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Elementary Schooler's Recognition and Understanding of the Scientific Units in Daily Life (초등학교 학생들의 생활 속 과학단위 인식과 이해)

  • Kim, Sung-Kyu
    • Journal of Science Education
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    • v.36 no.2
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    • pp.235-250
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    • 2012
  • This paper aims to find out whether or not elementary school students recognize and understand scientific units that they encounter in their everyday life. To select appropriate units for the survey, first, scientific units in elementary textbooks of science and other science related subjects were analyzed. Then it was examined how these units were related to the learners' daily life. The participants in the current survey were 320 elementary school 6th graders. A questionnaire consisted of 11 units of science, such as kg for mass, km for distance, L for volume, V for voltage, s for time, $^{\circ}C$ for temperature, km/h for speed, kcal for heat, % for percentage, W for electric power, pH for acidity, which can often be seen and used in daily life. The students were asked to do the following four tasks, (1) to see presented pictures and select appropriate scientific units, (2) to write reasons for choosing the units, (3) to answer what the units are used for, and (4) to check where to find the units. The data were analyzed in terms of the percentage of the students who seemed to well recognize and understand the units, using SPSS 17.0 statistical program. The results are as follows: Regarding the general use of the units, it was revealed that almost the same units were repeated in science and other subject textbooks from the same grade. With an increase of the students' grade more difficult units were used. As for the use of each unit, it was found that they seemed to relatively well understand what these units kg, km, L, $^{\circ}C$, kcal, km/h, and W stand for, showing more than 91% right. However, the units of V, s, in particular, %, and pH did not seem to be understood. With respect to the recognition of the units, most students did not recognize such units as L for volume and pH for acidity, probably because the units are difficult at the elementary level in comparison to other scientific units. The students indicated that schools were the best place where they could learn and find scientific units related to life, followed by shops/marts, newspapers/broadcasting, streets/roads, homes, and others in that order. The results show that scientific unit learning should be conducted in a systematic way at school and that teachers can play a major role in improving students' understanding and use of the units.

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The Analysis on the Relationship between Firms' Exposures to SNS and Stock Prices in Korea (기업의 SNS 노출과 주식 수익률간의 관계 분석)

  • Kim, Taehwan;Jung, Woo-Jin;Lee, Sang-Yong Tom
    • Asia pacific journal of information systems
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    • v.24 no.2
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    • pp.233-253
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    • 2014
  • Can the stock market really be predicted? Stock market prediction has attracted much attention from many fields including business, economics, statistics, and mathematics. Early research on stock market prediction was based on random walk theory (RWT) and the efficient market hypothesis (EMH). According to the EMH, stock market are largely driven by new information rather than present and past prices. Since it is unpredictable, stock market will follow a random walk. Even though these theories, Schumaker [2010] asserted that people keep trying to predict the stock market by using artificial intelligence, statistical estimates, and mathematical models. Mathematical approaches include Percolation Methods, Log-Periodic Oscillations and Wavelet Transforms to model future prices. Examples of artificial intelligence approaches that deals with optimization and machine learning are Genetic Algorithms, Support Vector Machines (SVM) and Neural Networks. Statistical approaches typically predicts the future by using past stock market data. Recently, financial engineers have started to predict the stock prices movement pattern by using the SNS data. SNS is the place where peoples opinions and ideas are freely flow and affect others' beliefs on certain things. Through word-of-mouth in SNS, people share product usage experiences, subjective feelings, and commonly accompanying sentiment or mood with others. An increasing number of empirical analyses of sentiment and mood are based on textual collections of public user generated data on the web. The Opinion mining is one domain of the data mining fields extracting public opinions exposed in SNS by utilizing data mining. There have been many studies on the issues of opinion mining from Web sources such as product reviews, forum posts and blogs. In relation to this literatures, we are trying to understand the effects of SNS exposures of firms on stock prices in Korea. Similarly to Bollen et al. [2011], we empirically analyze the impact of SNS exposures on stock return rates. We use Social Metrics by Daum Soft, an SNS big data analysis company in Korea. Social Metrics provides trends and public opinions in Twitter and blogs by using natural language process and analysis tools. It collects the sentences circulated in the Twitter in real time, and breaks down these sentences into the word units and then extracts keywords. In this study, we classify firms' exposures in SNS into two groups: positive and negative. To test the correlation and causation relationship between SNS exposures and stock price returns, we first collect 252 firms' stock prices and KRX100 index in the Korea Stock Exchange (KRX) from May 25, 2012 to September 1, 2012. We also gather the public attitudes (positive, negative) about these firms from Social Metrics over the same period of time. We conduct regression analysis between stock prices and the number of SNS exposures. Having checked the correlation between the two variables, we perform Granger causality test to see the causation direction between the two variables. The research result is that the number of total SNS exposures is positively related with stock market returns. The number of positive mentions of has also positive relationship with stock market returns. Contrarily, the number of negative mentions has negative relationship with stock market returns, but this relationship is statistically not significant. This means that the impact of positive mentions is statistically bigger than the impact of negative mentions. We also investigate whether the impacts are moderated by industry type and firm's size. We find that the SNS exposures impacts are bigger for IT firms than for non-IT firms, and bigger for small sized firms than for large sized firms. The results of Granger causality test shows change of stock price return is caused by SNS exposures, while the causation of the other way round is not significant. Therefore the correlation relationship between SNS exposures and stock prices has uni-direction causality. The more a firm is exposed in SNS, the more is the stock price likely to increase, while stock price changes may not cause more SNS mentions.

