• Restorative Dentistry and Endodontics
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• 제46권3호
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• pp.39.1-39.12
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• 2021

Objectives: This study analyzed the physical-chemical behavior of 2 bulk fill resin composites (BFCs; Filtek Bulk Fill [FBF], and Tetric-N-Ceram Bulk Fill [TBF]) used in 2- and 4-mm increments and compared them with a conventional resin composite (Filtek Z250). Materials and Methods: Flexural strength and elastic modulus were evaluated by using a 3-point bending test. Knoop hardness was measured at depth areas 0-1, 1-2, 2-3, and 3-4 mm. The translucency parameter was measured using an optical spectrophotometer. Real-time polymerization kinetics was analyzed using Fourier transform infrared spectroscopy. Results: Flexural strength was similar among the materials, while TBF showed lower elastic modulus (Z250: 6.6 ± 1.3, FBF: 6.4 ± 0.9, TBF: 4.3 ± 1.3). The hardness of Z250 was similar only between 0-1 mm and 1-2 mm. Both BFCs had similar hardness until 2-3 mm, and showed significant decreases at 3-4 mm (FBF: 33.45 ± 1.95 at 0-1 mm to 23.19 ± 4.32 at 3-4 mm, TBF: 23.17 ± 2.51 at 0-1 mm to 15.11 ± 1.94 at 3-4 mm). The BFCs showed higher translucency than Z250. The polymerization kinetics of all the materials were similar at 2-mm increments. At 4-mm, only TBF had a similar degree of conversion compared with 2 mm. Conclusions: The BFCs tested had similar performance compared to the conventional composite when used in up to 2-mm increments. When the increment was thicker, the BFCs were properly polymerized only up to 3 mm.

• Restorative Dentistry and Endodontics
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• 제46권4호
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• pp.51.1-51.13
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• 2021

Objectives: This study aimed to evaluate the effect of improper positioning single-peak and multi-peak lights on color change, microhardness of bottom and top, and surface topography of bulk fill and incremental composites after artificial aging for 1 year. Materials and Methods: Bulk fill and incremental composites were cured using multi-peak and single-peak light-emitting diode (LED) following 4 clinical conditions: (1) optimal condition (no angulation or tip displacement), (2) tip-displacement (2 mm), (3) slight tip angulation (α = 20°) and (4) moderate tip angulation (α = 35°). After 1-year of water aging, the specimens were analyzed for color changes (ΔE), Vickers hardness, surface topography (Ra, Rt, and Rv), and scanning electron microscopy. Results: For samples cured by single-peak LED, the improper positioning significantly increases the color change compared to the optimal position regardless of the type of composite (p < 0.001). For multi-peak LED, the type of resin composite and the curing condition displayed a significant effect on ΔE (p < 0.001). For both LEDs, the Vickers hardness and bottom/top ratio of Vickers hardness were affected by the type of composite and the curing condition (p < 0.01). Conclusions: The bulk fill composite presented greater resistance to wear, higher color stability, and better microhardness than the incremental composite when subjected to improper curing. The multi-peak LED improves curing under improper conditions compared to single-peak LED. Prevention of errors when curing composites requires the attention of all personnel involved in the patient's care once the clinical relevance of the appropriate polymerization reflects on reliable long-term outcomes.

• Restorative Dentistry and Endodontics
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• 제45권1호
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• pp.10.1-10.8
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• 2020

Objectives: This study aimed to compare the shear bond strength (SBS) of a self-adhering flowable composite (Dyad Flow) and a bulk-fill flowable composite (Smart Dentin Replacement [SDR]) to several pulp-capping materials, including MTA Plus, Dycal, Biodentine, and TheraCal. Materials and Methods: Eighty acrylic blocks with 2-mm-deep central holes that were 4 mm in diameter were prepared and divided into 2 groups (n = 40 each) according to the composite used (Dyad Flow or SDR). They were further divided into 4 sub-groups (n = 10 each) according to the pulp-capping agent used. SBS was tested using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed using 2-way analysis of variance. A p value of < 0.05 was considered to indicate statistical significance. Results: A statistically significant difference (p = 0.040) was found between Dyad Flow and SDR in terms of bond strength to MTA Plus, Dycal, Biodentine, and TheraCal. Conclusions: Among the 8 sub-groups, the combination of TheraCal and SDR exhibited the highest SBS.

