This study focuses on a job-shop scheduling problem with the objective of minimizing total tardiness for the job orders that have different due dates and different process flows. We suggest the dispatching rule based scheduling algorithm to generate fast and efficient schedule. First, we show the delay schedule can be optimal for total tardiness measure in some cases. Based on this observation, we expand search space for selecting the job operation to explore the delay schedules. That means, not only all job operations waiting for process but also job operations not arrived at the machine yet are considered to be scheduled when a machine is available and it is need decision for the next operation to be processed. Assuming each job operation is assigned to the available machine, the expected total tardiness is estimated, and the job operation with the minimum expected total tardiness is selected to be processed in the machine. If this job is being processed in the other machine, then machine should wait until the job arrives at the machine. Simulation experiments are carried out to test the suggested algorithm and compare with the results of other well-known dispatching rules such as EDD, ATC and COVERT, etc. Results show that the proposed algorithm, MET, works better in terms of total tardiness of orders than existing rules without increasing the number of tardy jobs.

As a system complexity increases and technology innovation progresses rapidly, leasing the equipment is considered as an important issue in many engineering areas. In practice, many engineering fields lease the equipment because it is an economical way to lease the equipment rather than to own the equipment. In addition, as the maintenance actions for the equipment are costly and need a specialist, the lessor is responsible for the maintenance actions in most leased contract. Hence, the lessor should establish the optimal maintenance strategy to minimize the maintenance cost. This paper proposes two periodic preventive maintenance policies for the leased equipment. The preventive maintenance action of policy 1 is performed with a periodic interval, in which their intervals are the same until the end of lease period. The other policy is to determine the periodic preventive maintenance interval minimizing total maintenance cost during the lease period. In addition, this paper presents two decision-making models to determine the preventive maintenance strategy for leased equipment based on the lessor’s preference between the maintenance cost and the reliability at the end of lease period. The structural properties of the proposed decision-making model are investigated and algorithms to search the optimal maintenance policy that are satisfied by the lessor are provided. A numerical example is provided to illustrate the proposed model. The results show that a maintenance policy minimizing the maintenance cost is selected as a reasonable decision as the lease term becomes shorter. Moreover, the frequent preventive maintenance actions are performed when the minimal repair cost is higher than the preventive maintenance cost, resulting in higher maintenance cost.

An aircraft engine is supposed to be used for a specified lifespan, and it is reused through the depot maintenance for a major overhaul when its cumulative service life reaches the lifespan. However, the depot maintenance takes a long time due to the complexity of its process, and thus to continuously operate aircraft, spare engines are required to substitute engines under renovation. Considering the limited capacity of the depot, the uniformity of the quantity and cycle of engines entering the depot maintenance provides an opportunity to the decrease of the spare engines and the improvement of aircraft availability. It is the purpose of engine life management. Furthermore, in establishing flight plans, the time for essential maintenance activities, such as pre/post-flight inspection, servicing, the preparation for next flight, has to guarantee. Especially, fighters additionally require much time for installing weapons for their mission. That is, the rearming procedure can be left out if the adjoining missions are identical. Otherwise, the rearming time is varyingly spent depending on the types of adjacent duties. Therefore, this study proposes the mathematical model for an aircraft-mission assignment considering engine life management and maintenance schedule, and it is formulated based on the time-space network. Moreover, to verify and validate the model, an example was developed by applying realistic aircraft operating environment and simulation to perform air operations for several days was fulfilled. The experimental results presented flight plans corresponding to the purpose of this study, such as engine life management and the assurance of maintenance time.

As a system complexity increases and technology innovation progresses rapidly, it tends to lease a system rather than own one. This paper deals with a decision-making model to determine the preventive maintenance strategy for leased equipment. Various maintenance options are presented and formulated via the non-homogeneous Poisson process. During the lease period, the preventive maintenance strategy that minimizes the total cost among the presented maintenance options is selected. A numerical example is provided to illustrate the proposed model.

