• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.7-13
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• 2019

This study aims to develop a FE Model to simulate dissimilar friction stir welding and to address its potential for fundamental analysis and practical applications. The FE model is based on Coupled Eulerian-Lagrangian approach. Multiphysics systems are calculated using explicit time integration algorithm, and heat generations by friction and inelastic heat conversion as well as heat transfer through the bottom surface are included. Using the developed model, friction stir welding between an Al6061T6 plate and an AZ61 plate were simulated. Three simulations are carried out varying the welding parameters. The model is capable of predicting the temperature and plastic strain fields and the distribution of void. The simulation results showed that temperature was generally greater in Mg plates and that, as a rotation speed increase, not the maximum temperature of Mg plate increased, but did the temperature of Al plate. In addition, the model could predict flash defects, however, the prediction of void near the welding tool was not satisfactory. Since the model includes the complex physics closely occurring during FSW, the model possibly analyze a lot of phenomena hard to discovered by experiments. However, practical applications may be limited due to huge simulation time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.2
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• pp.327-333
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• 2019

For sustainable lunar exploration, the most required resources should be procured on site because it takes tremendous cost to transfer the resources from the Earth to the Moon. The technologies required for use of lunar resources refers to In-Situ Resource Utilization (ISRU). As the ISRU technology cannot be verified in the Earth, a lunar surface environment simulator is necessary to be prepared in advance. The Moon has no atmosphere, and the average temperature of the lunar surface reaches to $107^{\circ}C$ during the daytime and $-153^{\circ}C$ at night. The lunar surface is also covered with very fine soils with sharp particles that are electrostatically charged by solar radiation and solar wind. In this research, generation of vacuum environment with lunar soil mass in a chamber and simulation of electrostatically charged soils are taken into consideration. It was successful to make a vacuum environment of a chamber including lunar soils without soil disturbance by controlling evacuation rate of a vacuum chamber. And an experiment procedure for simulating the charged lunar soil was suggested by theoretical consideration in charging phenomena on lunar dust.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.528-534
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• 2019

This study analyzes the factors affecting China's carbon emissions from 1985 to 2016. In recent years, the whole industries of China are in the midst of industrialization and have several problems. Now, the low-carbon economy has become the main task of China's economic development. This study analyzes the factors affecting China 's carbon emissions by selecting relevant data onto the Chinese yearbook and using a time series model. The analysis shows that related industries continue to innovate and increase the use of green energy such as electricity, but coal is still the largest share of the energy consumed. As energy use efficiency increases and industrial R&D investment increases year by year, carbon emissions are increasing every year. In addition, there is a stereotype that industry is the biggest factor affecting carbon emissions. The research found that the impact of the industry on China's carbon emissions is declining gradually. While controlling industrial carbon emissions, keeping continue to improve technology development and focusing on carbon emissions from other industries are critical to reduce overall carbon emissions. Based on the empirical results, if we can change stereotypes starting from the nature of the data, we will quickly reach a low carbon sustainable development economy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.568-578
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• 2021

Patents that are research results from industry-university cooperation (IUC) are a source of innovation, and play an important role in economic growth, such as technology transfer and commercialization. For this reason, there are many efforts to revitalize IUC, but in general, company patents are achievements that can be commercialized, rather than research achievements, so not all patents are used for business, even after their creation as the outcome of IUC. Therefore, this research supports the design of measures in which IUC can ultimately be linked to successful utilization of patents by identifying the purposes of IUC, even after it has been successfully promoted, and patents have been filed as a result. To this end, first, the patents registered for industry-academia cooperation in the United States are collected, and second, a predictive model is designed, with unexpired and expired patents predicted using machine learning techniques. The final identified patents are intended to derive available factors in terms of marketability and technicality. This study is expected to help predict the utilization of unexpired and expired patents, and is expected to contribute to setting goals for research results from technical cooperation between corporate and university officials planning early IUC.

• Korean Journal of Construction Engineering and Management
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• v.22 no.4
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• pp.20-28
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• 2021

The Domestic Construction Industry is in the process of changing from a one-sided production method centered on the contractor to a production method in which the order and the contractor can collaborate. Depending on the delivery method, the bid/success method, the contract method, and the degree of business involvement of the order may also vary. In this thesis, in order to introduce 'Construction Management at Risk' suitable for the domestic environment, domestic and foreign institutional analysis, bid process analysis, contract fulfillment and management analysis, post management analysis, and related laws and regulations for legalization In order to suggest a plan for the efficient operation of the system, a system and case analysis of domestic and international construction responsibility type construction project management was conducted. 'Construction Responsible Construction Project Management' defined in the Framework Act on the Construction Industry is divided into the main contract transfer contract, which is a service contract performing pre-con work, and the main contract, which is construction project management and construction contract. Therefore 'Construction Management at Risk' should be regarded as one of the ordering methods rather than a successful bid system, as in the case of overseas, and legalization as a bidding system equivalent to design/construction batch bid and technology proposal is necessary for introduction. In order to introduce 'Construction Management at Risk' suitable for the domestic environment, domestic and foreign institutional analysis, bidding process analysis, contract fulfillment and management analysis, and follow-up management analysis are conducted. A method for efficient operation was suggested so that it can be applied in the domestic market while maintaining the original merits of this system.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.6
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• pp.308-320
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• 2021

