• Title/Summary/Keyword: Forming method

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Plasma resistance of Bi-Al-Si-O and Bi-Al-Si-O-F glass coating film (Bi-Al-Si-O와 Bi-Al-Si-O-F 유리 코팅막의 플라즈마 저항성)

  • Sung Hyun Woo;Jihun Jung;Jung Heon Lee;Hyeong-Jun Kim
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.34 no.4
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    • pp.131-138
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    • 2024
  • In this study, the microstructure and plasma resistance characteristics of 35Bi2O3-15Al2O3-50SiO2 (BiAl SiO) and 35Bi2O3-7.5Al2O3-50SiO2-7.5AlF3 (BiAlSiOF) glass layers coated on sintered alumina substrates were investigated according to the sintering conditions. The coated layers were formed using the bar coating method and then sintered at a temperature in the range of 700~900℃, which corresponds to the temperature before and after the hemisphere forming temperature, after a debinding process. The plasma resistance of the two coated glasses was approximately 2~3 times higher than that of the quartz glass, and in particular, the BiAlSiOF glass film with F added showed higher plasma resistance than BiAlSiO. It is thought to be due to the effect of suppressing the reaction with fluorine gas by adding fluorine to the glass. When the sintering time was increased at 700℃ and 800℃, the plasma resistance of both glasses improved, but when the sintering temperature was increased to 900℃, the plasma resistance decreased again (i.e., the etching rate increased). This phenomenon is thought to be related to the crystallization behavior of both glasses. The change in plasma resistance depending on the sintering conditions is thought to be related to the appearance of Al and Bi-rich phases.

A study on the classification of research topics based on COVID-19 academic research using Topic modeling (토픽모델링을 활용한 COVID-19 학술 연구 기반 연구 주제 분류에 관한 연구)

  • Yoo, So-yeon;Lim, Gyoo-gun
    • Journal of Intelligence and Information Systems
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    • v.28 no.1
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    • pp.155-174
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    • 2022
  • From January 2020 to October 2021, more than 500,000 academic studies related to COVID-19 (Coronavirus-2, a fatal respiratory syndrome) have been published. The rapid increase in the number of papers related to COVID-19 is putting time and technical constraints on healthcare professionals and policy makers to quickly find important research. Therefore, in this study, we propose a method of extracting useful information from text data of extensive literature using LDA and Word2vec algorithm. Papers related to keywords to be searched were extracted from papers related to COVID-19, and detailed topics were identified. The data used the CORD-19 data set on Kaggle, a free academic resource prepared by major research groups and the White House to respond to the COVID-19 pandemic, updated weekly. The research methods are divided into two main categories. First, 41,062 articles were collected through data filtering and pre-processing of the abstracts of 47,110 academic papers including full text. For this purpose, the number of publications related to COVID-19 by year was analyzed through exploratory data analysis using a Python program, and the top 10 journals under active research were identified. LDA and Word2vec algorithm were used to derive research topics related to COVID-19, and after analyzing related words, similarity was measured. Second, papers containing 'vaccine' and 'treatment' were extracted from among the topics derived from all papers, and a total of 4,555 papers related to 'vaccine' and 5,971 papers related to 'treatment' were extracted. did For each collected paper, detailed topics were analyzed using LDA and Word2vec algorithms, and a clustering method through PCA dimension reduction was applied to visualize groups of papers with similar themes using the t-SNE algorithm. A noteworthy point from the results of this study is that the topics that were not derived from the topics derived for all papers being researched in relation to COVID-19 (

