• The Journal of Advanced Prosthodontics
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• v.14 no.6
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• pp.360-368
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• 2022

PURPOSE. This study assessed the physical and mechanical properties of interim crown materials fabricated using various digital techniques after accelerated aging. MATERIALS AND METHODS. Three groups of interim dental restorative materials (N = 20) were tested. The first group (CO) was fabricated using a conventional manual method. The second group (ML) was prepared from prefabricated resin blocks for the milling method and cut into specimen sizes using a cutting disc. The third group (3D) was additively manufactured using a digital light-processing (DLP) 3D printer. Aging acceleration treatments using toothbrushing and thermocycling simulators were applied to half of the specimens corresponding to three years of usage in the oral environment (N = 10). Surface roughness (Ra), Vickers microhardness, 3-point bending, sorption, and solubility tests were performed. A 2-way analysis of variance (ANOVA) and Fisher's multiple comparison test were used to compare the results among the groups. RESULTS. The mean surface roughness (Ra) of the resin after accelerated aging was significantly higher in the CO and ML groups than that before aging, but not in the 3D group. All groups showed reduced hardness after accelerated aging. The flexural strength values were highest in the 3D group, followed by the ML and CO groups after accelerated aging. Accelerated aging significantly reduced water sorption in the ML group. CONCLUSION. According to the tested material and 3D printer type, both 3D-printed and milled interim restoration resins showed higher flexural strength and modulus, and lower surface roughness than those prepared by the conventional method after accelerated aging.

• The Journal of Advanced Prosthodontics
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• v.15 no.2
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• pp.72-79
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• 2023

PURPOSE. The purpose of this in vitro study was to compare the accuracy of various 3D printers and a milling machine. MATERIALS AND METHODS. The die model was designed using CAD (Autodesk Inventor 2018 sp3). The 30 ㎛ cement space was given to the die and the ideal crown of the mandibular left first molar was designed using CAD (ExoCAD). The crowns were produced using the milling machine (Imes-icore 250i) and the 3D printers (Zenith U, Zenith D, W11) and they were divided into four groups. In all groups, the interior of each crown was scanned (Identica blue) and superimposed (Geomagic Control X) with the previously designed die. The difference between the die and the actual crown was measured at specific points. The Kruskal-Wallis test, the Mann-Whitney test, and Bonferroni's method were performed with a statistical analysis software (P < .008 in inter-group comparison P < .001 in intra-group comparison). RESULTS. In all groups, the center of the occlusal area and the anti-rotational dimple area showed significantly greater difference and the marginal area showed the smallest difference comparatively. The mean value of the difference in each area and the sum of the differences were higher in order of W11, Imes-icore 250i, Zenith D, and Zenith U. CONCLUSION. The digital light processing (DLP) method shows higher accuracy compared to the sereolithography (SLA) method using the same resin material.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.4
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• pp.260-268
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• 2017

Purpose: Manufacturing with AM (Additive manufacturing) technique has many advantages; but, due to insufficient study in the area, it is not being widely used in the general clinic. In this study, differences of flexural strength among various materials of 3 unit fixed dental prosthesis were analyzed. Materials and Methods: A metal jig for specimens that had a 3-unit-fixed dental prosthesis figure were fabricated. The jigs were made appropriately to the specifications of the specimens. Three different kinds of materials of specimens which were NC (mathacrylic esther based), DP-1 (Bisphenol A epoxy acrylate type oligomer based), and DT-1 (urethane acrylate based) were printed with DLP machine. Five specimens for each kind of material were printed with an angle of $30^{\circ}$ from the horizontal surface. The specimens were placed on the jig and the flexural strength was measured and recorded using Universal testing machine. The recorded data was analyzed in SPSS using One-way ANOVA and Tukey HSD to determine the significance of the differences of flexural strength among the groups. Results: The flexural strengths of each group were the followings: NC, $1119{\pm}305$ N; DP-1, $619{\pm}150$ N; DT-1, $413{\pm}65N$. Using One-way ANOVA and Tukey Honestly Significant Difference test, significant difference was found between NC and the other groups (P < 0.05), but there was no significant difference between DP-1 and DT-1 (P > 0.05). Conclusion: Higher flexural strength was shown in 3-unit-fixed dental prosthesis that were 3D printed using a DLP machine with NC material.

