• 한국직업건강간호학회지
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• 제23권1호
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• pp.20-27
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• 2014

Purpose: This study was conducted to identify the association between emotional labor and job stress in bus drivers, as well as to propose management strategies for job stress. Methods: The study was conducted in February 2013 and involved 182 bus drivers working in the Gyeonggi area. Results: emotional labor was $9.5{\pm}2.34$ on average, and job stress was higher than the median of the same indicator among Korea's workers in the areas of physical environment, job autonomy, and relationship conflicts. Factors that affected job stress was lower if the subjects' Higher values for emotional labor indicated a higher level of job stress. Conclusion: To reduce among drivers, the following measures are necessary: increase the comfort of the driver's seat within the vehicle, provide adequate rest between bus headways, provide comfortable in-house rest facilities, and establish physical training spaces to reduce musculoskeletal disorders as well as programs for reducing back pain. In addition, relationship conflicts may be relieved by increasing job autonomy as much as possible, by granting autonomous control of working hours and bus headways, as well as by banning long work hours. Moreover, various club activities, exercise programs, and counseling programs that workers can be involved in together may be beneficial. This study is significant in that it identified the relationship of the bus drivers' emotional labor and job stress, which has previously been ignored as a research topic. Through its results, this study provides baseline data for the preparation of management strategies that can address the job stress of bus drivers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.9-9
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• 2010

In this paper, High Brightness LED driver IC using new current sensing circuit is proposed. This LED driver IC can provide a constant current with high current precision over a wide input voltage range. The proposed current-sensing circuit is composed of a cascode current sensor and a current comparator with only one reference voltage. This IC minimizes the voltage stress of the MOSFET from the maximum input voltage and has low power consumption and chip area by using simple-structured comparator and minimum bias current. The LED current ripple of the designed IC is in ${\pm}5%$ and a tolerance of the average LED current is lower than 2.43%. This shows much improved feature than the previous method. Also, protections for input voltage and operating temperature are designed to improve the reliability of the designed IC. Designed LED driver IC uses $1{\mu}m$ X-Fab. BiCMOS process parameters and electrical characteristics and functioning are verified by spectre(Cadence) simulation.

• 전력전자학회논문지
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• 제21권1호
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• pp.42-48
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• 2016

Light-emitting diode (LED) drivers are recently replacing fluorescent lamps; these drivers can operate adaptively with various ballasts without modifying and removing such ballasts. To satisfy these trends, a LED driver that is compatible with both electronic and magnetic ballasts is proposed in this study. Unlike conventional LED drivers, the proposed driver has a ballast recognition circuit and a mode selection circuit to operate ballasts at optimal conditions. Therefore, it features low voltage stress, high efficiency, and good compatibility with both electronic and magnetic ballasts. Moreover, it can be compatible with a wide selection of ballasts from various manufacturers. To confirm the validity of the proposed LED driver, results of the theoretical analysis and experimental verification performed on a 15 W-rated prototype are presented.

• Safety and Health at Work
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• 제2권2호
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• pp.169-175
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• 2011

Objectives: The questionnaire of occupational stress index (OSI) has been popular in the workplace, and it has been tailored for bus drivers in Taiwan. Nevertheless, its outcomes for participants are based on self-evaluations, thus validation by their physiological stress biomarker is warranted and this is the main goal of this study. Methods: A cross-sectional study of sixty-three city bus drivers and fifty-four supporting staffs for comparison was conducted. Questionnaire surveys, 24-hour urine cortisol testing, and blood draws for dehydroepiandrosterone-sulfate (DHEA-S) testing were performed. The measured concentrations of these biological measures were logarithmically transformed before the statistical analysis where various scores of stressor factors, moderators, and stress effects of each OSI domain were analyzed by applying multiple linear regression models. Results: For drivers, the elevated 24-hour urine cortisol level was associated with a worker's relationship with their supervisor and any life change events in the most recent 3 months. The DHEA-S level was higher in drivers of younger age as well as drivers with more concerns relating to their salary and bonuses. Non-drivers showed no association between any stressor or satisfaction and urine cortisol and blood DHEA-S levels. Conclusion: Measurements of biomarkers may offer additional stress evaluations with OSI questionnaires for bus drivers. Increased DHEA-S and cortisol levels may result from stressors like income security. Prevention efforts towards occupational stress and life events and health promotional efforts for aged driver were important anti-stress remedies.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 추계학술대회
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• pp.171-173
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• 2018

