LSM 및 LSM-YSZ 양극의 임피던스 특성에 미치는 집전층의 효과

문지웅,이홍림,김구대,김재동,이해원 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.10

Effect of current collecting layer on the cathode was characterized by AC impedance spectroscopy at 800$^{\circ}C$ under flowing air. LSM-YSZ composite cathode showed lower polarization resistance due to the in-crease of triple phase (LSM/YSZ/Pore) boundary length by incorporation of YSZ. Ohmic resistance {{{{ {R }_{1 } }} of LSM-YSZ was higher than that of pure LSM however because in-plane resistance of the cathode was fair-ly high due to its high specific resistivity. To reduce the in-plane resistance of LSM-YSZ cathode cathode side current collecting layer was required. Ohmic resistance {{{{ {R }_{1 } }} was reduced after forming LSM current col-lecting layer on the LSM-YSZ cathode. In case of pure LSM cathode the formation of Pt, or LSCO current collecting layer reduced polarization resistance {{{{ {R }_{p } }} but ohmic resistance {{{{ {R }_{1 } }} was relatively constant. After annealing of LSM cathode with Pt current collector at higher temperature polarization resistance {{{{ {R }_{p } }} was in-creased but ohmic resistance {{{{ {R }_{1 } }} was constant. These phenomena indicate that Pt or LSCo current col-lecting layers act as a catalytic layer for oxygen reduction of pure LSM cathode. LSCO current collector was effective in reducing the ohmic and polarization resistance of LSM-YSZ cathode.

지역소공인 육성 방안

최태환,윤병섭 경남대학교 산업경영연구소 2015 지역산업연구 Vol.38 No.3

The Local Small Manufacturer(LSM) orients its networking-economical structure towards appropriate location regarding the regional features. Advanced nations continue to support the family-based-business LSM who are spread throughout regions to constitute economic clusters. Our country also guides LSM to start their business and help the industry grow with support. This would enhance the promotions of employment and build stronger industrial infrastructure. However, support policies for LSM still need improvements. If improvement policies had managed to encourage activities of LSM, who has the structure of business system on livelihood and independent business models, we believe that this would create more opportunities for small-medium enterprises to grow bigger. Firstly, we should establish reinforcement policies oriented for LSM. We must measure the effects of LSM improvement which is stipulated on [Special Law for urbanized LSM support]. Also, we should focus on building the infrastructure of social protection to help adjust the change of economic and social environment. Secondly, we should reform the operational independence of support to LSM. LSM are closely linked with establishment of manufacturing industries. Hence, we should re-classify the main supporting organizations, such as the Small-Medium Enterprises Promotion Agency, to focus on financing the policy. Thirdly, we should re-establish the direction of financial policy regarding LSM's towards to productive welfare. It would encourage the potential growth, resulting to enhance employments, improvement of individual productivity and so forth. Fourthly, we should maintenance the infrastructure to ensure the social guard for systematic support of financial support, such as financial policy specialized for LSM, and support of a means of living after the cessation of business. Fifthly, we need to improve the efficiency of LSM's financial support. The government has been expanding the LSM's financial support policies in order to reduce the market failure. But considering the report on the lack of efficiency of the policy, it should raise the value of business by improving the mutual relationship of social responsibility and purpose of policies. By the accurate statistical production on the scale of support on LSM, we should reduce the information-asymmetry;build strategic credit evaluation system and establish relationship-financial revitalization of the industry, This, then, would raise the direct observation of economic achievement along with the right existence of financial support for the purpose of policies. 소공인은 지역특성에 따라 적정한 위치에서 네트워크 경제구조를 지향한다. 선진국은 여러 지역에 산재한 가족기업 형태의 생계형 소공인이 클러스트를 형성하도록 지원하고 있다. 우리나라도소공인의 창업과 성장을 지원해 고용기회 창출 및 산업 인프라 형성을 유도하고 있다. 그러나 지역소공인 지원 정책은 여전히 개선할 필요성이 있다. 개선 정책이 생계형, 자영업 구조를 지니고있는 소공인의 활동을 촉진한다면 소기업, 중기업으로 성장할 수 있는 발판이 될 것으로 판단된다. 첫째, 「도시형소공인 지원에 관한 특별법」등에 나타난 소공인 육성 정책 효과를 측정해 발견되는 문제점을 바탕으로 소공인 경영기반 강화 정책을 수립해야 한다. 그리고 경제적․사회적 환경의 변화에 적응하는 사회안전망 확충 기반 조성에 힘써야 한다. 둘째, 소공인 지원 운영 주체의 변경이다. 소공인은 제조관련 뿌리산업의 업종과 관련이 깊으므로 중소기업진흥공단 등 제조업 중심의 지원기관이 정책자금을 전담하게 지원기관을 재분류해야 한다. 셋째, 성장잠재력을 끌어내 일자리 창출, 개인 단위당 생산성 향상 등을 이루는 지속가능한 생산적 복지에 소공인 관련 정책자금 지원 방향을 설정해야 한다. 넷째, 소공인 특화 정책자금 확대 등 재정지원을 체계적으로 뒷받침할 수 있는 시스템과 폐업후 생계보전 등 사회적 안전망을 확충할 수 있는 인프라를 정비해야 한다. 다섯째, 소공인 자금지원 효율성 증진이다. 정부는 시장실패를 완화하기 위해 확대해온 소공인금융지원 정책의 효율성이 낮다는 평가를 고려할 때 정책목적성과 사회적 책무 상호관계 증진으로사업의 가치를 높여야 한다. 소공인 지원규모에 대한 정확한 통계생산으로 정보비대칭성을 완화하는 정성적·정량적 신용평가시스템 구축, 관계형 금융 활성화 터전 마련 등 정책목적성을 띈 자금지원 존립 당위성으로 경제적 체감 성과를 높여야 한다.

