• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.689-692
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• 2002

Composite materials, when damaged under thermal or mechanical loadings, show property changes. Among many mechanical properties of composite materials. the stiffness tend to be reduced due to micro-cracking, debonding, or delamination caused by external loadings. This research presents results regarding the detecting technique of internal damages within composite that experienced low-velocity impacts. Post-damage evaluations were made experimentally using flexural and compression loadings. Preliminary finite element analysis was made and compared with analytical solutions. The experimental results to determine the degree of damage will be compared with finite element results.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.77-77
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• 2003

Gene expression in a cell is regulated by mutual activations or repressions between genes. Identifying the gene regulation network will be one of the most important research topics in the post genomic era. We propose a linear dynamic model of gene regulation for the yeast cell cycle. A small gene network consisting of about 40 genes is reconstructed from the analysis of micro-array gene expression data of yeast S. cerevisiae published by P. Spellman et al. We show that the network construction is consistent with the result of the hierarchical cluster analysis.

• Imaging Science in Dentistry
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• 제50권2호
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• pp.161-168
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• 2020

Purpose: The aim of this study was to evaluate the influence of voxel size and different post-processing algorithms on the analysis of dental materials using micro-computed tomography (micro-CT). Materials and Methods: Root-end cavities were prepared in extracted maxillary premolars, filled with mineral trioxide aggregate (MTA), Biodentine, and Intermediate Restorative Material (IRM), and scanned using micro-CT. The volume and porosity of materials were evaluated and compared using voxel sizes of 5, 10, and 20 ㎛, as well as different software tools(post-processing algorithms). The CTAn or MeVisLab/Materialise 3-matic software package was used to perform volume and morphological analyses, and the CTAn or MeVisLab/Amira software was used to evaluate porosity. Data were analyzed using 1-way ANOVA and the Tukey test(P<0.05). Results: Using MeVisLab/Materialise 3-matic, a consistent tendency was observed for volume to increase at larger voxel sizes. CTAn showed higher volumes for MTA and IRM at 20 ㎛. Using CTAn, porosity values decreased as voxel size increased, with statistically significant differences for all materials. MeVisLab/Amira showed a difference for MTA and IRM at 5 ㎛, and for Biodentine at 20 ㎛. Significant differences in volume and porosity were observed in all software packages for Biodentine across all voxel sizes. Conclusion: Some differences in volume and porosity were found according to voxel size, image-processing software, and the radiopacity of the material. Consistent protocols are needed for research evaluating dental materials.

• Restorative Dentistry and Endodontics
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• 제40권1호
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• pp.30-36
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• 2015

Objectives: This study was performed to determine whether the combined use of one-bottle self-etch adhesives and composite resins from same manufacturers have better bond strengths than combinations of adhesive and resins from different manufacturers. Materials and Methods: 25 experimental micro-shear bond test groups were made from combinations of five dentin adhesives and five composite resins with extracted human molars stored in saline for 24 hr. Testing was performed using the wire-loop method and a universal testing machine. Bond strength data was statistically analyzed using two way analysis of variance (ANOVA) and Tukey's post hoc test. Results: Two way ANOVA revealed significant differences for the factors of dentin adhesives and composite resins, and significant interaction effect (p < 0.001). All combinations with Xeno V (Dentsply De Trey) and Clearfil $S^3$ Bond (Kuraray Dental) adhesives showed no significant differences in micro-shear bond strength, but other adhesives showed significant differences depending on the composite resin (p < 0.05). Contrary to the other adhesives, Xeno V and BondForce (Tokuyama Dental) had higher bond strengths with the same manufacturer's composite resin than other manufacturer's composite resin. Conclusions: Not all combinations of adhesive and composite resin by same manufacturers failed to show significantly higher bond strengths than mixed manufacturer combinations.

