• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.4
• /
• pp.15-23
• /
• 1995

In this paper, we evaluate the performance of a transient queueing approximation when it is applied to modeling computer communication networks. An operational computer network that uses the ISO IS-IS(Intermediate System-Intermediate System) routing protocol is modeled as a Jackson network. The primary goal of the approximation pursued in the study was to provide transient queue statistics comparable in accuracy to the results from conventional Monte Carlo simulations. A closure approximation of the M/M/1 queueing system was extended to the general Jackson network in order to obtain transient queue statistics. The performance of the approximation was compared to a discrete event simulation under nonstationary conditions. The transient results from the two simulations are compared on the basis of queue size and computer execution time. Under nonstationary conditions, the approximations for the mean and variance of the number of packets in the queue erer fairly close to the simulation values. The approximation offered substantial speed improvements over the discrete event simulation. The closure approximation provided a good alternative Monte Carlo simulation of the computer networks.

• Journal of the Korea Safety Management & Science
• /
• v.16 no.3
• /
• pp.369-376
• /
• 2014

The national Logistics Information system has been rapidly developed on account of the dramatic improvements in the military's logistics support system and supply support system, making a transition from manual work system to computerized work system. Supply level, however, does not reflect these changes in the overall logistics environment and still retains the state it was in the 1970s. This research uses the accumulated data from the equipment maintenance information system developed in the year 2009 to analyze RWT(Requisition Wait Time) and CWT (Customer Wait Time). The analysis estimated the realistic transportation and ordering time and led to the conclusion that the differentiated ASL operation system that considers demand level should be adopted instead of the uniform ASL employment system.

• 한국초전도학회:학술대회논문집
• /
• v.10
• /
• pp.22-22
• /
• 2000

The discoveries of high temperature superconductors received great attention due to their high critical temperatures. These materials also exhibit extremely high critical magnetic fields and high critical current density at low temperature, high magnetic field. Thus, they are the most promising materials for superconducting magnets above 20 T. In this talk, progress in the development of HTS materials and insert coils at the National High Magnetic Field Laboratory will be reviewed. In 1999, a Bi-2212 stack of double pancakes generated 3 T in a 19 T background field. These results will be reviewed in terms of implications for future systems. Individual double pancakes of Bi-2223 have also been tested and their performance will also be discused. The present goal of a 57 system will be presented and the key technical requirements for larger, higher field systems will be addressed. It will be shown that in addition to increased critical current density, improved mechanical performance (stain resistanced) is necessary for high field systems. Furthemore, improvements in the conductor n-value will improve prospects for operational systems.

• Macromolecular Research
• /
• v.14 no.4
• /
• pp.473-477
• /
• 2006

The above described semi-transparent monochromators have been operational since 1997. Four units are permanently operating at the ESRF beam line ID14. Two units are in continuous operation at ID 10 and one unit is installed at the APS beamline 8-ID in USA. The water cooling of the crystals is currently being revised and above we showed that improvements most likely are possible by using micro fluidics techniques. Further tests will be performed in collaboration with the CEA-France and tested at ESRF. Parallel developments including nanofluids as coolants are under evaluation. Combination of nanofluidics and microfluidics cooling devices are under study. The authors are grateful to C. Gillot and J-A. Gruss for useful discussions and advices, and to S.Mcheik for his work on the thermal model.

• Proceedings of the Korea Society for Simulation Conference
• /
• 1999.10a
• /
• pp.217-217
• /
• 1999

The main objective of this study is to simulate the design and operational policies of the assembly shop of an automotive plant for planning purposes and to find possible improvements. The simulation study was used to answer the following questions: How does the sequence affect the daily throughput\ulcorner What are the bottlenecks to the assembly lines in a given scenario\ulcorner A Simulation model was developed in accordance with the objective of this study. The model incorporates detailed workstation logic to accurately model downtime results through the use of a pull cord system. It is written with SIMAN. The discrete event feature of SIMAN does not adequately model the conveyor systems of the asembly shop. As a result, a few subroutines were added to the SIMAN modeling structures to mimic the operations of the assembly shop. Use of the model uncovered attractive improvement opportunities, such as a tremendous gain in annual volume if four additional spaces were added to a between-line buffer.

