• 제목/요약/키워드: 효과차이

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Effect of the Level of Concentrates and Pasture Grazing on Growth, Reproductive Performance and Feed Efficiency in Spring born Hanwoo Heifers (농후사료 급여수준 및 방목이 춘계분만 한우 암송아지의 성장발육, 번식능력 및 사료이용성에 미치는 효과)

  • Kang, S. W.;Im, S. K.;Jeong, J. W.;Woo, J. S.;Jeon, K. J.
    • Journal of Animal Science and Technology
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    • 제45권1호
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    • pp.101-112
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    • 2003
  • This study was conducted to investigate the effect of the level of concentrates and pasture grazing in 60 head of spring born Hanwoo heifers(initial body weight; 125.3kg) for 450days from six to 21 months in age. Feeding trial was conducted with 5 treatment(twelve heads/ treatment) which were T1(1.5% of apparent body weight in concentrates and indoor feeding for over-all period), T2(0.5% of apparent body weight in concentrates for pre-pasture grazing and pasture grazing), T3(1.0% of apparent body weight in concentrates for pre-pasture grazing and pasture grazing), T4(1.5% of apparent body weight in concentrates for pre-pasture grazing and pasture grazing), T5(2.0% of apparent body weight in concentrates for pre-pasture grazing and pasture grazing). During the total experimental period, average daily gains by treatments ranged from 0.322 to 0.465kg(average 0.405kg) and higher in the order of T5, T4, T1, T3 and T2, and increased with the level of concentrates feeding for pre-pasture grazing. TDN intakes required per unit of kilogram gain were 9.13 to 9.79kg(average 9.49kg) higher in the order of T1, T3, T5, T4 and T2, For the grazing period, they were ranged from 12.39 to 12.98kg(average 12.68kg), and were not significantly different. But TDN requirements of grazing groups was higher about 15.6% than the indoor feeding group’s. The rate of roughage to concentrates by treatments were 57.8 to 73.6%(average 63.7%). The body weight of 15 and 21 month in ages, that is, the ages at puberty and first conception by treatments were 201.2 to 230.7kg(average 223.8kg) and 270.2 to 331.4kg (average 307.6kg), respectively, and the latter were high per unit of 20.4kg by increasing the level of concentrates feeding for pre-pasture grazing every 0.5% addition of apparent body weight. The age of 225 and 275kg in body weight, that is, the body weight at puberty and first conception by treatments were 14.0 to 17.6 month (average 15.3 month) and 17.9 to 21.7 month(average 19.4), respectively, and the latter were shorter about 1.3 month by increasing the level of concentrates feeding every 0.5% addition of apparent body weight. According to the above results, it may be concluded that spring born Hanwoo heifers are raised at indoor have to feed with 1.8% of body weight in concentrates under full feeding of rice straws for all period from six to 21 months in age, but with 1.5% of apparent body weight in concentrates for grazing period.

Structural and Compositional Characteristics of Skarn Zinc-Lead Deposits in the Yeonhwa-Ulchin Mining District, Southeastern Taebaegsan Region, Korea Part II : The Yeonhwa II Mine (연화(蓮花)-울진광산지대(蔚珍鑛山地帶) 스카른연(鉛)·아연광상(亞鉛鑛床)의 구조적(構造的) 및 성분적(成分的) 특징(特徵) 기이(其二) : 제2연화광산(第二蓮花鑛山))

