• Journal of radiological science and technology
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• v.36 no.2
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• pp.123-129
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• 2013

This study investigated the rate of setup variance by the rotating unbalance of gantry in image-guided radiation therapy. The equipments used linear accelerator(Elekta Synergy TM, UK) and a three-dimensional volume imaging mode(3D Volume View) in cone beam computed tomography(CBCT) system. 2D images obtained by rotating $360^{\circ}$and $180^{\circ}$ were reconstructed to 3D image. Catpan503 phantom and homogeneous phantom were used to measure the setup errors. Ball-bearing phantom was used to check the rotation axis of the CBCT. The volume image from CBCT using Catphan503 phantom and homogeneous phantom were analyzed and compared to images from conventional CT in the six dimensional view(X, Y, Z, Roll, Pitch, and Yaw). The variance ratio of setup error were difference in X 0.6 mm, Y 0.5 mm Z 0.5 mm when the gantry rotated $360^{\circ}$ in orthogonal coordinate. whereas rotated $180^{\circ}$, the error measured 0.9 mm, 0.2 mm, 0.3 mm in X, Y, Z respectively. In the rotating coordinates, the more increased the rotating unbalance, the more raised average ratio of setup errors. The resolution of CBCT images showed 2 level of difference in the table recommended. CBCT had a good agreement compared to each recommended values which is the mechanical safety, geometry accuracy and image quality. The rotating unbalance of gentry vary hardly in orthogonal coordinate. However, in rotating coordinate of gantry exceeded the ${\pm}1^{\circ}$ of recommended value. Therefore, when we do sophisticated radiation therapy six dimensional correction is needed.

• Journal of radiological science and technology
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• v.36 no.1
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• pp.49-55
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• 2013

Currently, commercially available phantom can reproduce and evaluate only a static situation, the study is incomplete research on phantom and system which is can confirmed functional situation in the kidney by time through dynamic phantom and blood flow velocity, various difference according to the amount of radioactive. Therefore, through this study, it has produced the dynamic kidney phantom to reproduce images through the dynamic flow of the kidney, it desires to evaluate the usefulness of nuclear medicine imaging. The production of the kidney phantom was fabricated based on the normal adult kidney, in order to reproduce the dynamic situation based on the fabricated kidney phantom, in this study, it was applied the volume pump that can adjust the speed of blood flow, so it can be integrated continuously radioactive isotopes in the kidney by using $^{99m}Tc$-pertechnate. Used the radioactive isotope was supplied through the two pump. It was confirmed the changes according to the infusion rate, radioactive isotopes and the different injection speeds on the left and right, analysis of the acquired images was done by drawn five times ROI in order to check the reproducibility of each on the front and rear of the kidney and bladder. Depending on the speed of injection, radioisotope was a lot of integrated and emissions up when adjusting the pressure of the pump as 30 stroke, it was the least integrated and emissions up when adjusting as 40 stroke. The integration of the left & right kidney was not reached in the amount of the highest when adjusting as 10 stroke. In the changes according to the amount of the radioactive isotope, 0.6 mCi(22.2 MBq), 0.8 mCi (29.6 MBq)was showed up similar tendency but, in the result of the different injection 0.8 mCi, it was showed up counts close to double of 0.6 mCi. In the result of the differently injection speed of the left & right kidney, as a result of different conditions that injection speed was 20 stroke through left kidney phantom, the injection speed was 30 stroke through right kidney phantom, it was enough difference in the resulting image can be easily distinguished with the naked eye. Through this study, the results showed that the dynamic kidney phantom system is able to similarly reproduce renogram in the actual clinical practice. Especially, the depicted over time for the flow to be excreted through the kidney into the bladder was adequately reproduce, it is expected to be utilized as basic data to check the quality of the dynamic images. In addition, it is considered to help in the field of functional imaging and quality control.

