• 전기학회논문지
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• 제59권3호
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• pp.515-524
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• 2010

Recently, many actions are taking to accelerate progress toward social consensus and implementation of Smart Grid. Smart Grid refers to a evolution of the electricity supply infrastructure that monitors, protects, and intelligently optimize the operation of the interconnected elements including various type of generators, power grid, building/home automation system and end-use consumers. The most distinguished element will be Advanced Metering Infrastructure (AMI) that will be installed to every end-use consumer's home or building and optimize the energy consumption of the end-use consumer. The key function of AMI is energy management capability that coordinates and optimally controls the various loads according to the operating condition and environments. In this study, we figure out the basic function of AMI in Smart Energy House that can be defined as a model house implementing in Smart Grid. This paper proposes the energy management algorithm that will be implemented in AMI at Smart Energy House. The paper also show how energy saving in Smart Energy House can be achieved applying the proposed algorithm to an actual house model that has mainly lighting, air-conditioning, TV loads.

• Journal of Biosystems Engineering
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• 제37권3호
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• pp.140-147
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• 2012

Purpose: This study was conducted to understand the work performance of crank-type rotavators and compare them with those of rotary-type rotavators in Korean farmland conditions. Methods: Tillage operations were carried out using both rotavators with the same nominal rotavating width and rated power. During the operations, PTO speed and torque, actual work speed, and rotavating width and depth were measured. To evaluate work performance, pulverizing ratio, inversion ratio, and specific volumetric tilled soil were calculated and compared for each rotavator. Results: It is found that the crank-type rotavator has better specific volumetric tilled soil performance and deep tillage, while the pulverizing ratio is worse. Conclusions: Crank-type and rotary type rotavator have diffenent properties each other in several work performances. It's important, therefore, to choose a suitable type of rotavator that satisfy the farmer's requirements in accordance with the condition of field and the purpose of tillage operation.

• 한국분무공학회지
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• 제25권2호
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• pp.45-50
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• 2020

Recently, global warming and environmental pollution are becoming more important, and fuel economy is becoming important. Each automobile company is actively developing various new technologies to increase fuel efficiency. CVVD(Continuously Variable Valve Duration) system means a device that continuously changes the rotational speed of the camshaft to change the valve duration according to the state of the engine. In this paper, VVT(Variable Valve Timing) and CVVD were applied to a single-cylinder diesel engine, and the characteristics of intake and exhaust flow rate and in-cylinder pressure characteristics were analyzed by numerical analysis. In order to analyze the effect of CVVD on the actual engine operation, the study was performed by setting the valve control and injection pressure as variables in two sections of the engine operating region. As a result, In the case of applying CVVD, the positive overlap with the exhaust valve is maintained, thus it is possible to secure the flow smoothness of air and increase the volumetric efficiency by improving the flow rate. The section 2 condition showed the highest peak pressure, but the pressure rise rate was similar to that of the VVT 20 and CVCD 20 conditions up to 40 bar due to the occurrence of ignition delay.

• 기록학연구
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• 제61호
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• pp.157-190
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• 2019

기록물평가심의서는 기록물 평가업무의 과정과 결과를 담고 있다. 이 연구는 기록물관리 전문요원이 배치된 22개 교육(지원)청의 2018년 기록물평가심의서를 분석한 것이다. 분석결과의 신뢰성 확보를 위해 분석데이터 작성기준을 적용하여 데이터 작성의 일관성을 유지하고 평가절차별, 보존기간별 통계를 교차검증 하였다. 기록물평가심의서 분석을 통해 기록물평가실태를 파악하고 처리과 기록물관리, 기록물관리 전문요원의 평가업무, 기록물평가심의회 운영의 측면에서 실무에 적용 가능한 개선방안을 제안하였다.

• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.111-118
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• 2019

Greenhouse gas emissions have a profound effect on global warming. Various environmental regulations have been introduced to reduce the emissions. The largest amount of greenhouse gases, including carbon dioxide, is produced in the steel industry. To decrease carbon dioxide emission, hydrogen-based iron oxide reduction, which can replace carbon-based reduction has received a great attention. Iron production generates various by-product gases, such as cokes oven gas (COG), blast furnace gas (BFG), and Linz-Donawitz gas (LDG). In particular, COG, due to its high concentrations of hydrogen and methane, can be reformed to become a major source of hydrogen for reducing iron oxide. Nevertheless, continuous COG cannot be supplied under actual operation condition of steel industry. To solve this problem, this study proposed to use two alternative COG-based fuel mixtures; one with natural gas and the other with biogas. Reforming study on two types of mixed gas were carried out to evaluate catalyst performance under a variety of operating conditions. In addition, methane conversion and product composition were investigated both theoretically and experimentally.