  • Yun, Suckew
    • Economic and Environmental Geology
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    • 제12권3호
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    • pp.147-176
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    • 1979
  • The Yeonhwa II zinc-lead mine is characterized by a dozen of moderately dipping tabular orebodies of skarn and zinc-lead sulfides, developed in accordance with the ENE-trending bedding thrusts and bedding planes of the Pungchon Limestone and underlying Myobong Formation, mostly along the contacts of a ENE-trending sill and a NW-trending dike of quartz mononite porphyry. The orebodies occur in three groups: (1) the footwall Wolgok orebodies with respect to the sill, (2) the hangingwall Wolgok orebodies, and (3) the Seongok orebodies extended from dike contacts into carbonate beds. Mineral compositions of these orebodies are dominated by calc-silicates (skarn) associated with ore minerals of sphalerite, galena, and chalcopyrite, as well as sulfide gangue of pyrrhotite. A pair of exo- and endo-skerns in the Wolgok footwall contact aureole between the Pungchon Limestone and quartz monzonite porphyry on the -120 level represents a well-developed symmetrical pattern of mineral zoning: a garnet/quartz zone in the center of exoskarn, two zones of pyroxene with ore minerals on both sides of the garnet/quartz zone, further outwards-an epidote/chlorite-bearing hornfelsic zone in the Myobong slate beyond a zone of unaffected limestone, and an epidote-dominated zone of endo skarn on the opposite side toward fresh quartz monzonite porphyry. These features indicate a combination of two effects on the skarn formation: (1) differences in composition of the host rocks(sedimentary and ignous), and (2) progressive outward migration of inner zones on outer zones on the course of metasomatic replacement of the pre-existing minerals. Microprobe analyses of garnet, pyroxene, pyroxenoids, epidote, and chlorite for nine major elements on a total of 23 mineral grains revealed that: the pyroxenes are hedenbergitic, in most zones, with a gradual decrease of Fe- and Mn-contents toward the central zone, whereas the garnets are andraditic in outer zones, but are grossularitic in the central zone. This indicates a reverse relationship of Fe-contents between pyroxene and garnet across the exoskarn zones. Pyroxenoids are lacking in wollastonite but are dominated by pyroxmangite, rhodonite and bustamite, indicating a Mn-rich nature in bulk chemistry. Pseudomorphic fluorite after garnet occurs abundantly reflecting a fluorine-enhanced evidence of the skarn-forming fluids. Epidote contains 0.19-0.25mole fraction of pistacite, and chlorite is Mn-rich but is Mg-poor. Sulfide mineralization took place with the most Fe-rich pyroxene rather than with garnet as indicated by the fact that the highest value of hedenbergite mole fraction occurs in the ore-bearing pyroxene zone. The Yeonhwa II ores are characterized by high zinc and low lead in metal grade, with minor quantity of copper content in almost constant grade. The hangingwall Wolgok and Seongok orebodies, that formed in a more open environment with respect to their local configurations of geologic setting, are more variable in metal grades and ratios, than are the footwall Wolgok orebodies formed in a more closed condition in a narrow interval of sedimentary beds.

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Hydrochemical and Isotopic Characteristics, and Origin of Noble Gas for Low-temperature Hot Spring Waters in the Honam Area (호남지역 저온형 온천수의 수리지화학적 및 안정동위원소 특성과 영족기체의 기원에 관한 연구)

  • Jeong, Chan-Ho;Hur, Hyun-Sung;Nagao, Keisuke;Kim, Kyu-Han
    • Economic and Environmental Geology
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    • 제40권5호
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    • pp.635-649
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    • 2007
  • Geochemical composition, stable isotopes $({\delta}^{18}O,\;{\delta}D,\;{\delta}^{34}S)$ and noble gases(He, Ne and Ar) of nine hot spring water and three groundwater for five hot springs(Jukam, Hwasun, Dokog, Jirisan, Beunsan) from the Honam area were analyzed to investigate the hydrogeochemical characteristics and the hydrogeochemical evolution of the hot spring waters, and to interpret the source of sulfur, helium and argon dissolved in the hot spring waters. The hot spring waters show low water temperature ranging from 23.0 to $30.5^{\circ}C$ and alkaline characteristics of pH 7.67 to 9.98. Electrical conductivity of hot spring waters is $153{\sim}746{\mu}S/cm$. Groundwaters in this area were characterized by the acidic to neutral pH range$(5.85{\sim}7.21)$, the wide electrical conductivity range $(44{\sim}165{\mu}S/cm)$. The geochemical compositions of hot spring and groundwaters can be divided into three water types: (1) $Na-HCO_3$ water type, (2) Na-Cl water type and (3) $Ca-HCO_3$ water type. The hot spring water of $Ca-HCO_3$ water type in early stage have been evolved through $Ca(Na)-HCO_3$ water type into $Na-HCO_3$ type in final stage. In particular, Jurim alkaline(pH 9.98) hot spring water plotted at the end point of $Na-HCO_3$ type in the Piper diagram is likely to arrive into the final stage in geochemical evolution process. Hydrogen and oxygen isotopic data of the hot spring water samples indicate that the hot spring waters originated from the local meteoric water showing latitude and altitude effects. The ${\delta}^{34}S$ value for sulfate of the hot spring waters varies widely from 0.5 to $25.9%o$. The sulfur source of most hot spring waters in this area is igneous origin. However, The ${\delta}^{34}S$ also indicates the sulfur of JR1 hot water is originated from marine sulfur which might be derived ken ancient seawater sulfates. The $^3He/^4He\;and\;^4He/^{20}Ne$ ratios of the hot spring waters range from $0.0143{\times}10^{-6}\;to\;0.407{\times}10^{-6}\;and\;6.49{\sim}584{\times}10^{-6}$, respectively. The hot spring waters are plotted on the mixing line between air and crustal components. It means that the He gas in the hot spring waters was mainly originated from crustal sources. However, the JR1 hot spring water show a little mixing ratio of the helium gas of mantle source. The $^{40}Ar/^{36}Ar$ ratios of hot spring water are in the range from $292.3{\times}10^{-6}\;to\;304.1{\times}10^{-6}$, implying the atmospheric argon source.

