• Progress in Medical Physics
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• v.16 no.2
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• pp.89-96
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• 2005

In this study, we investigated the effect of time gating threshold on the delivered dose at a organ with internal motion by respiration. Generally, the internal organs have minimum motion at exhalation during normal breathing. Therefore to compare the dose distribution time gating threshold, in this paper, was determined as the moving region of target during 1 sec at the initial position of exhalation. The irradiated fields were then delivered under three conditions; 1) non-moving target 2) existence of the moving target in the region of threshold (1sec), 3) existence of the moving target region out of threshold (1.4 sec, 2 sec). And each of conditions was described by the moving phantom system. It was compared with the dose distributions of three conditions using film dosimetry. Although the treatment time increased when the dose distributions was obtained by the internal motion to consider the TGT, it could be obtained more exact dose distribution than in the treatment field that didn't consider the internal motion. And it could be reduced the unnecessary dose at the penumbra region. When we set up 1.4 sec of threshold, to reduce the treatment time, it could not be obtained less effective dose distribution than 1 sec of threshold. Namely, although the treatment time reduce, the much dose was distributed out of the treatment region. Actually when it is treated the moving organ, it would rather measure internal motion and external motion of the moving organ than mathematical method. If it could be analyzed the correlation of the internal and external motion, the treatment scores would be improved.

• The Journal of the Korea Contents Association
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• v.16 no.1
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• pp.24-41
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• 2016

Study is about Bit Coin that is electronic cash that is received attention globally in recent. It is increasing domestically that uses bit coin for convenience of micro payment, and also bit coin is possible to exchange each countries' currency. In this point, we searched understanding degree and acceptance of bit coin. Also we applied transformed TAM(Technology Acceptance Model) to search factors that have an effect on consumers' intention to use it. In advance, we analyze features of bit coin, and extract factors through preceding researches for existing electronic cash, because studies for intention to use bit coin are weak in internal and external. First of results is that 'economic efficiency' which is a characteristic variable of bit coin influences 'intention to use,' a dependent variable through 'perceived usefulness,' a parameter. It was investigated that monetary and mental costs that was costed when we use bit coin were less than using other cash. Secondly, 'payment convenience' that is a characteristic variable affects 'intention to use', a dependent variable through 'perceived usefulness,' a parameter. It was measured that problems of inconvenience that include transaction process, cash management time shortage and exchange changes will be solved by using bit coin. Thirdly, 'reliability' that is a perceived risk variable of bit coin has a direct effect on 'intention to use,' a dependent variable. It was investigated that we could achieve purpose of payment because we weren't influenced by breakdown on system by processing distributed database in some computers. Fourthly, 'perceived usefulness,' a parameter of bit coin directly affects 'intention to use,' a dependent variable. Then consumers who want to use bit coin are fascinated bit coin for various usability. Moreover, we want to provide implications to all of finance corporations, companies related electronic cash and bit coin users based on these results.

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.103-113
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• 1995

To estimate buffer capacity and sensitivity of forest ecosystem to acid rain in Taejon, ionic components of throughfall, stemflow, soil leachate, and open rain in Pinus rigida and Quercus variabilis forest were analysed. The spatial sensitivity based on parent rock and forest type was given by IDRISI of GIS which created imagery conversion from soil and vegetation map. Parent rocks and soils were classified into acidic, sedimentary, metamorphic rock and then subdivided based on $SiO_2$ content. Average pH of vegetation leachate was higher in throughfall but lower in stemflow than open rain and higher in Quercus variabilis forest than in Pinus rigida forest. The flow of $SO{_4}^{2-}$, $NO_3{^-}$ and $Cl^-$ through vegetation leaching(throughfall plus stemflow) into soil were 7.2, 4.3, and 2.5 times, respectively, higher in Pinus rigida forest and 4.4, 2, and 2.5 times, respectively, higher in Quercus variabilis forest than in open field. But the concentration of exchangeable cations was 4.1 times higher in Pinus rigida forest and 4.6 times higher in Quercus variabilis forest than in open field. Average pH of soil leachate was lower than that of throughfall, but higher than that of stemflow. The concentration of exchangeable canons and $Al^{3+}$ in soil leachate were more in Pinus rigida forest than in Quercus variabilis forest and increase signficantly with the increase of acidic deposits. Pinus forest had more deposition and canopy interception of acidic pollutants and more nutrient loss than Quercus forest, and Quercus forest had more cation exchange and proton consumption and than consequently had less nutrient loss and better buffer capacity than Pinus forest. The 69% of forest soils was distributed on acidic rock, 25% of it on metamorphic rock, and 6% of it on intermediate and basic rock. Acidic rock residuals which had low very canon exchange capacity and high sensitivity to acid rain occupied a half of total forest land in Taejon area. Therefore forests in Taejon showed high vulnerability to acid rain and will receive much more stress with the increase of acid rain precursors.