Effect of Germination on the Quality and Amino acid Composition of Soymilk (대두발아(大豆發芽)가 대두유(大豆乳)의 품질(品質) 및 아미노산(酸) 조성(組成)에 미치는 영향)

  • Kim, Woo-Jung;Oh, Hoon-Il;Oh, Myung-Won;Byun, Si-Myung
    • Korean Journal of Food Science and Technology
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    • v.15 no.1
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    • pp.12-18
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    • 1983
  • Changes in the quality and amino acid composition of soymilk prepared from soaked and germinated soybeans were investigated. Soybeans were soaked in water for 3 hrs and germinated at $18{\pm}1^{\circ}C$ for 5 days followed by water extraction at room temperature, and then the soymilk was boiled for 30 min. The initial yields of total solid and protein after soaking were 80.7% and 88.6%, respectively and decreased slowly during germination. A slow decrease in lipids and a rapid reduction in total sugar content were found during germination. The change in protein fraction content of soymilk showed an initial increase followed by a gradual decrease. The intrinsic viscosity increased rapidly after 3 days of germination to maximum value at 4th day, then decreased. The amino acid composition of protein fraction of soymilk showed little change while that of nonprotein fraction changed significantly. After 4 days of germination, aspartic acid and alanine increased more than twice, and methionine and tyrosine decreased to half of their initial composition in soymilk prepared from soaked soybean.

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An Improved Method to Determine Corn (Zea mays L.) Plant Response to Glyphosate (Glyphosate에 대한 옥수수 반응의 개선된 검정방법)

