• International conference on construction engineering and project management
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• 2007.03a
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• pp.130-139
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• 2007

This paper presents a study on risk analysis in terms of contractor's costs in construction phase in which Crystal ball (software of Decisioneering, UK) has been utilized as a main tool. To realize it, a questionnaire survey has been carried out to identify the dominant factors that strongly influence contractor costs in Vietnam. Based on results of questionnaire investigation, the survey identified three factors which were duration of each construction task, costs of reinforcing steel, and cement. Then a spreadsheet model was created in order to analyze risks. The study also indicates that the cost of reinforcing steel and cement are the cause of risks for contractors. According to the suggested model, contractors may foresee the probability of completion within the approved budget, and the possibility of earning in accordance with owner's payment conditions.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.599-599
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• 2015

This research attempts to resolve the construction delay issues of indirect delays by developing the "Delay Responsibility Determination Model" (DRM) based on probabilistic risk analysis. DRM is envisioned to provide a way of quantitatively analyzing impacts of delayed activities while considering both direct and indirect influences. With the successful development of DRM, it would be possible to present relative probabilistic measures to all the related stakeholders in terms of their contributions to schedule delays. Upon the development completion of DRM, "Korean Construction Delay Claim/Dispute Resolution Protocols" will also be prepared to facilitate the effective use of DRM.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.166-168
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• 2015

Line of Balance (LOB) method is suitable to schedule construction projects composed of repetitive activities. Since existing LOB based repetitive project scheduling methods are deterministic, they do not lend themselves to handle uncertainties involved in repetitive construction process. Indeed, existing LOB scheduling dose not handle variability of project performance indicators. In order to bridge the gap between reality and estimation, this study provides a stochastic LOB based scheduling method that allows schedulers for effectively dealing with the uncertainties of a construction project performance. The proposed method retrieves an appropriate probability distribution function (PDF) concerning project completion times, and determines favorable start times of activities. A case study is demonstrated to verify and validate the capability of the proposed method in a repetitive construction project planning.

• Korean Journal of Construction Engineering and Management
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• v.6 no.4 s.26
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• pp.80-90
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• 2005

Activity durations retain probabilistic and stochastic natures due to diverse factors causing the delay or acceleration of activity completion. These natures make the final project duration to be a random variable. These factors are the major source of financial risk. Extending the Stochastic Project Scheduling Simulation system (SPSS) developed in previous research; this research presents a method to estimate how the final project duration behaves when activity durations change randomly. The final project cost is estimated by considering the fluctuation of indirect cost, which occurs due to the delay or acceleration of activity completion, along with direct cost assigned to an activity. The final project cost is estimated by considering how indirect cost behaves when activity duration change. The method quantifies the amount of contingency to cover the expected delay of project delivery. It is based on the quantitative analysis to obtain the descriptive statistics from the simulation outputs (final project durations). Existing deterministic scheduling method apply an arbitrary figures to the amount of delay contingency with uncertainty. However, the stochastic method developed in this research allows computing the amount of delay contingency with certainty and certain degree of confidence. An example project is used to illustrate the quantitative analysis method using simulation. When the statistical location and shape of probability distribution functions defining activity durations change, how the final project duration and cost behave are ascertained using automated sensitivity analysis method

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.137-147
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• 2018

This study is a descriptive evaluation of the differences in biomedical ethics consciousness, related knowledge, awareness, and attitude of nursing college students according to the completion of biomedical ethics education. The data were collected from 112 nursing students using self-report questionnaires and analyzed by t-test, Chi-Square test, Fisher's exact probability test and Pearson's correlation coefficient using SPSS 21.0. There were significant differences between the two groups in the sub-domains of biomedical ethics consciousness, artificial insemination, euthanasia and organ transplantation. The biomedical ethics consciousness was positively correlated with attitudes toward human tissue donation and transplantation, awareness of death, and awareness of hospice palliative care. The results of this study showed that after participating in the biomedical ethics education, nursing college students had statistically significant differences in the consciousness of artificial insemination, euthanasia, and organ transplantation. Moreover, the consciousness of biomedical ethics was related to attitude toward human tissue donation and transplantation and awareness of hospice palliative care. Based on the results of this study, we would like to suggest the need for development of various curricula related to death, hospice palliative care, human tissue donation and transplantation in the biomedical ethics curriculum. In addition, as the study was conducted in a single college, it is difficult to generalize the results; therefore, additional studies at different facilities are recommended.

