• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.393-393
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• 2000

FTA(Fault Tree Analysis) is a safety analysis method that focuses on one particular accident or main system failure and provides a method of determining causes of that event. While most of the statistical and cut set analysis have been automated, actual construction of the fault-tree is usually done manually. Manual construction of the fault-tree is extremely time consuming and it requires high level of expertise and experience. In addition to the time involved, different analyst often produces different fault-trees either by incorrect logic or omission of certain events. Automatic fault-tree construction system can be efficient in solving above problems. This study presents a new Digraph-FT conversion algorithm that leads automatic FTA system.

• Journal of Information Technology Applications and Management
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• v.9 no.1
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• pp.111-126
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• 2002

The purpose of this research is to study the effectiveness of applying Information technology to education, so-called education informatization. Education informatiantion consists of building information infrastructure, educational course operation and improvement of the teacher's ICT ( Information and Communication Technology) ability to consolidate and teach educational information development and diffusion. In this study, we've studied the effects of the use of IT on the improvement of student's class Participation and understanding level, We set the hypotheses and tested them. A method of teaching and learning using IT influences the degree of class participation. Educational courses and a method of teaching and learning have been proved to affect the understanding of a lecture. Also, we validated the educational effectiveness on the educational course and class teaching by setting WIS (Weighted least square) on the IT utilization time.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.9
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• pp.861-868
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• 2016

Dummy messages are usually generated for faking in preserving the location privacy of a sink or source against the global eavesdropping in wireless networks. In this paper, we propose a new method in which a certain number of nodes determined by considering the required privacy level are made to transit to the dormant state doing nothing so that the total number of dummy messages is reduced, while the paths from the sink to the sources are ensured. Through simulation we verify the success ratio of path establishments between the sink and a set of sources and the location privacy level of them.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.570-575
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• 2023

Demand and necessity for eco-friendly offshore wind farms have been increasing. Research on submarine cables is constantly being considered for a reliable and stable power transmission. This study aimed to evaluate the thermal aging characteristic of submarine cables inside the J-tube of offshore wind farms. In this study, a submarine cable was set in three sections: The first is the part exposed to the air above the sea level at high temperature. The second is the section exposed to repeated temperature fluctuation as the sea level rises and falls. The third is the part submerged at low temperature below the sea level. Aged samples were tested by using the method of electrical evaluation to obtain insulation characteristics. The experimental results show that the dielectric breakdown of the sample with temperature fluctuation was 7% lower than the sample with a constant temperature; thereby, demonstrating that the section where the temperature fluctuation occurred in the submarine cables was weaker than the other. The sections of submarine cable with temperature fluctuations are believed as a weak point during operation; therefore, this part should be monitored preferentially.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.2
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• pp.184-189
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• 2013

In this paper, we propose the injurious moving picture filtering system using certain sounds contained in the injurious moving picture to filter injurious moving picture which is distributed without limitation in internet and internet storage space. For this purpose, the Gaussian Mixture Model which can well represent the characteristics of the sound, is used and frame level likelihood estimation is used to calculate the likelihood between filtering target data and the sound models. Also, the pruning method which can real-time proceed by reducing the comparing number of data, is applied for real-time processing, and MWMR method which showed good performance from existing speaker identification, is applied for the distinguish performance of high precision. In the identification experiment result, in case of the frame rate which is the proportion of total frame to high likelihood frame, is set to 50%, identification error rate is 6.06%, and in case of frame rate is set to 60%, error rate is 3.03%. As the result, the proposed system can distinguish between general and injurious moving picture effectively.

• Korean small business review
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• v.43 no.1
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• pp.147-164
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• 2021

This study focuses on succession in a family business which is the crucial factor affecting future and survival of a family business. Especially, the study concentrate a successor's view which is regarded as a key-player during the succession. In this study, we used AHP (Analytic Hierarchy Process) methodology to identify priorities of factors influencing succession. We divided into two-tier level. The first-tier is defined as 1) the relationship with an incumbent CEO, 2) a successor 's management ability, 3) a successor' s self-efficacy and 4) succession plan. For the second-tier of each first-tier have 3 sub-factors ; 1) the relationship with an incumbent CEO is set as level of mutual trust, sharing the vision of a company, and level of communication each other. 2) A successor 's management ability is based on business competence, education and training and interpersonal management ability, 3) a successor 's self-efficacy was set as successor' s willingness of succession, confidence of overcoming crisis and confidence of achieving objectives. Lastly, 4) a succession plan is set as finance plan, leadership transformation plan and human-organization management plan. A total of 93 questionnaires is distributed and retrieved, and 88 questionnaires are used for the study, excluding those with missing data. As a result of this study, successors selected 1) the relationship with an incumbent C.E.O. as the most important priority in the first-tier. The second is 2) a successor 's management ability, the third is 3) a successor' s self-efficacy, and the last priority is 4) a succession plan. In particular, 3 sub-factors that make up the relationship with an incumbent are the most important factors. These factors rank the first to the third in the final result.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.2
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• pp.71-78
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• 2003

