• Journal of Korea Multimedia Society
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• v.20 no.5
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• pp.800-807
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• 2017

The Pattern Sequence-based Forecasting (PSF) is an approach to forecast the behavior of time series based on similar pattern sequences. The innovation of PSF method is to convert the load time series into a label sequence by clustering technique in order to lighten computational burden. However, it brings about a new problem in determining the number of clusters and it is subject to insufficient similar days occasionally. In this paper we proposed an adaption of the PSF method, which introduces a new clustering index to determine the number of clusters and imposes a threshold to solve the problem caused by insufficient similar days. Our experiments showed that the proposed method reduced the mean absolute percentage error (MAPE) about 15%, compared to the PSF method.

• Industrial Engineering and Management Systems
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• v.10 no.2
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• pp.161-169
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• 2011

In seeking further efficiency in production preparation, it is common to examine assembly sequences using digital manufacturing. The assembly sequences affect the product evaluation, so it is necessary to test several assembly sequences before actual production. However, because selection and testing of assembly sequences depends on the operator's personal experience and intuition, only a small number of assembly sequences are actually tested. Nevertheless, there is a systematic method for generating assembly sequences using a contact-related figure. However, the larger the number of parts, the larger the number of assembly sequences geometric becomes. The purpose of this study is to establish a systematic method of generating efficient assembly sequences regardless of the number of parts. To generate such assembly sequences selectively, a "Tournament Tree," which shows the structure of an assembly sequence, is formulated. Applying the method to assembly sequences of a water valve, good assembly sequences with the same structure as the Tournament Tree are identified. The structure of such a Tournament Tree tends to have fewer steps than the others. As a test, the structure is then applied for a drum cartridge with 38 parts. In all the assembly sequences generated from the contact-related figures, the best assembly sequence is generated by using the Tournament Tree.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.727-734
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• 2004

Collision Management Protocol (CMP) efficiently resolves collisions when data frames are transmitted in networks consisting of HomPNA 3.0 asynchronous MAC mode device with random access. Unlike Distributed Fair Priority Queueing (DFPQ) algorithm in HomePNA 2.0 or Binary Exponential Backoff (BEB) algorithm in IEEE 802.11, order of retransmission is decided according to Collision Signaling Sequence (CSS) values allocated to each device. Thus, CMP can minimize the number of mean collisions because order of retransmission is decided in a deterministic way. In this paper. we evaluate the saturation performance of CMP in HomePNA 3.0 using an analytic method.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.10a
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• pp.157-160
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• 2000

This study is concerned with how to optimize the Input sequence of product models with sequence -dependent setup time in Mixed-Model Assembly Line (MMAL) using conveyor system. Usually MMAL consists of a number of stations linked by conveyor belt and each station has a work zone limited by upstream and downstream boundaries. To avoid improper interference between operators in the adjacent stations and excess of machine moving range, operators are forced to complete their operations within their predetermined work zone. In this study, our goal is to determine sequence of models for minimizing the total work unfinished within their work zone. A generalized formulation of the product sequencing problem in MMAL is presented and we developed an optimal procedure using Branch & Bound. Also we developed a heuristic procedure using local search.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.3
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• pp.47-57
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• 1992

The purpose of this paper is to improve the operation performance of unit-load Automated Guided Vehicles (AGV's) used as a carrier and mobile workstation in a flow-shop type flexible manufacturing system. An algorithm is developed to determine the optimal job sequence which minimizes the vehicle idle time on the line and the production makespan by the use of the entering interval and travel time between workcenters. An entering times of AGV's and the minimum number of AGV's required are calculated by optimal job sequence. When the numbe rof AGV's is limited, enterling times of AGV's are adjusted to maximize the efficient use of vehicles. A numerical example is given to illustrate the application of the algorithm.

