• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.37-49
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• 1998

The specimens used were Ag-25 Pd-15 Cu 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 $350{\sim}550^{\circ}C$ Age- hardening characteristics 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, ergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, i.e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the $L1_0$ type face-centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affected by the Cu concentration. In stage II, decomposition of the ${\alpha}$ solid solution to a PdCu ordered phase($L1_0$ 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 conclued that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipetation procedure was ${\alpha}{\to}{\alpha}+{\alpha}_2+PdCu {\to}{\alpha}_1+{\alpha}_2+PdCu$ at Pd/Cu = 1.7 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.473-482
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• 2012

Purpose: The purpose of this study was to investigate the stress distribution of the surrounding tissues according to 3 proximal plate types of the RPI clasp. Methods: The removeable partial denture which mandibular right and left second premolars and mandibular molars were lost was attached to a three dimensional photo elastic epoxy resin model. Then 120N of vertical load was applied. After 3-dimensional photoelastic stress analysis was used to record the isochromatic fringe patterns. Results: Kratochvil type guiding plane exhibited little uniform stress distribution on load center and alveolar ridge, but higher stress concentration on buccal surface of second premolar. Krol type guiding plane exhibited the stress concentration on the front of load center and relatively higher stress concentration on buccal surface of first premolar. However, this type had no effect on canine. Researcher type guiding plane showed the stress concentration on second premolar and molar, but the little stress distribution on first premolar. Conclusion: In all types, excessive stress concentration was appeared and three types were not significant different.

• Journal of Technologic Dentistry
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• v.29 no.2
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• pp.79-85
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• 2007

In this study, We tried to find out the fracture strength of zirconia coping all ceramic crown and collarless porcelain fused gold alloy crown as the compared group. Each of the collarless porcelain fused gold crown and zirconia all ceramic crown has been produced specimen 10 each. And after pasting them on the steel jig, it had load given at porcelain incisal edge by 130$^{\circ}$ and measured fracture strength by Universal Testing Machine and then We have results from that. 1. The average value of fracture strength suggested 950.49 N at collarless porcelain fused gold alloy crown, 656.81 N at zirconia coping all ceramic crown. 2. Fractured pattern showed that the whole of labial part was exposed in collarless porcelain fused gold crown, but porcelain of margin part did not show fracture in advance. In the practice, the concern that collarless might cause fracture strength to be weaken does not matter, we concluded zirconia all ceramic crown made fracture that only a part of labial porcelain was fractured. The combination of zirconia all ceramic crown and turned out to be excellent.

• Journal of Technologic Dentistry
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• v.42 no.2
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• pp.99-105
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• 2020

Purpose: A study analysed the stress distribution of abutment screw and supporting bone of fixture by the tightening torque force of the abutment screw within clinical treatment situation for the stability of the dental implant prosthesis. Methods: The finite element analysis was targeted to the mandibular molar crown model, and the implant was internal type 4.0 mm diameter, 10.0 mm length fixture and abutment screw and supporting bone. The occlusal surface was modeled in 4 cusps and loaded 100 N to the buccal cusps. The connection between the abutment and the fixture was achieved by combining three abutment tightening torque forces of 20, 25, and 30 Ncm. Results: The results showed that the maximum stress value of the supporting bone was found in the buccal cortical bone region of the fixture in all models. The von Mises stress value of each model showed 184.5 MPa at the 20 Ncm model, 195.3 MPa in the 25 Ncm model, and 216.5 MPa in the 30 Ncm model. The contact stress between the abutment and the abutment screw showed the stress value in the 20 Ncm model was 201.2 MPa, and the 245.5 MPa in the 25 Ncm model and 314.0 MPa in the 30 Ncm model. Conclusion: The increase of tightening force within the clinical range of the abutment screw of the implant dental prosthesis was found to have no problem with the stability of the supporting bone and the abutment screw.

• Journal of Technologic Dentistry
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• v.19 no.1
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• pp.113-120
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• 1997

Candida albicans is now well recognized among the denture stomatitis patients. The broth macrodilution test is the most widely used technique for antifungal susceptibility testing. The purpose of this study was to determine the C. albicans carrier rate of the denture patients in Iksan, chonbuk. To determine the C. albicans carrier rate of denture patients, culture were made from 227 sample taken in Iksan, Chonbuk during July 1997 to August 1997. Also activities of amphotericin B and miconzole against isolates of denture patients of C. albicans were tested by broth macrodilution test using RPMI medium 1640. The results were as follows : First C. ablicans was isolated from 6.6% of denture patients samples and the frequency of isolation fo C. albicans was highest(50%) in the age group of 71-year-old to 80-year-old denture patients. Second, against C. albicans, the MIC range of amphotericn B was $0.06{\sim}0.25{\mu}g/ml$. MIC50 and MIC90 were $0.13{\mu}g/ml$ and $0.25{\mu}g/ml$, respectively. Third, the MIC range of miconazole was $10-{\ge}20{\mu}g/ml$ and MIC50 and MIC90 were $20{\mu}g/ml$ and ${\ge}20{\mu}g/ml$, respectively. It was concluded from this study that C. albicans acrriages from healthy denture individuals only over 60-year-old ages were isolated, they remain susceptible to amphotericin B and not rarely resistant to miconzole.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.917-919
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• 2011

