Randomized path planning on vector fields

Ko, Inyoung,Kim, Beobkyoon,Park, Frank Chongwoo SAGE Publications 2014 The International journal of robotics research Vol.33 No.13

<P>Given a vector field defined on a robot’s configuration space, in which the vector field represents the system drift, e.g. a wind velocity field, water current flow, or gradient field for some potential function, we present a randomized path planning algorithm for reaching a desired goal configuration. Taking the premise that moving against the vector field requires greater control effort, and that minimizing the control effort is both physically meaningful and desirable, we propose an integral functional for control effort, called the <B>upstream criterion</B>, that measures the extent to which a path goes against the given vector field. The integrand of the upstream criterion is then used to construct a rapidly exploring random tree (RRT) in the configuration space, in a way such that random nodes are generated with an a priori specified bias that favors directions indicated by the vector field. The resulting planning algorithm produces better quality paths while preserving many of the desirable features of RRT-based planning, e.g. the Voronoi bias property, computational efficiency, algorithmic simplicity, and straightforward extension to constrained and nonholonomic problems. Extensive numerical experiments demonstrate the advantages of our algorithm vis-à-vis existing optimality criterion-based planning algorithms.</P>

High-performance Planar Perovskite Solar Cells based on Low-temperature Processed Nb-doped TiO₂ Electron Selective Layer

Inyoung Jeong(정인영),Min Jae Ko(고민재) 한국신재생에너지학회 2018 한국신재생에너지학회 학술대회논문집 Vol.2018 No.11

모폴로지를 이용한 비디오 영상에서의 자동 문자 추출

장인영(InYoung Jang),고병철(ByoungChul Ko),김길천(KilChun Kim),변혜란(HyeRan Byun) 한국정보과학회 2001 한국정보과학회 학술발표논문집 Vol.28 No.2Ⅱ

본 논문에서는 뉴스 비디오의 정지 영상에서 뉴스 자막과 배경 문자를 추출하기 위한 새로운 방법을 제안한다. 본 논문에서는 일차적으로 입력 컬러 영상을 그레이 영상으로 변환한 후 입력 영상의 명암 대비를 강화시키기 위해 명암 대비 스트레칭을 적용한다. 이후 명암 대비 스트레칭된 영상의 분할을 위해 적응적 임계값을 적용하고 다음 단계에서 문자와 유사한 영역들을 적당한 크기의 structuring element를 이용하여 제거하는 1차 하부 단계와 모폴로지 녹임(erosion)을 적용한 영상과 모폴로지(열림닫힘[OpenCoose]+닫힘열림[CloseOpen])/2가 적용된 영상 사이의 차이 영상을 구하는 2차 하부 단계를 적용 시킨다. 마지막 단계에서 각 후보 영역들 중 실제 자막 영역을 추출해내기 위해, 후보 문자 영역의 화소수 비율과 외곽선의 화소수의 비율, 그리고 장축과 단축간의 비율 등에 대해 필터링을 적용한다. 본 논문에서는 임의의 300개의 뉴스영상을 입력 값으로 실험한 결과 93.6%의 우수한 인식률을 얻을 수 있었다. 또한 본 논문에서 제안한 방법은 structuring element의 크기 조절을 통해 크기가 다른 다양한 이미지에서도 좋은 성능을 거둘 수 있다.

형태학과 문자의 모양을 이용한 뉴스 비디오에서의 자동 문자 추출

장인영(InYoung Jang),고병철(ByoungChul Ko),김길천(KilCheon Kim),변혜란(HyeRan Byun) 한국정보과학회 2002 정보과학회 컴퓨팅의 실제 논문지 Vol.8 No.4

