• Journal of the Korean Society of Radiology
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• v.17 no.4
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• pp.489-495
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• 2023

Radiation shielding facilities are constructed in locations where diagnostic radiation generators are installed, with the aim of preventing exposure for patients and radiation workers. The purpose of this study is seek to compare and validate the trend of attenuation thickness of lead, the primary material in these radiation shielding facilities, at different maximum tube voltages by Monte Carlo simulations and measurement. We employed the Monte Carlo N-Particle 6 simulation code. Within this simulation, we set a lead shielding arrangement, where the distance between the source and the lead sheet was set at 100 cm and the field of view was set at 10 × 10 cm². Additionally, we varied the tube voltages to encompass 80, 100, 120, and 140 kVp. We calculated energy spectra for each respective tube voltage and applied them in the simulations. Lead thicknesses corresponding to attenuation rates of 50, 70, 90, and 95% were determined for tube voltages of 80, 100, 120, and 140 kVp. For 80 kVp, the calculated thicknesses for these attenuation rates were 0.03, 0.08, 0.21, and 0.33 mm, respectively. For 100 kVp, the values were 0.05, 0.12, 0.30, and 0.50 mm. Similarly, for 120 kVp, they were 0.06, 0.14, 0.38, and 0.56 mm. Lastly, at 140 kVp, the corresponding thicknesses were 0.08, 0.16, 0.42, and 0.61 mm. Measurements were conducted to validate the calculated lead thicknesses. The radiation generator employed was the GE Healthcare Discovery XR 656, and the dosimeter used was the IBA MagicMax. The experimental results showed that at 80 kVp, the attenuation rates for different thicknesses were 43.56, 70.33, 89.85, and 93.05%, respectively. Similarly, at 100 kVp, the rates were 52.49, 72.26, 86.31, and 92.17%. For 120 kVp, the attenuation rates were 48.26, 71.18, 87.30, and 91.56%. Lastly, at 140 kVp, they were measured 50.45, 68.75, 89.95, and 91.65%. Upon comparing the simulation and experimental results, it was confirmed that the differences between the two values were within an average of approximately 3%. These research findings serve to validate the reliability of Monte Carlo simulations and could be employed as fundamental data for future radiation shielding facility construction.

• Investigative Magnetic Resonance Imaging
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• v.6 no.1
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• pp.64-72
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• 2002

Purpose : To introduce and demonstrate the advantages of the new hybrid two-dimensional (2D) proton spectroscopic imaging (SI) over the single voxel spectroscopy (SVS) and conventional 2D SI in the clinical application of spectroscopy for pediatric cerebral disease. Materials and Methods : Eighty-one hybrid 2D proton spectroscopic imaging was performed in 79 children (36 normal infants and children, 10 with hypoxic-ischemic injury, 20 with toxic-metabolic encephalopathy, seven with brain tumor, three with meningoencephalitis, one with neurofibromatosis, one with Sturge-Weber syndrome and one with lissencephaly) ranging in age from the third day of life to 15 years. In adult volunteers (n=5), all three techniques including hybrid 2D proton SI, SVS using PRESS sequence, and conventional 2D proton SI were performed. Both hybrid 2D proton SI and SVS using PRESS sequence were performed in clinical cases (n=). All measurements were performed with a 1.5-T scanner using standard head quadrature coil. The 16$\times$16 phase encoding steps were set on variable field of view (FOV) depending on the size of the brain. The hybrid volume of interest inside FOV was set as $75{\times}75{\times}15{\;}\textrm{mm}^3$ or smaller to get rid of unwanted fat signal. Point-resolved spectroscopy (TR/TE=1,500 msec/135 or 270msec) was employed with standard chemical shift selective saturation (CHESSI pulses for water suppression. The acquisition time and spectral quality of hybrid 2D proton SI were compared with those of SVS and conventional 2D proton SI. Results : The hybrid 2D proton SI was successfully conducted upon all patients.

