• Progress in Medical Physics
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• v.9 no.2
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• pp.77-88
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• 1998

Wedge shaped isodoses are desired in a number of clinical situations. Hard wedge filters have provided nominal angled isodoses with dosimetric consequences of beam hardening, increased peripheral dosing, nonidealized gradients at deep depths along with the practical consequendes of filter handling and placement problems. Dynamic wedging uses a combination of a moving collimator and changing monitor dose to achieve angled isodoses. The segmented treatment tables(STT) that monitor unit setting by every distance of moving collimator, was induced by numerical formular. The characteristics of dynamic wedge by STT compared with real dosimetry. Methods and Materials : The accelerator CLINAC 2100C/D at Yonsei Cancer Center has two photon energies (6MV and 10MV), currently with dynamic wedge angles of 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$ and 60$^{\circ}$. The segmented treatment tables(STT) that drive the collimator in concert with a changing monitor unit are unique for field sizes ranging from 4.0cm to 20.0cm in 0.5cm steps. Transmission wedge factors were measured for each STT with an standard ion chamber. Isodose profiles, isodose curves, percentage depth dose for dynamic wedge filters were measured with film dosimetry. Dynamic wedge angle by STT was well coincident with film dosimetry. Percent depth doses were found to be closer to open field but more shallow than hard wedge filter. The wedge transmission factor were decreased by increased the wedge angle and more higher than hard wedge filters. Dynamic wedging probided more consistent gradients across the field compared with hard wedge filters. Dynamic wedging has practical and dosimetric advantages over hard filters for rapid setup and keeping from table collisions. Dynamic wedge filters are positive replacement for hard filters and introduction of dynamic conformal radiotherapy and intensity modulation radiotherapy in a future.

• Progress in Medical Physics
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• v.23 no.4
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• pp.309-316
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• 2012

Multimodal-imaging technique has been rapidly developed for improvement of diagnosis and evaluation of therapeutic effects. In despite of integrated hardware, registration accuracy was decreased due to a discrepancy between multimodal image and insufficiency of count in accordance with different acquisition method of each modality. The purpose of this study was to improve the PET image by event data resampling through analysis of data format, noise and statistical properties of small animal PET list data. Inveon PET listmode data was acquired as static data for 10 min after 60 min of 37 MBq/0.1 ml $^{18}F$-FDG injection via tail vein. Listmode data format was consist of packet containing 48 bit in which divided 8 bit header and 40 bit payload space. Realigned sinogram was generated from resampled event data of original listmode by using adjustment of LOR location, simple event magnification and nonparametric bootstrap. Sinogram was reconstructed for imaging using OSEM 2D algorithm with 16 subset and 4 iterations. Prompt coincidence was 13,940,707 count measured from PET data header and 13,936,687 count measured from analysis of list-event data. In simple event magnification of PET data, maximum was improved from 1.336 to 1.743, but noise was also increased. Resampling efficiency of PET data was assessed from de-noised and improved image by shift operation of payload value of sequential packet. Bootstrap resampling technique provides the PET image which noise and statistical properties was improved. List-event data resampling method would be aid to improve registration accuracy and early diagnosis efficiency.

• Clinical and Experimental Reproductive Medicine
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• v.37 no.1
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• pp.65-72
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• 2010

Objective: To compare the respective pregnancy outcomes of cycles undergoing elective two cleavage-stage embryos transfer (2ET) and three cleavage-stage embryos transfer (3ET) in fresh in vitro fertilization and embryo transfer (IVF-ET) program. Methods: We conducted a retrospective matched case control study that included 100 women with 2ET and 100 women with 3ET from January 2007 to June 2009. Subjects were matched for reproductive profiles and cycle characteristics. All of transferred embryos in both groups had good qualities. Pregnancy rates (PR), implantation rate, and multiple PR were compared. Results: Demographics, stimulation parameters and embryological data were comparable in both groups. Main pregnancy outcomes with 2ET and 3ET groups were not statistically different; implantation rate (41.0% vs. 35.3%), positive pregnancy rate (58.0% vs. 60.0%), clinical PR (55.0% vs. 59.0%), ongoing PR (51.0% vs. 55.0%), respectively. However, the 3ET group showed significantly higher multiple pregnancy and triplet pregnancy rates (30.9% vs. 50.8%, p=0.031; 1.8% vs. 11.9%, p=0.036, respectively). Conclusion: In women with favorable conditions and good quality embryos undergoing IVF, 2ET can get pregnancy outcomes comparable to those of 3ET and reduce multiple pregnancy (especially, triplet pregnancy).

