Performance of SOFC coupled with n-C₄H₁₀ autothermal reformer: Carbon deposition and development of anode structure

Bae, Gyujong,Bae, Joongmyeon,Kim-Lohsoontorn, Pattaraporn,Jeong, Jihoon Elsevier 2010 International journal of hydrogen energy Vol.35 No.22

<P><B>Abstract</B></P><P>The performance deterioration of solid oxide fuel cells (SOFCs, Nickel-Yttria stabilized zirconia (Ni-YSZ)/YSZ/lanthanum doped strontium manganite-YSZ (LSM–YSZ)) coupled with n–C<SUB>4</SUB>H<SUB>10</SUB> steam reformers (SR), autothermal reformers (ATR), or catalytic partial oxidation reformers (CPOX) was examined using an integrated system of a micro-reactor reformer and SOFC unit. The terminal voltage rapidly degraded in CPOX-driven SOFC (oxygen to carbon ratio (OCR) = 0.5) while it was fairly stable for SR-driven SOFC (steam to carbon ratio (SCR) = 2) over 250 h. For ATR-driven SOFC at near the thermoneutral point (OCR = 0.5 and steam to carbon ration (SCR) = 1.3), significant deterioration of the terminal voltage was observed in 100 h of operation. The main precursors of carbon deposition on the SOFC were identified by reformate gas analysis during the tests. In this study, we reveal that the carbon deposition on the SOFC anode can be affected by not only lower-order hydrocarbons (C<SUB>1</SUB>∼C<SUB>4</SUB>), but also by the CO/H<SUB>2</SUB> gas mixture. The change in electrical conductivity of the Ni-YSZ cermet used for the SOFC anode was investigated under different gas mixtures. To investigate the propensity for carbon deposition by each carbon-containing gas mixture, we defined the ratios of steam to specific carbon (C<SUB>1</SUB>∼C<SUB>4</SUB> lower-order hydrocarbons and CO) in the reformate gas (SSCR, steam to specific carbon ratio). To inhibit carbon deposition on SOFC anode, the SSCR must be sufficiently high. However, the reformer operates near its maximum efficiency at low SSCR value and the higher the SSCR value, the lower the open circuit voltage and operating power density due to Nernst potential. In this study, a metal-foam supported SOFC single cell (Ni-YSZ/YSZ/Gd-doped ceria (CGO) buffer layer/lanthanum strontium cobalt ferrite-samarium doped ceria (LSCF-SDC)), impregnated with catalyst was designed; this novel SOFC was then examined for operation at a low SSCR value of the autothermal reformer conditions (near maximum efficiency of n-C<SUB>4</SUB>H<SUB>10</SUB> reformer and thermal neutral point, SSCR = 0.5, OCR = 0.5 and SCR = 1.3). The voltage for the metal-foam supported SOFC impregnated with 0.5 wt% Rh/CGO remained at a nearly constant value, around 0.8 V, for 200 h under a constant temperature of 750 °C and current load of 250 mA cm<SUP>−2</SUP>.</P>

Detection of Citrus Canker using Hyperspectral Imager of Low-altitude Unmanned Aerial Vehicle

( Hyungjin Bae ),( Jihoon Bae ),( Byoung-kwan Cho ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

Citrus trees infected with Citrus canker suffer from low vigor and poor quality of fruit with less yield. This study was aimed to develop a monitoring system for citrus trees infected with canker using a hyperspectral imager mounted on a low-altitude Unmanned Aerial Vehicle (UAV). Hyperspectral Vis/NIR images were acquired for the infected and sound citrus trees in a citrus experiment station at National Horticultural Research Institute in Jeju Island, South Korea. Radiometric calibration was performed for the precise measurements of radiance of target objects. With simple image processing algorithm soil background could be deleted from the hyperspectral images. The normalized difference vegetation index (NDVI) was calculated from the preprocessed hyperspectral images as well as multi-waveband combinations for discriminating infected canopy from sound one. Among the classification methods the partial least squares discriminant analysis (PLS-DA) showed the best performance with the classification accuracy of 83.3%. The result shows that hyperspectral imaging technique with UAV has potential to monitor citrus trees infected with citrus canker in the farm.

