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

  • Chung, Chang Joo;Koh, Hak Kyun;Lee, Chong Ho;Kang, Hwa Seug
    • Journal of Biosystems Engineering
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    • v.4 no.2
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    • pp.9-9
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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?ure 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?hing compared to the dry-material threshing. 3. The optimum peripheral velocity to be maintained at the edge of teeth on the thr?esher 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.

Effects of Exogenous Thyroid Hormone $(T_3)$ on Skeletal Development and Physiological Conditions of Juvenile Black Seabream (Acanthopagrus schlegeli) (감성돔(Acanthopagrus schlegeli) 치어의 골격발달 및 생리적 조건에 미치는 외인성 갑상선호르몬$(T_3)$의 영향)

  • KANG Duk-Young;CHANG Young Jin
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.30 no.2
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    • pp.305-312
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    • 1997
  • Juveniles of black seabream, Acanthopagrus schlegeli were fed with the diets containing 0, 10, 20, 50 and 100 ppm of 3,5,3'-triiodo-1-thyronine $(T_3)$ respectively to assess the effect of this hormone on skeletal development and the change of physiological conditions for 50 days. $(T_3)$ treatment lasted for initial 40 days. Fish were fed the prescribed diet by hand to satiation in $2\~4$ times per day. After an initial 40 days period, skeletal development and abnormality were examined, and after a 50 days period, food intake, hepatosomatic index (HSI), thyroid cell height (TCH) and body proximate composition were also examined. Although toed intake was not different among 0, 10 and 20 ppm, the food intake of black seabream fed with the diets containing 50 and 100 ppm of $T_3$was significantly lower than those of 10 ppm. After the initial 40 days of $T_3$ administration, $T_3$ increased the relative growth of operculum, head, caudal fin and pectoral fin to body length, resulting in severe morphological abnormalities at the highest dose. Black seabream treated with 50 and 100 ppm of $T_3$ had abnormal shapes such as lordosis and opercular curl. The HSI parameters were reversely correlation with the dietary concentration of $T_3$. After the initial 40 days of this experiment, atrophy of thyroid gland was observed in fish administered with 50 and 100 ppm of $T_3$. On the 50th day of this experiment, atrophy of thyroid gland was observed only in the group administered with 100 ppm of $T_3$, and no difference was observed on TCH among the rest fours of experimental groups. At the end of the experiment the whore body proximate analyses indicated that there were significant effects of $T_3$ level on moisture, protein, lipid and ash contents.

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The effects of Moxibustion Therapy on Chronic Low Back Pain, Daily Living Disability and Sleep Pattern in Elderly Women (뜸요법이 여성노인의 만성요통, 일상생활기능장애 및 수면양상에 미치는 효과)

  • Kim, Hye-Jeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.7
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    • pp.301-310
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    • 2016
  • This is a nonequivalent control group non-synchronized experiment research to verify the effect of moxibustion therapy on efficient management of daily living disabilities and sleep patterns in elderly women with chronic low back pain. Total 12 sessions of moxibustion therapy were applied to elderly women(30 subjects in an experimental group and 30 subjects in a control group) in G City once a week for 12 weeks from March 15th to May $31^{st}$ 2015. Then the follow-up study was conducted 2 weeks after the post survey. For moxibustion, was applied to Shen-shu, Ashi point, Ta chang shu, Yang kuan and Yosu. 5 sheets of moxibustion were applied to 7 acupuncture points of Mugeukboyang moxibustion; Zu san li & Chu chi, Chung wan, Chung chi & Shui tao, Fei shu, Kao hung and Tien shu, Wijung respectively and experimental treatment was conducted. For assessing the degree of back pain, Visual Analog Scale(VAS) developed by Scott & Huskisson(1979) was used and for measuring the degree of daily living disability, Oswestry Disability Index, which was developed by Fairbank et al(1980) and translated and revised by Yim, Hyeon-sul et al.(1998), was used. For measuring sleep patterns, the sleep pattern measurement tool developed by Oh, Jin-su, Song, Mi-soon and Kim, Sin-mi(1998) was used. For data analysis, SPSS/WIN 18.0 was employed and Chi-square test, t-test and repeated measures ANOVA were performed. There were significant differences in pain score(F=2510.32, p<.001), daily living disability score(F=1937.82, p<.001) and sleep pattern score((F=15.54, p<.001) of elderly women that were provided with moxibustion therapy, compared to the control group. Therefore, it was found that moxibustion therapy made a positive contribution to reduction in pain and daily living disabilities and improvement in sleep quality. Based on this study finding, there is a need to apply moxibustion therapy to elderly people with chronic low back pain as a nursing intervention in future.

