• 조명전기설비학회논문지
• /
• 제25권6호
• /
• pp.68-74
• /
• 2011

The touch or step voltages which exist in the vicinity of a grounding electrode are closely related to the earth structure and resistivity and the ground current. The grounding design approach is required to determine the grounding electrode location where the hazardous voltages are minimized. In this paper, in order to propose a method of mitigating the electric shock hazards caused by the ground surface potential rise in the vicinity of a counterpoise, the hazards relevant to touch voltage were evaluated as a function of the soil resistivity ratio $\rho_2/\rho_1$ for several practical values of two-layer earth structures. The touch voltage and current on the ground surface just above the test electrode are calculated with CDEGS program. As a consequence, it was found that burying a grounding electrode in the soil with low resistivity is effective to reduce the electric shock hazards. In the case that the bottom layer soil where a counterpoise is buried has lower resistivity than the upper layer soil, when the upper layer soil resistivity is increased, the surface potential is slightly raised, but the current through the human body is reduced with increasing the upper layer soil resistivity because of the greater contact resistance between the earth surface and the feet. The electric shock hazard in the vicinity of grounding electrodes is closely related to soil structure and resistivity and are reduced with increasing the ration of the upper layer resistivity to the bottom layer resistivity in two-layer soil.

• 한국포장학회지
• /
• 제11권1호
• /
• pp.17-24
• /
• 2005

During handling unitized products, they are subjected to a variety environmental hazards. Shock and vibration hazards are generally considered the most damaging of the environmental hazards on a product, and it may encounter while passing through the distribution environment. A major cause of shock damage to products is drops during manual handling. The increasing use of unitization on pallets has been resulted in a reduction in the manual handling of products and with it a reduction in the shock hazards. This has caused and increasing interest in research focused on vibration caused damage. the use of pallets as a base for unitizing loads, aids in the mechanical handling, transportation and storage of products. Besides aiding in the handling, transportation and storage of products, a pallet also acts on and interface between the packaged goods and the distribution environment. The determination of the impact deformation of the cushioning materials such as tray cup (polymeric foam) and corrugated fiberboard pad must be carried out to design the proper packaging system providing adequate protection for the fruit, and to understand the complex interaction between the components of fruit when they relate to expected transportation vibration inputs. In this study, the theoretical analysis of impact deformation for cushioning materials by dynamic vibration. The impact deformations of SW and DW corrugated fiberboard pad in acceleration amplitudes of 0.25 G-rms and 0.5 G-rms that were usually generated in transport vehicles during distribution environments were very small compare with the thickness of corrugated fiberboard pad. The maximum of vibration acceleration level of tray cup by vibration impact was about 3.2 G-rms. The theoretical allowable acceleration (G-factor) of the pear was 0.7102 G-rms, and the maximum dynamic deformation estimated within G-factor was about 1 mm.

• 대한수의학회지
• /
• 제44권4호
• /
• pp.593-605
• /
• 2004

An egg has been considered as one of the most important food sources because of it's nutritional superiority and reasonable price. With the complexity of egg flow system from production to consumption in Korea, preventive measures for egg safety have been required. Therefore, our study was carried out to analyze hazards for the egg under farm level and develope preventive measures with a purpose of obtaining egg safety. To analyze biological hazards, microbial contamination of egg(normal, dirty and cracked), water, feed, manure and equipments associated with laying were investigated. One isolate of Salmonella enteritidis and S. bardo were detected from the manure and dirty egg shell respectively. The sanitary conditions in the farm were surveyed by questionaries. Confirmation of vaccination for purchasing chicks and establishment of sanitary guidances for water and type of water suppliers ought to be preceded. Feed supplier systems including feed tanks, feed pipes and hoppers were known that their contamination might give it a chance to infect individuals and egg content and shell. The safe and rapid disposal of dead chickens and rodent were reported as more crucial factors to prevent infectious disease and manage good sanitation. Egg selector and collecting belt should be kept properly not to be contaminated from egg fluids and feces. It should be also considered that regular gathering of eggs, removal of dirty or cracked ones, storage under refrigeration and the use of disposable egg tray were continuously fulfilled. Conclusively, Our results suggested that HACCP-based system for providing fresh and safe eggs to consumers should be applied to the farm.