그래프 신경망 기반 슈퍼픽셀 이미지분류

배지훈(Jihoon Bae),당탄부(Dang Thanh Vu),김진영(JinYoung Kim) 한국통신학회 2022 한국통신학회 학술대회논문집 Vol.2022 No.2

본 논문은 Graph Neural Network(GNN)기반 이미지 분류(Image Classification)방법을 제시하고 그 결과를 나타낸다. 우리는 먼저 SLIC 알고리즘을 사용하여 원본 이미지를 슈퍼픽셀 이미지로 변환한다. 그리고 각 슈퍼픽셀 영역을 노드로, 주변픽셀들을 엣지로 연결시키어 그래프를 생성하는 Region Adjacency Graph(RAG) 알고리즘을 적용한 뒤 GNN에 통과시켜 이미지 분류를 수행한다. 우리는 Graph Attention Network(GAT)모델을 사용하여 MNIST, FashionMNIST, CIFAR10 데이터셋으로 실험하였고, 결과분석 및 CGAT(Convolution Graph Attention Network)를 새로 제안하며 발전방향을 제시한다.

무인항공기(UAV) 및 다분광 영상 시스템(Multispectral Imager)을 이용한 온주밀감 나무의 비 생물적 스트레스 모니터링

배지훈 ( Jihoon Bae ),배형진 ( Hyungjin Bae ),조병관 ( Byoung-kwan Cho ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.2

온주밀감은 한국에서 가장 많이 소비되는 감귤품종으로, 높은 수요를 충족시키기 위하여 생산량을 적절히 관리해야 한다. 그러나 현행되는 재배기술은 스트레스에 노출된 작물에 대해 정시 처방을 제공하기 힘든 수작업에 의존하고 있다. UAV (Unmanned Aerial Vehicle) 를 활용한 원격 탐사 기술은 이에 대한 효과적인 대안이 될 수 있다. 높은 해상도로 세밀한 관측이 가능한 저고도 UAV 기반 원격 탐사 기술은 정밀농업 분야에 유용한 정보를 제공할 수 있다. Hyperspectral / Multispectral 이미징 기술은 대상의 물리화학적 특성을 측정하는 것에 신뢰할만한 성능을 보였다. 특히 소수의 파장만을 이용하는 Multispectral 이미징은 Hyperspectral 이미징에 비해 분석 속도가 빠르고 비용이 저렴하다는 장점이 있다. 이에 본 연구에서는 UAV 및 Multispectral imager 로 구성된 원격 탐사 시스템을 이용하여 온주밀감 나무의 비 생물적 스트레스를 모니터링 하고자 하였다. 정상 및 수분, 질소 스트레스에 노출된 작물에 대한 Multispectral Vis/NIR 이미지를 획득하였다. 이후 획득된 이미지에 대한 정사 영상을 추출하고, 광조건 및 대기조건 변화에 의한 오차를 최소화하고자 방사보정을 적용하였다. 온주밀감 나무의 스트레스 증상을 측정하기 위해 다양한 전처리와 함께 부분최소제곱 판별분석(PLS-DA) 및 NDVI 식생지수 분석을 수행한 결과, 스트레스에 노출된 감귤나무의 분류에 대해 합리적인 정확도의 결과를 얻을 수 있었다. 이는 Multispectralimager 및 UAV 를 이용한 원격 탐사 시스템이 온주밀감 나무의 신속하고 비파괴적인 스트레스 모니터링에 좋은 가능성을 가지고 있음을 보여주었다.

Fabrication of a thin-layer solid optical tissue phantom by a spin-coating method: pilot study.

Bae, Yunjin,Son, Taeyoon,Park, Jihoon,Jung, Byungjo SPIE--the International Society for Optical Engine 2013 Journal of biomedical optics Vol.18 No.2

<P>Solid optical tissue phantoms (OTPs) have been widely used for many purposes. This study introduces a spin-coating method (SCM) to fabricate a thin-layer solid OTP (TSOTP) with epidermal thickness. TSOTPs are fabricated by controlling the spin speed (250 to 2500 rpm), absorber concentration (0.2% to 1.0%), and the number of layers. The results show that the thicknesses of the TSOTPs are homogeneous in the region of interest. The one-layer TSOTP achieves maximum and minimum thicknesses of 650.28 μm (250 rpm) and 5.10.17 μm (2500 rpm), respectively, decreasing exponentially as a function of the spin speed. The thicknesses of the multilayer TSOTPs increases as a function of the number of layers and are correlated strongly with the spin speed (R20.95). The concentration of the OTP mixture does not directly affect the thickness of the TSOTP; however, the absorption coefficients exponentially increase as a function of absorber concentration (R20.98). These results suggest that the SCM can be used to fabricate homogeneous TSOTPs with various thicknesses by controlling the spin speed and number of layers. Finally, a double-layer OTP that combines epidermal TSOTP and dermal OTP is manufactured as a preliminary study to investigate the practical feasibility of TSOTPs.</P>

