• The Korean Journal of Nuclear Medicine
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• v.33 no.3
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• pp.316-326
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• 1999

Purpose: We evaluated the feasibility of extracting pure left ventricular blood pool and myocardial time-activity curves (TACs) and of generating factor images from human dynamic N-13 ammonia PET using factor analysis. The myocardial blood flow (MBF) estimates obtained with factor analysis were compared with those obtained with the user drawn region-of-interest (ROI) method. Materials and Methods: Stress and rest N-13 ammonia cardiac PET imaging was acquired for 23 min in 5 patients with coronary artery disease using GE Advance tomograph. Factor analysis generated physiological TACs and factor images using the normalized TACs from each dixel. Four steps were involved in this algorithm: (a) data preprocessing; (b) principal component analysis; (c) oblique rotation with positivity constraints; (d) factor image computation. Area under curves and MBF estimated using the two compartment N-13 ammonia model were used to validate the accuracy of the factor analysis generated physiological TACs. The MBF estimated by factor analysis was compared to the values estimated by using the ROI method. Results: MBF values obtained by factor analysis were linearly correlated with MBF obtained by the ROI method (slope = 0.84, r = 0.91), Left ventricular blood pool TACs obtained by the two methods agreed well (Area under curve ratio: 1.02 ($0{\sim}1min$), 0.98 ($0{\sim}2min$), 0.86 ($1{\sim}2min$)). Conclusion: The results of this study demonstrates that MBF can be measured accurately and noninvasively with dynamic N-13 ammonia PET imaging and factor analysis. This method is simple and accurate, and can measure MBF without blood sampling, ROI definition or spillover correction.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.1
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• pp.51-56
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• 2015

Purpose As medical radiation exposures on patients are being social issues an interest in a relief of radiation exposures on patients is increasing. Further, there are many cases where some patients among who are getting PET/CT tests choose to get implanted with metal artifacts in their bodies. This study is to find out effects of presence or absence of metal artifacts when dose change or CT attenuation correction for the relief of radiation exposures are applied using phantoms through changes in standard uptake value (SUV). Materials and Methods GE company's Discovery 710 machine was used for PET/CT test equipments. We used NEMA IEC body phantoms. We also used screw and mesh cage made of titanium which are used in real clinical processes for the metal artifacts. Two experiments were conducted: One is to test and measure repeatedly about SUV about differences in CT attenuation corrections according to dose changes and another is to do the same procedure for SUV about the presence and absence of the metal artifacts. We injected $^{18}F-FDG$ into NEMA IEC body phantoms with a TBR ratio of 4:1 and then put the metal material into the transformation phantoms. Once a scanning for the metal artifacts was done we eliminated the metal artifacts and went on non-metal artifacts. For the each two experiments, we scanned repeatedly with CT kVp (140, 120, 100, 80) and mA (120, 80, 40, 20, 10) for an experimental condition. For PET, we reconstructed each with standard AC (STD) technique and quantitation achieved cnsistently QAC) technique among CT attenuation correction methods. We conducted a comparative analysis on measured average values and variations which were measured through repeated measure of SUV of region 1, 2, 3 spheres for each conditions of non-metal /metal scan. Results For each kVp, 120, 80, 40 (mA) of non/metal (screw, mesh cage) showed low frequency of fluctuation rates of above 2%. In 20, 10 mA above 2% of fluctuation rates appeared in high frequency. Also, when we compared the fluctuation rates of STD and QAC techniques in non/metal (screw, mesh cage) tests QAC technique showed about 1-10% of differences for each conditions compared to STD technique. In addition, metal types did not have significant effects on fluctuation rates. Conclusion We confirmed that SUV fluctuation rates for both STD and QAC techniques increase as dosage is lower. We also found that the SUV of PET data was maintained steadily in a low dosage for QAC technique when compared with STD technique. Hence, when the low dosage is used for the relief of radiation exposures on patients QAC technique may be exploited helpfully and this could be applied in the same way for patients with metal artifacts implanted in their bodies.

