형광 검출 흐름 주입 분석법에 의한 암모늄 이온의 선택적 정량

최용욱,김미경,최윤정 전주대학교 자연과학종합연구소 1997 전주대학교 자연과학연구소 학술논문집 Vol.10 No.3

Selective determination of aqueous ammonia by flow injection analysis with fluorometric detection was described. The length of the mixing coil and the reaction coil, the composition of organic solvent, the sulfite concentration, the pH of buffer solution and the reaction temperature were optimized as analytical parameters for selectively determining NH_4^+/NH_3 by using FIA setup. The limit of detection (LOD) and the repeatability for aqueous ammonia were 0.04 ㎍/L (3SD) and better than 1%, respectively. This analytical condition showed considerable selectivity for aqueous ammonia over amino acids studied. Examples of the use of this FIA system were given for the anlysis of aqueous ammonia in lab water, tap water and groundwater.

베이지안 최적화를 이용한 암상 분류 모델의 하이퍼 파라미터 탐색

최용욱,윤대웅,최준환,변중무 한국지구물리.물리탐사학회 2020 지구물리와 물리탐사 Vol.23 No.3

With the recent advancement of computer hardware and the contribution of open source libraries to facilitate access to artificial intelligence technology, the use of machine learning (ML) and deep learning (DL) technologies in various fields of exploration geophysics has increased. In addition, ML researchers have developed complex algorithms to improve the inference accuracy of various tasks such as image, video, voice, and natural language processing, and now they are expanding their interests into the field of automatic machine learning (AutoML). AutoML can be divided into three areas: feature engineering, architecture search, and hyperparameter search. Among them, this paper focuses on hyperparamter search with Bayesian optimization, and applies it to the problem of facies classification using seismic data and well logs. The effectiveness of the Bayesian optimization technique has been demonstrated using Vincent field data by comparing with the results of the random search technique. 최근 인공지능 기술의 발전과 함께 물리탐사의 다양한 분야에서도 인공지능의 핵심 기술인 머신러닝의 활용도가증가하고 있다. 또한 머신러닝 및 딥러닝을 활용한 연구는 이미지, 비디오, 음성, 자연어 등 다양한 태스크의 추론 정확도를 높이기 위해 복잡한 알고리즘들이 개발되고 있고, 더 나아가 자료의 특성, 알고리즘 구조 및 하이퍼 파라미터의 최적화를 위한 자동 머신러닝(AutoML) 분야로 그 폭을 넓혀가고 있다. 본 연구에서는 AutoML 분야 중에서도 하이퍼 파라미터(hyperparameter) 자동 탐색을 위한 베이지안 최적화 기술에 중점을 두었으며, 본 기술을 물리탐사 분야에서도 암상 분류(facies classification) 문제에 적용했다. Vincent field의 현장 물리검층 및 탄성파 자료를 이용하여 암상 및 공극유체를 분류하는 지도학습 기반 모델에 적용하였고, 랜덤 탐색 기법의 결과와 비교하여 베이지안 최적화 기반 예측 프레임워크의 효율성을 검증하였다.

Surface treatment of iron by electrochemical oxidation and subsequent annealing for the improvement of anti-corrosive properties

최용욱,신소운,박동화,최진섭 한국물리학회 2014 Current Applied Physics Vol.14 No.5

Corrosion resistance of iron oxides on iron foils prepared by anodization, annealing or a combination of both was characterized by electrochemical methods. Even though iron oxide film with a thickness of more than 2 mm could be prepared by single anodization, corrosion resistance deteriorated because the oxide film was in the amorphous phase and contained many defects. Corrosion resistance of iron oxides was also not enhanced by single annealing. Conversely, combination of anodization and subsequent annealing led to a positive shift of the corrosion potential in the Tafel plot, indicating that corrosion resistance was improved. Formation of thicker oxide during anodization was associated with a more positive shift in corrosion potential after annealing. Electrochemical impedance spectroscopy showed that the slowest charge transfer was observed in oxide films grown by a combination of anodization and annealing. We found that the optimum annealing temperature of anodic films in terms of the most positive shift of Ecorr was 500 C.