Effects of Lime and NPK Application Rates on the Soil Characteristics after a 10-year Experiment in Oversown Hilly Pasture of Mixed Grass-Clover Sward I. Changes in the pH, contents of T-N, organic matter and available $P_{2}O_{5}$, coefficient of $P_{2}O_{5}$ absorption, and lime requirement by the soil depth (겉뿌림 산지초지에서 석회 및 3요소 시용수준이 10연후 토양특성에 미치는 영향 I. 토심별 pH, T-N, 유기물 및 유효인산 함량, 인기흡수계수와 석회소요량)

  • Jeong, Yeon-Gyu;Lee, Hyeok-Ho
    • Journal of The Korean Society of Grassland and Forage Science
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    • 제13권1호
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    • pp.49-57
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    • 1993
  • The main experiment related to this report was undertaken to assess the effects of two rates of $Ca(OH)_2$ (0, 250 kg/10a only at establishment) and five rates of N-$P_{2}O_{5}$-$K_2O$ (0-0-0, 0-10-10, 6-15-15, 12-20-20, 24-25-20 kg/10a/year) on the pasture establishment, on forage yield and quality, vegetation etc. After this 10-year main experiment, this pasture had been used to assess the effects of the above treatments on the soil characteristics in oversown hilly pasture of a grass-clover sward. This 1st part is concerned with the soil properties of pH-value. OM, T-N, avail. $P_{2}O_{5}$ and $P_{2}O_{5}$ absorption coefficient, and lime requirement by the soil depth. 1. The pH of the topsoil(0~l5 cm) was lowered from pH 5.12 of before the experiment to 4.90 of when $Ca(OH)_2$ was applied and to 4.68 of when $Ca(OH)_2$ was not applied. The pH decrease was more evident with the increase of NPK application rate and in the upper part of the top soil(0.0~7.5 cm). The additional application of lime was necessary in all the experiment blocks due to the strong acidity of the soil, and the amounts of lime requirement were increased with increased application rates of NPK and soil depth. 2. The contents of organic matter and T-N were increased in all the blocks by the establishment of the hilly pasture, and were higher in $Ca(OH)_2$ applied blocks than non-applied blocks. The contents were inversely correlated with the soil depth. No correlation was observed between the contents and the application rates of NPK. 3. The content of available $P_{2}O_{5}$-$K_2O$, was increased with the increased application of P, especially in the upper part of top soil. The content in the upper part(0.0~7.5 cm) was about twice of that in the lower part(7.5~15.0 cm). Since the contents of available $P_{2}O_{5}$$P_{2}O_{5}$/10a/year were applied, respectively), it is necessary to decrease the application rate of $P_{2}O_{5}$, gradually. The $P_{2}O_{5}$ absorption coefficient in topsoil (0.0~15.0 cm) was more or less higher when no lime and less $P_{2}O_{5}$, was applied. No correlation was observed in subsoil. 4. Further studies on the methods, rates, time of additional application of lime, and on the methods of decreased apllication of $P_{2}O_{5}$ should be performed for better management of oversown hilly pasture.

