• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.694-702
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• 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
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• v.18 no.5
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• pp.428-435
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• 2017

The purpose of this study is to propose a health improvement education program for the majority of elderly people who could not work due to health issues. This study focused on the fact that employment has a positive influence on the health outcomes of the elderly. The paper compares the health outcomes of employed elderly versus that of the unemployed, and suggests directions for future lifelong education programs related to health for the unemployed elders. The study results show more positive health outcomes for employed elders in terms of nutrition status and ability to perform daily tasks. Furthermore, their cognitive ability was more active (orientation, peripheral concentration, awareness of daily life) and their overall quality of life. Therefore, the study aims to develop health outcomes in the unemployed elderly population through safety education, improving health habits, performance improvement education via cognitive activation and socializing, and to secure the professionalism of lifelong education programs for the elderly which is currently only seen as a leisure activity. The object of the proposed program in this study is to maintain health by providing opportunities employment - a core component of successful aging - and relevant social interaction. This will greatly improve the quality of life of the elderly and provide a basis for widening the social role of elderly people in the future.

• Journal of Digital Convergence
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• v.11 no.4
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• pp.221-227
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• 2013

RFID is an automatic identification technology that can control a range of information via IC chips and radio communication. Also known as electronic tags, smart tags or electronic labels, RFID technology enables embedding the overall process from production to sales in an ultra-small IC chip and tracking down such information using radio frequencies. Currently, RFID-based application and development is in progress in such fields as health care, national defense, logistics and security. RFID structure consists of a reader that reads tag information, a tag that provides information and the database that manages data. Yet, the wireless section between the reader and the tag is vulnerable to security issues. To sort out the vulnerability, studies on security protocols have been conducted actively. However, due to difficulties in implementation, most suggestions are concerned with theorem proving, which is prone to vulnerability found by other investigators later on, ending up in many troubles with applicability in practice. To experimentally test the security of the protocol proposed here, the formal verification tool, CasperFDR was used. To sum up, the proposed protocol was found to be secure against diverse attacks. That is, the proposed protocol meets the safety standard against new types of attacks and ensures security when applied to real tags in the future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.10 s.352
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• pp.35-45
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• 2006

Coordinator is defining so that function as most trust center that is point in security in ZigBee Alliance. Because must do height connection with coordinator in device signing to PAN newly, coordinator has shortcoming that subordinate is revealed to danger directly to Centered and cattish device. When do height connection some device, do not become problem, but if network is huge, coordinator's subordinate shall increase as traffic quantity which happen in coordinator increases. Also, in ZigBee security to link network kina of transmission and mutually certification in ZigBee Alliance standard include, but I do not provide method to deliver master key in each node safely. Because process that transmit master key passes through channel that do not secure, master key has shortcoming that is revealed directly. In this paper, I suggested Parent-Child key establishment algorithm to solve these problem. Proposed algorithm consists of two structures. Master key establishment algorithm and device that sign to PAN newly that can use one-way Hash chain and transmit master key safety are consisted of Parent-Child network key establishment algorithm that do child node and parent node key establishment as can do key establishment efficiently. Method that device proposes in case method that propose in case have master key establishment time was shown better performance $200{\sim}1300ms$ than existing method, and device does not have master key than existing method height connect time about $400{\sim}500ms$ better performance see.

• Journal of Environmental Health Sciences
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• v.40 no.2
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• pp.88-97
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• 2014

Objectives: The aim of this study was to evaluate the occurrence of microbiological contamination of kitchen utensils and environments of food service operations at university located in Seoul, Korea. Methods: We collected swab samples from the surfaces of knives, chopping boards, floors, and drains, as well as drinking water and airborne bacteria samples from 20 food service operations. Three bacterial indicators and five food poisoning bacteria were measured quantitatively and qualitatively, respectively. We used selective culture media and the PCR assay targeting 16S rRNA gene for the microbiological analysis. Results: We detected bacterial indicators on knives or chopping boards in eight different food service operations and, three food service operations (I, M, and O) showed more than 3 log colony forming units $(CFU)/100cm^2$ on their knives, significantly higher than the others. The levels of bacterial indicators on the floors and drains in the cooking areas were much higher than those on the cooking utensils. S. aureus was detected on 10 floors and 8 drains. Culturable bacteria were identified in 5 drinking water samples, and food service operation B ($431.1CFU/m^3$) and C ($551.2CFU/m^3$) showed more than $400CFU/m^3$ of total airborne bacteria. Conclusions: These results suggest that some of food service operations in this study may require additional investigation to secure the microbial safety of cooking environments. In addition, further actions including hygiene education for employees and proper guidelines to maintain clean cooking environments should be prepared.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.579-588
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• 2006

