• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.30 no.2
• /
• pp.173-176
• /
• 2019

In this study, a Ka-band waveguide rotary joint that can be applied to a millimeter-wave seeker is designed and fabricated. The proposed rotary joint maintains a low standing-wave ratio and low-loss characteristics, and has two rotary axes designed to enable azimuth and elevation rotation. The rotary joint is designed as a ridge-waveguide-type mode converter and a ${\lambda}/4$ choke structure to match the electromagnetic wave propagation mode between the spherical and circular waveguides. A performance test using a network analyzer and a high-power transmitter to assess vibration and shock were conducted. Results showed that the rotary joint had a very low standing-wave ratio of less than the maximum of 1.19:1 and an insertion loss of less than 0.80 dB at $F_C{\pm}500MHz$.

• Journal of the Society of Disaster Information
• /
• v.14 no.4
• /
• pp.399-408
• /
• 2018

Purpose: Recently, the ground subsidence has caused social problem, because it occurred life and economic damage. Method: Ground subsidence is different from a sink hole. Ground subsidence occurred cavities from loss of by groundwater flow, surface layer is collapsed due to relaxation and expansion. Results: According to the survey, the caused of ground subsidence are classified as ground cavities, surrounding ground relaxation and pipe joint failure. Conclution: Cavities of ground is mainly caused by cavities formed by rainfall induced infiltration of the heavy rainfall, loss of soil due to rise and fall of ground water level and repeated sewage runoff.

• Journal of The Korean Association For Science Education
• /
• v.39 no.1
• /
• pp.101-113
• /
• 2019

This study aims to explore which aspects of student agency have previously been studied and the ways agent practices have been investigated in learning communities in research on science education. Results reveal five aspects of agency related to students' actions in a learning community: epistemic agency, transformative agency, educated action in science, disciplinary agency, and material agency. We delineated how agency is captured in epistemic practices, as described in the literature on each of the aforementioned aspects. We also probed into the three approaches by which previous research has examined the practices of students as agents that construct learning communities. These approaches are (a) the investigation of students' actions as representative of the agency of an entire learning community, (b) the exploration of the effects of focused student action on the structure of activity, and (c) the investigation of interactions between students as agents. We discussed the implications of previous research on the basis of each approach to understanding the diverse features of student-centered learning communities. The present work contributes to the exploration and support of students' practices as agents in the learning communities in science classrooms.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.10
• /
• pp.1310-1316
• /
• 2021

Recently, with the development of artificial intelligence and IoT technology, the importance of video processing such as object tracking, medical imaging, and object recognition is increasing. In particular, the noise reduction technology used in the preprocessing process demands the ability to effectively remove noise and maintain detailed features as the importance of system images increases. In this paper, we provide a modified weight filter based on pixel matching in an AWGN environment. The proposed algorithm uses a pixel matching method to maintain high-frequency components in which the pixel value of the image changes significantly, detects areas with highly relevant patterns in the peripheral area, and matches pixels required for output calculation. Classify the values. The final output is obtained by calculating the weight according to the similarity and spatial distance between the matching pixels with the center pixel in order to consider the edge component in the filtering process.

• Journal of the Korea Convergence Society
• /
• v.12 no.10
• /
• pp.169-175
• /
• 2021

This study viewed foreign students as a publics that requires active communication, and analyzed the causal relationship between the antecedent variables (professor competency service, university administrative service) and outcome variables (adaptation to university life) of the university-foreign student relationships. As a result, both the professor competency service and the university administrative service were found to have a positive effect on the university-foreign student relationships. Also, the university-foreign student relationships was found to have a positive effect on adaptation to university life. Based on these results, we discussed the need to set the university-foreign student relationship as a major performance indicator and use it as basic data for developing active communication strategies and messages.

