• Advances in environmental research
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• 제7권1호
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• pp.39-52
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• 2018

Direct membrane filtration (DMF) of wastewater has many advantages over conventional biological wastewater treatment processes. DMF is not only compact, but potentially energy efficient due to the lack of biological aeration. It also produces more biosolids that can be used to produce methane gas through anaerobic digestion. Most of ammoniacal nitrogen in wastewater is preserved in effluent and is used as fertilizer when effluent is recycled for irrigation. In this study, a technical feasibility of DMF was explored. Organic and nitrogen removal efficiencies were compared between DMF and membrane bioreactor (MBR). Despite the extremely high F/V ratio, e.g., $14.4kg\;COD/m^3/d$, DMF provided very high COD removal efficiencies at ~93%. Soluble microbial products (SMP) and extracellular polymeric substances (EPS) were less in DMF sludge, but membrane fouling rate was far greater than in MBR. The diversity of microbial community in DMF appeared very narrow based on the morphological observation using optical microscope. On the contrary, highly diverse microbial community was observed in the MBR. Microorganisms tended to form jelly globs and attach on reactor wall in DMF. FT-IR study revealed that the biological globs were structurally supported by feather-like materials made of secondary amines. Confocal laser scanning microscopy (CLSM) study showed microorganisms mainly resided on the external surface of microbial globs rather than the internal spaces.

• 산업기술연구
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• 제31권B호
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• pp.119-125
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• 2011

N-doped Titanium oxides were prepared by using urea as a source of nitrogen. The photoactivities of the doped $TiO_2$ were evaluated on the basis of degradation of humic acid in aqueous solutions with different light sources, ultraviolet lamp, fluorescent lamp and solar light. XRD analysis was conducted to identify the crystal structure of the synthesized photocatalysts. N-doped $TiO_2$ and $pure-TiO_2$ was anatase type. SEM results showed that spherical particles were formed, which are the characteristics of the anatase form. N doped $TiO_2$ showed higher $UV_{254}$ decrease ratio and DOC removal ratio compared to $pure-TiO_2$. The humic acid degradation reaction using the UV-A lamp and UV-C lamp was assigned to pseudo-first order reaction. For solar light, only $pure-TiO_2$ and $N-TiO_2$ exhibited the pseudo-first order reaction.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.310-313
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• 2002

Structures obtained with a direct boning of two FZ silicon wafers joined in such a way that a smooth surface of one wafer was attached to the grooved surface of the other were studied. A square net of grooves was made with a conventional photo lithography process. After high temperature annealing the appearance of voids and the rearrangement of structural defects were observed with X-ray diffraction topography techniques. It was shown that the formation of void free grooved boundaries was feasible. In the cases when particulate contamination was prevented, the voids appeared in the grooved structures could be eliminated with annealing. Since it was found that the flattening was accompanied with plastic deformation, this deformation was suggested to be intensively involved in the process of void removal. A model was proposed explaining the interaction between the structural defects resulted in "a dissolution" of cavities. The described processes may occur in grooved as well as in smooth structures, but there are the former that allow to manage air traps and undesirable excess of dislocation density. Grooves can be paths for air leave. According to the established mechanisms, if not outdone, the dislocations form local defect arrangements at the grooves permitting the substantial reduction in defect density over the remainder of the interfacial area.

• 한국축산시설환경학회지
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• 제14권1호
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• pp.1-8
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• 2008

This study was conducted to solve the problem of public grievance owing to odor of a pig farm. Odor emissions from pig production systems mainly originate from liquid manure storage and solid manure fermentation. The low-cost odor abatement system (OAS) for application at liquid manure storage tank and solid manure fermentation facilities was developed in this study. The OAS adapted odor removing principles of a biofilter and biotrickling filter. The OAS is very simplified in structure. The appearance of the OAS had a form of cylindrical or cubical shape. The system performance was monitored for about one year after stabilization. A 7 seconds empty bed contact time for the OAS was adapted to achieve the odor reduction levels. The commercial type of OAS was constructed with media comprised of wood chips. Moisture content always remained above 50% wet basis. Average ammonia removal efficiency for the developed design was 89% at the liquid manure storage tank. Also, the removal efficiency at a solid manure fermentation facility was 86% on ammonia.

• 대한치과의사협회지
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• 제55권10호
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• pp.706-714
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• 2017

Background Synocial chondromatosis(SC), a proliferative disorder of the synovial membrane. The etiology or cause of SC remains unclear. SC usually occurs in large articular joints such as knee, hip, elbow, and ankle. SC of the TMJ is very rare. It is a benign disease that mainly affects unilateral side. It can form cartilagenous and calcified loose bodies of various sizes and cause abnormal function of TMJ. Case Report In this paper, we report two cases of SC in the upper joint space of the left TMJ. One complained that "Sometimes the left jaw joint feels disoriented" and the other had no symptoms. CT scan and MRI showed left TMJ space widening, multiple tiny calcified mass. After clinical and radiographic analysis, we performed surgical removal of the lesion under genereal anesthesia. In the histologic examination, synovial chondromatosis was diagnosed in both patients. Conclusions We report two cases of synovial chondromatosis in the upper joint space of the left TMJ. We performed surgical removal of the lesion. The two patients showed good prognosis without recurrence or pain up to date.