A study of conception of pyo(標).bon(本).joong(中) in the part of woongihak(運氣學) in negeong(內徑) (내경(內徑) 운기편(運氣篇)의 표(標).본(本).중(中) 개념에 대한 연구(硏究))

  • Baik, You Sang;Park, Chan-Guk
    • Journal of Korean Medical classics
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    • v.11 no.2
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    • pp.114-134
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    • 1998
  • The conception of pyo(標) bon(本) joong(中) in the part of woongihak(運氣學) of negeong(內徑) one of the important thing that decides the relation between six gi(六氣) and samyum and samyang(三陰三陽) or between each other's of samyum and samyang itself, it says that the relation of Pyo-rce(表裏). So this conception from the ancient times have been used to explain the theory of meridian(經絡) and organs(五臟六腑) and in other important field of oriental medicine - Sanghannon(傷寒論), it became basis of explanation of pcthoiogical principles in the system of six kyung(六徑). At first, the subject or this study is limited to the rament of $\ll$Somun(素問)$\gg$ in order to find the accurate and original meanings of pyo(標) bon(本) joong(中). And the meanings are studied by the way of expanding it's meaning with basic conceptions of woongihak(運氣學) and astronomy included in negeong(內徑). In this study, the results are summarized as the followings. 1. The contents of - the 68th chapter of negeong(內徑), concerning pyo(標) and joong(中) come under chogi(初氣) and joonggi(中氣) of the same chapter, after consideration of astronomical knowledge. And they become active during the period that last about 30days, a haft of one step(一步) of kaekgi(客氣). 2. Bon(本) as a kind of six gi(六氣) that is revealed from internal principle of something, that is to say Ohhaeng(五行), comes mainly under the kaekgi(客氣) of woongihak(運氣學) with the meaning of 'sign' is thai the specific properties of six gi(六氣) are revealed to our sight, so we can feel that through the change of nature, Joong(中) is the other property hidden in the inside of six gi(六氣), that is a portion of original nature(本性) like the bon(本). 3. The relation of pyo(標) and bon(本) is like that bctween the principle hidden inside in all things(理) and it's expression into the real world(氣) also similar to thai of yumyang(陰陽) and ohhaeng(五行). Therefore bon(本), though it means one of the six gi(六氣), hale the property of ohhaeng(五行) and pyo(標) is revealed, with an appearance of samyum-samyang(三陰三陰). 4. pyo(標) and joong(中) are also the both sides of yum(陰) and yang(陰) that revealed under the change of yumyang-ohhaengl(陰陽五行) in the nature. For example, if the one is yang(陰), the other is yum(陰). In the process that the change of all things is revealed out, first the property of pyo(標) appears strongly and then that of joong(中) appears comparatively weakly. But, in spite of the inhibitive relation of yumyang(陰陽), pyo(標) and joong(中) promote each other. 5. Under the course of change. It happens according to the bon(本), the property of ohhaeng(五行) in the case of soyang(少陽) and taeyum(太陰), because the effect of moisture(濕) and fire(火) that makes hyung(形) and gi(氣) is very strong in the universe. In the case of taeyang(太陽) and soyum(少陰), it happens according to the bon(本) and pyo(標) because they hare the polarity of water and fire(火水), at the same time, are not separated each other. In the case of yangmeong(陽明) and gualyum(厥陰), the change appears only according to the joong(中), but not strongly because the phase of yangmeong(陽明) and gualyum(厥陰) is a lull phase processing to the next one.

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A Study on the Cooking in 'The Kosa-sibi Jip' (2) ("고사십이집(攷事十二集)"의 조리가공에 관한 분석적 연구(2))

