• Journal of Technologic Dentistry
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• v.27 no.1
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• pp.19-25
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• 2005

Ti6Al4V alloy have been mainly used as implant materials. Ti-6Al-4V alloy instead of pure Ti is being widely used as biomaterials has some characteristics such as high fatigue strength, tensile strength. But it has been reported recently that vanadium component expresses cytotoxicity and carcinogenicity and aluminium component is related with dementia of Alzheimer type. In order to overcome their detrimental effects, $\beta$-phase stabilizer Nb was chosen in the present study, in addition Ta and Hf were added to Ti-40wt.%Nb alloy to improve its mechanical properties. This paper was described the influence of heat treatment of Ti-40Nb alloys with 2wt%Ta, 2wt%Hf on the mechanical properties. Specimens of Ti alloys were melted in vacuum arc furnace and homogenized at 1050$^{\circ}C$ for 24 hr. and then were aged after solution heat treat at $\alpha+\beta$ and $\beta$ regions. The mechanical properties of Ti alloys were analysed by hardness test, tensile test, elongation test and SEM test. The results can be summarized as follows: 1. The mechanical properties Ti-40wt.%Nb were improved when 2wt.% Ta and 2wt.%Hf were added. 2. The higher tensile strength value and elongation at solution heat treat was higher than solution heat treat and then were aged.

• Journal of Technologic Dentistry
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• v.17 no.1
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• pp.41-57
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• 1995

This study was conducted to collect and analyze previous information in order to manage efficience, improve experience effect and promote employment rate. The questionnaire interview with 27 chief of dental Laboratory refered clinical experience in technology department about clinical experience in 14 Jumior colleges were also investigated. The results were summarried as follows : The portion of age of 35-39 among chief of dental Laboratory was 40.7% which was the highest, that of male was 96.3%, that of junior college graduate was 97.5%, that of 10years experience was 92.6% and that of ceramic technician was 85.2%, 63.0% dental laboratory for clinical experience was a bore space of 30pyong. Aspect of dental laboratory management, manufacturing all part of prosthetic restoration was 29.6%, othodontic appliance and ceramic restoration was 7.4%, 3.8%, each. The percentage of 40.7 was having connection with 30-3a dental clinics and referring case per day was 10-19 cases(40.7%), manufacturing time of referred prosthetic restoration was 3-4 days(77.8%), places preparing seminar room for education was 29.6%, above a place of 40pyong was 11.1% 30-34 pyong and 35-39 pyong was 7.4% each. During training of 2 years education course student, 18.5% was rack of thorough occupational career. While 44.4% will want the more salary among 3years education course student, 74.1% will expect the more dental techmicians would engaged in their field, 51.9% will hope improve of their theory and practice, 29.6% be expected better skill and 14.8% be expected better theory. Attitude of clinical experience places was distributed by 59.3% of offering only experience chance, 25.9% of wasting time and 29.0% of annoying. The big emphasis of climical experience was thorough occupational career(44.4%). The clinical experience places of our college were selected after direct visiting, so their condition of management was not that bad but most of dental laboratory were poor in management state and working environment. Therefore it is difficult to choose appropriate places and dental Laboratory are also limited manpower and time as suppliers. So that it recommended to induce flexible management of experience period by interval and rotation of experience places among college and to applicate intern-system for employment ant industry-college cooperation aspect.

• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.51-60
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• 1998

The artificial resin teeth used for removable prosthesis have good physical properties, but they have great wear rate. The purpose of this study is to compare the wear characteristics of several artificial resin teeth, such as Myerson teeth(Myerson Crop), Trubite IPN(Dentsply), Endura Posterio(Shofu), SROrthosit(Ivoclar), Trubite Biotone(Dentsply), Five samples of each resin tooth were abraded against natural teeth, type III gold for 150,000 cycles on the wear machine. The results obtained were as follow 1. The wear rate of artificial resin teeth when opposing enamel was the lowest in Myerson teeth($8.60{\mu}m$), followed by Trubite IPN($41.30{\mu}m$), Endure poster($63.00{\mu}m$), SR-Orthosit($68.40{\mu}m$), Trubite Biotone($209.90{\mu}m$) 2. The wear rate of artificial teeth when opposting type III gold specimens was the lowest in Myerson teeth($13.50{\mu}m$) followed by Endura Posterio($14.75{\mu}m$), Trubite IPN($53.40{\mu}m$), SROrthosit($54.20{\mu}m$), Trubite Boitone($341.50{\mu}m$)

• Journal of Technologic Dentistry
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• v.28 no.2
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• pp.331-346
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• 2006

