• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.241-269
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• 2012

Wireless networks composed of multimedia-enabled resource-constrained sensor nodes have enriched a large set of monitoring sensing applications. In such communication scenario, however, new challenges in data transmission and energy-efficiency have arisen due to the stringent requirements of those sensor networks. Generally, congested nodes may deplete the energy of the active congested paths toward the sink and incur in undesired communication delay and packet dropping, while bit errors during transmission may negatively impact the end-to-end quality of the received data. Many approaches have been proposed to face congestion and provide reliable communications in wireless sensor networks, usually employing some transport protocol that address one or both of these issues. Nevertheless, due to the unique characteristics of multimedia-based wireless sensor networks, notably minimum bandwidth demand, bounded delay and reduced energy consumption requirement, communication protocols from traditional scalar wireless sensor networks are not suitable for multimedia sensor networks. In the last decade, such requirements have fostered research in adapting existing protocols or proposing new protocols from scratch. We survey the state of the art of transport protocols for wireless multimedia sensor networks, addressing the recent developments and proposed strategies for congestion control and loss recovery. Future research directions are also discussed, outlining the remaining challenges and promising investigation areas.

• 지구물리와물리탐사
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• 제27권1호
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• pp.69-83
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• 2024

사용후핵연료 심층처분 부지조사는 그 중요성과 특수성을 고려할 때, 터널, 교량 등과 같은 일반적인 지반조사와는 달리 높은 수준의 품질관리가 요구된다. 본 논문에서는 단계별 부지조사에 적용할 물리탐사 기법을 선정하고, 탐사방법별 물리탐사 수행지침서를 작성한 사례를 소개하고자 한다. 물리탐사 수행지침서는 탐사계획, 자료획득, 자료처리 및 해석의 수행 절차와 고려사항 및 품질관리에 대한 내용이 포함되어 있으며, 이 중 항공전자탐사와 탄성파 반사법탐사 내용을 간략히 정리하였다.

• 한국소음진동공학회논문집
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• 제17권1호
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• pp.72-79
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• 2007

정밀 장비 운전시 지반진동 절연을 목적으로 널리 사용되는 공압제진대는 정밀 장비에서 요구하는 지반진동 규제의 강화에 따라 보다 개선된 절연성능을 요구받는다. 수동형 공압제진대의 경우, 제진대의 설계 변수들을 이용하여 그 성능을 개선하고 있으나, 제진대의 고유진동수 및 그 부근에서의 절연 성능 향상에는 한계가 있다. 이 연구에서는 진폭 의존성 등의 비선형성을 가지는 공압제진대에 대하여 비선형 강인성 능동제어이론인 시간지연 제어 기법을 적용하여 고유진동수 및 그 부근에서의 절연성능을 향상시키고자 한다. 공압제진대에 시간지연 제어기법을 적용하는 과정 및 능동제어 이론 적용에 따른 절연 성능 향상에 대한 모사실험 결과를 기술하고자 하며, 실험을 통하여 그 유효성 보이고자 한다.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제21권3호
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• pp.173-182
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• 2015

다양한 산업 자동화 분야에 활용되고 있는 모션 제어 시스템의 핵심 요소인 모션 제어기는 모션 명령의 전송의 주기성과 각 모터 드라이브 간 동작시점의 편차 최소화 등 실시간 성능 요구사항을 가진다. 이러한 요구사항을 만족시키기 위해 모션 제어기는 전통적으로 하드웨어 중심의 전용기 형태로 구현되어 왔으나 시스템 간 호환성과 확장성의 한계로 소프트웨어 중심의 범용 모션 제어기로 대체되는 추세이다. 한편 최근에는 저비용, 고성능의 범용 임베디드 플랫폼을 이용한 모션 제어기에 대한 관심도 커지고 있다. 본 논문에서는 고정밀 모션 제어 응용을 위해 ARM 기반 범용 임베디드 보드 상에서 Xenomai 기반 임베디드 제어기를 오픈소스 소프트웨어로 구현한 결과를 제시한다. 구현된 임베디드 제어기의 성능 평가를 위해 실제 응용 상황에서 측정 실험을 수행하였으며, 실험 결과 구현된 제어기는 드라이브 3개를 2 ms 제어주기로 동시 구동하는 환경에서도 안정적인 성능을 보임을 알 수 있었다.

