• 대한치과기공학회지
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• 제38권3호
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• pp.185-191
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• 2016

Purpose: The purpose of this study were to evaluate the quality of dental prostheses printed by 3-dimensional printing system. Methods: Mater model was prepared and ten study models were fabricated. Ten single crowns were printed by 3D-printing system(Resin group) and another ten single crowns using casting method were manufactured(Metal group). The marginal adaptation of single crowns were measured using by silicone replica technique. Silicone replicas were sectioned four times. The marginal adaptations were evaluated using by digital microscope. Statistical analyses were performed with Mann-Whitney test(${\alpha}=0.05$). Results: $Mean{\pm}standard$ deviations of all marginal adaptations were $92.1(20.0){\mu}m$ for Metal group and $69.7(12.3){\mu}m$ for Resin group. Two groups were no statistically significant differences(p>0.05). Conclusion: Marginal adaptation of single crowns printed by 3D-printing system were ranged within the clinical recommendation.

• Safety and Health at Work
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• 제8권3호
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• pp.315-317
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• 2017

We present the case of a 45-year-old man with a history of benzene exposure who developed splenic marginal zone lymphoma. For 6 years, he had worked in an enclosed space cleaning instruments with benzene. He was diagnosed with splenic marginal zone lymphoma 19 years after retirement. During his time of working in the laboratory in the 1980s, working environments were not monitored for hazardous materials. We indirectly estimated the cumulative level of past benzene exposure using job-exposure matrices and technical assumptions. Care must be taken in investigating the relevance of occupational benzene exposure in the occurrence of indolent B-cell lymphoma. Because of the long latency period and because occupational measurement data do not exist for the period during the patient's exposure, the epidemiological impact of benzene exposure may be underestimated.

• The Journal of Advanced Prosthodontics
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• 제14권4호
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• pp.250-261
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• 2022

PURPOSE. The purpose of this study was to analyze the marginal fit of three-unit resin prostheses printed with the stereolithography (SLA) method in two build orientations (45°, 60°) and two layer thicknesses (50 ㎛, 100 ㎛). MATERIALS AND METHODS. A master model for a three-unit resin prosthesis was designed with two implant abutments. Forty specimens were printed using an SLA 3D printer. The specimens were printed with two build orientations (45°, 60°), and each orientation was printed with two layer thicknesses (50 ㎛, 100 ㎛). The marginal fit was measured as the marginal gap (MG) and absolute marginal discrepancy (AMD), and MG and AMD measurements were performed at 8 points per abutment, for 16 points per specimen. All statistical analyses were performed using SPSS software. Two-way analysis of variance (ANOVA) was separately performed on the MG and AMD values of the build orientations and layer thicknesses. Moreover, one-way ANOVA was performed for each point within each group. RESULTS. The margins of the area adjacent to the pontic showed significantly high values, and the values were smaller when the build orientation was 45° than when it was 60°. However, the margin did not differ significantly according to the layer thicknesses. CONCLUSION. The marginal fit of the three-unit resin prosthesis fabricated by the SLA 3D method was affected by the pontic. Moreover, the marginal fit was affected by the build orientation. The 45° build orientation is recommended.

• BLOOD RESEARCH
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• 제53권4호
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• pp.329-332
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• 2018

• Communications for Statistical Applications and Methods
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• 제16권3호
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• pp.479-485
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• 2009

When a part of data is unobserved the marginal likelihood of parameters given the observed data often involves analytically intractable high dimensional integral and hence it is hard to find the maximum likelihood estimate of the parameters. Simulated maximum likelihood(SML) method which estimates the marginal likelihood via Monte Carlo importance sampling and optimize the estimated marginal likelihood has been used in many applications. A key issue in SML is to find a good proposal density from which Monte Carlo samples are generated. The optimal proposal density is the conditional density of the unobserved data given the parameters and the observed data, and attempts have been given to find a good approximation to the optimal proposal density. Algorithms which adaptively improve the proposal density have been widely used due to its simplicity and efficiency. In this paper, we describe a fully adaptive algorithm which has been used by some practitioners but has not been well recognized in statistical literature, and evaluate its estimation performance and robustness via a simulation study. The simulation study shows a great improvement in the order of magnitudes in the mean squared error, compared to non-adaptive or partially adaptive SML methods. Also, it is shown that the fully adaptive SML is robust in a sense that it is insensitive to the starting points in the optimization routine.

• Tuberculosis and Respiratory Diseases
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• 제54권6호
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• pp.635-639
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• 2003

폐에 발생하는 변연부 B-세포 림프종은 드문 질환으로 예후는 양호하다. 저자들은 우연히 발견된 폐종괴로 내원한 61세 남자 환자에서 폐조직생검으로 진단된 변연부 B-세포 림프종 1예를 경험하였기에 보고하는 바이다.

