When the fluid energy convert into kinetic energy due to water hammer, the propagation velocity of pressure wave appear. The propagation velocity of pressure wave(1050 m/s) of very fast could be damage to the pipeline system. If the occurrence of water hammer is due to down-pressure, the faster the air exhaust or supply device is needed. it is high Speed Air Valve. In this paper, Each 3.12, 3.13, 3.72, $3.74kg/cm^2$ pipeline pressure were setting, and then executed pressure rapid drop for obtaining a high Speed Air Valve Operating time and pressure change data. the result was that pipe line pressure stabilization time were each 0.98, 1, 1.22, 1.25 sec. In other words, that pressure drop experimental results pipe line pressure was equal to atmospheric pressure without negative pressure After about one second. The study result would be useful to pipe line system stability design because this data could be foresee pressure stabilization time.

This study aimed to develop members with the optimum impact characteristics to ensure a protected space for passengers in the case of automobile collisions. Accordingly, these members were fabricated to provide sufficient rigidity and safety to the passenger room structure and to absorb large amounts of energy during collision. In particular, CFRP members were fabricated with different section shapes such as square and single- and double-hat shapes. Next, their impact collapse characteristics and collapse modes were quantitatively analyzed according to the changes in section shapes and stacking angles. This analysis was performed to obtain design data that can be applied in the development of optimum lightweight members for automobiles.

The aim of this work is conduct the study on light weight and structural performance improvement of the composite wind power blade. GFRP (Glass Fiber Reinforced Plastic) pre-empted by CFRP(Carbon Fiber Reinforced Plastic), the major material of wind power blade, was identified the superiority of mechanical performance through the tensile and fatigue test. SENT(Single Edge Notched Tension) specimen fracture test was conducted on the specimen that laminated together 2 ply CFRP with 4 ply GFRP through DIC(Digital Image Correlation) analysis. The SENT specimen thickness and $a_0/W$ ratio is 1.45 mm and 0.2, respectively. The fracture test accomplished with displacement control with 0.1 mm/min at the room temperature. The experimental apparatus used for the fracture test consisted of a 50kN universal dynamic tester and CCD camera connected to a personal computer (PC), which was used to record images of the specimen surface. Following data acquisition, the images and load-displacements were transferred to the PC, on which the DIC software was implement. The experiment and DIC analysis results show that CFRP/GFRP laminated composite exhibits improvement of the strength, compared with that of the existing blade material. This study shows the result that the strength of CFRP rotor blade of wind turbine satisfies through the experimental and DIC method.

This study is compare to model-based analysis and experimental data of the response characteristic of interior impulse noise. Interior impulse noise and the pressure response characteristics of the building structure on its analysis are presented the impulse pressure acting on the rear wall 90 N-sec. The force acting on the wall $CFD^{{+}{+}}$ which are compared measurement and simulation analysis. Results of simulation and measurement data were shown. In this study, a high dimension of the degree of virtual space in the numerical space of the lesser degree in order to calculate folding method was applied. The results of this study contribute safety evaluation and model development for the interior impulse noise that affects the basic data for the interior impulse noise model validate for the physical quantity prediction.

The live line working is inherently dangerous as the workers have to work under the risk of electrical shock and most of works are carried out at height. The live line working need the some specific techniques and higher level safety measures such as a risk assessment to carry out works safely, but the electrical construction companies performed live-line working are usually small-sized companies. They have less capacity to have own safety management system. This study intended to conduct an in-depth analysis on the cause of electric shock accidents to provide basic data for policy proposing taking into considering the past eleven years for a long-term plan. And the aim of this study is to propose the policy about the equipment performance standards and/or worker's safety standards to revise the standards for preventing electric shock accidents, moreover, co-relation of the electrical work order form and on safety workings, especially electrical construction company/work.

