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Feasibility Analysis for Conceptual Design and Application of Hybrid Type Traction System for Improved Acceleration and Deceleration Performance of Urban and Metropolitan Railway
No full text본 논문은 도시·광역철도의 가·감속 성능향상을 위한 하이브리드형 견인전동기의 개념 설계 및 적용 타당성분석에 관한 연구논문이다. 우리나라는 경제 발전과 더불어 수도권 광역화로 인하여 출퇴근 시간 증가, 표정속도 감소때문에 속도 경쟁력이 많이 저하되고, 수단 분담률이 현저히 떨어져 있다. 이러한 문제를 해결하기 위하여 본 논문에서는 도시·광역철도의 급행화를 위한 방법으로 가·감속 성능향상을 위한 연구를 수행하였으며, 향상된 가·감속을 위한구동차 및 부수차에 모두 적용할 수 있는 하이브리드형 견인전동기의 개념 설계를 수행하였다. 유도전동기보다 효율및 출력밀도 등의 성능특성이 우수한 매입형 영구자석 동기전동기를 구동차에 적용하고, 부수차에는 선형 유도전동기를 적용하는 것을 제안하였다. 결론적으로 1편성 모두 구동차로 변경되는 하이브리드형 견인전동기를 적용하여, 가·감속 성능을 향상시켜 급행화할 수 있는 방안을 제안하였다. This paper is a conceptual design and application feasibility analysis of a hybrid traction system for improvement of acceleration and deceleration performance of urban and metropolitan railway. Due to economic development in the metropolitan area, the commuting time and scheduled speed have decreased. This has greatly reduced speed competitiveness and significantly reduced the modal share rate. To solve these problems, a study was conducted to improve the performance of acceleration and deceleration as a means of express service of urban and metropolitan railway. A conceptual design of a hybrid type traction motor, which can be applied to both the motor car and trailer car for enhanced acceleration and deceleration, was carried out. A permanent magnet synchronous motor with better efficiency and output density than those of an induction motor is applied to the motor car and a linear induction motor is suggested for application to the trailer car. In conclusion, the proposed hybrid type traction motor, which converts all cars to motor cars, improve the acceleration and deceleration performance.본 연구는 국토교통부 철도기술연구개발사업의 연구비지원(18RTRP-B146008-01)에 의해 수행되었습니다
A 12-Gb/s continuous-time linear equalizer with offset canceller
No full textA DC-offset of a continuous-time linear equalizer (CTLE) is cancelled by an analog offset canceller (OFC). The bandwidth (BW) of the OFC is designed to be 10-kHz not to affect the received signal integrity. The BW of the OFC set by an active-RC integrator is lowered by increasing the effective resistance through pulse width modulation (PWM). The input offset of the OFC itself is removed by employing chopping technique. The offset-cancelled CTLE is applied to a four-channel 12-Gb/s wireline receiver compliant with the high-definition multimedia interface (HDMI) version 2.1 standard. The 12-Gb/s wireline receiver has been implemented in a 28-nm CMOS process. The eye opening for the bit-error rate (BER) smaller than 10(-12) becomes larger than 0.26 unit-interval (U1) with the OFC while the BER is always larger than 10(-12) without the OFC.This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2016R1D1A1B03930310). The CAD tools were provided by the IC Design Education Center (IDEC), Korea
Green indoor and outdoor environment as nature-based solution and its role in increasing customer/employee mental health, well-being, and loyalty
No full textThe present study was an empirical endeavor to explore the effect of nature‐based solutions (NBS) on the customer and employee loyalty generation process by considering the role of mental health and well‐being in the hotel industry. A quantitative approach was employed. A survey methodology with a convenience sampling technique was used to collect the data. A total of 303 responses and 301 responses for customer and employee groups, respectively, were used for data analysis. Our results of the structural analysis indicated that green indoor and outdoor environment as NBS helps customers and employees improve mental health perception, emotional well‐being, and loyalty. In addition, the prominent role of emotional well‐being in building customer loyalty and of mental health perception in building employee loyalty was uncovered. The developed conceptual frameworks for customers and employees contained a satisfactory ability in predicting loyalty. Mental health perception and emotional well‐being were mediators. Moreover, the relationship strength among study variables differed between customer and employee groups. Overall, our findings significantly increased our understanding of NBS and its critical role in the hotel industry.This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government, Grant/Award Number: 2018R1A5A7059549; Ministry of Science and ICT
Alcohol use disorder and health-related quality of life in Korean night-shift workers: A cross-sectional study using the KNHANES 2007-2015 data
