전압강하를 고려한 전기방식 기준 개정에 관한 연구

류영돈(Young-don Ryou),이진한(Jin-han Lee),조영도(Young-do Jo),김진준(Jin-Jun Kim) 한국가스학회 2016 한국가스학회지 Vol.20 No.4

도시가스사업법령에서는 매설된 강관에는 부식을 방지하기 위하여 전기방식 조치를 하도록 하고 있다. 미국 등 국외에서 방식전위기준은 방식전류가 흐르는 상태에서 포화황산동 기준전극으로 -850 ㎷(On potential) 이하로 하도록 하고 있으며, 이 경우 전압강하(IR-Drop)를 고려하도록 하고 있다. 그러나, 국내의 방식전위 기준은 포화황산동 기준전극으로 -850㎷ 이하로 하도록 규정하고 있을 뿐, 전압강하를 고려하도록 규정하고 있지 않다. 다만, KGS GC202에서 가스시설에 대한 전위측정은 가능한 한 가스시설과 가까운 위치에서 기준전극으로 실시하도록 하고 있다. 본 연구에서는 기준전극을 매설배관 주위, 지표면 및 지표면 하부 50㎝에 각각 설치하여 방식전위를 측정하고, 측정위치에 따른 전위값을 비교하여 전압강하를 분석하였다. 전위 측정결과 기준전극을 매설배관 가까이에 위치하였을 때 IR-Drop이 가장 적고, 지표면에 기준전극을 위치할 때 IR-Drop 값이 가장 큼을 확인하였다. 따라서, 고체기준전극을 매설하는 경우에는 가능한 한 매설배관 가까이에 설치할 것을 제안하였다. 또한, 기존에 설치된 배관의 원격전위 측정을 위해서는 기존에 설치된 전위측정용터미널(T/B) 하부에 고체기준전극을 매설할 수 있도록 전기방식 기준전극 설치 기준 개정(안)을 제시하였다. According to the urban gas business legislation, cathodic protection systems should be applied for buried steel gas pipelines to prevent corrosion. In advanced countries including United States, the criteria for Cathodic Protection Potential is at least -850㎷ with respect to a saturated copper/copper sulfate electrode(CSE) when the CP applied, and the IR drops must be considered for valid interpretation. However, the IR drop through the pipe to soil boundary has been neglected in Korea. According to KGS code, a reference electrode must be placed in proximity to gas pipelines possible when measuring the CP potential. In this study, we have installed several solid reference electrodes around the buried pipeline(1.2m depth), lower surface(0.5m depth), and the surface individually in order to measure the CP potentials through the each reference electrode and find out the IR drops according to the location of each reference electrode. We have found the IR drop is the greatest when measuring the CP potential through the electrode placed on the ground and the IR drop is the smallest through the electrode installed near pipeline. Therefore, we have suggested the solid reference electrode should be installed as close as possible to buried pipeline in order to measure the correct CP potential without IR drop. We have also suggested the amendment of CP criteria considering IR drop.

Oxygen evolution reaction on Pt sphere and Ir-modified Pt sphere electrodes with porous structures

Sung, Moonchang,Kim, Jongwon Elsevier 2018 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.43 No.4

<P><B>Abstract</B></P> <P>Oxygen evolution reactions (OER) have received recent attention because of their importance in electrochemical water splitting for sustainable energy sources. Here, the electrochemical OER activity on electrodeposited Pt sphere electrodes with porous structures was investigated. The dependence of the OER activity on the porosity of the Pt sphere electrodes was systemically examined by changing the charge during the electrodeposition of the Pt spheres. Significantly enhanced OER activities were observed on the porous Pt sphere electrodes compared to that on a flat Pt electrode, and the activity increased as the porosity of the Pt sphere increased. Pt spheres with rough nanoscale surface features exhibited greater OER activities than the smooth Pt sphere electrodes. The surfaces of the Pt sphere electrodes were modified with Ir by spontaneous replacement reactions, which resulted in an OER activity enhancement relative to the Pt sphere electrodes. The OER activity of Pt electrodes depending on the porosity and surface roughness demonstrated in this work gives insight into the fabrication of efficient OER electrocatalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Porous Pt spheres exhibited significantly enhanced OER activity than flat Pt. </LI> <LI> The OER activity at porous Pt electrodes increased with roughness factors. </LI> <LI> Rough Pt spheres exhibited higher OER activity than smooth Pt spheres. </LI> <LI> Ir-modified Pt spheres exhibited higher OER activity than flat Ir electrodes. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Iridium catalyst based counter electrodes for dye-sensitized solar cells

