• Smart Structures and Systems
• /
• v.31 no.1
• /
• pp.45-56
• /
• 2023

Vibration-based structural health monitoring is used to ensure the safety of structures by installing sensors in structures. The peak picking method, one of the applications of vibration-based structural health monitoring, is a method that analyze the dynamic characteristics of a structure using the peaks of the frequency response function. However, the results may vary depending on the person predicting the peak point; further, the method does not predict the exact peak point in the presence of noise. To overcome the limitations of the existing peak picking methods, this study proposes a new method to automate the modal analysis process by utilizing long short-term memory, a type of recurrent neural network. The method proposed in this study uses the time series data of the frequency response function directly as the input of the LSTM network. In addition, the proposed method improved the accuracy by using the phase as well as amplitude information of the frequency response function. Simulation experiments and lab-scale model experiments are performed to verify the performance of the LSTM network developed in this study. The result reported a modal assurance criterion of 0.8107, and it is expected that the dynamic characteristics of a civil structure can be predicted with high accuracy using data without experts.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.36 no.3
• /
• pp.118-125
• /
• 2013

This paper deals with the picking batch size which a bi-directional carousel system can be feasible. The items that customers order are retrieved from the bins of carousel with batch size. The mathematical equations representing rotary travel distance and retrieval lead time to pick a given batch size are derived. Rotary travel distance represents the distance which carousel system rotates to retrieve items in a batch. The bi-directional carousel system rotates to minimize the travel distance in retrieving the items in a batch. Rotary travel distance and retrieval lead time are analyzed for the batch size through the simulation approach. From the simulation, the retrieval batch size that carousel system can be feasible is obtained. A numerical example is shown to explain the solution procedure.

• IE interfaces
• /
• v.22 no.3
• /
• pp.234-242
• /
• 2009

It is most important for distribution center in retail business to delivery commodities in a timely manner. Accordingly, many companies try to make distribution center effective using the Warehouse Management System(WMS) integrated legacy system. Also, the Customer Relationship Management(CRM) is the most typical paradigm in management lately. Even though the WMS and CRM are independent system of each other, WMS, coupled with CRM makes customer satisfied more effectively. In this paper, we proposed the methodology for inventory location after analyzing and applying customer buying pattern data in the CRM through the MBA(Market Basket Analysis), which is part of data mining. We used an example modeling a real distribution center in retail through a 3D simulation tool and examined correlation between commodities using customer buying pattern. After that, we applied it to the inventory location system through the MBA in an example. Finally, we identified decrease in the time for picking, which is the majority of distribution center. Besides, we proposed a simulation methodology before applying new methodology. Consequently, it removes potential errors in advance and makes a optimized inventory location system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.6
• /
• pp.61-69
• /
• 2016

Since 2000, the market of convenient stores in Korea has developed rapidly due to the explosive growth in single households but it still consists mainly of manual work due to the nature of the domestic industry. Hence the explosive increase in demand in the market is mostly due to workers. Therefore, the research aimed at encouraging efficiency via automation, which is carried out in manufacturing, such as electronic, cars and so on, is inadequate. This study performed a feasibility analysis of investment for introducing an automated system on brand A, which is domestic famous convenience store company. Productivity growth according to the introduction of an automated guided vehicle and the cost-benefits was studied with using a simulation for the picking process, which is most personnel and time consuming. As a result, the simulation showed that the equipment AGV introduced for choosing the process has the effects of cost saving and increased time efficiency for performing manual labor. Furthermore, appropriate numbers of AGV were forecasted considering the capacity of the distribution Center in the brand A convenient store, which has been growing steadily. There are increasing numbers of worker labor costs in the distribution industry these days. Before building a large new automate center, it is expected to provide a good information to investors who are considering increasing productivity through partial automation of each of unit process to achieve some cost reduction.

• The Journal of Bigdata
• /
• v.6 no.2
• /
• pp.17-28
• /
• 2021

Current development of technologies related to 4^th industrial revolution and the pandemic of COVID-19 lead the rapid expansion of e-marketplace. The level of competition among several companies gets increased by introducing different strategies. To cope with the current change in the market and satisfy the customers who request the better delivery service, the new concept, fulfillment, has been introduced. It makes the leadtime of process from order picking to delivery reduced and the efficiency improved. Still, the efficiency of operation in fulfillment centers constrains the service level of the entire delivery process. In order to solve this problem, several different approaches for demand forecasting and coordinating supplies using Bigdata, IoT and AI, which there exists the trivial limitations. Because it requires the most lead time for operation and leads the inefficiency the process from picking to packing the ordered items, the logistics service providers should try to automate this procedure. In this research, it has been proposed to develop the efficient plans to automate the process to move the ordered items from the location where it stores to stage for packing using AGV and AMR. The efficiency of automated devices depends on the number of items and total number of devices based on the demand. Therefore, the result of simulation based on several different scenarios has been analyzed. From the result of simulation, it is possible to identify the several factors which should be concerned for introducing the automated devices in the fulfillment centers. Also, it can be referred to make the optimal decisions based on the efficiency metrics.

