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Kim, Sehwa,Yun, Su-Won,Lee, Boreum,Heo, Juheon,Kim, Kihyung,Kim, Yong-Tae,Lim, Hankwon Elsevier 2019 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.44 No.4
<P><B>Abstract</B></P> <P>Process simulation and design as well as economic analysis were carried out to evaluate technical and economic feasibility of steam reforming of methanol in a membrane reactor (MR) for ultra-pure H<SUB>2</SUB> production. Using a commercial process simulator, Aspen HYSYS<SUP>®</SUP>, comparative studies were conducted to investigate the effect of operating conditions including the H<SUB>2</SUB> permeance (1 × 10<SUP>−5</SUP> - 6 × 10<SUP>−5</SUP> mol m<SUP>−2</SUP> s<SUP>−1</SUP> Pa<SUP>−1</SUP>), a H<SUB>2</SUB>O sweep gas flow rate (1–20 kmol h<SUP>−1</SUP>), and a reaction temperature (448–493 K) in a conventional packed-bed reactor (PBR) and the MR using a previously reported reaction kinetics. Improved performances such as methanol conversions and H<SUB>2</SUB> yields were observed in the MR compared to the PBR and several design guidelines for the MR were obtained to develop H<SUB>2</SUB> separation membranes with optimal H<SUB>2</SUB> permeance and to select a suitable H<SUB>2</SUB>O sweep gas flow rate. In addition, economic analysis based on itemized cost estimations was conducted for a small-sized H<SUB>2</SUB> fueling station by calculating a unit H<SUB>2</SUB> production cost for both the PBR and the MR reflecting a current economic status in Korea. As a result, a cost saving of about 23% was obtained in the MR (7.24 $ kgH<SUB>2</SUB> <SUP>−1</SUP>) compared to the PBR (9.37 $ kgH<SUB>2</SUB> <SUP>−1</SUP>) confirming the benefit of employing the MR for ultra-pure H<SUB>2</SUB> production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Techno-economic analysis for steam reforming of methanol was conducted. </LI> <LI> Improved methanol conversion and H<SUB>2</SUB> yield were obtained in the MR. </LI> <LI> A cost saving of about 23% in a unit H<SUB>2</SUB> production cost was observed in the MR. </LI> </UL> </P>
Increase in serum haptoglobin and apolipoprotein M in patients with obstructive sleep apnoea
KIM, JINKWAN,LEE, SEUNGGWAN,IN, KWANGHO,KIM, JEHYEONG,YOU, SEHWA,KANG, KYUNGHO,SIM, JAEJEONG,LEE, SANGYEUB,YOON, DAEWUI,LEE, JUNGBOK,SHIN, CHOL Blackwell Publishing Ltd 2009 Journal of sleep research Vol.18 No.3
<P>Summary</P><P>Obstructive sleep apnoea (OSA) is a common syndrome, which is associated with a number of medical problems that impact morbidity and mortality. Although the precise mechanisms that underlie these associations are not fully understood, previous studies have suggested that patients with OSA show elevations of several biomarkers that are associated with cardiovascular risk. This study was undertaken to identify serum proteins associated with OSA by using a proteomics technique and to examine changes in identified protein levels after continuous positive airway pressure treatment. The study participants consisted of 40 male patients (aged 40–49 years) with severe OSA and 34 male control subjects matched for age and body mass index. All subjects underwent polysomnography. Using a proteomics approach, we identified nine proteins that were differentially expressed in patients with severe OSA and controls. Three of these nine proteins, haptoglobin, paraoxonase-1 and apolipoprotein M, were quantified by using enzyme-linked immunosorbent assays, kinetic assays and by using Western blotting. Multiple regression analysis showed that haptoglobin and apolipoprotein M levels are independently related to apnoea–hypopnoea index (<I>P</I> < 0.01). A further study is required to determine the nature of associations between these identified proteins and OSA in a large population.</P>
Kim, Chang-Hyun,Han, Jae-Yun,Kim, Sehwa,Lee, Boreum,Lim, Hankwon,Lee, Kwan-Young,Ryi, Shin-Kun Elsevier 2018 International journal of hydrogen energy Vol.43 No.15
