• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.04a
• /
• pp.117-120
• /
• 2007

This study investigated the spray modeling of the pressure-swirl atomizer installed in liquid rocket engine and the effect of drop distribution function especially. The $X^2$, originally implemented to KIVA, Rosin-Rammler and modified Rosin-Rammler distribution functions were investigated theoretically and compared to each other. Also, they were applied to pressure-swirl atomizer similar to the injector installed in liquid rocket engine to evaluate the feasibility for LRE injector. Among the distribution functions, original Rosin-Rammler distribution function was the most compatible with predicting the spray characteristics of pressure-swirl atomizer installed in liquid rocket engine.

• Applied Chemistry for Engineering
• /
• v.10 no.3
• /
• pp.450-455
• /
• 1999

Unsaturated diol (UD) was prepared from the esterification of maleic anhydride with diethylene glycol (DEG). Unsaturated polyesters modified with rosin (UPMR) or with rosin maleic anhydride adduct (RMA) from 2-hydroxyethylmethacrylate (HEMA) and rosin (UPMRH) were prepared by the reaction of UD with RMA or RMA-HEMA. After crosslinking of UPMR and UPMRH with styrene and methylmethacrylate (MMA), respectively, solvent resistance, tensile strength, and adhesion property of the resins were measured. UPMR crosslinked with styrene or MMA shows an excellent resistance to water and acid. Solvents resistance and tensile strength of UPMR using styrene as crosslinking agent were increased compared with those of UPMR using MMA as crosslinking agent. UPMRH showed better solvents resistance and tensile strength than UPMR. Adhesion strengths of UPMR crosslinked with styrene and MMA were 1.61 and 3.02 MPa, and those of UPMRH were 2.32 and 3.89 MPa, respectively.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.12 no.1
• /
• pp.145-157
• /
• 1994

Litho printing ink vehicles based on rosin modified phenolic are faster drying, have better durability, are harder and glosser and have greater resistance to water than ones based on ester gums. Ink-Water balance and rheological properties are important in litho printing process. These physical properties is concerned with molecular weight of Resin to use vehicle. So this paper was studied about the effects of changing molecular weight of Rosin modified phenolic on surface tension, viscosity, pseudoplasticity and printability of Litho Inks. The results were as follows. 1) The surface tension of model inks depended on the molecular \veight of the resin : Dispersion componnent of ink increase but non dispersion component decrease as molecular weight of Resin increase. 2) Water pick-up of litho ink is more fast balance, using low molecular weight of Resin. 3) Viscosity, Yield value and Newtonian value of model inks increase as molecular weight of Resin increase. 4) The litho ink prepared with the modified phenolic of which molecular weight is about 20000 showed the highest printing density and gloss.

• Polymer(Korea)
• /
• v.24 no.6
• /
• pp.757-762
• /
• 2000

Vinylbenzyloxystyrylpyridine (VSP) as a photosensitive monomer was synthesized by the reaction of 4-hydroxystyrylpyrydine with 4-vinylbenzyl chloride. Photocrosslinkable polymers containing rosin moiety were then prepared by radically copolymerizing VSP with a methacrylic monomer having rosin moiety. In these copolymerizations, the VSP feed ratios of 5 to 20 mol% were used. The contents of VSP units in the copolymers were determined by UV spectroscopy to be 5.3 to 17.3 mol%. The numberaverage molecular weights of these polymers were in the range of 18000 to 28000 and the polydispersity indexes were about 1.8. The glass transition temperatures were about 15$0^{\circ}C$ and the initial decomposition temperatures were about 34$0^{\circ}C$. The polymers were relatively fast photocrosslinked and the photocrosslinking reaction could be traced by the UV spectroscopy and the residual yield method.

• Applied Chemistry for Engineering
• /
• v.5 no.2
• /
• pp.313-320
• /
• 1994

Rosin-maleic anhydride adduct(RMA) was synthesized from rosin and maleic anhydride. Highly purified RMA for the application of polymerization monomer was synthesized by means of two methods; the melt reaction followed by further purification and the solution reaction. As a result of this study, the solution reaction was better than the melt reaction for obtaining higher yield of RMA. Maximum yield of RMA obtained by the melt reaction was only 40%. But the yield of RMA obtained by the reaction in carbon tetrachloride solution was 48%(theoretical yield 87.6%) and that obtained by the reaction in acetic acid solution was 51.5%(theoretical yield 94%) respectively.

