• 전자공학회논문지SC
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• 제41권2호
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• pp.1-8
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• 2004

본 논문은 시간지연을 갖는 2차 시스템에서 시간영역의 설계사양을 만족하는 최적 강인 LQ-PID제어기 설계방법을 제안한다. 시간지연을 갖는 2차 시스템의 LQR 해를 이용한 LQ-PID제어기 파라미터는 설계사양을 만족하는 가격함수의 가중치요소 C와 R에 의해 결정되고, Q와 R의 선정은 시간영역에서의 오버슈트와 정착시간을 조절할 수 있는 설계파라미터들 선정에 의해 결정되어진다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.331-333
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• 1999

Power supply for Nuclear Power Plant was developed, and MMI monitoring circuit was added to the main function of power supply. The developed power supply is designed to show equal or higher performance compared with the existing power supplies. Performance of the power supply is verified by simulations, experiments, and authentication test for Q-class, he status of power supply and fault waveform can be displayed and analyzed on PC by RS-232C port. By adopting the latest parts, mainly domestic models, production cost and delivery can be reduced. Replacement period of capacitor can be extended by life estimation.

• 한국전기전자재료학회논문지
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• 제15권12호
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• pp.1039-1044
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• 2002

Film Bulk Acoustic Resonator (FBAR) using thin piezoelectric films can be made as monolithic integrated devices with compatibility to semiconductor process, leading to small size, low cost and high Q RF circuit elements with wide applications in communications area. This paper presents an MMIC compatible suspended FBAR using SOI micromachining. It is possible to make a single crystal silicon membrane using a SOI wafer In fabricating active devices, SOI wafer offers advantage which removes the substrate loss. FBAR was made on the 12㎛ silicon membrane. Electrode and Piezoelectric materials were deposited by RF magnetron sputter. The maximum resonance frequency of FBAR was shown at 2.5GHz range. The reflection loss, K$^2$$\_$eff/, Q$\_$serise/ and Q$\_$parallel/ in that frequency were 1.5dB, 2.29%, 220 and 160, respectively.

• Advances in aircraft and spacecraft science
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• 제9권5호
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• pp.479-491
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• 2022

This work concerns the investigation of a Q1D methodology employed to study pressure oscillations in solid rocket motors driven by hydrodynamic instabilities. A laboratory-scale solid motor designed to develop vortex-shedding phenomena is analyzed for the whole firing time. The comparison between numerical results and experimental data shows good agreement regarding pressure oscillations signature, especially in the flute-mode behavior, the typical oscillations frequency trend present in any motor liable to hydrodynamic instabilities. Such result ensures the model capability to cope with this particular kind of pressure oscillations source, allowing the investigation of the phenomenon with a lighter and cost savings methodology than CFD simulations.

• 품질경영학회지
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• 제40권2호
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• pp.117-125
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• 2012

For the highly reliable products, an accelerated degradation test (ADT) is a useful tool which has been employed in industry to obtain reliability-related information within an affordable amount of time and cost. In an ADT, as all other reliability tests, it is important to carefully design the ADT beforehand to obtain estimates of the quantities of interest as precisely as possible. In this paper, optimal ADTs are developed assuming that the constant-stress loading method is employed and the degradation characteristic follows a Wiener process. Under the constraint that the total cost does not exceed a pre-specified budget, the stress levels, the number of test units allocated to each stress level and the number of measurement (termination time) are determined such that the asymptotic variance of the maximum likelihood estimator of the q-th quantile of the lifetime distribution at the use condition is minimized.

• 산업공학
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• 제14권2호
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• pp.205-209
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• 2001

The number of tunnel has fast increased with the rapid expansion of highway network. Tunnel should be designed to provide for drivers both safety and pleasant driving conditions. In this perspective, the design for tunnel lightning is very important in order to provide its safety, pleasantness, and cost-efficienty of maintenance, all of which should be considered and analyzed for a better tunnel lighting. This paper attempts to compare the low-pressure sodium lamp, which has usually been used for tunnel lighting, with the fluorescent lamp, which we consider as an alternative for the former. In an effort to determine the number of lamps to meet the required illuminance in the tunnel, this research employs a simulation technique which would allow us to conjecture, with the aid of basic model, the life cycle cost for illumination per each tunnel. This analysis is expected to provide a basic method and related information for tunnel development and design.

