• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.429-430
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• 2006

To estimate the fatigue life of flange-shaft assembly, fatigue test for flange material and bending fatigue test for flange-shaft assembly were conducted. Also, finite element analysis for flange-shaft assembly was conducted. Then, we have changed the obtained P-N curve to S-N curve using the finite element analysis results which were stress values at the location of fracture. The S-N curve of flange material itself was almost consistent with that of flange-shaft assembly, so it seems that the fatigue life of flange-shaft assembly could be estimated by using S-N curve for flange material and the stress at the location of fracture calculated by finite element methods.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.217-222
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• 2001

For the life evaluating of notched members, it is the best way that performing the real fatigue test of structure containing notch. But this method required generally much times and costs to evaluate fatigue life. So, generally we use the modified S-N curve or several methods to predict fatigue life. In this study, crack initiation life was evaluated by fatigue testing the SAE keyhole specimen and smooth specimen made of Al 7075-T6 alloys using the constant load then obtained S-N curve of smooth specimen and P-N curve of SAE keyhole specimen. And, fatigue lives of keyhole specimen are predicted using some life prediction methods (Nominal range I method, Nominal range II method, FEM analysis) for investigating experimented results, and that were compared with experimental data. Predicted fatigue lives by FEM analysis were corresponded with experimental data between 1/3times and 3times on the whole, and predicted fatigue lives using modified S-N curve (Nominal range I method, Nominal range II method) were nonconservative compared with that of FEM analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.123-124
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• 2007

• PNF and Movement
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• v.7 no.2
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• pp.1-10
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• 2009

This research measures the conditions of spinal scoliosis of college students and analyses the factors that affect spinal scoliosis. From September 15, 2008 to October 30, 2008, the study was conducted with 142 C College students and measured the degrees of spinal scoliosis. The analysis was evaluated according to the Pneumex Analysis program. The collected data was compiled into statistics using the SPSS PC+ 12.0 program. The results were as follows: 1. It appeared that in the cases of C curve, reverse C curve, S curve, and the normal, there was a statistical significance(p=.010) between the conditions of spinal scoliosis of the two genders. 2. It appeared that the comparison among the three groups according to the characteristics of the subjects showed a statistical significance in spinal length(p=.000) in the C curve group, age(p=.019) and spinal length(p=.004) in the reverse C curve group, and spinal length (p=.035), difference in apparent leg length(p=.019), and difference in true leg length(p=.012) in the S curve group. 3. It appeared that in the normal group without spinal scoliosis, the results of comparing the differences in apparent true leg length and spinal length according to the characteristics of the subjects showed a statistical significance in spinal length and gender(p=.000), age (p=.008), height(p=.000), and whether or not there was a regular exercise over once per week(p=.001). 4. On the correlations between C curve, reverse C curve, and S curve and differences in apparent true leg length and spinal length, it appeared that: (a) As the difference in apparent leg length gets bigger the difference in true leg length gets big in C curve(r=.551, p=.000). (b) As the difference in apparent leg length gets bigger the difference in true leg length gets big in reverse C curve(r=.511, p=.006). (c) There is no correlation in S curve.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.90-93
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• 2003

The function, which represents the closed curve, is found from the sampling data by S-System in this study. Two methods are proposed. One is the extension of S-System. The data x and y are regarded as input data, and the data z=0 as output data. To avoid the trap into the invalid function, the judgment points (x$\_$j/, y/sug j/) are introduced. They are arranged in the inside and the outside of the closed curve. By introducing this concept, the functions representing closed curve are found by S-System. This method is simple because of a little extension of S-System. It is, however, difficult for the method to find the complex function like a hand-written curve. Then another method is also proposed. It uses the system incorporating the argument function. The closed curve can be expressed by the argument function. The relatively complex function, which represents the closed curve like a hand-written curve, is found by utilizing argument function.

• The Korean Journal of Applied Statistics
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• v.12 no.1
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• pp.153-163
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• 1999

경제학분야에서 소득분배의 불균형 정도에 대한 척도로 널리 이용되는 Lorenz curve를 소개하고, 변환에 의한 Lorenz curve기법을 도입하여 통계학의 주요 주제인 모집단의 분포에 대한 추정에 적용할 수 있는지 조사한다. 여러 특정분포에 대한 변환된 Lorenz curve의 특징을 제시하고 예제로 Hodgkin’s disease 데이터를 이용하여 Q-Q 플롯과 새로 제시한 변환된 Lorenz curve를 비교한다.

• Journal of Information Technology Services
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• v.11 no.3
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• pp.89-101
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• 2012

The study investigated if IT investment in Korean financial markets for the past 18 years has grown following the s-curve pattern based on Nolan's growth model in order to find the correlation between IT investment and management performance in the financial industry. According to the research finding it can be said that the overall financial markets maintain s-curve pattern, and IT investment is related to management performance, particularly increase in total assets and net profit. However, each sector has defining features of growth patterns. The banking industry has grown similarly to the s-curve, and the insurance industry also shows the s-curve but it looks more like linear pattern. In terms of securities industry, its growth patterns can hardly be considered s-curve due to the irregular changes. his research outcome illustrates the analysis of IT growth patterns in the financial industry and thus, it is expected to be a useful reference when deciding the appropriate time for IT investment in the financial industry.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42
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• pp.68-77
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• 2000

Analyses, in which load was regarded as instant load and gradual step load, respectively, were performed with data measured on a gradually loaded field, and the results were inspected to find the effect of load conditions, and the final settlements which were predicted by Hyperbolic, Tan's, Asaoka's, and Monden's methods were compared with each other. Settlement curves in which load was regarded as instant load and gradual step load being to coincide at twice the time of duration of embankment. On the ground installed vertical drain, from the results of Hyperbolic, Tan's, Asaoka's, Monden's, Curve fitting I, and Curve fitting II (simple, carrillo) methods it was concluded that Asaoka, Curve fitting I, and Curve fitting II methods are reliable for prediction final settlement with back analysis.

• IE interfaces
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• v.7 no.3
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• pp.201-212
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• 1994

In this paper, we develop computerized procedures of the S-Curve, the cumulative progress rates of load input, applied to shipbuilding basic plan. For a real world ship yard, we study the application related problems and develop more efficient procedures of applying the curves in terms of usability and computerization. The yard currently do not have any mathematical expression for the S-Curve. They express the curves using data tables which represents data points of the manually drafted S-Curve graphs, which causes the difficulties in efficient computerization. Another problem the yard has is the lack of the feedback procedure of the actual load different from the initial plan. Due to those problems, the application procedures of the S-Curve require much time and endeavor amounting two full time employees. To resolve the problems, we develop the mathematical expression of the S-Curve using beta distribution function and the feedback procedure regenerating the planned load reflecting the difference between the initial plan and its realization. To build user friendly program, the graphic user interface is also developed using OSF/MOTIF toolkits. Through the development, we reduce the burden required in applying the curves to a part-time job of one employee.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.369-374
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• 2001

Gear is general mechanical elements that used for power transmission between two shafts that interval is comparatively short. and it delivers big power as accurate ratio of speed. The profile of Spur gear which is the most basic factor is divided into Trochoidal fillet curve and Involute curve. Involute curve is used a lot of a shaped curve of machine parts such as a gear, a scroll compressor and a collar of centrifugal pump. However, it is poor to study the modeling of Trochoidal fillet curve and the three dimensions model shaped mathematical curve. This paper describes a mathematical model of profile shifted involute gear. and this model is based on Camus's theory. We draw three dimensions gear have accurate mathematical function using ADS, VisualLISP. and To check accuracy and perfection, we make a program of checking Interference. and use for this study.