    ) were the topic modeling results for each research topic (
    ) was found to be derived from For example, as a result of topic modeling for papers related to 'vaccine', a new topic titled Topic 05 'neutralizing antibodies' was extracted. A neutralizing antibody is an antibody that protects cells from infection when a virus enters the body, and is said to play an important role in the production of therapeutic agents and vaccine development. In addition, as a result of extracting topics from papers related to 'treatment', a new topic called Topic 05 'cytokine' was discovered. A cytokine storm is when the immune cells of our body do not defend against attacks, but attack normal cells. Hidden topics that could not be found for the entire thesis were classified according to keywords, and topic modeling was performed to find detailed topics. In this study, we proposed a method of extracting topics from a large amount of literature using the LDA algorithm and extracting similar words using the Skip-gram method that predicts the similar words as the central word among the Word2vec models. The combination of the LDA model and the Word2vec model tried to show better performance by identifying the relationship between the document and the LDA subject and the relationship between the Word2vec document. In addition, as a clustering method through PCA dimension reduction, a method for intuitively classifying documents by using the t-SNE technique to classify documents with similar themes and forming groups into a structured organization of documents was presented. In a situation where the efforts of many researchers to overcome COVID-19 cannot keep up with the rapid publication of academic papers related to COVID-19, it will reduce the precious time and effort of healthcare professionals and policy makers, and rapidly gain new insights. We hope to help you get It is also expected to be used as basic data for researchers to explore new research directions.

  • A Study on the Characteristics of Oddly Shaped Stone's Arrangement at Donggwoldo (동궐도(東闕圖)에 나타난 괴석(怪石)의 배치특성에 관한 연구)

    • Jung, Woo-Jin;Kim, Hwa-Ok;Park, Yool-Jin
      • Journal of the Korean Institute of Traditional Landscape Architecture
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      • v.32 no.2
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      • pp.12-26
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      • 2014
    • This study has researched the forms of arrangement and use of the oddly shaped stones which were used at palaces during Joseon Dynasty based on arrangements of stones as shown in Donggwoldo(東闕圖), and tried to identify its special features. The sorts of stone's arrangements which set formal patterns by assisting an axis in Donggwoldo can be classified as the single type using one stone, the symmetrical type using 2 stones symmetrically and the parallel type using 3 or more stones. The single type was used to endow a focal point and to accent centrality by arranging a stone on the axis performed from formal shaped buildings. The symmetrical type was used to show order and hierarchy by placing two odd-shaped stones on either side of a building. And the parallel type which is arranged three stones side by side, is put a middle stone on the central axis line to determine strong directional and frontality. Also similarity to method of arrangement of stones can be found from planting trees in a prominent way for scenery or planting trees symmetrically. Stones and trees can be chosen according to nature and scale of places and basically their effects of formation of axis and creating typical space is same. Based on these respect, the characteristics of arrangement of stones shown in Donggwoldo can be briefly summarized as follows. First, the oddly shaped stones were used by creating a centripetal space in order to show a grade of rank. Second, the distances among stones could be adjusted to the sizes of the architecture which was at the center. The aim was to provide stability through the balanced composition between the central axis and symmetrical structures. Third, the form of regularity was added by using stone vase in consideration of irregular shape of stone causing interference in forming regular symmetry. Fourth, a centrality was emphasized by adding change to central stones in the parallel type used 3 erect stones. Fifth, the sizes of stone were limited in order to make smooth for the mix and adjustment of its position with the types of other garden ornaments, so the oddly shaped stones in palace have portability. Sixth, the oddly shaped stones in palace which were appreciated as inspirational object basically were a sculpture of the same quality with suiseki (壽石), and the appreciative method, the composition and shape had developed in the same texture. Finally, the even number of stones by parallel type were arranged by equal partition. But odd number of stones followed the method with symmetrical arrangement on its center stone. These principles of stone arrangement are judged as distinguishing methods which oddly shaped stones was made and used in Joseon palaces.

    The Calculation Method of Cell Count for the Bloom-forming (Green tide) Cyanobacterium using Correlation between Colony Area and Cell Number in Korea (군체 크기와 세포수 상관관계를 이용한 녹조 유발 남조류의 세포수 산정 방법)