본 연구는 보건직 종사자의 행동유형에 따른 직무만족 및 조직몰입, 직무스트레스를 파악하여 바람직한 행동패턴을 제시하고자 시도하였다. 연구방법 : 부산 및 울산광역시의 종합병원과 병의원에서 1년이상 근무한 보건직 종사자 240명 중 자료의 누락이 없는 184명을 최종 분석 대상으로 하였다. 자료의 분석은 SPSS WIN 18.0을 사용하여 대상자의 일반적 특성 및 업무환경적 특성은 실수와 백분율로 행동유형에 따른 조직몰입과 직무만족, 직무스트레스는 ANOVA로 분석하였다. 연구결과 : 보건직 종사자의 행동유형에 따른 직무만족, 조직몰입에는 유의한 차이가 없었으나, 직무 스트레스에는 유의한 차이가 있었다.

• Journal of Convergence for Information Technology
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• v.10 no.1
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• pp.187-194
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• 2020

This study surveyed the convergence of organizational culture, organizational structure, emotional labor on job satisfaction of dental workers and analyzed it with SPSS WIN18.0 program to obtain statistically significant results(p<.05). Organizational culture was high men, dental hygienist, university graduates, hospitals, many workers, High income. Organization structure was high hospitals, many workers. Emotional labor was high low age and career, single, drinking. Job satisfaction was high more than 10 workers, high income. There was a positive correlation between job satisfaction, organizational culture, organizational structure. The regression analysis showed that Y (job satisfaction) = .907 + .106 (organizational structure). Therefore, in order to enhance job satisfaction of dental workers, it is necessary to make an effort to form a positive organizational culture by considering variables related to organizational structure.

• Transactions on Electrical and Electronic Materials
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• v.13 no.6
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• pp.310-316
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• 2012

A new method for early caries diagnosis was proposed and tested through a home-made optical examination system that used quantitative light fluorescence (QLF) and digital imaging fiber optic transillumination (FOTI) (DIFOTI), with light sources across a wide spectral range, from 350 nm to 1,000 nm. The front-illuminated infrared light scattering image (FIR) showed similar diagnostic abilities to that of DIFOTI. The FIR method was invented based on the observation that caries lesions lose the high transmittance and low scattering properties of benign enamel tissue. There are various methods for the early diagnosis of caries, such as visual examination, exploration, X-ray radiography, QLF, FOTI, and infrared fluorescence (diagnodent). Among them, methods based on optical properties are regarded as having the most potential. A comparative study was performed between the FOTI, QLF, diagnodent, optical coherence tomography, and FIR scattering image methods, using 20 extracted teeth samples with early caries. A scale of lesion measurement based on optical image contrast was proposed. The statistical analysis showed a significant correlation between the DIFOTI and FIR methods (r = 0.35, p < 0.05). However, the QLF and diagnodent methods showed little association with FIR images, as they have different detection principles as compared with FIR. Tomographic images obtained by OCT, using 1,330 nm super luminescent LED as a gold standard of tooth structure, verified that the FOTI and FIR results correctly represented the lack of homogeneity in dental tissue. The newly proposed FIR method attained similar diagnostic results to those of FOTI, but with an easier approach.

• Proceedings of the Materials Research Society of Korea Conference
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• 2004.05a
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• pp.46-46
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• 2004

• Journal of radiological science and technology
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• v.23 no.1
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• pp.63-76
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• 2000

License system of radiologic technologists has been started since 1965 in Korea. This study is to explore directions on radiotechnologists' license system classified by subspecialty. For this purpose, the authors surveyed on radiotechnologists' license system classified by subspecialty, with the subject related to radiotechnologic societies. Additionally, data on qualification and license system associated with medical and health care field were collected. The results are as follows. 1. The main body for subspecialty system for radiologic technologists should be the Korea Radiologic Technologists Association and the Association should maintain a close cooperation with radiotechnologic societies. 2. A radiologic technologist should be a basic role once they pass the license examination. In addition, they can get a special qualification by subspecialty in radiologic technology. 3. Radiotechnologists' license system classified by subspecialty will be keep priorities in order and done systematically. Execution order is as follows ; This study proposes that radiotechnologists responsible for ultrasonography, computed tomography(CT), magnetic resonance imaging(MRI) and security management be started for the first stage. For the second stage, radiotechnologists for mammography, angio-cardiography, digital imaging, maxillo-facial and dental radiography, nuclear medicine, radio-therapeutic field should be in force. 4. Professional education course(basic and intensive) and clinical training program have to be made for the eligibility of radiotechnologists' license system classified by subspecialty. 5. Eligibility system of radiotechnologists' license system classified by subspecialty(non-government or government) has to be made. Further more, inquiry commission to investigate eligibility for radiotechnologists' license system should be established.