• Journal of Korean Society of Forest Science
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• v.97 no.6
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• pp.627-633
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• 2008

This study was conducted to estimate volume growth rates for major Quercus species distributed in Korea, and based on the data collected from the 5th National Forest Inventory. Volume growth rates were estimated by each age class for each species, and their similarity or distinction was statistically analyzed. It was also intended to compare the resulted volume growth rates with the existing growth rates, and to develope a volume growth rate estimation model for the Quercus species. Six major Quercus species were considered in this study; Quercus acutissima, Quercus aliena, Quercus serrata, Quercus variabilis, Quercus dentata, and Quercus mongolica. Based on the data collected from the 5th National Forest Inventory, the diameter growth rates and the height growth rates were estimated for each species, and then the volume growth rates were estimated with the given diameter and height growth rates. To examine the distinction between species or age classes, statistical analyses such as ANOVA and Duncan's multiple range test were applied. The results indicated that the volume growth rate was 10% in the age class II, 6% in the age class III, and lower in the subsequent classes. In addition, the volume growth rates of Quercus acutissima, Quercus aliena, and Quercus serrata were relatively high compared to those of Quercus variabilis, Quercus dentata, and Quercus mongolica. According to their growth rates, the six Quercus species were classified into two groups; high-growth-rate group and low-growth-rate group. Statistical analysis conducted to examine the difference between and within the groups showed that there is no significant difference within groups, while significant between groups. Based on the results, volume growth rate estimation model were finally developed for each group. The classification of the Quercus species suggested in this study was not the same with that of existing volume growth estimation. Thus, it is necessary to improve the existing volume growth rate or its estimation system.

• Journal of Korean Academy of Nursing Administration
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• v.1 no.1
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• pp.132-146
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• 1995

Even though Korean medical law stipulates that number of patients attended by a nurse is 2.5 for hospitalization and 30 for ambulatory care, the number of patients cared by a nurse per day is much greater than the standard prescribed by the medical law. Current productivity of nurses is not desirable unless the quality of care is considered. And nursing manpower staffing based on neither current nurses' productivity nor standard of medical law cannot respond properly to dynamic situation of the medical services. Under this background, the necessity of more efficient management of nursing manpower occupying 1/3 of total hospital workers has been recognized by many nursing administrators. Many nursing researchers have studied to foretell the nursing manpower objectively on the basis of measured nursing workload according to patient classification as well. Most of These researches, however, have been conducted in the tertiary hospitals, so it is imperative to conduct other researches to predict necessary nursing manpower in the secondary and the primary hospitals. The study was performed to measure nursing workload and predict pertinent nursing manpower to a secondary hospital with 400beds. Nursing workload was surveyed using measuring tool for direct and indirect care hours in a surgical unit and a medical unit. Survey was conducted from Sep.10 to Sep.16 and from Oct.5 to Oct.11, 1994 respectively by two skilled nurses, Subjects were patients, patients' family members and nursing personnels. Results are follows : 1. Patient classification distributed as 22% of class I (mildly ill patient), 57% of class II (moderately ill patient), and 21% of class III (acutely ill patient) in the medical nursing unit, while 23% of class I, 29% of class II, 12% of class III, and 36% of classIV (critically ill patient) in the surgical nursing unit. There was no difference of inpatient number between weekday and weekend. Bed circulation rate was 89% in both units and average patients number per day was 37.4 (total 42beds) in the medical nursing unit, 32.9 (total 37beds) in the medical nursing unit. 2. Direct care hours per day measured as 2.8hrs for class I, 3.3hrs for class II, and 3.5hrs for class III in the medical nursing unit, while 3.1hrs for class I, 3hrs for class II, 2.7hrs for class III, and 2.2hrs for classIV in the surgical nursing unit. Meanwhile, hours for nursing assistant activities per patient by patients' family members were 11mins and 200mins respectively. Direct care hour rate by shift was day 36%, evening 25%, and night 39% in the medical nursing unit, while 40%, 29%, and and 31% respectively in the surgical nursing unit. 3. Measurement and observation activity held 44.2% of direct care activities of nurses and medication 36.7%, communication 11.7%, exercise 1.8%, treatment 1.3%, hygiene 1.3%, elimination and irrigation 1.1%, suction 1%, nutrition 0.5%, thermotherapy 0.3%, oxygen therapy 0.1% in order. 4. Indirect care hours per day were 294.2mins in the medical nursing unit, and 273.9mins in the surgical nursing unit. By shift, evening was the highest in both units. Indirect care hours for each patient were 44.5mins in the medical nursing unit and 46mins in the surgical nursing unit. 5. checking activities including doctor's order, medication, and delivering patients to the next shift occupied 39.7% of indirect care activities, and preparation 26%, recording 23.8%, communication and conference 6.7%, managing equipments 2.1%, messenger activity 1.7% in order. 6. On the ground of these results, nursing manpower needed in a secondary hospital was estimated ; 27 nursing personnels for the medical nursing unit of 37beds, and 20 nursing personnels for the surgical nursing unit of 33beds.

