• Korean Journal of Construction Engineering and Management
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• v.8 no.5
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• pp.71-79
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• 2007

It is common that the analysis of VE/LCC is performed in design phase of quay wall structures. The analysis is mainly executed based on experience and engineering sense of expert considering the selection of construction method, construction and maintenance cost. Recently there are increasing demands on the analysis that includes uncertainty and vulnerability of input parameters, for this purpose, fuzzy reliability based probabilistic VE/LCC analysis model for quay wall structures is suggested. In VE/LCC analysis for quay wall structures, the application of probabilistic analysis method give very similar results compare with those of deterministic analysis method. It is anticipated that the methodology proposed in this paper can also be utilized in the design and maintenance phase of other facilities where decision making is made for the probabilistic life cycle cost and value analysis.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.2
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• pp.126-131
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• 2017

In this paper, we propose a method to extract meaningful motion among various kinds of hand gestures on giving commands to robots using hand gestures. On giving a command to the robot, the hand gestures of people can be divided into a preparation one, a main one, and a finishing one. The main motion is a meaningful one for transmitting a command to the robot in this process, and the other operation is a meaningless auxiliary operation to do the main motion. Therefore, it is necessary to extract only the main motion from the continuous hand gestures. In addition, people can move their hands unconsciously. These actions must also be judged by the robot with meaningless ones. In this study, we extract human skeleton data from a depth image obtained by using a Kinect v2 sensor and extract location data of hands data from them. By using the Kalman filter, we track the location of the hand and distinguish whether hand motion is meaningful or meaningless to recognize the hand gesture by using the hidden markov model.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.307-311
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• 2010

지구 온난화로 인한 이상기후 현상이 지속적으로 발생됨에 따라 풍수해의 저감과 수자원의 효율적인 활용에 대한 관심이 높아지고 있다. 국내의 경우 주요지점의 상류에 댐을 건설하고 댐 상류의 저류공간을 이용하여 홍수를 저감하고 수자원을 확보하는 것이 가장 일반적으로 사용되고 있는 홍수대응과 수자원 활용 방안이다. 수자원 문제를 해결하기 위한 다양한 기법들이 연구되고 적용되고 있지만, 수자원 문제는 불확실성과 애매모호함을 내포하고 있어 풍수해 피해 저감과 한정된 수자원의 효율적인 활용을 어렵게 하고 있다. 본 연구에서는 수자원 문제에 내포되어 있는 불확실성과 애매모호함을 해결하기 위해, 인간의 사고과정과 유사한 추론과정을 통해 애매모호함을 처리하는 데 강점을 가진 퍼지추론기법을 적용하여 저수지 퍼지최적운영 모형을 개발하는 것을 목적으로 하였다. 또한 기후변화를 고려하기 위해, 일반적으로 발생하고 있는 홍수뿐만 아니라 이상홍수 발생의 경우도 고려하여 저수지 운영모형을 개발하였다. 저수지 운영모형 개발을 위해 다음과 같은 과정을 통해 퍼지최적운영모형을 개발하였다. 우선 선형계획법을 사용해 일반적인 홍수와 이상 홍수 유입시 저수지 최적연계운영을 실시하여 최적운영규칙을 추출하였다. 그리고, 최적운영을 통해 추출된 각각의 운영규칙을 퍼지기법을 도입하여 퍼지운영규칙으로 정리하였다. 마지막으로, 정리된 각각의 퍼지운영 규칙을 조합하여 이상홍수를 고려한 저수지 운영규칙을 구성하였다. 본 연구에서는 낙동강 상류에 위치한 다목적댐인 안동댐과 임하댐 유역을 시험유역으로 선정하여 모형을 개발하였고, 일반적인 홍수로는 안동댐과 임하댐에 각각 100년 빈도의 홍수가 유입되는 것을 가정하였으며, 이상홍수로는 각의 댐에 극한홍수(PMF)가 유입되는 것으로 설정하였다. 개발된 저수지 운영모형을 통해 시험유역의 저수지 운영을 모의한 결과 각 댐의 유입량자료와 저수지 저류량 자료, 하류지점의 유량자료만을 사용하여 간편하고 신속하게 저수지 운영을 수행 할 수 있었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.282-286
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• 2000

