• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.490-499
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• 2008

Statement of problem: Bioactive materials must have the ability to spontaneously form a bone like apatite layer on their surface and induce direct biochemical bonding to bone. A simple chemical treatment via alkali and heat has been revealed to induce bioactivity in titanium. Purpose: The purpose of this study was to evaluate the surface characteristics and stability of alkali and heat treated implants. Material and methods: Specimens were divided into three groups; group 1 was the control group with machined surface implants, groups 2 and 3 were treated with alkali solutions and heat treated in the atmosphere and vacuum conditions respectively. The surface characteristics were observed with FESEM, XPS, TF-XRD and AFM. Stability was evaluated with the resonance frequency analysis, periotest and removal torque values. One-way ANOVA and Duncan test were used for statistical analysis. Results: 1. Groups treated with alkali and heat showed similar characteristics. Groups 2 and 3 showed high compositions of Na ions on the surface with sub-micron sized pores compared to group 1. Group 2 showed mixed compositions of anatase and rutile with superior contents of rutile. 2. Resonance frequency analysis : The ISQ of group 2 showed significantly higher values than that of groups 1 and 3 at 12 weeks. The ISQ of groups 1 and 2 showed significant increase after 4 weeks, and the ISQ of group 3 increased significantly after 2 and 4 weeks respectively (P < .05). 3. Periotest: The PTV of groups 1 and 2 showed significant decrease after 4 weeks, and the PTV of group 3 showed significant decrease after 2 and 4 weeks respectively (P < .05). 4. Removal torque analysis: The removal torque value of group 2 was significantly higher than those of groups 1 and 3 at 2, 4 and 8 weeks. The removal torque values of groups 1 and 3 showed increase at 4 and 12 weeks, but the removal torque value of group 2 showed increase after 4 weeks (P < .05). Conclusion: An oxide layer with appropriate crystal structure and amorphous sodium titanate layer can be obtained on titanium implants through alkali and heat treatment in the atmosphere, and even alkali and heat treatment in vacuum conditions, provided a bioactive surface containing sodium. These surface layers can be considered to be effective for enhancement of osseointegration and reduction of healing period for implant treatment.

• The Korean Journal of Nuclear Medicine
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• v.36 no.2
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• pp.91-101
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• 2002

Purpose : The aim of this study was to identify the brain areas in which reductions of regional cerebral blood flow (rCBF) were correlated with decline of general mental function, measured by Mini-Mental State Examination (MMSE). Materials and Methods : Tc-99m HMPAO brain SPECT was peformed in 9 probable AD patients at the initial and follow-up periods of 1.8 years (average) after the first study. MMSE scores were also measured in both occasions. The mean MMSE score of the initial study 16.4 (range: 5 - 24) and the mean MMSE score of the follow-up was 8.1 (range: 0 - 17). Each SPECT image was normalized to the cerebellar activity and a correlation analysis was peformed between the level of rCBF in AD patients and the MMSE scores by voxel-based analysis using SPM99 software. Results : Significant correlation was found between the blood-flow decrease in left inferior prefrontal region (BA 47) and left middle temporal legion (BA 21) and the MMSE score changes. Additional areas such as anterior and posterior cingulate cortices, precuneus, and bilateral superior and middle prefrontal regions showed the similar trends. Conclusions : A relationship was found between reduction of regional cerebral blood flow in left prefrontal and temporal areas and decline of cognitive function in Alzheimer's disease(AD) patients. This voxel-based analysis is useful in evaluating the progress of cognitive function in Alzheimer's disease.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.533-540
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• 2000

Gonadal development, gametogenesis, reproductive cycle, gonad index, flesh weight rate, and first sexual maturity of the turban shell, Lunella coronata coreensis were investigated by histological observation. The materials used were collected monthly from the rocky intertidal zone of Daehang-ri, Buan-gun, Jeollabuk-do, on the west coast of Korea, from July 1998 to June 1999. Sex of L coronata coreensis was separate. The gonad was widely located in the spirals of the visceral mass buried in the digestive gland. The ovary and testis were composed of a number of oogenic follicles and speymatogenic follicles, respectively. Monthly variations in the gonad index increased from March ($23.86{\pm}3.73$) when the water temperature increased and reached the maximun in July ($49.76{\pm}6.47$). And then, the gonad index sharply decreased in September ($15.58{\pm}2.33$). The flesh weight rate ranged from $25.2{\%}$ to $32.3{\%}$, and its variation showed a similar pattern to the gonad index. Individuals $<5.9 mm$ in shell height could not take part in reproduction in both sexes. Percentages of first sexual maturity of female and male specimens ranging from $7.0{\~}7.9 mm$ in shell heights were $84.6{\%}\;and\;91.7{\%}$, respectively, and $100{\%}$ in those over 8.0 mm in shell height in both sexes took part in reproduction. By studying the monthly changes of the morphological features and sizes of germ cells during gametogenesis in the gonad, the reproductive cycle of this species could be devided into five successive stages: early active (December to April), late active (January to July), ripe (May to August), spawning (July to September), and recovery (September to March). The spawning period of this species was once a year between July and September, and the main spawning occurred in July when the seawater temperature reached above $24.8^{\circ}C$. The fully ripe eggs were $150{\~}160\;{\mu}m$ in diameter.

