• Proceedings of the KIEE Conference
• /
• 1998.07c
• /
• pp.923-925
• /
• 1998

Electric arc furnaces (EAFs) are a main cause of voltage flicker due to the interaction of the high demand currents of the load with the supply system impedance. The stochastic models have described the physical phenomena of EAFs. An alternative approach is to include deterministic chaos in the characterization of the arc currents. In this paper, a chaotic approach to such modeling is described and justified. At the same time, a DLL (Dynamic Link Library) module, which is a FORTRAN interface with TACS (Transient Analysis of Control Systems), is developed to implement the chaotic load model in the Electromagnetic Transients Program (EMTP). The details of the module and the results of tests performed on the module to verify the model and to illustrate its capabilities are presented in this paper.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.606-608
• /
• 2003

경쟁적인 전력시장에서의 전력 가격은 전력에 대한 수요(Demand)와 공급(Supply)에 의한 시장원리에 의해 결정되기 때문에, 매 시각의 전력가격은 정해져 있지 않고 시장에 의해 결정된다. 이와 같이 전력가격이 가지는 가변성 및 불확실성(Volatility) 때문에 향후 전력 시장에 참여하는 사업자의 수입(Revenue) 및 수익 규모의 불확실성이 커지는 한편, 전력을 사용하는 소비자의 에너지비용도 그 불확실성이 매우 크게 증가하게 마련이다. 이러한 전력가격의 가변성(Volatility)과 불확실성(Uncertainty)이 대두됨에 따라, 외국의 경우, 가정용 부하와 같은 소규모 전력소비자를 제외한 대부분의 대규모 소비자(산업용, 상업용, 일반용 전력소비자)들은 전력가격이나 자신이 사용하고 있는 전력의 소비패턴과 같은 정보(Information)와 전략(Strategy)이 없는 경우, 예전에 비해 상당히 높은 전기요금을 지불해야 하는 상황에 처하게 되었다. 본 논문에서는 이러한 경쟁적 환경에서 직접부하제어자원을 활용하여 비용 및 위험을 관리하는 해외사례를 집중적으로 분석하고자 한다.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.5 no.4
• /
• pp.63-73
• /
• 1996

The knowledge of the specialized fields has been changed rapidly in the both side of quantity and quality. A hyper media as a knowledge based system is so fixed in the linked media in mutual that we couldn't tell it information provision with the view of users. In this paper, we propose the way of offering intellectual and flexible information which is the same with demand in the side of user, selecting, searching and composing the hypertext at the point of user's view through the design of knowledge media system. Three concepts are used in order to challenge the knowledge media system : special document, agent system and ontology. The special document is a ensure that its activities are coordinated with those of the others within the community, providing a uniform control mechanism. Finally, ontology is a language for exchanging knowledgement, which is a message exchanged among agents to ensure the proper interaction among them. The combination of these three concepts is used to design the prototype of knowledge media system.

• Proceedings of the Korea Society for Simulation Conference
• /
• 1999.04a
• /
• pp.60-64
• /
• 1999

Recently in manufacturing environment, manufacturing order is characterized by unstable market demand, shorter product life cycle, a variety of product and shorter production lead time. In order to adapt this manufacturing order, flexible manufacturing system(FMS) in manufacturing technology advances into the direction that machines become further versatile functionally and that tools are controlled by fast tool delivery device. Unlike conventional FMS to mainly focus on part flow, it is important to control tool flow in single-stage multimachine systems(SSMS), consisting of versatile machines and fast tool delivery device. In this paper, in SSMS under dynamic tool allocation strategy to share tools among machines, we propose real-time part release and tool allocation algorithms which can apply real factory and which can improve system performance.

• Journal of the Ergonomics Society of Korea
• /
• v.27 no.4
• /
• pp.9-14
• /
• 2008

Work ability and job stress have become the important issues in Korea workplace recently. This study researched work ability and job stress and analyzed correlation with work ability and job stress using the Work Ability Index(WAI) and the Karasek's Job Content Questionnaire against 152 doctors. The results of this study show that the work ability in doctors was good in general. The work ability and the job stress according to major show statistical significance. The relation between job stress and disease showed statistical significance in musculoskeletal disorders, heart disease, and metabolic disease. The correlations between work ability and job stress showed statistical significance in job demand and job control. This study can be utilized to improve the job ability and prevent some disease from the job stress of doctors.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.5 no.1
• /
• pp.7-17
• /
• 2010

