• Tribology and Lubricants
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• 제36권3호
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• pp.139-146
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• 2020

Global warming has led to an increase in demand of eco-friendly vehicles, such as electric cars, for reducing greenhouse gas emissions, and especially, regulating carbon dioxide generation. In addition, electric vehicles are equipped with an electric drive-type hermetic scroll compressor and a refrigerant, which exhibit current and future trends of using environmentally friendly refrigerants, including R-1234yf. In this study, polyol ester-based refrigeration oils are prepared via condensation esterification of polyol and fatty acids. The oils can be combined with R-1234yf refrigerant for applications in air conditioning and cooling systems of electric vehicles. The structure of synthetic polyol esters is confirmed via ¹H-NMR and FT-IR spectrum analysis, and the composition of the polyol ester is analyzed via gas chromatogram analysis. Furthermore, kinematic viscosity, viscosity index, total acid value, pour point, and color are analyzed as fundamental physical properties of the synthetic polyol esters. The compatibility and chemical stability of the synthetic polyol ester combined with the R-1234yf refrigerant are obtained via high temperature and high pressure oil-resistant refrigerant tests. The changes in the oil color and catalyst activity are observed before and after the experiment to determine whether it is suitable as a refrigerator oil.

• 한국자기공명학회논문지
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• 제15권2호
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• pp.137-145
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• 2011

Hsp33, a prokaryotic molecular chaperone, exerts holdase activity in response to oxidative stress. In this study, the stepwise conformational change of Hsp33 upon oxidation was monitored by NMR. In order to overcome its high molecular weight (33 kDa as a monomer and 66 kDa as a dimer), spectra were simplified using a selectively [$^{15}N$]His-labeled protein. All of the eight histidines were observed in the TROSY spectrum of the reduced Hsp33. Among them, three peaks showed dramatic resonance shifts dependent on the stepwise oxidation, indicating a remarkable conformational change. The results suggest that unfolding of the linker domain is associated with dimerization, but not entire region of the linker domain is unfolded.

• Bulletin of the Korean Chemical Society
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• 제26권11호
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• pp.1728-1734
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• 2005

The interactions of Cu(II)-meso-Tetrakis(n-N-methylpyridiniumyl)porphyrin (n = 2,3,4), respectively referred to as o-, m- and p-CuTMPyP, and DNA, poly$[d(A-T)_2]$ and poly$[d(G-C)_2]$ were investigated by circular and linear dichroism (CD and LD). In the o-CuTMPyP case, in which the rotation of the pyridinium ring is prevented, the shape of the CD spectrum when associated to DNA and poly$[d(A-T)_2]$ resembles and is characterized by a positive band at a low drug to DNA concentration ratio (R ratio) and is bisignate at a high R ratio. The former CD spectrum shape has been attributed to porphyrin that is bound monomerically outside of DNA while the latter can be attributed to those that are stacked. When o-CuTMPyP is bound to poly$[d(G-C)_2]$, the excitonic CD appeared at a relatively high R ratio. In contrast, a characteristic negative CD band in the Soret region was apparent for both m- and p-CuTMPyP when bound to DNA and poly$[d(G-C)_2]$ at the low R ratios, indicating that the porphyrin molecule intercalates. However, the DNA is bent near the intercalation site and the plane of the porphyrin molecule tilts relative to the DNA helix axis, as judged by the magnitude of the reduced LD. Various stacking patterns were identified by the shape of the CD spectrum for m- and p-CuTMPyP when bound to poly$[d(A-T)_2]$. Three species for the former complex and two for the latter complex were found which may reflect the extent of the stacking.

• 대한화장품학회지
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• 제40권4호
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• pp.359-364
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• 2014

본 연구에서는 합성보존제로 흔히 쓰이는 메칠파라벤과 방부효능을 가지는 천연추출성분인 p-아니식애씨드를 HPLC를 통해 분리분석 하는 방법을 개발하였다. 메칠파라벤과 p-아니식애씨드는 같은 분자량(152.15 g/mol)과 비슷한 구조, 같은 최대흡수파장(250 nm)을 보이기 때문에 HPLC로 분석 시 동일한 RT값(13.3 min)을 갖는다. 본 연구 저자들은 아세틸화 반응을 통해 메칠파라벤을 선택적으로 유도체화 한 후 C18 컬럼을 통해 분석했을 때 두 물질이 분리됨을 확인하였다. 아세틸화반응을 거치면서 메칠파라벤의 피크유지시간이 13.3 min에서 23.9 min으로 이동하였으며, 평균값은 $23.9{\pm}0.1min$, 피크면적 값은 $5042882{\pm}4778$로 일정하게 나타났다. 또한 직선성의 평가에서 결정계수값은 0.9999658로 1에 가까운 값을 보였다. 시료의 검출한계는 $1.47{\mu}g/mL$이었고 정량한계는 $4.44{\mu}g/mL$이었다. 결론적으로 본 연구를 통해 개발된 분석법은 화장품 분야에서 유사한 구조를 가진 보존제 분석에 유용하게 사용될 수 있을 것으로 기대된다.