• Progress in Medical Physics
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• v.16 no.1
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• pp.10-15
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• 2005

IAEA's guidance levels have been provided for western people to the end. Guidance levels lower than the IAEA'S will be necessary in view of Korean people's proportions. Therefore, we need to develope the standard doses for Korean people. And we conducted a nationwide survey of patient dose from x-ray examinations in Korea. In this study, the 278 institutions were selected from Members Book of Korean Hospital Association. The valid response rate was approximately 57.9%. Doses were calculated from the questionnaires by NDD method. We obtained the results were as follows; 1) General radiographic equipments were distributed for 42.0%, fluoroscopic equipments 29.4%, dental equipments 13.2%, CT units 8.1 % and mamographic units 7.2%. 2) According to classification by rectification, three-phase equipments were 29.9%, inverter-type generators 29.5%, single-phase equipments 25.5%, constant voltage units 9.0% and unknown units 6.0%. 3) According to classification by receptor system, film-screen types were 46.8%, CR types 26.8%, DR types 17.7% and unknown types 8.9%. 4) The number of examinations were chest 49.2%, spine 16.8% and abdomen 12.7%. 5) Patient doses were head AP 3.44 mGy, abdomen AP 4.25 mGy and chest PA 0.39 mGy.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.2
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• pp.113-122
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• 2010

Purpose: To evaluate the accuracy of a target position at static and dynamic state by using Dynamic phantom for the difference between tumor's actual movement during respiratory gated radiation therapy and skin movement measured by RPM (Real-time Position Management). Materials and Methods: It self-produced Dynamic phantom that moves two-dimensionally to measure a tumor moved by breath. After putting marker block on dynamic phantom, it analyzed the amplitude and status change depending on respiratory time setup in advance by using RPM. It places marker block on dynamic phantom based on this result, inserts Gafchromic EBT film into the target, and investigates 5 Gy respectively at static and dynamic state. And it scanned investigated Gafchromic EBT film and analyzed dose distribution by using automatic calculation. Results: As a result of an analysis of Gafchromic EBT film's radiation amount at static and dynamic state, it could be known that dose distribution involving 90% is distributed within margin of error of 3 mm. Conclusion: As a result of an analysis of dose distribution's change depending on patient's respiratory cycle during respiratory gated radiation therapy, it is expected that the treatment would be possible within recommended margin of error at ICRP 60.

• Horticultural Science & Technology
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• v.35 no.3
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• pp.344-360
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• 2017

Zoysiagrasses are important turf plants used for school playgrounds, parks, golf courses, and sports fields. The two most popular zoysiagrass species are Zoysia japonica and Zoysia sinica. These are widely distributed across different growing zones and are morphologically distinguishable from each other; however, it is phenotypically difficult to differentiate those that grow along the coastal line from those in beach area habitats. A combination of morphological and molecular approaches is desirable to efficiently identify these two plant cultivars. In this study, we used a rapid identification system based on DNA barcoding of the nrDNA-internal transcribed spacer (ITS) regions. The nrDNA-ITS regions of ITS1, 5.8S nrDNA, and ITS2 from Z. japonica, Z. sinica, Agrostis stolonifera, and Poa pratensis were DNA barcoded to classify these grasses according to their molecular identities. The nrDNA-ITS sequences of these species were found at 686 bp, 687 bp, 683 bp, and 681 bp, respectively. The size of ITS1 ranged from 248 to 249 bp, while ITS2 ranged from 270 to 274 bp. The 5.8S coding region ranged from 163 - 164bp. Between Z. japonica and Z. sinica, nineteen (2.8%) nucleotide sites were variable, and the G+C content of the ITS region ranged from 55.4 to 63.3%. Substitutions and insert/deletion (indel) sites in the nrDNA-ITS sequence of Z. japonica and Z. sinica were converted to cleaved amplified polymorphic sequence (CAPS) markers, and applied to the Zoysia grasses sampled to verify the presence of these markers. Among the 62 control and collected grass samples, we classified three groups: 36 Z. japonica, 22 Z. sinica, and 4 Z. japonica/Z. sinica hybrids. Morphological classification revealed only two groups; Z. japonica and Z. sinica. Our results suggest that used of the nrDNA-ITS barcode region and CAPS markers can be used to distinguish between Z. japonica and Z. sinica at the species level.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.71-85
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• 2018