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Analysis of Prognostic Factors Related to Survival Time for Patients with Small Cell Lung Cancer (소세포폐암 환자의 생존기간에 관련된 인자 분석)

  • Kim, Hee-Kyoo;Yook, Dong-Seung;Shin, Ho-Sik;Kim, Eun-Seok;Lim, Hyun-Jeung;Lim, Tae-Kwan;Ok, Chul-Ho;Cho, Hyun-Myung;Jung, Maan-Hong;Jang, Tae-Won
    • Tuberculosis and Respiratory Diseases
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    • 제54권1호
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    • pp.57-70
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    • 2003
  • Background : Small cell lung cancer represents approximately 20% of all carcinomas of the lung, and is recognized as having a poor long term outcome compared to non-small cell lung cancer. Therefore, this study investigated the prognostic factors in small cell lung cancer patients in order to improved the survival rate by using the proper therapeutic methods. Material and method : The clinical data from 394 patients who diagnosed with small cell lung cancer and treated from 1993 to 2001 at the Kosin University Gospel Hospital, were analyzed. Result : There were 314 male patients (79.7%), and 80 female patients (20.3%). The number of those with limited disease was 177 (44.9%), and the number of those with extensive disease was 217 (55.1%). Overall, 366 out of 394 enrolled patients had died. The median survival time was 215 days (95% CI : 192-237days). The disease stage, Karnofsky performance state, 5% body weight loss for the recent 3 months, chemotherapy regimens, and the additive chest radiotherapy were identified as being statistically significant factors for the survival time. The median survival times of the supportive care group, one anticancer therapy, and two or more treatment groups were 17 days, 211 days, and 419 day, respectively (p<0.001). These data emphasize the importance of anticancer treatment to improve survival time for patients. The group of concurrent chemoradiotherapy (30 patients) showed significantly longer survival time than the group given sequential chemoradiotherapy (55 patients) (528 days versus 373 days, p=0.0237). The favorable prognostic factors of laboratory study were groups of leukocyte =8,000/mm3, ALP=200 U/L, LDH=450 IU/L, NSE=15 ng/mL, s-GOT=40 IU/L. In extensive disease, there was no difference according to the number of metastatic site. However, the median survival time of patients with ipsilateral pleural effusion had longer than patients having other metastatic sites. According to the survey periods, three groups were divided into 1993-1995, 1996-1998, and 1999-2001. The median survival time was significantly prolonged after 1999 in comparison to previous groups (177 days, 194 days, 289 days, p=0.001, 0.002, respectively). Conclusion: Disease stage and 5% body weight loss for recent 3 months at diagnostic state were significant prognostic factors. In addition, the performance status, serum ALP, LDH, NSE, CEA levels also appear to be prognostic factors. The survival time of those patients with small cell lung cancer has been prologned in recent years. It was suggested that the used of the EP (etoposied and cisplatin) chemotherapy method and concurrent chemoradiotherapy for patients with a limited stage contributed to the improved survival time.

The Role of Primary Radiotherapy for Squamous Cell Carcinoma of the Suprag1ottic Larynx (성문상부 상피세포암에서의 근치적 방사선치료의 역할)

  • Kim, Won-Taek;Kim, Dong-Won;Kwon, Byung-Hyun;Nam, Ji-Ho;Hur, Won-Joo
    • Radiation Oncology Journal
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    • 제18권4호
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    • pp.233-243
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    • 2000
  • Purpose : First of all, this study was performed to assess the result of curative radiotherapy and to evaluate different possible prognostic factors for squamous cell carcinoma of the supraglottic larynx treated at the Pusan National University Hospital. The second goal of this study was by comparing our data with those of other study groups, to determine the better treatment policy of supraglottic cancer in future. Methods and Material : Thirty-two patients with squamous cell carcinoma of the supraglottic larynx were treated with radiotherapy at Pusan National University Hospital, from August 1985 to December 1996. Minimum follow-up period was 29 months, Twenty-seven patients (84.4$\%$) were followed up over 5 years. Radiotherapy was delivered with 6 MV photons to the primary laryngeal tumor and regional iymphatics with shrinking field technique. Ail patients received radiotherapy under conventional fractionated schedule (once a day). Median total tumor dose was 70.2 Gy (range, 55.8 to 75.6 Gy) on primary or gross tumor lesion. Thirteen patients had Induction chemotherapy with cisplatln and 5-fluorouracil (1-3 cycles). Patient distribution, according to the different stages, were as follows: stage I, 5/32 (15.6$\%$): stage II, 10/32 (31.3$\%$); stage III, 8/32 (25$\%$): stage IV, 9/32 (28.1$\%$). Results :The 5-year overall survival rate of the whole series (32 patients) was 51.7$\%$. The overall survival rate at 5-years was 80$\%$ in stage I, 66.7$\%$ in stage II, 42.9$\%$ in stage III, 25$\%$ in stage IV (p=0.0958). The S-year local control rates after radiotherapy were as fellows: stage I, 100$\%$; stage II, 60$\%$ stage III, 62.5$\%$; stage IV, 44.4$\%$ (p=0.233). Overall vocal preservation rates was 65.6$\%$, 100% In stage I, 70% in stage II, 62.5$\%$ In stage III, 44.4$\%$ in stage IV (p=0.210). There was no statistical significance in survival and local control rate between neoadjuvant chemotherapy followed by radiotherapy group and radiotherapy alone group. Severe laryngeal edema was found in 2 cases after radiotllerapy, emergent tracheostomy was done. Four patients were died from distant metastsis, . three in lung, one in brain. Double primary tumor was found in 2 cases, one in lung (metachronous), another in thyroid (synchronous). Ulcerative lesions were revealed as unfavorable prognostic factor ( p=0.0215), and radiation dose (more or less than 70.2 Gy) was an important factor on survival (p=0.002). Conclusion : The role of radiotherapy treatment of supraglottic carcinoma is to important factor on survival and to preserve the laryngeal function. Based on our data and other studies, early and moderately advanced supragiottic carcinomas could be successfully treated with either consewative surgery or radiotherapy alone. Both modalities showed similar results in survival and vocal preservation. For the advanced cases, radiotherapy alone is Inadequate for curative aim and surgery combined with radiotherapy should be done in operable patients. When patients refuse operation or want to preserve vocal function, or for the patients with inoperable medical conditions, combined chemoradiotherapy (concurrent) or altered fractionated radiotherapy with or without radiosensitizer should be taken into consideration in future.

