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Study on the Salt Tolerance of Rice and Other Crops in Reclaimed Soil Areas. -6. On the Effects of Increased N. P. K. Applications for Rice Plant in Reclaimed Salty Areas (간척지(干拓地)에서 수도(水稻) 및 기타작물(其他作物)의 내염성(耐鹽性)에 관(關)한 연구(硏究) -6. 염분간척지(鹽分干拓地)에서 수도(水稻)에 대한 N, P, K,의 증비효과에 관(關)하여)

  • Im, H.B.
    • Korean Journal of Soil Science and Fertilizer
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    • v.3 no.1
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    • pp.35-41
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    • 1970
  • The experiment was conducted at the salt concentration of 0.5% and 1% end of April, respectively, in low and high-salty and the non-salty areas of silt loam with the Nongkwang, rice variety. The factorial design with confounding blocks of 3 levels each of 10, 15 and 20 kg of N, 8, 12 and 16kg of phosphate and potash, respectively, per 10a was applied. 1. N applications increased by 1.5 and 2 times with the fixed amount of $P_2O_5$ and $K_2O$ (8kg/10a each) increased the proportion absorbed to the applications of N in both non salty and low-salty areas. It was observed that the absorption of Ca and Si was inhibited by either an increased treatment of N alone or combination with the other nutrients in the salty area. 2. In the non-salty area, an increased applications of standard amount of N, $P_2O_5$ and $K_2O$ respectively did not increased the yields. Doubling the application of $K_2O$ resulted in a decreased yield. 3. Applications of additional of 1.5 and 2 times the 10 kg of N per 10a increased the rice yields 12% and 21% respectively, in the low-salty area. An increased application of $P_2O_5$ and $K_2O$ failed to bring about an increased yield. 4. Increasing the application of N gave a significant increased in the yield of rice grain and 1.5 times of N applications were seemed profitable on the high-salty area. Although an increased applications $P_2O_5$ and $K_2O$ seemed to increase the yields of grain, no significant increase was observed. 5. An increased application of N increased the number of panicles up to 1.5 times the standard amount in the non-salty area, but no further increase resulted by doubling the application. The number of panicles was increased in proportion to the increased application of N in both low and high-salty areas. An increased application of $P_2O_5$ increase the number of panicles per unit area in each experimental plot while that of $K_2O$ had no effect but rather decreased the number. 6. The effect of an increased application of N decreased the weight of panicle in the non-salty area, but when the application was increased to 1.5 times or more an increased weight of panicle resulted in both salty areas. Doubling the application had approximately the same effect as 1.5 times the application. Increasing the applications of $P_2O_5$ and $K_2O$ had no effect on the panicle weight in the experimental plots. Increasing the applications of N, $P_2O_5$ and $K_2O$ did not effect the weight of 1,000 grains produced in the non-salty and salty areas. Increasing the application of N decreased the number of grains per panicle in the non-salty area but increased the number of grains per panicle in either salty areas. 7. The ratio of matured grains was highest in the low-salty area and the lowest in the high-salty area. An increased N applications decreased the ratio of matured grains in the non-salty area. No effect was observed in both low and high-salty areas. Increased the $P_2O_5$ and $K_2O$ application showed no effect on the ratio of matured grains in the experimental plots. 8. Increased applications of N, $P_2O_5$ and $K_2O$ was observed not to change the percentage of milling recovery in any experimental plots. Broken rice was increased equally by an increased application of N in the non-salty and salty areas but more remarkably so in the former. 9. Increased applications of N increased the straw production equally in the non-salty, low and high-salty areas. However, no increased production was observed from heavier applications of $P_2O_5$ and $K_2O$. Additional N applications reduced the rate of rough grain weight v.s. straw weight in the non-salty area but increased the ratios in both low and high-salty areas. Additional $P_2O_5$ and $K_2O$ had no effect with the ratio.

