• Applied Chemistry for Engineering
• /
• 제31권5호
• /
• pp.552-559
• /
• 2020

Activated carbon-nickel (II) oxide (AC-NiO) electrodes were studied as materials for the capacitive deionization (CDI) of aqueous sodium chloride solution. AC-NiO electrodes were fabricated through physical mixing and low-temperature heating of precursor materials. The amount of NiO in the electrodes was varied and its effect on the deionization performance was investigated using a single-pass mode CDI setup. The pure activated carbon electrode showed the highest specific surface area among the electrodes. However, the AC-NiO electrode with approximately 10 and 20% of NiO displayed better deionization performance. The addition of a dielectric material like NiO to the carbon material resulted in the enhancement of the electric field, which eventually led to an improved deionization performance. Among all as-prepared electrodes, the AC-NiO electrode with approximately 10% of NiO gave the highest salt adsorption capacity and charge efficiency, which are equal to 7.46 mg/g and 90.1%, respectively. This finding can be attributed to the optimum enhancement of the physical and chemical characteristics of the electrode brought by the addition of the appropriate amount of NiO.

• Bulletin of the Korean Chemical Society
• /
• 제35권10호
• /
• pp.3015-3020
• /
• 2014

The behavior of benzo[a]pyrene-7,8-dione (BPQ) in aqueous solution and its interaction with native DNA was investigated using conventional absorption and linear dichroism (LD) spectroscopy. The appearance of a broad absorption maximum at long wavelengths and its proportional relationship to solvent polarizability suggested that BPQ adopts a aggregated state for all solutions examined. Disappearance of this absorption band at higher temperatures in aqueous solution also supported BPQ aggregation. When associated with DNA absorption spectral properties were essentially the same as that in aqueous solution. However, two isosbestic wavelengths were found in the concentration-dependent absorption spectrum of the BPQ-DNA complex, suggesting the presence of at least two or more DNA-bound BPQ species. Both species produced $LD^r$ spectra whose magnitude in BPQ absorption region is larger or comparable to that in the DNA absorption region, suggesting that the molecular BPQ plane is near perpendicular relative to the local DNA helical axis. Therefore, BPQ molecules are aligned along the DNA stem in both DNA-aggregated BPQ species.

• Macromolecular Research
• /
• 제10권4호
• /
• pp.187-193
• /
• 2002

Several methods have been used to synthesize polymer-clay nanocomposites. In-situ polymerization with clay belongs to a classical way to develop nano-structured materials, while melt intercalation is being recognized as another useful approach due to its versatility and environmentally benign character. In this research, we prepared polymer-clay nanocomposites based on the poly (methyl methacrylate) and organically modified montmorillonite via two-stage sonication process. According to the unique mode of power ultrasonic wave, the sonication during processing led to enhanced breakup of the clay agglomerates and reduction in size of the dispersed phase. Optimum conditions to form stable exfoliated nanocomposites were studied for various compositions and conditions. It was found that a novel attempt carried out in this study yielded further improvement in the mechanical performance of the nanocomposites compared to those produced by the conventional melt mixing process, as revealed by DMA, XRD and TEM. And rheological properties of nanocomposites were measured by ARES. As a result, sonicated PMMA-clay nanocomposites exhibits enhanced properties such as storage modulus and thermal stability than that of neat PMMA.

• Journal of Korean Society on Water Environment
• /
• 제31권4호
• /
• pp.367-376
• /
• 2015

The momentum and kinetic turbulent energy carried by the wind to a stratified lake lead to basin-scale motions, which provide a major driving force for vertical and horizontal mixing. A three-dimensional (3D) hydrodynamic model was applied to Lake Tahoe, located between California and Nevada, USA, to simulate the dominant basin-scale internal waves in the deep lake. The results demonstrated that the model well represents the temporal and vertical variations of water temperature that allows the internal waves to be energized correctly at the basin scale. Both the model and thermistor chain (TC) data identified the presence of Kelvin modes and Poincare mode internal waves. The lake was weakly stratified during the study period, and produced large amplitude (up to 60 m) of internal oscillations after several wind events and partial upwelling near the southwestern lake. The partial upwelling and followed coastal jets could be an important feature of basin-scale internal waves because they can cause re-suspension and horizontal transport of fine particles from nearshore to offshore. The internal wave dynamics can be also associated with the distributions of water quality variables such as dissolved oxygen and nutrients in the lake. Thus, the basin-scale internal waves and horizontal circulation processes need to be accurately modeled for the correct simulation of the dissolved and particulate contaminants, and biogeochemical processes in the lake.

• Journal of the Korean Society of Costume
• /
• 제60권10호
• /
• pp.88-99
• /
• 2010

The purpose of this study is to express visual and functional diversity through modifiable design, and to suggest a methodological model. With this view, this study was aimed to departmentalize the case of knitwear in modifiable design of clothes and propose the possibility of variable knit fashion through make the most of knit's characteristics. Four wearable physical clothes using the most of flexible knits' characteristics were made for this study based on the modifiable design on the expressive tendency and analysis of plasticity. The following results were obtained. First, as modifiable knit design can create effects of several dresses in visual aspect and functional aspect, so it has practicality and functionality. Because modifiable clothes required wearer's participation, this have amusement that give enjoyment and freshness to wearer. Second, in mode of wearing, flexibility of knit is suitable character to open & close and change of wearing position. In manipulation, a prearranged plan for line of clothes and good choice of subsidiary materials are important. Third, the characteristics of knits allow using and mixing with different pattern and materials on the two sides of the same cloths except for the some of the parts. Moreover, there is no unraveled thread on the part of knits margin against woven, so it has the broad applicable range for the changeable design. Finally, the form and function, a prearranged plan for modifiable design of clothes have all contributed in creating new structure and patterns in design.