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Comparison of Naphthalene Degradation Efficiency and OH Radical Production by the Change of Frequency and Reaction Conditions of Ultrasound (초음파 주파수 및 반응조건 변화에 따른 나프탈렌 분해효율과 OH 라디칼의 발생량 비교)

  • Park, Jong-Sung;Park, So-Young;Oh, Je-Ill;Jeong, Sang-Jo;Lee, Min-Ju;Her, Nam-Guk
    • Journal of Korean Society of Environmental Engineers
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    • 제31권2호
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    • pp.79-89
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    • 2009
  • Naphthalene is a volatile, hydrophobic, and possibly carcinogenic compound that is known to have a severe detrimental effect to aquatic ecosystem. Our research examined the effects of various operating conditions (temperature, pH, initial concentration, and frequency and type of ultrasound) on the sonochemical degradation of naphthalene and OH radical production. The MDL (Method detection limit) determined by LC/FLD (1200 series, Agilient) using C-18 reversed column is measured up to 0.01 ppm. Naphthalene vapor produced from ultrasound irradiation was detected under 0.05 ppm. Comparison of naphthalene sonodegradion efficiency tested under open and closed reactor cover fell within less than 1% of difference. Increasing the reaction temperature from $15^{\circ}C$ to $40^{\circ}C$ resulted in reduction of naphthalene degradation efficiency ($15^{\circ}C$: 95% ${\rightarrow}$ $40^{\circ}C$: 85%), and altering pH from 12 to 3 increased the effect (pH 12: 84% ${\rightarrow}$pH 3: 95.6%). Pseudo first-order constants ($k_1$) of sonodegradation of naphthalene decreased as initial concentration of naphthalene increased (2.5 ppm: $27.3{\times}10^{-3}\;min^{-3}\;{\rightarrow}$ 10 ppm : $19.3{\times}10^{-3}\;min^{-3}$). Degradation efficiency of 2.5 ppm of naphthalene subjected to 28 kHz of ultrasonic irradiation was found to be 1.46 times as much as when exposed under 132 kHz (132 kHz: 56%, 28 kHz: 82.7%). Additionally, its $k_1$ constant was increased by 2.3 times (132 kHz: $2.4{\times}10^{-3}\;min^{-1}$, 28 kHz: $5.0{\times}10^{-3}\;min^{-1}$). $H_2O_2$ concentration measured 10 minutes after the exposure to 132 kHz of ultrasound, when compared with the measurement under frequency of 28 kHz, was 7.2 times as much. The concentration measured after 90 minutes, however, showed the difference of only 10%. (concentration of $H_2O_2$ under 28 kHz being 1.1 times greater than that under 132 kHz.) The $H_2O_2$ concentration resulting from 2.5 ppm naphthalene after 90 minutes of sonication at 24 kHz and 132 kHz were lower by 0.05 and 0.1 ppm, respectively, than the concentration measured from the irradiated M.Q. water (no naphthalene added.) Degradation efficiency of horn type (24 kHz) and bath type (28 kHz) ultrasound was found to be 87% and 82.7%, respectively, and $k_1$ was calculated into $22.8{\times}10^{-3}\;min^{-1}$ and $18.7{\times}10^{-3}\;min^{-1}$ respectively. Using the multi- frequency and mixed type of ultrasound system (28 kHz bath type + 24 kHz horn type) simultaneously resulted in combined efficiency of 88.1%, while $H_2O_2$ concentration increased 3.5 times (28 kHz + 24 kHz: 2.37 ppm, 24 kHz: 0.7 ppm.) Therefore, the multi-frequency and mixed type of ultrasound system procedure might be most effectively used for removing the substances that are easily oxidized by the OH radical.

