• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.3
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• pp.86-97
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• 2021

As mechatronic systems have various, complex functions and require high performance, automatic fault detection is necessary for secure operation in manufacturing processes. For conducting automatic and real-time fault detection in modern mechatronic systems, multiple sensor signals are collected by internet of things technologies. Since traditional statistical control charts or machine learning approaches show significant results with unified and solid density models under normal operating states but they have limitations with scattered signal models under normal states, many pattern extraction and matching approaches have been paid attention. Signal discretization-based pattern extraction methods are one of popular signal analyses, which reduce the size of the given datasets as much as possible as well as highlight significant and inherent signal behaviors. Since general pattern extraction methods are usually conducted with a fixed size of time segmentation, they can easily cut off significant behaviors, and consequently the performance of the extracted fault patterns will be reduced. In this regard, adjustable time segmentation is proposed to extract much meaningful fault patterns in multiple sensor signals. By considering inflection points of signals, we determine the optimal cut-points of time segments in each sensor signal. In addition, to clarify the inflection points, we apply Savitzky-golay filter to the original datasets. To validate and verify the performance of the proposed segmentation, the dataset collected from an aircraft engine (provided by NASA prognostics center) is used to fault pattern extraction. As a result, the proposed adjustable time segmentation shows better performance in fault pattern extraction.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.3
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• pp.142-156
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• 2019

[Purpose] It aims to suggest the differential factors to enhance the customer satisfaction and to activate the shopping in the convenience store (CVS). [Methodology] Convenience store service convenience (CVS SERVCON) was developed at the first time and the gap of relative importance level between the owners and the consumers was assessed by AHP analysis method..[Findings] First, the importance of access convenience was assessed as the first priority in both CVS owners' group and the consumers' group, while the detailed elements showed the differences which required the improvements. Based on the consumers' assessment, the importance of location was relatively low. They assessed relatively high on 24 hours operation of CVS and personal services. Second with respect to the transaction convenience, CVS owners' group rated it as the fourth priority while the consumers' group rated as the second, which requires the improvement. Third in terms of benefit utility and value-added service of post-benefit convenience which are the sub-factors of benefit convenience, the rate on the importance from the consumers showed higher than that from the owners, which requires the improvement. [Implications] Based on this study results, CVS operating companies are anticipated to be able to satisfy the customers, moreover, to secure the loyal customers if they concentrate the resources to develop the differentiation strategy on the areas where the consumers' demands are high while performs the maintenance strategy on the areas where their demands are low. In addition, this study contributed the theoretical expansion of SERVCON upon development of CVS SERVCON to comply with its definition.

• Journal of Advanced Navigation Technology
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• v.26 no.3
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• pp.179-184
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• 2022

The accurate wing flexure model is required to improve the transfer alignment performance of guided weapon system mounted on a wing of fighter aircraft or armed helicopter. In order to solve this problem, mechanical or stochastical modeling methods have been studying, but modeling accuracy is too low to be applied to weapon systems. The deep learning techniques that have been studying recently are suitable for nonlinear. However, operating fighter aircraft for deep-learning modeling to secure a large amount of data is practically difficult. In this paper, it was used to generate amount of flexure data samples that are similar to the actual flexure data. And it was confirmed that generated data is similar to the actual data by utilizing "measures of similarity" which measures how much alike the two data objects are.

• Korean Journal of Construction Engineering and Management
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• v.23 no.6
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• pp.119-124
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• 2022

Recently a method of constructing architectural products using additive manufacturing technology has been proposed. The additive manufacturing technology automates the construction process and it can secure the safety of workers. In addition, due to the high implementation efficiency of atypical shapes, the applicability to the manufacturing process of buildings and infrastructure is drawing attention. Additive manufacturing technology has the ability of satisfying computer-based construction automation, resource management and construction period prediction which is required in the modern construction industry. However, the industrial application is still limited by insufficient data, standards, regulations, and operating methods. In this study, in order to analyze the applicability of architectural additive manufacturing technology, we manufacture each architectural product with two additive manufacturing systems. In addition, we apply an application of each building product into an appropriate manufacturing system through the AM production decision model. And identify problems in the manufacturing process through empirical experiments. As a result, we propose an extended additive production decision model to improve the quality of building products.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.121-126
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• 2023

As service utilization for IT technologies such as artificial intelligence, big data, and IOT has recently increased, cloud computing has been introduced to efficiently manage vast amounts of data and IT infrastructure resources that process them to provide stable and reliable information services while streamlining infrastructure costs. Efforts for this are ongoing. This thesis compares and analyzes the operation results before and after cloud adoption in terms of system failures for 426 systems at 360 branches nationwide in cloud systems of companies operating a total of 1,750 cloud systems. As a result of the analysis, the number of failures and failure types , service downtime, etc., the introduction of the cloud yielded significant results in securing service continuity. Through this result, it is expected to provide meaningful implications to companies expecting to secure service continuity by adopting the cloud.