    • You, Kyung-A;Song, Mi-Ae;Byeon, Myeong-Seop;Lee, Hae-Jin;Hwang, Soon-Jin
      • Korean Journal of Ecology and Environment
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      • v.47 no.4
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      • pp.350-357
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      • 2014
    • Harmful Algal Bloom Alert System (HABAS) for drinking water supply is require to fast and accurate count as system monitoring of cyanobacterium occurrence and inducing a response action. We measured correlation between colony size and cell number including genus Anabaena, Aphanizomenon, Microcystis, Oscillatoria which are targeted at HABAS, deducted from standard formula, and suggested calculation method from colony size to the number of cell. We collected cyanobacteria samples at Han River (Paldang reservoir), Nakdong River (Dalseong weir, Changnyeonghaman weir) and Geum River (Gobok reservoir) from August to October, 2013. Also, we studied correlation between colony size and cell number, and calculated regression equation. As a result of correlation of harmful cyanobacteria by genus, Anabaena spp. and Aphanizomenon spp. having trichome showed high correlation coefficients more than 0.93 and Microcystis spp. having colony showed correlation coefficient of 0.76. As a result of correlation of harmful cyanobacteria by species, Anabaena crassa, Aphanizomenon flos-aquae, A. issatschenkoi, Oscillatoria curviceps, O. mougeotii having trichome showed high correlation coefficients from 0.89 to 0.96, and Microcystis aeruginosa, M. wessenbergii, M. viridis having colony showed correlation coefficients from 0.76 to 0.88. Compared with other genus Microcystis relatively showed low correlation because even species and colony size are the same, cell density and cell size are different from Microcystis strains. In this study, using calculated regression might be fast and simple method of cell counting. From now on, we need to secure additional samples, and make a decision to study about other species.

    The Effect of PNF Technique application Using Thera-Band on the Balance and Gait of Females over 65 years old (세라밴드를 이용한 PNF 기법 적용이 65세 이상 여성노인의 균형과 보행에 미치는 영향)

    • Kang, Dal-Won;Kang, Mi-Kyoung;Kang, Eun-Sil;Go, Yu-Ri;Kim, Da-Woon;Kim, Dae-Yong;Kim, Jung-Eun;Kim, Won-Hwang;Kim, Ja-Yeon;Kim, Hwan;Jung, Dae-In;Kim, Myung-Hoon;Kim, Sang-Yup;Lee, Dong-Jin;Kim, Chan-Kyu;Kim, Hyun-Jin
      • Journal of Korean Physical Therapy Science
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      • v.18 no.1
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      • pp.1-10
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      • 2011
    • Purpose: Study on the effect of the use of Proprioceptive Neuromuscular Facilitation(PNF) method by use of the direction and charge regulation which is the advantage of the Thera-band therapy on the walks and balances in old people and comparison with the result after applying the general PNF technique. Method: The study has been performed on 30 females over 65 years old. The study has been done by dividing the object group in 3 patterns, which are number 1, the comparison group of 10, two ones that are applied the PNF technique using Thera-band and third, the ones that are applied only the PNF technique. For the PNF and the Thera-band using PNF, we have divided the group into Combination of Isotonic technique and the Rhythmical stabilization technique according to the patient's acquaintance pattern and applied them to the patient's body. Evaluation was the balancing ability which was calculated by using the BIODEX Balance system / FRT and for the evaluation of walking ability, we have used the speed of walking for 10M / TUG. Result: In the comparison group of 10, the balancing ability and the walking ability did not change much before and after the experiment, which made it possible to compare the group with the other two easily(p>0.05). For the other two groups, we have recognized the enhancement both in the balancing ability and the walking ability, but they did not know much difference between themselves(p<0.05). Conclusion: Though there were not a big difference in the sense of improvement between the Thera-band using PNF and the PNF technique only, we could infer that these two therapy has enhanced much in the walking and balancing ability for people over 65 and through these result we can foresee that not only using the method shown in this study but also by using many advantages of Thera-band, we could diminish the tiredness of healer, enhance the efficiency of exercise in them and also by forming self training program for older people we could help them build the prevention program from falls.

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    Estimation of Soil Surface Temperature by Heat Flux in Soil (Heat flux를 이용한 토양 표면 온도 예측)

    • Hur, Seung-Oh;Kim, Won-Tae;Jung, Kang-Ho;Ha, Sang-Keon
      • Korean Journal of Soil Science and Fertilizer
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      • v.37 no.3
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      • pp.131-135
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      • 2004
    • This study was carried out for the analysis of temperature characteristics on soil surface using soil heat flux which is one of the important parameters forming soil temperature. Soil surface temperature was estimated by using the soil temperature measured at 10 cm soil depth and the soil heat flux measured by flux plate at 5 cm soil depth. There was time lag of two hours between soil temperature and soil heat flux. Temperature changes over time showed a positive correlation with soil heat flux. Soil surface temperature was estimated by the equation using variable separation method for soil surface temperature. Arithmetic mean using temperatures measured at soil surface and 10 cm depth, and soil temperature measured at 5 cm depth were compared for accuracy of the value. To validate the regression model through this comparison, F-validation was used. Usefulness of deductive regression model was admitted because intended F-value was smaller than 0.001 and the determination coefficient was 0.968. It can be concluded that the estimated surface soil temperatures obtained by variable separation method were almost equal to the measured surface soil temperature.

