• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.330-343
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• 1997

Extraoral maxillofacial prostheses are essential for restoring facial structures that are lost as a result of congenital missing, injuries from accidents, surgical treatments of head and neck cancer. Recently, silicone is the most useful material for this purpose and is more advantageous than other maxillofacial prosthetic materials. However, there are some problems for long-term usage of silicone prostheses due to tear and color change. These are major contributing environmental factors to those problems that are such as ultraviolet light, cleansing agents, changes in humidity and successive adhesion and removal. The aim of this study is to evaluate the physical properties and color changes of maxillofacial prosthetic silicone material by those environmental factors using A-2186 silicone material (Factor II, USA) and two pigments, cadmium yellow medium and cosmetic red. Aluminium molds were fabricated according to the ASTM No. D412 & D624 specifications and resulted specimens from molds were fabicated and treated as follows. Control group and experimental I group were fabricated with 0.1% wt. pigment mixing in silicone elastomer and II-1 group, II-2 group of experimental II group were fabricated with 0.2%, 0.3% wt. pigment mixing in silicone elastomer, respectively. Control group was kept in darkroom at room temperature, I-1 group was kept under natural sunlight during 1week, I-2 group was soaked in 20% soap water during 1wk. I-3 group was successively adhered and removed 200 times on inner region of arm using Daro adhesive-33. Experimental II groups were kept in darkroom at room temperature. Instron universal testing machine was used to measure the % elongation, tensile strength, tear strength of control, experimental I, II groups and reflectance spectrophotometer(COLOR EYE-3000, Macbeth, USA) was used to measure the color differences between control group and experimental I group. The results were as follows : 1. When compared with control group, natural weathering group and 20% soap-water soaking group had no significant differences in % elongation(p>0.05). 2. 200 times successive adhesion and removal group, 0.2% wt. pigment group and 0.3% wt. pigment group had significant decreases in % elongation(p<0.05). 3. Natural weathering group, 20% soap-water soaking group and 200 times successive adhesion and removal group had no significant differences in tensile strength (p>0.05). 4. 0.2%, 0.3% wt. pigment groups had significant decreases in tensile strength(p<0.05). 5. Values of all experimental groups were decreased in tear strength. and 200 times successive adhesion and removal group had significant decrease in tear strength(p<0.05). 6. Natural weathering group and 20% soap-water soaking group had significant color differences(${\Delta}E$) and it could be detectable to naked eye(p<0.05). 7. Color differences between control group and 200 times adhesion and removal group were not detectable to the naked eye (${\Delta}E<1.0$).

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.209-216
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• 2018

In the field of angiography and interventional radiology, it is said that the risk of radiation exposure to the eyes is high due to the characteristics of work, but currently divided dose assessment and management are not carried out in reality. Therefore, in this study, in order to evaluate the dose of the operator in the surgical environment and to analyze the shields, firstly, we selected the point where the operator is mainly located, evaluated the exposure dose of the eye after attaching the pocket dosimeter to the lateral angle point of the head and neck phantom, and evaluate shielding effect when wearing lead glasses that is currently commercialized. Secondly, we evaluated the tendency of the exposure dose of the eye and the shielding effect through simulation in the same geometric structure as the actual measurement. As a result, in the case of measurement using a dosimeter, the cumulative dose increased with the increase of the fluoroscopic time, and the tendency was different according to the position of the operator. Simulation results show that the dose distribution of the eye lens in the mathematical phantom is about 1.1 ~ 1.3 times higher than that of the cornea. Also, The protective effect of the lead glasses showed a shielding effect of at least 3.7 ~ 21.4% in each eye.

• Journal of Preventive Medicine and Public Health
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• v.38 no.1
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• pp.107-116
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• 2005

