• Journal of the Korea Society of Computer and Information
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• v.19 no.1
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• pp.203-213
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• 2014

In this study, we proposed a new model with ISOIA (Insect Search by Observation based on Insect Appearance) method based on observation by insect appearance to improve user satisfaction, and compared it with the ISBC and ISOBC methods. In order to test these three insect search systems with AHP method, we derived three evaluation criteria for user satisfaction and three sub-evaluation criteria by evaluation criterion. In the ecological environment, non-experts need insect search systems to identify insect species and to get u-Learning contents related to the insects. To assist the public the non-experts, ISBC (Insect Search by Biological Classification) method based on biological classification to search insects and ISOBC (Insect Search by Observation based on Biological Classification) method based on the inference that identifies the observed insect through observation according to biological classification have been provided. In the test results, we found the order of priorities was ISOIA, ISOBC, and ISBC. It shows that the ISOIA system proposed in this study is superior in usage and quality compared with the previous insect search systems.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.3
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• pp.240-248
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• 2013

Torsional vibrations, such as the gear rattle of the manual transmission in vehicle systems, are correlated with the firing stroke from the engine. These vibro-impacts can be examined based upon linear time-invariant analysis. In order to understand the gear dynamics, a specific manual transmission with a front-engine front-wheel drive configuration is investigated. A method to reduce the degrees of freedom is suggested based upon the eigensolutions and frequency response functions, which will lead to the development of an efficient matrix size. The dynamic characteristics of single- and dual-mass flywheels are then compared. The effect of the dual-mass flywheel is investigated based upon the mobility analysis, which will lead to understanding of the concepts for avoiding vibro-impacts. A linear time-invariant system model is examined by employing the effective clutch stiffness from a two-stage clutch damper. Thus, the relationship between the dynamic characteristics and the clutch damper can be predicted by assuming a combination of different stage stiffness levels.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.230-240
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• 2013

Human powered aircraft: the aim is to fly only by human power, features many challenging issues. Contrary to the general aircraft operated by an engine, human powered aircraft, that manoeuvres by lower power, requires additional consideration about weight, material, aerodynamical and structural analysis. Since this aircraft flies at a low speed, low Reynolds number flight will need to be taken into account. In this paper, SNU (Seoul National University) Human Powered Aircraft was designed by comparing it with the existing human power aircrafts, as well as by using theoretical analysis that obtains the design parameters. Also, this paper discuss about the manufacturing process using composite material for real human powered aircraft.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.330-336
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• 2017

This study performs a root cause analysis of the sticking that occurs in the hydraulically actuated wet type multi-disc friction clutch in a ship's diesel engine propulsion system that uses rubber elastic coupling. The fishbone method was used to study the sticking through dismantling investigation of the reduction gear and clutch, investigation of the components, and onboard system tests including nondestructive testing. The friction plate sticking is caused by the slip due to friction heat resulting from the leakage of control oil through cracks in the assembled hollow shaft. The friction plate cooling oil also leaks simultaneously through the crack, and partial sticking occurs due to the hot spots in the friction plates. These are caused by insufficient amount of cooling oil due to oil leakage.

• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.391-400
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• 2007

According to the recent advances in multimedia computing, storage and searching technology have made large volume of music contents become prevalent. Also there has been increasing needs for the study on efficient categorization and searching technique for music contents management. In this paper, a new classifying method using the local information of music content and music tone feature is proposed. While the conventional classifying algorithms are based on entire information of music content, the algorithm proposed in this paper focuses on only the specific local information, which can drastically reduce the computing time without losing classifying accuracy. In order to improve the classifying accuracy, it uses a new classification feature based on music tone. The proposed method has been implemented as a part of MuSE (Music Search/Classification Engine) which was installed on various systems including commercial PDAs and PCs.

