• 한국학교보건학회지
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• 제25권1호
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• pp.85-94
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• 2012

Purpose: The purpose of this study was to investigate the stress, coping and suicidal ideation among school-aged children and provide evidence for developing a stress management program for them. Methods: Data were collected and analyzed from 308 fifth graders from 6 elementary schools located in Daegu/Gyeongbuk. Results: First, for stress by general characteristics, there were significant differences in economic status, school record, self-rated health and life satisfaction. Also, subcategory stress by gender, there was a significant difference in appearance stress. Second, passive/avoidant coping had a significant difference in gender. Social support seeking coping and passive/avoidant coping were significant differences in economic status. Active coping had a significant difference in school record. Passive/avoidant coping had a significant difference in self-rated health. Aggressive coping, active coping, social support seeking coping and passive/avoidant coping had significant differences in self-rated life satisfaction. Third, stress and coping had significant differences by suicidal ideation. Fourth, stress showed positive correlations with aggressive coping and passive/avoidant coping while revealing negative correlation with active coping. Conclusion: These results from the study suggest difference by gender and need more active and positive coping strategy for suicide prevention.

• 가정과삶의질연구
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• 제8권1호
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• pp.69-82
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• 1990

The purposes of this are to figure out the amounts of leisure time of full-time homemakers and to find out leisure time factors contributed to raise the quality of life. The major findings are the followings: 1) Full-time homemakers spend 353 minutes(5.9 hours) on the average per day on the leisure. Time for active leisure(creative activities, sports activities, spectator events, going to the party, and so on) is 70 minutes, while that for passive leisure(watching TV. listening to the radio, reading newspapers. magazines. Books, chating, relaxing, card playing) is 283 minutes(4.7 hours). The passive leisure is the main type of spending leisure time. 2) The total leisure time of wives is significantly related to SES factors. The higher the wives age and education, the family income, and the age of the latest child, the more the wives total leisure time. But the more the family numbers, and the child numbers, the lower the leisure time. Active leisure time is highly rela ed to family income, while passive leisure time is considerably family composition. 3) The wives are mostly satisfied with their lives. The wives perceptions of the quality of life is related to wives's education, house type, and family income. 4) The wives total leisure time is not related to the quality of life. There is a positive correlation between active leisure time and the quality of life, while a negative relationship is between passive leisure time and the perception of the quality of life. 5) In analysis of causal model, it appears that family income and active leisure time of wives directly affect the perceived quality of life. The more the family income and active leisure time, the higher the quality of life. it is implicated for wives to take and active attitude and to reduce, if possible, passive leisure time and to increase active leisure time.

• 대한환경공학회지
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• 제33권11호
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• pp.790-796
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• 2011

본 연구에서는 시화지구의 공단과 주거 지역에서의 휘발성 유기화합물 농도를 능동식과 수동식 시료채취기를 이용해 측정하고 그 특성을 비교 분석하였다. TVOC의 평균농도는 패시브샘플러(passive sampler)의 경우 공단지역이 주거지역보다 1.86배 더 높게 나타났다. 능동식 시료채취기의 경우 공단지역이 주거지역보다 1.07배 더 높게 나타났다. Passive sampler를 이용하였을 경우 공단지역이 주거지역보다 대부분의 물질에서 농도가 높게 나타났지만 열탈착 흡착 튜브(thermal desorption tube)를 이용했을 경우는 트리클로로에틸렌, 톨루엔, 에틸벤젠, 자일렌 등 일부 물질의 농도에 있어서 주거지역이 오히려 높게 나타났다. 전체 BTEX 비율 중에서 전반적으로 톨루엔이 차지하는 비율이 가장 컸으며, passive sampler의 경우 공단지역이 주거지역보다 톨루엔, 에틸벤젠, 자일렌의 상대비율이 높게 나타났다. 그러나 열탈착 흡착 튜브의 경우는 오히려 주거지역이 더 높게 나타났다. 본 연구를 통해서 대기오염 목적성분의 시간적, 공간적 농도 특성 파악을 위한 passive sampler를 이용하면 오염관리 혹은 역학적 연구에 도움이 되는 적절한 시료채취 방법이라는 사실을 알 수 있었다.

• Smart Structures and Systems
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• 제16권5호
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• pp.807-833
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• 2015

While tuned mass dampers are found to be effective in suppressing vibration in a tall building, integrating it with a semi-active control system enables it to perform more efficiently. In this paper a forty-story tall steel-frame building designed according to the Canadian standard, has been studied with and without semi-active and passive tuned mass dampers. The building is assumed to be located in the Vancouver, Canada. A magneto-rheological fluid based semi-active tuned mass damper has been optimally designed to suppress the vibration of the structure against seismic excitation, and an appropriate control procedure has been implemented to optimize the building's semi-active tuned mass system to reduce the seismic response. Furthermore, the control system parameters have been adjusted to yield the maximum reduction in the structural displacements at different floor levels. The response of the structure has been studied with a variety of ground motions with low, medium and high frequency contents to investigate the performance of the semi-active tuned mass damper in comparison to that of a passive tuned mass damper. It has been shown that the semi-active control system modifies structural response more effectively than the classic passive tuned mass damper in both mitigation of maximum displacement and reduction of the settling time of the building.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.240-241
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• 2009

