• Progress in Medical Physics
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• v.8 no.2
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• pp.67-76
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• 1997

We studied optical behavior of scintillation light generated in NaI(TI) crystal using Monte Carlo simulation method. The simulation was performed for the model of NaI(TI) scintillator (size: 60 mm ${\times}$ 60 mm ${\times}$ 6 mm) using an optical tracking code. The sensitivity as a function of surface treatment (Ground, Polished, Metal-0.95RC, Polished-0.98RC, Painted- 0.98RC) of the incident surface of the scintillator was compared. The effects of NaI(TI) scintillator thickness and the refractive index of light guide optically coupling between the NaI(TI) scintillator and photomultiplier tube (PMT) were simulated. We also evaluated intrinsic position resolution of the system by calculating the spread of scintillation light generated. The sensitivities of the system having the surface treatment of Ground, Polished, Metal-0.95RC, Polished-0.98RC and Painted-0.98RC were 70.9％, 73.9％, 78.6％, 80.1％ and 85.2％, respectively, and the surface treatment of Painted-0.98RC allowed the highest sensitivity. As increasing the thickness of scintillation crystal and light guide, the sensitivity of the system was decreased. As the refractive index of light guide increases, the sensitivity was increased. The intrinsic position resolution of the system was estimated to be 1.2 mm in horizontal and vertical directions. In this study, the performance of NaI(TI)-PMT detector system was evaluated using Monte Carlo simulation. Based on the results, we concluded that the NaI(TI)-PMT detector array is a favorable configuration for small gamma camera imaging breast tumor using Tc-99m labeled radiopharmaceuticals.

• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.293-299
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• 2010

Vertically aligned ZnO nanorods on Si (111) substrate were prepared by hydrothermal method. The ZnO nanorods on spin-coated seed layer were synthesized at $140^{\circ}C$ for 6 hours in autoclave and were thermally annealed in argon atmosphere for 20 minutes at temperature of 300, 500, $700^{\circ}C$. The effects of the thermal annealing on the structural and optical properties of the grown on ZnO nanorods were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL). All the ZnO nanorods show a strong ZnO (002) and weak (004) diffraction peak, indicating c-axis preferred orientation. The residual stress of the ZnO nanorods is changed from compressive to tensile by increasing annealing temperature. The hexagonal shaped ZnO nanorods are observed. The PL spectra of the ZnO nanorods show a sharp near-band-edge emission (NBE) at 3.2 eV, which is generated by the free-exciton recombination and a broad deep-level emission (DLE) at about 2.12~1.96 eV, which is caused by the defects in the ZnO nanorods. The intensity of the NBE peak is decreased and the DLE peak is red-shifted due to oxygen-related defects by thermal annealing.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.187-198
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• 1988

The second leaves from 30 days old seedlings of two rice cultivars which were selected as tolerant (cv. Chokoto) and susceptible (cv. Weld pally) cultivar were soaked in the concentration of $10^{-6}$, $10^{-5}$, $10^{-4}$ and $10^{-3}M$ of oxyfluorfen for 10, 15 and 22hrs and anatomical characteristics were abserved. Dipping to the solutions were carried out either directly to the attached leaves or to the seperated leaves. Development of any symptoms in epidermis, bundle sheath, mesophyll cells and bulliform cells were microscopically inspected. Both cultivars showed reductionin leaf thickness, but the susceptible ones was more sensitive than the tolerant. The degradation and disappearance of epidermal cell layer, breakage of bundle sheath cells, shrinkage of mesophyll cells and disappearance of bulliform cells were general response as affected by oxyfluorfen treatment. The susceptible cultivars showed such responses at the concentration of $10^{-5}M$ for 10 hrs while tolerant ones $10^{-3}M$, for 10 hrs. Those treatments were more effective in seperated leaves than in attached ones. The epicuticular wax layer of leaves treated as above for 20 hrs was inspected by SEM. Weld pally, the susceptible cultivar (Weld pally) showed rapid cleavage of wax layer under $10^{-5}M$ concentration while the tolerant (Chokoto) showed only minor damage on wax layer at the concentration of $10^{-3}M$.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.159-164
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• 2012

