• 산업경영시스템학회지
• /
• 제22권52호
• /
• pp.171-180
• /
• 1999

Industrial equipment reliability improvement and maintenance is gaining attention as the next great opportunity for manufacturing productivity improvement. Reactive maintenance is expensive because of extensive unplanned downtime and damage to machinery. To avoid such an unplanned machine downtime, it is needed to use proactive maintenance approach by either using historical maintenance data or by sensing machine conditions. This paper discusses failure diagonosis and prediction based on the condition-based maintenance and reliability technique. Thus, by enabling such a framework, it can bring us more efficient planning and execution of maintenance to reduce costs and/or increase profits.

• 산업경영시스템학회지
• /
• 제47권1호
• /
• pp.41-50
• /
• 2024

Korea is facing a significant problem with historically low fertility rates, which is becoming a major social issue affecting the economy, labor force, and national security. This study analyzes the factors contributing to the regional gap in fertility rates and derives policy implications. The government and local authorities are implementing a range of policies to address the issue of low fertility. To establish an effective strategy, it is essential to identify the primary factors that contribute to regional disparities. This study identifies these factors and explores policy implications through machine learning and explainable artificial intelligence. The study also examines the influence of media and public opinion on childbirth in Korea by incorporating news and online community sentiment, as well as sentiment fear indices, as independent variables. To establish the relationship between regional fertility rates and factors, the study employs four machine learning models: multiple linear regression, XGBoost, Random Forest, and Support Vector Regression. Support Vector Regression, XGBoost, and Random Forest significantly outperform linear regression, highlighting the importance of machine learning models in explaining non-linear relationships with numerous variables. A factor analysis using SHAP is then conducted. The unemployment rate, Regional Gross Domestic Product per Capita, Women's Participation in Economic Activities, Number of Crimes Committed, Average Age of First Marriage, and Private Education Expenses significantly impact regional fertility rates. However, the degree of impact of the factors affecting fertility may vary by region, suggesting the need for policies tailored to the characteristics of each region, not just an overall ranking of factors.

• 대한산업공학회지
• /
• 제21권3호
• /
• pp.329-343
• /
• 1995

Traditionally, machining process sequence was influenced and constrained by the design information obtained from CAD data base, i.e., class of operations, geometric shape, tooling, geometric tolerance, etc. However, even though all the constraints from design information are considered, there may exist more than one way to feasibly machine parts. This research is focused on the integrated problem of operations sequencing and machine tools selection in the presence of the product mix and their production volumes. With the transitional costs among machining operations, the operation sequencing problem can be formulated as a well-known Traveling Salesman Problem (TSP). The transitional cost between two operations is expressed as the sum of total machining time of the parts on a machine for the first operation and transportation time of the parts from the first machine to a machine for the second operation. Therefore, the operation sequencing problem formulated as TSP cannot be solved without transitional costs for all operation pairs. When solved separately or serially, their mutual optima cannot be guaranteed. Machining operations sequencing and machine tool selection problems are two core problems in process planning for discretely machined parts. In this paper, the interrelated two problems are integrated and analyzed, zero-one integer programming model for the integrated problem is formulated, and the solution methods are developed using a Tabu Search technique.

• 한국산학기술학회논문지
• /
• 제11권5호
• /
• pp.1601-1607
• /
• 2010

본 논문에서는 FMEA (Failure Mode Effect Analysis) 기법을 적용한 우편기계 유지보수 방법 제시하였다. 제안된 방법은 우편기계 모듈 및 부품에 대해 고장 유형을 정의하고, 고장 유형별 시스템에 주는 영향과 고장 빈도 및 검출도 등을 정의하여 고장 유형에 대한 시스템 위험도를 계산하여 그 값에 기반하여 점점 항목과 점검 주기를 조정하도록 하므로 시스템의 고장을 사전에 예방하고 시스템 가동율을 높이도록 하는 효율적인 유지보수 방법이다. 실제 현장에서 운영되고 있는 소형 통상 우편 구분 기계에 대해 제안된 방법의 적용 예를 보였다. 따라서 제안된 방법은 향후 국내 우편기계 유지보수에 적용시 유지보수 용이성과 효율성을 높일 것으로 기대한다.

