• The Journal of Advanced Prosthodontics
• /
• v.10 no.3
• /
• pp.218-226
• /
• 2018

PURPOSE. The aim of this study was to define a color space of non-vital teeth and to compare it with the color space of matched vital teeth, recorded in the same patients. MATERIALS AND METHODS. In a group of 218 patients, with the age range from 17 to 70, the middle third of the buccal surface of 359 devitalized teeth was measured using a clinical spectrophotometer (Vita Easyshade Advance). Lightness ($L^*$), chromatic parameters ($a^*$, $b^*$), chroma ($C^*$), hue angle (h) and the closest Vita shade in Classical and 3D Master codifications were recorded. For each patient, the same data were recorded in a vital reference tooth. The measurements were performed by the same operator with the same spectrophotometer, using a standardized protocol for color evaluation. RESULTS. The color coordinates of non-vital teeth varied as follows: lightness $L^*$: 52.83-92.93, $C^*$: 8.23-58.90, h: 51.20-101.53, $a^*$: -2.53-24.80, $b^*$: 8.10-53.43. For the reference vital teeth, the ranges of color parameters were: $L^*$: 60.90-97.16, $C^*$: 8.43-39.23, h: 75.30-101.13, $a^*$: -2.36-9.60, $b^*$: 8.36-39.23. The color differences between vital and non-vital teeth depended on tooth group, but not on patient age. CONCLUSION. Non-vital teeth had a wider color space than vital ones. Non-vital teeth were darker (decreased lightness), more saturated (increased chroma), and with an increased range of the hue interval. An increased tendency towards positive values on the $a^*$ and $b^*$ axes suggested redder and yellower non-vital teeth compared to vital ones.

• Journal of Korean Society for Geospatial Information Science
• /
• v.20 no.2
• /
• pp.15-22
• /
• 2012

The variation in the wind speed with height above ground is called the wind shear profile. In the field of wind resource assessment, analysts typically use one of two mathematical relations to characterize the measured wind shear profile: the logarithmic profile (log law) and the power law profile (power law). The logarithmic law uses the surface roughness as a parameter, and the power law uses the power law exponent as a parameter. The shape of the wind shear profile typically depends on several factors, most notably the roughness of the surrounding terrain and the stability of the atmosphere. Since the atmospheric stability changes with season, time of day, and meteorological conditions, the surface roughness and the power law exponent also tends to change in time. For this study, Using the observed data from Met-mast, located in Pyeongdae, Handong in Jeju. we used the matlab and windograper to calculate roughness length and the law exponents. These calculations are similar to reference the data, but they have different ranges. In the ocean case, each reference data and calculated data was the same, but the crop area is higher than the earlier studies. In addition, the agricultural village is lower than the earlier studies.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.28 no.5
• /
• pp.312-317
• /
• 2016

The submersion and emersion patterns are key factors that directly influence the habitat environment of the coastal plants and animals. In this study, the coasts are divided into five zones (zones 1, 2, 3, 4, and 5 - not flooded, flooded once, flooded and exposed to air twice, exposed to air once, continuously flooded in the day, respectively) based on the patterns using tidal elevation data at the major eight stations and the domestic and international reference tidal levels, i.e., AHHW, ALLW, HAT and LAT, are also estimated to analyse the characteristics of the five distinct zones. Based on the results, the frequency of the zone 3 are dominant and forms from 87.2% to 88.2% (nearly constant) irrelevant with the tidal ranges at all stations. The taking-up percentages of the zones 2 and 4 show nearly constant, below 4% and over 8%, respectively. In Pohang station classified as the mainly diurnal tide, the percentages are decreased to 1.4% in zone 2 and increased to 10.8% due to the effects of the annual and semi-annual tidal components.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.22 no.3
• /
• pp.175-183
• /
• 2012