  • Kim, Jin-Seog;Lee, Byung-Hoi;Kim, So-Hee;Min, Suk-Ki;Choi, Jung-Sup
    • Journal of Plant Biotechnology
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    • v.33 no.1
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    • pp.57-62
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    • 2006
  • Several methods for determining the response of corn to glyphosate were investigated to provide a fast and reliable method for identifying glyphosate-resistant corn in vivo. Two bioassays were developed. One assay is named 'whole plant / leaf growth assay', in which the herbicide glyphosate is applied on the upper part of 3rd leaf and the growth of herbicide-untreated 4th leaf is measured at 3 day after treatment. in this assay, the leaf growth of conventional corn was inhibited in a dose dependent from 50 to $1600{\mu}g/mL$ of glyphosate and growth inhibition at $1600{\mu}g/mL$ was 55% of untreated control. The assay has the potential to be used especially in the case that the primary cause of glyphosate resistance is related with a reduction of the herbicide translocation. Another assay is named 'leaf segment / shikimate accumulation assay', in which the four excised leaf segments ($4{\times}4mm$) are placed in each well of a 48-well microtiter plate containing $200{\mu}L$ test solution and the amount of shikimate is determined after incubation for 24 h in continuous light at $25^{\circ}C$. In this assay, 0.33% sucrose added to basic test solution enhanced a shikimate accumulation by 3 to 4 times and the shikimate accumulation was linearly occurred from 2 to $8{\mu}g/mL$ of glyphosate, showing an improved response to the method described by Shaner et al. (2005). The leaf segment / shikimate accumulation assay is simple and robust and has the potential to be used as a high throughput assay in the case that the primary cause of glyphosate resistance is related with EPSPS, target site of the herbicide. Taken together, these two assays would be highly useful to initially select the lines obtained after transformation, to investigate the migration of glyphosate-resistant gene into other weeds and to detect a weedy glyphosate-resistant corn in field.

A study on the recent trends of Islamic extremism in Indonesia (인도네시아 이슬람 극단주의 실태 연구)

  • Yun, Min-Woo
    • Korean Security Journal
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    • no.50
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    • pp.175-206
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    • 2017
  • The current study described the history of Islamic extremism and the recent expansion of international Islamic extremism in Indonesia. For doing so, both content analysis of the existing written documents and qualitative interviews were conducted. For the content analysis, media reports and research articles were collected and utilized. For qualitative interviews, Indonesian students and workers in Korea, Korean spouses married to Indonesian, and Korean missionaries in Indonesia were contacted and interviewed. Qualitative interview was conducted between 30 minutes and 2 hours. On the spot, interviews were recorded and later transcribed into written documents. Due to the difficulty of identification of population and the uneasiness of accessability to th study subjects, convenient sampling and snowball sampling were used. According to the results, Islamic extremism in Indonesia had a deep historical root and generally shared similar historical experience with other muslim countries such as Afghanistan, Pakistan, Egypt, and Saudi Arabia where Islamic extremism was deeply rooted in. That is, Islamic extremism began as a reaction to the western imperialism, after independence, Islamic extremism elements were marginalized in the process of construction of the modern nation-state, and Islamic extremist movement was radicalized and became violent during the Soviet-Afghan War. In addition, after 9.11, Islamic extremism in Indonesia was connected to international Islamic extremism network and integrated into such global movement. Such a historical development of Indonesian Islamic extremism was quite organized and robust. Meanwhile, the eastward infiltration and expansion of international Islamic extremism such as IS and Al Qaeda was observed in Indonesia. Particularly, such a worrisome expansion was more clearly visible in the marginalized and underdeveloped countrysides in Indonesia. Such expansion in Indonesia could negatively affect on the security of South Korea. Geographically, Indonesia is proximate to South Korea. This geographical proximity could be a direct security threat to the Korean society, as if Islamic extremism in North Africa and Middle East becomes a direct security threat to Europe. Considering the presence of a large size of Indonesian immigrant workers and communities in South Korea, such a concern is very realistic. The arrest of an Indonesian Islamic extremism supporter in November, 2016, could be a harbinger of the coming trend of Islamic extremism expansion inside South Korea. The Indonesian Islamic community in South Korea could be a passage of Indonesian Islamic extremism into the South Korean society. In this context, it is timely and necessary to pay an attention to the recent trend of Islamic extremism expansion in Indonesia.

