Magnetism in Ni-W textured substrates for coated conductors

Song K. J.,Park Y. M.,Yang J. S.,Kim S. W.,Ko R. K.,Kim H. S.,Ha H. S,Oh S. S.,Park C.,Joo J. H.,Kim C. J. The Korea Institute of Applied Superconductivity a 2005 한국초전도저온공학회논문지 Vol.7 No.2

The magnetic properties of a series of both annealed (biaxially textured) and as-rolled (non-textured) Ni-xW alloy tapes with compositions x = 0,1,3, and 5 at.$\%$, were studied. Characterization methods included XRD analyses to investigate the biaxial cube texturing of the annealed Ni-W alloy tapes and studies of the magnetization M for both annealed and as-rolled Ni-W alloy tapes. Both the isothermal mass magnetizations M(H) of a series of samples at different fixed temperatures and M(T) in fixed field, employing a PPMS-9 (Quantum Design), were measured. The Ni-W alloys have shown much reduced ferromagnetism as W-content x increases. Both the saturation magnetization Msat and Curie temperature Tc decrease linearly with W-content x, and both Msat and Tc go to zero at critical concentration of Xc - 9.50 at. $\%$ W.

Effects of the addition of ZnO and Y₂O₃ on the electrochemical characteristics of a Ni(OH)₂ electrode in nickel-metal hydride secondary batteries

Jung, K.W.,Yang, D.C.,Park, C.N.,Park, C.J.,Choi, J. Pergamon Press ; Elsevier Science Ltd 2010 International journal of hydrogen energy Vol.35 No.23

This study examined the effects of the addition of ZnO and Y<SUB>2</SUB>O<SUB>3</SUB> on the electrochemical characteristics of a Ni(OH)<SUB>2</SUB> electrode in nickel-metal hydride (Ni-MH) secondary batteries. The discharge capacity of the electrode was less affected by the addition of ZnO and Y<SUB>2</SUB>O<SUB>3</SUB> at a 0.2 C-rate and 25<SUP>o</SUP>C. However, the addition of Y<SUB>2</SUB>O<SUB>3</SUB> deteriorated the discharge capacity and the cycle life of the electrode by increasing the charge transfer resistance of the electrode at an increased C-rate of 1 C and 25<SUP>o</SUP>C. Under severer conditions at 1 C-rate and 60<SUP>o</SUP>C, the electrode materials were separated from the current collector and, accordingly, the discharge capacity was abruptly degraded with cycling for the electrodes comprising only 4wt% ZnO or 4wt% Y<SUB>2</SUB>O<SUB>3</SUB>. In contrast, the electrodes containing both 2wt% ZnO and 2wt% Y<SUB>2</SUB>O<SUB>3</SUB> exhibited stable discharge capacity with cycling and excellent cycle life due to the high overvoltage for oxygen evolution. The present results indicate that the addition of ZnO and Y<SUB>2</SUB>O<SUB>3</SUB> with an optimum composition suppresses oxygen evolution in the interfaces between active materials and the current collector and improves the cycle life of the electrode.

Development of additive [¹¹C]CO₂ target system in the KOTRON-13 cyclotron and its application for [¹¹C]radiopharmaceutical production

Moon, B.S.,Lee, H.J.,Lee, W.K.,Hur, M.G.,Yang, S.D.,Lee, B.C.,Kim, S.E. North-Holland Physics Pub 2015 Nuclear instruments & methods in physics research. Vol.356 No.-

