• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.35.1-35.1
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• 2019

One day, a galaxy study suddenly came to me and became a friend of 40 years. The study of galaxies, which began with surface photometry of nearby galaxies, ended up in galaxy morphology through chemical and dynamical evolution of galaxies. All that deviated from the study of galaxies was the study of the open clusters. So it seems to me that I devoted my entire life to the study of galaxies. The most memorable one is the observation at Sobaeksan Observatory. Even though the heavy snow fell, I climbed Sobaeksan to meet galaxies. Galaxies observed at Kiso Observatory, DAO, and BOAO are now beyond memory, but I still enjoy seeing them. There are many memories, but the biggest pleasure I've had in my galaxy studies is when I've encountered the galactic conformity between host and its satellite galaxies. Eureka! Now the night sky is changing from the object of study to the object of awe. I will share this joy.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.32.2-32.2
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• 2021

Radio relics, Mpc-size elongated diffuse radio emissions found at galaxy cluster outskirts, are known as the result of shock acceleration during the cluster merger. Theories have claimed that low Mach number shocks are too inefficient to create the observed properties of radio relics. Alternative scenarios such as fossil cosmic ray electrons (CRes) from AGNs are required to explain the observations. However, how exactly the fossil CRes from AGNs can supply the Mpc-size radio relic is still an open question. In this study, we present our recent uGMRT radio observation results of the merging galaxy cluster Abell 514. We found three remarkable AGN jet tails that may have undergone multiple reorientations and extend nearly 800 kpc. Using multi-frequency data, we have performed spectral analysis along the AGN tails and track how the tails lose or gain energy as they propagate in the intracluster medium. We will discuss whether these AGN jets can provide sufficient seed CRes to radio relics.

• Journal of Korean Library and Information Science Society
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• v.50 no.1
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• pp.333-356
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• 2019

Open access has emerged as an alternative to overcome the crisis brought by scholarly communication on commercial publishers. The purpose of this study is to suggest the intellectual structure that reflects the newest research trend in the field of open access, to identify how the subject area is structured by using co-word analysis, and compare and analyze with the existing study. In order to do this, the total number of dataset was 761 papers collected from Web of Science during the period from January 2012 to November 2018 using information science and 2,321 keywords as a noun phase are extracted from titles and abstracts. To analyze the intellectual structure of open access, 13 topic clusters are extracted by network analysis and the keywords with higher centrallity are drawn by visualizing the intellectual relationship. In addition, after clustering analysis, the relationship was analyzed by plotting the result on the multidimensional scaling map. As a result, it is expected that our research helps the research direction of open access for the future.

• Journal of Korean Academy of Nursing
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• v.22 no.4
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• pp.421-443
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• 1992

The purpose of this study was to identify patients' perceptions of health professionals' unkind behavior and the effects of this unkind behavior using a Phenomenological research methodology. Understanding of this phenomena should enlighten nurses to interaction and relationship problems between patient and health professionals and thus lead to further research toward enhancing these interaction and relationships. The subjects were 40 adult patients hospitalized in a university hospital in Seoul. They were from 20 to 65 yews old and hospitalized at IM, GS, OS, NS, OB /GY ward. Their hospital days were from 4 to 72. Data were collected from July 29 to August 9, 1991 and from January 6 to 17, 1992. The research questions were “What behavior on the part of health professionals you perceive as unkind and what effect does such behavior have in you\ulcorner”. Responses to the non-structured open-ended questions were audio-recorded during the interviews done by two nurses researchers. Data were analyzed using the phenomenological method of Colazzi. The validity was enhanced by confirmation of the analysis by two nursing clinical researchers, and professor of psychology, and philosophy, all knowledgable of phenomenological research. From the protocols, 146 significant statements about unkind behavior were organized into 38 formulating meanings which were then grouped into six clusters of themes. Patients' Perceived health professional' unkind behavior as being cold, insincere, unconcerned, disregardful, lacking in technical skill, and failing to provide a therapeutic environment. From the protocols, 65 significant statements about the influence of such behavior on patient care were organized into 18 formulating meanings which were then grouped into four clusters of themes. Patients perceived these unkind behavior influencing then emotionally, physically and having negative effects on their compliance with medical and nursing care. The study points to the need for health professionals to understand how their behavior may be perceived by their patients as unkind behavior. Patients perceptions of health professionals' unkind behavior may suggest the opposite desire, that professionals have exellent medical knowledge and skill and that they be sincere, concerned, respectful and warm emotionally toward their patients.

