• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.2
• /
• pp.145-151
• /
• 2015

As order quantity is increased, the ordering cost per item will be cheaper due to saving of transportation and material handling costs. In this paper, two realistic assumptions such as quantity discount and budget limit are considered. Quantity discount means that all units in the order will be discounted according to the predetermined order levels. Budget limit represents that the costs for inventory investments are bounded. This paper develops a Lagrangian relaxation approach for a continuous review inventory model with a budget constraint and quantity discounts. Computational results indicate that the proposed approach provides a good solution. Sensitivity analysis is done to get some insights on budget limit and quantity discount. As budget limit or the amount of discount according to order quantity is increased, order quantity is increased, whereas reorder point is not always increased.

• Journal of the Semiconductor & Display Technology
• /
• v.9 no.2
• /
• pp.21-25
• /
• 2010

In response to the industrial needs for automated handling of very thin solar cell wafers, this paper presents the design concept for the individual wafer separation from the stacked wafers by utilizing continuous water jet. The experimental apparatus for automated wafer separation was constructed and it includes the water jet system and the microprocessor controlled wafer stack advancing system. Through a series of tests, the performance of the proposed design is quantified into the success rate of single wafer separation and the rapidity of processing wafer stack. Also, the inclination angle of wafer equipped cartridge and the water jet flowrate are found to be important parameters to be considered for process optimization. The proposed design shows the concept for fast and efficient processing of wafer separation and can be implemented in the automated manufacturing of silicon based solar cell wafers.

• Smart Structures and Systems
• /
• v.13 no.3
• /
• pp.419-434
• /
• 2014

In this paper, the electromagnetic damper (EMD), which is composed of a permanent-magnet rotary DC motor, a ball screw and a nut, is considered to be analyzed as a semi-active damper. The main objective pursued in the paper is to study the two degrees of freedom (DOF) model of the semi-active electromagnetic suspension system (SAEMSS) performance and energy regeneration controlled by on-off and continuous damping control strategies. The nonlinear equations of the SAEMSS must therefore be extracted. The effects of the EMD characteristics on ride comfort, handling performance and road holding for the passive electromagnetic suspension system (PEMSS) are first analyzed and damping control strategies effects on the SAEMSS performance and energy regeneration are investigated next. The results obtained from the simulation show that the SAEMSS provides better performance and more energy regeneration than the PEMSS. Moreover, the results reveal that the on-off hybrid control strategy leads to better performance in comparison with the continuous skyhook control strategy, however, the energy regeneration of the continuous skyhook control strategy is more than that of the on-off hybrid control strategy (except for on-off skyhook control strategy).

• Journal of Ship and Ocean Technology
• /
• v.9 no.4
• /
• pp.35-46
• /
• 2005

The performance of optimisation methods, based on penalty functions, is highly problem- dependent and many methods require additional tuning of some variables. This additional tuning is the influences of penalty coefficient, which depend strongly on the degree of constraint violation. Moreover, Binary-coded Genetic Algorithm (BGA) meets certain difficulties when dealing with continuous and/or discrete search spaces with large dimensions. With the above reasons, Real-coded Micro-Genetic Algorithm (R$\mu$GA) is proposed to find the global optimum of continuous and/or discrete nonlinear constrained engineering problems without handling any of penalty functions. R$\mu$GA can help in avoiding the premature convergence and search for global solution-spaces, because of its wide spread applicability, global perspective and inherent parallelism. The proposed R$\mu$GA approach has been demonstrated by solving three different engineering design problems. From the simulation results, it has been concluded that R$\mu$GA is an effective global optimisation tool for solving continuous and/or discrete nonlinear constrained real­world optimisation problems.

• Journal of Distribution Science
• /
• v.13 no.1
• /
• pp.83-91
• /
• 2015

Purpose - Despite the structural irrationality of multi-level transportation and the oil price rise, the domestic freight transportation market continues to grow, mirroring the rise in e-commerce and resultant increase in courier services and freight volumes. Several studies on courier services have been conducted. However, few studies or statistics have been published regarding regular freight services although they have played a role in the freight service market. The present study identifies the characteristics of regular freight service users to seek competitiveness enhancement measures specific to regular freight services. Research design, data, and methodology - IPA is a comparative analysis of the relative importance of and satisfaction with each attribute simultaneously. This study used IPA because it facilitates the process of analyzing importance and performance, deriving implications and a visual understanding of results. To enhance the competitiveness of regular freight services, this study surveyed its current users regarding the importance of the regular freight service factors. A total of 200 copies of a questionnaire were circulated and 190 copies were returned. In addition to demographics, respondents answered questions about the importance of and satisfaction with services on a 5-point Likert scale. Excluding 3 inappropriate copies, 187 out of 190 copies were analyzed. PASW Statistics 18 was used for statistical analysis. A total of 20 question items were selected for the service factors presented in the questionnaire based on the 1st pilot survey and previous studies. Results - According to the IPA performed to compare the importance of and satisfaction with service factors, both importance and satisfaction are high in the 1st quadrant, which involves the economic advantage of using regular freight services, quick arrival at destinations, weight freight handling, and less time constraints on freight receipt/dispatch. This area requires continuous management. Satisfaction is higher than importance in the 2nd quadrant, which involves the adequacy of freight, cost savings over ordinary courier services, notification on freight arrival, and freight tracking information. This area requires intensive investment and management. Satisfaction is lower than importance in the 3rd quadrant, involving the credit card payment system, courier delivery service, distance to freight handling sites, easy access to freight handling sites, and prompt problem solving. This area requires further intensive management. Both importance and satisfaction are low in the 4th quadrant, involving the availability of collection service, storage space at freight handling sites, kindness of collection/delivery staff, kindness of outlet staff, and easy delivery checks. This area is a set of variables should be excluded from priority control targets. Conclusions - Based on the IPA, service factors that need priority controls because of high importance and low satisfaction include the credit card payment system, delivery service, distance to freight handling sites, easy access to freight handling sites, and prompt problem solving. The findings need to be applied to future marketing strategies for regular freight services and for developing competitiveness enhancement programs.