Objectives: This study developed a harmonized method for risk assessment based on the Hazard & Risk Evaluation of Chemicals (HREC) according to the Industrial Safety and Health Act (ISHA). Methods: Three preliminary studies, performed during 2010 and 2011 by the Occupational Safety and Health Research Institute and three academic research groups, were compared. The differences in risk assessment, especially in the dose-response assessment method, were analyzed. A new harmonized method for dose-response assessment was suggested and its applicability for the HREC was examined. Results: Considering the various steps of each dose-response assessment, the equivalent steps in quantitative correction, uncertainty factor 2 (UF2) for intra-species uncertainty, and UF3 for the experimental period in the uncertainty correction were relatively high. Using our new method, the total correction values (quantitative correction plus uncertainty correction) ranged from 72~15,789 to 30~60, and the ratio of the threshold limit value (TLV) to the reference concentration decreased from 12.8~1900 to 5.4~11.8. Furthermore, when we performed risk characterization by our new method, hazard quotient (HQ) values for chloroethylene, epichlorohydrin, and barium sulfate became 3.0, 14.1, and 1.13 respectively, whereas three previous studies reported HQ values of 7.1, 4580, and 87.3 considering reasonable maximum exposure (RME) conditions. HQs of the three chemicals were calculated to be 0.6, 2.4, and 0.1 respectively, when compared to their TLVs. Conclusions: Our new method could be applicable for the HREC because the total correction values and the ratio of TLVs were within reasonable ranges. It is also recommended that additional risk management measures be applied for epichlorohydrin, for which the HQ values were greater than 1 when compared with both reference values and the TLV. Our proposed method could be used to harmonize dose-response assessment methods for the implementation of risk assessment based on the HREC according to ISHA.

• Journal of Radiation Industry
• /
• v.5 no.4
• /
• pp.337-345
• /
• 2011

In order to provide an effective preparedness for a nuclear or radiological emergency happening in the domestic or neighborhood countries and to solve the vague fear of the people for the ingestion of radioactive livestock products, the establishment of national guideline level for radionuclides in feed is urgently necessary. This is because it is important to secure the safety and to manage the crisis in the agricultural, fishery and food sector by performing the effective safety control during and after nuclear incident. This study was performed to investigate the report cases of international organizations and foreign countries to set up a domestic control standard for managing radioactive substances that may be contaminated in animal feeds due to the nuclear power plant incident. In addition, an attempt was made to provide a useful reference that can help prepare a domestic control standard, using a coefficient that can consider the transfer into livestock through the intake of radioactive contaminated animal feeds. The standard radioisotopes investigated were confined to radioactive cesium ($^{137+134}Cs$) and iodine ($^{131}I$). Guideline level for the radionuclides was calculated by using the transfer coefficient factor and the maximum daily intake of animal feed provided by IAEA. For example, the maximum daily intake of animal feed was set as $25kg\;d^{-1}$ for dairy cows, $10kg\;d^{-1}$ for beef cattle, $3.0kg\;d^{-1}$ for pigs and $0.15kg\;d^{-1}$ for chickens. The result values for radioactive cesium were calculated as $8,696Bq\;kg^{-1}$, $4,545Bq\;kg^{-1}$, $1,667Bq\;kg^{-1}$ and $2,469Bq\;kg^{-1}$, respectively. The results for radioactive iodine showed the ranges between $741Bq\;kg^{-1}$ and $76,628Bq\;kg^{-1}$. These data can be utilized as a scientific reference for the preparation of a crisis management manual for the emergency control due to nuclear power plant accident in Korea and neighboring country. These results will contribute to establish the safe feed management system at national level as manual for responding the radioactive exposure of agricultural products and animal feeds, which are currently not established.

