• Food Science of Animal Resources
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• v.39 no.2
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• pp.222-228
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• 2019

This research was motivated by our encounter with the situation where an optimization was done based on statistically non-significant models having poor fits. Such a situation took place in a research to optimize manufacturing conditions for improving storage stability of coffee-supplemented milk beverage by using response surface methodology, where two responses are $Y_1$=particle size and $Y_2$=zeta-potential, two factors are $F_1$=speed of primary homogenization (rpm) and $F_2$=concentration of emulsifier (%), and the optimization objective is to simultaneously minimize $Y_1$ and maximize $Y_2$. For response surface analysis, practically, the second-order polynomial model is almost solely used. But, there exists the cases in which the second-order model fails to provide a good fit, to which remedies are seldom known to researchers. Thus, as an alternative to a failed second-order model, we present the heterogeneous third-order model, which can be used when the experimental plan is a two-factor central composite design having -1, 0, and 1 as the coded levels of factors. And, for multi-response optimization, we suggest a modified desirability function technique. Using these two methods, we have obtained statistical models with improved fits and multi-response optimization results with the predictions better than those in the previous research. Our predicted optimum combination of conditions is ($F_1$, $F_2$)=(5,000, 0.295), which is different from the previous combination. This research is expected to help improve the quality of response surface analysis in experimental sciences including food science of animal resources.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.2
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• pp.147-155
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• 2021

Objective: The purpose of this study was to find ways for strengthening occupational health services through monitoring exposure to health hazards. Methods: About 70,000 workplaces that have conducted the work environment measurement(WEM) over the last three years(2017~2019) were classified according to the Korean Standard Industry Classification(KSIC), and the current status of WEM by industry was analyzed. The authors considered ways to monitor exposure to health hazards in order to strengthen occupational health services and protect workers' health. Results: Based on the KSIC, 934 of the 1,196 total sub-classified industries have conducted WEM in at least one workplace over the last three year(2017~2019). In the case of manufacturing, out of a total of 477 sub-classified industries, 474 have conducted WEM at more than one workplace. However, in some industries, WEM was not conducted or the implementation rate was low, so it was necessary to examine whether WEM should be expanded based on a detailed analysis of the WEM database. To this end, it is necessary to form an exposure monitoring committee in which various experts from different fields can participate. The committee needs to discuss the overall matters necessary for selecting industries that require detailed investigation or research, review the results, and prepare a final recommendation. Conclusion: In conclusion, the government needs to come up with a plan to strengthen occupational health services through surveys and research on the current status of WEM and work environment management models by industry.

• Journal of Platform Technology
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• v.8 no.2
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• pp.22-31
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• 2020

The construction and operation of industrial automation has been actively taking place from manufacturing plan to production for improving operational efficiency of production line and flexibility of equipment. ISO/TC184 is standardizing on operating methods that can share information of programmable device controllers such as PLC and IoT that are geographically distributed in the production line. In this study, the design of the cell controller consists of PLC group and IoT group that perform signals such as temperature sensors, gas sensors, and pressure sensors for thermal processes and corresponding motors or valves. The operation and analysis of the cell controller were performed using SDN(Software Defined Network) and the three types of process services performed in thermal processes are real-time transmission service, loss-sensitive large-capacity transmission service, and normal transmission service. The simulation result showed that the average loss rate improved by about 17% when the traffic increased before and after the application of the SDN route technique, and the delay in the real-time service was as low as 1 ms.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.1
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• pp.26-36
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• 2021