A Study on the Morphological Structure of Sasul-Sijo (사설시조의 형태구조 연구)

  • Won, Yong-Moon
    • Sijohaknonchong
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    • 제23집
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    • pp.161-188
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    • 2005
  • The purpose of this study was to delve into the morphological types of Sijo in an effort to determine the morphological structure of Sasul-sijo, and it's also attempted to present standard about how to discriminate Pyong-si, Eos-sijo and Sasul-sijo from one another from a morphological standpoint. It's suggested that Si with tee Jangs, six verses and 12 stanzas or more, with three Jangs, seven verses and 14 stanzas or more, and with three Jangs, eight verses and 16 stanzas or more should respectively be called Pyong-sijo, Eos-sijo and Sasul-sijo. After what Sijo was and what's not were discussed, how to distinguish Eos-sijo from Sasul-sijo was described, and finally, the structure of Sasul-sijo was presented. As for Sijo and non-Sijo, the types of works that consisted of tee Jangs, like Sijo, yet didn't suit its framework and Yuljo and were written in Chinese characters were regarded as non-Sijo. Concerning discrimination between Eos-si and Sasul-sijo, the type of Sijo that included one more or higher number of verse(s) and two more or higher number of stanzas in one of three Jangs was defined as Eos-sijo, and the type of Sijo that involved two more or higher number of verses and four more or higher number of stanzas in one of three Jangs was called Sasul-sijo. In other words, Eos-sijo contained one more verse in one of tee Jangs, and Sasul-sijo included one more Jang in one tee Jangs. The sort of Sijo that contained one more Jang in one of three Jangs could be viewed as Sasul-sijo. Regarding the structure of Sasul-si, there should be three Jangs, eight verses and 16 stanzas in one piece of Sasul-sijo. Any type of Sijo that contained two more or higher number of verses and four more or higher number of stanzas could be called Sasul-sijo. Such an addition of verse and stanza could done in various ways. The examples were (1) adding stanzas the first Jang, 2) adding stanzas to the second Jang, (3) adding stanzas to the final Jang, (4) adding stanzas to both the first and Second Jangs, (5) adding stanzas to th the second and final Jangs, and (6) adding stanzas to all the first, second and third Jangs at the same time. Besides, there was an extremely broad gap between the numbers of verse and stanza in Sasul-sijo, which ranged from a low of eight stanzas to a high of 87 ones in one of three Jangs.

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A THREE-DIMENSIONAL FEM COMPARISON STUDY ABOUT THE FORCE, DISPLACEMENT AND INITIAL STRESS DISTRIBUTION ON THE MAXILLARY FIRST MOLARS BY THE APPLICATION OF VAR10US ASYMMETRIC HEAD-GEAR (비대칭 헤드기어의 적용시 상악제 1 대구치에 나타나는힘과 변위 및 초기 응력분포에 관한 3차원 유한요소법적 연구)