• Cross-Cultural Studies
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• v.41
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• pp.351-379
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• 2015

In the Andes regions of Latin America continents, groups of diverse native tribes are intensively distributed.Among these tribes, the Aymara compose the most representative group of natives along with the Quechua. Especially, the Aymara who are concentrated on the border areas of Peru and Bolivia centered on Lake Titicaca have pursued common identity forming the same cultural area although they belong to different nations. In the meantime, the Aymara have maintained a sense of fellowship while emphasizing historicity and specialty, which are differentiated with groups of other natives based on a language constituting identity of the tribe. However, recently, focused on Puno State as the center of the border areas of both countries, the tribe's conflicts come to the surface. After being divided by the artificial boundary line, which was formed in the course of building modern countries after the independence, natives of Latin America started to emphasize differences simultaneously with cultural similarity in the frame of cooperation and competition. Together with the historical contexts, lately, focused on the border areas of Peru and Bolivia, as the same tribe came to be bound by the frameworks of different nations respectively, a new tribal conflict is being developed. Though the Aymara unite emphasizing cultural and historical specialty and recognizing them as one tribe, when they conflict with each other over inner interest, a tendency to form the identity of differentiation and distinction appeared even in the inside of the tribe. Usually, disorder between tribes seems to be originated from intertribal strife, which coexists in one region. In case of the Aymara of Peru and Bolivia, centered on Puno State where both countries maintain the border, an aspect that the fellowship of the tribe, which was established through old history changes into conflict structures by realistic conditions comes out. In understanding this point, this study analyzed the historical origin of the conflict of the Aymara and the deepened cause of the tribal disorder.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.3
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• pp.10-25
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• 2011

Since 1950, the city of Yokohama has been demanding the return of US. military base sites in Yokohama. Yokohama has established a systematic utilization plan for these relocation sites. The Fukaya communication site is one of former US. military bases verified for return in 2004. The Fukaya communication site is distinctively circular in shape and is entirely national land. Yokohama took an idea competition to its citizens to create a new park at the relocation of the Fukaya communication site, involving lots of citizen opinion in its utilization goals. This study determined the process of the idea competition at the Fukaya communication site in encouraging civic participation and analyzing citizen demands for the utilization of the relocation site. Through the idea competition, Yokohama city was able to obtain several ideas on the new park from various angles such as the function and shape of the urban open spaces. Citizens showed great interest in creating a park as green infrastructure on the Fukaya communication site. In addition, beyond utilization as an urban open space, many ideas suggested new lifestyles for the region in connection with the natural environment in the vicinity. Yokohama city tried to share the process and results of the idea competition with as many citizens as it could through a variety of means such as Participation, Judging, Support, Observation and Understanding. The case study on the idea competition at the Fukaya communication site is a good example of community design practice in public projects, and is full of suggestions for military bases in Korea, which has just established the plan of utilizing relocation sites as parks. Based on this case study, it can be concluded that it is important to make a systemic form for utilization planning with a clear process, open information and partnership in a variety of participatory design processes in order to ensure maximum civic utilization of relocation sites.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.2
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• pp.19-32
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• 2020

The purpose of this study was to investigate the influence factors of the university level centering on the entrepreneurial performance of the university students and full-time faculties in the situation of increasing interest in entrepreneurial university. In order to achieve the purpose of the study, a panel data was established from 2015 to 2018 on the basis of the university notification data. The panel data included universities with data on the number of university students and full-time faculty founders for at least two years. Through this, four year data from 154 universities were used for analysis. As an analysis method, frequency analysis and descriptive statistics were conducted to understand the characteristics of the university. Since then, panel negative binomial regression analysis has been conducted in consideration of the longitudinal features and distribution of the data. Also, based on the Hausman test results, the results were interpreted based on random effect model. The results of this study are as follows. First, as a result of the analysis of the entrepreneurial performance and the change trend of the domestic university from 2015 to 2018, the entrepreneurial performance of the university has been steadily increasing in the last four years, and the increase in the number of university student entrepreneurs was relatively higher than the full-time faculties. Second, economic and educational approaches need to be combined to promote university students' start-ups. The university factors that promote the start-up of university students were found to be scholarships, start-up grants, startup lectures, and startup clubs. Third, the openness and regional characteristics of the univeristy can promote the establishment of university students. Fourth, the establishment of a research environment and support for start-ups for full-time faculty members can enhance their start-up performance. The university factors that promote the start-up of full-time faculty were research funds and staffes who support start-up. The conclusions drawn from these findings are as follows. First, overall efforts are needed to develop into an entrepreneurial university. Second, in order to change into an entrepreneurial university, direct support for entrepreneurship is needed. Third, as an entrepreneurial university, it is necessary to find a way to bridge the gap by university according to region and size. Fourth, it is necessary to reinforce the support for linking the research results of universities to start-ups. Fifth, it is necessary to improve the atmosphere for full-time faculty members to be entrepreneur.

