• 조명전기설비학회논문지
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• 제26권12호
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• pp.44-49
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• 2012

The earth leakage circuit-breakers installed to protect the human body against electrical shock have conventionally had a sensitivity current of 30 mA and an operating time of 30 ms or less. No reviews are found, however, on the operating time of the current conducting through the human body due to the electrical shock or ground fault. This paper measures the trip-operating time against the earth leakage under the condition of increased current as well as under the condition of rated sensitivity current of the earth leakage circuit-breakers. Further measurement with a prototype model showed an improved operating time of 16 ms or less under the condition of rated sensitivity current. It is expected that development of circuit-breakers with higher safety is possible if the performance of the electronic circuit can be improved.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1002-1011
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• 2013

This paper proposes the new adaptive protection algorithm for inverse-time overcurrent relays (OCRs) to ensure their proper operating time and protective coordination. The application of the proposed algorithm requires digital protection relays with microcontroller and memory. The operating parameters of digital OCRs are adjusted based on the available data whenever system conditions (system with distributed generation (DG)) vary. Moreover, it can reduce the calculation time required to determine the operating parameters for achieving its purpose. To verify its effectiveness, several case studies are performed in time-domain simulation. The results show that the proposed adaptive protection algorithm can keep the proper operating time and provide the protective coordination time interval with fast response.

• 산업경영시스템학회지
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• 제38권1호
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• pp.21-29
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• 2015

A steady-state controllable M/G/1 queueing model operating under the {T:Min(T,N)} policy is considered where the {T:Min(T,N)} policy is defined as the next busy period will be initiated either after T time units elapsed from the end of the previous busy period if at least one customer arrives at the system during that time period, or after T time units elapsed without a customer' arrival, the time instant when Nth customer arrives at the system or T time units elapsed with at least one customer arrives at the system whichever comes first. After deriving the necessary system characteristics including the expected number of customers in the system, the expected length of busy period and so on, the total expected cost function per unit time for the system operation is constructed to determine the optimal operating policy. To do so, the cost elements associated with such system characteristics including the customers' waiting cost in the system and the server's removal and activating cost are defined. Then, procedures to determine the optimal values of the decision variables included in the operating policy are provided based on minimizing the total expected cost function per unit time to operate the queueing system under considerations.

• 산업경영시스템학회지
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• 제37권1호
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• pp.96-103
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• 2014

A steady-state controllable M/G/1 queueing model operating under the (TN) policy is considered where the (TN) policy is defined as the next busy period will be initiated either after T time units elapsed from the end of the previous busy period if at least one customer arrives at the system during that time period, or the time instant when Nth customer arrives at the system after T time units elapsed without customers' arrivals during that time period. After deriving the necessary system characteristics such as the expected number of customers in the system, the expected length of busy period and so on, the total expected cost function per unit time in the system operation is constructed to determine the optimal operating policy. To do so, the cost elements associated with such system characteristics including the customers' waiting cost in the system and the server's removal and activating cost are defined. Then, the optimal values of the decision variables included in the operating policies are determined by minimizing the total expected cost function per unit time to operate the system under consideration.

• 대한전기학회논문지:전력기술부문A
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• 제52권8호
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• pp.457-462
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• 2003

This paper presents an optimal operating strategy of distributed generation (DG) with reliability worth evaluation of distribution systems. Using DG for peak-shaving unit could reduce the overall system operating cost, and using DG for standby power unit could reduce the customer interruption cost. If DG operating cost is less than utility power cost in peak time, DG should be running to reduce the overall system operating cost. When customer interruption cost enlarges, however, standby power strategy may be the better operating strategy than peak-shaving strategy. Selection of whether DG should be operated for peak-shaving or for standby power, needs the accurate reliability worth evaluation and the accurate power cost evaluation. Instead of using annual average reliability worth, the concept of hourly reliability worth is introduced in this paper to determine the optimal operating decision of DG. Applying suggested hourly reliability worth, the distribution companies that possess DG could set up the optimal operating strategy of DG.

