• 한국석유지질학회:학술대회논문집
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• autumn
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• pp.28-46
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• 2001

Natural gas is a mixture of hydrocarbon gases and impurities such as nitrogen, hydrogen sulfide, and carbon dioxide and a clean energy producing no pollution materials for combustion. Currently, the demand of the natural gas is rapidly increasing due to worldwide environmental problems. According to Hubbert's study in the past, the natural gas was predicted as rapidly depleted resources, and then the results led to high gas price and limitation of usage during 1980s. Afterward, the study of natural gas resources based on geology identified the additional natural gas resources that were not considered in Hubbert's study. They are unconventional gas, additional resources in the existed reservoirs, and natural gas in deep subsurface areas. Such additional resouces made the future of natural gas bright and pormised low and stable gas price in the future. Deep natural gas is defined as the gas existing at or below 15,000ft$(4,752{\cal}m)$ in depth from the surface. According to the study from the U.S. Geological Survey(USGS) in 1995, 1,412 TCF of technically recoverable natural gas was remained to be discovered or developed in the onshore of United States. A significant part of that resource base, 114 TCF, exists at deep sedimentary basins, and it shows wide distribution with various geological environments. In 1995, the deep gas contributed to $6.7\% of total supply amount of natural gas in the United States and is expected to be $18.7\% by 201.5. However, the development of the deep gas is a high risky business due to expensive investment and high portion of dry holes, although it is developed. Thus, for developing the deep gas economically, it is necessary to overcome many technical challenges. In this paper, for increasing success rate of the deep gas, 1) geologic and compositional characteristics, and production cost have been analyzed according to depth, 2) technical problems related to deep gas production have been summarized, and 3) finally future study areas for increasing application of the deep gas have been suggested. For reference, this paper was written based on the study results from USGS and Gas Research Institute(GRI), for the United States is doing the most active R&D in the deep gas area, and thus, has many reliable data.

• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.517-525
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• 2013

Time-series data of Normal Difference Vegetation Index (NDVI) obtained by the Moderate-resolution Imaging Spectroradiometer(MODIS) satellite imagery gives a waveform that reveals the characteristics of the phenology. The waveform can be decomposed into harmonics of various periods by the Fourier transformation. The resulting $n^{th}$ harmonics represent the amount of NDVI change in a period of a year divided by n. The values of each harmonics or their relative relation have been used to classify the vegetation species and to build a vegetation map. Here, we propose a method to estimate the annual amount of carbon absorbed on the forest from the $1^{st}$ harmonic NDVI value. The $1^{st}$ harmonic value represents the amount of growth of the leaves. By the allometric equation of trees, the growth of leaves can be considered to be proportional to the total amount of carbon absorption. We compared the $1^{st}$ harmonic NDVI values of the 6220 sample points with the reference data of the carbon absorption obtained by the field survey in the forest of South Korea. The $1^{st}$ harmonic values were roughly proportional to the amount of carbon absorption irrespective of the species and ages of the vegetation. The resulting proportionality constant between the carbon absorption and the $1^{st}$ harmonic value was 236 tCO2/5.29ha/year. The total amount of carbon dioxide absorption in the forest of South Korea over the last ten years has been estimated to be about 56 million ton, and this coincides with the previous reports obtained by other methods. Considering that the amount of the carbon absorption becomes a kind of currency like carbon credit, our method is very useful due to its generality.

• Radiation Oncology Journal
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• v.28 no.1
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• pp.50-56
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• 2010

Purpose: We report the results of an external audit on the absorbed dose of radiotherapy beams independently performed by third parties. For this effort, we developed a method to measure the absorbed dose to water in an easy and convenient setup of solid water phantom. Materials and Methods: In 2008, 12 radiotherapy centers voluntarily participated in the external auditing program and 47 beams of X-ray and electron were independently calibrated by the third party’s American Association of Physicists in Medicine (AAPM) task group (TG)-51 protocol. Even though the AAPM TG-51 protocol recommended the use of water, water as a phantom has a few disadvantages, especially in a busy clinic. Instead, we used solid water phantom due to its reproducibility and convenience in terms of setup and transport. Dose conversion factors between solid water and water were determined for photon and electron beams of various energies by using a scaling method and experimental measurements. Results: Most of the beams (74%) were within ${\pm}2%$ of the deviation from the third party's protocol. However, two of 20 X-ray beams and three of 27 electron beams were out of the tolerance (${\pm}3%$), including two beams with a >10% deviation. X-ray beams of higher than 6 MV had no conversion factors, while a 6 MV absorbed dose to a solid water phantom was 0.4% less than the dose to water. The electron dose conversion factors between the solid water phantom and water were determined: The higher the electron energy, the less is the conversion factor. The total uncertainty of the TG-51 protocol measurement using a solid water phantom was determined to be ${\pm}1.5%$. Conclusion: The developed method was successfully applied for the external auditing program, which could be evolved into a credential program of multi-institutional clinical trials. This dosimetry saved time for measuring doses as well as decreased the uncertainty of measurement possibly resulting from the reference setup in water.

