복잡한 지하철 역사에서 공기질은 승객의 안전과 건강을 좌우하는 중요한 요소이다. $CO_2$, VOCs먼지, 미생물 등의 농도는 역사의 여러 지점에서뿐만 아니라 원격지점에서도 감시 및 제어가 가능해야 하기 때문에 유무선 네트워크를 사용한 웹기반 감시 및 제어가 필요하다. 가상디바이스 네트워크(VDN) 개념에 근거한 원격 무선센서 네트워크와 디바이스 네트워크(LonWorks)를 IP 네트워크에 연동시키면 매우 강력한 분산 감시 및 제어 성능을 제공한다. 본 연구에서는 지하철역사내 공기질 감시 및 제어를 위한 유무선 네트워크의 성능평가를 실시하였다. 특히 유무선 네트워크의 데이터 전송과 지연특성을 평가하고 승객의 안전과 건강을 위한 핵심요소를 확인하였다.

This paper describes the diagnosis techniques using UV images taken in the field under energized condition of power equipments in order to figure out and analyze the abnormal states on the terminals of power equipments. To classify the features of the terminals, the counted No. of the corona generated at the terminals is defined. According to the result detected, the No. of corona detected on the power equipments installed inside a building is less than that installed outside a building, and it strongly depends on the environment and installed condition. Thus, the environmental condition needs enhanced, and stable operation by the periodic inspection under energized condition of the power equipments is required. Especially, the event counting technique using UV camera is useful for the power equipments apart more than 20 m to apply, and there can be an error due to the features of the sensing techniques when the distance between the user and the objects is close less than 15 m. Therefore, the experimental result shows that event counting technique is employed in the case of the distance more than 15 m. The electrical safety can be ensured by using the UV detection technique and the criteria.

This study proposes to suggest a direction hereafter which is the most suitable operating system of electrical safety management agency for electrical facilities to enhance electrical safety considering our domestic conditions. It was designed to prevent electrical disasters which are increasing due to environmental changes in the electrical industry, and the diversification and complication of the electrical facilities. And the strategy of this research is based on conditions of safety management agency for the electrical facilities, with the analysis on conditions of electrical disasters, and with a questionnaire investigation for owner of electrical facilities, safety management agency. Results of this research are expected to be used to prevent electric fires and shocks effectively by reinforcing the electrical safety management agency of electrical facilities having danger of large-scaled accidents. It is expected to enhance the nation's competing power against foreign countries by reducing the human and physical loss, resulted from the development of reasonable operating system for electrical safety management agency.

The purpose of the study is to assess the extinguishing concentration of inert gases in engine nacelle fire. The experiment was performed with a two dimensional rectangular bluff body stabilized flames, where the fuel was ejected to counter flow and co-flow against an oxidizer stream. Two inert gases, $CO_2$ and $N_2$, were used for extinguishing agent in the oxidizer and methane was used for fuel. The main experimental parameters were the direction of injecting fuel, the kinds of agent and the velocity ratio between air and fuel streams, which controlled the mixing characteristic near bluff body and the strength of recirculation zone in the downstream. The result shows the flame structure and the mode were strongly dependent with fuel/air ratio and the fuel jet direction. For both flow configurations, the extinguishing concentration of $CO_2$ was smaller than the $N_2$ because of the large heat capacity of $CO_2$. However, the concentration of inert gasesat blowout was much smaller than those in the cup burner and coflow jet diffusion flames, which implies that the extinction mechanism of bluff body stabilized flames was mainly due to the aerodynamic aspect. Compared to co-flow fuel injection, the extinguishing concentration of inert gases under counter flow configuration was lower. The effect of direction might result from the mixing characteristic and strength of recirculation zonearound a bluff body. More details should be investigated for the characteristic of recirculation zone in the wake of bluff body using the LES(Large Eddy Simulation).

Wood-plastic composites represents a growing class of materials used by the residential construction industry and furniture industry. In this study, the effect of flame retardants on the flammability and mechanical properties of wood flour-high density polyethylene(HDPE) composites were studied. we were manufactured wood flour-HDPE composites by modular intermeshing co-rotating twin screw extruder with L/D ratio of 42. The flame retardant properties were used limiting oxygen index(LOI) and mechanical properties were measured by universal testing machine(UTM). The Morphological analysis of composites were analyzed by Scanning electron microscope(SEM). It was found that Ammonium polyphosphate can effectively reduce the flammability of the wood flour-HDPE composites. Marginal reduction in the mechanical properties of the composites was found with addition of flame retardants. SEM images showed that the coupling agent improved wood flour-HDPE interfacial bonding.

