• Journal of Applied Reliability
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• v.15 no.2
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• pp.90-100
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• 2015

Reliability growth rate (or reliability growth curve slope) have the two cases of trend as a constant or changing one during the reliability growth testing. The changing case is very common situation. The reasons of reliability growth rate changing are that the failures to follow the NHPP (None-Homogeneous Poisson Process), and the solutions implemented during test to break out other problems or not to take out all of the root cause permanently. If the changing were big, the "Goodness of Fit (GOF)" of reliability growth curve to test data would be very low and then reduce the accuracy of assessing result with test data. In this research, we are using Duane model and AMSAA model for assessing test data and projecting the reliability level of complex and repairable system as like construction equipment and vehicle. In case of no changing in reliability growth rate, it is reasonable for reliability engineer to implement the original Duane model (1964) and Crow-AMSAA model (1975) for the assessment and projection activity. However, in case of reliability growth rate changing, it is necessary to find the method to increase the "GOF" of reliability growth curves to test data. To increase GOF of reliability growth curves, it is necessary to find the proper parameter calculation method of interesting reliability growth models that are applicable to the situation of reliability growth rate changing. Since the Duane and AMSAA models have a characteristic to get more strong influence from the initial test (or failure) data than the latest one, the both models have a limitation to contain the latest test data information that is more important and better to assess test data in view of accuracy, especially when the reliability growth rate changing. The main objective of this research is to find the parameter calculation method to reflect the latest test data in the case of reliability growth rate changing. According to my experience in vehicle and construction equipment developments over 18 years, over the 90% in the total development cases are with such changing during the developing test. The objective of this research was to develop the newly assessing method and the process for GOF level increasing in case of reliability growth rate changing that would contribute to achieve more accurate assessing and projecting result. We also developed the new evaluation method for GOF that are applicable to the both models as Duane and AMSAA, so it is possible to compare it between models and check the effectiveness of new parameter calculation methods in any interesting situation. These research results can reduce the decision error for development process and business control with the accurately assessing and projecting result.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.269-271
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• 2012

To investigate emission characteristics of laminar premixed CH4/air flame, combustion experiments were conducted at three flow rates (5.3L/min, 10.6L/min, 15.5L/min) with changing the combustor pressure(-30Kpa-30Kpa). It was found that with increasing flow rate, NOx emission increased in high pressure condition, while decreased in low pressure condition; and the emission of CO decreased with increasing flow rate. For the influence of pressure, emission of NOx increased with increasing pressure regardless of flow rates, while CO emission decreased on the contrary.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.4
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• pp.366-371
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• 2014

The neural network pitch controller using changing rate of generator speed has been suggested in this paper to regulate wind turbine power above the rated wind speed. The changing rate of generator speed is used in the suggested pitch controller as well as the difference between the rated and current generator speed. Matlab/simulink has been used for simulations and it has been shown that the suggested pitch controller regulates generator speed as the rated speed of 122.9[rad/s].

• Journal of Internet Computing and Services
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• v.21 no.4
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• pp.77-85
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• 2020

The purpose of this study is to explore the changing trajectory of using educational media through longitudinal data analysis. We categorize the feature of using educational media as usage for learning, usage for information, and usage for the game. We explore the longitudinal changing patterns of usage for learning, usage for information, and usage for the game by LGM(Longitudinal Growth Modeling). We also find the gender difference between these longitudinal changing trajectories. We used 3,499 samples of KYPS middle school second-grade panel data. We found these results: (a) Both usage for learning and information are statically significant variability in initial level and rate of change. Both of the changing trajectories have increased. (b) Girls have a higher rate of the change both in the usage of learning and information than boys over time. (c) There is a statistically significant individual variability in initial levels and rate of change in the usage of the game over time. (d) Boys have a higher rate of initial value than girls in the usage of games, but there is no significant difference in the rate of changing trajectories.