Conditioning Effects on LSM-YSZ Cathodes for Thin-film SOFCs

Lee You-Kee,Visco Steven J. The Korean Electrochemical Society 1999 한국전기화학회지 Vol.2 No.4

[ $50/50 vol\%$ ] LSM-YSZ의 양극은 콜로이드 증착법에 의해 YSZ 전해질상에 증착하였다. 양극 특성은 주사전자현미경과 임피던스 분석기에 의해 고찰하였다. LSM-YSZ양극의 제조 조건에 따른 영향을 관찰하였으며, 그 영향에 대한 개선책이 고체산화물 연료전지의 성능향상을 위해 제시되었다. 임피던스에 대한 온도, YSZ전해질로의 양극 접착에 대한 표면 오염, 사용하는 Pt 페이스트, 미세구조에 대한 곡표면에 가해진 연무질 분사기술과 셀과 셀의 변동성에 대한 영향들은 각각 $900^{\circ}C$ 측정, YSZ표면 연마, 일단의 Pt페이스트 사용, 평편한 YSZ판의 사용과 일관된 절차와 기술의 사용에 의해 해결되었다. 이때 재현성 있는 임피던스 스펙트럼들이 향상된 셀을 사용함으로써 얻어졌고, $900^{\circ}C$에서 (공기)LSM-YSZ/YSZ/LSM-YSZ(공기) 셀에 대해 측정된 전형적인 임피던스 스펙트럼들은 2개의 불완전한 호로 구성되었다. 또한 LSM-YSZ 양극의 임피던스 특성은 촉매층, 양극 조성, 인가 전류 등과 같은 실험 조건들에 의해서도 영향을 받았다. Composite cathodes of $50/50\;vol\%$ LSM-YSZ $(La_{-x}Sr_xMnO_3-yttria\;stabilized\;zirconia)$ were deposited onto dense YSZ electrolytes by colloidal deposition technique. The cathode characteristics were then examined by scanning electron microscopy (SEM) and studied by ac-impedance spectroscopy (IS). The conditioning effects on LSM-YSZ cathodes were seen and remedies for these effects were noted in order to improve the performance of a solid oxide fuel cell (SOFC). The effects of temperature on impedance, surface contamination on cathode bonding to YSZ electrolyte, changing Pt paste, aerosol spray technique applied to curved surface on microstructure and cell to cell variability were solved by testing at $900^{\circ}C$, sanding the YSZ surface, using only one batch of Pt paste, using flat YSZ plates and using consistent procedures and techniques, respectively. And then, reproducible impedance spectra were confirmed by using the improved cell and the typical spectra measured for an (air)LSM-YSZ/YSZ/LSM-YSZ(air) cell at $900^{\circ}C$ were composed of two depressed arcs. Impedance characteristics of the LSM-YSZ cathodes were also affected by experimental conditions such as catalytic interlayer, composite cathode compositions and applied current.

