항공기 주기환경이 대기부식위험도에 미치는 영향

윤주희 ( Juhee Yun ),이두열 ( Dooyoul Lee ),박승렬 ( Sungryul Park ),김민생 ( Min-saeng Kim ),최동수 ( Dongsu Choi ) 한국부식방식학회 2021 Corrosion Science and Technology Vol.20 No.2

Atmospheric corrosion severity associated with aircraft parking environment was studied using metallic specimens, and temperature and humidity sensors installed at each aircraft operating base. Data were analyzed after a year of exposure. Silver was used to measure chloride deposition by integrating X-ray photoelectron spectroscopy depth profiles. Carbon steel was utilized to determine the corrosion rate by measuring the weight loss. The time of wetness was determined using temperature and humidity sensor data. Analysis of variance followed by Tukey’s “honestly significant difference” test indicated that atmospheric environment inside the shelter varied significantly from that of unsheltered parking environment. The corrosion rate of unsheltered area also varies with the roof. Hierarchical clustering analysis of the measured data was used to classify air bases into groups with similar atmospheric corrosion. Bases where aircraft park at a shelter can be grouped together regardless of geographical location. Unsheltered bases located inland can also be grouped together with sheltered bases as long as the aircraft are parked under the roof. Environmental severity index was estimated using collected data and validated using the measured corrosion rate.

Thin film display based on polymer waveguides.

Park, Suntak,Park, Bong Je,Yun, Sungryul,Nam, Saekwang,Park, Seung Koo,Kyung, Ki-Uk Optical Society of America 2014 Optics express Vol.22 No.19

<P>This paper reports thin, transparent, and soft displays based on polymer waveguides that are compliant with curvilinear interfaces. In order to prove a feasibility of optical waveguide for a flexible display, we suggest the waveguide fabricated by a multi-step lithography process using two photo-curable pre-polymers with different refractive index. The displays are composed of light sources, polymer waveguides, and scatter patterns. The light signal propagating through the waveguides forms images of the scatter patterns by deflecting the light signals to outer surface. The scatter patterns are configured to a seven-segment. The seven-segment design with a switching methodology of the light sources contributes to selectively representing all decimal numbers from 0 to 9 by combination of activated segments. For a large area display based on the proposed methodology, a single light source interconnected to multi-waveguide section is integrated with a QWERTY key pad design. The display shows high transparency and flexibility without visual distortion.</P>

Polymer-Based Flexible Visuo-Haptic Display

Sungryul Yun,Suntak Park,Bongjae Park,Seung Koo Park,Prahlad, Harsha,Von Guggenberg, Philip,Ki-Uk Kyung IEEE 2014 IEEE/ASME transactions on mechatronics Vol.19 No.4

<P>We report a flexible visuo-haptic display that allows for interactive haptic feedback on the visual display. The visuo-haptic display is fabricated by integrating a dielectric elastomer (DE) based thin film actuator array into a flexible display and pressure sensors. The DE actuator array consists of nine active cells, which generate thickness-mode deformation in response to voltage signal. The flexible display presents images of the aligned three alphabet characters at each section in 3 × 3 matrix during light propagation via optical multiwaveguide. The pressure sensors are placed on the bottom of the DE actuator array for haptic feedback. The performance of the DE actuators is proved to be capable of realizing sufficient vibro-tactile sensation in the perceivable range of human touch sense. The integrated system enables the visual display to provide interactive haptic feedback such as key pressing, contact vibration sensations, etc., in accordance with user input.</P>

Comparison of Curved and Flat Displays from the Perspective of Visual Ergonomics

Sungryul Park,Gyouhyung Kyung 대한인간공학회 2017 대한인간공학회 학술대회논문집 Vol.2017 No.4

Effects of Display Type and Movie Watching Time on Presence and Cybersickness

Sungryul Park,Jihhyeon Yi,Minjung Kim,Gyouhyung Kyung 대한인간공학회 2017 대한인간공학회 학술대회논문집 Vol.2017 No.4

Determination of Basic Take-over Scenarios for Designing Human Factors Experiment in Conditional Automated Driving

Sungryul Park,Myoungouk Park,Joonwoo Son 대한인간공학회 2018 대한인간공학회 학술대회논문집 Vol.2018 No.5

Objective: This paper aims to propose basic take-over scenarios for evaluating human factors experimental design in take-over situation to assess take-over performance on conditional automated driving. Background: In the autonomous driving environment of SAE level 3, some studies have been conducted to ensure the safety of takeover situations. However, it is necessary to develop a basic scenario that can represent the transition situation for integrating and analyzing the results of individual studies. Method: The literature review was conducted focusing on the element, traffic complexity before the transition referring to our previous classification results. Results: The inclusion criteria for developing the scenarios were road type and event. Four types of basic take-over scenarios have been proposed in this study; straight road-missing lane marking, curved road-missing lane marking, straight road-unexpected external obstacle, and straight road-system failure. Application: The results of this study can contribute to designing an experiment to evaluate safety before control in the event of a conditional automatic (Level 3) in the future.

