• Journal of the Korean Society of Safety
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• v.33 no.6
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• pp.102-114
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• 2018

The Railway Safety Management System is based on risk management and the basic purpose of risk management is safety management activities to prevent railway accidents and operational obstacles in advance. In order to manage risk, an acceptable risk standard must be established. This risk criterion is used to evaluate the railway risk with both frequency and severity. In the case of overseas railway or other industrial sectors, various factors are reflected in the main variables that constitute the occurrence frequency, but this is no the case in the domestic railway sector. In particular, the current risk assessment criteria in the railway sector remain at a level that exploits the incidents that have occurred in the past and the severity of the property damage and it dose not properly reflect complex and diverse environmental and situational changes in railway operations. Therefore, in this study, it is possible to calculate the potential occurrence of future events instead of occurrence frequency as a component of the risk assessment criteria, focusing on the High-Speed Railway. In addition to the property damage to the consequence, we suggest a rational methodology, development direction, and theoretical implications for constructing accurate and reasonable risk criteria including actual damage such as human injury and time loss.

• Physical Therapy Korea
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• v.28 no.1
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• pp.65-71
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• 2021

Background: The hamstring is a muscle that crosses two joints, that is the hip and knee, and its flexibility is an important indicator of physical health in its role in many activities of daily living such as sitting, walking, and running. Limited range of motion (ROM) due to hamstring tightness is strongly related to back pain and malfunction of the hip joint. High-frequency diathermy (HFD) therapy is known to be effective in relaxing the muscle and increasing ROM. Objects: To investigate the effects of HFD on active knee extension ROM and hamstring tone and stiffness in participants with hamstring tightness. Methods: Twenty-four participants with hamstring tightness were recruited, and the operational definition of hamstring tightness in this study was active knee extension ROM of below 160° at 90° hip flexion in the supine position. HFD was applied to the hamstring for 15 minutes using the WINBACK device. All participants were examined before and after the intervention, and the results were analyzed using a paired t-test. The outcome measures included knee extension ROM, the viscoelastic property of the hamstring, and peak torque for passive knee extension. Results: The active knee extension ROM significantly increased from 138.8° ± 9.9° (mean ± standard deviation) to 143.9° ± 10.4° after the intervention (p < 0.05), while viscoelastic property of the hamstring significantly decreased (p < 0.05). Also, the peak torque for knee extension significantly decreased (p < 0.05). Conclusion: Application of HFD for 15 minutes to tight hamstrings immediately improves the active ROM and reduces the tone, stiffness, and elasticity of the muscle. However, further experiments are required to examine the long-term effects of HFD on hamstring tightness including pain reduction, postural improvement around the pelvis and lower extremities, and enhanced functional movement.

• Journal of the Korea Society of Computer and Information
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• v.24 no.12
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• pp.157-166
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• 2019

Globally, various disasters such as typhoons, floods, earthquakes, fires, explosions have caused work to be halted. If there is a large-scale disaster at public institutions in charge of major national affairs and their works are interrupted, not only will there be property damage, but there will also lead to a decline in national credibility and direct and indirect impacts on the people. Therefore, it is necessary to ensure continuity of operation by minimizing the interruption period of critical operations due to disasters. Overseas advanced countries such as the United States and Japan developed guidelines for Continuity of Operation (COOP) to prevent unexpected work disruptions caused by disasters. Recognizing the necessity of COOP in South Korea, a relevant law has been newly established in 「the Framework Act on the Management of Disasters and Safety」 to enable public institutions to establish the COOP in response to this situation. In this study, the definition, the necessity and overseas cases of COOP were investigated and described. Using the templates developed by these results, operational impact analysis, risk assessment, operational continuity strategies and operational continuity procedures were applied to "A" City Hall in Gyeonggi-do province and those results were described. The objective of this study is to substantially contribute to the introduction of COOP to local governments through their pilot application and implications of COOP.

• Clean Technology
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• v.27 no.1
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• pp.17-23
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• 2021

Black polymer spacers are currently used for physically separating aligned camera lenses in camera modules of mobile phones. However, the mechanical properties of polymer spacers have their limits, especially in the current trend of using more lenses in thinner camera modules. Thus, copper (Cu) becomes a good candidate for those polymer spacers because of its superior mechanical properties and its inherent blackness due to its black surfaced oxides, such as copper (II) oxide (cupric oxide, CuO). The latter property is critical in quality control because the closer the color of a spacer is to black, the less light interference and flaring phenomena can occur. A standard Cu blackening process and its operational conditions were proposed in this study through a comprehensive analysis of previous research and patents. The Cu blackening process is composed of cleaning, deoxidizing, activating, blackening and sealing. The effects of operational parameters, such as the temperature of each unit process and the activator concentration, were then investigated by measuring the blackness of the Cu strips with a colorimeter. The proposed operational conditions were determined by whether the blackness of Cu strips was within the on-spec. value used in the field.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.10
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• pp.1377-1384
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• 2003

An analysis has been performed for active thermal control of the KOMPSAT monopropellant rocket engine assembly, i.e., dual thruster module(DTM). The main efforts of this work have been directed at determining proper heater sizes for propellant valves and catalyst beds necessary to maintain their temperatures within specified temperature ranges under KOMPSAT environment and operational conditions. The TAS incorporated with TRASYS thermal radiation analyzer was used to establish a complete heat transfer model which allows to predict the DTM temperature as a function of time. The thermal analysis has been performed in transient mode to verify the appropriate power for catalyst bed heaters necessary to increase catalyst bed temperature to the required value within a specified period of time. Similar analysis has been executed to validate the heater power for the thermostatically controlled primary and redundant heater circuits used to prevent hydrazine freezing, i.e., single fault. Moreover the effect of the radiative property of thermal control coating of heat shield was examined. Thruster firing condition was also simulated for the heat soakback condition. As a consequence, all thermal analysis results for DTM satisfactorily met the thermal requirements for the KOMPSAT DTM under the worst case average voltage, i.e. 25 volt.