Noh, Y.,Yoo, K.,Kim, J.Y.,Song, O.,Ko, M.J. Elsevier 2013 Current Applied Physics Vol.13 No.8

Conventional Pt-based counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) have critical problems such as an expensive cost, dissolution and degradation in the iodine based electrolyte. In order to replace the Pt catalytic layer, as a cheaper and chemically stable material, iridium (Ir)-coated CEs were prepared for the application in DSSCs. The Ir catalytic layers with the thicknesses of 34, 46 and 69 nm were deposited to the fluorine doped tin oxide (FTO) glasses using a thermal evaporator. As the thickness of Ir catalytic layer increases, the sheet resistance decreases, however, the surface crack is enlarged. As a result, the electrocatalytic activity for the I<SUP>-</SUP>/I<SUB>3</SUB><SUP>-</SUP> redox electrolyte was optimized at the thickness of 46 nm, which was confirmed by cyclic voltammograms (CV) and impedance analysis. The photovoltaic performance of DSSC was also greatest when the 46-nm-thick Ir catalytic layer was employed as a CE (the conversion efficiency was 5.19%). Although the conversion efficiency of conventional Pt-coated CE was higher (7.38%), the performance of Ir-coated CE may be further enhanced if the Ir catalytic layer is more conformally coated without crack. These results promise that the Ir can be a suitable material to prepare inexpensive and chemically stable CEs of DSSCs.

Ir 전극 계면에서 위상이동 방법 및 상관계수를 이용한 수소의 흡착동온식 결정

전상규,Jeon, Sang-K. 한국전기화학회 2007 한국전기화학회지 Vol.10 No.2

백금족/수용액 계면에서 Langmuir, Frumkin, Temkin 흡착등온식(${\theta}\;vs.\;E$)을 결정하기 위해 최적중간주파수 일 때 위상이동($0^{\circ}{\leq}-{\varphi}{\leq}90^{\circ}$) 거동($-{\varphi}\;vs.\;E$)과 표면피복율($1{\geq}{\theta}{\geq}0$) 거동(${\theta}\;vs.\;E$) 사이의 선형 관계식 연구에 관한 위상이동 방법 및 상관계수를 제안하고 증명하였다. Ir/0.1 M KOH수용액 계면에서 음극 $H_2$ 발생 반응에 관한 수소의 Langmuir 및 Temkin 흡착등온식(${\theta}\;vs.\;E$), 평형상수(Langmuir 흡착등온식: $K=3.3{\times}10^{-4}mol^{-1}$, Temkin 흡착등온식: $K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}$), 상호작용 파라미터(Temkin 흡착등온식: g=4.6), 표준자유에너지($K=3.3{\times}10^{-4}mol^{-1}$ 일 때 ${\Delta}G_{ads}^0=19.9kJ\;mol^{-1},\;K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}$ 및 $0.2<{\theta}<0.8$일 때 $16.5<{\Delta}G_{\theta}^0<23.3kJ\;mol^{-1}$)를 결정한다. 수소 흡착부위의 비균일 및 측 방향 상호작용 효과는 무시할 수 있다. ${\theta}$의 중간값 즉, $0.2<{\theta}<0.8$일 때 Langmuir 또는 Frumkin 흡착등온식과 상관관계에 있는 Temkin 흡착등온식은 상관계수를 이용하여 쉽게 결정할 수 있다. 위상이동 방법 및 상관계수는 흡착동온식(${\theta}\;vs.\;E$) 및 연관된 전극속도론과 열역학 파라미터(K, g, ${\Delta}G_{ads}^0, {\Delta}G_{\theta}^0$)를 결정하기 위한 정확하고 확실한 기술 및 방법이다. The phase-shift method and correlation constants for studying a linear relationship between the behavior ($-{\varphi}\;vs.\;E$) of the phase shift ($0^{\circ}{\leq}-{\varphi}{\leq}90^{\circ}$) for the optimum intermediate frequency and that (${\theta}\;vs.\;E$) of the fractional surface coverage ($1{\geq}\theta{\geq}0$) have been proposed and verified to determine the Langmuir, Frumkin, and Temkin adsorption isotherms (${\theta}\;vs.\;E$) at noble metal/aqueous electrolyte interfaces. At an Ir/0.1 M KOH aqueous electrolyte interface, the Langmuir and Temkin adsorption isotherms (${\theta}\;vs.\;E$), equilibrium constants ($K=3.3{\times}10^{-4}\;mol^{-1}$ for the Langmuir and $K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}$ for the Temkin adsorption isotherm), interaction parameter (g = 4.6 for the Temkin adsorption isotherm), and standard free energies (${\Delta}G_{ads}^0=19.9kJ\;mol^{-1}\;for\;K=3.3{\times}10^{-4}\;mol^{-1}$ and $16.5<{\Delta}G_{\theta}^0<23.3\;kJ\;mol^{-1}\;for\;K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}\;and\;0.2<\theta<0.8$) of H for the cathodic $H_2$ evolution reaction are determined using the phase-shift method and correlation constants. The inhomogeneous and lateral interaction effects on the adsorption of H are negligible. At the intermediate values of ${\theta},\;i.e,\;0.2<{\theta}<0.8$, the Temkin adsorption isotherm (${\theta}\;vs.\;E$) correlating with the Langmuir or the Frumkin adsorption isotherm (${\theta}\;vs.\;E$), and vice versa, is readily determined using the correlation constants. The phase-shift method and correlation constants are accurate and reliable techniques to determine the adsorption isotherms (${\theta}\;vs.\;E$) and related electrode kinetic and thermodynamic parameters(K, g, ${\Delta}G_{ads}^0, {\Delta}G_{\theta}^0$).