"low and old age trend" is a big social national problem in korea but also in foreign countries. The Government pursues a policy for aged people to take part in construction site as labours. Low childbirth and avoidance of 3D work kinds lead to exposure of aged workers to industry work places. According to korea department of labour, it is expected that 18% of total economic activity people in 2008 to 27.2% in 2018 be increased with age of more than 55 old years. Therefore, It is needed that more countermeasures for old workers should be taken for safer work conditions. This old workers with more than 55 old years contain major portion of accident occurrence in construction industry. It is found that accident rate in construction industry can be decreased if appropriate technical safety training is provided to them who wish to work at construction sites. Statistic analysis such as frequency, cross, logistic regression using program package SPSS 13.0 has been made after collecting questionnaire survey of more than 330 workers at construction sites.

The seismic safety of long-period cable-stayed bridges is assessed by probabilistic finite element analysis and reliability analysis under NFE. The structural response of critical members of cable-stayed bridges is evaluated using the developed probabilistic analysis algorithm. In this study, the real earthquake recording(Chi-Chi Earthquake; 1997) was selected as the input NFE earthquake for investigating response characteristics. The probabilistic response and reliability index shows the different aspect comparing the result from FFE earthquake. Therefore, the probabilistic seismic safety assessment on NFE earthquakes should be performed for the exact evaluation of long-period cable-stayed bridges and the earthquake resistant design criteria should be complemented.

The objective of this study is to investigate the capacity of epoxy injection method using low pressure mixed with high pressure. Injection depth test and flexural strength test were respectively performed on $40{\times}45{\times}35$ cm and $100{\times}10{\times}40$ cm specimens. Considered as the test variables were injection type(low pressure, low and high pressure), crack width(0.25 mm, 0.50 mm), injection direction(upper, lower, side), and epoxy viscosity(low, medium, high). Test results showed that low viscosity epoxy injection depth of injector using low pressure mixed with high pressure for upper direction were 23 cm and tension strength of crack face repaired by injector using low pressure mixed with high pressure was larger than that of concrete.

Steel plate or FRP materials have been typically used for the seismic retrofit of civil infrastructures. In order to overcome the limitation of each retrofitting material, a composite material, which takes advantages from both metal and fiber polymer materials, has been developed. In the study herein, the composite retrofitting material consists of metal part(steel or aluminum) and FRP sheet part(glass or carbon fiber). The metal part can enhance the ductility and the FRP part the ultimate strength. As a preliminary study to investigate the fundamental mechanical characteristics of the metal-FRP laminated composite material this study performed the flexural fracture test with various experimental variables including the number, the angle and the combination of FRP laminates. From the aluminum-FRP composite tests no great increase in flexural strength and flexural toughness were observed. However, flexural toughness of steel-FRP laminate composite was increased so that its behavior can be considered in the retrofit design. In addition, the angle and the kind of fibers should be carefully considered in conjunction with the expected loading conditions.

Ready-mixed concrete(RMC) has been a major construction materials for infrastructures. However, RMC with poor quality is reported to be social issue since it directly user's safety and convenience. Because the properties of concrete as a construction material are greatly influenced by the variation of water content, to control water accurately is the most efficient method for the quality control in RMC industry. In this study, the automatic measurement technology of fine aggregate was developed by using the microwave moisture measurement. For the various conditions of fine aggregate such as moisture, temperature and pressure, the calibration curve of moisture measurement was obtained by using oven-dry method. From the infield and outfield test, it can be obtained that the accuracy of microwave moisture measurement is very high and the automatic system of microwave moisture measurement is very convenient and useful for quality control in RMC Industry.

For the vibration control of earthquake-excited structures, a pivot-type displacement amplification damper system is proposed and its validity is investigated in this study. A rotational frame amplifies the stroke of the proposed damper system and it can absorb more vibrational energy compared to the conventional dampers of which strokes are not large. In order to prove the effectiveness of the system, time-history analyses are performed with a three story building modelled by a three dimensional frame and numerical results are compared with those for a conventional V-shape braced damper system. In addition, the seismic performances are investigated according to the changes of damper capacity and location.

This paper proposes a robust damper design technique for adjacent structures against model uncertainty. This approach introduces multi-objective optimization based system identification using measurement information which enables reasonable selection of the perturbation range in the robust design. Moreover, in order to improve the numerical efficiency in sampling the structural models required for the robust design of large structures, we define new objective functions which enable us to minimize the number of candidate models suitable to the purpose of the robust design. In addition, the performance index is newly employed to evaluate the robust performance of the sampled structural models, and the robust design has been performed according to the performance index. As a numerical example to demonstrate the efficiency of the proposed method, 5-story and 10-story two adjacent buildings are taken into account, and the existing and newly proposed robust design approaches are compared with each other. The results demonstrate that the proposed approach can guarantee more robust damper system only using small number of samples of the structural models because of using the measurement information which leads to improvement in the numerical efficiency, compared with the existing robust design methods.

