• 한국물환경학회지
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• 제21권4호
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• pp.353-359
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• 2005

This study was conducted to evaluate the operation characteristics with aeration time in intermittent aeration membrane bioreactor. The BOD removal efficiency rate of this process was over than 97% regardless of aeration on/off time. To get over than 82% of nitrogen removal efficiency rate, aeration off time needs more than 70 minutes in reactor. Specific denitrfication rate was 2.68 mg $NO_3-N/gMv/hr$ in 40/80 min aeration on/off time, was 2.6 times more than 60/60 min, and 1.4 times more than 50/70 min in 6,300 mg/L of MLSS concentration. Specific nitrification rate was 1.96 mg $NH_4-N/gMv/hr$ in 50/70 min, was 1.4 times more than 40/80 min, but it was effectded little upon nitrification. Microbial activity was effected little according to aeration on/off time, oxygen demend was reduced according to aeration off time increased and microbial concentration increased. The longer aeration off time become, the higher Extraceller Pollymeric Substance (EPS), 50/70 min and 40/80 min in aeration on/off time was increased 1.6 times and 2.7 times, respectively more than 60/60 min because of increase of operation pressure.

• Architectural research
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• 제11권2호
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• pp.43-49
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• 2009

Since the late 1980s, the schedule technique applied to the construction industry around the world has rapidly changed from the traditional ADM (Arrow Diagramming Method) to the PDM (Precedence Diagramming Method) technique. The main reason for this change is to overcome the limits and inconveniences of the traditional ADM technique. The time-cost trade-off is one of the core scheduling techniques to establish the best optimized combination plan in terms of a relationship between the cost and schedule. However, most of the schedule-related textbooks and research papers have discussed and proposed applications of a time-cost trade-off technique based only on the Finish to Start relationship. Therefore, there are almost no consideration and discussion of problems or restrictions that emerge when the time-cost trade-off technique is applied to the PDM network that has overlapping relationships. This paper proposes the lead-time adjustment method as a methodology for overcoming some restrictions that are encountered when the time-cost trade-off technique is applied to the overlapping relationships of the PDM network.

• 대한인간공학회지
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• 제18권3호
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• pp.27-39
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• 1999

The purpose of this study was to approve the capability of human sensibility evaluation based on physiological responses and real-time subjective assessments. Three well-trained healthy human subjects were participated in the experiments. We measured physiological responses such as Heart Rate Variability(HRV), Galvanic Skin Response(GSR) and skin temperature under rest and visual stimulation conditions, respectively. Off-time subjective assessments were recorded before and after visual stimulations. Real-time subjective assessments were recorded during visual stimulations. The results of physiological responses and off-time and real-time subjective assessments were quantified and compared. The results showed that the correlation between physiological responses and real-time subjective assessments was high (83%) for both the positive and negative visual stimulation. The correlation between the physiological responses and off-time subjective assessments was high (83%) for the negative visual stimulation but was low (15%) for the positive visual stimulation. Although the current observation is preliminary and requires more careful experimental study, it appears that the correlation between real-time subjective assessment and physiological responses is higher than that of the off-time subjective assessment and physiological responses.

• 대한전자공학회논문지TC
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• 제48권5호
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• pp.33-39
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• 2011

두명의 사용자를 위한 무선 통신에서 심볼 간 간섭 및 다중 접속 간섭을 최소화하는 유동적인 전송률 back-off 적용 지연 time reversal (TR) 기법의 성능을 평가하였다. 지연 TR 기법의 성능을 기존 full-rate TR과 full back-off TR의 성능과 비교하였으며, guard interval이 1보다 큰 경우 비트오차율 측면에서 지연 TR 기법의 성능이 full-rate TR이나 full back-off TR보다 우수함을 확인하였다.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.501-506
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• 2022

Long turn-off time limits high frequency operation of Bipolar Junction Transistors (BJTs). Turn-off time decreases with increases in the recombination rate of minority carriers at switching transients. Fast neutron irradiation on a Si BJT incurs lattice damages owing to the displacement of silicon atoms. The lattice damages increase the recombination rate of injected holes with electrons, and decrease the hole lifetime in the base region of pnp Si BJT. Fast neutrons generated from a beryllium target with 30 MeV protons by an MC-50 cyclotron were irradiated onto pnp Si BJTs in experiment. The experimental results show that the turn-off time, including the storage time and fall time, decreases with increases in fast neutron fluence. Additionally, it is confirmed that the base current increases, and the collector current and base-to-collector current amplification ratio decrease due to fast neutron irradiation.