• 센서학회지
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• 제10권6호
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• pp.279-285
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• 2001

본 연구에서는 HNA를 이용한 Si의 bulk 식각을 통해 렌즈 모양을 갖는 몰드를 제작 한 뒤 그 위에 렌즈로 사용될 SU-8을 도포 한 다음 몰드와 렌즈를 분리시키는 방법으로 마이크로렌즈 배열을 제조하는 공정을 개발하였으며 이는 공정순서가 단순하며 경제적인 것을 특징으로 한다. Stirring 속도 800rpm 이상의 조건에서 높이 $45{\mu}m$, 직경 $150{\mu}m$의 높은 fill factor를 가지는 렌즈의 제작조건을 확립하였으며, 이와 같이 제작된 초소형 렌즈는 적외선 감지 소자와 같은 영상 소자나 projection display 영역에 응용되어 소자 성능을 향상시킬 수 있다.

• 한국토양비료학회지
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• 제14권4호
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• pp.190-194
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• 1982

개간지(開墾地)에서 절토지(切土地)와 성토지(盛土地)의 토양생산력(土壤生産力)을 연차적(年次的)으로 비교(比較)하기 위(爲)하여 경기도(京畿道) 평택(平澤)에서 콩-보리, 고구마-보리 작부(作付)를 대상(對象)으로 3년간(年間) 시험(試驗)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 개간후(開墾後) 절토지(切土地)의 가비중(假比重)과 경도(硬度)는 각각(各各) $1.52g/cm^3$, 23.3mm이었고 성토지(盛土地)는 $1.32g/cm^3$, 14.3mm이었다. 성토지(盛土地)에서 고구마 재배(栽培)는 우량(優良)한 물리성(物理性) 유지(維持)에 효과적(效果的)이었다. 2. 토양화학성(土壤化學性)의 보지능력(保持能力)은 절토지(切土地)에서 낮았고 성토지(盛土地)는 3년차(年次)까지도 높았다. 3. 절토지(切土地)의 작물(作物) 수량(收量)은 낮았으나 작기(作期)에 따라 증가(增加)하는 경향(傾向)이었고 성토지(盛土地)는 개간당년부터 안정(安定)된 수량(收量)을 얻을 수 있었다.

• Restorative Dentistry and Endodontics
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• 제47권1호
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• pp.5.1-5.11
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• 2022

Objectives: This study aimed to assess the clinical longevity of a bulk-fill resin composite in Class II restorations for 3-year. Materials and Methods: Patient record files acquired from the 40 patients who were treated due to needed 2 similar sizes Class II composite restorations were used for this retrospective study. In the experimental cavity, the flowable resin composite SDR was inserted in the dentinal part as a 4 mm intermediate layer. A 2 mm coverage layer with a nano-hybrid resin composite (CeramX) was placed on SDR. The control restoration was performed by an incremental technique of 2 mm using the nano-hybrid resin composite. The restorations were blindly assessed by 2 calibrated examiners using modified United States Public Health Service criteria at baseline and 1, 2, and 3 years. The data were analyzed using non-parametric tests (p = 0.05). Results: Eighty Class II restorations were evaluated. After 3-years, 4 restorations (5%) failed, 1 SDR + CeramX, and 3 CeramX restorations. The annual failure rate (AFR) of the restorations was 1.7%. The SDR + CeramX group revealed an AFR of 0.8%, and the CeramX group an AFR of 2.5% (p > 0.05). Regarding anatomical form and marginal adaptation, significant alterations were observed in the CeramX group after 3-years (p < 0.05). The changes in the color match were observed in each group over time (p < 0.05). Conclusions: The use of SDR demonstrated good clinical durability in deep Class II resin composite restorations.

