• 설비공학논문집
• /
• 제14권12호
• /
• pp.1063-1070
• /
• 2002

To resist ice adhesion on cooling wall is concerned to continuous ice formation in thermal storage system. In this study, ice slurries were formed with two ecological aqueous solution, one is ethanol+silanol and the other is propylene glycol+silanol. By freezing under stirring the solution of $300m\ell$ in a stainless steel vessel which was immersed and cooled in a temperature controlled bath, the shape of ice slurry and the strength of ice adhesion on wall was observed with measuring the temperature and stirring load variation. As the concentration is smaller and the supercooling degree is larger, the ice adhesion is easy to occur. When the stirring load is larger than$ 2.1\times10^{-5}W$, the ice adhesion occurred.

• The Korean Journal of Ceramics
• /
• 제6권3호
• /
• pp.280-285
• /
• 2000

The electrolyte, $(HO)_2C_6H_2(SO_3Na)_2H_2O $(Tiron), disperses efficiently alumina powder in aqueous media and stable suspensions with 60 vol% solid loading can be prepared. The strong adsorption of this additive is mainly due to the ability of the molecule to form chelate rings with the particle surface but electrostatic interactions between the surface charge and the anionic dispersant strongly influence the amount of Tiron adsorbed. By using a cationic exchange route to substitute the counter ion which neutralizes the sulfonate groups, new molecules of dispersant have been prepared, either with mineral cations as $Li^+,\; Na+^,\; NH_4^\;+$, or with organic cations as counter ion but organic counter ions lead to less to less viscous suspensions than $Na^+$ in particular when the number of carbon atoms of the aliphatic chain increases from 1 to 3.

• The Korean Journal of Ceramics
• /
• 제4권4호
• /
• pp.292-296
• /
• 1998

In wet powder processing of alumina, a number of organic molecules such as dispersant and binder are used to produce the flow behavior and properties requisite for shape forming. In this study, interparticle forces of alumina particles suspended in aqueous media were controlled by suspension pH, poly (methacrylic acid) (PMAA, used as dispersant) and poly (vinyl alcohol) (PVA, used as binder). The combined adsorption isotherms of the dispersant and binder additives on alumina were determined by total organic carbon analyzer, while the adsorption of dispersant was differentiated from binder in the mixed additive system by ultraviolet spectroscopy. The electrokinetic behavior of alumina suspensions were then correlated with the adsorption characteristics of dispersant and binder onto alumina particles. It was found that the isoelectric ($pH_{iep}$) of alumina shifted from pH 8.9${\pm}$0.1 to acidic pH as PMAA concentration increased, while PVA adsorption did not affect the $pH_{iep}$ but caused a decrease in the near surface potential.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
• /
• pp.358-361
• /
• 2004

The photocatalytic degradation of Endocrine Discruptors, dibuthyl phthalate(DBP) has been investigated over TiO$_2$ photocatalysts irradiated with a ultraviolet (UV) light. The effect of operational parameters, i.e., reaction time, light intensity, pH and additive on the degradation rate of aqueous solution of Endocrine Discruptors has been examined. Results show that the employment of efficient photocatalysts and the selection of optimal operational parameters may lead to degradation of Endocrine Discruptors solutions.

• Korea-Australia Rheology Journal
• /
• 제14권3호
• /
• pp.129-138
• /
• 2002

A cationic surfactant, cetyltrimethylammonium $\rho$-toluenesufonate (CTA$\rho$TS), forms long threadlike micelles in aqueous solution. The threadlike micelles make concentrated entanglement networks, so that the solution shows pronounced viscoelastic behavior as concentrated polymer systems do. However, a mechanism for a process responsible for the longest relaxation time of the threadlike micellar system is different from that of semi-dilute to concentrated polymer systems. The threadlike micellar system exhibits unique viscoelasticity described by a Maxwell model. The longest relaxation time of the threadlike micellar system is not a function of the concentration of CTA$\rho$TS, but changes with that of $\rho$-toluenesufonate ($\rho$$TS^{-}$) ions in the bulk aqueous phase supplied by adding sodium $\rho$-toluenesulfonate (NapTS). The rates of molecular motions in the threadlike micelles are not influenced by the concentration of $\rho$$TS^{-}$ anions, therefore, molecular motions in the threadlike micelles (micro-dynamics) are independent of the longest relaxation mechanism (macro-dynamics). A nonionic surfactant, oleyldimethylamineoxide (ODAO), forms long threadlike micelles in aqueous solution without any additives. The aqueous threadlike micellar system of ODAO also shows Maxwell type viscoelastic behavior. However, the relaxation mechanism for the longest relaxation process in the system should be different from that in the threadlike micellar systems of CTA$\rho$TS, since the system of ODAO does not contain additive anions. Because increase in the average degree of protonation of head groups of ODAO molecules in micelles due to adding hydrogen bromide causes the relaxation time remarkably longer, changes in micro-structure and micro-dynamics in the threadlike micelle are closely related to macro-dynamics in contrast with the threadlike micellar system of CTA$\rho$TS.

