• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.3
• /
• pp.52-60
• /
• 2018

In the automobile industry, in order to increase the fuel efficiency and conform to the safety regulations, it is necessary to make the vehicles as light as possible. Therefore, it is crucial to manufacture dual phase steels, complex phases steels, MS steels, TRIP steels, and TWIP from high strength steels with a tensile strength of 700Mpa or more. In order to apply ultra-high tensile strength steel to the body, the welding process is essential. Resistance spot welding, which is advantageous in terms of its cost, is used in more than 80% of cases in body welding. It is generally accepted that ultra-high tensile strength steel has poor weldability, because its alloy element content is increased to improve its strength. In the case of the resistance spot welding of ultra-high tensile steel, it has been reported that the proper welding condition area is reduced and interfacial fracture and partial interfacial fracture occur in the weld zone. Therefore, research into the welding quality judgment that can predict the defect and quality in real time is being actively conducted. In this study, the dynamic resistance of the weld was monitored using the secondary circuit process variables detected during resistance spot welding, and the factors necessary for the determination of the welding quality were extracted from the dynamic resistance pattern. The correlations between the extracted factors and the weld quality were analyzed and a regression analysis was carried out using highly correlated pendulums. Based on this research, a regression model that can be applied to the field was proposed.

• Tunnel and Underground Space
• /
• v.15 no.6 s.59
• /
• pp.452-461
• /
• 2005

In a bidirectional tunnel, the accident rate is 1.5 times as high as that of one directional tunnel , the risk of a fire is increased. On fire, there is a problem that the jet fan should not be operated until completion of refuge. To be special, as the great damages occur owing to the expansion of smoke in long tunnels, there is a need to minimize fatality by constructing cross passage and smoke removal system. This study aims at verifying the efficiency of smoke exhaust system through fire propagation simulation as well as scale model test. The results show that completion of escape through emergency exit requires 335 seconds, while addition of smoke exhaust system reduce the escape time to 185 seconds. Also, near the fire source temperature decreased by about $60^{\circ}C$. Without the exhaust system, fire propagation speed was in the range of 0.36 and 0.82 m/s, and it dropped to $0.27\~0.58\;m/s$ with the exhaust system on. Taking into account the escape speed of tunnel users, usually $0.7\~1.0\;m/s$, the emergency exit built every 150m is sufficient for the safe egress. The ultimate goal of this study is to provide fundamental information for the smoke exhaust system in bidirectional tunnels.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.6
• /
• pp.97-114
• /
• 2022

Unlike ground roads, the on-ramp merging section of underground roads cannot be seen by drivers of main road due to tunnels. In this study, a driving simulator was used for analysis, and virtual driving experiments were carried out to assess the driver's visibility for different design factors. The driver's driving behavior was analyzed by setting scenarios considering the length of chevron markings and the approach speed from the main road. The results of the analysis were used to determine the design factors for ensuring visibility when constructing the virtual driving environment for each scenario. These factors, including speed, lane change points, and driver's gaze ratios, were reviewed for significance using a statistical approach. As a result, in scenarios with a higher approach speed from the main road, it was discovered that there was a difference in driver's behavior between specific scenarios depending on the length of the section with chevron markings. Based on these findings, this study suggests implications and feasible solutions to improve driver safety on the on-ramp merging section of underground roads.

• The Journal of the Korea Contents Association
• /
• v.17 no.12
• /
• pp.461-472
• /
• 2017

The purpose of this study is to analyze the current status and condition of children's playgrounds in K which parents recognize as in Gyeonggi-do and provide basic data for the qualitative environment for daily outdoor play of young Children. To do so, a survey of 269 parents living in Gyeonggi-do was conducted and reconstructed based on the advanced research related to outdoor play. Also it was evaluated and revised after consultation with 3 children education specialists. The repossessed questionaries were frequency-analyzed with SPSS 20.0 program. The result of the analysis on outdoor playgrounds is in the following. First of all, it was analyzed that parents required 1 or 2 hours for their children to play outdoors in a type of "forest playgrounds." Moreover, they said that it was really important for the children to feel "interesting and funny" during the outdoor play, and they recognized that the play would be helpful for the children's socialization. However, they felt that a risk factor of the outdoor play was "a vehicle risk in streets." Secondly, the study suggested that there were outdoor playgrounds around parents' houses, and a type of the outdoor play was "a playground installed in the apartment complex." Furthermore, most of the parents weren't satisfied with the outdoor play because the apartment neglected the management of the playgrounds, and there were no playing facilities that were good enough to derive children's curiosity and adventurous spirit. The result also showed that most of the children played outdoors with "their mothers," and they participated in indoor activities, especially playing a game or watching TV rather than outdoor activities after attending a children educational institute. Lastly, when it comes to areas of outdoor play to be improved, it was necessary to "expand playgrounds that children can use for each season," build "safe playgrounds" for a type of the outdoor play," provide "playing spaces" for a spatial type, and "control vehicles around the playgrounds and deal with dangerous things" to prevent safety accidents. The result can expand the understanding of outdoor play for Young Children and offer discussions about the relevant organizations and studies.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.180-185
• /
• 2003

