• Imaging Science in Dentistry
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• v.52 no.4
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• pp.393-398
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• 2022

Purpose: This study proposed a generative adversarial network (GAN) model for T2-weighted image (WI) synthesis from proton density (PD)-WI in a temporomandibular joint(TMJ) magnetic resonance imaging (MRI) protocol. Materials and Methods: From January to November 2019, MRI scans for TMJ were reviewed and 308 imaging sets were collected. For training, 277 pairs of PD- and T2-WI sagittal TMJ images were used. Transfer learning of the pix2pix GAN model was utilized to generate T2-WI from PD-WI. Model performance was evaluated with the structural similarity index map (SSIM) and peak signal-to-noise ratio (PSNR) indices for 31 predicted T2-WI (pT2). The disc position was clinically diagnosed as anterior disc displacement with or without reduction, and joint effusion as present or absent. The true T2-WI-based diagnosis was regarded as the gold standard, to which pT2-based diagnoses were compared using Cohen's ĸ coefficient. Results: The mean SSIM and PSNR values were 0.4781(±0.0522) and 21.30(±1.51) dB, respectively. The pT2 protocol showed almost perfect agreement(ĸ=0.81) with the gold standard for disc position. The number of discordant cases was higher for normal disc position (17%) than for anterior displacement with reduction (2%) or without reduction (10%). The effusion diagnosis also showed almost perfect agreement(ĸ=0.88), with higher concordance for the presence (85%) than for the absence (77%) of effusion. Conclusion: The application of pT2 images for a TMJ MRI protocol useful for diagnosis, although the image quality of pT2 was not fully satisfactory. Further research is expected to enhance pT2 quality.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.447-456
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• 2023

Even after 2000, oil prices rose enough to be comparable to the past, but the impact on economic variables was relatively stable. Therefore, this study tries to empirically examine that the response of the Korean economy to oil prices has changed since the 1998 financial crisis, when there was a structural change in the Korean economy. Through empirical analysis, it was tested that the influence of oil prices and producer prices on consumer prices had changed in the period before and after 1998, and that the influence of producer prices on the value-added ratio by industry sector also changed. This means that the transfer of the increase in production cost to consumer prices has been alleviated, and the impact on added value has also been alleviated. Various studies should be conducted to understand the causes of the empirical results, such as changes in the relationship between producer prices and consumer prices, factors in the industrial sector due to rising oil prices, and changes in products.

• Journal of the Korean Institute of Gas
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• v.27 no.1
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• pp.78-85
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• 2023

Fixed-bed reactor Computational Fluid Dynamics (CFD) simulation of methanol steam reforming reaction was performed using the intrinsic kinetic data of the copper-impregnated hydrotalcite catalyst. The activation energy of the copper hydrotalcite catalyst obtained from the previous study results was 97.4 kJ/mol, and the pre-exponential was 5.904 × 10¹⁰. Process simulation was performed using the calculated values and showed a similar tendency to the experimental results. And the conversion rate according to the change of the reaction temperature (200 - 450 ℃) and the molar ratio of methanol and water was observed using the intrinsic kinetic data. In addition, mass and heat transfer phenomena analysis of a commercial reactor (I.D. 0.05 - 0.1m, Length 1m) was predicted through axial 2D Symmetry simulation using the power law model of the above kinetic constants.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3D
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• pp.399-405
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• 2008

Development of the paved track is required as a low-maintenance of conventional line. The paved tracks are one of the types of the ballast reinforced tracks those are manufactured by adopting the prepacked concrete technique. The main elements of this tracks are large sleeper, low elastic pad, fastener, cement mortar, geotextile and recycled ballast. Low elastic pad is the most effective element of such tracks on the basis of stress-displacement characteristics, dynamic response and fatigue characteristics. The stiffness of the pad determine the stiffness of the track. Consequently, it is more important in case of concrete track structure such as paved track because application of low elastic pad seriously effect the durability and stability of the track. The main objective of this study is to confirm the reduction of train load, which transfer to roadbed through various pad effects. To achieve this task static, numerical analysis and real scale repeated loading test was performed while load reduction effect of low elastic pad was analyzed by using displacement, stress and strain ratio characteristics of the paved track.