• Journal of radiological science and technology
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• v.38 no.2
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• pp.107-114
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• 2015

The purpose is reducing radiation dose while maintaining of image quality in liver dynamic CT(LDCT) scan, by protocols generally used and the tube voltage set at a low level protocol compared to the radiation dose and image quality. The target is body mass index, 18.5~24 patients out of 40 patients who underwent the ACT(abdominal CT). Group A(tube voltage : 120kVp, SAFIRE strength 1) of 20 people among 40 people, to apply the general abdominal CT scan protocol, group B(tube voltage : 100kVp, apply SAFIRE strength 0~5) was 20 people, set a lower tube voltage. Image quality evaluation was setting a region of interest(ROI) in the liver parenchyma, aorta, superior mesenteric artery (SMA), celiac trunk, visceral fat of arterial phase. In the ROI were compared by measuring the noise, signal to noise ratio(SNR), contrast to noise ratio(CNR), CT number. In addition, qualitative assessments to evaluate two people in the rich professional experience in Radiology by 0-3 points. We compared the total radiation dose, dose length product(DLP) and effective dose, volume computed tomography dose index(CTDIvol). The higher SAFIRE in the tube voltage 100 kVp, noise is reduced, CT number was increased. Thus, SNR and CNR was increased higher the SAFIRE step. Compared with the tube voltage 120kVp, noise, SNR, CNR was most similar in SAFIRE strength 2 and 3. Qualitative assessment SAFIRE strength 2 is the most common SAFIRE strength 2 the most common qualitative assessment, if the tube voltage of 100kVp when the quality of the images better evaluated was SAFIRE strength 1. Dose was reduced from 21.69%, in 100kVp than 120kVp. In the case of a relatively high BMI is not LDCT scan, When it is shipped from the factory tube voltage is set higher, unnecessary radiation exposure when considering the reality that is concerned, when according to the results of this study, set a lower tube voltage and adjust the SAFIRE strength to 1 or 2, the radiation without compromising image quality amount also is thought to be able to be reduced.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.67-71
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• 2013

Purpose: The Change of CT exposure condition have a effect on image quality and patient exposure dose. In this study, we evaluated effect CT image quality and SUV when CT parameters (Pitch, Rotation time) were changed. Materials and Methods: Discovery Ste (GE, USA) was used as a PET/CT scanner. Using GE QA Phantom and AAPM CT Performance Phantom for evaluate Noise of CT image. Images are acquired by using 24 combinations that four stages pitch (0.562, 0.938, 1.375, 1.75:1) and six stages X-ray tube rotation time (0.5s-1.0s). PET images are acquired using 1994 NEMA PET Phantom ($^{18}F-FDG$ 5.3 kBq/mL, 2.5 min/frame). For noise test, noise are evaluated by standard deviation of each image's CT numbers. And then we used expectation noise according to change of DLP (Dose Length Product) to experimental noise ratio for index of effectiveness. For spatial resolution test, we confirmed that it is possible to identify to 1.0 mm size of the holes at the AAPM CT Performance Phantom. Finally we evaluated each 24 image's SUV. Results: Noise efficiency were 1.00, 1.03, 1.01, 0.96 and 1.00, 1.04, 1.02, 0.97 when pitch changes at the QA Phantom and AAPM Phantom. In case of X-ray tube rotation time changes, 0.99, 1.02, 1.00, 1.00, 0.99, 0.99 and 1.01, 1.01, 0.99, 1.01, 1.01, 1.01 at the QA Phantom and AAPM Phantom. We could identify 1.0 mm size of the holes all 24 images. Also, there were no significant change of SUV and all image's average SUV were 1.1. Conclusion: 1.75:1 pitch is the most effective value at the CT image evaluation according to pitch change and It doesn't affect to the spatial resolution and SUV. However, the change of rotation time doesn't affect anything. So, we recommend to use the effective pitch like 1.75:1 and adequate X-ray tube rotation time according to patient size.