<P><B>Abstract</B></P> <P>With the aim of producing hydrogen at low cost and with a high conversion efficiency, steam methane reforming (SMR) was carried out under moderate operating conditions in a Pd-based composite membrane reactor packed with a commercial Ru/Al<SUB>2</SUB>O<SUB>3</SUB> catalyst. A Pd-based composite membrane with a thickness of 4–5 μm was prepared on a tubular stainless steel support (diameter of 12.7 mm, length of 450 mm) using electroless plating (ELP). The Pd-based composite membrane had a hydrogen permeance of 2.4 × 10<SUP>−3</SUP> mol m<SUP>−1</SUP> s<SUP>−1</SUP> Pa<SUP>−0.5</SUP> and an H<SUB>2</SUB>/N<SUB>2</SUB> selectivity of 618 at a temperature of 823 K and a pressure difference of 10.1 kPa. The SMR test was conducted at 823 K with a steam-to-carbon ratio of 3.0 and gas hourly space velocity of 1000 h<SUP>−1</SUP>; increasing the pressure difference resulted in enhanced methane conversion, which reached 82% at a pressure difference of 912 kPa. To propose a guideline for membrane design, a process simulation was conducted for conversion enhancement as a function of pressure difference using Aspen HYSYS<SUP>®</SUP>. A stability test for SMR was conducted for ∼120 h; the methane conversion, hydrogen production rate, and gas composition were monitored. During the SMR test, the carbon monoxide concentration in the total reformed stream was <1%, indicating that a series of water gas shift reactors was not needed in our membrane reactor system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CH<SUB>4</SUB> conversion reached ∼82% at a ΔP = 912 kPa at 823 K in Pd/PSS membrane reformer. </LI> <LI> H<SUB>2</SUB> ∼97.7% was obtained in the permeate stream with CO<SUB>2</SUB> 60% in the retentate stream. </LI> <LI> MSR results in Pd/PSS membrane reactor was well agreement with simulation results. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Electric Propulsion Naval Ships with Energy Storage Modules through AFE Converters
Kim, So-Yeon,Choe, Sehwa,Ko, Sanggi,Kim, Sungmin,Sul, Seung-Ki The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.2
This paper proposes a novel electric propulsion system for naval ships, which consists of Active Front End (AFE) converters directly connected to battery Energy Storage Modules (ESMs). Employing the proposed AFE converters with ESMs in the power systems of naval ships can enhance the reliability and quality of the electric power. Furthermore, the fuel-efficiency of the generator can be improved by a higher loading factor of the generator and its prime movers. The proposed AFE configuration does not require an additional dedicated DC/AC converter for the ESMs. Instead of that, the AFE converter itself can control the DC link voltage and the discharging and/or charging of the ESMs. A control scheme to achieve these control objectives is also presented in this paper. The overall power system, including the generators and electrical loads of a naval ship, is implemented by a small scaled Power Hardware-In-the-Loop (PHIL) simulator. Through this experimental setup, the proposed system configuration and the power control strategies are verified. It is shown that the fuel-efficiency and transient dynamics can be improved in the normal and contingency operation modes.
다매체 활용 환경교육이 초등학생의 환경친화적 태도에 미치는 영향
김세화(Sehwa Kim),이상원(Sang-Won Lee) 한국환경교육학회 2008 環境 敎育 Vol.21 No.3
The purpose of this study was to investigate the influences of environmental education program through various instructional media on pro-environmental attitudes of forth graders in an elementary school in Seoul. The students were divided into an experimental group and a control group. A questionnaire was used to survey the effects of applying environmental education program through various instructional media. The SPSS 12.0 program was used to analyze the results. The student in the experimental group acquired a higher level of pro-environmental attitudes than the control group did. The environmental education program through various instructional media used in this study were effective especially in dealing with the environmental educational subdomains such as verbal commitment, actual commitment, affect. The major results of this study were as follows. First, environmental education program through various instructional media had a positive effect on the environmental concerns and needs for learning of environmental problems. Second, the group by environmental education program through various instructional media showed the significant difference(p<.001) on the pro-environmental attitudes as it proved those are effect on 3 subdomains of verbal commitment, actual commitment and affect. Third, environmental education program through various instructional media had a positive correlation(from 585 to .680) among the 3 subdomains of verbal commitment, actual commitment and affect. So, students who hold verbal commitment showed good effect on the actual commitment and affect. In conclusion, the environmental education program through various instructional media had a positive effect on pro-environmental attitudes of elementary school students. It is demanded that more intensive research on this study should be done, linking with teaching and learning method, as a follow-up activity.