흐름주입 분석법에 의한 상수중 아염소산 이온의 정량

최용욱,김미경 전주대학교 자연과학종합연구소 1996 전주대학교 자연과학연구소 학술논문집 Vol.9 No.2

The determination of chlorite ion in tap water by flow injection analysis(FIA) with iodometric UV detection were investigated. The pH of the acid stream, the concentration of the iodide ion, the length of the mixing coil and the reaction coil, the injection loop volume, temperature, and flowrate were optimized as parameters for selectively determining a sort of inorganic disinfection by-product, chlorite ion by using FIA setup. Under rather acidic condition(pH1.5), chlorite ion react with iodide ion to form iodine and itself is reduced to chloride ion. Masking agents for removing oxidants or interferences from the sample mixtures were tested. Independent calibration curve presented linear range of 0.002-0.2mg/L for chlorite ion with a correlation coefficient of 0.999 or better. The detection limit was 0.18㎍/L for chlorite ion. Under these analytical conditions, chlorite ion concentrations in several tap water of Jeonju area were measured.

P-27 : Determination of Aldehydes in Drinking Water by HPLC / UV / ECD

최용욱,최윤정,이수영,김성호,김미경 한국분석과학회 1998 학술대회논문집 Vol.- No.-

흐름 주입 분석법에 의한 하이포아염소산 이온의 분광학적 정량

崔鎔旭,李秀令,金美警 전주대학교 1999 論文集 Vol.24 No.2

흐름주입 분석법(FIA)에 의한 간접 요오드화 UV 검출법으로 하이포 차아염소산 이온을 신속하게 정량하는 방법을 연구하였다. FIA장치를 최적화하기 위해 용리액의 pH, 요오드화 이온의 농도, 혼합 및 반응코일의 길이, 시료주입량 및 유속, 온도 및 검출파장에 대한 변화를 고찰하였다. pH 8.3에서 하이포아염소산 이온은 요오드화 이온을 선택적으로 산화시키고 자신은 염화이온으로 환원되었다. 방해이온을 제거하기 위한 가리움제로서 에틸랜다이아민이 가장 좋은 효율을 나타내었다. 하이포아염소산 이온의 검정곡선은 0.03∼0.3mg/L의 농도범위에서 0.999이상의 직선성을 나타내었고, 검출한계는 0.007mg/L 이었다. 이러한 분석조건하에서 몇몇 전주근교 상수 중 총 잔류염소의 농도를 정량하였다. The determination of hypochlorite ion by flow injection analysis(FIA) with iodometric UV detection was investigated. The pH of the acid stream, the concentration of the iodide ion, the length of the mixing and reaction coils, the injection sample size, and flowrate were optimized as parameters for determining total chlorine residuals by FIA method. Iodide was selectively oxidized to iodine by hypochlorite ion at pH 8.3. Ethylenediamine as masking agent for masking interference ions from the sample was given the best efficency. Calibration curve presented linear range of 0.03-3mg/L for hypochlorite ion with a correlation coefficient of 0.999 or better, The detection limit was found to be 0.007mg/L for hypochlorite ion, Under these analytical conditions, total chlorine residuals in several tap water sampled in the city of Jeonju were analyzed.

플라즈마 표면처리를 통한 CO₂ 전기화학적 전환 촉매성능 개선

최용욱,Choi, Yong-Wook 한국표면공학회 2022 한국표면공학회지 Vol.55 No.5

CO₂ electroreduction is considered as a means to overcome climate change by converting CO₂ into value-added chemicals and liquid fuels. Although numerous researchers have screened versatile metal for the use of electrodes, and looked into the reaction mechanism, it is still required to develop highly enhanced electrocatalyst for CO₂ reduction to reach beyond lab-scale. Plasma treatment applying onto the surface of meal electrodes could improve activity, selectivity and stability of the electrocatalysts. This review highlights the effect of plasma pretreatment, and provides insight to design suitable CO₂ electrocatalyst.

소설을 통한 독자의 정체성 탐구

최용욱 한국언어문학교육학회 2013 한어문교육 Vol.29 No.-

제연용 벽부형 축류 송풍기 개발 과제 진행 및 성과

최용욱 한국유체기계학회 2021 유체기계 연구개발 발표회 논문집 Vol.2021 No.7

Investigation of heteromaterial effect in Ti nanostructured electrode for water electrolysis application

최용욱,남희일,임동하 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

Hydrogen fuel obtained via water electrolysis has been attracted as a clean energy source. Although water electrolysis has reached matured technological level, it is still necessary to find alternative electrode material due to the employment of novel metal such as platinum. Titanium oxide (TiO_x) proved the possibility for counter electrode, impacting the overall kinetic, employed in water electrolysis. To enhance activity of TiO_x electrode, several chemical species was deposited (doped) over TiOx electrode. This study investigated the heteromaterial role in water electrolysis by measuring the performance of TiO_x. In addition, morphological/chemical structure analysis elucidated how deposited heteromaterial influenced TiOx electrode during electrolysis. Acknowledgments