Development of a Gaze Fixation Identification Algorithm for Comparison of Performance of Gaze Fixation Induction Methods in Visual Field Testing

Jihyung Lee,Nahyun Lee,Jaechun Cho,Baekhee Lee,Kyunghyun Jin,Hyejee Kim,Younggyun Kim,Jaheon Kang,Heecheon You 대한인간공학회 2015 대한인간공학회 학술대회논문집 Vol.2015 No.10

Objective: The present study to evaluate an ergonomic gaze fixation induction method for gaze fixation during visual field testing developed and applied a gaze fixation identification algorithm to the gaze tracking data analysis. Background: Development of the gaze fixation identification algorithm is necessary to evaluate the degree of gaze fixation which is important for checking the reliabilities of visual field testing. Method: the present study investigated factors of gaze tracking data and developed an identification algorithm to identify gaze fixation. 32 men and women (29.0 ± 4.4 yr) participated in gaze fixation testing to evaluate three gaze fixation induction methods (black dot, flashing black dot, bulls eye and cross hair) in the aspects of correct fixation rate using gaze fixation identification algorithm. Results: It is necessary to analyze gaze location at 0.2 seconds intervals before and after target presenting for identify a gaze fixation in visual field testing. If one of two interval gaze trajectory is belong within visual angle 1° when the gaze tracking data analyzed in 0.2 seconds intervals before and after target presenting, the gaze fixation identification algorithm decide to fix the participant’s gaze to a fixation target when the target presents. Correct fixation rate of flashing black dot (91.5%) and bulls eye and cross hair (88.0%) are higher 5.5% and 1.5% than that of black dot (86.7%). Conclusion: The analysis using short interval gaze tracking data at before and after target presenting is more effective method in visual field testing for evaluating the degree of gaze fixation. Application: The gaze fixation identification algorithm is expected to be effectively used for monitor-based gaze tracking research.

Development of a Diagnostic Model for Glaucoma

Jihyung Lee,Sudong Lee,Baekhee Lee,Jaheon Kang,Chi-Hyuck Jun,Heecheon You 대한인간공학회 2013 대한인간공학회 학술대회논문집 Vol.2013 No.5

Objective: The aim of this study was to develop a glaucoma diagnostic model applying the statistical classification method by various testing results for glaucoma. Background: Statistical diagnostic models applied with structural (e.g., fundus examination) and functional (e.g., visual field testing) testing results have been developed to diagnose glaucoma more accurately. The existing studies with regards to the glaucoma diagnostic model considered statistical techniques by various input data such as intraocular pressure and cup-to-disc ratio; however, constant exertions for improving the performance of a diagnostic model are necessary through applying unvalidated methods and input data. Method: Glaucoma testing results of 145 eyes (glaucomatous eyes = 74, normal eyes = 71) were used as input data. Five classification techniques (linear and Gaussian support vector machines [L-SVM and G-SVM], linear discriminant analysis [LDA], binary logistic regression [BLR], and classification and regression tree [CART]) were applied to develop the model. Used as input, the performance (accuracy, sensitivity, specificity and AUC) of the developed models were compared with among the developed models. Results: The PD/G-SVM model which applied with G-SVM with pattern deviation (PD) was determined as an optimal model (accuracy = 0.87; sensitivity = 0.81; specificity = 0.92; and AUC = 0.95). Conclusion: The developed PD/G-SVM model can contribute to making a diagnosis of glaucoma more precisely. Application: The developed model would be expected to apply to develop a comprehensive diagnostic system for glaucoma.

번역문 사후교정을 위한 교차언어 모델 기반의 전이학습

이지형(Jihyung Lee),이원기(WonKee Lee),김영길(Young-Gil Kim),이종혁(Jong-Hyeok Lee) 한국정보과학회 2020 한국정보과학회 학술발표논문집 Vol.2020 No.7

Analysis of Usability Evaluation for a Graphic User Interface

Sungho Kim,Baekhee Lee,Jihyung Lee,Jawon Lee,Soojung Lee,Kiwon Lee,Seikwon Park,Heecheon You 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.11

Objective: The present study is to establish a usability evaluation framework for graphic user interface (GUI). Background: Existing studies have mainly focused on specific GUI evaluation such as mobile applications and website; however, lacked of consideration with GUIs for a specialized field such as the military. Method: A four-step approach was applied in the study: (1) literature review of twenty studies related to usability evaluation, (2) analysis of GUI usability aspects by design component, design guideline/evaluation criterion, and evaluation method, (3) development of an integrated usability evaluation framework, and (4) application to screen GUIs of a computer based training (CBT). Results: Design component in the integrated usability evaluation framework was consisted of 40 design dimensions in 9 components (e.g., alignment in layout), design guideline/evaluation criterion 33 principles and guidelines (e.g., visibility), and evaluation method 38 measures (e.g., completion time) and 19 techniques (e.g., heuristic evaluation). Conclusion: The usability evaluation framework for GUI was developed in the study. Application: The usability evaluation framework for GUI can be applicable to a variety of GUIs (e.g., console screen) and utilized to evaluate GUIs systematically.