• Physical Therapy Korea
• /
• v.4 no.1
• /
• pp.11-19
• /
• 1997

The use of therapeutic ultrasound(US) in humans with malignant neoplasms has been contraindicated in physical therapy practice. Some studies have shown that results after application of US differ according to tumor type and penetration depth. The purposes of this study were to determine the effects of US on melanoma in mice and to determine treatment dosage. Twenty-four female C57BL/6 mice, age 8 weeks. The right flank of all mice was shaved, and a 0.1 ml suspension of cells was injected subcutaneously into the animals' right flank. In this study, 24 subjects were randomly divided into three groups: experimental group 1(n=8), experimental group 2(n=8), control group(n=8). In the experimental group 1, animals received continuous 3 MHZ US treatment, administered at $2.0W/cm^2$ for five minutes. In experimental group 2, animals received continuous 3 MHz US treatment, administered at $1.0W/cm^2$ for 5 minutes. The control group received the same handling as other experimental groups, including rodent chow, water, US gel application but US head pressure without the power turned on. After 10 days treatment, all mice were killed with a potassium solution. Tumors were excised and weighed on an electrical balance and fixed in a 10% neutral buffered formalin solution. Tumor weights were smaller in experimental group 2(0.3838 g) than in the control group(0.6275 g). Tumor weights of the experimental group 1(0.015 g) were smaller than those of experimental group 2. Continuous therapeutic US decreased the weight of subcutaneous melanoma tumors in mice. The treatment dosage($2.0W/cm^2$) we suggest was more effective than earlier studies on decreasing tumor size with ultrasound.

• Journal of Navigation and Port Research
• /
• v.32 no.8
• /
• pp.621-628
• /
• 2008

Container terminals keenly compete with one another because of the continuous increase of container flows and the appearance of large-sized vessels. Major cargo handling equipment manufacturers are interested in the development of new conceptual equipment to greatly increase its productivity. In this study, a two-phase procedure is suggested for selecting the optimal development alternatives, when various development alternatives for container cranes are given. The first phase removes the alternatives that violate essential requirements and the second phase selects final alternatives by the evaluation of experts and the linear assignment method. Finally, a case applying the procedure is provided.

• Journal of the Korea Safety Management & Science
• /
• v.16 no.3
• /
• pp.101-110
• /
• 2014

This study tried to identify the effects of ergonomic risk factors for absence from work of fire fighters in Korea. A self-administered questionnaire was prepared for this study. The questionnaire consisted of several parts such as 'general information', 'work-related factors', 'physical & chemical risk factors', 'ergonomic risk factors', and 'absence information'. A total of 7,098 fire fighters participated in this study. The data obtained from the survey was mainly analyzed by logistic regression. A total of 856 out of 7,098 fire fighters experienced absence from work. The risk factors such as gender, age, marital status, education level, total work year, work area. position, job rotation, noise, dust, organic solvent, skin contact with chemical substance, toxic waste, regional vibration, manual material handling, continuous standing posture, awkward working posture were associated with absence from work. Specifically, awkward working posture and manual material handling from ergonomic risk factors were major risk factors for absence from work.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.8 no.1
• /
• pp.11-17
• /
• 2008

Typical wireless sensor networks used in structural monitoring are continuous types wherein data transmission is progressive at all time that may include irrelevant and insignificant data and information. Continuous types of wireless monitoring systems often pose problems of handling large-sized data that may deteriorate the performance of the system. The proposed method is to suggest an event-triggered monitoring system that captures and transmits relevant data only. An error signal generated by the Principal Components Analysis (PCA) is utilized as an index for event detection and selective data transmission. With this new monitoring scheme, the remote server is relieved of unwanted data by receiving only relevant information from the wireless sensor networks. The performance of the proposed scheme was verified with simulation studies.

• Journal of the Korea Convergence Society
• /
• v.8 no.11
• /
• pp.103-108
• /
• 2017

In the ubiquitous environment, there has been a problem of transmitting data from various sensors at a long distance. Especially, in the process of integrating data arriving at different locations, data having different property values of data or having some loss in data had to be processed. This paper present a method to analyze such data. The core of this method is to define an objective function suitable for the problem and to develop an algorithm that can optimize this objective function. The objective function is used by modifying the OCS function. MFA (Mean Field Annealing), which was able to process only binary data, is extended to be applicable to fields with continuous values. It is called CMFA and used as an optimization algorithm.