• 전기학회논문지
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• 제66권2호
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• pp.328-338
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• 2017

In this paper, a zero torque control scheme adopting current sharing function (CSF) used in integrated Switched Reluctance Motor (SRM) drive with DC battery charger is proposed. The proposed control scheme is able to achieve the keeping position (KP), zero torque (ZT) and power factor correction (PFC) at the same time with a simple novel current sharing function algorithm. The proposed CSF makes the proper reference for each phase windings of SRM to satisfy the total charging current of the battery with zero torque output to hold still position with power factor correction, and the copper loss minimization during of battery charging is also achieved during this process. Based on these, CSFs can be used without any recalculation of the optimal current at every sampling time. In this proposed integrated battery charger system, the cost effective, volume and weight reduction and power enlargement is realized by function multiplexing of the motor winding and asymmetric SR converter. By using the phase winding as large inductors for charging process, and taking the asymmetric SR converter as an interleaved converter with boost mode operation, the EV can be charged effectively and successfully with minimum integral system. In this integral system, there is a position sliding mode controller used to overcome any uncertainty such as mutual inductance or DC offset current sensor. Power factor correction and voltage adaption are obtained with three-phase buck type converter (or current source rectifier) that is cascaded with conventional SRM, one for wide input and output voltage range. The practicability is validated by the simulation and experimental results by using a laboratory 3-hp SRM setup based on TI TMS320F28335 platform.

• 한국정보과학회논문지:정보통신
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• 제36권5호
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• pp.456-469
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• 2009

본 논문에서 ECOT(Estimated Channel Occupancy Time)이라는 새로운 무선 링크 성능 지표를 제시하며, 이를 기반으로 멀티 홉 무선 메쉬 네트워크 환경에서 종간간 높은 수율을 얻고자 한다. ECOT의 핵심적인 특징은 다양한 형태의 IEEE 802.11 MAC(Medium Access Control) 환경에서 적용이 가능하다는 점이다. 우리는 802.11 DCF(Distributed Coordination Function), 802.11e EDCA(Enhanced Distributed Channel Access) with BACK(Block Acknowledgement), 802.11n A-MPDU(Aggregate MAC Protocol Data Unit)와 같은 다양한 형태의 링크 계층 구조를 고려하며, 이와 같은 다양한 환경에서 제안하는 ECOT이 기 제안된 다른 성능 지표 방법론과 비교하여 높은 종단간 수율 성능(이득: $8.5{\sim}354.4%$)을 보여줄 수 있다는 것을 확인하였다.

• 소프트웨어공학소사이어티 논문지
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• 제28권1호
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• pp.7-12
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• 2019

최근 무기체계에서 소프트웨어가 차지하는 비중이 증가됨에 따라 소프트웨어의 품질이 매우 중요한 요소가 되고 있다. 무기체계 소프트웨어의 품질 향상을 위해 방위사업청은 무기체계 소프트웨어 개발 및 관리 매뉴얼에 소프트웨어 신뢰성을 제도화 하였고, 구체적인 방법 및 절차를 제시하고 있다. 매뉴얼에서 요구하는 소프트웨어 신뢰성 시험의 기준을 충족하기 위해서는 개발 전(全) 순기에 걸쳐 지속적인 시험을 통해 결함의 검출 및 수정이 필요하지만, 보안을 위한 망분리 환경, 시험 도구 확보를 위한 비용 문제로 인해 적정 수준의 시험 환경을 구축하는데 어려움이 따른다. 따라서 본 연구에서는 방위산업 분야에서 제한된 개발 환경과 한정된 자원을 활용해 효율적으로 소프트웨어 신뢰성 시험을 수행 할 수 있는 환경 구축 방안을 제시하고자 한다.

• 토지주택연구
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• 제13권4호
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• pp.105-114
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• 2022

화재감지기는 비화재보가 많이 발생함에 따라서 신속하게 감지기를 확인해야 하지만 일반감지기는 주소기능이 없어 신속한 대응에 한계가 있다. 주소 기능을 갖는 아날로그감지기 등을 적용하면 해결되지만 기존 공동주택의 경우 교체기간, 교체 비용, 선로의 사용 등의 문제로 인해 설비의 전면 교체에는 한계가 있다. 이에 별도로 기존아파트에 적용성을 고려한 맞춤형 설비가 필요하다. 본 연구에서는 기존아파트의 특성을 고려하여 주소형 감지기와 중계기를 설계하여 중계기에서 감지기 위치를 확인할 수 있는 시스템을 개발하였다. 주소형 감지기는 정온식과 광전식 감지기를 설계하였으며, 주소형 중계기는 FND를 추가하여 감지기 위치 확인이 가능하게 하였다. 선로의 종류, 길이를 고려하여 성능검증을 하였으며, 단선에러 동작과 일반감지기와의 호환성 등을 추가 검증하였다.