This research proposes an implementation method of linearized equations of motion for multibody systems with closed loops. The null space of the constraint Jacobian is first pre-multiplied to the equations of motion to eliminate the Lagrange multiplier and the equations of motion are reduced down to a minimum set of ordinary differential equations. The resulting differential equations are functions of all relative coordinates, velocities, and accelerations. Since the variables are tightly coupled by the position, velocity, and acceleration level coordinates, direct substitution of the relationships among these variables yields very complicated equations to be implemented. As a consequence, the reduced equations of motion are perturbed with respect to the variations of all variables, which are coupled by the constraints. The position velocity and acceleration level constraints are also perturbed to obtain the relationships between the variations of all relative coordinates, velocities, and accelerations and variations of the independent ones. The Perturbed constraint equations are then simultaneously solved for variations of all variables only in terms of the variations of the independent variables. Finally, the relationships between the variations of all variables and these of the independent ones are substituted into the variational equations of motion to obtain the linearized equations of motion only in terms of the independent variables variations.

• Journal of Biomedical Engineering Research
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• v.22 no.4
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• pp.369-375
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• 2001

The statistical regression model is one of the most frequently used clinical analysis methods. It has basic assumption of linearity, additivity and normal distribution of data. However, most of biological data in medical field are nonlinear and unevenly distributed. To overcome the discrepancy between the basic assumption of statistical model and actual biological data, we propose a new analytical method based on artificial neural network. The newly developed multilayer perceptron(MLP) is trained with 120 data set (60 normal, 60 patient). On applying test data, it shows the discrimination power of 0.76. The diabetic risk factors were also identified from the MLP neural network model and the logistic regression model. The signigicant risk factors identified by MLP model were post prandial glucose level(PP2), sex(male), fasting blood sugar(FBS) level, age, SBP, AC and WHR. Those from the regression model are sex(male), PP2, age and FBS. The combined risk factors can be identified using the MLP model. Those are total cholesterol and body weight, which is consistent with the result of other clinical studies. From this experiment we have learned that MLP can be applied to the combined risk factor analysis of biological data which can not be provided by the conventional statistical method.

• Journal of the Korean Society of Safety
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• v.21 no.5 s.77
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• pp.53-59
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• 2006

Standard safety management costs can not be applied to each site with same rate, it is very difficult, because it depends on the experience, work method, work kind, work progress schedule, and hazard level of each construction company. Therefore, this study is to find out hazard level of each work kinds through questionnaire and interview and investigate analyze the status which standard safety management costs have been used. Also, this study is to show reasonable rates of standard safety management costs in construction industry and to set up countermeasures against those problem after reviewing its status in korea with in Japan and Europe. The domestic system of standard safety management costs is not considered in the foreign country, while only related subjective items have been investigated and evaluated for this study. This study is to investigate eleven project kinds of domestic system, first, and to investigate eleven items of apartment bldg, office, civil work such as bridge, tunnel, dam, plant etc, secondly. Additionally, three items of gymnasium, railway, particular steel tower are investigated in this study. Also this study is to investigate and analyze performed costs of presently processing worker finished work so that it shows a new reasonable rate against standard safety management costs in construction industry, in order to make basial data and material to be systemized.

• Communications of Mathematical Education
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• v.22 no.4
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• pp.471-487
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• 2008

Inventive mathematical thinking, original mathematical problem solving ability, mathematical invention and so on are core concepts, which must be emphasized in all branches of mathematical education. In particular, Polya(1981) insisted that inventive thinking must be emphasized in a suitable level of university mathematical courses. In this paper, the author considered two cases of inventive problem solving ability shown by his many students via real analysis courses. The first case is about the proof of the problem "what is the derived set of the integers Z?" Nearly all books on mathematical analysis sent the question without the proof but some books said that the answer is "empty". Only one book written by Noh, Y. S.(2006) showed the proof by using the definition of accumulation points. But the proof process has some mistakes. But our student Kang, D. S. showed the perfect proof by using The Completeness Axiom, which is very useful in mathematical analysis. The second case is to show the infinite countability of NxN, which is shown by informal proof in many mathematical analysis books with formal proofs. Some students who argued the informal proof as an unreasonable proof were asked to join with us in finding the one-to-one correspondences between NxN and N. Many students worked hard and find two singled-valued mappings and one set-valued mapping covering eight diagrams in the paper. The problems are not easy and the proofs are a little complicated. All the proofs shown in this paper are original and right, so the proofs are deserving of inventive mathematical thoughts, original mathematical problem solving abilities and mathematical inventions. From the inventive proofs of his students, the author confirmed that any students can develope their mathematical abilities by their professors' encouragements.