• Journal of Korean Library and Information Science Society
• /
• v.51 no.4
• /
• pp.249-278
• /
• 2020

The purpose of this study is to design metadata for management and sharing of Yeogu data produced in the ecological field. Specifically, metadata is designed based on DCAT, which is designed to facilitate interoperability between data catalogs published on the web. In addition, ABCD, Darwin Core, and EML were analyzed and applied to metadata design to reflect the characteristics of the ecological field. As a result of the research, a total of 51 metadata elements were derived for managing research data in the ecological field, and 6 essential elements, 23 recommended elements, and 22 optional elements were included. The results of this study can be used to design a DB when building a research data management and sharing system based on metadata elements, and to suggest a metadata exchange format when linking with other systems.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.35 no.8
• /
• pp.35-46
• /
• 2019

This study started from the interest about a theme repeated in a similar way among a group of architects in Japan. They argue that a building composed of random elements can lead to discoverable functions rather than fixed functions. Their work supports this to a certain extent, but at the same time raises the following two research questions. Can 'formal randomness' and 'functional discoverability' be completely identical? Does such a form sufficiently fulfill other functions of the building? In order to answer these two research questions, this study analyzes the relationship between form and function in the 'Children's Center for Psychiatric Rehabilitation' of Sou Fujimoto. The analysis proceeded in three steps. In the first step, I found that alcoves were the most important factor in functional discoverability by comparing scenarios with different conditions. At the same time, however, I could see that these alcoves were weakened in the process of functional adjustment. In the second step, I analyzed the final design and found Sou Fujimoto's response to the preceding problem. He thought that in-between alcoves created from formal randomness, were not enough and thus introduced a new method, cutting alcoves. This means that formal randomness alone does not fully guarantee both the functional discoverability and the fulfillment of the basic functions. In the third step, I searched for the significance of this problem through a brief comparison with other similar projects.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.1
• /
• pp.1-7
• /
• 2020

Fuzzy clustering, represented by FCM(Fuzzy C-Means), is a simple and efficient clustering method. However, the object function in FCM makes clusters affect clustering results proportional to the density of clusters, which can distort clustering results due to density difference between clusters. One method to alleviate this density problem is EDI-FCM(Extended Density-Independent FCM), which adds additional terms to the objective function of FCM to compensate for the density difference. In this paper, proposed is an enhanced EDI-FCM using regularization, Regularized EDI-FCM. Regularization is commonly used to make a solution space smooth and an algorithm noise insensitive. In clustering, regularization can reduce the effect of a high-density cluster on clustering results. The proposed method converges quickly and accurately to real centers when compared with FCM and EDI-FCM, which can be verified with experimental results.

• Journal of IKEEE
• /
• v.24 no.4
• /
• pp.1028-1033
• /
• 2020

The existing in-band interference reduction method recommends the physical separation distance between wireless devices and interference signals, and the interference can be suppressed through the separation distance. If the in-band interference signals can be reduced in a wireless device, a margin can be given to the physical separation distance. Since there is an effect of extending the receiver dynamic range of receivers, it is highly useful for interference reduction and improvement method. In this paper, the structure of an in-band analog IRM(Interference Reduction Module) is proposed and the design and implementation of the proposed analog IRM are described. To design an analog IRM, the interference reduction performance according to the delay mismatch, phase error and the number of delay lines that affect the performance of the analog IRM was simulated. The proposed analog IRM composed of 16 delay lines was implemented and the implemented IRM has the interference reduction performance of about 10dB for a 5G(NR-FR1-TM-1.1) signal having a 40MHz bandwidth at a center frequency of 3.32GHz. The analog IRM proposed in this paper can be used as an in-band interference canceller.

• International Area Studies Review
• /
• v.13 no.2
• /
• pp.255-276
• /
• 2009

This article has examined the international transmission of returns among S&P500, Nikkei225 and SENSEX stock index cash markets using the daily closing prices covered from January 4, 2002 to February 6, 2009. For this purpose we employed dynamic time series models such as the Granger causality analysis and variance decomposition analysis based on VAR model. The main empirical results are as follows; First, according to Granger causality tests we find that S&P500 stock index has a significant prediction power on the changes of SENSEX and Nikkei225 stock index market and vice versa. However, US stock market's influence is dominant to the other stock markets at a significant level statistically. Second, according to variance decomposition, SENSEX stock index is more sensitive to the movement of S&P500 than that of Nikkei225 stock index. These kinds of empirical results shows that the three stock markets are integrated over times and these results will be informative for the international investors to build the world-wide investment portfolio and risk management strategies, etc.