Cheon-Seok Park

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—In this brief, we present a 60-W power amplifier that is linearized using an RF predistorter for multicarrier wideband code-division multiple-access (WCDMA) applications. The proposed RF predistorter is fully composed of RF or analog circuits, and it has a moderate memory effect compensation capability using a delayed third-order intermodulation (IM3)(More)
The thermostability of maltogenic amylase from Thermus sp. strain IM6501 (ThMA) was improved greatly by random mutagenesis using DNA shuffling. Four rounds of DNA shuffling and subsequent recombination of the mutations produced the highly thermostable mutant enzyme ThMA-DM, which had a total of seven individual mutations. The seven amino acid substitutions(More)
α-Arbutin (α-Ab) is a powerful skin whitening agent that blocks epidermal melanin biosynthesis by inhibiting the enzymatic oxidation of tyrosine and l-3,4-dihydroxyphenylalanine (l-DOPA). α-Ab was effectively synthesized from hydroquinone (HQ) by enzymatic biotransformation using amylosucrase (ASase). The ASase gene from Deinococcus geothermalis (DGAS) was(More)
Arbutins (α- and β-arbutins) are glycosylated hydroquinones that are commercially used in the cosmetic industry. These compounds have an inhibitory function against tyrosinase, a critical enzyme for generating pigments, which leads to the prevention of melanin formation, resulting in a whitening effect on the skin. Although β-arbutin is found in various(More)
The deduced amino acid sequence from a gene of the hyperthermophilic archaeon Pyrococcus sp. ST04 (Py04_0872) contained a conserved glycoside hydrolase family 57 (GH57) motif, but showed <13 % sequence identity with other known Pyrococcus GH57 enzymes, such as 4-α-glucanotransferase (EC 2.4.1.25), amylopullulanase (EC 3.2.1.41), and branching enzyme (EC(More)
—This paper presents a new adaptive leakage canceler based on a direct leaky coupling method for an RF front-end circuit of an ultrahigh-frequency radio-frequency identication (UHF RFID) reader. For better receiver sensitivity, the leakage signal from a transmitter (TX) to a receiver (RX) should be suppressed. Compared with conventional methods, the(More)
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