• 한국식생활문화학회지
• /
• 제11권1호
• /
• pp.107-121
• /
• 1996

This study was carried out to develop the computer-assisted Hazard Analysis and Critical Control Point (HACCP) program for a systematic approach to the identification, assessment and control of hazards for foodservice manager to assure the microbiological quality of food in hospital foodservice operations. Sanitation practices were surveyed and analyzed in the dietetic department of 4 hospitals. Among them, one 762-bed general hospital was selected as standard model to develop computer-assisted HACCP program. All data base files and processing programs were created by using Foxpro package for easy access of HACCP concept. HACCP program was developed based on the methods suggested by NACMCF, IAMFES and Bryan. This program consisted of two parts: the pre-stage for HACCP study and the implementation stage of the HACCP system. 1. Pre-stage for HACCP study includes the selection of menu item, the development of the HACCP recipe, the construction of a product flow diagram, and printing the HACCP recipe and a product flow diagram. A menu item for HACCP study can be selected from the menu item lists classified by cooking methods. HACCP recipe includes ingredients, their amount and cooking procedure. A flow diagram is constructed based on the HACCP recipe. The HACCP recipe and a product flow diagram are printed out. 2. Implementation of HACCP study includes the identification of microbiological hazards, the determination of critical control points, the establishment of control methods of each hazard, and the complementation of data base file. Potentially hazardous ingredients are determined and microbiological hazards are identified in each phase of the product flow. Critical control points (CCPs) are identified by applying CCP decision trees for ingredients and each process stage. After hazards and CCPs are identified, criteria, monitoring system, corrective action plan, record-keeping system and verification methods are established. When the HACCP study is complemented, HACCP study result forms are printed out. HACCP data base file can be either added, corrected or deleted.

• 한국산업보건학회지
• /
• 제31권2호
• /
• pp.147-155
• /
• 2021

Objective: The purpose of this study was to find ways for strengthening occupational health services through monitoring exposure to health hazards. Methods: About 70,000 workplaces that have conducted the work environment measurement(WEM) over the last three years(2017~2019) were classified according to the Korean Standard Industry Classification(KSIC), and the current status of WEM by industry was analyzed. The authors considered ways to monitor exposure to health hazards in order to strengthen occupational health services and protect workers' health. Results: Based on the KSIC, 934 of the 1,196 total sub-classified industries have conducted WEM in at least one workplace over the last three year(2017~2019). In the case of manufacturing, out of a total of 477 sub-classified industries, 474 have conducted WEM at more than one workplace. However, in some industries, WEM was not conducted or the implementation rate was low, so it was necessary to examine whether WEM should be expanded based on a detailed analysis of the WEM database. To this end, it is necessary to form an exposure monitoring committee in which various experts from different fields can participate. The committee needs to discuss the overall matters necessary for selecting industries that require detailed investigation or research, review the results, and prepare a final recommendation. Conclusion: In conclusion, the government needs to come up with a plan to strengthen occupational health services through surveys and research on the current status of WEM and work environment management models by industry.

• 한국식품조리과학회지
• /
• 제27권4호
• /
• pp.55-65
• /
• 2011

This study was performed to analyze the microbiological hazards of ready-to eat sandwiches and to evaluate the effect of implementing a hazard analysis and critical control points (HACCP) for quality improvement of ready-to-eat sandwiches. In total, 174 samples were examined for the microbiological hazard analysis. About 37.4% of the samples had an aerobic plate count ${\geq}$6 log CFU/g, and the numbers of coliforms exceeded 3 log CFU/g in 82.2% of the samples. Additionally, Staphylococcus aureus, E. coli, and Salmonella spp. were detected in 10.3%, 4.6%, 1.1% of sandwiches, respectively. In contrast, E. coli O157:H7, and Listeria monocytogenes were not detected in any of the samples. The results of the microbiological verification after implementing a HACCP throughout the production process indicated that S. aureus, E. coli, Salmonella spp., E. coli O157:H7, and L. monocytogenes were not detected in any of the samples. Consequently, implementing a HACCP is effective for quality improvement of ready-to-eat sandwiches.