• 구강회복응용과학지
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• 제31권4호
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• pp.294-300
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• 2015

목적: 저점도 벌크필레진과 복합레진을 적층한 수복물의 색조를 평가하기 위함이다. 연구 재료 및 방법: 저점도 벌크필레진(SDR)과 A2, A3 색조의 미세혼합형 복합레진(A2, A3)을 4 mm 두께로 제작하여 광중합한 후 색차계를 이용하여 레진 시편의 CIE $L^*a^*b^*$ 값을 측정하였다. 이후 저점도 벌크필레진 상방에 2 mm 두께로 A2, A3 색조의 미세혼합형 복합레진을 적층하여(SA2, SA3) 광중합한 후 색측정을 하고(n = 10), 저점도 벌크필레진과 미세혼합형 복합레진, 그리고 이들을 적층한 시편의 색차(${\Delta}E$)를 계산하였다. 결과: $L^*$ 값은 SDR이 가장 컸고 SA2, SA3 그리고 A2, A3 순으로 감소했다. $a^*$ 값은 SDR이 가장 작았고 SA2, SA3 그리고 A2, A3 순으로 증가했다. $b^*$ 값은 SDR이 가장 작았으며 A2, SA2 그리고 A3, SA3 순으로 증가했다. 적층한 시편과 미세복합형 복합레진 시편의 ${\Delta}E$ 값은 A2와 SA2 사이에 ${\Delta}E=3.4$, A3와 SA3 사이에 ${\Delta}E=3.1$로 계산되었다. 결론: 저점도 벌크필레진과 미세혼합형 복합레진을 적층한 시편과 미세혼합형 복합레진만으로 제작한 시편의 색조의 차이는 일반적으로 인지하지 못할 정도로 작았다.

• 한국재료학회지
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• 제31권2호
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• pp.108-114
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• 2021

In the manufacturing of bulk graphite, pores produced by vaporization and discharge of volatile materials in binders during carbonization reduce the density of bulk graphite, which adversely affects the electrical conductivity, strength and mechanical properties. Therefore, an impregnation process is introduced to fill the pores and increase the density of bulk graphite. In this study, bulk graphite is prepared by varying the viscosity of the impregnant. The microstructure of bulk graphite is observed. The flexural strength and electrical resistivity are measured. As the viscosity of the impregnants decreases and the number of impregnations increases, it is shown that the number of pores decreases. The density before impregnation is 1.62 g/㎤. The density increases to 1.67 g/㎤ and porosity decreases by 18.6 % after three impregnations using 5.1 cP impregnant, resulting in the best pore-filling effect. After three times of impregnation with a viscosity of 5.1 cP, the flexural strength increases by 55.2 % and the electrical resistivity decreases by 86.76 %. This shows that a slight increase in density due to the pore-filling effect improves the properties of bulk graphite.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.230.2-230.2
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• 2003

Erdosteine, an expectorant, has been known to show a very poor flowability. Furthermore, high dosing amount (300mg/cap) and bulk density make it more difficult to fill in a capsule less than No. 0 size as bulk state. We have studied the possibility of dry granulation process in purpose of getting a better flowability and manufacturing efficiency. A roller compactor was introduced for this purpose and the applicability of laboratory result into commercial scale instrument was also experimented.Roller compacting process was very favorable to obtain the granules with good flowability and improved density profiles. (omitted)

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.869-872
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• 2000

The aim of present work was to fabricate the piezoelectric composite materials of low megahertz applications such as non-destructive testing of materials. Among all the various composites, those with PZT rods embedded in Spurrs epoxy with regular periodicity (1-3 connectivity) was fabricated by dice and fill method. The fabricated size of the PZT cell were 0.18X0.18, 0.28X0.28mm$^2$, respectively. And the volume ratio of the PZT cell were 52, 64%, respectively. The resonant frequency and anti-resonant frequency of the composites were 3.5 MHz and 4.3MHz, respectively. The piezoelectric coupling coefficient were about 38 and 37% and the mechanical quality factor were about 12.7 and 22. These value were very different from these of bulk PZT Plate.