• Journal of Arbitration Studies
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• v.32 no.4
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• pp.103-141
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• 2022

Traditionally, schedule analysis in Korea has been used, mainly through the Critical Path Method, to evaluate the claim for extension of time and/or the amount of liquidated damages for delay. Critical path method, however, cannot identify the delay event and its impact occurred in non-critical path especially in multi facility projects. In multi facility projects that comprise several independent but related facilities or structures, each facility has its own facility critical path the duration of which will be impacted by facility specific critical delays. Thus, only through the non-critical delay analysis along with the critical delay analysis damages not attributable to contractors may be remedied in full. Because all the records and pictures can reveal what has actually happened in post contract review, only the retrospective analysis rather than the prospective analysis based on the assumptions can establish the cause and allocate the each parties' responsibilities appropriately.

• IE interfaces
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• v.16 no.3
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• pp.344-351
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• 2003

Critical dimension is one of the most important characteristics of up-to-date integrated circuit devices. Hence, critical dimension control in a semiconductor wafer fabrication process is inevitable in order to achieve optimum device yield as well as electrically specified functions. Currently, in complex semiconductor wafer fabrication processes, statistical methodologies such as Shewhart-type control charts become crucial tools for practitioners. Meanwhile, given a critical dimension sampling plan, the analysis of variance technique can be more effective to investigating critical dimension variation, especially for on-chip and on-wafer variation. In this paper, relating to a typical sampling plan, linear statistical models are presented for the analysis of critical dimension variation. A case study is illustrated regarding a semiconductor wafer fabrication process.

• Journal of Aerospace System Engineering
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• v.9 no.1
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• pp.1-6
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• 2015

A critical speed analysis of oxidizer pump was peformed for a 7 ton class liquid rocket engine as the third stage engine of the Korea Space Launch Vehicle II. Based on the previously developed experimental 30 ton class turbopump and presently developing 75 ton class turbopump for the first and second stage rocket engine of Korea Space Launch Vehicle II, a layout and configuration of the 7 ton class turbopump rotor assembly are determined. A ball bearing stiffness analysis and rotordynamic analysis are performed for both of the bearing unloaded condition and loaded condition. Structural flexibility of the oxidizer pump casing is also included to predict critical speeds. From the numerical analysis, it is confirmed that the rotor system acquires sufficient separate margin of critical speed as a sub-critical rotor even though decrease of critical speed due to the casing structural flexibility.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.2
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• pp.60-67
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• 2018

The purpose of this study was to examine the effects of internet-use Anatomy class, as one of the Flipped learning method, on critical thinking disposition. The class for this study was conducted from March 1 to April 10, 2018. The study involved a total of 180 people in the first year of a University located in C province. Data collection was carried out before and after the Flipped learning method application. Frequency analysis, Paired t-test, Pearson correlation, and Regression analysis were used for the analysis. According to the analysis, 28.3% of men and 71.1% of women and before applying the program analysis of correlation between Flipped learning perception and critical thinking disposition showed a significant correlation between confidence(sub-component of critical thinking) only (p<.005). Comparing the scores of critical thinking before and after the program, it was found that Truth seeking (p<.001), Open-mindness (p<.005), Confidence (p<.001), Systematicity (p<.005), Analyticity (p<.001), and Inquisitiveness (p<.001) scores had increased significantly except Maturity (p>.005). And the regression analysis of Flipped learning method applying influence on critical thinking disposition were significantly affected (p<.001). Based on the results of this study, it was possible to determine that Flipped learning method had a positive effect on critical thinking disposition.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.11
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• pp.507-517
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• 2005

This paper presents the results of critical contingency analysis for the Korean power system which is performed to identify the impact of the critical contingencies on the Korean power system and set up a short term system operation planning for the purpose of preventing large scale blackout. The static and dynamic simulation is carried out for each critical contingency and the simulation results for each contingency are shown under the peak load condition for the year 2005, 2007 and 2010.

