• 대한치과의사협회지
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• 제53권7호
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• pp.476-484
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• 2015

Purpose: This study intended to analyze the validity of clinical effectiveness data of clinical trials testing systemic titrated extract of Zea Mays L. unsaponifiable fraction chemotherapeutic agent. Material and Methods: Among 5 clinical trials claimed as proof of clinical effectiveness on the Web site of the manufacturer of this chemotherapeutic agent, a review of 4 clinical trials, written in either Korean or English, was conducted. Data were extracted from studies for the following variables: year of publication, age, sample size, follow-up period, combination with contemporary periodontal treatments, randomization, randomization check, blinded measurement, and statistical test type. Results: The study subjects' age intervals were too diverse to decide a common target population to generalize the findings. No study stated clearly the rationale for the sample size determination. Follow-up period to observe the start of clinical effectiveness was inconsistent and decided without any rationale of pathophysiological latent period. Randomization to make the comparisons on the same start line was performed but failed in a study. Randomization effect was not checked in 4 studies. Performance of blinded measurement of clinical outcomes to prevent bias was unclear in 2 studies. Type of statistical test was inappropriate in 3 studies. Conclusions: Based on the analysis of the validity of data on clinical and demographic variables, the four available clinical trials have not demonstrated compelling evidence of therapeutic effectiveness of systemic titrated extract of Zea Mays L. unsaponifiable fraction chemotherapeutic agent to improve prognosis of periodontal disease either with the contemporary periodontal treatment or without it.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권1호
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• pp.81-98
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• 2013

Since Probabilistic Latent Semantic Analysis (PLSA) and Latent Dirichlet Allocation (LDA) were introduced, many revised or extended topic models have appeared. Due to the intractable likelihood of these models, training any topic model requires to use some approximation algorithm such as variational approximation, Laplace approximation, or Markov chain Monte Carlo (MCMC). Although these approximation algorithms perform well, training a topic model is still computationally expensive given the large amount of data it requires. In this paper, we propose a new method, called non-simultaneous sampling deactivation, for efficient approximation of parameters in a topic model. While each random variable is normally sampled or obtained by a single predefined burn-in period in the traditional approximation algorithms, our new method is based on the observation that the random variable nodes in one topic model have all different periods of convergence. During the iterative approximation process, the proposed method allows each random variable node to be terminated or deactivated when it is converged. Therefore, compared to the traditional approximation ways in which usually every node is deactivated concurrently, the proposed method achieves the inference efficiency in terms of time and memory. We do not propose a new approximation algorithm, but a new process applicable to the existing approximation algorithms. Through experiments, we show the time and memory efficiency of the method, and discuss about the tradeoff between the efficiency of the approximation process and the parameter consistency.

• 대기
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• 제26권3호
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• pp.473-482
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• 2016

An accurate determination of turbulent fluxes over an urban area is a challenging task due to its morphological diversity and associated flow complexity. In this study, an eddy covariance (EC) method is applied over a highly heterogeneous urban area in a small city (Gongju), South Korea to investigate the quantitative influence of 'coordinate tilt' in determining the turbulent fluxes of sensible heat, latent heat, momentum, and carbon dioxide mass. Two widely-used coordinate transform methods are adopted and applied to eight directional sections centered on the site to analyze a 1-year period EC measurement obtained from the urban site: double rotation (DR) and planar fit (PF) transform. The results show that mean streamline planes determined by the PF method are distinguished from the sections, representing morphological heterogeneity of the site. The sectional pitch angles determined by the DR method also compare well with those in the PF method. Both the PF and DR methods show large variabilities in the determined streamline planes at each directional section, implying that flow patterns may form in a complicate way due to the surface heterogeneity. Resulting relative differences of the turbulent fluxes, defined by $(F_{DR}-F_{PF})/F_{DR}$, are found on average +13% in sensible heat flux, +21% in latent heat flux, +37% in momentum flux, and +26% in carbon dioxide mass flux, which are larger values than those reported previously for fairly homogeneous natural sites. The fractional differences depend significantly on wind direction, showing larger differences in northerly winds at the measurement site. It is also found that the relative fractional differences are negatively correlated with the mean wind speed at both stable/unstable atmospheric conditions. These results imply that EC turbulent fluxes determined over heterogeneous urban areas should be carefully interpreted with considering the uncertainty due to 'coordinate tilt' effect in their applications.