• 한국철도학회논문집
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• 제16권6호
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• pp.519-527
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• 2013

무선 통신 기술 발전을 통하여 철도환경에서 안정적인 무선 접속과 다양한 통신 기능 제공이 가능함에 따라 철도서비스 고도화의 기반이 마련되었다. 특히, 최근의 무선 통신 기술은 향상된 철도 승객서비스뿐만 아니라 효율적이고 안전한 철도 운영을 가능하게 한다. LTE 기반의 무선통신 기술은 다양한 경제적 혜택과 높은 통신 성능을 철도 산업에 제공 가능함에 따라 세계적으로 차세대 철도 통신 시스템의 후보 기술로 각광받고 있다. 그러나 철도 통신은 열차의 안전한 운행을 위하여 매우 엄격한 철도 통신만의 요구 사항도 존재한다. 본 논문에서는 미래의 철도 통신이 반드시 갖추어야 할 요구사항과 기능을 설명한다. 또한 LTE 무선 통신 기술이 철도 분야의 통신 요구사항을 만족하는지에 대해서도 서술한다. 마지막으로 최근 진행되고 있는 차세대 철도 통합무선망의 국내외 표준화 동향과 구축일정에 대하여 설명한다.

• Pediatric Infection and Vaccine
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• 제27권3호
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• pp.180-183
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• 2020

목적: 국내 초중고 학교 등교재개 이후 소아에서의 코로나바이러스감염증-2019 (코로나19) 사례의 감염경로를 파악하고자 하였다. 방법: 2020년 5월 1일부터 7월 12일까지 국가감염병감시체계에 신고된 3-18세 소아 청소년 코로나19 확진자의 사례조사서 및 역학조사서를 분석하였다. 결과: 2020년 5월 국내 초중고 학교 등교 재개 이후 7월 12일까지 총 127명의 소아 청소년 코로나19 확진자가 신고되었다. 그 중 59명(46%)은 가족 및 친지로부터 전파된 사례였으며 18명(14%)은 학원 및 개인교습 중 전파되었다. 8명(6%)은 다중이용 시설에서 전파되었으며 3명(2%)은 학교에서 전파된 사례였다. 결론: 코로나19 감염예방을 위한 관리체계가 사전에 마련되고 준비된 경우 학교 내 코로나19 전파는 드물게 나타났다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 추계학술대회 학술발표 논문집
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• pp.452-455
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• 2000

There are increasingly important financial incentives and environmental consideration to improve the effluent quality of wastewater from domestic and industrial users. The activated sludge process is a widely used biological wastewater treatment process. The activated sludge process is complicated due to the many factors such as the variation of influent flowrate and concentration, the complexity of biological reactions and the various operation conditions. Nowadays, not only suspended solids and residual carbon, but also nitrogen and phosphorous concentration of the effluent water must be taken into account for the design and operation of wastewater treatment plants. Also, the effluent quality to be met are more stringent. Therefore, an intelligent control approach is required in order to successful biological nitrogen removal. In this paper, the strategies for dosage of extra carbon in the anoxic zone and DO concentration in the aerobic zone are presented and evaluated through the simulation using the denitrification layout of the IWA simulation benchmark implemented by Matlab$\^$/5.3/Simulink$\^$/3.0. The control strategy to achieve sufficient denitrification rates in an anoxic zone. Methanol is used as an external extra carbon source. The external extra carbon source is required for the nitrogen removal process because nitrogen and organic concentration are fluctuated in the influent flowrate. The dissolved oxygen is calculated by So concentration in the activated sludge model NO.1. The air flowrate of each aerobic reactor is intelligently controlled to achieve the predefined setpoints. Air flowrate is adjusted by the fuzzy logic controller that includes two inputs and one output. The objective function for the optimization procedure is designed to improve effluent quality and reduce the operating cost.

