• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.4
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• pp.771-781
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• 2017

The helmet is an imperative personal protective equipment. This protective device must be able to guard the human head against potential risks. Helmets are classified according into the purpose of use; therefore, the required performance and specifications depend on the type of products. Military helmets are intended to protect the wearer's head from bullets and shrapnel. Generally, lightweight super fibers and fiber reinforced composite materials are used as helmet shell materials, and NIJ STD of U.S. Department of Justice is most widely used as international standard related to bulletproof helmets. Safety helmets are widely used for industrial application and sports leisure. In general, the performance of shock absorption must be ensured, and various lining systems are applied in material, design, and combination methods. Evaluation standards have also been classified and strictly controlled for each purpose; therefore, it is difficult to certify with the existing standards such as the recently developed convergence helmets. However, it is possible to launch the product through a separate national integrated certification procedure.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.25-30
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• 2017

Carbon-fiber-reinforced plastic (CFRP) composite materials have been widely used in various industrial fields because the design variables can be adjusted according to the application of the required structure. Thermosetting and thermoplastic resins are used as the base materials of CFRP composites for the lightweight construction of automotive components. Thermoplastics have several advantages such as no curing and recyclability compared to thermosetting resin. In this study, CFRP composites were made using the Long-Fiber Thermoplastic-Direct (LFT-D) process. The LFT-D process includes an in-line production system that directly impregnates a thermoplastic resin, extrudes the composite material, and molds it. This process increases the strength and decreases the molding time. The tensile strength characteristics on the mechanical properties of CFRP were analyzed according to the parameters of LFT-D based on thermoplastics. To analyze the properties of CFRP, the specimens were prepared based on the tensile test standard ASTM 3039 of composite materials.

• Corrosion Science and Technology
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• v.23 no.4
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• pp.310-314
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• 2024

The corrosion behavior of high chromium white cast iron was studied in 0.5 mol dm^-3 H₂SO₄ + 0.01 mol dm^-3 HCl solution over time through electrochemical and immersion experiments. Potentiodynamic and potentiostatic polarizations revealed active-passivation transition behavior, with critical current densities observed at -0.27 V_SSE and 0.00 V_SSE, repectively. The former potential showed preferential dissolution of primary γ phases, while the latter one showed preferential dissolution of eutectic γ phases. Immersion tests showed an exponential increase in corrosion rate, with significant acceleration observed around 1000 seconds due to the onset of eutectic γ phase dissolution. Over a 24-hour immersion period, both γ phases exhibited extensive corrosion, leaving carbides largely intact. These findings elucidate distinct corrosion behaviors of high chromium white cast iron in acidic environments, providing critical insights into material performance evaluation. Understanding these mechanisms is essential for predicting the longevity and durability of materials in corrosive conditions, thereby informing better material design and application strategies.

• Journal of Korea Multimedia Society
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• v.21 no.5
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• pp.599-608
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• 2018

As natural disasters are increasing due to the unusual weather and the modern society is getting complicated, the rapid change of the urban environment has increased human disasters. Thus, citizens are becoming more anxious about social safety. The importance of preparation for safety has been suggested by providing the disaster safety services such as regional safety index, life safety map, and disaster safety portal application. In this paper, we propose an application framework to predict the urban safety index based on user's location with realtime weather/atmosphere data after creating a predication model based on the machine learning using number of occurrence cases and weather/atmosphere history data. Also, we implement an application to provide traffic safety index with executing preprocessing occurrence cases of traffic and weather/atmosphere data. The existing regional safety index, which is displayed on the Si-gun-gu area, has been mainly utilized to establish safety plans for districts vulnerable to national policies on safety. The proposed system has an advantage to service useful information to citizens by providing urban safety index based on location of interests and current position with realtime related data.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.11
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• pp.21-26
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• 2005

We propose a fully converged Ethernet and TDM transport system. Developed Ethernet and TDM convergence system can support not only L2 VPN service and premium multimedia service based on MPLS protocol but also TDM leased line service, simultaneously. Developed convergence system can provide high reliability for Ethernet packet due to support protection and restoration function of circuit based networks. Evaluation for Ethernet and TDM path was successfully performed to show the typical application of the proposed system in the legacy networks.