No full textThis study aimed to evaluate the prevalence of night-shift work, and the association of night-shift work with alcohol use disorders(AUDs), as well as with health-related quality of life (HRQL), in Korean adult workers. A total of 26,895 adult workers aged 20-59 years were included in the analysis. AUDs were assessed using the Alcohol Use Disorders Identification Test(AUDIT), and HRQL was measured by the EuroQol-5D questionnaire with five main dimensions. We found an interaction effect between gender and working status on AUDs (p = 0.0065), suggesting that women are more fragile than men in terms of the effects of night work but not regarding HRQL (p = 0.1729). Female night workers had higher risk of AUDs than female day workers (odds ratio(OR): 2.23, 95% confidence interval (CI): 1.48-3.38) but this effect was not noted in male night workers (OR: 0.97, 95% CI: 0.69-1.37). Lower HRQL was found in depression dimension for night workers compared to day workers (OR: 1.37, 95% CI: 1.00-1.89), whereas day-night regular shift workers were protected from depression. Risk of AUDs and lower HRQL were identified in female night workers but not in male night workers. This association suggests that women are more fragile than men in terms of the effects of night work.This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (NRF-2016R1C1B1013621 to BP). The funders had no role in study design, data collection and analysis, decision to present, or preparation of the manuscript
Robust and scalable three-dimensional spacer textile pressure sensor for human motion detection
No full textThere is a growing demand for wearable sensing devices to perceive and respond to vital biological signals or human activities. In this work, a carbon nanotube ink drop-coated textile resistive pressure sensor on a typical three-dimensional (3D) spacer textile was developed to detect human health and motion through scalable, cost-effective, and simple processing. A 3D spacer textile comprises two outer layers interconnected with a monofilament spacer with robust compression resistance and high air circulation with open-hole structures, which demonstrates the potential for use in a wearable pressure sensing device. The textile pressure sensor unit shows a wide range of sensing performance of 200 Pa-50 kPa, which facilitates the detection of physiological signal acoustic vibrations and hand motion, and it exhibits stable cycling performances up to 10 000 cycles, along with a fast response time of 20 ms. Furthermore, large-area sensor arrays are successfully demonstrated for the spatial distribution of pressure mapping, suggesting significant potential in smart textiles or wearable electronics.This research was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean Government (NRF-2018R1A2B6005220) and the research fund of Hanyang University (HY-2017)
Validation of algorithms to identify knee osteoarthritis patients in the claims database
No full textBackground To identify knee osteoarthritis (OA) patients among OA patients in the claims database. Methods All patients with OA diagnostic codes for any sites (M15 to M19) in 2014 were recruited from a single academic referral hospital. After excluding patients who had inflammatory arthritis or were less than 50 years of age, we identified data for the overall OA population. Radiographic knee OA of Kellgren and Lawrence grades >= 2 is considered the gold standard for knee OA, and we evaluated the sensitivity, specificity, and positive predictive value (PPV) of three operational definitions using the diagnostic codes in the claims database. The operational definitions were: (1) gonarthrosis (M17); (2) any site of OA (M15 to M19) with knee X-ray; and (3) (1) or (2). Results A total of 7959 OA patients were included in this study of whom 74.5% were women. The PPV of gonarthrosis (M17) was 0.67 (95% CI 0.65-0.69), and sensitivity was 0.44 (95% CI 0.42-0.46). The PPV and sensitivity of any OA site (M15 to M19) with knee X-ray were 0.65 (95% CI 0.62-0.67), and 0.37 (95% CI 0.35-0.39), respectively. When knee OA was defined as satisfying either of the two above definitions, PPV was 0.63 (95% CI 0.62-0.65) and sensitivity 0.55 (95% CI 0.53-0.57). Conclusions Knee OA patients can be identified in a claims database using the algorithms of gonarthrosis (M17) or any site of OA (M15 to M19) with a performed knee X-ray.This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (Grant number: HC15C3388)
Combined effects of sulfamethazine and sulfamethoxazole on a freshwater microalga, Scenedesmus obliquus: toxicity, biodegradation, and metabolic fate
No full textThis study investigated the environmental effects of two common emerging contaminants, sulfamethazine (SMZ) and sulfamethoxazole (SMX), and their mixture using a green microalga, Scenedesmus obliquus. The calculated EC50 values of SMZ, SMX, and their mixture (11:1 wt/wt) after 96 h were 1.23, 0.12, and 0.89 mg L-1, respectively. The toxicity of the mixture could be better predicted using a concentration addition model than an independent action model. The risk quotients of SMZ, SMX, and their mixture were > 1 during the experiment, indicating their high potential risks on aquatic microorganisms. Despite their toxicity, S. obliquus exhibited 17.3% and 29.3% removal of 0.1 mg L-1 and 0.2 mg L-1 after 11 days of cultivation. The changes of SMZ and SMX removal were observed when combined, which showed a significantly improved removal of SMZ (up to 3.4 folds) with addition of SMX (0.2 mg L-1). The metabolic pathways of SMZ and SMX were proposed according to mass spectroscopic analysis, which showed six metabolites of SMX and seven intermediates of SMZ, formed as a result of ring cleavage, hydroxylation, methylation, nitrosation, and deamination.This study was supported by National Research Foundation of Korea (NRF) grants funded by the Ministry of Education, Science, and Technology (MEST) of the South Korean government (No. 2017R1A2B2004143), and the Doosan Yonkang Foundation