The BWIM(Bridge Weigh-In-Motion) is a technology to identify vehicle properties, such as weight, speed, axle spacing and running lane, passing over a bridge by using dynamic response of bridge member. Such information will be used for assessing durability and establishing a maintenance strategy of roadway structures. In this paper, as a first step for developing BWIM system, analytical and experimental studies were conducted in order to verify whether the response of vertical stiffener in steel girder bridge can be used to identify vehicle properties running on the bridge. It was known from this study that such vehicle information could be estimated reasonably by using strain time history curve of a vertical stiffener due to running vehicles. It is because the effect of each axle-load of vehicle appears definitely in the curve. However, as the magnitude of strain of vertical stiffener is effected by running pattern of vehicles, further study is necessary to reduce error when estimating vehicle weight.

The objective of this study is to compare on the occupational injury rate and mortality rate of all workers and foreign workers. By doing so, this study seeks to find out the improvements necessary to secure the basic safety net for foreign workers, as well as to find out the legal and institutional measures in place to make timely political intervention and protect the health of foreign workers. The status of foreign workers in Korea, their employment trends by industries, and occupational accident types and scales of Korean and foreign workers were analyzed from 2005 to 2009. Each year, foreign workers' occupational injury rate was much lower than Korea's overall occupational injury rate. But when analyzed by industry, occupational injury rate (death rate per 10,000 workers) of manufacturing industry was about 2 to 5 times higher than the overall occupational injury rate in Korea. Also, construction industry showed 3 to 16 times higher rate than the rate of overall industries. Although the death rate per 10,000 workers showed a declining yearly trend, foreign workers' occupational injury rate has the tendency to increase gradually. In particular, occupational injury rates and death rates per 10,000 workers were considerably high in the manufacturing and construction industries.

Although reinforcement of work intensity caused by the recent prosperity of shipbuilding businesses and the steady increasing of results which produces orders has difficulties with heavy workload, unique work circumstance in shipbuilding industry where main and subcontractor do the job together is not easy to manage its safety systematically. According to KOSHA(Korea Occupational Safety & Health Agency), there were 2, 587 deaths of 95,806 disaster victims a year on average for late 6 years(2003-2008), therein 36,605 disaster victims and 646 death in manufacture where shipbuilding have 2,287 victims, 6.25% of total disaster victims and 45 deaths, 6.97%. Moreover it shows much higher accident rate in shipbuilding industry in Korea than well developed countries in this industry as Japan, Singapore, Taiwan and so it does about 3 to 10 times higher in case of death. Compared to Japan with a shipbuilding competition of orders received system, 2 times and 2.3 times higher for each and it is more than 2 times higher than accident rate of all domestic industries. These increasing of disaster result in a labor-management dispute and it is necessary that more positive efforts and investments because there occurs blind spot, neglected industry safety and health management by lack of them, Therefore this study, for the effective safety and health management of shipbuilding industry, attempts to analyze risk on kinds of ships and budget needed in safety management through classifying ships that are being made recently by three dominate major companies. For this, we carried out a survey and interview targeting experts related to shipbuilding industry and used AHP(Analytic Hierarchy Process) for result analysis. It is considered that cost of safety and health management will be spent more effectively on the results about risk on kinds of ships and budget needed in safety management in the study and that this study can contribute to decreasing disasters in shipbuilding industry.

Workers who work with his neck bent backward in the standing posture have often complained of their musculoskeletal stress. The objective of this study was to find how much stress there was for workers who worked with their neck bent backward. The subjective evaluation and electromyography(EMG) were used to check the level of the stress. It was found that all subjects felt extreme pain after working with the neck bent backward and alternating 1 minute work and 0.5 minute rest for 30 minutes. The EMG level(amplitude) of neck muscles increased 80 percent on the average and the center frequency of EMG shifted to the lower frequency level which indicated fatigue of neck muscles. Thus, the intervention of this musculoskeletal stress is strongly recommended.

In recent years, there have been a number of concerns and measures surrounding 'Traffic Safety' for children. But, actually, safety measurements of 'School Zone' lack. This research thesis was designed to quantify risk degrees of 'School Zone', in a simple way, with the development of evaluation indicators to evaluate risk degrees of 'School Zone'. This is deems to be used for a guideline necessary for devising improvements or safety measures against 'School Zone' in the future. And, this is expected to be useful for managing and controlling safety each local facility about elementary schools.