• The Korean Journal of Nuclear Medicine
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• v.38 no.5
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• pp.338-343
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• 2004

Purpose: The purpose of this study was to develop a small animal PET using dual layer phoswich detector to minimize parallax error that degrades spatial resolution at the outer part of field-of-view (FOV). Materials and Methods: A simulation tool GATE (Geant4 Application for Tomographic Emission) was used to derive optimal parameters of small PET, and PET was developed employing the parameters. Lutetium Oxyorthosilicate (LSO) and Lutetium-Yttrium Aluminate-Perovskite(LuYAP) was used to construct dual layer phoswitch crystal. $8{\times}8$ arrays of LSO and LuYAP pixels, $2mm{\times}2mm{\times}8mm$ in size, were coupled to a 64-channel position sensitive photomultiplier tube. The system consisted of 16 detector modules arranged to one ring configuration (ring inner diameter 10 cm, FOV of 8 cm). The data from phoswich detector modules were fed into an ADC board in the data acquisition and preprocessing PC via sockets, decoder block, FPGA board, and bus board. These were linked to the master PC that stored the events data on hard disk. Results: In a preliminary test of the system, reconstructed images were obtained by using a pair of detectors and sensitivity and spatial resolution were measured. Spatial resolution was 2.3 mm FWHM and sensitivity was 10.9 $cps/{\mu}Ci$ at the center of FOV. Conclusion: The radioactivity distribution patterns were accurately represented in sinograms and images obtained by PET with a pair of detectors. These preliminary results indicate that it is promising to develop a high performance small animal PET.

• Korean Journal of Digital Imaging in Medicine
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• v.16 no.1
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• pp.13-19
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• 2014

Purpose: FLAIR image is beneficial for the diagnosis of various bran diseases including ischemic CVS, brain tumors and infections. However the border between the legion of brain metastasis and surrounding edema may not be clear. Therefore, this study aims to investigate the practical benefits of delayed imaging by comparing the image from a patient with brain metastasis before a contrast enhancement and the image 10 minutes after a contrast enhancement. Materials and methods: Of the 92 people who underwent MRI brain metastases in suspected patients 13 people in three patients there is no video to target the 37 people confirmed cases, and motion artifacts brain metastases in our hospital June-December 2013, 18 people measurement position except for the three incorrect patient (male: 11 people, female: 7 people, average age: 60 years) in the target, test equipment, 3.0T MR System (ACHIEVA Release, Philips, I was 8ChannelSENSE Head Coil use Best, and the Netherlands). TR 11000 ms, TE 125 ms, TI2800 ms, Slice Thickness 5 mm, gap 5 mm, is a Slice number 21, the parameters of the 3D FFE, T2 FLAIR variable that was used to test, TR 8.1 ms, TE 3.7 ms, Slice number 240 I set to. The experiment was conducted by acquiring the FLAIR prior to contrast enhancement (heretofore referred to as Pre FLAIR), and acquiring the 3D FFE CE five minutes after the contrast enhancement, and recomposing the images in an axial plane of S/T 3mm, G 0mm (heretofore referred to as MPR TRA CE). Using the FLAIR 10 minutes after the contrast enhancement (heretofore referred to as Post FLAIR) and Pi-View, a retrospective study was conducted. Using MRIcro on the image of a patient confirmed for his diagnosis, the images before and after the contrast media, as well as the CNR and SNR of the MPR TRA CE images of the lesion and the site absent of lesion were compared and analyzed using a one-way analysis of variance. Results: CNR for Pre FLAIR and Post FLAIR were 34.35 and 60.13, respectively, with MPR TRA CE at 23.77 showing no significant difference (p<0.050). Post-experiment analysis shows a difference between Pre FLAIR and Post FLAIR in terms of CNR (p<0.050), but no difference in CNR between Post FLAIR and MPR TRA CE (p>0.050), indicating that the contrast media had an effect only on Pre FLAIR and Post FLAIR. The SNR for the normal site Pre FLAIR was 106.43, and for the lesion site 140.79. Post FLAIR for the normal site was 107.79, and for the lesion site 167.91. MPR TRA CE for the normal site was 140.23 and for the lesion site 183.19, showing significant difference (p<0.050), and post-experiment analysis shows that there was a difference in SNR only on the lesion sites for Pre FLAIR and Post FLAIR (p<0.050). There was no difference in SNR between the normal site and lesion site for Post FLAIR and MPR TRA CE, indicating no effect from the contrast media (p>0.050). Conclusions: This experiment shows that Post FLAIR has a higher contrast than Pre FLAIR, and a higher SNR for lesions, It was not not statistically significant and MPR TRA CE but CNR came out high. Inspection of post-contrast which is used in a high magnetic field is frequently used images of 3D T1 but, since the signal of the contrast medium and the blood flow is included, this method can be diagnostic accuracy is reduced, it is believed that when used in combination with Post FLAIR, and that can provide video information added to the diagnosis of brain metastases.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.1
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• pp.105-116
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• 2017

