• Journal of KIISE:Computer Systems and Theory
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• v.37 no.1
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• pp.27-34
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• 2010

Web crawlers are fundamental programs which iteratively download web pages by following links of web pages starting from a small set of initial URLs. Previously several web crawling orderings have been proposed to crawl popular web pages in preference to other pages, but some graph search techniques whose characteristics and efficient implementations had been studied in graph theory community have not been applied yet for web crawling orderings. In this paper we consider various graph search techniques including lexicographic breadth-first search, lexicographic depth-first search and maximum cardinality search as well as well-known breadth-first search and depth-first search, and then choose effective web crawling orderings which have linear time complexity and crawl popular pages early. Especially, for maximum cardinality search and lexicographic breadth-first search whose implementations are non-trivial, we propose linear-time web crawling orderings by applying the partition refinement method. Experimental results show that maximum cardinality search has desirable properties in both time complexity and the quality of crawled pages.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.410-419
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• 2015

In this study, the roadability, fuel economy and emission characteristics were evaluated for a natural gas converted vehicle. The results are as follows; Not only the shortage of power was observed in stall test, but also large deterioration of acceleration performance was exposed in roadability. Compared to the original LPG system, the acceleration is 76% in start acceleration and 45 ~ 65% in overtaking acceleration, especially the decline became larger when air conditioner is at work. Furthermore, because the mapping data, which controls the injection depending on driving condition, do not match up with injection system, the failure of air-fuel ratio feedback control occurs resulting from the large gap between the required and the really supplied amount of fuel. This failure cause the exhaust gas to emit without catalytic conversion and the fuel economy based on the fuel heat value to get worse 22% in the mode test and 16% in road test respectively. In addition, the existing injection system does not secure enough fuel at the starting so that it may lead to the fail of clod start, the deterioration of hot start and inharmonic of engine at the idle after start.

• Journal of Information Technology Applications and Management
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• v.26 no.3
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• pp.61-80
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• 2019

The cooperation between universities and industries is already one of the most important factors driving the national economy in the knowledge-based society of the 21st century represented by the Fourth Industrial Revolution. The Korean government has also been carrying out legal and institutional re-adjustments to promote industrial-university cooperation in line with demands for such changes in the times. However, despite this industry-academic cooperation system, there is still a significant mismatch between industrial demand and the university's workforce development system. By the way, there is a Cooperative Education(CO-OP) in Canada and the United States. It's an innovative link between the university and the industry. The reason is that the CO-OP program not only allows students to gain experience with their majors in the industrial field, but also plays a positive role in improving their specialty expertise. In particular, field information, ideas, and job insights that students acquire through CO-OP also serve as motivation for starting a business beyond employment after graduation. Furthermore, CO-OP experience is an important opportunity for future researchers to come up with commercialized research results that are not separated from the field sites The purpose of this study is to overcome the gap between industrial demand and the college manpower training system, and develop a Korean-style coaching program model as a growth engine for creative talent-building policies, represented by 'creation of start-ups and new industry.' In addition, this study suggested measures that can be applied in real universities. In addition, the study also highlighted that the introduction of CO-OP programs with field practices in Korea could also boost start-ups. Based on the Korean CO-OP program model, the curricula applicable to domestic universities consisted of two types : general and research-oriented university types.

• Journal of Advanced Navigation Technology
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• v.24 no.4
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• pp.251-260
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• 2020

Unlike manned aerial vehicles, because an unmanned aerial vehicle (UAV) has a limitation which allows only remote test during flights, it is very important to maintain the high reliability of the vehicle through pre- and post-flight tests. To this end, this paper designed an air vehicle test equipment (AVTE) for UAV which meets the derived hardware and software requirements. Based on this design, the AVTE was implemented in accordance with the actual test scenario. The implemented AVTE has the advantage of reducing the time and cost required for the test of UAV by allowing the operator to perform automatic or manual tests for necessary parts in various situations such as before and after starting engine and pre- and post-flight tests. Furthermore, this study is expected to help with the design and implementation of AVTE for other UAVs.

• Transactions of Materials Processing
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• v.30 no.6
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• pp.291-300
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• 2021

Currently, starting with electric vehicles, the application of ultra-high-strength steel sheets and light metals has expanded to improve mileage by reducing vehicle weight. At a time when internal combustion engine vehicles are rapidly changing to electric vehicles, the application of ultra-high-strength steel is expanding to satisfy both weight reductions and the performance safety of the chassis parts. There is an urgent need to improve the quality of parts without defects. It is particularly difficult to estimate the part formability through the finite element method (FEM) in the burring operation, so product design has been based on the hole expansion ratio (HER) and experience. In this study, design of experiment (DOE), analysis of variance (ANOVA), and regression analysis were combined to optimize the formability by adjusting the process variables affecting the burring formability of ultra-high-strength steel parts. The optimal variables were derived by analyzing the influence of variables and the correlation between the variables through FE analysis. Finally, the optimized process parameters were verified by comparing experiment with simulation. As for the main influence of each process variable, the initial hole diameter of the piercing process and the shape height of the preforming process had the greatest effects on burring formability, while the effect of a lower round of punching in the burring process was the least. Moreover, as the diameter of the initial hole increased, the thickness reduction rate in the burring part decreased, and the final burring height increased as the shape height during preforming increased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.3
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• pp.195-203
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• 2019