• ETRI Journal
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• 제42권1호
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• pp.46-53
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• 2020

Gait analysis is an effective clinical tool across a wide range of applications. Recently, inertial measurement units have been extensively utilized for gait analysis. Effective gait analyses require good estimates of heel-strike and toe-off events. Previous studies have focused on the effective device position and type of triaxis direction to detect gait events. This study proposes an effective heel-strike and toe-off detection algorithm using a smart insole with inertial measurement units. This method detects heel-strike and toe-off events through a time-frequency analysis by limiting the range. To assess its performance, gait data for seven healthy male subjects during walking and running were acquired. The proposed heel-strike and toe-off detection algorithm yielded the largest error of 0.03 seconds for running toe-off events, and an average of 0-0.01 seconds for other gait tests. Novel gait analyses could be conducted without suffering from space limitations because gait parameters such as the cadence, stance phase time, swing phase time, single-support time, and double-support time can all be estimated using the proposed heel-strike and toe-off detection algorithm.

• 대한방사선기술학회지:방사선기술과학
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• 제1권1호
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• pp.37-43
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• 1978

This Study was conducted, during the period of 8-16th, August in 1977 and 27th, January through 2, Feburury in 1978, to measure laking off and on time for patient's clothes at the radiologic department in general hospitals. The study dealt with three general hospitals which were classified into groups by ownerships; two university hospitals, one private hospitals. The scope of the study was limited to measurement's of taking off and on time except taking a radiograph. The results were summarized as follows: [1] In Summer, the average taking off ana on tine for male was 3 minutes and 7 seconds and 3 minutes and 43 seconds for female. The latter was longer than that for the former. [2] In Winter, the mean taking off and on time for male was 3 minutes 42 seconds, 4 minutes 17 seconds for female. [3] In this respect, the average taking off and on time for female was longer than that for male and that for winter was expended that for summer. [4] In Summer, regardless of age group and sex, the average taking off and on time for taking a radiograph was 3 minutes 25 seconds, and 3 minuteds 59 seconds in Winter. [5] Regardless of season, sen, and age, the mean time expended to take off and on for taking a radiograph was 3 minutes 43 seconds.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.49-52
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• 2003

IEEE 802.11 MAC uses a distributed coordination function (DCF) known as carrier sense multiple access with collision avoidance (CSMA/CA) for medium access. Random back-off algorithm helps to avoid the collision. This paper proposes virtual back-off and modified back-off algorithm for reduce a waiting time by back-off and reduce the collision. The modified DCF is consisted of these two algorithms. We expect to reduce the average waiting time of each transmission by using the modified DCF algorithm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.820-825
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• 1996

This paper is concerned with effective operating method of pneumatic on-off valves for improving position control accuracy, valve life-time and position settling time using modified pulse width modulation with dead-zone. The pneumatic system using on-off valves studied in this paper has advantage of simple construction and low cost compared with a system with servo-valves. The performance of proposed control system is investigated experimentally for the position control of a pneumatic cylinder using on-off valves. Experimental results show that the proposed algorithm for valve operation can be used to obtain fast and accurate position control and to prevent on-off valves from unnecessary switching.

• 대한전기학회논문지
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• 제43권2호
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• pp.244-250
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• 1994

This paper presents the design of a new turn-off gate drive circuit for GTO which can accomplish faster turn-off switching. The major disadvantage of the conventional turn-off gate drive technique is that it has a difficulty in realizing high negative diS1GQT/dt because of VS1RGM(maximum reverse gate voltage) and stray inductances of turn-off gate drive circuit[1~2]. The new trun-off gate drive technique can overcome this problem by adding another turn-off gate drive circuit to the conventional turn-off gate drive circuit. Simulation and experimental results of the new turn-off gate drive circuit in conjunction with chopper circuit verify a faster turn-off switching performance.