• Korean Chemical Engineering Research
• /
• v.60 no.1
• /
• pp.125-131
• /
• 2022

The microstructure of highly aggregated colloidal dispersions was investigated by probing the rheological behavior of magnetic suspensions. The dynamic moduli as functions of frequency and strain amplitude are shown to closely resemble that of colloidal gels indicating the formation of network structure. The two types of characteristic critical strain amplitudes, γ_c and γ_y, were characterized in terms of the changing microstructure. The amplitude of γ_c indicates the transition from linear to nonlinear viscoelasticity and depends only on particle volume fraction not magnetic interactions. The study of scaling behavior suggests that it is related to the breakage of interfloc, i.e., floc-floc structure. However, yielding strain, γ_y, was found to be independent of particle volume fraction as well as magnetic interaction. It relates to extensive deformation resulting in yielding behavior. The scaling of elastic constant, G_e, implies that this yielding behavior and hence γ_y is due to the breakage of long-range interfloc interactions. Also, the deformation of flocs due to increase strain was indicated from the investigation of the fractal nature.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.26 no.1
• /
• pp.35-46
• /
• 2023

The purpose of this research is to provide characteristics and satisfaction of visitors for Deoksan Provincial Park in Chungcheongnam-do. This study conducted face-to-face interview during Oct. to Nov. in 2022. Total sample size of this study was 521. This study used to implement frequency analysis, cross analysis and logit analysis via SPSS 21.0 version. The results showed most of visitors were one day visitors and visited with family and relatives. Many visitors visited the Deoksan Provincial Park to climb the mountain and relaxing/healing with the nature. The satisfaction level of factors such as nature, facility, access to information of the park was high with about more than 4-point on Likert scale. This study would be useful to develop site-specific policies to the management of provincial parks as this study identified the characteristics and satisfaction level of the visitors.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.11 no.3 s.25
• /
• pp.89-99
• /
• 1987

The purpose of this present study is not only to investigate mutal relationship between the preference of clothing design and the nature of Reflectiveness-Impulsiveness, but to offer clothing design for desirably developing of child, especially of preschool children. And the practical research was performed for 166 preschool children who are in kindergarten located in Seoul and are selected according to their sex and social class. This study used Kagan's MFFT and Personality Inventory of Hwang Eung-Yeon for the test of Reflectiveness-Impulsiveness, while for the preference of clothing design used the photo deck which is showed to children. The data analysis was based on frequency, percentage, mean, standard deviation, chi-square ($x^2$) test, t-test, F-test, and Duncan's Multiple Range Test. It can be concluded that girls rather than toys, high class children rather than middle or low class children were more reflective as a general trend. The relationship between the preference of clothing design and the nature of Reflectiveness and Impulsiveness is as follows : 1. In color, reflective boy liked blue series and reflective girl liked pastel coloring series, while they disgusted red series and non-coloring series. The group of impulsiveness liked red series, while they disgusted non-coloring series. 2. In color combination, group of reflectiveness liked similar color, while group of impulsiveness liked contrasting color. 3. In texture, group of reflectiveness liked soft and shiny texture, while they disgusted thick and rough texture. Also Group of impulsiveness liked soft texture. 4. In pattern, reflective boy liked lettering pattern and reflective girl liked flower pattern, while she disgusted lettering pattern. Impulsive boy liked stripe pattern and limpulsive girl liked flower pattern. 5. In pattern size, group of reflectivenss liked small size, while group of impulsiveness liked large one. 6. In style, group of reflectiveness liked formal style.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.2 no.1
• /
• pp.21-35
• /
• 2000

The purpose of this study was to evaluate the preference of image for modern application of Korean traditional patterns. A survey was conducted using the randomly selected 292 undergraduate women students of Taegu city. The degree of interest and preference in Korean traditional style or something like that had measured by 5 scale method. And then they had two groups which are interest/non-interest group, and preference/non-preference group in Korean traditional style. Also, preference of Korean traditional patterns was measured by 5 scale method. The image of Korean traditional patterns consisted of semantic differential scales. Analysis was by frequency, percentage, and mean. For difference of groups analysis was by t-test. The results were as follows:1. For the survey, 53.8% showed the interest and 40.4% did the preference for the traditional patterns. There was the positive correlation(0.782) between the degree of the interest and preference. 2. Among twenty traditional patterns, the patterns of plants and nature were very preferred, but the patterns of geometrical things was not preferred. 3. For the nature pattern, the image seemed to be elegant and feminine(womanly). For the plant pattern, the image seemed to be feminine, neat, weak, light and mild. For the animal pattern, the image seemed to be heavy, gorgeous, deluxe, virile(manly), strong and active. Last, for the geometrical pattern, the image seemed to be elegant, deluxe, rigid and strong. 4. Between the interest／non­interest groups, there was the significant difference in pattern of cloud, mountain, lotus flower, plum blossoms, orchid, dragon, chinese phoenix and bogy. Especially, for the orchid pattern, the preference difference between these groups was large. 5. For the plant pattern, the image difference between these groups was very large as the elegant-rustic image. Especially, the interest group evaluated as the elegant image. 6. Between the preference／non­preference groups, there was the strongly significant difference in the preference for the orchid pattern. 7. For the geometrical pattern, the image difference between these groups was very large as the mild­cold image. Especially, the preference groups evaluated as the cold image.