• Journal of Korean Society of Rural Planning
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• v.29 no.4
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• pp.27-34
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• 2023

Recently, worldwide to respond to climate change and secure sustainability. Korea aimed to increase water use efficiency by implementing integrated management according to the water management unification policy. Therefore, the necessity of establishing and operating governance is expanding to ensure the sustainability of agricultural water. In this study aims to evaluate the importance of agricultural water governance components and provide essential data for the participation of stakeholders in the efficient use of agricultural water in Korea. For this study, a total of 19 respondents to the ANP survey for this study were composed of experts in agricultural water and governance in Korea. As a result, the ranking for the main components was in the order of law, policy, and systems(0.222), core subjects(0.191), information sharing and communication(0.180), budget support(0.178), mutual learning(0.124), and external experts(0.105). The most important components for the operation of agricultural water governance are laws, policies, and systems. Since Korea's agricultural water management is a public management system, national standards are considered the first priority. This study, which is the purpose of the agricultural water governance model, evaluated the importance of the constituent components for participating in demand management with a sense of responsibility. Moreover, if agricultural water governance is expanded nationwide by reflecting agricultural and water resource policies in the future, it is believed that positive effects can be achieved in increasing utilization efficiency and securing sustainability through agricultural water saving.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.2
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• pp.222-229
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• 2024

As the operating condition for the penetrating missile has been more advanced, the survivability of main charge has been strongly required when the warhead impacts the target. Lots of efforts to desensitize explosives such as the development of insensitive molecular explosives or optimizing plastic-bonded explosives(PBX) systems has been made to enhance the survivability of main charge. However, these efforts face their limits as the weapon system require higher performance. Herein, we suggest a new strategy to secure the survivability of main charge. We applied structurally supportable aluminum honeycomb(HC) structure to cast PBX. The aluminum HC structure reinforces the mechanical strength of cast PBX and helps it to withstand external pressure without the reaction like detonation. In this study, impact resistance character, shock sensitivity and internal blast performance of PBXs reinforced with HC structure were investigated according to the application of aluminum HC structure. The newly suggested aluminum HC structure applied to cast PBX was proved to be a promising manufacturing method available for high-tech weapon systems.

• Journal of Korea Entertainment Industry Association
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• v.14 no.5
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• pp.131-146
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• 2020

This research is based on social flow that is in need of sports welfare that diagnoses the delivery system of sports program pass that is typical business of national sports welfare services and operation structure, and analyze the supplier, operator, beneficiary and all that is related to business from multilateral aspects, therefore seek for operation systems for provision systems of sports welfare services. To clearly grasp the operating mechanisms of service provision system that is happening in real field, there were in-depth interview done by the 18 people of suppliers, operators, and beneficiaries that are the main participants of business, and through which drew an ideal agreed point for sports welfare services to get in the right direction. The result of this study is as following: First, based on the limited government budget for the compilation of budget for the business of sports welfare services it is found that there is need of constructing a pragmatic service provision system that can bring maximum of efficiency. Second, voucher that was introduced for market logic application and greater transparency of the business of sports welfare services has a complex structure that it is in need of simplification of structure which that is well fit with its characteristics. Third, for convenience enlargement in administration and management, make management policy of provision system be reflected and therefore enlarge the independence of management and secure the power of negotiation regarding fee savings through centralized budget management.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.397-404
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• 2020

The military tactical vehicle currently being operated is manufactured by improving the parts of commercial vehicles. In addition, the power supply system is applied by installing a separate converter inside the communication room to secure the operating environment of communication equipment. On the other hand, due to electromagnetic radiation noise, there are problems in frequent noise and deterioration in communication sensitivity during wireless communication in vehicles. To improve these, an advanced power supply system is applied, which is also equipped with an alternator to receive power required for communication equipment reducing broadband electromagnetic radiation noise. An additionally installed alternator, which is located in the engine room, is separated from the communication room where communication equipment is operated and is expected to reduce the effect of electromagnetic radiation noise generated from the power supply system. To verify these, a broadband radiation test was performed on a previous and advanced one. As a result, the broadband radiation noise of vehicles with an applied advanced power supply system satisfied all of the domestic vehicle safety standards and reduced in most of the sections except for some frequencies compared to previous typed vehicles. In particular, broadband radiation noise was decreased by up to 10.751 dB𝜇V/m in the vertical sections in 170 to 200 MHz on the right side of the vehicle.

• Journal of Software Assessment and Valuation
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• v.15 no.2
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• pp.111-119
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• 2019

The existing smart grid device authentication system is concentrated on DCU, meter reading FEP and MDMS, and the authentication system for smart meters is not established. Although some cryptographic chips have been developed at present, it is difficult to complete the PKI authentication scheme because it is at the low level of simple encryption. Unlike existing power grids, smart grids are based on open two-way communication, increasing the risk of accidents as information security vulnerabilities increase. However, PKI is difficult to apply to smart meters, and there is a possibility of accidents such as system shutdown by sending manipulated packets and sending false information to the operating system. Issuing an existing PKI certificate to smart meters with high hardware constraints makes authentication and certificate renewal difficult, so an ultra-lightweight password authentication protocol that can operate even on the poor performance of smart meters (such as non-IP networks, processors, memory, and storage space) was designed and implemented. As a result of the experiment, lightweight cryptographic authentication protocol was able to be executed quickly in the Cortex-M3 environment, and it is expected that it will help to prepare a more secure authentication system in the smart grid industry.