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Characterization of the Laser Scribing Process of HIT Cells for a Photovoltaic Shingled Module
Jee Hongsub,Lee Jaehyeong,Moon Daehan,Park Min-Joon,Jeong Taewung,Jeong Hyoungjin,Jeong Chaehwan 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.11
Shingled string technology can be used to maximize the output power of photovoltaic modules. The maximum power (Pmax) of a shingled photovoltaic module can be increased by using a bifacial heterojunction with an intrinsic thin layer (HIT) of cells. To fabricate the shingled strings for a high power module, we first cut 6-inch solar cells by laser scribing while minimizing cutting loss. Unlike standard crystalline silicon (c-Si) solar cells, the structure of bifacial HIT solar cells is weak under thermal effect, so an optimal scribing condition had to be found. After laser scribing processes had been optimized, Pmax was increased by 0.02W for each separated solar cells when we using an ultraviolet (UV) laser compared to the green laser, and a UV cut shingled string of HIT cell was demonstrated for the first time.
기계학습 기법에 따른 KOMPSAT-3A 시가화 영상 분류 - 서울시 양재 지역을 중심으로 -
윤형진 ( Hyoungjin Youn ),정종철 ( Jongchul Jeong ) 대한원격탐사학회 2020 大韓遠隔探査學會誌 Vol.36 No.6
시가화 지역 토지피복분류는 도시계획 및 관리에 활용된다. 따라서, 시가화 지역에 대한 분류 정확도 향상 연구는 중요하다고 할 수 있다. 본 연구에서는 고해상도 위성영상인 KOMPSAT-3A을 기계학습 중 Support Vector Machine(SVM)과 Artificial Neural Network(ANN)을 기반으로 시가화지역 분류를 진행하였다. 훈련 데이터 구축과정에서 25 m 격자를 기반으로 훈련 지역을 구분하여 영상을 학습하였으며, 학습된 모델을 활용하여 테스트 지역을 분류하였다. 검증과정에서 250개의GTP를 활용하여 오차 행렬을 통한 결과를 제시하였다. SVM 4가지 기법과 ANN 2가지 기법 중 SVM Polynomial Model이 가장 높은 정확도인 86%를 나타냈다. Ground Truth Points(GTP)를 활용하여 두 개의 모델을 비교하는 과정에서, SVM 모델은 전체적으로 ANN 모델보다 효과적으로 KOMPSAT-3A 영상을 분류하였다. 건물, 도로, 식생, 나대지 4가지 클래스 분류 중 건물이 가장 낮은 분류 정확도를 보여주었으며, 이는 고층건물에 따른 건물 그림자에 의한 오분류가 주요 원인으로 나타났다. Urban land cover classification is role in urban planning and management. So, it’s important to improve classification accuracy on urban location. In this paper, machine learning model, Support Vector Machine (SVM) and Artificial Neural Network (ANN) are proposed for urban land cover classification based on high resolution satellite imagery (KOMPSAT-3A). Satellite image was trained based on 25 m rectangle grid to create training data, and training models used for classifying test area. During the validation process, we presented confusion matrix for each result with 250 Ground Truth Points (GTP). Of the four SVM kernels and the two activation functions ANN, the SVM Polynomial kernel model had the highest accuracy of 86%. In the process of comparing the SVM and ANN using GTP, the SVM model was more effective than the ANN model for KOMPSAT-3A classification. Among the four classes (building, road, vegetation, and bare-soil), building class showed the lowest classification accuracy due to the shadow caused by the high rise building.
정기연(Kiyeon Jeong),김덕현(Dukhyun Kim),이충희(Choonghee Lee),이형진(Hyoungjin Lee) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12
고체추진기관의 연속적인 추력조절에 적합한 핀틀 노즐에 대한 수치해석적 연구를 수행하였다. 핀틀 노즐은 핀틀과 노즐의 직경비에 따라 관통형과 비관통형으로 나뉘며, 본 연구에서는 핀틀 직경이 노즐 직경보다 큰 비관통형을 선택하였다. 노즐은 초음속 출구조건을 가지며 직선형인 conical과 곡선형인 bell 노즐을 비교하였다. 핀틀의 형상은 면적 변화부분이 1차 기울기 값을 가지는 형상을 선택하여 노즐 목의 변화가 선형적으로 변하도록 설계하였다. 수치해석은 STAR-CCM+ 10.06을 이용하여 수행하였으며 노즐과 핀틀의 형상 변화에 대한 노즐 내 유동변화, 추력의 변화를 비교하였다. Numerical simulations have been performed to investigate the proper nozzle shape for thrust control of pintle nozzle. The type of pintle nozzle was divided to through-type and non through-type from the ratio of pintle and nozzle diameter. the designed nozzle has supersonic exit condition, diverging section of nozzle has straight(conical nozzle) and curve(bell nozzle) shape respectively. the pintle shape was designed at negative first order gradient to linearize change of nozzle throat. STAR-CCM+ 10.06 was used to analysis the flow characteristics in the nozzle and variation of thrust.
