• ETRI Journal
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• 제26권5호
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• pp.423-431
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• 2004

In earlier works on transmitter power control in cellular radio systems, the problem of whether a signal-to-interference ratio (SIR) threshold is achievable is determined by apparently different rules for homogeneous and heterogeneous SIR systems. In this paper, we present a unified and more universal framework for both cases. We also highlight the conditions under which a given SIR threshold vector for the heterogeneous SIR system is achievable, although so far there is no general solution to this problem.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1119-1120
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• 2010

• Bulletin of the Korean Chemical Society
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• 제26권12호
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• pp.2084-2086
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• 2005

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2004년도 추계 기술심포지움 초록집
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• pp.23-23
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• 2004

• 천문학회지
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• 제29권spc1호
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• pp.181-182
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• 1996

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권4호
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• pp.332-342
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• 2017

Purpose: In this study, the lifetime distribution of a k-out-of-n system with heterogeneous components is suggested as Markov model, and the time-to-failure (TTF) distribution of each component is considered as phase-type distribution (PHD). Furthermore, based on the model, a redundancy allocation problem with a mix of components (RAPMC) is proposed. Methods: The lifetime distribution model for the system is formulated by the structured Markov chain. From the model, the various information on the system lifetime can be ascertained by the matrix-analytic (or-geometric) method. Conclusion: By the generalization of TTF distribution (PHD) and the consideration of heterogeneous components, the lifetime distribution model can delineate many real systems and be exploited for developing system operation policies such as preventive maintenance, warranty. Moreover, the effectiveness of the proposed RAPMC is verified by numerical experiments. That is, under the equivalent design conditions, it presented a system with higher reliability than RAP without component mixing (RAPCM).

• 한국환경과학회지
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• 제22권10호
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• pp.1263-1271
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• 2013

Graphene oxide (GO)-titania composites have emerged as an attractive heterogeneous photocatalyst that can enhance the photocatalytic activity of $TiO_2$ nanoparticles owing to their potential interaction of electronic and adsorption natures. Accordingly, $TiO_2$-GO mixtures were synthesized in this study using a simple chemical mixing process, and their heterogeneous photocatalytic activities were investigated to determine the degradation of airborne organic pollutants (benzene, ethyl benzene, and o-xylene (BEX)) under different operational conditions. The Fourier transform infrared spectroscopy results demonstrated the presence of GO for the $TiO_2$-GO composites. The average efficiencies of the $TiO_2$-GO mixtures for the decomposition of each component of BEX determined during the 3-h photocatalytic processes were 26%, 92%, and 96%, respectively, whereas the average efficiencies of the unmodified $TiO_2$ powder were 3%, 8%, and 10%, respectively. Furthermore, the degradation efficiency of the unmodified $TiO_2$ powder for all target compounds decreased during the 3-h photocatalytic processes, suggesting a potential deactivation even during such a short time period. Two operational conditions (air flow entering into the air-cleaning devices and the indoor pollution levels) were found to be important factors for the photocatalytic decomposition of BEX molecules. Taken together, these results show that a $TiO_2$-GO mixture can be applied effectively for the purification of airborne organic pollutants when the operating conditions are optimized.

• 드라이브 ㆍ 컨트롤
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• 제17권3호
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• pp.1-8
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• 2020

Recently, a special purpose machine with two manipulators and quadruped crawler system has been developed for rapid life-saving and initial restoration work at disaster sites. This special purpose machine provides the driver with various environmental recognition functions for accurate and rapid task determination. In particular, the human detection technology assists the driver in poor working conditions such as low-light, dust, water vapor, fog, rain, etc. to prevent secondary human accidents when moving and working. In this study, a human detection module is developed to be mounted on a special purpose machine. A thermal sensor and CCD camera were used to detect victims and nearby workers in response to the difficult environmental conditions present at disaster sites. The performance of various AI-based life detection algorithm were verified and then applied to the task of detecting various objects with different postures and exposure conditions. In addition, image visibility improvement technology was applied to further improve the accuracy of human detection.

• 한국해양공학회지
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• 제17권5호
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• pp.82-87
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• 2003

A practical method to investigate the sharing architecture of FMS, for small and medium enterprises, on distributed heterogeneous environmental conditions is investigated. Because the industrial FMS model requires a reasonable size for actual work-site flexible operation, the initial facility expense is very heavy. The support for flexible cooperation of FMS, with some external different FMS, can reduce expenditures and provide greater functionality. While most FMS provide their operation process using an adequate mechanism, when used in isolation, such as island of automation, there is increasing demand for FMS that can cooperate. By exchanging intermediate products and information with other external FMS, products can be produced that cannot be produced alone, such as those that require various processes. This study first considers the sharing architecture of FMS for small and medium enterprises, and investigates the effects of the general sharing architecture of FMS on distributed heterogeneous environments, by using transducer approach to agentification. In this study, set-up station or in-out station takes charge of the gateway of intermediate products, and routes them among distributed heterogeneous FMS plants. The transducer approach is applied to web agent and set-up agent established interfaces, with system controller and setup controller. In this study, the FMS-established sharing architecture is able to obtain not only the internal flexibility, but also the external flexibility.

• 멤브레인
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• 제25권5호
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• pp.431-439
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• 2015

이 연구는 양이온 불균질막을 제조하기 위해 PVdF와 상용 양이온교환수지를 배합하여 제조하고 최적의 조건제시 및 기존 상용화막과 비교 평가하였다. 연구결과 불균질막이 기존의 상용화막보다 이온교환용량, 전기저항, 함수율 부분에서 높은 물성을 나타내기 위해서는 이온교환수지의 무게 비율을 40% 이상 첨가해야 한다는 것을 확인하였다. 인장강도가 상용화막보다 높기 위해서는 이온교환수지의 무게 비율을 50% 이하로 첨가해야 한다는 것을 확인하였다. 따라서 화학적 특성과 기계적 특성을 고려했을 때, PVdF와 이온교환분말의 최적 비율은 60 : 40이며, 이때의 전기저항 $1.82{\Omega}{\cdot}cm^{-1}$, 함수율 79%, 이온교환용량 1.60 meq/g으로 측정되었고 기계적 강도는 0.97 MPa로 측정되었다. 이때, TDS 제거율은 약 40%로 측정되었다.