• 한국경제지리학회지
• /
• 제13권2호
• /
• pp.196-218
• /
• 2010

본 연구는 광역적 산업클러스터의 관점에서 영남지역 기계금속산업클러스터의 형성과정과 연계 구조를 설명하고자 하였다. 그간의 국내외 연구들에서 광역적 산업클러스터에 대한 이론적, 경험적 연구가 미흡한 실정이었다면, 이론적인 분석과 함께 영남지역 기계금속산업클러스터를 대상으로 구체적인 사례연구를 시도한 것이다. 이를 위해 먼저 광역적 산업클러스터의 형성과정 및 구조에 관한 모델을 이론적으로 검토하였다. 광역적 산업클러스터의 형성과정은 외연확산형과 연계 심화형 그리고 복합형으로 구분될 수 있는 것으로 사료된다. 그리고 광역적 산업클러스터의 내부 구조는 다양하며, 흔히 광역클러스터와 그 하위에 존재하는 개별 산업클러스터가 중층적 (혹은 다층적) 구조를 형성하고 있는 것으로 분석되었다. 남지역에서 광역적 산업클러스터가 형성된 과정을 살펴보면 거시적 관점에서 개별 산업도시(산업클러스터)들이 점차 연계를 심화한 계심화형으로 분류할 수 있다. 그러나 부산이나 대구 대도시권에서 발생한 제조업 교외화 과정에서 산업클러스터의 외연 확산이 있었으며, 그러한 점에서 보다 엄격히 말한다면 연계심화형에 부분적으로 외연확산형이 혼합된 복합형이라고 할 것이다. 영남지역의 광역적 기계금속산업클러스터는 공간적 차원에서 중층적 구조를 가지고 있는 것으로 확인 되었다. 영남지역 대부분을 포함하는 광역 클러스터가 작동하는 한편으로, 그 하위에는 포항, 울산, 창원, 거제 등 개별 산업클러스터들이 독자적 단위로 존립하고 있는 것이다.

• 품질경영학회지
• /
• 제52권1호
• /
• pp.43-56
• /
• 2024

Purpose: The injection molding process, crucial for plastic shaping, encounters difficulties in sustaining product quality when replacing injection machines. Variations in machine types and outputs between different production lines or factories increase the risk of quality deterioration. In response, the study aims to develop a system that optimally adjusts conditions during the replacement of injection machines linked to molds. Methods: Utilizing a dataset of 12 injection process variables and 52 corresponding sensor variables, a predictive model is crafted using Decision Tree, Random Forest, and XGBoost. Model evaluation is conducted using an 80% training data and a 20% test data split. The dependent variable, classified into five characteristics based on temperature and pressure, guides the prediction model. Bayesian optimization, integrated into the selected model, determines optimal values for process variables during the replacement of injection machines. The iterative convergence of sensor prediction values to the optimum range is visually confirmed, aligning them with the target range. Experimental results validate the proposed approach. Results: Post-experiment analysis indicates the superiority of the XGBoost model across all five characteristics, achieving a combined high performance of 0.81 and a Mean Absolute Error (MAE) of 0.77. The study introduces a method for optimizing initial conditions in the injection process during machine replacement, utilizing Bayesian optimization. This streamlined approach reduces both time and costs, thereby enhancing process efficiency. Conclusion: This research contributes practical insights to the optimization literature, offering valuable guidance for industries seeking streamlined and cost-effective methods for machine replacement in injection molding.

• 산업경영시스템학회지
• /
• 제20권41호
• /
• pp.197-201
• /
• 1997

Presses are very used in industrial and commercial companies and are often the source of serious accidents occurring during operation. Most of accidents are due to inadequate design of the press machine. This paper presented an experiment which examined eye movement characteristics of the operators in the press operation. Continuous recordings of eye movements were made on five subjects in press operation. It was observed that the subjects stared longer at the die and did not stare at the switch. The eyemovemen patterns per cycle of the subjects were mostly identified as material container $\rightarrow$ die pattern type. The results could be used as basic data to establish a design guideline when manufacturer made the press machine.

• 대한산업공학회지
• /
• 제15권2호
• /
• pp.93-101
• /
• 1989

The classic machine repair problem is extended to the case where a number of different machines are arranged in the sequence of operation. The steady-state availability of the system with a series of operating machines is maximized under some constraints such as total cost, available space. In order to find the optimal numbers of spare units and repair channels for each operating machine, the problem is formulated as non-linear integer programming(NLIP) problem and an efficient algorithm, which is a natural extension of the new Lawler-Bell algorithm of Sasaki et al., is used to solve the NLIP problem. A numerical example is given to illustrate the algorithm.

• 산업경영시스템학회지
• /
• 제37권3호
• /
• pp.43-50
• /
• 2014

In this paper, we deal with a single machine scheduling problems integrating with step deterioration effect and a rate-modifying activity (RMA). The scheduling problem assumes that the machine may have a single RMA and each job has the processing time of a job with deterioration is a step function of the gap between recent RMA and starting time of the job and a deteriorating date that is individual to all jobs. Based on the two scheduling phenomena, we simultaneously determine the schedule of step deteriorating jobs and the position of the RMA to minimize the makespan. To solve the problem, we propose a hybrid typed genetic algorithm compared with conventional GAs.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.438-443
• /
• 2005

Handy paint rollers with simple or no patterns are generally used to transcribe its design to a wall just after painting. However, the types of the patterns are limited to several conventional ones, so that interior planners' or decorators' demands are gradually tending to getting attractive roller designs. In order to obtain abundant kinds of the roller designs, a new advanced 3D machining method should be established for cylindrical models. In this paper, a post-processor that can generate suitable NC data is proposed for multi-axis NC machine tools with a rotary unit. The 3D machining system with the post-processor is also presented for an attractive interior decorating. The machining system allows us to easily transcribe the relief designs from on a flat model to on a cylindrical model. The effectiveness of the proposed 3D machining system using the post-processor is demonstrated through some machining experiments.