• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2007년도 한국우주과학회보 제16권2호
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• pp.37-37
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• 2007

• Structural Engineering and Mechanics
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• 제25권5호
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• pp.577-596
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• 2007

Recent development of fiber optic sensor technology has provided an excellent choice for civil engineers for performance monitoring of civil infrastructures. Fiber optic sensors have the advantages of small dimensions, good resolution and accuracy, as well as excellent ability to transmit signal at long distances. They are also immune to electromagnetic and radio frequency interference and may incorporate a series of interrogated sensors multiplexed along a single fiber. These advantages make fiber optic sensors a better method than traditional damage detection methods and devices to some extent. This paper provides a review of recent developments in fiber optic sensor technology as well as some applications of fiber optic sensors to the performance monitoring of civil infrastructures such as buildings, bridges, pavements, dams, pipelines, tunnels, piles, etc. Existing problems of fiber optic sensors with their applications to civil structural performance monitoring are also discussed.

• Structural Engineering and Mechanics
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• 제26권4호
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• pp.377-392
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• 2007

A discrete sliding mode control (SMC) method based on hybrid model of neural network and nominal model is proposed to reduce the vibration of flexible structures, which is a robust active controller developed by using a sliding manifold approach. Since the thick boundary layer will reduce the virtue of SMC, the multilayer feed-forward neural network is adopted to model the uncertainty part. The neural network is trained by Levenberg-Marquardt backpropagation. The design objective of the sliding mode surface is based on the quadratic optimal cost function. In course of running, the input signal of SMC come from the hybrid model of the nominal model and the neural network. The simulation shows that the proposed control scheme is very effective for large uncertainty systems.

• Computers and Concrete
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• 제4권1호
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• pp.19-32
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• 2007

This paper is concentrated on the behaviors of five different types of fiber reinforced concrete (FRC) in uniaxial tension and flexural impact. The complete stress-strain responses in tension were acquired through a systematic experimental program. It was found that the tensile peak strains of concrete with micro polyethylene (PEF) fiber are about 18-31% higher than that of matrix concrete, those for composite with macro polypropylene fiber is 40-83% higher than that of steel fiber reinforced concrete (SFRC). The fracture energy of composites with micro-fiber is 23-67% higher than that of matrix concrete; this for macro polypropylene fiber and steel fiber FRCs are about 150-210% and 270-320% larger than that of plain concrete respectively. Micro-fiber is more effective than macro-fiber for initial crack impact resistance; however, the failure impact resistance of macro-fiber is significantly larger than that of microfiber, especially macro-polypropylene-fiber.

• Communications for Statistical Applications and Methods
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• 제14권3호
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• pp.483-495
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• 2007

In a general fractional factorial design, the n-levels of a factor are coded by the $n^{th}$ roots of the unity. Pistone and Rogantin (2007) gave a full generalization to mixed-level designs of the theory of the polynomial indicator function using this device. This article discusses the optimal blocking scheme for nonregular designs. According to hierarchical principle, the minimum aberration (MA) has been used as an important criterion for selecting blocked regular fractional factorial designs. MA criterion is mainly based on the defining contrast groups, which only exist for regular designs but not for nonregular designs. Recently, Cheng et al. (2004) adapted the generalized (G)-MA criterion discussed by Tang and Deng (1999) in studying $2^p$ optimal blocking scheme for nonregular factorial designs. The approach is based on the method of replacement by assigning $2^p$ blocks the distinct level combinations in the column with different blocks. However, when blocking level is not a power of two, we have no clue yet in any sense. As an example, suppose we experiment during 3 days for 12-run Plackett-Burman design. How can we arrange the 12-runs into the three blocks? To solve the problem, we apply G-MA criterion to nonregular mixed-level blocked scheme via the mixed-level indicator function and give an answer for the question.

• International Journal of Quality Innovation
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• 제8권2호
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• pp.100-114
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• 2007

Decision makers in the service industry must effectively cope with queuing problems, service capacity optimization, service efficiency and service quality problems. This study proposes a computer simulation-enabled MCDM framework that integrates computer simulation analysis, Taguchi method, expert opinion and multiple criteria decision making (MCDM) to assist decision makers in coping with decision problems. In this framework, Taguchi method is adopted to reduce the time required for the simulation experiment. Computer simulation analysis is adopted to obtain useful information for rapid decision-making without interrupting actual production. MCDM is used to select the optimal alternative. The illustrative result is extremely promising.

