• Smart Structures and Systems
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• 제16권4호
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• pp.743-758
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• 2015

This paper presents an advanced life cycle cost (LCC) analysis of a ground source heat pump (GSHP) system and suggests a smart operation mode with a thermal performance test (TPT) and an energy pile system constructed on the site of the Incheon International Airport (IIA). First, an economic analysis of the GSHP system was conducted for the second passenger terminal of the IIA considering actual influencing factors such as government support and the residual value of the equipment. The analysis results showed that the economic efficiency of the GSHP system could be increased owing to several influential factors. Second, a multiple regression analysis was conducted using different independent variables in order to analyze the influence indices with regard to the LCC results. Every independent index, in this case the initial construction cost, lifespan of the equipment, discount rate and the amount of price inflation can affect the LCC results. Third, a GSHP system using an energy pile was installed on the site of the construction laboratory institute of the IIA. TPTs of W-shape and spiral-coil-type GHEs were conducted in continuous and intermittent operation modes, respectively, prior to system operation of the energy pile. A cooling GSHP system in the energy pile was operated in both the continuous and intermittent modes, and the LCC was calculated. Furthermore, the smart operation mode and LCC were analyzed considering the application of a thermal storage tank.

• Tribology and Lubricants
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• 제26권1호
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• pp.73-77
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• 2010

One of the important trends for condition monitoring in the 21st century is the development of smart sensors that will permit the cost-effective continuous monitoring of key machine equipments. In this study, an integrated in-line oil monitoring sensor assigned for continuous in situ monitoring multiple parameters of oil performance is presented. The sensor estimates oil deterioration based on the information about chemical degradation, total contamination, water content of oil and oil temperature. The oil oxidation is estimated by "chromatic ratio", total contamination is measured by the changes in optical density of oil in three optical wave-bands ('Red', 'Green' and 'Blue') and water content is evaluated as relative saturation of oil by water. In order to evaluate the sensor's effectiveness, the sensor was applied to several used oil samples in steel making industry and the results were compared with those measured by standard test methods.

• 대한음성학회지:말소리
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• 제67호
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• pp.181-193
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• 2008

In this paper, we propose a vocabulary coverage improvement method for embedded continuous speech recognition (CSR) using a part-of-speech (POS) tagged corpus. We investigate 152 POS tags defined in Lancaster-Oslo-Bergen (LOB) corpus and word-POS tag pairs. We derive a new vocabulary through word addition. Words paired with some POS tags have to be included in vocabularies with any size, but the vocabulary inclusion of words paired with other POS tags varies based on the target size of vocabulary. The 152 POS tags are categorized according to whether the word addition is dependent of the size of the vocabulary. Using expert knowledge, we classify POS tags first, and then apply different ways of word addition based on the POS tags paired with the words. The performance of the proposed method is measured in terms of coverage and is compared with those of vocabularies with the same size (5,000 words) derived from frequency lists. The coverage of the proposed method is measured as 95.18% for the test short message service (SMS) text corpus, while those of the conventional vocabularies cover only 93.19% and 91.82% of words appeared in the same SMS text corpus.

• 수면정신생리
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• 제3권1호
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• pp.38-46
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• 1996

The purpose of this study is to investigate the neurocognitive dysfunction and the degree of severity according to the oxygen desaturation in obstructive sleep apnea patients. We performed nocturnal polysomnographic recording and administered 3 Vienna Test System subtest of Reaction unit, Continuous attention and Cognitrone to 11 obstructive sleep patients and 13 controls. The result were as follows: 1) On Continous attentin and Cognitrone, patients with obstructive sleep apnea showed significant lower score on correct answer, higher score on missed answer and prolonged reaction time than control. But, there was no significant difference on Reaction unit between two groups. 2) Among 3 groups divided by degree of oxygen desaturation, there were no significant differences on Reaction unit. As the oxygen saturation decreased however, the obstructive sleep apnea group revealed significantly poor performance score on continuous attention and cognitrone. We suggested that obstructive sleep apnea patients showed disturbed neurocognitive function with complex cognitive process and the severity of neurocognitive dysfunction was also correlated with oxygen desaturation.

• 태양에너지
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• 제11권2호
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• pp.29-33
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• 1991

본 연구는 일차원 열 성능 분석 프로그램인 SERI-RES를 이용하여 우리 고유의 난방 방식이라 할 수 있는 Radiant Floor Heating System의 운전 모드(Operation Modes)에 대한 시뮬레이션을 수행하였다. SERI-RES는 원래 공기 가열식 시스템을 주요 난방 방식으로 작성된 프로그램이라 본 연구의 시뮬레이션을 수행하기 위하여 Source Code에 대한 약간의 수정을 가하였다. 얻은 결과를 분석하여 보면 Radiant Floor Heating System은 그 운용 방법(Operation Modes)에 따라 건물의 동적 열 성능에 상당한 영향을 미치는 것으로 나타났으며 이는 Test Cell에 대한 간단한 실측 실험을 통해서도 확인되었다. SERI-RES는 비록 HVAC 시스템등에 대한 구체적인 시뮬레이션은 불가하나, 비록 일차원적이기는 하지만 Radiant Floor Heating 시스템과 건물의 동적 열 성능에 대한 분석에는 상당히 효율적인 Simulation Model을 제공하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제23권5호
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• pp.687-694
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• 1999

This study was conducted to develop new drying process for automatic control and marine engi-neering system. Air-water tests were carried out to investigate dryer performance. The dispersed flow in he dryer test apparatuses was also simulated by using a numerical code which solves the Dittus-Boelter equation for continuous liquid phase and the Reynolds equation of droplet motion for continuous liquid phase and the Reynolds equation of droplet motion for dispersed phase to predict droplet removal efficiency. Proper conditions for dehumidification were optimized by response ambient conditions. When the selected indexes were constrained in the range of 85-98% moisture content above $15^{\circ}$ and more than mass flow rates of moist air 750kg/h. The numerical results were compared with the experimental data pertaining to the removal effi-ciency at chamber stage and overall pressure drop along concentric tubes Good agreement was obtained as for the efficiency while relatively poor agreement was obtained for the relative humidity. The results also showed that the efficiency depended strongly on the relative humidity at the inlet condition which indicated the importance of estimating the heat exchanger length. Effects of some design parameters in both removal efficiency and breakthrough onset condition are discussed.