  • 김성미
    • Journal of the East Asian Society of Dietary Life
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    • v.4 no.3
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    • pp.1-19
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    • 1994
  • In this paper, twenty-five kinds of food presented in Sooljip(戌集) 5 and 6 of Food collections of 'Kosa-sibi Jip(攷事十二集)' have been classified into four : Staple food, subsidiary food, Tuck(rice cake) and Han-gwa(Korean confectionery), and Tang-jng and tea. Cooking processes have been examined and scientifically analyzed in terms of cooking, Fourteen kinds of Jook (thick gruel with cereal) as well as Urak-Jook were presented among the methods of making Jook, one of staple foods. Milk and ground rice were boiled together into Urak-Jook, which was nutritious because of carbohydrate, added to milk. Hong-sa Myun was mode of ground shrimps, ground bean, ground rice and flour which were kneaded together. It was a nutritiously balanced food. Nineteen kinds of Kimchi presented in this book were classified by the recipes. The five of Jook-soon Ja, U-so Ja, Tam-bok Ja and Jo-gang were made by adding red malt and cereals(boiled rice or candies). Jo-gang, Jo-ga and Jo-gwa-chae were made by adding salt and rice wine. With salt and fermenters added, eight were made. Chim-jup-jeo-ga was made by adding Jang(soy-bean sauce) and the inner chaff of wheat instead of salt. The four of Ka-za-san, Hwang-gwa-san, Tong-gwa-san and Jo-gang were made by adding salt and vinegar. Jo-gang was made by adding salt, rice wine, residue of rice wine and candies. The four of Kae-mal-ga, Ku-cho-chim-chae, Un-gu-hwa and Suk-hwa-chim-chim-chae were made by adding salt and spices. San-got-Kimchi was made without salt. San-got-Kimchi and Suk-hwa-chim-chae were made originally in Korea. Suk-hwa-chim-chae, in particular, was first classified as a kind of Kimchi in this book and oysters were added, which is notable. Pork could be preserved longer when smoked oven the weak fire of thatch ten days and nights. Dog meat was sauced and placed on the bones in a pot. A porcelain was put on the top of the pot. Flour paste sealed the gap between the porcelain and the pot. Some water was poured into the porcelain, and the meat was steamed, with two or three thatched sacks burned, which was a distilled dry steaming. This process has been in use up to now. Various cooking methods of chicken were presented from in Umsik-dimi-bang to in Chosun Musang Sinsik Yori Jebup. These methods were ever present regardless of ages. Such measuring units as Guin(斤) and Nyang(兩) were most frequently used in cooking processes of this book, except in case of Jang(soy bean sauce), vinegar and liquor. Twenty eight kinds of kitchenware and cookers were used, of which porcelains wee most used and pans and sieves followed. The scientific eight cooking methods were as follows. First, salt was refined through saturated solution. Next, it was recommended Hong-sa Myun containing shrimps should not be taken along with pork, which is thought to be a proper diet in terms of cholesterol contained by shrimps and pork. Third, meat was coated with thin gruel and quickly roasted and cleared of the dried gruel membrane, which prevented nutrients from exuding and helped to make the meat well-done. Fourth, The fruit of paper mulberry trees has the protease which can soften meat. Therefore when meat was boiled with th fruit of paper mulberry trees, it can be softened easily. Fifth, pork was smoked over the weak fire of thatch. Sixth, in cooking dog meat, distilled dry steaming raised the boiling point and made it possible to preserve meat longer. Seventh, in boiling the sole of a bear, lime was added, which made meat tender by making the pH lower or higher than that of raw meat. Finally, in boiling down rice gluten, a porcelain in the pot prevented boiling over the brim, which is applied to pots in which to boil medical herbs.

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A study of the effects of PDGF-BB on the characteristics of bone stromal and periodontal ligament cells (혈소판유래성장인자-BB가 골간질세포와 치주인대세포의 성상에 미치는 영향)