• Journal of Korea Multimedia Society
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• v.21 no.8
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• pp.925-933
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• 2018

In this paper, we propose a new smart ordering application system for granting the customer numbers. The proposed system assigns sequence number of customers who visit at offline store as using speaker and microphone of smart device. This system has more advantage than the existing ordering system. Because the proposed system does not need any customer information like as phone number or SNS ID, it can protect customer privacy information. In this system, we use high frequency which is inaudible to the human ear as communication signal between speaker and microphone. To confirm performance evaluation, we perform a test with ten smart devices like as iPhone 6, 7, 8, Galaxy s8 and the result shown a success rate of 98.7 percent. Therefore, the proposed system can be useful service technology at the various offline store which need to assign a sequence number for customers, because many customers visit at the store.

• Ocean Systems Engineering
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• v.8 no.4
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• pp.409-426
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• 2018

This paper presents the strengthening of tubular joint by wrapping Carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP). In this study, total number of layers, stacking sequence and length of wrapping are the different parameters involved when fiber reinforced polymers (FRP) composites are used for strengthening. For this, parameters where varied and results were compared with the reference joint. The best stacking sequence was identified which has the highest value in ultimate load with lesser deflections. For determining the best stacking sequence, numerical investigation was performed on CFRP composites; length of wrapping and number of layers were fixed. Later, the studies were focused on CFRP and GFRP strengthened joint by varying the total number of layers and length of wrapping. An attempt was done to propose a parametric equation from multiple regression analysis, which can be used for CFRP strengthened joints. Hashin failure criteria was used to check the failure of composites. Results revealed that FRP was having a greater influence in the load bearing capacity of joints, and in reducing the deflections and stresses of joint under axial compressive loads. It was also seen that, CFRP was far better than GFRP in reducing the stresses and deflection.

• Journal of Platform Technology
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• v.6 no.1
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• pp.17-23
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• 2018

Taxi's queue for entering into taxi stand makes traffic jam and congestion around taxi stand. If we make that taxi waits in another place around taxi stand, and can approach to taxi stand when it gets in its turn, these traffic jam and congestion around taxi stand can be reduced. In this paper, we propose entry sequence operating system for taxi stand to reduce traffic jam and congestion around taxi stand. In this system, taxi driver can request his sequence number, and the system issues sequence number to driver. When it is time to approach to taxi stand due to issued sequence number, the proposed system notifies to taxi driver via taxi terminal. Taxi getting the proposed service can wait in another place around taxi stand, and can approach to taxi stand after receiving notify for approaching. Therefore, the proposed system in this paper can reduce traffic jam and congestion around taxi stand because it can reduce or get rid of taxi's queue around taxi stand. We implement the taxi stand approach sequence management system proposed in this paper for taxi stand installed in Chungju-Si, Chungbuk. We use Google Cloud service and Android platform for implementing.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.3
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• pp.83-91
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• 2014

We consider the problem of scheduling identical jobs with sequence-independent setup times on parallel machines. The objective is to minimize total completion times. We present the pseudopolynomial-time algorithm for the case with a fixed number of machines and an efficient approximation algorithm for our problem with identical setup times, which is known to be NP-hard even for the two-machine case.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.1
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• pp.49-64
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• 2003

Although assembly sequence planning is an essential task in assembly process planning, it is known as one of the most difficult and time consuming jobs because its complexity is increased geometrically when the number of parts in an assembly is increased. The purpose of this study is to develop a more efficient algorithm for generating assembly sequences automatically. By considering subassemblies, a new heuristic method generates a preferred parallel assembly sequence that can be used in robotic assembly systems. A parallel assembly sequence concept provides a new representation scheme for an assembly in which the assembly sequence precedence information is not required. After an user inputs both the directional mating relation information and the mating condition information, an assembly product is divided into subgroups if the product has cut-vertices. Then, a virtual disassembly process is executed to generate alternate parallel assembly sequences with intermediate assembly stability. Through searching parts relations in the virtual disassembly process, stable subassemblies are extracted from translation-free parts along disassembling directions and this extraction continues until no more subassemblies are existed. Also, the arithmetic mean parallelism formula as a preference criterion is adapted to select the best parallel assembly sequence among others. Finally a preferred parallel assembly sequence is converted to an assembly BOM structure. The results from this study can be utilized for developing CAAPP(Computer-Aided Assembly Process Planning) systems as an efficient assembly sequence planning algorithm.