• 한국가스학회지
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• 제7권4호
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• pp.20-23
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• 2003

공정설비의 신뢰도분석은 자주 Weibull 분포에 기초를 둔 모델을 사용한다. 여기에 사용되는 매개변수들은 조업조건의 함수로서 실험에 의해 값이 결정되며 이를 토대로 신뢰도, 평균수명 및 표준편차를 계산한다 이때 기존 방법은 조업조건이 일정하다고 가정하고 이 매개변수들을 상수로 취급한다. 본 논문에서는 척도모수가 시간의 함수일 때 적용할 수 있는 신뢰도함수 및 이를 토대로 한 분석기법을 제안한다. 냉각팬에 대한 사례연구 결과 평균조업조건을 적용한 기존 방법과 큰 차이를 보였다. 제안된 방법은 다른 공정설비들에도 적용 가능하며 조업조건변화가 설비신뢰도에 미치는 영향을 효과적으로 고려할 수 있을 것으로 기대된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.184-186
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• 2007

Currently many sensors and processing data in a robot based on USN environments need to real-time features. In this paper, we examine recent research trends on real-time operating systems, especially on real-time embedded Linux, RTAI and Xenomai, for intelligent robots. Xenomai is a real-time development framework and have special feature supporting RTAI, VxWorks, pSOS+ etc. through the "skin". This research gives a guide to researcher in using real-time embedded Linux in the sense of architecture, supporting real-time mechanisms, kinds of real-time device driver, performances.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.285-288
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• 1998

In this paper, we present mSROS(Micro-Scalable Realtime Operating System) to be applied commonly to the device controller systems in the HANbit ACE256 system. The device controller systems in HANbit ACE256 system are organized as many kinds of device controller. Applying modified PPOS(Peripheral Processor Operating System)which is an operating system for devices of the TDX-10 switching system to the firmwares for them, the inefficiency in development and maintenance exists inherently. To remove the inefficiency nd to improve the performqance of firmwares, we build a common operating system platform that including multi-tasking microkernel so that the firmwares among devices can acquire convenient development and cheap cost of maintencance. Especially, building a virtual machine as a development methodology, it is possible to remove dependency from the kernel so that any kinds of commercial real-time kernels can be used in mSROS as a basic kernel. The virtual machine in mSROS is compatible with the API of SROS(Scalable Realtime Operating System), PPOS, and CROS(Concurrent Realtime Operating System).

• Archives of Plastic Surgery
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• 제50권1호
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• pp.125-129
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• 2023

Three-dimensional (3D) video exoscopes are high-magnification stereo cameras that project onto monitors mounted in the operating room, viewable from different angles. Outside of plastic surgery, exoscopes have been shown to successfully improve the ergonomics of microsurgery, though sometimes with prolonged operating times. We compare a single surgeon's early experience performing free flap procedures from 2020 to 2021 using either a binocular microscope or a 3D video exoscope. Ten procedures were performed with the standard operating microscope and 8 procedures with the 3D exoscope. The microsurgeon, having minimal prior experience using an exoscope, reported less neck discomfort following the free flap procedures performed with the exoscope compared with the binocular surgical microscope. Total average operating time was comparable between the standard surgical microscope and the 3D exoscope (13.7 vs. 13.4 hours, p = 0.34). Our early experience using a 3D exoscope in place of a standard optical microscope demonstrated that the exoscope shows promise, offering an ergonomic alternative during microvascular reconstruction without increasing overall operating times. Future studies will compare free flap ischemia time between cases performed using the exoscope and the conventional binocular microscope. Medical Subject Headings authorized following words: free tissue flaps; operating rooms; ergonomics; microsurgery.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2003년도 봄 학술발표논문집 Vol.30 No.1 (A)
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• pp.226-228
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• 2003

실시간 운영체제(Real-Time Operating System)는 그 실행환경상 시스템이 예상치 못한 특정 이벤트가 발생하는 악 조건속에서도 태스크 수행의 데드라인을 초과하지 않도록 시간적인 측면의 determinism을 보장하는 안정된 스케줄링 기능을 갖춘 운영체제이다. 또한, 예상치 못한 fault 를 미연에 방지할 수 있는 장치를 가지고 있어야 한다. 본 논문에서는 예상치 못한 fault 를 미연에 방지하기 위하여 필요한 운영체제를 설계 및 구현하는데 그 목적이 있다.