• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.279-285
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• 2016

The space radiation dose over air routes including polar routes should be carefully considered, especially when space weather shows sudden disturbances such as coronal mass ejections (CMEs), flares, and accompanying solar energetic particle events. We recently established a heliocentric potential (HCP) prediction model for real-time operation of the CARI-6 and CARI-6M programs. Specifically, the HCP value is used as a critical input value in the CARI-6/6M programs, which estimate the aviation route dose based on the effective dose rate. The CARI-6/6M approach is the most widely used technique, and the programs can be obtained from the U.S. Federal Aviation Administration (FAA). However, HCP values are given at a one month delay on the FAA official webpage, which makes it difficult to obtain real-time information on the aviation route dose. In order to overcome this critical limitation regarding the time delay for space weather customers, we developed a HCP prediction model based on sunspot number variations (Hwang et al. 2015). In this paper, we focus on improvements to our HCP prediction model and update it with neutron monitoring data. We found that the most accurate method to derive the HCP value involves (1) real-time daily sunspot assessments, (2) predictions of the daily HCP by our prediction algorithm, and (3) calculations of the resultant daily effective dose rate. Additionally, we also derived the HCP prediction algorithm in this paper by using ground neutron counts. With the compensation stemming from the use of ground neutron count data, the newly developed HCP prediction model was improved.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.386-395
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• 2010

Widespread deployment of infrastructure WLANs has made Wi-Fi an integral part of today's Internet access technology. Despite its crucial role in affecting end-to-end performance, past research has focused on MAC protocol enhancement, analysis, and simulation-based performance evaluation without sufficiently considering a misbehavior stemming from capture effect. It is well known that the capture effect occurs frequently in wireless environment and incurs throughput unfairness between nodes. In this paper, we propose a novel Fair MAC algorithm which achieves fairness even under physically unfair environment. While satisfying the fairness, the proposed algorithm maximizes the system throughput. Extensive simulation results show that the proposed Fair MAC algorithm substantially improves fairness without throughput reduction.

• Solar Energy
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• v.15 no.2
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• pp.3-11
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• 1995

This paper reports the performance of solar domestic hot water systems manufactured with heat pipes. A series of tests were conducted on a number of systems to elicit the most suitable configuration of the system for possible commercialization in Korea. The heat pipe is made with a copper tube and the respective length of the evaporator, adiabatic, and condenser sections are 1700mm, 100mm and 200mm. The evaportor section is finned with a copper plate to increase solar input for its proper operation as a heat pipe. Results show quite an interesting performance data stemming from the difference in working fluids, presence of wick, and other various design parameters associated with the collection and utilization of solar energy.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.382-388
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• 2017

In response to the global warming crisis, the Kyoto protocol was established by major developed countries in 1997. The Paris Agreement, which imposes a carbon reduction obligation for both developed countries and developing countries, was signed in 2015. Regulations and efforts to reduce greenhouse gas emissions accordingly have been implemented. In this study, we analyzed the reduction of carbon emissions computerizing of the traditional project management system for efficient railway construction at Korea Rail Network Authority. We suggest a model that measures two major effects of carbon reduction, stemming from transportation and from a decrease of paper use. In this paper, we calculate the amount of carbon reduction and the economic effect of carbon reduction with application of the construction project management system at Korea Rail Network Authority. The model and methodology in this study are expected to be helpful to measure the carbon reduction performance for similar e-transformation.

• Journal of Soil and Groundwater Environment
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• v.25 no.2_spc
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• pp.86-100
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• 2020

Analyzing and monitoring environmental contaminants based on geophysical exploration techniques have become important and it is now widely applied to delineate spatial distribution geophysical characteristics in wide area. Among the techniques, induced polarization (IP) method, which measures polarization effects on electrical potential distribution, has drawn much attention as an effective tool for environmental monitoring since IP is sensitive to changes in biochemical reactions. However, various reactions stemming from the presence of multiple contaminants have greatly enhanced heterogeneity of polluted sites to result in highly variable electrical characteristics of the site. Those contaminants influence chemical and physical state of soil and groundwater to alter electrical double layer, which in turn influences polarization of the media. Since biochemical reactions between microbes and contaminants result in various IP effects, IP laboratory experiments were conducted to investigate IP responses of the contaminated soil samples under various conditions. Field IP surveys can delineate the spatial distribution of contamination, while providing additional information about electrical properties of a target medium, together with DC resistivity. Reviewing IP effects of contaminants as well as IP surveys can serve as a good starting point for the application of IP survey in site assessment for environmental remediation.