• Journal of the Korean earth science society
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• v.34 no.2
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• pp.173-186
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• 2013

The purpose of the study was to investigate the change of students' conceptual structures about sedimentary rocks through the field trip. A semantic network analysis method was utilized to assess the change. An open-ended questionnaire was developed to assess high school students' knowledge of sedimentary rock including its definition, classification, formation process, and characteristics. Fifteen high school students participated in the field trip of this study. The text data were analyzed using the semantic network analysis method. Results are as follows. First, high school students' conceptual structures about sedimentary rocks were more expanded after the field trip. Second, students' conceptual structures formed a 'small world network' by combining the sub-clusters. Third, the size of students' conceptual structures was decreased after a few month of field trip. Nonetheless, the connection among the clusters remained the same.

• Journal of Korean Academy of Nursing
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• v.42 no.4
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• pp.508-516
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• 2012

Purpose: The purpose of the study was to understand and explain the essences and structures of the experience of Korean women who have had a spinal cord injury. Methods: The data were collected in 2010 through individual in-depth interviews using open-ended questions. A total of 9 women with spinal cord injuries participated in the study. Each interview lasted about 2 hours. Verbatim transcripts were analyzed using phenomenological analysis. Results: Five theme clusters emerged from the analysis using Colaizzi's method: frozen mind with rigid body; shame due to restrictions of physical function and dependency; struggle to go back to the previous normal body; disabilities that are noticeable in everyday family life; rebirth by discarding the obsessions of the past. These theme clusters illustrate that although most participants faced very strange and unbearable situations in most aspects of life after the injury, they were empowered finally by finding their hope and by giving new meanings to the current existence. Conclusion: This study provides deep understanding of women with spinal cord injuries who are relatively alienated from society. Based on the results of the study, health professionals could develop effective nursing interventions to improve quality of life of these women.

• International Journal of Knowledge Content Development & Technology
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• v.7 no.1
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• pp.57-78
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• 2017

There are several statistical classification algorithms available for land use/land cover classification. However, each has a certain bias or compromise. Some methods like the parallel piped approach in supervised classification, cannot classify continuous regions within a feature. On the other hand, while unsupervised classification method takes maximum advantage of spectral variability in an image, the maximally separable clusters in spectral space may not do much for our perception of important classes in a given study area. In this research, the output of an ANN algorithm was compared with the Possibilistic c-Means an improvement of the fuzzy c-Means on both moderate resolutions Landsat8 and a high resolution Formosat 2 images. The Formosat 2 image comes with an 8m spectral resolution on the multispectral data. This multispectral image data was resampled to 10m in order to maintain a uniform ratio of 1:3 against Landsat 8 image. Six classes were chosen for analysis including: Dense forest, eucalyptus, water, grassland, wheat and riverine sand. Using a standard false color composite (FCC), the six features reflected differently in the infrared region with wheat producing the brightest pixel values. Signature collection per class was therefore easily obtained for all classifications. The output of both ANN and FCM, were analyzed separately for accuracy and an error matrix generated to assess the quality and accuracy of the classification algorithms. When you compare the results of the two methods on a per-class-basis, ANN had a crisper output compared to PCM which yielded clusters with pixels especially on the moderate resolution Landsat 8 imagery.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.413-415
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• 2015