• Archives of Pharmacal Research
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• 제10권1호
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• pp.1-8
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• 1987

One of the problems of derivatie spectrophotometry, the decrease of signal-to-noise ratio by derivative operations, was solved by three concepts of digital filtering, ensemble averaging, least squares polynomial smoothing and Fourier smoothing. The suthors made several compouter programs written in APPLE SOFT BASIC language for the actual applications of the concepts of these digital filters on UV spectrophotometer system. As a result, ensemble averaging could not be used as a routine operation for the spectrophotometer used. The maximum S/N ratio enhancement factors achieved by least squares polynomial smoothing were 6.17 and 7.47 for the spectra of Gaussian and Lorentzian distribution models, and by Fourier smoothing 16.42 and 11.78 for the spectra of two models, respectively.

• 약학회지
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• 제57권5호
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• pp.316-322
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• 2013

The new pyridazinone analogs were synthesized for development of candidates to retain anticancer activity. Various 6-substituted pyridazin-3(2H)-ones were prepared from the pyridazinyl chloride 3a~d via endothermic nucleophilic substitution with hydroxide ion as nucleophile for 2~48 h. Pyridazinyl chloride 3a~d could be converted to hydroxypyridazines (or pyridazin-3(2H)ones) using 1~5 equivalents of water (or 1 equivalent of sodium hydroxide) at reflux in DMF. The tautomerism of lactim form to lactam form was also accomplished in pyridazine derivatives. Formation of pyridazinones 10 was undertaken with stirring using sodium hydroxide at reflux in DMF for 2 h. Synthetic compounds were identified using NMR spectrum.

• 한국멀티미디어학회논문지
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• 제10권12호
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• pp.1551-1558
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• 2007

The standard of evaluating function of speech coder for mobile telecommunication can be shown in channel capacity, noise immunity, encryption, complexity and encoding delay largely. This study is an algorithm to reduce complexity applying to CDMA(Code Division Multiple Access) mobile telecommunication system, which has a benefit of keeping the existing advantage of telecommunication quality and low transmission rate. This paper has an objective to reduce the computing complexity by controlling the frequency band nonuniform during the changing process of LSP(Line Spectrum Pairs) parameters from LPC(Line Predictive Coding) coefficients used for EVRC(Enhanced Variable-Rate Coder, IS-127) speech coders. Its experimental result showed that when comparing the speech coder applied by the proposed algorithm with the existing EVRC speech coder, it's decreased by 45% at average. Also, the values of LSP parameters, Synthetic speech signal and Spectrogram test result were obtained same as the existing method.

• 환경위생공학
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• 제20권4호통권58호
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• pp.38-44
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• 2005

Cryptand resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene divinylbenzene (DVB) copolymer with crosslink of $1\%,\;2\%,\;5\%\;and\;10\%$ by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium$(UO_2^{2+})$ ion were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium$(UO_2^{2+})$ > zinc$(Zn^{2+})$ > samarium$(Sm^{3+})$ ion. The adsorption was in order of $1\%>2\%>5\%>10\%$ crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• 천문학회보
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• 제35권2호
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• pp.78.1-78.1
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• 2010

We obtained the spectra of 93 Planet host stars and 73 normal field stars in F, G, K type using BOES at BOAO. We measured the equivalent width of Fe and 13 elements lines using the automatic EW measurement program, TAME(Tools for Automatic Measurement of Equivalent-widths) and estimated the abundances by synth and abfind driver of MOOG code. Since the absence of planets in the normal field stars cannot be "completely" proved, this work focused on the chemical abundances and planet properties of planet host stars, which have the massive planets close to the parent star relatively. We carried out an investigation for the difference of abundances between stars with "Hot Jupiter" and normal field stars with no known planets. We examined the chemical composition of 12 elements, such as Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni by EW measurements, and the S abundances were estimated using synthetic spectrum.

• 천문학회보
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• 제35권1호
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• pp.89.2-89.2
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• 2010

우리는 목성의 emission과 absorption 스펙트럼에 영향을 미치는 인자를 알아보고 목성의 대기구조를 연구하기 위하여 2006년 4월 18일부터 8월22일 사이 중 7일간 United Kingdom Infrared Telescope(UKIRT)의 고분산분광기 CGS4(R=37,000)를 이용하여 관측한 목성의 $2.86-3.53{\mu}m$ 분광관측 자료를 분석하였다. 관측자료의 분석에는 $CH_4,\;CH_3D,\;NH_3,\;C_2H_2,\;C_2H_6,\;PH_3$, HCN의 분광선 뿐만 아니라 구름과 Haze의 영향도 포함하는 대기모델을 사용하였다. 대부분의 관측된 분광선은 모델링을 통하여 얻은 synthetic spectrum과 일치하였으나 3.00 에서 $3.10{\mu}m$사이에서 일치하지 않는 다섯 개의 미확인 분광선을 발견하였다. 이들은 각각 $3.003{\mu}m$ 근처와 3.0505, 3.0735, $3.0865{\mu}m$ 그리고 $3.0935{\mu}m$에서 나타나며, 미확인 분광선들이 Seo et al.(2007)이 언급한 태양의 적외선 흡수선에 의해서 나타나는 분광선이 아님을 보였다. 우리는 이 미확인 분광선들을 설명할 수 있는 가능한 분자들을 제시 하고자 한다.