Fault Tolerant Control Using Self-Diagnostic Smart Actuator

Inseok Yang,Kyungmin Kang(번역자),Dongik Lee2 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

In this paper, a networked fault tolerant control strategy that utilizes a self-diagnostic smart actuator is presented with an application to “"steer-by-wire”" (SBW) which is a network based steering system for intelligent cars. Networked control systems (NCS) like SBW have various advantages, such as easy maintenance, low cost implementation and reconfiguration ability. In NCS, it is possible to achieve bi-directional communications using intelligent subsystems called “"smart actuators.”" Using a built-in processing unit and bi-directional communication, a smart actuator can offer the capability of self-diagnosis and self-compensation resulting in a high level of dependability. This paper highlights the usefulness of such smart actuators from the point of view of enhancing the ability of tolerating actuator faults without any redundant actuators. The proposed approach is mainly relying on an actuator performance index, called effectiveness factor, which can be obtained through self-diagnosis performed by the built-in actuator processor. Simulation results with a SBW system show that the proposed smart actuator-based control system provides fast and accurate control strategy to tolerate faults.

Relationship of EMG and Subjective Discomfort Ratings for Repetitive Handling of Lightweight Loads

Inseok Lee,Sungpill Jo 대한인간공학회 2014 大韓人間工學會誌 Vol.33 No.6

Objective: The aim of this study is to evaluate the effect of weight of load and time on the physical workload of repetitive upper-limb tasks with handling light weight loads using EMG and perceived discomfort, and to investigate the relationship between EMG and perceived discomfort for those repetitive tasks of moving light weight loads. Background: Repetitive upper-limb motion is known as one of the main risk factors of musculoskeletal disorders, and a lot of repetitive tasks are carried out while handling light weight loads in the industry. In evaluating the workload of repetitive tasks handling light weight loads, EMG and perceived discomfort can be used, though their relationship in those work conditions are not much investigated. Method: A laboratory experiment with 18 healthy males were conducted to record EMG signals from 5 muscle sites of the right arm and shoulder and rate perceived discomforts for the body parts and the whole body while carrying out repetitive materials-handling tasks for 52min. The subjects were divided into 3 groups which handled the loads of 1kg, 2kg and 3kg, respectively. ANOVAs were conducted to analyze the effects of the weight and time on RMS of EMG amplitude (normalized RMS: NRMS), median frequency of power spectrum of EMG (normalized MDF: NMDF) and perceived discomfort. The correlations between NRMS and NMDF and perceived discomfort were also analyzed. Results: Statistically significant muscular fatigue effects were not found from NRMS and NMDF in most muscles, while there were significant increases of discomfort as the task time elapsed. It was shown that there were an increasing trend of the muscular activity as the weight of load increased and a decreasing trend of median frequency of EMG of upper and lower arms as time elapsed. It was found that there were significant negative correlations between NMDFs from the lower arm and discomfort ratings, though the relationships were weak. Conclusion: It can be concluded that the working conditions adopted in this study were not enough to induce muscular fatigue, while there was significant increase in perceived discomfort. A further study is necessary to integrate the objective and subjective measures for more reliable and sensitive evaluation of workload of repetitive tasks of handling light weight loads. Application: This study can be used as a basic study for the evaluation of workload of repetitive tasks handling light weight loads.

Colonic Chicken Skin Mucosa Surrounding Colon Polyps Is an Endoscopic Predictive Marker for Colonic Neoplastic Polyps

Lee Yu Mi,Song Kyung Ho,Koo Hoon Sup,Lee Choong-Sik,Ko Inseok,Lee Sang Hyuk,Huh Kyu Chan 거트앤리버 소화기연관학회협의회 2022 Gut and Liver Vol.16 No.5