• Korean Journal of Community Nutrition
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• v.15 no.3
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• pp.308-328
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• 2010

As the older adult period $({\geq}65y)$ is increasing, it is needed to investigate the trend of aging-dependent anthropomeric index and nutrient intake, and establish the more specific dietary guide for the different stages of aging period. To find the difference in nutrient intake among the Koreans aged 50-64, 65-74 and 75 years and older, and also any characteristics of dwellers in longevity area, we recruited 1,083 subjects (385 male and 698 female) aged 50-95 years (mean age, 71.3 yrs) living in Kugoksoondam area (Kurye, Goksung, Soonchang and Damyang counties), known as a longevity-belt region in Jeonlaprovince, Korea. We measured some anthropometric index and collected 2 day-dietary record. Nutrient intakes were analyzed by using DW24 program. The mean height and weight of subjects aged 75 years and older were lower than Korean national reference. BMI and obesity $({\geq}25kg/m^2)$ prevalence were significantly decreasing with aging. Underweight $(BMI<18.5kg/m^2)$ prevalence was also increasing with aging, especially in males, and it was slightly higher than national average, but similar to that in some other rural area. Obesity prevalence of male subjects was lower compared to national prevalence, but abdominal obesity prevalence $(waist{\geq}80cm)$ was very high in females (about 89%). In both genders, the average proportional contribution of carbohydrate, protein and fat to energy intake was not different between 65-74 years and 75 years and older. On overall, nutrient intake and quality of diet of females were inferior to those of males so that many of females aged 75 years and older assumed to be at risk of malnourished status. Fiber, folate and vitamin E intakes were substantially higher compared to those in 2007 KNHNES and other some studies in rural area. While almost nutrient %EAR was significantly decreased with aging in females, there was no significant difference in %EAR for protein, vitamin A, $B_1$, $B_6$, $B_{12}$, niacin, Ca and Zn between 65-74 years and 75 years and older in males. Vitamin $B_2$ for male aged 50-64 years, vitamin $B_2$ and Ca for male aged 65 years and over and female aged 50-74 years, and vitamin $B_2$, vitamin C, Ca and folate intake for female aged 75 years and older were assessed to be at risk to undernutrition based on the prevalence of intake below EAR. MAR of 13 nutrients and the number of nutrients consuming below EAR were significantly decreasing with aging in both genders, however, the number of nutrients of INQ < 1 and the average mini-nutritional assessment score were not significantly different between 65-74 years and 75 years and older. Taken together, decreasing tendency of nutrients intake and the quality of diet with aging was more evident in females than in males, and it is unique that our subjects consumed substantially higher fiber, folate and vitamin E compared to not only urban but also some other rural areas.

• Journal of Nutrition and Health
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• v.35 no.1
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• pp.37-44
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• 2002

The purpose of this study was to provide a reference range for plasma homocysteine and to explore the relation between plasma homocysteine and nutritional indexes in a Korean college women. Thirty women were selected from college students in Seoul area With mean age of 22.4y. Dietary intakes of Vitamins B$_{6}$, B$_{12}$, folate were estimated from a 3 day food diary method and plasma homocysteine concentration was mearsured as well as the levels of blood vitamins. The results obtained are as follows. Mean daily intake of energy, vitamin B$_{6}$, B$_{12}$, and folate were 1731.9kcal, 0.9mg, 2.2mg and 139.8$\mu\textrm{g}$ respectively. Mean plasma homocysteine concentration was 12.4$\mu$mol/l with a range between 6.7 and 17.8$\mu$mol/l and the mean concentrations of plasma vitamin B$_{6}$(PLP), serum vitamin $_{12}$, Serum folate and RBC folate were 77.5nmol/l, 267.4pmol/l, 17.1 nmol/l and 736.5nmol/l arid 736.5nmol/l respectively. we found a negative correlation between plasma homocysteine concentration and dietary vitamins, and blood levels of vitamin although it was not significant.