This paper is purposed to analyze the thermal characteristics of wiring according to the number of electric fans in operation for 10 fans over 10 year old and 10 fans less than 1 year old in livestock barn. In order to achieve the goal in the paper, it selected VCTFK, VFF, HIV, and CV wiring that were used most at 64 livestock barns in Cheongwon location through the research on the field investigation. Finally, it also analyzed the dangers by deducing the thermal characteristic data of 4 wiring. In addition, this paper suggested the mode of load current (the most frequently measured load current) of both over 10 years old and less than 1 year old electric fans. The data of this paper could be used for the maintenance and management of wiring and fire investigation of livestock barn as well as for materials of safe designs of wiring of electric fans.

This paper deal with due to the additional equipment established on the vehicle fire accident cases. Recently, vehicle was recognized as other living spaces and it was increasing installation of additional devices such as a black box, multivision, additional battery and so on. However, these additional devices were established on the vehicle by non-specialists such as the general public user or manufacturing and distributors of additional devices since the vehicle factory. Resulting from the additional equipments due to installation errors in these additional equipments connected to the electrical wiring insulation damage or electrical breakdown occurs, and finally leading to a fire caused by the additional equipments. Therefore, additional equipment established on the vehicle due to a fire in order to prevent accidents during the manufacturing process of these devices are installed. If not installed unless the manufacturing process, the installation of additional equipments established by professional who knows the vehicle structure that will be able to prevent the fire.

Despite the automatic fire alarm system, according to the national fire data system of national emergency management agency, the fires account for 40,932 incidents, 2,184 injuries and about 430 billion won in property losses in 2013. Since the conventional automatic fire alarm system has several weaknesses related to electrical signal such as noise, surge, lighting, etc. Most fires are mainly caused by electrical faults, mechanical problem, chemical, carelessness and natural. The electrical faults such as line to ground fault, line to line fault, electrical leakage and arc are one of the major problems in fire. This paper describes the development of a novel real-time fire monitoring system algorithm including fault detection function which puts the existing optic smoke and heat detectors for fire detection with current and voltage sensors in order to utility fault monitoring using high accuracy DAQ measurement system with LabVIEW program. The fire detection and electrical fault monitoring with a proposed a new detection algorithm are implemented under several test. The fire detection and monitoring system operates according to the proposed algorithm well.

The record type receivers that are operated in large industrial sites have strength in preventing fire. However, because of its long circuit lines and multiple detectors, the receivers are vulnerable to lightning, noise, and breakdown of equipments, resulting in malfunction. In case of malfunctioning of detection circuits of main protection areas, such as electrical room and server room, potential release of gaseous extinguisher agents may lead to property and life damage. In this paper, we present the results on the characteristics of the transponder that initiates the solenoid valves, with respect to various electromagnetic and lightning inflow conditions. Based on the measured data, we analyzed the systematic problems of the transponder. In order to prevent receiver malfunctions, a sequential circuit was configured with two additional transponders and a timer. The circuit was tested with a simulator with preference and delay circuit algorithms.

Depending on the progress of the industrial advances, the use of the thermal oil system in the utility system has been increased, which became an important part in the operation of the plant. However, fire or explosion have occurred due to lack of risk awareness and safety management, more frequently than we know. In this study, by using a questionnaire, actual conditions of safety management in thermal oil system is surveyed and analyzed, it is composed of general, a safety status of the thermal oil system component and the stage of recognition and management in the thermal oil system. These results of this study can be used as basic data to the safety management and the accident prevention of fire or explosion in the workplace.

Construction equipment such as tower crane should be installed in a field without appropriate anchorage to cause a collapse of crane. The anchorage capacity can be varied with Anchor length, concrete strength, anchor diameter, hooked or non hooked these variables will be made and tested in the study. It is shown what anchorage capacity will be more effective case by case. Hooked and non-hooked rebar anchor concrete weight with dia 22mm rebar are shown with initial displacement at 170~220KN of hooked case and 200~210KN of non-hooked one which are linearly increased, without any ductility behavior with almost brittleness. Three(3) same test pieces are almost similarly behaviored without relation to hooked or non-hooked cases. It is found out that the bigger diameter of rebar becomes, the more resistant capacity could be made, but conversely ductility against sudden collapse similar to brittleness becomes the more insufficient. It is also found out that dia 16mm rebar could be more effectively applied to heavy support weight at construction sites.

