• Journal of Preventive Medicine and Public Health
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• v.49 no.4
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• pp.230-239
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• 2016

Objectives: We aimed to evaluate the effect of geographic units of analysis on measuring geographic variation in medical services utilization. For this purpose, we compared geographic variations in the rates of eight major procedures in administrative units (districts) and new areal units organized based on the actual health care use of the population in Korea. Methods: To compare geographic variation in geographic units of analysis, we calculated the age-sex standardized rates of eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee-replacement surgery, caesarean section, hysterectomy, computed tomography scan, and magnetic resonance imaging scan) from the National Health Insurance database in Korea for the 2013 period. Using the coefficient of variation, the extremal quotient, and the systematic component of variation, we measured geographic variation for these eight procedures in districts and new areal units. Results: Compared with districts, new areal units showed a reduction in geographic variation. Extremal quotients and inter-decile ratios for the eight procedures were lower in new areal units. While the coefficient of variation was lower for most procedures in new areal units, the pattern of change of the systematic component of variation between districts and new areal units differed among procedures. Conclusions: Geographic variation in medical service utilization could vary according to the geographic unit of analysis. To determine how geographic characteristics such as population size and number of geographic units affect geographic variation, further studies are needed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6019-6026
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• 2015

In this study, we have tried to use 3D-printing technology, which is very useful for small amount production and individual personalization manufacturing to produce a cast customized by individual. To do this, we have made casts by the 3D printer in the method of fused deposition modeling technique using ABS(acrylonitrile butadiene styrene) resin which is thermoplastic plastics. The computed tomography of human hand part was used as the modeling of the cast and it was designed to circulate air well. As a result, an individual personalized cast that fitted well with the model part was produced. In addition, we could get more excellent radiography from the cast than the existing cast. In conclusion, this study of 3D-printing could be used as basic data when a similar designed structure in fused deposition modeling technique by ABS resin is printed out.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.216-233
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• 2021

In this work, Rhizophora spp. particleboard phantoms were made using SPI-based adhesives, modified with sodium hydroxide and itaconic acid polyamidoamine-epichlorohydrin (0, 5, 10, and 15 wt%). An X-ray computed tomography (CT) imaging system was used to ascertain the CT numbers and density distribution profiles of the particleboards. The SPI-based/NaOH/IA-PAE/Rhizophora spp. particleboard phantoms with 15 wt% IA-PAE addition level had the highest solid content, flexural strength, flexural modulus, and internal bonding strength of 36.06 ± 1.08%, 18.61 ± 0.38 Nmm^-2, 7605.76 ± 0.89 Nmm^-2, and 0.463 ± 0.053 Nmm^-2, respectively. The moisture content, mass density, water absorption, and dimensional stability were 6.93 ± 0.27%, 0.962 ± 0.037 gcm^-3, 22.36 ± 2.47%, and 10.90 ± 0.86%, respectively. The results revealed that the mass attenuation coefficients and effective atomic number values within the 16.59-25.26 keV photon energy region, were close to the calculated XCOM values in water, with a p-value of 0.077. Moreover, the CT images showed that the dissimilarities in the discrepancy of the profile density decreased as the IA-PAE concentrations increased. Therefore, these results support the appropriateness of the SPI-based/NaOH/IA-PAE/Rhizophora spp. particleboard with 15 wt% IA-PAE adhesive as a suitable tissue-equivalent phantom material for medical health applications.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.244-254
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• 2018