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Impacts assessment of Climate changes in North Korea based on RCP climate change scenarios II. Impacts assessment of hydrologic cycle changes in Yalu River (RCP 기후변화시나리오를 이용한 미래 북한지역의 수문순환 변화 영향 평가 II. 압록강유역의 미래 수문순환 변화 영향 평가)

  • Jeung, Se Jin;Kang, Dong Ho;Kim, Byung Sik
    • Journal of Wetlands Research
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    • v.21 no.spc
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    • pp.39-50
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    • 2019
  • This study aims to assess the influence of climate change on the hydrological cycle at a basin level in North Korea. The selected model for this study is MRI-CGCM 3, the one used for the Coupled Model Intercomparison Project Phase 5 (CMIP5). Moreover, this study adopted the Spatial Disaggregation-Quantile Delta Mapping (SDQDM), which is one of the stochastic downscaling techniques, to conduct the bias correction for climate change scenarios. The comparison between the preapplication and postapplication of the SDQDM supported the study's review on the technique's validity. In addition, as this study determined the influence of climate change on the hydrological cycle, it also observed the runoff in North Korea. In predicting such influence, parameters of a runoff model used for the analysis should be optimized. However, North Korea is classified as an ungauged region for its political characteristics, and it was difficult to collect the country's runoff observation data. Hence, the study selected 16 basins with secured high-quality runoff data, and the M-RAT model's optimized parameters were calculated. The study also analyzed the correlation among variables for basin characteristics to consider multicollinearity. Then, based on a phased regression analysis, the study developed an equation to calculate parameters for ungauged basin areas. To verify the equation, the study assumed the Osipcheon River, Namdaecheon Stream, Yongdang Reservoir, and Yonggang Stream as ungauged basin areas and conducted cross-validation. As a result, for all the four basin areas, high efficiency was confirmed with the efficiency coefficients of 0.8 or higher. The study used climate change scenarios and parameters of the estimated runoff model to assess the changes in hydrological cycle processes at a basin level from climate change in the Amnokgang River of North Korea. The results showed that climate change would lead to an increase in precipitation, and the corresponding rise in temperature is predicted to cause elevating evapotranspiration. However, it was found that the storage capacity in the basin decreased. The result of the analysis on flow duration indicated a decrease in flow on the 95th day; an increase in the drought flow during the periods of Future 1 and Future 2; and an increase in both flows for the period of Future 3.

Study on ${\ulcorner}Bonchojeonghwa{\lrcorner}$ ${\ulcorner}Inbu{\lrcorner}$ ("본초정화(本草精華)" "인부(人部)"에 대한 고찰)