How galaxy evolution differs in different environments is one of the intriguing questions in the study of structure formation. While galaxy properties are clearly distinguished in different environments in the local universe, it is still an open issue what causes this environmental dependence of various galaxy properties. To address this question, in this work, we investigate the build-up of passive galaxies over a wide redshift range, from z ~ 2 to z ~ 0.5, focusing on its dependence on galaxy environment. In the UKIDSS/Ultra Deep Survey (UDS) field, we identify high-redshift galaxy cluster candidates within this redshift range. Then, using deep optical and near-infrared data from Subaru and UKIRT available in this field, we analyze and compare the stellar population properties of galaxies in the clusters and in the field. Our results show that the environmental effect on galaxy star-formation properties is a strong function of redshift as well as stellar mass - in the sense that (1) the effect becomes significant at small redshift, and (2) it is stronger for low-mass ($M_{\ast}<10^{10}M_{\odot}$) galaxies. We have also found that galaxy stellar mass plays a more significant role in determining their star-formation property - i.e., whether they are forming stars actively or not - than their environment throughout the redshift range.

• Steel and Composite Structures
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• v.34 no.2
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• pp.261-277
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• 2020

The main objective of this research paper is to consider vibration analysis of vacancy defected graphene sheet as a nonisotropic structure via molecular dynamic and continuum approaches. The influence of structural defects on the vibration of graphene sheets is considered by applying the mechanical properties of defected graphene sheets. Molecular dynamic simulations have been performed to estimate the mechanical properties of graphene as a nonisotropic structure with single- and double- vacancy defects using open source well-known software i.e., large-scale atomic/molecular massively parallel simulator (LAMMPS). The interactions between the carbon atoms are modelled using Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential. An isogeometric analysis (IGA) based upon non-uniform rational B-spline (NURBS) is employed for approximation of single-layered graphene sheets deflection field and the governing equations are derived using nonlocal elasticity theory. The dependence of small-scale effects, chirality and different defect types on vibrational characteristic of graphene sheets is investigated in this comprehensive research work. In addition, numerical results are validated and compared with those achieved using other analysis, where an excellent agreement is found. The interesting results indicate that increasing the number of missing atoms can lead to decrease the natural frequencies of graphene sheets. It is seen that the degree of the detrimental effects differ with defect type. The Young's and shear modulus of the graphene with SV defects are much smaller than graphene with DV defects. It is also observed that Single Vacancy (SV) clusters cause more reduction in the natural frequencies of SLGS than Double Vacancy (DV) clusters. The effectiveness and the accuracy of the present IGA approach have been demonstrated and it is shown that the IGA is efficient, robust and accurate in terms of nanoplate problems.

• Journal of The Korean Astronomical Society
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• v.56 no.1
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• pp.97-115
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• 2023

We present the deep homogeneous UBV RI photometric data of 135,071 stars down to V ~ 23 mag and I ~ 22 mag toward the Carina Nebula. These stars are cross-matched with those from the previous surveys in the X-ray, near-infrared, and mid-infrared wavelengths as well as the Gaia Early Data Release 3 (EDR3). This master catalog allows us to select reliable members and determine the fundamental parameters distance, size, stellar density of stellar clusters in this star-forming region. We revisit the reddening toward the nebula using the optical and the near-infrared colors of early-type stars. The foreground reddening [E(B-V)_fg] is determined to be 0.35 ± 0.02, and it seems to follow the standard reddening law. On the other hand, the total-to-selective extinction ratio of the intracluster medium (R_V,cl) decreases from the central region (Trumpler 14 and 16, R_V,cl ~ 4.5) to the northern region (Trumpler 15, R_V,cl ~ 3.4). It implies that the central region is more dusty than the northern region. We find that the distance modulus of the Carina Nebula to be 11.9 ± 0.3 mag (d = 2.4 ± 0.35 kpc) using a zero-age main-sequence fitting method, which is in good agreement with that derived from the Gaia EDR3 parallaxes. We also present the catalog of 3,331 pre-main-sequence (PMS) members and 14,974 PMS candidates down to V ~ 22 mag based on spectrophotometric properties of young stars at infrared, optical, and X-ray wavelengths. From the spatial distribution of PMS members and PMS candidates, we confirm that the member selection is very reliable down to faint stars. Our data will have a legacy value for follow-up studies with different scientific purposes.