Simultaneous Determination of Traces of Platinum and Rhodium by Differential Pulse Polarograpy

채명준,이철,홍태기,권영순,홍미정,Czae, Myoung-Zoon,Lee, Chul,Hong, Tae-Kee,Kwon, Young-Soon,Hong, Mi-Jeong Korean Chemical Society 1995 대한화학회지 Vol.39 No.1

백금과 로듐 모두 미량으로 존재할 때 펄스 차이 폴라로그래피법으로 동시 정량할 수 있는 용액조건을 확립하였다. 포름알데히드 0.004%(w/v)-히드라진 0.0012$(w/v)-황산 0.75 M의 조건에서 가장 예민한 수소 촉매파를 얻을 수 있었다. 이 조건에서 단일 금속의 검출 한계는 $7.3{\times}10^{-11}\; M\; Pt$ 그리고 $3.2{\times}10^{-11}\; M\; Rh$이었다. 이 농도범위에서 로듐(10배 이상)과 이리듐(100배 이상)만이 백금을 방해하였다. 로듐은 어떠한 여타 백금족 원소(1000배 이상의 백금, 500배의 이리듐 존재하에서도)의 방해도 받지 않았다. Simultaneous measurements of trace platinum and rhodium, based on catalytic reduction of protons by the adsorbed Pt-formazone and Rh-formaldehyde complexes formed in formaldehyde-hydrazine-sulfuric acid medium, were demonstrated. The conditions for the measurements of Pt and Rh both present at trace levels (>10-10 M) were 0.004% (w/v) formaldehyde-0.0012% (w/v) hydrazine-0.75 M sulfuric acid. In this medium method detection limits are 7.3${\times}$10-11 M Pt and 3.2${\times}$10-11 M Rh. And dynamic ranges are 5${\times}$10-10~6${\times}$10-8 M and 1${\times}$10-10∼2${\times}$10-8 M for platinum and rhodium respectively. In the linear dynamic ranges, Rh and Ir interfere platinum in the presence of only 10 and 100 times that of Pt respectively. There are no interferences from other platinum group metal ions for rhodium even in the presence of a 500-fold excess of Ir(IV), a hundredfold excess of platinum.

바닷물 중의 화학적 산소요구량: 가열분해시간의 영향과 남해안 및 서해안 일부에서의 자료

채명준 漢陽大學校 環境科學硏究所 1985 環境科學論文集 Vol.6 No.-

바닷물처럼 염소이온의 함유량이 많은 시료중의 COD측정 절차에서 실험자마다 다르게 잡고 있는 가열분해시간이 결과에 미치는 영향을 조사하여 가열시간 단축가능성 여부를 검토하였다. 알카리성 과망간산칼륨법에서 공정시험법대로 60분이 최고의 COD결과를 주었고 40분만해도 86%로 90분 때에도 오히려 85%로 감소함을 보아 정확히 60분 가열해야함을 알았다. 화력발전소가 위치한 남해안 삼천포, 및 서해안 보령연안에서 38개의 시료를 채취 COD를 측정한 결과 모두 1.0∼3.9mgO₂/L로 나타나 해양상태가 양호함을 알았다. In the manipulative procedure for the determination of chemical oxygen demand(COD) in seawater by alkaline permanganate reflux method, effects of the reflux time on the result are evaluated. Reflux for 60 minutes, it was found to give maximum COD, for 40 minutes only 86%, for 90 minutes only 85% of the maximum values. The experimental results of surface seawater samples,38 from southern and western coasts where power plants are located, are reported. COD range was 1.0∼3.9mgO₂/L.

남해안 일대 海水의 플루오르에 관한 환경 자료

蔡命俊 漢陽大學校 環境科學硏究所 1982 環境科學論文集 Vol.3 No.-

환경오염에 의한 분쟁의 판정, 조정을 위한 참고자료의 하나로서 남해안 일대의 해수 중 ?? 농도의 자연 분포상황을 조사하였다. 미량성분 F를 정량하는 흡광광도법들도 아울러 검토하였다. 공해공정시험법의 플루오르 정량 방법은 해수의 경우에는 적용할 수가 없었다. 란탄-알리자린 콤플렉손법은 Ce에 의한 방법보다 언제나 높은 결과를 주었다(약 +2.5%). F의 농도나 염소도 모두 해역에 따라 두드러진 현상은 없으며 평균적으로 ??는 1.11~1.17ppm, 염소도는 18.4~19.0‰, 이비는 6.04~6.33 ×??으로 나타났다. 그 중 제주도의 서귀포가 F의 함량과 F/CL 비가 각각 1.11ppm 및 6.04 ×?? 으로 가장 적게 나타났다. Natural flouride contents of coastal seawater around some area in southern coast were determined for a reference environmental data. Comparison of current spectrophothometric methods for fluoride showed that La-Alizarin Complexone method gives somewhat (about 2.5%) higher result than Ce-method. Results shows 1.11~1.17 ppm of ?? and 18.40~19.01‰ of chlorinity, giving 1.11ppm and 6.04 ×?? for the smallest values of ?? content and F/CI ratio, respectively, at Jeju island.

