• 천문학회보
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• 제44권2호
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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.

• 천문학회보
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• 제46권1호
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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.

• 한국도서관정보학회지
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• 제50권1호
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• pp.333-356
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• 2019

기존 상업 출판사 중심의 학술 커뮤니케이션 체제가 가져온 위기를 해소할 수 있는 대안으로 오픈액세스가 등장하였다. 본 연구는 계량정보분석 기법 가운데 하나인 동시출현단어 분석을 활용하여 오픈액세스 분야의 최신 연구 경향을 반영하는 지적구조를 제시하고 주제영역이 어떻게 구성되었는지 확인하는 것을 주된 목적으로 두며, 기존에 수행되었던 오픈액세스 지적구조 분석 연구와 비교분석하였다. 이를 위해 Web of Science로부터 오픈액세스 관련 키워드 검색을 통하여 2013년 1월 1일부터 2018년 11월 31일까지 출판된 문헌정보학 분야 논문 총 761편을 수집하였으며, 이들 논문 가운데 제목과 초록으로부터 명사구 형태의 키워드 총 2,321개를 추출하였다. 오픈액세스 지적구조 분석을 위해 네트워크 분석을 통하여 13개의 세부 주제영역이 추출되었으며, 지적관계를 시각화하여 전역 및 지역 중심성이 높은 키워드를 도출하였다. 또한 군집분석을 실시하고 이 결과를 다차원축적지도에 표시하여 키워드들과의 상관관계를 분석하였다. 이를 통해 앞으로 오픈액세스 영역에서의 연구 방향성 모색에 도움이 될 것으로 기대한다.

• 대한간호학회지
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• 제22권4호
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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.

• 한국지구과학회지
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• 제34권2호
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• pp.173-186
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• 2013

본 연구의 목적은 언어네트워크분석을 이용하여 야외지질학습에서 학생들의 퇴적암에 대한 개념 구조 변화를 알아보기 위한 것이다. 이를 위하여 고등학생 15명을 대상으로 퇴적암에 대한 정의, 분류, 생성과정 및 특징을 묻는 개방형 문항을 개발하였으며, 이 텍스트 자료를 언어네트워크분석법을 통해 분석하였다. 그 결과 첫째, 야외지질학습을 통해 학생들의 퇴적암에 대한 개념 구조는 사전에 비해 사후에 크게 확장되었다. 둘째, 학생들의 개념 구조를 구성하는 하위 클러스터는 서로 긴밀하게 연결되어 있는 '작은 세상 네트워크'를 형성하였다. 셋째, 학생들의 개념 구조의 규모는 수개월이 지난 후 감소하였지만, 하위 클러스터의 연결 상태는 그대로 유지하고 있었다.

• 대한간호학회지
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• 제42권4호
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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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• 제7권1호
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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.

• 천문학논총
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• 제30권2호
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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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• 제34권2호
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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.

• 천문학회지
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• 제56권1호
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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.