• Journal of Nutrition and Health
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• v.40 no.8
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• pp.719-727
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• 2007

To elucidate the relationship among the levels of nutrients intake, bone mineral density(BMD) and the urinary biochemical markers of bone metabolism, this survey is conducted with 225 postmenopausal women over 50 years of age. The urinary biochemical markers including deoxypyridinoline(DPD) and Ca excretion were measured. Bone mineral densities of lumbar spine(L2-L4), femoral neck, ward's triangle and trochanter were measured with dual-energy X-ray absorptiometry and the nutrient intake data obtained by 24 hr recall method. Mean age of all subjects was 64.8 years old, and the BMDs of the subjects were $0.86g/cm^2$(lumbar spine), $0.60g/cm^2$(femoral neck), $0.49g/cm^2$(trochanter), and $0.41g/cm^2$(ward's triangle). The results were compared among 3 groups with different nutrient intake levels classified by the percentage of Dietary Reference Intakes(DRIs) for Koreans as follows: low < 75% DRIs, 75% DRI $\leq$ adequate < 125% DRIs, high $\geq$ 125% DRIs. Bone mineral density of adequate protein intake group was significantly higher than those of low and high protein intake groups(p<0.05). Urinary DPD excretion was lowest in protein and calcium adequate intake groups(p<0.05, p<0.05), respectively. In relation to urinary Ca excretion, it is revealed to be considerably lower in the groups taking protein and vitamin C adequate intake(p<0.05, p<0.05). The percent DRI of protein and calcium were positively correlated with the BMD of the femoral neck after adjusted age(p<0.05, p<0.05). These results showed that there are probably some relationships between nutrient intake levels and urinary biochemical markers. For postmenopausal women with adequate nutrition expecially protein, calcium and vitamin C, has an important role to postpone bone resorption and to prevent the decrease of bone density.

• Progress in Medical Physics
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• v.10 no.1
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• pp.17-22
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• 1999

INJ-I, INJ-E, PFN, BMI, and PRF were selected among the various factors which constitute a digital linear accelerator to find effects on the dose distribution by changing current and voltage within the permitted scale which Mevatron automatically maintained. We measured the absorbed dose using an ion chamber, analyzed the waveform of beam output using an oscilloscope, and measured symmetry and flatness using a dosimetry system. An RFA plus (Scanditronix, Sweden) device was used as a dosimetry system. Then an 0.6cc ion chamber (PR06C, USA), an electrometer (Capintec192, USA), and an oscilloscope (Tektronix, USA) were employed to measure the changes on the dose distribution characteristics by changing the beam-tuning parameters. When the currents and the voltages of INJ-I, INJ-E, PFN, BMI, and PRF were modified, we were able to see the notable change on the dose rate by examining the change of the output pulse using the oscilloscope and by measuring them using the ion chamber. However, the results of energy and flatness graph from RF A plus were almost identical. The factors had fine differences: INJ-I, INJ-E, PFN, BMI, and PRF had 0.01∼0.02% differences in D10/D20, 0.1∼0.2 % differences in symmetry, and 0.1∼0.4% differences in flatness. Since Mevatron controlled itself automatically to keep the reference value of the factor, it was not able to see large differences in the dose distribution. There were fine differences on the dose rate distribution when the voltage and the currents of the digitized factors were modified Nonetheless, a basic operational management information was achieved.

• Journal of Science Education
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• v.32 no.1
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• pp.33-46
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• 2008

The purpose of this study was to know whether or not any wrongful description or simple errors were in photosynthesis unit of Biology II textbook under 7th national curriculum and if so, to know whether or not high school teachers recognized and corrected properly the mistakes. The mistakes in photosynthesis unit of text books were determined by the comparison with several reference books and through examination by three plant physiologists in 8 different Biology II textbooks. After the mistakes were analysed, the survey using contents of textbook containing the mistakes was conducted on high school teachers teaching Biology II. As a result, 48 mistakes were determined in 13 subjects. As many as four mistakes were found even in one subject in a certain textbook and a same mistake was found repeatedly in several textbooks. The survey result showed that the teachers who pointed exactly the mistakes out corrected properly, however, the percentage of these ones out of 35 teachers replied to survey was less than 50%. The ratios of correction out of total number of responses were high in question #6 (43%), #4-3 (40%), and #1-2 (32%) which were containing a simple mistake in graph, a wrong word and a wrong picture, respectively. But, no one pointed out and made correction in question #5-1 and #5-2 which were containing Z scheme of light reaction without the legend of vertical axis that should be explained as electron energy or standard reduction potential. The result indicates the possibility that the mistakes in photosynthesis unit of Biology II textbook can be corrected and teached properly by teachers may be low. In order to reduce the possibility that students may have misconceptions about photosynthesis, the list of print's errors should be provided to the teachers and/or the training program and/or workshop for in-service high school biology teachers was recommended.