In-situ coalesced vacancies on MoSe₂ mimicking noble metal: Unprecedented Tafel reaction in hydrogen evolution

Lee, Junghyun,Kim, Changmin,Choi, KeunSu,Seo, Jihyung,Choi, Yunseong,Choi, Wooseon,Kim, Young-Min,Jeong, Hu Young,Lee, Jun Hee,Kim, Guntae,Park, Hyesung Elsevier 2019 Nano energy Vol.63 No.-

<P><B>Abstract</B></P> <P>Transition metal dichalcogenides (TMDs) have shown promising potential as electrocatalyst materials for the hydrogen evolution reaction (HER). However, the low catalytic activity in the basal planes of TMDs results in only limited HER activity, and several strategies to overcome this bottleneck have been proposed, involving various post-synthesis treatments such as introducing chalcogen vacancies or applying mechanical strain. Herein, we demonstrate in-situ modulation of chalcogen vacancy sites during the chemical vapor deposition synthesis of molybdenum diselenides (MoSe<SUB>2</SUB>) for application in the HER. We demonstrate for the first time that the Tafel reaction can be activated via in-situ vacancy-engineered MoSe<SUB>2</SUB>, resulting in improved onset potential and an exceptionally low Tafel slope, which exhibits one of the lowest values reported for TMDs to date in our knowledge. Density functional theory calculations revealed that vacancy coalescence in the MoSe<SUB>2</SUB> lattice reduced the hydrogen adsorption free energy and diffusion barrier to activate the Tafel reaction. Our approach could contribute to the development of high-performance TMDs-based electrocatalysts with relatively simple processability to make hydrogen production more viable.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Vacancy MoSe<SUB>2</SUB> was synthesized by hydrogen reactivity control during CVD process without any post-treatment. </LI> <LI> The <I>in-situ</I> synthesized vacancy-MoSe<SUB>2</SUB> exhibited outstanding HER performance with exceptionally low Tafel slope. </LI> <LI> Our results present a new perspective for developing high performance TMDs-based electrocatalysts. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Patient Health Questionnaire-9, Body Mass Index, Household Income According to Sleep Duration: Findings From a Community Health Survey

Lee Jihyung,Um Yoo Hyun,Jeong Jong-Hyun,Seo Ho-Jun,Kim Young-Chan,Yoon Sung Hoon,김석영,Kim Tae Won,Hong Seung-Chul 대한수면학회 2023 sleep medicine research Vol.14 No.1

Background and Objective Research on the relationship between sleep duration and Patient Health Questionnaire-9 (PHQ-9), body mass index (BMI), and income in South Korea was scarce. This study aimed to investigate the relationship between sleep duration and the PHQ-9, BMI, and household income.Methods We used data from the Korean Community Health Survey (KCHS) conducted by the Korean Center for Disease Control and Prevention in 2018 which included a total of 228340 participants from across the country. We divided the participants into four groups based on their sleep duration and used one-way analysis of variance (ANOVA) to compare the mean values of PHQ-9, BMI, and household income among the groups.Results A total of 227899 respondents were included in the study. Based on a one-way ANOVA, the mean PHQ-9 score tended to increase as sleep duration decreased. However, the group with a sleep duration of 9 hours or more had an exceptionally higher mean PHQ-9 score than the group with a sleep duration of 7 to 9 hours. The BMI score generally decreased as the sleep duration increased. Additionally, the group with a sleep duration of 5 to 7 hours and 7 to 9 hours had higher household income than the group with a sleep duration of 5 hours or less or 9 hours or more.Conclusions This study demonstrated the association between sleep duration and PHQ-9, BMI, and household income. Sleep duration was found to be a factor influencing PHQ-9, BMI, and household income.

Evaluation of an Ergonomic Gaze Fixation Induction Method for Improving the Accuracy of Visual Field Testing

Jihyung Lee,Baekhee Lee,Sungho Kim,Jaheon Kang,Heecheon You 대한인간공학회 2014 대한인간공학회 학술대회논문집 Vol.2014 No.11

