• Journal of the Korea Society for Simulation
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• v.8 no.4
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• pp.73-87
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• 1999

Order Review/Release (ORR) System is the linkage between planning system and actual production. Reduction of the waiting time on the machines, work in process and lead time variation may be achieved by adopting ORR strategies. But researchers on the ORR do not agree on the effectiveness of ORR. Some say that the overall system flow time may be increased if ORR is adopted, but others say that ORR can reduce work in process, flow time and variation of flow time. The objective of this research is to clarify under what environments order release strategy is effective. Simulation study was conducted in a hypothetical job shop. The experimental results show that dispatching rule is much more important than ORR is in controlling the shop floor. But the results indicate that ORR can reduce mean shop flow time, average work in process and variation of shop flow time under such environments where utilization level is high and planned order is weekly released to the order pool. And the results also show that the effect of plan smoothing on the ORR is insignificant, which is inconsistent with the results of the previous researches.

• Journal of KIBIM
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• v.6 no.3
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• pp.34-41
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• 2016

The previous studies argue that using the semantic properties of BIM objects is efficient for simulating the behaviors of autonomous, computer agents, called virtual-users, but such assumption is not proven via evidence-based research approaches. Hence, this present study aims to investigate the empirical effects of a human behavior simulation model equipped the semantics of spaces on the architecture-major students' operation and understanding of the simulation system, compared to a typical path-finding model. To achieve the aim, this study analyzed the survey and interview data, collected in the authentic design projects. The analysis indicates that (1) using a simulation model equipped the semantics of spaces helps the students' operation of the simulation, and (2) it also aids understanding the relationship between the variables of spaces and virtual-users (${\alpha}=0.74$). In addition, the qualitative data inform that the advantages of the simulation model that computes the semantics of spaces stem in the automatic behavioral changes of massive numbers of virtual-users, and efficient detection and activation on the what-if situations. The analysis also reveals that the simulation model has shortcomings in orchestrating the complex data structure between the semantics properties of spaces and virtual-users under multi-sequential scenarios. The results of this study contribute to develop a future design system combining BIM with human behavior simulation.

• The Journal of Industrial Distribution & Business
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• v.11 no.10
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• pp.7-16
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• 2020

Purpose: It suggests that making a policy and strategies in a way of AI and its impact of commercialization on economic efficiency, social custom ethics. Research design, data, and methodology: The paper has analyzed the data based on the proposed model when derived as AI vs. FI job, etc. It is very different for each professional evaluation, which is artificial intelligence or robot job. One concept case was selected as a substitute job, with a relatively low level of occupation ability, such as direct labors, easily replaced. By the induction data has resulted in modeling. Results: The paper suggests that AI at high level become something how to make real decisions on ethical value modeling. Through physical simulation with the deduction data, it can be tuned to design and control what has not been solved, from human senses to climate. Conclusion: For the exploiting of new AI decision-making jobs in markets, the deduction data is possible to prove to AI's Decision-making that the percentage who can easily have different leadership as is different for each person. what is generated by some information silos may be applied to occupation societies. The empirical results indicate the deduction data that if AI determines ethical decisions (VC) for that modifications, it may replace future jobs.

• Journal of the Korea Society of Computer and Information
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• v.23 no.8
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• pp.51-57
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• 2018

In this paper, we investigate the impact of channel estimation error on the D2D power control algorithm. In the previous work, D2D power control algorithm has been proposed under the assumption that the channel between the transmitter and the corresponding receiver is perfectly estimated. In reality, the channel estimation error is more often the case. The first question is that the power control algorithm designed for perfect channel estimation is still valid under the channel estimation error environment ? The second question is, if it is not valid, what could be the possible remedy for the channel estimation error ? In this paper, to answer the first question, we investigate the impact of the channel estimation error on the power control algorithm. We first review the D2D power control algorithm designed for perfect channel estimation. Then, we model the channel estimation error. Finally, we summarize the main results observed from the analysis of the simulation.