• Journal of Chest Surgery
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• v.39 no.3 s.260
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• pp.201-207
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• 2006

Background: Percutaneous cardiopulmonary support (PCPS) provides passive support of gas exchange and perfusion, allowing the use of other methods of care for organ recovery, and saves lives of patients with severe cardiopulmonary failure in a wide variety of clinical settings with a minimal risk of bleeding and need for chest re~ exploration. We summarized a single center's experiences with PCPS in patients with cardiogenic shock or cardiac arrest due to the ischemic heart disease. Material and Method: Among the 20 consecutive patients with cardiogenic shock or cardiac arrest from May 1999 to June 2005, Biopump (Medtronic, Inc, Minneapolis, MN) was used in 7 patients and the self-priming, heparin-coated circuit of EBS (Terumo, Japan) was applied to remaining 13 patients. Most of cannulations were performed percutaneously via femoral arteries and veins. The long venous cannulas of DLP (Medtronic inc. Minneapolis, MN) or the RMI (Edwards's lifescience LLC, Irvine, CA) were used with the arterial cannulae from 17 Fr to 21 Fr and the venous cannula from 21 Fr to 28 Fr. Result: The 20 consecutive patients who were severely compromised and received PCPS for the purpose of resuscitation were comprised of 13 cardiac arrests and 7 cardiogenic shocks in which by-pass surgery was performed in 11 patients and 9 ongoing PCls under the cardiopulmonary support. The mean support time on the PCPS was 38$\pm$42 hours. Of the 20 patients implanted with PCPS, 11 patients ($55\%$) have had the PCPS removed successfully; overall, 8 of these patients ($40\%$) were discharged from the hospital in an average surviving time for 27$\pm$17 days after removing the PCPS and survived well with 31$\pm$30 months of follow-up after the procedure. Conclusion: The use of PCPS appears to provide the hemodynamic restoration, allowing the survival of patients in cardiac arrest or cardiogenic shock who would otherwise not survive, and patients receiving PCPS had a relatively long-term survival.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.2
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• pp.110-117
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• 2019

Purpose: This study was to evaluate the wear resistance of 3D printed, milled, and conventionally cured provisional resin materials. Materials and methods: Four types of resin materials made with different methods were examined: Stereolithography apparatus (SLA) 3D printed resin (S3P), digital light processing (DLP) 3D printed resin (D3P), milled resin (MIL), conventionally self-cured resin (CON). In the 3D printed resin specimens, the build orientation and layer thickness were set to $0^{\circ}$ and $100{\mu}m$, respectively. The specimens were tested in a 2-axis chewing simulator with the steatite as the antagonist under thermocycling condition (5 kg, 30,000 cycles, 0.8 Hz, $5^{\circ}C/55^{\circ}C$). Wear losses of the specimens were calculated using CAD software and scanning electron microscope (SEM) was used to investigate wear surface of the specimens. Statistical significance was determined using One-way ANOVA and Dunnett T3 analysis (${\alpha}=.05$). Results: Wear losses of the S3P, D3P, and MIL groups significantly smaller than those of the CON group (P < .05). There was no significant difference among S3P, D3P, and MIL group (P > .05). In the SEM observations, in the S3P and D3P groups, vertical cracks were observed in the sliding direction of the antagonist. In the MIL group, there was an overall uniform wear surface, whereas in the CON group, a distinct wear track and numerous bubbles were observed. Conclusion: Within the limits of this study, provisional resin materials made with 3D printing show adequate wear resistance for applications in dentistry.

