• Korean Journal of Ecology and Environment
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• v.56 no.3
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• pp.218-228
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• 2023

Invasive predators are one of the most damaging species groups to biodiversity. In the Nakdong River, the lake skygazer Chanodichthys erythropterus is a dominant species that is fiercely carnivorous and a concern for commercial fish. Although it is important to understand the ecological characteristics related to the feeding habit, studies on the diets of lake skygazer in Nakdong River have been limited to studies of gut contents. In this study, the trophic position (TP) and feeding habits of C. erythropterus were studied by calculating TPs using samples collected from 13 sites throughout the Nakdong River. Compound-specific isotopic analysis of amino acids provided reliable TPs from the muscle of Lake skygazer C. erythropterus without any isotope baseline. The results were approximately 3 to 3.6 and suggesting a carnivorous but size-dependent prey variation. In particular, the TP variability of C. erythropterus observed in the Nakdong River showed that it had a selective feeding habit compared to carnivorous fish species of relatively similar trophic levels.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.2
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• pp.66-72
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• 2024

In this study, the applicability of CCMs (Carbondioxide conversion capture materials) manufactured by reacting carbon dioxide gas with DG (Desulfurization gypsum) as a cement substitute for secondary concrete products were evaluated and the basic physical properties of CCMs-mixed mortar and concrete specimens were measured to derive the optimal mixing ratio. The main chemical oxides of CCMs were CaO and SO₃, and the main crystalline phases were CaSO₄·2H₂O, Ca(OH)₂, CaCO₃, and CaSO₄. In addition, by the results of particle size analysis and heavy metal measurement, the applicability of CCMs as a cement substitute for secondary concrete products was confirmed. As a result of measuring the strength behavior using mortar and concrete specimens with CCMs, the compressive and flexural strength decreased as the mix ratio of CCMs increased, but requirements by the standards for interlocking blocks and retaining wall blocks, which are target products in this study, were satisfied up to the optimal mixing ratio of 10 wt.% substitution. Therefore, its applicability as a cement substitute for secondary concrete products was confirmed.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.683-696
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• 2023

The conservation of wetland ecosystems has a significant role in climate change. Notably, the Han River Protected Area, including the Siam-ri wetland and Janghang wetland, provides high biodiversity value. Thus, it is necessary to comprehensively evaluate the function and value of wetland ecosystems. This study evaluated the ecosystem services of Siam-ri and Janghang Wetlands located in the Han River Protected Area using the Rapid Assessment Wetland Ecosystem Services approach, a function-oriented ecosystem analysis. The results were calculated using the Ecosystem Services Index formula to analyze wetland ecosystem services. We also assessed the key ecosystem services based on a focus group interview. We identified that the supporting and cultural services index scores were relatively high in the study area. The results can provide helpful information for sustainable wetland conservation, conservation planning as primary data, and raising awareness for the Han River Protected Area.

• Investigative Magnetic Resonance Imaging
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• v.4 no.1
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• pp.42-51
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• 2000

Purpose: Projection-type Fast Spin Echo (PFSE) imaging is robust to patient motion or flow related artifact compared to conventional Fast Spin Echo (FSE) imaging, however, it has difficulty in controlling $T_2$ contrast. In this paper, Tz contrast in the PFSE method is analyzed and compared with those of the FSE method with various effective echo times by computer simulation. The contrasts in the FSE and PFSE methods are also compared by experiments with volunteers. From the analysis and simulation, it is shown that ${T_2}-weighted$ images can well be obtained by the PFSE method proposed. Materials and methods: Pulse sequence for the PFSE method is implemented at a 1.0 Tesla whole body MRI system and $T_2$ contrasts in the PFSE and FSE methods are analyzed by computer simulation and experiment with volunteers. For the simulation, a mathematical phantom composed of various $T_2$ values is devised and $T_2$ contrast in the reconstructed image by the PFSE is compared to those by the FSE method with various effective echo times. Multi-slice ${T_2}-weighted$ head images of the volunteers obtained by the PFSE method are also shown in comparison with those by the FSE method at a 1.0 Tesla whole body MRI system. Results: From the analysis, $T_2$ contrast by the PFSE method appears similar to those by the FSE method with the effective echo time in a range of SO-lOOms. Using a mathematical phantom, contrast in the PFSE image appears close to that by the FSE method with the effective echo time of 96ms. From experiment with volunteers, multi-slice $T_2-weighted$ images are obtained by the PFSE method having contrast similar to that of the FSE method with the effective echo time of 96ms. Reconstructed images by the PFSE method show less motion related artifact compared to those by the FSE method. Conclusion: The projection-type FSE imaging acquires multiple radial lines with different angles in polar coordinate in k space using multiple spin echoes. The PFSE method is robust to patient motion or flow, however, it has difficulty in controlling $T_2$ contrast compared to the FSE method. In this paper, it is shown that the PFSE method provides good $T_2$ contrast (${T_2}-weighted$ images) similar to the FSE method by both computer simulation and experiments with volunteers.

