• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.638-644
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• 2020

This study examines cracks that occur under the load of an aircraft. The life of aircraft vulnerability structures was analyzed and structural fitting improvements were made. Structural integrity and safety have been achieved through preemptive life expectancy and life management of aircraft structures. The crack size inspection capability of the aircraft under analysis is 0.03inch, compared with 0.032inch, which is the lowest of the three vulnerable parts. In addition, the fatigue life analysis results in approximately 1450 operating hours, the lowest of the three vulnerable parts relative to the aircraft's required life of more than 15000 operating hours, which increased the repeat count of the aircraft's initial and re-inspection times, and hence raised the resulting costs and manpower consumption. Finally, the features were improved through structural fitting of the identified three weak parts. The lowest critical crack size was secured at 0.13 through increased structural resistance to generated cracks and increased aircraft safety. The lowest structural fatigue life for cracks occurring during aircraft operation is 25000 operating hours, which are analyzed above the required structural life, resulting in more optimized improvements than the repair costs and excessive fitting range caused by cracks and fractures.

• Journal of Korea Water Resources Association
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• v.43 no.7
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• pp.609-623
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• 2010

In this paper the feedback loop mechanisms that are inherent in the management of water supply systems were identified based on the system dynamics modeling methodology. As a result, a system dynamics (SD) computer simulation model that can be used to aid efficient management of water supply systems was developed. The developed SD model can be used to predict operating conditions of water supply systems including the effects of pipe maintenance on the entire system. The developed model is consisted of water supply, pipe maintenance and water supply business finance model. The operation and maintenance data from a study water supply system were used to verify the model and to predict the past and future operating conditions of the system. The policy leverage that greatly affects the operating condition was evaluated by the sensitivity analyses for the operational indices due to changes in the exogenous variables. It was found that while the pipe maintenance related exogenous variables had great effects on the leakage and conditions of pipes, they did not have great effects on the major operational indices such as revenue water ratio. It is considered that the social costs due to leaks and pipe breaks and the corresponding mechanism of propagation of the costs must be modeled to better evaluate the effects of pipe maintenance on the operational conditions of water supply systems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.452-458
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• 2019

The purpose of this study is to analyze how managers' reporting choices affect asymmetric cost behaviors in manufacturing firms in Korea and Japan. In order to analyze the contents, SG&A, COGS, and operating expenses (OE), which were the targets of the previous studies, were analyzed using the operating costs paid in cash (OC) and the operating expenses before depreciation (OEBD) proposed by Shust and Weiss (2014). The differentiation of cost behavior was analyzed. The analysis revealed, first, that both Korea and Japan showed the difference between cost behavior of OE and OC. Specifically, the cost stickiness of OC was higher than that of OE. In particular, it showed that Korea firms have a higher intensity of tangible fixed assets that are weakening the cost stickiness compared to Japanese firms. Second, the occurrence of depreciation costs weakens the cost stickiness in both countries. Lastly, the higher the debt ratio, the more aggressively the cost reduction of Japanese companies. We hope that this study will help to improve the relationship between the two countries at the academic level when the Korea-Japan relationship cools down.

• The Journal of Fisheries Business Administration
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• v.55 no.3
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• pp.1-13
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• 2024

The purpose of this study is to examine the determinants of management performance in the remaining offshore fishing industry after the resource management-oriented fisheries structure improvement policy by the fisheries vessel buy-back program and Total Allowable Catch (TAC). The results of the analysis of the determinants of management performance of offshore fishing can be summarized as follows. First, based on the management performance determinant model of offshore fishing, it is confirmed that the government's resource-managed fishing structure improvement policy, such as the fishing boat reduction project and the TAC policy, is improving the management performance of the resource-managed remaining fishing boat. Second, looking at the specific management performance determinants based on the management performance model of offshore fishing, the leverage ratio (TLTA), which is the total debt ratio, shows a statistically significant positive (+) relationship with management performance, which increases management performance directly proportional to the leverage ratio. The increase in the leverage ratio (total debt ratio) was expected to lead to a high interest cost burden, resulting in a reverse (-) financial leverage effect; however, rather a positive (+) financial leverage effect occurred with a high profit covering interest costs. The total catch (TCATCH) has a positive (+) relationship with management performance at a statistical significance level of less than 1%, indicating that an increase in catch is improving or increasing the management performance of fishing companies. The selling price (UPRICE) shows a positive (+) relationship with management performance at a very high statistical significance level of less than 1%, and it can be seen that high fishing prices are a major factor in improving or increasing the management performance of offshore fishing. On the other hand, fishing vessel tonnage (TON), fishing vessel horsepower (RHP), and operating days (WDAYS), which indicate have a statistically significant negative (-) relationship with management performance, which deviates from the existing fisheries common sense that the size of fishing vessel tonnage and fishing vessel horsepower and the increase in the number of operating days is proportional to management performance. As a result of the increase in fishing vessel tonnage, horsepower, and the number of operating days, it was confirmed that the higher the fishing cost, such as oil costs, is worsening the management performance of fishing companies. Participation in TAC has a statistically significant positive (+) value with management performance, indicating that the remaining offshore fishing companies participating in TAC are improving or increasing management performance compared to offshore fishing companies that do not. Third, there are conflicting results depending on the industry as a result of estimating the management performance determinants of offshore fishing by TAC participation, and TAC participation had a negative impact on management performance in anchovy boat seine and southern west sea bottom trawl in fishing industry while TAC participation had a positive impact on management performance in large stow nets on anchor in fishing industry.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.517-544
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• 2011

