• Journal of Technologic Dentistry
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• v.12 no.1
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• pp.73-93
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• 1990

The study objected to the 120 persons out of 360 persons who have registered under the association of the dental technicians in Pusan to grasp contents about improvement of life long education of the present day of November, 1987, and its results, which we have acquired by this study were as follows : 1. A sense of satisfaction toward the system of life long education appeared as unsatisfaction and its unsatisfaction decreased from the rate of member's attendance or exam. marks, the contents of education, and place of education. 2. The problem of the exam. mark which derived by the presence by the substitute appeared which 46.7 percent(56 persons), lack of opportunity for the recompletion at branch association appeared which 19.2%(23 persons), given 4. exam. marks at the over all scientific contest was appeared 14.2 percent(17 persons), relation which legal treatment when ones didn't completed exam. mark was appeared 10.8 percent(13 persons) and lastly, appeared 8.3 percent (10 persons) with time of delivery of the exam mark card. 3. The frequency of the opening for the life long education which related with the rate of members attendance was fixed as nowadays two times per annually, but they perferred the opening per academic blanch once out of the firest half year and the latter half of the year and, they liked the openings at the first week or second week and preferred the holding on saturdays and sundays. 4. The subject of the life long education have appeared the opinion that the thesis was lop-sided toward the allocation of time schedule of lecture appeared the opinion of which they perferred the rate of an hour of cultural subject and two hours of major studies, and invitation for an instructor they preferred one dentist, one member, one dean for the cultural subject, and there are lots of opinions which they wished display of materials. 5. A sence of satisfaction about the place they perferred was decreased such as ; an auditorium concerned of the colleges was 46.7 Percent(56 Persons), hotels 26.7 Percent(32 Persons), an auditorium of the general hospital 20 percent(24 persons) 6. And lastly, there are lots of opinions who have required the necessities to constitute for the academic branch.

• 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 Technologic Dentistry
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• v.21 no.1
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• pp.27-41
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• 1999

The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-30Pd-10Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at 350-$550^{\circ}C$ Age-hardening characteristic of the small Au-containing Ag-Pd-Cu dental alloys were investigated by means of hardness testing, X-ray diffraction and electron microscope observations, electrical resistance, differential scanning calorimetric, energy dispersed spectra and electron probe microanalysis. Principal results are as follows ; Maximum hardening occured in two co-phases of ${\alpha}_2$ + PdCu In stage II, decomposition of the $\alpha$ solid solution to a PdCu ordered phase($L1_o$ type) and an Ag-rich ${\alpha}_2$ phase occurred and a discontinuous precipitation occurred at the grain boundary. From the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu redered phase, which has AuCu I type face-centered tetragonal structure. Precipitation procedure was ${\alpha}{\to}{\alpha}_1+PdCu{\to}{\alpha}_2+PdCu$ at Pd/Cu = 3 Pd element of Ag-Pd-Cu alloy is more effective dental alloy on anti-corrosion and is suitable to isothermal ageing at $450^{\circ}C$.

• Journal of dental hygiene science
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• v.15 no.5
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• pp.577-584
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• 2015

The purpose of this study was to evaluate the effect of metal chloride infiltration treatment on color and strength changes of the yttria-stabilized tetragonal zirconia polycrystals (Y-TZP). Fifty disc specimens were prepared with a Y-TZP powder (ZPEX; Tosoh, Japan). Thirty different metal chloride solutions containing 0.03~0.08 wt% chromium and 0.03~0.07 wt% terbium ions were prepared. Presintered Y-TZP specimens were soaked in metal chloride coloring liquids for 3 minutes and sintered in air at $1,450^{\circ}C$ for 2 hours. The color of the specimens was measured with spectrophotometer and color difference (${\Delta}E^*$) was obtained based on the CIE $L^*$, $a^*$, $b^*$ color coordinate values. To evaluate the effect of metal chloride infiltration strength changes, the biaxial flexural test was performed at crosshead speed 0.5 mm/min. Colors of the sintered Y-TZP showed the colors of Vita shade guide A1, A2 and A3 with the infiltration of chromium and terbium chloride solutions. Density of the sintered Y-TZP increased by the infiltration of chromium and terbium chloride solutions. Bi-axial flexural strength of the sintered Y-TZP did not show statistically significant differences by the infiltration of chromium and terbium chloride solutions (p>0.05). Chromium and terbium chloride did not affect the crystal phase of zirconia, and all specimens showed tetragonal phase. Accordingly, this study suggests that chromium and terbium chlorides can make colored zirconia while adding in a liquid form. The color of colored zirconia differ from that of vita shade guide but it can use all ceramic restoration as substructure in dental clinic.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2585-2592
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• 2015

