• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.771-780
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• 2013

Inspection system which was performed in the past selected the final winning bidder by separating Pre-Qualification, the basic design evaluation and price evaluation. However, turnkey and alternative bidding construction has selected way to determine the successful bidder as the best design and the most low cost method, comprehensive evaluation method (bid price adjustment, design score adjustments, weights standard), the best design and the fixed amount method from january 1, 2010 to the present. Due to these institutional problems, orders institutions were often a way to determine the successful bidder to apply differently for identical or similar construction. Therefore this study winning bidder selection criteria through analysis of construction the number and construction order performance, order performance by work division and institutional orders, the weights bidder order performance and orders status of turnkey alternative tendering construction to civil part performed in domestic.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.91-100
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• 2017

The solution was developed for the maintenance decision support of combined cycle power plant gas turbine. The developed solution was applied to MHI501G gas turbine and is, in present, on the process of field test at GUNSAN combined cycle power plant, South Korea. The developed solution provides the calculated result of optimal overhaul maintenance period through following modules: Real Time Performance Monitoring, Model-Based Diagnostics, Performance Trend Analysis, Optimal Overhaul Maintenance Interval, Compressor Washing Period Management, and Blade Path Temperature Analysis. Model-Based Diagnostics module analyzed the differences between the data of gas turbine performance model and the online measurement. Compressor washing management module suggests the optimal point of balancing between the compressor performance and the maintenance cost.

• Geophysics and Geophysical Exploration
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• v.10 no.2
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• pp.124-130
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• 2007

Least squares ($l^2$ norm) solutions of seismic inversion tend to be very sensitive to data points with large errors. The $l^1$ norm minimization gives more robust solutions, but usually with higher computational cost. Iteratively reweighted least squares (IRLS) method gives efficient approximate solutions of these $l^1$ norm problems. I propose an efficient implementation of the IRLS method for a hybrid $l^1/l^2$ minimization problem that behaves as $l^2$ norm fit for small residual and $l^1$ norm fit for large residuals. The proposed algorithm shows more robust characteristics to the decision of the threshold value than the l1 norm IRLS inversion does with respect to the threshold value to avoid singularity.

• Journal of Korea Port Economic Association
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• v.26 no.2
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• pp.58-81
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• 2010

The economic appraisal of a port remodeling project must be transparent and persuasive to the public over the entire stage of the project. A project evaluator need to be familiar with the guidelines on evaluation, and to do his best to follow the guidelines to evaluate the given project. To make the right decision on investment, the evaluator must take into consideration not only economic efficiency, but also equity issues such as income redistribution and balanced development between regions. Port remodeling projects tend to produce externalities to the environment. However, these externalities are of qualitative nature, and hard to measure in monetary terms, so these are liable to be ignored in the process of project evaluation. Two different approaches - RP(revealed preference) and SP(stated preference) have been tried to assess the value of these non-market goods. Government authorities need to set minimum guidelines which project evaluators must follow in order to make the evaluation more reliable.

• Journal of the Korea Society of Computer and Information
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• v.15 no.5
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• pp.125-132
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• 2010

Decision problem called an optimal release policies, after testing a software system in development phase and transfer it to the user, is studied. The applied model of release time exploited infinite non-homogeneous Poisson process. This infinite non-homogeneous Poisson process is a model which reflects the possibility of introducing new faults when correcting or modifying the software. The failure life-cycle distribution used exponential and non-exponential family which has various intensity. Thus, software release policies which minimize a total average software cost of development and maintenance under the constraint of satisfying a software reliability requirement becomes an optimal release policies. In a numerical example, after trend test applied and estimated the parameters using maximum likelihood estimation of inter-failure time data, estimated software optimal release time.

• Journal of Digital Convergence
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• v.11 no.10
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• pp.305-311
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• 2013

The size of the market as the economy continues to evolve, in order to make the right decisions to accurately predict the economic problems the market has emerged as an important issues. To express the modern economic system, the largest of the various economic indicators, pillars stock indicators analysis and decision-making with a proper understanding of the problem for the application of the model is suitable for time-series data concealment HMM. Based on this time series model and the calculation of the time and cost savings dimension decrease techniques for the estimation and prediction of the model was applied to the problem was to verify the validity. As a result, the model predictions in both the short term rather than long-term predictions of the model estimates the optimal predictive value similar pattern very similar to both the actual data and was able to confirm that.