This study proposes an advanced type of a micropile system. The proposed micropile system consists of perfobond ribs installed steel rod to improve shear capacity between the thread and the grout, and partially expanded drill holes to increase resistance capacity between the grout and the ground. This study contains experimental evaluations on the proposed micropile system to verify the shear capacity of perfobond rib installed on the steel rod and the load-carrying capacity of shear key created by the partially expanded drill hole. Push-out tests were conducted on a rolled screw thread and steel rods which perfobond ribs are installed instead of rolled screw, in order to compare their load-carrying capacity and behavioral characteristics. As a result, it was confirmed that the perfobond-rib steel rods show much superior structural behavior in terms of initial stiffness, ultimate load, and ductile behavior.

The procedures of safety diagnosis assessment have been applied by synthetical consideration of structural safety, functionality, and economic efficiency in determining reconstruction or remodeling, but they have limitations in some special cases such as the non-association apartment. In this regard, this study was conducted to establish more desirable criteria and procedures in determining reconstruction or new construction and suggests a way to improve policy and laws of reconstruction correctly by reviewing the safety diagnosis in reconstruction process. Besides, the safety diagnosis of reconstruction for non-association apartments in government-owned public district was carried out preemptively to remove reckless procedures. As a result, the reconstruction of non-association apartments should be effectively without interference in the administrative procedures. This requires that the policy and laws of reconstruction safety diagnosis should be revised in priority in order that similar projects in future can be effectively executed.

Each year, it seems inevitable that major accidents will occur on construction sites. Industrial accidents, sometimes involving foreign laborers, have been constantly increasing. Construction laborers have higher hazard rates and higher work intensity than other industries, which means that they experience more job stress, as a result of the subcontracting structure. Therefore, this study performed an influence factor analysis on job stress and its relevance to industrial accidents involving Korean and foreign construction laborers, and proposed its effectiveness with the job stress and construction accident management measures based on the results of those. A questionnaire to measure job stress was performed targeting Korean and foreign laborers, and the results were analyzed. The results of this study can be utilized as important reference materials in efforts to reduce the job stress of foreign laborers on construction sites, and can be expected to contribute to preventing construction accidents related to job stress in the future.

To ensure durability and light weight of bridges, high-strength concrete is required for long-span deck slabs. Such a technology eventually extends the life of bridges and improves the economic efficiency. The results of this study suggests a formula for calculating the minimum thickness of long-span deck slabs built with high strength concrete. The minimum thickness is proposed based on the limit states indicated in the CEB-FIP Model Code and the Korean Highway Bridge Design Code(limit state design). The design compressive strength of concrete used for the study is 80MPa. Moreover, the required thickness for satisfying the flexural capacity and limiting deflection is estimated considering the limit state load combination. The formula for minimum thickness of deck slabs is proposed considering the ultimate limit state(ULS) and the serviceability limit state(SLS) of bridges, and by comparing the Korean Highway Bridge Design Code and similar previous studies. According to the research finding, the minimum thickness of long-span deck slab is more influenced by deflection limit than flexural capacity.

More than 76% of occupational accidents occur in small and medium sized enterprises(SME) employing less than 50 workers, due to the lack of safety and health systems, and carelessness of workers and owners. Timely Technical Guidance(TTG) project of Korea Occupational Safety & Heath Agency(KOSHA) for SME was initiated to analyze and inform accident causes just after accidents occur. Improvement direction of TTG project is suggested through situation and performance analysis on TTG services conducted in 2012. KOSHA provided TTS services on 15,571 SMEs(suffering at least one accident in 2012), through which the working day losses from recurrence resulted in 19.0%p, 14.5%p and 31.3%p decreases in manufacturing, services and construction businesses, respectively.