The KOTRON-13 cyclotron, which was developed in South Korea for the production of medical radioisotopes, has the structural limitation of only one beam-output port, restricting the production of the carbon-11 isotope. In the present study, we investigate the design of a switchable target system and develop an effective carbon-11 target in the KOTRON-13 cyclotron, for combination with the fluorine-18 target. The target system was designed by introducing a sliding-type element between the fluorine-18 and carbon-11 targets, a tailor-made C-11 target and its cooling system. For the efficient production of [<SUP>11</SUP>C]CO<SUB>2</SUB>, the desirable target shape and internal volume were determined by a Stopping and Range of Ions in Matter (SRIM) simulation program, and the target grid was modified to resist the cavity pressure during beam irradiation. We evaluated the [<SUP>11</SUP>C]CO<SUB>2</SUB> production while varying the material and thickness of the target foil, oxygen content of the nitrogen gas, and target loading pressure. Using sliding-type equipment including an additional gate valve and a high vacuum in a beam line, the bi-directional conversion between the fluorine-18 and carbon-11 targets was efficient regarding the accurate beam irradiation on both targets. The optimal [<SUP>11</SUP>C]CO<SUB>2</SUB> production for 30min irradiation at 60μA (86.6+/-1.7GBq in the target at EOB) was observed at a thickness of 19μm with HAVAR® material as a target foil and a target loading pressure of 24bar with nitrogen plus 300ppb of oxygen gas. Additionally, the coolant cavity system in the target grid and target chamber is useful to remove the heat transferred to the target body by the internal convection of water and thereby ensure the stability of the [<SUP>11</SUP>C]CO<SUB>2</SUB> production under a high beam current. In the application of C-11 labeled radiopharmaceuticals such as [<SUP>11</SUP>C]PIB, [<SUP>11</SUP>C]DASB, [<SUP>11</SUP>C]PBR28, [<SUP>11</SUP>C]Methionine and [<SUP>11</SUP>C]Clozapine, the radiochemical yields were shown to be 25-38% (decay corrected) with over 166GBq/μmol of specific activity. Consequently, the additive carbon-11 target system was successfully developed in only one output port of the KOTRON-13 cyclotron and exhibited the stable production of C-11 labeled radiopharmaceuticals.

Metal(loid) immobilization in soils with biochars pyrolyzed in N₂ and CO₂ environments

Igalavithana, Avanthi Deshani,Yang, Xiao,Zahra, Hilda Rizkia,Tack, Filip M.G.,Tsang, Daniel C.W.,Kwon, Eilhann E.,Ok, Yong Sik Elsevier 2018 Science of the Total Environment Vol.630 No.-

<P><B>Abstract</B></P> <P>Previous studies indicated that using CO<SUB>2</SUB> as a reaction agent in the pyrolysis of biomass led to an enhanced generation of syngas <I>via</I> direct reaction between volatile organic carbons (VOCs) evolved from the thermal degradation of biomass and CO<SUB>2</SUB>. In addition, the physico-chemical properties of biochar in CO<SUB>2</SUB> were modified. In this current study, biochars generated from red pepper stalks in N<SUB>2</SUB> and CO<SUB>2</SUB> (RPS-N and RPS-C, respectively) were tested for their effects on the immobilization of Pb, Cd, Zn, and As in contaminated soils. Soils were incubated for one month with 2.5% of RPS, and two biochars (<I>i.e.</I>, RPS-N and RPS-C) at 25°C. After the incubation period soils were analyzed to determine the amendment effects on the behavior of metal(loid)s. The potential availability and mobility kinetics of metal(loid)s were assessed by single extraction of ammonium acetate and consecutive extraction of calcium chloride, respectively. Sequential extraction was used to further examine potential changes in geochemical fractions of metal(loid)s. The increased soil pH induced by application of the biochars reduced the potentially available Pb, Cd, and Zn, while RPS-C significantly reduced Pb due to the high surface area and aromaticity of RPS-C. However, RPS-C mobilized potentially available As compared to RPS-N due to the increased soil pH. Biochars reduced the mobility kinetics of Pb, Cd, and Zn, and RPS-N effectuated the greatest reduction of As mobility. The RPS-C increased the Fe and Mn oxides, hydroxide, and organically bound Pb, while both biochars and RPS-N increased residual Cd and Zn, and organically bound As, respectively. When considering the two biochars, RPS-C was highly effective for immobilization of Pb in soils, but it had no effect on Cd and Zn and a negative effect on As. In addition, RPS-C significantly increased the total exchangeable cations in soils.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biochars markedly reduced Cd, Pb and Zn mobility in soils. </LI> <LI> Biochar pyrolyzed in CO<SUB>2</SUB> most effectively immobilized Pb. </LI> <LI> Biochar pyrolyzed in CO<SUB>2</SUB> increases As mobility more. </LI> <LI> More siloxane groups present in biochar pyrolysed in CO<SUB>2</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication of spherical biochar by a two-step thermal process from waste potato peel

Yang, Xiao,Kwon, Eilhann E.,Dou, Xiaomin,Zhang, Ming,Kim, Ki-Hyun,Tsang, Daniel C.W.,Ok, Yong Sik Elsevier 2018 Science of the Total Environment Vol.626 No.-

