• Clean Technology
• /
• v.30 no.2
• /
• pp.113-122
• /
• 2024

In order to better understand carbon dioxide recycling, the carbon dioxide capture characteristics of six different alkaline industrial by-products, including incineration ash, desulfurized gypsum, low-grade quicklime, and steelmaking slag were investigated using a laboratory-scale direct aqueous carbonation reactor. In addition to the dissolution characteristics of each sample, the main reaction structure was confirmed through thermogravimetric analysis before and after the reaction, and the reactive CaO content was also defined through thermogravimetric analysis. The carbon dioxide capture capacity and efficiency of quicklime were determined to be 473 g/kg and 86.9%, respectively, and desulfurized gypsum and incineration ash were also evaluated to be relatively high at 51.1 to 131.7 g/kg and 51.2 to 87.7%, respectively. On the other hand, the capture efficiency of steelmaking slag was found to be less than 10% due to the influence of the production and post-cooling conditions. Therefore, in order to apply the carbonation process to steelmaking slag, it is necessary to optimize the slag production conditions. Through this study, it was confirmed that the carbon dioxide capture characteristics of incineration ash, quicklime, and desulfurized gypsum are at levels suitable for carbonation processes. Furthermore, this study was able to secure basic data for resource development technology that utilize carbon dioxide conversion to produce calcium carbonate for construction materials.

• Resources Recycling
• /
• v.10 no.1
• /
• pp.56-65
• /
• 2001

Chemical decontamination techniques have been employed to reuse the high cost check valves contaminated with radioactivity and to reduce the radiation exposure during the inspection and maintenance work of safety injection system containing check valves. After chemical decontamination, an ultrasonic treatment was conducted to remove the fine solid particles retained in the crevices of check valves. The decontamination process conditions and the amount of chemical reagents were determined from the results of a pre-test, using the (list arm holder. The decontamination factors (DF), estimated from the activity in the solution, ranged from 14.5 to 18.5 corresponding to the activity removal of 93-95ft. The corrosion test data indicated that the general corrosion rate during a chemical decontamination-ultrasonic treatment process are low for type 304 S tainless steel, Inconel -600 and Stellite-6 materials $ (2.1\times10^{-2}$ $6.0\times10^{-2}$ and$ 1.7\times10^{-2}$ mil, respectively).

• Applied Chemistry for Engineering
• /
• v.9 no.2
• /
• pp.243-248
• /
• 1998

This study investigated the separation and the property of palladium precipitate formed by ascorbic acid in a simulated radioactive liquid waste, which was composed of 10 elements((Pd, Ru, Rh, Nd, Cs, Sr, Fe, Ni, Zr, Mo). Pd was separated selectively by using reduction characteristics of metal ions contained in the simulated waste with ascorbic acid. When the nitric acid concentration was 0.5 M, the Pd over 99.5% was precipitated by adding 0.04 M ascorbic acid. Nitric acid concentration is important at the reduction reaction of Pd ion. The precipitation yield of Pd was decreased as the concentration of nitric acid was increased. The Pd precipitate was re-dissolved in reaching at an equilibrium when the concentration of nitric acid was high and ascorbic acid was added with a small amount. The Pd precipitate formed by ascorbic acid was Pd metal and was aggregated by particles less than $1.0{\mu}m$.

• Journal of the Korea Concrete Institute
• /
• v.16 no.1 s.79
• /
• pp.54-60
• /
• 2004

This study deals with the setting behavior of polystyrene mortars using waste expanded polystyrene(EPS) solution-based binders. The binders for polystyrene mortars are made by mixing crosslinking agent with EPS solutions prepared by dissolving EPS in styrene. Polystyrene mortars are prepared with various EPS concentrations of EPS solutions and crosslinking agent contents, subjected to a dry curing, and tested for working life, peak exotherm temperature and 10h-length change. From the test results, He working lives of polystyrene mortars are shortened with raising EPS concentration of EPS solution and crosslinking agent content. Low-shrinkage or non-shrinkage polystyrene mortars could be obtained by adjusting EPS concentration of EPS solution and crosslinking agent content.

• Journal of Korea Foundry Society
• /
• v.34 no.3
• /
• pp.94-99
• /
• 2014

A commercially used Zr-based amorphous alloy was recycled and the effects of introducing carbon during recycling on the glass forming ability and mechanical properties of the alloy were investigated. The initial carbon content used in this study was 229ppm. The carbon content was gradually increased as the number of recycling iterations was increased and after the $4^{th}$ recycling it rapidly increased. As return scrap was recycled, polygonal particles precipitated, and they were identified as ZrC. The amount of the precipitates also increased with recycling. Tg, Tx and ${\Delta}T$ of the base alloy were 615 K, 696 K and 81 Kr respectively and they changed to 634 K, 706 K and 72 K after the $10^{th}$ recycling. The decrease of the ${\Delta}T$ value indicates deterioration of the glass forming ability. Hardness was not changed during three iterations of recycling but after the $4^{th}$ recycling it significantly increased. This is ascribed to an increase of amount of the hard particles, namely ZrC.

• Composites Research
• /
• v.15 no.1
• /
• pp.53-60
• /
• 2002

Composite ablative tubes required capabilities of ablative and structural characteristics were fabricated through filament winding technique and several experiments were conducted to evaluate the structural performance of composite ablative tubes. For this purpose, manufacturing procedures were briefly described and then resin digestion method was applied to measure the fiber volume fraction and the void content of composite ablative tubes. The configuration of tensile specimen fur composite ablative tubes with not losing the continuity of reinforced fibers was suggested by evaluating mechanical properties of several types of the specimen with different widths. Also, suitable processing variables for composite ablative tubes were determined by evaluating mechanical properties of several types of the specimen with different processing variables. In addition, acoustic emission signals were obtained during the proof test and could be applicable to study the crack initiation and the damage mode of composite ablative tubes. Finally, the structural reliability of composite ablative tubes could be verified to satisfy design requirements through the proof and burst tests.

