• Structural Engineering and Mechanics
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• v.37 no.6
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• pp.593-615
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• 2011

This study determines the water length effects on the modal behavior of a prototype arch dam using Operational and Analytical Modal Analyses. Achievement of this purpose involves construction of a prototype arch dam-reservoir-foundation model under laboratory conditions. In the model, reservoir length was taken to be as much as three times the dam height. To determine the experimental dynamic characteristics of the arch dam using Operational Modal Analysis, ambient vibration tests were implemented for empty reservoir and three different reservoir water lengths. In the ambient vibration tests, the dam was vibrated by natural excitations provided from small impact effects and the response signals were measured using sensitive accelerometers. Operational Modal Analysis software process signals collected from the ambient vibration tests, and Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification techniques estimated modal parameters of the dams. To validate the experimental results, 3D finite element model of the prototype arch dam was modeled by ANSYS software for empty reservoir and three different reservoir water lengths, and dynamic characteristics of each model were determined analytically. At the end of the study, experimentally and analytically identified dynamic characteristics compared to each other. Also, changes on the natural frequencies along to water length are plotted as graphs. Results suggest that reservoir water complicates the modal behavior of the arch dam significantly.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.3
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• pp.430-440
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• 2022

Shipping companies are key components of the logistics industry, which is extremely significant in enhancing the country's comprehensive national power and promoting global trade development. In the context of the implementation of the new development pattern strategy in China and the impact of the global novel coronavirus (COVID-19), this paper takes 22 Chinese shipping listed companies as the research object and analyses the operational efficiency of them from 2011 to 2020 based on the Super-SBM DEA Model and Window DEA Model. Factors affecting the efficiency are further analyzed with the Tobit model. The research conclude that the operational efficiency of Chinese shipping companies as a whole shows a steady increase from 2011 to 2020. Although most of them are in a relatively ef ective operation state, fewer are absolutely effective companies. Besides efficiency among companies differs obviously, which indicates the potential of further improvement and promotion. What's more, factors such as current economic development level, enterprise size, human resources quality and enterprise turnover speed have significant positive correlation to the operation efficiency of Chinese shipping listed companies, which is significant to improve the operation efficiency of Chinese shipping companies.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.3
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• pp.23-40
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• 2014

This paper measures the operational efficiency of domestic online game companies and analyze its trends and patterns by using data envelopment analysis (DEA). DEA is a non-parametric approach to measuring the relative efficiency of decision-making units (DMUs) with multiple inputs and outputs. 14 online game companies are selected as DMUs and three inputs (number of employees, capital and asset) and three outputs (sales, operating profit and net profit) are selected as DEA variables. First, the output-oriented BCC model and super-efficiency model are employed to measure the static operational efficiency of the online game companies from 2003 to 2012. We also conduct the dynamic analysis with DEA window model to capture the trends of their operational efficiency influenced by internal and external environmental changes. The results are expected to provide fruitful implications for strategic decision making of online game companies and policy making for the online game industry.

• Earthquakes and Structures
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• v.19 no.1
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• pp.45-57
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• 2020

This paper presents the experimental application of a new method for seismic vulnerability assessment of buildings recently introduced in literature, the SMAV (Seismic Model Ambient Vibration) methodology with reference to their operational limit state. The importance of this kind of evaluation arises from the civil protection necessity that some buildings, considered strategic for seismic emergency management, should retain their functionality also after a destructive earthquake. They do not suffer such damage as to compromise the operation within a framework of assessment of the overall capacity of the urban system. To this end, for the characterization of their operational vulnerability, a Structural Operational Index (IOPS) has been considered. In particular, the dynamic environmental vibrations of the two considered strategic buildings, the fire station and the town hall building of a small town in the South of Italy, have been monitored by positioning accelerometers in well-defined points. These measurements were processed through modern Operational Modal Analysis techniques (OMA) in order to identify natural frequencies and modal shapes. Once these parameters have been determined, the structural operational efficiency index of the buildings has been determined evaluating the seismic vulnerability of the strategic structures analyzed. his study aimed to develop a model to accurately predict the acceleration of structural systems during an earthquake.

• Journal of Korea Trade
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• v.27 no.3
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• pp.65-86
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• 2023

Purpose - As globalization progresses, complexity also increases, and various factors that threaten port functions are emerging. Accordingly, the demand for port security to prevent the crisis and resilience that quickly recovers its original function after the crisis is also increasing in port operations. However, few studies have examined how to ensure the port security and how the resilience affects operation performance of port and sustainability performance as well. So the study aims to find out how port security affects port resilience and port operational performance, and consequently, this two factors affect socioeconomic and environmental sustainability performance respectively and synthetically. Design/methodology - Confirmatory Factor Analysis (CFA) was first performed to determine the validity of the factors of model and hypothesis test was performed using Structural Equation Model (SEM) to analyze the Port Performance Model, which show the perception logic among port security level, port resilience, operation performance, and sustainability performance. In order to empirically analyze this model, total 264 respondents from port security operators, shipping companies in South Korea were surveyed. Findings - As result of SEM, First, port security level positively affected the resilience (H1) and cargo operational performance (H2) but not in both of the sustainability performances (H3, H4). Second, resilience positively affected only cargo operational performance (H5) and socio-economic sustainability performance (H7). Last, cargo operation performance positively affects the both of sustainability performances (H8, H9). Originality/value - It was confirmed that port security could improve cargo operational performance through ensuring port resilience and eventually increase the socio-economic sustainability. Therefore the study implies that careful integration and management of port security, port resilience, and sustainability are required, along with compromise on sustainable development goals in the social, economic, and environmental area among all stakeholders.

