• 상하수도학회지
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• 제19권2호
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• pp.149-154
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• 2005

Conventionally used flocculation tanks require large space and high energy requirement for mixing. Static flocculators using gravel bed filter operate at a lower flow rate ($5-10m^3/m^2{\cdot}h$). Further, the cleaning of this system is difficult. A novel high rate static flocculator/filter developed at UTS packed with buoyant media such as polystyrene, polypropylene has been found to operate at higher filtration rates (30-45 $5-10m^3/m^2{\cdot}h$). They can easily be cleaned with minimal energy. Detailed experiments conducted with an artificial kaolin clay solution show that buoyant media is an excellent static flocculator in producing uniform filterable microflocs (12-15 m) even when it is operated at a high rate of 30-40 m/h. Detailed filtration experiments were conducted in a wastewater treatment plant to treat the biologically treated effluent with a floating media of depth of 120 cm. This filter was able to remove majority of phosphorus and remaining solids. It reduced significantly the fecal coliforms and fecal streptoccoci, thus requiring less amount of chlorine for disinfection. The advantage of this system is the low energy and water requirement for cleaning of filter bed. The periodic backwash adopted 30 seconds air and water and 30 seconds water cleaning every 90 minutes filter operation. Thisis equivalent to 1-2% of filtered water production. Mechanical cleaning system on the other hand, requires very low energy requirement (<1% of filtered water production).

• 원자력산업
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• 8호
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• pp.35-52
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• 1978

The geologically favourable areas for the occurrence of uranium in Australia and the geology of the major deposits are discussed as well as exploration programs and expenditures. Australis has no short-term requirement for nuclear power generation and its

• 한국임산에너지학회:학술대회논문집
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• 한국산림바이오에너지학회 2011년도 정기총회 및 학술연구발표회
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• pp.81-83
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• 2011

• 한국통신학회논문지
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• 제40권9호
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• pp.1767-1775
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• 2015

무선 센서 네트워크는 다양한 응용 서비스에 이용이 가능한 네트워크이다. 다양한 응용 서비스에 따라서 서비스에서 요구하는 네트워크 전송량은 매우 다양하다. 특히 무선 센서 네트워크에서는 센서 노드의 에너지 소모를 줄이고 통신 효율성을 높이기 위해서 다양한 토폴로지 제어 방법들이 제시되어 왔다. 이러한 토폴로지 제어 방법들은 대부분 통신의 효율성 측면에서 연구가 되어왔기 때문에 실제 응용 서비스에서 요구되는 데이터 전송량을 만족시키지 못하는 문제점이 있다. 본 논문에서는 이러한 문제를 해결하기 위해서 응용 서비스에서 요구하는 데이터 전송량을 만족시킬 수 있도록 하는 토폴로지 제어 알고리즘을 제시하였다.

• KIEAE Journal
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• 제17권4호
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• pp.67-74
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• 2017

Purpose: As the recent climate environment changes so rapidly, environmental problems such as hot weather and fine dust have occurred, and interest in environmental policies and technology development is increasing in countries around the world. Similarly in the Architecture, researches to reduce greenhouse gas emissions and to reduce energy application are actively conducted. Looking at previous studies, it is analyzed that the electric VRF is more energy efficient than the gas engine VRF. However, energy costs have changed due to recent price hikes and discounts on gas charges due to high electricity consumption in summer. Method: In this study, the actual building of Gas Engine VRF system was modeled using SketchUp program, and EnergyPlus was used to simulate actual building. Also, Electric VRF system was simulated, and compared with Gas Engine VRF system. Result: The total secondary energy requirement of Electric VRF system was 19.6% less than that of the Gas Engine VRF system, But when analyzing with primary energy requirement, EHP used 15.8% more energy. CO2 emissions were also estimated to be 16.9% more EHP. Energy costs were 14.8% more in Electric VRF systems, because their electricity charges are 0.6 to 160% more expensive than gas charges.

• Asian-Australasian Journal of Animal Sciences
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• 제31권9호
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• pp.1431-1441
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• 2018

