In this study, we consider the problem of forecasting the number of inbound foreigners visiting Korea. Forecasting tourism demand is an essential decision to plan related facilities and staffs, thus many studies have been carried out, mainly focusing on the number of inbound or outbound tourists. In order to forecast tourism demand, we use a seasonal ARIMA (SARIMA) model, as well as a SARIMAX model which additionally comprises an exogenous variable affecting the dependent variable, i.e., tourism demand. For constructing the forecasting model, we use a search procedure that can be used to determine the values of the orders of the SARIMA and SARIMAX. For the exogenous variable, we introduce factors that could cause the tourism demand reduction, such as the 9/11 attack, the SARS and MERS epidemic, and the deployment of THAAD. In this study, we propose a procedure, called Measuring Impact on Demand (MID), where the impact of each factor on tourism demand is measured and the value of the exogenous variable corresponding to the factor is determined based on the measurement. To show the performance of the proposed forecasting method, an empirical analysis was conducted where the monthly number of foreign visitors in 2019 were forecasted. It was shown that the proposed method can find more accurate forecasts than other benchmarks in terms of the mean absolute percentage error (MAPE).

The plastic waste problem is deepening all over the world. Plastic wastes have serious impacts on our lives as well as environmental pollution. The production and use of plastics increases every year, but once they are produced, they usually roam the earth for hundreds or thousands of years to pollute the environment. Although there is growing interest in plastic issues around the world and environmental regulations are being tightened, but no clear solution has yet been found. This study suggests Environmental degradation index (EDI). EDI can help raise consumers’ attention to plastic wastes. In addition, EDI will contribute to reduce them in the future. As far as we know, this is the first study. We developed EDI for the confectionery packaging. This study defines four factors that may affect the environment of confectionery packaging: greenhouse gas emissions, energy consumption, methane emissions, and packaging space ratio. Then we quantify the value of each element and compute EDI as the sum of the four component values. In order to evaluate the feasibility of EDI proposed in this study, confectionery-packaging materials distributed in Korea were collected and analyzed. First, the types of confectionery are classified into pies, biscuits, and snacks and basic data was collected. Then the values of the four components were calculated using existing research data on the environment. We can use the proposed EDI to determine how much a product packing affects the environment.

In this study, we consider the assembly line balancing (ALB) problem which is known as an very important decision dealing with the optimal design of assembly lines. We consider ALB problems with soft constraints which are expected to be fulfilled, however they are not necessarily to be satisfied always and they are difficult to be presented in exact quantitative forms. In previous studies, most researches have dealt with hard constraints which should be satisfied at all time in ALB problems. In this study, we modify the mixed integer programming model of the problem introduced in the existing study where the problem was first considered. Based on the modified model, we propose a new algorithm using the genetic algorithm (GA). In the algorithm, new features like, a mixed initial population selection method composed of the random selection method and the elite solutions of the simple ALB problem, a fitness evaluation method based on achievement ratio are applied. In addition, we select the genetic operators and parameters which are appropriate for the soft assignment constraints through the preliminary tests. From the results of the computational experiments, it is shown that the proposed algorithm generated the solutions with the high achievement ratio of the soft constraints.

According to a simple survey on the current status of the assembly line design, it was found that trial and error methods on the basis of experiences have been used mainly in domestic manufacturing industries, even though there exist a lot of excellent line balancing studies. It seems that more practical researches should be carried out to develop user-oriented line balancing tools especially for small and medium-sized enterprises. This study presents a design of the line balancing tool which can support the line balancing tasks of nonspecialists. The proposed design tool is composed of three major modules: pre-process, line balancing, and post-process. In particular, pre-process and post-process are newly proposed to increase its ease of use. We applied the proposed design to a test problem and test result showed that our practical method may contribute to enhance the efficiency of production operations management.

In this thesis, we surveyed the current status of production operations management to find how to improve the operations efficiency. From the survey research, we have found that practical software tools should be developed to increase the efficiency of production operations management, especially for small and mediumsized enterprises. Although there exist a lot of excellent line balancing researches, the results of our survey represent that trial and error methods on the basis of experiences have been used mainly used in the domestic manufacturing industry. It seems that more practical researches should be carried out to develop user-oriented line balancing tools. As a part of the development of those tools, this thesis proposed a design of the line balancing tool which can support the line balancing tasks of nonspecialists. The proposed design is composed of three major phases: redundancy check of the precedence diagram, line balancing, and modification of the line balancing results. The first phase is to check the precedence diagram of work elements and remove the redundancy. The redundancy may affect the quality of solutions and computational time. Although it is important to prepare a neat and proper precedence data, it is not easy to develop a tidy precedence diagram for laymen. The first phase automatically removes the overlapped data. The next phase is the line balancing algorithm. The proposed algorithm is based on COMSOAL and can solve minimization of the number of work stations given the target production cycle time and minimization of the production cycle time given the number of work stations. Additionally, our suggested method can accommodate the predetermined location constraints. The third phase is to modify the solution suggested by the second phase. Frequently, users may want to change the result to reflect some constraints which were not easy to be included into the line balancing algorithm. So, a practical line balancing tool should provide mechanisms to modify the solution and they should check the precedence violation while a user tries to change the work station of an element. This research suggested a simple mechanism to check the precedence violation. We applied the proposed design to some test problems and test results showed that it performed successfully. Therefore, our method may contribute to enhance the efficiency of production operations management.

Because of user's apathy and carelessness, it is difficult to keep the public places (such as school practical rooms) clean. In this study, we presented a six sigma project to improve the level of cleanliness of a university laboratory. We applied the DMAIC (define, measure, analyze, improve, and control) procedure which is the general methodology of the six sigma project. In the process of DMAIC, we listened to the VOC, quantified the level of cleanliness as the level of sigma, and performed various activities to improve user's consciousness level. As a result of the project execution, cleanliness satisfaction has been increased about more than three times. It is expected that results of the proposed case study can be applied to other public places. Also, this study showed the academy campus can be used as a good place for the practical six sigma education.

This thesis proposes a new social network simulator, which can be used for the social network analysis (SNA). It is composed of three modules; initialization, network evolution, and output generation. For the network evolution module, we suggest a modifie

The purpose of this thesis is to develop a performance rating training tool for the time and motion study. It is widely recognized that rating training tools based on films were made several decades ago and introduced to Korea. However, to the best of our

To survive head-to-head competition, we should keep our labor productivities above those of other nations. However, our labor productivities are low compared to those of the developed countries. It is the well-known fact that we make up for the productivi

  HPI (High-speed Portable Internet) system which provides high speed internet services is going to be commercialized soon. Since HPI provides simultaneously four different service types such as UGS (Unsolicited Grant Service), rtPS (real time Polling Ser

Computer simulation is widely known as a very powerful and practical tool to understand behaviors of considered sys-tems and evaluate design alternatives However, to use simulation technologies, one should acquire simulation languages, statistics, etc Als

This paper presents a new heuristic algorithm for the machine celJ(MC) formation problem. MC formation problem is represented as an unbalanced k-way network partition and the proposed algorithm uses four stage-approach to solve the problem. Four stages ar

In this paper, machine cell formation problem is discussed. To reflect precisely actual manufacturing situations such as routing sequences, production quantities, and machining (or operation) characteristics, a new network presentation for the problem is