• The Journal of the Korea Contents Association
• /
• v.11 no.11
• /
• pp.145-155
• /
• 2011

This study aims to examine how convention & exhibition visitors perceived value on their satisfaction, revisit and recommendation intention. To accomplish the goals, a field survey was conducted on the visitors of the COEX in Seoul area. The results of this study, based on a positive analysis, could be summarized as follows. First, perceived value is factorized as acquisition value, emotional value, monetary value, social value. Second, all factor of perceived value turned out to have affirmative effects on hotel employee's visitors satisfaction. Third, visitors satisfaction turned out to have affirmative effects on revisit intention. Forth, visitors satisfaction turned out to have affirmative effects on recommendation intention.

• Journal of the Korean Wood Science and Technology
• /
• v.21 no.4
• /
• pp.7-28
• /
• 1993

본 총설에서는 새로운 방부제와 방부처리 기술의 현재 발전 동향을 요약, 보고한다. 많은 새로운 방부제들이 약제의 독성 측면에서 환경적인 충격을 완화시킬 수 있는 잠재성을 가지고 있지만, 방부제로서 상업화되기 위해서는 이러한 약제들은 약제의 효능과 환경 안전성 간의 몇 가지 상호 조정 관계가 반드시 해결되어야 한다. Ammoniacal copper 계통의 방부제들이 지접부 사용에 적합한 새로운 수용성 방부제들의 주종을 이루고 있으며, 기존의 유용성 방부제들을 물에 용해한 emulsion 형태도 지접부 사용의 가능성을 보여 준다. 새로운 유용성 방부제 중에서 copper naphthenate, substituted isothiazolones, chlorothalonil, oxine copper가 지접부 사용을 위한 최상의 후보로 평가되고 있다. 유용성 방부제를 emulsion 형태로 사용하는 것은 유용성 방부제에 사용되는 석유 계통 용제의 소비를 감소시키기 때문에 중대한 의미를 가진다. 방부제들의 효능을 개선하고 강화시키기 위해 사용되는 첨가제들도 본 총설에서 거론된다. 재질개량을 위해 사용되는 비통상적인 방법(nonconventional system)들도 생물학적 열화 및 기상열화에 대한 저항성을 부여하여 목재의 사용수명을 증가시킨다. 전처리 공정에서 침상 자상처리(Needle incising)와 레이져 자상처리는 난주입 수종의 처리도를 개선시킬 수 있는 잠재성을 가지고 있다. 처리기술에 있어서 여러 가지 혁신적인 변화들은 기존의 처리 schedule을 조성함에 그 기본을 두고 있다. 난주입 수종의 처리도 개선은 pulsation법이나 고압 약제 분사법 (high energy liquid jets) 같은 고압을 적용하는 처리법에 의해서 달성된다. 미래의 처리공장들은 방부제를 기체상태로 또는 물질의 임계점 이상에서 방부제를 처리할 수도 있다. 이러한 새로운 접근은 외관이 깨끗하고, 처리도도 매우 양호한 처리재를 생산하는데 일조하리라 기대한다. 환경에 대한 대중적인 지대한 관심은 앞으로 목재 방부산업에 큰 영향을 미칠 것으로 보인다. 결과적으로 방부제의 처리목재내 가속 정착에 관한 연구에 상당한 노력이 투자될 것이다. 처리 후 가공에 관한 다른 주요한 연구는 방부제 처리 후 실시되는 재건조가 처리재의 역학적 성질에 미치는 영향에 대한 것이다.

• Journal of the Mineralogical Society of Korea
• /
• v.25 no.2
• /
• pp.117-122
• /
• 2012

The leaching of Li from fly ashes was studied. The fly ash produced from the Taean electric power plant of the Korea Western Power Co., Ltd. was used for this study. The Li leaching was observed according to the changes in solid:solution ratio, solution types (seawater or deionized water), and the $CO_2$ condition in the atmosphere. The results showed that the Li concentrations in the solution increased continuously as the solid:solution ratio increased. The Li leaching per unit mass of fly ash was greater when the deionized water was used for the experiment and when the $CO_2$ dissolution is limited during the reaction because the precipitation of $CaCO_3$ is suppressed under those conditions. At high solid:solution ratio, $Mg^{2+}$, the ion preventing the Li extraction from seawater by adsorption, was effectively removed from the seawater.

• KSBB Journal
• /
• v.10 no.5
• /
• pp.533-539
• /
• 1995

An autolytic system based on a thermally inducible phage lambda, λHL1, has been applied for the recovery of poly(3-hydroxybutyrate) [PHB] from a recombinant Escherichia coli XL1-Blue, harbouring a plasmid (pSYL105) containing the Alcaligenes eutrophus PHB biosynthesis genes. The lytic capability ofλHL1 was evaluated in flask culture for both lysogens, XL1-Blue (λHL1) and XL1-Blue (λHL1, pSYL105). When the optical density of culture at 600nm(OD600) reached 0.2, cell lysis was induced by increasing the temperature from $30^{\circ}C$ to $42^{\circ}C$. Most cells of XL1-Blue ($\lambda$HL1) were lysed by the autolytic system in an hour after the thermal induction, while the lytic efficiency was slightly lower for XLl-Blue (λHL1, pSYL105). The existence of pSYL105 in cells seemed to inhibit, to some extent, the lytic capability of λHL1 even at low PHB content. The lylic efficiency remarkably decreased as the induction was delayed to allow PHB accumulation. When a chemical induction using 2% (v/v) chloroform was introduced after an hours of thermal induction, we could obtain a good lytic efficiency.