• 자원ㆍ환경경제연구
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• 제12권1호
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• pp.75-90
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• 2003

본 연구는 도로혼잡의 외부효과를 제거하기 위한 정책방안으로 선행연구들이 제안한 피구세의 타당성 여부를 편익측면의 분석을 통해 재조명하고 있다. 본 연구는 예산제약 조건과 시간제약 조건하의 효용극대화 모형을 이용하여 고속도로 이용을 통해 얻을 수 있는 사적 한계편익과 사회적 한계편익을 규명하고 있다. 그 결과 본 연구는 사적 한계편익과 사회적 한계편익의 차이인 외부 시간비용 만큼을 피구세로 부과할 것을 제안하고 있다. 이 때 외부 시간비용은 고속도로 혼잡으로 인해 고속도로 이용자가 추가로 부담하는 한계시간비용의 가치를 나타낸다. 그리고 본 연구는 효용 극대화 모형을 통해 도출한 피구세의 크기와 이윤(또는 부)의 극대화를 통해 선행연구들이 도출한 피구세의 크기가 동일하다는 사실을 이론적으로 보여주고 있다. 아울러 본 연구는 효용극대화 모형을 통하여 사회적 평균혼잡비용과 사적 한계혼잡비용이 일치한다는 사실도 동시에 보이고 있다.

• 구강회복응용과학지
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• 제36권4호
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• pp.232-241
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• 2020

목적: 이 연구는 정출된 자연치와 대합되는 임플란트에 발생하는 합병증과 그 양상에 대해 고찰하여 대합치 정출이 임플란트 합병증에 어떠한 영향을 미치는지에 대해 알아보고자 하였다. 연구 재료 및 방법: 조선대학교 치과병원에서 2006년부터 2018년 사이에 임플란트치료를 받은 환자 중에서 유지관리기간이 최소 5년 이상이면서 구치부 임플란트와 대합되는 자연치가 방사선 사진상으로 측정 및 비교 가능한 임플란트만을 선택하였다. 정출된 구치부 자연치와 대합되는 임플란트를 실험군인 Group 1 (n = 167: 상악(Group 1max) = 92, 하악(Group 1man) = 75)과 정출소견이 없는 구치부 자연치와 대합되는 임플란트를 대조군인 Group 2 (n = 656: 상악(Group 1max) = 272, 하악(Group 1man) = 384)로 분류하였다. 두 그룹 사이에 합병증의 발생빈도와 변연골 흡수에 대해 조사하였다. 결과: Group 1과 Group 2 사이에 합병증의 발생빈도는 통계학적으로 유의성이 있었다. 특히, 상악골의 치조골 소실 빈도와 치조골 소실 양이 통계적으로 유의한 차이를 나타내었다. 결론: 정출된 자연치는 대합되는 임플란트에 골흡수를 비롯한 합병증을 더 빈번하게 유발할 수 있다.

• 대한치과기공학회지
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• 제36권3호
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• pp.159-164
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• 2014

Purpose: The purpose of this study was analysis of quality of fixed prostheses fabricated by dental CAD/CAM system. Methods: The ten same cases of stone models were manufactured by dental scannable model, and stone models were scanned using the dental scanner for changing digital model. Ten digital models were completed. The design of zirconia core for zirconia based all-ceramic crown was conducted by the dental CAD program. The samples were fabricated using the pre-sintered zirconia block by dental milling machine. Marginal gaps were analyzed using by silicone replica technique at the eight parts for quality analysis of samples. One-way ANOVA was used for statistical analysis(${\alpha}=0.05$). Results: The mean for marginal gaps were $93.2{\sim}99.1{\mu}m$ at the eight parts. One-was ANOVA didn't show significant differences(p=0.089). Conclusion: The fixed dental prostheses fabricated by dental CAD/CAM were within clinically acceptable range.

• 에너지공학
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• 제15권4호
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• pp.256-276
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• 2006

경쟁적 전력시장에서, 송전혼잡은 지역적 시장지배력의 핵심 요인들 중 하나이다. 재무적 송전권을 구매한 시장 참여자는 그들이 지불한 혼잡 세를 돌려받음으로써 재무적 보호를 받을 수 있다. 하지만 많은 연구에서, 이러한 송전권이 오히려 시장지배력을 강화시킴을 보였다. 따라서 본 논문은 새로운 개념의 송전권인 Contingent Transmission Rights을 이용해 지역적 시장지배력을 완화시키는 것이 목적이다. 본 논문은 각 모선의 한계가격 (Locational Marginal Pricing LMP)을 기반으로 한 모선별 가격제도(Nodal Pricing)와 최적조류계산(Optimal Power Flow)를 이용해 사례연구를 수행하였다.