The topic of this study is the field of humanitarian logistics for disaster response. Many existing studies have revealed that compliance with the golden time in response to a disaster determines the success or failure of relief activities, and logistics costs account for 80% of the disaster response cost. Besides, the agility, responsiveness, and effectiveness of the humanitarian logistics system are emphasized in consideration of the disaster situation's characteristics, such as the urgency of life-saving and rapid environmental changes. In other words, they emphasize the importance of logistics activities in disaster response, which includes the effective and efficient distribution of relief supplies. This study proposes a mathematical model for establishing a transport plan to distribute relief supplies in a disaster situation. To determine vehicles' route and the amount of relief for cities suffering a disaster, it mainly considers the urgency, effectiveness (restoration rate), and uncertainty in the logistics system. The model is initially developed as a mixed-integer nonlinear programming (MINLP) model containing some nonlinear functions and transform into a Mixed-integer linear programming (MILP) model using a logarithmic transformation and piecewise linear approximation method. Furthermore, a minimax problem is suggested to search for breakpoints and slopes to define a piecewise linear function that minimizes the linear approximation error. A numerical experiment is performed to verify the MILP model, and linear approximation error is also analyzed in the experiment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.128-135
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• 2021

WDM(Wavelength Division Multiplexing) is called a wavelength division multiplexing optical transmission method and is a next-generation optical transmission technology. Case company F has recently developed and sold PLC(Planar Lightwave Circuit), a key element necessary for WDM system production. Although Chinese processing companies are being used as a global outsourcing strategy to increase price competitiveness by lowering manufacturing unit prices, the average defect rate of products manufactured by Chinese processing companies is more than 50%, causing many problems. However, Chinese processing companies are trying to avoid responsibility, saying that the cause of the defect is the defective PLC Wafer provided by Company F. Therefore, in this study, the responsibility of the PLC defect is clearly identified through estimating the defect rate of PLC using the sampling inspection method, and the improvement plan for each cause of the PLC defect for PLC yeild improvement is proposed. The result of this research will greatly contribute to eliminating the controversy over providing the cause of defects between global outsourcing companies and the head office. In addition, it is expected to form a partnership with Company F and a Chinese processing company, which will serve as a cornerstone for successful global outsourcing. In the future, it is necessary to increase the reliability of the PLC yield calculation by extracting more precisely the number of defects.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.1
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• pp.100-109
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• 2022

Installation of dental implants at optimal angles and positions is critical in long-term stable implant-supported restorations. Surgery and prosthodontic procedures should be performed accurately as the treatment is planned. In this clinical case, Computer aided design and manufacturing technology was used not only to establish a precise surgical plan, but also to fabricate both provisional and definitive fixed prostheses. A surgical guide was designed to install the implants at proper positions for the definitive prostheses. The patient's esthetic information, which was necessary for the new provisional and definitive fixed prostheses, was obtained from the existing temporary dentures. Finally, the complete mouth fixed implant-supported rehabilitation using monolithic zirconia provided the patient with functionally and esthetically satisfactory prostheses.

• Journal of Advanced Navigation Technology
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• v.26 no.5
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• pp.358-364
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• 2022

The Inter Communication System for avionics is in charge of processing all voice signals that internal calls between Pilot and Co-pilot, internal calls between Pilots and Crews, external calls through communication equipment such as Ultra/Very High Frequency Receiver/Transmitter(U/VHF RT), audio signal monitoring for navigation and mission equipment such as VHF Omnidirectional Range/Instrument Landing System(VOR/ILS), Tactical Air Navigation(TACAN), audio signal output for voice recording to Flight Data Recorder(FDR) and Data Transfer System(DTS), and warning/caution audio signal generate about the status and threat of aircraft. Because Inter Communication System for avionics is sensitive to noise in the case of analog audio signals, a redundant design that can protect audio signal from electromagnetic noise inside/outside of aircraft is required for the mission of pilots and crews. In this paper, Normal/Back-up operation mode and redundancy design plan based on digital method for the redundancy of the digital Inter Communication System for avionics and manufacturing, verification results are described.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.409-416
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• 2009