• Archives of Craniofacial Surgery
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• v.25 no.1
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• pp.22-26
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• 2024

Background: This study analyzed the demographic characteristics of patients with facial palsy who were treated using either dynamic or static procedures. This study aimed to compare the frequency of procedure implementation and age distribution between the two groups. Methods: This study retrospectively analyzed the medical records of patients treated for facial palsy at a single institution from 2014 to 2022. Among cases included in our study, dynamic procedures involved cross-facial nerve graft and latissimus dorsi or gracilis muscle flap transfer. Static procedures included gold weight insertion, canthopexy, browlift, and thread lift/static slings. Results: Among the 31 patients included in our study, eight (25.8%) incorporated dynamic techniques, and the average age of patients was 44.75 years (range, 24-68 years) with a male to female ratio of 1:4. The remaining 23 patients (74.2%) underwent a static procedure, of which the average age was 59.17 years (range, 23-81 years) which was statistically significantly higher than the average age of 44.75 of dynamic patients (p= 0.013). Regarding the timing of treatment after diagnosis, no patient underwent dynamic procedures more than 20 years after initial diagnosis. A greater diversity in the timing of treatment was observed in the static group. All patients who underwent dynamic procedures were treated using static procedures during the study period. Conclusion: Because aesthetics-based static techniques are typically quick outpatient procedures that can be performed under local anesthesia, our study shows that these are often preferred treatments for all age groups, especially for debilitated or older patients. Further research is required to investigate the long-term functional outcomes of these surgical techniques in a wider population of patients.

• Advances in materials Research
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• v.13 no.3
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• pp.161-171
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• 2024

This study aimed to investigate the effect of physicochemical properties and mix ratios of iron ore (oxide feed): coke (reductant) on the carbothermic reductions of iron ore. Coke size was fixed at ≤63 ㎛ while iron ore size varied between 150-63 ㎛ and ≤63 ㎛ respectively. Mix ratios were changed from 100:0 (reference) to 80:20 and 60:40 while the temperature, heating rate and soaking duration in muffle furnace were fixed at 1100 ℃, 10 ℃/min and 1 hour. Particle size analyzer, XRF, CHNS and XRD analyses were used for determination of raw feed characteristics. The occurrence of phase transformations from various forms of iron oxides to iron during the carbothermal reductions were identified through XRD profiles and supported with weight loss (%). XRF analysis proved that iron ore is of high grade with 93.4% of Fe₂O₃ content. Other oxides present in minor amounts are 2% Al₂O₃ and 1.8% SiO₂ with negligible amounts of other compounds such as MnO, K₂O and CuO. Composite pellet with finer size iron particles (≤63 ㎛) and higher carbon content of 60:40 exhibited 45.13% weight lost compared to 32.30% and 3.88% respectively for 80:20 and 100:0 ratios. It is evident that reduction reactions can only occur with the presence of coke, the carbon supply. The small weight loss of 3.88% at 100:0 ratio occurs due to the removal of moisture and volatiles and oxidations of iron ore. Higher carbon supply at 60:40 leads into better heat and mass transfer and diffusivity during carbothermic reductions. Overall, finer particle size and higher carbon supply improves reactivity and gas-solid interactions resulting in increased reductions and phase transformations.

• Steel and Composite Structures
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• v.52 no.4
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• pp.419-434
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• 2024

A flat slab is a structural system where columns directly support it without the presence of beam elements. However, despite its wide advantages, this structural system undergoes a major deficiency where stresses are concentrated around the column perimeter, resulting in the progressive collapse of the entire structure as a result of losing the shear transfer mechanisms at the cracked interface. Predicting the punching shear capacity of RC flat slabs is a challenging problem where the factors contributing to the overall slab strength vary broadly in their significance and effect extent. This study proposed a new expression for predicting the slab's capacity in punching shear using a nonuniform concrete tensile stress distribution assumption to capture, as well as possible, the induced strain effect within a thick RC flat slab. Therefore, the overall punching shear capacity is composed of three parts: concrete, aggregate interlock, and dowel action contributions. The factor of the shear span-to-depth ratio (a_v/d) was introduced in the concrete contribution in addition to the aggregate interlock part using the maximum aggregate size. Other significant factors were considered, including the concrete type, concrete grade, size factor, and the flexural reinforcement dowel action. The efficiency of the proposed model was examined using 86 points of published experimental data from 19 studies and compared with five code standards (ACI318, EC2, MC2010, CSA A23.3, and JSCE). The obtained results revealed the efficiency and accuracy of the model prediction, where a covariance value of 4.95% was found, compared to (13.67, 14.05, 15.83, 19.67, and 20.45) % for the (ACI318, CSA A23.3, MC2010, EC2, and JSCE), respectively.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.253-259
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• 2004