• Investigative Magnetic Resonance Imaging
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• v.5 no.2
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• pp.138-148
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• 2001

Purpose : Within a clinically acceptable time frame, we obtained the high resolution MR images of the human brain, knee, foot and wrist from 3T whole-body MRI system which was equipped with the world first 37 active shield magnet. Materials and Methods : Spin echo (SE) and Fast Spin Echo (FSE) images were obtained from the human brain, knee, foot and wrist of normal subjects using a homemade birdcage and transverse electromagnetic (TEM) resonators operating in quadrature and tuned to 128 MHz. For acquisition of MR images of knee, foot and wrist, we employed a homemade saddle shaped RF coil. Topical common acquisition parameters were as follows: matrix=$512{\times}512$, field of view (FOV) =20 cm, slice thickness = 3 mm, number of excitations (NEX)=1. For T1-weighted MR images, we used TR = 500 ms, TE = 10 or 17.4 ms. For T2-weighted MR images, we used TR=4000 ms, TE = 108 ms. Results : Signal to noise ratio (SNR) of 3T system was measured 2.7 times greater than that of prevalent 1.5T system. MR images obtained from 3T system revealed numerous small venous structures throughout the image plane and provided reasonable delineation between gray and white matter. Conclusion The present results demonstrate that the MR images from 3T system could provide better diagnostic quali\ulcorner of resolution and sensitivity than those of 1.5T system. The elevated SNR observed in the 3T high field magnetic resonance imaging can be utilized to acquire images with a level of resolution approaching the microscopic structural level under in vivo conditions. These images represent a significant advance in our ability to examine small anatomical features with noninvasive imaging methods.

• Journal of the Korean Geographical Society
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• v.49 no.4
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• pp.525-545
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• 2014

This study seeks to clarify the influence of the stage migration which has proceeded through generations, on the population growth of local cities in the case of Jeollabuk-do. For this, setting to baby boomer as parents generation and echo boomer as their children, this study traces each generation's birth, distribution and the process of selective migration using aggregate level data. And the stage migration is analyzed by O-D, divided into three regions in each; Jeollabuk-do rural areas, Jeollabuk-do cities and other provinces. The major findings of this study are as follows. First, it was estimated that the number of the baby boomer births in Jeollabuk-do rural areas was seven times more numerous than in cities. Second, both rural and urban born baby boomers overwhelmingly moved into other provinces, especially Seoul metropolitan area and metropolis in their selective migration processes. However, there was also migration stream from rural areas to cities in Jeollabuk-do and the amount of this stream was approximately equal to the amount of outflux from cities in Jeollabuk-do to other provinces. Third, due to baby boomers' stage migration, from rural to urban, echo boomers were born in cities more than in rural areas. Fourth, urban born echo boomers still have moved into other provinces just like their parents generation in selective migration process. But comparing with baby boomer, the number of echo boomers influx from rural areas to cities has decreased. Consequentially the population of echo boomer in Jeollabuk-do cities also has decreased. Finally, the stage migration has been a basic cause of the social growth of urban population, and also influenced on the natural growth, closely connected with migrants' life course, such as marriage, childbirth and rearing. Therefore, this study concludes that the stage migration through generations is one of the crucial factor to understand the population growth in local cities.

• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.152-157
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• 2002

Purpose : The differential diagnosis between Modic type I degenerative spine and infectious spondylitis sometimes is difficult, because the affected bone marrows in both disease show similar signal intensity on conventional MR imaging. We evaluate the usefulness of diffusion-wighted MR imaging for differential diagnosis between Modic type I degenerative spine and infectious spondylitis. Materials and methods : The spin-echo and diffusion-weighted MR images of eight patients with Modic type I degenerative spines and 14 patients with infectious spondylitis diagnosed by clinical findings or CT-guided biopsies we re analyzed. The diffusion-weighted imaging sequence was based on reversed fast imaging with steady-state precession (PSIF). Signal intensity changes of the vertebral bone marrow on conventional spin-echo and diffusion-weighted MR imaging were compared between degenerative spine and infectious spondylitis. Results : On T1-weighte d images, the affeted bone marrow in both disease showed hypointense signals. On T 2-weighted images, all of type I degenerative spine and 11 of infectious spondylitis showed hyperintensity, and three of infectious spondylitis showed heterogeneo us mixed signal intensity. On diffusion-weighted MR images, all of type I degenerative spine were hypointense with peripheral high signal intensity to normal vertebral body, but infectious spondylitis was hyperintense (n = 11) and hypointense (n=3). Conclusion : Diffusion-weighted MR imaging is useful to differentiate Modic type I degenerative spine from infectious spondylitis. On diffusion-weighted images, the high singal intensity of bone marrow suggests infectious spondylitis, whereas the low signal intensity of bone marrow with peripheral focal high signal intensity suggests type I degenerative spine.

