• Bulletin of the Korean Chemical Society
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• 제25권4호
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• pp.517-524
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• 2004

Two simple and sensitive spectrophotometric methods were developed for the determination of carbocisteine, penicillamine, ethionamide and thioctic acid in bulk and in their pharmaceutical preparations using alkaline potassium permanganate as an oxidizing agent. The first one involves determination of ethionamide and thioctic acid by spectrophotometric investigation of the oxidation reaction of the two drugs. The second method involves determination of carbocisteine and penicillamine by kinetic studies of the oxidation reaction of these two drugs at room temperature for a fixed time of 20 minutes. The absorbance of the colored manganate ions was measured at 610 nm in both methods. 1-10 ${\mu}$g/mL of ethionamide and thioctic acid could be etermined by the spectrophotometric method with detection limits of 0.11 and 0.089 ${\mu}$g/mL for the two drugs respectively. 2-10 ${\mu}$g/mL of carbocisteine and penicillamine could be determined by the kinetic method with detection limits of 0.14 and 0.21 ${\mu}$g/mL respectively. The two methods were successfully applied for the determination of these drugs in their dosage forms.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1907-1914
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• 2010

A novel catalytic kinetic method is proposed for the determination of Se(IV), Se(VI) and total inorganic selenium in water based on the catalytic effect of Se(IV) on the reduction of bromate by p-nitrophenylhydrazine at pH 3.0. The generated bromine, $Br_2$ or $Cl_2$ plus $Br_2$ in 0.1 M NaCl (or NaBr) environment efficiently decolorized Calmagite and the reaction was monitored spectrophotometrically at 523 nm as a function of time. In this indicator reaction, bromide acted as an activator for the catalysis of selenium (IV) and a reducing agent for selenium (VI) at pH 3.0, which allowed the determination of total selenium. The fixed time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the calibration graph are linear in the range 1 - 35 ${\mu}gL^{-1}$ of Se(IV) for the fixed time method at $25^{\circ}C$. The detection limit based on statistical $3S_{blank}$/m-criterion was 0.215 ${\mu}gL^{-1}$ for the fixed time method (7 min). All of the variables that affect the sensitivity at 523 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se (IV) determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The RSDs for ten replicate measurements of 5, 15 and 25 ${\mu}gL^{-1}$ of Se(IV) and Se(VI) was changed between 2.1 - 4.85%. Analyses of a certified standard reference material (NIST SRM 1643e) for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. Se(IV), Se(VI) and total inorganic selenium in environmental water samples have been successfully determined by this method after selective reduction of Se(VI) to Se(IV).

• Bulletin of the Korean Chemical Society
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• 제27권6호
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• pp.863-868
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• 2006

The partial least squares (PLS-1) calibration model based on spectrophotometric measurement, for the simultaneous determination of sulfite and sulfide is described. This method is based on the difference between the rate of the reaction of sulfide and sulfite with Malachite Green in pH 7.0 buffer solution and at 25 ${^{\circ}C}$. The absorption kinetic profiles of the solutions were monitored by measuring the decrease in the absorbance of Malachite Green at 617 nm in the time range 10-180 s after initiation of the reactions with 2 s intervals. The experimental calibration matrix for partial least squares (PLS-1) calibration was designed with 24 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range 0.030-1.5 and 0.030-1.2 $\mu$g m$L ^{-1}$ for sulfite and sulfide, respectively. The proposed method was successfully applied to simultaneous determination of sulfite and sulfide in water samples and whole human blood.

• Bulletin of the Korean Chemical Society
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• 제24권9호
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• pp.1261-1264
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• 2003

A method for the determination of trace amount of sulfide based on the addition reaction of sulfide with methyl green at pH 7.5 and $25{\circ}C$ is described. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of the dyestuff at 637 nm by the initial rate and fixed time method. The calibration graph is linear in the range 30-1200 ppb. The theoretical limit of detection was 0.014 ppm. Seven replicate analysis of a sample solution containing 0.70 ppm sulfide gave a relative standard deviation of 1.5%. The interfering effects of various ions on sulfide determination have been reported and procedures for removal of interference have been described. The proposed method was applied successfully to the determination of sulfide in tap and wastewater samples.

• Archives of Pharmacal Research
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• 제27권9호
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• pp.968-972
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• 2004

A 1, 2-diglyceride-based multi-step colorimetric assay to measure the pancreatic lipase activ-ity was applied for the determination of the kinetic profiles of the lipase inhibition with a slight modification and the validity verification. With this assay method, our study revealed that platy-codin D, one of major constituents of Platycodi Radix, inhibits the pancreatic lipase activity in a competitive type, with the value of $K_1$ being 0.18${\pm}$0.02 mM. In addition, PO has affected the val-ues of $K_{m}$, app/ and $K_{cat}$/$K_{m}$ in a dose-dependent manner. The results shed a meaningful light on how PO mediates lipid metabolism in the intestinal tracts. On the other hand, since the revised assay is sensitive, rapid, and does not affect the accuracy to the kinetic properties, it is applica-ble not only to evaluation of the kinetic properties of the pancreatic lipase, but also to high-throughput screening of pancreatic lipase activity.