in this study, we developed a Monte Carlo imaging simulation code written by the visual C$\^$++/ programing language for design optimization of a digital X-ray imaging system. As a digital X-ray imaging system, we considered a Gd$_2$O$_2$S(Tb) scintillator and a photosensor array, and included a 2D parallel grid to simulate general test renditions. The interactions between X-ray beams and the system structure, the behavior of lights generated in the scintillator, and their collection in the photosensor array were simulated by using the Monte Carlo method. The scintillator thickness and the photosensor array pitch were assumed to 66$\mu\textrm{m}$ and 48$\mu\textrm{m}$, respertively, and the pixel format was set to 256 x 256. Using the code, we obtained X-ray images under various simulation conditions, and evaluated their image qualities through the calculations of SNR (signal-to-noise ratio), MTF (modulation transfer function), NPS (noise power spectrum), DQE (detective quantum efficiency). The image simulation code developed in this study can be applied effectively for a variety of digital X-ray imaging systems for their design optimization on various design parameters.

• Korean Journal of Animal Reproduction
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• v.24 no.1
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• pp.97-108
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• 2000

The objectives of this study were performed to increase the efficiency of the culture conditions of embryos produced in vitro, and to assess the developmental potential after transfer of those embryos into recipients. The mean number of folliclular oocytes recovered from an ovary was 10.7. The rates of maturation and fertilization in Grade I oocytes were significantly (P＜0.05) higher than Graden and III. Developmental rate into blastocyst in the culture group of TCM-199 with BOEC were significantly higher (P＜0.05) than the groups of TCM-199 and conditioned medium (24.7% vs. 12.4% and 18.2%). The survivability of post-thawed blastocysts equilibrated for 3 min in EFS solution was significantly (P＜0.05) lower than l0 for 1 and 2 min (32.1% vs. 82.9% and 73.3%). Significantly higher (P＜0.05) survival rate in blastocysts was seen after freezing than in morulae stage embryos. Out of all 105 recipients, 49 (46.7%) were confirmed in pregnant. On pregnancy of cattle, 48 calves were born from 40 recipients. The ratio of twin and single calves was 30.5% (32/40 and 7.6% (8/40), respectively. However, the others composed of abnormal, as judging as 6 (12.2%) for abortion and 3 (6.1%) for stillbirth during the pregnant period.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.733-742
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• 2000

Fundamental materialistic characterization and adsorption/neutralization behavior of waste egg shell for heavy metal ion have been studied for its application to wastewater treatment. To investigate the structural change and thermal decomposition characteristics of egg shell. X-ray diffraction and FT-IR analysis were conducted for egg shell treated at $105^{\circ}C$ and $700^{\circ}C$, respectively. For the result of FT-IR analysis, the sample treated at $700^{\circ}C$ showed a reduced C-O absorption band compared with that of egg shell treated at $105^{\circ}C$, which may be due to the $CO_2$ release. Unlike to the result of FT-IR analysis, the XRD patterns of egg shell were almost similar for the cases of $105^{\circ}C$ and $700^{\circ}C$ treatment. however, characteristic diffraction pattern of CaO was observed for $850^{\circ}C$ treatment, at which $CaCO_3$ is known to be completely converted to CaO. TGA/DTA analysis showed a slow decline in weight loss up to $600^{\circ}C$ and, for $600{\sim}800^{\circ}C$ range, the weight loss became drastic by reason of $CO_2$ discharge, which was accompanied by an appearance of major endothermic peak. The ratio of practical breakthrough time to ideal one, total transfer unit, and mass transfer coefficient were observed to be increased as the adsorption was progressed in a multiple-column fixed-bed reactor using egg shell as an adsorbent, which signified the distribution effect of mass transfer for continuous adsorption reaction. The neutralization effect of egg shell for several types of acidic wastewater made of different mineral acids was not much different from each other except for the case of $H_2SO_4$, for which the neutralization reaction was thought to be retarded by the formation of gypsum.