• Imaging Science in Dentistry
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• v.39 no.3
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• pp.115-120
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• 2009

Purpose : The purpose of this study was to determine a conversion coefficient for Hounsfield Units(HU) to material density ($g\;cm^{-3}$) obtained from cone-beam computed tomography ($CBMercuRay^{TM}$) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. Materials and Methods : CT Scanner Phantom (AAPM) equipped with CT Number Insert consists of five cylindrical pins of materials with different densities and teflon ring was scanned by using the $CBMercuRay^{TM}$ (Hitachi, Tokyo, Japan) volume scanner. The raw data were converted into DICOM format and the HU of different areas of CT number insert measured by using $CBWorks^{TM}$. Linear regression analysis and Student t-test were performed statistically. Results : There was no significant difference (P > 0.54) between real densities and measured densities. A linear regression was performed using the density, $\rho$($g\;cm^{-3}$), as the dependent variable in terms of the HU (H). The regression equation obtained was $\rho=0.00072H-0.01588$ with an $R^2$ value of 0.9968. Density values based on the Hounsfield scale was $1697.1{\pm}24.9\;HU$ in cortical bone, $526.5{\pm}44.4\;HU$ in trabecular bone, $2639.1{\pm}48.7\;HU$ in enamel, $1246.1{\pm}39.4\;HU$ in dentin of dental head phantom. Conclusion : CBCT provides an effective option for determination of material density expressed as Hounsfield Units.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.3
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• pp.65-72
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• 2011

Extensive computer simulations to account for the randomness in the process of seismic demand estimation have been a serious obstacle to the adoption of probabilistic performance assessments for the decision of applying seismic intervention schemes. In this study, a method for rapid fragility assessments based on a response database and the fragility contour method are presented. By the comparison of response contours in different formats, it is shown that representing maximum responses in ductility demand is better for the investigation of the effect of structural parameter changes on seismic demands than representations in absolute values. The presented fragility contour enables designers to practically investigate the probabilistic performance level of every possible retrofit option in a convenient manner using visualized data sets. This example demonstrates the extreme efficiency of the proposed approach in performing fragility assessments and successful application to the seismic retrofit strategies based on limit state probabilities.

• Journal of Korean Society on Water Environment
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• v.37 no.1
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• pp.47-54
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• 2021

Aerobic granular sludge (AGS) can be classified as a type of self-immobilized microbial aggregates measuring more than 0.2 mm. It offers the option to simultaneously remove COD, N, and P that occur in different zones inside a granule. Also, AGS is characterized by high precipitability, treatability with high organic loading, and high tolerance to low temperature. In this study, a sequencing batch reactor inoculated with AGS (AGS-SBR) is a new advanced wastewater treatment process that was proven to grow AGS with integrated nutrient removal and low C/N ratio. A pilot plant, AGS-SBR with a capacity of 225 ㎥/d was installed at an S sewage treatment plant in Gyeonggi-do. The results of the operation showed that the water quality of the effluent indicated that the value of BOD5 was 1.5 mg/L, CODMn was 11.4 mg/L, SS was 6.2 mg/L, T-N was 13.2 mg/L, and T-P was 0.197 mg/L, and all of these values reliably satisfied an effluent standard (I Area). In winter, the T-N treatment efficiency at a lower temperature of less than 11℃ also showed reliability to meet the effluent standard of the I Area (20 mg/L or less). Analysis of microbial community in AGS showed a higher preponderance of beneficial microorganisms involved in denitrification and phosphorus accumulation compared with activated sludge. The power consumption and sludge disposal cost were reduced by 34.7% and 54.9%, respectively, compared to the domestic SBR type sewage treatment plant with a processing capacity of 1,000 ㎥/d or less.

• Journal of Climate Change Research
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• v.7 no.3
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• pp.351-356
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• 2016

The carbon capture and storage (CCS), which collects and stores carbon dioxide in a geological site, is a promising option to mitigate climate change. However, there is the possibility of carbon dioxide leakage from the soil in the steps of collecting, transporting, and storing. To ensure the feasibility of this technology, it is important to monitor the leakage of carbon dioxide and to assess the potential impacts. As plants are sensitive to the changes in carbon dioxide in the soil environment, we can utilize plant parameter to detect the carbon dioxide leakage. Currently, chlorophyll a content is a conventional index indicating the changes in plants, however, this method is labor intensive and it only utilizes a small portion of leaves. To overcome its limitations, a simple spectroscopic parameter, DGCI (dark green color index), was suggested as an easy and quick indicator. In this study, we compared the values of chlorophyll a contents with DGCI from the experiment investigating the impacts of high underground $CO_2$ on grape plants. Results suggest that DGCI had high correlation with chlorophyll a contents and it has high potential to be utilized as an easy indicator to monitor plants' responses to $CO_2$ treatment.