• 한국가스학회지
• /
• 제25권4호
• /
• pp.43-48
• /
• 2021

본 연구는 가스사고 전문해석 프로그램인 FLACS를 이용하여 진행하였다. 안전성해석 대상인 수소충전소는 압축설비, 저장탱크, 수소 배관 등으로 구성되어있다. 주요 시설 및 구성품의 설계 사양, 수소충전소 주변의 환경 조건 등을 반영한 후 잠재적 위험요인에 대한 안전성해석을 실시하였다. 국내 수소충전소는 2021년 기준 약 70여곳의 충전소가 보급되어있으며, 향후 2040년에는 1200기 도입이 예정되어있다. 수소충전소의 안전한 보급을 위해 잠재적 위험에 의한 발생 가능한 사고를 대비하고자 누출·확산 시나리오를 도출하여 안전성을 검토하고자 한다.

• Fisheries and Aquatic Sciences
• /
• 제5권1호
• /
• pp.48-53
• /
• 2002

The HACCP (hazard analysis critical control point) concept becomes an important aspect of Good Manufacturing Practices (GMP) in safe food production. The HACCP plan was developed with food safety objective. The authors already carried out hazards analysis on Changran Jeotgal manufacturing process in a previous report. In this study we developed a HACCP plan on the manufacturing process of Changran Jeotgal. We could decide two CCPs those were salt concentration and eliminations of foreign materials before packaging. Foreign materials should be certainly checked out with laser detector just before packaging. Salt should be maintained more than $8\%$ to inhibit pathogenic bacteria in end product. On the Jeotgal process free water is removed after salting and Jeotgal is seasoned with several subsidiary materials such as com syrup. In result end products have $8\%$ salt with water activity 0.82. Most bacteria are inhibited but some can live in this condition. Materials on the working may be contaminate by pathogens, chemicals or physical hazards. It will be decreased by SSOP (standard sanitary operating program). The SSOP needed in Jeotgal plants is nearly same as other general food manufacturing plants but essential to fulfill HACCP program.

• Smart Structures and Systems
• /
• 제6권4호
• /
• pp.405-421
• /
• 2010

This paper proposes a method for early warning of hazard for pipelines. Many pipelines transport dangerous contents so that any damage incurred might lead to catastrophic consequences. However, most of these damages are usually a result of surrounding third-party activities, mainly the constructions. In order to prevent accidents and disasters, detection of potential hazards from third-party activities is indispensable. This paper focuses on recognizing the running of construction machines because they indicate the activity of the constructions. Acoustic information is applied for the recognition and a novel pipeline monitoring approach is proposed. Principal Component Analysis (PCA) is applied. The obtained Eigenvalues are regarded as the special signature and thus used for building feature vectors. One-class Support Vector Machine (SVM) is used for the classifier. The denoising ability of PCA can make it robust to noise interference, while the powerful classifying ability of SVM can provide good recognition results. Some related issues such as standardization are also studied and discussed. On-site experiments are conducted and results prove the effectiveness of the proposed early warning method. Thus the possible hazards can be prevented and the integrity of pipelines can be ensured.

• 항공우주시스템공학회지
• /
• 제6권3호
• /
• pp.7-12
• /
• 2012

The contents of aircraft system safety assessment vary depending on factors such as the complexity of the system, how critical the system is to flight safety, what volume of experience is available on the type of system and the novelty and complexity of the technologies being used. If the system safety assessment is to substantiate that the developed products are 'safe enough' to be taken into use, then the system safety assessment should be planned and managed to provide the necessary assurance that all relevant hazards and failure conditions have been identified and that all significant combinations of hazards and failures which could cause those conditions have been considered. The assessment must assist the designer and management in making decisions. It must make clear what the critical features of each system are and upon which special manufacturing techniques, inspection, testing, crew drills and maintenance practice they are critically dependent. This paper has prepared to study on promoting the efficiency of aircraft system safety assessment and to present how to compile system safety assessment strategy.