• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.13 no.1
• /
• pp.1-7
• /
• 2020

Directivity control technology of sound system is a key technology for improving sound quality. Providing a line source rather than a point source in an acoustic system can reduce the effects of attenuation interference at long distances, thereby providing high quality sound. In particular, A line-array speaker system can be used to provide coherent, high-quality sound over long distances. However, high frequencies have shorter wavelengths, so the distance between the speakers of a line array system must be shorter, but there are physical limitations. In this paper, we designed a wave guide and installed it in the speaker's compression driver to solve this problem. We measured and tested various acoustic characteristics to verify the performance of the speaker. As a result, when the line array sound system is constructed using the developed speakers, it is possible to provide a line source in all areas including the treble range, thereby achieving the same effect as a single extended source and providing high quality sound up to far distances.

• Journal of Convergence for Information Technology
• /
• v.9 no.3
• /
• pp.120-127
• /
• 2019

A study on the factors affecting oral health beliefs of some high school third graders on oral health promotion behavior After the oral health education on November 21, 2017, 160 students who explained and agreed on the study purpose and method were final analyzed. Oral health belief and oral health promotion behavior according to general characteristics were analyzed with t-test, one-way ANOVA, and the correlation with Pearson's correlation test. The convergence factors affecting oral health promotion were performed multiple regression analysis. The convergence factors affecting oral health promotion were performed multiple regression analysis. Oral health belief was the highest with 3.61 points, with 4.06 points of benefit, while oral health promotion with 3.25 points. Convergence factors affecting oral health improvement were shown as susceptibility (${\beta}=-0.210$), salienece(${\beta}=0.396$), seriousness(${\beta}=0.306$), and barrier(${\beta}=-0.170$). To explore ways to change the oral health beliefs of high school students, the school district health education is very important, and various oral health education programs to promote oral health promotion should be developed.

• Journal of the Korea Convergence Society
• /
• v.11 no.12
• /
• pp.89-95
• /
• 2020

This study empirically demonstrates how the amount of advertising attitude and recall information differs according to the type of art infusion advertising (simple borrowing vs. modification vs. reinterpretation) and engagement level (high vs. low) of digital signage. It is to look into. Factorial design was performed between 3×2 subjects, and the hypothesis was verified through a two-way MANOVA analysis. As a result of the study, first, when simply art infusion of masterpieces in digital signage, both advertisement attitude and recall information were found to be low regardless of the level of engagement. Second, in the case of digital signage art infusion advertising, when the engagement is low, the modification has high advertising attitude and recollection. Third, when the level of engagement of digital signage is high, the attitude and recollection of the reinterpreted famous painting borrowing ads are high.

• Asia-Pacific Journal of Business
• /
• v.13 no.1
• /
• pp.167-183
• /
• 2022

Purpose - The purpose of this study is to show the need to use the past long-term returns for investment decisions in U.S. equity funds and to suggest an investment strategy using long-term returns. Design/methodology/approach - This study solves the problem of high return volatility in long-term returns and proposes new investment portfolios based on the behavior of fund investors according to past returns. For the investment portfolio of this study, 60 months are divided into several periods and the average of the performance ranks for each period is used. Findings - First, funds with high average returns over multiple periods have lower future outflows and higher future returns than funds with high 60-month cumulative returns. Second, funds with low average returns over multiple periods have lower future inflows and lower future returns than funds with low 60-month cumulative returns. The findings mean that when making decisions based on past long-term returns, it is a smarter investment choice to buy funds with high average returns over multiple periods and sell funds with low average returns over multiple periods. Research implications or Originality - This study shows that it is necessary to use long-term returns in fund investment by analyzing the characteristics of the portfolio based on past returns. In addition, the study is meaningful in that it suggests a way to use long-term returns more efficiently based on the behavior of fund investors and shows that such investments lead to higher returns in the future.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.6
• /
• pp.145-155
• /
• 2023

A radial combiner with high efficiency characteristics in the X-band was designed and manufactured using a waveguide and matching structure. In particular, in order to manufacture it in a small size, a dual waveguide to coaxial transition structure was applied that allows two ports to be matched to one waveguide. Applying this structure makes it possible to manufacture smaller than typical coaxial to waveguide radial combiner. As a result of measurement in the X-band band of 9.2~10GHz, the return loss was less than -18.408dB and the output insertion loss was less than 0.206dB, and the output combining efficiency was obtained as high as 95.37% or more. It is expected that it can be used in the combining part for high output transmitters in the millimeter wave band in the future. In particular, the range of use is expected to increase by reducing the size and weight.

• Journal of Animal Science and Technology
• /
• v.66 no.5
• /
• pp.1049-1068
• /
• 2024

This study aimed to compare the changes in the bioactivities of peptide extracts (< 10 kDa) obtained from Jeju black pigs (JBP) and three-way crossbred pigs (Landrace × Yorkshire × Duroc, LYD) before and after digestion. The results showed that the loin peptide extracts of JBP maintained high 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity after in vitro digestion. However, the iron chelating activity and antihypertensive activity of all peptide extracts were decreased. This study suggested that the peptide extracts produced through alkaline-AK digestion have sufficiently high antioxidant and antihypertensive activities; however, these activities were reduced after in vitro digestion. Meanwhile, the JBP loin and ham peptide extracts promoted high superoxide dismutase (SOD) activity than that of LYD when administered to mice. Furthermore, the ham peptide extracts of JBP showed a relatively high antihypertensive activity in mice. Therefore, it is deemed that these peptide extracts from JBP are more bioactive than that of LYD, and can be used as bioactive materials.

