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NARX modeling for real-time optimization of air and gas compression systems in chemical processes
Lee, Won Je,Na, Jonggeol,Kim, Kyeongsu,Lee, Chul-Jin,Lee, Younggeun,Lee, Jong Min Elsevier 2018 Computers & chemical engineering Vol.115 No.-
<P><B>Abstract</B></P> <P>This study considers the Nonlinear Autoregressive eXogenous Neural Net model (NARX NN) based real-time optimization (RTO) for industrial-scale air & gas compression system in a commercial terephthalic acid manufacturing plant. NARX model is constructed to consider time-dependent system characteristics using actual plant operation data. The prediction performance is improved by extracting the thermodynamic characteristics of the chemical process as a feature of this model. And a systematic RTO method is suggested for calculating an optimal operating condition of compression system by recursively updating the NARX model. The performance of the proposed NARX model and RTO methodology is exemplified with a virtual plant that simulates the onsite commercial plant with 99.6% accuracy. NARX with feature extraction model reduces mean squared prediction error with the actual plant data 43.5% compared to that of the simple feed-forward multi-perceptron neural networks. The proposed RTO method suggests optimal operating conditions that reduce power consumption 4%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> NARX NN modeling for dynamic multi-stage compression system. </LI> <LI> First principle feature extraction method for circumventing overfitting and extrapolation. </LI> <LI> Real-time optimization framework of air and gas supply network with NARX NN. </LI> <LI> Improvement of prediction performance about 43.5% compared to a conventional method. </LI> <LI> Reduced energy consumption by approximately 4% compared to conventional operation. </LI> </UL> </P>
Quantitative risk assessment of offshore carbon dioxide injection system considering seismic effects
Lee, Younggeun,Lee, Gunhak,An, Jinjoo,Kim, Kyeongsu,Ahmed, Usama,Lee, Chul-Jin,Han, Chonghun Elsevier 2018 INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL Vol.77 No.-
<P><B>Abstract</B></P> <P>Quantitative risk analysis (QRA) is one of the most generally used safety analysis measures for risk management in process industries. Currently, earthquakes occur worldwide, resulting in significant damage. Despite the importance of considering the danger of earthquakes, however, seismic effects are often not included in risk analysis owing to difficulties in considering the multi-hazard nature and domino effects of earthquakes.</P> <P>In this study, an improved methodology for QRA was proposed to consider the seismic effects including domino effects, and multi-hazard impacts of an earthquake by using a Bayesian network (BN). This analysis was applied to a topside CO<SUB>2</SUB> injection system for underground storage, which is susceptible to seismic effects. Because frequency analysis is based on a causal relationship, the BN can be used to simultaneously consider domino effects and multi-hazard risks. As a result, the societal risk integral, one of the factors in risk analysis, was 9.667 × <SUP> 10 - 4 </SUP> / y e a r in modified QRA; this value shows an increase of 3.9% compared with the societal risk integral in conventional QRA. Furthermore, the value can be increased to 35% in the sensitivity analysis depending on annual exceedance probability (AEP). This result shows the importance of considering seismic effects, including both the domino effect and multi-hazard impacts, in QRA. A risk reduction method was additionally applied to mitigate the process risk.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Quantitative risk assessment is performed on topside CO<SUB>2</SUB> injection system. </LI> <LI> Modified QRA methodology considering seismic effect is applied. </LI> <LI> Domino-effect and multi-hazard are considered by using Bayesian network. </LI> <LI> Risk mitigation and reduction are performed to manage the risks. </LI> </UL> </P>
Analysis of Korean Facial Measurements for Sizing System of Face Wearable Products
Baekhee Lee,Nahyeon Lee,Younggeun Choi,Eunjin Jeon,Kwangae Park,Boyoung Park,Wonsup Lee,Hee-Eun Kim,Jeongrae Lee,Junghee Won,Hyoseon Kim,Younghyun Kim,Heecheon You 대한인간공학회 2015 대한인간공학회 학술대회논문집 Vol.2015 No.10
Objective: The present study is to analyze Korean facial dimensions and select facial key dimension candidates for establishing a sizing system of face wearable products such as dust mask and oxygen mask. Background: An anthropometric sizing system accommodating different facial characteristics of the target population can contribute to improving usability of the face wearable product. Method: Facial key dimension candidates were selected by correlation analysis among 19 facial dimensions. Korean facial sizes measured by KATS (2004, 2010) and Lee et al. (2013) were compared to Chinese facial sizes measured by Du et al. (2008) to each facial key dimension candidate. Results: Face length, bitragion breadth, bitragion-subnasale arc, and bitragion-pronasale arc were selected as facial key dimension candidates. The face length of Korean was 6.6 mm longer compared to that for Chinese; the bitragion-subnasale arc 17.4 mm shorter. Conclusion: The present study proposed four facial key dimensions for Korean face wearable product sizing systems. Found that Korean have longer face length and lower cheekbones compared to Chinese. Application: The facial key dimension and corresponding analysis result can be applied to design for sizing system of Korean facial wearable products.