Surface modified poly ${\text\tiny{L}}$-lactic acid (PLLA) samples with hydroxyapatite (HA), heparin and bone morphogenetic protein-2 (BMP-2) mediated by polydopamine (pDA) coating (PLLA/pDA/HA/Hep/BMP-2) were prepared, and their effects on the enhancements of bone formation and osseointegration were evaluated in vitro and in vivo as compared to PLLA, PLLA/pDA/HA, and PLLA/pDA/Hep/BMP-2. The changes in surface chemical compositions, morphologies and wettabilities were observed by X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and water contact angle measurements. Pre-coating of HA particles with pDA provided uniform and homogeneous anchoring of particles to PLLA surface. In addition, the strong ionic interaction between heparin and pDA led PLLA surface readily heparinized for loading of BMP-2. In vitro experiments revealed that the levels of alkaline phosphatase (ALP) activity, calcium deposition, and osteocalcin (OCN) gene expression were higher in MG-63 human osteosarcoma cell lines grown on PLLA/pDA/HA/Hep/BMP-2 than on control PLLA, PLLA/pDA/HA, and PLLA/pDA/Hep/BMP-2. In vivo studies using micro-computed tomography (micro-CT) also showed that PLLA/pDA/HA/Hep/BMP-2 screw exhibited greatest value of bone volume (BV) and bone volume/tissue volume (BV/TV) among samples. Histological evaluations with H&E and Von Kossa staining demonstrated that a combination of HA and BMP-2 contributed to the strong osseointegration.

• Journal of Powder Materials
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• v.21 no.4
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• pp.266-270
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• 2014

Metal foams have a cellular structure consisting of a solid metal containing a large volume fraction of pores. In particular, open, penetrating pores are necessary for industrial applications such as in high temperature filters and as a support for catalysts. In this study, Fe foam with above 90% porosity and 2 millimeter pore size was successfully fabricated by a slurry coating process and the pore properties were characterized. The Fe and $Fe_2O_3$ powder mixing ratios were controlled to produce Fe foams with different pore size and porosity. First, the slurry was prepared by uniform mixing with powders, distilled water and polyvinyl alcohol(PVA). After slurry coating on the polyurethane(PU) foam, the sample was dried at $80^{\circ}C$. The PVA and PU foams were then removed by heating at $700^{\circ}C$ for 3 hours. The debinded samples were subsequently sintered at $1250^{\circ}C$ with a holding time of 3 hours under hydrogen atmosphere. The three dimensional geometries of the obtained Fe foams with an open cell structure were investigated using X-ray micro CT(computed tomography) as well as the pore morphology, size and phase. The coated amount of slurry on the PU foam were increased with $Fe_2O_3$ mixing powder ratio but the shrinkage and porosity of Fe foams were decreased with $Fe_2O_3$ mixing powder ratio.

• Journal of Chest Surgery
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• v.46 no.2
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• pp.130-134
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• 2013

Background: Rib fractures are the most common type of thoracic trauma and cause other complications. We explored the risk factors for pneumonia in patients with multiple rib fractures. Materials and Methods: Four hundred and eighteen patients who visited our hospital with multiple rib fractures between January 2002 and December 2008 were retrospectively reviewed. Chest X-rays and chest computed tomography were used to identify injury severity. Patients with only a single rib fracture or who were transferred to another hospital within 2 days were excluded. Results: There were 327 male patients (78%), and the median age was 53 years. The etiologies of the patients' trauma included traffic accidents in 164 cases (39%), falls in 78 cases (19%), slipping and falling in 90 (22%), pedestrian accidents in 30 (7%), industrial accidents in 41 (10%), and assault in 15 (4%). The median number of rib fractures was 4.8. Pulmonary complications including flail chest (2.3%), lung contusion (22%), hemothorax (62%), pneumothorax (31%), and hemopneumothorax (20%) occurred. Chest tubes were inserted into the thoracic cavity in 216 cases (52%), and the median duration of chest tube insertion was 10.26 days. The Injury Severity Score (ISS) and rib score had a median of 15.27 and 6.9, respectively. Pneumonia occurred in 18 cases (4.3%). Of the total cases, 33% of the cases were managed in the intensive care unit (ICU), and the median duration of stay in the ICU was 7.74 days. Antibiotics were administered in 399 patients (95%) for a median of 10.53 days. Antibiotics were used for more than 6 days in 284 patients (68%). The factors affecting pneumonia in patients with multiple rib fractures in multivariate analysis included age (p=0.004), ISS (p<0.001), and rib score (p=0.038). The use of antibiotics was not associated with the occurrence of pneumonia (p=0.28). In-hospital mortality was 5.3% (n=22). Conclusion: The factors affecting risk of pneumonia in patients with multiple rib fractures included age (p=0.004), ISS (p<0.001), and rib score (p=0.038). Elderly patients with multiple traumas have a high risk of pneumonia and should be treated accordingly.