This paper presents a tool called Quality-Cost optimization system (QCOS), which integrates Multi-Objective Genetic Algorithm (MOGA) and Quality Function Deployment (QFD), for tradeoff between quality and cost of the unitized metal curtain-wall unit. A construction owner as the external customer pursues to maximize the quality of the curtain-wall unit. However, the contractor as the internal customer pursues to minimize the cost involved in designing, manufacturing and installing the curtain-wall unit. It is crucial for project manager to find the tradeoff point which satisfies the conflicting interests pursued by the both parties. The system would be beneficial to establish a quality plan satisfying the both parties. Survey questionnaires were administered to the construction owner who has an experience of curtain-wall project, the architects who are the independent assessor, and the contractors who were involved in curtain-wall design and installation. The Customer Requirements (CRs) and their importance weights, the relationship between CRs and Technical Attributes (TAs) consisting of a curtain-wall unit, and the cost ratios of each components consisting curtain-wall unit are obtained from the three groups mentioned previously. The data obtained from the surveys were used as the QFD input to compute the Owner Satisfaction (OS) and Contractor Satisfaction (CS). MOGA is applied to optimize resource allocation under limited budget when multi-objectives, OS and CS, are pursued at the same time. The deterministic multi-objective optimization method using MOGA and QFD is extended to stochastic model to better deal with the uncertainties of QFD input and the variability of QFD output. A case study demonstrates the system and verifies the system conformance.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.3
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• pp.1-10
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• 1986

Nowadays, air pollution by increasing consumption of fossil fuels resulting from rapidly growing population and industrialization has caused the adverse effects on terrestrial ecosystems and become one of the most serious problems causing environmental discriptions. Air pollution such as $SO_2, HF, NO_X,$ fly ash, ozone and PAN might influence plant growth, reproduction, nutrient cycling, photosynthesis and predisposition to entomological and pathological stresses on plants. Furthermore, accumulation of those toxic substances in forests might cause subtle or serious changes in the structure and function of forest ecosystems. Since 1970s, a number of large industrial complexes had been constructed as a part of industrialization plan in Korea. Accordingly, the forest exosystems around them has been under chronic influences of air pollution and effects of air pollution on plants became a matter of concern. In Yocheon Industrial Complex which consisted of lots of petrochemical plants and a phosphatic fertilizer manufacturing plant, forests has been exposed to chronic air pollution, mainly HF and $SO_2$ gas, Various reports were available to investigate the potential effects of air pollution on crops and forest trees in Yocheon. Kim and Kim surveyed vegetation by naked eye method and reported 71 families, 150 genera and 158 species were growing within a 2 km from air pollution sources in 1981. Needle injuries on Pinus spp. in the polluted area water reported by Kim, et al. and Kim, et al. Kim, et al. investigated the primary production of Pinus thunbergii forests in the polluted area and verified that growth inhibition of Pinus thunbergii was attributable to air pollution. Thus, previous reports suggested that forest ecosystems around Yocheon Industrial Complex were influenced adversely by air pollution. The objective of this study was to investigate the subtle ecological changes in forest community exposed to chronic air pollution in Yocheon.

• Journal of Korean Society for Quality Management
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• v.50 no.1
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• pp.153-167
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• 2022

Purpose: The purpose of this study is to guide the operation managers who plan daily production of large mass-processing facility that services multi-customers with multi-product, small-batch item characteristics by providing the practical best production quantity and the inventory allowed to build. Methods: Close observation of a subcontract paint-shop operator captured the daily decision process which was reflected in the subcontractor-unique mathematical model and the system dynamics simulation model. Multiple simulations were run to find the practical best production quantity and the maximum allowable stock level of inventory that did not undermine the profit from practical best daily production. Actual data and a few constant values were obtained from the firm under study. Results: While the inventory holding cost for the customer-owned material harms the total profit of the subcontractor, the running cost of the processing facility hinders production in small batches. This balances the maximum possible productions and results in practical best daily production which can be found through simulation runs with actual data. The maximum level of stocked inventory is deduced from the practical best daily production. Conclusion: To build a large volume that enables economy-of-scale production, operators should deal with multi-product small-batch items from multiple customers. When the planned schedule of the time and amount of material in-flow tend not to be reliable, operators can find it practical to execute level production across the planning horizon instead of adjusting to day-to-day in-flow fluctuations.