• Korean Journal of Dental Materials
• /
• v.43 no.1
• /
• pp.81-89
• /
• 2016

The purpose of this study was to evaluate the effect of the experimental and commercial fluoride varnishes on the Vickers hardness of bovine teeth. The experimental fluoride varnishes with 5 wt.% NaF were fabricated using Bis-GMA or rosin as the resin base. The components were mixed with over-head stirrer under warming up in a double boiler for 30 minutes. Four commercial fluoride varnishes (V-varnish, Flor-opal, Cavity shield, Fluor protector) were compared with the experimental fluoride varnishes. Vickers hardness was measured on the labial surface of bovine anterior teeth after applying fluoride varnish on 5th and 30th day. The surface of bovine teeth was observed with a scanning electron microscope before and after applying fluoride varnish and the change of the components on the bovine teeth surface was measured with EDX. In terms of hardness, the experimental rosin-based fluoride varnish showed significantly higher hardness on the 5th and 30th day than the control (bovine teeth without fluoride treatment)(p<0.05). EDX results showed that the fluoride content on the surface of bovine teeth treated with the experimental rosin-based fluoride varnish was highest on the 1st and 10th day. The higher hardness and fluoride content of experimental rosin-based fluoride varnish can be considered to be used as an effective fluoride varnish to prevent dental caries.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.10
• /
• pp.3413-3416
• /
• 2012

Phenol-free resin was synthesized and its printing ink properties were investigated. The phenol-free resin was produced by esterification of poly phthalate and Diels-Alder adduct of rosin anhydride. Compared to rosin modified phenolic resin, eco-friendly phenol-free resin showed better vehicle properties in terms of gloss, yellowing, runability, and storage stability. The results suggest the utility of phenol-free resin instead of conventional rosin modified phenolic resin.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.24 no.1
• /
• pp.1-12
• /
• 2006

The rheological characteristics of an ink relate to its performance on the press and to the printing quality such as ink stability, transfer characteristics, mottle, squash, misting, dot gain, and so on. For lithographic print, the emulsification of ink is an important factor to determine the product. And also the rheological characteristics of the emulsified ink should be investigated. Thus, in this study, the effects of the changing molecular weight of rosin modified phenolic resin on the water-pickup ratio of neat inks were studied. And then rheological properties of neat inks and emulsified inks with changing molecular weight of rosin modified phenolic resin were analyzed by using rotational rheometer.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 1999.04b
• /
• pp.390-393
• /
• 1999

In this paper, a series of PAC (polyaluminum chloride) samples were prepared for rosin neutral sizing system. Some characters of PAC were discussed in detail. The experimental results show that it is possible to achieve neutral sizing when PAC is compounded with DRS (dispersed rosin size) instead of alum (aluminum sulfate).

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.48 no.2
• /
• pp.56-60
• /
• 2016

Neutral or alkaline papermaking provides many advantages in paper strength and processing conditions. It also provides the opportunity of using calcium carbonate fillers in papermaking. These diverse advantages have made almost all paper machines of printing and writing papers run under neutral and alkaline conditions. On the other hand, linerboard machines, which use recycled papers as a raw material, are running under acid conditions using a rosin sizing system. Because the recycled raw materials used by the linerboard industry contain significant amounts of alkaline papers, the linerboard industry has an interest in the possibility of using the neutral or alkaline papermaking opportunity. In this study, the compatibility of the recycled linerboards under neutral or alkaline papermaking conditions was examined by recycling them under various pH conditions. The sizing degree of the papers recycled under neutral or alkaline was significantly lower than that of acid formed papers indicating that during the neutral or alkaline recycling process the rosin sized papers lost their sizing efficiency. Recycling of acid formed linerboards under neutral or alkaline conditions increased the amount of foam, and the foam contained substantial amount of solid materials derived from the acid sizing systems. Use of cationic polyelectrolytes including PEI and poly-DADMAC improved the sizing degree of the recycled papers under neutral and alkaline conditions. PEI decreased the foam generation as well while poly-DADMAC did not show any reducing effect of the foam. These results suggest that PEI forms coordinate bonds with rosin acid and precipitate them onto the surface of recycled fibers, while the reaction products between poly-DADMAC and rosin acid ions still remain water soluble under neutral or alkaline conditions.