ITS(Intelligent Transport System) as things are used for Broadcast service using TDMB/TPEG/NAVI rather than personal seamless service. It is attaching weight to Traffic information gathering, Charging, Settlement service. This research is applied to improve DCCP(Datagram Congestion Control Protocol) which has function as protecting data and preserving message boundary. The improving method is like that we solve data trust in UDP because Connection and Transmission overhead in UDP is less than in TCP. We fix the data loss which is generated from unordered delivery section of IP base wireless service by using DCCP protocol. We guarantee of connection with OBE(On-Board Equipment) and reliance about transmission of data by complement to mapping table and multi-hoping. Finally, We evaluate the performance about transmission of IP based data. We constructed a test-bed near research center for this test.

• Journal of Agricultural Extension & Community Development
• /
• v.3 no.1
• /
• pp.43-54
• /
• 1996

Citrus farming become one of highly potent area for the farmer s income in the Asia region. Because of its favorable taste and distinctive aroma, attractive color, and nutritional values, market demand has increased steadily along with the income increases in the region. However, realization of the potent have been constrained due to poor orchard management, frequent occurrences of pest and diseases, and a high cost in production besides of the market failures. Cutting down of production cost should be an operational goal to obtain mope profit where marketing structure has yet been underdeveloped. The objective of this study was to provide a comparative information to those program efforts of searching comparative advantage in production. For the three countries, reduction of labor cost by reduction of chemical application frequency was recommended while pursuing further mechanization in those operation such as in pruning, harvesting and pest control. Adoption of the IPM (integrated pest management) will be useful to reduce the number of spraying chemicals with changed knowledge and attitude of the farmers.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2002.04a
• /
• pp.53-60
• /
• 2002

It has been recognized that damage control must become a more explicit design consideration. In an effort to develop design methods based on performance it is clear that the evaluation of the inelastic response is required. The methods available to the design engineer today are nonlinear time history analyses, or monotonic static nonlinear analyses, or equivalent static analyses with simulated inelastic influences. Some codes proposed the capacity spectrum method based on the nonlinear static(pushover) analysis to determine earthquake-induced demand given the structure pushover curve. This procedure is conceptually simple but iterative and time consuming with some errors. This paper presents a nonlinear direct spectrum method to evaluate seismic Performance of structure, without iterative computations, given the structural initial elastic period and yield strength from the pushover analysis, especially for multi degree of freedom structures. The purpose of this paper is to investigate accuracy and confidence of this method from a point of view of various earthquakes and unloading stiffness degradation parameters.

• Journal of the Korea Society of Computer and Information
• /
• v.21 no.1
• /
• pp.49-57
• /
• 2016

In this paper we propose the resource allocation scheme for the overlaid macro-femtocell networks, which considers the type of handovers such as the inter-macrocell, macrocell-to-femtocell, femtocell-to-macrocell, or inter-femtocell in order to guarantee Quality of Service (QoS) and expand the accommodation capacity. Our proposed scheme takes into account the movement of mobile terminals, the QoS degradation, or the load control which trigger handovers in the overlaid networks, before it allocates resources dynamically. Moreover it considers QoS requirements of realtime or non-realtime mobile multimedia services such as video communication, Video on Demand (VoD) and dataa services. Simulation results show that our scheme provides better performances than the conventional one with respect to the outage probability, data transmission throughput and handover failure rate.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1998.10a
• /
• pp.427-432
• /
• 1998

최근 산업발전에 따라 야기되는 문제점 중 전력수요의 증가에 의한 피해가 증대되고 있다. 여름철 하계부하등에 의한 과부하는 가정이나 대형건물의 정전을 발생시키거나 공장의 기계를 파손시키기도 하기 때문에 이를 미연에 방지할 수 있는 부하예측기법이 점차로 강조되고 있는 현실이다. 이에 본 논문에서는 초(sec)단위의 순시부하예측/제어를 위한 새로운 방법과 퍼지제어기를 제안한다. 제안한 순시부하예측/제어는 크게 과거의 데이터를 가지고 일정시간 후의 값을 예측하는 예측부와 이 결과의 신뢰도를 높여주기 위한 퍼지제어기로나눌 수 있다. 예측부는 SOFM (Self-Organizing Feature Map) 신경망을 이용하며, 예측된 출력값을 퍼지제어기의 입력으로 사용한다.