• 대한기계학회논문집A
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• 제24권8호
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• pp.1991-1999
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• 2000

This research has been performed to reveal the hysteresis phenomena of the hunting motion in a railway passenger car having a bolster. Since linear analysis can not explain them, bifurcation analysis is used to predict its outbreak velocities in this paper. However bifurcation analysis is attended with huge computing time, thus this research proposes more effective numerical algorithm to reduce it than previous researches. Stability of periodic solution is obtained by adapting of Floquet theory while stability of equilibrium solutions is obtained by eigen-value analysis. As a result, linear and nonlinear critical speed are acquired. Full scale roller rig test is carried out for the validation of the numerical result. Finally, it is certified that there are many similarities between numerical and test results.

• Journal of applied mathematics & informatics
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• 제10권1_2호
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• pp.17-26
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• 2002

A stability analysis of a non-linear prey-predator system under the influence of one dimensional diffusion has been investigated to determine the nature of the bifurcation point of the system. The non-linear bifurcation analysis determining the steady state solution beyond the critical point enables us to determine characteristic features of the spatial inhomogeneous pattern arising out of the bifurcation of the state of the system.

• 기술혁신연구
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• 제5권1호
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• pp.44-66
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• 1997

This study is a critical assessment of research productivity through publication among scientists and engineers. Through the analysis of the 223 mail questionnaires collected from professors of mechanical engineering, electrical engineering, chemistry and physics, this study obtains the particular determinants of publication productivity at the science and engineering schools in Korea. The data are analyzed using correlation, ANOVA, multiple regression analysis and path analysis. The result shows that early research productivity and the number of doctoral students are very important to publish good research articles. Also the qualities of professors' Ph.D. institution and the quality of employing university are critical influencing factors to publication productivity.

• 한국항만학회지
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• 제11권2호
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• pp.281-294
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• 1997

Fatigue strength analysis is one of the most important themes of ship structure design, as fatigue damages are reported on ship structures even now. But these need basic research workes which will take time. The others are the problem to apply fatigue strength analysis in design and have to be investigated in parallel with basic researches. The one of major items in the latter is the critical damage factor to define with S-N curve for fatigue strength analysis of ship structure design.

• 디지털융복합연구
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• 제10권7호
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• pp.93-98
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• 2012

본 논문에서는 비즈니스 인텔리전트 시스템의 구축 후 활용 효과에 영향을 미치는 요인들을 분석하였다. 이를 위하여 우선 비즈니스 인텔리전트 시스템에 영향을 미칠 수 있는 여러 요인들을 문헌 연구를 통해서 정리 하였고, 이를 검증하기 위하여 비즈니스 인텔리전트 시스템을 구축하여 활용하고 있는 기업을 대상으로 인터넷 설문을 실시하여 필요한 데이터를 수집하였다. 본 논문의 목적을 달성하기 위하여 요인분석(FA)과 계층분석기법(AHP)분석을 실시하였다. 요인분석을 통해서 성과측정지표들의 차원이 감소된 요인을 도출하였고, 이들 요인들 사이의 중요도를 계층분석기법(AHP)으로 분석하였다. 본 연구의 결과로 본 연구를 통해서 생성된 요인은 모두 6가지이다. 비즈니스 인텔리전트 시스템의 성과에 영향을 미치는 요인들은 정보시스템의 성숙도가 제일 중요한 요인으로 나타났으며, 경영전략의 수립 필요성, 정보조직, 그리고 사용자 교육의 순서로 나타났다. 본 연구는 기업에서 비즈니스 인텔리전트 시스템을 구축하여 사용하고 있거나, 미래에 비즈니스 인텔리전트 시스템을 구축하려는 계획을 가지고 있는 기업에게 비즈니스 인텔리전트 시스템의 활용에 대한 방향을 제시해 줄 것으로 기대된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.98-115
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• 2012

