• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2211-2220
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• 2015

This paper analyzes multiple active management (AM) techniques of active distribution network (ADN), and proposes an optimal coordination model of intermittent distributed generation (IDG) accommodation considering the timing characteristic of load and IDG. The objective of the model is to maximize the daily amount of IDG accommodation under the uncertainties of IDG and load. Various active management techniques such as IDG curtailment, on-load tap changer (OLTC) tap adjusting, voltage regulator (VR) tap adjusting, shunt capacitors compensation and so on are fully considered. Genetic algorithm and Primal-Dual Interior Point Method (PDIPM) is used for the model solving. Point estimate method is used to simulate the uncertainties. Different scenarios are selected for the IDG accommodation capability investigation under different active management schemes. Finally a modified IEEE 123 case is used to testify the proposed accommodation model, the results show that the active management can largely increase the IDG accommodation and penetration.

• Journal of Preventive Medicine and Public Health
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• 제30권3호
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• pp.599-608
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• 1997

6명의 20대 여성을 대상으로 VDT작업으로 인한 조절반응 및 동공대광반사의 작업부과에 따른 변화와 다른 사무작업을 부과할 때와의 차이를 보았다. 그 결과 다음과 같은 결과를 얻었다. 1. VDT작업에서 작업부과 시간이 증가함에 따라 조절 수축속도가 감소했으며 1시간의 휴식시간 후에는 현저하게 증가했고 다시 작업을 부과함에 따라 감소하는 경향을 보였다. 조절 수축속도의 변화보다는 뚜렷하지 않지만 이완속도도 VDT작업부과에 따라 감소되고 휴식에 의한 회복되는 경향을 보였다. 2. 일반 사무작업과 근거리 사무작업에서는 조절 수축속도에서 VDT작업부과때와 같은 반응은 보이지 않았으며, 근거리 사무작업에서 이완속도가 작업부과에 따라 감소하였으나 휴식 후 회복되지 않았다. 3. 동공대광반사에서 최초동공직경, 최초동공면적은 VDT작업에서만 작업시간의 증가에 따라 유의한 감소를 보였는데 휴식 후 회복되지 않았다. 이러한 결과는 조절 수축속도의 변화, 조절 이완속도, 동공직경과 면적의 변화가 VDT작업의 특성을 연구하는데 사용될 가능성을 보여주며, 이를 위해서 연구대상이 개인차, 생체리듬, 감정적 자극 등을 보정한 연구가 필요하다고 생각된다.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 춘계학술대회논문집
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• pp.265-269
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• 1997

A series of experiments was carried out while using totally six female subjects in order to evaluate their psycho-physilolgical variations during their work with VDT both subjectively and objectively compared to those of ordinary office type work and speech communication type work. The results led by the experiment were as follows; the effects with data input work on the subjects from the view point of psychological load was larger than those with the ordinary office work. Oral communication between subjects gave the positive effects upon each subjects to reduce their psychological and mental burden.

• 소성∙가공
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• 제11권5호
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• pp.447-456
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• 2002

A study has been made to investigate the boundary sliding and its accommodation mode with respect to the variation of $\alpha$$_2$/$eta$ volume fraction during superplastic deformation of two-phase Ti$_3$Al-xNb intermetallics. Step strain rate and load relaxation tests have been performed at 950, 970 and 99$0^{\circ}C$ to obtain the flow stress curves and to analyze the deformation characteristics by the theory of inelastic deformation. The results show that the grain matrix deformation and boundary sliding of the three intermetallics containing 21, 50 and 77% in $eta$ volume fractions are well described by the plastic deformation and viscous flow equations. Due to the equal accommodation of both $a^2$ and $\beta$ phases, the accommodation modes for fine-grained materials are in good agreement with the iso-strain rate models. The sliding resistance analyzed for the different boundaries is the lowest in the $\alpha$$_2$/$\alpha$$_2$ boundary, and increases in the order of $\alpha$$_2$/$\alpha$$_2$<< $\alpha$$_2$/$\beta$ = $\beta$/$\beta$, which plays an important role in controlling the superplasticity of the alloys with the various $\alpha$$_2$/$\beta$ phase ratio.