  • Kwon, Young-Hyuk;Park, Joon-Bong
    • Journal of Periodontal and Implant Science
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    • v.26 no.4
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    • pp.949-965
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    • 1996
  • The main goal of periodontal therapy is to restore the lost periodontal tissue and establish the attachment appratus. Current acceptable therapeutic techniques are included : removal of diseased soft tissue, demineralization of exposed root surface, using the barrier membrane for preventing the downgrowth of gingival epithelial cell, insertion of graft materials as a scaffolding action, and biological mediators for promoting the cell activity. The latest concept one among them has been studied which based on the knowledge of cellular biology of destructed tissue. Platelet-derived growth factor(PDGF) is one of the polypeptide growth factor which have been reported as a biological mediator to regulate activities of wound healing progress including cell proliferation, migration, and metabolism. The purposes of this study is to evaluate the influences of the PDGF as biological mediator to periodontal ligament and bone marrow cell. Both right and left maxillary first molar were extracted from rat which had treated with 0.4% ${\beta}-Aminopropionitril$ for 5 days, and feeded until designed date to sacrifice under anesthesisa. Periodontal ligament were removed from the extracted socket of the rat, and cultured with Dulbecco's Modified Essential Medium(DMEM) contained with 10% Fetal Bovine Serum, 100U/ml penicillin, $100{\mu}g/ml$ streptomycin, $0.5{\mu}g/ml$ amphotericin-B. Bone marrow cell were culture from bone marrow suspension with which washed out from femur with same medium. The study was performed to evaluate the effect of PDGF to periodontal ligament and bone cell, cell proliferation rate, total protein synthesis, and alkaline phosphatase activity of rat periodontal ligament(PDL) cell and bone stromal(RBS) cell in vitro. The effects of growth factors on both cells were measured at 3, 5th day after cell culture with (control group) or without growth factors(experimental group). The results were as follows: 1. The tendency of cell proliferation under the influence of PDGF showed more rapid proliferation pattern than control at 3 and 5 days after inoculation. 2. The activity of Alkaline phosphatase revealed 14, 80% increased respectively at 3, 5 days culture than control group. Measurements of ALPase levels indicated that PDL cells had significantly higher activity when compared with that of co-culture groups and GF only(P<0.05). And, ALPase activity in 10 days was higher than that of 7 days(P<0.05). 3. The tendency of formation of the mineralized nodule were observed dose-depend pattern of PDL cells. There was statistically significant difference among group l(PDL 100%), 2(PDL 70%:GF 30%), and 3(PDL 50%:GF 50%)(P<0.01). But, there was no difference among group 3, 4(PDL 30%:GF 70%), and 5(GF 100%). 4. Also, the number of nodule was greater in co-culture of PDL 70% and GF 30% than in culture of PDL 70%(P<0.05). From the above results, it is assumed that the PDGF on PDL cells and RMB cell culture. GF stimulates the cell growth, which is not that of PDL cells but GF. And, the activity of ALPase depends on the ratio of PDL cells, and ALPase may relate to the initial phase of nodule formation. Also, it is thought that the calcified nodule formation principally depends on PDL cells, is inhibited by GF, and affected by cell density. In conclusion, platelet-derived growth factor can promote rapid osteogenesis during early stage of periodontal tissue regeneration.

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KOREAN CHILD AND ADOLESCENT PSYCHIATRY - A REVIEW OF THE PAST, THE PRESENT AND THE FUTURE - (한국 소아 ${\cdot}$ 청소년정신의학 - 과거 ${\cdot}$ 현재 ${\cdot}$ 미래 -)

  • Hong, Kang-E
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
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    • v.14 no.2
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    • pp.139-149
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    • 2003
  • Objectives:To review the history of the development and current status of Korean Child and Adolescent Psychiatry and to propose the future tasks at this 20th anniversary of Korean Academy of Child and Adolescent Psychiatry. Methods:Records and publications of Korean Academy, personal communications with senior members of the Academy, the author's recollections and memoirs. Results:Korean Child Psychiatry started with opening Child Psychiatry Clinic at Seoul National University Hospital in 1979 and establishing Division of Child and Adolescent Psychiatry at the same hospital in 1980. A Child Psychiatry Study Group was formed in 1983 and it transformed into Korean Academy of Child and Adolescent Psychiatry in 1986. In the past 20 years, Korean child and adolescent psychiatry made an impressive progress and contributed significantly to the development of Korean medicine as well as to the establishment of child mental health service. There are 77 board-certified and 48 board-eligible child psychiatrists, and 18 child psychiatry fellows are in training as of 2003. Main forces of this successful introduction of child psychiatry are 1) 7 child psychiatry training centers at major university hospitals, 2) publication of Korean Journal of Child and Adolescent Psychiatry in 1990, 3) the establishment child psychiatry board certification system in 1996. Korean child psychiatry has extended its role in the international child psychiatry and took leadership in establishing Asian Society of Child and Adolescent Psychiatry and Allied Professions(ASCAPAP). Conclusion:Korean child psychiatry has achieved a remarkable progress for the past 20 years and is currently producing 15 or more child psychiatry each year. However, there are needs of more active involvements in adolescent problems, more active consultation-liaison services at general hospitals as well as community mental health institutions. More school consultation and preventive educational services are desired. There is a urgent need of carrying out more empirical studies with strong scientific rigor. Korean Academy should pay attention and provide assistance to the development of child psychiatry service in other countries in Asia.

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