Tungsten-Catalyzed Reduction Waves

채명준 成均館大學校 1969 論文集 Vol.14 No.-

Anomalous polarographic currents of the tungsten (Ⅵ) in weak acidic solution (pH 1.5-3.9) in the presence of hydroxylamine are attributed to the catalytic action of the tungsten on the hydroxylaminie reduction. Thus the tungsten catalyzes the polarographic reduction of hydroxylamine, giving rise to two catalytic waves. The waves are characterized by peaks, the peak potentials of the waves correspond to that of the normal reduction of isopolyacid, pseudo-metatungstate (_6Ψ) and dodecatungstate (meta, _12M), would act as catalyzers. The peak currents (corrected for resicual current) are strictly proportional to the tungsten concentration in the range between 10^-5 (or less) and 2×10 exp (-4) Mregardless of the acidity considered, and do not show the linearity with the square root of the hydroxylamine concentration. The mechanism of the process, not simple catalytic in nature, the chemical species that catalyze the processes are proposed. The characteristcs of the catalytic hydroxylamine waves have been determined and interpreted under various experimental conditions. Unified model for the kinetic and catalytic processes by introducing the feedback concept, thorough review on the catalytic current are also given.

Sella-Turcica 측면 방사선검사 기준에 관한 연구

채명준,임청환,정성훈 대한방사선과학회 2019 방사선기술과학 Vol.42 No.1

In order to analyze the factors affecting incidence angle and incident point when conducting a general radiography using Sella Turcica, the length and width of the head bone according to age and gender, length and width of Sella Turcica, and the distance between the front and the top of EAM to Sella Turcica were measured. The subjects were 400 patients who underwent a Skull series. For statistical analysis, t-test and ANOVA analysis were conducted using SPSS Ver.22.0. For post-test, Duncan was conducted and if the results were 95% or more (p<.05), it was determined to be significant. As a result of this study, the average length of the head bone was 177.45 mm, where the males were 182.84 ㎜ and the females were 172.05㎜ showing that males were measured longer (p<.001). The width of the head bone was 116.98㎜ on average, where the males were 119.18㎜ and the females were 114.77㎜(p<.001) showing that males were measured longer. The average length of Sella Turcica was 4.59㎜, where the males were 4.54㎜(p<.001) and the females were 4.63㎜(p<.001) showing that females were measured longer. The average length of Sella Turcica was 7.08㎜, where the males were 7.01㎜(p<.001) and the females were 7.16㎜(p<.001) showing that females were measured longer. The general radiology examination of Sella Turcica at a medical facility should be conducted in consideration of age and gender in accordance with the characteristics of Koreans.

Determination of Iron in Seawater by Adsorptive Stripping Voltammetry

채명준,김경,권영순,Czae, Myung-Zoon,Kim, Kyung,Kwon, Young-Soon Korean Chemical Society 1995 대한화학회지 Vol.39 No.3

바닷물 중의 미량 철을 별도의 사전 농축이나 분리절차 없이 바로 정량할 수 있을 만큼 예민하면서 비용이 절감되는 손쉬운 흡착 벗김 분석 방법을 제안한다. 용액의 pH가 8.0인 붕산염 완충액에서 철/카테콜 착물을 수은 방울전극에 흡착시켜 수집한 후 음극 벗김과정을 수행하면서 펄스차이 방식 전류를 측정한다. 최적조건은 2.5 mM 붕산염, pH 8.0, 2 mM 카테콜, 수집전위 -0.25 V, 수집시간 1~3분이었다. 이 조건에서의 검출한계는 1.5 nM Fe였다. 붕산염 완충용액(높은 pH)의 사용은 기존의 지지전해질에서 문제되던 구리의 방해를 피할 수 있음은 물론 바탕선의 기울기가 완만해져 바탕선 잡기가 매우 좋았으므로 정밀성의 향상을 기대할 수 있다. 표준물 첨가법에 의해 실제시료에 적용해 본 결과 기대에 잘 부합하였다. A simple procedure, readily available at low cost with a sensitivity sufficient to determine trace levels of iron in seawater is proposed, which utilizes adsorptive accumulation of the iron/catechol complex on the mercury drop electrode in a borate medium of pH 8.0. Optimal conditions include a solution concentration of 2 mM catechol, 2.5 mM borate and a pH of 8.0, an accumulation potential of - 0.25 V is applied for 1∼3 min, and the potential scan is in the differential pulse mode. The limit of detection is 1.5 nM Fe using a preconcentration time of 3 min. The interference from copper can be eliminated and baseline slope is greatly improved, because its peak is well separated from that of iron in the proposed medium.

