• 폴리머
• /
• 제36권2호
• /
• pp.177-181
• /
• 2012

본 연구에서는 poly(dimethylsiloxane)(PDMS) 기반의 미세유체 시스템을 이용하여 이중 에멀젼을 형성하는 방법을 구현하였다. 반응기 친수성 연속상과 표면 젖음성을 향상시키기 위해 우선 PDMS 표면과 3-(trimethoxysilyl) propyl methacrylate(TPM)간의 졸-젤 반응을 통해 표면에 메타크릴레이트를 유도하였고, 선택적인 영역에 친수성 단량체인 아크릴산과 메타크릴레이트간의 공유결합을 유도하였다. 이를 확인하기 위해 아크릴산과 정전기적 인력 결합을 하는 염료를 통하여 선택적 표면 개질의 성공을 확인하였다. 사용된 유체로는 "spreading coefficient"를 도입하여 시스템 내에서 이중 에멀젼을 형성하는 조건을 예측하여 물과 0.5% w/w sodium dodecyl sulfate 혼합물, 헥사데칸 혼합물(hexadecane; 1% w/w Span80)을 선정하였다. 이를 통하여, 코어 및 쉘의 사이즈가 48.5 ${\mu}m$(CV:1.6%), 65.1 ${\mu}m$(CV:1.6%)인 단분산성 이중 에멀젼을 성공적으로 생성하였고, 유체의 유량 제어를 통하여 함입되는 코어의 개수 조절이 가능함을 보여주었다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
• /
• pp.73-76
• /
• 2009

Generally, wind or solar power system is operated as a stand-alone power system, the efficiency of which could be higher by designing wind-solar combined system considering average wind speed and solar radiation of the desert region, Mongolia. This system is designed to generate electricity for power users and pumps the ground water for irrigation using deep well pump. The ground water can be used for farming or forestation where there is no or little irrigation system. In connection with this study, a renewable energy park, Green Eco Energy Park, was developed at about 50km east of Ulaanbaatar. 3 sets of 10kW wind power generator and 70 kW of solar power module were installed there. The electricity generated from the system is used to on-site office building and deep well pump for ground water pumping. A 10kW stand-alone solar pumping system, which has no rechargeable battery system, is installed to pump the ground water with the amount of generated power. The ground water is stored in 3 artificial ponds and then it is used for raising nursery tree and farming. The purpose of this study is to provide a possible energy solution to desert regions where there is no or little power system. The system also supply power to ground water pump, and the water can be used for farming and forestation, which will also be a solution of preventing desertification or spreading of desert area.

• International Journal of Computer Science & Network Security
• /
• 제22권10호
• /
• pp.97-106
• /
• 2022

Objective. Nanotechnology is spreading among all areas of life, from everyday devices to medicine. The concept of nanotechnology argues that not only can new physical and chemical properties of materials be discovered, but also the new potential of nanostructures when reduced to the nanoscale. The growing interest in the application of nanomaterials in dentistry contributes to the proliferation of the range of nanomaterials used by specialists. The purpose of this review of information sources was to analyze the prospects for the use of nanomaterials in dentistry. Methods. We used the bibliographic semantic method of research, for which we analyzed electronic databases of primary literature sources Scopus, Web of Science, Research Gate, PubMed, MDPI, and MedLine. English-language scientific articles published after 2017 were taken into consideration. Results. According to the results of a search study among modern information primary sources, nanotechnology improves the preventive properties of oral care products, improves the structural-mechanical and aesthetic properties of composite mixtures for dentistry, overcomes the problems of the clinical application of dental implants. Despite the prospects of nanotechnology applications in medicine in general and dentistry in particular, the existing economic and technological problems require a thorough solution for further implementation of nanostructures. Scientific novelty. For the first time, the analysis of modern trends in the application of nanotechnology in dentistry is carried out and the peculiarities of materials are highlighted, the problems and prospects of nanostructures implementation in modern dental implantology are given, physical, chemical, mechanical, and antibacterial properties of nanomaterials are evaluated. The effect of nanomaterials on the microbial adhesion of the tooth or implant surface is described. Practical significance. The presented publication can become a scientific basis for the solution of urgent problems hindering the introduction of nanotechnology into dental practice. Conclusions. Thus, the use of nanostructures opens up great opportunities for the treatment of a wide range of diseases, not only of dental nature but also in medicine in general.