최근 들어 인터넷 사용의 증가와 더불어 디지털 비디오의 수요 또한 급격히 증가하고 있는 추세이다. 따라서 디지털 비디오 데이타베이스의 인덱싱을 위한 자동화된 도구가 필요하게 되었다. 디지털 비디오 영상에 인위적으로 삽입되어진 문자와 배경에 자연적으로 포함되어진 배경문자 등의 문자 정보는 이러한 비디오 인덱싱을 위한 중요한 단서가 되어질 수 있다. 본 논문에서는 뉴스 비디오의 정지 영상에서 뉴스 자막과 배경 문자를 추출하기 위한 새로운 방법을 제안한다. 제안된 알고리즘은 다음과 같이 세 단계로 구성된다. 첫 번째 전처리 단계에서는 입력된 컬러 영상을 명도 영상으로 변환하고, 히스토그램 스트레칭을 적용하여 영상의 수준을 향상시킨다. 이 영상에 적응적 임계값 추출에 의한 분할 방법을 수정 적용하여 영상을 분할한다. 두 번째 단계에서는 적응적 이진화가 적용된 결과 영상에 모폴로지 연산을 적절하게 사용하여, 우선 문자 영역은 아니면서 문자로 판단되기 쉬운 양의 오류(false-positive) 요소들이 강조되어 남아있는 영상을 만든다. 또한, 변형된 이진화 결과 영상에 모폴로지 연산과 본 논문에서 제안한 기하학적 보정(Geo-correction) 필터링 방법을 적용하여 문자와 문자로 판단되기 쉬운 요소들이 모두 강조되어 남아있는 영상을 만든다. 이 두 영상의 차를 구함으로서 찾고자 하는 문자 요소들이 주로 남고, 문자가 아닌 문자처럼 보이는 오류 요소들은 대부분 제거된 결과 영상을 만든다. 문자로 판단되는 양의 오류 영역들을 남기는데 사용된 모폴로지 연산은 3x3 크기의 구조 요소를 갖는 열림과 (열림닫힘+닫힘열림)/2 이며, 문자 및 문자와 유사한 요소들을 남기는데 사용된 연산은 (열림닫힘+닫힘열림)/2와 기하학적 보정이다. 세 번째 검증 단계에서는 전체 영상 화소수 대비 각 후보 문자 영역의 화소수 비율, 각 후보 문자 영역의 전체 화소수 대비 외곽선의 화소수 비율, 각 외곽 사각형의 폭 대 높이간의 비율 등을 고려하여 비문자로 판단되는 요소들을 제거한다. 임의의 300개의 국내 뉴스 영상을 대상으로 실험한 결과 93.6%의 문자 추출률을 얻을 수 있었다. 또한, 본 논문에서 제안한 방법으로 국외 뉴스, 영화 비디오 등의 영상에서도 좋은 추출을 보임을 확인할 수 있었다. In recent years the amount of digital video used has risen dramatically to keep pace with the increasing use of the Internet and consequently an automated method is needed for indexing digital video databases. Textual information, both superimposed and embedded scene texts, appearing in a digital video can be a crucial clue for helping the video indexing. In this paper, a new method is presented to extract both superimposed and embedded scene texts in a freeze-frame of news video. The algorithm is summarized in the following three steps. For the first step, a color image is converted into a gray-level image and applies contrast stretching to enhance the contrast of the input image. Then, a modified local adaptive thresholding is applied to the contrast-stretched image. The second step is divided into three processes: eliminating text-like components by applying erosion, dilation, and (OpenClose+CloseOpen)/2 morphological operations, maintaining text components using (OpenClose+CloseOpen)/2 operation with a new Geo-correction method, and subtracting two result images for eliminating false-positive components further. In the third filtering step, the characteristics of each component such as the ratio of the number of pixels in each candidate component to the number of its boundary pixels and the ratio of the minor to the major axis of each bounding box are used. Acceptable results have been obtained using the proposed method on 300 news images with a recognition rate of 93.6%. Also, my method indicates a good performance on all the various kinds of images by adjusting the size of the structuring element.