이중층 전기용량 연속 측정 장치

채명준,우승수,최규원,Czae Myung-Zoon,Woo Seung-Soo,Choi Q. Won 대한화학회 1992 대한화학회지 Vol.36 No.5

전기저항이 큰(묽은) 용액에서도 금속전극의 이중층 전기용량을 전위와 시간의 변화에 따라 연속적으로 정확신속하게 측정할 수 있는 간단한 기기를 설계제작하였다. 주사전위에 작은 진폭의 삼각파를 겹칠 때 정전용량의 응답으로 주어지는 구형파를 관찰하면서 용액의 비보상 저항을 보정하여 평평한 부분을 얻고 이부위의 진폭을 샘플-홀드 회로로 채취하여 기록한다. 샘플링 위치와 기간의 조절가능 기능과 저잡음 대책을 마련하여 삼각파의 진폭을 7mV까지 낮출 수가 있어 페러데이 임피던스 영향을 줄일 수가 있었다. 몇가지 경우에 대한 성능 실험을 통해 응용성과 한계를 고찰하였다. An instrument is described that can obtain directly the whole capacitance vs. potential curve and accurately even in dilute solutions using positive feedback for IR correction. Applying a small (7∼10 mV) triangular signal, controlled rectification of the resulting square wave using sample-and-hold circuit allows one to plot the corrected double layer capacitance over a wide potential range. Several illustrations involving the improved performance characteristics of its applicability are given and its limitations discussed.

Derivative Thermometric Titrations Employing Operational Amplifier Instrumentation

채명준,변종홍,김상옥,Czae, Myung-Zoon,Pyun, Chong-Hong,Kim, Sang-Ok Korean Chemical Society 1970 대한화학회지 Vol.14 No.4

An improved derivative thermometric titration apparatus designed around operational amplifiers is described which is capable of monitoring the small temperature change and of computing the derivatives for accentuation of the titration end point that is difficult to locate by extrapolation methods. The instrument is constructed of four commercial operational amplifiers. A use of dummy cell provides the subtraction means for compensation of the initial temperature and random temperature fluctuations with a resultant gain in signal-to-noise ratio. The successive differentiation action of the computer has been nearly "perfect," so that the two breaks (blank or starting and end point of the titration curve can be located with the precision of 0.2% by observing two peak points on the second derivative curve. Arrangements useful in obtaining such a good derivative response that is exactly proportional to the input signal are discussed. Plots of the enthalphogram and its derivatives are presented, with the results of several titrations used to evaluate the performance of the apparatus.

일정전류 비평행교류브릿지에 의한 전도도측정과 황의 정량

채명준,최규원,Czae, Myung-Zoon,Choe, Gyu-Won 대한화학회 1970 대한화학회지 Vol.14 No.4

A simple and convenient device for deflection-type direct reading the variations in electrolytic conductance is described and applied to the analysis of sulfur by combustion-$H_2O_2$ oxidation method. The apparatus consisted of a high resistance-ratio bridge in which the other adjacent arms are the differential cells. By adopting unusually high a-c voltage source for the bridge excitation, the a-c method for unbalanced bridge is established, decreased sensitivity owing to reduced bridge factor, 0.01, is overcome and also the absolute sensitivity and linearity are greatly improved. Over 50% variations in impedance of the balanced cell, within 1% deviation from the linearity can be attained with a volt (rms)order of output which was detected directly with VTVM without further amplification. Analysis of the bridge shows that these useful features are natural result of the constant current character of the high source impedance generator and the performance of the device agreed with the theoretical predictions. A standard procedure for the rapid analysis of sulfur using the bridge is also given, the analytical accuracy was approximately 1%. A determination takes not more than 5 minutes.

환경과학의 시스팀연구

蔡命俊 漢陽大學校 環境科學硏究所 1980 環境科學論文集 Vol.1 No.-

경계영역적이며 광범위하며 복잡한 환경과학을 오염을 방지하여 환경을 보전하므로써 생존을 유지할려는 인간의 노력으로 보아 이들을 시스팀활동으로 하는 폐회로 제어시스팀으로 모델링하였다. 이 결과 시스팀경계가 결정되어 환경 문제의 일목요연한 계층구조를 짤 수 있고 각 시스팀요소의 확인에 의하여 환경보전법의 보완점 또는 연구기구의 필요성과 이들의 업무, 기능등이 명쾌하게 파악된다. An interdisciplinary field, the environmental science is modeled as a manually controlled closed-loop control system by employing the system postulation technique. The desription of this static model is presented at a three levels of detail. Regarding the human activities for survival by conservation of environments and controlling the pollutions as the consisting system activities, the system boundaries, entities and the attributes for each proposed system are identified. Some case studies are carried out giving a better understanding of the environmental problems. The implication of this system model leads also to the conclusion that some modifications are inescapable for the present laws and organizations for environmental problems.