• Steel and Composite Structures
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• v.49 no.4
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• pp.431-440
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• 2023

The functionally graded (FG) porous plates are usually characterized by the non-symmetric elastic modulus distribution through the thickness so that the plate neutral surface does not coincide with the mid-surface. Nevertheless, the conventional analysis models were mostly based on the plate mid-surface so that the accuracy of resulting numerical results is questionable. In this context, this paper presents the neutral surface-based static and free vibration analysis of FG porous plates and investigates the differences between the mid- and neutral surface-based analysis models. The neutral surface-based numerical method is formulated using the (3,3,2) hierarchical model and approximated by the last introduced natural element method (NEM). The volume fractions of metal and ceramic are expressed by the power-law function and the cosine-type porosity distributions are considered. The proposed numerical method is demonstrated through the benchmark experiment, and the differences between two analysis models are parametrically investigated with respect to the thickness-wise material and porosity distributions. It is found from the numerical results that the difference cannot be negligible when the material and porosity distributions are remarkably biased in the thickness direction.

• Journal of the Korean Home Economics Association
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• v.37 no.8
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• pp.55-72
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• 1999

The purpose of this study is to identify the levels of informationized life of individual, consumers knowledge and attitudes to informationized society, and the recognition of consumer problems in informationized society, and to investigate the related variables. Data were collected from 693.consumers living in Seoul using the constructed questionnaires by the authors. Frequency, Percentage and Multiple Regression Analysis were applied for the analysis. The level of informationized life of consumers was lower than the mid-point of the scale, the level of the consumers knowledge about informationized society was sightly higher than mid-point of the scale, and the consumer attitudes to informationized society appeared to be positive. The level of the recognition of consumer problems in informationized society was higher than the mid-point of the scale,and was influenced by job, age of consumers, and the level of consumers knowledge about informationized society.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.371-376
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• 2017

In this paper, we propose a magnetic resonant WPT(wireless power transfer) scenario using a large coil resonating at 6.78 MHz, and compare the characteristics through a three-dimensional electromagnetic field simulation and a magnetic resonant WPT equivalent circuit. The magnetic resonant WPT equivalent circuit proposed in this paper considers the parasitic capacitance generated between the coils in addition to the conventional equivalent circuit. Based on this analysis, we fabricated the magnetic resonant WPT coil and compared it with simulation prediction. As a result of comparison, the transfer characteristics and the resonance frequency shift can be predicted. Error proposed characteristics of equivalent circuit for the magnetic resonant WPT and the measured values are estimated to be ${\Delta}{\mid}S11{\mid}=1.31dB$ and ${\Delta}{\mid}S21{\mid}=1.21dB$, respectively.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.362-367
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• 1987

Cylinder pressure level is defined the value of sound pressure level derived from relations of pressure and frequency which are obtained Fourier series expansion of cylinder pressure. CPL is alone in general use in combustion analysis without regarding attenuation coefficient determined by engine structure because it is almost constant in various kinds of engines. Combustion pressure fluctuation and influence of CPL was investigated in this paper using Wiebe combustion function superposition th obtain the effect of premixed and diffusive combustion. The results are as follow. (1) Influence of combustion maximum pressure(P$\sub$max/) on CPL is correspond with total energy per cycle well. (2) P$\sub$max/, .DELTA.P$\sub$max/, (dp/d.theta.)$\sub$max/ and (d$\^$2/p/d.theta.$\^$2/)$\sub$max/ are very effective on CPL in the range of low frequency, mid-low frequency, mid-high frequency and high frequency respectively.

• Journal of Families and Better Life
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• v.7 no.1
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• pp.97-118
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• 1989