• Investigative Magnetic Resonance Imaging
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• v.4 no.2
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• pp.107-112
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• 2000

Purpose : To evaluate the usefulness of comparison of the signal intensity of uterine septum in the differential diagnosis of bicornuate and septate uterus on magnetic resonance (MR) imaging. Materials and methods : Preoperative MR imaging findings of surgically proven 5 bicornuate and 6 septate uteri were retrospectively analyzed. Because preoperative differential diagnosis of both was possible in all cases in terms of the intercornual distance, external contour of uterine fungus, and divergent angle of two uterine cavities, these criteria were excluded in this study. The signal intensity of uterine septum in patients with bicornuate and septate uterus was analyzed on T1-weighted and fast spin echo T2-weighted images obtained in the axial and coronal planes, using a 1.5-T MR scanner. The signal intensity of uterine septum especially on T2-weighted images was compared with that of myometrium or junctional zone. Results : The signal intensity of uterine septum in patients with bicornuate uterus (n=5) and septate uterus (n=6) was similar to that of myometrium in all cases on T1-weighted images. The septum of bicornuate uterus (n=5) on fast spin echo T2-weighted images was isointense with myometrium in three and hypointense in two cases. The uterine septum of septate uterus (n=6) on T2-weighted images was isointense with myometrium in two, hypointense in two, and isointense with or more hypointense than junctional zone in two cases. No patient showed different signal intensity between upper and lower uterine septum. Conclusion : Because the MR signal intensity of the uterine septum in bicornuate or septate uterus is variable, it should not be used alone in the differential diagnosis of them. In these clinically important differentiation, therefore, comprehensive analysis of MR findings in terms of the external contour of uterine fundus, intercornual distance, divergent angle of two uterine cavities, in addition to the signal intensity of the uterine septum, should be considered.

• Progress in Medical Physics
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• v.12 no.2
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• pp.113-124
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• 2001

For veterinary imaging diagnosis, we obtained MR images of the canine brain, spine, kidney and pelvis from 3T MRI system which was equipped with the world first 3T active shield magnet. Spin echo (SE) and fast Spin Echo (FSE) images were obtained from the canine brain, spine, kidney and pelvis of normal and sick dogs using a homemade birdcage and transverse electromagnetic (TEM) resonators operating in quadrature and tuned to 128 MHz. In addition, we employed a homemade saddle shaped RF coil. Typical common acquisition parameters were as follows: matrix=512$\times$512, field of view (FOV)=20cm, slice thickness=3 w, number of excitations (NEX)=1. For T1-weighted MR images, we used TR=500 ms, TE=10 or 17.4 ms. For T2-weighted MR images, we used TR=4000 ms, TE=108 ms. Signal to noise ratio (SNR) of 3T system was measured 2.7 times greater than that of prevalent 1.57 system. The high resolution images acquired in this study represent more than a 4-fold increase in in-plane resolution relative to conventional images obtained with a 20 cm field of view and a 5 mm slice thickness. MR images obtained from 3T system revealed numerous small venous structures throughout the image plane and provided reasonable delineation between gray and white matter The present results demonstrate that the MR images from 3T system could provide better diagnostic quality of resolution and sensitivity than those of 1.5T system. The elevated SNR observed in the 3T high field magnetic resonance imaging can be utilized to acquire images with a level of resolution approaching the microscopic structural level under in vivo conditions. These images represent a significant advance in our ability to examine small anatomical features with noninvasive imaging methods. Moreover, MRI technique could begin to apply for veterinary medicine in Korea.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.2 no.1
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• pp.1-6
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• 2009

Purpose: The goal of this study is to evaluate the relationship between the clinical findings and ultrasonographic findings of plantar fasciitis. Materials and Methods: Forty-nine symptomatic heels of 36 patients with plantar fasciitis and 21 asymptomatic heels were included. Twenty-three patients had unilateral lesions and 13 had bilateral lesions. Of these, 16 were men and 20 were women. The average age of the patients was 48.6 years. The plantar fascia thickness was measured at its insertion of the calcaneus. Qualitative parameters such as decreased echogenity, biconvexity, partial rupture and calcification of plantar fascia, and subcalcaneal spur on plain radiographs were also noted. Comparisons of ultrasonographic parameters between symptomatic heels and asymptomatic heels as well as between unilateral and bilateral groups were done. Results: There was no differences in the age, sex, body mass index, and duration of symptom between the unilateral and bilateral group. There were a statistically significant difference between the thickness of plantar fascia of unilateral group (mean 5.2 mm, SD1.5 mm) and that of bilateral group (mean 4.4 mm, SD 1.4 mm) (p=0.045). The hypoechogenity of plantar fascia and subcalcaneal spur did not differ between two groups. No fascial rupture or fascial calcification were identified. There was a statistically significant difference between the thickness of plantar fascia of symptomatic heels (mean 4.8 mm, SD1.5 mm) and that of asymptomatic heels (mean 3.1 mm, SD 0.5 mm) (p=0.000). The thickness of plantar fasia was negatively correlated with duration of symptoms (p=0.046). Conclusion: The thickness of plantar fascia in plantar fasciitis seems to be negatively correlated with the duration of symptoms, and the thickness of symptomatic heels and unilateral group was significantly thicker than that of asymptomatic heels and bilateral group, respectively.