• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1018-1021
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• 2003

A scratch tester was developed to evaluate the adhesive strength at interface between thin film and substrate(silicon wafer). Under force control, the scratch tester can measure the normal and the horizontal forces simultaneously as the probe tip of the equipment approaches to the interface between thin film and substrate of wafer. The capacity of each component of force sensor is 0.1 N ∼ 100 N. In addition, the tester can detect the signal of elastic wave from AE sensor(frequency range of 900 kHz) attached to the probe tip and evaluate the bonding strength of interface. Using the developed scratch tester. the feasibility test was performed to evaluate the adhesive strength of semiconductor wafer.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1448-1452
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• 2003

A scratch tester was developed to evaluate the adhesive strength at interface between thin-film and substrate(silicon wafer). Under force control, the scratch tester can measure the normal and the tangential forces simultaneously as the probe tip of the equipment approaches to the interface between thin-film and substrate of wafer. The capacity of each component of force sensor is 0.1 N ${\sim}$ 100 N. In addition, the tester can detect the signal of elastic wave from AE sensor(frequency range of 900 kHz) attached to the probe tip and evaluate the bonding strength of interface. Using the developed scratch tester, the feasibility test was performed to evaluate the adhesive strength of thin-film.

• Corrosion Science and Technology
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• v.14 no.4
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• pp.184-189
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• 2015

In this study, the combined effect of chloride and thiosulfate ions and the effect of the ratio of the two ions on passivation in 304L, 316L, and the duplex stainless steels 2101 and 2205 are investigated using potentiostatic scratch tests. Cyclic polarization and the scratch tests were used to understand the role of anions on localized corrosion in these systems. It was found that the thiosulfate pitting began at a lower potential for 2101 than 304L in 0.6 M NaCl + 0.03 M $Na_2S_2O_3$ solution. The pit morphologies for 304L, 316L, and 2101 in an 0.6 M NaCl + 0.03 M $Na_2S_2O_3$ solution were very different from each other. The results indicate that the pitting switches from predominately thiosulfate pitting to chloride pitting at approximately 0.1 V.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.219-222
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• 2013

본 논문에서는 스크래치2.0을 활용한 초등정보영재의 프로그래밍 교육 방안을 제안하고자 한다. 스크래치는 블록을 쌓는 것만으로 프로그래밍이 가능하기 때문에 프로그래밍을 처음 접하는 초등정보영재 학생의 프로그래밍 교육과정으로 적합하다. 또한 2.0으로 버전업되면서 스크립트 보기(See inside)나 리믹스(Remix)기능이 추가되어 프로그램의 공유 및 협업이 더 용이하여졌다. 따라서 이러한 스크래치2.0의 기능을 사용한다면 학습자에게 필요한 협업 및 의사소통 능력을 기르게 하는데 적합하다고 할 수 있다. 또한 영재학생들은 학습자 스스로 목표를 정하고 계획을 능동적으로 수행해나갈 때 높은 성과를 보이는 특성이 있다. 따라서 자기 주도적 학습 모형을 영재학생들에게 사용한다면 더 효과적이다. 이에 본 연구에서는 스크래치 2.0을 활용하여 Treffinger의 자기 주도적 학습모형을 적용한 프로그래밍 교육 방안을 제안하였다. 추후에 초, 중, 고 영재기관 연계를 위한 프로그래밍 교육위계에 대한 연구가 필요하다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.50 no.4
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• pp.206-215
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• 2024