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The Acceptance Testing of 5 Mega Pixels Primary Electronic Display Devices and the Study of Quality Control Guideline Suitable for Domestic Circumstance (5 Mega 화소 진단용 전자표시장치 인수검사 및 국내 실정에 적합한 정도관리 가이드라인 연구)

  • Jung, Hai-Jo;Kim, Hee-Joung;Kim, Sung-Kyu
    • Progress in Medical Physics
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    • v.18 no.2
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    • pp.98-106
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    • 2007
  • In June 2005, Yonsei University Medical Center, Severance Hospital upgraded a full-PACS system by adding twenty (5 mega pixels) Totoku ME511L flat panel LCD display devices for diagnostic interpretation purposes. Here we report upon the quantitative (or visual) acceptance testing of the twenty Totoku ME511L display devices for reflection, luminance response, luminance spatial dependency, resolution, noise, veiling glare, and display chromaticity based on AAPM TG 18 report. The tools used in the tests included a telescopic photometer, which was used as a colorimeter, illuminance meter, light sources for reflection assessment, light-blocking devices, and digital TG18 test patterns. For selected 8 flat panel displays, mean diffuse reflection coefficient ($R_d$) was $0.019{\pm}0.02sr^{-1}$. In the luminance response test, luminance ratio (LR), maximum luminance difference ($L_{max}$), and deviation of contrast response were $550{\pm}100,\;2.0{\pm}1.9%\;and\;5.8{\pm}1.8%$, respectively. In the luminance uniformity test, maximum luminance deviation was $14.3{\pm}5.5%$ for the 10% luminance of the TG18-UNL10 test pattern. In the resolution test with luminance measurement method, percent luminance (${\Dalta}L$) at the center was $0.94{\pm}0.64%$. In all cases of noise testing, rectangular target In every square in the three quadrants was visible and all 15 targets except the smallest one in the every corner pattern and the center pattern. The glare ratio (GR) was $12,346{\pm}1,995$. The color uniformity, (u',v'), was $0.0025{\pm}0.0008$. Also, the research results of qualify control guideline of primary disply devices suitable for domestic circumstance are presented All test results are in-line with the criteria recommended by AAPM TG18 report and are thus fully acceptable for diagnostic image interpretation. As a result, the acceptance testing schedule described provides not only an acceptance standard but also guidelines for quality control, optimized viewing conditions, and a means for determining the upgrading time of LCD display devices for diagnostic interpretation.

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The Frequency of Chromosomal Aberrations of Peripheral Lymphocytes according to Radiation Dose and Dose Rate (선량 및 선량률 변화에 따른 말초혈액 임파구의 염색체 이상의 빈도)

  • Jeong Tae Sik;Baek Heum Man;Shin Byung Chul;Moon Chang Woo;Kim Mi Hyang;Lee Yong Hwan;Yum Ha Yong
    • Radiation Oncology Journal
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    • v.18 no.2
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    • pp.138-149
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    • 2000
  • Purpose : It was studied that the relationship between radiation dose, dose rate and the frequency of chromosomal aberrations in peripheral lymphocytes. Methods and Materials : Peripheral lymphocytes were irradiated in vitro with 6 MeV X-ray at dose ranges from 50 cGy to 800 cGy. The variations of the frequency of chromosomal aberrations were observed according to different radiation dose rate from 20 cGy/min to 400 cGy/min at constant total dose of 400 cGy which it was considered as factor to correct biological radiation dose measurement. Results : The yields of lymphocytes with chromosomal aberrations (dicentric chromosome, ring chromosome, acentric fragment pairs) are 0% at 50 cGy, 9% at 100 cGy, 20% at 200 cGy, 27% at 300 cGy, 55% at 400 cGy, 88% at 600 cGy, and 100% at 800 cGy. The value of Ydr is 0.000 at 50 cGy, 0.093 at 100 cGy, 0.200 at 200 cGy, 0.354 at 300 cGy, 0.612 at 400 cGy, 2.040 at 600 cGy, and 2.846 at 800 cGy. The relationship between radiation (D) and the frequency of dicentrlc chromosomes and ring Chromosomes (Ydr) can be expressed as Ydr=0.188${\times}$10$^{-2}$ D/Gy+0.422${\times}$10$^{-4}$/Gy$^{2}$${\times}$D$^{2}$ The Value of Qdr is 0.000 at 50 cGy, 1.000 at 100 cGy, 1.000 at 200 cGy, 1.333 at 300 cGy, 1.118 at 400 cGy, 2.318 at 600 cGy, and 2.846 at 800 cGy. When 400 cGy is irradiated with different dose rate each of 20, 40, 60, 80, 100, 160, 240, 320, and 400 cGy/min, Ydr is each of 0.982, 0.837, 0.860, 0.732, 0.763, 0.966, 0.909, 1.006, and 0.806, and Qdr is each of 1.839, 1.555, 1.654, 1.333, 1.381, 1.750, 1.6000, 1.710, and 1.318. Conclusion : There are not the significant variations of Ydr and Qdr values according to different dose rate. And so radiation damage is influenced by total exposed radiation doses and is influenced least of all by different dose rate when it is acute single exposure.

