting intercalation compound with safe operation, high rate capability, no volume change, and excellent cycleability. But the insulating character of $Li_4Ti_5O_{12}$ has raised concerns about its electrochemical performance. The initial insulating character associated with Ti4+ in $Li_4Ti_5O_{12}$ limits the electronic transfer between particles and to the external circuit, thereby worsening its high rate performance. In order to overcome these weak points, several alternative synthetic methods are highly required. Hence, in this presentation, novel ways using a synergetic strategy based on 1D architecture and surface coating will be introduced to enhance the kinetic property of Ti-based electrode. In addition, first-principle calculation will prove its significance to design Ti-based electrode for the most optimized electrochemical performance.

• Fire Science and Engineering
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• v.34 no.4
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• pp.45-51
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• 2020

The aim of this study is to investigate the gas temperature and velocity during sprinkler activation considering the fire growth scenario based on the thermal response model of the sprinkler. The fire source is assumed to have time square fire growth scenarios with a maximum heat release rate of 3 MW. Eight types of standard and fast-response sprinkler heads with an operating temperature range of 65-105 ℃ and a response time index range of 25-171 m^1/2s^1/2 were adopted. The temperature difference between the gas stream and the sensing element of the sprinkler head decreased as the fire growth slowed down, and the RTI value decreased. The overall gas temperature and velocity conditions predicted using the FDS model at sprinkler activation were in reasonable agreement with those of standard test conditions of the sprinkler head response. However, the sprinkler head could be activated at lower limits of gas temperature and velocity under the current test conditions for a slowly growing fire scenario.

• Journal of Microbiology and Biotechnology
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• v.20 no.10
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• pp.1463-1470
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• 2010

E. coli has long been widely used as a host system for the manufacture of recombinant proteins intended for human therapeutic use. When considering the impurities to be eliminated during the downstream process, residual host cell DNA is a major safety concern. The presence of residual E. coli host cell DNA in the final products is typically determined using a conventional slot blot hybridization assay or total DNA Threshold assay. However, both the former and latter methods are time consuming, expensive, and relatively insensitive. This study thus attempted to develop a more sensitive real-time PCR assay for the specific detection of residual E. coli DNA. This novel method was then compared with the slot blot hybridization assay and total DNA Threshold assay in order to determine its effectiveness and overall capabilities. The novel approach involved the selection of a specific primer pair for amplification of the E. coli 16S rRNA gene in an effort to improve sensitivity, whereas the E. coli host cell DNA quantification took place through the use of SYBR Green I. The detection limit of the real-time PCR assay, under these optimized conditions, was calculated to be 0.042 pg genomic DNA, which was much higher than those of both the slot blot hybridization assay and total DNA Threshold assay, where the detection limits were 2.42 and 3.73 pg genomic DNA, respectively. Hence, the real-time PCR assay can be said to be more reproducible, more accurate, and more precise than either the slot blot hybridization assay or total DNA Threshold assay. The real-time PCR assay may thus be a promising new tool for the quantitative detection and clearance validation of residual E. coli host cell DNA during the manufacturingprocess for recombinant therapeutics.