The increase of traffic over a bridge has been emerged as one of the most severe problems in view of bridge maintenance, since the load effect caused by the vehicle passage over the bridge has brought out a long-term damage to bridge structure, and it is nearly impossible to maintain operational serviceability of bridge to user's satisfactory level without any concern on bridge maintenance at the phase of completion. Moreover, bridge maintenance operation should be performed by regular inspection over the bridge to prevent structural malfunction or unexpected accidents front breaking out by monitoring on cracks or deformations during service. Therefore, technical breakthrough related to this uninterested field of bridge maintenance leading the public to the turning point of recognition is desperately needed. This study has the aim of development on automated inspection system to lower surface of bridge superstructures to replace the conventional system of bridge inspection with the naked eye, where the monitoring staff is directly on board to refractive or other type of maintenance .vehicles, with which it is expected that we can solve the problems essentially where the results of inspection are varied to change with subjective manlier from monitoring staff, increase stabilities in safety during the inspection, and make contribution to construct data base by providing objective and quantitative data and materials through image processing method over data captured by cameras. By this system it is also expected that objective estimation over the right time of maintenance and reinforcement work will lead enormous decrease in maintenance cost.

• Journal of Food Hygiene and Safety
• /
• v.30 no.1
• /
• pp.13-27
• /
• 2015

A systemic review on the factors affecting food catering hygiene was conducted to provide information for risk management of food catering in Korea. In total 47 keywords relating to food catering and food hygiene were searched for published journals in the DBpia for the last decade (2005-2014). As a result, 1,178 published papers were searched and 142 articles were collected by the expert review. To find the major factors affecting food catering and microbial safety, an analysis based on organization and stakeholder were conducted. School catering (64 papers) was a major target rather than industry (5 pagers) or hospitals (3 papers) in the selected articles. The factors affecting school catering were "system/facility/equipment (15 papers)", "hygiene education (12 papers)", "production/delivery company (6 papers)", food materials (4 papers)" and "any combination of the above factors (9 papers)". The major problems are follow. 1) The problems of "system/facility/equipment" were improper space division/separation, lack of mass cooking utensil, lack of hygiene control equipment, difficulty in temperature and humidity control, and lack of cooperation in the HACCP team (dietitian's position), poor hygienic classroom in the case of class dining (students'), hard workload/intensity of labor, poor condition of cook's safety (cook's) and lack of parents' monitoring activity (parents'). 2) The problem of "hygiene education' were related to formal and perfunctory hygiene education, lack of HACCP education, lack of compliance of hygiene practice (cook's), lack of personal hygiene education and little effect of education (students'). 3) The problems of "production/delivery company" were related to hygiene of delivery truck and temperature control, hygiene of employee in the supplying company and control of non-accredited HACCP company. 4) The area of "food materials" cited were distrust of safety regarding to raw materials, fresh cut produces, and pre-treated food materials. 5) In addition, job stability/the salary can affect the occupational satisfaction and job commitment. And job stress can affect the performance and the hygiene practice. It is necessary for the government to allocate budget for facility and equipment, conduct field survey, improve hygiene training program and inspection, prepare certification system, improve working condition of employees, and introducing hygiene and layout consulting by experts. The results from this study can be used to prepare education programs and develop technology for improving food catering hygiene and providing information.

