• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1066-1077
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• 2004

Dramatic increase in the number of Internet users want highly qualified service of continuous media contents on the web. To solve these problems, we present two network caching schemes(PPC, PPCwP) which consider the characteristics of continuous media objects and user access pattern in this paper. While there are plenty of reasons to create rich media contents, delivering this high bandwidth contents over the internet presents problems such as server overload, network congestion and client-perceived latency. PPC scheme periodically calculates the popularity of objects based on the playback quantity and determines the optimal size of the initial fraction of a continuous media object to be cached in proportion to the calculated popularity. PPCwP scheme calculates the expected popularity using the series information and prefetches the expected initial fraction of newly created continuous media objects. Under the PPCwP scheme, the initial client-perceived latency and the data transferred from a remote server can be reduced and limited cache storage space can be utilized efficiently. Trace-driven simulation have been performed to evaluate the presented caching schemes using the log-files of iMBC. Through these simulations, PPC and PPCwP outperforms LRU and LFU in terms of BHR and DSR.

• Journal of the Korea Society of Computer and Information
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• v.20 no.1
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• pp.153-161
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• 2015

In this paper, we propose a locomotor evaluation System for mouse based on continuous shooting images. In the field of veterinary medicine and animal studies are subjected to using the mouse for the quality of human life. In particular, during the experiments using the artificially created mice injury, through a variety of scoring and a lot of experiments to measure the extent of recovery from the injury. The traditional method of measuring the quantity of exercise while in this experiment was made of a method for directly observing person. The proposed system performs the continuous shooting per unit of time specified by the movement of the mouse is extracted from a continuous image shooting with the outline of a mouse point cloud. And using the extracted point cloud to extract again the inner contour of the body of the mouse. So using the new point cloud obtained its center, Then, using the center point calculated by accumulating the distance between two points on locomotor evaluation system design and implement to obtain the total distance the mouse moves over a unit of time.

• Journal of Dental Anesthesia and Pain Medicine
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• v.23 no.2
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• pp.91-99
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• 2023

Background: Extrusion of debris is a major factor that results in postoperative pain during root canal treatment with various instruments and instrumentation techniques. Therefore, instrumentation techniques that extrude minimal debris into the periapical area while reducing pain are desirable. This study aimed to compare the incidence of postoperative pain and intake of analgesic medication (frequency and quantity) after endodontic treatment of mandibular posterior teeth using two single files and full-sequence continuous rotary systems with different kinematic motions. Methods: Thirty-five of 105 patients were assigned equally to three groups according to the instrumentation system used: ProTaper Next (PN) X2, 25/06 (Dentsply, Maillefer, Ballaigues, Switzerland), One Shape (OS), #0.25/06 (Micro Mega, Besancon, France), and Wave One Gold (WG), Red - #0.25, 0.07 (Dentsply, Maillefer, Ballaigues, Switzerland). Five specialists were included in this study design; each professional prepared 21 teeth, and randomly selected 7 per instrument system. The VAS sheet ranging from 0 to 10 was used to record the initial and postoperative pains at 24, 48, and 72 h, and 7^th day after single visit endodontic treatment in mandibular premolars and molars with a diagnosis of asymptomatic irreversible pulpitis with or without apical periodontitis. Postoperatively, an analgesic, ibuprofen 400 mg was administered for intolerable pain at a dose of 1 tablet for 6 h. The patients were asked over the telephone regarding postoperative pain at intervals of 24, 48, and 72 h, and 7^th day using a visual analogue scale. Result: There were no statistically significant differences among the PN, OS, and WG systems (P > 0.05) with regard to the incidence of postoperative pain at any of the four time points assessed. Conclusion: The intensity of postoperative pain, frequency, and analgesic intake were similar across all three types of instrument systems; however, the reciprocating single file (WG) was associated with less postoperative pain than the full sequence continuous rotary file.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.10
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• pp.867-873
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• 2001

