• Journal of Korean Society for Quality Management
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• v.44 no.4
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• pp.751-770
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• 2016

Purpose: Two-stage ${\bar{X}}$ chart is a useful tool for process control when a surrogate variable may be used together with a performance variable. This paper extends the two-stage ${\bar{X}}$ chart to a three stage version by decomposing the first stage into the preliminary stage and the main stage. Methods: The expected cost function is derived using Markov-chain approach. The optimal designs are found for numerical examples using a genetic algorithm combined with a pattern search algorithm and compared to those of the two-stage ${\bar{X}}$ chart. Sensitivity analysis is performed to see the parameter effects. Results: The proposed design outperforms the optimal design of the two-stage ${\bar{X}}$ chart in terms of the expected cost per unit time unless the correlation between the performance and surrogate variables is modest and the shift in process mean is smallish. Conclusion: Three-stage ${\bar{X}}$ chart may be a useful alternative to the two-stage ${\bar{X}}$ chart especially when the correlation between the performance and surrogate variables is relatively high and the shift in process mean is on the small side.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.11a
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• pp.30-36
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• 2007

Recently, many performing arts facilities are under construction to accommodate people's various interest in cultural experiences. However, due to Korea's lack of know-how in such constructions and an absence of proper regulations on design planning, each designer designs and constructs the facilities differently, so several problems are occurring in the process of construction, such as high production cost for stage sets, high labor cost, low efficiency of stage work, and complicated work process. This resulted in low quality production of performance. This study is conducted to address the need for a systematic study on stage floor, and to propose an efficient way of regulating stage work in existing performing arts facilitiesand new facilities to be built. By a comparative analysis of performing arts facilities in Korea, and by analyzing stage floors of the facilities, this research suggests minimum modules as well as an appropriate unit of modules based on the minimum modules; and provides basic data on stage floors, which can be used for remodeling existing facilities orfor planning new cultural facilities. Also, this study suggests various ways of utilizing performing arts facilities in Korea.

• Korean Journal of Construction Engineering and Management
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• v.10 no.3
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• pp.32-41
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• 2009

In the execution of construction management, such pre-design steps as a planning stage, a basic design stage, and a work design stage are regarded as more important than an actual construction stage. However, the manpower input criterion from the aspect of construction management price standard in the Construction Engineering Management Law does not attach weight to the pre-design stage. In this regard, the aim of this study was to examine the propriety of manpower input in the pre-design stage of construction management and then present an improvement strategy of it. For this, the investigator examined the criterion of service price prescribed in the Construction Engineering Management Law and then comparatively analyzed four sites of construction management services. Study findings are as follows: 1) the actual state of manpower input based on the stepwise average price criterion of construction management service is presented with such steps as the newly established planning step (6.6%), the basic design stage (3.9%$\rightarrow$5.6%), the practical design stage(7.6%$\rightarrow$13.5%), the construction stage (88.5%$\rightarrow$64.0%), and the newly established maintenance stage (10.3%). The average price criterion is classified by total construction expenses and calculated by improved rates and stage; and 2) the three-step criterion of the Construction Engineering Management Law is classified into five stages including the planning stage and the maintenance stage by dividing it with the stepwise construction businesses. Study findings show that the calculation of price criterion in the actual site of construction management services must be operated in a practical and flexible manner and the systematic improvement of stepwise manpower input must be carried out actually.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.312-317
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• 2000

High efficient steam turbine stage has been developed with the help of the 3-dimensional design tool. In this stage design, the compound leaned stacking method has been adopted to reduce the secondary flow loss of a turbine passage and to increase the performance efficiency for the turbine nozzles. And the turbine buckets have been designed with the quasi-3-dimensional turbomachinery blade design method. To verify the stage design, therefore, the 3-dimensional numerical simulation of a steam turbine stage was conducted. In this design, CFX-TASCflow was employed to predict the turbulent flow of a steam turbine stage. The analysis was performed in parallel calculation using the HP N4000 8 CPUs machine. The result showed CFX-TASCflow could be used as the 3-dimensional flow analysis tool of steam turbine design.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1077-1084
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• 2000

