• Restorative Dentistry and Endodontics
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• 제32권5호
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• pp.445-458
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• 2007

단일과정 접착제를 이용함에 있어 복합레진과의 부적합성을 개선하고자 중간레진이 결합에 영향을 미칠 것으로 사료된다. Experimental single step system (Bisco Ltd., Schaumburg, IL)을 대조군으로 하고 6종의 중간레진을 접착제의 중합여부, 복합레진의 광중합-자가중합 여부로 분류하였다. 상아질에 대한 광중합 또는 자가중합형 복합레진의 결합강도를 측정하고 접착계면에 대한 투과전자현미경 관찰하여 다음과 같은 결론을 얻었다. 1. 중간레진의 적용은 광중합형 복합레진의 결합강도를 증가시키지 않았다. 2. 자가중합형 복합레진의 결합강도는 중간레진을 적용할 경우 증가하였다. 3. 중간레진의 적용 전 접착제의 중합여부는 결합강도의 변화에 영향을 미치지 않았다. 4. 중간레진이 친수성일 때 소수성 중간레진을 적용할 때 보다 높은 결합강도를 나타냈으나 통계적 유의차는 없었다. 광중합형 복합레진의 수복 시 단일과정 접착제를 사용하는 것은 초기 결합강도에 영향을 미치지 않으며, 자가중합형 복합레진을 단일과정 접착제와 사용할 때는 접착층의 투과도를 감소시키는 소수성의 중간레진을 적용하여 부적합성을 해소할 수 있을 것이다.

• Structural Engineering and Mechanics
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• 제55권1호
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• pp.137-160
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• 2015

The one-way (two-way) flexural strength of RCC prisms (circular slabs) reinforced with glass fiber textiles is addressed. To this end, alkaline-resistant glass fiber textiles with three surface weights were used in the composite, the matrix concrete was designed with zero/nonzero slump, and the textiles were used with/without an intermediate layer provided by epoxy resin and sand mortar. Prisms were tested under a four-point loading apparatus and circular slabs were placed on simple supports under a central load. Effects of the amount and geometry of reinforcement, matrix workability, and the intermediate layer on the ultimate load and deflection were investigated. Results revealed that, with a specific reinforcement amount, there is an optimum textile tex for each case, depending on the matrix mix design and the presence of intermediate layer. Similar results were obtained in one-way and two-way bending tests.

• Restorative Dentistry and Endodontics
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• 제32권4호
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• pp.313-326
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• 2007

본 연구는 단일 접착과정 상아질 접착제와 복합레진 사이에는 부적합성이 존재하며, 이를 개선하기 위해 중간 레진층이 필요하다는 가설을 규명하기 위해 시행되었다. 발치된 치아의 협설측 상아질에 3종의 단일 접착과정 상아질 접착제를 도포 후 광중합, 2종의 중간 레진층 적용, 광중합 또는 자가중합형 복합레진의 사용여부에 따라 30개의 실험군으로 분류하였다. 미세전단 결합강도를 측정하고 투과전자현미경 (TEM)을 이용하여 접착계면에서의 미세 누출과 수분의 이동경로를 관찰하여 접착제의 투과성을 평가하여 다음과 같은 결론을 얻었다. 중간 레진층을 적용 시 접착층의 투과도가 감소되었고 복합레진에 대한 단일 접착과정 상아질 접착제의 결합강도가 증가되었다. 따라서 시간 절약 및 간단한 접착과정을 선호하여 단순화된 상아질 접착제를 선택하는 것은 재고되어야 한다.

• 한국세라믹학회지
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• 제46권5호
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• pp.534-539
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• 2009

Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

• 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.

• Restorative Dentistry and Endodontics
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• 제31권2호
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• pp.103-112
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• 2006

본 실험에서는 자가부식형 접착제와 콤포짓트 레진 사이의 산도의 차이를 완화시킬 수 있는 접착레진을 자가부식형 접착제 위에 추가적으로 도포할 경우, 상아질에 대한 접착력을 개선할 수 있는지를 연구하였다. 자가부식형 접착제로는 실험실에서 직접 제작한 실험용 자가부식형 접착제 (pH: 1.96)와 Adper Prompt (3M ESPE, VSA, pH: 1.0)를 사용하였으며, 중성의 접착레진으로 All-Bond 2의 D/E bonding resin (Bisco Inc., USA, pH: 6.9)을 사용하였다. 두 대조군에서는 두 가지 자가부식형 접착제를 각각 두번씩 도포하였으며, 두 실험군에서는 각 자가부식형 접착제를 한번 도포한 후 그 위에 D/E bonding resin을 추가 도포하였다. Z-250 하이브리드 복합레진을 쌓아올려 모레시계 형태의 시편을 제작하여 미세인장강도를 측정하고 t-test를 이용하여 비교하였다. 파절 양상은 입체현미경과 주사전자현미경을 이용하여 관찰하였다. D/E bonding resin을 추가 도포한 미세 인장접착강도는 유의하게 증가되었고, 접착층과 복합레진 또는 접착층과 상아질 사이의 파절을 보인 시편의 수는 감소하고, 접착층 내의 파절을 보인 시편의 수는 증가되었다. 따라서 자가부식형 접착제와 복합레진의 산도의 차이를 완화할 수 있는 중성의 접착레진을 추가 도포할 경우 미세인장접착강도를 증가시킬 수 있음을 확인하였다.

• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.80-83
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• 2015

White reflective patterns are very difficult to fabricate, due to the scattering and reflection of light, especially when the pattern size goes down to micron size. A reflective white barrier structure of height $50{\mu}m$ and width $80{\mu}m$ was fabricated using dry-film resist as an intermediate reverse pattern. The reverse dry-film resist pattern was coated with an $SiO_2$ layer by sputtering, to protect the resist from chemical attack by the radical molecules in UV white resin. The UV white resin was applied on the dry-film resist pattern and then cured with ultraviolet light. The fine three-dimensional reflective patterns were finished by removing the dry-film resist.

• Applied Microscopy
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• 제1권1호
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• pp.11-17
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• 1969

Conidio spores of Aspergillus niger (strain No. NRRL 330) cultured on potato dextrose agar media were studied by electron microscopy, using the thin sectioning techniques. Conidio spores to be sectioned were fixed by triple methods with $K_2Cr_2O_7$, Glutaraldehyde and $OsO_4$. After dehydrated with alcohol, the specimens were embedded in metacrylate and epon resin media, and thinly sectioned by Porter-Blum MT-2. After sectioned these specimens were negative-stained with uranyl acetate and observed. by Hitachi HS-6 electron microscope. The results of this experiment were summarized as follows. 1. The structures of spore ,wall system seem to be formed 4 layers; exosporium, basal layer, spore coat and unit cell membrane. The protuberance of spore surface that was looked like hair appears to be protrusived from the basal layer. 2. The 3 layers of unit cell membrane was constituted outer layer membrane, inner layer membrane and inter-mediate light layer. 3. The structures of intra cytoplasmic membrane appear as spiral form which was consisted of 3 layers membrane system; outer membrane, inner membrane, and intermediate layer, which has pits. 4. The cement substance of spore coat and cortex may be changed quantitatively by physiological state in cell. 5. In some cases, we observed that the ribosome was transformed into poly ribosome group, and the storage materials and the protein crystals were changed variously. It. has been suggested that the morphological change of some cytoplasmic materials may be caused by some specialized function of the physiological stage.

• 상하수도학회지
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• 제22권1호
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• pp.131-140
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• 2008

The application of magnetic ion exchange resin($MIEX^{(R)}$) is effective for natural organic matter(NOM) removal and for control of the formation of disinfection byproducts(DBPs). NOM removal is also enhanced by adding $MIEX^{(R)}$ with coagulant such as polyaluminium chloride(PACl) in conventional drinking water treatment systems. In the application of $MIEX^{(R)}$, it is important to understand changes of NOM characteristics such as hydrophobicity and molecular weight distributions with $MIEX^{(R)}$ or $MIEX^{(R)}$+coagulant treatment.To observe characteristics of NOM by treatment with $MIEX^{(R)}$ or $MIEX^{(R)}$+coagulant, four major drinking water sources were employed. Results showed that the addition of $MIEX^{(R)}$ to coagulation significantly reduced the amount of coagulant required for the optimum removal of dissolved organic matter(DOC) and turbidity in the all four waters. The DOC removal was also increased approximately 20%, compared to coagulant treatment alone. The process with $MIEX^{(R)}$ and coagulant showed that complementary removal of hydrophobic and hydrophilic fraction of DOC. The combined processes preferentially removed the fractions of intermediate (3,000-10,000 Da) and low (< 500 Da) molecular weight. The microfiltration test showed that membrane cake resistance was decreased for waters with flocs from $MIEX^{(R)}$+coagulant. A porous layer was formed to $MIEX^{(R)}$ on the membrane surface and the layer consequently inhibited settling of coagulant flocs, which could act on a foulant.

• 한국정밀공학회지
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• 제24권8호통권197호
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• pp.138-143
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• 2007

Microstereolithography technology is similar to the conventional stereolithography process and enables to fabricate a complex 3D microstructure. This is divided into scanning and projection type according to aiming at precision and fabrication speed. The scanning MSL fabricates each layer using position control of laser spot on the resin surface, whereas the projection MSL fabricates one layer with one exposure using a mask. In the projection MSL, DMD used to generate dynamic pattern consists of $1024{\times}768$ micromirrors which have $13.68{\mu}m$ per side. The fabrication range and resolution are determined by the field of view of the DMD and the magnification of the projection lens. If using the projection lens with high power, very fine microstructures can be fabricated. In this paper, the projection MSL system adapted to a large surface for array-type fabrication is presented. This system covers the meso range, which is defined as the intermediate range between micro and macro, with a resolution of a few ${\mu}m$. The fabrication of array-type microstructures has been demonstrated to verify the performance of implemented system.