• Korean Journal of Remote Sensing
• /
• v.34 no.6_3
• /
• pp.1427-1443
• /
• 2018

Object-based image analysis (OBIA) allows higher computation efficiency and usability of information inherent in the image, as it reduces the complexity of the image while maintaining the image properties. Superpixel methods oversegment the image with a smaller image unit than an ordinary object segment and well preserve the edges of the image. SLIC (Simple linear iterative clustering) is known for outperforming the previous superpixel methods with high image segmentation quality. Although the input parameter for SLIC, number of superpixels has considerable influence on image segmentation results, impact analysis for SLIC parameter has not been investigated enough. In this study, we performed optimal parameter analysis and evaluation of change detection for SLIC-based superpixel techniques using KOMPSAT data. Forsuperpixel generation, three superpixel methods (SLIC; SLIC0, zero parameter version of SLIC; SNIC, simple non-iterative clustering) were used with superpixel sizes in ranges of $5{\times}5$ (pixels) to $50{\times}50$ (pixels). Then, the image segmentation results were analyzed for how well they preserve the edges of the change detection reference data. Based on the optimal parameter analysis, image segmentation boundaries were obtained from difference image of the bi-temporal images. Then, DBSCAN (Density-based spatial clustering of applications with noise) was applied to cluster the superpixels to a certain size of objects for change detection. The changes of features were detected for each superpixel and compared with reference data for evaluation. From the change detection results, it proved that better change detection can be achieved even with bigger superpixel size if the superpixels were generated with high regularity of size and shape.

• Archives of Plastic Surgery
• /
• v.50 no.4
• /
• pp.370-376
• /
• 2023

Background The posterior ledge (PL) is a vital structure that supports the implant posteriorly during orbital floor reconstruction. This study describes a technique for mapping the PL in relation to the infraorbital margin (IM) in patients with orbital floor blowout fractures. This study establishes the location of the optic foramen in relation to the PL. Methods Facial computed tomography (FCT) scans of 67 consecutive patients with isolated orbital floor blowout fractures were analyzed using Osirix. Planes of reference for orbital fractures, a standardized technique for performing measurements on FCT, was used. Viewed coronally, the orbit was divided into seven equal sagittal slices (L1 laterally to L7 medially) with reference to the midorbital plane. The distances of PL from IM and location of optic foramen were determined. Results The greatest distance to PL is found at L5 (median: 30.1 mm, range: 13.5-37.1 mm). The median and ranges for each slice are as follows: L1 (median: 0.0 mm, range: 0.0-19.9 mm), L2 (median: 0.0 mm, range: 0.0-21.5 mm), L3 (median: 15.8 mm, range: 0.0-31.7 mm), L4 (median: 26.1 mm, range: 0.0-34.0 mm), L5 (median: 30.1 mm, range: 13.5-37.1 mm), L6 (median: 29.0 mm, range: 0.0-36.3 mm), L7 (median: 20.8 mm, range: 0.0-39.2 mm). The median distance of the optic foramen from IM is 43.7 mm (range: 37.0- 49.1) at L7.

• Journal of Radiation Protection and Research
• /
• v.47 no.4
• /
• pp.237-245
• /
• 2022

Background: The current study reports measurements of activity concentrations of radon (²²⁰Rn) and thoron (²²⁰Rn) in dwellings, followed by inhalation dose assessment of the public, and then by the development of regulation and the national radon action plan (NRAP) in Cameroon. Materials and Methods: Radon, thoron, and thoron progeny measurements were carried out from 2014 to 2017 using radon-thoron discriminative detectors (commercially RADUET) in 450 dwellings and thoron progeny monitors in 350 dwellings. From 2019 to 2020, radon track detectors (commercially RADTRAK) were deployed in 1,400 dwellings. It was found that activity concentrations of radon range in 1,850 houses from 10 to 2,620 Bq/㎥ with a geometric mean of 76 Bq/㎥. Results and Discussion: Activity concentrations of thoron range from 20 to 700 Bq/㎥ with a geometric mean of 107 Bq/㎥. Thoron equilibrium factor ranges from 0.01 to 0.6, with an arithmetic mean of 0.09 that is higher than the default value of 0.02 given by UNSCEAR. On average, 49%, 9%, and 2% of all surveyed houses have radon concentrations above 100, 200, and 300 Bq/㎥, respectively. The average contribution of thoron to the inhalation dose due to radon and thoron exposure is about 40%. Thus, thoron cannot be neglected in dose assessment to avoid biased results in radio-epidemiological studies. Only radon was considered in the drafted regulation and in the NRAP adopted in October 2020. Reference levels of 300 Bq/㎥ and 1,000 Bq/㎥ were recommended for dwellings and workplaces. Conclusion: Priority actions for the coming years include the following: radon risk mapping, promotion of a protection policy against radon in buildings, integration of the radon prevention and mitigation into the training of construction specialists, mitigation of dwellings and workplaces with high radon levels, increased public awareness of the health risks associated with radon, and development of programs on the scientific and technical aspects.