• The Korean Journal of Malacology
• /
• v.31 no.2
• /
• pp.83-92
• /
• 2015

The effect of different intermediated rearing method by expanding the attached floor space in order to highly density culture on the growth characteristics and survival rate of the juvenile abalone, Haliotis discus hannai, were investigated in land-based tanks. The intermediated culture methods was determined thru the shelter counts and layer for 10 month with two replicates : the single layer shelter (SLS), the double layer shelter (DLS), the triple layer shelter (TLS) and the single layer shelter under net cage (SLSNC). In addition, the culture on shallow race way tank had to set up as culture of the ditch raceway tank (CDRT) and the floor race way tank (CFRT). In the growth performance of reared abalone (initial mean shell length $54.18{\pm}7.39mm$ and weight $1.93{\pm}0.14g$) at experimental tanks, that the absolute growth rate (ARG), daily growth rate (DGR) and specific growth rate (SGR) to the shell length and shell breadth was not significant at each experimental tanks except SLSNC. As well as too, weight gain (WG), daily weight gain (DWG) and specific weight gain (SWG) to weight was not significant at each experimental tanks except SLSNC, too. Survival rates of CDRT and CFRT was lower than those of different experimental tanks (P < 0.05). Therefore, these results is showed that high density different intermediated rearing method by expanding the attached floor space for juvenile H. discus hannai was not have difference as growth performance and survival rate both one layer shelter and multi layer shelter. Also, it is considered that shallow race way tank was not useful rearing for the juvenile intermediate culture of H. discus hannai in land based.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.24 no.1
• /
• pp.36-41
• /
• 2011

Medical X-ray has been brought many changes according to the rapid development of high technology. Especially, for high-voltage generator which is the most important in X-ray generation the traditional way is to use high-voltage electric transformers primarily. However, since it is large and heavy and the ripple rate of DC high-voltage applied to X-ray tube is too big, it has a disadvantage of low X-ray production efficiency. To solve these problems, the studies about high-voltage power supply are now proceeding. At present, the high-voltage generator that generates high-voltage by making high frequency using inverter control circuit consisting of semiconductor device is mainly used. High-voltage generator using inverter has advantages in the diagnosis using X-ray including high performance with short-term use, miniaturization of power supply and ripple reduction. In this study, the X-ray high-voltage device with inverter type using pulse width modulation scheme to the control of tube voltage and tube current was designed and produced. For performance evaluation of produced device, the control signal analysis, irradiation dose change and beam quality depending on the load variation of tube voltage and tube current were evaluated.

• Hwankyungkyoyuk
• /
• v.8 no.1
• /
• pp.81-97
• /
• 1995

This study is to consider the result of the Field Trip Contest(FTC) and get a suggestion as a way of environmental education at school level in field. FTC was executed with selected students(3/1team) of 5th grade nationwide at Nam-Han mountain fortress in the suburbs of Seoul in Oct., 1994. The outcome of FTC was very high with the score of 1.38/2.0, and the quality of the program was generally high with the score of 1.09/2.0. Among areas of the outcome domain, accomplishment of the objectives of FTC was very high(1.55), execution of the policy of FTC was generally high(1.27), and operation and promotion of FTC was generally high(1.16). And in the Program of FTC domain, meaning of execution was very high(1.57), possibility of accomplishment was not high(0.03), validity of the content was generally high(1.18), appropriateness of activity scope was generally high(1.15), possibility of application into school system was generally high(1.22), and extending effect to education was generally high(0.9). Participants responded they got a great experience of inquiry for protecting nature during the activity of FTC and teachers accompanying found a good possibility to do in own school province.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2007.11a
• /
• pp.995-998
• /
• 2007

The number of households old over as much as 20 years is expected to get increased rapidly more than 1,000,000(1 million). As a measure to this fact remodeling is being revitalized over the country. parking lots expansion actually takes up a great deal of weight among the requirement for remodeling. When constructing a parking lot for enlargement, the way of going into the main building determines such construction features as selection of Retaining Wall Method, installation of an elevator, parking measure of capacity, etc. This study derived the affecting factors for selecting the way of going into the main building when constructing an underground parking lot. In a research way, we examined the features on each method of going into the main building in an apartment complex through an in-depth interview with some experts after investigating the method of enlarging an underground parking lot and going into the main building. After that, we derived the affecting factors for selecting the way of going into the main building. The affecting factors include constructability, convenience, economic efficiency as a high level as well as existence and nonexistence of basement and removal, safety of current building, parking measure of capacity, amenity, inhabitant traffic line, construction expenses and construction duration as a low one. This study will be applied as a reference for selecting the way of going into the main building when constructing an underground parking lot especially targetted on an old apartment house.