• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.28-30
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• 2022

Recently, the number of confirmed cases has increased again with the new variant of COVID-19. Quarantine is recommended, especially to prevent the rapidly increasing spread, as environmental controls, such as minimizing contact with others, can increase safety. In addition, there are often cases in which the patient's condition cannot be confirmed from the standpoint of a guardian, such as visitation being prohibited under certain conditions. At this time, the sensor data values of oxygen, carbon dioxide concentrations, temperature and humidity, and alcohol, which are medical gases used in hospitals, are collected remotely using ZigBee wireless communication technology. Design a system that can be stored and monitored in a database. We propose an environmental monitoring system, which is a visualization system designed to allow hospitals to check and feedback data on the managed environment, and to give reliability to parents.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.117-124
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• 2024

The objective of Value Engineering (VE) is to derive the optimal value at the most efficient life cycle cost, comprising three stages: Pre-Study, Study, and Post-Study. In this study, we propose a method for information collection and analysis during planned site visit surveys in the preparation stage of VE. The 3D spatial model, created using a drone, facilitated observation and analysis of the study area from various angles, both from the center and the outside. Additionally, through the utilization of drones, we conducted on-site investigations of the research area's 3D spatial model, enabling a macroscopic perspective previously only feasible through a microscopic viewpoint during planned site visits in the pre-study phase. Furthermore, the utilization of actual spatial data obtained from observations allowed for real-time information verification during Design VE workshops, enhancing the efficiency and reliability of the VE project.

• Steel and Composite Structures
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• v.52 no.3
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• pp.377-390
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• 2024

Analyzing thermoelastic, elastoplastic, and residual stresses is pivotal for deepening our insights into material characteristics, particularly in the engineering of advanced materials like functionally graded materials (FGM). This research delves into these stress types within a thick-walled sphere composed of Al-SiC FGM, employing a detailed successive approximation method (SAM) to pinpoint stress distributions under varied loading scenarios. Our investigation centers on how the sphere's structure responds to different magnitudes of internal pressure. We discover that under various states-thermoelastic, elastoplastic, and residual-the radial stresses are adversely impacted, manifesting negative values due to the compressive nature induced by internal pressures. Notably, the occurrence of reverse yielding, observed at pressures above 410 MPa, merits attention due to its significant implications on the sphere's structural integrity and operational efficacy. Employing the SAM allows us to methodically explore the nuanced shifts in material properties across the sphere's thickness. This study not only highlights the critical behaviors of Al-SiC FGM spheres under stress but also emphasizes the need to consider reverse yielding phenomena to maintain safety and reliability in their application. We advocate for ongoing refinement of analytical techniques to further our understanding of stress behaviors in various FGM configurations, which could drive the optimized design and practical application of these innovative materials in diverse engineering fields.

• The Journal of the Acoustical Society of Korea
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• v.42 no.5
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• pp.469-490
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• 2023

Survey was carried out on the acoustic outputs from 12 shock wave fields produced by the 10 extracorporeal shock wave lithotriptors whose technical documents are available, among the 33 devices approved by the Ministry of Food & Drug Safety (MFDS).The results show that the acoustic outputs (P+, P-, efd, and E), critical to the therapeutic efficacy and the patient safety, are largely different between the devices. The maximum values of P+, P-, efd, and E vary up to 2.08, 3.72, 3.89, and 15.98 times, respectively. The acoustic output parameters are not thoroughly provided in the technical documents, and some of data (eg. efd) are suspected to be abnormal outside usual ranges. The large device to device differences in the shock wave outputs are likely to undermine equivalence between the ESWL devices approved for the same indication. To verify the reliability of the data in the technical documents of the approved devices and to confirm if the acoustic outputs from the devices in clinical use are the same as those in their technical documents, an authorized test laboratory should be available. A postapproval monitoring led by the regulatory agency is suggested to maintain the acoustic outputs from the ESWL devices that suffer from degrading in performance due to aging.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.704-711
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• 2023

This paper discusses the control method of BLDC(Brushless Direct Current) motor that has similar electrical characteristics with DC motor but has improved its lifespan and reliability. The BLDC motor can improve durability and speed stability by using rotor position information to eliminate commutators that require mechanical contact with DC motors. In this study, a controller for a DC motor was designed based on the fact that the current in the windings of a BLDC motor is a square-wave current like the current flowing in the armature of a DC motor. Next, the designed controller was applied to a 3-phase BLDC motor to confirm the effectiveness of the controller. In detail, a single-phase DC motor with electrical parameter values of a three-phase BLDC motor was modeled and a PI controller for motor speed control was designed by applying the root locus method to the derived system. The speed control simulation of the DC motor was performed to confirm the validity of the controller, and the same controller was applied to the speed control of the 3-phase BLDC motor implemented in MATLAB. From the simulation, similar results of the DC motor were obtained in the 3 phase BLDC motor and confirmed the usefulness of the proposed control scheme.