• Journal of radiological science and technology
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• v.39 no.1
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• pp.1-11
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• 2016

The purpose of this study was to provide resources for medical exposure reduction through evaluation of organ dose and image resolution for lumbar spine around according to the size of the collimator in DR system. The size of the collimator were varied from $8^{\prime\prime}{\times}17^{\prime\prime}$ to $14^{\prime\prime}{\times}17^{\prime\prime}$ by 1" in AP and lateral projection for the lumbar spine radiography with RANDO phantom. The organ dose measured for liver, stomach, pancreas, kidney and gonad by the glass dosimeter. The image resolution was analyzed using the Image J program. The organ dose of around lumbar spine were reduced as the size of the collimator is decreased in AP projection. There were no significant changes decreasing rate whenever the size of the collimator were reduced 1" in the gonad. The organ dose showed higher on liver and kidney near the surface in lateral projection. There were decreasing rate of less than 5% in liver and kidney, but decreasing rate was 24.34% in the gonad whenever the size of the collimator were reduced 1". Organ dose difference for internal and external of collimator measured $549.8{\mu}Gy$ in the liver and $264.6{\mu}Gy$ in the stomach. There were no significant changes organ dose difference that measured $1,135.1{\mu}Gy$ in the gonad. Image Quality made no difference because SNR and PSNR were over than 30 dB when the collimator size is less than $9^{\prime\prime}{\times}17^{\prime\prime}$ on AP projection and $10^{\prime\prime}{\times}17^{\prime\prime}$ on lateral projection. Therefore, we are considered that the recommendations criterion for control of collimator were suggested in order to reduce unnecessary X-ray exposure and to obtain good image quality because lumbar spine radiography contains a lot of peripheral organs rather than other area radiography.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.549-556
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• 2017

This study compared the spatial scattered dose distribution according to whether the recently developed radiation shielding is used or not in order to understand the spatial scattered dose distribution of C-arm. The horizontal side distribution increased by $30^{\circ}$ in the interval of the radius 50 cm on the height of 95 cm based on the head of the patient, and it was measured by increasing $30^{\circ}$ with the interval of 50 cm in the vertical side of each horizontal side. In the same method, the radiation shielding was installed and measured. The result of measurement shows that the horizontal side of 50 cm distance was $0^{\circ}$, $90^{\circ}$ and $180^{\circ}$, was $1.77{\pm}0.12$, $1.90{\pm}0.13$, $2.12{\pm}0.14$, and $2.69{\pm}0.15mSv/h$ in the $270^{\circ}$ direction, and was $1.59{\pm}0.12$, $0.99{\pm}0.09$, $1.47{\pm}0.11$, and $1.37{\pm}0.11mSv/h$ after the use of the radiation shielding. In addition, the vertical distribution in horizontal direction $90^{\circ}$ with 50 cm distance was $30^{\circ}$, $60^{\circ}$, $120^{\circ}$, was $3.85{\pm}0.18$, $9.15{\pm}0.28$, $10.82{\pm}0.31$, and $5.40{\pm}0.22mSv/h$ in $150^{\circ}$, and was $2.03{\pm}0.13$, $4.32{\pm}0.19$, $2.76{\pm}0.16$, and $1.92{\pm}0.13mSv/h\;mR/h$ after the use of the radiation shielding. Both direction showed decrease according to the use of the radiation shielding. Therefore, radiation related workers who work in operating rooms should recognize the spatial scattered dose distribution exactly and need to try to prevent the risk of radiation exposure with proper protective measures.

• Korean Journal of Remote Sensing
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• v.31 no.6
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• pp.501-512
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• 2015

Landfast sea ice (LFI) in Terra Nova Bay, East Antarctica where the Jangbogo Antarctic Research Station is located, has significant influences on marine ecosystem and the sailing of an icebreaker. Therefore, it is essential to analyze the spatio-temporal variation of the LFI in Terra Nova Bay. In this study, we chose interferometric pairs with the temporal baseline from 1 to 9 days out of a total of 62 COSMO-SkyMed synthetic aperture radar (SAR) images over Terra Nova Bay obtained from December 2010 to January 2012, and then constructed the coherence image of each pair. The LFI showed coherence values higher than 0.3 even in the interferometric SAR (InSAR) pairs of up to 9-days of temporal baseline. This was because the LFI was fixed at coastline and thus showed low temporal phase decorrelation. Based on the characteristics of the coherence on LFI, We defined the areas of LFI that show spatially homogeneous coherence values higher than 0.5. Pack ice (PI) and open water showed low coherence values due to large temporal phase decorreation caused by current and wind. Distinguishing PI from open water in the coherence images was difficult due to their similarly low coherence values. PI was identified in SAR amplitude images by investigating cracks on the ice. The extents of the LFI and PI were estimated from the coherence and SAR amplitude images and their temporal variations were analyzed. The extent of the LFI increased from March to July (maximum extent of $170.7km^2$) and decreased from October. The extent of the PI increased from February to May and decreased from May to July when the LFI increases dramatically. The extent of the LFI and air temperature showed an inverse correlation with a time lag of about 2 months, i.e., the extent of the LFI decreases after 2 months of the increase in the air temperature. Meanwhile the correlation between wind speed and the extent of the LFI was very low. This represents that the extent of LFI in Terra Nova Bay are influenced more by the air temperature than wind speed.