Objectives : We analyzed the changes from 1996 to 2002 in distributive equity of the contribution burden in the Korean National Health Insurance. Methods : The study subjects were a total of 8,923 employee households and a total of 7,296 self-employed households over the period from 1996 to 2002. Those were the households meeting the two criteria as completing each annual survey and having no change in the job of head of the household during that period from the raw data of the Household Income and Expenditure Survey annually conducted by the Korean National Statistical Office. The unit of analysis was a household, and this was the standard for assessing the contribution that is now applied on a monthly basis. Deciles Distribution Ratio, Contribution Concentration Curve and Contribution Concentration Index were estimated as the index of inequality. Multiple regression analysis was conducted to compare the annual ability-to-pay elasticity of the contribution to the reference year of 1996 for three groups (all households, the employee households, and the self-employed households). Results : For the index of inequality, the distributive equity of contribution was improved in all three groups. In particular, the employee group experienced a substantial improvement. Using multiple regression analysis, the ability-to-pay elasticity of the contribution in the employee group significantly increased ($\beta$=0.232, p<0.0001) in the year 2002 as compared to the reference year of 1996. The elasticity in the self-employed group also significantly increased ($\beta$=0.186, p<0.05), although its change was smaller than that in the employee group. Conclusions : The employee group had a greater improvement for the distributive equity of the contribution burden than the self-employed group. Within the observation period, there were two important integration reforms: one was the integration of 227 self-employed societies in 1998 and the other was the integration of 139 employee societies in 2000. We expected that the equity of the contribution burden would be improved for the self-employed group since the integration reform of 1998. However, it was not improved for the self-employed group until the year 2000. This result suggests that capturing exactly the beneficiaries' ability-to-pay such as income is the precedent for distributive equity of the contribution burden, although a more sophisticated imposition standard of contribution is needed.

• Journal of the Korean Magnetics Society
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• v.25 no.6
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• pp.208-218
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• 2015

Recently, radiation therapy is used in the CT existing conventional two-dimensional radiation image, and set the size and location of the tumor in a manner that the image is going to change the treatment plan. After using the simulation using CT, radiation therapy it is four-dimensional or three-dimensional treatment made possible. and radiation therapy became the more effective ever before. High technology radiation therapy such as the treatment of SRS,IMRT, IGRT, SBRT, is a need to try contemplating the possibility to apply appropriate analysis and situation, so it has its own characteristics. and then it is believed that it is necessary to analyze and try it worries the proper applicability of the situation. The configuration of the various treatment that is applicable in many hospitals is necessary to try to determine how to practically apply the patients. Critical organs surrounding tumor give a small dose to avoid side effects and then the tumor has the therapeutic effect by providing a larger dose than before the radiation treatment.

• Journal of Ginseng Research
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• v.11 no.2
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• pp.145-252
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• 1987

Isolated rat adipocytes are well known to possess opposite pathways of lipid metabolism: lipolysis and ipogenesis. Both of the metabolism respond to various biologically active substances such as epinephrine, ACTH and insulin. Epinephrine and ACTH stimulate lipolysis and insulin accelerates lipogenesis. Recently, Korean red ginseng powder was found to contain adenosine and an acidic poptide which inhibited epinephrine-induced lipolysis and sl imulated insulin-mediated lipogenesis from added glucose. The acidic peptide is consisted mainly of glutamic acid and glucose. Ginsenosides Rb1 and Re inhibited ACTH-induced lipolysis in isolated rat adipocytes, while they did not affect insulinstimulated lipogenesis, Thus, all these substances extracted from Korean red ginseng exhibited selective modulations toward the opposite metabolic pathways in rat adipocyte; They inhibited the lipolysis but not the lipogenesis. We call these substances"selective modulators". Recently, we isolated a toxic substance named "toxohormone-L " from ascites fluid of patients with various malignant tumors. The toxohormone-L stimulated lipolysis in rat adipocytes and induced anorexia in rats. Both the lipolytic and the anorexigenic actions of toxohormone-L were found to be inhibited by ginsenoside Rb2 in Korean red ginseng. Based on these results, physiological signifi¬cances of these substances in Korean red ginseng were discussed. Pan ax ginseng is a medicinal plant long used in treatment of various pathological states including general complaints such as head ache, shoulder ache, chilly constitution and anorexia in cancer patients, There have been many pharmacological studies on Panax ginseng roots. Petkovllreported that oral administration of an aqueous alcoholic extract of ginseng roots decreased the blood sugar levtl of rabbits. Saito2lreported that Panax ginseng suppressed hyperglycemia induced by epinephrine and high carbohydrate diets. These findings suggest that Panax ginseng roots contain insulin-like substances. Previously, we demonstrated that gin¬seng roots contain an insulin-like peptide which inhibits epinephrine-induced lipolysis and stimulated insulin-mediated lipogenesis. In 1984, we suggested that such an insulin-like substance should be called a selective modulator4). Present investigation describes the details of the selective modulators in ginseng roots. During progressive weight loss in patients with various neoplastic disease, depletion of fat stores have been observed. The depletion of body fat during growth of neoplasms is associated with increase in plasma free fatty acids. Recently, we found that the ascites fluid from patients with hepatoma or ovarian tumor and the pleural fluid from patients with malignant lymphoma elicited fatty acid release in slices of rat adipose tissue in vitro. The lipolytic factor, named"toxohormone-L". was purifed from the ascites fluid of patients with hepatoma. The isolated preparation gave a single band on both disc gel electrophoresis and sodium dodecyl sulfate(SDS)-acrylamide gel electrophoresis in the presence of ${\beta}$-mercaptoethanol. Its molecular weight was determined to be 70,000-75,000 and 65,000 by SDS-acrylamide gel electrophoresis and analytical ultracentrifugation, respectively. Injection of toxohormone-L into the lateral ventricle of rats significantly suppressed food and water intakes. There was at least 5 hr delay between its injection and appearance of its suppressive effect. In the present study, we also tried to find a inhibitory substance toward toxohormone-L from root powder of ginseng.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.3
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• pp.219-227
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• 2005