VERI-PEN : DIGITAL PEN SYSTEM FOR AUTHENTICATING DIGITAL AUTHORSHIP

Jihoon Suh,Sang Min Bae 한국디자인학회 2015 한국디자인학회 학술발표대회 논문집 Vol.2015 No.10

Living in the Internet age, we have high threats of data leakage, identity theft, and inconvenience over authenticating ourselves online. Simple digital identification is crucial in the digital realm. Veri-Pen is a smart pen that provides alternative digital identification and authorship. Through dual authentication using fingerprint scanner and signature recognition, it provides enhanced security yet simple verification procedure for authentication and legitimacy of authorship. Together with cloud system of authorship authentication, Veri-Pen aims to link written materials to the corresponding authors.

원자로냉각재펌프의 저널베어링 마모 특성 평가

이지훈(Jihoon Lee),배병건(Byeonggeon Bae),김태균(Tae-Kyoon Kim) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.6

최소 극단치 분포를 이용한 자동차 도어 래치의 아이링 모델 가속 수명 예측을 위한 회귀 분석 방법 연구

손지훈(Jihoon Son),심재술(Jaesool Shim),배영화(Younghwa Bae),김우엽(Wooyoub Kim),김정재(Jungjae Kim),김청산(Chungsan Kim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

Door latch of automobile is a necessary component for automobile passengers which performs not only Open/Close but also Lock/Unlock. Also, door latch is strongly controlled by automobile safety regulation and requires high reliability. Door latch is exposed to wide range of temperatures due to climate and repetitive load of motor is applied to gears. Therefore, estimation of cumulative failure rate and lifespan under stress condition is necessary. Therefore, in this study, the theoretical Erying model accelerated life anaylsis, which is the zero failure test method, is proposed using Weibull distribution theory under the log relationship between the Weibull distribution and Minimum extreme value distribution. This research investigated various parts inside of latch which is defined failure mechanisms and factors using step of reliability analysis. Also, HALT was performed for acceleration level decision. Failure mechanism of door latch is gear damage due to high/low temperature and repetitive load and applied temperature (-45℃ ~ 100℃) and load (18V, 24V) conditions to accelerate failure. Common shape parameter and scale parameters were derived as a result of multi-levels, factors ALT. By applying Eyring model, lifespan under specific temperature and load condition is estimated. Also, the theoretical and experimental values predicted by regression analysis using the minimum extreme value distribution under the log relationship with the weibull distribution were compared. As a result, it was confirmed that there was no error in the two values, and it was possible to theoretically predict the multifactor acceleration life.

최소 극단치 분포를 이용한 자동차 도어 래치의 아이링 모델 가속 수명 예측을 위한 회귀 분석 방법 연구

손지훈(Jihoon Son),심재술(Jaesool Shim),배영화(Younghwa Bae),김우엽(Wooyoub Kim),김정재(Jungjae Kim),김청산(Chungsan Kim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

Door latch of automobile is a necessary component for automobile passengers which performs not only Open/Close but also Lock/Unlock. Also, door latch is strongly controlled by automobile safety regulation and requires high reliability. Door latch is exposed to wide range of temperatures due to climate and repetitive load of motor is applied to gears. Therefore, estimation of cumulative failure rate and lifespan under stress condition is necessary. Therefore, in this study, the theoretical Erying model accelerated life anaylsis, which is the zero failure test method, is proposed using Weibull distribution theory under the log relationship between the Weibull distribution and Minimum extreme value distribution. This research investigated various parts inside of latch which is defined failure mechanisms and factors using step of reliability analysis. Also, HALT was performed for acceleration level decision. Failure mechanism of door latch is gear damage due to high/low temperature and repetitive load and applied temperature (-45℃ ~ 100℃) and load (18V, 24V) conditions to accelerate failure. Common shape parameter and scale parameters were derived as a result of multi-levels, factors ALT. By applying Eyring model, lifespan under specific temperature and load condition is estimated. Also, the theoretical and experimental values predicted by regression analysis using the minimum extreme value distribution under the log relationship with the weibull distribution were compared. As a result, it was confirmed that there was no error in the two values, and it was possible to theoretically predict the multifactor acceleration life.

모핑 항공기를 위한 계층적 비행제어시스템

이지훈(Jihoon Lee),정승윤(Seungyun Jung),김성훈(Seong-hun Kim),이한나(Hanna Lee),김유단(Yondan Kim),배재성(Jaesung Bae) 항공우주시스템공학회 2018 항공우주시스템공학회 학술대회 발표집 Vol.2018 No.11