• Journal of Engineering Education Research
• /
• v.16 no.1
• /
• pp.3-14
• /
• 2013

The previously developed practical inquiry activity supporting tools, deduced from the design principles and implementation principles based on the study of precedent researches and theories, applicable to conceptual learning in engineering education were implemented to an on-line learning community, a web-based Windows application, to find out its effectiveness in actual classroom situation through experimental research. The On-line learning community includes the inquiry activity menu to implement learning procedure of inquiry based conceptual learning, the functions supporting the communication among participants, the information sharing function, the scheduling function of class and inquiry activity, the mentoring function, and the evaluation of on-line activities of learners. Experimental study were also conducted in order to analyze the effects of inquiry activity supporting tools on inquiry based conceptual learning in engineering education.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.4
• /
• pp.149-158
• /
• 2015

Up-to-date manufacturing companies have faced a market-driven environment of pull production order. There should be a difference in operating manufacturing resources according to the type, quantity, and delivery time of manufactured products, because the process situation in pull production is changed by customer orders. And it should be taken into account from the stage of preparing for production such as process design and the placement and utilization of manufacturing resources. However, the feasibility of production plans is limited because most of small manufacturing businesses make production/supply plan of the parts and products assuming that equipment abilities in scheduling is sufficient without managing process standard information systemically. In this study, a discrete event simulation system based on BOM (bill of material), that is F-OPIS (online productivity innovation system), is introduced and a case study on application of the system leading to improving productivities is presented. F-OPIS deals with a decision-problem on production management and it is specialized for small-and- medium sized manufacturing companies. The target company of this case study is a typical small-and-medium sized manufacturing company in Korea, that produces various machined parts. The target company adopts make-to-stock production management to prevent tardy delivery because of fluctuations in demand. Therefore, it is required to apply an efficient inventory control solution for improving productivities. In this paper, based on the constraints of working capacity of manufacturing resources, the bottleneck process is analyzed as production conditions are changed. Consequently, an improvement plan is proposed, that eventually enhances overall utilization rates of resources in the bottleneck process and reduces overall production lead-time and inventory level.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.7
• /
• pp.2977-2997
• /
• 2018

In big data era, fresh data grows rapidly every day. More than 30,000 gigabytes of data are created every second and the rate is accelerating. Many organizations rely heavily on real time streaming, while big data stream computing helps them spot opportunities and risks from real time big data. Storm, one of the most common online stream computing platforms, has been used for big data stream computing, with response time ranging from milliseconds to sub-seconds. The performance of Storm plays a crucial role in different application scenarios, however, few studies were conducted to evaluate the performance of Storm. In this paper, we investigate the performance of Storm under different application scenarios. Our experimental results show that throughput and latency of Storm are greatly affected by the number of instances of each vertex in task topology, and the number of available resources in data center. The fault-tolerant mechanism of Storm works well in most big data stream computing environments. As a result, it is suggested that a dynamic topology, an elastic scheduling framework, and a memory based fault-tolerant mechanism are necessary for providing high throughput and low latency services on Storm platform.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.04a
• /
• pp.148-150
• /
• 2000

자원 예약을 보장하지 못하는 네트워크 상에서 실시간 멀티미디어 응용의 만족스러운 서비스를 위해서는 효과적인 종단 시스템의 운영이 필요하다. 이러한 운영 기술 중 버퍼를 이용한 응용 프로그램 수준의 대역폭 평활화 기술과 태스크 스케줄링 기법은 핵심적인 부분을 차지한다. 기존에 제안된 온라인 대역폭 평활화 기법은 동적 슬라이딩 윈도우와 공적 버퍼를 이용하여 네트워크에 적응할 뿐만 아니라 요구 대역폭 평활화를 통해 지터를 흡수, 완충시킴으로써 더 나은 서비스 품질을 보장한다. 그러나 응용 프로그램 수준에서 동작하기 때문에 프로그램의 수행 품질보장을 위한 시간 대역을 보장하지 못할 뿐만 아니라 지터의 발생 가능성이 높다. 본 연구에서는 효과적인 버퍼 관리를 통해 서비스 품질의 손실을 최소화하는 적응성 있는 온라인 대역폭 평활화 기법이 안정적으로 동작하기 위한 최적화된 태스크 스케줄링 기법을 제안한다. 먼저 태스크 스케줄링 기법은 멀티미디어 데이터의 생산과 소비를 적시에 보장할 수 있도록 하여 지터의 발생을 최소화하고, 만일 네트워크 지터가 발생하더라도 응용 프로그램 수준의 버퍼 관리를 통해 완충시킴으로서 서비스 품질의 손실을 최소화한다. 모의 실험에서는 제안된 기법이 온라인 대역폭 평활화 기법을 효과적으로 지원함을 보인다.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.57 no.2
• /
• pp.202-208
• /
• 2008

Condition monitoring technologies allow achieving this goal by minimizing downtime through the integrated planning and scheduling of repairs indicated by condition monitoring techniques. Thermal runaways induced by conduction problems deteriorate insulating material and cause disruptive dielectric discharges resulting in arcing faults. Therefore, having the ability to directly measure the temperature of the contacts while in service will provide more information to determine the true condition of the equipment. It allows connective measures to be taken to prevent upcoming failure. Continuous temperature monitoring and event recording provides information on the energized equipment's response to normal and emergency conditions. On-line temperature monitoring helps to coordinate equipment specifications and ratings, determine the real limits of the monitored equipment and optimize facility operations. Using wireless technique eliminates any need for special cables and wires with lower installation costs if compared to other types of online condition monitoring equipment. In addition, wireless temperature monitoring works well under difficult conditions in strategically important locations. Wireless technology for on -line condition monitoring of energized equipment is applicable both as stand alone system and with an interface for power quality monitoring system. The paper presents the results of wireless temperature monitoring: of electrical equipment at a power plant.