The purpose of this study is to find analytic solution of determining the optimal capacity (lot-size) of multiproduct acyclic multistage production and inventory system to meet the finished product demand under the constraint of finite intermediate storage. Intermediate storage is a practical way to mitigate the material flow imbalance through the line of supply and demand chain. However, the cost of constructing and operating storage facilities is becoming substantial because of increasing land value, environmental and safety concern. Therefore, reasonable decision-making about the capacity of processes and storage units is an important subject for industries. The industrial solution for this subject is to use the classical economic lot sizing method, EOQ/EPQ(Economic Order Quantity/Economic Production Quantity) model, incorporated with practical experience. But EOQ/EPQ model is not suitable for the chemical plant design with highly interlinked processes and storage units because it is developed based on single product and single stage. This study overcomes the limitation of the classical lot sizing method. The superstructure of the plant consists of the network of serially and/or parallelly interlinked non-continuous processes and storage units. The processes transform a set of feedstock materials into another set of products with constant conversion factors. A novel production and inventory analysis method, PSW(Periodic Square Wave) model, is applied to describe the detail material flows among equipments. The objective function of this study is minimizing the total cost composed of setup and inventory holding cost. The advantage of PSW model comes from the fact that the model provides a set of simple analytic solutions in spite of realistic description of the material flows between processes and storage units. the resulting simple analytic solution can greatly enhance the proper and quick investment decision for the preliminary plant design problem confronted with economic situation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.08a
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• pp.113-120
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• 2004

Considering the present and expected demand for human resources by the maritime community, its quantity and quality depend on the number of the ships and the technology applied to them. Scientific and economic developments in this community bring the intensive use of modem technology for many of ships operation. Generally it effects to reduce the quantity of manpower, while it increases the requirement of qualifications of human resources to utilize such advanced technology. Considering above, the maritime education, training and research activities should be revised and updated according to the demand of the community. Because of a difference between the transition of the demand for the human resources and development of the maritime education, training and research activities, there are two most common questions as “What to teach” and “How to teach”. The first question has been asked for many years. The contents of maritime education and training are always related to the existing maritime knowledge and technology and should be updated with consideration of changes of the demand namely “Globalisation of maritime community”. It brings globalisation of the maritime education, training and research activities. The second question is still keeping us busy to look for the best way. Presently traditional methods are used together with new system, while the use of sophisticated simulation, communication and information systems etc. and it is changing our understanding on teaching. This paper introduces the new role of Maritime Institutions from the viewpoints of the maritime education. training and research activities. The role of guide for seafarers and maritime companies is always essential and the concepts such as “Refreshment Training”, “On the Job Training”, “Lifelong” or “Continuous Training” bring new understanding to the training period, trainee's age and position. As a result, the maritime institutions should be ready for their new role, which is, in brief, guiding the maritime society, recommending and providing new learning environments, organising research and developments, performing the education, training and assessment, improving existing methods and developing new methods of the education, training and assessment.

• The Mathematical Education
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• v.45 no.3 s.114
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• pp.319-343
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• 2006

The purpose of this study is to investigate how fifth and sixth graders recognize average and to find out suggestions for teaching/learning methods of average by examining which difference there is depending on the way of the word problem presentation. For the this purpose, was conducted experiment study with the way of the world problem presentation set up as experimental treatment. The conclusions drawn from the results obtained in the this study were as follows : First, since students who did not learn the regular course of average had various informal concepts already, it is needed to consider handling more various concepts of average in order to enable students to expand flexible thoughts. Second, compared with fifth and sixth graders showed a wide difference in informal concepts of average depending on the way of the word problem presentation. In expect data with given average, concepts of mean as algorithm, balance point, and mode indicated similar percentage, while in estimate average with given data, the percentage of students who showed the concept of mean was very high at 67.6%. That may be because problems related to mean in the current textbooks are items of 'estimate average with given data', so in types of 'estimate average with given data', students solve questions with mean as algorithm without considering situations of problems. This result suggests that it is necessary to diversify the way of the word problem presentation even in textbooks. Third, as a result of analyzing informal concepts of average, there was significant difference in grades. In addition, the results suggested that there would be difference in the concepts of average depending on gender or attributes of discrete quantity and continuous quantity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7204-7210
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• 2015

This paper has developed the system for supporting the approximate construction cost and the quantity estimation based on 3D model information in the pre-project planning phase of 3-span continuous cable-bridge with 2-pylons. First of all, we'd analyzed the design information (structural design report, blueprint and quantity) of the existing cable-stayed bridges and derived the design variables of cable-stayed bridges. We developed the BIM wizard that generates a cable-stayed bridge model parametrically based on derived design variables. The principle material quantities of cable-stayed bridge are calculated directly from 3-dimensional bridge model built by using the BIM wizard. Then, we can estimate the construction cost in relation to its quantities and unit cost of cable-stayed bridge. In a result, we have established the system that the construction cost can be estimated more specific than the conventional method (construction estimates per meter or square meter). We hereby will be able to review various alternatives as soon as possible in bidding process.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.3
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• pp.95-100
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• 2020