• Journal of IKEEE
• /
• v.24 no.2
• /
• pp.536-542
• /
• 2020

This paper presents a nature-inspired wideband sprout-leaf shaped antenna with end-fire radiation pattern. A sprout-leaf shape angled-radiator was designed for wide beamwidth radiation patterns for motion detection sensors. An extended and truncated ground plane was used as a reflector for end-fire radiation patterns. To feed the balanced radiator, a broadband microstrip (MS) to coplanar stripline (CPS) balun was utilized with excellent amplitude and phase balance. The proposed antenna demonstrates wide frequency bandwidth from 8.5 to 14.5 GHz with wide beamwidth and the radiation efficiency of 90%. The measured gain is from 4 to 5 dBi and front-to-back ratio was 10 to 20 dB. It has been shown that the proposed antenna can be used for imaging sensors, phased array systems, and radars that require a wide bandwidth and a directional radiation pattern.

• Textile Coloration and Finishing
• /
• v.6 no.3
• /
• pp.27-36
• /
• 1994

In order to produce a water repellent surface on polyester fabric, samples were treated in the atmosphere of $CF_4$ glow discharge plasma. The samples used in the study were ployester fabric and poyester film. The purpose of film treatment is for the comparison of hydrophobicity with fabric sample at same treatment condition. Radio frequency(13.56MHz) generator was used as electric source and its in put power is 100 Watt. Water repellency was evaluated by contact angle measurement. Result obtained are as follows. 1) Fiber interstice of original fabric was ana lysed as 0.43$\mu$m, and this value was sufficiently ideal for making water repellent fabric. 2) The most favorable setting position of substrate was the center area between two electrodes. 3) Fabric contact angle was higher than film contact angle at same treatment condition, and its difference was more than 50${\circ}$. And it was incapalbe of fabric contact angle measurement when the film contact angle was less than 90${\circ}$. because the fabric is susceptible to absorption of water by the capillary effect. 4) Fabric contact angle can not revealed the precise defferences of surface hydrophobicity, however, the film contact angle showed the real hydrophobic nature. 5) It was not sufficient method to evaluate the hydrophobicity of fabric surface by merely measure of the water contact angle. 6) It showed high water repellent nature at 0.06 torr of $CF_4$ plasma gas pressure and duration of 45 seconds treatment, and it can not be anticipated more improved nature if the pressure and duration of treatment time were increased.

• Journal of Korean Physical Therapy Science
• /
• v.13 no.4
• /
• pp.43-62
• /
• 2006

The survey was conducted with participation of the 289 handicapped persons residing at the rural area OOeup-gun in Kyungbook for the period of March 2 - May 31, 2006, to study the nature in general of the handicapped and the boundaries of their need. For the nature in general of the handicapped, the study was done by gender iscrimination, age, marital status, religion, educational level, occupation, monthly income, disability cause, disabled duration, disability type, disability level. For the boundaries of their need, the study was done by demand of financial support, educational demand, demand of voluntary workers, need of rehabilitation and medical treatment, job training, improvement of living conditions, or so. Using the Win.SPSS program, we made a frequency analysis and conclusions on the nature in general of the handicapped and the boundaries of their need on a 2-test. Conclusions are : 1. Nature in general of the handicapped The existence of the handicapped shows high at the age over 51 (71.6%), male-handicapped (65.1%), primary school graduates (62.9%), farming engaging (65.2%), monthly income less than one million Won (80.5%), cause by disease (53.8%), duration more than 10 years (61.6%), disability at level 3 (39.8%), extremity disability (66.4%). 2. Correlation of nature in general with demand of the handicapped a. In demanding the financial support, support for helper’s compensation shows high (p<0.05). In demanding the necessity of voluntary workers, the male-handicapped appears high during the absence of family assistance and the female-handicapped appears differently per week and also appears high during the absence of family assistance (p<0.05). b. In educational demand of the handicapped by their age, the age below 30 demands technical-job training and the age over 31 demands medical education for health care (p<0.01). c. In demanding the financial support by educational level, support for living cost shows high (p<0.05). d. In demanding improvement of living conditions by postnatal cause of disability, improvement of house structure shows high (p<0.05). e. In demanding assistance of voluntary workers by disabled duration, "No Need" shows high in the disabled duration more than 4 years (p<0.05). f. In demanding rehabilitation and medical treatment by disability type, home-visiting treatment, oriental medical treatment and physical therapy show high (p<0.001). g. In educational demand by disability level, medical education for health care shows high (p<0.01).

