• The Journal of the Acoustical Society of Korea
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• v.42 no.2
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• pp.83-93
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• 2023

Trapezoidal corrugated plates are often treated as orthotropic plates to simplify the modelling of the corrugation. However, this simplification is not valid at high frequencies in which the localized vibration within the parts of corrugation takes place. In this study, the vibrational and acoustical characteristics of corrugated plates are investigated up to high frequencies by means of the wavenumber domain numerical approach. Based on the findings from this numerical analysis, an approximate method to predict vibro-acoustic characteristics of corrugated plates is proposed. This approximate model consists of four equivalent plates which can represent global and local behaviours of corrugated plates. The radiation efficiency of corrugated plates is predicted from the approximate model and validated through the comparison with those of the numerical method.

• Journal of the Korean Geotechnical Society
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• v.26 no.9
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• pp.47-58
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• 2010

This paper presents the injection efficiency of 2.0 shot system which was verified by strength and injection time. In order to perform this study, laboratory model tests and field tests are carried out. The laboratory model tests consist of the test of injection time for verifying the injection ratio, and the tests of homo-gel and sand-gel strengths for estimating the characteristic of strength. It is found that the injection ratio of 1:2 shows the best seepage into the ground. The results of the strengths are also larger than other injection ratio. The large strength will also be expressed by field tests at construction site.

• International Area Studies Review
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• v.13 no.1
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• pp.103-122
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• 2009

The paper is basically designed to investigate any existence of co-movement among foreign exchange market, goods market, and monetary market implemented by relative PPP and interest rate parity. And, rational expectation and GARCH-M model are employed for an empirical application. The result revealed that since the co-movement among the markets is hardly found, an efficiency of foreign exchange market is independent from any shocks from the goods market and the monetary market. Whereas, the exchange rate is strongly effected by a real interest rate parity. To this end, the real interest rate should be a key policy instrument to stabilize the foreign exchange market.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.162-163
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• 2022

Maritime transportation is going to transfer to alternative fuels as a result of the worldwide demands toward decarbonization and tougher maritime emissions regulations. Methanol is considered as a potential marine fuel, which has the ability to reduce SOx and CO₂ emissions, reduce climate change effects, and achieve the objective of green shipping. This work proposes and combines the innovative combination system of direct methanol solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC), gas turbines (GT), and organic Rankine cycles (ORC) for maritime vessels. The system's primary power source is the SOFC, while the GT and PEMFC use the waste heat from the SOFC to generate useful power and improve the system's ability to use waste heat. Each component's thermodynamics model and the combined system's model are established and examined. The multigeneration system's energy and exergy efficiency are 76.2% and 30.3%, respectively. When compared to a SOFC stand-alone system, the energy efficiency of the GT and PEMFC system is increased by 19.2%. The use of PEMFC linked SOFC has significant efficiency when a ship is being started or maneuvered and a quick response from the power and propulsion plant is required.

• The Journal of Fisheries Business Administration
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• v.55 no.2
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• pp.17-37
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• 2024

In this study, the effect of Distribution efficiency through the fishery production base distribution center (FPC) on the production site board facility was studied. FPC is a new distribution system for Korean fishery products that has been promoted in earnest since 2012, and in this study, the effect before and after the introduction of FPC was analyzed using the DID (Difference in Difference) model for the effect of FPC in the fishery industry. The results of analysis shows that in the case of Wando Geumil FPC, the volume and unit price of consignment sales decreased during the analysis period, which was statistically significant. In the case of Sokcho FPC, the volume of consignment sales decreased during the analysis period, which was statistically insignificant. But the unit price of consignment sales rose during the analysis period, which was statistically significant. In the case of Gyeongju FPC, the volume of consignment sales increased during the analysis period, which was statistically significant at the 90% confidence level. But the unit price of consignment sales fell during the analysis period, which was statistically significant.

• Journal of Korean Society for Quality Management
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• v.44 no.4
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• pp.785-798
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• 2016

Purpose: This paper developed the framework for extracting strategies of research and business development (R&BD) based on the data envelopment analysis(DEA). Methods: DEA has been widely utilized in evaluating R&D efficiency. Even though, technology transfer and commercialization has been regarded as the important factors for practical R&D efficiency evaluation, most research have evaluated R&D efficiency by just using the DEA outputs such as the number of patents and papers. The technology transfer, commercialization and relations among costs and generated technology and commercialization are needed to be considered for more practical R&D efficiency evaluation. Thus, this research addressed a method on how to incorporate the commercialization factors into the R&DB efficiency evaluation, and improve the efficiency strategically in terms of R&D and B&D. To achieve this, this research utilized a two-stage network DEA model for R&BD efficiency evaluation. Results: The proposed framework was applied to the 15 public research institutes and the 34 universities for validation. R&BD efficiency for the 15 public research institutes and the 34 universities was evaluated, and the differentiated improvement strategies for the inefficient DMUs to improve their efficient were proposed. Conclusion: The R&BD efficiency would be effectively analyzed based on two-stage network DEA. It would be utilized for the effective strategy planning for cultivating R&BD.