The purpose of this study is to clarify the definition of middle age, to compare the different perspectives about mid-life crisis, and to identify the variables that cause the mid-life crisis of men and women.. For this purpose reviewing literatures and emprical research were conducted. For the emprical research, Mid-life Crisis Scale, Mid-life Indentity Scale, Family Relation Scale. Health Scale and Religious Scale were developed. The Sample was selected form the men and women living in Seoul, whose age is from 40 to 59 , and whose last child is older than 13 years of age. Among 820 respondents 218 men and 442 women were finally selected as datum sources. The data were analyzed by the statistical method such as the factor analysis frequency distribution, percentile, ANOVA, Pearson's correlation and regression analysis. The main results were as follows; 1) Men and women experience mid-life crisis some extent. The mid-life crisis score for men is 33.60 and 35.0 for women. This implies women reveal significantly higher crisis than men. As for women's mid-life crisis. self-awaring age, education, income, husband's occupation, employment status of wife and occupational status of wife have a significant influence Expecially employment status of wife seemed to interact with sex, husband's occupation and educational level of wife. however status of child, family pattern, son's existence are not as important an influence on mid-life crisis. 3) Among the psychological variables, work identity and physical identity have the strong influence on the mid-life crisis of men and women, It implies that mid-life crisis si lower when one has higher work identity and physical identity. 4) Mid -life crisis of men and women is influenced significantly according to family relation variables and health variables. It reveals that the better one's family relations and health sate, the lower one's mid-life crisis is. However menopause and the years after menopause do not influence on the mid-life crisis of women. 5) Mid-life crisis of women differs significantly according to the kind of religion and religious activity. That is mid-life crisis of women is lower when she believes in Protestantism and Catholicism and participate in more religious activity. Mid-life crisis of men is not significantly influenced by religious variables. After all among the five categories of variables that related to mid-life crisis, psychological variables-especially work identity and physical identity are observed to have the strongest degree of significance.

• Journal of Korea Water Resources Association
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• v.47 no.9
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• pp.813-824
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• 2014

In this study, drought of North Korea are analyzed using drought index. 27 weather stations are selected and monthly precipitation and average temperature data are collected for drought analysis. SC-PDSI is used for drought analysis and calculated using collected weather data during 1984~2013 (30 years) in 27 weather stations. From the analysis result of historical drought event using drought index, it is confirmed that severe droughts occurred in the early and mid 2000's at most stations. Secondly, drought frequency analysis was carried out for the derivation of drought severity-duration-frequency (SDF) curves to enable quantitative evaluations of past historical droughts having been occurred in 6 stations (Pyeongyang, Hamheung, Cheongjin, Wonsan, Haeju, Sinuiju). This study can suggest return periods for historical major drought events by using derived SDF curves for each station. In the result, drought events in the early and mid 2000's had return periods of 20~50 years.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.8
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• pp.1240-1245
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• 2015

The purpose of this paper is to investigate the autonomic nervous system activity in various ambient temperatures. To evaluate autonomic function, we use the frequency domain analysis of heart rate variability such as FFT(fast fourier transformation), AR(Auto-Regressive) model and Lomb-Scargle peridogram. HRV(heart rate variability) is calculated by using ECG recorded from 3 different temperature room which temperature is controlled in 18℃(low), 25℃(mid) and 38℃(high), respectively. Totally 22 subjects were participated in the experiment. In the results, the most significant autonomic changes caused by temperature load were found in the HF(high frequency) component of FFT and AR model. And the HF power is decreased by increasing temperature. Significance level was increased by increasing the difference of temperatures.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.11
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• pp.1277-1282
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• 2014

In this paper, we aimed to analysis EEG signals related to concentration of adolescents using letter visual stimulus to induce the concentration. The visual stimulus tasks were searching errors of propositional particle in several sentences. In the EEG signals, we specially focussed on SMR waves and mid-beta waves according to the results of a preceding research. Therefore we presented position of channel and frequency band of mid-beta significantly related to the concentration waves as the experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.672-673
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• 2012

• Speech Sciences
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• v.7 no.2
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• pp.193-208
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• 2000

This paper describes a multi-step method of intonation modeling for corpus-based Korean speech synthesizer. We selected 1833 sentences considering various syntactic structures and built a corresponding speech corpus uttered by a female announcer. We detected the pitch using laryngograph signals and manually marked the prosodic boundaries on recorded speech, and carried out the tagging of part-of-speech and syntactic analysis on the text. The detected pitch was separated into 3 frequency bands of low, mid, high frequency components which correspond to the baseline, the word tone, and the syllable tone. We predicted them using the CART method and the Viterbi search algorithm with a word-tone-dictionary. In the collected spoken sentences, 1500 sentences were trained and 333 sentences were tested. In the layer of word tone modeling, we compared two methods. One is to predict the word tone corresponding to the mid-frequency components directly and the other is to predict it by multiplying the ratio of the word tone to the baseline by the baseline. The former method resulted in a mean error of 12.37 Hz and the latter in one of 12.41 Hz, similar to each other. In the layer of syllable tone modeling, it resulted in a mean error rate less than 8.3% comparing with the mean pitch, 193.56 Hz of the announcer, so its performance was relatively good.