• Journal of Korean Society for Quality Management
• /
• v.30 no.3
• /
• pp.53-65
• /
• 2002

This paper studies an economic manufacturing quantity (EMQ) model with two types of failures and planned preventive maintenance of the production facility. One is a type I (major) failure which should be corrected by a failure maintenance and the other is a type H (minor) failure which can be minimally repaired without interrupting the production run. The objective is to determine the lot size and preventive replacement policy minimizing the long-run expected cost per unit time. We consider a control policy with a constant production lot size and preventive maintenance after completing n production runs. It is assumed that both preventive and failure maintenance times are random and the demand arriving during a stock-out period is lost. An expression for the expected cost per unit time is obtained in the general case. A special case is discussed and numerical results are provided.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.05a
• /
• pp.673-676
• /
• 2007

These days, the damage of noise has increased seriously by rapid change of life style because of the centralization of urban population, and the rapid increase of traffic. The Ministry of Environment has emphasis on the systematic management about the noise of daily life and the close connection of daily noise management policy with relevant ministries, and put into practice "the master plan of lessening the noise of daily life" from year 2006. This study tried to find out the reduction methods and the effective management of railway noise in the action plan of railway part of "the master plan of lessening the noise of daily life". According to this study, railway noise can be reduced greatly by taking action of railway detail plans. The cause of railway noise varies by rolling stock, track and more, so the reduction methods of railway noise can be studied specially, scientifically and constantly in every field.

• Journal of Technology Innovation
• /
• v.12 no.1
• /
• pp.1-24
• /
• 2004

This paper analyses the effects of R＆D investment on patent in Korean manufacturing firms during the period 1984-99. The data contains 140 companies which listed in Korea Stock Exchange(KSE). We observed that the relative shares of R＆D investments and patent applications are much higher in scientific firms than in the other firms. The regression results show that R＆D investment has significantly positive effects on the growth of patent application and registration. And the effects of R＆D on patent turns out to be stronger in scientific firms than the other firms. The firm size and the capital intensity also have an important effect on the propensity to patent.

• IE interfaces
• /
• v.25 no.3
• /
• pp.338-346
• /
• 2012

Regarding the green environment, it is important to boost the spread of environmentally friendly vending machines and to operate the vehicles for their inventory replenishments while minimizing emissions of greenhouse gases. In general, the vending machine management company lacks capability to operate the supply chain effectively in an integrated way under the dynamic, complex, and stochastic environment. This paper presents a decision support system, termed DSSVM, for the operations of the general and smart vending machine supply chains with stock-out-based, one stage item substitution in a green logistics environment. The DSSVM supports the estimation of item demand and substitution probabilities, determination of operation parameters, supply chain analysis, what-if analysis, and $CO_2$ analysis for which various analytical models are employed.

• Structural Engineering and Mechanics
• /
• v.50 no.4
• /
• pp.541-561
• /
• 2014

This paper approaches the issue of seismic vulnerability assessment strategies for facade walls of traditional masonry buildings through the development of a methodology and its subsequent application to over 600 building facades from the old building stock of the historic city centre of Coimbra. Using the post-earthquake damage assessment of masonry buildings in L'Aquila, Italy, an analytical function was developed and calibrated to estimate the mean damage grade for masonry facade walls. Having defined the vulnerability function for facade walls, damage scenarios were calculated and subsequently used in the development of an emergency planning tool and in the elaboration of an access route proposal for the case study of the historic city centre of Coimbra. Finally, the methodology was pre-validated through the comparison of a set of results obtained from its application and also resourcing to a widely accepted mechanical method on the description of the out-of-plane behaviour of facade walls.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.39 no.4
• /
• pp.1-17
• /
• 2014

The functions of stocking and releasing in logistics center consist of three major procedure such as receiving, shipping and stock managements. Each process includes various sub-processes which are complicatedly connected with each other. Furthermore, lots of operators execute various tasks in the different sub-processes, simultaneously. It makes difficult to standardize, monitor, and analyze the processes. This paper proposed the quantitative methodology using process mining approach to discover and analyze receiving and shipping processes. For this purpose, the PDA operation log data is analyzed to build a realistic process model. The deduced model has been compared with official process model. In addition, task assignment and social networks analysises are carried out by utilizing process mining tools. Also, it has been proposed how to improve the processes with the analytical simulation model based on the results of process mining.

• Journal of Distribution Science
• /
• v.11 no.3
• /
• pp.5-11
• /
• 2013

Purpose - Going concern is one of fundamental concepts in accounting and auditing and sometimes the assessment of a company's going concern status that is a tough process. Various going concern prediction models' based on statistical and data mining methods help auditors and stakeholders suggested in the previous literature. Research design - This paper employs a data mining approach to prediction of going concern status of Iranian firms listed in Tehran Stock Exchange using Particle Swarm Optimization. To reach this goal, at the first step, we used the stepwise discriminant analysis it is selected the final variables from among of 42 variables and in the second stage; we applied a grid-search technique using 10-fold cross-validation to find out the optimal model. Results - The empirical tests show that the particle swarm optimization (PSO) model reached 99.92% and 99.28% accuracy rates for training and holdout data. Conclusions - The authors conclude that PSO model is applicable for prediction going concern of Iranian listed companies.

• Microbiology and Biotechnology Letters
• /
• v.27 no.5
• /
• pp.399-403
• /
• 1999

For the production of trehalose, microorganisms capable of producing trehalose extracellularly were screened from the stock cultures in our laboratory. among them, Micrococcus luteus IFO 12708 showed the highest productivity of trehalose. For the increase of productivity, the mutant strai Hs-208 having higher trehalose production was selected with NTG(N-methyl-N'-nitrosoguanidine) mutagenesis, which led to the decrease of the specific activity of trehalose phosphorylase(3.2-fold) as compared to the wild strain. The optimum condition for the trehalose production was established as follows: 20g/l of glucose and 6g/l of tryptone were used as a sole carbon source and nitrogen source, respectively, and cultivations were carried out at 3$0^{\circ}C$ and pH 6.0. After 20hrs cultivation, addition of 20unit/ml penicillin G led to the higher conversion yield of trehalose. Under the optimum condition, 6.547g/l trehalose was produced with conversion yield of 32.7%.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.878-882
• /
• 2004

We investigated the effect of weld details on fatigue behavior of a material, JIS SM 490 A, with yielding strength of about 350 MPa and tensile strength of about 520 MPa. Tensile tests, instrumented indentation tests and fatigue tests were carried out on double V-grooved butt weld plates such as reinforcement removed, as-welded and weld toe ground. In addition plates with transverse fillet welded web, load carrying cruciform fillet welded plates, non-load-carrying cruciform fillet welded plates, longitudinal butt welded plates and welded rectangular life-size box beams were tested. S-N curves for the above specimens were obtained and analyzed.

• Korean Journal of Computational Design and Engineering
• /
• v.16 no.3
• /
• pp.207-215
• /
• 2011

Due to its large size, a ship is first divided into scores of blocks and then each block is constructed through various shops, such as the assembly shop, the painting shop, and the outfitting shop. However, each block may not be directly moved to the next shop and may be temporarily laid on a block stockyard because the working time in each shop is different. If blocks are laid on the block stockyard without any planning, the rearrangement of the blocks by a transporter are required because the blocks have the different in and out time. In this study, an optimal layout method based on the genetic algorithm was proposed in order to minimize the rearrangement of the blocks in the block stockyard. To evaluate the applicability of the proposed method, it was applied to a simple layout problem of the block stockyard.