Free-end partial dentures, which are supported by teeth surrounded by dental root membranes and elastic mucous membrane tissues, may cause stress to the abutment teeth due to external force imposed on the denture base, increase the mobility of the abutment teeth, and bring about a change in the periodontal tissue. General retainers used in partial dentures are categorized into clasp, attachment, and Konus crown. Stress imposed on the abutment teeth and mobility of the denture base have relations with the lifetime of a crown and abutment teeth, and have direct relations with the chewing ability. Thus, a need arises to make a comparative analysis of stress of the three direct retainers on the abutment teeth and interpret the mobility of the denture base. This study designed three kinds of removable partial dentures (one kind of attachment partial denture, one kind of Konus crown partial denture, and one kind of clasp partial denture), and fabricated Dentiforms of bilateral partial dentures (Kennedy Class I) with lower left 1st premolar and lower right 1st and 2nd premolars being as the abutment teeth. A strain gauge was installed in the mesial and distal surface of the lowerr left 1st premolar (No. 34) of the fabricated dentiform and in the lower part of the denture base, and installed were a clasp partial denture, an attachment partial denture, and a Konus crown partial denture. Then, the vertical static load of 5kgf and 7.5kgf at the occlusion surface of the lower left No. 6 molar was generated for a total of 20 frequencies of load each using a push-full gauge, and thus a change in the output of the strain gauge was measured. With the respective application of Konus crown, attachment and RPI clasp in the free-end partial denture, surveyed was the distribution of stress imposed on the abutment teeth and the denture base according to the location of occlusion force load so as to come up with the following results. 1. Konus crown and attachment partial dentures generated much stress, and more stress on the abutment teeth than RPI clasp dentures did. Attachment dentures tended to further intensify stress on the abutment teeth than Konus crown dentures did. 2. Attachment dentures and Konus dentures imposed less stress on the denture base than RPI clasp dentures did. There was no stress difference between Attachment and Konus crown dentures. 3. Dentures that were designed with the application of retainers using sturdy linkage methods tended to be less mobile.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.7
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• pp.951-957
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• 2009

In this study, antibacterial activity of extruded ginseng extract by 60 and 80% Et-OH were investigated by agar diffusion assay against two bacteria causing dental caries (Streptococcus mutans and Lactobacillus casei). Extrusion conditions were 20% moisture content $100^{\circ}C$ and $140^{\circ}C$ barrel temperature. The inhibition effect of 60% Et-OH ginseng extract was higher than 80% Et-OH ginseng extract. The minimum inhibitory concentration (MIC) of 80% Et-OH extruded ginseng extract at 140 and $100^{\circ}C$ barrel temperature against L.casei were 100 and 150 mg/mL respectively using broth assay method. The amount of glucosyltransferase (GTase) inhibitory content was the highest in extruded ginseng at $140^{\circ}C$ barrel temperature with 60% Et-OH. Moreover, n-hexane and n-butanol fraction ginseng extract had potential against tested bacteria. Our results demonstrated that antibacterial activities of extruded ginseng extract at $140^{\circ}C$ barrel temperature were more effective than Ex-$100^{\circ}C$, RG and WG.

• Journal of Technologic Dentistry
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• v.33 no.1
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• pp.25-35
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• 2011

Purpose: There are some advantages of the acrylic resin denture base ; appropriate strength, volume safety, simple processing apparatus, and low cost. But, it have a weakness for fracture by intense pressure or shock. However, the repairs for resin denture base are possible using various materials and techniques. There is a few studies in repairs for resin denture base, but not clinical researches. And there is no studies in absorbed saliva into the region of fracture and bond strength. This study is to observe re-bond strength of resin denture base after repairing under saliva absorption. Methods: The samples were made of heat curing resin and the rectangular parallelepiped specimens which were 50mm long, 10mm wide and 3mm high. The four different groups immersed in the artificial saliva for 2 weeks were prepared, 1) no repaired control samples, 2) immediately repaired samples, 3) repaired samples after 1 day dry, and 4) repaired samples after 3 days dry. The prepared samples were repaired by two different curing materials, self curing resin and heat curing resin method. Each groups composed of 10 specimens were experimented with the three point bending tests for bonding strength measuring Results: There were under condition absorbed in the artificial saliva and repaired by self curing resin method, repaired specimens after 1 day and 3 days dry groups had higher values of bonding strengths than control group, and bonding strengths of immediately repaired samples were similar to those of control samples (p<0.05). There were under condition immersed in the artificial saliva and repaired by heat curing resin method, immediately repaired samples showed similar values to bonding strengths of control groups, and repaired samples after 1 day and 3 days dry groups were lower than those of control group (p>0.05). Conclusion: In this study, the repairs for resin denture base were remarkably high values of bonding strengths than those of the past, and showed that have stable bonding strengths independent of saliva absorption of denture base, so present repairs for resin denture base can be performed, regardless of saliva conditions.

• Journal of Convergence for Information Technology
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• v.9 no.10
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• pp.227-233
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• 2019

This study surveyed the dental hygiene and health science students in order to grasp the bioethics consciousness from June to July 2018 and to provide basic data for the development of the bioethics curriculum. Correlation between fetal right of life and artificial insemination awareness was significant in gender(r=0.241), religion(r=-0.176), and department(r=-0.160). Correlation between awareness of organ donation and organ transplantation was significant in grade(r=0.129), religion(r=-0.098), bio ethics educ ation(r=0.235). Correlation of euthanasia perception was significant in religion (r=0. 139), bioethics education(r=-0.157). As a result, To establish an ethical view that is desirable for health college students, Necessary to develop a curriculum and to sys tematically run education programs by analyzing the factors that affect biomedical ethics.