• Hwankyungkyoyuk
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• v.6 no.1
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• pp.63-99
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• 1994

The international environmental activities and environmental education began in 1970's. Environmental education in Korea was emphasized since the Forth National Curriculum. 'The Environmental Education Curriculum' will be separated as one of the most important parts in the Sixth National Education Curriculum in Korea. The purpose of this study was development. of 'Environmental Science' of high school appropriate to Sixth National Education Curriculum. First step was to state goals of environmental education in detail based on analysis of goals about environmental education in our country and other countries. Second was to analyse seven environments-related texts of Korea, America and England. Third, to measure how much environmental education has achieved in Fifth National Curriculum of Korea. Fourth, to develop a new environmental text of high school level. Fifth, to verify the effect of developed environmental text. The environmental part of 'Science I'(unit V. Life and Environments) and high school environments-related reference text(Survival and Environments) in Korea, American knowledges. American 'Environments' was stressed in many skills but they didn't include various teaching strategies. On the other hand, American 'Science-Technology-Society(S-T-S)' and British 'Science and Technology in Society(SATIS)' were stressed in knowledges and skills, and they included many teaching strategies and student actions. American 'S-T-S' was the only one stressed in values and attitudes. And all seven texts were not interested in behaviors and participations. To measure the achievement of environmental education by questionnaire, 497 high school students in total were selected from five different schools. Actually, most students had a positive thinkings and attitudes in their hearts about environmental problems, about environmental problems, but many of them did not take actions to solve environmental problems and to protect environments. The higher the score students got in 'knowledges and informations', the higher the score in 'skill'. It implies that learning of skills is based on learning of knowledges and informations about environments. On the other hand, much knowledges and information about environments has not always ensured positive thinkings and attitudes or active behaviors and participations to solve environmental problem. In view that ultimate aim of environmental education is forming responsible environmental behaviors and the goals of values and behaviors are as important as knowledges and skills. A new environmental text of high school level was developed and it was based on analysis of seven texts and environmental education in Fifth Korean Curriculum. This text have seven units, 1. Habitates : What're the meanings?, 2. Nuclear Energy : Can't be Avoid?, 3. Acid Rain : What're the Messages?, 4. Ethanol : Is this Future Fuel?, 5. Wastes : A New War!, 6. What're the National and Gloval Environmental education and avoided from the array of knowledges. Therefore included various teaching strategies and independent actions of students. 'Open-ended value learning' and 'free behavior learning' in text were special learning parts for aquisition of values and formation of behaviors. To verify the effects. of new developed environmental text, the direct learning was carried out by 286 students in total. Post test scores of experimental groups per each units were significantly higher than those of control groups from five different schools were as follows. For validity of selecting contents for units, 74% of respondent replied positively. For classification and presentation of four goal-groups, 90% replied positively in validity and 82%, in utility. For validity of various teaching strategies, 88% and for the degree of including student-centered independent actions, 86% replied positively, For importances and expected effects of 'open=ended value learning' and 'free behavior learning', showed positive responses respectively, 88%, 92% Therefore this text is effective to achieve four goals of environmental education equally.

• Progress in Medical Physics
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• v.23 no.2
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• pp.114-122
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• 2012

For the determination of absorbed dose to water from a linear accelerator photon beams, it needs a exposure calibration factor $N_x$ or air kerma calibration factor $N_k$ of air ionization chamber. We used the exposure calibration factor $N_x$ to find the absorbed dose calibration factors of water in a reference source through the TG-21 and TRS-277 protocol. TG-21 used for determine the absorbed dose in accuracy, but it required complex calculations including the chamber dependent factors. The authors obtained the absorbed dose calibration factor $N_{dw}{^{Co-60}}$ for reduce the complex calculations with unknown $N_{dw}$ only with $N_x$ or $N_k$ calibration factor in a TM31010 (S/N 1055, 1057) ionization chambers. The results showed the uncertainty of calculated $N_{dw}$ of IC-15 which was known the $N_x$ and $N_{dw}$ is within -0.6% in TG-21, but 1.0% in TRS-277. and TM31010 was compared the $N_{dw}$ of SSDL to that of PSDL as shown the 0.4%, -2.8% uncertainty, respectively. The authors experimented with good agreement the calculated $N_{dw}$ is reliable for cross check the discrepancy of the calibration factor with unknown that of TM31010 and IC-15 chamber.