• Industrial Engineering and Management Systems
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• 제3권1호
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• pp.59-62
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• 2004

The number of tunnel has fast increased with the rapid expansion of highway network. Tunnel should be designed to provide for drivers both safety and pleasant driving conditions. In this perspective, the design for tunnel lightning is very important in order to provide its safety, pleasantness, and cost-efficiency of maintenance, all of which should be considered and analyzed for a better tunnel lighting. This paper attempts to compare the low-pressure sodium lamp, which have usually been used for tunnel lighting, with the fluorescent lamp, which we consider as an alternative for the former. In an effort to determine the number of lamps to meet the required illuminance in the tunnel, this research employs a simulation technique which would allow us to conjecture, with the aid of basic model, the life cycle cost for illumination per each tunnel. This analysis is expected to provide a basic method and related information for tunnel development and design.

• 한국생활과학회지
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• 제23권2호
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• pp.205-217
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• 2014

This study examined attitudes of grandmothers who had experience in grandchild care in order to explore their subjectivity. Research questions were 1) to categorize the attitudes toward grandchild care, and 2) to analyze each type's characteristics and elucidate the analyses. The results are as follows. Grandmothers' attitudes toward grandchild care were categorized into three types: (1) adjusting-to-role-change type, (2) recognizing-the-role-burdens type, (3) enjoying-the-traditional-role type. Type 1, the adjusting-to-role-change type was aware of positive facets of grandchild care, and actively accepted the caring responsibility, but did not think it was a grandmother's duty to care for the grandchildren or that it was the sole pleasure in a grandmother's life. Type 2, the recognizing-the-role-burdens type, had a negative view regarding grandchild care, perceiving the cost too high relative to the reward. On the other hand, Type 3, the enjoying-the-traditional-role type considered grandchild care as a pleasure and a duty, and downplayed negative aspects such as having no time to herself, assuming the traditional grandmother role and enjoying it. These results imply that the attitudes of grandmothers nowadays are undergoing a change from the traditional grandmother role attitude.

• Journal of Information Processing Systems
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• 제16권5호
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• pp.1223-1230
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• 2020

Recently, extensive studies have been conducted to apply deep learning to reinforcement learning to solve the state-space problem. If the state-space problem was solved, reinforcement learning would become applicable in various fields. For example, users can utilize dance-tutorial systems to learn how to dance by watching and imitating a virtual instructor. The instructor can perform the optimal dance to the music, to which reinforcement learning is applied. In this study, we propose a method of reinforcement learning in which the action space is dynamically adjusted. Because actions that are not performed or are unlikely to be optimal are not learned, and the state space is not allocated, the learning time can be shortened, and the state space can be reduced. In an experiment, the proposed method shows results similar to those of traditional Q-learning even when the state space of the proposed method is reduced to approximately 0.33% of that of Q-learning. Consequently, the proposed method reduces the cost and time required for learning. Traditional Q-learning requires 6 million state spaces for learning 100,000 times. In contrast, the proposed method requires only 20,000 state spaces. A higher winning rate can be achieved in a shorter period of time by retrieving 20,000 state spaces instead of 6 million.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 1995년도 정기총회 및 학술발표회
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• pp.1-26
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• 1995

Key aspects of the Norwegian Method of Tunnelling (NMT) are reviewed. These include a predictive method of support design using the six-parameter Q-system of rock mass characterisation. The rock mass rating or Q-value is updated during tunnel driving. The designed tunnel support generally consists of wet process, steel fibre reinforced shotcrete combined with fully grouted, untensioned rock bolts, Even in poor rock conditions S(fr) + B usually acts as the final rock reinforcement and tunnel lining. Since it is a drained lining, it is very economic compared to cast concrete with membranes. Light, free-standing steel liners are used to prevent water affecting the runnel environment. Rock mass conditions, and hence lining design and cost estimation can be assessed by careful use of seismic surveys. Relationships between the P-wave velocity, the rock mass deformation modulus and the Q-value have recently been established, where tunnel depth, rock porosity and the uniaxial compression strength of the rock are important variables. The rock mass modulus estimate, and simple index testing of the joints, provide the key input which joints are discretely represented (either in two dimensions with the UDEC code or in three dimensions with the 3DEC code) is generally favoured compared to continuum analysis. The latter may give a misleading impression of uniformity and deformations tend to be understimated. Q-system NMT designs of S(fr) + B (fibre reinforced shotcrete and bolting) are numerically checked and adjustments made to bolt capacities and shotcrete thickness if overloading is evident around the modelled profile.