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NIRS AS AN ESSENTIAL TOOL IN FOOD SAFETY PROGRAMS: FEED INGREDIENTS PREDICTION H COMMERCIAL COMPOUND FEEDING STUFFS

  • Varo, Ana-Garrido;MariaDoloresPerezMarin;Cabrera, Augusto-Gomez;JoseEmilioGuerrero Ginel;FelixdePaz;NatividadDelgado
    • Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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    • 2001.06a
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    • pp.1153-1153
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    • 2001
  • Directive 79/373/EEC on the marketing of compound feeding stuffs, provided far a flexible declaration arrangement confined to the indication of the feed materials without stating their quantity and the possibility was retained to declare categories of feed materials instead of declaring the feed materials themselves. However, the BSE (Bovine Spongiform Encephalopathy) and the dioxin crisis have demonstrated the inadequacy of the current provisions and the need of detailed qualitative and quantitative information. On 10 January 2000 the Commission submitted to the Council a proposal for a Directive related to the marketing of compound feeding stuffs and the Council adopted a Common Position (EC N$^{\circ}$/2001) published at the Official Journal of the European Communities of 2. 2. 2001. According to the EC (EC N$^{\circ}$ 6/2001) the feeds material contained in compound feeding stufs intended for animals other than pets must be declared according to their percentage by weight, by descending order of weight and within the following brackets (I :< 30%; II :> 15 to 30%; III :> 5 to 15%; IV : 2% to 5%; V: < 2%). For practical reasons, it shall be allowed that the declarations of feed materials included in the compound feeding stuffs are provided on an ad hoc label or accompanying document. However, documents alone will not be sufficient to restore public confidence on the animal feed industry. The objective of the present work is to obtain calibration equations fur the instanteneous and simultaneous prediction of the chemical composition and the percentage of ingredients of unground compound feeding stuffs. A total of 287 samples of unground compound feeds marketed in Spain were scanned in a FOSS-NIR Systems 6500 monochromator using a rectangular cup with a quartz window (16 $\times$ 3.5 cm). Calibration equations were obtained for the prediction of moisture ($R^2$= 0.84, SECV = 0.54), crude protein ($R^2$= 0.96, SECV = 0.75), fat ($R^2$= 0.86, SECV = 0.54), crude fiber ($R^2$= 0.97, SECV = 0.63) and ashes ($R^2$= 0.86, SECV = 0.83). The sane set of spectroscopic data was used to predict the ingredient composition of the compound feeds. The preliminary results show that NIRS has an excellent ability ($r^2$$\geq$ 0, 9; RPD $\geq$ 3) for the prediction of the percentage of inclusion of alfalfa, sunflower meal, gluten meal, sugar beet pulp, palm meal, poultry meal, total meat meal (meat and bone meal and poultry meal) and whey. Other equations with a good predictive performance ($R^2$$\geq$0, 7; 2$\leq$RPD$\leq$3) were the obtained for the prediction of soya bean meal, corn, molasses, animal fat and lupin meal. The equations obtained for the prediction of other constituents (barley, bran, rice, manioc, meat and bone meal, fish meal, calcium carbonate, ammonium clorure and salt have an accuracy enough to fulfill the requirements layed down by the Common Position (EC Nº 6/2001). NIRS technology should be considered as an essential tool in food Safety Programs.