• 한국재료학회지
• /
• 제33권12호
• /
• pp.517-524
• /
• 2023

BaTiO₃-Poly vinylidene fluoride (PVDF) solution was prepared by adding 0~25 wt% BaTiO₃ nanopowder and 10 wt% PVDF powder in solvent. BaTiO₃-PVDF film was fabricated by spreading the solution on a glass with a doctor blade. The output performance increased with increasing BaTiO₃ concentration. When the BaTiO₃ concentration was 20 wt%, the output voltage and current were 4.98 V and 1.03 ㎂ at an applied force of 100 N. However, they decreased when the over 20 wt% BaTiO₃ powder was added, due to the aggregation of particles. To enhance the output performance, the generator was poled with an electric field of 150~250 kV/cm at 100 ℃ for 12 h. The output performance increased with increasing electric field. The output voltage and current were 7.87 V and 2.5 ㎂ when poled with a 200 kV/cm electric field. This result seems likely to be caused by the c-axis alignment of the BaTiO₃ after poling treatment. XRD patterns of the poled BaTiO₃-PVDF films showed that the intensity of the (002) peak increased under high electric field. However, when the generator was poled with 250 kV/cm, the output performance of the generator degraded due to breakdown of the BaTiO₃-PVDF film. When the generator was matched with 800 Ω resistance, the power density of the generator reached 1.74 mW/m². The generator was able to charge a 10 ㎌ capacitor up to 1.11 V and turn on 10 red LEDs.

• 대한기계학회논문집B
• /
• 제39권4호
• /
• pp.359-370
• /
• 2015

본 연구는 다양한 조건하에서 모세관력 불균형에 의해 구동되는 수평 표면 위의 액적 거동을 수치해석적으로 연구한 것이다. 액적 거동은 자체개발 코드(PowerCFD)를 사용하여 수치해석하였다. 수치해석에 사용된 코드는 보존적인 압력기반 유한체적방법에 기초한 비정렬 셀 중심 방법 및 VOF 방법에 체적포착법인 CICSAM을 채용하고 있다. 상세한 액적 거동이 다양한 초기 액적형상, 접촉각 및 표면장력(또는 Bond 수)의 조건하에서 얻어졌다. 또한 액적 이송 메커니즘이 액적 형상에 대한 수치해석 결과로부터 검토되었다.

• 한국전기전자재료학회논문지
• /
• 제28권7호
• /
• pp.446-449
• /
• 2015

An improvement of light-extraction efficiency of organic light-emitting diodes was studied by using random-textured films (RTF). Device was made in a structure of RTF/glass/ITO/TPD/$Alq_3$/LiF/Al. RTF mold was made by spreading PDMS solution on a sandpaper. By pressing this mold on the glass substrate pre-coated with ZPU material, the RTF was obtained. From this study, there was an improvement of external quantum efficiency by about 30% in the device with the random-textured film (RTF 40) compared to that of the reference one.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2009년도 추계학술발표대회
• /
• pp.42.1-42.1
• /
• 2009

In recent years, it has been tried to develop the efficacy and bioactivity of Calcium Phosphate cements(CPC) as injectable bone substitute (IBS) by reinforcing them through varying the amount in its compositions and relative concentrations or adding other additives. In this study, the biocompatibility of are inforced Calcium Phosphate-Calcium Sulfate injectable bone substitute (IBS)containing poly ($\varepsilon$-caprolactone)PCL microspheres was evaluated which consisted of solution chitosan and Na-citrate as liquid phase and tetra calcium phosphate (TTCP), dicalciumphosphate anhydrous (DCPA) powder as the solid phase. The in vitrobiocompatibility of the IBS was done using MTT assay and Cellular adhesion and spreading studies. The in vitro experiments with simulated body fluid (SBF) confirmed the formation of apatite on sample surface after 7 and 14 days of incubation in SBF. SEM images for one cell morphologies showed that the cellular attachment was good. MG-63 cells were found to maintain their phenotype on samples and SEM micrograph confirmed that cellular attachment was well. In vitro cytotoxicity tests by an extract dilution method showed that the IBS was cytocompatible for fibroblast L-929.

