Materials and nano‑structural processes for use in solid oxide fuel cells: a review

Seungyeon Jo,Bharat Sharma,Dae‑Hwan Park,Jea‑ha Myung 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.2

Solid oxide fuel cells (SOFCs) are considered to be the focus of investigation for energy systems owing to their efficiency in converting chemical energy into electrical energy, low carbon footprint, and fuel flexibility. Despite their high performance and durability, SOFCs suffer from critical problems such as carbon coking, agglomeration, and poor redox stability. This review presents research on the development of nanostructures for use in commercial SOFC systems and highlights various aspects of research and applications across the globe. The materials utilized for anodes, electrolytes, and cathodes are discussed and compared, detailing how their respective properties can attain high catalytic activity, conductivity, and stability at low temperatures with the aim of direct application using diverse fuels such as hydrogen, hydrocarbons, and carbon fuels. This review also discusses and compares the various processes used for the synthesis of the electrodes and electrolytes used in SOFCs, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), infiltration, and in situ exsolution, that have gained much attention with a view to increase the active areas, decrease the Ohmic resistance, and reduce the manufacturing price.

Similarity based Deep Neural Networks

Seungyeon Lee,Eunji Jo,Sangheum Hwang,Gyeong Bok Jung,Dohyun Kim 한국지능시스템학회 2021 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.21 No.3

Deep neural networks (DNNs) have recently attracted attention in various areas. Their hierarchical architecture is used to model complex nonlinear relationships in high-dimensional data. DNNs generally require large numbers of data to train millions of parameters. However, the training of a DNN with a small number of high-dimensional data can result in an overfitting. To alleviate this problem, we propose a similarity-based DNN that can effectively reduce the dimensionality of the data. The proposed method utilizes a kernel function to calculate pairwise similarities of observations as input, and the nonlinearity based on the similarities is then explored using a DNN. Experiment results show that the proposed method performs effectively regardless of the dataset used, implying that it can be applied as an alternative when learning a small number of high-dimensional data.

Optical Properties of EVA Films Including V570 for Transparent Luminescent Solar Concentrator

Kukhyun Jo,Seungyeon Hong,Hyo Jung Kim 한국진공학회(ASCT) 2020 Applied Science and Convergence Technology Vol.29 No.1

We fabricated a transparent luminescent solar concentrator (LSC) film using Lumogen F Violet 570 (V570) luminescent molecules and polyethylene-co-vinylaccetate (EVA) polymer. The transparent LSC was produced by a solution process (Doctor Blade coating) using a tetrahydrofuran solvent. We measured physical properties such as thickness, absorption efficiency, emission efficiency, and photocurrent characteristics of the LSC films. We also discuss the physical properties of the LSC films by observing the crystallinity and surface morphology using X-ray diffraction and atomic force microscopy. During the formation of LSC films, V570 molecules did not induce macroscopic changes, but had a significant effect on nanoscale morphology, i.e., surface roughness. In addition, changes in the light scattering characteristics were observed when the V570 concentration increased, which was found by X-ray diffraction to be related to the formation of V570 crystals, not EVA crystals. The light scattering and surface roughness of a film could be improved through heat treatment. As a result, we obtained ~ 1.3 times larger photocurrent in thermally treated LSC films.

소셜 네트워크에서의 사용자관계 시각화 방안

양승연 ( Seungyeon Yang ),조현성 ( Hyunsung Jo ),이천희 ( Chunhee Lee ),박석천 ( Seok-cheon Park ) 한국정보처리학회 2013 한국정보처리학회 학술대회논문집 Vol.20 No.2

데이터 시각화 기술을 이용하여 데이터에 대한 접근성과 이해도를 높여 사용자가 빅데이터 가치를 효율적으로 활용할 수 있도록 소셜 네트워크에서의 사용자 관계 시각화 기술에 대해 연구하였다. 본 논문은 소셜 네트워크의 사용자관계를 시각화하기 위해 소셜 네트워크 데이터 스트리밍 기술, 동적 애니메이션 적용을 위한 시각화 기술 그리고 사용자 관계를 분석하기 위한 데이터마이닝 기술을 적용하여 소셜 네트워크 사용자들 간의 관계를 본인 중심으로 시각화하는 방안을 제시하였다.