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Properties of Indigenous Korean Paper(Hanji) - Classification of Oebal(single frame)Papermaking Methods - (토착한지의 특성 - 외발 초지법 분류를 중심으로 -)

  • Cheon, Cheol;Kim, Seong-Ju;Jin, Young-Mun
    • Journal of the Korean Wood Science and Technology
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    • v.27 no.1
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    • pp.88-104
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    • 1999
  • This study was carried out to classify the Hanjis into three groups that were indigenous Hanji, traditional Hanji, and improved Hanji handmade by paper making method according to the physical properties of each paper sheet such as tensile, bursting and tearing strength, folding endurance and fiber orientation in each layer. The results obtained were summarized as follows: 1. The multi-layered Hanjis made by "Oebal" Hanji making method in different direction of fiber orientation have good properties in tearing resistance. 2. The multi-layered Hanji in different direction of fiber orientation has good properties in the tearing resistance, but the burst index and the breaking length results were lower than the single layered Hanjis. 3. The different fiber orientation and multi-layered method didn't increase, the three indexes(burst index, tear index, breaking length). Only, the different direction of fiber orientation decreased the difference of width and length strength (tensile, tear) of the Hanji. 4. "Dochim"(Korean finishing touch process for indigenous Hanji by fulling round sticks) greatly increase folding endurance(double folds, not $log_{10}$) and good effect to tensile strength and burst strength. 5. The today's Oebal Hanji were the maximum of 2 layers and the indigenous Oebal Hanji were 16 layers the maximum. In addition, average of the indigenous Oebal Hanji was 4 layers(all 4-layer Hanji were the different fiber orientation of each layer). 6, The indigenous Hanji(multi-layered, and different fiber orientation) was good condition with "Dochim". Dochim increased tensile strength and burst strength of the indigenous Hanji. So the three-strength indexes were similar level("--"). 7. When the number of layer which were same fiber orientation increase, the increased Hanji became similar strength pattern("V", breaking length and burst index was higher than tear index) with "Ssangbal" Hanji. 8. The single layered papers that made by "Oebal" Hanji making method were similar strength pattern with Ssangbal Hanji. 9. There was no way to find the width and length direction of multi-layered Hanji by comparison between the difference of tensile strength and the difference of tearing resistance. 10. The compared pattern of tensile strength and tearing resistance of indigenous Oebal Hanji was different from today's Oebal Hanji. Especially, the tearing resistance of all indigenous Oebal Hanji(16 samples) was stronger on width of tearing resistance. And in the half of indigenous Oebal Hanji samples, the width of tensile strength and tearing resistance was stronger than length strength (Indigenous Oebal: '$\ulcorner\lrcorner$' 50%, '$\bigcup$' 50% $\leftrightarrow$ Today's Oebal: '$\ulcorner\lrcorner$' 12%, '$\bigcup$'6%, '$\llcorner\urcorner$'17%, '$\bigcap$'65%). In 65% today's Oebal, the length direction of tensile strength and tearing resistance was stronger than the width direction.