The market size of plant projects in overseas is so large that domestic EPC project contractors are actively seeking the overseas projects and then trying to meet completion plans since successful fulfillment of these projects can provide great opportunities for them to expand into new foreign markets. International EPC projects involve all of the uncertainties common to domestic projects as well as uncertainties specific to foreign projects including marine transportation, customs, regulations, nationality, culture and so on. When overseas project gets off-schedule, the resulting uncertainty may trigger unexpected exceptions and then critical effects to the project performance. It usually require much more time and costs to encounter these exceptions in foreign sites compared to domestic project sites. Therefore, an exception handling approach is required to manage exceptions effectively for successful project progress in foreign project sites.In this research, we proposed a methodology for prediction and evaluation of exceptions caused by risks in international EPC projects based on sensitivity analysis and Bayesian Networks. First, we identified project schedule risks and related exceptions, which may meet during the fulfillment of foreign EPC projects that is performed in a sequence of engineering, procurement, preparatory manufacture, foreign shipping, construction, inspection and modification activities, and affect project performance, using literature review and expert interviews. The impact of exceptions to the schedule delay were also identified. Second, we proposed a methodology to predict the occurrence of exceptions caused by project risks and evaluate them. Using sensitivity analysis, we can identify activities that critically affect schedule delay and need to focus by priority. Then, we use Bayesian Networks to predict and evaluate exceptions. Third, we applied the proposed methodology to an international EPC project example to validate the proposed approach. Finally, we concluded the research with the further research topics. We expect that the proposed approach can be extended to apply in exception management in project management.

The project schedule risk in the engineering and facility construction industry is increasingly considered as important management factor because the risks in terms of schedule or deadline may significantly affect the project cost. Especially, the project-based operating companies attempt to find the best estimate of the project completion time for use at their proposals, and therefore, usually have much interest in accurate estimation of the duration of the projects. In general, the management of projects schedule risk is achieved by modeling project schedule with PERT/CPM techniques, and then performing risk assessment with simulation such as Monte-Carlo simulation method. However, since these approaches require the accumulated executional data, which are not usually available in project-based operating company, and, further, they cannot reflect various schedule constraints, which usually are met during the project execution, the project managers have difficulty in preparing for the project risks in advance of their occurrence in the project execution. As these constraints may affect time and cost which role as the crucial evaluation factors to the quality of the project result, they must be identified and described in advance of their occurrence in the project management. This paper proposes a Bayesian Net based methodology for estimating project schedule risk by identifying and enforcing the project risks and its response plan which may occur in storage tank engineering and construction project environment. First, we translated the schedule network with the project risks and its response plan into Bayesian Net. Second, we analyzed the integrated Bayesian Net and suggested an estimate of project schedule risk with simulation approach. Finally, we applied our approach to a storage tank construction project to validate its feasibility.

Logistics project scheduling problem in indeterminate environment is gaining more and more attention in recent years. One effective way to cope with indeterminacy is to develop robust baseline schedule. There exist many related researches on building robust schedule in stochastic environment, where historical data is sufficient to learn probability distributions. However, when historical data is not enough, precise estimation on variables may be impossible. This kind of indeterminate environment can be described by uncertainty according to uncertainty theory. Related researches in uncertain environment are sparse. In this paper, our aim is to solve robust project scheduling in uncertain environment. The specific problem is to develop robust schedule with uncertain activity durations for logistics project. To solve the problem, an uncertain model is built and an intelligent algorithm based on simulated annealing is designed. Moreover, we consider a logistics project as a numerical example and illustrate the effectiveness of the proposed model and algorithm.

다양한 전자제품의 조작법을 빠르고 정확하게 학습하는 것은 일상적이고 중요한 과제가 되었다. 특히 소프트 웨어는 여러 제품들의 통제 및 조작에서 핵심적인 지위를 차지하고 있다. 본 연구는 기존 학습연구에서 중요한 변인으로 연구되어온 학습방법, 학습계획, 과제난이도가 소프트웨어 학습에 미치는 영향을 검증하였다. 실험1에 서는 2 (학습방법: 경험적 vs. 언어적) x 2 (학습계획: 간격 vs. 덩이진) x 2 (난이도: 쉬움 vs. 어려운)의 피험자간 요인설계를 사용하여 각 조건에서 참가자들이 윈도우 무비메이커를 사용하여 파일을 조작하는 방법을 학습하는 실험을 실시하였다. 그 결과 학습계획에 따른 수행의 차이는 발견할 수 없었으나, 언어적 학습보다 경험적 학습 에서 참가자들은 더 빠르게 평가과제를 완료하였다. 특히 과제난이도가 높아질 경우 참가들은 언어적 조건에서 경험적 조건보다 두드러진 수행저하를 보였는데, 이는 과제가 어려워질수록 경험적 학습이 효과적인 학습방법이라는 것을 시사한다. 즉 소프트웨어 학습에서 간단한 조작의 경우에는 매뉴얼 혹은 지시문의 형태로 구성된 언 어적 학습으로 충분하지만 어려운 과제의 경우에는 체험 프로그램이나 투토리얼 모드를 통해 학습하는 것이 효 과적일 것이다. 추가실험에서 난이도 증가에 따른 언어적 학습의 선형적 이득을 확인하기 위해 난이도를 3단계 로 세분화하여 검증하였으며 (실험 2) 학습계획의 효과를 확인하기 위해 학습시행간 간격을 증가시켰으나 (실험 3) 유의미한 결과를 발견하지는 못했다.