잠재적 교육과정의 관점에서 본 북한의 외국어로서의 조선어 교재 연구 : 시대에 따른 서술 방식의 변화를 중심으로

이승연(Lee Seungyeon),조현준(Jo Hyeonjun),윤명식(Yoon Myungsik),전혜리(Jeon Hyeri) 한국문화융합학회 2020 문화와 융합 Vol.42 No.12

본고에서는 잠재적 교육과정의 관점에서 조선어 교재의 서술 방식의 변화에 주목하였다. 구체적으로 <조선말회화(류학생용)>(1984), <혼자서 배울수 있는 조선말>(2015, 2017), <쉽게 배울수 있는 조선어>(2019)의 세 교재를 바탕으로 교재에 나타나는 서술 방향을 살펴보았다. 세 교재에서 공통적으로 언급하고 있는 ‘시간’, ‘장소’, ‘표현’의 예문을 살펴본 결과는 다음과 같다. 첫째, 요일과 날짜, 절기 등의 시간을 다룬 과에서는 <1984>에서 흔하게 나타나던 지도자 일가에 대한 찬양이나 북한 체제의 안정성을 강조하고 드높이는 표현이 사라지는 경향을 보였다. 둘째, 장소를 다룬 주제에서도 시대가 변화함에 따라 북한의 체제를 강조하고 칭송하던 표현들이 감소한 것을 확인하였다. 셋째, <1984>에서 사용된 주변국에 대한 주관적인 표현, 모든 주제에서의 북한 정권의 찬양과 추대 등은 2010년대에서는 드러나지 않았음을 확인하였다. 1980년대에는 북한의 주체사상 및 북한 정권의 찬양과 추대가 많은 비중을 차지한 반면, 2010년대의 교재에서는 사실적인 정보를 서술함으로써 상대적으로 지도자 일가에 대한 찬양이나 북한 체제의 안정성을 강조하고 드높이는 표현이 사라지는 경향을 보였다. This paper took notice of the changes in the narrative styles of cho-sŏn-ŏ textbooks from the perspective of them being a potential curriculum. Concretely, the directions of narrations appearing in these textbooks were examined based on three textbooks, namely <cho-sŏn- mal-hoe-hwa(lyu-hak-saeng-yong)>(1984), <hon-cha-sŏ pae-ul su iss-nŭn cho-sŏn-mal>(2015, 2017), and <swip-ke pae-ul-su iss-nŭn cho-sŏn-ŏ> (2019). The results of the examination of example sentences for “time,” “place,” and “expression,” which are commonly mentioned in the three textbooks are as follows. First, in the lessons dealing with time, such as the days of week, dates, and seasons, expressions that praised the leader, or emphasized and praised the stability of the North Korean system were observed to disappear. Second, the expressions that emphasized and praised the North Korean system in subjects that dealt with places were observed to decrease as the times changed. Third, it was identified that expressions for subjective self-reliance ideology that had been used to undermine the neighboring countries until <1984>, and expressions in the praise of and support for the North Korean regime in all subjects were no longer used in the 2010s. While the praise of and support for the North Korean self-reliance ideology and the North Korean regime accounted for large portions of textbooks in the 1980s, the textbooks in the 2010s described only factual information. As a result, the expressions that praised the family of the leader or emphasized and praised the stability of the North Korean system showed a tendency of disappearing from textbooks.