• 대한조선학회논문집
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• 제33권4호
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• pp.124-132
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• 1996

선박 거주구 설계를 예로하여 선박설계에 있어서 업무 부하가 평준화된 최적의 설계일정계획을 도출할 수 있는 일정계획시스템을 수립하여 보았다. 설계일정관리에 영향을 주는 여러 요소들을 찾아 분석하여 최적의 설계일정을 도출할 수 있는 알고리즘을 설계하였다. 계획된 선박의 각 도면작성에 소요되는 시수를 신속하게 추정하기 위하여, 표준선박에 대한 기본 시수를 미리 설정하여 놓고 해당 선박에 대한 난이도를 적절히 적용하는 방법을 사용했다. 여러 도면작업의 진행상의 선후관계를 matrix table로 표현하여 일정표 작성의 전산화를 단순화 하였다. 이 시스템을 전산화 함으로써 계획된 선박에 대하여 그 선박의 특성이 충분히 반영 되어 작업이 평준화된 설계일정계획을 짧은 시간에 얻을 수 있었다.

• Geomechanics and Engineering
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• 제30권2호
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• pp.169-185
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• 2022

The urbanization and increasing rate of population demands effective means of transportation system (basement and tunnels) as well as high-rise building (resting on piled foundation) for accommodation. Therefore, it unavoidable to construct basements (i.e., excavation) nearby piled foundation. Since the basement excavation inevitably induces soil movement and stress changes in the ground, it may cause differential settlements to nearby piled raft foundation. To understand settlement and load transfer mechanism in the piled raft due to excavation-induced stress release, numerical parametric studies are carried out in this study. The effects of excavation depths (i.e., formation level) relative to piled raft were investigated by simulating the excavation near the pile shaft (i.e., H_e/L_p=0.67), next to (H_e/L_p=1.00) and below the pile toe (H_e/L_p=1.33). In addition, effects of sand density and raft fixity condition were investigated. The computed results have revealed that the induced settlement, tilting, pile lateral movement and load transfer mechanism in the piled raft depends upon the embedded depth of the diaphragm wall. Additional settlement of the piled raft due to excavation can be account for apparent loss of load carrying capacity of the piled raft (ALPC). The highest apparent loss of piled raft capacity ALPC (on the account of induced piled raft settlement) of 50% was calculated in in case of H_e/L_p = 1.33. Furthermore, the induced settlement decreased with increasing the relative density from 30% to 90%. On the contrary, the tilting of the raft increases in denser ground. The larger bending moment and lateral force was induced at the piled heads in fixed and pinned raft condition.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.433-437
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• 2004

A provision crane is generally installed on the upper deck to the rear of the accommodation of the ship in order to load and unload engine part or something heavy. There are two types of provision cranes: one is jib-type and the other is monorail-type. So the natural frequency of the jib-type crane equipment is low, therefore, there are some possibility of resonance between crane structure and the main excitation sources of the ship in normal operating range. This study describe a vibration reduction technique for provision crane by applying a proper countermeasure through finite element analysis and modal test. In order to find out weak point in design of provision crane, a sensitive analysis has been performed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권12호
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• pp.4356-4371
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• 2014

When the load in a multi-cell orthogonal frequency division multiple access (OFDMA) system is allowed to excessively increase in face of frequent handover, the cell area becomes smaller than the designed size, and thus continuity of quality of service (QoS) for handover requests cannot be guaranteed. To efficiently support the mobility of a mobile terminal (MT), we should adaptively cope with the resource demand of handover calls. This paper proposes a twofold resource-reservation scheme for OFDMA systems to guarantee continuity of QoS for various mobile multimedia services during MT handover from lightly to heavily loaded cells. Our twofold scheme attempts to guarantee service continuity for handover and to maximize resource allocation efficiency. We performed a simulation to evaluate our scheme in terms of outage probability, handover failure rate, total throughput, and blocking rate.

• 한국컴퓨터정보학회논문지
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• 제21권1호
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• pp.49-57
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• 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.

• 항공우주산업기술동향
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• 제8권2호
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• pp.54-64
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• 2010

위성은 지상에서의 발사부터 우주에서의 운용까지 다양한 진동환경에 놓인다. 따라서 위성 설계시, 진동은 중요한 고려 대상중 하나이다. 경제적인 발사 비용을 위해 구조체 경량화는 필수적이며, 이는 진동측면에서 위성체내의 장비들에는 불리한 여건이 되고 있다. 또한 영상에 대한 해상도가 높아짐에 따라 탑재체의 지향 안정성의 보장을 위해 탑재체로 전달되는 하중에 대한 요구조건도 엄격해지고 있다. 이러한 상황을 해결하고자 진동절연 시스템이 도입되었으며, 발사체로 부터 전달되는 진동을 감소시키거나, 궤도상 운용중 위성내 장비들이 발생시키거나 이들로 전달되는 진동을 차단하는 방법이 적용된다. 본 논문에서는 진동저감과 관련된 최근의 위성체/발사체 적용 사례들을 살펴보고, 이를 통해 향후 진동절연 시스템 적용에 필요한 고려 사항들을 확인하고자 한다.