• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.163-171
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• 1999

The abnormal grain coarsening in wire rolling induces detrimental defects, such as jagged size tolorance, severe bending after heat treatments and drawing troubles, in the following secondary processes. Neishi et al observed that there is a band type region where grain coarsenting occurs in the plastic strain vs. deformation temperature plot. Based on the finding, we have investigate whether grain sizes and ferrite volume fractions are correlation to deformation strain with three kinds of wire rod diameters as for the different average deformation conditions. The samples were chosen from the No.2 Wire Rod Mill of POSCO where 3-roll type of finishing mill stand are used. It was found in the present work that the grain size and ferrite volume fraction of the rolled and cooled microstructure were changed with rolling reduction and rolling temperature. Abnormally grown grains at various observed points were also found. To have homogeneously fine grains of microstructure from the No. 2 Wire Rod Mill, it will be easier to control finish rolling temperature at around 750$^{\circ}C$ rather than to find another rolling schedule.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.73-79
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• 2010

Deck plates have been widely used for steel framework due to their merits in terms of schedule reduction and work repetition. For this reason, most of the previous studies related to deck plates have focused on the development of form type and their constructability. In this study, through an actual case study and interviews with experts, a simulation model was developed using the CYCLONE method. Based on this model, this study not only analyzed the productivity of the work process of the deck plate in steel framework, but also identified the occurrence of idle time in the work process. In addition, using a sensitivity analysis, productivity and duration could be analyzed according to variation of input resources. Based on the results, this paper suggests a way to improve the productivity of deck plate work in steel frameworks. Using the model, it is expected that project managers would be able to predict the productivity and total duration of the deck plate work in the early project phase, which will enable managers to make an appropriate plan for input resources.

• Korean journal of food and cookery science
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• v.20 no.4
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• pp.335-341
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• 2004

The purpose of this study was to measure the labor intensity of menus according to various cooking types. Through a literature review and in-depth interview, the attributes that affected the labor intensity were identified as the level of skill, amount of effort, degree of tiredness, time consumed, and machine usage. A survey was conducted in April, 2001 among cooks who Dew the entire process of cooking. There was a strong positive correlation between labor intensity and labor intensity attributes. Through regression analysis, a regression equation was obtained between labor intensity and labor intensity attributes. The labor intensity index calculated from this study showed the extent of labor intensity of menus. The result of this study could be used as basic data for foodservice manager to establish a menu planning and work schedule based on a scientific method.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.903-910
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• 2000

Because the construction type SFRB is completely different in comparison with that of RC apartment the construction and work process, which are currently used, have to be changed. The main purpose of study is to analyze the difficulties of this construction and to apply the technology for other construction area. In this study, it is investigated to the problems of construction for SFRB and the construction method of PC panel fabricated on SFRB in Yongin goosng. Later, it is estimated prefabricated method had an great effect on PC panel System as lower cost and shorter schedule in SFRB. The Precast concrete framed System has many merit than the reinforced concrete structures system at constructability, structural safety and quality, therefore, it will be widely applied at parking structure in the future.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.237-238
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• 2016

Rework is a major cause that adversely affects the performance of a construction project, such as schedule delay or cost overrun. In order to prevent rework, research has been mainly conducted to analyze the cause of rework, but limited to quantitatively measure cost of rework and analyze its impact on project performance. Therefore, this paper aims to analyze impact of rework cost using 369 rework items collected from 3 construction site. This research is expected to accurately determine control target of rework and to improve efficiency of business operations in construction project.

• Journal of the Korean Society of Food Culture
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• v.9 no.2
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• pp.159-170
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• 1994

Central commissary school foodservice operations' practices and their dietitians' job duties were assessed and compared with those of their counterpart of conventional school foodservice operations to find out strategies for early settlement and better management for commissary system. Survey qestionnaires consisted of general background, employees' work schedule and dietitians' job duties. 12 commissary schools(out of 22 existing in Korea) and 77 conventional schools from Kyungkido were participated in the survey. The results of this study can be summarized as follows: 1. Central commissary school foodservice was presently utilized at 5 schools from islands type, 11 schools from rural type, and 6 schools from urban type, consisting total of 22 commissary schools, and 52 satellite schools. 2. Dietitians were evenly employed with their experiences, 55.5% were those with less than 2 years of experience, 44.6% were those with more than 2 years of experience. 3. Commissary schools employed more full-time empolyees$(1.8{\pm}0.7)$ than conventional schools$(0.3{\pm}0.5)$, however as far as the production capacity was concerned, only the part-time employees played significant roles(p<.01). Regardless of the number of students, an absolute number of full-time employees were employed, and their duties were not carried out efficiently. The part-time employees of commissary schools performed more loaded work compared to their counterparts in conventional schools. 4. Out of the dietitians' foodservice duties, 'basic food service production$(3.9{\pm}0.7)$' were carried out adequately, whereas 'nutrition education and advertisement$(2.5{\pm}0.6)$' and 'administrative affairs and information related duties$(2.8{\pm}0.9)$' were not. In order to enhance their working capacity, systematic organizational reforms are imminent. 5. Survey results also showed that dietitians performed less duties at satellite school than at the central commissary. This indicates more systematic foodservice management practices are urgently needed.