• Journal of the Korean Society of Radiology
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• v.6 no.2
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• pp.137-142
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• 2012

This study is investigated dose change on intra-oral radiography when same conditions under the others unit and same unit under the different exposed conditions. Three different radiation devices were studied. Exposure to the upper anterior, premolar and molar on the variant time and dose measure was using semiconductor radiation dose meter. Obtained film density value was analyzed to the belong in the range of diagnosis. Results for dose of each region were less dissimilar between the maximum and minimum. Its value was different 10 times as many as 3 times. In addition, the range of film density was 2.10 ~ 2.95. These values were exceeded on the allow density of diagnostic value '0.25 ~ 2.0'. Even if the same device and the same condition, measured dose was considerable differance and film density was showed show the inappropriate density range. Those can be caused the patient's re-take and patient's diagnostic errors so patients has affected direct and indirect radiological harm. Therefore, dental radiography devices will be required periodical maintenance and also provided standard on the exposure and processing conditions.

• Journal of Technologic Dentistry
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• v.33 no.1
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• pp.37-45
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• 2011

Purpose: Heat pressed ceramics, used for all ceramic restorations, have the additional advantage of being technically less change through using of the lost-wax technique. Conceptually, combining the ceramic with the clinically proven reinforcing ability of a metal framework would be advantageous; however, cause of mismatching of fusion between ceramics and metal frameworks which from differences of casting temperature and coefficient of thermal expansion, pressed ceramics could not be used with a metal framework. The purpose of this study was to compare shear bond strength of press-to metal ceramic to porcelain fused non precious metal and feldspatic porcelain fused non precious metal. Methods: The 30 metal specimens were casted in a porcelain fused non precious metal nickel-chromium alloy. They were divided into 3 groups by surface treatment and applied ceramic: $125{\mu}m$ aluminium oxide sandblasting and veneered feldspatic porcelain (group FP), $125{\mu}m$ aluminium oxide sandblasting and had press-to-metal ceramic applied (group PC), porcelain bonder (gold bonder) fused on surface of metal specimens and had press-to-metal ceramic applied (group PCG). In each group 10 metal specimens were used. The press-to-metal ceramic applied 20 specimens had ash-free wax pattern applied, the metal-wax complexes invested, and were pressed with heat press ceramic. All specimens were subjected to shear bond strength test at a crosshead speed of 1.0 mm/min. Results: The results of measured in Mean SD and data were analyzed by one-way AVOVA (p= .05) and Tukey HSD test (p= .05).: group FP $16.090{\pm}1.841$ MPa, group PC $12.620{\pm}1.8256$ MPa, group PCG $10.920{\pm}0.9283$, significant differences between all groups (p < .05). Significant differences were found in each between group FP and group PC, group FP and group PCG (p < .05). Conclusion: The shear bond strength of press-to-metal ceramic to porcelain fused non precious metal was described higher in unused gold bonder group than used gold bonder groups.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.193-202
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• 2019

Purpose : The study was conducted to analyze the differences in perceptions, attitudes, and knowledge of health tourism students' medical tourism industry as a basic data for improving the curriculum for human resource development that can be activated by the medical tourism industry. Methods : The questionnaires were directly distributed and retrieved from 394 university students attending 4 year college health department and tourism department of some regions (IRB approval number, KW-2017-05). The questionnaire used the Likert 5-point scale to analyze differences in perceptions, attitudes, and knowledge levels in the medical tourism industry. Independent sample t tests were conducted to examine the differences in perceptions, attitudes, and knowledge about the medical tourism industry between the two groups. Results : Results obtained from this study are as follows. 1. Differences in perceptions of the medical tourism industry were 3.44 points for health and 3.45 points for tourism (p<.05). 2. The difference in attitude level was 2.28 for health and 2.79 for tourism. And that tourism has a high perception and attitude. The knowledge of medical tourism industry was 5.93 in health department and 7.11 in sight tourism, and the tourism sector was significantly higher (p<.001). 3. As a result of analysis on attitudes, interest, direct and indirect experience, practical knowledge acquisition, and development possibility were all statistically significant. 4. 98.6 % of the health students and 97.8 % of the tourism students did not obtain the qualification for the qualification of the international medical tourism coordinator. However, in the future, respondents who answered that they have obtained the certificate of international medical tourism coordinator responded positively to 54.9 % of tourism department and 25.2 % of health department. Conclusion : A systematic education of the medical tourism industry will improve the level of human resource development in the medical tourism industry, including the acquisition of international medical tourism coordinator certification, as well as the level of medical tourism industry awareness, knowledge and attitude.