• Translational and Clinical Pharmacology
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• v.26 no.4
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• pp.166-171
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• 2018

Although there are many commercially available training software programs for pharmacokinetics, they lack flexibility and convenience. In this study, we develop simulation software to facilitate pharmacokinetics education. General formulas for time courses of drug concentrations after single and multiple dosing were used to build source code that allows users to simulate situations tailored to their learning objectives. A mathematical relationship for a 1-compartment model was implemented in the form of differential equations. The concept of population pharmacokinetics was also taken into consideration for further applications. The source code was written using R. For the convenience of users, two types of software were developed: a web-based simulator and a standalone-type application. The application was built in the JAVA language. We used the JAVA/R Interface library and the 'eval()' method from JAVA for the R/JAVA interface. The final product has an input window that includes fields for parameter values, dosing regimen, and population pharmacokinetics options. When a simulation is performed, the resulting drug concentration time course is shown in the output window. The simulation results are obtained within 1 minute even if the population pharmacokinetics option is selected and many parameters are considered, and the user can therefore quickly learn a variety of situations. Such software is an excellent candidate for development as an open tool intended for wide use in Korea. Pharmacokinetics experts will be able to use this tool to teach various audiences, including undergraduates.

• Archives of Craniofacial Surgery
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• v.20 no.1
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• pp.10-16
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• 2019

Background: Physicians tend to overcorrect when applying the acellular dermal matrix for reconstructive option because of volume decrement problem after absorption comparing with initial volume. However, there are no studies on the exact volume decrement and absorption rate with commercial products in South Korea. To figure out absorption rate of acellular dermal matrix product in South Korea (Megaderm), authors designed this experiment. Methods: Nine mice were used and randomly divided into three groups by the time with sacrificing. The implant (Megaderm) was tailored to fit a cuboid form ($1.0cm{\times}1.0cm$ in length and width and 2.0 mm in thickness). A skin incision was made at anterior chest with blade #15 scalpel with exposing the pectoralis major muscle. As hydrated Megaderm was located upon the pectoralis major muscle, the skin was sutured with Ethilon #5-0. After the surgical procedure, each animal group was sacrificed at 4, 8, and 12 weeks, respectively, for biopsies and histological analysis of the implants. All samples were stained with routine hematoxylin and eosin staining and Masson's trichrome staining and the thickness were measured. A measurements were analyzed using Friedman test. Statistically, the correlation between thicknesses of Megaderm before and after implantation was analyzed. Results: After sacrificing the animal groups at postoperative 4, 8, 12 weeks, the mean tissue thickness values were $2.10{\pm}1.03mm$, $2.17{\pm}0.21mm$, and $2.40{\pm}0.20mm$ (p= 0.368), respectively. The remaining ratios after absorption comparing with after initial hydrated Megaderm were 82.7%, 85.4%, and 94.5%, respectively. In histopathological findings, neovascularization and density of collagenous fiber was increased with time. Conclusion: Author's hypothesis was absorption rate of implant would be increased over time. But in this experiment, there is no statistical significance between mean absorption thickness of implant and the time (p= 0.368). Also it can be affected by graft site, blood supply, and animals that were used in the experiment.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.4
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• pp.274-278
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• 2020

Pig slurry (PS) is the most applicable recycling option as an alternative organic fertilizer. The application of pig slurry has the risk of air pollution via atmospheric ammonia (NH3) and nitrous oxide (N2O) emission. The zeolite has a porous structure that can accommodate a wide variety of cations, thus utilizing for the potential additive of deodorization and gas adsorption. This study aimed to investigate the possible roles of zeolite in mitigating NH3 and N2O emission from the pig slurry applied to the maize cropping. The experiment was composed of three treatments: 1) non-N fertilized control, 2) pig slurry (PS) and 3) pig slurry mixed with natural zeolite (PZ). Both of NH3 and N2O emission from applied pig slurry highly increased by more than 3-fold compared to non-N fertilized control. The NH3 emission from the pig slurry was dominant during early 14 days after application and 20.1% of reduction by zeolite application was estimated in this period. Total NH3 emission through whole period of measurement was 0.31, 1.33, and 1.14 kg ha-1. Nitrous oxide emission in the plot applied with pig slurry was also reduced by zeolite treatment by 16.3%. Significant increases in forage and ear yield, as well as nutrient values were obtained by pig slurry application, while no significant effects of zeolite were observed. These results indicate that the application of zeolite and pig slurry efficiently reduces the emission of ammonia and nitrous oxide without negative effects on maize crop production.

