• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.4
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• pp.230-241
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• 2020

Since the construction of Pohang New Port, the problems of the low harbor tranquility caused by decreasing port operation rate has been continuously reported. In order to improve the harbor tranquility, a detached breakwater (DB) has been constructed outside the outer breakwater of Pohang New Port in 2018~2020. In this study, the effectiveness of the DB was proved by comparing the reduction rates of wave heights that were observed before and after the construction of the DB. First, the observed data were compared with the numerical model results available from a previous study, and the model data showed reasonable agreement with measured data at 3 out of 4 locations inside the port. The discrepancy in one of the locations was because the model could not accurately calculated the effect of wave interference in the inner corner of the port. The observation data showed excellent results that the number of waves that exceeded 0.3 m, the critical value to reach desired harbor tranquility, was significantly reduced after the construction of the DB. In addition, the reduction rate, the ratio of wave heights between outside and inside of the port, was decreased after the DB construction, which proved that properly designed coastal structures such as DB in this study could be effective in improving the port tranquility. The results of this study can be usefully applied for solving problems in similar cases.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.12
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• pp.17-26
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• 1998

Ultrasonic sensors are widely used in various applications due to advantages of low cost, simplicity in construction, mechanical robustness, and little environmental restriction in usage. But for the application of object recognition, ultrasonic sensors exhibit several shortcomings of poor directionality which results in low spatial resolution of objects, and specularity which gives frequent erroneous range readings. The time-of-flight(TOF) method generally used for distance measurement can not distinguish small object patterns of plane, corner or edge. To resolve the problem, an increased number of the sensors in the forms of a linear array or 2-dimensional array of the sensors has been used. Also better resolution has been obtained by shifting the array in several steps using mechanical actuators. Also simple patterns are classified based on analyzing signal reflections. In this paper we propose a method of a sensor array system with improved capability in pattern distinction using electronic circuits accompanying the sensor array, and intelligent algorithm based on neuro-fuzzy processing of data fusion. The circuit changes transmitter output voltages of array elements in several steps. A set of different return signals from neighborhood sensors is manipulated to provide enhanced pattern recognition in the aspects of inclination angle, size and shift as well as distance of objects. The results show improved resolution of the measurements for smaller targets.

• Korean Journal of Veterinary Research
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• v.45 no.4
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• pp.469-475
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• 2005

Cytogenetic and hematological analysis was performed in peripheral blood obtained from pigs bred in the high background radiation areas (HBRA) (Cheongwon-gun and Boeun-gun) and a control area. The frequencies of gamma-ray induced micronuclei (MN) in the cytokinesis-blocked (CB) lymphocytes at several doses were measured in three pigs. An estimated dose of radiation was calculated by a best fitting linear-quadratic model based on the radiation-induced MN formation from the swine lymphocytes exposed in vitro to radiation over the range from 0 mGy to 1,969 mGy. The measurements performed after irradiation showed dose-related increases in the MN frequency in each donors. The results were analyzed using a linear-quadratic model with a line of best fit of $y=0.0005404D^2+0.04237D+0.00833$ [y = number of MN/cytokinesis-blocked (CB) cells and D = irradiation dose in Gy]. MN rates per 1,000 CB lymphocytes of pig from the HBRA (Cheongwon-gun, Boeun-gun) and the control area were $6.70{\pm}2.36$, $9.00{\pm}3.50$ and $11.00{\pm}2.98$, respectively. The MN frequencies of CB lymphocytes from pigs bred in three areas means that the values are within the background variation in this experiment. The MN frequencies and hematological values were similar regardless of whether the pigs were bred in the HBRA or the control area.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.189-193
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• 1981

An apparatus for continuous measurements of sorption isotherm of dried food was manufactured to shorten the time required for equilibration. The apparatus was so designed that the temperature, air velocity and relative humidity in the experimental chamber could be controlled. The use of dynamic stream of conditioned air with a velocity of 0.2m/sec, instead of static atmosphere, allowed a faster equilibration of dried filefish muscle at $25^{\circ}C$. The mean time necessary for the equilibration of dried filefish muscle at the water activity of a given state to a higher water activity was about 45 hours. The monolayer moisture content of dried filefish muscle calculated from BET-equation was 0.092 kg water /kg dry matter at $25^{\circ}C$.