An integrated sediment management approach that includes the recovery of the amount of declined sediment supply is effective as a fundamental solution to coastal erosion. During planning, it is essential to analyze the transfer mechanism of the sediments generated from estuaries (the junction between a river and sea) to assess the amount and rate of sediment discharge (from the river to sea) supplied back to the coast. Although numerical models that interpret the tidal sand bar flushing process during flooding have been studied, thus far, there has been no study focusing on the formation and development processes of tidal sand bars. Therefore, this study aims to construct wave deformation, flow regime calculation, and topographic change analysis models to assess the amount of recovered sediment discharge and reproduce the tidal sand bar formation process through numerical analysis for integrated littoral drift management. The tidal sand bar formation process was simulated, and the wave energy and duration of action concepts were implemented to predict the long-term littoral movement. The river flux and wave conditions during winter when tidal sand bars dominantly develop were considered as the external force conditions required for calculation. The initial condition of the topographic data directly after the Maeupcheon tidal sand bar flushing during flooding was set as the initial topography. Consequently, the tidal sand bar formation and development due to nearshore currents dependent on the incident wave direction were reproduced. Approximately 66 h after the initial topography, a sand bar formation was observed at the Maengbang estuary.

• Conservation Science in Museum
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• v.27
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• pp.1-22
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• 2022

A chimi(a roof ridge decoration) excavated from the Busosan Temple Site in Buyeo was restored in 1978 at the Buyeo Museum. The gypsum restoration material had deteriorated over time and part of it was seriously damaged and unable to bear the weight of the chimi. The chimi features traces of emergency treatment revealing that the inside of the body and some portions of the tail were reinforced several times using epoxy resin. A condition survey performed in preparation for its transfer for an exhibition found the lower body and wings of the chimi to be highly vulnerable and it was determined that the chimi needed further restoration. The dismantling of the chimi for restoration revealed several elements that provide clues to the production techniques applied by its makers, so they were subjected to inspection. This study explores the production techniques used in the chimi from the Busosan Temple Site that were revealed during the process of dismantling it for restoration. The chimi was inspected using 3D scanning and its rigid vertical shape was restored to a natural form based on the production techniques identified during the dismantling process. The existing restoration material was replaced to improve durability. 3D printed elements were produced based on 3D modelling and were joined to the original chimi to correct its shape and fill in the missing parts, restoring the chimi to its original appearance.

• Korean Journal of Ichthyology
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• v.33 no.4
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• pp.217-225
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• 2021

The family Platycephalidae is a taxonomic group of economically important demersal flathead fishes that predominantly occupy tropical or temperate estuaries and coastal environments of the Indo-Pacific oceans and the Mediterranean Sea. In this study, we for the first time analyzed the complete mitochondrial genome (mitogenome) of the flathead Platycephalus cultellatus Richardson, 1846 from Vietnam by Next Generation Sequencing method. Its mitogenome was 16,641 bp in total length, comprising 13 protein-coding genes (PCGs), two ribosomal RNA genes, and 22 transfer RNA genes. The gene composition and order of the mitogenome were identical to those of typical vertebrates. The phylogenetic trees were reconstructed based on the concatenated nucleotide sequence matrix of 13 PCGs and the partial sequence of a DNA barcoding marker, cox1 in order to determine its molecular phylogenetic position among the order Scorpaeniformes. The phylogenetic result revealed that P. cultellatus formed a monophyletic group with species belonging to the same family and consistently clustered with one nominal species, P. indicus, and two Platycephalus sp. specimens. Besides, the cox1 tree confirmed the taxonomic validity of our specimen by forming a monophyletic clade with its conspecific specimens. The mitogenome of P. cultellatus analyzed in this study will contribute valuable information for further study on taxonomy and phylogeny of flatheads.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.3
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• pp.155-163
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• 2022

The optimization of long-range ensemble climate prediction for rice phenology model with advanced bias correction method is conducted. The daily long-range forecast(6-month) of mean/ minimum/maximum temperature and observation of January to October during 1991-2021 is collected for rice phenology prediction. In this study, the concept of "buffer period" is newly introduced to reduce the problem after bias correction by quantile mapping with constructing the transfer function by month, which evokes the discontinuity at the borders of each month. The four experiments with different lengths of buffer periods(5, 10, 15, 20 days) are implemented, and the best combinations of buffer periods are selected per month and variable. As a result, it is found that root mean square error(RMSE) of temperatures decreases in the range of 4.51 to 15.37%. Furthermore, this improvement of climatic variables quality is linked to the performance of the rice phenology model, thereby reducing RMSE in every rice phenology step at more than 75~100% of Automated Synoptic Observing System stations. Our results indicate the possibility and added values of interdisciplinary study between atmospheric and agriculture sciences.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.4
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• pp.362-373
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• 2022

For a full-mouth fixed prosthetic treatment of the edentulous patient, it is essential to confirm the proper tooth position and thorough evaluation of the remaining alveolar bone and soft tissue before surgery. CAD-CAM dentistry and guided implant surgery have such advantages of providing simultaneous planning of surgery and prosthetic treatment to ensure pre-knowledge of the treatment. In this clinical case, using the digital technology, digital temporary denture fabrication, esthetic evaluation before fixed prostheses treatment, and guided surgery planning was possible. After the surgery, previously obtained data was used for fabricating fixed temporary prostheses. Definitive zirconia prostheses transferred from the provisional prostheses were fabricated and functionally and esthetically satisfying results were obtained.