• Journal of the military operations research society of Korea
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• v.35 no.3
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• pp.17-30
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• 2009

In this study, we propose the operational availability computation model that can be used on the weapon system's requirement planning phase. The proposed model consists of the time parameters of Ao(Operational Availability) for a system and each time parameter's estimation method. The time parameters for Ao computation are TT(Total Time) and TDT(Total Down Time). The time parameters are defined by considering OMS/MP(Operational Mode Summary/Mission Profile) elements. TT is a calendar time as a specific mission time at wartime or one year at peacetime. TDT consists of TPM(Total Preventive Maintenance time), TCM (Total Corrective maintenance time), TALDT(Total Administrative and Logistics Down Time). Then the estimation method for these time parameters are presented by the weapon systems types.

• Journal of the Korean Society of Systems Engineering
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• v.13 no.2
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• pp.42-48
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• 2017

OCD (Operational Concept Document) is very important in system development. To develop OCD we should answer questions about, what template to use, what is the overall process to develop OCD, what kinds of diagrams we should use and how can we validate the OCD. To answer about the template we compared tow industrial guide on operational concept development and tailored it. For development process, we proposed a comprehensive process which satisfies the requirements of the project context. For use of proper diagram, we analyzed many kinds of diagrams used in representing behavior of system and choose some diagrams which best fit for our purpose. Finally we established validation criteria for operational scenario and requirement texts in operational concept documents.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.2
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• pp.9-17
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• 2019

In order to deal with high uncertainty and variability in emergency medical centers, many researchers have developed various models for their operational planning and scheduling. However, most of the models just provide static plans without any risk measures as their results, and thus the users often lose the opportunity to analyze how much risk the patients have, whether the plan is still implementable or how the plan should be changed when an unexpected event happens. In this study, we construct a simulation model combined with a risk-based planning and scheduling module designed by Simio LLC. In addition to static schedules, it provides possibility of treatment delay for each patient as a risk measure, and updates the schedule to avoid the risk when it is needed. By using the simulation model, the users can experiment various scenarios in operations quickly, and also can make a decision not based on their past experience or intuition but based on scientific estimation of risks even in urgent situations. An example of such an operational decision making process is demonstrated for a real mid-size emergency medical center located in Seoul, Republic of Korea. The model is designed for temporal short-term planning especially, but it can be expanded for long-term planning also with some appropriate adjustments.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.595-602
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• 2009

In this study, a two-dimensional storm surges/tide prediction model called the Storm surges/Tide Operational Model (STORM) was applied as the operational forecast model of the Korea Meteorological Administration (KMA). The operational model results were verified for two years (2006-2007) using observed results from tidal stations. Comparisons of modeled and observed storm surges show that larger differences at the western coast of Korea than at the southern and eastern coasts. The averaged root mean square error between the modeled and observed storm surges height are 0.16 m and 0.10 m in 2006 and 2007, respectively.

• Asia pacific journal of information systems
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• v.25 no.3
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• pp.597-625
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• 2015

Prior research has emphasized the significant effect of service orientation on organizational performance. However, little research on service orientation has been conducted in the financial field, including the investment management service industry in which high quality service for clients is required. In this paper, we propose a research model that centers on the concept of service orientation as a type of dynamic capability affecting firm performance. The research variables include job competency, risk management capability, operational capability, service orientation, and service performance. We assume that service orientation partially mediates the effects of risk management capability and operational capability on service performance. To test the model, we collected data from 391 fund managers in 86 teams (37 investment management companies) and analyzed it with partial least squares (PLS) method. Each of the 391 fund managers was asked to answer team level measures, which is effective for team level analysis. We find that job competency positively affects both risk management capability and operational capability, which in turn affect service orientation. Risk management capability and operational capability are assumed to directly affect service performance. However, risk management capability does not influence perceived service performance, whereas operational capability does affect it. This result indicates that risk management capability does not directly affect service performance. However, via service orientation, considering that risk management inconveniences customers and is geared to enhance service orientation, service performance is positively affected. Operational capability does not influence service orientation, whereas it affects perceived service performance. This result reveals that operational capability directly affects firm performance. As expected, service orientation significantly affects the service performance perception of fund managers. This study contributes to the literature by introducing service orientation to the financial industry and measures and tests team-level service performance. Our findings also provide insights to practitioners because to enhance team performance, managers must focus on service orientation in addition to operational capability.