Machines and facilities are physically or chemically degenerated by continuous usage. One of the results of this degeneration is the process mean shift. The representative type of the degeneration is wear of tool or machine. According to the increasing wear level, non-conforming products cost and quality loss cost are increasing simultaneously. Therefore a periodic preventive resetting the process is necessary. The total cost consists of three items: adjustment cost (or replacement cost), non-conforming cost due to product out of upper or lower limit specification, and quality loss cost due to difference from the process target value and the product characteristic value among the conforming products. In this case, the problem of determining the adjustment period or wear limit that minimizes the total cost is called the 'process mean shift' problem. It is assumed that both specifications are set and the wear level can be observed directly. In this study, we propose a new model integrating the quality loss cost, process variance, and production volume, which has been conducted in different fields in previous studies. In particular, for the change in production volume according to the increasing in wear level, we propose a generalized production quantity function g(w). This function can be applied to most processes and we fitted the g(w) to the model. The objective equation of this model is the total cost per unit wear, and the determining variables are the wear limit and initial process setting position that minimize the objective equation.

• Journal of the Korean Dietetic Association
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• v.10 no.1
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• pp.47-57
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• 2004

The sound dietary habit is formed in childhood, which is basic foundation for keeping health. The school foodservice is practiced to provide proper nutritions, to establish the sound dietary habit. Continuous evaluation and improvement are necessary to operate school foodservice effectively. This study was conducted to evaluate the quality of meals served in elementary school based on nutrient content, food diversity. A questionnaire was mailed to dietitian of each school requested for menus of one week. Menus served in 77 schools from each province and major cities in Korea were analyzed. The results of this study were summarized as follows; Compared to 1/3 of RDA for children, many schools provide lower amounts of energy, calcium and Vitamin A. Proportions of energy from carbohydrate, protein and fat were 59.64%, 17.43% and 20.11%, respectively and were not significantly different by the area, the foodservice system, and the number of persons served. NAR(nutrient adequacy ratio) were lowest for calcium(0.67) and Vitamin A(0.65). MAR(mean adequacy ratio) was 0.83. The results of comparison of NAR and MAR by the area, the foodservice system, and the number of persons served were similar to those of nutrient contents. Comparing foods served by the nutrient density were different by nutrient contents, NAR and MAR. Mean nutrient density per meal were higher in large cities than in small cities and rural area, in conventional than in commissary foodservice system. Mean number of dishes and food items per meal were 5.86 and 19.87, respectively. The mean of total quantity of each food group per meal was 352g. The mean of total quantity of each food group per meal were higher in small cities and rural area than in large cities, in commissary than in conventional foodservice system. This study is based only on served menus, and the evaluations of meals based on actual consumption of children are needed. These results suggest that in order to improve the quality of school food service, realistic standard should be suggested and basic study should be done continuously.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.59-69
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• 2018

This study deals with the case study on the pallet quantity determination problem for the flexible manufacturing system producing 32 different types of aircraft wing ribs which are major structures of an aircraft wings. A Korean company has constructed the WFMS (wing rib flexible manufacturing system) that is composed of several automated equipments such as the 5-axis machining centers, the RGV (rail guided vehicles)s, the AS/RS (automated storage and retrieval system), the loading/unloading stations, and so on. Pallets play a critical role in the WFMS to maintain high system utilization and continuous work flow between 5-axis machining machines and automated material handling devices. The discrete event simulation method is used to evaluate the performance of the WFMS under various pallet mix alternatives for wing rib manufacturing processes. Four performance measures including system utilization, throughput, lead-time and work in process inventory level are investigated to determine the best pallet mix alternative. The best pallet mix identified by the simulation study is adopted in setting up and operating a real Korean aircraft parts manufacturing shop. By comparing the real WFMS's performances with those of the simulation study, we discussed the cause of performance difference observed and the necessity of developing the CPS (cyber physical system).