• 인간식물환경학회지
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• 제24권6호
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• pp.563-572
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• 2021

Background and objective: The ongoing COVID-19 pandemic restricted daily life, forcing people to spend time indoors. With the growing interest in mental health issues and residential environments, 'pet plants' have been receiving attention during the unprecedented social distancing measures. This study aims to analyze the change in trends of pet plants before and during the COVID-19 pandemic and provide basic data for studies related to pet plants and directions of future development. Methods: A total of 2,016 news articles using the keyword 'pet plants' were collected on Naver News from January 1, 2018 to August 15, 2019 (609 articles) and January 1, 2020 to August 15, 2021 (1,407 articles). The texts were tokenized into words using KoNLPy package, ultimately coming up with 63,597 words. The analyses included frequency of keywords and topic modeling based on Latent Dirichlet Allocation (LDA) to identify the inherent meanings of related words and each topic. Results: Topic modeling generated three topics in each period (before and during the COVID-19), and the results showed that pet plants in daily life have become the object of 'emotional support' and 'healing' during social distancing. In particular, pet plants, which had been distributed as a solution to prevent solitary deaths and depression among seniors living alone, are now expanded to help resolve the social isolation of the general public suffering from COVID-19. The new term 'plant butler' became a new trend, and there was a change in the trend in which people shared their hobbies and information about pet plants and communicated with others in online. Conclusion: Based on these findings, the trend data of pet plants before and after the outbreak of COVID-19 can provide the basis for activating research on pet plants and setting the direction for development of related industries considering the continuous popularity and trend of indoor gardening and green hobby.

• 설비공학논문집
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• 제12권9호
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• pp.825-834
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• 2000

A heat exchanger analysis is performed to investigate the heating characteristics of cryogenic nitrogen by ambient air for the purpose of cryogenic automotive propulsion. The heat exchanger is a concentric triple-passage for supercritical nitrogen, and the radial fins are attached on the outermost tube for the crossflow of ambient air. The temperature distribution is calculated for the nitrogen along the passage, including the real gas properties of nitrogen, the fluid convections and the conductions through the tube walls and the fins. Since the wall temperature of the outer (ambient side) tube is very low in most cases, a heavy frost can be formed on the surface, affecting the heat exchange performance. By the method of the similarity between the heat and the mass transfer of moist air, the frost growth and the time-dependent effectiveness of the heat exchanger are calculated for various operating conditions. It is concluded that the frost formation can augment the heating of nitrogen during the initial period because of the latent heat, then gradually degrades the heat exchange because of the increased thermal resistance. Practical design issues are discussed for the flow rate of nitrogen, the velocity and humidity of ambient air, and the sizes of the fin.

• Journal of Microbiology and Biotechnology
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• 제26권9호
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• pp.1629-1635
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• 2016

A novel bacteriophage, PBES 02, infecting Cronobacter sakazakii was isolated and characterized. It has a spherical head of 90 nm in diameter and a tail of 130 nm in length, and belongs to Myoviridae as observed under a transmission electron microscope. The major virion protein appears to be 38 kilodaltons (kDa) in size. The latent period of PBES 02 is 30 min and the burst size is 250. Infectivity of the phage remained intact after exposure to temperatures ranging from 4℃ to 55℃ for 1 h. It was also stable after exposure to pHs ranging from 6 to 10 for 1 h. The phage effectively removed contaminating Cronobacter sakazakii from broth infant formula. PBES 02 has a double-stranded DNA genome of 149,732 bases. Its GC ratio is 50.7%. Sequence analysis revealed that PBES 02 has 299 open reading frames (ORFs) and 14 tRNA genes. Thirty-nine ORFs were annotated, including 24 related to replication and regulation functions, 10 related to structural proteins, and 5 related to DNA packaging. The genome of PBES 02 is closely related to that of two other C. sakazakii phages, CR3 and CR8. Comparison of DNA sequences of genes encoding the major capsid protein revealed a wide geographical distribution of related phages over Asia, Europe, and America.

• 한국콘텐츠학회논문지
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• 제22권4호
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• pp.37-46
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• 2022

본 연구는 한국과 몽골이 수교 이후부터 지금까지 외교관계 격상을 이루는 동안 국내에서는 어떤 분야에 관심을 가져왔는지 확인하고자 몽골과 관련된 국내 언론 보도를 중심으로 빅데이터 분석을 실시하였다. '몽골' 키워드로 검색된 13만여 개의 기사를 분석 대상으로 삼고, 관계 격상일을 기준으로 4개의 시기로 나누어 토픽 모델링을 실시하였다. 시기별 주요 토픽을 도출하여 살펴본 결과, 관계 격상에 따라 사라지는 이슈도 있었으나 초기에 나타났던 이슈들이 상당수 유지되면서 여러 분야의 이슈가 추가되어 나타나는 양상을 보였다. 즉, 기존의 정치, 역사 위주의 협력에서 문화, 교육, 보건, 항공, 기후 등으로 분야가 다양화되고 있었으며, 특히 민간교류 측면에서 토픽이 더욱 세분화되어 발전하는 양상을 보였다. 본 연구는 양국 간 외교 관계 연구에서 기존에 시도되지 않았던 새로운 분석 방법을 시도함으로써 막대한 양의 데이터를 바탕으로 결론의 신뢰성을 높이고 기존 연구에 새로운 시각을 제공하고 있다.