Background/Aims: Narrow band imaging provides an accurate diagnosis of colonic polyps. However, these diagnostic modalities are not used as standard endoscopic tools in most institutions. This study aims to investigate whether the chicken skin mucosa (CSM) surrounding the colon polyp yields additional information about colorectal polyps, including histological differentiation of neoplastic and non-neoplastic polyps, under conventional white light colonoscopy. Methods: This study prospectively observed 173 patients who underwent endoscopic polypectomy and reviewed the clinical data and pathologic reports of 313 polyps from a university hospital. Two endoscopists each performed colonoscopy and polypectomy and assessed the CSM. The association between CSM surrounding colorectal polyps and histology was analyzed. Results: The majority (91.3%) of CSM-positive polyps were neoplastic (sensitivity, 37.90%; specificity, 86.15%; p<0.001). In logistic regression, the neoplastic polyps were associated with positive CSM (adjusted odds ratio [OR], 3.51; 95% confidence interval [CI], 1.45 to 9.25; p=0.007), protruded polyps (adjusted OR, 4.85; 95% CI, 1.65 to 17.23; p=0.008), and neoplastic histology–associated pit pattern (pit III, IV, and V) (adjusted OR, 10.14; 95% CI, 4.85 to 22.12; p=0.000). Furthermore, advanced adenomas were associated with positive CSM (adjusted OR, 5.64; 95% CI, 1.77 to 20.28; p=0.005), protruded polyps (adjusted OR, 3.30; 95% CI, 1.15 to 9.74; p= 0.026), and ≥10 cm polyp size (adjusted OR, 18.56; 95% CI, 3.89 to 147.01; p=0.001). Conclusions: Neoplastic and advanced polyps were associated with CSM-positive polyps. These findings suggest that CSM is a useful marker in differentiating neoplastic polyps and advanced polyps under conventional white colonoscopy.

Single-Channel Recording of TASK-3-like K<SUP>+</SUP> Channel and Up- Regulation of TASK-3 mRNA Expression after Spinal Cord Injury in Rat Dorsal Root Ganglion Neurons

Inseok Jang,Jun-Ho La,Gyu-Tae Kim,Jeong-Soon Lee,Eun-Jin Kim,Eun-Shin Lee,Su-Jeong Kim,Jeong-Min Seo,Sang-Ho Ahn,Jae-Yong Park,Seong-Geun Hong,Dawon Kang,Jaehee Han 대한생리학회-대한약리학회 2008 The Korean Journal of Physiology & Pharmacology Vol.12 No.5

Single-channel recordings of TASK-1 and TASK-3, members of two-pore domain K⁺ channel family, have not yet been reported in dorsal root ganglion (DRG) neurons, even though their mRNA and activity in whole-cell currents have been detected in these neurons. Here, we report single-channel kinetics of the TASK-3-like K⁺ channel in DRG neurons and up-regulation of TASK-3 mRNA expression in tissues isolated from animals with spinal cord injury (SCI). In DRG neurons, the single-channel conductance of TASK-3-like K⁺ channel was 33.0±0.1 pS at −60 mV, and TASK-3 activity fell by 65±5% when the extracellular pH was changed from 7.3 to 6.3, indicating that the DRG K⁺ channel is similar to cloned TASK-3 channel. TASK-3 mRNA and protein levels in brain, spinal cord, and DRG were significantly higher in injured animals than in sham-operated ones. These results indicate that TASK-3 channels are expressed and functional in DRG neurons and the expression level is up-regulated following SCI, and suggest that TASK-3 channel could act as a potential background K⁺ channel under SCI-induced acidic condition.

Plasmonic absorbers with optical cavity for the enhancement of photothermal/opto-calorimetric infrared spectroscopy

Lee, Dongkyu,Chae, Inseok,Kwon, Ohwon,Lee, Kang-Ho,Kim, Changwon,Kim, Seonghwan,Thundat, Thomas American Institute of Physics 2017 Applied Physics Letters Vol.110 No.1

Analysis of working postures of blueberry-harvesting tasks

Inseok Lee(이인석),Yonghwi Kim(김용휘) 대한인간공학회 2018 대한인간공학회 학술대회논문집 Vol.2018 No.11

Branched Segments in Polymer Gate Dielectric as Intrinsic Charge Trap Sites in Organic Transistors