The method of the reduction of the duct noise can be classified by the method of passive control and the method of active control. However, the passive control method has a demerit to reduce the effect of noise reduction at low frequency (below 500Hz) range and to be limited by a space. Whereas, the active control method can overcome the demerit of passive control method. The algorithm of active control is mostly used the Least-Mean-Square (LMS) algorithm because the LMS algorithm can easily obtain the complex transfer function in real-time. Especially, When the Filtered-X LMS (FXLMS) algorithm is applied to an ANC system.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.631-640
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• 2016

A dual-mode power management for a hybrid-electric UAV with a cruise power of 200W is proposed and empirically verified. The subject vehicle is a low-speed long-endurance UAV powered by a solar cell, a fuel cell, and a battery pack, which operate in the same voltage bounds. These power sources of different operational characteristics can be managed in two different methods: passive management and active management. This study proposes a new power management system named PMS2, which employs a bypass circuit to control the individual power sources. The PMS2 normally operates in active mode, and the bypass circuit converts the system into passive mode when necessary. The output characteristics of the hybrid system with the PMS2 are investigated under simulated failures in the power sources and the conversion of the power management methods. The investigation also provides quantitative comparisons of efficiencies of the system under the two distinct power management modes. In the case of the solar cell, the efficiency difference between the active and the passive management is shown to be 0.34% when the SOC of the battery is between 25-65%. However, if the SOC is out of this given range, i.e. when the SOC is at 90%, using active management displays an improved efficiency of 6.9%. In the case of the fuel cell, the efficiency of 55% is shown for both active and passive managements, indicating negligible differences.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.338-345
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• 2002

This paper presents a hybrid control strategy for seismic protection of a benchmark cable-stayed bridge, which is provided as a testbed structure for the development of strategies for the control of cable-stayed bridges. In this study, a hybrid control system is composed of a passive control system to reduce the earthquake-induced forces in the structure and an active control system to further reduce the bridge responses, especially deck displacements. Lead rubber bearings and ideal hydraulic actuators are used fur the passive and active control systems. Bouc-Wen model is used to simulate the nonlinear behavior of lead rubber bearings and an H₂/LQG control algorithm is adopted as an active control algorithm. Numerical simulation results show that the performance of the proposed hybrid control strategy is superior to that of the passive control strategy and slightly better than that of the active control strategy. The proposed control method is also more reliable than the fully active control method due to the passive control part. Therefore, the proposed hybrid control strategy can effectively be used to seismically excited cable-stayed bridges.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.176-179
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• 2005

To control the vibration transmitted to the precision instruments from ground has always been of great interest among the researchers. This paper proposes a single axis vibration isolation system which can be used as a module far a table top six axis isolator for highly precise measurement and actuation system. The combined active-passive isolation principle is used for vertical vibration isolation by mounting the instrument on a passively damped isolation system made of Elastomer along with the active stage in series which consists of very stiff piezo actuator. The active stage works in combination with the passive stage for working as a very low frequency vibration attenuator. The active stage is isolated from the payload disturbance through the Passive stage and thus modularity in control is achieved. This made the control algorithm much easier as it does not need to be tuned to specific payload.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.676-682
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• 2019

After the Fukushima Daiichi accident, there has been an increasing preference for passive safety features in the nuclear power industry. Some passive safety systems require limited active components to trigger subsequent passive operation. Under very serious accident conditions, passive safety features could be rendered inoperable or damaged. This study evaluates (i) the performance and effectiveness of the passive safety features of iPOWER (innovative Power Reactor), and (ii) whether a severe accident condition could be reached if the passive safety systems are damaged, namely the case of heat exchanger tube rupture. Analysis results show that the reactor coolant system remains in the hot shutdown condition without operator actions or electricity for over 72 h when the passive auxiliary feedwater systems (PAFSs) are operable without damage. However, heat exchanger tube rupture in the PAFS leads to core damage after about 18 h. Such results demonstrate that, to enhance the safety of iPOWER, maintaining the integrity of the PAFS is critical, and therefore additional protections for PAFS are necessary. To improve the reliability of iPOWER, additional battery sets are necessary for the passive safety systems using limited active components for accident mitigation under such extreme circumstances.

• 산업기술연구
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• 제23권A호
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• pp.35-39
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• 2003

There are many kinds of electronic ballast for various kinks of fluorescent lamps. The PFC(Power Factor Correction) circuit in electronic ballast is classified in two types. One is the active PFC and the other is the passive PFC circuit. The active type PFC is higher than the passive type, but the cost of the passive type is cheaper than the active type. In this study, we introduced the modified passive PFC method which is called semi-boost PFC, and then we analyzed and experimented the electronic ballast which is composed of the semi-boost PFC, half-bridge, and LCC resonant tank. Experimental results showed that the $$PF{\geq_-}0.98$$, $$CF{\leq_-}1.4$$ and input current $THD{\approx}15%$.