• 펄프종이기술
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• 제35권5호
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• pp.17-25
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• 2003

The influence of base paper properties and fiber type on coating penetration was studied in terms of characterization of coating holdout using two types of hand sheets as the base paper which were prepared from thermomechanical pulp (TMP) and hardwood bleached kraft pulp(KP) sized internally with alkyl ketene dimmer (AKD). Laboratory rod draw down coater was used for surface sizing and coating application. Characterization of coating penetration was done by measuring the roughness of the backside of coating layer. The backside of the coating was exposed by dissolving the fibers in a solution of cupriethylenedimine (CEO). Data show that internal sizing of base paper is effective and surface sizing is more effective to prevent coating penetration. Comparing between the two types of base papers, backside roughness of coating layer of TMP sheet is much larger and sizing is more effective to reduce coating penetration than those of KP sheet. From the result of water absorption and sizing degree after surface sizing, it seems that internal sizing slows down molecular diffusion much more than capillary penetration, but surface sizing reduces the capillary penetration. Furthermore, predominant mechanism of water into paper of TMP sheet seems to be capillary penetration, but it is molecular diffusion in the case of KP sheet.

• Environmental Engineering Research
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• 제16권2호
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• pp.97-102
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• 2011

This study investigates the treatment of pigment wastewater using a sequential batch reactor (SBR) followed by dissolved ozone flotation-pressurized ozone oxidation treatement (DOF-$PO_2$). The process efficiency has been evaluated at the lab scale on the basis of water quality parameters. In addition, the effect of pure oxygen and air was investigated on the removal of COD, BOD, and TN in the SBR process. It was observed that under comparable conditions the removal efficiencies of these water quality parameters using pure oxygen and air were similar. The effect of the recycle rate was also investigated for its impact on the water quality parameters using different ozone dissolving pressures in a DOF process in order to optimise conditions. The results conclude that the use of an SBR and ozone contact by DOF-$PO_2$ is a highly effective treatment for pigment wastewater and aids in the achievement of effluent discharge criteria.

• 한국물환경학회지
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• 제22권2호
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• pp.288-293
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• 2006

Basic investigations have been carried out for the solvent extraction of silver contained in the waste photographic fixing solution using D2EHPA as an extractant. Extraction experiments were conducted using artificial waste solution which was made by dissolving $AgNO_3$ in distilled water along with actual waste fixing solution. For artificial waste solution, the extraction of silver was found to occur very rapidly at the initial stage of extraction. In addition, more silver was extracted as the volumetric ratio between aqueous phase and organic phase was decreased. The volumetric ratio of organic extractant to diluent was also taken as an influential variable and the extracted amount of silver was observed to decrease with temperature. The characteristics of silver extraction for actual fixing solution was generally similar to that for artificial waste solution. Regarding the kinetic analysis, the extraction of silver contained in the actual solution was observed to follow a first order reaction.

• 한국산학기술학회논문지
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• 제5권4호
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• pp.350-353
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• 2004

일체형 원자로는 제어봉의 고장으로 인해 제어봉을 이용한 원자로 정지가 불가능한 경우 원자로에 붕산을 주입하여 정지시킨다. 일반적으로 붕산을 주입하는 방식은 붕산 분말을 물에 용해시켜 고농도의 붕산수를 만들어 저장하고 있다가 사용하는 것이다. 그러나 이와 같은 방식은 구성 기기의 수가 많고 구성이 복잡하므로 비경제적이며 운전과 계측제어 및 유지보수 측면에서 불리하다 본 연구에서는 이와 같은 단점을 개선하기 위해 붕산 분말을 원자로에 직접 주입하는 방식을 채택하였다. 붕산 분말을 원자로에 직접 주입하므로써 기기의 수가 줄어들고 계통의 구성, 운전 및 유지보수가 매우 단순해지고 경제적이다

• 한국환경과학회지
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• 제27권8호
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• pp.621-629
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• 2018

Many chemically active species such as ${\cdot}H$, ${\cdot}OH$, $O_3$, $H_2O_2$, hydrated $e^-$, as well as ultraviolet rays, are produced by Dielectric Barrier Discharge (DBD) plasma in water and are widely use to remove non-biodegradable materials and deactivate microorganisms. As the plasma gas containing chemically active species that is generated from the plasma reaction has a short lifetime and low solubility in water, increasing the dissolution rate of this gas is an important challenge. To this end, the plasma gas and water within reactor were mixed using the air-automizing nozzle, and then, water-gas mixture was injected into water. The dissolving effect of plasma gas was indirectly confirmed by measuring the RNO (N-Dimethyl-4-nitrosoaniline, indicator of the formation of OH radical) solution. The plasma system consisted of an oxygen generator, a high-voltage power supply, a plasma generator and a liquid-gas mixing reactor. Experiments were conducted to examine the effects of location of air-automizing nozzle, flow rate of plasma gas, water circulation rate, and high-voltage on RNO degradation. The experimental results showed that the RNO removal efficiency of the air-automizing nozzle is 29.8% higher than the conventional diffuser. The nozzle position from water surface was not considered to be a major factor in the design and operation of the plasma reactor. The plasma gas flow rate and water circulation rate with the highest RNO removal rate were 3.5 L/min and 1.5 L/min, respectively. The ratio of the plasma gas flow rate to the water circulation rate for obtaining an RNO removal rate of over 95% was 1.67 ~ 4.00.