• Journal of the Korean Society of Radiology
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• v.83 no.5
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• pp.1059-1070
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• 2022

Purpose To compare the sensitivity of tumor detection and inter-observer agreement between acquired diffusion-weighted imaging (aDWI) b2000 and computed DWI (cDWI) b2000 in patients with prostate cancer (PCa). Materials and Methods Eighty-eight patients diagnosed with PCa by radical prostatectomy and having undergone pre-operative 3 Tesla-MRI, including DWI (b, 0, 100, 1000, 2000 s/mm²), were included in the study. cDWI b2000 was obtained from aDWI b0, b100, and b1000. Two independent reviewers performed a review of the aDWI b2000 and cDWI b2000 images in random order at 4-week intervals. A region of interest was drawn for the largest tumor on each dataset, and a Prostate Imaging-Reporting and Data System (PI-RADS) score based on PI-RADS v2.1 was recorded. Histologic topographic maps served as the reference standard. Results The study population's Gleason scores were 6 (n = 16), 7 (n = 53), 8 (n = 9), and 9 (n = 10). According to the reviewers, the sensitivities of cDWI b2000 and aDWI b2000 showed no significant differences (for reviewer 1, both 94% [83/88]; for reviewer 2, both 90% [79/88]; p = 1.000, respectively). The kappa values of cDWI b2000 and aDWI b2000 for the PI-RADS score were 0.422 (95% confidence interval [CI], 0.240-0.603) and 0.495 (95% CI, 0.308-0.683), respectively. Conclusion cDWI b2000 showed comparable sensitivity with aDWI b2000, in addition to sustained moderate inter-observer agreement, in the detection of PCa.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.34-42
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• 2014

Purpose : To evaluate the correlation of lesion-to-normal ratio (LNR) of signal intensity from double inversion recovery MR imaging and total choline-containing compound (tCho) resonance from single voxel MR spectroscopy in breast cancers. Materials and Methods: Between August 2008 and December 2009, 28 patients who were diagnosed as breast cancer and had undergone both double inversion recovery (DIR) MR imaging and MR spectroscopy (MRS) were included in this study. The signal intensities of the lesion (L) and ipsilateral normal breast tissue (N) were measured in region of interest of each breast cancer in DIR and contrast enhance MR image (CE-T1WI) to calculate the LNR value for each technique. MRS was performed using single-voxel MR spectroscopy. The height, width and area of tCho resonance were compared with each LNR of DIR and CE-T1WI. We used Pearson's correlation coefficient(r) for correlation analysis and the significance level was p=0.05. Results: There was no statistically significant correlation between LNR of CE-T1WI and height (r=-0.322, p=0.094), width (r=-0.233, p=0.232) and area (r=-0.309, p=0.109) of MRS tCho. There was no statistically significant correlation between LNR of DIR and height (r=0.067, p=0.735), width (r=-0.287, p=0.139) and area (r=0.012, p=0.953) of MRS tCho, either. The Pearson's correlation coefficient was 0.186 between LNRs of CET1WI and DIR (p=0.344). Conclusion: There was no statistically significant correlation between LNR of DIR and relative amount of tCho resonance of MRS.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.115-121
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• 2014

Purpose: In addition to improving the quality of the PET image, through much research, the development of various programs are performed. Astonish TF reconstruction techniques by Philips can confirm the improved contrast of the lesion. Also, It's image reconstruction of 2 mm is possible with rapid reconstruction rate than conventional. In this study, we compared and evaluated Standardized Uptake Value (SUV) in accordance with the 2 mm reconstruction techniques and traditional 4 mm from the $^{18}F-FDG$ PET whole body image. Materials and Methods: In the phantom experiment, NEMA IEC body phantom (sphere: 10, 13, 17, 22, 28, 37 mm) was used to obtain images by using GEMINI TF 64 PET/CT (Philips, Cleveland, USA). Also, In the clinical images, we performed $^{18}F-FDG$ PET/CT examination to 30 women (age: $55.1{\pm}11.3$, BMI: $24.1{\pm}2.9$) with a diagnosis of breast cancer. After that, we reconstructed images in 2 mm and 4 mm respectively. The region of interest was drawn to acquired images. Since then, we measured SUV and statistically analyzed with SPSS ver.18 by using EBW (Extended Brilliance Workstation) NM ver.1.0. Results: After analyzing the result of the phantom study, there was a tendency that the bigger hot sphere size, the higher SUV. If you compared the 2 mm reconstruction techniques to 4 mm, it increased 95.78% in 10 mm, 50.60% in 13 mm, 25.00% in 17 mm, 30.04% in 22 mm, 31.81% in 28 mm, and 27.84% in 37 mm. Through the result of the analysis of the 2 mm reconstruction techniques and 4 mm in clinical images, it appeared that SUV of 2 mm was higher than that of 4 mm. Also the smaller the volume was, the more the change rate increased. Conclusion: After analyzing the result of the clinical picture and phantom experiments applied by Astonish TF reconstruction techniques, as the size of the volume was small, the change rate of the SUV increased. Therefore, it was necessary to further research about the SUV correction for accurate and active utilization of 2 mm reconstruction techniques which had excellent lesion discrimination ability and contrast in clinic.

