• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2519-2522
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• 2014

Recently, the observation of the electrocatalytic behavior of individual nanoparticles (NPs) by electrochemical amplification method has been reported. For example, the Iridium oxide ($IrO_x$) NP collision on the Pt UME was observed via electrocatalytic water oxidation. However, the bare Pt UME had poor reproducibility for the observation of NP collision signal and required an inconvenient surface pre-treatment for the usage. In this manuscript, we has been investigated other metal electrode such as Cu UME for the reproducible data analysis and convenient use. The $IrO_x$ NP collision was successively observed on the bare Cu UME and the reproducibility in collision frequency was improved comparing with previous case using the $NaBH_4$ pre-treated Pt UME. Also, the adhesion coefficient between NP and the Cu UME was studied for better understanding of the single NP collision system.

• 분석과학
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• 제14권2호
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• pp.95-102
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• 2001

쇠고기 돼지고기 속에 포함된 nonylphenol, octylphenol, bis(2-ethyltexyl) phthalate의 동시 정량방법을 연구하였다. 이 방법에서는 밀폐된 배양시험관에서 이염화메탄을 이용하여 추출하고 용매를 이소헥산으로 바꾸고 aminopropyl 칼럼(2g)을 이용하여 분리한 후 GC/MS-SIM 방법으로 분석하였다. 다중점보정을 위한 nonylphenol(NP), octylphenol(OP), bis(2-ethylhexyl) phthalate(BEHP)의 회수율에서 NP, OP는 $0.125-12.5{\mu}g/g$, BEHP는 $0.0125-12.5{\mu}g/g$ 범위에서 좋은 회수율을 보였다. 확립된 방법을 전주시와 전주시 근교 마트와 정육점에서 구입한 16점의 쇠고기 돼지고기 시료에 적용하였다. Nonylphenol은 4점의 시료에서 검출되었으며 bis(2-ethlhexyl) phthalate는 전 시료에서 검출되었고, 그 농도범위는 $0.06-0.24{\mu}g/g$과 $0.36-2.35{\mu}g/g$ 이었다. Octylphenol은 어떠한 시료에서도 검출되지 않았다. 이 방법은 매우 적은량의 생체 시료에도 쉽게 적용이 가능하였다.

• Journal of Pharmaceutical Investigation
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• 제32권2호
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• pp.95-101
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• 2002

Matrix tablets of nifedipine (NP) were prepared with Eudragit, diluent (lactose or Ca. phosphate) and Mg. stearate employing two different preparation methods (wet granulation and direct compression) to develop its sustained-release dosage forms. The effects of various formulation factors on the dissolution rate of the drug were investigated. Dissolution test was studied in pH 6.8 phosphate buffer containing 1% sodium lauryl sulfate using the paddle method. Formulation factors were the type and content of Eudragit, the type of diluent and the tablet preparation method. The optimum formula of NP matrix tablet, which resulted in a similar dissolution profile to that from Adalat Oros used as a reference, was 30 mg NP, 10% Eudragit RS, 2% Mg. stearate and an adequate quantity of lactose to yield 500 mg weight using the wet granulation method.

• Journal of Electrochemical Science and Technology
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• 제12권3호
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• pp.323-329
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• 2021

This work presents a contrasting behavior of formic acid oxidation (FAO) on the Pt and Bi deposits on different Pt substrates. Using irreversible adsorption method, Bi and Pt were sequentially deposited on Pt electrodes of nanoparticle (Pt NP) and disk (Pt disk). The deposited layers of Bi and Pt on the Pt substrates were characterized with X-ray photoelectron spectroscopy, transmission microscopy and scanning tunneling microscopy. The electrochemical behaviors and FAO enhancements of Pt NP and Pt disk with deposited Bi only (i.e., Bi/Pt NP and Bi/Pt disk), were similar to each other. However, additional deposition of Pt on Bi/Pt NP and Bi/Pt disk (i.e., Pt/Bi/Pt NP and Pt/Bi/Pt disk) changed the electrochemical behavior and FAO activity in different ways depending on the shapes of the Pt substrates. With Pt/Bi/Pt NP, the hydrogen adsorption was suppressed and the surface oxidation of Pt was enhanced; while with Pt/Bi/Pt disk, the opposite behavior was observed. This difference was interpreted as a stronger interaction between the deposited Bi and Pt on Pt NP than that on Pt disk. The FAO performance on Pt/Bi/Pt NP is much better than that on Pt/Bi/Pt disk, most likely due to the difference in the interaction between the deposited Pt and Bi depending on the shapes of Pt substrates. In designing FAO electrochemical catalysts using Pt and Bi, the shape of a Pt substrate was concluded to be critically considered.