Murals in villages revitalize communities and spaces, and are economically efficient. Central and local governments are therefore actively undertaking Mural Village Projects but there are some issues and concerns about the projects for the provision of uniformed landscapes for the regions that are the result of a short-term completion of projects, and instead of cohesion, cause destruction of place identities. In addition, the problem of sustainable landscape management that is the result of low community involvement can be pointed out because the murals are products of government-led projects. The study covered the context of landscape and space change processes from a critical perspective, and focused on Ihwa-dong Mural Village, which is considered the first mural village in Korea and has begun to undergo drastic changes due to attention received from media. The purposes of this study are as follows. First, the study provides data about difference of place identity perception and landscape preference between residents and tourists in Ihwa-dong Mural Village. Second, this paper evaluates the current Mural Village Projects and finds alternative directions to improve the projects by using these data. This paper analyzed tourist hot spots in Ihwa-dong Mural Village by using SNS analysis, a field study and focus group interviews. The difference of place identity perception and landscape preference was examined among three groups: residents, new residents who are invited by Mural Village Projects, and tourists. This study showed that many tourists are focused on landscape areas that were not intentionally constructed projects. In addition, the locations of preferred landscapes and stores overlapped. Meanwhile, using qualitative data analysis, it was found that residents perceived the area as being an under-privileged location, while the murals, a non-daily landscape, largely affected place identity perception of new residents and tourists. For landscape preference, tourists preferred outdoor rest areas, while new residents and residents preferred less. Additionally, new residents and tourists preferred an area's night view while residents made no mention of this. Related to the direction of the projects, three groups showed their dependence on the government. This empirical study is significant from a participatory design perspective and in analyzing the issues for mural villages' landscapes, which are spreading across the nation and proceeding without criticism in urban regeneration. Implications for urban planners and suggestions for the future projects are given.

• Journal of Radiation Protection and Research
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• v.40 no.1
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• pp.1-9
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• 2015

Compton cameras overcome several limitations of conventional mechanical collimation based gamma imaging devices, such as pin-hole imaging devices, due to its electronic collimation based on coincidence logic. Especially large-scale Compton camera has wide field of view and high imaging sensitivity. Those merits suggest that a large-scale Compton camera might be applicable to monitoring nuclear materials in large facilities without necessity of portability. To that end, our research group have made an effort to design a large-scale Compton camera for safeguard application. Energy resolution or position resolution of large-area detectors vary with configuration style of the detectors. Those performances directly affect the image quality of the large-scale Compton camera. In the present study, a series of Geant4 Monte Carlo simulations were performed in order to examine the effect of those detector parameters. Performance of the designed large-scale Compton camera was also estimated for various monitoring condition with realistic modeling. The conclusion of the present study indicates that the energy resolution of the component detector is the limiting factor of imaging resolution rather than the position resolution. Also, the designed large-scale Compton camera provides the 16.3 cm image resolution in full width at half maximum (angular resolution: $9.26^{\circ}$) for the depleted uranium source considered in this study located at the 1 m from the system when the component detectors have 10% energy resolution and 7 mm position resolution.