• Journal of the Korea Society for Simulation
• /
• v.22 no.4
• /
• pp.83-92
• /
• 2013

The demand of a camera-lens-module which is installed in mobile phone has been increased explosively as the increase of mobile phone market. Recently, two missions are given to the parts manufacturer of lens module, and they are how to keep the quality of injection moulding process as the increase of resolution, and how to decrease manufacturing cost. In this paper, a simulation study is introduced which is used for developing barrel and shield considering the double-cassette type of mould. At first, the simulation for injection process using Mold Flow$^{TM}$ is applied in the phase of mould design, and mechanical simulation using DPM Assembly$^{TM}$ is applied for collision detection between picking robot and mould. As a result, the productivity increased more than 300%.

• Korean Management Science Review
• /
• v.11 no.1
• /
• pp.39-50
• /
• 1994

Carousel systems can be classified into unidirectional and bidirectional carousel, depending on the hardware structure. Bidirectional carousels again can be classified into reversible and irreversible carousel, depending on whether the reversal of direction is allowed or not during the process of an order. In this study, single carousel served by one operator is considered. Analytical models for the rotation distance to process an order of size are developed for unidirectional and irreversible bidirectional cases. For reversible bidirectional and Nearest Neighbor Heuristic cases, simulation results of the average rotation distance are presented. Since the throughput capacity of carousel systems also depends upon the picking time of the operator; order size; and the rotation speed of carousel, the model considers the above three factors to express the throughput capacity of single carousel systems.

• Journal of Environmental Health Sciences
• /
• v.46 no.3
• /
• pp.245-255
• /
• 2020

Objective: The present study analyzed domestic and overseas academic journals to understand the research status and characteristics of radon concentration distribution in Korea in accordance with environmental conditions. Methods: As part of the meta-analysis, pooled average concentration was calculated using an inverse variance-weighted average of the arithmetic means and standard deviations among the investigated values. Using the obtained pooled average concentration, a Monte-Carlo simulation was performed to increase the reliability of the occurrence possibility of the calculated concentration distribution. A total of 38 research articles were selected, including 27 articles published in domestic academic journals and 11 articles published in foreign academic journals. Results: The comparison results showed differences in radon concentration distribution in accordance with regional and topographical characteristics. Conclusion: Currently, even though research into radon is steadily picking up the pace in Korea much remains to be done. Additional research is thus needed to establish a baseline for radon emissions in Korea.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.12 s.177
• /
• pp.108-116
• /
• 2005

Transplanting accuracy of a rice transplanter mainly depends on the trajectory of the hoe for picking, conveying and transplanting of seedlings as well as the return motion. The trajectory can be decided and prescribed to be suitable in treating seedlings fur a prevailing soil condition. For the purpose of the transplanting accuracy, the design of a transplanting mechanism would be carried out using a planetary-gear-train system instead of the four bar linkage system. In this study, a design method of transplanting mechanism is theoretically proposed by synthesizing a noncircular planetary-gear-train system fur the tool (hoe) to trace a prescribed trajectory. The method utilizes an optimization approach to decide the lengths of an arm and a tool, the inverse kinematics to figure out the configuration angles of the two links, the roll contact condition in transmitting motion between the gears, and a linearization approach to obtain the shapes of the gears. Based on the proposed method, the shapes of the gears and the lengths of the tools of the planetary-gear-train system are determined fur three prescribed trajectories. A kinematical simulation with a commercialized package program is also carried out to confirm that the gear-train system synthesized with the proposed method is able to trace the prescribed trajectory.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.18 no.2
• /
• pp.206-211
• /
• 2008

Trainee can enhance his perception of and interaction with the real world by displayed virtual objects in simulation using image processing technology. Therefore, it is essential for realistic simulation to determine the occlusion areas of the virtual object produces after registering real image and virtual object exactly. In this paper, we proposed the new method to solve occlusions which happens during virtual target moves according to the simulated route on real image using improved object contour extraction by neighboring edge search and picking algorithm. After we acquire the detailed contour of complex objects by proposed contour extraction algorithm, we extract the three dimensional information of the position happening occlusion by using MER for performance improvement. In the experiment, we compared proposed method with existed method and preyed the effectiveness in the environment which a partial occlusions happens.