• Proceedings of the KSME Conference
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.3013-3018
• /
• 2008

Supercharging system was adopted to investigate the influence of boost pressure on operating range, brake specific fuel consumption (BSFC) and exhaust emissions by using a supercharger at low temperature diesel combustion (LTC) condition in a 5-cylinder 2.7 L direct injection diesel engine. The experimental parameters such as injection quantity, injection timing, injection pressure and exhaust gas recirculation (EGR) rate were varied to find maximum operating range. The result showed that operating range with boost was expanded up to 41.9% compared to naturally aspirated LTC condition due to increased mixing intensity. The boosted LTC engine showed low BSFC value and dramatically reduced soot emission under all operating range compared with high speed direct injection (HSDI) mode. Finally, this paper presents the boosted LTC map of emission and the strategy of improved engine operating range.

• Journal of Fashion Business
• /
• 제8권6호
• /
• pp.39-56
• /
• 2004

At the outset, surrealism starts from pure art, but surrealism has greatly influenced commercial art and fashion circles, more so than any other genre of art. The critical thinking methods of surrealism and its mode of expression continues to influence fashion theory extensively. Even now, surrealism may be found in the designs presented in fashion circles and is still expected for future lines. Surrealism in modern fashion has been reborn, newly integrated and transformed, based on the features of Surrealism paintings. The characteristics of its forms can be found in a combination of modern material, modern design and new skills and the classical items : bodyform molding context of architecture, experimental and sex-appealing of body. Expression was made by borrowing natural motives and recreating natural fabrics while the existing typical idea about clothes was destructed, with the boundary of patterns changed. Expression was also made by mixing items, uniting future images, and using up-to-date functional techniques. This study is significant that up-to-date technological culture expands cyber-space and increases surrealistic expressions by combined heterogeneous materials, thus arousing much interest. The purpose of this study is to determine interrelationship between how surrealism developed and what formative properties those clothes affected by surrealism obtained in the 1990s.

• Journal of the Korean Society of Combustion
• /
• 제22권1호
• /
• pp.46-52
• /
• 2017

High-frequency combustion instabilities may occur during the development of feasible engine combustors. These instabilities can result in irreparable damages to the wall of combustors or the degradation of engine performance. So, it is essential to identify injectors that have high stability characteristics during the early stages of development. The objective of present study was to assess the stability of coaxial injectors and an impinging injector with different recess lengths in order to develop stable injectors optimally. Stability margin was evaluated based on the distance from operating condition to the unstable regions. A simulating combustion test method was used to analyze the stability of injectors. A small-scale combustion chamber was designed to simulate the first tangential acoustic mode of the actual combustor. Gaseous oxygen and a mixture of methane and propane were used as simulant propellants to satisfy their flow similarity to the actual propellants of a combustor in a liquid rocket combustor. The results indicated that injectors having small recess lengths showed relatively large combustion stability margins. For the injectors of large recess lengths, instability regions with large and super-large amplitude oscillations were observed. Thus, injector with shorter recess lengths had a higher stability than that of longer one due to the different mixing processes.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• 제30권5호
• /
• pp.457-464
• /
• 2006

Controlled auto ignition (CAI) combustion, also known as HCCI (homogeneous charge compression ignition), offers the potential to simultaneously improve fuel economy and reduce emission. CAI-combustion was achieved in a single cylinder gasoline DI engine, with a cylinder running in a CAI mode. Standard components were used the camshafts which had been modified in order to restrict the gas exchange process. The effects of air-fuel ratio, residual EGR rate and injection timing such as early injection and late injection on the attainable CAI combustion region were investigated. The effect that injection timings on factor such as start of combustion, combustion duration and heat release rate was also investigated. From results early injection caused the mixture to ignite earlier and burn more quickly due to the exothermic reaction during the recompression and gave rise to good mixing of the fuel-air.

• Korean Journal of Metals and Materials
• /
• 제49권12호
• /
• pp.930-936
• /
• 2011

In the present study, we show that the addition of Ag, an element having a positive enthalpy of mixing with Cu in the liquid state, enables the simultaneous enhancement of the glass forming ability and the plasticity in Cu-Zr-Ag bulk metallic glasses (BMGs). Rods of 4 mm diameter could be prepared with a fully amorphous structure and values of plastic strain up to 18% were measured under a compression mode for compositions around $Cu_{42.5}Zr_{47.5}Ag_{10}$. The possible role of Ag in the change of the atomic structure and the enhancement of the plastic strain in the ternary Cu-Zr-Ag BMGs is discussed based on analyses from transmission electron microscopy and EXAFS (extended X-ray absorption fine structure).