• 한국식품영양과학회지
• /
• 제33권5호
• /
• pp.864-868
• /
• 2004

철분은 생체 내에서 이루어지는 거의 모든 대사에 필수적인 성분이지만, 식음에 포함된 철분의 양은 극히 적어서 철분강화에 대한 연구가 꾸준히 진행되어 왔다. 이에 따라， 철분공여물질을 함유한 리포즘을 이용하여 철분 강화 식품첨가제를 개발하였다. 철분공여물질로 ferrous sulfate와 hemin을 사용하였으며, 이러한 철분 함유 리포좀을 제조하는데 가장 큰 문제점은 ferrous sulfate의 자체 산화와 ferrous sul fate와 hemin으로 인한 리포좀의 지질산화로 지적되었다 또한, ferrous sulfate에 의한 리포좀의 산화 정도는 hemin의 경우보다 낮은 것으로 관찰되었다. Ferrous sulfate의 자동 산화를 억제하기 위하여 수용성 항산화제인 ascorbic acid가 첨가되었으나, 첨가된 ascorbic acid는 ferrous sulfate와 hemin을 함유한 리포좀의 산화를 억제시키지 못했으며, 오히려 ferrous sulfate에 의한 리포좀의 산화를 촉진시키는 것으로 관찰되었다 여기에 지용성 항산화제인 $\alpha$-tocopherol을 추가적으로 첨가함으로써, ferrous sulfate의 자동산화를 억제하고 hemin과 ferrous sulfate에 의한 리포좀의 산화가 억제된 철분 함유 리포좀이 제조되었다.

• Korean Chemical Engineering Research
• /
• 제48권2호
• /
• pp.157-163
• /
• 2010

CRT 용 shadow mask의 생산속도 향상을 위해 첨가제를 투입한 염화제이철 수용액을 개발하였고 이를 shadow mask의 식각속도 향상에 적용하였다. $Fe(ClO_4)_3$ 첨가제를 종래의 식각용액인 염화제이철 수용액에 투입한 결과, shadow mask의 식각속도가 크게 향상되었으며, 이때 첨가제의 농도가 증가할수록 식각속도가 증가함을 알 수 있었다. 또한 첨가제가 투입된 식각용액으로 순수 니켈과 철-니켈 합금(Invar 강)의 식각속도를 비교한 결과, 대부분의 공정조건에서 둘 사이의 식각속도 차이가 작음을 알 수 있었고, 이는 첨가제의 투입에 따라 니켈과 철의 식각속도가 모두 향상된 결과로 해석되었다. 첨가제의 주입에 따라 식각속도가 증가하는 이유는, 첨가제 내의 음이온인 $ClO^{4-}$가 염화제이철 수용액 내의 $Cl^-$에 비해 전자를 이동하는 가교로서의 역할이 우수하여 전자를 더 빠르게 이동시킬 수 있기 때문인 것으로 추정된다.

• 한국대기환경학회지
• /
• 제21권6호
• /
• pp.605-612
• /
• 2005

In this study, the possible use of HMDA (Hexamethylenediamine) as additive to enhance reaction between $CO_{2}$ and AMP (2-amino-2-methyl-1-propanol) which has higher absorption capacity than that of MEA (Monoethanolamine) was investigated. Also, the absorption capacity for $CO_{2}$ was compared with addition of HMDA, piperazine or MDEA (N-methyldiethanolamine) into $30\;wt\%$ AMP at $40^{circ}C$ and $CO_{2}$ partial pressure ranging from 0.5 to 120 kPa. Apparent rate constant ($K_{app}$) and absorption capacity with the addition of $5\∼20\;wt\%$ HMDA into AMP increased $214.2\∼276.3\%$ and $29.9\∼91.7\%$ than those of AMP alone. As a result, when $5\;wt\%$ HMDA added into AMP, the increasing rate of the absorption rate and the absorption capacity was found to be the highest. In addition, the absorption capacity increased $6.8\%,\;9.8\%,\;11.6\%$ with addition of MDEA, piperazine or HMDA respectively as compared to AMP alone at $CO_{2}$ partial pressure of 20 kPa. Consequently, HMDA as additive to improve absorption capacity of AMP was superior to other additives.

• 대한기계학회논문집B
• /
• 제27권5호
• /
• pp.604-611
• /
• 2003

This study was concerned with the enhancement of mass transfer by surfactant added to the aqueous solution of LiBr. Different vertical inner tubes were tested with and without an additive of normal octyl alcohol. The test tubes were a bare tube, groove tube, corrugate tube and inserted spring tubes. The additive concentration of normal octyl alcohol as a surfactant is about 0.08mass%. The Sherwood number was measured as a function of film Reynolds number 20~200. The experimental results were compared with those which use no surfactant. The enhancement of mass transfer by Marangoni convection effect which was generated by addition of the surfactant is proved for each testing tube Especially, it is clarified that the tube with the spring has the highest enhancement effect. A correlation of the experimental mass transfer data for the bare, groove, corrugate and insert spring tubes results expressed as the form of Sh=cㆍ Re$_{f}$ $^{n}$ .

• Journal of Advanced Marine Engineering and Technology
• /
• 제28권8호
• /
• pp.1239-1250
• /
• 2004

This research was concerned with the enhancement of heat transfer by surfactant added to the aqueous solution of LiBr. Different vertical tubes were tested with and without an additive of normal octyl alcohol. The test tubes are a bare inner surface. a groove inner surface, a corrugated inner surface and a spring inserted inner surface tubes. The additive concentration was about 0.08 mass%. The heat transfer coefficient was measured as a function of the film Reynolds number in the range of 20~200. Experiments were carried out at higher cooling water temperature of $35^{\circ}C$ to simulate an air cooling condition for several kinds of absorber testing tubes. The experimental results were compared with and without surfactant. The enhancement of heat transfer by Marangoni convection effect which was generated by addition of the surfactant is observed in each test tube. Especially, it is clarified that the tube with an inserted spring has the highest enhancement effect.