2相 Linear Stepping Motor의 진동특성에 관한 연구

오홍석,김동희,이상호,정도영,김춘삼 전력전자학회 1999 전력전자학회 논문지 Vol.4 No.6

리니어 스텝핑 모터(Linear Stepping Motor : 이하 LSM이라 칭함)는 운동 변환기구 없이 입력신호에 따라 선형적인 변위를 발생시키는 다이렉트 드라이브(Direct Drive)방식의 전동기이다. 따라서 LSM은 자동반송장치, 의료기기, OA,FA 응용 등에 다양하게 사용되고 있다. 그러나 LSM은 구동시 구조적으로 큰 진동이 발생됨으로서 추력이 급격히 떨어질 때가 있으며, 최악의 경우에는 역전이나 탈조현상이 발생하고, 또한 소음의 원인이 되기 때문에 응용에 있어서 많은 제약을 받고 있는 실정이다. 여기에 대응하기 위해, 본 논문에서는 권선 인덕턴스에 저장된 에너지와 LSM의 유도전압을 이용한 새로운 1상 여자방식에 의한 진동억제 방법을 보여주며, 또한 LSM의 구조를 기초로 자기등가회로를 구성하였으며, 또한 자기등가회로에 대한 방정식을 이용하여 LSM의 전기적인 등기회로를 유도하였다. 그리고, LSM의 새로운 1상 여자방식에 의한 진동특성을 전압방정식과 추력방정식 및 운동방정식을 사용하여 ACSL에 의하여 시뮬레이션 하였으며, 레이저 실측 시스템에 의한 실측결과와 비교·검토하였다. In this paper, a vibration suppression method using an energy stored in winding inductance and an induced v voltage of the Linear Stepping Motor(LSM) is shown, and it is applied to a new one-phase excitation method A And a magnetic equivalent circuit is based on the structure of the LSM, and then the electric equivalent circuit of the LSM is derived by solving equations for the magnetic equivalent circuit. Several dynamic characteristics of the LSM are analyzed by the ACSL with the voltage equations, the force equations and the kinetic equation, a and are measured by experimental system.

초고속 자기부상열차용 LSM 설계 및 추력 측정 시험

오세영(Se-Young Oh),이창영(Chang-Young Lee),이주(Ju Lee) 대한전기학회 2014 전기학회논문지 Vol.63 No.10

This paper deals with design and thrust force measurement of EMS type LSM for propulsion of the high-speed maglev train. The load of maglev train is calculated, and the design equations of the LSM are presented, and the LSM which is suitable for the operation of short-distance test track is designed. In addition, the finite element analysis is performed to confirm the back-EMF and thrust force characteristics of the LSM designed model. A short length LSM prototype model is manufactured. Finally, the thrust force of the LSM is measured by the method applying dc current to the stator winding instead of three-phase ac current. And the validity of the design and analysis is verified by this measurement.

LSM이 코팅된 고체산화물 연료전지용 Crofer Mesh 집전체 개발

백주열,박석주,이승복,이종원,임탁형,송락현,김광범,신동열,Baek, Joo-Yul,Park, Seok-Joo,Lee, Seung-Bok,Lee, Jong-Won,Lim, Tak-Hyoung,Song, Rak-Hyun,Kim, Kwang-Bum,Shin, Dong-Ryul 한국전기화학회 2010 한국전기화학회지 Vol.13 No.4

