• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.122-126
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• 2010

Purpose: F-18-FPCIT that shows strong familiarity with DAT located at a neural terminal site offers diagnostic information about DAT density state in the region of the striatum especially Parkinson's disease. In this study, we altered the iteration and subset and measured SUV${\pm}$SD and Contrasts from phantom images which set up to specific iteration and subset. So, we are going to suggest the appropriate range of the iteration and subset. Materials and Methods: This study has been performed with 10 normal volunteers who don't have any history of Parkinson's disease or cerebral disease and Flangeless Esser PET Phantom from Data Spectrum Corporation. $5.3{\pm}0.2$ mCi of F-18-FPCIT was injected to the normal group and PET Phantom was assembled by ACR PET Phantom Instructions and it's actual ratio between hot spheres and background was 2.35 to 1. Brain and Phantom images were acquired after 3 hours from the time of the injection and images were acquired for ten minutes. Basically, SIEMENS Bio graph 40 True-point was used and True-X method was applied for image reconstruction method. The iteration and Subset were set to 2 iterations, 8 subsets, 3 iterations, 16 subsets, 6 iterations, 16 subsets, 8 iterations, 16 subsets and 8 iterations, 21 subsets respectively. To measure SUVs on the brain images, ROIs were drawn on the right Putamen. Also, Coefficient of variance (CV) was calculated to indicate the uniformity at each iteration and subset combinations. On the phantom study, we measured the actual ratio between hot spheres and back ground at each combinations. Same size's ROIs were drawn on the same slide and location. Results: Mean SUVs were 10.60, 12.83, 13.87, 13.98 and 13.5 at each combination. The range of fluctuation by sets were 22.36%, 10.34%, 1.1%, and 4.8% respectively. The range of fluctuation of mean SUV was lowest between 6 iterations 16 subsets and 8 iterations 16 subsets. CV showed 9.07%, 11.46%, 13.56%, 14.91% and 19.47% respectively. This means that the numerical value of the iteration and subset gets higher the image's uniformity gets worse. The range of fluctuation of CV by sets were 2.39, 2.1, 1.35, and 4.56. The range of fluctuation of uniformity was lowest between 6 iterations, 16 subsets and 8 iterations, 16 subsets. In the contrast test, it showed 1.92:1, 2.12:1, 2.10:1, 2.13:1 and 2.11:1 at each iteration and subset combinations. A Setting of 8 iterations and 16 subsets reappeared most close ratio between hot spheres and background. Conclusion: Findings on this study, SUVs and uniformity might be calculated differently caused by variable reconstruction parameters like filter or FWHM. Mean SUV and uniformity showed the lowest range of fluctuation at 6 iterations 16 subsets and 8 iterations 16 subsets. Also, 8 iterations 16 subsets showed the nearest hot sphere to background ratio compared with others. But it can not be concluded that only 6 iterations 16 subsets and 8 iterations 16 subsets can make right images for the clinical diagnosis. There might be more factors that can make better images. For more exact clinical diagnosis through the quantitative analysis of DAT density in the region of striatum we need to secure healthy people's quantitative values.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.13-17
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• 2010

Purpose: Partial volume effect (PVE) is the phenomenon to lower the accuracy of image due to low estimate, which is to occur from PET/CT 3D image acquisition. The more resolution is declined and the lesion is small, the more it causes a big error. So that it can influence the test result. Studied the optimum image reconstruction method by using variation of parameter, which can influence the PVE. Materials and Methods: It acquires the image in each size spheres which is injected $^{18}F$-FDG to hot site and background in the ratio 4:1 for 10 minutes by using NEMA 2001 IEC phantom in GE Discovey STE 16. The iterative reconstruction is used and gives variety to iteration 2-50 times, subset number 1-56. The analysis's fixed region of interest in detail part of image and compute % difference and signal to noise ratio (SNR) using $SUV_{max}$. Results: It's measured that $SUV_{max}$ of 10 mm spheres, which is changed subset number to 2, 5, 8, 20, 56 in fixed iteration to times, SNR is indicated 0.19, 0.30, 0.40, 0.48, 0.45. As well as each sphere's of total SNR is measured 2.73, 3.38, 3.64, 3.63, 3.38. Conclusion: In iteration 6th to 20th, it indicates similar value in % difference and SNR ($3.47{\pm}0.09$). Over 20th, it increases the phenomenon, which is placed low value on $SUV_{max}$ through the influence of noise. In addition, the identical iteration, it indicates that SNR is high value in 8th to 20th in variation of subset number. Therefore, to reduce partial volume effect of small lesion, it can be declined the partial volume effect in iteration 6 times, subset number 8~20 times, considering reconstruction time.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.1
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• pp.20-24
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• 2009