  • Kwon, Young-Bae;Eom, Dong-Myung;Kim, Hong-Kyoon
    • Korean Journal of Oriental Medicine
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    • v.11 no.2
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    • pp.1-22
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    • 2005
  • Study on ${\ulcorner}$Bonchojeonghwa${\lrcorner}$, which is one of the most specialized medical books in Boncho(Herbal Medicines), has been done by comparing it with some other medical books published in the Chosun dynasty. Though there was not meaningful result on e names of Korean medicine by this study and more study should follow in the future, from medicines recorded in ${\ulcorner}$Inbu (a chapter of medical ingredients from human body)${\lrcorner}$, we can reach on some results as follows by comparing in names of Korean medicines, their medical components, relevant explanations and etc. 1. Though it is difficult to know the author and the published year due to absence of the preface and epilogue, the publication is presumed to date from mid-l7th century, from the facts that Muheeong's ${\ulcorner}$Shinnongbonchokyongso${\lrcorner}$ is in the ${\ulcorner}$Bonchojeonghwa${\lrcorner}$'s reference list, and that there is not Hangul expression in the names of medicines nor the Ching dynasty’s books as a reference. 2. As a result of studying on the names of medicines recorded in ${\ulcorner}$Inbu${\lrcorner}$ of the Chosun dynasty's famous medical books, before ${\ulcorner}$ Bonchojeonghwa${\lrcorner}$, 19 medicines in ${\ulcorner}$Hyangyakjipsungbang${\lrcorner}$, 25 in ${\ulcorner}$Donguibogam${\lrcorner}$, and after ${\ulcorner}$Bonchojeonghwa${\lrcorner}$, 6 in ${\ulcorner}$Uimumbogam${\lrcorner}$, 4 in ${\ulcorner}$Kwangjebikup${\lrcorner}$, 11 in ${\ulcorner}$Bangyakhappyon${\lrcorner}$. And there are 37 medicines which are unique, ${\ulcorner}$Bonchojeonghwa${\lrcorner}$ has 31, the biggest records among them. 3. As a result of studying on the names of medicines recorded in 「Inbu」 of the ${\ulcorner}$Bonchojeonghwa${\lrcorner}$ and ${\ulcorner}$ Donguibogam${\lrcorner}$, 22 medicines were recorded in the both books, 9 were only recorded in ${\ulcorner}$Bonchojeonghwa${\lrcorner}$ and 3 were only recorded in ${\ulcorner}$Donguibogam${\lrcorner}$. 3 out of the total 37 medicines recorded in ${\ulcorner}$Inbu${\lrcorner}$ are only recorded in ${\ulcorner}$Hangyakjipsungbang${\lrcorner}$, and more study on this is needed. 4. From the contents recorded in ${\ulcorner}$Bonchojeonghwa${\lrcorner}$ and ${\ulcorner}$Donguibogam${\lrcorner}$, Benchojeonghwa is more in detail than Donguibogam. Thus, it was specialized in Boncho (Herbal Medicines) enough to be compared with general medical books, and played a good role in leading medical science's specialization. 5. Late Chosun dynasty's medical study on Boncho (Herbal Medicines) just like ${\ulcorner}$Bonchojeonghwa${\lrcorner}$ didn't lead to an active development of knowledge communication due to Confucian ethics. This limitation created the trend relying on general medical books or Yaksungga (songs of memorizing Boncho information) for Boncho information, but Boncho information of late Chosun dynasty became more in detail. That is, while Bokhapbang, combination of various medicines, were developed in China, Danmibang, single medicine but different intensity, were developed in Chosun. And thus, even though the kinds of medicines became smaller, but its contents became rather rich. 5. The medicines recorded in ${\ulcorner}$Bonchojeonghwa${\lrcorner}$ and ${\ulcorner}$Donguibogam${\lrcorner}$ are, from the view point of today, unclean or rather uncomfortable to use. Out those medicines, Bunchung, Hwasijangsanginkol, Hongyon, Gonidoogun, Inkondang had been used for a very long time and which proves their medical efficacy, and it is a great pity that they can’t be tried today due to the limitation by modern ethics.

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Yoo Young-kuk's Early Constructivism: Utopianism in (1937) (유영국(劉永國)의 초기 구성주의: <랩소디>(1937)에 나타난 유토피아니즘)