• Biotechnology and Bioprocess Engineering:BBE
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• 제2권2호
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• pp.77-81
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• 1997

Removal of nitrogen compound from waste water is essential and often accomplished by biological process. To prevent washout and to develop an efficient bioreactor, immobilization of sutibal microorganisms could be sensible approach. Strains and permeabilized cell encapsulated in cellulose nitrate microcapsules and immobilized on polystyrene films were prepared by the method described in the previous study. In the wastewater treatment system, nitrification of ammonia component is generally known as rate controlling step. To enhance the rate of nitrification, firstly nitrifying strains Nitrosomonas europaea(IFO14298), are permeabilized chemically, and immobilized on polystyrene films and secondly oxidation rates of strain system and permeabilized strain system are compared in the same condition. with 30 minute permeabilized cells, it took about 25 hours to oxidize 70% of ammonia in the solution, while it took about 40 hours to treat same amount of ammonia with untreated cells. All the immobilization procedures did not harm to the enzyme activity and no mass transfer resistance through the capsule well was shown. In the durability test of immobilized system, the system showed considerable activity for the repeated operation for 90 days. With these results, the system developed in this study showed the possibility to be used in the actual waste water treatment system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.421-426
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• 2009

Recently, the design process for a railway bogie frame in Europe has been carried out according to the norm EN 13749. The activities in the norm EN shall demonstrate that the design of the bogie frame fulfills the acceptances of 4 steps of the program such as structural calculation, static tests, fatigue test and on-tracks tests. At the end of the acceptance program, the on-tracks tests have the aim to measure the real stress history generated in operation and to verify that they are reasonably next to those calculated and measured on the test rig. Therefore, in order to assure the safety of the railway vehicle, it is important to examined the durability of that under load histories measured from on-tracks tests. In this study, under variable amplitude loading based on the actual acceleration history, fatigue analysis of the welding bogie frame is investigated by using durability software. Moreover, the fatigue life of the frame under the loading in the norm EN fatigue test condition is evaluated and compared with the life under variable amplitude loading.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권2호
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• pp.253-270
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• 2013

To achieve accurate localization information, complex algorithms that have high computational complexity are usually implemented. In addition, many of these algorithms have been developed to overcome several limitations, e.g., obstruction interference in multi-path and non-line-of-sight (NLOS) environments. However, localization systems those have complex design experience latency when operating multiple mobile nodes occupying various channels and try to compensate for inaccurate distance values. To operate multiple mobile nodes concurrently, we propose a localization system with both low complexity and high accuracy and that is based on a chirp spread spectrum (CSS) radio. The proposed localization system is composed of accurate ranging values that are analyzed by simple linear regression that utilizes a Big-$O(n^2)$ of only a few data points and an algorithm with a self-calibration feature. The performance of the proposed localization system is verified by means of actual experiments. The results show a mean error of about 1 m and multiple mobile node operation in a $100{\times}35m^2$ environment under NLOS condition.

• 정보처리학회논문지D
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• 제12D권7호
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• pp.1031-1038
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• 2005

본 논문에서는 시스템 사용현황을 파악할 수 있는 데이터를 최대수용 트래픽양과 실제 트래픽량으로 구분해서 측정하며 프로토콜 변경에 따른 트래픽량 변화와 사고발생시의 과부하 조건에서의 트래픽을 분석할 것이다. 이로 인해 전력감시제어설비의 안전성을 극대화할 수 있는 계기를 미련하고자 한다 또한, 현재 유통되고 있는 트래픽이 어느 정도인지를 알고 그 증가율 추세를 파악하여 앞으로 예상되는 트래픽량을 미리 예측하여 필요한 대역폭을 미리 확보하는 자료로 활용하고, 네트워크 정보분석을 통한 한정된 네트워크 자원의 효율적인 배치로 안정된 전력감시페어시스템의 운용을 가능하게 함으로써 신뢰성을 향상시킬 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.114-119
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• 2004

Endbeam is an important structural member of freight bogie for the support of service loading. In general, more than 25 years' durability is necessary. However, endbeam occur fatigue fracture in dynamic stress concentration location because comparatively strength and stiffness are low. Therefore, structure analysis is performed to evaluate structural problem of endbeam and local strain range as durability analysis. The number of cycles is extracted concerning the bogie in operation by measurement dynamic stress time history on critical part which is crack initiation in actual fact. At this time rainflow cycle counting is used to consider change of stress for operating condition. Based on the fatigue life curves and the stress analysis, the fatigue life of the endbeam is predicted and compared with the experimentally determined fatigue life, resulting in a fairly good correlation.