• International Journal of Internet, Broadcasting and Communication
• /
• v.9 no.2
• /
• pp.70-77
• /
• 2017

Where there are all the flowers, the songs of all kinds of insects and birds are put in, the sunshine and shadows flicker The forest through which the water sound flows is an optimum resting space. All living creatures in these spaces will awaken the five senses of humans and perhaps turn the sensibility index (EQ). The forest meditation in the forest, which can be an optimal shelter for the people who need it, needs to feel the reverence of nature, to refine emotions, to be a self-reflection, to have a mind to respect, Have an important meaning. In this paper, we tried to consider the cause of the influence of forest sounds on human hearing from the acoustical aspect. The type of sound source of forest was divided into four seasons of spring, summer, autumn, winter. And the change in the duration of the sound during the four seasons, so that the general characteristics of the sounds of the four seasons are as follows: It can be seen that the change in the ratio of sub-band energy is almost equal to the change in dB in frequency of the equal-light curve. To compare this phenomenon, the criterion for changing the sound duration of each forest is natural The main forms of the luminance curve, such as the change in the duration of the white signal in the sound, are determined by the minimum, maximum audible frequency and the most sensitive frequency band, and the auditory characteristics of the other three inflection points Determines the overall shape of the equal-light curve.

• Wind and Structures
• /
• v.12 no.5
• /
• pp.441-455
• /
• 2009

Studying the spatial distribution in coherent fields such as turbulence and turbulence-induced force is important to model and evaluate turbulence-induced forces and response of structures in the turbulent flows. Turbulence field-based coherence function is commonly used for the spatial distribution characteristic of the turbulence-induced forces in the frequency domain so far. This paper will focus to study spectral coherent structure of the turbulence and induced forces in not only the frequency domain using conventional Fourier transform-based coherence, but also temporo-spectral coherence one in the time-frequency plane thanks to wavelet transform-based coherence for better understanding of the turbulence and force coherences and their spatial distributions. Effects of spanwise separations, bluff body flow, flow conditions and Karman vortex on coherent structures of the turbulence and induced pressure, comparison between turbulence and pressure coherences as well as intermittency of the coherent structure in the time-frequency plane will be investigated here. Some new findings are that not only the force coherence is higher than the turbulence coherence, the coherences of turbulence and forces depend on the spanwise separation as previous studies, but also the coherent structures of turbulence and forces relate to the ongoing turbulence flow and bluff body flow, moreover, intermittency in the time domain and low spectral band is considered as the nature of the coherent structure. Simultaneous measurements of the surface pressure and turbulence have been carried out on some typical rectangular cylinders with slenderness ratios B/D=1 (without and with splitter plate) and B/D=5 under the artificial turbulent flows in the wind tunnel.

• Journal of Positioning, Navigation, and Timing
• /
• v.13 no.1
• /
• pp.111-115
• /
• 2024

This study builds a machine learning model optimized for clocks among various techniques in the field of artificial intelligence and applies it to clock stabilization or synchronization technology based on atomic clock noise characteristics. In addition, the possibility of providing stable source clock data is confirmed through the characteristics of machine learning predicted values during holdover of atomic clocks. The proposed machine learning model is evaluated by comparing its performance with the AutoRegressive Integrated Moving Average (ARIMA) model, an existing statistical clock prediction model. From the results of the analysis, the prediction model proposed in this study (MSE: 9.47476) has a lower MSE value than the ARIMA model (MSE: 221.2622), which means that it provides more accurate predictions. The prediction accuracy is based on understanding the complex nature of data that changes over time and how well the model reflects this. The application of a machine learning prediction model can be seen as a way to overcome the limitations of the statistical-based ARIMA model in time series prediction and achieve improved prediction performance.