• Journal of Korean Society for Quality Management
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• v.27 no.2
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• pp.112-125
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• 1999

In a robust regression model, it is typically assumed that the errors are normally distributed. However, what if the error distribution is deviated from the normality and the response variables are not completely observable due to censoring? For complete data, Kim and Lai(1998) suggested a new adaptive M-estimator with an asymptotically efficient score function. The adaptive M-estimator is based on using B-splines to estimate the score function and simple cross validation to determine the knots of the B-splines, which are a modified version of Kun( 1992). We herein extend this method to right-censored data and study how well the adaptive M-estimator performs for various error distributions and censoring rates. Some impressive simulation results are shown.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.1
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• pp.58-61
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• 2003

A loop power system has a nonlinear characteristics. Also it is very hard to analyse through a equation if a discontinuous characteristic of the ULTC is added to a system. However, the problem which is hard to analyse by equations can acquire the useful result with what use the genetic algorithm (GA) which is a multi-point search program. In this paper, we proved through a simulation that the proposed method can reduce an operation frequency of tap changers and improving the quality of voltage of the buses by decreasing the deviation between the actual voltage and the reference voltage through the coordinated control of the ULTC that use GA in the loop power system.

• Communications for Statistical Applications and Methods
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• v.28 no.3
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• pp.307-314
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• 2021

We showed that any missing mechanism is reproduced by EMAR or MNAR with equal fit for observed likelihood if there are non-negative solutions of maximum likelihood equations. This is a generalization of Molenberghs et al. (2008) and Jeon et al. (2019). Nonetheless, as MCAR becomes a nested model of MNAR, a natural question is whether or not MNAR and MCAR are testable by using the well-known three statistics, LR (Likelihood ratio), Wald, and Score test statistics. Through simulation studies, we compared these three statistics. We investigated to what extent the boundary solution affect tesing MCAR against MNAR, which is the only testable pair of missing mechanisms based on observed likelihood. We showed that all three statistics are useful as long as the boundary proximity is far from 1.

• Journal of KIBIM
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• v.6 no.4
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• pp.27-34
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• 2016

A Building Information Model (BIM) is an attempt to simulate the process of building structures in a three-dimensional (3D) digital space. While the technology is usually applied to structured buildings, bridges, and underground facilities, it is rarely applied to an unstructured environment of earthwork operations. If a BIM is used for earthworks, the 3D simulation can be used for construction equipment guidance and earthwork management. This paper presents a real-time, 3D earthwork BIM that provides a 3D graphical simulation of excavators in conjunction with geographic modeling. Developing a real-time, 3D earthwork BIM requires handling a variety of factors, such as geographical information and vehicular movement. This paper mainly focuses on the management of these attributes and provides a database design for storing and retrieving data. In an example application, a prototype of the 3D earthwork BIM is presented to understand what it would provide when used during earthwork operations at a construction site.

• KIEAE Journal
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• v.17 no.4
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• pp.89-94
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• 2017

Purpose: Condensation in walk-in closets attached to apartment bathroom has been known as an emerging issue that may threat occupants' comfort and health. Despite a number of design guidelines and enforcements to prevent condensation, condensation issues may still occur depending on various cases and scenarios. We aim to identify what condensation scenarios may lead to walk-in closet condensation and/or worse the existing condensation issues. Method: First we choose an actual walk-in closet of an apartment that suffers from sporadic condensation and resulting mold and mildew. Then we observe its relative humidity and temperature after the bathroom is used, in which excessive vapor is thought to be transported to the walk-in closet. We analyze Temperature Difference Ratio - a domestic indicator of condensation occurrence, and dew point temperature to compare it with surface temperature using 2D heat transfer simulation upon various condensation scenarios. Result: TDR of the test walk-in closet turns out be OK despite mold and mildew actually occurring. Hot water pipe installed in the floor would greatly reduce condensation. If hot water pipe in the upper floor, however, is not used, or hot water pipe of the closet is turned off during swing seasons, it is expected that condensations may still occur.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.1
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• pp.117-129
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• 2009

The bullwhip effect is known as the significant factor which causes unnecessary inventory, lost sales or cost increase in supply chains. Therefore, the causes of the bullwhip effect must be examined and removed. In this paper, we develop two analytical tools for the bullwhip effect control in supply chains. First, we develop the quantitative models for computing the bullwhip effect in a three-stage supply chain consisted of a single retailer, a single distributor and a single manufacturer when the fixed-interval replenishment policy is applied at each stage. The quantitative models are developed under the different conditions for the demand forecasting and share of customer demand information. They are validated through the computational experiments. Second, we develop a simulation-based decision support system for the bullwhip effect control in a more diverse dynamic supply chain environment. The system includes a what-if analysis function to examine the effects of varying input parameters such as operating policies and costs on the bullwhip effect.