• Journal of Yeungnam Medical Science
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• v.3 no.1
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• pp.81-85
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• 1986

Observation of changing pattern of blood pressure and pulse rate of enflurane anesthesia for 200 cases operations, performed during the past 4 years(1983~1986) in Yeungnam University Hospital have been evaluated clinically. In order to observe the influence of enflurane upon the blood pressure and pulse rate during general anesthesia, the authors prepared a formula, expressing changing of blood pressure and pulse rate by time series and analyzed the types and distribution pattern in the experiment. The results obtained were as follows : 1. Blood pressure and pulse rate were increased at the time of intubation. 2. Generally, blood pressure and pulse rate were increased at the time of intubation and then stabilized withing 20 minutes. 3. Most common patterns were identified, ADEE type was 73~74%, Which is most common type and AEEE type was about 40%.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.415-419
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• 1997

The left ventricular relaxation rate is used as a golden standard which describes the left ventricular diastolic unction. So far, to get the rate of relaxation one should calculate the data after full recording, that is, off-line method. Therefore one cannot get the rate of relaxation in real-time while changing loading condition or infusing drug. But real time monitoring of the relaxation rate is necessary while changing loading condition or infusing drug to control the mechanics of heart and to get more information. We propose a new criterion to get the left ventricular relaxation rate and a real time algorithm. By comparison, it was turned out that our criterion outperforms others criterion.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.3
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• pp.100-105
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• 1984

The optimal Load-Frequency Control law is presented with the performance criterion which includes the changing rate of governor speed. The authors propose two controllers. One is a dynamic controller using the method of state augmentation and the other is a constant gain controller with use of the trace function lemma by Kleinman. For a more practical realization, a reduced-order Luenberger observer is applied in order to identify unmeasurable states and power demand. The control schemees presented here are tested through the model developed by Elgerd, and the usefulness is demonstrated.

• Journal of Power System Engineering
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• v.21 no.6
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• pp.110-116
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• 2017

Recently the global warming caused by greenhouse gas has emerged as a global environmental problem. For this reason the continued efforts to reduce greenhouse gas emission by international cooperation and each country are in progress. Climate changing has been recognized as the world economy development from fossil fuel use is the culprit. The international maritime organization marine environment protection committee of the global warming reduction emerged restrictions on air pollution have been strengthened. Therefore, the author has investigated the effects of fuel temperature on the characteristics of combustion and performance, using an four-cycle, six cylinders and direct injection diesel engine. The results of cylinder pressure, rate of pressure rise, rate of heat release and specific fuel consumption were increased by changing of fuel temperature.

• Composites Research
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• v.13 no.5
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• pp.10-17
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• 2000

The fatigue properties of short nylon66 fiber reinforced Chloroprene rubber have been investigated as functions of interphase conditions and fiber content. The spring constant of rubber decreased about 21% after the fatigue test. On the contrary, that of reinforced rubber increased in all cases. The changing rate of spring constant for reinforced rubber decreased with increasing fiber content. This means that the better interphase condition, the smaller changing rate of spring constant. Temperature of matrix increased about 2.5 times and one of reinforced rubber showed 1.7∼2 times up after the test. The changing rate of temperature for reinforced rubber during fatigue test decreased with increasing fiber content. It is found that the better interphase condition, the smaller changing rate of specimen temperature at the same fiber content. Double coatings of bonding agent 402 and rubber solution became the best interphase model in this study. And, we have investigated the possibility of applying short-fiber reinforced rubber to automotive engine mount rubber, bush and stopper.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.301-306
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• 2013

The Ratio of APT jeonse to purchase price was still rising. The interaction of APT Purchase and Jeonse price indices by region analysis in order to analyze this phenomenon, and results were summarized as follows. First, because the regional APT purchase and jeonse prices appears the rise and fall differently by region, regional polarization was deepening. Second, the recently real estate market was analyzed the province's booming real estate and the downturn of the metropolitan area. So, the ratio of APT jeonse to purchase price was continued to rise. Finally, the Ratio of APT jeonse to purchase price changing rate is (+) increased if the APT purchase price changing rate is larger then the APT purchase price changing rate and smaller then is (-) decreased.