• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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• pp.149-158
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• 2015

Up-to-date manufacturing companies have faced a market-driven environment of pull production order. There should be a difference in operating manufacturing resources according to the type, quantity, and delivery time of manufactured products, because the process situation in pull production is changed by customer orders. And it should be taken into account from the stage of preparing for production such as process design and the placement and utilization of manufacturing resources. However, the feasibility of production plans is limited because most of small manufacturing businesses make production/supply plan of the parts and products assuming that equipment abilities in scheduling is sufficient without managing process standard information systemically. In this study, a discrete event simulation system based on BOM (bill of material), that is F-OPIS (online productivity innovation system), is introduced and a case study on application of the system leading to improving productivities is presented. F-OPIS deals with a decision-problem on production management and it is specialized for small-and- medium sized manufacturing companies. The target company of this case study is a typical small-and-medium sized manufacturing company in Korea, that produces various machined parts. The target company adopts make-to-stock production management to prevent tardy delivery because of fluctuations in demand. Therefore, it is required to apply an efficient inventory control solution for improving productivities. In this paper, based on the constraints of working capacity of manufacturing resources, the bottleneck process is analyzed as production conditions are changed. Consequently, an improvement plan is proposed, that eventually enhances overall utilization rates of resources in the bottleneck process and reduces overall production lead-time and inventory level.

• Journal of Environmental Health Sciences
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• v.30 no.3
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• pp.293-299
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• 2004

Traffic represents one of the largest sources of primary air pollutants in urban area. As a consequence, numerous abatement strategies are being pursued to decrease the ambient concentration of pollutants. A characteristics of most of the these strategies is a requirement for accurate data on both the quantity and spatial distribution of emissions to air in the form of an atmospheric emission inventory database. In the case of traffic pollution, such an inventory must be compiled using activity statistics and emission factors for vehicle types. The majority of inventories are compiled using passive data from either surveys or transportation models and by their very nature tend to be out-of-date by the time they are compiled. The study of current trends is towards integrating urban traffic control systems and assessments of the environmental effects of motor vehicles. In this study, a model of vehicle emission calculation by using real-time traffic data was studied. Traffic data, which are required on a street-by-street basis, is obtained from induction loops of traffic control system. It is possible that characteristics of hourly air pollutants emission rates is obtained from hourly traffic volume and speed. An emission rates model is allocated with a high resolution space by using geographic information system (GIS). Vehicle emission model was developed with a high resolution spatial, gridded and hourly emission rates.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.5
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• pp.369-381
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• 2009

The objective of this study was to simulate surface air pollutants and to examine reliability of mobile emission for CMAQ system using an observation-based approach in the Seoul Metropolitan Area. Accurate assessment of emissions from mobile source is one of the most debatable parts in the entire emissions inventory process. For this study, we evaluated the official emission inventories of Volatile Organic Compounds (VOCs) and nitrogen oxides ($NO_x$) using an observation-based approach. In this paper, we achieved VOCs/CO and $NO_x$/CO ratios derived from ambient measurements taken from June to August of 2005 in early morning (07:00~08:00). And we compared them with those derived from the emission inventory. Based on these ratios and on the assumption that official inventory of CO emissions is reasonably accurate, mobile emissions of $NO_x$ seem to be slightly overestimated and VOCs emissions significantly underestimated. The results of simulations using modified emission of mobile source were in closer agreement with the observation results except NO. Predicted NO values based on revised $NO_x$ emissions were considerably lower than the observed values. Using modified emission inventories brings the modeled values into closer agreement with observed ozone levels in Seoul. Especially in case of CO, $NO_x$ and VOCs emission, the modified values were suitable for simulating ozone levels in Seoul and Gyeonggi. However, ozone values predicted using the modified emissions were higher than the observed and predicted values based on original emissions. According to the 95 percentile ozone concentrations, emission revised by CO, $NO_x$ and VOCs from mobile source was the best for predicting high concentration.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.147-152
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• 2008

The Climate Change Convention has a purpose for stabilizing the concentration of greenhouse gases of the atmosphere so that the dangerous and artificial effects may not influence atmosphere systems. We intend to present the model needed to establish the systems able to monitor and control in real time not sticking to places by grafting IPTV technique and setting the monitoring objects of the greenhouse emitting sources of industrial facilities, the estimation instruction of emissions, the guidelines of emission estimation, etc. in order to corresponding to this Climate Change Convention.

• Journal of Korean Society for Geospatial Information Science
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• v.6 no.1 s.11
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• pp.53-63
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• 1998

The purpose of this study is to investigate the current status of automatic measuring systems for air pollution emissions in Seoul and to suggest an improvement method using GIS and GPS. In Korea, there have been very few critical researches and managements for mobile and area sources regarding moving subjects such as automobiles. In order to control or to make a plan for reducing air pollutions, air pollution emission data based on tim and location, emission inventory systems and emission models should be implemented. Using digital maps and MS Visual Basic, we developed a visualized interface for air pollution emission data from automatic emission measurement systems in Seoul.