Influences of Large Flexible Display Curvature on Legibility and Visual Fatigue

( Sungryul Park ),( Jihhyeon Yi ),( Donghee Choi ),( Gyouhyung Kyung ),( Seungbae Lee ),( Byeonghwa Choi ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

The aim of the current study was to examine if legibility and visual fatigue are affected by display curvature. Twenty four subjects (13 males and 11 females) who had visual acuity > 0.8 and passed a color-blind test were participated in the current study. Their mean (SD) age was 21.7 (1.12) years [male: 21.10 (1.29), female: 21.00 (1.41)], and their mean (SD) visual acuity for the left and right eyes was 1.1 (0.27) and 1.05 (0.21), respectively. Each subject was asked to do a visual searching task that is counting the number of letter ``A`` while reading a pseudo-text. Four radii of curvature were used (400mm, 600mm, 1200mm, and flat condition), and visual distance was set to 500 mm. The error rate of finding letter ``A`` and the text reading speed were measured to assess legibility. The ECQ (Eye Complaint Questionnaire) was administered before and after each visual searching task to assess visual fatigue. Results indicated that legibility and visual fatigue improved when curved display was used. These results can be used as guidelines for determining the optimal range of flexible display curvature from the visual ergonomics perspective.

Electrically tunable binary phase Fresnel lens based on a dielectric elastomer actuator

Park, Suntak,Park, Bongje,Nam, Saekwang,Yun, Sungryul,Park, Seung Koo,Mun, Seongcheol,Lim, Jeong Mook,Ryu, Yeonghwa,Song, Seok Ho,Kyung, Ki-Uk The Optical Society 2017 Optics express Vol.25 No.20

Effects of display curvature, display zone, and task duration on legibility and visual fatigue during visual search task

Park, Sungryul,Choi, Donghee,Yi, Jihhyeon,Lee, Songil,Lee, Ja Eun,Choi, Byeonghwa,Lee, Seungbae,Kyung, Gyouhyung Elsevier 2017 Applied ergonomics Vol.60 No.-

<P><B>Abstract</B></P> <P>This study examined the effects of display curvature (400, 600, 1200 mm, and flat), display zone (5 zones), and task duration (15 and 30 min) on legibility and visual fatigue. Each participant completed two 15-min visual search task sets at each curvature setting. The 600-mm and 1200-mm settings yielded better results than the flat setting in terms of legibility and perceived visual fatigue. Relative to the corresponding centre zone, the outermost zones of the 1200-mm and flat settings showed a decrease of 8%–37% in legibility, whereas those of the flat setting showed an increase of 26%–45% in perceived visual fatigue. Across curvatures, legibility decreased by 2%–8%, whereas perceived visual fatigue increased by 22% during the second task set. The two task sets induced an increase of 102% in the eye complaint score and a decrease of 0.3 Hz in the critical fusion frequency, both of which indicated an increase in visual fatigue. In summary, a curvature of around 600 mm, central display zones, and frequent breaks are recommended to improve legibility and reduce visual fatigue.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Curvatures of 600 mm and 1200 mm were more legible and less visually fatiguing than a flat display. </LI> <LI> Legibility decreased by 8%–37% in the outermost zones of the 1200-mm and flat settings. </LI> <LI> Visual fatigue increased by 26%–45% in the outermost zones of the flat setting. </LI> <LI> A 30-min visual search task induced visual fatigue. </LI> <LI> Use of ∼600 mm curvature, avoiding the outer zones, and frequent breaks are advised for VDT tasks. </LI> </UL> </P>

A Survey of Smartphone Usage Patterns among Korean College Students

Sungryul Park,Jihhyeon Yi,Donghee Choi,Gyouhyung Kyung 대한인간공학회 2013 대한인간공학회 학술대회논문집 Vol.2013 No.10

Objective: 본 연구의 목적은 대학생의 스마트폰 사용패턴을 분석하는 것이다. Background: 스마트폰 사용자들의 사용특성을 분석하기 위한 다양한 연구가 진행되어왔다. 스마트폰의 사용과 관련된 데이터를 수집하기 위한 방법으로 대부분의 연구가 설문조사방법을 사용하였다. 그러나, 설문조사는 응답자의 기억에 의존 하는 단점을 가지기 때문에 보다 정확히 데이터를 얻을 수 있는 방법이 필요하다. Method: 본 연구에서는 안드로이드 기반의 스마트폰을 사용하는 대학생(평균나이: 21.4세, SD:0.8세)을 대상으로 MoMo라는 어플리케이션을 사용하여 스마트폰 사용패턴을 조사하였다. 총 34 명 (남: 15, 여: 19)의 스마트폰 사용자는 MoMo 앱을 통해 자동으로 저장 된 하루 평균 앱 사용시간과 사용빈도를 7일간 매일 diary keeping 방식을 통해 기록하였다. Results: 대학생의 하루 평균 스마트폰 사용시간은 389분으로 나타났으며, 하루 평균 사용빈도는 174회로 나타났다. 하루 동안의 스마트폰 평균사용시간은 남학생(403분)과 여학생(381분)간 유의한 차이가 없었으나 (p=0.624), 여학생(188회)이 남학생(154회)보다 더 자주 스마트폰을 사용하는 것으로 나타났다(p=0.033). Conclusion: 대학생은 스마트폰을 이용해 정보검색의 기능을 가장 자주, 그리고 가장 많은 시간 동안 사용하였다. 이러한 결과는 기존의 선행연구들의 연구결과와 대체로 일치하나, 사용자들의 하루 평균 스마트폰 총 사용시간의 경우 기존연구보다 더 큰 결과값 (223% ~ 400%)을 보이고 있다. 이러한 결과는 기존 연구에서 사용한 설문조사방식에 의한 데이터의 누락이 한 원인이 될 수 있다. 스마트폰 사용자들의 사용 패턴을 분석하기 위해서는 전용 어플리케이션을 이용해서 설문조사방식보다 체계적이고 정확한 데이터 수집이 필요하다. Application: 본 연구에서 체계적으로 수집된 스마트폰 사용 패턴 데이터는 스마트폰의 하드웨어나 어플리케이션 관련 컨텐츠 개발을 위한 기초자료로 활용될 수 있다.