• Korean Journal of Environment and Ecology
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• v.24 no.4
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• pp.395-405
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• 2010

This study was carried out to offer basic data to minimize the indiscreet development and damage of coastal wetlands through an evaluation from an ecological standpoint highlighting the importance of the coastal wetland in South Gyeongsang Province, Korea. The result of the macrobenthos survey for the coastal wetland assessment showed that Dongdal and Hwasan-ri, Yongnam-myeon, and Tongyeong city had the largest species number; Oegan-ri and Naegan-ri, Geoje-myeon, and Geoje city had the largest population and biomass; and Miryong-ri, Samsan-myeon, Goseong-gun had the highest species diversity. In the halophytes survey, Imyeong-ri, Jinjeon-myeon, Masan city and Oegan-ri and Naegan-ri, Geoje-myeon, Geoje city had the large character species and companion species. The evaluation results of the ecological values of the coastal wetlands were categorized into five grades based on the field surveys, and the sedimentary environment factor in the case of Danghang-ri, Hoehwa-myeon, and Goseong-gun; Miryong-ri, Samsan-myeon, Goseong-gun; Guho-ri, Gonyang-myeon, Sacheon city; Sulsang-ri Yangpo-ri, Jingyo-myeon, Hadong-gun; and Seokpyeong-ri, Idong-myeon, Namhae-gun, were appraised at the highest rating of grade II. The halophytes factor in the case of Imyeong-ri, Jinjeon-myeon, Masan city, Dongdal-ri and Hwasan-ri, Yongnam-myeon, Tongyeong city and Oegan-ri and Naegan-ri, Geoje-myeon, Geoje city, were highly evaluated as grade II. The macrobenthos factor in the case of Imyeong-ri, Jinjeon-myeon, Masan city and Oegan-ri and Naegan-ri, Geoje-myeon, Geoje city was highly evaluated as grade II. The final evaluation grade was calculated by the mean values of three evaluation factors, and Imyeong-ri, Jinjeon-myeon, Masan city and Oegan-ri and Naegan-ri, Geoje-myeon, and Geoje city had the highest rating of II. On the other hand, Seokpyeong-ri, Idong-myeon, Namhae-gun had the lowest rating of IV. These locations will require future research to survey and monitor the coastal wetland ecosystems by season, in addition to the construction of the GIS-based wetland information system with a view to manage the coastal wetlands.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.3
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• pp.265-272
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• 2002

Spatial distribution of Phytoplankton Pigment Concentration (PPC) and Sea Surface Temperature (SST) around the East Korean Warm Current (EKWC) was described, using both Coastal Zone Color Scanner (CZCS) images and Advanced Very High Resolution Radiometer (AVHRR) images in May, 1980. Water mass in this region can be classified into five categories in the horizontal profile of PPC and SST, nLw (normalized water-leaving radiance) images: (1) coastal cold water region associated with concentrations of dissolved organic material or yellow colored substances and suspended sediments, (2) cold water region of thermal frontal occurred by a combination of phytoplankton absorption and suspended materials, (3) warm water overlay region by the phytoplankton absorption than the suspended materials; (4) warm water region occurred by the low phytoplankton absorption, and (5) offshore region occurred by the high phytoplankton absorption. In particular, the highest PPC (>2.0 mg/m^3) area appeared in the CZCS and AVHRR images with a band shaped distribution of the thermal front and ocean color front region, which is located the coastal cold waters alonB western thermal front of the warm streamer of the EKWC. In this region, the highest PPC occurred by a combination of the high absorption of the phytoplankton (443 nm) and highest reflectance of suspended materials (550 nm). Another high PPC ($\simeq$$6\;mg/m^3$) appeared in the warm water overlay region inside warm streamer. High phytoplankton pigment concentration of this region was corresponding to the short wavelength of 443 nm, which represented phytoplankton absorption of the CZCS image.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.4
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• pp.104-117
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• 2017