• 한국조경학회:학술대회논문집
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• 한국조경학회 2007년도 Journal of Landscape Architecture in Asia Vol.3
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• pp.30-37
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• 2007

Modern cities are weak in traditional culture with the lack of characteristics and the problem of environmental deterioration. As the important carrier of urban culture, landscape architecture should be responsible for solving these problems. The urban need is paid much attention in the design of South Bank Linear Park in Meizhou city. Following the principle of inheriting and developing urban traditional culture, the design of the whole park is integrated with Hakka culture in Meizhou, which forms the landscape with local features and modern landscape architecture culture, and promotes the urban culture construction.

• Computers and Concrete
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• 제4권3호
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• pp.207-220
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• 2007

In this paper, hybrid fibers including high elastic modulus steel fiber and low elastic modulus synthetic macro-fiber (HPP) as two elements were used as reinforcement materials in concrete. The flexural toughness, flexural impact and fracture performance of the composites were investigated systematically. Flexural impact strength was analyzed with statistic analyses method; based on ASTM and JSCE method, an improved flexural toughness evaluating method suitable for concrete with synthetic macro-fiber was proposed herein. The experimental results showed that when the total fiber volume fractions ($V_f^a$) were kept as a constant ($V_f^a=1.5%$), compared with single type of steel or HPP fibers, hybrid fibers can significantly improve the toughness, flexural impact life and fracture properties of concrete. Relative residual strength RSI', impact ductile index ${\lambda}$ and fracture energy $G_F$ of concrete combined with hybrid fibers were respectively 66-80%, 5-12 and 121-137 N/m, which indicated that the synergistic effects (or combined effects) between steel fiber and synthetic macro-fiber were good.

• 한국조경학회지
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• 제45권2호
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• pp.40-50
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• 2017

수정된 IPA는 전통적 IPA와 비교시 실제 방문객 만족도가 반영된 관리전략을 수립하는데 있어 효과적인 방법이다. 그러나 전통적 IPA와 수정된 IPA의 비교연구는 제한적이다. 그러므로 본 연구에서는 순천만 습지 내 효과적인 관리전략을 구축하기 위해 전통적 IPA와 수정된 IPA를 비교분석하였다. 첫째, 수정된 IPA를 선정하기 위해 선행연구를 고찰하였고, 공간 내 방문객의 실제 만족도에 영향을 받는 관리전략과 서비스 질을 정량화 할 수 있는 적절한 방법으로 Deng(2007) 방법론을 선정하였다. 둘째, 순천만 습지 내 전통적 IPA와 수정된 IPA를 적용한 결과를 비교분석하였다. 셋째, 수정된 IPA의 관리전략과 변화된 관리요소에 관해 논의하였다. 그 결과, 전통적 IPA 결과보다 관리요구도가 더 높게 도출된 관리요소로 혼잡도가 나타났고, 관리요구도가 더 낮게 도출된 관리요소 중 집중관리에서 저우선순위로 관리전략이 변화하는 관리요소의 경우, 그늘목, 전시시설 내부, 프로그램, 가이드투어가 분석됐으며, 현 상태 유지에서 과잉노력지양으로 분석된 관리요소의 경우, 휴게시설, 낙조, 생울타리, 전시시설 외부로 도출되었다. 이는 현재 순천만 습지 내 관리전략과 비교시 전통적 IPA 결과값보다 수정된 IPA의 결과값에 더 부합된 결과로 실제 방문객들의 만족변화에 대해 탄력적인 반응을 보이는 것으로 분석되어졌다. 이를 통해 의사결정자들의 관리전략 구축시 수정된 IPA가 더 정확하고 신뢰성 높은 기초자료로 제공될 수 있을 것으로 기대된다.

• International Journal of Automotive Technology
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• 제8권4호
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• pp.395-402
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• 2007

Homogeneous Charge Compression Ignition (HCCI) shows great potential for low $NO_x$ emission but is hampered by the problem of no direct method to control the combustion process. Therefore, HCCI combustion becomes unstable easily, especially at lower and higher engine load. This paper presents a method to achieve diesel-fueled HCCI combustion, which involves directly injecting diesel fuel into the cylinder before the piston arrives at top dead center in the exhaust stroke and adjusting the valve overlap duration to trap more high temperature residual gas in the cylinder. The combustion stability of diesel-fueled HCCI combustion and the effects of engine load, speed, and valve overlap on it are the main points of investigation. The results show that: diesel-fueled HCCI combustion has two-stage heat release rate (low temperature and high temperature heat release) and very low $NO_x$ emission, combustion stability of the HCCI engine is worse at lower load because of misfire and at higher load because of knock, the increase in engine speed aids combustion stability at lower load because the heat loss is reduced, and increasing negative valve overlap can increase in-cylinder temperature which aids combustion stability at lower load but harms it at higher load.