• Journal of the Korean Society of Systems Engineering
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• v.10 no.1
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• pp.33-41
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• 2014

New design concept of Reactor Coolant System (RCS) including a reactor assembly for the SMR is introduced in this work. An exploration of new type of reactor that is advanced from proposed SMRs is performed by using systems engineering approach. In this point of view project structured on three main phases; needs analysis (NA), concept exploration (CE), and concept definition (CD). Main objectives as an output of the CE stage are a small size, low cost, shortening the schedule, and enhancing safety. The SMRs usually have a small size requirement. In order to meet the size requirement and to achieve a productivity, in other words, easiness to manufacture, this paper suggests an integrated PWR design concept through researching predecessors. Although the integrated PWR concept provides many advantages, it has disadvantages that composite of maintenance and a low availability problem. Therefore, this paper comes up with a run-to-fail design concept based on modular design to address the maintenance problem and to maximize the availability of SMRs as well as to be compatible with the overall-SMRs including Barge Mounted(BM)type.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.2
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• pp.254-264
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• 2007

This paper considers a scheduling problem to minimize the total weighted completion time in the two-stage assembly-type flowshop. The system is composed of multiple fabrication machines in the first stage and a final-assembly machine in the second stage. Each job consists of multiple components, each component is machined on the fabrication machine specified in advance. The manufactured components of each job are subsequently assembled into a final product on the final-assembly machine. The objective of this paper is to find the optimal schedule minimizing the total weighted completion time of jobs. Three lower bounds are derived and tested in a branch-and-bound (B&B) Procedure. Also, three heuristic algorithms are developed based on the greedy strategies. Computational results show that the proposed B&B procedure is more efficient than the previous work which has considered the same problem as this paper.

• KIEAE Journal
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• v.7 no.6
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• pp.113-118
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• 2007

The composite beam adopted in the study was designed to reduce the floor height as well as to embed the top flange of steel frame into the slab that will enable to avoid applying the fire-resistant coating and to unify the joint method with a steel frame-type. As the steel frame and bottom concrete of the beam is pre-fabricated at the factory it could reduce the overall schedule at the jobsite. Applying such composite beam system to the work is expected to provide the efficient and enhanced performance, given the current tendency of the building construction that tends to be getting higher, larger and dense. The study focused on combining the composite beam with various column systems in a bid to propose the details thereof. A desirable composite girder can be adopted depending on site conditions through the evaluation of various beam and jointing approaches. Among the column systems applied to the study are steel column, SRC column, RC-PC column and RC column. The ways of combining with the columns addressed in the study were categorized into the rigid joint, pin joint, steel frame joint and bracket type joint. Besides, the instruction for site fabrication of beam-column was added in an effort to help set up the site fabrication procedures.

• Korean Journal of Construction Engineering and Management
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• v.16 no.5
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• pp.54-64
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• 2015

The modular construction has several advantages such as high quality of product, safe work condition and short construction duration. The manufacturing planning of modular construction should consider time frame of manufacturing, transport and erection process with limited resources (e.g., modular units, transporter and workers). The manufacturing planning of multi modular construction project manages the modular construction's characteristics and diversity of projects, as a type of modular unit, modular unit quantities, and date for delivery. However, current modular manufacturing planning techniques are weak in dealing with resource interactions and each project requirement in multi modular construction project environments. Inefficient allocation of resources during multi modular construction project may cause delays and cost overruns to construction operation. In this circumstance, this research suggest a manufacturing planning model for schedule optimization of multi project of modular construction, using genetic algorithm as one of the powerful method for schedule optimization with multiple constrained resources. Comparing to the result of the existed schedule of case study, setting optimized scheduling for multi project decrease the total factory producing schedule. By using proposed optimization tool, efficient allocation of resource and saving project time is expected.