• Industrial Engineering and Management Systems
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• v.14 no.2
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• pp.196-209
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• 2015

Retail sales forecast is a special area of forecasting. Its unique characteristics call for unique data models and treatment, and unique forecasting processes. In this paper, we will address lessons learned and challenges encountered in retail sales forecast from a practical and technical perspective. In particular, starting with the data models of retail sales data, we proceed to address issues existing in estimating and processing each component in the data model. We will discuss how to estimate the multi-seasonal cycles in retail sales data, and the limitations of the existing methodologies. In addition, we will talk about the distinction between business events and forecast events, the methodologies used in event detection and event effect estimation, and the difficulties in compound event detection and effect estimation. For each of the issues and challenges, we will present our solution strategy. Some of the solution strategies can be generalized and could be helpful in solving similar forecast problems in different areas.

• Proceedings of the Korea Society for Simulation Conference
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• 1992.10a
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• pp.5-5
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• 1992

The DEVS(discrete event system specification) formalism describes a discrete event system in a hierarchical, modular form. DEVSIM++ is C++ based general purpose DEVS abstract simulator which can simulate systems to be modeled by the DEVS formalism in a sequential environment. We implement P-DEVSIM++ which is a parallel version of DEVSIM++. In P-DEVSIM++, the external and internal event of models can be processed in parallel. To process in parallel, we introduce a hierarchical distributed simulation technique and some optimistic distributed simulation techniques. But in our algorithm, the rollback of a model is localized itself in contrast to the Time Warp approach. To evaluate its performance, we simulate a single bus multiprocessor architecture system with an external common memory. Simulation result shows that significant speedup is made possible with our algorithm in a parallel environment.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.6
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• pp.647-656
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• 2007

Simulation model of outdoor block movement of shipyard is implemented in this paper. The load of the outdoor workshops in a shipyard influences a mid-term planning and scheduling of the shipyard. Since the load analysis is expected in advance before confirming the planning and scheduling, a discrete event simulation (DES) may be a good solution. The accuracy of DES is up to the accurate modeling of Products, Processes, and Resources (PPR) included in a system. PPR in the outdoor system are clearly defined and the simulation model for the outdoor logistics is implemented by modeling the selective PPR with the help of a DES tool which is programmable by users. The simulation model is verified by comparing the results with the real shipyard data. The outputs through the simulation are discussed.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.3
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• pp.303-312
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• 2009

Recently, requests for the accurate process planning using modeling and simulation technique are increasing in many engineering fields including shipbuilding industry. In this study, Combined DEVS(Discrete EVent System specification) and DTSS(Discrete Time System Specification) simulation kernel is developed, and an integration strategy of dynamics simulation module and graphics module is also implemented. To evaluate the efficiency and applicability of the simulation kernel and integration strategy, these are applied to the block erection simulation of offshore structures.

• Communications for Statistical Applications and Methods
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• v.25 no.2
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• pp.131-157
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• 2018

We propose a robust event date model to estimate the date of a target event by a combination of individual dates obtained from archaeological artifacts assumed to be contemporaneous. These dates are affected by errors of different types: laboratory and calibration curve errors, irreducible errors related to contaminations, and taphonomic disturbances, hence the possible presence of outliers. Modeling based on a hierarchical Bayesian statistical approach provides a simple way to automatically penalize outlying data without having to remove them from the dataset. Prior information on individual irreducible errors is introduced using a uniform shrinkage density with minimal assumptions about Bayesian parameters. We show that the event date model is more robust than models implemented in BCal or OxCal, although it generally yields less precise credibility intervals. The model is extended in the case of stratigraphic sequences that involve several events with temporal order constraints (relative dating), or with duration, hiatus constraints. Calculations are based on Markov chain Monte Carlo (MCMC) numerical techniques and can be performed using ChronoModel software which is freeware, open source and cross-platform. Features of the software are presented in Vibet et al. (ChronoModel v1.5 user's manual, 2016). We finally compare our prior on event dates implemented in the ChronoModel with the prior in BCal and OxCal which involves supplementary parameters defined as boundaries to phases or sequences.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.11a
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• pp.71-74
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• 2007

오늘날 자연재해 발생 빈도수가 증가하고 있어 ESP(Energy Service Provider)와 대수용가에 서는 예기치 못한 정전 및 에너지 중단과 같은 이벤트가 발생하면 재산상의 손실과 같은 피해가 커지고 있다. 이에 에너지 포털 시스템에서 발생활 수 있는 다양한 이벤트들을 실시간으로 처리할 수 있는 효율적인 이벤트 모델링 개발이 필요하다. 그러나 현재 이러한 이벤트 처리를 위한 이벤트 모델링 개발은 거의 이루어지고 있지 않다. 이에 본 논문에서는 에너지 포털 시스템에서 발생하는 정전과 같은 이벤트와 원격 검침 둥과 같은 부가 서비스를 제공함에 따라 발생하는 이벤트들을 지능을 가진 실시간 에이전트를 사용하여 웹 환경에서 W3C 이벤트 처리 권고안인 DOM 모델을 기반으로 esXML(energy system eXtensible Markup Language)을 사용하여 효율적으로 처리할 수 있는 모델링을 개발하였다.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.882-885
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• 2003

In this paper, we describe a haptic jacket and wheel as a haptic interface to enhance VR game realism. Building upon the VR game system using this devices, our haptic interface technique allows the user to intuitive interact on game contents, and then to sense the game event properties such as walking, attacking, driving and fire in a natural way. In addition, we extended the initial haptic model to support haptic decoration and dynamic interactions due to the added game event in a real time display. An application example presented here is a VR Dino-Attack game. This game supports interactions among dynamic and our intuitive haptic interface. Modeling physic interactions involves precise collision detection, real-time force computation, and high control-loop bandwidth.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1564-1569
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• 1991

In this paper we describe Flexible Manufacturing Systems (FMS) using Petri nets, since Petri nets provide a powerful tool for modeling dynamical behavior of discrete concurrent processes. We deal with off-Line and on-Line rule-based scheduling of FMS. The role of the rule-base is to generate appropriate priority rule for resolving conflicts, that is, for selecting one of enabled transitions to be fired in a conflict set of the Petri nets. This corresponds to select a part type to be processed in the FMS. Towards developing more Intelligent Manufacturing Systems (IMS) we propose a conceptual framework of a futuristic intelligent scheduling system.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.10a
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• pp.161-164
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• 2000

A cyclic shop is a production system that repeatedly produces identical sets of jobs, called minimal part sets, in the same loading and processing sequence. We consider a version of cyclic shop where the operations are processed and unloaded within time limits, so called a time window. We model the shop using an event graph model, a class of Petri nets. To represent the time window constraint, we introduce places with negative time delays. From the shop modeling graph, we develop a linear system model based on the max- plus algebra and characterize the conditions on the existence of a stable schedule.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.1
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• pp.78-85
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• 2007

A gun is still one of the major weapons of a combat ship. To assess the ship's fire control capability which is influenced by tracking system, fire control algorithm, gun, the ship itself, target behavior, environment and engagement situation, simulation system for gun-oriented engagement for surface ship is needed. This paper proposes the process for designing and implementing a gun-oriented engagement simulation system using DEVS(Discrete Event Simulation Specification), which is a formalism based on the set theory. It consists of the following activities : 1) analyzing the characteristics of a gun-oriented engagement, 2) constructing the deterministic model of the combat ship of study with DEVS, 3) modeling properties of each entity showing as stochastic errors. With this process, the gun-oriented engagement simulation system is developed and applied for the combat system under development.