• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.4
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• pp.511-521
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• 2022

Decommissioning of nuclear power plants generates a large amount of radioactive waste in a short period. Moreover, Radioactive waste has various forms including a large volumes of metal, concrete, and solid waste. The disposal of decommissioning waste using 200 L drums is inefficient in terms of economics, work efficiency, and radiation safety. Therefore, The Korea Radioactive Waste Agency is developing large containers for the packaging, transportation, and disposal of decommissioning waste. Assessing disposability considering the characteristics of the radioactive waste and facility, convenience of operation, and safety of workers is necessary. In this study, the exposure dose rate of workers during the disposal of new containers was evaluated using Monte Carlo N-Particle Transport code. Six normal and four abnormal scenarios were derived for the assessment of the dose rate in a near surface disposal facility operation. The results showed that the calculated dose rates in all normal scenarios were lower than the direct exposure dose limitation of workers in the safety analysis report. In abnormal scenarios, the work hours with dose rates below 20 mSv·y^-1 were calculated. The results of this study will be useful in establishing the optimal radiation work conditions.

• Structural Engineering and Mechanics
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• v.86 no.2
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• pp.221-235
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• 2023

To calculate the vibrations of a tout cable subjected to axial support excitations, a nonlinear relationship of cable force and the support displacement under static situations are employed to depict the quasi-static vibration of the cable. The dynamic components of quasi-static vibration are inputted as "direct loads" to cause the parametric vibrations on the cable. Both the governing equations of motion and deformation compatibility for parametric vibrations are then derived, which indicates the high coupling of cable parametric force and deformation. Numerical solutions, based on the finite difference method, are put forward for the parametric vibrations, which is validated by the finite element method under periodic axial support excitations. For the quasi-static response, the shorter cables are more sensitive to support excitations than longer ones at small cable force. The quasi-static cable force makes the greatest contribution to the total cable force, but the parametric cable force is responsible for the occurrence of cable loosening at large excitation amplitudes. Moreover, this study also revealed that the traditional approach, assuming a linear relationship between quasi-static cable force and axial support displacement, would result in some great error of the cable parametric responses.

• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.6
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• pp.758-766
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• 2023

Multi-copter of unmanned aerial vehicle (UAV) was initially developed as strategic technology in the only military field, but it is developing into an industrial field with a wide range of applications in the civil sector based on the development and convergence of aviation technology and information and communication technology. Currently, the degree of utilization of multi-copter is increasing in various industries for the purpose of performing classic tactical missions, logistics transportation, farm management, internet supply, video filming, weather management, life-saving, etc, and active technology development responding to market demand. Existing commercial multi-copter mainly use an electric energy propulsion system consisting of an electric battery and a brushless direct current (BLDC) motor. It is the limitations for usage in the flying time (up to 20 minutes) and payload (less than 20 kg). this study aims to overcome these limitations and expand the commercialization of engine-powered multi-copter of UAV in various industries in the futures.

• Journal of ILASS-Korea
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• v.28 no.4
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• pp.176-183
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• 2023

Many countries are striving to reduce carbon emissions with the goal of net zero by 2050. Accordingly, vehicles are rapidly being electrified to reduce greenhouse gases in the transportation sector. However, many organizations predict that internal combustion engines of LDV (light-duty vehicle) will exist even in 2050, and it is difficult to electrify aircraft and large ships in a short time. Therefore, synthetic fuel (i.e., e-Fuel) that can reduce carbon emissions and replace existing fossil fuels is in the spotlight. The e-Fuel refers to a fuel synthesized by using carbon obtained through various carbon capture technologies and green hydrogen produced by eco-friendly renewable energy. The purpose of this study is to compare and analyze the injection and spray characteristics of the simulated e-Gasoline. We mixed the hydrocarbon fuel components according to the composition ratio of the synthetic fuel produced based on the FT(Fischer-Tropsch) process. As a result of injection rate measurement, simulated e-Gasoline showed no significant difference in injection delay and injection period compared to standard gasoline. However, due to the low vapor pressure of the simulated e-Gasoline, the spray tip penetration (STP) was lower, and the size of spray droplets was larger than that of traditional gasoline.

• Asia pacific journal of information systems
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• v.30 no.1
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• pp.214-228
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• 2020

Shared value enhances the competitiveness of a company while simultaneously reducing societal burdens. By allowing companies to share their resources, collaborative logistics systems provide companies with an opportunity to create shared value, namely, not only economic value by enhancing the utilization of resources, but also social value by reducing energy consumptions and greenhouse gas emissions associated with logistics and transportation. Emerging businesses, such as ES3 and Flexe, have recently demonstrated how they created shared value through collaborative logistics services, for example, ES3's collaborative warehousing and direct-to-store (D2S) program, and Flexe's on-demand warehousing platform. However, the development of collaborative logistics systems is currently at a nascent stage. There are quite a few socio-technical barriers to overcome for sharing resources (data as well as infrastructure). Drawing on the socio-technical approach, this research examines how companies create both economic and social value from collaborative logistics systems. We highlight socio-technical barriers, particularly one set of social barriers, that is, competition-oriented conservatism prevalent among companies. Using the case study methodology and interview data, we closely investigate ES3 and Flexe, which provide collaborative logistics services, and demonstrate how technical and social barriers are addressed to create shared value from collaborative logistics systems.

