• Structural Engineering and Mechanics
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• v.23 no.1
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• pp.29-42
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• 2006

This paper describes the design scheme of the three-dimensional structures based on the concept of the cellular automata simulation. The cellular automata simulation is performed according to the local rule. In this paper, the local rule is derived in the mathematical formulation from the optimization problem. The cell density is taken as the design variable. Two objective functions are defined for reducing the total weight of the structure and obtaining the fully stressed structure. The constraint condition is defined for defining the local rule. The penalty function is defined from the objective functions and the constraint condition. Minimization of the penalty function with respect to the design parameter leads to the local rule. The derived rule is applied to the design of the three-dimensional structure first. The final structure can be obtained successfully. However, the computational cost is expensive. So, in order to reduce the computational cost, the material parameters $c_1$ and $c_2$ and the value of the cell rejection criterion (CRC) are changed. The results show that the computational cost depends on the parameters and the CRC value.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.2
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• pp.40-46
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• 2015

The modular assembly system can make it possible for the variety of products to be assembled in a short lead time. In this system, necessary components are assembled to optional components tailor to customers' orders. Budget for inventory investments composed of inventory and purchasing costs are practically limited and the purchasing cost is often paid when an order is arrived. Service cost is assumed to be proportional to service level and it is included in budget constraint. We develop a heuristic procedure to find a good solution for a continuous review inventory system of the modular assembly system with a budget constraint. A regression analysis using a quadratic function based on the exponential function is applied to the cumulative density function of a normal distribution. With the regression result, an efficient heuristics is proposed by using an approximation for some complex functions that are composed of exponential functions only. A simple problem is introduced to illustrate the proposed heuristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.5
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• pp.527-532
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• 2024

Physically Unclonable Functions (PUFs) provide a high level of security for private keys using unique physical characteristics of hardware. However, fabricating PUF chips requires numerous semiconductor processes, leading to high costs, which limits their applications. In this work, we introduce a low-cost manufacturing method for PUF security chips. First, surface roughening through wet-etching is utilized to create random variables. Additionally, physical vapor deposition is added to further enhance randomness. After PUF chip fabrication, both Hamming distance (HD) and Hamming weight (HW) are extracted and compared to verify the fabricated chip. It is confirmed that the PUF chip using two different multiple process variables demonstrates superior uniqueness and uniformity compared to the PUF security chip fabricated using only a single process variable.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.5
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• pp.209-218
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• 2015

BPEL is used in various domains since it can describe the flow of works according to conditions and rules, and it can call web services in service-oriented computing environments. However, new functions that are not provided by BPEL grammar are required in specific domains. Generally, when new functions are required, the domain-specific language should be newly defined and developed, which requires high development cost. In this regard, a new function needs to be defined and added instead of developing domain-specific language with the new functions added. However, such methods only allow an addition of a single function, and it is difficult to design and add new functions according to the needs. This paper defines XAS4B document, which extends the BPEL grammar function through XML schema in order to add new functions, and proposes BPEL engine generator that generates BPEL engine with the new functions added by processing the document. The XAS4B document enables the creation of a new grammar added to BPEL using XML schema. It also shows the process of adding new functions to BPEL engine using AspectJ, JAVA implementation of aspect-oriented programming. The proposed system can add new functions using AspectJ without modifying BPEL engine. This allows the provision of new functions at low cost in various domains.

• Journal of Korean Institute of Industrial Engineers
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• v.2 no.1
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• pp.85-92
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• 1976

In this paper, the employment planning model is developed which is a decision-making model for determining the optimum employment level with respect to varying net manpower requirement for each planing period such that total cost in a planning horizon is minimized. It is constructed as a nonlinear programming model and a dynamic programming model on the basis of studies in the areas of production smoothing and manpower scheduling. Costs for a planning period are categorized into regular wage cost, hiring cost, and overtime cost. The first is a linear function. The other two cost functions are of quadratic nature. The planning horizon of this planning model is intermediate range (five years) for which a fair planning accuracy can be guaranteed. The model considers learning period for each job class. It is simple and an optimum solution can be easily obtained by direct search techniques.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.2
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• pp.175-183
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• 1998

When a product is designed, tolerances must be given to the product so that required functions are guaranteed and production costs are minimized. In this research, a model is suggested which allocates tolerances to components optimally according to the STA(Statistical Tolerance Allocation) method. Taking into account the concept that dimensional errors have characteristics of statistical distributions, this model presents the discrete pseudo-boolean approach for the tolerance optimization by minimizing the tolerance cost and the quality loss cost. In this approach, two methods are proposed for the reduction of the problem scale; 1) a method for converting the minimization model for casts into the maximization model for cost savings, and 2) procedures to reduce the number of constraints and variables.

• International journal of advanced smart convergence
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• v.9 no.2
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• pp.157-163
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• 2020

Recently the blockchain technology has been actively studied due to its great potentiality. The smart contract is a key mechanism of the blockchain system. Due to the short history of the smart contract, many issues have not been solved yet. One main issue is vulnerability and another main issue is cost optimization. While the vulnerability of smart contract has been actively studied, the cost optimization has been rarely studied. In this paper, we propose two cost optimization methods for smart contracts running on the blockchain system. Triggering a function in a smart contract program code may require costs and it is repeated continuously. So the minimization of costs required to trigger a function of smart contract while maintaining the performance equally is very important. The proposed two methods minimize the usage of expensive permanent variables deployed on the blockchain system. We apply the proposed two methods to three prevalent blockchain platforms: Ethereum, Klaytn and Tron. Evaluation experiments verify that the proposed scheme significantly reduces the costs of functions in the smart contract written with Solidity.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.12
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• pp.349-376
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• 1999

The objective of this paper is to identify the problems of Korean inland transportation system and suggest the improvement plan for reducing the export logistics cost. The results are as follows: (1) Expansion of logistics hub facilities : Logistics hub facilities- integrated freight terminal and ICD, etc. can shorten the empty leg and reduce the logistics cost. (2) Design for CVO(Commercial Vehicle Operations) : CVO has various functions that improve the efficiency and effectiveness of freight transportation. (3) Rationalization of freight transportation industry : In particular, the deregulation of the motor freight industry and the privatization of the railway industry induce the competition among their firms and undercut the transportation rates in the long run. (4) Use of third-party logistics : The benefits of TPL are system reliability, improved customer service, and more efficient cost performance.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2463-2466
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• 2008

The public transportation in operation or to be planned domestically includes subway, LRT, bimodal tram and bus, which are independently characterized in their passenger capacity and cost. High quality service is generally accompanied by high cost of construction and operation. Thus, ITS, BIS/BMS and BRT system are recently introduced to provide high quality service to the passengers with the cost as low as possible. The bimodal tram is under development to achieve such goals in public transportation. The passenger capacity is approximately expected to be 10,000$\sim$17,000 persons/hour and the construction cost to be 10$\sim$30 million dollars/km. It is possible to construct the infrastructure gradually depending on the demand of transportation in the planned route, which can effectively reduce the initial cost to launch the service. The bimodal tram is developed to provide the advantages of subway and bus to the passengers with respect to the scheduled operation and flexibility of the lines.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.197-199
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• 2014

Todays, with the spread of Mobile devices, SNS service usage has been increasing. While SNS services have many benefits such as providing communication with social functions, these have also negative aspects like fatique. In the point that consumers make their own purchasing decision with considering cost and benefits of goods and services, this paper is to evaluate the value of SNS services considering both sides of beneficial and cost aspects.