• Annals of Occupational and Environmental Medicine
• /
• v.35
• /
• pp.41.1-41.11
• /
• 2023

Background: Shift work has been reported to have several harmful effects on the human body. However, a small number of studies have evaluated the association between shift work and adverse effects on the thyroid. In our longitudinal study, we examined the causal association between shift work and the risk of hypothyroidism. Methods: A Kangbuk Samsung Cohort Study was conducted on 112,648 men without thyroid disease at baseline who were followed up at least once between 2012 and 2019. Shift work status and shift schedule types were categorized using standardized questionnaires. Hypothyroidism was defined using the reference ranges of serum thyroid-stimulating hormones and free thyroxine levels. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident hypothyroidism were estimated using Cox proportional hazards regression analyses with the daytime work group as the reference. Results: During the 501,237 person-years of follow-up, there were 6,306 incident cases of hypothyroidism (incidence density, 1.26 per 100 person-years). The multivariable-adjusted HR of incident hypothyroidism for the shift work total group that included all shifts compared with the daytime work group was 1.27 (95% CI: 1.15-1.40). For the fixed evening, fixed night, rotating shift, and other shift workers, the multivariable-adjusted HRs (95% CI) were 1.11 (0.76-1.61), 2.18 (1.20-3.93), 1.39 (1.23-1.56), and 1.00 (0.82-1.22), respectively. In subgroup analyses by age, the association between shift work and hypothyroidism was more pronounced in younger participants (< 40 years; HR: 1.31; 95% CI: 1.16-1.47). Conclusions: Our large-scale cohort study showed an association between shift work and the incidence of hypothyroidism, especially in younger workers with night shifts.

• Journal of Environmental Impact Assessment
• /
• v.6 no.2
• /
• pp.35-59
• /
• 1997

In this study, for the effective environmental investigation at the level of planning, environmental assessment model to be integrated with urban comprehensive plans was developed. This model was applied to the Suwon City urban comprehensive plan and was tested to derive the future application program and the adaptability to the current research issues. The results of this study can be summarized as follows: First, we defined basic items for environmental assessment as to be used in the developed SEA model. We also defined three ranges and twelve items for the environmental assessments, which can be used in the assessment of the urban comprehensive plan through the expert advices. Second, we performed the case study by applying the developed SEA model to the Suwon City urban comprehensive assessment, and investigated the environmental impacts through an expert inquiry at the "phase 5" of the model. The results of the case study showed that Suwon City urban comprehensive plan contained partially discrepancies at the goal of the planning. The spatial strategy for leisure, park and open space, and green belt was analysed not to be effective in energy use. The case study also indicated that the environments of Suwon City are expected to be much worse in each sectional plan, if the City was to implement the present five sectional plans for life boundary and distribution of population, land use plan, transportation plan, industrial development plan, and life environmental plan. Third, according to the result of the case study, an mitigation plan for urban comprehensive plan of Suwon City was proposed as the following four stages; modification of planning goal, modification of site alternatives, modification of planning contents, and proposal of mitigation measures.