Lee, Junghwi,Choi, Hyun Ho,Park, Namwoo,Min, Honggi,Han, Singu,Jeong, Heejeong,Song, Inseok,Kim, Se Hyun,Lee, Hwa Sung American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.14

<P>Charge traps in polymer gate dielectrics determine the electrical stability of organic field-effect transistors (OFETs), and polar alkoxy groups are well-known extrinsic charge traps. However, the actual location of intrinsic charge traps in nonpolar polymer gate dielectrics has been poorly understood yet. Here, we demonstrate that the skeletal structure of polymer chain plays an important role in determining the electrical stability. To verify it, we prepared linear and branched polystyrene (<I>l</I>-PS and <I>b</I>-PS) and blended them, in which branched segments provide much larger free volume than the other segments. The current-insulating performance and field-effect mobility increased with decease of <I>b</I>-PS portion. In particular, the bias-stress stability was remarkably varied according to the change of <I>b</I>-PS portion even though all measurements excluded reactive components such as oxygen and water; the increase of <I>b</I>-PS resulted in time-dependent decay of mobility and threshold voltage under bias stress. This indicates that the branched segments in <I>b</I>-PS provide intrinsic and metastable charge trap sites. Our result suggests that the skeletal structure of polymeric chains in gate dielectric is one of the important factors affecting intrinsic long-term operational stability of OFET devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-14/acs.jpcc.5b01522/production/images/medium/jp-2015-015226_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5b01522'>ACS Electronic Supporting Info</A></P>

Foreword: Special Issue Title: International Symposiums on Ergonomics and Human Factors Held by Ergonomics Society of Korea (ESK) in 2021 and 2022

Inseok Lee,Taezoon Park,Kyungdoh Kim 대한산업공학회 2024 Industrial Engineeering & Management Systems Vol.23 No.1

김치냉장고 사용자의 사용성 만족도 조사

Inseok Lee(이인석),Jae Hee Park,Tae-Joo Park,Jaehyun Choi,Dohyung Kee 대한인간공학회 2007 대한인간공학회 학술대회논문집 Vol.- No.-

Kimchi refrigerator is a specific refrigerator for Kimchi, Korean traditional fermented dish. It has been fast popularized since it was developed about ten years ago. In this study, a survey was conducted with 103 female voluntary respondents to understand the customer satisfaction of the Kimchi refrigerator in the aspect of physical usability. The respondents showed a high satisfaction for the use of the refrigerator. It was, however, shown that they felt highly uncomfortable in using the refrigerator. In particular, the high discomfort is related to the fact that the customer should bend his/her torso very much to put Kimchi cases into the refrigerator, take them out of it, or clean its inside. Seventy-five percent of the respondents reported the experience of body-part pains and 58.4% of them reported pain experience in the back. It is presumed that these results are highly correlated to the top-cover design of the refrigerator, which is the popular style to improve its performance of maintaining the temperature properly. Therefore, the developers should consider these physical usability problems related to the refrigerator and try to enhance its usability.

Prediction of whole-body postural discomfort using an artificial neural network

Lee, Inseok,Chung, Min K. 안성산업대학교 2002 論文集 Vol.34 No.-

Work posture is one of the main risk factors of work-related musculoskeletal disorders. In this study, the relationship model to predict the whole-body postural discomfort form body-joint discomfort scores was developed using an artificial neural network. Seventeen male subjects rated their perceived discomfort for representative automobile assembly tasks in a laboratory experiment. Each subject simulated 42 different work postures for 1 min each, and reported their whole-body discomfort ratings using the magnitude estimation technique with free modulus. The subjective discomfort rating data of each subject were then normalized with reference to the maximum data to reduce the inter-individual variations. Among data for 42 postures, discomfort data for 28 randomly selected postures were used in developing the neural network models, and the others were used in validating the prediction model. Statistical analyses showed that the models have a good prediction performance. Although the error rates were not small enough to be applied in the evaluation of field jobs, it is expected that the prediction performance can be increased by using larger data set in developing the artificial neural network model. This study showed the possibility of applying the neural network technique in the evaluation of postural stresses.