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A Study on Fractionation and Characterization of Water-Soluble Natural Fe-Chelates From Garbage Compost and Activated Sewage Sludge (활성오니(活性汚泥) 및 진개퇴비중(塵芥堆肥中) 수용성(水溶性) 철(鐵) 킬레이트의 분리(分離)와 특성(特性)에 관(關)한 연구(硏究))

  • Park, Nae-Joung;Lindsay, W.L.
    • Applied Biological Chemistry
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    • v.18 no.4
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    • pp.194-202
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    • 1975
  • This study was conducted to study the properties of the water-soluble natural chelating agents from garbage compost and activated sewage sludge responsible for Fe chelation, which is closely associated with the effectiveness in correcting iron chlorosis in plant. The water-soluble fraction of these materials was fractionated by menas of Sephadex gel filtration and the fractions of Fe chehates were traced by radioactive $^{59}Fe$. The fractions were examined by ultraviolet and infrared. spectroscopy and stability constants for Fe. The water-soluble fraction from garbage compost was separated by Sephadex G-25 into approximately four fractions. Most of the added $^{59}Fe$ was associated with fraction I, which appeared at the void volume. Further fractionation by Sephadex G-50 indicated that the molecular weight of water-soluble chelating agents is in the approximate range of 5000 to 10,000. The water-soluble fraction from activated sewage sludge gave six fractions by Sephadex G-25. Most of the added $^{59}Fe$ was found in the fraction I,II, and III, The molecular weights of most chelating agents associated with $^{59}Fe$ appeared to be less than 5,000 and those of fraction I that appeared at the void volume was in the range of 5,000 to 1,000. Discrepancy between radio activity count and UV absorption indicated the heterogeneity of the fractions obtained by Sephadex gel filtration. Ultraviolet absorption spectra of all fractions separated by Sephadex G-25 and containing chelating agents showed no differences. Fraction IV and V of sewage extract showed absorption maxima and shifting similar to nucleic acid components suggesting the presence of decomposition products of nucleic acid. Similarity fraction VI contained phenolic type amino acid groups. Fraction I of compost extract contained most of the added $^{59}Fe$ and showed weak but extra definite absorption in the 1230, and $1270cm^{-1}$ region, suggesting that extra oxygen groups in polyphenolic structure were probably involved in Fe chelation. In sewage extract, fraction I,II, and III in which most of the $^{59}Fe$ was found, showed strong definite polypeptide absorption in the region of $1540cm^{-1}$ due to NH deformation and C-N stretching of amide groups in the peptidebond. These extra functional groups in fraction I, II, and III appeared to be associated with Fe chelation. The other fractions, not associated with $^{59}Fe$, still have carboxyl and hydroxyl groups, suggesting that these functional groups in these water extracts may not independently form the Fe chelates. Precipitation of ferric hydroxide precluded measuring the stability constants for Fe-chelates. However, the formation constants for Zn chelates as log K values for compost extract and sewage extract at pH 4.0 from which the strength of chelation with Fe could be presumed, were 8.23, and 9.75, respectively, indicating strong complexation with metals. The chelating capacity of compost extract containing 6.5 g organic matter per liter was 0.82 mM, and that of sewage extract containing 5.3 g per liter was 0. 64 mM.

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Breakthrough Urinary Tract Infection: A Clinical Study of Experience of a Single Center (예방적 항생제 사용중에 발생한 요로감염: 단일 병원에서 경험한 임상연구)