A Crofer 22 APU mesh coated with a conductive ceramic material was developed as an alternative cathode current collector to Ag-based materials for solid oxide fuel cells. $(La_{0.80}Sr_{0.20})_{0.98}MnO_3$ (LSM) layer was deposited onto the Crofer mesh using a spray-coating technique, in an attempt to mitigate the degradation of electrical properties due to surface oxidation at high temperatures. The oxidation experiments at $800^{\circ}C$ in air indicated that the areaspecific resistance (ASR) of the LSM-coated Crofer mesh was strongly dependent on the wire diameter and the contact morphology between mesh and cell. In addition, the post-heat-treatment in $H_2/N_2$ resulted in a reduced thickness of Cr-containing oxide scales at the interface between Crofer mesh and LSM layer, leading to a decreased ASR. 본 연구에서는 고체산화물 연료전지의 공기극 집전체로 사용되고 있는 고가의 Ag 소재를 대체하고자 전도성 세라믹이 코팅된 mesh 형태의 Crofer 22 APU 집전체를 개발하였다. 고전자전도성의 $(La_{0.80}Sr_{0.20})_{0.98}MnO_3$ (LSM)을 습식 스프레이법으로 코팅하여 고온 산화 및 전기적 특성의 열화를 억제하고자 하였다. $800^{\circ}C$의 산화 실험 결과에 의하면 LSM이 코팅된 Crofer mesh의 면저항(area-specific resistance)은 mesh의 제작에 사용된 와이어 지름과 접촉 부위의 형상등 실제 접촉점의 수 및 면적을 좌우하는 mesh의 특성에 의해 좌우되었다. 또한 LSM 코팅 후 $H_2/N_2$ 분위기에서의 열처리를 통해 Crofer mesh와 LSM 코팅층 계면에서의 Cr 함유 산화물의 형성을 효과적으로 억제하여 전기적 특성의 열화를 억제할 수 있다.

고체산화물 연료전지의 공기극으로서 La_1-xSr_xMnO₃ 계의 합성 및 특성

이유기,이영기,Lee, You-Kee,Lee, Young-Ki 한국재료학회 2012 한국재료학회지 Vol.22 No.9

$La_{1-x}Sr_xMnO_3$(LSM,$0{\leq}x{\leq}0.5$) powders as the air electrode for solid oxide fuel cell were synthesized by a glycine-nitrate combustion process. The powders were then examined by X-ray diffraction(XRD) and scanning electron microscopy (SEM). The as-formed powders were composed of very fine ash particles linked together in chains. X-ray maps of the LSM powders milled for 1.5 h showed that the metallic elements are homogeneously distributed inside each grain and in the different grains. The powder XRD patterns of the LSM with x < 0.3 showed a rhombohedral phase; the phase changes to the cubic phase at higher compositions($x{\geq}0.3$) calcined in air at $1200^{\circ}C$ for 4 h. Also, the SEM micrographs showed that the average grain size decreases as Sr content increases. Composite air electrodes made of 50/50 vol% of the resulting LSM powders and yttria stabilized zirconia(YSZ) powders were prepared by colloidal deposition technique. The electrodes were studied by ac impedance spectroscopy in order to improve the performance of a solid oxide fuel cell(SOFC). Reproducible impedance spectra were confirmed using the improved cell, which consisted of LSM-YSZ/YSZ. The composite electrode of LSM and YSZ was found to yield a lower cathodic resistivity than that of the non-composite one. Also, the addition of YSZ to the $La_{1-x}Sr_xMnO_3$ ($0.1{\leq}x{\leq}0.2$) electrode led to a pronounced, large decrease in the cathodic resistivity of the LSM-YSZ composite electrodes.

Noah LSM을 이용한 지표 플럭스 산정 및 한반도에서의 적용성 검토

장애선,문희원,황석환,최민하 한국습지학회 2013 한국습지학회지 Vol.15 No.4

지표와 대기간의 에너지 및 수문기상인자들의 교환에 대한 이해는 수자원분야의 연구에 있어서 기초라 할 수 있으며 이 를 위하여 Land Surface Mode(LSM)을 활용한 연구가 활발히 진행되고 있다. Noah Land Surface Model (Noah LSM)은 에 너지 방정식과 물수지 방정식을 기반으로 한 지면모형으로 수문기상인자들에 대한 모의가 가능하다. 국외에는 Noah LSM 을 이용한 다양한 연구사례들이 있으나, 국내에서는 적용사례가 매우 부족하며, 특히 단독으로 Noah LSM을 적용한 사례 는 전무한 실정이다. 본 연구에서는 Noah LSM의 국내 적용성을 평가하기 위해 해남(HFK)과 광릉(GDK) Korea Flux Network (KoFlux)에서 제공하는 자료를 입력자료로 활용하여 모형 결과를 산출하고, 순 복사량, 잠열, 현열의 결과를 관측 자료와 비교·검증하였다. 모형 결과와 관측치를 비교한 결과 회귀분석에서의 상관계수 값이 각 인자 별로 해남은 0.83∼ 099, 광릉은 0.64∼0.99로 신뢰할 만한 수준인 것으로 나타났다.