• Smart Media Journal
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• v.12 no.10
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• pp.85-92
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• 2023

In December 2014, Livestock and Livestock Products Traceability Act was established, allowing consumers to receive livestock traceability information. While the Livestock Traceability System provides consumers with transparent and fair information about their food, it has brought increased workload and penalty burdens to stakeholders in the livestock industry. In this paper, we propose an IoT system for inventory management based on traceability numbers to enable sellers to conveniently provide livestock traceability information to consumers. We analyzed the protocol for managing data from electronic scales and conducted functional testing and verification on mobile devices. Furthermore, we implemented the design and system functionality, taking into account UI/UX on Android OS-based devices to synchronize and interconnect traceability and product information with electronic scales. We anticipate that the proposed approach will minimize user inconvenience and raise production efficiency in the existing market.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1859-1864
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• 2004

An effective methodology is reported for the optimal design of multisite batch production/transportation and storage networks under uncertain demand forecasting. We assume that any given storage unit can store one material type which can be purchased from suppliers, internally produced, internally consumed, transported to or from other plant sites and/or sold to customers. We further assume that a storage unit is connected to all processing and transportation stages that consume/produce or move the material to which that storage unit is dedicated. Each processing stage transforms a set of feedstock materials or intermediates into a set of products with constant conversion factors. A batch transportation process can transfer one material or multiple materials at once between plant sites. The objective for optimization is to minimize the probability averaged total cost composed of raw material procurement, processing setup, transportation setup and inventory holding costs as well as the capital costs of processing stages and storage units. A novel production and inventory analysis formulation, the PSW(Periodic Square Wave) model, provides useful expressions for the upper/lower bounds and average level of the storage inventory. The expressions for the Kuhn-Tucker conditions of the optimization problem can be reduced to two sub-problems. The first yields analytical solutions for determining lot sizes while the second is a separable concave minimization network flow subproblem whose solution yields the average material flow rates through the networks for the given demand forecast scenario. The result of this study will contribute to the optimal design and operation of large-scale supply chain system.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.6
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• pp.788-793
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• 2012

This study was focused on the estimations of air pollutants, such as PM(Particulate matters), SOx(Sulfur Oxides), $CO_2$(Carbon diOxides) and NOx(Nitrogen Oxides), from a diesel propulsion engine installed on a naval vessel. Legislative and regulatory actions for exhaust emissions from ships are being strengthened in international communities and national governments to protect human health and the environment. In this context, various technologies have been developed from all of the nations of the world to meet strict standards. These regulations are based on commercial ship applications and according to size, but are not suitable for military naval vessels, which have much different engine operating conditions and hull architectures. Additionally, there is no international emission control system for military ships. Emission factors have been updated for commercial ship types from work at various research institutes; however, it is difficult to develop emission factors for military vessels because of their characteristics. In this paper, exhaust emissions from diesel engines installed on naval vessels under steady navigation condition were estimated with emission inventory methodology applied to ocean going vessels using fuel-based methods and fuel sulfur content analysis.

• Journal of the Korea Society for Simulation
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• v.22 no.1
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• pp.31-40
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• 2013

Recent development in science and technology has modernized the weapon systems of ROKN (Republic Of Korea Navy). Although the cost of purchasing, operating, and maintaining the cutting-edge weapon systems has been increased significantly, the national defense expenditure is under a tight budget constraint. In order to maintain the availability of ships with low cost, we need an efficient and scientific method for managing repairable parts. In this study, we propose a simulation model that computes the availability of ship's repairable parts. Our model is based on the METRIC (Multi Echelon Technique Repairable Item Control) model and extends to five sub-models to reflect the realistic situations that arise in the navy, such as planned maintenance, condemnation, lateral transshipment, and cannibalization. We have performed simulations to compute the availability of repairable parts while setting the part-level consistent throughout the five models and carried out two sensitivity analyses. The simulation results show the differences in the part availability in different models. The experiments confirm our claim that ROKN needs an inventory management system that captures the operational characteristics of the navy.

• Journal of Convergence for Information Technology
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• v.10 no.8
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• pp.187-193
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• 2020

This study analyzed how risk factors in management affect the management of working capital in general hospitals in Korea. The data used accounting information for three years (2016~2017 and 2018) of 271 general hospitals using the medical institution accounting information disclosure system. The independent variables were the working capital level and the cash conversion cycle, The dependent variables were operational risk and market risk, Control variables were selected as components of working capital(cash, accounts receivable, inventory assets, accounts payable). According to the study, the lower the operational risk, the higher the level of working capital hospitals in Korea. Working capital decisions were confirmed to be attributable to operating risks, cash, inventory assets and accounts payable. And the lower the market risk (Operating Margin), the higher the cash conversion cycle. Therefore, it is necessary to review appropriate management measures of operational risks, cash, inventory assets and accounts payable identified as operating capital determinants so that medical institutions can also have economic response capabilities in consideration of the specificity of their operations.