This study compares the results of landscape image analysis using text mining techniques and factor analysis for Lotte World Tower, which is the first atypical skyscraper building in Korea, and identifies landscape images of the site to determine possibilities of use. Lotte World Tower's landscape image has been extracted from text mining analysis focusing on adjectives such as 'new', 'transformational', 'unusual', 'novelty', 'impressive', and 'unique', and phrases such as in the process of change, people's active elements(caliber, outing, project, night view), media(newspaper, blog), and climate(weather, season). As a result of the factor analysis, factors affecting the landscape image of Lotte World Tower were symbolic, aesthetic, and formative. Identification, which is a morphological feature, has characteristics of scale and visibility but it is not statistically significant in preference. Rather, the psychological factors such as the symbolism with characteristics such as poison and specialty, harmony with the characteristics of the surrounding environment, and beautiful aesthetic characteristics were an influence on the landscape image. The common results of the two research methods show that psychological characteristics such as factors that can represent and represent the city affect the landscape image more greatly than the morphological and physical characteristics such as location and location of the building. In addition, the text mining technique can identify nouns and adjectives corresponding to the images that people see and feel, and confirms the relationship between the derived keywords, so that it can focus the process of forming the landscape image and further the image of the city. It would appear to be a suitable method to complement the limitation of landscape research. This study is meaningful in that it confirms the possibility that big data can be utilized in landscape analysis, which is one research field of landscape architecture, and is significant for understanding the information of a big data base and contribute to enlarging the landscape research area.

• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.2
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• pp.71-78
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• 1987

This experiment was carried out to examine the effects of sowing method and summer management on the dry matter yield, dead matter, weed development and ground cover of orchardgrass (Dactylis glomerata L.) meadow. The experiment was allocated as a split-split plot design with three replications. The main plots were sowing method of drilling and broadcasting, sub plots were drainage of experimental field, adequate and inadequate, and sub-sub plots were cutting timeof orchardgrass, cutting before rainy season started and cutting after rainy season ended. The experiment was undertaken over a period of 14 months from September, 1983 to October, 1984. The results obtained are summarized as follows: 1. There were no significant differences in dry matter yield among treatments at the first cutting, but cutting before rainy season produced significantly more forage yield ($P{\le}0.01$) than cutting after rainy season at the second and third cuts. At the third cutting, drilled orchardgrass meadow showed a significant dry matter yield ($P{\le}0.05$) than broadcast orchardgrass meadow, 2. The dead matter of orchardgrass was accumulated only at the second cutting when orchardgrass meadow cut after rainy season. Orchardgrass produced in the adequate and inadequate drainage plots consisted 20.4 and 35.9% of dead material, respectively, but no significant difference was found between two drainage treatments. 3. Drilled orchardgrass meadow produced significantly less weeds ($P{\le}0.05$) than broadcast orchardgrass meadow, but the plots cut after rainy season produced significantly more weeds ($P{\le}0.01$) than the plots cut before rainy season. 4. The percent ground cover of orchardgrass in the plots cut before rainy season was significantly higher ($P{\le}0.01$) than that in the plots cut after rainy season at the second cutting. Drilled plots showed a slight increase in the ground cover than the broadcast, but the difference was not significant. The same trend of ground cover of the meadow estimated at the second cutting was sustained after the third cutting. 5. Based on the results of the experiment, it indicates that the second cut of orchardgrass should be made before rainy season related for maintaining high yield of the meadow. Drilling as a sowing method of orchardgrass meadow could be adopted in the view point of reducing weed development.