A fluorinated polythiophene hole-transport material for efficient and stable perovskite solar cells

Jeong, Inyoung,Jo, Jea Woong,Bae, Seunghwan,Son, Hae Jung,Ko, Min Jae Elsevier 2019 Dyes and pigments Vol.164 No.-

<P><B>Abstract</B></P> <P>Charge-transport materials for use in highly efficient and stable perovskite solar cells (PSCs) must exhibit energy levels appropriate for high charge selectivity, sufficiently high charge-transport ability for efficient charge collection, and high humidity resistance for long-term device stability. Polythiophenes are a promising class of hole-transport layer (HTL) materials that could satisfy these requirements. However, PSCs fabricated using conventional poly(3-hexylthiophene) (P3HT) HTLs show limited efficiencies of <16% owing to the shallow highest occupied molecular orbital (HOMO) energy level and poor charge extraction ability of P3HT. Herein, we demonstrate that the fluorinated polythiophene derivative FEH is a suitable replacement for P3HT and a promising HTL material for perovskite solar cells. The FEH was found to have a deeper HOMO and exhibit more efficient charge-extraction ability at the perovskite/HTL interface than P3HT. This is attributed to the electron-withdrawing nature of the fluorine atoms in FEH and its ability to form more uniform films on the perovskite layer. Thus, when FEH was employed as the HTL, the corresponding PSC showed an improved efficiency of 18.0% and an enhancement of all device parameters compared with control devices fabricated using P3HT (10.8%) and Spiro-OMeTAD (17.0%) HTLs. Moreover, fluorination on the conjugated backbone of the polymer increases its hydrophobicity, and the resulting hydrophobic surface of the FEH HTL prevents the ingress of water, resulting in an improvement of the long-term stability of the corresponding PSCs under air exposure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fluorinated polythiophene derivative was used as hole-transport layer (HTL) of perovskite solar cells (PSCs). </LI> <LI> The fluorinated polymeric HTL shows efficient charge extraction and hydrophobic surface property. </LI> <LI> The PSCs based on the HTL exhibit a best efficiency of 18.0% and better stability compared to conventional Spiro-OMeTAD HTL. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Solution-Processed Ultrathin TiO₂ Compact Layer Hybridized with Mesoporous TiO₂ for High-Performance Perovskite Solar Cells

Jeong, Inyoung,Park, Yun Hee,Bae, Seunghwan,Park, Minwoo,Jeong, Hansol,Lee, Phillip,Ko, Min Jae American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.42

<P>The electron transport layer (ETL) is a key component of perovskite solar cells (PSCs) and must provide efficient electron extraction and collection while minimizing the charge recombination at interfaces in order to ensure high performance. Conventional bilayered TiO2 ETLs fabricated by depositing compact TiO2 (c-TiO2) and mesoporous TiO2 (mp-TiO2) in sequence exhibit resistive losses due to the contact resistance at the c-TiO2/mp-TiO2 interface and the series resistance arising from the intrinsically low conductivity TiO2 of TiO2. Herein, to minimize such resistive losses, we developed a novel ETL consisting of an ultrathin c-TiO2 layer hybridized with mp-TiO2, which is fabricated by performing one-step spin-coating of a mp-TiO2 solution containing a small amount of titanium diisopropoxide bis(acetylacetonate) (TAA). By using electron microscopies and elemental mapping analysis, we establish that the optimal concentration of TAA produces an ultrathin blocking layer with a thickness of similar to 3 nm and ensures that the mp-TiO2 layer has a suitable porosity for efficient perovskite infiltration. We compare PSCs based on mesoscopic ETLs with and without compact layers to determine the role of the hole-blocking layer in their performances. The hybrid ETLs exhibit enhanced electron extraction and reduced charge recombination, resulting in better photovoltaic performances and reduced hysteresis of PSCs compared to those with conventional bilayered ETLs.</P>