• Composites Research
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• 제20권5호
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• pp.49-55
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• 2007

반도체 쿼츠 웨이퍼 다이싱용 블레이드는 마이크로/나노 디바이스와 부품을 제조하기 위해 고정밀도의 가공성을 요구한다. 따라서 균일한 마이크로/나노 선폭의 가공을 위해서는 블레이드의 제작 단계에서 균일한 두께와 밀도를 유지하는 것이 중요하다. 기존의 실리콘웨이퍼 가공을 위해서는 금속의 블레이드가 사용되고 있지만 쿼츠 웨이퍼 가공을 위해서는 고분자 복합재가 사용된다. 이러한 복합재는 가공성, 전기전도성, 그리고 적절한 강도와 연성 및 마모저항성이 있어야 한다. 그러나 기존의 건식성형 공정으로는 균일성을 유지하기 위해 많은 공정과 비용이 소비되고 있다. 본 연구에서는 도전성 나노 세라믹스 분말, 연마재 세라믹스 분말에 열경화성 수지, 전도성 고분자를 혼합한 복합재 분말을 습식성형 공정에 의해 제조, 평가하는 연구를 수행하였다. 먼저 복합재 분말을 액상과 혼합하여 블레이드를 제작하였으며, 액상의 종류, 액상 건조공정의 영향을 고찰하였다. 평가는 마이크로미터 측정기와 현미경을 이용하여 두께를 측정하였다. 두께편차와 기공률, 밀도, 경도, 등의 특성을 비교, 평가하였다. 그 결과 습식성형에 의해 블레이드의 두께편차를 감소시킬 수 있었으며, 경도 등의 특성을 향상시킬 수 있었다.

• Reproductive and Developmental Biology
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• 제30권4호
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• pp.279-285
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• 2006

Vitrification has been suggested to be an effective method for the cryopreservation of human ES cells. However, the efficiency of vitrification with different vehicles remains a matter of ongoing controversy. The objective of this study was to assess the efficiency of cryopreservation in human ES cells by vitrification using different vehicles. A human ES cell line and a variety of vehicles, including micro-droplet (MD), open-pulled straw (OPS) and electron microscopic grid (EM-grid), were employed in an attempt to assess vitrification efficiency. In order to evaluate the survivability and the undifferentiated state of the post-vitrified human ES cells, we conducted alkaline phosphatase staining and characterization via both RT-PCR and immunofluorescence assays. The survival rates of the post-vitrified human ES cells using MD, OPS and EM-grid were determined to be 61.5%, 66.6% and 53.8%, respectively. There also exist significant differences between slow-freezing and vitrification (p<0.01). However, no significant differences were detected between the vehicle types. Finally, the pluripotency of human ES cells after thawing was verified by teratoma formation. Cryopreservation using vitrification is more effective than slow-freezing, and the efficiency of vehicles proved effective with regard to the preservation of human ES cells.

• Asian-Australasian Journal of Animal Sciences
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• 제28권6호
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• pp.876-887
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• 2015

Dicer, an ribonuclease type III type endonuclease, is the key enzyme involved in biogenesis of microRNAs (miRNAs) and small interfering RNAs (siRNAs), and thus plays a critical role in RNA interference through post transcriptional regulation of gene expression. This enzyme has not been well studied in the Indian water buffalo, an important species known for disease resistance and high milk production. In this study, the primary coding sequence (5,778 bp) of bubaline dicer (GenBank: AB969677.1) was determined and the bubaline Dicer1 biocomputationally characterized to determine the phylogenetic signature among higher eukaryotes. The evolutionary tree revealed that all the transcript variants of Dicer1 belonging to a specific species were within the same node and the sequences belonging to primates, rodents and lagomorphs, avians and reptiles formed independent clusters. The bubaline dicer1 is closely related to that of cattle and other ruminants and significantly divergent from dicer of lower species such as tapeworm, sea urchin and fruit fly. Evolutionary divergence analysis conducted using MEGA6 software indicated that dicer has undergone purifying selection over the time. Seventeen divergent sequences, representing each of the families/taxa were selected to study the specific regions of positive vis-$\grave{a}$-vis negative selection using different models like single likelihood ancestor counting, fixed effects likelihood, and random effects likelihood of Datamonkey server. Comparative analysis of the domain structure revealed that Dicer1 is conserved across mammalian species while variation both in terms of length of Dicer enzyme and presence or absence of domain is evident in the lower organisms.

