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Development of magnetically separable Cu catalyst supported by pre-treated steel slag
윤선호,배성준 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.11
Wastewater contaminated with organic compounds is a serious problem; therefore, many catalysts, especially copper catalysts, have been developed to treat it and remove contaminants before discharge. However, such separation and reuse of these catalysts is often challenging. Steel slag (SS), a by-product of steel production, is produced in large quantities and requires careful disposal. Therefore, in this study, we developed a magnetically recyclable copper catalyst utilizing pre-treated magnetic steel slag (MSS) as a support. First, magnetic separation was carried out to remove calcium silicate impurities such as alite and belite in MSS up to five times, thus increasing the Fe content of the MSS. We synthesized the Cu catalyst supported by MSS (donated as Cu@MSS) and characterized the catalyst by various surface analysis techniques, showing the presence of CuO and CuCO3 nanoparticles on the MSS surface. In catalytic reduction tests of para-nitrophenol using sodium borohydride in the presence of Cu@MSS, the reaction was accelerated when using the five-times pre-treated MSS because of the removal of inhibitors such as calcium compounds, as well as the high content of iron oxides leading to a synergetic effect with metallic Cu in this study. In addition, we investigated the effects of various factors, including Cu loading, sodium borohydride concentration, and catalyst dosage, on the catalytic activity of Cu@MSS. The catalyst was found to be stable and reusable. In summary, these results suggest that treated SS can be used as a support material for copper catalysts for the treatment of contaminated wastewater and the easy separation and reuse of the catalyst.
알칼리형 연료전지용 수소극의 촉매 특성과 조촉매의 영향
윤선호,이홍기,이주성 ( Sun Ho Yun,Hong Ki Lee,Ju Seong Lee ) 한국공업화학회 1993 공업화학 Vol.4 No.2
The preparation method of Raney nickel catalyst and the effect of promoter for the hydrogen electrode in alkaline fuel cell were investigated with electrochemical methods. The best electrode performance was observed with the Raney nickel which was obtained at 700℃ of sintering temperature and 60:40 of nickel:aluminum. As titanium was added for promoter, the activity of catalyst and characteristic of electrode was improved. Especially, the electrode containing 2w/o of titanium showed the maximum mass activity of 2.4A/g and its mean particle size was 5.7㎛. The resistance and capacitance of the electrode containing 2w/o of titanium, measured with AC impedance spectroscopy, were calculated to the 0.3Ω㎠ and 0.42F/㎠, respectively.
FSR로 구성된 촉각 센서 패드용 Readout 회로의 설계 및 구현
윤선호,백승희,김청월,Yoon, Seon-ho,Baek, Seung-hee,Kim, Cheong-worl 한국센서학회 2017 센서학회지 Vol.26 No.5
A readout circuit for a tactile sensor pad based on force sensing resistors was proposed, which was composed of an analog signal conditioning circuit and a digital circuit with a microcontroller. The conventional signal conditioning circuit has a dc offset voltage in the output signal, which results from the reference voltage applied to the FSR devices. The offset voltage reduces the dynamic range of the circuit and makes it difficult to operate the circuit under a low voltage power supply. In the proposed signal conditioning circuit, the dc offset voltage was removed completely. The microcontroller with A/D converter and D/A converter was used to enlarge the measurement range of pressure. For this, the microcontroller adjusts the FSR reference voltage according to the resistance magnitude of FSR under pressure. The operation of the proposed readout circuit which was connected to a tactile sensor pad with $5{\times}10$ FSR array was verified experimentally. The experimental results show the proposed readout circuit has the wider measurement range of pressure than the conventional circuit. The proposed circuit is suitable for low voltage and low power applications.
윤선호,하원석,최종학 한국회계학회 2018 회계저널 Vol.27 No.6
This case study discusses the specific accounting standards (i.e., percentage of completion method) applied to shipbuilding and construction industries, which are conveniently called order-based industries. It first investigates the causes for the extreme operating losses that Hyundai Heavy Industry. Co. recognized in 2014 and 2015. Hyundai Heavy Industry Co., one of the most successful shipbuilding firms in Korea, enters marine plant industry in response to plummeting demand for shipbuilding after the 2008 Financial Crisis. However, lack of designing and construction capabilities and principals’ frequent request for revision of design led contract costs to surge significantly, while contract revenues were set low and fixed due to intense price-competition. Consequently, marine plant projects incurred huge losses. The losses recorded in 2014 and 2015 are partly due to K-IFRS 1011 Construction Contract, which mandates that the expected future losses be recognized as expense immediately. This case study aims to help students understand how the percentage of completion method applied to order-based industries (such as shipbuilding and construction) can affect the financial performance of firms belonging to the industries. It also discusses how the adoption of a new accounting standard, K-IFRS 1115, has effects on accounting practice in the industries. In doing so, it may be able to enhance proper understanding of accounting information produced under the percentage of completion method for the outside users of the financial statements. 본 사례연구는 공사진행기준이라는 특수한 방법을 사용하는 수주산업의 회계처리에 대해 살펴본다. 이를 위해 2014년과 2015년 현대중공업이 큰 규모의 영업손실을 기록하 게 된 원인에 대해 분석한다. 현대중공업은 2008년 금융위기에 따른 상선건조 수요 감소 에 대응하기 위해 해양플랜트 산업에 진출한다. 하지만 저가 수주와 더불어 설계 엔지니어 링 및 공사역량 부족과 발주사의 사양 변경 등의 이유로 예정공사원가가 예상보다 급증하 면서 큰 손실이 발생한다. 2014년과 2015년 현대중공업이 해양플랜트 산업에서 큰 손실 을 인식하게 된 배경에는 진행기준을 적용하면 예상손실을 조기에 인식하도록 규정한 K-IFRS 1011호의 영향이 크다. 본 사례연구를 통해 수주산업에서 사용되는 진행기준이 재무제표에 보고되는 경영성과에 어떤 영향을 미치는지 살펴본다. 또한 2018년부터 K-IFRS 제1115호가 도입되면서 수주산업의 회계처리가 어떻게 영향을 받는지를 학습한 다. 본 사례는 이러한 과정을 통해 회계정보이용자가 진행기준에 의해 생산된 회계정보를 올바르게 이해하는 것을 목표로 한다.