• Journal of Life Science
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• v.32 no.7
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• pp.532-541
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• 2022

Obesity induced by high-fat diet (HFD) is verified as a strong risk factor and negative prognostic factor for prostate cancer in several genetically engineered mice although it was not examined in the normal mice. To investigate whether HFD-induced obesity can affect the development and progression of cancer in the prostate of normal mice, alterations in the weight and histological structure of the prostate as well as the expression of cancer-related proteins were analyzed in obese C57BL/6N mice fed with 60% HFD for 16 weeks. First, HFD-induced obesity, including an increase in organ weight, body weight, fat accumulation, and serum lipid profile, was successfully induced in C57BL/6N mice after HFD treatment. The total weight of the prostate significantly increased HFD-induced obesity in the model mice compared with the control group. Among the four lobes of the prostate, the weight of the ventral prostate (VP) and anterior prostate (AP) were higher in HFD-induced obesity model mice than in the control group, although the weights of the lateral prostate (DLP) and seminal vesicle (SV) were constantly maintained. In addition, the incidences of hyperplasia and non-hodgkin's lymphoma (NHL) in the histological structure were remarkably increased in HFD-induced obesity model mice, while the epithelial thickness was higher in the same group. A significant increase in the phosphorylation levels of key proteins in the AKT (protein kinase B) signaling pathway was detected in HFD-induced obesity model mice. Therefore, these results suggest that HFD-induced obesity can promote hyperplasia and NHL in the prostates of C57BL/6N mice through the activation of the AKT signaling pathway.

• The Journal of the Korea Contents Association
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• v.13 no.6
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• pp.331-338
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• 2013

CT for follow-up visits because of liver disease, body mass index (BMI) and kVp according to the change of the image quality and radiation dose to evaluate for changes. March 2010 to June 2011 at Pusan P University Hospital, abdominal CT scans a patient BMI (Body Mass Index. Less BMI) index was less than 25 in the treatment of subjects had a 48-person Noise and SNR at 100kVp abdominal image is lager than the 120kVp image. CTDI volume value at by the analysis of the radiation dose is 4.47mGy(100kVp) and 9.01mGy(120kVp). So CTDIvol in 100kVp is smaller than CTDIvol in 120kVp(decrease by 44.1%). And, effective dose is 7.1mSv(100kVp) and 12.51mSv(120kVp). So effective dose in 100kVp is smaller than effective dose in 120kVp(decrease by 43%). Evaluation of image quality is that Unacceptable 0 person, Suboptimal 0 person, Adequate 0 person, Good 1 person, Excellent 47 person. In case of repeatly patient, we examinate abdomianl CT scan by using low kVp and body mass index less than 25. We can has good quality image and benefit of low radiation dose.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.193-201
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• 2017

Financial firms strengthen to protect personal information from the leakage, introducing various security solutions such as print output security, internet network Isolation system, isolationg strorage of customer information, encrypting personal information, personal information detecting system, data loss prevention, personal information monitoring system, and so on. Financial companies are also entering the era of cutthroat competition due to accept of the new channels and the paradigm shift of financial instruments. Accordingly, The needs for security for customer information held by financial firms are keep growing. The large security accidents from the three card companies on January 2014 were happened, the case in which one of the outsourcing personnel seized customer personal information from the system of the thress card companies and sold them illegally to a loan publisher and lender. Three years after the large security accidents had been passed, nevertheless the security threat of the IT outsourcing workforce still exists. The governments including the regulatory agency realted to the financail firms are conducting a review efforts to prevent the leakage of personal information as well as strengthening the extent of the sanction. Through the analysis on the application of security policy for outsourcing personnel in case of large-scale Financial IT projects and the case study of appropriate security policies for security compliance, the theis is proposing a solution for both successfully completing large-scale financial IT Project and so far as possible minizing the risk from the security accidents by the outsouring personnel.