    A Comparative Study on the Recognition of Urban Agriculture between Urban Farmers and Public Officials (도시농업인과 공무원의 도시농업 인식 비교·평가)

    • Park, Won-Zei;Koo, Bon-Hak;Park, Mi-Ok;Kwon, Hyo-Jin
      • Journal of the Korean Institute of Landscape Architecture
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      • v.40 no.4
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      • pp.90-103
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      • 2012
    • The aim of this study is to be able to understand the problems within the urban agriculture policy promoted by the Government and local autonomous entity base on the comparison of the consciousness of the urban agriculture between urban farmers and public officials and to inquire into the further revitalization scheme in the end. For this purpose, this study drew implications through studying latest trend and the legislation of domestic and foreign urban agriculture and then conducted a questionnaire survey of urban farmers and public officials. Because of this research, the revitalization schemes of urban agriculture are as follows: First, it's necessary to secure the usable arable land, such as the green roof, community garden, as well as urban agriculture park, etc. Second, it is necessary to establish the urban agriculture relations act suited for the actual circumstances of our country and to back up the legislation at an institutional, technological level in terms of a nation in order to secure the durability of urban agriculture. Third, it is advisable to make a proposal about the problems in time of activities for cultivation by forming a network between urban farmers and public officials and to prepare the plan for the active exchange of farming technologies. Fourth, it's necessary to activate the community gardens by supplying the education through cultivation method & its management method, and a variety of urban-agriculture-participation programs. Fifth, it is necessary to set up the specialized and practical education through an institute for landscape architecture. Sixth, it is necessary to induce the spontaneous participation in urban agriculture from urban farmers accompanied by the activities for promotion that are worth arousing urban farmers' interest. Lastly, it is also necessary to establish a legal basis of urban agricultural parks and facilities as well as to promote a search for multilateral policies and their practice so that the further urban agriculture can be stably continued within city boundaries.

    The Correlation between Concepts on Chemical Reaction Rates and Concepts on Chemical Equilibrium in High School Students (고등학생들의 화학반응속도 개념과 화학평형 개념간의 상관관계)

    • Park, Guk-Tae;Kim, Gyeong-Su;Park, Gwang-Seo;Kim, Eun-Suk;Kim, Dong-Jin
      • Journal of the Korean Chemical Society
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      • v.50 no.3
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      • pp.247-255
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      • 2006
    • The purpose of this study was to investigate the correlation between concepts on chemical reaction rates and concepts on chemical equilibrium in high school students. The subjects of the investigation consisted of 120 third grade students attending high school in K city of Kyunggi province. For this study, questionnaire relevant to the subject of chemical reaction rates and chemical equilibrium was developed and the answers were analyzed. As a result of the study, a large percentage of high school students answered questions on reaction rates correctly, but only a small percentage of the students could give explanations. Many high school students answered questions on the rates of forward reactions correctly, but not the questions on the rates of reverse reactions. For the concepts on chemical equilibrium, many high school students gave correct answers when faced with equilibrium questions that only required the understanding of one side of the reaction. But the students could not answer the questions requiring understanding of both forward and reverse reactions as well. Overall, there was a little high correlation between concepts on chemical reaction rates and concepts on chemical equilibrium in high school students. Especially, high school students with little understanding of reverse reaction rates did not understand that chemical equilibrium is a dynamic equilibrium. Also, high school students with little understanding of the collision mechanism regarding chemical reaction rates did not understand the effect of concentration and catalyst factors on chemical equilibrium. And the correlation between concepts on chemical reaction rates and concepts on chemical equilibrium related to concentration and catalyst factors was low. In conclusion, the formation of scientific concepts on chemical reactions rates can decrease misconceptions on chemical equilibrium. Also the teaching-learning method limited to one side of a reaction can cause difficulty in forming the concepts on chemical dynamic equilibrium. Therefore, the development of a teaching-learning method which covers both the forward and reverse reactions can be effective in helping students form the concepts on chemical equilibrium.