The construction accidents which had been on the downward trend for the past decades have increased for five consecutive years since 2008. In order to let the increasing trend of construction accident slow growing or switching to decline, various efforts are required of all members in construction industry such as government, employers, construction engineers, safety managers, construction workers, etc. Although the criteria for appointment of safety managers in construction site introduced in 1982 have contributed to prevent construction accident as a forefront for the past 30 years, it has not been a remarkable improvement in the safety manager's status and roles which have been required to change according to the changes of circumstances and environments. In associated with a newly introduced the criteria for appointment of health managers in construction site in the year 2015, the problems such as role, status, number of safety and health managers are needed to be considered comprehensively and improved widely. In this study, we propose several improvement plans which will improve the current criteria for appointment of safety and health managers in construction sites.

Assessment of setting process of concrete is important as it provides useful information to schedule concreting work in construction site. Electrical impedance measurement method, which utilizes the change of electrical resistance of concrete, has been applied to assess setting process of cement-based materials. However, the applicability of the method has been demonstrated only for cement paste and mortar. The main purpose of this research is to develop the electrical impedance based setting process assessment for concrete. To this end, electrical impedance response model for concrete should be developed in advance since it is essential to estimate the electrical resistance of concrete from measured impedance response. The electrical resistance of concrete is a key parameter for the setting process assessment. In this study electrical impedance responses of the concrete in setting process are measured and analyzed. Thereby, an electrical impedance response model of the liquid state concrete is developed and schematically validated.

This study investigated a posttraumatic stress, social support, and work burden and identified related factors which exerted influence on posttraumatic stress of new firefighters. Data were gathered from total of 144 new firefighters. Also, 22 PTS items, 20 work burden items, and 8 social support items were analyzed by SPSSWIN 21.0 program. Posttraumatic stress according to general characteristics showed significant difference in gender(t=-2.57, p=0.01), experience of self danger(t=3.06, p=0.00), experience of rescuee danger(t=2.41, p=0.02), and experience of colleague danger(t=3.43, p=0.00). High risk group of PTS was 20.1%. Posttraumatic stress, social support, and work burden showed significant difference in the high and low risk group. Posttraumatic stress was correlated with work burden(r=0.34, p=0.00), social support(r=-0.29,p=0.00). Factors influencing PTS were Experience of colleague danger(${\beta}$=1.274, 95% CI=0.08-0.96), social support(${\beta}$=-0.090, 95% CI=0.85-0.98) and work burden(${\beta}$=0.057, 95% CI=1.02-1.10). We need to reduce the work burden caused by influencing variable of traumatic stress and create more preventive discipline of traumatic stress for the new firefighters to improve the social support at work or home. Also, posttraumatic stress has to be managed consistently with support by changing the social attitudes and we need to seek the new system that anybody can get a consultation of a specialist.

In recent studies, construction industry workers with higher job stress and lower work ability were more likely to experience accidents at their workplace. Likewise, fatal accidents rate was higher among simple labor workers compared to technical workers. Therefore the evaluation of a worker's job stress and work ability seems to be important in preventing the occurrence of fatal accidents. To search for ways to reduce job stress and to improve work ability, the current study conducted a job stress analysis based on age, years of service, skill level, hobbies, sleep patterns, and monthly income. For this, the Korean occupational stress questionnaire short form and the Work Ability Index (WAI) developed by the Finnish Institute of Occupational Health (FIOH) were used. In this study, SPSS 12.0K statistics program was used for statistical analysis and significance was verified by the Kruskal-Wallis test and non-parametric tests. The results of this study can be summarized as follows : (1) Simple labor workers had higher job stress and less work ability than technical workers. (2) The more experienced workers had lower job stress and higher work ability. (3) In the case of workers who slept a lot, work ability was higher and job stress was less. (4) Monthly income influenced on the job stress and work ability. (5) Job stress and work ability in accordance with the age difference was not significant.