In this paper, magneto-rheological(MR) damper is studied for vibration control of large infra structures under earthquake. Generally, active control devices need a large control force and a high power supply system to reduce the vibration effectively. Large and miss tuned control force may induce the dangerous situation such that the generated large control force acts to amplify the structural vibration. Recently, to overcome the weaknesses of the active control, the semi-active control method is suggested by many researchers. Semi-active control uses the passive control device of which the characteristics can be modified. Control force of the semi-active device is not generated from the actuator with power supply. It is generated as a dynamic reaction force of the device same as in the passive control case, so the control system is inherently stable and robust. Unlike the case of passive control, control force of semi-active control is adjusted depending on the measured response of the structure, so the vibration can be reduced more effectively against various unknown environmental loads. Magneto-rheological(MR) damper is one of the semi-active devices. Dynamic characteristics of the MR material can be changed by applying the magnetic fields. So the control of MR damper needs only small power. Response time of MR to the input voltage is very short, so the high performance control is possible. MR damper has a high force capacity so it is adequate to the vibration control of large infra structure. Because MR damper has a nonlinear property, normal control method used in active control may not be effective. Clipped optimal control, modified bang-bang control etc. have been suggested to MR damper by many researchers. In this study, sliding mode fuzzy control(SMFC) is applied to MR damper. Genetic algorithm is used for the controller tuning. To verify the applicability of MR damper and suggested algorithm, numerical simulation on the aseismic control is carried out. Simulation model is three-story building structure, which was used in the paper of Dyke, et al. The control performance is compared with clipped optimal control. The present results indicate that the SMFC algorithm can reduce the earthquake-induced vibration very effectively.

• The Journal of Industrial Distribution & Business
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• v.5 no.4
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• pp.31-42
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• 2014

Purpose - According to the applied studies knowledge, management implementation can improve organizational performance. The main objective of this study is to develop an understanding of critical success factors that enhance the successful implementation of knowledge management. Research design, data, and methodology - This study used Analytical Hierarchy Procedure (AHP), which is a multi-criteria decision making model that works on fuzzy logic. Using this method, researchers can find the proportion of success due to the contribution of the critical success factors (CSFs). Results - The results show that more than 70% of respondents indicate the possibility of success in knowledge management implementation. Further, the results show that top management support has the greatest relationship with the success of knowledge management implementation. This was followed by information technology, performance measurement, and culture, which had a high relation with knowledge management success. Process and activities have a moderate positive relation, while education and training has a low relation with success. Because of an inappropriate p-value, knowledge management strategies show no relation to the success of knowledge management in the Iranian health Industry. Conclusions - This study was conducted because of a critical issue in the Iranian health industry that indicated that a significant portion of the workforce would retire in 5 to 10 years. Most highly experienced and knowledge oriented employees would become eligible for retirement. Therefore, knowledge management is presented as a complete solution in the Iranian health sector.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.71-83
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• 2013

Recently, the advanced condition monitoring methods such as the model-based method and the artificial intelligent method have been applied to maximize the availability as well as to minimize the maintenance cost of the aircraft gas turbines. Among them the non-linear GPA(Gas Path Analysis) method and the GA(Genetic Algorithms) have lots of advantages to diagnose the engines compared to other advanced condition monitoring methods such as the linear GPA, fuzzy logic and neural networks. Therefore this work applies both the non-linear GPA and the GA to diagnose AE3007 turbofan engine for an aircraft, and in case of having sensor noise and bias it is confirmed that the GA is better than the GPA through the comparison of two methods.

• Journal of Korea Trade
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• v.25 no.5
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• pp.58-73
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• 2021

Purpose - In the context of economic globalization and the continuous development of international trade, as countries around the sea peninsula, port construction is particularly important. Based on the research on the influencing factors of port logistics development based on the allocation analysis, QCA (Qualitative Comparative Analysis) provides the basis for the planning and policy of port logistics development and has important theoretical value and practical significance for improving the level of port logistics management, reducing logistics operating costs and increasing economic benefits. In the tide of global integration for the development of port logistics, promote the growth of foreign trade economy of the city. It is also of great significance to the development and progress of commerce and trade. Design/methodology - Based on the relevant data samples of various ports in South Korea, this paper uses fsQCA (fuzzy set Qualitative Comparative Analysis) to integrate and analyze the influence mechanism of port logistics development and extracts five influencing factors of port logistics development, including the port's scale and infrastructure in the hard environment, port-neighboring enterprises in the soft environment, hinterland economy and government support. Findings - The five factors are unable to separately constitute the necessary and sufficient conditions of port logistics development, only a combined model can influence lake port logistics development. The scale and infrastructure of the port itself and port-neighboring ring enterprises are the main core conditions, which work together on the port, affect the throughput capacity of the port, and promote the development of port logistics. When the port-neighboring enterprises are not complete and the scale is low, the growth of port throughput will be restrained and the development of port logistics will be affected, whether the hinterland economic benefits are general, the development of port-neighboring enterprises is insufficient, or the government supports are limited. Originality/value - Through the research on the development of port logistics in South Korea from the perspective of configuration, this paper finds the configuration influence of hard environment and soft environment on the development of port logistics, which has important theoretical and practical significance for better promoting the development of port logistics in South Korea.

