• The Journal of Engineering Geology
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• v.4 no.1
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• pp.79-90
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• 1994

Development of industries and increasing population demand civil engineering projects of various types and sizes to be looated along the ooastal aaaas where extremely soft marine sedirnents are encountered. These sediments present settlement and stability problems, among others, and consequently, cost increase and schedule delay are resulted.Insulfident understanding of the basic nature of the soft formations dulling design and construction phases result in catastrophicfailures all too often. In order to provide safe and economic solutions to these problems, utilization of various related disciplines should be made for analyses. However, this paper will primarily rely in portions of paleoclimatology, sedimentology, and soil mechanics to define the problems and to provide basic understanding of the sediment, and the directions and methodology for the analyses.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.1
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• pp.78-83
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• 2011

Traditional autopilot design requires an accurate aerodynamic model and relies on a gain schedule to account for system nonlinearities. This paper presents the control architecture applied to a dynamic model inversion at a single flight condition with an on-line neural network (NN) in order to regulate errors caused by approximate inversion. This eliminates the need for an extensive design process and accurate aerodynamic data. The simulation results using a developed full nonlinear 6 degree of freedom model are presented. This paper also presents the stability evaluation for control systems to which NNs were applied. Although feedback can accommodate uncertainty to meet system performance specifications, uncertainty can also affect the stability of the control system. The importance of robustness has long been recognized and stability margins were developed to quantify it. However, the traditional stability margin techniques based on linear control theory can not be applied to control systems upon which a representative non-linear control method, such as NNs, has been applied. This paper presents an alternative stability margin technique for NNs applied to control systems based on the system responses to an inserted gain multiplier or time delay element.

• Journal of the Korean Society for Railway
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• v.15 no.1
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• pp.80-87
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• 2012

This study analyzed the quality of a commuter rail service of Incheon line 1 with respect to two service measures such as occupancy (crowdedness) and punctuality based on transit smart card data collected in 2009. In order to analyze the metro services by individual fleet, we aggregated the personal level card data into the fleet operated in each planned schedule. The results show a low level of service for both crowdedness and punctuality during peak hours at the line segment from 'Gyeyang' to 'International business district'. Further, a close relationship between vehicle occupancy and punctuality is found, which illustrates high passenger demand causes successive metro delay.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.272-273
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• 2014

Existing the free-form concrete segments (FCS) mold is produced by state of solid such as steel, wood, Styrofoam that can not be recycled. Using FCS mold result in delay on schedule and decrease of productivity because it consists of irregular curved variety and it requires more time than fixed mold. Thus, FCS mold should be developed which can reduce the costs and also it can be used as semipermanent. The aim of this study is to suggest of flexible mold production process for using the phase change materials(PCM). PCM is maintain that its solid state at low temperature but it changes phase to liquid state by heating. PCM is suitable material for flexible mold due to change of phase in relatively high temperature compare to other phase change materials such as water. Flexible mold is possible that reuse semi-permanently made by PCM. Thus, this study is proposed the process of flexible mold production for using the PCM. The study results will be used as the basic theory for studies on production and installation of FCS.

• Journal of Information Technology Applications and Management
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• v.12 no.1
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• pp.213-229
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• 2005

Cost overrun or schedule delay of the software development project happens frequently despite that software developers continue to make every effort for the effective management of the projects. Previous researches have ascertained that these problems are ascribed to the uncertainty of projects and the improper management of the projects. The purposes of this research are to investigate the impacts of user participation and task interdependence on the performance of the projects and also to find out the appropriate project management method to improve the project performance. Even though the model fitness of the path model is proved to be very high, the verification of the hypotheses showed a variety of results including the four verifications and the one refutation of the hypotheses as well as the suggestion of one alternative hypothesis. The contribution of this research is that the integration model is proposed and verified, comprising the relationship among the user participation, the task interdependence, and the performance of software development projects. A project manager can utilize the implication of this research for an effective management of software development project.

• Plant Journal
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• v.5 no.2
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• pp.62-67
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• 2009

The capability of design and engineering of global EPC companies has long been equalized through past similar construction experiences. Among various key factors in the success of EPC project, the capability of engineering is considered to be the most important factor since the engineering is preceding activities of EPC contract. The failure of engineering may adversely affect the subsequent procurement & construction activities and in turn may cause cost overrun or schedule delay. Therefore, an EPC company needs to continue to improve the engineering capabilities for the success of project. The engineering capabilities can be further improved if the EPC company should prevent recurrence of similar design faults that were previously committed. This study is intended to present how to make the most of the failure examples from previous projects towards a success of project. Failure is but a stepping stone to success. The EPC company can obtain useful lessons from the analysis of past failure examples.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.1
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• pp.29-36
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• 2016

In shipbuilding and offshore plant construction, pipe-stools of various types are installed. Moreover, these are many quantities but they must be installed in a successive manner. Due to these characteristics the pipe-stool installation processes easily tends to cause the schedule delays in the overall production processes. In order to reduce delay, the goal of this study is to predicts production’s lead time before manufacturing. Through this predictions it’s expected to reduce total production’s lead time by improving it's process. First of all, we made MLR(Multiple Linear Regression) and PLSR(Partial Least Square Regression) model to predict pipe-spool's lead time and then compared predictability of MLR and PLSR model. If a explanatory variable is added, it will be possible to predict results precisely.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.112-118
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• 2013

Air travel demand has recently been growing and establishment and operation of low-cost carriers have been increased. Against this backdrop, low-cost carriers need to figure out diversified customer demand for low-cost carriers and ways to maximize marketing efficiency before applying it to the field so that they can attain superiority to large carriers in increased intensified competition. Low-cost carriers need to be differentiated from other carriers for the purpose of improving profits. Toward this end, this study conducted analysis on importance and satisfaction with carrier choice using IPA with regard to low-cost carrier customers. In conclusion, the paper accurately examined advantages and disadvantages of low-cost carriers compared to general carriers based on results of IPA analysis and suggested managerial strategies to enhance competitiveness based on division into four parts including maintenance and enforcement (1st quadrant, Delay compensation, Booking rapidity, Check rapidity, Crew service, refund service, baggage service, punctuality, transit services, airlines images), concentrated improvement (2nd quadrant, price, Convenience of seat), passive administration (3rd quadrant, Boarding service, cabin cleanliness, flight schedule, whether local crew on board, meal service, in-flight entertainment service), and enhanced satisfaction (4th quadrant, duty-free service, Variety of routes), so that practical suggestions could be presented to employees working in the field.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.295-300
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• 2001

Additional costs as well as schedule delay are occurred due to change orders in today's construction projects. Additional costs, overhead calculation methods are of various types. In a foreign country cases, many claims related to the loss of labor productivity quote research statistics data. In domestic cases, the study of the reason why the loss of labor productivity occurs and its effect have not been performed. Therefore, this paper analyzes factors affecting lost productivity and a methodology is presented to estimate the lost productivity.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.3-6
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• 2007

Korea Aerospce Research Institute(KARI) has been developing the first civilian rocket, Korea space launch vehicle (KSLV-I), which can put the small size satellite into designated orbit. Developing launch vehicles contains a lot of uncertainty due to large scale, complexity, and technical difficulty. The uncertainty may become risk in the areas of business and technology which causes schedule delay, cost increase, and design changes of subsystems and components. This study describes the technical risk identification methods using FTA and procedures of planning and implementation of risk assessment and reduction of launch vehicle propulsion system.