This article has compared the level of activities of occupational safety and health in workplace among sub-sectors of manufacturing industry in order to set the priority for policy intervention. Data of manufacturing industry in the survey on the current status of occupational safety and health was used with factor analysis and radar graphic method. Authors have categorized sub-sectors of manufacturing industry into four categories, attained group, active group, neglected group, and passive group based on injury rate, level of safety and health activities. The neglected group may be the first target group for occupational safety and health policy guiding some detailed occupational safety and health activities. Limitation of this study is that cross sectional data was analyzed. The long term effect could not be analyzed.

This study looks at the impact of psychological and physical factors of the working conditions on the health of workers depending on whether technology is used by such workers. The data used for the study is the third work environment survey. Out of 50,032 respondents, a total of 29,711 paid workers were used as analysis subjects. Although it was anticipated that the use of technology was a factor that hindered job autonomy and teamwork autonomy. However, the analysis results showed low levels of job autonomy and teamwork autonomy in the group that did not use technology. The study assumes a regression analysis model about work environment and work organizational practices of workspaces that have an impact on musculoskeletal complaints, stress symptoms and level of work satisfaction by controlling the social demographic variable that represents the level of individual sensitivity. As a result of the study, ergonomic risk had a significant effect on both groups that did or did not use technology with respect to stress symptoms, musculoskeletal complaints and level of work satisfaction. In particular, as workspace practices and work environment had an effect on the development of musculoskeletal complaints in the group that used machines, there is a need to improve such situation. The autonomous team work or level of job autonomy within the group that used technology may act as a risk factor to the health and welfare of workers. However, because it may also act as a buffer factor, there is a need for a change to reduce stress symptoms and increase the level of work satisfaction by improving autonomous team work and the level of job autonomy.

This study deals with the pedestrian accidents of intersections in case of Cheongju. The objective is to develop the pedestrian accident models using Tobit regression model. In pursuing the above, the pedestrian accident data from 2007 to 2011 were collected from TAAS data set of Road Traffic Authority. To analyze the accident, Poisson, negative binomial and Tobit regression models were utilized in this study. The dependent variable were the number of accident by intersection. Independent variables are traffic volume, intersection geometric structure and the transportation facility. The main results were as follows. First, Tobit model was judged to be more appropriate model than other models. Also, these models were analyzed to be statistically significant. Second, such the main variables related to accidents as traffic volume, pedestrian volume, number of traffic island, crossing length and the pedestrian countdown signal systems were adopted in the above model.

The realistic cases causing severe core damage should be analyzed and arranged systematically for preparing an accident management of the specific nuclear power plant. The objective of this paper is to establish basic technical information for reactor safety and reactor building integrity management strategies in CANDU reactor severe accident. For the development of severe accident management strategies, plant specific features and behaviors must be studied by detailed analysis works. This analysis scope will serve to cover overall methods and analyzing results to understand the reactor building integrity status in the most likely severe accident sequences that could occur at CANDU reactor. Also analysis results could help prevent or mitigate severe accidents for the identification of any plant specific vulnerabilities to severe accidents using the probabilistic safety assessment (PSA) quantified results.

This study is conducted to compare three methods of hazard analyses and to propose the control for the accidents arising under construction of heat accumulator of group energy projects(co-generation plants). The analysis of fatal accidents and the Analytic Hierarchical Process(AHP) using by the questionnaire survey for the workers engaged in the construction of heat accumulator and the quantitative questionnaire survey of expert group has been carried out. In order to analyze the fatal accidents, the 115 cases of accidents from 2001 to 2012 published by Korean Occupational Safety and Health Agency(KOSHA) and workers suffered from industrial accidents are collected and analyzed. The AHP is applied and analyzed for 66 persons of the construction site managers, safety engineers and construction engineers and the questionnaire survey of expert group is carried out and analyzed for the 51 persons of contractors and construction inspectors. The analyses of the types of accidents and the jobs of the suffered workers and the hazardous construction processes which are occurred accidents frequently are shown. The results of the analysis of fatal accidents and the AHP as well as the questionnaire of expert group are shown similar results.