• Archives of Plastic Surgery
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• 제34권1호
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• pp.123-127
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• 2007

Purpose: Rigid external distraction(RED) is a highly effective technique for correction of maxillary hypoplasia in patients with cleft or syndromic craniosynostosis. Despite many advantages of RED, it also has the problem of relapse as the conventional advancement surgery. Bicoronal approach, that is the common approach to gain access to the craniofacial skeleton, had some morbidity, such as hair loss, sensory loss, wide scar and temporal hollowing. We present our clinical experience of RED distraction with minimal invasive approach and early rigid fixation to overcome these disadvantages. Methods: A 27-year-old female patient with Crouzon's disease underwent Le Fort III osteotomy and RED device application through the minimal invasive direct skin incisions. After the latent period of 5 days, distraction was undertaken until proper convexity and advancement were obtained. During the rigid retention period, inflammation occurred on the right cheek, and proper conservative managements were done including continuous irrigation. To maintain the stability of distraction, early rigid fixation was undertaken on the osteotomy sites through another skin incisions. Preoperative and postoperative orthodontic treatments were performed. Serial photographs and cephalometric radiographs were obtained preoperatively, after distraction and 6 months after distraction. Results: The cephalometric analysis demonstrated postoperatively significant advancement of the maxilla and improvement of facial convexity. After 6-month follow-up period, the maxilla was stable in the sagittal plane and no relapse was found. Facial scars were not noticeable and other deformity and morbidity did not occur. Conclusion: This effective and stable technique will be a good alternative for the patients who need large amount of distraction and for adult patients with severe maxillary hypoplasia or syndromic craniosynostosis.

• 가정간호학회지
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• 제30권2호
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• pp.141-154
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• 2023

Purpose: This study aimed to explore the social perception of visiting nursing before and after coronavirus disease (COVID-19). Methods: This survey-based study used online big data for comparative analysis by classifying the keywords related to visiting nursing searched on domestic portal sites before and after COVID-19. Results: According to the results of analyzing the Intertopic Distance Map based on Latent Dirichlet Allocation in this study, four topics were extracted, two each before and after COVID-19. The first topic before the COVID-19 period was termed "the expansion of visiting nursing subjects and services visiting nursing," while the second was termed "visiting nursing," which is related to customized welfare. The first topic after the COVID-19 period was termed "the suspension and resumption of visiting nursing services," while the second was "the development of a non-face-to-face home visit healthcare system". Conclusion: The results of this study can be used as useful reference data to contribute to future medical service delivery system reform policies starting at the end of COVID-19 and the revitalization of community care for visiting nursing.

• 정보관리학회지
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• 제32권1호
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• pp.135-152
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• 2015

이 논문의 연구목적은 컴퓨터공학 및 정보학 관련 연구동향을 분석하는 것이다. 이를 위해 텍스트마이닝 기법을 이용하여 DBLP(Digital Bibliography & Library Project)의 학술회의 데이터를 분석하였다. 대부분의 연구동향 분석 연구가 계량서지학적 연구방법을 사용한 것과 달리 이 논문에서는 LDA(Latent Dirichlet Allocation) 기반 다항분포 토픽모델링 기법을 이용하였다. 가능하면 컴퓨터공학 및 정보학과 관련된 광범위한 자료를 수집하기 위해서 DBLP에서 컴퓨터공학 및 정보학과 관련된 353개의 학술회의를 수집 대상으로 하였으며 2000년부터 2011년 기간 동안 출판된 236,170개의 문헌을 수집하였다. 토픽모델링 결과와 주제별 문헌 수, 주제별 학술회의 수를 조사하여 2000년부터 2011년 사이의 주제별 상위 저자와 주제별 상위 학술회의를 제시하였다. 주제동향 분석 결과 네트워크 관련 연구 주제 분야는 성장 패턴을 보였으며, 인공지능, 데이터마이닝 관련 연구 분야는 쇠퇴 패턴을 나타냈고, 지속 패턴을 보인 주제는 웹, 텍스트마이닝, 정보검색, 데이터베이스 관련 연구 주제이며, HCI, 정보시스템, 멀티미디어 시스템 관련 연구 주제 분야는 성장과 하락을 지속하는 변동 패턴을 나타냈다.