• Journal of Digital Convergence
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• v.13 no.3
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• pp.201-208
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• 2015

Recently computer, smart phone, medical devices, etc has become used in a variety of environments as the application fields of IT products have become diversification. Attack case of abuse of software security vulnerabilities is on the increase as the application fields of software have become diversification. Accordingly, secure coding program is of a varied but history management, updating, API module to be vulnerable to attack. Thus, this paper proposed a materialization of CMS linked system to enable check the vulnerability of the source code to content unit for secure software development, configuration management system that interwork on the transmission module. Implemented an efficient coding system secure way that departmentalized by the function of the program and by analyzing and applying secure coding standards.

• Journal of Internet Computing and Services
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• v.23 no.5
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• pp.17-23
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• 2022

Network slicing is a promising paradigm and significant evolution for adjusting the heterogeneous services based on different requirements by placing dynamic virtual network functions (VNF) forwarding graph (VNFFG) and orchestrating service function chaining (SFC) based on criticalities of Quality of Service (QoS) classes. In system architecture, software-defined networks (SDN), network functions virtualization (NFV), and edge computing are used to provide resourceful data view, configurable virtual resources, and control interfaces for developing the modified deep reinforcement learning agent (MDRL-A). In this paper, task requests, tolerable delays, and required resources are differentiated for input state observations to identify the non-critical/critical classes, since each user equipment can execute different QoS application services. We design intelligent slicing for handing the cross-domain resource with MDRL-A in solving network problems and eliminating resource usage. The agent interacts with controllers and orchestrators to manage the flow rule installation and physical resource allocation in NFV infrastructure (NFVI) with the proposed formulation of completion time and criticality criteria. Simulation is conducted in SDN/NFV environment and capturing the QoS performances between conventional and MDRL-A approaches.

• Journal of Digital Convergence
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• v.7 no.3
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• pp.49-60
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• 2009

The aim of this study was to develop a model for teaching-teaming by applying Ubiquitous at a learning experience field, in which connect characteristics of both ubiquitous application learning and experience teaming, making use of them. A literature survey of concepts was conducted, with the main areas to find out relationships between ubiquitous application learning and experience learning. Experience learning by applying ubiquitous learning methods maximizes its efficiency of experience learning in considering ubiquitous learning methods's characteristics of dynamic, interaction, sharing. Also it makes communications through positive participation and active interaction, and leads to a process of internal examination. The research data suggests that critical factors of experiencing learning applying ubiquitous are acquiring information and memory, information integration and exquisiteness, emotional and social activity, producing activity, help activity.

• Journal of Internet Computing and Services
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• v.19 no.1
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• pp.19-26
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• 2018

Social issues for environmental pollution are continuously increasing globally. Especially, Users require services to measure environmental factors in indoor and outdoor and manage related data effectively and conveniently. According to this demand, sensors that can measure environmental factors in indoor and outdoor have been developed. However, since one sensor is composed of independent module, the interface of output data from each sensor is different. To solve the problem, we propose a customized protocol for low-power short-range wireless communication between smartphone using Bluetooth and All-in-One sensor device board and analyze the performance of the proposed customized protocol by developing program for performance verification of interface with user smartphone through Bluetooth. In addition, we implement a smartphone application using proposed protocol.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.64-68
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• 2011

On the limited urban area, precise measurement of meteorological data is not easy for the cost problem. The facilities collecting the data require high installment costs. The mobile sources can be a solution in city region. For example, a public bus on which some meteorological sensors are installed can act as moving information gathering station. The information is gathered on a server and aggregated to generate useful information for smart phone application. To implement the services, several obstacles are exists. This paper studies on a design of this mobile meteorological information service system for urban area.