Purpose: Abnormalities in the p53 gene are regarded as the most consistent genetic abnormalities detected in head and neck squamous cell carcinogenesis. Two new members of the p53 gene family, p73 and p63 have recently been identified. They share considerable sequence homology with p53 in the transactivation, DNA binding, and oligomerization domains, indicating possible involvement in carcinogenesis. Disruption of the homeostatic balance between proliferation and apoptosis is widely believed to contribute to human oral carcinogenesis. The aim of this study was to analyze expression of p63 in squamous cell carcinogenesis and to compare with immunochemical markers representing cell proliferation and apoptosis. Materials and Methods: Using the Syrian hamster oral cancer model, the fraction of apoptotic (apoptotic index-AI), proliferating (mitotic index-MI) and p63 expressing keratinocytes were examined at normal, dysplastic and malignant oral epithelium using the TUNEL assay, PCNA and p63 immunostaining. Results: p63 significantly increased between normal and dysplastic epithelium and between dysplastic and malignant epithelium. PCNA significantly increased between normal and dysplastic epithelium and between normal and malignant epithelium. However, increase between dysplastic and malignant epithelium, though still increasing, was not statistically significant. The percentage of TUNEL positive cells increased from normal to dysplastic epithelium and returned to normal keratinocyte level in the malignant epithelium. However, differences between tissue types were not significant. The ratio of MI:AI increased significantly only in the dysplastic-malignant epithelial transition. The increase of p63 expression closely reflected the change in the MI:AI ratio during oral carcinogenesis. Conclusion: The p63 may be associated with the regulation of epithelial proliferation and apoptosis in DMBA-induced hamster buccal pouch squamous cell carcinogenesis. Further study is required to investigate which p63 isoforms are involved in hamster buccal pouch carcinogenesis.

• Progress in Medical Physics
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• v.13 no.1
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• pp.32-36
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• 2002

For Intensity Modulated Radiation Therapy(IMRT), the spatial resolution of intensity map(IM) is limited by the width of multi-leaf collimator, which would make an effect on the conformity of the target, as well as organs at risk. Several Methods are suggested to increase the spatial resolution, which can be categorized by the hardware-dependent technique and the software-based technique. However the best solution might be to make the width of MLC finer. it has several obstacles in the respects of technical difficulty and cost. This preliminary study is designed to investigate the clinical effectiveness of the virtual-micro IMRT(VMIMRT) technique, one of the software-based technique. A particular intensity map was created, which has 42$\times$54 pixel dimension ,0.5cm pixel size and 15 intensity levels. Using this intensity map, segment fields of IMRT were generated with 1$\times$lcm, 0.5$\times$1cm, 0.5$\times$0.5cm(VMIM) beamlet size, respectively As results, we found that there was no evidence of improvement for VMIMRT, compared with the 0.5$\times$lcm beamlet size which can be delivered by 1cm width MLC. The reason seems to be due to the constraint of VMIMRT. Further study is required to prove the benefit of the VIMRT in clinical case like head and neck cancer, where is expected that higher resolution than 1cm is necessary.