• Structural Engineering and Mechanics
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• 제42권6호
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• pp.799-813
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• 2012

Five two-span reinforced concrete (RC) slabs and seven two-span RC beams were tested under the ISO 834 standard fire with different durations. CFRP strengthening was then applied to some of the specimens after the damaged concrete was removed from the specimens and replaced with polymer mortar. All the specimens were loaded to failure to investigate the influence of fire-damage and the effectiveness of strengthening methods. Test results indicated that the flexural capacities of specimens decrease with the fire duration increases. Moreover, fire exposure had more significant effect on the flexural rigidity than on the bearing capacity of the specimens. After rehabilitation, the bearing capacities of specimens reached or even exceeded that of the reference RC specimen, and the strengthening methods seemed to have limited effect on flexural rigidity recovery. From the analysis of moment redistribution of tested beams, elevated temperature is found having different impacts on sagging moment region and hogging moment region. The damage of RC continuous member is definitely a comprehensive response of different regions.

• Steel and Composite Structures
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• 제17권2호
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• pp.173-184
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• 2014

This study aimed to theoretical calculate the thermal residual stress in continuous SiC fiber reinforced titanium matrix composites. The analytical solution of residual stress field distribution was obtained by using coaxial cylinder model, and the numerical solution was obtained by using finite element model (FEM). Both of the above models were compared and the thermal residual stress was analyzed in the axial, hoop, radial direction. The results indicated that both the two models were feasible to theoretical calculate the thermal residual stress in continuous SiC fiber reinforced titanium matrix composites, because the deviations between the theoretical calculation results and the test results were less than 8%. In the titanium matrix composites, along with the increment of the SiC fiber volume fraction, the longitudinal property was improved, while the equivalent residual stress was not significantly changed, keeping the intensity around 600 MPa. There was a pronounced reduction of the radial residual stress in the titanium matrix composites when there was carbon coating on the surface of the SiC fiber, because carbon coating could effectively reduce the coefficient of thermal expansion mismatch between the fiber and the titanium matrix, meanwhile, the consumption of carbon coating could protect SiC fibers effectively, so as to ensure the high-performance of the composites. The support of design and optimization of composites was provided though theoretical calculation and analysis of residual stress.

• Journal of Mechanical Science and Technology
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• 제19권12호
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• pp.2312-2320
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• 2005

The aerodynamic effects of leading-edge accretion can raise important safety concerns since the formulation of ice causes severe degradation in aerodynamic performance as compared with the clean airfoil. The objective of this study is to develop a numerical simulation strategy for predicting the particle trajectory around an MS-0317 airfoil in the test section of the NASA Glenn Icing Research Tunnel and to investigate the impingement characteristics of droplets on the airfoil surface. In particular, predictions of the mean velocity and turbulence diffusion using turbulent flow solver and Continuous Random Walk method were desired throughout this flow domain in order to investigate droplet dispersion. The collection efficiency distributions over the airfoil surface in simulations with different numbers of droplets, various integration time-steps and particle sizes were compared with experimental data. The large droplet impingement data indicated the trends in impingement characteristics with respect to particle size ; the maximum collection efficiency located at the upper surface near the leading edge, and the maximum value and total collection efficiency were increased as the particle size was increased. The extent of the area impinged on by particles also increased with the increment of the particle size, which is similar as compared with experimental data.

• 한국철도학회논문집
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• 제14권2호
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• pp.151-159
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• 2011

본 논문에서는 시공이음 및 세그먼트 연결부 등 불연속 구간을 포함하고 있는 튜브 구조물에 대한 기밀성 평가를 위해 실험에 기초한 연구를 수행하였다. 실제 진공튜브 시스템을 위해 적용 가능한 콘크리트 라이닝을 최대한 모사할 수 있도록 콘크리트 관 1개로 구성된 일체형 튜브(N1) 1기, 동 콘크리트 관 두 개를 연결시킨 연결식 튜브 시험체(N2) 1기, 그리고 콘크리트 세그먼트형 튜브(S) 1기 등 총 3기의 시험체를 제작하여 각 시험체에 대해 내부 기압을 0.1atm로 낮춘 후 시간에 따른 내부 기압의 변화를 측정하였다. 기밀성 실험 결과 얻어진 흐름 곡선으로부터 시스템의 등가 투기계수를 산출하였는데 이음부가 많을수록 시스템의 등가투기계수는 높아지는 경향을 보였다. 또한 실험 결과를 바탕으로 가정된 튜브 단면 변화에 따른 기밀성의 민감도를 해석적으로 분석하였는데 튜브 구조물의 두께 및 직경이 커질수록 시스템 기밀성이 더 향상될 뿐 아니라 기밀성 보강의 효과가 더욱 커진다는 것을 알 수 있었다.