• Archives of Pharmacal Research
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• 제27권10호
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• pp.1048-1052
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• 2004

A 1, 2-diglyceride-based multi-step colorimetric assay to measure the pancreatic lipase activity was applied for the determination of the kinetic profiles of the lipase inhibition with a slight modification and the validity verification. With this assay method, our study revealed that platycodin D, one of major constituents of Platycodi Radix, inhibits the pancreatic lipase activity in a competitive type, with the value of $K_I$ being 0.18${\pm}$0.02 mM. In addition, PD has affected the values of $K_{m,app}\;and\;K_{cat}/K_m$ in a dose- dependent manner. The results shed a meaningful light on how PD mediates lipid metabolism in the intestinal tracts. On the other hand, since the revised assay is sensitive, rapid, and does not affect the accuracy to the kinetic properties, it is applicable not only to evaluation of the kinetic properties of the pancreatic lipase, but also to highthroughput screening of pancreatic lipase activity.

• 한국전자통신학회논문지
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• 제14권4호
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• pp.743-754
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• 2019

지표면 침식 잠재력은 비가 내린 영향으로 토양에 전달 된 운동 에너지로 평가할 수 있다. 충격 신호를 분석할 수 있는 디즈드로미터로 우적 에너지율 관계식을 산출하였다. 대륙 강수의 97%와 해양 강수의 95%가 강우량과 강우율의 관계로 이루어진 이 지수 방정식으로 설명되었다. 이 관계식의 지수는 강우 유형에 의존하지 않지만 계수는 강우 사건에 따라 조정될 수 있는 변동을 나타냈다. 이 관계식은 결정 계수, 평균 절대 오차 및 신뢰 오차에 의해 검증되었다. 특정 유형의 토양과 관련된 강수의 운동 에너지는 강우로 인한 침식의 가능성을 결정할 수 있다.

• 한국진공학회지
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• 제9권4호
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• pp.419-427
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• 2000

본 연구는 원자의 주변 환경에 따른 각각의 확산 속도를 구할 수 있는 기구를 제시하였다. STM 또는 HRLEED 등의 실험과 kinetic Monte Carlo(KMC) 시뮬레이션 계산과의 비교를 통하여 테라스 위 흡착 원자의 확산장벽, step 끝 부착 원자의 탈착 확산 장벽, 잘 알려진 Schwoebel 장벽을 포함한 각각의 확산 장벽을 구할 수 있었다. 팔-넓이, 군집 밀도, 거칠기 등이 시뮬레이션 계산과 실험 결과를 비교하는 데에 가장 적절한 원자단위의 구조변수들임을 확인하였고, 특히 아직 잘 사용되지 않은 구조 계수인 가지폭이 확산 장벽을 구별하여 구하는 데에 중요한 역할을 하는 것을 확인하였다.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1993년도 추계학술발표회 초록집
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• pp.31-36
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• 1993

Three different methods were employed to measure the degree of aerial oxidation in coal and the resulting oxidation/weathering indices were applied to obtain kinetic parameters of aerial oxidation processes, The index (i.e., slurry pH, Free Swelling Index, weight gain) values were subjected to kinetic analysis based on power-law Arrhenius type reaction model. The results show that activation energy of the aerial oxidation in 20-29$0^{\circ}C$ is in the range of 12-16 ㎉/㏖ and the agreement among three techniques is remarkable. The first order kinetic model is suitable in describing low temperature aerial oxidation process, except in the FSI case where the zero order expression is the best one.

• Bulletin of the Korean Chemical Society
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• 제15권3호
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• pp.241-245
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• 1994

A method has been developed to estimate the kinetic energy release originating from the reverse critical energy in unimolecular ion dissociation. Contribution from the excess energy was estimated by RRKM theory, the statistical adiabatic model and the modified phase space calculation. This was subtracted from the experimental kinetic energy release distribution (KERD) via deconvolution. The present method has been applied to the KERDs in $H_2$, loss from $C_6H_6^+$ and HF loss from ${CH_2CF_2}^+$. In the present formalism, not only the energy in the reaction coordinate but also the energy in some transitional vibrational degrees of freedom at the transition state is thought to contribute to the experimental kinetic energy release. Details of the methods for treating the transitional modes are found not to be critical to the final outcome. For a reaction with small excess energy and large reverse critical energy. KERD is shown to be mainly governed by the reverse critical energy.