• Progress in Medical Physics
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• v.24 no.4
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• pp.265-270
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• 2013

Correct target volume delineation is an important part of radiosurgery treatment planning process. We designed head phantom and performed target delineation to evaluate the volume differences due to radiosurgery treatment planning systems and image acquisition system, CT/MR. Delineated mean target volume from CT scan images was $2.23{\pm}0.08cm^3$ on BrainSCAN (NOVALS), $2.13{\pm}0.07cm^3$ on Leksell gamma plan (Gamma Knife) and $2.24{\pm}0.10cm^3$ on Multi plan (Cyber Knife). For MR images, $2.08{\pm}0.06cm^3$ on BrainSCAN, $1.94{\pm}0.05cm^3$ on Leksell gamma plan and $2.15{\pm}0.06cm^3$ on Multi plan. As a result, Differences of delineated mean target volume due to radiotherapy planning system was 3% to 6%. And overall mean target volume from CT scan images was 6.36% larger than those of MR scan images.

• The Korean Journal of Nuclear Medicine
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• v.38 no.6
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• pp.511-515
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• 2004

Purpose: The sodium-iodide symporter (NIS) expression is an important factor in determining the sensitivity of radioiodine therapy in well-differentiated thyroid cancers. Several previous studies for the expression of NIS in thyroid tissues show diverse results. To investigate whether there is difference between methods in determining the expression of NIS in thyroid tissues of patients with thyroid nodules, we measured the expression ot NIS using two different methods (RT-PCR and immunoshistochemical staining) and compared the results. Materials & Methods: We measured the expression of NIS by reverse transcriptase-polymerase chain reaction (RT-PCR) and also by immunohistochemical staining using anti-NIS antibody in thyroid cancers and other benign thyroid diseases. We compared the results of each method. We included 19 papillary carcinomas, 1 follicular carcinoma, 7 medullary carcinoma, 4 adenomas and 7 nodular hyperplasias. Results: By RT-PCR analysis, 10 of 19 papillary carcinomas expressed NIS, but 1 follicular cancer didn't express NIS. By immunohistochemical staining, 15 of 19 papaillary carcinomas express NIS, but 1 follicular lancer didn't express NIS. There was a significant correlation between the semiquautitative results of RT-PCR and immunohistochemical staining of NIS expression. (p<0.01) Conclusion: Our data demonstrated that the expression of NIS in thyroid cancers and other benign diseases investigated by RT-PCR and immunohistochemical staining correlated well each other. However, by immunohistochemical staining, more NIS expression was found.

• Journal of the Korean Physical Society
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• v.80
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• pp.516-525
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• 2022

This study is to assess the clinical use of commercial PerFRACTION^TM for patient-specific quality assurance of volumetric-modulated arc therapy. Forty-six pretreatment verification plans for patients treated using a TrueBeam STx linear accelerator for lesions in various treatment sites such as brain, head and neck (H&N), prostate, and lung were included in this study. All pretreatment verification plans were generated using the Eclipse treatment planning system (TPS). Dose distributions obtained from electronic portal imaging device (EPID), ArcCHECK^TM, and two-dimensional (2D)/three-dimensional (3D) PerFRACTION^TM were then compared with the dose distribution calculated from the Eclipse TPS. In addition, the correlation between the plan complexity (the modulation complexity score and the leaf travel modulation complexity score) and the gamma passing rates (GPRs) of each quality assurance (QA) system was evaluated by calculating Spearman's rank correlation coefficient (r_s) with the corresponding p-values. The gamma passing rates of 46 patients analyzed with the 2D/3D PerFRACTION^TM using the 2%/2 mm and 3%/3 mm criteria showed almost similar trends to those analyzed with the Portal dose imaging prediction (PDIP) and ArcCHECK^TM except for those analyzed with ArcCHECK^TM using the 2%/2 mm criterion. Most of weak or moderate correlations between GPRs and plan complexity were observed for all QA systems. The trend of mean rs between GPRs using PDIP and 2D/3D PerFRACTION^TM for both criteria and plan complexity indices as in the GPRs analysis was significantly similar for brain, prostate, and lung cases with lower complexity compared to H&N case. Furthermore, the trend of mean rs for 2D/3D PerFRACTION^TM for H&N case with high complexity was similar to that of ArcCHECK^TM and slightly lower correlation was observed than that of PDIP. This work showed that the performance of 2D/3D PerFRACTION^TM for pretreatment patient-specific QA was almost comparable to that of PDIP, although there was small difference from ArcCHECK^TM for some cases. Thus, we found that the PerFRACTION^TM is a suitable QA system for pretreatment patient-specific QA in a variety of treatment sites.