  • 유영아
    • The Journal of Art Theory & Practice
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    • no.9
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    • pp.93-121
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    • 2010
  • This study is about Yoo Young-kuk's early works which show constructivism, especially focus on his debut painting, for the 7th Dokuritsu Bijutsu Kyokai(獨立美術協會, the Independent Fine Arts Association) in Tokyo in 1937. The work was painted 2 years after he had started his study in Japan in 1935. It was the first painting that applied Constructivism. played an important role for Constructivism to be a leading art in his abstraction. After this picture, Yoo was soon devoted to the principles of Constructivism-- Faktura(material), Tektonika (tectonics), Tekhnika(technique), space, construction-- in his painterly reliefs. This article examined why Yoo concentrated on Constructivism for , what the characteristics were, and what influences were on other works from 1935 to 1949. In addition, I investigated in which period was painted and how Constructivism was spread in 1930s and early 1940s in chapter 2. I scrutinized Rhapsody in chapter 3. When Yoo created Japan was under the Fifteen Years War(1931-1945), and a major discourse was the Japanese Spirit at that time. It was connected with construction of an ideal nation which the Japanese ultra-national fascism pursued. This ideological pursuit was intended to unite the Japanese people for total war system and to restore a national dignity which had been fallen down due to Manchurian Incident(1931). Thus, on the hand, Kokusai Bunka Shinkokai(國際文化振興, The Society for International Cultural Relations) and the Nippon Kosaku Bunka Renmei(日本工作文化連盟, Japanese Werkbund) were supported financially by the Japanese government. On the other hand, the government enacted regulations to opposing parties which would distract Japanese people's unification. As for the Japanese art world, the merge of art groups was carried out through remodeling of Teikoku Bijutsuin(帝國美術院, The Imperial Fine Arts Academy) in 1935. This brought out continuous dispute and disorder. Young artists who felt difficulty of entering an entry of Imperial Fine Arts Exhibition repeatedly grouped and disbanded for small art groups to build their standing, which they pursued Surrealism and Abstract art. Among them Constructivism was considered as the latest trend and was popular in craft, design, architecture as well as fine arts. In the year before he painted , Avant-garde theatres including Constructivism theatre were introduced in a feature article of September, 1936 in Atelier, which was dealing with mainly avant-garde arts. Books related with Constructivism were translated into Japanese, and Gestaltung Education had become active since the publication of A Compendium of Gestaltung Education("構成敎育大系"(1934)), Salvador Dali(1904-1989) was also introduced, so Surrealism was drawn more attention by young artists. reflected popular trends. Yoo analyzed the Japanese avant-gardists' archaic taste in the Independent Art Association that he submitted his painting to. And then he entitled 'Rhapsody' which derives from Ancient Greek's epic poetry and deliberately set up images in a scene. In chapter 3, I examined a theme which was planned carefully by sorting favorite images from the Japanese Surrealism. was a result that Yoo Young-kuk observed objectively the phenomenon that young artists dreamt of Utopia or longed for Nostalgia passively and lethargically under wars. And then he otherized himself from that circumstance. First of all, for he used the typical icons of Japanese Surrealism such as the horizon, flowing clouds, and vast plain that were considered stereotypes of Arcadia. He, however distinguished himself form those Japanese Surrealists. He made his own vision about Utopia by referring Lyubov Popova(1889-1924)'s stage design. His objective point of view was expressed by positive and dynamic images of structure and human's actions. Constructivism which was attempted in had an effect on other early constructive works, and the principles of Constructivism were sought hard in reliefs, paintings, and photos.

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Automatic Notification System for Nuclear Medicine Blood Test (핵의학 혈액 검사의 경고치 자동통보 시스템)

  • Sim, Seong-Jae;Yoon, Pil-Young;Lim, Soo-Yeon;Cheon, Jun-Hong;Shin, Young-Kyoon;Yu, Seon-Hui;Cho, Si-Man
    • The Korean Journal of Nuclear Medicine Technology
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    • v.13 no.3
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    • pp.159-164
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    • 2009
  • Purpose: The automatic notification system for alarm values on blood tests conducted by this hospital is designed to immediately inform the attending physician of the result of a blood test, to help the relevant patient to promptly receive proper treatment, and furthermore, to reduce the likelihood of a fatal influence to the patient. From 2004, the clinical pathology department of this hospital has been operating an automatic notification system for blood tests, in relation to the items of WBC, Hb, Plt, PB cell morphology, Malaria, PT, aPTT, BT, fibrinogen, Ca, K, Na, Cl, Mg, Glucose, Ketone, Digoxin, PKU, Homocystinuria, 17-OHP, Neonatal TSH, and Galactosemia. Recently, the blood test room of the nuclear medicine department has been operating an automatic notification system for the alarm values of a blood test, in relation to three items of TSH, FT4, and 17-${\alpha}$-OH-PGR, and the details of its operation will be described here. Materials and Methods: The subjects were newborn babies that were receiving TSH, FT4, and $17{\alpha}$-OH-PGR prescriptions from February $19^{th}$ to May $11^{st}$, 2009, and who met with the following criteria: N2340 Thyroid-Stimulating Hormone: >$10{\mu}IU/mL$ (Reference value: 0.4~5.0). N2360 Free-Thyroxine: <$0.8{\mu}g/dL$ (Reference value: 0.8~1.9), N2444 $17{\alpha}$-OH-Progesterone: >$30\;{\mu}g/mL$ (Reference value: Male (0.6~3.42), Female follicular phase (0.19~1.8). The automatic notification system was operated by entering test items, relevant treatment departments, and standard values for reporting alarm values into the OCS program, and then transmitting results that met with the input conditions to the PDAs of the prescription and the attending physician by SMS. Results: Reporting an alarm value of the nuclear medicine blood test, which can have a fatal influence on the lives of patients, will help cure patients, improve the quality of the test, and furthermore, will increase the patient's satisfaction with the prescription and treatment of the test.