가토경골에 Polylactic-Glycolic Acid와 Hydroxyapatite 복합물 매식후 알리자린 레드 및 무기질 침착에 의한 신생골 형성에 관한 연구

배성호,천재식,박양호 대한구강악안면병리학회 2003 대한구강악안면병리학회지 Vol.27 No.1

Hydroxyapatite(HA) has been widely used as bone substitutes to rehabilitate bone loss area by new bone formation. But there were some problem of bone formation around HAs due to a little space between HAs embedded in bone loss area. The purpose of this study was to observe morphologically new bone formation around HAs mixed with PLGA block (5.5㎜ in diameter, 4 mm in depth) in Newzealand white rabbit tibia. Before 1 week of sacrification, Alizarin red was injected intraperitoneally into rabbit. At 3 day, 1, 2, 4, 10, 18, 32 weeks, bones with HA as control group(CG)and HA mixed with PLGA block as experimental group (EG)were fixed with 10 % neutral formalin, dehydrated, and embedded with Spurr low viscosity resin. After the specimens were cut by 500 ㎛ with slow diamond wheel saw, these were coated with carbon and examined by REM, LSM and qualifative analysis of calcium and phosphorous deposition were done with EPMA. The obtained results were as follows. 1. Both group showed scattered HA around compact bone under REM and little AZ labelled bone under LSM at 3 days. 2. Both group showed active AZ labelled bone, while EG showed higher Ca(calcium) and P(phosphate) deposition than that of CG at 1 wk. 3. There was decreased AZ labelled bone of both group under LSM. REM of EG showed HA associated with new bone from compact bone, while EPMA features showed similar to Ca and P deposition at 1 wk and EG showed higher than that of CG. 4. REM features of both group showed resorbed HA associated with new bone. There was decreased AZ labelled bone of both group under LSM. EPMA features showed higher Ca and P deposition at 4 wks than that of 2 wks. 5. New bone of both group was well demarcated from compact bone under REM at 10 wks. LSM features showed various AZ labelled bone, but weak AZ labelled than that of CG. 6. LSM features of 14 wks showed discontinuous AZ labelled on osteon formation. EPMA of both group showed increased Ca deposition, while there was higher Ca deposition of EG and similar P deposition to CG. 7. REM featureless of 18 wks in EG showed similar gray color to compact bone. LSM features showed osteon formation with little concentric lamellars. EPMA of both group showed increased Ca deposition, while there was higher Ca and P deposition of EG. 8. New bone was ill demarcated from compact bone and increased otseon formation of REM features at 32 wks. There was little AZ labelled bone. EPMA features showed higher Ca and P deposition of EG than that of compact bone. From the aboving results, there was early active AZ labelled bone of both group within 1-2 weeks and since 18 weeks new bone with active osteon formation was poorly demarcated from compact bone. Calcium deposition of EG was early increased than that of CG deposition since 4 weeks after experiments. It was suggested that EG showed active and rapid new bone formation and similar bone mineralization of compact bone

직접탄소 연료전지용 LSM/GDC 공기극 지지체 제조 및 전기화학 특성 평가

빌랄 아메드,완디와휴디,이승복,송락현,이종원,임탁형,박석주 한국수소및신에너지학회 2013 한국수소 및 신에너지학회논문집 Vol.24 No.3

In this study, successive coating and co-sintering techniques have been used to fabricate LSM/GDC based cathode supported direct carbon fuel cells. The porous LSM/GDC cathode substrate, dense, thin and crack free GDC and ScSZ layers as bi-layer electrolyte, and a porous Ni/ScSZ anode layer was obtained by co-firing at 1400℃. The porous structure of LSM/GDC cathode substrate, after sintering at 1400℃, was obtained due to the presence of GDC phase, which inhibits sintering of LSM because of its higher sintering temperature. The electrochemical characterization of assembled cell was carried out with air as an oxidant and carbon particles in molten carbonate as fuel. The measured open circuit voltages (OCVs) were obtained to be more than 0.99 V,independent of testing temperature. The peak power densities were 116, 195 and 225 mW cm-2 at 750, 800 and 850℃, respectively.