Promote competition in local government and the construction of a subway construction in the vicious cycle of debt due to the operating deficit as a greater burden on local finances was leave. This government policy of public transport in the center of the metro construction costs affordable and to respond appropriately to public transport demand new transit LRT(Light rail Transit) by introducing the current Busan was the opening of Line 4, yongin line, Busan - Gimhae line, parliamentary and barge construction or ready for the opening. What is light rail, compared to the existing subway and cheaper construction cost, the existing road or bridge that runs along the track is installed, etc. Manless system construction cost and operating expenses as a possible new railway transportation has been a leading state-of-the-art mad. However, the domestic business system engineering of light rail-related companies in the developed countries are doing to advance to the national to the local engineering skills of the self-free, hurry will have to be secured. Therefore, this paper applies local light rail project on the status of the systems engineering analysis and based on this source of the latest engineering technology-intensive systems engineering to provide direction to the development of technology.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.6
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• pp.23-33
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• 1996

The exploitation of locality of reference in shared memory NUMA multiprocessors is one of the improtant problems in parallel processing today. In this paper, we propose a revised hardeare reference counter to help operating system to manage locality. In contrast to the previous one, the value of counter can abe adjusted dynamically and periodically to adapt the page replication policy to the various memory reference patterns of processors. We use execution-driven simulation of real applications to evaluate the effectiveness of our adjustable DELAY counter. Our main conclusijon is that by using the adjustable DELAY counter the t normalized average memory access costs and the variance of them become smaller for most applications than the previous one and more robust memory management policies can be provided for the operating systems.

• ETRI Journal
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• v.39 no.3
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• pp.353-363
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• 2017

Recently, sink mobility has been shown to be highly beneficial in improving network lifetime in wireless sensor networks (WSNs). Numerous studies have exploited mobile sinks (MSs) to collect sensed data in order to improve energy efficiency and reduce WSN operational costs. However, there have been few studies on the effectiveness of MS operation on WSN closed operating cycles. Therefore, it is important to investigate how data is collected and how to plan the trajectory of the MS in order to gather data in time, reduce energy consumption, and improve WSN network lifetime. In this study, we combine two methods, the cluster-head election algorithm and the MS trajectory optimization algorithm, to propose the optimal MS movement strategy. This study aims to provide a closed operating cycle for WSNs, by which the energy consumption and running time of a WSN is minimized during the cluster election and data gathering periods. Furthermore, our flexible MS movement scenarios achieve both a long network lifetime and an optimal MS schedule. The simulation results demonstrate that our proposed algorithm achieves better performance than other well-known algorithms.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.177-182
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• 2009

The purpose of this study is to investigate planning of urban energy supply systems configuration and operating conditions for the district heating and cooling system using combined heat and power system. Generally the district heating and cooling system has been known to one of the effective way for energy saving, cost reduction and demand side management of energy. Economical analyses were carried out and operating characteristics for some systems were examined in terms of GER factor which represents to the ratio of gas and electricity costs. Rates of the energy consumption and the $CO_2$ emission were compared from the system configuration of the energy supply system with new district cooling system with the conventional one.

• Journal of Sensor Science and Technology
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• v.29 no.1
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• pp.40-44
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• 2020

An integrated multifunctional sensor, capable of raising an early electric-fire warning, was fabricated. An arc-light, temperature, and humidity sensor was fabricated on a flexible substrate using a printed thin film of indium tin oxide. A polyethylene terephthalate (PET) substrate was used as the flexible substrate. The sensor was fabricated on a PET substrate, and its operating characteristics were tested. The operating performances of the sensor when serving as an arc-light, a temperature, and a humidity sensor were estimated to be 0.6247 Ω/W, 80.6 Ω/K, and -4.08 Ω/RH, respectively. The feasibility of the proposed fire sensor was demonstrated; it costs low and offers multiple functionalities.

• KIISE Transactions on Computing Practices
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• v.23 no.1
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• pp.80-84
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• 2017

Existing operating systems experience scalability issues as the number of cores increases. The network I/O performance on manycore systems is faced with the major limiting factors of cache consistency costs and locking overheads. Legacy methods resolve this issue include the new microkernel-like operating system or modification of existing kernels; however, these solutions are not fully application transparent. In this study, we proposed a library that improves the network performance by separating system call context from user context and by applying the core affinity without any kernel and application modifications. Experiment results showed that our implementation can improve the network throughput of Apache by up to 30%.