The purpose of this study was to evaluate the shear bond strength between metal core fabricated by 3D printing and dental porcelain. Thirty metal cores were fabricated(cast 15ea, 3D printing 15ea). The porcelain for each group was builded to the metal core. Sample was loaded to shear force(crosshead speed 1mm/min) in a universal material testing machine. The fracture samples were analyzed failure aspect. The means were statistical analyzed using by Mann-whitney test(${\alpha}=0.05$). The period of experimental(metal cores fabrication, dental porcelain build up, data analysis, statistical analysis, failure aspect analysis and others) for this study took six months. The $mean{\pm}SDs$ of shear bond strength was $50.14{\pm}1.60MPa$ for the cast group, and $54.36{\pm}3.18MPa$ for the 3D printing group(p=0.035). The failure aspect showed mixed failure. As a results, metal cores fabricated by 3D printing method were clinically acceptable range.

• Imaging Science in Dentistry
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• v.51 no.2
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• pp.117-127
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• 2021

Purpose: The aim of this study was to evaluate the volumetric characteristics of mucous retention cysts(MRCs) in the maxillary sinus and to analyze potential associations of MRCs with dentoalveolar pathologies. Materials and Methods: Cone-beam computed tomography (CBCT) scans exhibiting bilateral maxillary sinuses that were acquired from January 2016 to February 2019 were initially screened. A total of 227 scans(454 sinuses) that fulfilled the inclusion criteria were included. The presence, location, and volumetric characteristics of the diagnosed MRCs were evaluated on CBCT images using the 3D-Slicer software platform. The presence of MRCs was correlated with potential influencing factors including age, sex, and dentoalveolar pathology. For MRCs located on the sinus floor, factors with a potential impact on the volume, surface, and diameter were analyzed. Results: An MRC was present in 130 (28.6%) of the 454 sinuses. Most MRCs were located on the sinus walls and floor. The mean MRC volume, surface, and diameter were 551.21±1368.04 mm³, 228.09±437.56 mm², and 9.63±5.40 mm, respectively. Significantly more sinuses with associated endodontically treated teeth/periapical lesions were diagnosed with an MRC located on the sinus floor. For MRCs located on the sinus floor, endodontic status exhibited a significant association with increased volume, surface, and diameter. Conclusion: Periapical lesions might be a contributing factor associated with the presence and volume of MRCs located on the sinus floor. The 3D-Slicer software platform was found to be a useful tool for clinicians to analyze the size of MRCs before surgical interventions such as sinus floor elevation procedures.

• Journal of radiological science and technology
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• v.30 no.4
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• pp.313-320
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• 2007