Objective: In this study, the differences between two reconstruction methods were analyzed by comparing image uniformity and contrast according to Iteration and Subset, which were altered through the Iterative method and True X method, used in Siemens' PET/CT studies. Methods: The Phantom images were obtained by exposure for two minutes per one bed. To determine the image uniformity, the Coefficient of variance was used. Also, in order to compare the contrast value, we measured and analyzed the ratio of the SUV mean of Phantom image's hot spheres and the background. Results: Under the same reconstruction conditions (Iteration and Subset) of CV, the Iterative method was higher than the True X method. In the comparison of the SUV mean ratio of the background and hot sphere, the True X method had a closer rate than the Iterative method. Conclusion: The newly developed True X reconstruction method is better than the previously used Iterative method in terms of uniformity and contrast. However, the date for this study was only obtained using the Phantom device. In order to obtain more accurate and useful information from the experiment, further research should be conducted. Also, it is necessary to find the appropriate standards for Iteration and Subset for further experimentation.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.2
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• pp.31-36
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• 2017

Purpose Recently, the performance of PET/CT scanner has been improved and various techniques have been developed to increase the image quality such as Sensitivity and Resolution. The purpose of this study is to evaluate the usefulness of Q.Clear (a fully convergent iterative reconstruction) technique of GE Discovery IQ equipment to enhance the image quality. Materials and Methods All scans were acquired by Discovery IQ (GE Healthcare, MI, USA). In NEMA IEC Body Phantom test, Background to Hot-sphere (10 mm, 13 mm, 17 mm, 22 mm) ratio was 1:4 and scan time was 3 minutes. The images were reconstructed by VPHDs (VUE Point High-Definition + SharpIR) and Q.Clear to evaluate each Contrast. We injected 18F-FDG 187 M㏃ to PET/SPECT Performance Phantom. And then it was scanned for 4 minutes to evaluate Resolution and Uniformity. T-test statistical analysis was performed on SUVmax of small lesions less than 2 cm in 100 clinical patients regardless of disease type. Results In the NEMA IEC Body Phantom, the Contrast was $63.6{\pm}5.7%$ (VPHDs) and $75{\pm}4.8%$ (Q.Clear). In the PET/SPECT Performance Phantom, the Resolution was 9.2 mm (VPHDs) and 7.3 mm (Q.Clear). Uniformity of Q.Clear was 10.8% better than VPHDs. T-test statistic of the clinical patients showed a significant difference of p value of 0.021. Conclusion Both the phantom test and the clinical results showed that the quality of the image was improved in Q.Clear was applied. The SUVmax was highly measured in Q.Clear and the lesions were clearly distinguished visually. Therefore Q.Clear can be useful in various aspects such as dose-reduction, patients evaluation and image analysis.

• Journal of Sericultural and Entomological Science
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• v.41 no.1
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• pp.20-28
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• 1999

Color qualities investigated on the basis of Munsell code and Korean standard color code for the cocoons from various strain of mulberry silkworm, Bombyx mori. 16 of different color qualities were identified from 21 of original silworm strains, and determinated international name with the revision of Korean color name for cocoon. The various cocoon color confirmed on the sphere from 567 to 593 nm wavelength, 78% of those located at the region about 580 nm (575~584) of sensitive "color difference limen". Y gene engaged broad ranges of wavelength (575~593 nm) in the color expression, by contrast with other genes of Pk (593 nm), F (584~593), Grc and relative G group (567~570 nm), on the transmission of carotenoid or flavonoid color substance. YC gene expression by original silk worm strain was also distinguished by those variation of specific yellow than other colors from Grc, GaGb, Gc, and YPkF. Appearance of chrome yellow cocoon was dominant than other yellow in the cross among vivid yellow group. F1 of pin${\times}$green produced the cocoon of yellow such as "additive mixture" as color light, however, most of the hybrid between yellow cocoon showed the color similar to "subtractive mixture" as a mixture of dyestuff. Hybrid cocoons among yellow or green colors were decreased their hue, value, and chroma, than those of parent. Diallel cross among the strain of various green cocoon suggest the existence of Grc, Ga, Gb, Gc genes. Cream colored cocoon of B. mandarina was differed from other yellow cocoon of Bobyx mori B. mori. Y$^A$ with Ymc showed the similar role of Y with C, therefore, segregated yellow cocoon from the B. mori${\times}$B. mandarina (+$^YC/Y^AYmc$). YC expression of $Y^AY$mc genes might be suppressed by deficiency of outer layer sericin on the middle division of silk giand in the B. mandarina.