A recent topic of interest within ecology is ecosystem services that are importantly connected with biodiversity. Biodiversity is a fundamental component of ecological studies and has been the subject of many studies worldwide. However, studies on the diversity and distribution of freshwater fish were not undertaken in earnest until 2000, and the number of internationally available studies is therefore still limited. In this study, we used data from "The Survey and Evaluation of Aquatic Ecosystem Health (hereafter SEAEH)" within the framework of which whole water systems on the Korean peninsula are annually monitored to investigate and determine the current status of the diversity and distribution of freshwater fish, as well as to elucidate major factors impacting freshwater fish. A total of 130 species from 28 families were identified at around 953 sites in the SEAEH investigation of 2014. The species Zacco platypus (relative abundance: 28.2%) and Z. koreanus (19.3%) were identified as the most abundant species on the Korean peninsula, and besides these 20 endangered species, 51 endemic species and 4 exotic species were also collected. Highest (96 species) and lowest (72 species) diversity were identified in the Han River Watershed and the Yeongsan/Seomjin River Watershed, respectively. The mean endemic rate was 32.7%, which is higher than the previous rate determined in 1995. The exotic species Micropterus salmoides, Lepomis macrochirus and Carassius cuvieri were found in the whole river system except north Yeongdong, whereas Oreochromis niloticus occurred only at three sites due to the cold water temperatures in winter. Totally, 28 species were found to be translocated to different water systems not connected with known original habitats, most translocations occurring in the Nakdong River and the Yeongdong region. Among the translocated species, Opsariichthys uncirostris amurensis, and Erythroculter erythropterus were dominantly distributed in the mid- to lower reaches of Nakdong River where they may be harmful to the native fish assemblages due to their strong predation. The construction of weirs in connection with the "4 River Project" generated changes in fish assemblages before, during and after the project, resulting in altered habitat condition. Especially, a decrease in the number of endemic species and an increase in the abundance of lentic species were seen. Human-induced global warming will allow exotic species requiring high water temperatures to adapt to the environmental conditions of the Korean peninsula, which may enhance the diversity of native fishes and create changes in distribution. For the establishment of realistic and efficient management and protection strategies for Korean freshwater fish, SEAEH, which produces fundamental and quantitative data for Korean streams, is an important and necessary tool.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.1
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• pp.8-13
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• 2010

Seedling establishment, overwintering ability and dry matter production of Chinese milk vetch (Astragalus sinicus L. CMV) in natural reseeding practice were compared with the annual seedling in 2006~2007 and 2007~2008. In natural reseeding, CMV seeds were distributed up to 15 cm soil depth in autumn after rice harvest and the seeds generally emerged from soil at less than 5 cm depth while they all emerged from soil surface in the annual seeding. It took 7-8 d longer in seedling establishment of the natural reseeding practice than the annual seeding. Generally, the natural reseeding practice showed higher seedling stand than the annual seeding because of high seedling survival rate. The high seedling survival rate in natural reseeded plant was attributed to the longer root length than that of the annual-seeded plant. In annual seeding, most of the seeds emerged from the soil surface and the root can not easily penetrate the soil while, in natural reseeding technology, the seeds incorporated into the soil during land preparation emerged from the soil at 0 to 5 cm depths, thereby having longer root length. The long root length contributed to greater ability to survive even under low temperature and low soil moisture conditions during winter. The dry matter production in the natural reseeding practice was also higher than the annual seeding when the temperature is low and soil moisture is not sufficient. This result indicates that natural reseeding technology is more stable and beneficial in seedling establishment and dry matter production as compared with the annual seeding especially under unfavorable environmental condition for CMV growth. This practice could be encouraged in CMV-rice cropping system in the southern parts of Korea.