• Resources Recycling
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• v.11 no.4
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• pp.11-16
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• 2002

Analysis and separation of constituent materials of old car have been performed by using the industrial shredding line. For this aim, three old cars made by domestic automobile manufacturers, Sonata II, Sephia and Prince were chosen and delivered in pressed form without engine, tires and doors, etc. Shredding line was substantially composed of pre- and main-shredder. cyclone, magnetic separation, eddy current separation and man-power separation. From the separation of shredder products, iron scrap was observed to be the major material of old car accounting for 60.1 ％ of total weight and non-ferrous metals involving Al, Cu and Zn, etc. were about 2％. Light fluff, about 90％ of total fluff product, was comprised with plastic, fiber and sponge, etc. and the fraction of 5 cm undersize in light fluff was 70.5%. In case of heavy fluff, however. rubber and plastic were found to be the major constituent materials of it. Among the constituent materials of fluff, plastic showed the highest calorific value, more than 10,000 cal/gr and leather and rubber showed relatively high chlorine content, 10.3 and 2.55 wt%, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.475-481
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• 2019

The importance of performance-based design feedback is being emphasized when it comes to the potential impact that affects all the lifecycle of the building. However, the latency and disconnection of domain expert in the sector of AEC/FM remain current obstacles between design and performance feedback. It is hard to utilize performance feedback information for design exploration and support design decision making during the conceptual phase of design. Using parametric design, this paper proposes various design alternatives from a set of rules and constraints defined by algorithms for the geometric configurations of an Office Building. A Building Performance Analysis (BPA) was to developed using Autodesk® Revit® 2019 which integrates Autodesk® Green Building Studio® to predict its sufficient daylighting conditions of the LEED v4's Daylighting Autonomy (DA). The parametric-based performance feedback of this study outlines potential design improvements for further exploration in application to the early design process.

• Korean Journal of Cognitive Science
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• v.13 no.3
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• pp.33-46
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• 2002

Recently, unstructured random data such as website logs, texts and tables etc, have been flooding in the internet. Among these unstructured data there are potentially very useful data such as bulletin boards and e-mails that are used for customer services and the output from search engines. Various text mining tools have been introduced to deal with those data. But most of them lack accuracy compared to traditional data mining tools that deal with structured data. Hence, it has been sought to find a way to apply data mining techniques to these text data. In this paper, we propose a text mining system which can incooperate existing data mining methods. We use text mining as a preprocessing tool to generate formatted data to be used as input to the data mining system. The output of the data mining system is used as feedback data to the text mining to guide further categorization. This feedback cycle can enhance the performance of the text mining in terms of accuracy. We apply this method to categorize web sites containing adult contents as well as illegal contents. The result shows improvements in categorization performance for previously ambiguous data.

• Tribology and Lubricants
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• v.28 no.6
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• pp.315-320
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• 2012

For proper functioning, general machines usually need lubricant oil as a cooling, cleaning, and sealing agent at points of mechanical contact. The quality of lubricant oil can deteriorate during operation owing to various causes such as high temperature, combustion products and extraneous impurities. In this study, a heavy load stopped during operation, and the oil was analyzed to check whether any impurities were added. Extraction using acetonitrile followed by reaction with BSTFA(bistrimethylsilyl trifluoroacetamide) showed that, trimethylsilylated ethylene glycol was present in the lubricant oil. To quantify the ethylene glycol in the oil, deuterium-substituted ethylene glycol, which acted as an internal standard, was added to the sample and then extracted with the solvent. Next, the extract was reacted with the derivatizing agent(BSTFA) and then analyzed with GC/MS. The detection limit of this method was found to be $0.5{\mu}g/g$ and the recovery of oil containing $20,000{\mu}g/g$ of ethylene glycol was measured to be 94.8%. A damaged O-ring and eroded cylinder liner were found during the overhaul, which implied the leakage of coolant containing ethylene glycol into the lubricating system. The erosion of the cylinder liner was assumed to be due to cavitation of the coolant in the cooling system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.3
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• pp.373-378
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• 2013

The speed change performance of transmissions has become a serious issue because of the increase in the inertia moment that has accompanied increases in engine output and transmission size. Therefore, it is necessary to develop better wear resistant friction materials. In this study, an appropriate sintered friction component for the synchronizer ring of a diesel manual transmission was developed, and its bonding characteristics were analyzed. That is, a process for bonding an Fe-based base material and Cu-based sintered friction material was developed. BSE and EDX analyses of this bonding layer were conducted, along with a shear strength test, to determine the bonding characteristics.