Ir-192 방사선원의 밀봉 용접부 품질에 미치는 저항용접 공정변수의 영향

한인수,손광재,이영호,이유황,이준식,장경덕,박울재,박춘득,Han, In-Su,Son, Kwang-Jae,Lee, Young-Ho,Lee, You-Hwang,Lee, Jun-Sig,Jang, Kyung-Duk,Park, Ul-Jae,Park, Chun-Deuk 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.1

Ir-192 radiation sealed sources are widely employed to the therapeutic applications as well as the non-destructive testing. Production of Ir-192 sources requires a delicate but robust welding technique because it is employed in a high radioactive working environment. A GTA(Gas Tungsten Arc) welding technique is currently well established for this purpose. However, this welding method requires a frequent replacement of the electrode, which results in the delay of the production to take a preparatory action such as to isolate the radiation sources from the working place before getting access to the welding machine. Hence, a resistance welding technique is considered as an alternative method of the GTA welding technique. The advantages of resistance welding are high welding speed and high-rate production. Also it has very long life of electrode comparing to GTA welding. In this study, the resistance welding system and proper welding conditions were established for sealing Ir-192 source capsule. As a results of various experiments, it showed that electrode displacement can be employed as a indicator to predict welding quality. We proposed two mathematical models(linear and curvilinear) to estimate electrode displacement with process parameters such as applied force, welding current and welding time by using regression analysis method. Predicting results of both linear and curvilinear model were relatively good agreement with experiment.

Iridium catalyst based counter electrodes for dye-sensitized solar cells

노윤영,유기천,Jae-Yup Kim,송오성,고민재 한국물리학회 2013 Current Applied Physics Vol.13 No.8

Conventional Pt-based counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) have critical problems such as an expensive cost, dissolution and degradation in the iodine based electrolyte. In order to replace the Pt catalytic layer, as a cheaper and chemically stable material, iridium (Ir)-coated CEs were prepared for the application in DSSCs. The Ir catalytic layers with the thicknesses of 34, 46 and 69 nm were deposited to the fluorine doped tin oxide (FTO) glasses using a thermal evaporator. As the thickness of Ir catalytic layer increases, the sheet resistance decreases, however, the surface crack is enlarged. As a result, the electrocatalytic activity for the I-=I-3 redox electrolyte was optimized at the thickness of 46 nm, which was confirmed by cyclic voltammograms (CV) and impedance analysis. The photovoltaic performance of DSSC was also greatest when the 46-nm-thick Ir catalytic layer was employed as a CE (the conversion efficiency was 5.19%). Although the conversion efficiency of conventional Pt-coated CE was higher (7.38%), the performance of Ir-coated CE may be further enhanced if the Ir catalytic layer is more conformally coated without crack. These results promise that the Ir can be a suitable material to prepare inexpensive and chemically stable CEs of DSSCs.