In this work, a modified stage-stacking method for the performance prediction of multi-stage axial flow compressors is proposed. The method is based on a simultaneous calculation of all interstage variables (temperature, pressure, flow velocity) instead of the conventional sequential stage-by-stage scheme. The method is also very useful in simulating the effect of changing angles of the inlet guide vane and stator vanes on the compressor operating characteristics. Generalized stage performance curves are used in presenting the performance characteristics of each stage. General assumptions enable determination of flow path data and stage design performance. Performance of various real compressors is predicted and comparison between prediction and field data validates the usefulness of the present method.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.9
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• pp.202-209
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• 2000

In recent years the concern of designing multi-stage gear drives increases with the more application of gear drives in high-speed and high-load. until now however research on the gear drive design has been focused on single gear pairs and the design has been depended on experiences and know-how of designers and carried out commonly by trial and error. We propose the automation of the dimensional design of gears and the configuration design for gear arrangement of two-and three-stage cylindrical gear drives. The dimensional design is divided into two types of design processes to determine the dimensions of gears. The first design process(Process I) uses the total volume of gears to determine gear ratio and uses K factor unit load and aspect ratio to determine gear dimensions. The second one(Process II) makes use of Niemann's formula and center distance to calculate gear ratio and dimensions. Process I and II employ material data from AGMA and ISO standards respectively. The configuration design determines the positions of gears to minimize the volume of gearbox by simulated annealing algorithm. Finally the availability of the design algorithm is validated by the design examples of two-and three-stage gear drives.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.6
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• pp.114-119
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• 2004

For passenger vessels, twin shaft types in propulsion system is generally adopted to provide a high-speed performance in low draught due to restricted operating condition in harbors or water channels. Struts of twin open shaft type support the shafts, bearings, and propellers. Therefore, strut design is needed to consider not only hydrodynamic performance but also structural and noise/vibration performance, In this paper, considerations in strut design at the initial design stage have been discussed based on existing references, numerical calculations, and their comparisons. Also, the strut design of a RoPax ferry has been carried out at the initial design stage, for an example.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.759-762
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• 2002

A preliminary design process in the multi-stage gear drives design is important part. a preliminary design support system which run efficiently the design is developed with fuzzy expert system. the system automatically generate the mechanism of multi-stats gear drives and select a candidate mechanism by the general expert rule and sorting using fuzzy expert system. the preliminary mechanism design of multi-stage gear drives have a short execution time, add accuracy in a preliminary design considering volume, cost, power and efficiency in preliminary, a design efficiency is increased and a preliminary design have a elasticity using a weight on variable's sorting mechanism.

• Korean Journal of Construction Engineering and Management
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• v.8 no.4
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• pp.167-175
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• 2007

A renovation project of apartment housing is generally divided into four stages: Project inquiry stage, planning and feasibility stage, design stage and construction stage. Currently, procedure and managerial technique for a remodeling project has not been systematically established so that many companies have difficulty in doing their business. In particular, the design stage in participant which a project managers, designers, residents and engineers is more complicate than the other stages in terms of roles and working procedure. The design documents can be found trial and error if it is not well managed. The insufficient design caused by lack of ability to efficiently utilize information obtained during the stage and inappropriate decision-making not only results in diverse problems in the construction stage but also makes people suspect satisfaction and reliability on the remodeling improvements. Therefore the design stage is very significant issue on the renovation project. As the consequence, the design stage of a remodeling project is so important that it should be carefully managed, and composite understanding of the process to be executed. To do this, we provide roles and responsibility of each participant in the design stage and analyze the process where information is utilized in design stage. The information is analyzed in terms of input, tool and output.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.2
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• pp.57-64
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• 2001

In recent years, the concern of designing multi-stage gear drives ha increased with more application of them in high-speed and high-load. Until now, however, the researches on the design of gear drives have been focused on single gear pairs. Thus the design practice for multi-stage gear drives has been depended on experiences and expertise of designers and carried out commonly by trial and error. We propose an automation algorithm for the design of two-and three-strage cylindrical gear drives. The two types of dimensional design processes have been proposed to determine gear dimensions in a formal way. The first design process(Process I) uses to total volume of gears to determine gear ration , and uses K factor , unit load and aspect ration to determine gear dimensions, The second one(Process II) makes use of Niemann's formula and center distance to calculate gear ratio and gear dimensions. Process I and Process II employ material date from AGMA and ISO standards, respectively. The configuration design determines the positions of gears with minimizing the volume of gearbox by using a simulated annealing algorithm. The availability of the design algorithm is validated by the design examples to two-and three=stage gear drives.