Time Transient Electrochemical Monitoring of Tetraalkylammonium Polybromide Solid Particle Formation: Observation of Ionic Liquid- to-Solid Transitions
No full textEnergy storage systems (ESSs) using a Br-/Br-2 redox reaction such as a Zn/Br redox flow battery (RFB) or a redox-enhanced electrochemical capacitor (Redox-EC) suffer from self-discharge reactions resulting in significant Coulombic loss. To inhibit the self-discharge, quaternary ammonium (Q(+)) and tetraalkylammonium (T+) bromide are added to form ionic liquid (QBr(2n+1)) and solid (TBr3) polybromides during the ESS charging process. The electrochemical formation of liquid QBr(2n+1) and its electrochemical properties have been examined. The detailed mechanisms of ionic solid TBr3 formation, however, have not yet been explored. In this article, we analyzed the ionic liquid-to-solid phase transition of TBr3 particles using a time transient electrochemical method. We suggest the formation of ionic solid TBr3 particles via hydrated TBr3 droplets as an intermediate phase, which are generated by electro-oxidation of Br- in an aqueous TBr solution. We found the phase transition time of TBr3 particles is strongly dependent on the chemical structure of T+ and the concentration of TBr in an aqueous solution.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Bio & Medical Technology Development Program (Grant 2017M3A9G8084539), and NRF funded by the Ministry of Education (Grants 2018R1D1A1B07044990 and 2018R1A2B6006320). This work was also supported by the Korea Institute of Energy Research (Project B9-2434-02), the research fund of Hanyang University (Grant HY-201800000001417), and the Sungshin Women's University Research Grant of 2019
The Influence of Topological Characteristics and Tourism Environment Information on Spatial Cognition and Satisfaction: Focused on Virtual Reality Techniques
No full text본 연구는 가상현실기법을 사용하여 관광공간에 대한 정량적인 분석을 통해 도출된 공간위상학적 특성과 그에 따른 관광객의 공간 인지가 만족도에 미치는 영향 관계를 검증하고자 하였다. 또한 공간위상학적 특성에 따라 변화하는 관광객의 인지가 어떠한 관광환경정보에 더 큰 영향을 받는지 밝히고자 하였다. 이를 밝히기 위해 유사실험연구를 실시하였으며, 요인설계는 2(공간위상학적 특성 낮은 공간vs공간위상학적 특성 높은 공간)×2(관광안내체계vs도움요청)로 구성하였다. 분석결과, 동일한 시설이 배치된 가상현실에서 공간위상학적 특성에 따른 관광객 공간 인지에 차이가 나타났다. 또한 공간위상학적 특성이 다른 공간에서 관광환경정보가 서로 다른 수준의 상호작용효과가 있는 것으로 나타나 이에 따른 시사점을 제시하였다. This study aims to construct the spatial topological characteristics of tourism space by utilizing virtual reality technique and to confirm the influence of tourist spatial cognition from them on satisfaction. It is also intended to reveal which tourist information is more affected by cognition change of tourists depending on the spatial topology. To verify given hypotheses, quasi-experimental study was conducted in this study. For factorial designs 2(Spatial topological characteristics: LOW vs HIGH) × 2(Tourist Information System vs Request for help) was set. Results showed a difference in tourist spatial recognition according to spatial topology characteristics in virtual reality where the same facility is deployed. In addition, it was found that the information on the tourism environment have different levels of interaction effects in spaces with different spatial topology characteristics
Relationship between cerebral microbleeds and white matter MR hyperintensities in systemic lupus erythematosus: a retrospective observational study
No full textPurposeWhite matter hyperintensities (WMH) and cerebral microbleeds (CMBs) are known to be associated with small vessel diseases (SVD) and neuroinflammation. The purpose was to investigate the relationship between CMBs and WMH in patients with systemic lupus erythematosus (SLE).MethodsThirty-one SLE patients with WMH and 27 SLE patients with normal brain MRI were compared. The presence, location, and grading of CMBs were assessed using susceptibility-weighted images. WMH volume was quantitatively measured. Clinical characteristics and serologic markers were compared. We also performed two separate subgroup analyses after (1) dividing WMH into inflammatory lesion vs. SVD subgroups and (2) dividing WMH into those with vs. without CMB subgroups.ResultsThe WMH group showed more frequent CMBs than the normal MR group (p˂0.001). The WMH group showed higher SLE disease activity index, longer disease duration, and a higher incidence of antiphospholipid syndrome than the normal MR group (p=0.02, 0.04, and 0.04, respectively). There was a moderate correlation between WMH volume and CMB grading (r=0.49, p=0.006). Within the WMH group, the inflammatory lesion subgroup showed more frequent CMBs and larger WMH volume than the SVD subgroup (p˂0.001 and 0.02, respectively). The WMH with CMB subgroup had larger WMH volume than the WMH without CMB subgroup (p=0.004).ConclusionIn patients with SLE, CMBs could be related to large-volume WMH and inflammatory lesions. CMBs along with severe WMH could be used as an imaging biomarker of vasculitis in patients with SLE.This study was funded by a grant from the Korean Health Technology R&D Project, Ministry of Health and Welfare, Republic of Korea (Grant no. HI09C1379 [A092077])