• The Journal of Advanced Prosthodontics
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• 제8권4호
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• pp.251-258
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• 2016

PURPOSE. This study was undertaken to investigate whether use of an adhesive penetration enhancer, dimethyl sulfoxide (DMSO), improves bond stability of fiber posts to root dentin using two two-step etch-and-rinse resin cements. MATERIALS AND METHODS. Forty human maxillary central incisor roots were randomly divided into 4 groups after endodontic treatment and post space preparation, based on the fiber post/cement used with and without DMSO pretreatment. Acid-etched root dentin was treated with 5% DMSO aqueous solution for 60 seconds or with distilled water (control) prior to the application of Excite DSC/Variolink II or One-Step Plus/Duolink for post cementation. After micro-slicing the bonded root dentin, push-out bond strength (P-OBS) test was performed immediately or after 1-year of water storage in each group. Data were analyzed using three-way ANOVA and Student's t-test (${\alpha}$=.05). RESULTS. A significant effect of time, DMSO treatment, and treatment${\times}$time interaction were observed (P<.001). DMSO did not affect immediate bonding of the two cements. Aging significantly reduced P-OBS in control groups (P<.001), while in DMSO-treated groups, no difference in P-OBS was observed after aging (P>.05). CONCLUSION. DMSO-wet bonding might be a beneficial method in preserving the stability of resin-dentin bond strength over time when fiber post is cemented with the tested etch-and-rinse adhesive cements.

• Asian Pacific Journal of Cancer Prevention
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• 제15권16호
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• pp.6639-6641
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• 2014

Background: To evaluate the clinical significance of atypical squamous cells of undetermined significance (ASCUS) in PAP test in post-menopausal women and compare with reproductive age women. Materials and Methods: A total of 367 patients who referred to our gynecologic oncology clinic were included to the study between September 2012 and August 2013. Data for 164 post-menopausal (group 1) and 203 pre-menopausal (group 2) women with ASCUS cytology were evaluated retrospectively. Immediate colposcopy and endocervical curettage was performed for both groups and conization for all women with a result suggestive of CIN2-3. Histopathological results and demographic features of patients were compared between the two groups. Results: Mean age of the patients was $54.6{\pm}6.5$ years in group 1 and $38{\pm}6.6$ years in group 2. Some 14 (8.5%) of post-menopausal women and 36 (17.7%) of pre-menopausal women were current smokers (p=011). Totals of 38 (23.2%) post-menopausal and 64 (31.5%) pre-menopausal women were assessed for HPV-DNA. High risk HPV was detected in 7 (4.3%) and 21 (10.3%), respectively (p=0.029). Final histopathological results recorded were normal cervix, low grade cervical intra-epithelial neoplasia (CIN 1), and high grade cervical intra-epithelial neoplasia (CIN2-3). In group 1 results were 84.8%, 12.2% and 1.8%, respectively, and in group 2 were 71.9%, 23.2% and 4.9%. There were no cases of micro invasive or invasive cervical carcinoma in either group. Two cases were detected as endometrial carcinoma in the menopausal group (1.2%). Conclusions: In current study we found that preinvasive lesions were statistically significantly higher in pre-menopausal women than post-menopausal women with ASCUS. Cervicitis was more common in menopausal women. Therefore, we think that in case of ASCUS in a post-menopausal woman there is no need for radical management.

• Asian Pacific Journal of Cancer Prevention
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• 제14권6호
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• pp.3757-3760
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• 2013

MicroRNAs (miRNAs) are small, non-coding RNAs (18-25 nucleotides) that post-transcriptionally modulate gene expression by negatively regulating the stability or translational efficiency of their target mRNAs. In this context, the present study aimed to evaluate the in vitro effects of miR-485 mimics in breast carcinoma T47D cells. Forty-eight hours after T47D cells were transfected with miR-485 mimics, an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was utilized to determine the effects on cell viability. Colony formation and cell migration assays were adopted to determine whether miR-485 affects the proliferation rates and cell migration of breast carcinoma T47D cells. Our results showed that ectopic expression of miR-485 resulted in a significant decrease in cell growth, cell colony formation, and cell migration. These findings suggest that miR-485 might play an important role in breast cancer by suppressing cell proliferation and migration.