• Nuclear Engineering and Technology
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• 제49권3호
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• pp.541-548
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• 2017

Uranium metal used for fabrication of fuel for research reactors in India is generally produced by magnesio-thermic reduction of $UF_4$. Performance of magnesio-thermic reaction and recovery and quality of uranium largely depends on properties of $UF_4$. As ammonium diuranate (ADU) is first product in powder form in the process flow-sheet, properties of $UF_4$ depend on properties of ADU. ADU is generally produced from uranyl nitrate solution (UNS) for natural uranium metal production and from uranyl fluoride solution (UFS) for low enriched uranium metal production. In present paper, ADU has been produced via both the routes. Variation of uranium recovery and crystal structure and composition of ADU with progress in precipitation reaction has been studied with special attention on first appearance of the precipitate Further, ADU produced by two routes have been calcined to $UO_3$, then reduced to $UO_2$ and hydroflorinated to $UF_4$. Effect of two different process routes of ADU precipitation on the characteristics of ADU, $UO_3$, $UO_2$ and $UF_4$ were studied here.

• 대한교통학회:학술대회논문집
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• 대한교통학회 2000년도 제37회 학술발표회논문집
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• pp.25-47
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• 2000

In route guidance systems fastest-path routing has typically been adopted because of its simplicity. However, empirical studies on route choice behavior have shown that drivers use numerous criteria in choosing a route. The objective of this study is to develop computationally efficient algorithms for identifying a manageable subset of the nondominated (i.e. Pareto optimal) paths for real-time vehicle routing which reflect the drivers' preferences and route choice behaviors. We propose two pruning algorithms that reduce the search area based on a context-dependent linear utility function and thus reduce the computation time. The basic notion of the proposed approach is that ⅰ) enumerating all nondominated paths is computationally too expensive, ⅱ) obtaining a stable mathematical representation of the drivers' utility function is theoretically difficult and impractical, and ⅲ) obtaining optimal path given a nonlinear utility function is a NP-hard problem. Consequently, a heuristic two-stage strategy which identifies multiple routes and then select the near-optimal path may be effective and practical. As the first stage, we utilize the relaxation based pruning technique based on an entropy model to recognize and discard most of the nondominated paths that do not reflect the drivers' preference and/or the context-dependency of the preference. In addition, to make sure that paths identified are dissimilar in terms of links used, the number of shared links between routes is limited. We test the proposed algorithms in a large real-life traffic network and show that the algorithms reduce CPU time significantly compared with conventional multi-criteria shortest path algorithms while the attributes of the routes identified reflect drivers' preferences and generic route choice behaviors well.

• Journal of Information Processing Systems
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• 제17권5호
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• pp.879-891
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• 2021

With improvements in living conditions, an increasing number of people are choosing to spend their time traveling. Comfortable tour routes are affected by the season, time, and other local factors. In this paper, the influencing factors and principles of scenic spots are analyzed, a model used to find the available routes is built, and a multi-route choice model based on a game theory utilizing a path recommendation weight is developed. A Monte Carlo analysis of a tourist route subjected to fixed access point conditions is applied to account for uncertainties such as the season, start time, end time, stay time, number of scenic spots, destination, and start point. We use the Dijkstra method to obtain multiple path plans and calculate the path evaluation score using the Monte Carlo method. Finally, according to the user preference in the input path, game theory generates path ordering for user choice. The proposed approach achieves a state-of-the-art performance at the pseudo-imperial palace. Compared with other methods, the proposed method can avoid congestion and reduce the time cost.

• Acta Via Serica
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• 제4권1호
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• pp.1-24
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• 2019

Bloody wars between Arab Muslims and Khazar Turks in the Caucasus continued for a more than a hundred years from the mid $7^{th}$ century to the end of the $8^{th}$ century CE. The Khazar state survived but had to withdraw from Caucasian Albania, the present territory of the Republic of Azerbaijan. However, the Khazars managed to expand their political control over the trade routes north-east and north-west of the Caucasian ridge. A trade partnership was established between former rival powers in the region that allows us to call the period after the end of the Arab-Khazar wars up to the time of the collapse of the Khazar state in the middle of the 10th century an era of Arab-Khazar partnership and domination of the Silk Road. This article highlights the impact made by geopolitical shifts in the regions of the time upon international trade tracks and particularly on the development of trade facilities, infrastructure, and local production in Azerbaijan, which became a major transit country of goods from the north to markets in the Muslim Near East.

• 전력전자학회논문지
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• 제24권3호
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• pp.139-146
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• 2019

As the number of electric vehicles (EVs) in Jejudo Island increases, the secondary use of EV batteries is becoming increasingly mandatory not only in reducing greenhouse gas emissions but also in promoting resource conservation. For the secondary use of EV batteries, their capacity and performance at the end of automotive service should be evaluated properly. In this study, the battery state information from the on-board diagnostics or OBD2 port was acquired in real time while driving three distinct routes in Jejudo Island, and then the battery operating characteristics were assessed with the driving routes. The route with higher altitude led to higher current output, i.e., higher C-rate, which would reportedly deteriorate state of health (SOH) faster. In addition, the SOH obtained from the battery management system (BMS) of a 2017 Kia Soul EV with a mileage of 55,000 km was 100.2%, which was unexpectedly high. This finding was confirmed by the SOH estimation based on the ratio of the current integral to the change in state of charge. The SOH larger than 100% can be attributed to the rated capacity that was lower than the nominal capacity in EV application. Therefore, considering the driving environment and understanding the SOH estimation process will be beneficial and necessary in evaluating the capacity and performance of retired batteries for post-vehicle applications.