• Journal of the Korean Arthroscopy Society
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• v.16 no.1
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• pp.26-33
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• 2012

Purpose: The purpose of this study was to evaluate the clinical outcomes and stability of anatomical single bundle anterior cruciate ligament reconstruction (SBACLR) with quadriceps tendon comparable to double bundle anterior cruciate ligament reconstruction (DBACLR). Materials and Methods: We retrospectively reviewed 28 consecutive patients (16 male, 12 female) who underwent SBACLR using quadriceps tendon from March 2009 (Group 1) and compared its clinical results to whom DBACLR with semitendinosus tendon for 53 patients (51 male, 2 female) from August. 2006 (Group 2). Mean age were 34.9 (range, 16-52) in Group 1 and 21.6 (range, 17-55) in Group 2. Mean follow up periods were 13.9 months (range, 12-20) in Group 1 and 36.2 months (range, 20-52) in Group 2. Lysholm score, International Knee Documentation Committee (IKDC) evaluation form and Tegner score were performed for evaluating the clinical outcome. Lachman test, pivot shift test and KT-1000 arthrometer (MEDmetric Corp., San Diego, CA, USA) were performed for stability. Results: There was no statistical significant difference between the two groups in terms of Lysholm score (Group 1: $85.9{\pm}2.6$, Group 2: $90.9{\pm}1.0$, P=0.226), IKDC score (P=0.345) and Tegner score (Group 1: $6.9{\pm}1.4$, Group 2: $7.1{\pm}1.3$, P=0.523). Nor was there statistical significance between the two groups in terms of KT-1000 arthrometer (Group 1: $1.5{\pm}1.1\;mm$, Group 2: $1.5{\pm}1.6\;mm$, P=0.457), Lachman test (P=0.547) and pivot shift test (P=0.073). Conclusion: Anatomical SBACLR with quadriceps tendon shows similar clinical outcomes and stability comparable to anatomical DBACLR with hamstring tendon.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.20 no.4
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• pp.305-315
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• 1998

The fibrous layer of mandibular condyle of the neonatal, 1-, 7-, 14-, 27-, 55-days and 1 year old rats were examined in the electron microscope with particular attention to the ultrastructure and diameter of collagen fibrils. In the 1-day rats, most of the cells of the fibrous layer were undifferentiated mesenchymal cells and fibroblasts with rough a little developed rough endoplasmic reticulum(RER) and golgi apparatus(GA). In 7-, 17 and 27-days old rats, most of the fibroblast showed well developed GA and RER with widely distended cisternae containing granular materials. In many of these cells contained intracytoplasmic filaments among the cytoplamic organelle. In 55-day and 1-year old rats, three types of cells were observed, ie, cells containing well developed cytoplasmic organelle presumed to be involved in the collagen fibril synthesis, cells showing well developed lysosomes, golgi apparatus, mitochondria and short cytoplasmic process presumed to be involved in the active resorption of the injured collagen fibrils or cellular debris, cells containing many intracytoplasmic filaments and a little organelle presumed to be cells of inactive state. The average diameters of collagen fibrils were similar in 1- and 7-day old rats as $38.48{\pm}3.81nm$, $38.06{\pm}3.86nm$. That was thickest in 14 days old rats as $50.21{\pm}3.93nm$ among experimental groups. They were gradually thinner in 27-, 55-day rats as $40.05{\pm}2.52nm$, $43.63{\pm}1.20nm$ and thinnest in 1-year old rats as $37.38{\pm}2.17nm$. The distribution pattern of diameters of collagen fibrils were unimordal with peak of 30-60nm in rats from 1-day to 17-day old. With aging from 27-day to 1 year old rats, collagen fibril diameters showed wide distribution pattern and percentage of thin collagen fibrils increased. These results may show the functional adaptation of fibrous layer of mandibular condyle to the increased mechanical forces with aging.