Since the hypersonic intake is directly related to the overall performance of the engine, it is essential to analyze performance characteristics under various off-design conditions. In this paper, Busemann intake and conical intake with external compression were designed, and numerical simulations were performed at on/off-design conditions. Based on the results, the overall performance characteristics of two types of intake were analyzed in various Mach numbers and angle of attacks. The results showed that performance degradation of Busemann intake with truncation angle of 2 degrees was minimal. Also, the performance of Busemann intake was higher than external compression intake at various Mach numbers, however, the starting characteristics were significantly reduced with an angle of attack.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.7
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• pp.529-537
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• 2021

Wind tunnel tests were carried out with a scramjet high speed vehicle. Since the scramjet engine does not have a compressor, it has a simple structure, but it is important to design the intake for the supersonic combustion in the combustion chamber. In this study, internal flow characteristics and the starting condition were analyzed by measuring the pressure at the isolator exit just before the combustion chamber, and the intake performance parameters were calculated and compared the result on every Mach number. The aerodynamic characteristics of the flow-through high speed vehicle were analyzed and internal drag correction is required to precisely analyze the aerodynamic characteristics. In this paper, an experimental technique using three probes for internal drag correction was proposed. By applying internal drag correction, it was able to figure out the effect of the internal flow on the aerodynamic force of the vehicle.

• Journal of the Korea Fashion and Costume Design Association
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• v.19 no.2
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• pp.29-37
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• 2017

Due to the pursuit of individuality by modern consumers, the day has come when it is hard for design to be sustained solely by external beauty. Accordingly, products with the psychological value and brand stories are appearing, so that products that reinterpret traditional crafts are now being appreciated for their merits. Handmade goods defined as new luxury goods or products of high-quality craftsmanship are being used to enhance the consumer's individual image, and has created an unprecedented consumer stratum structure. Japan is one of the countries that actively applies traditional crafts to contemporary design and this study aims to investigate cases that are being reinterpreted in modern fashion in the theme of Boro, which is not as well known among Japanese traditional crafts. The purpose of this study is to offer basic data for designers by investigating the cases of the reinterpretation of traditional crafts. In addition, in reinterpreting traditional crafts into other fields, it is regarded as a meaningful way to contribute to a variety of other ideas. As the research method, first, the definition and kind of Boro were investigated utilizing the related literature information about the traditional fabric of Boro, which is the starting point and basis of the research. Second, Japanese aesthetic sense defined in the previous research was classified and the relationship of the anti-decorative aesthetic sense and Boro investigated. Third, after classifying the reinterpretation cases of Boro that have appeared in four major fashion collections and designer brands from 2011 to 2016 by the selected aesthetic sense, its characteristics were investigated. The search for examples of the reinterpretation of Boro uses the results of the keyword search of Boro and Boro Fashion via the internet search engine Google from April 2016 to December 2016. In addition, the search results were selected on the basis of whether the designer specified borrowing from Boro or whether Boro on the collection order was included or not. In addition to introducing an unknown fabric craft, this study also raises the methodological problems of the reinterpretation of traditional crafts. Products containing psychological value are expected to come into the spotlight in the upcoming consumer market. Therefore, as a follow-up study, it is suggested to research examples in which various crafts are being applied as products before one knows, how this creates new originality, and the limitations involved in this.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.703-709
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• 2017

Korea Utility Helicopter(KUH) is a project to replace the aging helicopter presently being operated by the military with a domestic helicopter. The auxiliary power unit is a device that supplies emergency power to the system by an alternator installed when the main generator fails and the start motor converts the electrical energy of the battery into mechanical rotational energy to rotate the auxiliary power unit engine. With continuing power and operation, defects of the starting motor were found and improvements were carried out to solve it. In the failure mode analysis, the causes of possible defects were classified into 5 categories. Analysis of the 5 factors revealed that the main cause of defects is mechanical wear, which was found to be related to spring pressure. 250 tests were conducted through the theoretically determined pressure and regression analysis was performed with 4 sampling.The results showed that pressure was related to wear rate. In conclusion, early wear and breakage due to wear can be controlled through spring force and test showed the prediction of wear and the validity of the result were confirmed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.162-170
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• 2021

The Smart City Living Lab is becoming important as a local innovation platform to develop urban solutions. In January 2018, the 4th industrial innovation committee, which was a direct subordinate from the president, empathized citizens' participation and their roles within the Smart City [Urban Innovation and Future Growth Engine-Creating Smart City Strategy]. This was the starting point of the living lab. The central government and local governments have been promoting various types of living labs to encourage citizens to participate. On the other hand, due to the lack of systematic concepts and theories for practicing and structuring living labs, the practice is not performed well. This study aimed to develop systematic approaches and implementation methods of the public-led Smart City Living Lab. The Full-cycle Smart City living Lab model was designed by integrating smart city living lab work processes, as suggested in the standards of the national land plan, double design diamond framework, which is a type of innovative design methodology, and design thinking process. The entire cycle Smart City living lab model requires four components to practice the living lab, such as framework, module, process, and methodologies. In the future, this model is expected to be incorporated in the Smart City Living Lab.