• Asian Journal of Innovation and Policy
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• v.10 no.2
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• pp.195-211
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• 2021

This paper measures the economic impacts of the U.S. port investment strategies coping with the Panama Canal expansion. Using secondary import data, negative and positive estimates of the impacts were presented in this study. Reduced port activities into the West Coast Customs Districts negatively affect transportation and warehousing industries, among other effects. Still, they have simultaneous positive effects in other states from increased imports resulting from modal shifts and changes in the entry port located in the South and East coasts. This study applied the supply-driven National Interstate Economic Model that measures all interstate trade among the U.S. states to divert foreign imports from 15 Pacific Rim countries. For this purpose, the following assumption was adopted: larger ships using the canal will lead to a redirection of seaborne trade among U.S. (and other) ports and result in secondary effects, e.g., using different freight modes and regional growth spillovers. This study also accounted for the entry point change and significant port investments for foreign trade under alternative scenarios. The choice of ports for international trade depends on decisions about how to minimize multimodal delivery costs. The total direct reduction of transportation and warehousing activities associated with foreign imports in the West Coast ports was estimated at $3.3 billion, leading to total negative effects of $5.8 billion. Total positive impacts from the shift of transportation modes with the choice of an entry port and new warehousing activities for foreign imports in the selected 12 states varied. As expected, states that involved an entry port had the most prominent benefits, but Texas, New York, and New Jersey may be benefited through all the port enhancement projects in the U.S. Also, except for Transportation and Postal, and Warehousing industries, Construction is another dominant positive affected industry of the Canal expansion in the U.S.

• Korea Real Estate Review
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• v.28 no.1
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• pp.65-77
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• 2018

This paper analyzes the redemption risk of renters by estimating the LTV and CoLTV with finance market big data (individual credit information) and housing market big data (actual housing transaction data). The analysis showed that when using LTV, the redemption risk was higher in the case of the monthly renter than of the chonsei renter. On the other hand, when using CoLTV, the chonsei renter had a higher redemption risk than the monthly renter. This implies that there is a need to activate a guarantee system, such as risk management using the CoLTV index and the chonsei deposit return guarantee because it is possible for renters to experience losses on their chonsei deposits due to the higher redemption risk. Another implication is that the risk manager should consider the individual characteristics of renters because of the different effects of the redemption risk stemming from the characteristics of the rental contract and the personal characteristics of the renters. CoLTV was just a concept until this study calculated it using housing big data and actual housing transaction information. It helps identify the redemption risk through the characteristics of renters and their contracts.

• Journal of the Korean Wood Science and Technology
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• v.47 no.3
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• pp.265-276
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• 2019

In our previous study, the LeNet3 model successfully classified images from the transverse surfaces of five Korean softwood species (cedar, cypress, Korean pine, Korean red pine, and larch). However, a practical limitation exists in our system stemming from the nature of the training images obtained from the transverse plane of the wood species. In real-world applications, it is necessary to utilize images from the longitudinal surfaces of lumber. Thus, we improved our model by training it with images from the longitudinal and transverse surfaces of lumber. Because the longitudinal surface has complex but less distinguishable features than the transverse surface, the classification performance of the LeNet3 model decreases when we include images from the longitudinal surfaces of the five Korean softwood species. To remedy this situation, we adopt ensemble methods that can enhance the classification performance. Herein, we investigated the use of ensemble models from the LeNet and MiniVGGNet models to automatically classify the transverse and longitudinal surfaces of the five Korean softwoods. Experimentally, the best classification performance was achieved via an ensemble model comprising the LeNet2, LeNet3, and MiniVGGNet4 models trained using input images of $128{\times}128{\times}3pixels$ via the averaging method. The ensemble model showed an F1 score greater than 0.98. The classification performance for the longitudinal surfaces of Korean pine and Korean red pine was significantly improved by the ensemble model compared to individual convolutional neural network models such as LeNet3.

• Agribusiness and Information Management
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• v.13 no.1
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• pp.1-25
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• 2021

Technological propensity of agricultural entrepreneurs is becoming necessary to identify and explore new opportunities. Recent studies suggest that the adoption of new technologies is strictly coherent with wider approaches of Entrepreneurial Orientation (EO). Even if the relevance of agriculture is increasing, entrepreneurial research has largely overlooked this challenging sector. Moreover, there is a relative shortage of empirical studies in the literature and there is an enormous potential to be still explored. Stemming from the EO literature, the work proposes for the agricultural sector, the approach of Humane Entrepreneurial Orientation (HEO). The paper proposes an empirical analysis, to verify the effect of the different dimensions of HEO on the propensity of farmers to adopt new technologies. All the results highlight several implications for businesses, for the research system and for public policies.

• Journal of Environmental Science International
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• v.30 no.2
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• pp.109-118
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• 2021

Due to changes such as those stemming from the onset of the fourth industrial revolution, it is expected that industrial complexes will transform from being spacious structures into smaller, integrated complexes. Green parks, which are also a type of infrastructure within industrial complexes, also require planned direction suited to the changing environment. The planned directions of green parks in new industrial complexes were examined and surveys were conducted on industrial complex workers. Preferred functional arrangement, importance, and satisfaction levels of green ratios, preference of compound facilities linked to parks, appropriate dimensional greening methods were all surveyed across 1,035 businesses. Results of the survey exhibited that there was high awareness on the importance of building green areas, but it was found that current greenery levels were insufficient. There was a high rate of responses indicated that dimensional greening is required in building-type industrial spaces, and preferences for rooftop greenery, stair-type greenery, and atrium greenery were also high. There were many opinions that it is necessary to integrate cultural facilities, exhibition and educational facilities, commercial facilities, parking lots in parks. Furthermore, it was found that it is necessary to provide pathways for bikes and pedestrians, rather than those for vehicles, and to connect them with the green parks. This study stopped short of exploring the directions for which green parks should aim in new industrial complexes with changes in the industrial environment. In the future, more concrete plans on green park planning techniques according to the spatial characteristics and structures of new industrial complexes will be necessary.