• Journal of the Korea Safety Management & Science
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• v.26 no.2
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• pp.93-105
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• 2024

In this study, based on previous research on personal broadcasting, we indirectly measured content quality, YouTuber attributes, user satisfaction, and behavioral intention, which are latent variables that cannot be directly measured, as measurement variables, and then measured theoretically between the latent variables. In order to analyze the causal relationship, we used a structural equation model to determine to what extent the content quality of the YouTube mukbang channel and the YouTuber's attributes influence behavioral intentions such as purchase, recommendation, and continued use according to viewers' satisfaction with use. We intend to analyze and verify the relationship between related variables. The research results are as follows. First, the value, relevance, timeliness, completeness, and data quantity of content quality were found to have no significant impact on user satisfaction. Second, the trustworthiness, expertise, attractiveness, and intimacy of YouTuber attributes were found to have a significant impact on user satisfaction, but the similarity of YouTuber attributes did not have a significant impact on usage. Third, user satisfaction was found to have a significant impact on behavioral intentions and purchase intentions. However, user satisfaction was not found to have a direct significant impact on recommendation intentions or continued usage intentions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.143-149
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• 2016

This study evaluated the shear behavior of geogrid reinforced ballast material using a large scale direct shear test and discrete element method (DEM) based on PFC 3D program. The direct shear test was conducted on ballast materials that have different particle size distributions. Whereas the test results revealed that the shear strength generally increased with the larger particle size of ballast material without geogrid reinforcement, the shear behavior of ballast material was found to change pertaining to the relationship between particle size distribution and geogrid rib size. Generally, it is deemed the effectiveness of reinforcement can be achieved when the rib size is two times greater than average particle size. A numerical analysis based on DEM was conducted to verify the test results. The geogrid modeling was successfully completed by calibration process along with sensitivity analysis to have actual tensile strength provided by manufacturer. With a given geogrid model, the parametric evaluation was further carried out to examine the interactive behavior between geogrid and ballast material. Consequently, it was found that the effectiveness zone of geogrid reinforcement generated within a specific depth.

• Journal of Preventive Medicine and Public Health
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• v.42 no.4
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• pp.251-260
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• 2009

Objectives : To estimate the annual socioeconomic costs of stroke in Korea in 2005 from a societal perspective. Methods : We identified those 20 years or older who had at least one national health insurance (NHI) claims record with a primary or a secondary diagnosis of stroke (ICD-10 codes: I60-I69, G45) in 2005. Direct medical costs of the stroke were measured from the NHI claims records. Direct non-medical costs were estimated as transportation costs incurred when visiting the hospitals. Indirect costs were defined as patients and caregivers productivity loss associated with office visits or hospitalization. Also, the costs of productivity loss due to premature death from stroke were calculated. Results : A total of 882,143 stroke patients were identified with prevalence for treatment of stroke at 2.44%. The total cost for the treatment of stroke in the nation was estimated to be 3,737 billion Korean won (KRW) which included direct costs at 1,130 billion KRW and indirect costs at 2,606 billion KRW. The per-capita cost of stroke was 3 million KRW for men and 2 million KRW for women. The total national spending for hemorrhagic and ischemic stroke was 1,323 billion KRW and 1,553 billion KRW, respectively, which together consisted of 77.0% of the total cost for stroke. Costs per patient for hemorrhagic and ischemic stroke were estimated at 6 million KRW and 2 million KRW, respectively. Conclusions : Stroke is a leading public health problem in Korea in terms of the economic burden. The indirect costs were identified as the largest component of the overall cost.

• The Korean Journal of Air & Space Law and Policy
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• v.20 no.1
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• pp.143-209
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• 2005

In 1994, the North Korea indicated their intention to open up airspace. The air route passing through from Daegue FIR to Pyungyang FIR has established in 1996. The air transport cooperation between South and North Korea seemed to be reinforced at the event of President Kim, Dae-Jung's visit to North Korea by passing through a temporarily established Yellow Sea Airway in the year of 2000. The nature characteristics of air transport burdening of many circumstantial situations, however, have kept cooperation between South and North Korea from being facilitated till now. Recently as the more exchange between North and South Korea, the more frequent opportunities to discuss economic cooperation, which in sequence increased political credibility has been increased. The rail, road, and port reconnecting has realized which have been regarded impossible. Furthermore, it is expected to transport personnel and goods through South-North direct connected routes in the near future This study shows several meanings of air transport cooperation between South and North Korea. It will be far beyond simply partial air route connecting in this region, it gives great significance to realize economic cooperation and Northeast hub through air transport industry sector. This will be an exit for air transport industry have suffered limits derived from North Korea troubles and difficulties in growing as Northeast air hub. Namely, South-North air connection denote its meaning in providing opportunities Korea to be Northeast Hub and advanced country having globally competitive air transport industry To develop strategy for air transport cooperation between South and North Korea. they were developed by SWOT analysis on the basis of circumstantial analysis. These strategy need to be commanded properly to the changes of surrounded circumstances. The study result show it is desirable to apply phasal strategies by using strengths, weaknesses, threats and opportunities factors underlying analysis of inner and outer circumstances to cooperate in air transport sector.