• 한국실내디자인학회논문집
• /
• 제19권2호
• /
• pp.15-23
• /
• 2010

First appeared in the 1970s, the underground shopping mall has been spreading across the country, and there reportedly exist 77 malls in the 2010. After over 30 decades operation, many underground shopping malls are now under the planning phase for renovation in many cities. This study considers the renovation issue of the underground shopping mall in the perspective of spatial re-configuration. A case is taken from Kangnam TerminalUnderground Shopping Mall in Seoul for detailed observation and suggestion. The monotonous and confusingspatial layout of the existing mall is investigated by observation methods. Based on the observation, a modifiedplan is suggested and evaluated by means of computer simulation program, Depth Map. The program mainly deals with visual network analysis in order to quantify the optical exposure in a given space. It is argued in this paper that the enhanced visual connectedness could affect the pedestrian performance positively in the shopping mall, and this leads to an easy and quick access to each shops in users' stand point. It is thought that this configurational solution for the remodelling of a specific case would be an effective reference for other malls in the country which are facing the similar problems.

• The Plant Pathology Journal
• /
• 제33권2호
• /
• pp.103-108
• /
• 2017

World wheat production is now under threat due to the wheat blast outbreak in Bangladesh in early March 2016. This is a new disease in this area, indicating the higher possibility of this pathogen spreading throughout the Asia, the world's largest wheat producing area. Occurrence of this disease caused ~3.5% reduction of the total wheat fields in Bangladesh. Its economic effect on the Bangladesh wheat market was little because wheat contributes to 3% of total cereal consumption, among which ~70% have been imported from other countries. However, as a long-term perspective, much greater losses will occur once this disease spreads to other major wheat producing areas of Bangladesh, India, and Pakistan due to the existing favorable condition for the blast pathogen. The wheat blast pathogen belongs to the Magnaporthe oryzae species complex causing blast disease on multiple hosts in the Poaceae family. Phylogenetic analysis revealed that the Bangladesh outbreak strains and the Brazil outbreak strains were the same phylogenetic lineage, suggesting that they might be migrated from Brazil to Bangladesh during the seed import. To protect wheat production of Bangladesh and its neighbors, several measures including rigorous testing of seed health, use of chemicals, crop rotation, reinforcement of quarantine procedures, and increased field monitoring should be implemented. Development of blast resistant wheat varieties should be a long-term solution and combination of different methods with partial resistant lines may suppress this disease for some time.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2011년도 정기 학술발표대회
• /
• pp.198-198
• /
• 2011

The numerical simulation of dam break problem suffers from several challenges in terms of accuracy, stability, and versatility of the simulation algorithm since the water flow is generally discontinuous and presents abrupt variations. Thus, to obtain stable and accurate solutions, flow models for this purpose require numerical schemes provided with shock-capturing properties, and with the ability to work with flexible two-dimensional meshes. In this context, SU/PG method(Hughes and Brooks, 1979) is excellent candidate for the solution of the dam break problem. The weak formulation of the equations and the discontinuous polynomial basis lead to an accurate representation of bore waves(shocks). Furthermore, the discretization of the domain in finite elements is extremely effective in modeling complex geometries. In this study, a finite element model based on the SU/PG scheme is developed to solve shallow water equations and the model is applied to dam break problem. It is found that the present model accurately captures the bore wave that propagates downstream while spreading laterally and the depression wave that moves upstream. Furthermore, the propagation and formation of water surface profile compared favorably with those obtained by the previously published results.