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Detection of Food-Grade Hydrogen Peroxide by HRP-Biocomposite Modified Biosensors
장승철 한국식품위생안전성학회 2017 한국식품위생안전성학회지 Vol.32 No.6
A new amperometric biosensor has been developed for the detection of hydrogen peroxide (H2O2). The sensor was fabricated through the one-step deposition of a biocomposite layer onto a glassy carbon electrode at neutral pH. The biocomposite, as a H2O2 sensing element, was prepared by the electrochemical deposition of a homogeneous mixture of graphene oxide, aniline, and horseradish peroxidase. The experimental results clearly demonstrated of that the sensor possessed high electrocatalytic activity and responded to H2O2 with a stable and rapid manners. Scanning electron microscopy, cyclic voltammetry, and amperometry were performed to optimize the characteristics of the sensor and to evaluate its sensing chemistry. The sensor exhibited a linear response to H2O2 in the range of 10 to 500 μM concentrations, and its detection limit was calculated to be 1.3 μM. The proposed sensing-chemistry strategy and the sensor format were simple, cost-effective, and feasible for analysis of “food-grade H2O2” in food samples.
How should the regulatory defaults be set?
장승철 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.7
How to choose defaults in risk-informed regulations depends on the conservatism implicated in regulatorydefaults. Without a universal agreement on the approaches dealing with the conservatism ofdefaults, however, the desirability of conservatism in regulatory risk analyses has long been controversial. The opponent views it as needlessly costly and irrational, and the proponent as a form of protectionagainst possible omissions or underestimation of risks. Moreover, the inherent ambiguity of risk makes itdifficult to set suitable defaults in terms of risk. This paper, the extension of the previous work [1], focuseson the effects of different levels of conservatism implicated in regulatory defaults on the estimatesof risk. According to the postulated behaviors of regulated parties and the diversity of interests of regulators,in particular, various measures for evaluating the effect of conservatism in defaults are developedand their properties are explored. In addition, a simple decision model for setting regulatory defaults isformulated, based on the understanding of the effect of conservatism implicated in them. It can helpdecision makers evaluate the levels of safety likely to result from their regulatory policies
네트워크 통신에서 패킷의 암호화 알고리즘의 키 해킹시 데이터 보안을 위한 조립알고리즘 제안
장승철(Jang, Seung-Chul),전문석(Jeon, Mun-Seok) 한국산학기술학회 2010 한국산학기술학회 학술대회 Vol.- No.-
오늘날 네트워크 통신은 다양한 해킹방법들로부터 데이터를 보호하기 위하여 다양한 암호화 알고리즘을 사용하여 통신하고 있다. 이렇게 사용되는 암호화 알고리즘에서 키가 누출되어 해킹되었을 경우 데이터에 대한 정보누출 및 수정, 삭제 등의 데이터 가공을 당하게 된다. 본 논문에서는 이러한 문제를 보완하기 위하여 본래의 데이터를 섞고, 재조립하는 조립알고리즘을 제안한다.
Tetraethoxysilane의 졸-겔 반응을 이용한 전기화학적 glucose biosenor 개발
장승철 ( Seong Cheol Chang ),박덕수 ( Deog Su Park ) 한국센서학회 2012 센서학회지 Vol.21 No.4
Disposable amperometric screen-printed biosensor strips have been fabricated by a sol-gel encapsulation for the analysis of glucose. The glucose oxidase(GOx) is entrapped in the gel matrix through sol-gel transition of tetraethoxysliane(TEOS). The biosensor is fabricated by GOx containing thin film of TEOS gel on the surface of screen-printed carbon electrode(SPCE). The GOx-containing thin film of TEOS gel offers a one-step modification process on the surface of SPCE. The optimum conditions for glucose determination have been characterized with respect to the applied potential, enzyme loading ratio, and pH. The linear range and detection limit of glucose detection were from 2.0 mM to 16.0 mM and 0.25 mM, respectively.
장승철 ( Seung Cheol Chang ) 한국센서학회 2011 센서학회지 Vol.20 No.1
A disposable electrochemical immunosensor system has been developed for the detection of herbicide in aqueous samples. Disposable screen printed carbon electrodes(SPCE) were used as basic electrodes and an enzyme, horseradish peroxidase (HRP), and anti-herbicide antibodies was immobilised on to the working electrode of SPCE by using avidin-biotin coupling reactions. An herbicide-glucose oxidase conjugates have been used for the competitive immunoreaction with sample herbicides. The enzymatic reaction between the conjugated glucose oxidase and glucose added generates hydrogen peroxide, which was reduced by the peroxidase immobilised. The latter process caused an electrical current change, due to direct re-reduction of peroxidase by a direct electron transfer mechanism, which was measured to determine the herbicides in the sample. The optimal operational condition was found to be: 20 μgl-1 deglycosylated avidin loading to the working electrode and working potential +50 mV vs. Ag/AgCl. The total assay time was 15 min after sample addition. The detection limits for herbicides, atrazine and simazine, were found to be 3 ppb and 10 ppb, respectively.
FAULT-TREE-BASED RISK ASSESSMENT FOR DYNAMIC CONDITION CHANGES
강현국,장승철 한국원자력학회 2007 Nuclear Engineering and Technology Vol.39 No.2
In order to apply a static fault-tree (FT) method to a system or a plant whose configuration changes dynamically, condition gates and a post processing method are used to effectively accommodate these changes. An operator’s performance change, which can be caused by these configuration changes, should also be considered to assess the risk to a plant in a more realistic manner. This study aims to develop an integrated framework to accommodate various configuration changes and their effect on an operator’s performance by using the FT model. We applied a condition-based human reliability assessment (CBHRA) method to consider various conditions endured by an operator. That is, we integrated the CBHRA method with the conventional post processing method for modeling the system configuration changes. The effect of the condition monitoring systems installed in a plant is also considered. In this study, we show an example application of the integrated framework to a probabilistic safety assessment for the shutdown phase of a nuclear power plant.