Objectives: The current in vitro study aimed to assess the effects of ascorbic acid augmented albumin platelet-rich fibrin (AA Alb-PRF) on the wound healing activity of human gingival fibroblasts (HGFs) purported to be a regenerative biomaterial in surgical procedures. Materials and Methods: All assays were performed on three HGF groups, group I: complete media; group II: Alb-PRF, and group III: AA Alb-PRF. Alb-PRF was prepared following the protocol by Fujioka-Kobayashi et al. (2021). For preparation of AA Alb-PRF, 2,500 ㎍ AA was added to the blood pre-centrifugation. All groups were subjected to 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay to estimate cell viability and proliferation, scratch assay for migration (0, 4, 12, and 24 hours) and transwell migration assay for chemotactic migration assessment (24 hours). Outcome variables were optical density (OD) for MTT assay, percentage of wound closure in scratch assay, and number of migrated cells in transwell migration assay. One-way ANOVA for MTT and transwell migration assays and two-way ANOVA for scratch assay with Bonferroni correction were performed with significance set at P<0.05. Results: Cell viability and proliferation (OD: 0.684±0.003 and proliferation: 28%) and wound closure (49.92%±1.62% at 4 hours and 61.39%±0.88% at 12 hours) were significantly higher in group III, while group II demonstrated the maximum number of HGFs migrating across the transwell membrane (9.25±2.49) with P<0.05. Conclusion: HGFs demonstrated a significant increase in viability and proliferation along with rapid wound closure in the presence AA Alb-PRF compared to Alb-PRF alone, indicating additional beneficial effects of AA. Thus, AA Alb-PRF potentiates the wound healing activity of HGFs and could be employed in oral, maxillofacial, and periodontal surgeries as a regenerative biomaterial.

• Journal of Surface Science and Engineering
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• v.42 no.4
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• pp.173-178
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• 2009

DLC film was synthesized on plastic injection mold(SKD11, $30\;mm\;{\times}\;19\;mm\;{\times}\;0.5\;mm$) and Si(100) wafer for 2 h at $130^{\circ}C$ under 6 mTorr using hybrid method of rf sputtering and ion source. The obtained film was analysed by Raman spectroscopy, AFM, TEM, Nano indenter and scratch tester, etc. The film was defined as an amorphous phase. In the Raman spectrum, broad peak of $sp^2$-bonded carbon attributed to graphite at $1550\;cm^{-1}$ were observed, and the ratio of ID($sp^3$ diamond intensity)/IG($sp^2$ graphite intensity) was approximately 0.54. The adhesion of DLC film was more than 80 N with scratch tester when $0.2\;{\mu}m$ thickness Cr was coated as interlayer. The micro-hardness was distributed at 35~37 GPa. The friction coefficient was 0.02~0.07, and surface roughness(Ra) was 0.34~1.64 nm. The lifetime of DLC coated plastic injection mold using as a connector part in computer was more than 2 times of non-coated mold.

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.445-449
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• 2018

Chromium plating is a common surface treatment technique extensively applied in industry due its excellent properties which include substantial hardness, abrasion resistance, corrosion resistance, surface color, and luster. In this study, the effect of $MoS_2$ particles of the composite coating was investigated. To improve the lubrication of mold, $Cr-P-C/MoS_2$ composite plating was studied by varying the $MoS_2$ content. The current efficiency of the composite plating incorporated $MoS_2$ particles was increased at $MoS_2$ contents of 0.5 and 1.0 g/l due to the incorporation of fine particles. On the other hand, when the content of $MoS_2$ is 1.0 g/l or more, the current efficiency is lowered due to an increase in impact on the cathode surface. In order to evaluate the mechanical properties of Scratch test were conducted. Scratch test confirmed the lubricity and abrasion resistance characteristics revealed that the composite plating with added $MoS_2$ had relatively low surface roughness and uniform surface modification to improve its properties.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.259-264
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• 2018