• Journal of Engineering Education Research
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• v.24 no.1
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• pp.46-52
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• 2021

The purpose of this study is to clarify that critical writing can be a positive stimulus factor for the cultivation of critical thinking through actual cases of writing education targeting engineering students in universities. Critical writing education is a very important way to develop critical thinking necessary for acquiring scientific knowledge, sharing social values, creativity and cultivating new production capacity. Especially, when critical writing education is performed with materials that maintain critical view of social reality such as the movie "Bowling for Columbine", it is characterized by the fact that it is naturally combined with the dimension of engineering ethics faced by engineers from the analysis and judgment of social reality. This is an example of the fact that critical thinking education for engineering students does not necessarily meet their major areas.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.3
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• pp.205-210
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• 2017

Critical speed analysis was conducted for a active steering bogie prototype, developed to improve the curving performance of railway vehicles. The critical speed for the design concept was about 169.2k m/h. To validate the analysis result, we performed a critical speed test for the prototype bogie using a roller-rig tester. The test results showed that the critical speed for the prototype bogie was about 165 km/h. From the analysis and test results, The critical speed for the prototype bogie was determined to be 165 km/h. Considering the maximum operating speed of the test vehicle is 100 km/h, the prototype bogie is considered stable.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.310-316
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• 2019

Fluidelastic instability is a key issue in steam generator tube bundles subjected in cross-flow. With a low flow velocity, a large amplitude vibration of the tube observed by many researchers. However, the mechanism of this vibration is seldom analyzed. In this paper, the mechanism of cross-flow effects on fluidelastic instability of tube bundles was investigated. Analysis reveals that when the system reaches the critical state, there would be two forms, with two critical velocities, and thus two expressions for the critical velocities were obtained. Fluidelastic instability experiment and numerical analysis were conducted to obtain the critical velocity. And, if system damping is small, with increases of the flow velocity, the stability behavior of tube array changes. At a certain flow velocity, the stability of tube array reaches the first critical state, a dynamic bifurcation occurs. The tube array returns to a stable state with continues to increase the flow velocity. At another certain flow velocity, the stability of tube array reaches the second critical state, another dynamic bifurcation occurs. However, if system damping is big, there is only one critical state with increases the flow velocity. Compared the results of experiments to numerical analysis, it shows a good agreement.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.361-370
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• 2015

There will inevitably be errors and uncertainties in tire yaw mark related critical speed formula, which is derived merely from the relationship between the centrifugal force and the friction force acting on the point-mass vehicle. Constructing and measuring yaw marks through appropriate simulation works have made it possible to perform uncertainty analysis in calculation of critical speeds under variation of variety of conditions and parameters while existing yaw mark experimental tests have not performed properly. This paper does not present only the critical speed analysis results for parametric sensitivity and uncertainty of chord and middle ordinate, coefficient of friction and road grade, but also modeling uncertainty such as variation of braking level during turning and vehicle size. The yaw mark analysis methods and results may be now applied in practice of traffic accident investigation.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.534-539
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• 2001

This paper presents the critical speed analysis of geogrid-reinforced rail roadbeds on soft soil. A rail roadbed on soft ground must be designed to avoid intolerable stress in the underlying soil and to give sufficient support for the rail system. At high speeds, the deformation of rail systems will gain dynamic amplification, and reach excessive values as a certain speed, here termed critical speed is approached. The elastic Winkler foundation model was used to predict the critical speed of geogrid-reinforced rail roadbeds on soft soil and the model properties were determined by the in-situ cyclic plate load test. Based on the parametric study of elastic beam on Winkler foundation model, the critical speed increase with the increase of the flexural risidity of subgrade EI and the stiffness coefficient of Winkler foundation k. From the in-situ cyclic load tests and analysis of elastic beam on Winkler foundation model, the critical speed increase with increase in number of reinforced layer and non-dimensional value for depth of first geogrid layers and the thickness of reinforced rail roadbed u/d.