<P><B>Abstract</B></P> <P>The aim of this study was to develop a new approach for the preparation of spherical biochar (SBC) by employing a two-step thermal technology to potato peel waste (PPW). Potato starch (PS), as a carbon-rich material with microscale spherical shape, was separated from PPW as a precursor to synthesizing SBC. The synthesis process comprised (1) pre-oxidization (preheating under air) of PS at 220 °C and (2) subsequent pyrolysis of the pretreated sample at 700 °C. Results showed that the produced SBC successfully retained the original PS morphology and that pre-oxidization was the key for its shape maintenance, as it reduced surface tension and enhanced structural stability. The SBC possessed excellent chemical inertness (high aromaticity) and uniform particle size (10–30 μm). Zero-cost waste material with a facile and easy-to-control process allows the method to be readily scalable for industrialization, while offering a new perspective on the full use of PPW.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Potato starch (PS) derived from potato peel waste (PPW) has highly regular spherical shape. </LI> <LI> PS morphology was retained with pre-oxidation process after pyrolysis. </LI> <LI> PS's spherical shape affords great homogeneity to the produced biochar. </LI> <LI> Mechanism of shape maintenance was studied via various spectral characterizations. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

FUEL CELL ELECTRIC VEHICLES: RECENT ADVANCES AND CHALLENGES-REVIEW

W. -C. YANG 한국자동차공학회 2000 International journal of automotive technology Vol.1 No.1

The growing concerns on environmental protection have been constantly demanding cleaner and more energy efficient vehicles without compromising any conveniences provided by the conventional vehicles. The recent significant advances in proton-exchange-membrane (PEM) fuel cell technology have shown the possibility of developing such vehicles powered by fuel cells. Several prototype fuel cell electric vehicles (FCEV) have been already developed by several major automotive manufactures, and all of the favorable features have been demonstrated in the public roads. FCEV is essentially a zero emission vehicle and allows to overcome the range limitation of the current battery electric vehicles. Being motivated by the laboratory and field demonstrations of the fuel cell technologies, variety of fuel cell alliances between fuel cell developers, automotive manufactures, petroleum companies and govemment agencies have been formed to expedite the realization of commercially viable FCEV. However, there still remain major issues that need to be overcome before it can be fully accepted by consumers. This paper describes the current fuel cell vehicle development status and the staggering challenges for the successful introduction of consumer acceptable FCEVs.<br/>

SCM440H의 레이저 열처리 연구

전용호(Y. Jeon),염현호(H. Yeom),윤우준(W. J. Youn),정명찬(M. C. Chung),김성환(S. H. Kim),임채원(C. W. Lim),한상배(S. B. Lee),양승철(S. C. Yang) 한국생산제조학회 2013 한국생산제조시스템학회 학술발표대회 논문집 Vol.2013 No.4

항공기용 가스터빈 연소기의 수치해석 연구

양시원(S.W. Yang),정승채(S.C. Jung),김신현(S.H. Kim),박희호(H.H. Park),류시양(S.Y. Ryu),유경원(G.W. Ryu) 한국전산유체공학회 2015 한국전산유체공학회 학술대회논문집 Vol.2015 No.5

가공용 감자 저장중 맹아억제제 Pursuit 처리효과

정진철(Jeong J. C),김숭열(Kim S. Y),박천수(Park C. S),엄영현(Om Y. H.),신관용(Shin K. Y),박권우(Park K. W),양용준(Yang Y. J) 한국원예학회 1996 한국원예학회 학술발표요지 Vol.14 No.2

난류 파이프 유동 내 물질전달에서의 경계조건 영향

강창우(C.W. Kang),양경수(K.S. Yang) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5

Direct Numerical Simulation(DNS) of turbulent mass transfer in fully developed turbulent pipe flow has been performed to study the effect of wall boundary conditions on the concentration fields at Re<SUB>r</SUB>=180 based on friction velocity and pipe radius. Fully developed turbulent pipe flows for Sc=0.71 are studied with two different wall boundary conditions, namely, constant mass flux and constant wall concentration. The mean concentration profiles and turbulent mass fluxes obtained from the present DNS are in good agreement with the previous numerical results currently available. To investigate the effects of wall boundary condition on the turbulent mass transfer, the mean concentration profile, root-mean-square of concentration fluctuation, turbulent mass fluxes and higher-order statistics (Skewness and Flatness factor) are compared for the two cases. Furthermore, the budgets of turbulent mass fluxes and concentration variance were computed and analyzed to elucidate the effects of wall boundary conditions on the turbulent mass transfer.