  • Bae, Sang-In;Cheon, Chong-Kun;Kim, Su-Young
    • Childhood Kidney Diseases
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    • v.14 no.2
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    • pp.203-209
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    • 2010
  • Purpose : It has been a common medical practice to use prophylactic antibiotics to prevent recurrent urinary tract infections (UTI) in high risk situations such as urinary tract obstruction, vesicoureteral reflux, neurogenic bladder, or urinary stones. But sometimes, we meet difficult situation of breakthrough infections (BI) which might cause new or progressive renal scarring. The clinical characteristics of children contracting breakthrough UTI experienced in a single center were studied. Methods : The study was done retrospectively through medical records of 150 pediatric patients who had been cared in pediatric and urologic clinics of Pusan National University Hospital from Jan. 2001 till June 2006 and had prophylactic antibiotics to prevent recurrent UTI. Results : The starting age of prophylactic antibiotics of 150 patient was 1-76 months, and median age was 5 months. The BI developed 61 times in 43 patients (28.7%), 1.5 times per 100 patient-months. The BI occurred more frequently in patients with higher grade of VUR, and in the cases with abnormal DMSA scan. Co-trimoxazole was more effective than 2nd and 3rd generation cephalosporins to prevent UTI. The distribution of causative organisms was more diverse than usual UTI. The causative organisms were sensitive to the antibiotics used for prophylaxis in 29.5%, and resistant in 59.1%. After experience of BI, 40 percents of patients went to the surgical treatment including endoscopic injection of Deflux, 35% to new antibiotics for prophylaxis, 26% remain on the same antibiotics as the previous one. Conclusion : Based on our study results, preexisting renal scar might be one of the factors which should be considered in favor of early surgical interventions of VUR. Poor compliance and wrong selection of antibiotics such as cephalosporins are important underlying causes of breakthrough UTIs.

Performance Characteristics of Agitated Bed Manure Composting and Ammonia Removal from Composting Using Sawdust Biofiltration System (교반식 축분 퇴비화 및 톱밥 탈취처리 시스템의 퇴비화 암모니아 제거 성능)

  • Hong, J.H.;Park, K.J.
    • Journal of Animal Environmental Science
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    • v.13 no.1
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    • pp.13-20
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    • 2007
  • Sawdust biofiltration is an emerging bio-technology for control of ammonia emissions including compost odors from composting of biological wastes. Although sawdust is widely used as a medium for bulking agent in composting system and for microbial attachment in biofiltration systems, the performance of agitated bed composting and sawdust biofiltration are not well established. A pilot-scale composting of hog manure amended with sawdust and sawdust biofiltration systems for practical operation were investigated using aerated and agitated rectangular reactor with compost turner and sawdust biofilter operated under controlled conditions, each with a working capacity of approximately $40m^3\;and\;4.5m^3$ respectively. These were used to investigate the effect of compost temperature, seed germination rate and the C/N ratio of the compost on ammonia emissions, compost maturity and sawdust biofiltration performance. Temperature profiles showed that the material in three runs had been reached to temperature of 55 to $65^{\circ}C$ and above. The ammonia concentration in the exhaust gas of the sawdust biofilter media was below the maximum average value as 45 ppm. Seed germination rate levels of final compost was maintained from 70 to 93% and EC values of the finished compost varied between 2.8 and 4.8 ds/m, providing adequate conditions for plant growth.

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Study of Oil Palm Biomass Resources (Part 5) - Torrefaction of Pellets Made from Oil Palm Biomass - (오일팜 바이오매스의 자원화 연구 V - 오일팜 바이오매스 펠릿의 반탄화 연구 -)