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Effect of Thresher Drum-Speed on the Quality of the Milled Rice (탈곡기의 급동 속도가 도정 손실에 미치는 영향)

  • 정창주;고학균;이종호;강화석
    • Journal of Biosystems Engineering
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    • v.4 no.2
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    • pp.10-24
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    • 1979
  • It is understood that drum speed of threshers and the moisture content of paddy grains to be threshed, respectively, have a signific:mt effect upon rice recoveries. Threshing under an increased drum speed would give a high performance rate, which is the general practice in custom work threshing in association with the use of semiauto-t hreshers. In the connection, however, it may result in the promotion of grain cracks and brokens of the rice product after milling. No reference or determination for an opti mum drum speed of the thresher is made available for various grain moisture contents at the time of the threshing operation and for different rice varieties especially for the Tongil rice varieties. This study was Conducted to find out and determine effects of the drum speeds on grain losses. The grain loss was quantified in terms of recovery rates of rice grains after treatments. Samples of each of all treatments were taken from the grain sampling plate placed in the grain conveyor of threshers. The grain sample plate was specially provided for this experiment. The brown-rice, milling, and head-rice recJveries were tes ted in the laboratory mill, respectively. Two rice varieties, Akibare and Suweon 251, each with five levels of different moist\ulcornerure contents at harvest and six levels of different drum speeds of threshers, were selected and used for treatments in this experiment. Two conditions of materials were tested in the thresher. One condition was to thresh the experimental material immediately after cutting, referred to as the wet-material thr eshing in this study. The other was to thresh the experimental :material, dried to contain about 15-16 percent of the grain moisture under the shocking operation. This is referred to as the dry-material threshing in this study. In additioon, field measurements for the grain moistures and drum-sdeeds under actual operation practices of the traditional field threshing, were conducted with a view to comparing with results of the experimental treatments. The results of the study may be summarized as follows: 1. For threshing treatments of Japonica-type rice variety (Akibare) , the effect of drum speeds and levels of grain moisture at cutting upon brown-rice, milling, and head-rice recoveries were found statistically significant. No significant difference in these recovery rates was noticed regardless of whether the material was threshed right after cutting or after drying by the shocking operation. 2. For the Tongil-sister rice variety(Suweon 251), milling recovery for the varied drum-speed and the grain~moisture level at cutting was found statististically significant. Th milling recovery was much significant when associated with the wet-material thres\ulcornerhing compared to the dry-material threshing. 3. The optimum peripheral velocity to be maintained at the edge of teeth on the thr\ulcorneresher drum was determined and may be recommanded as that of about 12 to 13 meters per second in view of the maximum recovery rate of the milled rice. 4. The effect of the drum speed on the qualitative loss of the milled rice was much greater in the case of the Tongil variety than Japonica. This effect was also greater by the wet-material threshing than by the dry-material threshing. Therefore, to apply the wet-material threshing operation for the Tongil variety, in particular, it should be very important to introduce the kind of threshing technology which would maintain the drum speed at optimum. 5. A field survey for the actual drum speed of threshing operations for 50 threshers indicated that average peripheral velccity was 12.76m/sec., and that the range was from 10.50 to 14.90m/sec. Approximately, more than 30% of the experimented and measured threshers were being operated at speeds which exceeded the optimum speed determined and assessed in this study. Accordingly, it should be highly desirable and important to take counter-measures against these threshing practices of operational overspeed.

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