대중교통 운전자들의 열악한 근무 환경은 근로자의 정신적 스트레스와 피로누적을 초래할 뿐만 아니라 대중교통 사고의 주요 원인과 직결된다. 스트레스와 피로누적은 심리적, 육체적으로 건강에 영향을 미치기 때문에 생체신호와도 밀접한 연관성을 가진다. 본 논문에서는 심전도와 맥박 수, 체온을 측정하여 운전자의 건강상태를 파악할 수 있는 디지털 의류를 설계하였다. 또한, 이상이 있을 경우를 가정하여, 측정된 생체신호를 블루투스를 통하여 스마트폰 앱으로 전송하고 스마트폰 내장 GPS를 활용하여 운전자의 현재 위치를 서버로 전송해주는 시스템을 제안하였다.

• 한국정보통신학회논문지
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• 제14권5호
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• pp.1303-1310
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• 2010

최근 운전자의 건강상태 모니터링 및 졸음운전 방지를 위한 자동차용 부품관련 센서개발 및 시스템 연구들이 국내외에서 활발히 진행되고 있다. 본 논문은 이러한 운전자의 건강 상태 및 졸음운전을 점검하기 위해 체스트벨트 심전도 (ECG)와 손목착용형 산소포화도 (SpO2) 센서를 제작하여 생체신호를 측정하였으며, 측정된 심전도, 산소 포화도, 그리고 심장박동수 신호는 무선센서네트워크를 통해 수집, 전송 및 모니터링 등의 처리를 가능하게 하여 운전자에게 안전운행을 위한 정보를 제공하도록 하였다. 원격지인 서버 PC와 연결된 베이스스테이션으로 수집된 심전도와 용적맥파 신호에서 HRV (Heart Rate Variability, 심박변이도) 신호를 검출하였으며, 검출된 HRV 신호를 시간 영역과 주파수 영역에서의 해석을 통하여 운전자의 스트레스 지수 및 졸음 상태의 실시간 모니터링 및 졸음상태의 운전자에게 주의를 제공하기 위하여 알람을 제공하는 형태의 지능형 모니터링 시스템을 구현하였다.

• Journal of Power Electronics
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• 제6권4호
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• pp.298-306
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• 2006

A high efficiency and low cost sustain driver for a plasma display panel (PDP) utilizing a current pumping method is proposed. The main concept of the proposed circuit is using the current source to charge and discharge the panel. As a result, all power switches can achieve zero voltage switching (ZVS) and every auxiliary switch can also achieve zero current switching (ZCS). Since the inductor current can compensate for the discharge current, the current stress of all the power switches can be reduced considerably. Furthermore, it has features such as a simpler structure, less mass, lower cost, and lower electromagnetic interference than in previous circuits.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1176-1178
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• 2007

A novel integrated a-Si:H gate driver with high reliability has been designed and simulated. Since the a-Si:H TFT is easily degraded by gate bias stress, we should optimize the circuit considering the threshold voltage shift. The conventional circuit shows voltage drop at the input stage by threshold voltage of the TFT, however, the proposed circuit dose not shows voltage drop and keeps constant regardless of threshold voltage shift of the TFT.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1301-1304
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• 2008

In this study, we used a multiple phase scheme for the clock in the dual-pull-down driver for TFT display panels. In this scheme, the turn-on time for the transistors in the dual-pull-down structure was reduced from 1/2 to 1/4 or 1/8 of the period cycle time. While keeping proper operation of the transistor size of circuit was fine tuned to achieve an optimal performance. The relation between the active time and the transistor dimensions was obtained for the optimal design.

• 재활복지공학회논문지
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• 제6권1호
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• pp.9-15
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• 2012

본 논문에서는 장애인 자가운전을 위한 휠체어 자동탑재기능을 가지는 캐리어를 개발하기 위하여 기구학적 동특성을 분석하고 기구부의 안전성을 고려한 강도 해석을 하였다. 휠체어 자동탑재장치의 실차량 장착 및 크기를 고려한 자가운전용 차량으로는 9인승 승합차량을 선정하였다. 먼저 기구학적 동특성과 구동 방식을 결정하고, 운동 궤적 및 동작 프로세스를 참조하여 캐리어를 적용하고자 하는 승합 차량에 대한 간섭여부를 확인하여 기구학적 개념 설계를 확정하고 기구부의 안전성을 확인하기 위해 강도해석을 통하여 설계의 신뢰성을 검증하였다.