위상이동 방법에 의한 다결정 $Ir/H_2SO_4$ 수성 전해질 계면에서 과전위 수소흡착에 관한 해석

천장호,문경현,Chun Jagn Ho,Mun Kyeong Hyeon 한국전기화학회 2000 한국전기화학회지 Vol.3 No.2

다결정 $Ir/H_2SO_4$수성 전해질 계면에서 중간주파수 구간의 위상이동 변화와 Langmuir흡착등온식 사이의 관계를 교류임피던스 방법 즉 위상이동 방법을 이용하여 연구 조사하였다. 간소화된 계면 등가회로는 전해질저항(Rs), Faraday저항$(R_F)$, 흡착유사용량$(C_\phi)$ 등가회로 요소$(C_P)$의 직렬접속으로 구성된다. 음전위(E)에 대한 위상이동$(-\phi)$과 표면피복율$(\theta)$ 변화율$[\Delta(-\phi)/{\Delta}E,\;{\Delta}{\theta}/{\Delta}E]$을 비교 및 제시하였다. 지연되는 위상이동$(-\phi)$은 음전위(E) 및 주파수(f)에 따르며, $\phi=tan^{-1}[1/2{\pi}f(R_s+R_F)C_P]$이다. 중간주파수(1 Hz)에서 위상이동 변화$(-\phi\;vs.\;E)$는 Langmuir흡착등온식 $(\theta\;vs.\;E)$의 결정에 적용할 수 있는 실험적인 방법이다. 다결정 Ir/0.1 M $H_2SO_4$ 전해질 계면에서 수소의 흡착평형상수(K)와 흡착표준자유에너지 $({\Delta}G_{ads})$는 각각 $2.0\times10^{-4}$와 21.1kJ/mol이며 과전위 수소흡착(OPD H)에 기인한다. The relation between the phase-shift profile fur the intermediate frequencies and the Langmuir adsorption isotherm at the poly-Ir/0.1 M $H_2SO_4$ aqueous electrolyte interface has been studied using ac impedance measurements, i.e., the phase-shift methods. The simplified interfacial equivalent circuit consists of the serial connection of the electrolyte resistance $(R_s)$, the faradaic resistance $(R_F)$, and the equivalent circuit element $(C_P)$ of the adsorption pseudoca-pacitance $(C_\phi)$. The comparison of the change rates of the $\Delta(-\phi)/{\Delta}E\;and\;\Delta{\theta}/{\Delta}E$ are represented. The delayed phase shift $(\phi)$ depends on both the cathode potential (E) and frequency (f), and is given by $\phi=tan^{-1}[1/2{\pi}f(R_s+R_F)C_P]$. The phase-shift profile $(-\phi\;vs.\;E)$ for the intermediate frequency (ca. 1 Hz) can be used as an experimental method to determine the Langmuir adsorption isotherm $(\theta\;vs.\;E)$. The equilibrium constant (K) for H adsorption and the standard free energy $({\Delta}G_{ads})$ of H adsorption at the poly-Ir/0.1 M $H_2SO_4$ electrolyte interface are $2.0\times10^{-4}$ and 21.1kJ/mol, respectively. The H adsorption is attributed to the over-potentially deposited hydrogen (OPD H).

Comparison of Retention Characteristics of Pb(Zr,Ti)O 3 (PZT) Capacitors Fabricated with Noble Metal Electrodes and Their Oxide Electrodes

SHIN, SANGMIN,CHO, CHOONG,KOO, JUNE,KIM, SUK,CHO, YOUNG-JIN,PARK, SUNG-HO,LEE, JUNG,PARK, YOUNGSOO,LEE, JUNE-KEY,JO, JI,KIM, DONG,NOH, TAE,YOON, JONG-GUL,KANG, BO Taylor Francis 2004 Integrated ferroelectrics Vol.64 No.1