• 산업경영시스템학회지
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• 제44권2호
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• pp.24-35
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• 2021

Due to increasing awareness on the treatment of end-of-use/life products, disassembly has been a fast-growing research area of interest for many researchers over recent decades. This paper introduces a novel lot-sizing problem that has not been studied in the literature, which is the service-parts lot-sizing with disassembly option. The disassembly option implies that the demands of service parts can be fulfilled by newly manufactured parts, but also by disassembled parts. The disassembled parts are the ones recovered after the disassembly of end-of-use/life products. The objective of the considered problem is to maximize the total profit, i.e., the revenue of selling the service parts minus the total cost of the fixed setup, production, disassembly, inventory holding, and disposal over a planning horizon. This paper proves that the single-period version of the considered problem is NP-hard and suggests a heuristic by combining a simulated annealing algorithm and a linear-programming relaxation. Computational experiment results show that the heuristic generates near-optimal solutions within reasonable computation time, which implies that the heuristic is a viable optimization tool for the service parts inventory management. In addition, sensitivity analyses indicate that deciding an appropriate price of disassembled parts and an appropriate collection amount of EOLs are very important for sustainable service parts systems.

• 산업경영시스템학회지
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• 제44권4호
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• pp.32-42
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• 2021

The printing process can have to print various colors with a limited capacity of printing facility such as ink containers that are needed cleaning to change color. In each container, cleaning time exists to assign corresponding inks, and it is considered as the setup cost required to reduce the increasing productivity. The existing manual method, which is based on the worker's experience or intuition, is difficult to respond to the diversification of color requirements, mathematical modeling and algorithms are suggested for efficient scheduling. In this study, we propose a new type of scheduling problem for the printing process. First, we suggest a mathematical model that optimizes the color assignment and scheduling. Although the suggested model guarantees global optimality, it needs a lot of computational time to solve. Thus, we decompose the original problem into sequencing orders and allocating ink problems. An approximate function is used to compute the job scheduling, and local search heuristic based on 2-opt algorithm is suggested for reducing computational time. In order to verify the effectiveness of our method, we compared the algorithms' performance. The results show that the suggested decomposition structure can find acceptable solutions within a reasonable time. Also, we present schematized results for field application.

• Coupled systems mechanics
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• 제11권1호
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• pp.55-78
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• 2022

The main aim of this paper is the identification of the model parameters for the constitutive model of concrete and concrete-like materials capable of representing full set of 3D failure mechanisms under various stress states. Identification procedure is performed taking into account multi-scale character of concrete as a structural material. In that sense, macro-scale model is used as a model on which the identification procedure is based, while multi-scale model which assume strong coupling between coarse and fine scale is used for numerical simulation of experimental results. Since concrete possess a few clearly distinguished phases in process of deformation until failure, macro-scale model contains practically all important ingredients to include both bulk dissipation and surface dissipation. On the other side, multi-scale model consisted of an assembly micro-scale elements perfectly fitted into macro-scale elements domain describes localized failure through the implementation of embedded strong discontinuity. This corresponds to surface dissipation in macro-scale model which is described by practically the same approach. Identification procedure is divided into three completely separate stages to utilize the fact that all material parameters of macro-scale model have clear physical interpretation. In this way, computational cost is significantly reduced as solving three simpler identification steps in a batch form is much more efficient than the dealing with the full-scale problem. Since complexity of identification procedure primarily depends on the choice of either experimental or numerical setup, several numerical examples capable of representing both homogeneous and heterogeneous stress state are performed to illustrate performance of the proposed methodology.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권1호
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• pp.46-63
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• 2024

