• International Journal of Automotive Technology
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• v.8 no.3
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• pp.259-268
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• 2007

A knock detection circuit that is based on the signal of an accelerometer installed on the engine block of a spark ignition automotive engine has a band-pass filter with a certain frequency as a parameter to be calibrated. A new statistical method for the determination of the frequency which is the most suitable for the knock detection in real-time applications is proposed. The method uses both the cylinder pressure and block vibration signals and is divided into two steps. In both steps, a new recursive trigonometric interpolation method that calculates the frequency contents of the signals is applied. The new trigonometric interpolation method developed in this paper improves the performance of the Discrete Fourier Transformation, allowing a flexible choice of the size of the moving window. In the first step, the frequency contents of the cylinder pressure signal are calculated. The knock is detected in the cylinder of the engine cycle for which at least one value of the maximal amplitudes calculated via the trigonometric interpolation method exceeds a threshold value indicating a considerable amount of oscillations in the pressure signal; this cycle is selected as a knocking cycle. In the second step, the frequency analysis is performed on the block vibration signal for the cycles selected in the previous step. The knock detectability, which is an individual cylinder attribute at a certain frequency, is verified via a statistical hypothesis test for testing the equality of two mean values, i.e. mean values of the amplitudes for knocking and non-knocking cycles. Signal-to-noise ratio is associated in this paper with the value of t-statistic. The frequency with the largest signal-to-noise ratio (the value of t-statistic) is chosen for implementation in the engine knock detection circuit.

• The Korean Journal of Applied Statistics
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• v.16 no.1
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• pp.87-100
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• 2003

Most of statistical data are generated by a set of dynamic, stochastic, and simultaneous relations. An important question is how to specify statistical models so that they are consistent with the dynamic feature of those data. A general hypothesis is that the lagged effect of a change in an explanatory variable is not felt all at once at a single point in time, but The impact is distributed over a number of future points in time. In other words, current control variables are determined by a function that can be reduced to a distributed lag function of past observations. It is possible to explain the relationship between variables in different points of time and to estimate the long-run impacts of a change in a variable on another if time lag series of explanatory variables are incorporated in the model specification. In this study, distributed lag structure is applied to the domestic stock market model to capture the dynamic response of the market by exogenous shocks. The Domestic market is found more responsive to the changes in foreign market factors both in the short and the long run.

• Education of Primary School Mathematics
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• v.21 no.2
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• pp.131-150
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• 2018

The structure of a mathematics task shapes the aspects of learning of those who solve the task. This study explores the process of understandings on the statistical variability of primary school students. Students were given two problems with different degrees of structuring - a well-structured problem (WSP) and an ill-structured problem (ISP) - and discussed in a group to solve each task. The highest level of development achieved in both cases appeared to be similar. However, when given the ISP, students dynamically proposed ideas and justified the conclusion based on their hypothesis. Furthermore, all students actively participated in solving the ISP until the end whereas some students were marginalized while solving the WSP. This discrepancy results from the difference in the degrees of task structuring.

• ETRI Journal
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• v.36 no.5
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• pp.714-720
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• 2014

In this paper, we propose the use of data-driven probabilistic utterance-level decision logic to improve Weighted Finite State Transducer (WFST)-based endpoint detection. In general, endpoint detection is dealt with using two cascaded decision processes. The first process is frame-level speech/non-speech classification based on statistical hypothesis testing, and the second process is a heuristic-knowledge-based utterance-level speech boundary decision. To handle these two processes within a unified framework, we propose a WFST-based approach. However, a WFST-based approach has the same limitations as conventional approaches in that the utterance-level decision is based on heuristic knowledge and the decision parameters are tuned sequentially. Therefore, to obtain decision knowledge from a speech corpus and optimize the parameters at the same time, we propose the use of data-driven probabilistic utterance-level decision logic. The proposed method reduces the average detection failure rate by about 14% for various noisy-speech corpora collected for an endpoint detection evaluation.