• Journal of the Korean Institute of Gas
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• v.15 no.6
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• pp.28-33
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• 2011

The purpose of this paper analyzes and studies to improve the failure cases on the computer that one of electronic control elements for engine in liquified petroleum gas vehicle. The first case, it certified the non-starting phenomenon of engine that it's electronic control unit didn't control the fuel for idle speed actuator because of no given action signal in slow-cut solenoid valve. The second case, it knew the bad condition phenomenon of engine and back-fire by the wire melting of ignition coil and firing of transistor being inside ECU. The third case, it certified the action stoping phenomenon of engine and malfunctioning signal for engine ECU because of leakage of current and an excess current by moisture inflowing inside ECU curcuit plate. Therefore, it is thought that will elevate the durability and reliability of engine computer throughout procure of quality.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.1
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• pp.171-182
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• 2014

Common Criteria is a scheme that minimize IT products's vulnerabilities in accordance with the evaluation assurance level. SSDLC(Secure Software Development Lifecycle) is a methodology that reduce the weakness that can be used to generate vulnerabilities of software development life cycle. However, Common Criteria does not consider certificated IT products's vulnerabilities after certificated it. So, it can make a problem the safety and reliability of IT products. In addition, the developer and the evaluator have the burden of duplicating evaluations of IT products that introduce into the government business due to satisfy both Common Criteria and SSDLC. Thus, we researched the relationship among the Common Criteria, the static code analysis tools, and the SSDLC. And then, we proposed how to combine SSDLC into Common Criteria.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.5
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• pp.81-88
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• 2012

Turbopump is a key component in liquid rocket engines, and reducing weight while maintaining structural safety is one of the major concerns of turbopump designers. To reduce the weight aluminium alloy castings instead of steel casings are introduced. The casting process is especially useful for enhancement of productivity and for reduction of product costs. But, since castings are used in space vehicle engines, reliability cannot be compromised. Therefore, proper design, production process and thorough investigation should be performed to ensure structural integrity. In this study inlet casings for a fuel pump were casted with A356.0-T6 alloy and using one of them a burst test was conducted to ensure structural integrity. Structural analysis is performed for simulation, and with multiple strain gages strains are measured and compared with predictions.

• Journal of Korean Society of Transportation
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• v.26 no.2
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• pp.177-186
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• 2008

Video Image Detection System can be used for various traffic managements including traffic operation and traffic safety. Video Image Detection Technique can be divide by Tripwire System and Tracking System. Autoscope, which is widely used in the market, utilizes the Tripwire System. In this study, we developed an individual vehicle tracking system that can collect microscopic traffic information and also developed another image detection technology under the Tripwire System. To prove the accuracy and reliability of the newly developed systems, we compared the traffic data of the systems with those generated by Autoscope. The results showed that 0.35% of errors compared with the real traffic counts and 1.78% of errors with Autoscope. Performance comparisons on speed from the two systems showed the maximum errors of 1.77% with Autoscope, which confirms the usefulness of the newly developed systems.

• Journal of Korean Society of Transportation
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• v.29 no.6
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• pp.75-83
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• 2011

This research explores the relative importance of factors and service items that influence the air cargo service quality for provision services by the Skyteam Cargo in the Korean market. In general, the Skyteam Cargo provides a package of services which are different functions and operations of service such item as Equation Heavy (heavy and large express freight), Equation (small express freight), Variation (special freight), and Dimension (general freight). To carry out the research, the expert questionnaire survey, the Analytic Hierarchy Process (AHP) analysis had adopted to evaluate the level of quality for the provision air cargo operation services by the Skyteam Cargo at Incheon International Airport. Based on an expert survey and the AHP, five core service factors, namely, infrastructure as installed facilities, reliability, promptness, efficiency, and safety are defined.