• Nuclear Engineering and Technology
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• 제39권5호
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• pp.673-682
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• 2007

The contents of transuranic elements in high-burnup spent fuel samples were determined. The activity amounts of $^{238}Pu,\;^{239}Pu,\;^{240}Pu,\;^{241}Am,\;^{244}Cm\;and\;^{242}Cm$ were measured by alpha spectrometry using $^{242}Pu\;and\;^{243}Am$ as tracers, respectively. A spike addition method for $^{237}Np$ was established by an alpha and gamma spectrometry using $^{239}Np$ as a spike after the optimum conditions for the measurements of $^{237}Np\;and\;^{239}Np$, respectively, were obtained. A separation system using anion exchange chromatography and diethylhexylphosphoric acid extraction chromatography was applied for the separation of these elements. This method was applied to high-burnup spent nuclear fuel samples $(40{\sim}60GWD/MTU)$. The contents of the transuranic elements were compared with those by ORIGEN-2 code. Measurements and the calculations of the contents of the plutonium isotopes $^{238}Pu,\;^{239}Pu\;and\;^{240}Pu$ agreed to within 10% on average. The contents of $^{237}Np$ agreed to within approximately 5% except for one instance of a calculation, while those of $^{241}Am,\;^{244}Cm\;and\;^{242}Cm$ showed higher values by approximately 19%, 35% and 14% on average, respectively, compared to the calculations according to the burnup.

• 한국환경과학회지
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• 제1권1호
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• pp.69-76
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• 1992

The effects of $Ca_{2+}$ ion on the formation of micelle colloid of nonionic surfactants, nonylphenol-(ethylene oxide)n [NP-(EO)n: n= 11, 40, 100) were investigated by the iodine solubilization method. The characteristics of spectra depended on the concentration of $Ca_{2+}$ ion and the number of EO unit. Above CMC(critical micelle concentration), the intensity of the CT (charge transfer) band by the addition of $Ca_{2+}$ ion for the NP-(EO)11 and NP-(EO)40 increased and when decreased and for the NP-(EO)In continuously increased. The increase in the intensity of CT band were attributed to the compactness of micelle in the presence of $Ca_{2+}$ ion. These phenomena may be explained by the fact that the linear ethylene oxide (EO) chain, relatively free to assume various configuration in aqueous solution, could form a pseudo-crown ether structures capable of forming complexes with $Ca_{2+}$ ion.

• 한국정보통신학회논문지
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• 제19권12호
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• pp.2865-2870
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• 2015

최근 양자 컴퓨터가 개발되는 등 컴퓨팅 하드웨어의 성능이 발전하면서 단시간 내에 처리할 수 있는 정보의 양이 기하급수적으로 증가하고 있다. Koblitz-Fellows가 제안한 암호시스템은 생성할 수 있는 불변 다항식(invariant polynomial)의 개수가 충분하지 않아 특정 3-정규 그래프에서 완전지배집합(Perfect Dominating Set, PDS)을 찾는 문제가 NP-complete임을 보장할 수 없는 문제점이 발생한다. 본 논문에서는 이러한 취약점을 보완하기 위해 Koblitz-Fellows가 제안한 3-정규 그래프 상에서 완전지배집합을 이용하여 불변 다항식의 개수를 기하급수적으로 증가시킴으로 계산의 복잡도를 더욱 난해하게 하여 암호시스템의 취약점을 개선하도록 제안한다.

• 융합보안논문지
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• 제14권7호
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• pp.59-64
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• 2014

이 논문에서는 고정된 개수를 가진 bin들을 이용하여 실행 복잡도가 $p(n){\cdot}2^{O(\sqrt{n})}$인 알고리즘을 제시한다, 여기서 x는 (5)n개의 객체들에 대한 리스트의 길이에 대한 총 비트 수를 나타낸다. 이러한 방법은 수치적 크기나 비중의 합의 리스트를 이용하는 여러 가지 최적화 알고리즘이나 결정 문제등에 적용할 수 있다. 이 논문에서 제시한 알고리즘은 의사-다항식(pseudo-polynomial) 시간을 갖는 NP-Complete의 많은 문제들을 결정적인 서브-지수 시간에 해결할 수 있은 가능성을 제시한다. 여기서 제시한 알고리즘을 이용하여 생명공학의 유전자 분석에 적용하려고 한다.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 추계 학술발표회 논문집
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• pp.143-148
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• 1999

A distributed real-time system that is being wed now is usually divided into three level : higher level, middle level, and lower level. The higher level network is usually called an information network, the middle level is called a control network, and the lower level is called a field network or a divice network. This dissertation suggests and implements a middle level network which is called PICNET-NP (Plant Implementation and Control Network for Nuclear Power Plant). PICNET-NP is based partly on IEEE 802.4 token-passing bus access method and partly on IEEE 802.3 physical layer. For this purpose a new interface, a physical layer service translator, is introduced. A control network using this method is implemented and applied to a distributed real-time system.

• 분석과학
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• 제36권5호
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• pp.224-235
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• 2023

An analytical method was developed for the determination of phenol (P) and the seven substituted phenols in water samples and fish tissue samples collected from three streams located in eastern Gangwon State in spring and summer. The phenols were extracted and then derivatized to phenyl acetates using acetic anhydride. The derivatives were subsequently identified and quantified using gas chromatography coupled with mass spectrometry. P and 4-nitrophenol (4NP) were found at relatively high levels in water, ranging from below the method detection limit (MDL) to 3.32 ㎍/L and from < MDL to 4.91 ㎍/L, respectively. P and 4NP were also the dominant compounds in the fish tissue, ranging from < MDL to 407 ㎍/kg and from < MDL to 870 ㎍/kg, respectively. Phenol concentrations were significantly higher in spring than in summer. The ecological risk quotient calculated for P was higher than 4NP but not high enough to pose any risk of adverse effects to fish health.