• Investigative Magnetic Resonance Imaging
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• v.9 no.1
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• pp.9-15
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• 2005

Purpose : This study attempted to investigate the effects of supply of highly concentrated $(30\%)$ oxygen on human ability of visuospatial cognition using time course data analysis of functional Magnetic Resonance Imaging (fMRI). Materials and Methods : To select an item set in the visuospatial performance test, two questionnaires with similar difficulty were developed through group testing. A group test was administered to 263 college students. Two types of questionnaire containing 20 questions were developed to measure the ability of visuospatial cognition. Eight college students (right-handed male, average age of 23.5 yrs) were examined for fMRI study. The experiment consisted of two runs of the visuospatial cognition testing, one with $21\%$ level of oxygen and the other with $30\%$ oxygen level. Each run consisted of 4 blocks, each containing control and visuospatial items. Functional brain images were taken from 37 MRI using the single-shot EPI method. Using the subtraction procedure, activated areas in the brain during visuospatial tasks were color-coded by t-score. To investigate the time course data in each activated area from brain images, 4 typical regions (cerebellum, occipital lobe, parietal lobe, and frontal lobe) were selected. Results : The average accuracy was $50.63{\pm}8.63$ and $62.50{\pm}9.64$ for $21\%\;and\;30\%$ oxygen respectively, and a statistically significant difference was found in the accuracy between the two types of oxygen (p<0.05). There were more activation areas observed at the cerebellum, occipital lobe, parietal lobe and frontal lobe with $30\%$ oxygen administration. The rate of increase in the cerebellum, occipital lobe and parietal lobe was $17\%$ and that of the frontal lobe, $50\%$. Especially, there were increase of intensity of BOLD signal at the parietal lobe with $30\%$ oxygen administration. The increase rate of the left parietal lobe was $1.4\%$ and that of the right parietal lobe, $1.7\%$. Conclusion : It is concluded that while performing visuospatial tasks, high concentrations of oxygen administration make oxygen administration sufficient, thus making neural network activate more, and the ability to perform visuospatial tasks increase.

• 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.

• Journal of the Mineralogical Society of Korea
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• v.30 no.2
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• pp.59-70
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• 2017

$SiO_2$ is one of the most abundant constituents of the Earth's crust and mantle. Probing its electronic structures at high pressures is essential to understand their elastic and thermodynamic properties in the Earth's interior. The in situ high-pressure x-ray Raman scattering (XRS) experiment has been effective in providing detailed bonding transitions of the low-z materials under extreme compression. However, the relationship between the local atomic structures and XRS features at high pressure has not been fully established. The ab initio calculations have been used to overcome such experimental difficulties. Here we report the partial density of states (PDOS) of O atoms and the O K-edge XRS spectra of ${\alpha}-quartz$, ${\alpha}-cristobalite$, and $CaCl_2$-type $SiO_2$ phases calculated using ab initio calculations based on the full-potential linearized augmented plane wave (FP-LAPW) method. The unoccupied O PDOSs of the $CaCl_2$-type $SiO_2$ calculated with and without applying the core-hole effects present significantly distinctive features. The unoccupied O p states of the ${\alpha}-quartz$, ${\alpha}-cristobalite$ and $CaCl_2$-type $SiO_2$ calculated with considering the core-hole effect present similar features to their calculated O K-edge XRS spectra. This confirms that characteristic features in the O K-edge XRS stem from the electronic transition from 1s to unoccupied 2p states. The current results indicate that the core-hole effects should be taken in to consideration to calculate the precise O K-edge XRS features of the $SiO_2$ polymorphs at high pressure. Furthermore, we also calculated O K-edge XRS spectrum for $CaCl_2$-type $SiO_2$ at ~63 GPa. As the experimental spectra for these high pressure phases are not currently available, the current results for the $CaCl_2$-type $SiO_2$ provide useful prospect to predict in situ high-pressure XRS spectra.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.4
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• pp.132-142
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• 2014

This study is the first stage to identify distinctive characteristics of American Romantic Garden compared to English Romantic Garden. The purpose of the study is to identify characteristics of transitional garden in the early period of America by analyzing of Paca garden, Mount Vernon and Monticello when English Naturalistic Garden was firstly imported. The analysis studied historical background, people who designed garden, formal garden and characteristics of natural garden through reference. Also based on data through reference and field research, spatial configuration and garden factors of each site were analyzed. In spatial configuration, straight line and curve line, formal terrace and natural slope, visible axis and invisible axis, symetric and asymmetric, and perspective and oblique perspectives were used as analyzing factors. As a result of analysis, each garden showed different type from that of formal gardens from colony period, which is natural garden of asymmetric garden(English natural garden) coexisted. Paca garden which planned formal garden and natural garden in each space showed characteristics of each space, but in formal garden residential axis and garden axis does not coincide which shows it is out of formal garden type. Such phenomena and the fact that naturalistic garden coexist in the same garden shows that the formal garden type from early days in US is starting to change in different types. Mount Vernon garden, similar to Paca garden, was designed to have two different types of gardens in harmony rather than divide the space into different space and design it. It adapted serpent walkway but shows symmetric by central axis and considered formalistic plan through same materials. However through terrace in hills and spatial plan of oblique perspective, one could observe that naturalistic type was beginning to settle in US gardens. Through Monticello analysis, space was designed with major characteristics of naturalistic garden which is serpent walkway, ornamental farm, winding flower bed grove and bush and oblique perspective, and it completely duplicates characteristics of naturalistic garden which could not be found in gardens imported from UK.