New trend called ubiquitous leads the recent business by standardization and integration. It should be the main issue how to guarantee the integration and accountability on each business, especially in mission critical system which is mainly supported by M2M (Machine to Machine) control mechanism. This study is from the analysis of digital forensics case study that is from the M2M Sensing Control Mechanism problem of the "Imjin River" case in 2009, where a group of family is swept away to death by water due to M2M control error. The ubiquitous surroundings bring the changes in the field of criminal investigation to real time controls such as M2M systems. The needs of digital forensics on M2M control are increasing on every crime scene but we suffer from the lack of control metrics to get this done efficiently. The court asks for more accurately analyzed results accounting high quality product development design. Investigators in the crime scene need real-time analysis against the crime caused by poor quality of mission critical systems. It seems to be every need of Real-Time-Enterprise, so called ubiquitous society on the case. We try to find the efficiency and productivity in discovering non-functional design defects in M2M convergence products focusing on three metrics in study model with quick implementation. Digital forensics system in present status depends on know-how of each investigator and is hard to expect professional analysis on every field. This study set up a hypothesis "Co-working of professional investigators on each field will qualify Performance and Integrity" especially in mission critical system such as M2M and suggests "Online co-work analysis model" to efficiently detect and prevent mission critical errors in advance. At the conclusion, this study proved the statistical research that was surveyed by digital forensics specialists around M2M crime scene cases with quick implementation of dash board.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.215-220
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• 2001

The objective of this study is to examine the fracture characteristics of concrete at early ages such as critical stress intensity factor, critical crack-tip opening displacement, fracture energy based on the concepts of the effective-elastic crack model and the cohesive crack model. A wedge splitting test for Mode I was performed on cubic wedge specimens with a notch at the edge. By varying strength and age, load-crack mouth opening displacement curves were obtained and the results were analyzed by linear elastic fracture mechanics. The results from the test and analysis showed that critical stress intensity factor and fracture energy increased, and critical crack-tip opening displacement decreased with concrete age from 1 day to 28 days. The obtained fracture parameters at early ages may be used as a fracture criterion and an input data for finite element analysis of concrete at early ages.

• 한국정밀공학회지
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• 제19권8호
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• pp.126-133
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• 2002

The cutting thickness of ultra-precision machining is generally very small, only a few micrometer or even down to the order of a few nanometer. In such case, a basic understanding of the mechanism on the micro-machining process is is necessary to produce a high quality surface. When machining at very small depths of cut, metal flow near a rounded tool edge become important. In this paper a finite element analysis is presented to calculate the stagnation point on the tool edge or critical depth of cut below which no cutting occurs. From the simulation, the effects of the cutting speed on the critical depths of cut were calculated and discussed. Also the transition of the stagnation point according to the increase of the depths of cut was observed.

• 시스템엔지니어링학술지
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• 제16권1호
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• pp.84-97
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• 2020

This paper aims to develop an optimized inventory management method for safety critical Instrument and Control (I&C) components. In this regard, the paper focuses on estimating the consumption rate of I&C components using demand forecasting methods. The target component for this paper is the Foxboro SPEC-200 controller. This component was chosen because it has highest consumption rate among the safety critical I&C components in Korean OPR-1000 NPPs. Three analytical methods were chosen in order to develop the demand forecasting methods; Poisson, Generalized Linear Model (GLM) and Bootstrapping. The results show that the GLM gives better accuracy than the other analytical methods. This is because the GLM considers the maintenance level of the component by discriminating between corrective and preventive.

• 대한산업공학회지
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• 제41권2호
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• pp.144-149
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• 2015

In this study, the effective technology readiness assessment (TRA) method for system development project is suggested. We analyze the domestic and foreign TRA practice and derive the new idea to resolve the problems found from the analysis. Domestic and foreign organizations develop and use checklist for the precise TRA, but the checklist has some problems in type of questions and analysis of assessment. TRA method using the original TRL definition or the checklist should be selected depending on the project characteristic. Questions of the checklist should be classified into critical or non-critical according to their importance. Finally, Test and evaluation master plan (TEMP) in system engineering process can provide an obvious criteria to assess technology readiness level (TRL) of critical technology elements (CTE) composing the system.