Objective: 본 연구는 시야검사(visual field examination) 시 피검사자의 시선을 효과적으로 고정시켜 검사의 정확성을 향상시킬 수 방법을 개발하고 평가하였다. Background: 시야검사는 시신경의 기능성을 정량적으로 측정하는 장비로 시선을 한 곳에 고정시킨 상태에서 수행된다. 그러나 기존 시야계는 의미 없는 단순한 점을 시선고정용 시표로 사용하고 있어, 검사가 진행되는 약 6분 동안 피검사자의 시선을 효과적으로 고정시키는데 한계가 있었다. Method: 본 연구는 20 ~ 30대 남녀 총 60명을 대상(남:녀 = 1:1)으로 basic dot(●), alphanumeric, color changing dot, 그리고 flashing dot 방법을 사용하여 시야검사 시 시선고정 성능 및 주관적 만족도 평가를 수행하였다. 시선고정 성능은 시선고정 오류율(fixation loss rate), 거짓 시표 반응률(false positive error rate), 그리고, eye tracking data 기반의 시선 이동거리의 총합(total gaze distance)를 활용하여 평가되었다. 주관적 만족도는 시선고정 용이성, 눈피로도 그리고, 전반적 만족도 세 가지 항목에 대해 7 point-Likert-scale을 사용하여 평가되었다. Results: flashing dot은 시선 집중도가 basic dot(●)에 비해 2.4배 향상 되었고, 시선고정 용이성 측면에서 1.5배 주관적 만족도가 높은 것으로 평가되었다. Discussion: 보다 정확한 시야검사 결과를 얻기 위해, 시선고정 유도방법은 flashing dot을 사용하는 것이 선호되는 것으로 파악되었다. Application: 본 연구에서 선정된 시선고정 유도방법은 적용가능한 기존 시야계와 신규 개발될 시야계에 탑재되어 보다 정확한 시야 평가에 유용하게 활용될 것으로 기대된다.

Cyclic AMP concentrations in dendritic cells induce and regulate Th2 immunity and allergic asthma

Lee, Jihyung,Kim, Tae Hoon,Murray, Fiona,Li, Xiangli,Choi, Sara S.,Broide, David H.,Corr, Maripat,Lee, Jongdae,Webster, Nicholas J. G.,Insel, Paul A.,Raz, Eyal National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.5

<P><B>Significance</B></P><P>Allergic asthma is characterized by Th2 type inflammation, leading to airway hyperresponsiveness and remodeling. However, the mechanisms by which DC promote Th2 differentiation remain unclear. Herein we demonstrate that low cAMP levels in DC induce Th2-biased responses in vitro and in vivo. Furthermore, mice with conditional deletion of <I>Gnas</I> in DC (<I>Gnas</I><SUP>ΔCD11c</SUP> mice) develop spontaneous bronchial asthma that shares multiple similarities with human asthma. In contrast, increasing cAMP levels inhibit these responses. Thus, regulators of cAMP levels in DC such as G-protein-coupled receptors are non-pattern recognition receptors that play a significant role in CD4 T cell differentiation.</P><P>The inductive role of dendritic cells (DC) in Th2 differentiation has not been fully defined. We addressed this gap in knowledge by focusing on signaling events mediated by the heterotrimeric GTP binding proteins Gαs, and Gαi, which respectively stimulate and inhibit the activation of adenylyl cyclases and the synthesis of cAMP. We show here that deletion of <I>Gnas</I>, the gene that encodes Gαs in mouse CD11c<SUP>+</SUP> cells (<I>Gnas</I><SUP>ΔCD11c</SUP> mice), and the accompanying decrease in cAMP provoke Th2 polarization and yields a prominent allergic phenotype, whereas increases in cAMP inhibit these responses. The effects of cAMP on DC can be demonstrated in vitro and in vivo and are mediated via PKA. Certain gene products made by <I>Gnas</I><SUP>ΔCD11c</SUP> DC affect the Th2 bias. These findings imply that G protein-coupled receptors, the physiological regulators of Gαs and Gαi activation and cAMP formation, act via PKA to regulate Th bias in DC and in turn, Th2-mediated immunopathologies.</P>

내열 재료별 삭마형상에 따른 초음속 노즐 성능 분석

이지형(Jihyung Lee),함희철(Heecheol Ham) 한국추진공학회 2007 한국추진공학회 학술대회논문집 Vol.2007 No.11

Needle형 Pintle의 위치에 따른 초음속 노즐 내부 유동장 연구

이지형(Jihyung Lee),김중근(Jungkeun Kim),장홍빈(Hongbeen Chang) 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.11

고체 추진기관의 추력을 조절하기 위하여 사용되는 핀틀은 초음속 유동장 내부에 위치하기 때문에 핀틀 팁의 형상과 노즐의 Contour형상에 따라 초음속 노즐 내부는 복잡한 유동장 패턴을 가지게 된다. 본 연구는 핀틀 노즐성능에 대한 연구로 Needle형 핀틀을 사용하여 수행한 공압 시험과 수치해석을 이용하여 핀틀의 위치에 따른 초음속 노즐 내부 유동장 변화가 핀틀 노즐의 추력성능에 미치는 영향에 대하여 분석하였다. 연구의 결과, 노즐 내부에 3가지 충격파가 존재하고 경사충격파의 위치가 핀틀의 위치에 따라 진동함을 알 수 있었다. Internal flow field of supersonic nozzle with pintle, which control thrust of solid rocket motor, is very complicated by pintle tip shape and contour of nozzle. For studying of pintle nozzle performance by effects of internal flow field variation with pintle position, cold flow test and numerical analysis about needle type pintle shape were performed and results were presented in this paper. As the results of this study, three types of internal shocks exists in the pintle nozzle and oblique shock is oscillated by pintle position