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.3
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• pp.207-216
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• 2020

Purpose: To compare the polishing characteristics and their influence on Candida albicans adhesion to the recently introduced polyetherketoneketone (PEKK) and the conventional polymethylmethacrylate (PMMA) denture resin material. Materials and methods: Specimens from PEKK (Group E) and PMMA (Group M) were made in dimensions of 8 mm in diameter and 2 mm in thickness. The specimens were further divided into sub-groups according to the extent of polishing (ER, MR: rough; EP, MP: polished, N = 12 each). The specimens were polished using polishing machine and SiC foil. ER and MR group specimens were polished with 600 grit SiC foil only. EP and MP groups were further polished with 800, 1,000, 1,200 grit SiC foils sequentially. To measure the surface roughness values (Sa) of specimens, atomic force microscope (AFM) was used and scanning electron microscope (SEM) observation under 1,000, and 20,000 magnifications was performed to investigate surface topography. The polished specimens were soaked in C. albicans suspension for 2 hours with shaking to promote adhesion. The attached C. albicans were detached from the surface with 10 times of pipetting. The suspension of detached C. albicans was performed by serial dilution to 10³ times, and the diluted suspensions were inoculated on Sabouraud dextrose agar plates using spread plate method. After incubating the plate for 48 hours, colony forming unit (CFU)/plate of C. albicans was counted. Statistical analysis was performed using one-way ANOVA and Tukey HSD test to confirm significant difference between the groups (α=.05). Results: Average Sa value was significantly higher in MR group compared to other groups (P<.05), meaning that additional polishing steps reduced surface roughness effectively only in the PMMA specimens. There was no significant difference in Sa values between MP and EP groups. In SEM images, PEKK specimens showed numerous spikes of abraded material protruding from the surface and this phenomenon was more significant in EP group. The mean CFU/plate value was the highest in EP group and this was significant when it was compared to MP group (P<.05) which was the lowest. Conclusion: Polishing PEKK using serial SiC abrasive foil may result in higher adhesion of C. albicans. In clinic, this should be considered carefully.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.3
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• pp.183-195
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• 2020

Purpose: The purpose of this study is to compare the flexural strength of CAD/CAM denture base resins with conventional denture base resins based on their thicknesses. Materials and Methods: For the conventional denture base resins, Lucitone 199^® (C-LC) was used. DIOnavi - Denture (P-DO) and DENTCA Denture Base II (P-DC) were taken for the 3D printing denture base resins. For the prepolymerized PMMA resins, Vipi Block Gum (M-VP) and M-IVoBase^® CAD (M-IV) were used. The final dimensions of the specimens were 65.0 mm x 12.7 mm x 1.6 mm / 2.0 mm / 2.5 mm. The 3-point bend test was implemented to measure the flexural strength and flexural modulus. Microscopic evaluation of surface of fractured specimen was conducted by using a scanning electron microscope (SEM). After testing the normality of the data, one-way ANOVA was adopted to evaluate the differences among sample groups with a significance level of P = 0.05. The Tukey HSD test was performed for post hoc analysis. Results: Under the same thicknesses, there are significant differences in flexural strength between CAD/CAM denture base resins and conventional denture base resins except for P-DO and C-LC. M-VP showed higher flexural strength than conventional denture base resins, P-DC and M-IV displayed lower flexural strength than conventional denture base resins. Flexural modulus was highest in M-VP, followed by C-LC, P-DO, P-DC, M-IV, significant differences were found between all materials. In the comparison of flexural strength according to thickness, flexural strength of 2.5 mm was significantly higher than that of 1.6 mm in C-LC. Flexural strength of 2.5 mm and 2.0 mm was significantly higher than that of 1.6 mm in P-DC and M-VP. In M-IV, as the thickness increases, significant increase in flexural strength appeared. SEM analysis illustrates different fracture surfaces of the specimens. Conclusion: The flexural strength of different CAD/CAM denture base resins used in this study varied according to the composition and properties of each material. The flexural strength of CAD/CAM denture base resins was higher than the standard suggested by ISO 20795-1:2013 at a thickness of 1.6 mm or more though the thickness decreased. However, for clinical use of dentures with lower thickness, further researches should be done regarding other properties at lower thickness of denture base resins.

• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.130-136
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• 2009

The aim of this study was to develop a method for measuring the slumping resistance of flowable resin composites and to evaluate the efficacy using rheological methodology. Five commercial flowable composites (Aelitefil flow:AF, Filtek flow:FF, DenFil flow:DF, Tetric flow:TF and Revolution:RV) were used. Same volume of composites in a syringe was extruded on a glass slide using a custom-made loading device. The resin composites were allowed to slump for 10 seconds at $25^{\circ}C$ and light cured. The aspect ratio (height/diameter) of cone or dome shaped specimen was measured for estimating the slumping tendency of composites. The complex viscosity of each composite was measured by a dynamic oscillatory shear test as a function of angular frequency using a rheometer. To compare the slumping tendency of composites, one way-ANOVA and Turkey's post hoc test was performed for the aspect ratio at 95% confidence level. Regression analysis was performed to investigate the relationship between the complex viscosity and the aspect ratio. The results were as follows. 1. Slumping tendency based on the aspect ratio varied among the five materials (AF

• The Korean Journal of Nuclear Medicine
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• v.39 no.1
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• pp.49-56
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• 2005

Purpose: Dedicated animal PET is useful equipment for the study of new PET tracer. recently, microPET R4 was installed in the Korea institute of radiology and medical science. In this study, we measured the characteristics of scanner. Materials and methods: Resolution was measured using a line source (F-18:65 ${\mu}Ci$, inner diameter: 0.5 mm). The line source was put in the axial direction and was moved from the center of field of view to outside with 1 mm interval. PET images were reconstructed using a filtered back-protection and ordered subset expectation maximization. line source (16.5 ${\mu}Ci$, 78 mm) was put on the tenter of axial direction to measure the sensitivity when the deadtime was under 1%. Images were acquired during 4 minutes respectively from center to 39 mm outward. Delayed count was subtracted from total count and then decay was corrected for the calculation of sensitivity. Noise equivalent count ratio and scatter fraction were calculated using cylindrical phantom. Results: Spatial resolution of reconstructed image using filtered back-projection was 1.86 mm(radial), 1.95 mm(tangential), 1.95 mm(axial) in the tenter of field of view, and 2.54 mm, 2.8 mm, 1.61 mm in 2 cm away from the center respectively. Sensitivity was 2.36% at the center of transaxial field of view. Scatter fraction was 20%. Maximal noise equivalent count ratio was 66.4 kcps at 242 kBq/mL. Small animal images were acquired for confirmation of performance. Conclusion: Performance characteristics of microPET R4 were similar with reported value. So this will be a useful tool for small animal imaging.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.4 s.54
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• pp.289-293
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• 2005

