http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
A Classification of Drivers' Sitting Strategy based on Seating Pressure
Younggeun Choi,Baekhee Lee,Jangwoon Park,Kihyo Jung,Sungjin Sah,Heecheon You 대한인간공학회 2011 대한인간공학회 학술대회논문집 Vol.2011 No.5
As driver's body pressure distribution has been considered in ergonomic car seat design, several researches about pressure distribution based sitting strategy classification have been conducted. However, the seating strategies extracted by the existing studies have been visually classified based on body pressure distribution graph. The present study measured 40 Korean drivers' (20 male, 20 female) body pressure in their preferred sitting posture, and quantitatively classified drivers' sitting strategy using body pressure ratio (BPR) and cluster analysis. This study measured the body pressure of seventeen body parts (9 upper body parts, 8 lower body parts) separately by utilizing a seating buck which can be converted into three different types (coupe, sedan, and SUV) of occupational package layout (OPL). The measured body pressure has been classified into five sitting strategies (mid-back & scapular, hip; mid-back & scapular, hip & mid-thigh; mid-back & lumbar, hip; mid-back & lumbar, hip & mid-thigh; lumbar, hip & mid-thigh) by independence test between upper body and lower body sitting strategies, and cluster analysis of whole strategies. Moreover, this study developed a sitting strategy classification system based on five classified sitting strategies. The sitting strategies classified in this study can be utilized in ergonomic evaluation of vehicle seat design.
MAEPER: Matching Access and Error Patterns With Error-Free Resource for Low Vcc L1 Cache
Younggeun Choi,Sungjoo Yoo,Sunggu Lee,Jung Ho Ahn,Kangmin Lee IEEE 2013 IEEE transactions on very large scale integration Vol.21 No.6
<P>Large SRAMs are the practical bottleneck to achieve a low supply voltage, because they suffer from process variation-induced bit errors at a low supply voltage. In this paper, we present an error-resilient cache architecture that resolves the drawback of previous approaches, i.e., the performance degradation at a low supply voltage which is caused by cache misses in accesses to faulty resources. We utilize cache access locality and error-free resources in a cost-effective manner. First, we classify cache lines into fully and partially accessed groups and apply appropriate methods to each group. For the partially accessed group, we propose a method of matching memory access behavior and error locations with intra-cache line word-level remapping. In order to reduce the area overhead used to store the cache access information history, we present an access pattern-learning line-fill buffer (LFB). For the fully accessed group, we propose the utilization of error-free assist functions in the cache, i.e., a LFB and victim cache with no process variation-induced error at the target minimum supply voltage. We also present an error-aware prefetch method that allows us to utilize the error-free victim cache to achieve a further reduction in cache misses due to faulty resources. Experimental results show that the proposed method gives an average 32.6% reduction in cycles per instruction at an error rate of 0.2% with a small area overhead of 8.2%.</P>
Choi, Younggeun,Youn, Duck Hyun,Lee, Seung Ok,Kim, Youngkwon,Lee, Jae Sung Elsevier 2012 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.37 No.12
<P><B>Abstract</B></P><P>Nafion ion clusters are used as nanoscale polymerization reactors to synthesize sulfonated resorcinol-formaldehyde (RF) polymer gels to be used as fillers of a hybrid membrane. Because these ion clusters are distributed well over the entire Nafion structure, the polymer gels are also well dispersed in this unique organic–organic hybrid membrane compared with inorganic–organic hybrid membranes prepared by common recasting process that usually show serious aggregation of the fillers. The obtained organic–organic hybrid membranes show increased water uptake capability and the higher proton conductivity relative to pristine Nafion membrane under low-humidity conditions. In single-cell proton exchange membrane fuel cell operation without external humidifying system, the maximum power density of 289 mW/cm<SUP>2</SUP> is observed for the membrane electrode assembly (MEA) fabricated with 2 wt% sulfonated RF polymer gels/Nafion hybrid membrane, which is <I>ca</I>. 63% higher than that of the MEA fabricated with pristine Nafion membrane. However, pristine Nafion membrane showed similar or better performance to that of hybrid membranes when reactant gases are fully humidified.</P> <P><B>Graphical abstract</B></P><P><ce:figure id='dfig1'></ce:figure></P><P><B>Highlights</B></P><P>► Sulfonated RF polymer gels synthesized in Nafion ion clusters as nanoscale reactors. ► Uniform dispersion of the nano-sized polymer gels in Nafion matrix. ► The polymer gel/Nafion became a hybrid membrane for PEMFC. ► Greatly improved single-cell performance under non-humidifying feed conditions.</P>