There are the Medical Radiation Health and Safety Act(the Patient Radiation Health and Safety Act, the Radiologic Technologist Act), the Medical Laboratory Technologist Act, the Physical Therapy Practice Act, and the Dental Hygienist Act, etc in America. However, Korea has only one Act for a medical radiologic technologist(including radiation therapy technologist, nuclear medicine technologist), medical laboratory technologist, physical therapist, occupational therapy examiner, dental hygienist, and so on. It is the Medical Technologist Act. Therefore, the Medical Radiation Health and Safety Act for a radiologic technologist(including radiation therapy technologist, nuclear medicine technologist) has to be enacted independently in Korea. It is the purpose of this Act to provide for the appropriate certification of persons using radioactive materials, equipment emitting ionizing radiation on humans or performing medical imaging for diagnostic and therapeutic purposes. In Korea, the radiologic technologist is a "fusion technologist" who is a person other than a licensed practitioner as a radiographer, radiation therapist, nuclear medicine technologist, computed tomography technologist, magnetic resonance technologist, mammographer, sonographer, medical dosimetrist, quality management technologist, etc. This Act will have some provisions related to the definitions, reserved title, scope of practice, specialized technologist, application for licensure, radiologic technology council, renewal, continuing education, the radiation control advisory commission, etc. This Act will ensure that quality radiation therapy treatments are delivered and that quality diagnostic information is presented for interpretation, which will lead to accurate diagnosis, treatment and cure. Accurate diagnosis can be provided only when a personnel is properly educated in technique, equipment operation and radiation safety. In the end, this Act will protect the civil right to health. By regulating the personnel responsible for performing those procedures, this Act will mean improved care for patients-higher quality images, improved accuracy, and less exposure to radiation.

• Food Science and Preservation
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• v.7 no.3
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• pp.303-307
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• 2000

This study was conducted to investigate difference of the flavor components of barley bran, barley meju and sigumjang. The number of flavor components identified in barely meju and sigumjang was 46, 67 and 61, respectively. Among the flavor components in sigumjang, tetramethylpyrazine was the most dominant and followed by 2-furancarboxaldehyde, ethyl palmitate, 4-ethylphenol. Among the 13 kinds of flavor components commonly identified in thest samples, butanoic acid, hexanoic acid, heptanoic acid, octanoic acid and 2-pentylfuran were the most abundant in barley bran and followed by barley meju and sigumjang. In the mean while the content of nonanoic acid, 2-furancarboxaldehyde, benzenacetaldehyde and tetramethylpyrazine were the most dominant in sigumjang followed by barley meju and barley bran.

• Applied Biological Chemistry
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• v.43 no.3
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• pp.196-201
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• 2000

This study was conducted to investigate various flavor components of barley meju during fermentation. The change of PH was $5.2{\sim}5.6$. L-value and b-value gradually decreased. a-value gradually increased until fifth day and then decreased. Among 75 flavor compounds identified in barley meju, 10 aldehydes and 10 ketones were most in number followed by 9 acids, 9 phenols, 7 hydrocarbons, 7 alcohols and 6 esters. The contents of ethyl acetate $(67.8{\sim}89.1%)$ was more than those of any ether component followed by hexadecanoic acid $(1.21{\sim}12.00%)$ and tetramethylpyrazine $(0.06{\sim}12.30%$).

• Journal of Oral Medicine and Pain
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• v.33 no.2
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• pp.147-158
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• 2008

In our study, we investigated self-evaluation of tongue coating, self-rating intensity of oral malodor, habit related to tooth brushing and tongue scraping. Investigation was carried out on 714 Korean college students by method of self-reporting to prepared questionnaire. The obtained data were processed and analyzed with SAS program. The results of this study are as follows. 1. Students who have frequently experienced tongue coating have tendency to have stronger oral malodor than the other students. 2. The self-reporting prevalence rate of oral malodor is 81.1%. 3. Students who brush teeth shortly and irregularly have tendency to have stronger oral malodor than the other students. 4. Students with strong oral malodor have tendency to neglect scraping tongue. 5. Students with low index of tooth brushing or low index of oral hygiene controllability have tendency to have stronger oral malodor than the other students. 6. Mean scales of tooth brushing index(p<.0001), tongue scraping index(p=0.0439) and oral hygiene controllability index(p<.0001) among students in the department of Dental Hygiene and Dental Technology are significantly higher than those among general students.