The project-based business companies usually have much interest in predicting the expected finish date and related probability of project completion to refer at their proposals for projects. In general, the management of projects schedule risk is achieved by modeling project schedule with PERT/CPM techniques, then performing risk assessment with Monte-Carlo simulation method. However, since these approaches cannot reflect various schedule constraints, the project managers cannot prepare for the project risks in advance of their. This paper proposed a methodology for predicting project schedule risk by identifying and enforcing the constraints which may occur in a storage tank engineering and construction project environment. We applied our approach to a storage tank construction project to validate its feasibility. By using the methodology proposed in this paper, the project schedule risk can be evaluated and predicted more accurately and practically than the PERT/CPM or Monte-Carlo simulation approach.

漢文 敎科 敎育에서 經書의 經文은 많은 교육 내용을 포함하고 있다. 그러나 지금까지 경서 교육의 중요성에 비해 이에 관련된 연구는 많이 부족하였다. 필자 는 지금까지 교과서에 수록된 사서의 經文과 관련된 연구를 진행하던 중 몇 가지 큰 문제점을 발견하였다. 우선, 한문 교과서 경문 제시의 문제를 살펴보면, 첫째로 현재 중학교 1학년 교과서의 경서 단원 구성은 체계적이지 못했다. 경서 교육의 목표를 효율적으로 달성하기 위해서는 교과서의 단원들이 유기적으로 구성되어야 하고 교육 목표도 더욱 상세하게 진술해 주어야 할 것이다. 둘째, 懸吐․句讀의 제시 방법에 관한 구체적인 기준이 없는 문제를 확인할 수 있다. 이에 따라 한문 독해에서 懸吐․句讀의 제시방법에 대한 객관적 실험연구가 필요한 실정이다. 마지막으로 經文을 제시할 때 전체 경문을 제시하기보다는 대부분 斷章으로 제시하 고 있었다. 經文의 斷章이 잘못되었을 경우 經文의 의미를 제대로 파악할 수 없 는 문제가 발생한다. 즉, 효과적인 斷章에 대한 방안이 모색되어야 할 것이다. 다 음으로 한문 교과서 수록 경문의 난이도 문제이다. 현재 중학교 1학년에 수록된 사서 경문들은 겉으로 보이기는 쉬운 문장처럼 보이나 그 함의는 매우 깊다고 할 수 있다. 또한, 중학교 교과서의 수록 경문이나 고등학교 수록 경문의 차이는 극명 하게 나타나지는 않는다. 이는 사서 경문의 난이도에 대한 위계화가 이루어지지 못한 것이 가장 큰 이유이다. 따라서 객관적으로 경문의 수준을 위계화 하는 방안 이 필요하다. 이러한 문제점을 보다 체계적이고 객관적으로 접근하여 경서교육에 적용한다면 더욱 효과적인 교육이 이루어질 수 있을 것이라 기대한다.

In the project management context, the impotance of risk management is increasing because the risks in terms of time and cost may significantly affect the result of the project. In general, the management of projects schedule risk is achieved by modeling project schedule with PERT/CPM techniques, then performing risk assesment with monte-carlo simulation method. However, these approach can not reflect constraints, which may be occurred during the project execution, and cope with uncertainty in the future. As these constraints may affect time and cost which are the crucial evaluation factor to the project, they must be identified and evaluated to manage the future project risk before the project is started. This paper proposes a methodology for project schedule risk management by identifying and enforcing the constraints which may be occurred in complex and uncertain project environment. First, project risk constraints are identified and categorized into time, dependancy, and branching. Then, project schedule model with constraints is converted to CPN(Colored Petri Net) which can represent all the identified constraints to assess and predict schedule risk. Finally, the expected risk of the project (in terms of time and cost) is assessed and predicted by performing Petri Net simulation. By using the methodology proposed in this paper, the risk in terms of time and cost in project schedule model can be assessed and predicted more accurately and practically than the PERT/CPM and/or Monte-carlo simulation method. Furthermore, the constraints, which may occur unexpectedly after the project launch, can be evaluated to determine the schedule risk. The expected risk can be used to decide whether risk mitigation or project termination process undertake.