• Journal of Digital Convergence
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• v.11 no.9
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• pp.159-166
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• 2013

In this paper, make a study decision problem called an optimal release policies after testing a software system in development phase and transfer it to the user. When correcting or modifying the software, finite failure non-homogeneous Poisson process model, presented and propose release policies of the life distribution, half-logistic property model which used to an area of reliability because of various shape and scale parameter. In this paper, discuss optimal software release policies which minimize a total average software cost of development and maintenance under the constraint of satisfying a software reliability requirement. In a numerical example, the parameters estimation using maximum likelihood estimation of failure time data, make out estimating software optimal release time. Software release time is used as prior information, potential security damages should be reduced.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.145-154
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• 2003

By optimizing the radiation protection the collective dose and individual dose could be reduced during YGN #4 $5^{th}$ outage in 2001. The collective doses for the two high radiation jobs decreased to 85% and 65% of expected doses. The proportion of workers with low dose (below 1mSv) exposure increased 4% while the proportion of workers with over 3mSv and 5mSv exposure are decreased to 2%, 1% respectively. But none is exposed over 8mSv for the annual dose. To aid decision of utilizing the robot, cost- benefit analysis was performed and reasonable point was proposed to use the robot. For the first time job, repeated ALARA meeting and mock up training were implemented to set up working procedure by identifying the trouble. To easily set up standard procedure, mockup process was videotaped and reviewed during ALARA meeting. Monitoring is a good approach to chase radiological working condition such as working time, dose rate. behavior of workers, especially for high radiation work. Those data were estimated and adjusted from the stage of work planning to mock up. At the stage of actual work the monitoring data were compared to the estimation and recorded to database. This database will not only be used as a powerful tool for dose optimization at the following outage but also as a guideline to dose constraint set up for optimization for each specific situation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.175-195
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• 1997

The learning curve has an important effect the growth of corporation. But, in Korea, the study and inference on the learning rate of each industry are unprepared, and so, Korean industires have difficult in productivity and cost. At this point, this study infers the learning rate of the oil industries and investigates the productivity and growth of them. In conclusion, this study presents the direction of the oil industries' development. With the intention of this objects, this study seizes the status which is concerned the total quantity, the operating rate, the plant capacity, the indicators concerning productivity, the investment of R & D and the scales, and then, infers and verifies the relevancy in connection with the learning rate. In the oil industry, the average rate of learning is 65.96% from 1982 to 1994 which the total quantity and the average operation time are used to infer the rate. To observe the low rate within a same period of time, this study takes the consequences that the learning rate is almost indentical with them each year. This steady state is caused by a difference between the employee and the decision maker about the acquirement and assimiliated of technology. When the high-quality technologies posses the environment to applicate in the scene of labor with them, this technology applies to the productivities. As the learning rate increases, the productivity has more effectiveness. The result of analysis about the effectiveness of the learning rate follows that the R & D unfoldes to exist and does not contribute to the growth of the oil industry. To analyze the variables of the growth, such as the learning rate, the investement of R & D, the operating rate and the gross value added to property, plant and equipment, the model is established and examined. The business strategy in the oil industry must be developed to achive the internal growth as well as the external.

• Korea Journal of Hospital Management
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• v.4 no.1
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• pp.1-20
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• 1999

Since the late 1980s, there have been radical changes in the managerial environment of Y University Medical Center(YUMC). Externally, the competition among hospitals has intensified due to the establishment of universal health insurance in 1939 and the entrance of large enterprises into the health care industry in the early 1990s. In addition, government regulation of medical institution is becoming stricter. Also, consumer groups have continued to demand the respect for patient rights and improvement of the quality of medical services. Internally, the financial condition of YUMC has worsened, not only because weak control and poor mediation in its large-scale structure have made its operation inefficient, but also because the rates of increase in the prices of goods and labor have grown faster than any increases in revenues. This study on materials management at YUMC presents a way for YUMC to reduce costs and increase its productivity, thereby overcoming its financial difficulties and dealing with external pressures. This study utilized the case studies of the materials purchasing and medical supply management in the United States and the comparative analysis of management to suggest short-term and long-term alternatives for innovation in YUMC. The goals of the short-term alternatives for innovation are to centralize the purchasing and supply departments and to simplify the decision-making processes. Through these attempts, it is estimated that YUMC's costs could be reduced by $600,000 per year. In the long-term, it is necessary to consider introducing a Supply Processing Distribution(SPD) system and setting up a centralized electronic system for supply and inventory management, although it is difficult to estimate the effect of cost-cutting because of the lack of analysis data. Thus, YUMC should thoroughly analyze initial investment costs and economical efficiency generated from long-term alternatives.