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
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>
Lee, Jae Young,Park, Younggeun,Pun, San,Lee, Sung Sik,Lo, Joe F.,Lee, Luke P. The Royal Society of Chemistry 2015 Nanoscale Vol.7 No.23
<P>Intracellular Cyt c release profiles in living human neuroblastoma undergoing amyloid β oligomer (AβO)-induced apoptosis, as a model Alzheimer's disease-associated pathogenic molecule, were analysed in a real-time manner using plasmon resonance energy transfer (PRET)-based spectroscopy.</P>
박영근(YoungGeun Park),이중렬(JoongRyul Lee),김범석(BeomSeok Kim),이영호(YoungHo Lee) 한국마린엔지니어링학회 2005 한국마린엔지니어링학회 학술대회 논문집 Vol.2005 No.-
KOWACO - ChangWon Branch - have conducted the new study which aimed to improve flocculation performance in Mixers. The Purposes in this study were increasing flocculation efficiency by finding significant factor which was affected flow characteristics. In the result of this research we modified the error in equation of G-value and RPM which have been used till quite recently. Also we developed program auto-calculating G-value and RPM and then we had made their statistical list. We had conducted experiment with flocculation Mixer's model sized 1/10 by PIV's method. We analysed characteristic of all flow fields by changing case such as changing direction of flocculator roatation etc.
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>
Evaluation of an Ergonomic Seat Motion System using EOG Analysis
Baekhee Lee,Jangwoon Park,Younggeun Choi,Jihyoung Lee,Taekho You,Hyewon Lee,Sungjin Sah,Heecheon You 대한인간공학회 2012 대한인간공학회 학술대회논문집 Vol.2012 No.11
Objective: The aim of this study is to develop and evaluate an ergonomic seat motion system for reducing driver’s mental fatigue. Background: Driving fatigues are physically and cognitively occurred due to internal/external workloads generated by various driving environments. In particular, passive task-related (PTR) fatigue occurred by monotonous driving (e.g., expressway driving) induces drowsy driving and reduces driving ability. Thus, seat motion systems (SMSs) for decreasing driver’s mental fatigue have been developed recently; however SMSs need those validations. Method: Three-step research protocol (S1. development of a SMS, S2. experiment on ergonomic driving, S3. evaluation of the SMS) was applied as followings; (1) development of the SMS derived from literature survey, (2) measurement of EOG signals through expressway driving simulation experiment (n = 30; 20s ~ 50s, driving experience > 2 yr) at both a static seat and a dynamic seat applied with the SMS, and (3) validation of the SMS through EOG waveform analysis. Meanwhile, the present study developed and applied an eye location correction algorithm to minimize variation of driver’s eye location by occurring seat motion. Results: Three eye blink types (alert, normal, drowsy) were classified through K-means clustering analysis by using three EOG parameters (peak amplitude, closing time, opening time). 70% of drivers had that drowsy blink rate at the dynamic seat was reduced comparing with that at the static seat. Mean drowsy blink rate at the dynamic seat (35%) was significantly lower than that at the static seat (38%) (z = 9.56, p < .001). Conclusion: The developed SMS can contribute to reducing driver’s PTR fatigue. Application: The SMS can be applied with real vehicles for maintaining driving ability and driving safety.