기혼간호사의 사회적 지지와 일-가정 갈등, 일-가정 향상과의 관계

이인영 ( Inyoung Lee ),고유경 ( Yukyung Ko ) 한국병원경영학회 2021 병원경영학회지 Vol.26 No.1

Purpose: This study is to identify the relationship among married nurses’ social support, work-family conflict and work-family enrichment and to examine the influence of social support on work-family conflict and work-family enrichment. Methods: Data were collected from married nurses working at three hospitals with more than 100 beds in J Province and analyzed by descriptive statistics, t-test, ANOVA, Mann-Whitney U test, Kruskal-Wallis H test, Pearson’s correlation analysis and hierarchical regression analysis using SPSS 21 program. Findings: In the correlation analysis only social support and work-family enrichment showed positive correlation. As a result of hierarchical multiple regression analysis, social support still acted as a significant influence factor on work-family conflict and work-family enrichment even in the state of considering the effect of control variables. Conclusion: In order to lower work-family conflict and to enhance work-family enrichment of married nurses, it is necessary to introduce and implement welfare policies for work-family reconciliation at the workplace level and at home level it is necessary to provide concrete measures so that married nurses can find the value of life as workers while house working and nurturing.

무기양이온 도입을 통한 유무기하이브리드 페로브스카이트 태양전지의 성능 및 안정성 향상

정인영(Inyoung Jeong),고민재(Min Jae Ko) 한국신재생에너지학회 2017 한국신재생에너지학회 학술대회논문집 Vol.2017 No.9

A tailored TiO₂ electron selective layer for high-performance flexible perovskite solar cells via low temperature UV process

Jeong, Inyoung,Jung, Heesuk,Park, Minwoo,Park, Joon Suh,Son, Hae Jung,Joo, Jin,Lee, Jinwoo,Ko, Min Jae Elsevier 2016 Nano energy Vol.28 No.-

<P><B>Abstract</B></P> <P>To realize high-performance flexible perovskite solar cells (PSCs), electron selective layers (ESL) that can be processed at low temperatures are required. Here, we develop UV-assisted solution process to prepare highly compact Nb-doped TiO<SUB>2</SUB> (UV-Nb:TiO<SUB>2</SUB>) ESLs at low temperature (<50°C). Highly crystalline TiO<SUB>2</SUB> nanocrystals (NCs) stabilized with oleic acid are synthesized and the highly dispersed TiO<SUB>2</SUB> NCs solution is spin-coated, followed by UV treatment. The UV exposure induces photocatalytic removal of the organic ligands and spontaneous coalescence of the TiO<SUB>2</SUB> NCs, resulting in highly uniform and compact TiO<SUB>2</SUB> thin films. The UV-processed TiO<SUB>2</SUB> layer (UV-TiO<SUB>2</SUB>) shows higher transmittance and a better blocking effect, compared to a conventional TiO<SUB>2</SUB> layer (HT-TiO<SUB>2</SUB>) prepared by high temperature sintering process. Furthermore, Nb doping of the TiO<SUB>2</SUB> NCs improves the electrical conductivity and gives rise to a downward shift of the conduction band, enhancing the charge extraction. Thanks to the advantages, PSCs based on UV-Nb:TiO<SUB>2</SUB> ESLs show improved photovoltaic performances and less hysteresis, compared to the HT-TiO<SUB>2</SUB> ESL. The best-performing PSCs based on UV-Nb:TiO<SUB>2</SUB> ESL exhibit outstanding power conversion efficiencies of 19.57% and 16.01% for rigid and flexible substrates, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Low-temperature solution processed TiO<SUB>2</SUB> ESL is developed for high-performance PSCs. </LI> <LI> Nb doping of TiO<SUB>2</SUB> ESL improves photovoltaic performances of PSCs. </LI> <LI> Champion cells exhibit PCE of 19.57% for rigid and 16.01% for flexible substrates. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

동해 울릉분지 CO₂ 지중저장 후보지 암상모델링 결과 개선

최인영(Inyoung Choi),임용수(Yongsu Lim),고은미(Eunmi Ko),배성인(Sungin Bae) 대한지질학회 2022 대한지질학회 학술대회 Vol.2022 No.10