• 한국자동차공학회논문집
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• 제18권6호
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• pp.76-83
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• 2010

Recently, as the current and future emission regulations go stringent, the research of NOx reduction has become a subject of increasing interest and attention in diesel engine. Selective Catalytic Reduction (SCR) is one of the effective technology to reduce NOx emission from diesel engine. Especially, Urea-SCR that uses urea as a reductant is becoming increasingly popular as a cost effective way of reducing NOx emissions from heavy duty vehicles. In this research, we designed urea injector and DCU (Dosing Control Unit) specially developed for controlling the Urea-SCR process onboard vehicles. As passenger and commercial diesel engine experiment, we grasped characteristics of NOx emission and SCR catalyst temperature level in advance. As a result, highest NOx emission level was shown in condition of low engine speed and high load. On the other hand, SCR catalyst temperature was highest at high engine speed and load. On the basis of these result, we conducted the NOx reduction test at steady engine operating conditions using the urea injector and DCU. It was shown that 74% NOx conversion efficiency on the average and 97% NOx conversion efficiency was obtained at high SCR catalyst temperature.

• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 제6회 하계 Workshop (98 한국막학회, 국립환경연구원 국제 Workshop, 수자원 보전과 막분리 공정)
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• pp.95-112
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• 1998

Water quality in the public water course has been polluted more seriously than ever before due to the increase of the number and aremount of pollution sources such as domestic and industrial wastewater. For water quality conservation, the Korean government has been trying to construct sewage treatment facilities continually, of which treatment capacity reached to 11,452,400m$^{3}$/day in 1996. Night soil treatment facilites of m nationwide have the treatment capacity of 24,038m$^{3}$/day. But water quality has not been improved because the sewer systems were insufficient and the treatment efficiencies of sewage were not high, enough. For renovation of water quality, miscellaneous domestic wastewater must be treated because 27g BOD/day out of total 40g BOD/person-day come from miscellaneous wastewater, comparing to 13g BOD/day from night soil. However, sole treatment purifier treat only night soil from the flushing toilet. Therefore, it may be desirable to treat the miscellaneous domestic wastewater and the night soil from flushing toilet together by joint treatment purifier system as on-site domestic wastewater treatment technology. In Korea, the joint treatment purifier system, introduced in 1997, have the benefit as follows; i) good water poiluion control effect, ii ) good effect on river water flow, iii) water pollution control with sewage treatment facility, and iv) rapid pollution control effect, etc. In order to achieve a good effect as stated before, i ) strengthening effluent guideline including BOD, nitrogen and phosphorus, ii ) specializing operation to maintain high performance, and iii) supporting its construction and maintenance costs by the governmental level may be necessary: In addition, automation system of joint treatment purifier, technology for its package and compactness, and a new bio-media bio-filter with higher capacity should be further developed in agreement with a more stringent effluent guideline.

• Journal of Mechanical Science and Technology
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• 제14권1호
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• pp.72-83
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• 2000

In recent years considerable progress has been made in the characterisation of surface finish in three dimensions, and in the development of protocols which can be used for international standardisation. Although the subject as it has currently developed has much further to go if the process of surface characterisation is to impact on manufacture, control and specification of the manufacturing process itself. Researchers in this important area are beginning to realise that if the subject is to have great impact on manufacturing industries, surface characterisation must be broadened to include measures of surface integrity of the component and in addition be related to the functional demands imposed on the surface. The functional demands being a requirement of the engineering situation in which the components are employed. If these three factors are considered simultaneously, surface characterisation, surface integrity and component function, then a new and important subject is born, the subject of the Engineered Surface. Part 1 of this paper attempts to draw together the elements which go together to create the subject, 'The Engineered Surface'. The paper presents a method by which this important subject can be developed to the benefit of manufacturing industries. The paper also discusses the importance of a co-ordinated approach to the subject and the way that information can be documented to eventually provide a useful atlas of controlling parameters which are essential for a range of material processing industries as they strive to meet the ever more stringent and cost effective requirements of the manufacture.