  • Kim, Jong-Soo;Cha, Dyung-Suk;Ju, Jin-Won;Lee, Jin-Woo
    • The korean journal of orthodontics
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    • 제31권1호
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    • pp.25-38
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    • 2001
  • The purpose of this study was to compare the force, the displacement and the stress distribution on the maxillary first molars altered by the application of various asymmetric head-gear. For this study, the finite element models of unilateral Cl II maxillary dental arch was made. Also, the finite element models of asymmetric face-bow was made. Three types of asymmetric face-bow were made : each of the right side 15mm, 25mm and 35mm shorter than the left side. We compared the forces, the displacement and the distribution of stress that were generated by application of various asymmetric head-gear, The results were as follows. 1. The total forces that both maxillary first molars received were similar in all groups. But the forces that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow shortened. 2. In lateral force comparison, the buccal forces that normally positioned tooth received were increased as the length of the outer-bow shortened, and the buccal fortes that mesially positioned tooth received were decreased as the length of the outer-bow shortened. Though the net lateral force moved to the buccal side of normally positioned tooth as the length of the outer-bow shortened, both maxillary first molars received the buccal force. That showed 'Avchiai Expansion Effect' 3. The distal forces, the extrusion forces and the magnitudes of the crown distal tipping that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow was shortened. 4. The magnitude of the distal-in rotation that normally positioned tooth received were increased as the length of the outer-bow was shortened. But, mesially positioned tooth show two different results. For the outer-bow 15mm shortened, mesially positioned tooth showed the distal-in rotation, hut for the outer-bow 25mm and 35mn shortened, mesially positioned tooth showed the distal-out rotation. Thus, the turning point exists between 15mm and 25mm. 5. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the compressive stress in the distobuccal root of the normally positioned tooth moved from the palatal side to the distal side and the buccal side successively as the length of the outer-bow shortened. 6. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the magnitudes of stress were altered but the total stress distributions were not altered in the mesiobuccal root and the palatal root of normally positioned tooth, and also three roots of mesially positioned tooth as the length of the outer-bow shortened.

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Different Perceptions, Knowledge, and Attitudes of Elementary, Middle, and High School Students regarding Irradiated Food, Nuclear Power Generation, and Medical Radiation (초, 중, 고등학생의 방사선조사식품, 원자력발전, 의료방사선에 대한 인식, 지식, 태도 차이)

  • Han, Eun Ok;Kim, Jae Rok;Choi, Yoon Seok
    • Journal of Radiation Protection and Research
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    • 제39권2호
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    • pp.118-126
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    • 2014
  • A survey was conducted on perceptions, knowledge, and attitudes of elementary, middle, and high school students, who will lead public opinion in the future, regarding irradiated food, nuclear power generation, and medical radiation. These topics urgently require general social acceptability among various fields in which radiation is used. Educational methods to enhance social acceptability were partially discovered. First, it is necessary to implement different strategies when designing courses for female and male students. Male students have higher levels of objective knowledge (p<0.039) of irradiated food, necessity (p<0.001) and objective knowledge (p<0.001) of nuclear power generation, approval of building a nuclear power plant in the nation (p<0.001), necessity (p<0.001) and objective knowledge (p<0.001) of medical radiation, and attitudes regarding using medical radiation (p<0.007, p<0.001). Second, the educational effect of explanations to help increase national understanding of the necessity and safety of nuclear power generation will increase if information on the necessity and safety of medical radiation is provided as well. Both male and female students perceived that medical radiation is the most necessary (p<0.001), medical radiation is the safest (p<0.001), and nuclear power generation is the least safe (p<0.013). Moreover, the correlation between medical radiation and nuclear power generation was the highest. Third, there is a need for different lectures between classes, since the patterns of perception vary according to the field of radiation use among elementary, middle, and high school students. Elementary school students had high interest in education on nuclear power generation (p<0.005), perceived that irradiated food is safe (p<0.001), and had the most positive attitude toward consuming irradiated food (p<0.001). Middle school students had high interest in education on nuclear power generation (p<0.018), perceived that nuclear power generation (p<0.001) and medical radiation (p<0.002) are safe, and had the most positive attitude toward using radiation for treatment (p<0.001). High school students had the highest level of objective knowledge on nuclear power generation (p<0.001) and medical radiation (p<0.001), and perceived that medical radiation is the most necessary (p<0.017); however, they perceived that nuclear power generation is the least safe (p<0.001). Attitudes toward irradiated food intake (p<0.001) and approving construction of a nuclear power plant in their neighborhood (p<0.001) were both low. Fourth, it is necessary to provide educational programs to change perceptions and improve attitudes rather than providing education focused on objective knowledge. There was no correlation between objective knowledge and necessity of irradiated food, objective knowledge and safety and interest in education on nuclear power generation, and objective knowledge and interest in education and information acquirement regarding medical radiation. In particular, high school students had the highest level of objective knowledge and yet had the least positive attitudes toward approving construction of nuclear power plants in their neighborhood and intake of irradiated food. Therefore, to increase the social acceptability of using nuclear energy and radiation in Korea, it is desirable to provide strategic educational programs to improve perceptions, knowledge, and attitudes regarding the necessity and safety of their use.