Nowadays there are many sun protection cosmetics including organic or inorganic UV filter as an active ingredient. Chemically stable inorganic sunsEreen agents, usually metal oxides, we widely employed in high SPF products. Titanium dioxide is one of the most frequently used inorganic UV filters. It has been used as pigments for a long period of cosmetic history. With the development of micronization techniques, it becomes possible to incorporate titanium dioxide in sunscreen formulations without whitening effect and it becomes an important research topic. However, there are very few works related to quantitations of titanium dioxide in sunscreen products. In this research, we analyzed amounts of titanium dioxide in sunscreen cosmetics by adapting redof titration, reduction of Ti(IV) to Ti(III) and reoxidation to Ti(IV). After calcification of other organic ingredients of cosmetics, titanium dioxide is dissolved by hot sulfuric acid. The dissolved Ti(IV) is reduced to the Ti(III) by adding aluminum metals. The reduced Ti(III) is titrated against a standard oxidizing agent, Fe(III) (ammonium iron(III) sulfate), with potassium thiocyanate as an indicator In order to test accuracy and applicability of the proposed method, we analyzed the amounts of titanium dioxide in four types of sunscreen cosmetics, such as cream, make-up base, foundation and powder, after adding known amounts of titanium dioxide $(1{\sim}25w/w%)$. The percent recoveries of the titanium dioxide in four types of formulations were in the range between 96 and 105%. We also analyzed 7 commercial cosmetic products labeled titanium dioxide as an ingredient and compared the results with those of obtained from ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry), one of the most powerful atomic analysis techniques. The results showed that the titrated amounts were well coincided with the analyzed amounts of titanium dioxide by ICP-AES. Although instrumental analytical methods, ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) and ICP-AES, are the best for the analysis of titanium, it is hard to adopt because of their high prices for small cosmetic companies. It was found that the volumetric method presented here gat e quantitative and reliable results with routine lab-wares and chemicals.

• Korean Journal of Psychosomatic Medicine
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• v.24 no.2
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• pp.174-183
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• 2016

Objectives : The aim of this study is to evaluate difference of somatic symptoms of anxiety disorder and major depressive disorder and domainal association with suicidal idealization, plan, and attempts. Methods : A total of 359 adults diagnosed with major depressive disorder and anxiety disorder of last one year participated. Participants interviewed with certain sections of Korean version of Composite International Diagnostic interview of CIDI. Sections of interests includes questionnaires regarding somatic symptoms and suicidal idea, plan and attempts of last one year. Results : Chest pain shows more prevalence in major depressive disorder. Symptoms of Headache and loose stool are more prevalent in anxiety disorder. Difficulty in equilibrium and fainting spells are more common somatic complaints of co-diagnosis states of anxiety disorder and major depressive disorder. Comparing 3 domains of pain symptoms, gastrointestinal symptoms and pseudo-neurological symptoms, pain symptom domains, gastrointestinal symptoms domain shows significant statistic difference between diagnosis. Average somatic symptom numbers of each symptom domains increase through suicidal idealization, plan and attempt, accordingly. Conclusions : Our finding shows some of somatic symptoms are more prevalent at certain diagnosis. Since increasing numbers of somatic complaints of each symptom domains goes with the suicidal idealization to suicidal attempts, proper psychiatric evaluation and consultations are crucial for patients with numerous somatic complaints in non-psychiatric clinical settings.

• Korean Journal of Breeding Science
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• v.43 no.3
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• pp.201-205
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• 2011

'Hangangchal 1' is a new glutinous rice cultivar of second generation Tongil-type with a mid-maturing ecotype that developed by the rice breeding team of Yeongnam Agricultural Research Institute (YARI), RDA. in 2006. This cultivar was derived from a cross between 'Hangangchal', a Tongil-type glutinous cultivar and 'YR8208-20', a high yield potential in 1986/1987 winter season. 'Hangangchal 1' was selected by pedigree and bulk breeding methods from $F_3$ to $F_6$ populations. A promising line, YR10498-8-1-3, was selected and designated as 'Milyang 167' in 1997. The local adaptability test of 'Milyang 167' was carried out at seven locations during 3 years in 1998, 2005, and 2006. It has tolerance to lodging with good canopy architecture as 87cm of culm length. This cultivar is resistant to bacterial blight $K_1$, $K_2$, and $K_3$ race, rice stripe virus, rice dwarf virus, and leaf blast disease. The milled rice endosperm of 'Hangangchal 1' is glutinous and its whiteness was almost similar compared to 'Shinseonchalbyeo'. The yield of milled rice of 'Hangangchal 1' was average 5.97 MT/ha at ordinary cultivation of 9 kg/10a N fertilizer level in local adaptability test. This cultivar would be adaptable to the mid and southern plain of Korea.