• Journal of agricultural medicine and community health
• /
• v.44 no.3
• /
• pp.124-137
• /
• 2019

Objectives: The purpose of this study was factors affecting self-efficacy of cardiopulmonary resuscitation (CPR) in adults. Therefore, the provide basic data for strategy development to improve the performance rate of bystander CPR. Methods: The data were collected from 164,165 adults of the 2016 Korean Community Health Survey. The survey method was 1:1 interview with households, and the survey period was from August 16, 2016 to October 31, 2016. The survey variables were as follows: self-efficacy of CPR, awareness of CPR, training experience of CPR, demographic characteristics, medical characteristics, health promoting behaviors, and safety practices. Results: The rate of self-efficacy of CPR in adults was 60.6%. Factors affecting self-efficacy of CPR were age, sex, residence, education level, occupation, marital status, any CPR training, CPR training within the last 2 years, CPR training with manikin within the last 2 years, emergency room visit within the last 1 year, physical activity status, drive a bicycle, seat belts on rear seat, seat belts when riding a bus were statistically significant. Conclusions: In conclusion, in order to improve the self-efficacy of CPR in adults, the recent experience rate of CPR education, the practice rate of health promotion behavior, and the practice rate of safety behavior should be improved. The government should expand the provision of education programs to improve the self-efficacy of CPR and actively prepare national-level public advertisements strategies.

• Journal of the Korean Electrochemical Society
• /
• v.4 no.4
• /
• pp.152-159
• /
• 2001

Electric vehicle performance is very dependent on traction batteries. For developing the electric vehicles with high performance and good reliability, the traction batteries have to be managed to get maximum performance under various operating conditions. The enhancement of the battery performance can be accomplished by implementing battery management system (BMS) that plays important roles of optimizing the control mechanism of charge and discharge of the batteries as well as monitoring battery status. In this study the battery management system has been developed for maximizing the use of Ni/MH batteries in electric vehicle. This system provides several tasks: the control of charging and discharging, overcharge and over-discharge protection, the calculation and display of state of charge, safety and thermal management. The BMS was installed in and tested using the DEV5-5 electric vehicle developed by Daewoo Motor Co. and Institute for Advanced Engineering in Korea. The 18 modules of Panasonic Ni/MH battery, 12 V-95 Ah, were used in the DEV5-5. The high accuracy within the range of $3\%$ and the good reliability were shown in the test results. The BMS can also improve the performance and cycle life of Ni/MH battery pack as well as the reliability and safety of the electric vehicles (EV).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.3
• /
• pp.694-702
• /
• 2017

In the case of an elevated railway station, structure borne noise and vibration due to structural limitations allow the load and vibration from railway vehicles to be directly transmitted to the station structure, resulting in an increase in the number of civil complaints from customers and staff of the station. The floating slab track system, which is well known as one of the solutions for reducing the noise and vibration from elevated railway stations, usually contains rubber mounts or rubber pads under the railway slab which act as a damper. These types of device have the disadvantage that is difficult to predetermine the exact stiffness and damping ratio under the nonlinear loads resulting from train services. In this study, an isolator with a friction type of wedge is introduced, which can be applied to floating slab track systems and to be designed with precisely the required stiffness. Furthermore, a comparative analysis of the stiffness between the designed and experimental values is carried out, while the damping ratio, which is closely related to the friction wedge blocks, is deduced according to the train load condition. The performance tests of the isolator were conducted in accordance with the DIN 45673-7 standard which includes both static and dynamic load tests. The load conditions for the performance tests are designed to conform to the DIN standard related to the weight of the train and rail track, in order to perform vertical and horizontal load tests, so as to ensure the secure structural safety of the railway. Also, by checking the change aspect of the friction coefficients of the friction elements according to the loading rate, the vibration reduction performance of the friction type isolator with variable loading rate conditions is examined.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.3
• /
• pp.333-344
• /
• 2017

This research analyzes Seoul station, a typical transfer station complex, focusing on the evaluation of its barrier free design suitable for vulnerable persons such as senior citizens. The analysis was conducted to assess its compliance with the "barrier-free" design standard for those with physical or other disabilities. This paper proposes a list of items to evaluate for transfer station complexes with a barrier-free design. The results showed that the overall connections and internal and sanitation facilities of (Seoul station/the design?)were excellent. However, because of the lack of transfer and guidance facilities, vulnerable persons felt uncomfortable when searching for information about transferring from one means of transport to another. Furthermore, there was an extremely high risk of accidents when they transferred to the bus station. Therefore, it is necessary to arrange the transfer information facilities, in order to improve their readability and visibility. Once this is done, vulnerable people will be able to use this station more safely and conveniently.