• Journal of Audiology & Otology
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• v.24 no.1
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• pp.29-34
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• 2020

Background and Objectives: Bilateral microphones with contralateral routing of signal (BiCROS) hearing aid is an option for hearing rehabilitation in individuals with asymmetric sensorineural hearing loss (ASNHL). The clinical factors influencing the trial and purchase of BiCROS were investigated. Subjects and Methods: We reviewed the medical records of 78 patients with ASNHL who were recommended to use BiCROS and analyzed the demographic and audiological factors influencing the trial and purchase of BiCROS. Results: Among the 78 patients, 52 (66.7%) availed of the free BiCROS trial and 21 (26.9%) purchased BiCROS. The mean pure tone audiometry (PTA) air conduction (AC) threshold of the better- and worse-hearing ears were 44.2±12.8 dB and 90.7±22.5 dB HL, respectively. The decision for trial or purchase of BiCROS was not influenced by age, sex, duration of hearing loss of the worse-hearing ear, or PTA AC threshold or speech discrimination score of both ears. The first and third quartiles of the PTA AC thresholds for the better-hearing ear of BiCROS buyers were 38.75 dB and 53.75 dB HL, respectively. The counterpart values for the worse-hearing ear were 72.50 dB and 118.75 dB HL, respectively. Conclusions: The clinical factors analyzed in this study were found to be irrelevant to the trial and purchase of BiCROS in patients with ASNHL. Nevertheless, the distribution range of the auditory thresholds of the subjects using BiCROS can be a useful basis for the counseling of patients with ASNHL and selection of candidates for BiCROS use.

• Korean Journal of Agricultural Science
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• v.49 no.3
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• pp.431-440
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• 2022

Hanwoo cattle are a unique and historical breed in Korea that have been genetically improved and maintained by the national evaluation and selection system. The aim of this study was to provide information that can help improve the accuracy of the estimated breeding values in Hanwoo cattle by showing the difference between the imputation reference chip platforms of genomic data and the scaling factor of the genetic relationship matrix (GRM). In this study, nine sets of data were compared that consisted of 3 reference platforms each with 3 different scaling factors (-0.5, 0 and 0.5). The evaluation was performed using MTG2.0 with nine different GRMs for the same number of genotyped animals, pedigree, and phenotype data. A five multi-trait model was used for the evaluation in this study which is the same model used in the national evaluation system. Our results show that the Hanwoo custom v1 platform is the best option for all traits, providing a mean accuracy improvement by 0.1 - 0.3%. In the case of the scaling factor, regardless of the imputation chip platform, a setting of -1 resulted in a better accuracy increased by 0.5 to 1.6% compared to the other scaling factors. In conclusion, this study revealed that Hanwoo custom v1 used as the imputation reference chip platform and a scaling factor of -0.5 can improve the accuracy of the estimated breeding value in the Hanwoo population. This information could help to improve the current evaluation system.

• Ocean and Polar Research
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• v.44 no.3
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• pp.235-247
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• 2022

A marine protected area (MPA) is a spatially designated section of the ocean where the biodiversity is high. Munseom MPA has a unique underwater landscape including soft coral, subtropical fish, and benthos, attracting many scuba divers. This paper intends to evaluate the willingness-to-pay (WTP) for the scuba diving management policy in the Munseom MPA. As a stated preference valuation method, a choice experiment was applied to assess divers' preferences with economic values for the policy. The attributes used in the study included zoning (temporal closure), conservation education, daily permit, soft coral area, and diving fee. We collected 333 questionnaires through online and field surveys and used 296 after excluding incomplete responses for the final data analysis. Study results show that a six-month closure, a decrease in soft coral habitat, and the diving fee were statistically significant. A positive coefficient with regard to the six-month closure variable indicates that divers preferred the policy, and the marginal willingness to pay (MWTP) was estimated to be KRW 8,637 per person per dive. The aggregate WTP of KRW 233 million was obtained by multiplying the MWTP by the number of visiting divers per year. When comparing the levels of recreation specialization, more skilled divers preferred the management option. The results of this study will help predict the priority of management measures and the levels of acceptability among divers when diving management is implemented in Korea in the future. This study suggests that marine environmental policies need to consider divers as one of the important stakeholders for marine conservation.