Objective: This study was conducted to assess the effects of replacing rice straw with different proportions of cassava pulp on growth performance, feed intake, digestibility, rumen microbial population, energy partitioning and efficiency of metabolizable energy utilization in beef cattle. Methods: Eighteen yearling Thai native beef cattle (Bos indicus) with an average initial body weight (BW) of $98.3{\pm}12.8kg$ were allocated to one of three dietary treatments and fed ad libitum for 149 days in a randomized complete block design. Three dietary treatments using different proportions of cassava pulp (100, 300, and 500 g/kg dry matter basis) instead of rice straw as a base in a fermented total mixed ration were applied. Animals were placed in a metabolic pen equipped with a ventilated head box respiration system to determine total digestibility and energy balance. Results: The average daily weight gain, digestible intake and apparent digestibility of dry matter, organic matter and non-fiber carbohydrate, total protozoa, energy intake, energy retention and energy efficiency increased linearly (p<0.05) with an increasing proportion of cassava pulp in the diet, whereas the three main types of fibrolytic bacteria and energy excretion in the urine (p<0.05) decreased. The metabolizable energy requirement for the maintenance of yearling Thai native cattle, determined by a linear regression analysis, was $399kJ/kg\;BW^{0.75}$, with an efficiency of metabolizable energy utilization for growth of 0.86. Conclusion: Our results demonstrated that increasing the proportion of cassava pulp up to 500 g/kg of dry matter as a base in a fermented total mixed ration is an effective strategy for improving productivity in zebu cattle.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.726-737
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• 2017

The use of energy storage systems (ESSs) has become a feasible solution to solve the wind power intermittency issue. However, the use of ESSs increases the system cost significantly. In this paper, an optimal power flow control scheme to minimize the ESS capacity is proposed by using the zero-phase delay low-pass filter which can eliminate the phase delay between the dispatch power and the wind power. In addition, the filter time constant is optimized at the beginning of each dispatching interval to ensure the fluctuation mitigation requirement imposed by the grid code with a minimal ESS capacity. And also, a short-term power dispatch control algorithm is developed suitable for the proposed power dispatch based on the zero-phase delay low-pass filter with the predetermined ESS capacity. In order to verify the effectiveness of the proposed power management approach, case studies are carried out by using a 3-MW wind turbine with real wind speed data measured on Jeju Island.

• Asian-Australasian Journal of Animal Sciences
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• 제9권1호
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• pp.69-74
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• 1996

There levels of dietary ME (3,000, 3,200 and 3,400 kcal/kg) and four levels of Total Sulphur Amino Acid (TSAA) (0.73, 0.83, 0.93 and 1.03%) were studied in the starter period (0-3 wks) of the broilers. Three levels of dietary ME (3,000, 3,200 and 3,400 kcal/kg) combined with four levels of TSAA (0.65, 0.72, 0.79 and 0.86%) were studied in the grower period (3-6 wks). The crude protein content of the diet of the starter period was 23% while the diet of the grower period was 20%. The performance data of the starter broilers indicated that the dietary energy levels had no significant effects on body weight gain, feed intake and feed:gain ratio. However, TSAA levels had a significant influence on the growth and feed parameters. The response pattern for the grower period was similar to the starter period. The present experiment showed that in the tropics the TSAA requirement for the starter period was between 0.83 to 0.93% which is similar to the values recommended by NRC while for the grower period the TSAA requirement was between 0.79 to 0.86% at all the three energy levels which is higher than the values recommended by NRC.

• Journal of Advanced Marine Engineering and Technology
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• 제38권6호
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• pp.751-760
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• 2014

무인잠수정은 한정된 탑재공간으로 인해 에너지 밀도가 높은 에너지원이 적용되어야 하며, 특히 장시간 운행을 목표로 하는 무인잠수정의 경우 요구되는 총 전력에 대한 에너지원의 탑재 가능 여부를 가장 우선적으로 검토하여야 한다. 이에 본 논문에서는 무인잠수정의 필요에너지에 따른 에너지원의 탑재가능성에 대해 분석하였고, 특히 에너지밀도가 높은 연료전지 시스템에 대한 연료 및 산화제의 필요량을 산출하여 내부 탑재가능성에 대한 배치성을 분석하였다. 또한 수중환경에서의 운용에 따른 밀폐형 연료전지 시스템에 대한 구성 방안을 도출하여 1kW급 고분자 전해질 연료전지 시스템을 이용하여 실험을 통해 적용 가능성을 검토하였다.

• 방사성폐기물학회지
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• 제21권1호
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• pp.165-173
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• 2023

Various linear system solvers with multi-physics analysis schemes are compared focusing on the near-field region considering thermal-hydraulic-chemical (THC) coupled multi-physics phenomena. APro, developed at KAERI for total system performance assessment (TSPA), performs a finite element analysis with COMSOL, for which the various combinations of linear system solvers and multi-physics analysis schemes should to be compared. The KBS-3 type disposal system proposed by Sweden is set as the target system and the near-field region, which accounts for most of the computational burden is considered. For comparison of numerical analysis methods, the computing time and memory requirement are the main concerns and thus the simulation time is set up to one year. With a single deposition hole problem, PARDISO and GMRES-SSOR are selected as representative direct and iterative solvers respectively. The performance of representative linear system solvers is then examined through a problem with an increasing number of deposition holes and the GMRES-SSOR solver with a segregated scheme shows the best performance with respect to the computing time and memory requirement. The results of the comparative analysis are expected to provide a good guideline to choose better numerical analysis methods for TSPA.