Purpose: Of the various methods of vision training, the essay aims to explore the effective ways of using the Fresnel prism lens in order to expand the positive fusional vergence for the patient having specific condition of convergence insufficiency or basic exophoria. Methods: 15 students of city of Daejeon university without an eye disease (average age $22.73{\pm}1.68$) were selected and underwent the subjective refraction test and binocular vision test, and recording their test results before vision training and replacing an identical frame with a lens of same quality after the full calibration, the lens was then adhered with the Fresnel prism lens and continued to train for thirty minutes daily during two weeks. Afterwards, the binocular vision test was reattempted. The observation of the change in the results of the binocular vision test in use of the fresnel prism lens in the vision training test was researched. Results: After training, the positive fusional vergence had increased to a number of $22.27{\pm}2.26$ $\Delta$, to 7.80 $\Delta$, at near, the fused cross cylinder test increased to an average of $0.55{\pm}0.09$ D, 0.40 D after training, showing a normal result. The value of negative relative accommodation after training had an average of $2.22{\pm}0.08$D, showing that 0.42 D had increased. The value of near point of convergence after training had an average of $6.13{\pm}0.53$ cm, showing that 2.80 cm had decreased. To patients who had convergence insufficiency or basic exophoria, the value of the near vision test that used the Fresnel prism lens which was able to expand BO positive fusional vergence had increased without phoria. Conclusions: The changes were tested and the effectiveness of the Fresnel prism lens, due to the nature of the lens itself, helped with both cosmetic effects and cost. It also allows good optical correction effects, in addition to these clinical effects indicated before. Therefore, it may be determined that the Fresnel prism lens binocular vision therapy for patients is more popular and highly recommended.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.161-171
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• 2009

The present study was performed to describe the influence of water temperature and salinity on filtration rates of the venus clam, Gomphina veneriformis, a suspension-feeding (filter-feeding) bivalve species. The calmswere collected from the eastern coastal area of Sokcho, Gangneung and Jumunjin at Kangwon-do, Korea, during December 2006 and May 2007. Isochrysis galbana (KMCC H-002) cells as food organisms were indoor-cultured by f/2 medium, and were used to measure the filtration rate of clam. Filtration rates of clam were measured by indirect method. Cell concentration of food organisms were determined by direct counting cells used the hemacytometer under the light microscope. The filtration rates of clams by water temperature sharply increased with temperatures up to $15^{\circ}C$ as optimum temperature and above this temperature, the filtration rates decreased exponentially. Venus clams showed very low filtration rates at low salinity (10-15 psu) and maximum values at high salinity (30-35 psu). Regardless of water temperature and salt change, 2-year class clams showed high filtration rates, but low in 4-year-class. Polynomial regression curves with water temperature were shifted to the left in low temperature region. Thermal coefficient $Q_{10}$ values showed much higher values at low temperature range than at high temperature range, too. These results indicate that the venus clam is more sensitive in cold water. Polynomial regression curves with salinity were shifted to the right in high saline region. According to this study, the venus clam Gomphina veneriformis, subtidal filter-feeding bivalve, was the stenothermal organism, inhabited mainly in low temperature and the stenohaline, in high saline waters.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.1
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• pp.9-17
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• 2014