• Korean Journal of Remote Sensing
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• v.30 no.5
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• pp.597-605
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• 2014

The continuous observations for atmospheric aerosols were conducted during 3 years (2009 to 2011) by using Gwangju Institute of Science and Technology (GIST) multi-wavelength Raman lidar at Gwangju, Korea ($35.10^{\circ}N$, $126.53^{\circ}E$). The aerosol depolarization ratios calculated from lidar data were used to identify the Asian dust layer. The optical properties of Asian dust layer were different according to its vertical distribution. In order to investigate the difference between the optical properties of each individual dust layers, the transport pathway and the transport altitude of Asian dust were analyzed by Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. We consider that the variation of optical properties were influenced not only their transport pathway but also their transport height when it passed over anthropogenic pollution source regions in China. The lower particle depolarization ratio values of $0.12{\pm}0.01$, higher lidar ratio of $67{\pm}9sr$ and $68{\pm}9sr$ at 355 nm and 532 nm, respectively, and higher ${\AA}ngstr\ddot{o}m$ exponent of $1.05{\pm}0.57$ which are considered as the optical properties of pollution were found. In contrast with this, the higher particle depolarization ratio values of $0.21{\pm}0.09$, lower lidar ratio of $48{\pm}5sr$ and $46{\pm}4sr$ at 355 nm and 532 nm, respectively, and lower ${\AA}ngstr\ddot{o}m$ exponent of $0.57{\pm}0.24$ which are considered as the optical properties of dust were found. We found that the degree of mixing of anthropogenic pollutant aerosols in mixed Asian dust govern the variation of optical properties of Asian dust and it depends on their altitude when it passed over the polluted regions over China.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.1-7
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• 2004

To choose a organic acid and in-organic acid composite which is the most effective in soil-flushing process cleaning lead-contaminated sites, lead removal rates were investigated in the experiments with some organic acids; 0.01M of EDTA showed the highest lead-extraction rate ($69.4\%$) compared to the other organic acids. Furthermore, the lead removal rates were measured with 0.01M of EDIA and 0.1M of in-organic acid ; a EDTA and boric acid composite showed the highest lead-extraction rate ($68.8\%$) at pH5 compared to the other composites. As the concentration of boric acid was increased from 0.1M to 0.4M in a 0.01M of EDTA and boric acid composite, lead removal rate was decreased from $68\%\;to\;45\%$. But as the concentration of EDTA was increased from 0.01M to 0.04M in a EDTA and 0.1M of boric acid composite, permeability was decreased from $6.98{\times}10^{-4}cm/sec$ (0.01M of EDTA) to $5.99{\times}10^{-4}cm/sec$ (0.04M of EDTA). However, permeability was increased from $4.41{\times}10^{-4}cm/sec$ (0.03M of EDTA) to $6.26{\times}10^{-4}cm/sec$ (0.03M of EDTA and 0.1M of boric acid composite). indicating EDTA could increase lead dissolution/extraction rate and decrease permeability. In this system, lead remediation rate is the function of lead dissolution rate from soils and permeability of the composite into soils, and the optimized [EDTA]/[Boric acid] ratio is [0.01M]/[0.1M].

• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.45-53
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• 2005

The objective of this study is to evaluate the effects of changes in soil temperature on biodegradation rate of diesel compounds from a field pilot test using hot air injection process. Total remediation time was estimated from in-situ biodegradation rate and temperature for optimum biodegradation. All tests were conducted by measuring in-situ respiration rates every about 10 days on highly contaminated area where an accidental diesel release occurred. The applied remediation methods were hot air injection/extraction process to volatilize and extract diesel compounds followed by a bioremediation process to degrade residual diesels in soils. Oxygen consumption rate varied from 2.2 to 46.3%/day in the range of 26 to $60^{\circ}C$, and maximum $O_2$ consumption rate was observed at $32.0^{\circ}C$. Zero-order biodegradation rate estimated on the basis of oxygen consumption rates varied from 6.5 to 21.3 mg/kg-day, and the maximum biodegradation rate was observed at $32^{\circ}C$ as well. In other temperature range, the values were in the decreasing trend. The first-order kinetic constants (k) estimated from in-situ respiration rates measured periodically were 0.0027, 0.0013, and $0.0006d^{-1}$ at 32.8, 41.1, and $52.7^{\circ}C$, respectively. The estimated remediation time was from 2 to 9 years, provided that final TPH concentration in soils was set to 870 mg/kg.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.53-59
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• 2001

There is a lot of method to manage the insanitary landfill but vertical cutoff walls have been widespreadly used and were installed into the subsurface to act as a barrier to horizontal groundwater flow, The stabilized material such as specialized cement or mixed soil with additives has been generally applied for the materials of the deep soil mixing barrier in korea. The amount of the stabilized material is dependent on the field conditions, because the mixing ratio of the material and the field soil should achieve a requirement in the coefficient of permeability, lower than 1.0$\times$$10^{7}$cm/sec. This study determined the quantity and optimized function ratio of the stabilized material in the formation process of the mixed barrier that was added with stabilized material on the field soil classified into SW-SC under USCS (Unified Soil Classification System). After that the fly ash and lime were selected as an additives an that could improve the function of the stabilized material and then the method to improve the functional progress in the usage of putting into the stabilized material as an appropriate ratio was studied and reviewed. The author used the flexible-wall permeameter for measuring the permeability and unconfined compressive strength tester for compressive strength, and in the view of environmental engineering the absorption test of heavy metals and leaching test regulated by Korean Waste Management Act were performed. As the results, the suitable mixing ratio of the stabilized material in the deep soil mixing barrier was determined as 13 percent. To make workability easy, the ratio of stabilized material and water was proven to be 1 : 1.5. With the results, the range of the portion of the additives(fly ash : lime= 70 : 30) was proven to be 20-40% for improving the function of the stabilized material, lowering of permeability. In heavy metal absorption assessment of the mixing barrier system with the additives, the result of heavy metal absorption was proved to be almost same with the case of the original stabilized material; high removal efficiency of heavy metals. In addition, the leaching concentration of heavy metals from the leaching test for the environmental hazard assessment showed lower than the regulated criteria.

• The Korean Journal of Mycology
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• v.38 no.2
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• pp.105-111
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• 2010

Lentinus lepideus, known as train wrecker fungus, has been used for nutritional and medicinal purposes. Recently, commercial cultivation technique and a new cultivar of the mushroom were developed. To investigate the genetic diversity and phylogenetic relationship for identifying the mushroom strains and cultivar, one commercial and 13 strains of Lentinus lepideus from different geographical regions of Korea were analyzed by ITS regions of rDNA and RAPD of genomic DNA. Three strains of Lentinus edodes were also used for the analysis. The size of the ITS1 and ITS2 regions of rDNA from the different strains varied from 173 to 179 bp and 203 to 205 bp, respectively. The sequence of ITS1 was more variable than that of ITS2, while the 5.8S sequences were identical with 156 base pairs. A phylogenetic tree based on the ITS region sequences indicated that selected strains could be classified into four clusters, while 3 strains of L. edodes was divided into a new cluster. Ten primers out of 20 arbitrary primers used in the RAPD-PCR efficiently amplified the genomic DNA. The numbers of amplified DNA bands varied with the primers and strains, with polymorphic DNA fragments in the range from 0.2 to 2.6 kb. The results showed that phylogenetic relationship among Korean strains of Lentnus lepideus is high, but genetic diversity is low.