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Practical Application Routing Implementation for Software-Defined Networking
공석환,SAIKIADIPJYOTI,박성용 에스케이텔레콤 (주) 2013 Telecommunications Review Vol.23 No.5
We present the design, implementation, and evaluation of an practical application routing implementation using the software-defined network (SDN). Our application routing is implemented by an OpenFlow controller that delegates read and write authority from the network’s administrators to end users, or applications and devices acting on their behalf. Users can then work with the network, rather than around it, to achieve better performance, security, or predictable behavior. Our application routing serves well as the next layer atop of the current SDN stacks using the North-bound layer. In this paper, our design address how to make an architecture for the application routing in the SDN, and what is needed for that architecture. Using a real OpenFlow testbed, we demonstrate our application routing's feasibility through the simple use case, and its usefulness by experiments.
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Service adaptive Network Architecture(SaNA)을 활용한 콘텐츠 전송 시스템
공석환(Seok-Hwan Kong),이재용(Jai-Yong Lee) 한국통신학회 2014 韓國通信學會論文誌 Vol.39 No.6(네트워크)
최근 몇 년 사이 인터넷을 통해 접속 가능한 디바이스가 다양해지는 한편 디바이스가 콘텐츠의 사용자가 아닌 제공자가 되면서 콘텐츠 트래픽이 급속하게 증가하고 있다. 이와 같은 콘텐츠 트래픽이 기존과는 다른 패턴을 갖기 때문에, 효율적인 콘텐츠 전송 서비스를 위한 다양한 연구가 진행 중이다. 대표적 콘텐츠 전송 서비스 기술인 CCN(Contents Centric Network)은 기존의 기술 구조와 상이한 혁신적인 구조를 갖고 있기 때문에 기존의 네트워크와의 호환 문제가 발생한다. 이와 같은 문제를 해결하기 위해 본 논문에서는 CCN과 기존 망과의 연동 시 효율적 콘텐츠 전송을 위한 SaNA(Software adaptive Network Architecture) 구조를 제안한다. 이는 미래 인터넷의 핵심 기술 분야인 CCN 과 소프트웨어 정의 네트워킹 기술(Software Defined Networking : SDN) 을 활용하여 기존 망에 점진적으로 적용해 나가기 위한 융합 시스템이다. SaNA를 통해 콘텐츠를 서비스하는 경우, 기존 네트워크 대비 네트워크 대역폭 효율성을 두 배로 높일 수 있고, 콘텐츠 전송 시간도 약 1.7 배 단축시킬 수 있다. (스타일-요약본문) In recent years, various contents traffics are increasing according to the various internet connectable devices which have become contents provider. Because these contents traffics show different pattern from previous one, many researches for efficient contents delivery system are in progress. CCN(Contents Centric Network), one of the representative research subject, has inter operation problem with a current network because it has clean-state architecture. In this point of view, this paper suggests the SaNA(Service adaptive Network Architecture) for efficient contents delivery when it inter operates with current network architecture. SaNA is a convergence system which can be gradually applied to current network using CCN and SDN(Software Defined Network) which are core future internet technologies. Appling this system on the contents delivery service, it can increase the network bandwidth utilization by two times and decrease the contents delivery time by 1.7 times.
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플래너 밀러 재제조를 위한 역설계 및 마모 분석에 관한 연구
최두한,공석환,변정원,김태우,홍대선 한국산업융합학회 2022 한국산업융합학회 논문집 Vol.25 No.6
The old machine tools that have been used for a long time cause both increase in defective rate and decrease in productivity compared to new machines due to wear and failure of their components. In order to improve productivity and quality of machined components through remanufacturing, it is necessary to analyze the wear and failure of major components of old machine tools. In this study, the process for reverse engineering is designed for the remanufacture of planner millers, which belong to a very large machine tool. Also, the suitability of the designed process is verified through the analysis of the selected remanufactured components. In the first step of the process, some major components of the aging planner miller are scanned using a 3D laser scanner. In the next step, reverse engineering is performed using the data obtained through 3D scanning. Finally, wear and failure analysis is performed by comparing the reverse engineering data with the scan data. As a result, this reverse design and wear analysis can complement the insufficient design database and reduce costs in the maintenance of remanufactured products.