• International Journal of Safety
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• v.1 no.1
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• pp.36-42
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• 2002

This paper is aimed at predicting the life of rubber insulating gloves under normal operating stresses from relatively rapid test performed at higher stresses. Specimens of rubber insulating gloves are subject to multiple stress conditions, i.e. combined electrical and thermal stresses. Two modes of electrical stress, step voltage stress and constant voltage stress are used in specimen aging. There are two types of test for electrical stress in this experiment: the one is Breakdown Voltage (BDV) test under step voltage stress and thermal stress and the other is lifetime test under constant voltage stress and temperature stress. The ac breakdown voltage defined as the break-down point of insulation that leakage current excesses a limit value, l0mA in this experiment, is determined. Because the very high variability of aging data requires the application of statistical model, Weibull distribution is used to represent the failure times as the straight line on Weibull probability paper. Weibull parameters are deter-mined by three statistical methods i.e. maximum likelihood method, graphical method and least squares method, which employ SAS package, Weibull probability paper and FORTRAN, respectively. Two chosen models for predicting the life under simultaneous electrical and thermal stresses are inverse power model and exponential model. And the constants of life equation for multistress aging are calculated using numerical method, such as Gauss Jordan method etc.. The completion of life equation enables to estimate the life at normal stress based on the data collected from accelerated aging test. Also the comparison of the calculated lifetimes between the inverse power model and the exponential model is carried out. And the lifetimes calculated by three statistical methods with lower voltage than test voltage are compared. The results obtained from the suggested experimental method are presented and discussed.

• The Transactions of the Korea Information Processing Society
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• v.7 no.8S
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• pp.2608-2619
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• 2000

This paper proposes the Handover Scheme for the mobile and describes the result of the performance analysis. In the conventional scheme of handover request, the withdrawal of terminal may occur because handover request is performed based on fixed signal level without considering network load and terminal mobility. The proposed scheme offers the minimization of withdrawal and handover blocking probability by means of the handover request of terminal based on the network load and terminal mobility. Conventional handover scheme has the sequential procedure that network performs resource check and path rerouting on the handover by MT(Mobile Terminal). Proposed handover scheme pre-processes the resource check before the handover request by predicting the handover request timo so that handover latency can be reduced. Moreover, path optimization is executed after the completion of handover in order to reduce handover latency. The rdduction of handover latency prevents the dropping of service by minimizing backward handover blocking. In summary, we propose the prediction of handover request time and decision method based on terminal, validating the performance of proposed scheme considering various cases of simulation.

• The Journal of Korean Association of Computer Education
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• v.23 no.1
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• pp.29-36
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• 2020

Various items were used as evaluation tools that identify the student's abilities accurately to confirm the completion of learning. Among them, the multiple choice item has the advantages of high objectivity and reliability in scoring, but it cannot remove the factor of guessing. In this paper, the multiple choice items are classified into two types according to the relationship between the questionnaire and the choices. One is the type used in the classical test theory with the probability of guessing 1/k for k choices and the other is the novel proposed type which introduces the concept of partial knowledge. In the proposed type, the probability of guessing when the number of knowledge i is (i+1)/k for k choices. Based on the assumptions of the previous theories about multiple choice items, we derive the guessing parameter about the proposed type. And we analyzed the effect of the guess on the correct answer in the existing type and the proposed type. This shows that the proposed type has more question guessing than the existing type.

• Journal of Ocean Engineering and Technology
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• v.32 no.2
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• pp.106-115
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• 2018

The forward and afterward parts of ships and offshore structures are designed to improve the fuel consumption performance. These are made of curved plates with a large thickness. If a fabricated curved plate has some dimensional errors, a lot of additional cost is incurred in the assembly process. Thus, an accurate dimensional assessment is very important for fabrication. In this paper, we propose an assessment method for the dimensional quality management of curved plates. This can be applied to data measured using a variety of three-dimensional instruments, with boundary measurement points automatically classified and sorted to create a measurement surface. The assessment is evaluated after matching the CAD surface and the measured surface considering constrained conditions. The fabrication assessment is evaluated as a probability of how much the tolerance is satisfied.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.729-738
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• 1995

We consider a priority-based packet-switching system with three phases of the packet transmission time. Each packet belongs to one of several priority classes, and the packets of each class arrive at a switch in a Poison process. The switch transmits queued packets on a priority basis with three phases of preemption mechanism. Namely, the transmission time of each packet consists of a preemptive-repeat part for the header, a preemptive-resume part for the information field, and a nonpreemptive part for the trailer. By an exact analysis of the associated queueing model, we obtain the Laplace-Stieltjes transform of the distribution function for the delay, i.e., the time from arrival to transmission completion, of a packet for each class. We derive a set of equations that calculates the mean response time for each class recursively. Based on this result, we plot the numerical values of the mean response times for several parameter settings. The probability generating function and the mean for the number of packets of each class present in the system at an arbitrary time are also given.