Purpose: The purpose of this study was to compare zirconia implants with titanium implants from the view point of biomechanical stability and histologic response on osseointegration when those were placed with xenograft materials. Materials and methods: Specimens were divided into two groups; the control group was experimented with eighteen titanium implants which had anodized surface and the experimental group was experimented with eighteen sandblasted zirconia (Y-TZP) implants. At the tibias of six pigs, implants were installed into bone defect sites prepared surgically and treated with resorbable membranes and bovine bone. Two pigs were sacrificed after 1, 4 and 12 weeks respectively. Each implant site was sampled and processed for histologic and histomorphometric analysis. The stability of implants was evaluated with a $Periotest^{(R)}$. And the interfaces between bone and the implant were observed with a scanning electron microscope. Results: In stability analysis there was no significant difference between Periotest values of the control group and the experimental group. In histologic analysis with a light microscope after 4 weeks, there was new bone formation with the resorption of bovine bone and the active synthesis of osteoblasts in both groups. In bone-implant contact percentage there was significant difference between both groups (P<.05). In bone area percentage there was no significant difference between both groups. In analysis of both groups with a scanning electron microscope there was a gap between bone and a surface at 4 weeks and it was filled up with bone formed newly at 12 weeks. Conclusion: When accompanied by xenograft using membrane, bone to implant contact percentage of zirconia implants used in this experiment was significantly less than that of the titanium implants by surface treatment of anodic oxidation. So, it is considered that the improvement of zirconia implant is needed through ongoing research on surface treatment methods for its practical use.

• The Korean Journal of Nuclear Medicine
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• v.38 no.4
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• pp.288-293
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• 2004

Purpose: increased uptake of wrist and hand joints in three phase bone scintigraphy (TPBS) have been used in the detection of reflex sympathetic dystrophy syndrome (RSDS). TPBS frequently shows increased shoulder uptake in the hemiplegic RSDS patients. We investigated the significance of the shoulder uptake in the detection of these patients. Materials and Methods: Twenty three patients who had hemiplegia due to brain stroke and diagnosed as RSD were enrolled in this study (M:F=16:7, R:L=11:12). The mean age was $63{\pm}10$ yrs. Ter normal volunteer (mean age: $60{\pm}5$, M:F=1:9) data was used as control group. TPBS was performed $59{\pm}32$ days after stoke (acute stage). We obtained the count ratios of bilateral hands by drawing a region of interest (ROI) in three phase images and compared to the count ratios of shoulders in the delayed image. Hand ROI included an ipsilateral wrist. Sensitivity of detecting the affected limb was defined using the right/left count ratio of normal control. Results: Sensitivities using count ratios of hand blood flow, blood pool and delayed image were 45%, 76% and 78%, respectively. Sensitivity of shoulder count ratio was 74%. Log of right/left counts of hand delayed image and that of shoulder delayed image were correlated well with statistical significance (Spearman's R=0.824, p<0.001). Conclusion: Shoulder uptake showed good correlation with hand uptake in the delayed image of TPBS. Shoulder uptake maybe helpful in the diagnosis of reflex sympathetic dystrophy syndrome in patients with hemiplegia.

• Journal of Conservation Science
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• v.31 no.1
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• pp.21-27
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• 2015

The Phoenix-shaped Glass Ewer, which is No. 193 National Treasure, was seriously damaged by a unique form of green glass pieces when excavated among a number of burial accessories of Hwangnamdaechong known to have been formed in the 5th century. While it has long been exhibited at the National Museum of Korea since its treatment for conservation treatment at conservation science laboratory in 1984, the existing adhesive materials seriously deteriorated for the 30 years, and the condition was quite unstable. The epoxy resin used as a restorative materials turned yellowing due to the light and heat so much that it was no longer able to exhibit it in a stable and effective manner. As a result, a re-treatment for conservation was conducted lately. This study focuses on the three pieces of Gold wires used to carefully wrap up the handle of the Phoenix-shaped Glass Ewer broken into three pieces, which has not been studied so far. As for the analysis method for Gold wires, SEM-EDS and Stereo Microscope were used for nondestructive analysis. First of all, the result of the SEM-EDS analysis shows that the composition was Au 91.9 wt.%-Au 92.8 w.t% and Ag 5.9 wt.%-Ag 6.5 wt.%, which indicates that it was an alloy made of Au and Ag. The production technique of Gold wires was also observed by means of optical microscopes. In general, Gold wires were manufactured by a drawing process in which a lump of gold was beaten or pulled out of a hole or by a process of twisting a gold plate. However, Gold wires separated from the handle of the Phoenix-shaped Glass Ewer did not involve any trace of twisting on the surface. Rather, fine vertical stripes were observed with the sections filled up. Hence, it is thought that this Ewer went through a drawing process and then was mended. As a result, no certain relation with the golden mending material used for the Phoenix-shaped Glass Ewer was verified. The findings above indicate that most of the existing researches on Gold wires recognized them, not as separate remains, but merely as a component of other golden remains. Thus, there has been little systematic study on the manufacturing techniques of Gold wires. The future study on Gold wires may verify the correlation between the Gold wires used to fix the handle of the Phoenix-shaped Glass Ewer, which is examined in this study, with that of golden remains in the Silla era.