• Journal of Environmental Science International
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• v.13 no.5
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• pp.441-448
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• 2004

The purpose of this research was to investigate and analyse the internal structural organisation of UK's urban fringe management initiatives and its roles. Caerphilly Mountain Countryside Service and Thames Chase Community Forest Initiatives were investigated. The Caerphilly Mountain Countryside Service Initiative operates through a tiered structure consisting of the Caerphilly Mountain Joint Committee, the Officers' Working Party, and the management team. The Thames Chase Community Forest Initiative is operated through a tiered structure comprising the Thames Chase Joint Committee and the management team. Although the role of each management initiative is invested differently in certain internal organisational bodies, such as the governance body and the management body, what is common to all the urban fringe management initiatives is that the governance body within each management initiative tries to speak with one voice to bring about an effective operation process, and the management team employs a variety of devices to secure the enrolment of a variety of interest groups in its operational processes.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.589-595
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• 2010

This paper presents a reliability-based shape optimization (RBSO) using the evolutionary structural optimization (ESO). An actual design involves uncertain conditions such as material property, operational load, poisson's ratio and dimensional variation. The deterministic optimization (DO) is obtained without considering of uncertainties related to the uncertainty parameters. However, the RBSO can consider the uncertainty variables because it has the probabilistic constraints. In order to determine whether the probabilistic constraint is satisfied or not, simulation techniques and approximation methods are developed. In this paper, the reliability-based shape design optimization method is proposed by utilization the reliability index approach (RIA), performance measure approach (PMA), single-loop single-vector (SLSV), adaptive-loop (ADL) are adopted to evaluate the probabilistic constraint. In order to apply the ESO method to the RBSO, a sensitivity number is defined as the change of strain energy in the displacement constraint. Numerical examples are presented to compare the DO with the RBSO. The results of design example show that the RBSO model is more reliable than deterministic optimization.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.637-644
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• 2010

This paper presents a reliability-based shape optimization (RBSO) using the growth-strain method. An actual design involves uncertain conditions such as material property, operational load, Poisson's ratio and dimensional variation. The purpose of the RBSO is to consider the variations of probabilistic constraint and performances caused by uncertainties. In this study, the growth-strain method was applied to shape optimization of reliability analysis. Even though many papers for reliability-based shape optimization in mathematical programming method and ESO (Evolutionary Structural Optimization) were published, the paper for the reliability-based shape optimization using the growth-strain method has not been applied yet. Growth-strain method is applied to performance measure approach (PMA), which has probabilistic constraints that are formulated in terms of the reliability index, is adopted to evaluate the probabilistic constraints in the change of average mises stress. Numerical examples are presented to compare the DO with the RBSO. The results of design example show that the RBSO model is more reliable than deterministic optimization. It was verified that the reliability-based shape optimization using growth-strain method are very effective for general structure. The purpose of this study is to improve structure's safety considering probabilistic variable.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.675-687
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• 2017

In the aerospace industry, we have produced various models according to operational conditions and the environment after development of the base model is completed. Therefore, when design change is necessary, there are modification and updating costs of the circuit whenever environment variables change. For these reasons, recently, in various fields, system designs that can flexibly respond to changing environmental conditions using field programmable gate arrays (FPGAs) are attracting attention, and the rapidly changing aerospace industry also uses FPGAs to organize the system environment. In this paper, we design the controller area network (CAN) intellectual property (IP) protocol used instead of the avionics protocol that includes ARINC-429 and MIL-STD-1553, which are not suitable for small unmanned aerial vehicle (UAV) systems at the register transistor logic (RTL) level, which does not depend on the FPGA vender, and we verify the performance. Consequentially, a Spartan 6 FPGA model-based system on chip (SoC) including an embedded system is constructed by using the designed CAN communications IP and Xilinx Microblaze, and the configured SoC only recorded an average 32% logic element usage rate in the Spartan 6 FPGA model.

• Journal of the Korean housing association
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• v.26 no.6
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• pp.169-180
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• 2015

This study was carried out to offer direction to the Housing Management Support Center in terms of its key features and specific operational tasks. The research involved the property management office (n=35) and Resident Representatives of the apartment blocks (n=52). Advisory Services conducted a consumer survey, as well as a survey of expert interviews (n=15). Survey results were as follows: (1) the Managing Director and secretary residents were satisfied with the Diagnosis and Advisory services; (2) the administrative support services need to address housing issues, including a long-term repair plan and advice on using long-term repair reserves and "conflict resolution associated with public housing management"; and (3) there was a greater need for a "basic, common-sense Housing Management Information Base to provide services to the Resident Representatives of the apartment blocks". Based on the survey results, the main roles of the Housing Management Support Center are to act as a House of Commons Administrator to handle complaints with counseling, diagnosis and advice; to support the Resident Committees; to provide professional training, research, and investigation; to support community revitalization; to manage the business of guidance and inspection; to coordinate conflicts and disputes; to build a comprehensive source of information; and to build networks.