• Journal of The Korean Society of Clinical Toxicology
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• v.3 no.1
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• pp.40-44
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• 2005

Nitrogen dioxide ($NO_2$), which produced during the process of silage, metal etching, explosives, rocket fuels, welding, and by-product of burning of fossil fuels, is one of major components of air pollutant. Accidental exposure of high level of $NO_2$ produces cough, dyspnea, pulmonary edema which may be delayed $4\~12$ hours and, in $2\~6$weeks, bronchiolitis obliterans. We experienced a case of acute pulmonary injuny induced by industrial exposure to high level of $NO_2$ during repair of $NO_2$ pipeline in a refinery. A 55-year-old man experienced nausea and severe dyspnea in 6 hours after $NO_2$ inhalation. Initial blood gas examination revealed severe hypoxemia accompanying increased alveolar-arterial O2 difference. Radiological examination showed diffuse ground glass opacities in both lung fields. Clinical symptoms and laboratory findings, including radiological study and pulmonary function test were improved with conservative treatment using inhaled oxygen and bronchodilator. and there was no evidence of bronchial fibrosis and bronchiolitis obliterance in chest high resolution computed tomography performed 6 weeks after exposure. Here, we report a case of $NO_2$ induced acute pulmonary injuny with a brief review of the relevant literature.

• Progress in Medical Physics
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• v.16 no.1
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• pp.47-51
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• 2005

We report a case of an accidental extravasation of contrast material. A large-volume extravasation occurred in an adult during spiral contrast-enhanced CT. The amount of contrast material extravasated was 47 ml. The patient had a swelling of the dorsum right hand. The extravasation injury site was determined by CT scanning. The extavasation case was examined using five separate display techniques: axial, multi planar reformation (MPR), maximum intensity projection (MIP), volume rendering, and shaded-surfaced display (SSD). This paper introduces extravasation with the CT and the three-dimensional appearance.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.10
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• pp.122-128
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• 2009

The aim of this study was to investigate, through a longitudinal tracking, whether gender influences morphological characteristics on trabeucular bone of tibia during unloading. 12 male and 15 female ICR mice at 6 week of age were used and randomly allocated into two groups in each gender; unloading and normal group, respectively Mice in unloading group were operated on denervation (sciatic neurectomy). The tibiae were scanned by using in vivo micro-computed tomography (micro-CT) at 0 day (before denervation) and after 14 days. Structural parameters and BMD on tibia were measured. In female, BV/TV (65%), Tb. Th (5%), Tb.N (61%) and BMD (62%) were significantly decreased and BS/BV (17%), Tb.Sp (54%), SMI (19%) and Tb.Pf (75%) were significantly increased after unloading (p<0.05). In male, BV/TV (1%) and Tb.N (10%) were significantly decreased and SMI (5%) was significantly increased after unloading (p<0.05). In addition, trabeuclar bone loss of female was significantly bigger than that of male (p<0.05). These results indicated that effects of unloading on trabecular bone in growing mice might have difference between female and male, although unloading result in loss of quantity and quality on trabecular bone both female and male.

• Progress in Medical Physics
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• v.23 no.4
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• pp.292-302
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• 2012

The patient dose in advanced radiotherapy techniques is an important issue. These methods should be evaluated to reduce the dose in diagnostic imaging for radiotherapy. Especially, the Computed Tomography in radiotherapy has been used widely; hence the CT was evaluated for dose and image in this study. The evaluations for dose and image were done in equal condition due to compare the dose and image simultaneously. Furthermore, the possibility of dose and image evaluations by using the Monte Carlo simulation MCNPX was confirmed. We made the iterative reconstruction for low dose CT image to elevate image quality with Maximum Likelihood Expectation Maximization; MLEM. The system we developed is expected to be used not only to reduce the patient dose in radiotherapy, also to evaluate the overall factors of image modalities in industrial research.