• Computers and Concrete
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• v.29 no.3
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• pp.187-199
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• 2022

The usability of waste materials as raw materials is necessary for sustainable production. This study investigates the effects of different powder materials used to replace cement (0%, 5% and 10%) and standard sand (0%, 20% and 30%) (basalt, limestone, and dolomite) on the compressive strength (f_c), flexural strength (f_r), and ultrasonic pulse velocity (UPV) of mortars exposed to freeze-thaw cycles (56, 86, 126, 186 and 226 cycles). Furthermore, the usability of artificial intelligence models is compared, and the prediction accuracy of the outputs is examined according to the inputs (powder type, replacement ratio, and the number of cycles). The results show that the variability of the outputs was significantly high under the freeze-thaw effect in mortars produced with waste powder instead of those produced with cement and with standard sand. The highest prediction accuracy for all outputs was obtained using the adaptive-network-based fuzzy inference system model. The significantly high prediction accuracy was obtained for the UPV, f_c, and f_r of mortars produced using waste powders instead of standard sand (R² of UPV, f_c and f_f is 0.931, 0.759 and 0.825 respectively), when under the freeze-thaw effect. However, for the mortars produced using waste powders instead of cement, the prediction accuracy of UPV was significantly high (R²=0.889) but the prediction accuracy of f_c and f_r was low (R²f_c=0.612 and R²f_f=0.334).

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.501-501
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• 2023

하천에서의 여가활동에 대한 수요가 증가함에 따라 각종 친수활동에 대한 안전도 평가가 사고예방을 위해 중요해지고 있다. 친수 활동의 안전은 수리 및 수질 인자에 크게 영향을 받지만 기존 친수지수는 수질 인자에만 집중되어 개발되어왔다. 하지만, 세일링, 패들링, 저동력보트 등 입수형 친수활동의 경우, 다양한 수리 현상에 큰 영향을 받기 때문에 유속, 흐름 방향, 수심 및 수면 폭 등의 수리인자를 친수지수에 반영할 필요가 있다. 또한, 친수활동에 위험이 되는 수리적 조건은 유량 조건과 하천의 평면적 공간에 따라 상이하게 발생하기에 이를 공간적으로 평가하는 것 역시 필요한 실정이다. 본 연구에서는 수리학적 요소를 기반으로 하천 친수 활동에 대한 안전도를 평가하기 위해 공간적으로 친수활동의 안정성을 평가할 수 있는 SRRI (Spatial River Recreation Index)를 제안하였다. SRRI의 개발을 위해 1단계에서는 다양한 유량 조건에서 EFDC 동수역학모형을 이용하여 수리 인자들의 공간적 분포를 재현한 후, 2단계에서는 퍼지합성법 (FSE)를 적용하여 수리인자의 모든 소속도와 가중치를 종합하여 하천 지점별 하천친수지수를 산정하였다. 개발한 SRRI를 낙동강-금호강 합류부에 적용한 결과, 유량 및 지형 조건에 따라 각 수리인자가 친수활동 안전성에 미치는 영향이 공간적으로 매우 상이하게 나타났다. 유향(흐름 방향)은 합류지점 부근에서 친수활동의 위험성을 크게 증가시키는 반면, 사행구간에서는 수심이 중요한 요인으로 나타났다. 고유량 조건에서는 유속이 세일링 및 패들링에서 가장 큰 영향을 미치는 요소로 작용하였다. 특히 세일링은 유량 변화에 민감하여 고유량시에는 주흐름부와 합류부 부근을 제외하고 일부 공간에서만 안전하게 이용이 가능한 것으로 나타났다. 반면 무동력 및 저동력보트는 유량 변화에 덜 민감하여 고유량 조건에서도 부분적으로 허용될 수 있었지만 사행구간의 고수심부에서는 위험 등급으로 권고되었다. 이러한 결과를 바탕으로 SRRI는 다양한 수리학적 조건을 기반으로 공간적 안전정보를 제공함으로써 많은 이용자들이 하천에서 보다 안전한 친수활동을 즐기는 데에 기여할 수 있을 것으로 판단된다.

• Steel and Composite Structures
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• v.52 no.3
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• pp.293-312
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• 2024

Researchers are actively investigating the potential for utilizing alternative materials in construction to tackle the environmental and economic challenges linked to traditional concrete-based materials. Nevertheless, conventional laboratory methods for testing the mechanical properties of concrete are both costly and time-consuming. The limitations of traditional models in predicting the tensile strength of concrete composited with geopolymer have created a demand for more advanced models. Fortunately, the increasing availability of data has facilitated the use of machine learning methods, which offer powerful and cost-effective models. This paper aims to explore the potential of several machine learning methods in predicting the tensile strength of geopolymer concrete under different curing conditions. The study utilizes a dataset of 221 tensile strength test results for geopolymer concrete with varying mix ratios and curing conditions. The effectiveness of the machine learning models is evaluated using additional unseen datasets. Based on the values of loss functions and evaluation metrics, the results indicate that most models have the potential to estimate the tensile strength of geopolymer concrete satisfactorily. However, the Takagi Sugeno fuzzy model (TSF) and gene expression programming (GEP) models demonstrate the highest robustness. Both the laboratory tests and machine learning outcomes indicate that geopolymer concrete composed of 50% fly ash and 40% ground granulated blast slag, mixed with 10 mol of NaOH, and cured in an oven at 190°F for 28 days has superior tensile strength.