• Corrosion Science and Technology
• /
• v.23 no.2
• /
• pp.83-92
• /
• 2024

A hot-dip simulator was utilized to replicate abnormal coating buildup observed during line stops at galvanize lines, assessing the influence of processing conditions on buildup (up to 14 mm/side). Steel samples from 19 coils (comprising IF, BH, LCAK, HSLA, DP600-DP1180, Si: 0.006 - 0.8 wt%, P: 0.009 - 0.045 wt%) were examined to explore the phenomenon of heavy coating growth. It was discovered that heavy coating buildup (~3 mm/h) and rapid strip dissolution (~0.17 mm/h) in a GA or GI pot can manifest with specific combinations of steel chemistry and processing conditions. The results reveal the formation of a unique coating microstructure, characterized by a blend of bulky Zeta crystals and free Zn pockets/networks due to the "Sandlin" growth mechanism. Key variables contributing to abnormal coating growth include steel Si content, anneal temperature, dew point in heating and soaking furnaces, Zn pot temperature, Zn bath Al%, and cold-rolling reduction%. At ArcelorMittal Dofasco galvanize lines, an automatic online warning system for operators and special scheduling for incoming Si-bearing steels have been implemented, effectively preventing further heavy buildup occurrences.

• Journal of The Korean Association For Science Education
• /
• v.39 no.5
• /
• pp.669-679
• /
• 2019

In this study, we investigated how 'Scientific Inquiry Experiment,' a newly introduced subject under the 2015 revised curriculum, was implemented to identify the difficulties that science teachers face in the process of teaching the subject and to explore how to support them through online survey and interview methods. A questionnaire of the survey, which consisted of environmental factors of class, preparation and execution of class, teacher self-evaluation of class, and direction for the subject, was developed, and the online survey was requested with a response from one teacher per school from 1674 high schools nationwide. We analyzed the results from 814 teachers who answered all required questions, and we also conducted interviews and online advisory discussions to ensure the validity of our analysis. In the results of the study, teachers complained of lack of time for preparation and execution of the subject, and they demanded laboratory assistants and quality teaching materials. In addition, in order to achieve the goal of the subject, they agreed the necessity of using the 'block scheduling' though they also agreed the difficulties of its implementation. Meanwhile, the alteration of guidelines for evaluation, which was changed from 9-grade system to 3-grade system, was positively recognized by teachers. As a result of this change, the percentage of performance assessment increased in 2019 compared to 2018, but there were no significant changes in the number of 'hands-on activity.' Finally, we proposed ways to support 'scientific inquiry experiment'.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.3
• /
• pp.499-510
• /
• 2012

An SNS(Social Network Service) is an online service that supports an effective way to share information over virtual communities. Recently, as SNSs such as Twitter, Facebook, and Me2day are getting bigger, the purposes of using popular SNSs are expanded to broadcastings, politics, marketings and so on. In this paper, we propose an API to integrate and manage open APIs for various SNSs, presenting a library as an implementation of the proposed API. Also, utilizing the developed library, a smartphone application is provided which supports integrated management of popular SNSs and personal schedules. Using the library, developers can reduce costs when they need to implement specific functions for managing various SNSs. With the developed application, we can read and write to/from the related SNSs on same screen, automatically reminding our schedule and sharing the schedule with friends over the SNSs.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.41 no.4
• /
• pp.138-145
• /
• 2018

In the field of optimization, many studies have been performed on various types of Vehicle Routing Problem (VRP) for a long time. A variety of models have been derived to extend the basic VRP model, to consider multiple truck terminal, multiple pickup and delivery, and time windows characteristics. A lot of research has been performed to find better solutions in a reasonable time for these models with heuristic approaches. In this paper, by considering realtime traffic characteristics in Map Navigation environment, we proposed a method to manage realistic optimal path allocation for the logistics trucks and cargoes, which are dispersed, in order to realize the realistic cargo mixing allowance and time constraint enforcement which were required as the most important points for an online logistics brokerage service company. Then we developed a prototype system that can support above functionality together with delivery status monitoring on Map Navigation environment. First, through Map Navigation system, we derived information such as navigation-based travel time required for logistics allocation scheduling based on multiple terminal multiple pickup and delivery models with time constraints. Especially, the travel time can be actually obtained by using the Map Navigation system by reflecting the road situation and traffic. Second, we made a mathematical model for optimal path allocation using the derived information, and solved it using an optimization solver. Third, we constructed the prototype system to provide the proposed method together with realtime logistics monitoring by arranging the allocation results in the Map Navigation environment.

• The Journal of the Korea Contents Association
• /
• v.19 no.5
• /
• pp.187-193
• /
• 2019

Key-value storage engines are an essential component of growing demand in many computing environments, including social networks, online e-commerce, and cloud services. Recent key-value storage engines offer many features such as transaction, versioning, and replication. In a key-value storage engine, transaction processing provides atomicity through Write-Ahead-Logging (WAL), and a synchronous commit method for transaction processing flushes log data before the transaction completes. According to our observation, flushing log data to persistent storage is a performance bottleneck for key-value storage engines due to the significant overhead of fsync() calls despite the various optimizations of existing systems. In this article, we propose a group synchronization method to improve the performance of the key-value storage engine. We also design and implement a transaction scheduling method to perform other transactions while the system processes fsync() calls. The proposed method is an efficient way to reduce the number of frequent fsync() calls in the synchronous commit while supporting the same level of transaction provided by the existing system. We implement our scheme on the WiredTiger storage engine and our experimental results show that the proposed system improves the performance of key-value workloads over existing systems.