• Journal of the Korea Safety Management & Science
• /
• v.17 no.2
• /
• pp.13-25
• /
• 2015

In recent years, the surroundings of Fire have rapidly changed and citizens need for Fire have been demanding very high. Under these situations, in order for satisfaction to all these demands, Seoul Emergency Operations Center have made improvements as the core fire operational center in Korea. However, There have been so many problems happening in the middle of receiving calls from malice citizens of Seoul. The purpose of this study is to scrutinize current operations focused on fire fighters in Seoul Emergency Operations Center and to cope with how to overcome these problem by using AMOS 21 & SPSS Statistics 21. The result of this study presents that how we can find to be Seoul Emergency Operations Center running well. And This study is applied to seoul fire policies or helped to setting them up.

• Journal of Engineering Education Research
• /
• v.23 no.5
• /
• pp.16-25
• /
• 2020

This article aims to analyze the experience of designing and operating a class model linking undergraduate and graduate students in engineering education and suggest its development direction. To achieve these objectives, the undergraduate-graduate linked class model was applied to community problem-solving education and a case was analyzed. It also specifically presented the process of how we design the class model and what the actual operational performances and improvements are. This study found that undergraduate and graduate students could build integrated and horizontal cooperative relationships in their classes through undergraduate-graduate linked education and, particularly, graduate students could gain meaningful educational experiences. However, it was difficult to obtain tangible performances through the team activities of these students within a semester. In order for engineering colleges to operate undergraduate-graduate linked education, it would be necessary to provide a longer and more systematic educational environment and better curriculum. The study tried to seek specific tasks and ways to improve them.

• Progress in Medical Physics
• /
• v.31 no.3
• /
• pp.71-80
• /
• 2020

This paper provides a brief review of the advanced technologies for carbon ion radiotherapy (CIRT), with a focus on current developments. Compared to photon beam therapy, treatment using heavy ions, especially a carbon beam, has potential advantages due to its physical and biological properties. Carbon ion beams with high linear energy transfer demonstrate high relative biological effectiveness in cell killing, particularly at the Bragg peak. With these unique properties, CIRT allows for accurate targeting and dose escalation for tumors with better sparing of adjacent normal tissues. Recently, the available CIRT technologies included fast pencil beam scanning, superconducting rotating gantry, respiratory motion management, and accurate beam modeling for the treatment planning system. These techniques provide precise treatment, operational efficiency, and patient comfort. Currently, there are 12 CIRT facilities worldwide; with technological improvements, they continue to grow in number. Ongoing technological developments include the use of multiple ion beams, effective beam delivery, accurate biological modeling, and downsizing the facility.

• Journal of KIISE:Software and Applications
• /
• v.36 no.9
• /
• pp.718-731
• /
• 2009

Software Maintenance needs to continually improve from corrective maintenance to operational management and service improvement. In this study, we propose a software maintenance maturity model and its evaluation criteria based on 4 maintenance projects of K organization. For the proposal, we derive 13 process areas and 64 evaluation criteria based on some references such as SMMM, ITSMM, ITIL. We evaluate the criteria using 5-point scale, and then establish the maturity model of K organization classified by levels of the maturity model based on the evaluation result. And, to verify and improve the maturity model of K organization, we propose improvements for evaluation criteria. In addition, we apply the maturity model to the 4 projects, evaluate the projects, and propose improvements for the projects based on the evaluation result to identify how the model shows software maintenance improvement.

• Journal of the Korean Society for information Management
• /
• v.33 no.1
• /
• pp.139-160
• /
• 2016

This study suggested improvements after analyzing the effectiveness of "A" university library. So, this study analyzed the effectiveness of E-group "A" university, and measured the effectiveness, classifying with three conditions about input & output and factors and conditions about regional categories. As a result, it is necessary to operate E-group 38 university libraries and "A" University library by increasing input factors to increase outputs. The improvements are as followings. First, it is necessary to stir up member's recognition on libraries. To this, there is a legal system for university library. Second, it is necessary to include library use education in curriculum. Third, it is necessary to prepare complex space so that the members can borrow books and use it for cultural space and rest space.