• Bulletin of the Korean Chemical Society
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• 제17권8호
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• pp.725-729
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• 1996

Reaction of carbonyl compounds with B-alkoxydiisopinocampheylborane (Ipc2BOR, R=H, Et, i-Pr, t-Bu) was investigated in detail in order to establish their usefulness as selective reducing agents. The reagents were extremely mild and reduced only aldehydes effectively under mild conditions. The reagents also reduced α,β-unsaturated aldehydes to the corresponding allylic alcohols without any detectable 1,4-reduction. Furthermore, aldehydes can be reduced in the presence of epoxides and acid chlorides. Consequently, the selective reduction of aldehyde groups in the presence of keto and all other functional groups has been realized with these reagents.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.325-327
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• 2004

• Bulletin of the Korean Chemical Society
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• 제26권7호
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• pp.1125-1128
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• 2005

• Tribology and Lubricants
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• 제10권3호
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• pp.29-38
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• 1994

The friction and wear of mild steel at dry sliding surfaces under different vacuum conditions have been investigated to understand the wear mechanisms. For the test, a ball-ondisk typed wear-rig has been built and implemented, allowing control of sliding speed, load and vacuum. Results show that, at a high sliding velocity, friction of low carbon steel (SS41) under a high vacuum is much higher than that of ambient condition and wear is much severer. It is due to lack of effective oxidation film formation on which steel surfaces could protect themselves against the severe wear. It has been shown, however, that there is a critical regime with contact conditions (at a low sliding velocity, a low load, and under a medium vacuum) at which effective, protective films of low carbon steel have been built on the surfaces in a friction process with a self-regulating way, resulting in both very low coefficients of friction (about 0.3) and mild wear. In order to investigate the protective films on steel surfaces, the worn surfaces and the wear debris have been experimentally analyzed with SEM, AES/SAM and XRD. A theoretical analysis of frictional heating at sliding surfaces, and an experimental analysis of the influence of oxidation wear under various vacuum conditions are described. The important variables on which self-formations of protective films at dry sliding surfaces depend, and the wear mechanisms are also investigated.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.153-154
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• 2002

Wear map of silver coatings on AISI 52100 has been constructed to delineate the wear transition behavior with the change in operating conditions in various environments. Three main regimes were clearly identified: (i) elastic/plastic deformation of silver coating without failure. (ii) mild wear regime after initial failure of silver coating and (iii) severe wear regime. In the mild wear regime, the contact surfaces were covered with transfer layers of agglomerated wear particles. The transfer layer acted as a protective layer and resulted in low friction even after the initial failure of the coated films, whose characteristics were strongly dependent on both the operating and environmental conditions. Also, the existence of the critical sliding speed, above which no transfer layer was able to form, was discussed in the work.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.459-463
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• 2012

N-hydroxyphthalimide (NHPI) and copper chloride ($CuCl_2$) were first utilized for aerobic oxidation of ${\alpha}$-isophorone (${\alpha}$-IP) to ketoisophorone (KIP) and the effects of co-catalysts, temperature, reaction time, solvent, amount of $CuCl_2$ and pressure of oxygen were investigated extensively. NHPI/$CuCl_2$ turned out to be highly efficient to this oxidation with up to 91.3% conversion and 81.0% selectivity under mild conditions. And various hydrocarbons including benzylic compounds, cycloalkene and its derivatives were also oxidized smoothly under optimized conditions. Moreover, the possible reaction mechanism was proposed and verified by FT-IR spectra.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.715-720
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• 2014

A Cu(II) complex with an three nitrogens and one sulfur coordination environment was synthesized and characterized. Its redox potential was observed at 0.483 V vs. NHE, very similar to that of a Cu-containing fungal enzyme, galactose oxidase, which catalyzes the oxidation of alcohols to corresponding aldehydes with the concomitant reduction of molecular oxygen to water. The Cu(II) complex selectively oxidizes the benzylic alcohols using TEMPO/$O_2$ under mild reaction conditions to corresponding aldehydes without forming any over-oxidation product. Moreover, the catalyst can be recovered and reused multiple times for further oxidation reactions, thus minimizing the waste generation.

• 대한조선학회지
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• 제16권3호
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• pp.25-33
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• 1979

The relation between the welding conditions and welding distortions were studied with the weld parameters, current, welding speed and plate thickness, and the form of the distortions were derived theoretically. To derive these formulas, the temperature distribution on the plane normal to the direction of the weld line was assumed to be parabolic. Both the theoretical studies for the transverse shrinkage and angular distoction were compared with the experiments. The experiments were performed on the fundamental cases of a bead welds on rectangular mild steel plates. It was found that the distoction formulas were in good agreement with the results of the experiments. The formulas for the calculation of the distortion were established for the case of bead on plate weld using rectangular mild steel plate and the KS E4313, $4mm\phi$ welding rod.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2367-2374
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• 2013

Lysine (Lys) immobilized on zeolite 4A was prepared by a simple adsorption method. The physical and chemical properties of Lys/zeolite 4A were investigated by X-ray diffraction (XRD), FT-IR, Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis. The obtained organic-inorganic composite was effectively employed as a heterogeneous basic catalyst for synthesis of ${\alpha},{\beta}$-unsaturated carbonyl compounds. No by-product formation, high yields, short reaction times, mild reaction conditions, operational simplicity with reusability of the catalyst are the salient features of the present catalyst.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.380-386
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• 2018

A sustainable method was developed for the upgrade of biomass derived vanillin (a typical model compound of lignin) into the potential liquid biofuels over a layered double hydroxide supported Pd catalyst (abbreviated as CoAl-LDH/Pd). The CoAl-LDH/Pd catalyst showed high catalytic activity towards the hydrodeoxygenation of vanillin into 2-methoxy-4-methylphenol (MMP) under mild conditions in aqueous media. High MMP yield up to 86% was produced at $120^{\circ}C$ after 4 h. Kinetic studies revealed that the rate-determining step for the hydrodeoxygenation of vanillin was the hydrogenolysis of vanillyl alcohol. More importantly, the CoAl-LDH/Pd catalyst was highly stable without the loss of activity.