• 전기학회논문지
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• 제65권6호
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• pp.1108-1114
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• 2016

The cause of failure in the AT feeding system is divided into grounding, short-circuit of feeding circuit and internal faults of the railway substation. Since the fault current is very high, real-time current is detected and the failure must be immediately removed. In this paper, a new DC offset elimination filter that can remove component to decrease in the form of exponential function using low-pass filter was proposed in order to extract the fundamental wave from distorted fault current. In order to confirm the performance of the proposed filter method, AT feeder system was modelled by simulation tool and simulations were performed under various conditions such as fault location, fault resistance and fault voltage phase angle in case of trolley-rail short-circuit fault. When applying the proposed DC-offset removal method, it can be seen that the phase delay and gain error did not appear.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.561-561
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• 2012

Graphene, two dimensional single layer of carbon atoms, has tremendous attention due to its superior property such as fast electron mobility, high thermal conductivity and optical transparency, and also found many applications such as field-effect transistors (FET), energy storage and conversion, optoelectronic device, electromechanical resonators and chemical sensors. Several techniques have been developed to form the graphene. Especially chemical vapor deposition (CVD) is a promising process for the large area graphene. For the electrically isolated devices, the graphene should be transfer to insulated substrate from Cu or Ni. However, transferred graphene has serious drawback due to remaining polymeric residue during transfer process which induces the poor device characteristics by impurity scattering and it interrupts the surface functionalization for the sensor application. In this study, we demonstrate the characteristics of solution-gated FET depending on the removal of polymeric residues. The solution-gated FET is operated by the modulation of the channel conductance by applying a gate potential from a reference electrode via the electrolyte, and it can be used as a chemical sensor. The removal process was achieved by several solvents during the transfer of CVD graphene from a copper foil to a substrate and additional annealing process with H2/Ar environments was carried out. We compare the properties of graphene by Raman spectroscopy, atomic force microscopy(AFM), and X-ray Photoelectron Spectroscopy (XPS) measurements. Effects of residual polymeric materials on the device performance of graphene FET will be discussed in detail.

• 한국세라믹학회지
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• 제55권5호
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• pp.473-479
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• 2018

Highly toxic gases such as hydrogen sulfide ($H_2S$), carbon dioxide ($CO_2$), and ammonia ($NH_3$) are generated by both nature and human activities and affect human health. In this research, activated carbon combined with $Ca(OH)_2$ and $CaCO_3$ (AC-CO and AC-CC, respectively) were fabricated and applied in absorbing toxic gases from air pollutants. Activated charcoal powder was compressed in the form of pellets and used in the designated conditions. The optimum operating conditions and material properties, such as adsorption capacity, effect of weight ratio of the mixture, and hardness, have been investigated after combining with the calcium derivative. The good performance exhibited in this study suggests that this material is expected to be an effective and economically viable adsorbent for $NH_3$, $CO_2$, and $H_2S$ removal from the air system.

• 한국환경보건학회지
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• 제34권3호
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• pp.247-254
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• 2008

Non-point source pollution that originates from surface applied chemicals in either liquid or solid form is a part of urban activities and it appears in the surface runoff caused by rainfall. This study investigates the characteristics of non point source pollution in relation to storm events and the first washing effect in the Study area, which is comprised of different land use types. Then, a Best Management Practices (BMP) model, for urban areas, is applied with the Storm water Management Model (SWMM) Windows Interface which was developed by the EPA in the USA. During the storm event analysis of the hydrographic and pollutographic data showed that the peak of pollutants concentration was within the peak flow, 30 to 60 minute into the storm event in the Study area. The results of simulation using SWMM Windows Interface, Structure Techniques as applied in the study were highly efficient for removal of pollutants. Predicted removal efficiency was 26.0% for SS, 22.1 for BOD, 24.1% for COD, 20.6% for T-N, and 21.6% for T-P, respectively.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.1015-1020
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• 2007

A simple approach to prepare arrays of Au/TiO2 composite nanoparticles by using Au-loaded block copolymers as templates combined with a sol-gel process is described. The organic-inorganic hybrid films with closely packed inorganic nanodomains in organic matrix are produced by spin coating the mixtures of polystyrene-block-poly(ethylene oxide) (PS-b-PEO)/HAuCl4 solution and sol-gel precursor solution. After removal of the organic matrix with deep UV irradiation, arrays of Au/TiO2 composite nanoparticles with different compositions or particle sizes can be easily produced. Different photoluminescence (PL) emission spectra from an organic-inorganic hybrid film and arrays of Au/TiO2 composite nanoparticles indicate that TiO2 and Au components exist as separate state in the initial hybrid film and form composite nanoparticles after the removal of the block copolymer matrix.