choi, Younggeun,Kim, Youngkwon,Kang, Kyung Yeon,Lee, Jae Sung Elsevier 2011 Carbon Vol.49 No.4
<P><B>Abstract</B></P><P>Sulfonated carbon spheres (SCS) were employed with perfluorinated ionomers as a binder to make proton-conducting electrolyte membranes for polymer electrolyte membrane fuel cells (PEMFC). Hot-pressing produced a symmetric, thin membrane with SCS particles concentrated in the center of the membrane. Relative to Nafion, the SCS materials showed higher density of sulfonic acid groups and increased water retention capacity of the membrane. This is the favorable condition for effective back diffusion of water from cathode preventing dehydration of membrane. As a result, the SCS membrane showed much better performance in single cell PEMFC operation than Nafion membrane. The membrane also showed much improved tolerance to chemical degradation by oxygen radical species.</P>
Younggeun Choi,Taekho You,Geon Ha Kim,Ji Yeong An,Duklyul Na,Heecheon You 대한인간공학회 2013 대한인간공학회 학술대회논문집 Vol.2013 No.5
A steady increase in the number of people with dementia along with aging requires a counterplan to help the aged effectively manage their cognitive capabilities. Although many brain fitness systems have been developed, seniors have had difficulty in utilizing them due to a lack of usability and customization. The present study developed a medical entertainment (meditainment) program for brain fitness of seniors. The brain fitness meditainment program, called Smart Harmony, was developed by a five-step process: (1) needs survey, (2) benchmarking, (3) idea development, (4) prototyping, and (5) usability testing. First, desirable values and user needs for brain fitness were investigated. Second, existing brain fitness programs were benchmarked. Third, novel design concepts were generated and selected. Fourth, the selected concepts were prototyped. Lastly, iterative usability tests were conducted for refinement. Smart Harmony is a musical game which can enhance the social, physical, emotional, and cognitive (SPEC) activities of users. The features of Smart Harmony includes (1) played by up to seven users, (2) eight musical instruments such as piano and violin and numerous favorite songs for selection, and (3) scores by brain age of the team and individuals for motivation. Smart Harmony is expected to be utilized in welfare centers to improve seniors’ SPEC capabilities. A clinical evaluation is needed to examine the validity of Smart Harmony for brain fitness.
Development of an Ultrasonic Doppler Sensor-Based Swallowing Monitoring and Assessment System
Younggeun Choi(최영근),Minjae Kim(김민재),Baekhee Lee(이백희),Xiaopeng Yang,Jinwon Kim(김진원),Dohoon Kwon(권도훈),Sang-Eok Lee(이상억),HyangHee Kim(김향희),Seok In Nam(남석인),Saewon Hong(홍세원),Giltae Yang(양길태),Duk L. Na(나덕렬 대한인간공학회 2020 대한인간공학회 학술대회논문집 Vol.2020 No.10
Grip Posture Analysis for Ergonomic Smartphone Interface Design
Younggeun Choi,Hayung Jung,Heecheon You 대한인간공학회 2015 대한인간공학회 학술대회논문집 Vol.2015 No.10
Objective: The present study is intended to objectively classify grip postures for smartphone when user conduct tasks with hard keys and a touchscreen. Background: Grip postures need to be considered to ergonomic smartphone interface design for better usability such as controllability, user performance, and safety. Although grip postures for mobile devices were analyzed by previous researches to enhance the signal transmission performance and find out satisfaction level of each touchscreen area, grip postures of smartphones which users can conduct variety of tasks by using hard keys and a touchscreen have not been analyzed. Method: Forty five smartphone experienced users conducted tasks with nine different sized smartphone mock-ups. Two cameras were installed at both above and under the smartphone mock-up and recorded synchronized video of grips postures. The grips postures were classified by counting the number of fingers at each side of smartphones. Results: 1-finger back support & 4-finger grasp (72.2%) and 5-finger grasp (12.6%) were two major grip postures among ten different grip postures for hard key use, and 4-finger back support (66.0%) and 1-finger back support & 3-finger grasp (16.6%) were two major grip postures among twelve different grip postures for touchscreen use. Conclusion: Participants had interacted with smartphones by having various grips postures depending on the size of the smartphone and individual preference. Application: The classified major grip postures would be of use in ergonomic smartphone interface design.