PURPOSE. The purpose of this study was to evaluate the effect of the zirconia surface architecturing technique (ZSAT) on the bond strength between veneering porcelain and zirconia ceramic. MATERIALS AND METHODS. 20 sintered zirconia ceramic specimens were used to determine the optimal surface treatment time, and were randomly divided into 4 groups based on treatment times of 0, 1, 2, and 3 hours. After etching with a special solution, the surface was observed under scanning electron microscope, and then the porcelain was veneered for scratch testing. Sixty 3 mol% yttria-stabilized tetragonal zirconia polycrystal ceramic blocks were used for tensile strength testing; 30 of these blocks were surface treated and the rest were not. Statistical analysis was performed using ANOVA, the Tukey post-hoc test, and independent t-test, and the level of significance was set at ${\alpha}=.05$. RESULTS. The surface treatment of the zirconia using ZSAT increased the surface roughness, and tensile strength test results showed that the ZSAT group significantly increased the bond strength between zirconia and veneering porcelain compared to the untreated group (36 MPa vs. 30 MPa). Optimal etching time was determined to be 2 hours based on the scratch test results. CONCLUSION. ZSAT increases the surface roughness of zirconia, and this might contribute to the increased interfacial bond strength between zirconia and veneering porcelain.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.493-496
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• 1999

Ni/3C-SiC 옴믹 접합에 대한 미세구조적-접합 특성과의 상관관계를 규명하였다. 3C-SiC 웨이퍼 위에 저저항 전면 옴믹 적합층을 형성하기 위하여 Ni(t=300$\AA$)을 thermal evaporator를 사용하여 증착하고, 50$0^{\circ}C$, 80$0^{\circ}C$, 103$0^{\circ}C$ 온도에서 30분간(Ar 분위기) 열처리 한 후, scratch test를 실행하여 Ni/3C-SiC의 접착력 특성을 조사하였다. 여러 다른 온도에 따른 Ni/3C-SiC 층의 표면과 계면의 미세구조는 X-ray scattering 법을 사용하였다. 50$0^{\circ}C$ 에서 열처리된 Ni/3C-SiC 층은 가장 낮은 계면 평활도와 가장 높은 표면 평활도를 나타내었다. Ni/3C-SiC 접착력 분석에서 500 $^{\circ}C$ 열처리된 시편의 측정된 임계하중 값은 As-deposited 시편(12 N~ 13 N)보다 훨씬 낮은 2 N~3 N 범위의 값을 보였으나, 열처리 온도가 증가함에 따라 다시 높아지는 경향을 보였다. 미세구조 특성에서는 열처리 온도가 500 $^{\circ}C$ 이상에서는 NiSi$_2$silicides의 domain size는 결정성의 향상에 따라 증가되었다. 결정성 향상이 3C-SiC와 silicides 사이의 격자상수의 낮은 불일치를 완화시키는데 기여 하였 다.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.2.1-2.7
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• 2020

Objectives: This study aimed to evaluate the cell viability and migration of Endosequence Bioceramic Root Canal Sealer (BC Sealer) compared to MTA Fillapex and AH Plus. Materials and Methods: BC Sealer, MTA Fillapex, and AH Plus were placed in contact with culture medium to obtain sealers extracts in dilution 1:1, 1:2 and 1:4. 3T3 cells were plated and exposed to the extracts. Cell viability and migration were assessed by 3-(4,5-dimethylthiazoyl)-2,5-diphenyl-tetrazolium bromide (MTT) and Scratch assay, respectively. Data were analyzed by Kruskal-Wallis and Dunn's test (p < 0.05). Results: The MTT assay revealed greater cytotoxicity for AH Plus and MTA Fillapex at 1:1 dilution when compared to control (p < 0.05). At 1:2 and 1:4 dilutions, all sealers were similar to control (p > 0.05) and MTA Fillapex was more cytotoxic than BC Sealer (p < 0.05). Scratch assay demonstrated the continuous closure of the wound according to time. At 30 hours, the control group presented closure of the wound (p < 0.05). At 36 hours, only BC Sealer presented the closure when compared to AH Plus and MTA Fillapex (p < 0.05). At 42 hours, AH Plus and MTA Fillapex showed a wound healing (p > 0.05). Conclusions: All tested sealers demonstrated cell viability highlighting BC Sealer, which showed increased cell migration capacity suggesting that this sealer may achieve better tissue repair when compared to other tested sealers.