In recent years, the availability of high-strength reinforcing and prestressing steels leads us to build economically and efficiently designed concrete structural members. One of critical problems faced to the structural engineers dealing with these types of structural member is controls of crack width that is used as a criterion for the serviceability in the limit state design. Especially, flexural cracking must be controlled to secure the structural safety and to improve the durability as well as serviceability of the load carving members. The proposed method utilizes the results of pure tension test in which tensile loads are applied both side of specimen, done by Ikki. The bond characteristics of deformed reinforcing bar under pure tension is considered by the area of concrete and rib area. The results of proposed method are compared with the test data and the results show that the proposed method can take into account the dimensions, variation of sectional properties, and direction of reinforcing and gives more accurate maximum bond stress and corresponding relative slip than the existing methods. the characteristics of bonding is considered by using dimensionless slip magnitude and effective reinforcement ratio. The validity of the proposed equation is verified by test experimental data.

• Journal of the Korean GEO-environmental Society
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• v.21 no.6
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• pp.13-17
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• 2020

In the era of the fourth industrial revolution, drones are being used in various civil engineering fields. Currently, the construction and maintenance of slopes are generally managed by manpower. This method has a risk of safety accidents, and it is difficult to accurately evaluate the slope because it is difficult to secure the vision. In this paper, the effects of RTK and GCP on the 3D model of the slope were studied by using digital images taken by the drone. GNSS coordinates were measured for nine points to compare the quality of the slope 3D model, three points of which were used as the check points and the remaining points were used as GCPs. When making the 3D model of the slope using high-accuracy geotagging images using RTK, it was found that the error at the check point decreases as the number of GCP increases. Even if GNSS was used, it was found that the error at the check points of the 3D slope model was not significant when the GCPs were applied. However, it was found that even if high-accuracy geotagging images are used using the RTK module, a significant error occur when the 3D slope model is created without applying GCPs. Therefore, it can be stated that GCP must be applied to create the 3D slope model in which information about the height as well as plane information is important.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.251-258
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• 2010

The Republic of Korea is the maritime country of which its infrastructure of the country's development is based on maritime trade. This can be easily understood according to degree of dependence upon foreign trade, which is the economic indicator for expressing one country's economic characteristics. In 2008, the degree of dependence upon foreign trade of Korea is 83.5%, and this figure is much higher than that of Japan and China, which is 28.8% and 68% respectively. This in turn means that the development of Korea, and also the security of Korea depends greatly on safety of the sea. On the other hand, there is a growing trend that threats to the maritime security of Korea increases as examples seen in Somalia pirates. Thus we could say that interest on this issue should increase and also measures to counter those threats should be prepared. Also Korea should take the maritime security as important as critical factors as national security, which is similar to military threats from North Korea. Therefore all citizen's interests on the issue should be raised, and organizations that are capable of mutually integrating the functions related to maritime security should be established. Finally, Korea should actively participate international efforts on maritime security, and secure maritime security of our nation therefore contribute to the nation's prosperity and future development.

• Korean Journal of Construction Engineering and Management
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• v.16 no.1
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• pp.15-23
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• 2015

In the construction industry, risk management has gained constant attention as the factor not only to evaluate global competitiveness of the country but also to secure competitiveness of public institutions and private companies. For effective construction risk management, the specific work process improvement that can be employed in the field in terms of risk management of the entire corporation such as financial, insurance and safety management is necessary. To manage construction risks, what is important is the step to identifying inherent risks in the construction project. The identification of risks will be followed by the step to seeking ways to establish and manage strategies responding to the risks. This study suggests ways and processes to make a checkslit to identify risks through case studies. To that end, the focus will be placed on working process improvement of risk identification among stages to manage construction risks such as risk identification and analyses, planning to respond to risks, risk monitoring and management. The case study checklists show that setting up the system to classify risks by stage is helpful to figure out causes of risks to reduce or eliminate risk factors. The checklist making process that considers features of the project is expected to contribute to successful completion of the project by enabling effective risk identification and systematic risk management.

• Fire Science and Engineering
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• v.34 no.1
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• pp.72-78
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• 2020

In this paper, the risk of damages to humans and properties due to fire explosions in gasoline storage tanks is identified, and the effects of radiant heat on adjacent tanks are evaluated to present the necessary area to secure safety. A simulation was conducted to evaluate the effect of radiant heat (Maximum emission) on adjacent tanks in an oil storage tank fire due to environmental conditions (Wind speed and temperature) in the Northern Gyeonggi Province. The result indicated that the radiant heat released in the fire of an oil storage tank was increased by approximately 1.9 times by the maximum wind speed and the difference occurred in the range of 700~800 kW by the maximum temperature. If a storage tank fire occurs, securing approximately 34.4 m of holding area is necessary. In the future, evaluating the radiant heat emitted by the fire of gasoline storage tanks will be required by applying various environmental conditions, and through this, research on specific and quantitative holding area is required.