• Journal of Korea Trade
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• v.25 no.5
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• pp.93-109
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• 2021

Purpose - The logistics industry is often featured by its location relevance and industrial concentration. Industrial concentration is conducive to the effective transmission of information by reducing transaction costs and improving transaction efficiency, thus promoting the development of trade. The main purpose of this paper is to measure the spatial total factor productivity and location quotient of the logistics industry in Korea, and to study the impact of the logistics industry efficiency and agglomeration effect on import and export trade in Korea. Design/methodology - First, used the spatial stochastic frontier method to measure the spatial total factor productivity of the logistics industry in Korea, this serves as the efficiency index of the logistics industry in various regions of Korea. Second, calculated the location quotient (LQ) of the logistics industry to measure the industry's concentration degree. Third, employed a spatial econometric model to analyze the impacts of factors such as the efficiency and concentration levels of the logistics industry on import and export trade in Korea. Findings - This study's main findings can be summarized as follows: this study found that the overall efficiency of the logistics industry in Korea needs to be improved, even though it showed an upward trend in all regions of the country; Moreover, the agglomeration level of Korea's logistics industry needs to be improved; Finally, the positive spatial correlation and industrial agglomeration effect of Korea's logistics industry had a positive impact on the country's import and export trade. Originality/value - This study is innovative in terms of research perspective and methods. Most of the previous studies have measured the development level of the logistics industry using the logistics performance index (LPI), Fewer studies have assessed through the spatial total factor productivity and location quotient of the logistics industry in Korea to measure the efficiency index of the logistics industry in various regions of Korea and concentration degree, as well as there was almost no study on the impact of logistics industry efficiency and agglomeration effect on import and export trade in Korea. This study addresses this limitation by analyzing the impacts of the efficiency and agglomeration effect of the logistics industry on import and export trade in Korea.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.353-363
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• 2021

This study analyzed to provide information for business improvement by analyzing the management efficiency of start-up investment companies so that startup investment companies can operate efficiently and by presenting information on inefficient factors. From 2014 to 2018, 83 start-up investment companies were analyzed using the DEA model. Input variables were he number of employees, capital, and output variables were selected for start-up investment assets, operating income, and net profit. As a result of the analysis, technical efficiency and pure technical efficiency showed a pattern with an increase in average, but scale efficiency repeatedly increased and decreased. It is believed that the decline in technology efficiency was due to the decrease in pure technology efficiency, and the inefficiency of start-up investment companies seems to have influenced the inefficiency of start-up investment companies rather than the inefficiency of scale. In addition, the size revenue shows that the DRS value is gradually decreasing, and the IRS value is generally increasing. It is believed that efficiency can be improved if operational inefficiency is improved based on the results and efficiency measures are established through scale expansion.

• The Journal of Society for e-Business Studies
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• v.26 no.2
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• pp.45-59
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• 2021

As software(SW) has been considered as a key driver of the fourth industrial revolution, significant R&D investment has been made by Korean government. Despite the attention and support by the government, systematic analysis on the SW R&D efficiency has not been fully addressed. In this study, the efficiency of SW national research and development projects was analyzed using Data Envelopment Analysis(DEA) techniques. Efficiency was measured from both static and dynamic perspectives based on 1,463 projects conducted by the National IT Industry Promotion Agency(NIPA) from 2008 to 2018. The static efficiency analysis identified the causes of inefficiency as scale and technology problems. As a result of dynamic efficiency analysis, we present a sector-specific response model using an efficiency-stability matrix. This study is meaningful in that efficiency analysis was conducted on the entire SW national R&D project, and static/dynamic efficiency analysis results are expected to be used as a guideline for planning SW national R&D project.

• Tunnel and Underground Space
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• v.24 no.6
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• pp.449-463
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• 2014

There are many case studies and application cases in abandoned mines for hydraulic filling method filled by slurry or paste form, but research on the pneumatic filling is not applied in Korea. The damage of steel pipe is occurred by wear due to the flow of filling material in the bent area of steel pipe in traditional pneumatic filling method. In this study, the new pneumatic filling method was developed using a newly devised improved nozzle to improve the above problem. The model test for mine filling was performed in the laboratory for the simulated accessible or inaccessible mine cavities, and the filling efficiency by the results obtained from the test was calculated. The filling efficiency was analyzed from the variation of outlet angle, feed rate and grain size of sand in model test of simulated accessible mine cavity. The superiority of improved pneumatic filling method was proved through the analysis of filling efficiency by the results obtained from each model tests of gravitational, traditional, and improved filling method in simulated inaccessible mine cavity.