• Journal of Agricultural Extension & Community Development
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• v.5 no.1
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• pp.113-122
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• 1998

Community Attachment variables(specially, system model variables : gender, age, education, income, number of children, marital status, length of residence, and job) have been tested. The data for this study were collected from 295 residents of Yesan in Chungnam. The SPSSWIN package was utilized for data analysis. Frequency, percent, t-test, and ANOVA were utilized for statistical analysis. Each hypothesis was tested at .01, .05, and 01 level. The major findings of this study were: 1) the range of community attachment score was $17{\sim}56$. The mean score of community attachment was 29.8 with a standard deviation of 5.34. 2) t-test showed that job was statistically significant at .05 level among gender, marital status, and job. 3) length of residence, age, and numbers of children were statistically significant at .05, .10, and .01, respectively.

• Journal of Families and Better Life
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• v.25 no.6
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• pp.111-120
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• 2007

The purpose of this study was to investigate the relationship between householder's education level and the education expenditure for children. The Family Income and Expenditure Survey data of the 2005 National Statistical Survey were used to examine the hypothesis. For data analysis, ANOVA and regression method were applied. The results are as follows: House-holds in Seoul spent 533,000 won for child education per month on the average, and 64% of the expenditure was for private education. Households whose householder's education level was high spent more expenditures on public and private education for children than the households whose householder's education level was low. When the household income level was controlled, householder's education level affected only private education expenditure.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2255-2258
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• 2013

The activity of Rb proteins is controlled by post-translational modifications, especially through phosphorylation. Acetylation of Rb2/p130 was reported recently in NIH3T3 cells but its physiological relevance in cell cycle control and tumorigenesis is still unknown. Efforts are underway to investigate possible interplay between Rb2/p130 phosphorylation and acetylation. Here we hypothesized that Rb2/p130 acetylation, like p53 acetylation, may play a role in development of the tumor phenotype. The proposed hypothesis regarding acetylation of Rb2/p130 in tumor VS normal cells was found to be true in our case study of 36 tumor samples. Statistical analysis of results suggest strong correlation among Rb2/p130 acetylation and cancer phenotype.

• Journal of Korean Society for Quality Management
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• v.18 no.2
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• pp.117-126
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• 1990

The Purpose of this study is to grasp the general effects of measurement-related investment by industrial firms. We presupposed the hypothesis that the measurement-related investment affects the decrease of product inferiority rates and analyzed the investigation results by means of PIMS(Profit Improvement of Market Strategy) model. As the results, we found out that the firms with positive measurement-related investment showed for less inferiority rates of products considerably. This study put an emphasis on the verification results showing that the considerable increase of measurement-related investment decreases the product inferiority rate by the statistical methods.

• Journal of the Korean Home Economics Association
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• v.35 no.6
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• pp.143-155
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• 1997

The purpose of this study is to compare the differences of clothing behavior by the level of self-monitoring under given social situations. The result of this study is drown from the analysis of the survey, gathered from the 522 female students of universities reside in Seoul, by using the method of convenience sampling. The statistical methods used to test the data were MANOVA and chi-square test. The results of this study can be summarized s follows; first, as a result of analyzing the differences of situational self-image pursuits among situations depending individual's self-monitoring levels, it was found that the pursuits changes among situations regardless of the self-monitoring levels. Thus, this hypothesis could not be verified. Second, as a result of analyzing the changes of priority of clothing selection factors among situations depending on individual's self-monitoring levels, it was found that the priority factors changed among situations regardless of the self-monitoring levels.

• Journal of Information Technology Services
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• v.13 no.4
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• pp.155-168
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• 2014

This paper discussed about business ethics and innovation management performance of IT service firms in Korea. To prove empirically the research hypothesis, the statistical analysis was based on the response from the 92 IT Service firms in Korean. As analysis results, it was found that the business ethics of organizations were the effect factors of the innovation management performance. And the knowledge competency and creativity are confirmed as a mediator between the business ethics and innovation management performance. So this paper suggests that business ethics in organizations are the important factor for enhancement of IT service firm's innovation performance. Specially the mediation effects of knowledge competency and creativity variables were proved empirically for the relation between the business ethics and innovation management performance. So it is desirable that knowledge-based service firms, for example IT service firms, have to strive to upgrade their level of business ethics and to link with their creativity and knowledge competency.