• Korean Journal of Remote Sensing
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• v.38 no.5_2
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• pp.747-763
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• 2022

Ocean salinity affects ocean circulation on a global scale and low salinity water around coastal areas often has an impact on aquaculture and fisheries. Microwave satellite sensors (e.g., Soil Moisture Active Passive [SMAP]) have provided sea surface salinity (SSS) based on the dielectric characteristics of water associated with SSS and sea surface temperature (SST). In this study, a Light Gradient Boosting Machine (LGBM)-based model for generating high resolution SSS from Geostationary Ocean Color Imager (GOCI) data was proposed, having machine learning-based improved SMAP SSS by Jang et al. (2022) as reference data (SMAP SSS (Jang)). Three schemes with different input variables were tested, and scheme 3 with all variables including Multi-scale Ultra-high Resolution SST yielded the best performance (coefficient of determination = 0.60, root mean square error = 0.91 psu). The proposed LGBM-based GOCI SSS had a similar spatiotemporal pattern with SMAP SSS (Jang), with much higher spatial resolution even in coastal areas, where SMAP SSS (Jang) was not available. In addition, when tested for the great flood occurred in Southern China in August 2020, GOCI SSS well simulated the spatial and temporal change of Changjiang Diluted Water. This research provided a potential that optical satellite data can be used to generate high resolution SSS associated with the improved microwave-based SSS especially in coastal areas.

• Journal of the Korean Geotechnical Society
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• v.23 no.9
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• pp.5-16
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• 2007

The simple linear elastic-perfectly plastic model with soil parameters $s_u,\;E_u$ and n of undrained condition is usually applied to predict the displacement of a constructed diaphragm wall(DW) on soft soils during excavation. However, the application of this soil model for finite element analysis could not interpret the continued increment of the lateral displacement of the DW for the large and deep excavation area both during the elapsed time without activity of excavation and after finishing excavation. To study the characteristic behaviors of soil behind the DW during the periods without excavation, a series of tests on soft Bangkok clay samples are simulated in the same manner as stress condition of soil elements happening behind diaphragm wall by triaxial tests. Three kinds of triaxial tests are carried out in this research: $K_0$ consolidated undrained compression($CK_0U_C$) and $K_0$ consolidated drained/undrained unloading compression with periodic decrement of horizontal pressure($CK_0DUC$ and $CK_0UUC$). The study shows that the shear strength of series $CK_0DUC$ tests is equal to the residual strength of $CK_0UC$ tests. The Young's modulus determined at each decrement step of the horizontal pressure of soil specimen on $CK_0DUC$ tests decreases with increase in the deviator stress. In addition, the slope of Critical State Line of both $CK_0UC$ and $CK_0DUC$ tests is equal. Moreover, the axial and radial strain rates of each decrement of horizontal pressure step of $CK_0DUC$ tests are established with the function of time, a slope of critical state line and a ratio of deviator and mean effective stress. This study shows that the results of the unloading compression triaxial tests can be used to predict the diaphragm wall deflection during excavation.