Lee, Junsung,Lee, Hyoungjin,Goh, Unbyeol,Kim, Jiyoung,Jeong, Moonkyoung,Lee, Jean,Park, Ji-Ho American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.11
<P>Engineering of extracellular vesicles (EVs) without affecting biological functions remains a challenge, limiting the broad applications of EVs in biomedicine. Here, we report a method to equip EVs with various functional agents, including fluorophores, drugs, lipids, and bio-orthogonal chemicals, in an efficient and controlled manner by engineering parental cells with membrane fusogenic liposomes, while keeping the EVs intact. As a demonstration of how this method can be applied, we prepared EVs containing azide-lipids, and conjugated them with targeting peptides using copper-free click chemistry to enhance targeting efficacy to cancer cells. We believe that this liposome-based cellular engineering method will find utility in studying the biological roles of EVs and delivering therapeutic agents through their innate pathway.</P>
Lee, Junsung,Kim, Jiyoung,Jeong, Moonkyoung,Lee, Hyoungjin,Goh, Unbyeol,Kim, Hyaeyeong,Kim, Byungji,Park, Ji-Ho American Chemical Society 2015 NANO LETTERS Vol.15 No.5
<P>Natural membrane vesicles (MVs) derived from various types of cells play an essential role in transporting biological materials between cells. Here, we show that exogenous compounds are packaged in the MVs by engineering the parental cells via liposomes, and the MVs mediate autonomous intercellular migration of the compounds through multiple cancer cell layers. Hydrophobic compounds delivered selectively to the plasma membrane of cancer cells using synthetic membrane fusogenic liposomes were efficiently incorporated into the membrane of MVs secreted from the cells and then transferred to neighboring cells via the MVs. This liposome-mediated MV engineering strategy allowed hydrophobic photosensitizers to significantly penetrate both spheroids and in vivo tumors, thereby enhancing the therapeutic efficacy. These results suggest that innate biological transport systems can be in situ engineered via synthetic liposomes to guide the penetration of chemotherapeutics across challenging tissue barriers in solid tumors.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2015/nalefd.2015.15.issue-5/nl5047494/production/images/medium/nl-2014-047494_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl5047494'>ACS Electronic Supporting Info</A></P>
높은 수율의 임계값 스위칭 특성을 위한 CMOS 호환 전극을 갖는 NbO<SUB>x</SUB> 층에서 산화물 장벽의 역할
최현식(Hyeonsik Choi),김윤서(Yunsur Kim),박형진(Hyoungjin Park),정지애(Jiae Jeong),우지용(Jiyong Woo) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.11
This study shows how the threshold switching (TS) characteristics of a NbOx layer with noninert W electrodes can be improved by introducing an oxide barrier. The ~10-nm-thick NbOx layer exhibits TS, which is known to originate from NbO₂, after electroforming. However, through X-ray photoelectron spectroscopy, a Nb₂O<SUB>5</SUB> layer, which is known to cause resistive memory switching, is formed mainly at the top interface as well. This results in a worsening TS yield. Therefore, thin oxides were introduced to improve the TS behavior and systematically investigate the role of the oxide barrier by considering their location and material properties. The barrier inserted at the bottom interface makes the formation of NbO₂ difficult, preventing TS. When the barrier was introduced at the top interface, the unwanted Nb₂O<SUB>5</SUB> created through reaction with the W electrode can be mitigated, promoting the occurrence of TS. Note that when an AL₂O₃ (or HfO₂) barrier is used, which prefers to scavenge (or provide) oxygen from (or to) the NbOx, a dielectric (or weak TS) behavior is shown. As a result, excellent cell-to-cell uniformity of the TS is achieved in the ZrO₂/NbOx stack, which not only prevents the formation of Nb₂O<SUB>5</SUB> but also stabilizes the NbO₂ in the NbOx layer. Through examining the temperature dependence of the TS obtained from the W/NbOx/W and W/ZrO₂/NbOx/W stacks, it was found that the suppression of the Nb₂O<SUB>5</SUB> at the top interface is indirectly shown as a strengthened Schottky barrier from an electrical measurement perspective.