  • Lee, Ji-Young;Kim, Chul-Hwan;Sung, Yong Joo;Nam, Hye-Gyeong;Park, Hyeong-Hun;Kwon, Sol;Park, Dong-Hun;Joo, Su-Yeon;Yim, Hyun-Tek;Lee, Min-Seok;Kim, Se-Bin
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.48 no.2
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    • pp.34-45
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    • 2016
  • Global warming and climate change have been caused by combustion of fossil fuels. The greenhouse gases contributed to the rise of temperature between $0.6^{\circ}C$ and $0.9^{\circ}C$ over the past century. Presently, fossil fuels account for about 88% of the commercial energy sources used. In developing countries, fossil fuels are a very attractive energy source because they are available and relatively inexpensive. The environmental problems with fossil fuels have been aggravating stress from already existing factors including acid deposition, urban air pollution, and climate change. In order to control greenhouse gas emissions, particularly CO2, fossil fuels must be replaced by eco-friendly fuels such as biomass. The use of renewable energy sources is becoming increasingly necessary. The biomass resources are the most common form of renewable energy. The conversion of biomass into energy can be achieved in a number of ways. The most common form of converted biomass is pellet fuels as biofuels made from compressed organic matter or biomass. Pellets from lignocellulosic biomass has compared to conventional fuels with a relatively low bulk and energy density and a low degree of homogeneity. Thermal pretreatment technology like torrefaction is applied to improve fuel efficiency of lignocellulosic biomass, i.e., less moisture and oxygen in the product, preferrable grinding properties, storage properties, etc.. During torrefacton, lignocelluosic biomass such as palm kernell shell (PKS) and empty fruit bunch (EFB) was roasted under an oxygen-depleted enviroment at temperature between 200 and $300^{\circ}C$. Low degree of thermal treatment led to the removal of moisture and low molecular volatile matters with low O/C and H/C elemental ratios. The mechanical characteristics of torrefied biomass have also been altered to a brittle and partly hydrophobic materials. Unfortunately, it was much harder to form pellets from torrefied PKS and EFB due to thermal degradation of lignin as a natural binder during torrefaction compared to non-torrefied ones. For easy pelletization of biomass with torrefaction, pellets from PKS and EFB were manufactured before torrefaction, and thereafter they were torrefied at different temperature. Even after torrefaction of pellets from PKS and EFB, their appearance was well preserved with better fuel efficiency than non-torrefied ones. The physical properties of the torrefied pellets largely depended on the torrefaction condition such as reaction time and reaction temperature. Temperature over $250^{\circ}C$ during torrefaction gave a significant impact on the fuel properties of the pellets. In particular, torrefied EFB pellets displayed much faster development of the fuel properties than did torrefied PKS pellets. During torrefaction, extensive carbonization with the increase of fixed carbons, the behavior of thermal degradation of torrefied biomass became significantly different according to the increase of torrefaction temperature. In conclusion, pelletization of PKS and EFB before torrefaction made it much easier to proceed with torrefaction of pellets from PKS and EFB, leading to excellent eco-friendly fuels.

Determination of Electron Beam Output Factors of Individual Applicator for ML-15MDX Linear Accelerator (선형가속기 ML-15MDX의 각 Applicator에 대한 전자선 출력선량 계수 결정)

  • Park, Tae-Jin;Kim, Ok-Bae
    • Progress in Medical Physics
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    • v.5 no.1
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    • pp.87-99
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    • 1994
  • Purpose : The determination of electron beam output factor was investigated from individual applicator for various energy of ML-15MDX linear accelerator. The output factor of electron beam was extended from square to rectangular field in individual applicator size through with a least-square fit to a polynomial expression. Materials : In this experiments. the measurement of output was obtained from 2${\times}$cm$^2$ to 20${\times}$20cm$^2$ of field size in different applicator size for 4 to 15 MaV electron beam energy. The output factor was defined as the ratio of maximum dose output on the central axis of the field of individual applicator size to that of a given field size. Applicator factors were derived from comparing with the output dose of reference field size 10${\times}$10cm$^2$. The thickness of block was specially designed as 10mm in thickness of Lipowitz metal for field shaping in all electron energy. Two types of output curves are included as output factors versus side of square fields and that of variable side length for X and Y in one-dimensional to compare the expected values to that of experiments. Results : Expected output factors of rectangular which was derived from that of square fields in individual applicator size from 2${\times}$2cm$^2$ to 20${\times}$20cm$^2$ in different electron energy was very closed to that of experimental measurements within 2% uncertainty. However 1D method showed a 3% discrepancy in small rectangular field for low energy electron beam. Conclusion : Emperical non-linear polynomial regressions of square root and 1D method were performed to determin the output factor in various field size and electron energy. The expected output of electron beam of square root method for square field and 1D method for rectangular field were very closed to that of measurement in all selected electron beam energy.

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