Flat rolling of wire is an industrial process used to manufacture electrical flat wire, medical catheters, springs, piston segments and automobile parts, among other products. In a multi-step wire flat rolling process, a wire with a circular crosssection is rolled at room temperature between two flat rolls in several passes to achieve the desired thickness to width ratio. To manufacture a flat wire with a homogeneous microstructure, mechanical and metallurgical properties with an appropriate pass schedule, this study investigated the effect of each pass schedule (1stand ~ 4stand) on the microstructures, mechanical properties and widths of cold rolled high carbon steel wires using four-pass flat rolling process. The evolutions of the microstructures and mechanical properties of the widths of cold rolled wires during three different pass schedules of the flat rolling process of high carbon wires were investigated, and the results were compared with those for a conventional eight-pass schedule. In the width of cold rolled wires, three different pass schedules are clearly distinguished and discussed. The experimental conditions were the same rolling speed, rolling force, roll size, tensile strength of the material and friction coefficient. The experimental results showed that the four-pass flat cold rolling process was feasible for production of designed wire without cracks when appropriate pass schedules were applied.

자동차 부품 개발은 대부분 프로젝트의 형태로 진행된다. 프로젝트의 일정을 단축하는 것이 기업의 이윤 창출에 도움이 되는 것은 사실이다. 하지만 자동차 부품을 개발하는 기업의 입장에서는 일정 단축 보다는 일정 내 고객의 요구 품질을 만족하는 제품을 공급하는 것이 더 중요하다. 이는 프로젝트 일정 단축이 부품업체의 권한 밖에 있으며, 또한 일정 단축에서 오는 이익보다는 일정 지연으로 인한 손실이 더 크기 때문 일 것이다. 이에 본 연구는 일정 관리 기법인 PERT/CPM, TOC(제약이론)를 기반으로 한 CCPM 기법과 자동차 산업의 신규 개발 부품 품질 보증을 위한 APQP(사전제품품질계획) 절차 등의 이론들을 고찰하고, PERT/CPM 기법을 적용한 상용 프로그램인 MS Project를 이용하여 부품개발 프로젝트의 일정 수립과 CCPM 기법을 적용한 CCPM+라는 상용 프로그램을 통한 일정 수립을 해보고자 한다. 마지막으로 두 기법의 일정과 자원제약에 대한 비교 분석을 통하여 자동차 부품 개발 프로젝트에 적합한 일정수립 방안에 대하여 고찰하고자 한다.

크로스도킹은 물류센터의 운영 개념으로써 입고트럭에 의해 배달된 물품이 재고로써 보관됨이 없이 즉시 고객의 수요에 따라 재분류되어 출고트럭에 적재되어 고객에게 배달되는 프로세스로 구성된다. 본 연구에서는 임시보관 장소를 보유한 크로스도킹 시스템의 총 운영시간을 최소화하기 위한 입고 트럭과 출고 트럭의 일정계획 수립을 위한 수학적 모델을 개발하였다. 본 연구에서 개발한 모델의 적용으로 물류센터 내에서의 자재 취급 빈도 및 시간이 감소하여 제품 손상을 최소화

Since the commencement of the government health insurance program in 1977, there has been criticism that the national insurance fee for health care service had been set too low by the Korean government. The existing insurance fee schedule for occupational therapy service was developed first in 1980 in Korea. But they are not reflecting the current health care environment. Even though the fee schedule has been revised almost every year, the fee has been estimated too low to warrant a quality service. To make the situation worse, Health Insurance Review Agency has recently proposed to substantially cut down the fee for occupational therapy service. Many medical institutions opening occupational therapy clinics are avoiding investment in this “financial deficit” department. This is threatening the survival of the occupational therapy profession that is essential for rehabilitation process. The objective of this study is to review and analyze the current Korean health insurance fee schedule and its changing process in occupational therapy service and suggest the better solutions. The researcher suggests that the health insurance fee schedule must cover computer-based occupational therapy, a Pediatric occupational therapy and evaluation, and treatment for the use of equipment such as Baltimore Therapeutic Equipment. Also, the government must increase the fee for occupational therapy service at least up to the level of consumer price index.