• 한국수산과학회지
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• 제10권4호
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• pp.275-279
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• 1977

전성장실험기간을 통하여 잉어의 먹이 섭취와 성장 및 사료효율은 스트레이너의 지소회수, 오탁된 사육수의 교환정도, 먹이의 분할공급의 회수, 적량내의 먹이 공급 및 용존산소량에 직접적이고 직각적인 반응을 나타내었다. 그러나 지소나, 물 교환을 위한 취급에는 별로 영향을 받지 않는 것으로 보였다. 특히 해로운 점은 식욕이 왕성하지 못할 때 먹이를 주는 일과 일시에 과량의 먹이는 주는 것이었다. 특히 직각적으로 삼킬 수 있는 량을 주면 물에 녹아나는 것이 거의 없고, 먹이를 준 후에도 물이 투명하지만, 그 이상의 먹이를 주면 식욕이 왕성할 때는 입속에 여분의 먹이를 머금고 삼킬 노력을 함으로써 녹아서 물에 흩어져 나오는 량이 많고, 먹이를 준 후 물이 혼탁해 진다. 그리하여, 여과조를 포함한 사육수질을 악화시키고, 성장이 불량해지고, 또 사료의 효율을 심하게 저하시킨다.

• 한국염색가공학회지
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• 제15권4호
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• pp.43-50
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• 2003

N-methylmorpholine-N-oxide(NMMO) is recently hewn as a solvent dissolving cellulose to produce a new regenerated cellulosic fiber, lyocell. In this study, four kinds of cellulosic fibers (lyocell, regular cotton, treated cotton with 50% and 75% NMMO aqueous solution) was examined and compared in terms of mechanical properties and dyeability. The swelling of cotton treated with NMMO aqueous solution is higher than that of cotton treated with water. In dyeing rate, the cotton treated with NMMO was faster than regular cotton. NMMO treatment decreased the crystallinity of cotton fabrics and improved their softness and smoothness.

• 펄프종이기술
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• 제31권4호
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• pp.23-29
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• 1999

The effect of dilute sulfuric acid treatment was examined to improve recyclability of coated brokes. Turbidity , electric conductivity , and cationic demand of the white water from coated broke prepared from an alkaline base paper was determined. Sulfuric acid treatment was found to be effective in dissolving undisintegrated substances such as binders, pigments, and fibers. The properties of papers prepared by adding the broke to pulp stock up to 30% dry weight were examined . With the increase of broke addition, retention, sizing degree and smoothness were improved ; on the other hand, formation uniformness, air permeability and internal bonding strength were decreased. The extent of improvement by broke addition was greater for the surfuric acid-treated broke than the control broke. It was concluded that the use of coated broke should be limited within 10-15% weight of the product for either type of broke.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.773-776
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• 2005

MSWI ash is the residue from waste combustion processes at temperature between $850^{\circ}C\;and\;1000^{\circ}C$. And the main components of MSWI ash are $SiO_2,\;CaO\;and\;Al_2O_3$. The aim of this study is to find a way to useful application of MSWI ash(after treatment) as a structural material and to investigates the hydraulic activity, compressive strength development, composition variation of such chemicallyi-activated MSWI ashes concrete. And it was found that early cement hydration, followed by the breakdown and dissolving of the MSWI-ashes, enhanced the formation of calcium silicate hydrates(C-S-H), The XRD and SEM-EDS results indicate that, both the hydration degree and strength development are closely connected with a curing condition and a chemically-activator. Compressive strengths with values in the 40.5MFa were obtained after curing the activated MSWI ashes with NaOH+water glass at $90^{\circ}C$.

• Korea-Australia Rheology Journal
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• 제14권2호
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• pp.71-76
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• 2002

Metal thin films, which are indispensable constituents of ULSI (Ultra Large Scale Integration) circuits, have been fabricated by physical or chemical methods. However, these methods have a drawback of using expensive high vacuum instruments. In this work, the fabrication of tungsten metal film by spin coating was investigated. First of all, inorganic peroxopolytungstic acid (W-IPA) powder, which is soluble in water, was prepared by dissolving metal tungsten in hydrogen peroxide and by evaporating residual solvent. Then, the solution of W-IPA was mixed with organic solvent, which was spin-coated on wafers. And then, tungsten metal films, were obtained after reduction procedure. By selecting an appropriate organic solvent and irradiating UV, the sheet resistance of the tungsten metal film could be remarkably reduced.