<P>We compared retention characteristics of Pb(Zr,Ti)O 3 (PZT) capacitors with either noble metal electrodes or their oxide compounds. Very thin PZT films with thickness below 100 nm were deposited by metal-organic chemical vapor deposition (MOCVD) on Ir bottom electrodes, and Pt, Ir, IrO 2 were covered as top electrodes thereon. The capacitors with IrO 2 top electrodes had the better opposite-state retention performance than those with Pt, Ir top electrodes. Inserting IrO 2 top electrode affected the alleviation of the size effect more in the aged capacitors than in the virgin capacitors. In addition, we also discuss problems of using IrO 2 as a bottom electrode in our PZT capacitors.</P>

MOD 법으로 제조한 강유전성 SBT 박막에서 하부전극이 유전 및 전기적 특성에 미치는 영향

김태훈,송석표,김병호 한국전기전자재료학회 2000 전기전자재료학회논문지 Vol.13 No.8

S $r_{0.9}$/B $i_{2.1}$/T $a_{2}$/ $O_{9}$ solutions was synthesized by MOD (metalorganic decomposition) method. SBT thin films with 2000$\AA$ thickness were prepared on Ir $O_2$/ $SiO_2$/Si and Pt/Ti/ $SiO_2$/Si substrates using the spin coating process and then investigated the dielectric and electrical properties of them. In the case of using Ir $O_2$bottom electrode the hysteresis loop was saturated at lower temperature than Pt/Ti electrode but the breakdown phenomenon was occurred at low voltage because of the rough surface morphology and porous microstructure of SBT thin films. As the results of the fatigue and imprint characteristics related to the lifetime and reliability of devices after 10$^{10}$ cycles the fatigue rates were about 10% at the Ir $O_2$and Pt/Ti bottom electrodes. Both SBT thin films with Ir $O_2$ and with Pt/Ti bottom electrodes show a slight tendency to imprint after 10$^{9}$ cycles but do not lead to a failure.e.e.

수소 전착에 관한 다결정 Ir표면의 흡착부위 효과

천장호,문경현,Chun Jang Ho,Mun Kyeong Hyeon 한국전기화학회 1999 한국전기화학회지 Vol.2 No.3

0.2M LiOH전해질 내의 다결정 Ir표면에서 저전위 및 과전위 전착된 수소(UPD H및 OPD H)의 전이와 2구별되는 흡착부위를 위상이동 방법을 이용하여 연구하였다 순방향과 역방향 주사시, 순환 전압전류도에 UPD H 봉우리가 나타난다. 위상이동 변화 또는 Langmuir흡착등온식에 전이영역(-0.80 to -0.95 V vs. SCE)이 나타난다. 전이영역(-0.80 to -0.95 V vs. SCE)에서 수소 흡착평형상수(K)는 $7.9\tiems10^{-2}$에서 $1.5\times10^{-4}$또는 $1.5\times10^{-4}$에서 $7.9\times10^{-2}$로 전이한다. 마찬가지로, 수소 흡착표준자유에너지$({\Delta}G_{ads})$도 6.3kJ/mol에서 21.8kJ/mol 또는 21.8kJ/mol에서 6.3kJ/mol로 전이한다. 다결정 Ir표면에서 UPD H와 OPD H는 구별이 가능한 2종류의 전착된 수소같이 작용한다. UPD H봉우리와 전이영역은 다결정 Ir 표면에서 UPD H와 OPD H의 2 구별되는 흡착부위에 기인한다. The two distinct adsorption sites and transition between the under and over-potentially deposited hydrogen (UPD H and OPD H) on the polycrystalline iridium (poly-Ir) surface in the 0.2 M LiOH electrolyte have been studied using the phase-shift method. At the forward and backward scans, the UPD H peak occurs on the cyclic voltam-mogram. The transition region on the phase-shift profile or the Langmuir adsorption isotherm occurs at ca. -0.80 to -0.95 V vs. SCE. At the transition region (-0.80 to -0.95 V vs. SCE), the equilibrium constant (K) for H adsorption transits from $7.9\times10^{-2}\;to\;1.5\times10^{-4}$ and vice versa. Similarly, the standard free energy $({\Delta}G_{ads})$ of H adsorption transits from 6.3 to 21.8kJ/mol and vice versa. The UPD H and OPD H on the poly-Ir surface act as two distinguishable electroadsorbed H species. Both the UPD H peak and the transition region are attributed to the two distinct adsorption sites of the UPD H and OPD H on the poly-Ir surface.