• Journal of the Korean Geographical Society
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• v.29 no.3
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• pp.297-317
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• 1994

This study demonstrates the changes in the spatial organization of Korea by the construction of Seoul-Pusan railroad. This Seoul-Pusan line, which is the most important one in Korea was constructed in 1905. The original plan of the line was selected to cross the main traditional roads to control the entire Korean peninsular and to mobilize the Korean commercial potentials. It was the line to exploit the staples and to expand the Japanese market in Korea. In accordance with the contracts between Japan and Korean government, Korean government had to supply the lands for railroad, office, and service facilities. That was one of the important reasons that Korean government had been broken down. The main findings of this study are as follows: 1. The Seoul-Pusan railroad line was constructed Japanese colonial policy which emphasized three main purposes; the first was to reorganize the economic space and to collapse the traditional Korean markets for Japanese ruling, and the second was to find out the military supply routes, and the third was to search for the transcontinental line for China and Siberia. As the results, the old Korean pedestrian routes, which were the Eastern, the mid, the westren, and the Samnam route lost their functions. 2. Japanese requested for Korean government usually ten times of wider space for the site of stations than the needed one. The land was expropriated, and constructed the new centers aparted from the original Korean towns. In this process Japanese got the most developmental and windfall profits. The newly constructed centers were for Japanese immigration and the town service facilities which would be used to control the Korean financial market. At last, they easily converted the Korean spatial economy into Japanese colonial one, which made to reinforce the sphere of Seoul-Pusan line. 3. Japanese planned the stations as the central points in Korea. So the railroad stations were located apart from the centers of towns, to avoid the Korean resistances, and to maximize their profits. The mean distance from staiton to 'the town center is about 1km while the Japanese case is 0.6km. 4. The pattern of present Korean railroads is not the 'X type'. Because the Honam line is not the trunk one. So, we could call the Korean railroad pattern as the 'Ip(Chinese character 入) type' . The operational effects of Seoul-Pusan line brought out the concentration of the national economy to this line as Japanese planned. And the polorization had occurred between this line and the other parts of Korea. For twenty years (1910-1930), the transported freights were increased about 5 times. In 1930, the total freight of Seoul-Pusan line became 2, 010, 444 metric tons. If we examine this process, the underconstructing Seoul-Pusan express electric railroad should avoid adjacent this line to reduce the regional and ecological imbalance. 5. The forms of centers on the Seoul-Pusan line were classified into six types in relation to station, town center, and built-up area; the compact (integrated) type, the elongated one, the splited (independent) one, the absorbed one, the consolidated one, and the declined one. All types of these towns might be developed in accordance with the centrality, railroad function, and the other transportational functions. 6. The Seoul-Pusan line plays the most important role among Korean railroads but the ratio of passenger and freight become lower because the effiects of other inaugurated railoads the different transportation modes such as trucks and cars would be got more merits in competition. 7. The results of cluster analyses on the cities of railroad stations showed the rudimentary urban systems in 1910 and 1930. In 1930, the cities were classified into three groups; the group of small cites, the intermediate (developing) city-group, and the special city-group. In 1930s the spatial organization and urban system of Korea were similar to the present ones. We call appreciate that these were the effects of the Seoul-Pusan line.

• Journal of Korean Society for Atmospheric Environment
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• v.10 no.E
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• pp.332-342
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• 1994

Hierarchical cluster and factor analyses were used to identify various influences on free tropospheric air samples at Mauna Loa Observatory in Hawaii during MLOPEX. The cluster analysis separated thirteen chemical and meteorological variables into three characteristic groups (1)clean air, (2)anthropogenically influenced air, (3)marine and volcanic influenced air. The cluster analysis results compared well with those of factor analysis. Six independent components were identified in factor analysis. We have related these components to (1)volcano influenced air, (2)stratosphere-like air, (3)boundary-layer air with recent anthropogenic influence, (4)photochemical haze, (5)marine boundary- layer air, and (6)modified marine tropospheric air. Excluding local influence, we could calculate the nighttime free tropospheric values for $O_3$(41$\pm$10 ppbv), HN $O_3$(94$\pm$45 pptv), N $O_3$$^{[-10]}$ (16$\pm$10 ppbv), S $O_4$$^{[-10]}$ (60$\pm$0 pptv), N $H_4$$^{＋}$(71$\pm$6 pptv), N $a^{＋}$(5$\pm$1 pptv), PAN(13$\pm$9 pptv), MeN $O_3$(3.5$\pm$1.5 pptv), 2-butyl N $O_3$(0.6$\pm$0.1 pptv), $H_2O$$_2$(1015$\pm$44 pptv), $C_2$C $l_4$(3.3$\pm$0.1 pptv), condensation nuclei(249$\pm$13c $m^{-3}$), and dew point(-8.5$\pm$5.3$^{\circ}C$) during this experiment..