One of the biggest dangers in the globe is water contamination. Water is a necessity for human survival. In most cities, the digging of borewells is restricted. In some cities, the borewell is allowed for only drinking water. Hence, the scarcity of drinking water is a vital issue for industries and villas. Most of the water sources in and around the cities are also polluted, and it will cause significant health issues. Real-time quality observation is necessary to guarantee a secure supply of drinking water. We offer a model of a low-cost system of monitoring real-time water quality using IoT to address this issue. The potential for supporting the real world has expanded with the introduction of IoT and other sensors. Multiple sensors make up the suggested system, which is utilized to identify the physical and chemical features of the water. Various sensors can measure the parameters such as temperature, pH, and turbidity. The core controller can process the values measured by sensors. An Arduino model is implemented in the core controller. The sensor data is forwarded to the cloud database using a WI-FI setup. The observed data will be transferred and stored in a cloud-based database for further processing. It wasn't easy to analyze the water quality every time. Hence, an Optimized Neural Network-based automation system identifies water quality from remote locations. The performance of the feed-forward neural network classifier is further enhanced with a hybrid GA- PSO algorithm. The optimized neural network outperforms water quality prediction applications and yields 91% accuracy. The accuracy of the developed model is increased by 20% because of optimizing network parameters compared to the traditional feed-forward neural network. Significant improvement in precision and recall is also evidenced in the proposed work.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.715-727
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• 2024

During fast neutron imaging, besides the dark current noise and readout noise of the CCD camera, the main noise in fast neutron imaging comes from high-energy gamma rays generated by neutron nuclear reactions in and around the experimental setup. These high-energy gamma rays result in the presence of high-density gamma white spots (GWS) in the fast neutron image. Due to the microscopic quantum characteristics of the neutron beam itself and environmental scattering effects, fast neutron images typically exhibit a mixture of Gaussian noise. Existing denoising methods in neutron images are difficult to handle when dealing with a mixture of GWS and Gaussian noise. Herein we put forward a deep learning approach based on the Swin Transformer UNet (SUNet) model to remove high-density GWS-Gaussian mixture noise from fast neutron images. The improved denoising model utilizes a customized loss function for training, which combines perceptual loss and mean squared error loss to avoid grid-like artifacts caused by using a single perceptual loss. To address the high cost of acquiring real fast neutron images, this study introduces Monte Carlo method to simulate noise data with GWS characteristics by computing the interaction between gamma rays and sensors based on the principle of GWS generation. Ultimately, the experimental scenarios involving simulated neutron noise images and real fast neutron images demonstrate that the proposed method not only improves the quality and signal-to-noise ratio of fast neutron images but also preserves the details of the original images during denoising.

• 농촌계획
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• 제18권2호
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• pp.47-56
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• 2012

Recently urban areas have been advanced in the aspects of convenience, traffic, and cultural environments, but they have faced various problems including environmental issues, traffic congestion, and increasing stress. In contrast, rural areas are in charge of various functions, conservations of natural environments and traditional cultures. Rural life style may be beneficial to urbanites. As urbanites are increasingly interested in leisure activities, such as experiences of tradition cultures and education, safe foods and rural tourism are gaining attention as alternative ways of satisfying their desires. In other words, the rural tourism not only provides urbanites with leisure spaces by playing a role in relations between urban and rural areas, but also acts as a nonfarm income to the rural residents. With the changes of time, the number of current rural experience tourism on a nationwide is increasing and competition among locations is getting intensive. Particularly, despite various rural tourism villages in operation, there is not a standard in the dice for experience cost and accommodation costs. Accordingly, the aim of the study was to estimate urbanites' willingness to pay(WTP) for rural experience tourism and to provide basic data for qualitative growth and revitalization with regard to the tours. The estimated WTP for rural experience tourism was found to be 5,600won for experience, 5,600won for food, 42,000won for accommodation, and 13,000won for purchasing farm products, respectively. This trend could be similarly found (there were slight differences in food cost) on all analyses, such as the research of the current situations of rural tourism villages in Gyeongnam province, the pilot survey and the estimation depending on whether or not urbanites experienced the tours. In other words, the WTP for urban hands-on experience tours estimated by this study is considered highly significant in terms with possibility of its application in the sites. It is concluded that the urbanites' WTP for rural experience tourism obtained by this study will contribute to the setup of standard index of rural tourism, the qualitative development of rural hands-on experiences, and the raise of nonfarm income.