    Effect of internal gap on retentivity in implant fixed prosthesis with lingual slot (설측 슬롯을 부여한 임플란트 고정성 보철물에서 내면 간격이 유지력에 미치는 영향)

    • Kim, Tae-Kyun;Lee, Kyu-Bok
      • The Journal of Korean Academy of Prosthodontics
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      • v.56 no.3
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      • pp.206-211
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      • 2018
    • Purpose: Recently, a method of forming a slot in the prosthesis lingual has been introduced to solve the occlusal and aesthetic disadvantages of screw-retained prosthesis in the manufacture of implant-fixed prosthesis and to ensure retrievability in cement retained prostheses. The purpose of this study is to investigate the effect of the internal gap on the removal of the prosthesis in the preparation of cement-retained implant prostheses with lingual slots. Materials and methods: Titanium abutment and internal gap of the zirconia prosthesis to be attached to the upper part were set to 30, 35, and $50{\mu}m$, respectively. Three for each type total 15 were produced for each type. The zirconia prosthesis formed a retrievable cement-type slot with a space of 1 mm at the location where the titanium abutment meets the shelf area. Autocatalytic resin cement was used for bonding of abutment and zirconia prosthesis, and the maximum removal stress value was measured in units of Ncm by using the customized equipment of the cemented specimen. The Kruskal-Wallis test was used to compare the three groups by statistical analysis (${\alpha}=.05$), modified by post hoc test the Mann-Whitney U-test and the Bonferroni correction method were used to compare the two methods (${\alpha}=.017$). Results: There was no statistically significant difference in removal stress between the $30{\mu}m$ group and the $35{\mu}m$ group in the internal gap (P = .032), and there was a significant difference between the $30{\mu}m$ group and the $50{\mu}m$ group, between the $35{\mu}m$ group and the $50{\mu}m$ group (P < .017). Conclusion: Thus, the internal gap of computer-aided design affected the retention between the zirconia prosthesis and the titanium abutment.

    A study on usage status of auxiliary oral hygiene devices in service workers behavior (일부 서비스 종사자들의 구강위생보조용품의 사용실태에 관한 조사 연구)

    • Kim, Myung-Eun
      • Journal of Korean society of Dental Hygiene
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      • v.8 no.3
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      • pp.37-52
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      • 2008
    • The purpose of this study was to provide basic data for oral health promotion of service worker and their effective interpersonal relationships forming through the evaluation about service workers' awareness of the auxiliary oral hygiene devices and using behavior of it. The survey was carried out questionnaire research targeting 400(service group 200, non-service group 200) and compared the two groups. The obtained results were as follow: 1. brushing behavior showed the highest ratio of 3~4 times/day(53.4%) in brushing frequency, up-down method(50.8%) in brushing method, after 5 minutes after the meals(45.0%) in brushing time, shape brush(56.6%) in brush change time. 2. service group used a lot more auxiliary oral hygiene devices than non-service group(50.9%). the frequency of use was toothpick(30.9%), gargle(29.9%), floss(13.5%), tongue cleaner(10.1%). 3. In comparison of two group about state of use, service group showed more higher ratio of floss(66.1%), tongue cleaner(64.4%), gargle(56.6%) than non-service group. non-service group showed more higher ratio of toothpick(54.6%) than service group 4. Service group used auxiliary oral hygiene devices by suggestions of dental clinic(53.6%) and didn't use them because of uncomfortable to use(45.4%) or didn't know how to use(21.6%). 5. As result of the awareness-related using rate of auxiliary oral hygiene devices, service group showed higher using ratio except toothpick than non-service group. especially gargle(54.8%), tongue cleaner(43.3%), floss(35.8%) were showed high. 6. service group took a regular checkups more than non-service group and showed the highest ratio of each 1 year(43.5%) in checkup period.

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