• Korean Journal of Veterinary Research
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• v.42 no.1
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• pp.1-6
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• 2002

The frequencies of gamma-ray-induced micronuclei (MN) in cytokinesis-blocked (CB) lymphocytes at several doses were measured in three donors of three species (human, rabbit, dog). Measurements performed after irradiation showed a dose-related increases in MN frequency in each of the donors studied. When analysed by linear-quadratic model the line of best fit was : human : $y=0.1184D+0.01867D^2+0.01$, rabbit : $y=0.0387D+0.00528D^2+0.01$ (y = number of MN/CB cells and D = irradiation dose in Gy). The relative sensitivity of rabbit lymphocytes compared with human lymphocytes was estimated by best fitting linear-quadratic model based on the radiation-induced MN data over the range from 0 Gy to 4 Gy. In the case of MN frequency with 0.2, the relative sensitivities of rabbit lymphocytes was 0.39. These data indicate that the induction of MN in rabbit CB cells following irradiation was much less sensitive to the MN induction effects of gamma-irradiation than those from human. The MN assay with dog lymphocytes was very difficult and time-consumed because the dog PHA-stimulated lymphocytes yielded cultures with very low level of CB cells formation in the condition of this experiment. Our in vitro radiobiological study confirmed that the cytogenetic response obtained in blood from rabbit can be utilized for application in environmental studies.

• The Journal of Advanced Prosthodontics
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• v.11 no.5
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• pp.239-246
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• 2019

PURPOSE. The purpose of this study was to propose and assess a shade guide for pink gingival aesthetics using a Spanish population sample. MATERIALS AND METHODS. The $L^*$, $C^*$, h, $a^*$ and $b^*$ coordinates of 259 participants were measured using a spectrophotometer in 3 standardized points along the attached gingiva of the maxillary central incisors. A hierarchical clustering analysis was applied to obtain separate solutions regarding the number of shade tabs. For each of the solutions obtained, color differences (${\Delta}E^*$) were calculated using the CIELab and CIEDE2000 formulas, and the proposed shade guide was selected considering (1) the color differences between tabs and (2) the coverage error of each of the solutions. RESULTS. The proposed shade guide consisted of 8 gingival shade tabs and achieved CIELab and CIEDE2000 coverage errors of less than the respective 50:50% acceptability thresholds (${\Delta}E^*=4.6$ units and ${\Delta}E_{00}=4.1$). The coordinates for the various gingival shade tabs were as follows: Tab 1: $L^*43.3$, $a^*21.9$, $b^*12.3$ (1.6); Tab 2: $L^*42.9$, $a^*34.1$, $b^*19.1$; Tab 3: $L^*46.5$, $a^*25.8$, $b^*10.9$; Tab 4: $L^*46.5$, $a^*27.3$, $b^*15.1$; Tab 5: $L^*49.6$, $a^*23.5$, $b^*16.8$; Tab 6: $L^*51.5$, $a^*19.7$, $b^*13.6$; Tab 7: $L^*55.9$, $a^*22.0$, $b^*15.0$; and Tab 8: $L^*56.0$, $a^*19.9$, $b^*18.8$. CONCLUSION. The CIELab and CIEDE2000 coverage errors for the 8 shade tabs of the proposed gingival shade guide were significantly lower than those of other guides. Therefore, despite the limitations of this study, the proposed guide is more appropriate for matching gingival shade in the Spanish general population.

• Journal of Korean Dental Science
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• v.11 no.2
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• pp.71-81
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• 2018

Purpose: The purpose of this study was to investigate the corrosion behaviors of dental implant alloy after microsized surface modification in electrolytes containing Mn ion. Materials and Methods: $Mn-TiO_2$ coatings were prepared on the Ti-6Al-4V alloy for dental implants using a plasma electrolytic oxidation (PEO) method carried out in electrolytes containing different concentrations of Mn, namely, 0%, 5%, and 20%. Potentiodynamic method was employed to examine the corrosion behaviors, and the alternatingcurrent (AC) impedance behaviors were examined in 0.9% NaCl solution at $36.5^{\circ}C{\pm}1.0^{\circ}C$ using a potentiostat and an electrochemical impedance spectroscope. The potentiodynamic test was performed with a scanning rate of $1.667mV\;s^{-1}$ from -1,500 to 2,000 mV. A frequency range of $10^{-1}$ to $10^5Hz$ was used for the electrochemical impedance spectroscopy (EIS) measurements. The amplitude of the AC signal was 10 mV, and 5 points per decade were used. The morphology and structure of the samples were examined using field-emission scanning electron microscopy and thin-film X-ray diffraction. The elemental analysis was performed using energy-dispersive X-ray spectroscopy. Result: The PEO-treated surface exhibited an irregular pore shape, and the pore size and number of the pores increased with an increase in the Mn concentration. For the PEO-treated surface, a higher corrosion current density ($I_{corr}$) and a lower corrosion potential ($E_{corr}$) was obtained as compared to that of the bulk surface. However, the current density in the passive regions ($I_{pass}$) was found to be more stable for the PEO-treated surface than that of the bulk surface. As the Mn concentration increased, the capacitance values of the outer porous layer and the barrier layer decreased, and the polarization resistance of the barrier layers increased. In the case of the Mn/Ca-P coatings, the corroded surface was found to be covered with corrosion products. Conclusion: It is confirmed that corrosion resistance and polarization resistance of PEO-treated alloy increased as Mn content increased, and PEO-treated surface showed lower current density in the passive region.

• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.757-763
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• 2019

Recently, Following the recent development of flat panel detector with wide dynamic ranges, increasing numbers of healthcare providers have begun to use digital radiography. As a result, filter thickness standards should be reestablished, as current clinical practice requires the use of thicknesses recommended by the National Council on Radiation Protection and Measurements, which are based on information, acquired using conventional analog systems. Here we investigated the possibility of minimizing dose creep and optimizing patient dose using Al filters in digital radiography. The use of thicker Al filters resulted in a maximum 19.3% reduction in the entrance skin exposure dose when medical images with similar sharpness values were compared. However, resolution, which is a critical factor in imaging, had a significant change of 1.01 lp/mm. This change in resolution is thought to be due to the increased amount of scattered rays generated from the object due to the X-ray beam hardening effect. The increase in the number of scattered rays was verified using the scattering degradation factor. However, the FPD, which has recently been developed and is widely used in various areas, has greater response to radiation than analog devices and has a wide dynamic range. Therefore, the FPD is expected to maintain an appropriate level of resolution corresponding to the increase in the scattered-ray content ratio, which depends on filter thickness. Use of the FPD is also expected to minimize dose creep by reducing the exposure dose.

• Korean Journal of Radiology
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• v.22 no.5
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• pp.688-698
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• 2021

Objective: To compare the lumen parameters measured by the location-adaptive threshold method (LATM), in which the inter- and intra-scan attenuation variabilities of coronary computed tomographic angiography (CCTA) were corrected, and the scan-adaptive threshold method (SATM), in which only the inter-scan variability was corrected, with the reference standard measurement by intravascular ultrasonography (IVUS). Materials and Methods: The Hounsfield unit (HU) values of whole voxels and the centerline in each of the cross-sections of the 22 target coronary artery segments were obtained from 15 patients between March 2009 and June 2010, in addition to the corresponding voxel size. Lumen volume was calculated mathematically as the voxel volume multiplied by the number of voxels with HU within a given range, defined as the lumen for each method, and compared with the IVUS-derived reference standard. Subgroup analysis of the lumen area was performed to investigate the effect of lumen size on the studied methods. Bland-Altman plots were used to evaluate the agreement between the measurements. Results: Lumen volumes measured by SATM was significantly smaller than that measured by IVUS (mean difference, 14.6 mm³; 95% confidence interval [CI], 4.9-24.3 mm³); the lumen volumes measured by LATM and IVUS were not significantly different (mean difference, -0.7 mm³; 95% CI, -9.1-7.7 mm³). The lumen area measured by SATM was significantly smaller than that measured by LATM in the smaller lumen area group (mean of difference, 1.07 mm²; 95% CI, 0.89-1.25 mm²) but not in the larger lumen area group (mean of difference, -0.07 mm²; 95% CI, -0.22-0.08 mm²). In the smaller lumen group, the mean difference was lower in the Bland-Altman plot of IVUS and LATM (0.46 mm²; 95% CI, 0.27-0.65 mm²) than in that of IVUS and SATM (1.53 mm²; 95% CI, 1.27-1.79 mm²). Conclusion: SATM underestimated the lumen parameters for computed lumen segmentation in CCTA, and this may be overcome by using LATM.

• Korean Journal of Environmental Biology
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• v.18 no.2
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• pp.215-226
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• 2000

We evaluated the aquatic ecosystem of Keum-Ho River through applications of the Index of Biological Integrity (IBI) using fish assemblages and Qualitative Habitat Evaluation Index (QHEI) during June-November 1999. Overall IBI values ranged from 13 to 37 with mean of 23 (n=25, Std. error= 1.16), indicating a "Poor" or "Very Poor" condition according to the criteria of Karr (1981) and U.S. EPA (1993). The values of mean IBI declined at the rate of $0.22km^{-1}$(($r^2$=0.91, p< 0.05) along the longitudinal distance from the headwaters to the down-river. Reduced IBI values at down-river (St. 4 and 5) were attributed to the decreases in riffle benthic species and the relative abundance of insectivore and increases in tolerant species, anormalies and exotic species. Spatial pattern in IBI agreed with QHEI values, which showed a linear relation ($r^2$=0.998, p< 0.001) with mean number of species. Field measurements of conductivity and pH, indicators for variation of conservative ions, showed that the river water was diluted up to 30% by summer precipitation and surface run-off from the watershed, resulting in physical and chemical instability during the monsoon. For these reasons, average IBI values during monsoon and postmonsoon decreased more than 20% compared to pre -monsoon. Before the perturbation of the system (i.e., pre-monsoon), values of QHEI were inversely correlated (r=-0.99, p< 0.0001) with realtive abundance of native omnivore and were positively correlated (r=0.87, p=0.05) with relative abundance of native carnivore. These results indicate that spatial degradation of habitat quality modified the species richness and trophic structure, producing decreased IBI values. (Biological integrity, IBI, Monsoon, Habitat, River, Korea)bitat, River, Korea)