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.10 no.6
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• pp.15-26
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• 2015

The purpose of this study was to examine the area, theme and method of domestic articles on the successful establishment of venture companies, which were presented between 1998 and 2014, according to related basic classification criteria in an effort to shed light on the characteristics of these studies. It's basically meant to make a contribution to the development of research on the success of venture business and to be of practical use for the success of venture companies in our country. After related earlier studies were analyzed, 164 articles were collected, and 64 articles were selected from among them. The articles that were overlapped, not presented or not registered were excluded. The related studies had been conducted by different learned societies that were interested in the same research themes, and the studies were primarily led by the Korean Society of Business Venturing as of 2014, especially by Asia-Pacific Journal of Business Venturing and Entrepreneurship that was a journal published by this society. This society seemed to have taken the initiative in this field. There was a tendency that the related studies increased in number due to the shifts of modern industrial society and the changing policies of the government, as the number of the studies has been on the steady rise since 2012. In terms of method, quantitative research methods, especially descriptive studies, were prevailing. To step up the development of research into this field, a wide variety of research methods should be utilized in the future. As for the sphere of research, the characteristics of founders, strategic characteristics and environmental characteristics were mainly covered as the success factors of venture business. More diverse variables should be explored as well to make more advanced, extended research in the years to come. The findings of the study are expected to provide both theoretical and practical information on the establishment and success of venture business to make a contribution to the development of research.

• Progress in Medical Physics
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• v.16 no.1
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• pp.24-31
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• 2005

The stereotactic radiosurgery (SRS) describes a method of delivering a high dose of radiation to a small tar-get volume in the brain, generally in a single fraction, while the dose delivered to the surrounding normal tissue should be minimized. To perform automatic plan of the SRS, a new method of multi-isocenter/shot linear accelerator (linac) and gamma knife (GK) radiosurgery treatment plan was developed, based on a physical lattice structure in target. The optimal radiosurgical plan had been constructed by many beam parameters in a linear accelerator or gamma knife-based radiation therapy. In this work, an isocenter/shot was modeled as a sphere, which is equal to the circular collimator/helmet hole size because the dimension of the 50% isodose level in the dose profile is similar to its size. In a computer-aided system, it accomplished first an automatic arrangement of multi-isocenter/shot considering two parameters such as positions and collimator/helmet sizes for each isocenter/shot. Simultaneously, an irregularly shaped target was approximated by cubic structures through computation of voxel units. The treatment planning method by the technique was evaluated as a dose distribution by dose volume histograms, dose conformity, and dose homogeneity to targets. For irregularly shaped targets, the new method performed optimal multi-isocenter packing, and it only took a few seconds in a computer-aided system. The targets were included in a more than 50% isodose curve. The dose conformity was ordinarily acceptable levels and the dose homogeneity was always less than 2.0, satisfying for various targets referred to Radiation Therapy Oncology Group (RTOG) SRS criteria. In conclusion, this approach by physical lattice structure could be a useful radiosurgical plan without restrictions in the various tumor shapes and the different modality techniques such as linac and GK for SRS.

• Progress in Medical Physics
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• v.22 no.1
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• pp.35-41
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• 2011

For overall system test, hidden-target test have been used using film which leads to inherent analysis error. The purpose of our study is to quantify this error and to propose gel dosimeter based verification technique for 3-dimensional target point error. The phantom was made for simulation of human head and this has ability to equip 10 gel-dosimeter. $BANGkit^{TM}$ which we are able to manufacture whenever it is needed as well as to easily change the container with different shapes was used as a gel dosimeter. The 10 targets were divided into two groups based on shapes of areas with a planned 50% isodose line. All treatment and analysis was performed three times using Novalis and $BrainSCAN^{TM}$. The target point error is $0.77{\pm}0.15mm$ for 10 targets and directional target point error in each direction is $0.54{\pm}0.23mm$, $0.37{\pm}0.08mm$, $0.33{\pm}0.10mm$ in AP (anterior-posterior), LAT (lateral), and VERT (vertical) direction, respectively. The result of less than 1 mm shows that the treatment was performed through each precise step in treatment procedure. In conclusion, the 3-dimensional target point verification technique can be one of the techniques for overall system test.