• 산경연구논집
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• 제13권12호
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• pp.9-22
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• 2022

Purpose: Establishing a competitive advantage in the aviation market is essential as the competition among domestic airlines intensifies. Therefore, this study examined the management strategies of both large domestic airlines and low-cost airlines. Research design, data, and methodology: This study classified domestic airlines into Full Service Airlines (FSA) and Low Cost Carriers (LCC), examined each airline's current status and characteristics, and conducted case analyses of FSA and LCC based on Porter's generic competitive strategy. Results: The analyses determined that LCC primarily implemented a cost-advantage strategy, and FSA implemented a differentiation strategy. However, as competition intensified, FSA pursued cost-advantage strategies while establishing LCC through subsidiaries. There are various specific cost reduction methods, including service simplicity, scalability, high utilization, low landing fees, low-cost unit, and point-to-point flight strategies. Conclusions: LCCs are focusing on cost advantage strategies that reduce costs; however, the FSA also runs special price events that are as good as LCCs and are comparable to LCCs on some routes. Furthermore, LCC has recently expanded its mid- and long-distance routes, making competition for long-distance routes with major airlines unavoidable.

• 무역학회지
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• 제44권6호
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• pp.303-325
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• 2019

The purpose of this study is to determine optimal transportation routes through the comparison of Korean - European transportation routes of automotive parts and to suggest information that can be utilized in Korea - Europe trade activities or trade route selection by establishing multipath. This study analyzed the direct transportation cost, inventory cost, and warehouse inventory cost of the sea and TSR / TCR railroad transport based on characteristics of automotive parts logistics and multimodal transportation. Also, this study identifies the most effective transportation route from the viewpoint of total logistics cost. In addition to the economic factors, we conducted an in-depth analysis through interviews with corporate executives to identify the importance of the factors with the behavioral factors, and the reliability was further secured through interviews. Through this study, it is possible to understand various aspects of international logistics by analyzing the factors of transportation choice in terms of economic and behavioral perspectives concurrently by differentiating from existing research.

• International Journal of Computer Science & Network Security
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• 제21권4호
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• pp.33-40
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• 2021

The traveling salesman problem (TSP) is one of the well-known and extensively studied NPC problems in combinatorial optimization. To solve it effectively and efficiently, various optimization algorithms have been developed by scientists and researchers. However, most optimization algorithms are designed based on the concept of improving route in the iterative improvement process so that the optimal solution can be finally found. In contrast, there have been relatively few algorithms to find the optimal solution using route construction mechanism. In this paper, we propose a route construction optimization algorithm to solve the symmetric TSP with the help of ratio value. The proposed algorithm starts with a set of sub-routes consisting of three cities, and then each good sub-route is enhanced step by step on both ends until feasible routes are formed. Before each subsequent expansion, a ratio value is adopted such that the good routes are retained. The experiments are conducted on a collection of benchmark symmetric TSP datasets to evaluate the algorithm. The experimental results demonstrate that the proposed algorithm produces the best-known optimal results in some cases, and performs better than some other route construction optimization algorithms in many symmetric TSP datasets.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.115-116
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• 2020

Recently, due to fires in high-rise residential and commercial buildings and apartments in Ulsan and Busan, the issue of evacuation safety in the event of a building fire is being closely watched. In the evacuation safety design for these building fires, it is important to secure evacuation routes considering the spatial characteristics of the building or the characteristics of the occupants and to take measures to protect the evacuation routes in order to ensure the safety of the occupants in the event of a fire. Although simulation is mainly used in Korea to assess the safety of evacuation, there is a big difference in that the Building Standards Act provides tools that can be calculated more than simulation in neighboring Japan. In addition to the evaluation method, which is called the "Building Law Assessment Methods" in Japan, the research team considered that it is important to know the process of evaluation in future domestic research, and investigated the contents of the evaluation process and wanted to apply it first to domestic buildings in the future.

• 한국항공운항학회지
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• 제31권4호
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• pp.126-132
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• 2023

During the COVID-19 pandemic, there have been many changes in the aviation industry as a whole. Passenger traffic has decreased, but on the contrary, the international transport demand for cargo planes has never been higher. Due to their geopolitical location when flying to major cities around the world, Korea's international pilots are bound to have relatively more jet lag-causing routes than their American or European-based pilots. Through this study, we tried to analyze the degree of fatigue and fatigue weighting factors according to operating conditions for domestic pilots. As a result of the study, the following conclusions were drawn. Despite the variety of models, routes, and fatigue between individuals, it was found that the 3 Pilot operation route was concentrated as a representative fatigue route. Most of the individual fatigue improvement request sections showed higher fatigue as the night flight section was longer among the 3Pilot routes for more than 12 hours, and 43 out of 90 participants (Korean Air pilots) focused on 3Pilot (two captains and one pilot) as fatigue-intensive operating conditions. Therefore, it proposes an improvement in the system of applying 12-hour unification standards according to Korea's geopolitical international operating conditions and time difference standards.