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Ru 착화학물 기반의 전기화학발광 소자 내에서 PMMA 함유량에 의존하는 이온들의 이동현상
박희진,이현석,공석환,유영문,이지열,강문성 한국화상학회 2017 한국화상학회지 Vol.23 No.1
본 논문에서는 전기화학발광 소재로 널리 이용되는 Ruthenium 착화합물을 함유한 전기화학발광 소자의 활 성층 제작시, 인쇄성 및 공정성을 향상시키기 위해 Poly(methyl methacrylate) (PMMA)를 첨가하였을 때, PMMA의 함유량이 전기화학발광소자의 발광층 내 이온들의 이동 현상에 미치는 영향에 대하여 살펴보았다. 이를 위해, Ruthenium 착화합물과 이온성 액체가 9:1 비율로 섞인 용질이 Acetonitrile에 20 mg/ml 농도로 녹여진 용액과 Dichloromethane에 PMMA가 25 mg/ml의 농도로 용해된 용액을 세 가지 (10:0.14, 10:1 그리고, 10:3) 중량비로 섞어 서 준비한 용액으로부터 발광층을 형성하여 전기화학발광소자를 제작하고, 소자의 전기적 특성을 평가하였다. 그 결 과, 발광층 내의 PMMA 함유량이 증가할수록 Ruthenium 착화합물 기반 전기화학발광소자의 구동 전압은 점차 증가 하였고, PMMA의 양이 줄어들면 순방향 전압하의 전류와 역방향 전압하의 전류 차에 따라 나타나는 이력곡선 (hysteresis)이 점차 사라지는 것을 확인할 수 있었다. In this paper, we have investigated the effects of poly(methyl methacrylate) (PMMA), which is intentionally added to improve the printability and processability of ruthenium complex-based light-emitting layers, on the migration of ions in the emissive layer of the electrochemiluminescent (ECL) device. For this purpose, we fabricated the ECL devices with three different (ratios of 10:0.14, 10:1, and 10:3) solutions comprised in a 9:1 ratio mixture of ruthenium complex and ionic liquid dissolved in acetonitrile at a concentration of 20 mg/ml and a solution of PMMA dissolved in dichloromethane at a concentration of 25 mg/ml and evaluated the electrical characteristics of the devices. As a result, the driving voltage of the ruthenium complex-based ECL devices gradually increased as the PMMA contents in the layer increased. However, the hysteresis, that is the difference in the current flows under the forward and the reverse bias, was getting disappeared as the amount of PMMA decreased.
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전기자동차 충전기 쿨링시스템의 성능에 관한 실험적 연구
홍대선,최두한,공석환,김태우,임경석 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.12
As the global automobile market is rapidly changing from internal combustion engines to electric vehicles, the number of charging stations for electric vehicles continues to rise. For rapid charging, fast chargers are frequently used, and high current flows through the cable that connects a fast charger to a battery in electric vehicles. Also, heat is usually generated by the electric resistance of the charging cable. This heat causes a temperature rise in the cable and reduces the battery charging efficiency. Therefore, it is necessary to develop a cooling system that can solve these problems. An oil pump was used in a cooling system for transporting oil that absorbs heat. In this study, a series of experiments were conducted to verify the appropriate rotational speed of the oil pump for minimizing power consumption while maintaining the required cooling performance. Through these experiments, we investigated how the cooling capacity and power consumption change according to the rotational speed of the oil pump. Based on the results of the experiments, the appropriate rotational speed was derived. In conclusion, it is possible to reduce the power consumption of an electric vehicle charger's cooling system by using the appropriate rotational speed for the proposed oil pump. 세계 자동차 시장은 내연기관차에서 전기자동차로의 전환이 빠르게 이뤄지고 있으며, 이에 따라 전기자동차 충전인프라가 지속적으로 증가하고 있다. 전기자동차의 충전을 위한 급속충전기와 전기자동차 배터리를 연결하는 케이블에는 고전류가 흐르게 되는데, 이 과정에서 충전 케이블의 전기 저항에 의해 열이 발생된다. 이 열은 케이블 및 충전기의온도를 상승시켜 충전 효율을 감소시키게 되는데, 이러한 효율 감소를 해결하기 위해서는 케이블 냉각을 위한 쿨링시스템이 요구된다. 쿨링시스템에서 냉각유 펌프는 충전 케이블에서 발생한 열을 흡수하여 이동시키는 역할을 한다. 본 연구에서는 쿨링시스템의 냉각능력을 일정 수준으로 유지하면서 소비전력을 최소화하기 위한 냉각유 펌프 회전속도를 산출하기 위해 실험을 진행하였다. 본 실험을 통해 냉각유 펌프의 회전속도에 따라 냉각능력과 소비전력이 어떻게 변하는지분석하고, 이를 통해 쿨링시스템의 효율적인 펌프의 회전속도를 제안하였다. 제안된 냉각유 펌프의 적합한 회전속도를통해 전기자동차 충전기 쿨링시스템의 소비전력 절감이 가능하다.
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전산해석을 이용한 산업용 오일펌프 성능개선에 관한 연구
김진우,이현준,공석환,이성원,정원지 한국산업융합학회 2022 한국산업융합학회 논문집 Vol.25 No.6
Recently, interest in the circular economy has emerged in the industry. As a result, interest in Re-manufacturing, which makes old equipment similar to new products, is growing. In the machine tool industry with many aging equipment, the Re-manufacturing industry is essential, and among them, research on the performance improvement of gear type oil pumps was conducted. The purpose was to achieve the target performance of flow rate and volume efficiency by changing the shape of the gear pump housing clearance and inlet/outlet, and Computational Fluid Analysis and Central Composite Design were conducted using ANSYS CFX 2022 R2 and MINITAB®. The level of each determined factor was determined. 20 design points were derived, and the Flow Rate at each design point was calculated, and the Theoretical Flow Rate was calculated to obtain Volumetric Efficiency. The optimal design point was obtained when the Flow Rate was 140 lpm and the Volumetric Efficiency was maximum, the optimal design point was obtained when both were maximum, and the Surface Plot for each factor was obtained to identify the tendency.
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