Feasibility study of shutter scan acquisition for region of interest ( ROI ) digital tomosynthesis

Kim, Dohyeon,Jo, Byungdu,Lee, Donghoon,Lee, Haenghwa,Choi, Sunghoon,Kim, Hyemi,Chao, Zhen,Choi, Seungyeon,Kim, Hee‐,Joung unknown 2018 Journal of applied clinical medical physics Vol.19 No.3

<P><B>Abstract</B></P><P>Dose reduction techniques have been studied in medical imaging. We propose shutter scan acquisition for region of interest (ROI) imaging to reduce the patient exposure dose received from a digital tomosynthesis system. A prototype chest digital tomosynthesis (CDT) system (LISTEM, Wonju, Korea) and the LUNGMAN phantom (Kyoto Kagaku, Japan) with lung nodules 8, 10, and 12 mm in size were used for this study. A total of 41 projections with shutter scan acquisition consisted of 21 truncated projections and 20 non‐truncated projections. For comparison, 41 projections using conventional full view scan acquisition were also acquired. Truncated projections obtained by shutter scan acquisition were corrected by proposed image processing procedure to remove the truncation artifacts. The image quality was evaluated using the contrast to noise ratio (CNR), coefficient of variation (COV), and figure of merit (FOM). We measured the dose area product (DAP) value to verify the dose reduction using shutter scan acquisition. The ROI of the reconstructed image from shutter scan acquisition showed enhanced contrast. The results showed that CNR values of 8 and 12 mm lung nodules increased by 6.38% and 21.21%, respectively, and the CNR value of 10 mm lung nodule decreased by 3.63%. COV values of the lung nodules were lower in a shutter scan image than in a full view scan image. FOM values of 8, 10, and 12 mm lung nodules increased by 3.06, 2.25, and 2.33 times, respectively. This study compared the proposed shutter scan and conventional full view scan acquisition. In conclusion, using a shutter scan acquisition method resulted in enhanced contrast images within the ROI and higher FOM values. The patient exposure dose of the proposed shutter scan acquisition method can be reduced by limiting the field of view (FOV) to focus on the ROI.</P>

3D CNN을 이용한 미래 프레임 예측을 통한 비디오 이상 감지

조영완(Youngwan Jo),조준흠(Junheum Cho),최승연(Seungyeon Choi),박상현(Sanghyun Park) 한국정보과학회 2022 한국정보과학회 학술발표논문집 Vol.2022 No.06

Electrochemical characteristics of La0.8Sr0.2MnO3 (LSM)–scandia-stabilized zirconia (ScSZ) composite cathode

Jeong Hyeongwon,SHARMA BHARAT,Jo Seungyeon,Kim Yo Han,Myung Jae-Ha 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.4

LSM–ScSZ composite electrode for solid oxide fuel cells (SOFCs) cathode application has been investigated for its oxy- gen reduction reaction (ORR) performance. The composition and sintering temperature of LSM–ScSZ were controlled to determine the optimized microstructure of the LSM–ScSZ electrode layer, considering its length of triple-phase boundaries (TPBs), and transfer of oxygen for cathode reaction. The electrochemical impedance spectroscopy (EIS) method with an equivalent circuit model was introduced to characterize the specifi c impedance of each sample. The results demonstrated that volume ratio of LSM:ScSZ = 6:4 sintered at 1200 °C sample showed the lowest total impedance of 0.031 Ω  cm 2 at 900 °C operating temperature, compensating slightly increased high-frequency impedance ( R HF ) of TPBs region with drastically improved the active surface of LSM area and their connectivity, which correspond to middle- and low-frequency impedance ( R MF and R LF ) value, respectively. This study suggests an integrated approach in the development of the SOFCs cathode design with the proper compositional ratio and sintering process via using commercial materials.

Marine Afforestation Basic Core Technology Development using Macroalgal Spore Encapsulation

Jihyun PARK,Sohee KIM,Seungyeon JO,Gayoung KIM,Chaebin PARK,Seungah LEE,Yuhyun SEOL,Dong Soo HWANG 한국생물공학회 2018 한국생물공학회 학술대회 Vol.2018 No.10

문항반응이론을 적용한 직원몰입척도 타당도 검증 : Rasch 측정모형을 중심으로

홍아정(Ahjeong Hong),조윤성(Yunseong Jo),이승연(Seungyeon Lee) 대한경영학회 2020 大韓經營學會誌 Vol.33 No.4