• Korean Journal of Radiology
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• v.23 no.2
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• pp.226-236
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• 2022

Objective: This study aimed to explore the myelin volume change in patients with mild traumatic brain injury (mTBI) with post-concussion syndrome (PCS) using a multidynamic multiecho (MDME) sequence and automatic whole-brain segmentation. Materials and Methods: Forty-one consecutive mTBI patients with PCS and 29 controls, who had undergone MRI including the MDME sequence between October 2016 and April 2018, were included. Myelin volume fraction (MVF) maps were derived from the MDME sequence. After three dimensional T1-based brain segmentation, the average MVF was analyzed at the bilateral cerebral white matter (WM), bilateral cerebral gray matter (GM), corpus callosum, and brainstem. The Mann-Whitney U-test was performed to compare MVF and myelin volume between patients with mTBI and controls. Myelin volume was correlated with neuropsychological test scores using the Spearman rank correlation test. Results: The average MVF at the bilateral cerebral WM was lower in mTBI patients with PCS (median [interquartile range], 25.2% [22.6%-26.4%]) than that in controls (26.8% [25.6%-27.8%]) (p = 0.004). The region-of-interest myelin volume was lower in mTBI patients with PCS than that in controls at the corpus callosum (1.87 cm³ [1.70-2.05 cm³] vs. 2.21 cm³ [1.86-3.46 cm³]; p = 0.003) and brainstem (9.98 cm³ [9.45-11.00 cm³] vs. 11.05 cm³ [10.10-11.53 cm³]; p = 0.015). The total myelin volume was lower in mTBI patients with PCS than that in controls at the corpus callosum (0.45 cm³ [0.39-0.48 cm³] vs. 0.48 cm³ [0.45-0.54 cm³]; p = 0.004) and brainstem (1.45 cm³ [1.28-1.59 cm³] vs. 1.54 cm³ [1.42-1.67 cm³]; p = 0.042). No significant correlation was observed between myelin volume parameters and neuropsychological test scores, except for the total myelin volume at the bilateral cerebral WM and verbal learning test (delayed recall) (r = 0.425; p = 0.048). Conclusion: MVF quantified from the MDME sequence was decreased at the bilateral cerebral WM in mTBI patients with PCS. The total myelin volumes at the corpus callosum and brainstem were decreased in mTBI patients with PCS due to atrophic changes.

• Korean Journal of Ecology and Environment
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• v.50 no.2
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• pp.216-237
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• 2017

Thermal effluent of the hot spring has long been a field of interest in the relationship between temperature gradient and freshwater algae in geology, limnology and aquatic ecology throughout the world. On the other hand, many artificial hot springs have been developed in Korea, but the research on them has not been still active. This study was performed every month from December 2015 to September 2016, to elucidate the spatiotemporal effects of thermal wastewater effluent (TWE) on the ecosystem of benthic algal assemblage in four stations(BSU (upstream), HSW (hot spring wastewater outlet), BSD1~2 (downstream)) of the upstream reach of the Buso Stream, a tributary located in the Hantan River basin. During the survey, the influencing distance of temperature on TWE was <1.0 km, and it was the main source of N P nutrients at the same time. The effects of TWE were dominant at low temperature and dry season (December~March), but it was weak at high temperature and wet season (July~September), reflecting some seasonal characteristics. Under these circumstances, the attached algal communities were identified to 59 genera and 143 species. Of these, the major phylum included 21 genera 83 species of diatoms(58.0%), 9 genera 21 species of blue-green algae (14.7%) and 25 genera 32 species of green algae (22.4%), respectively. The spatiotemporal distribution of them was closely related to water temperature ($5^{\circ}C$ and $15^{\circ}C$) and current ($0.2m\;s^{-1}$ and $0.8m\;s^{-1}$). In the basic environment maintaining a high water temperature throughout the year round, the flora favoring high affinity to $PO_4$ in the water body or preferring stream habitat of abundant $NO_3-PO_4$ was dominant. As a result, when compared with the outcomes of previous algal ecology studies conducted in Korea, the Buso Stream was evaluated as a serious polluted state due to persistent excess nutrient supply and high thermal pollution throughout the year round by TWE. It can be regarded as a dynamic ecosystem in which homogeneity (Summer~Autumn) and heterogeneity (Winter~Spring) are repeated between upstream and downstream.