• Journal of the Korea Society for Simulation
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• v.14 no.3
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• pp.119-127
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• 2005

Web services and their composition (web processes) are promising technologies to efficiently integrate disparate software components over various types of systems. As many web services are nowadays available on Internet, quality of services (QoS) and performance/cost become increasingly important to differentiating between similar service providers. In this work, we introduce sPAC (Web Services Performance Analysis Centre) and show how customers can benefit from sPAC to consider performance in composing and commercializing web services. sPAC 1) helps users to graphically describe the workflow of web services, 2) invokes web services to test out performance for light load conditions, 3) automatically converts the web services and the flow between them into a simulation model, 4) conducts extensive simulations for heavy load conditions and various usage patterns, and 5) reports analysis results and estimation data for the web services.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.50-55
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• 2005

웹 서비스와 웹 프로세스(Web Processes)는 다양한 시스템 상에서 이종의 소프트웨어 컴포넌트들을 효과적으로 통합할 수 있는 기술이다. 웹 서비스의 활용이 증대함에 따라 성능(performance), 비용(cost) 등 005(Quality of Service)는 서비스 제공자들 간의 차별화를 위한 요건으로 그 중요성이 증가하고 있다. 본 논문에서는 웹 서비스 성능 분석 도구인 sPAC(Web Service Performance Analysis Center)을 소개하여, 웹 서비스 조합시 성능의 만족 여부를 미리 고려할 수 있음을 보인다. sPAC은 1) 그래픽 기반 웹 프로세스 구성 환경을 제공, 2) 경부하(light load) 조건에서의 성능 테스트를 위해 웹 서비스를 호출, 3) 웹 프로세스에 대한 시뮬레이션 모델을 자동 생성 하여, 과부하(heavy load) 조건에서 시뮬레이션 기반의 성능 분석 수행, 4) 웹 서비스의 성능 분석 결과와 평가 데이터의 보고서 생성을 제공한다.

• Journal of the Korea Safety Management & Science
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• v.19 no.1
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• pp.87-94
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• 2017

In construction work, safety accidents often occur in combination with unstable physical and human conditions during preparation and execution of work. In Korea, the accident rate is higher to that of any country in the world. Therefore, it is necessary to take measures by fundamental prescription. In this paper, in the case of construction safety management, we tried to find a reasonable alternative through a questionnaire survey to apply to subcontracting and small-scale construction. In conclusion, workers who are well aware of the task could be able to reduce the accident rate by deploying them as safety management officers after receiving the training.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.137-140
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• 2004

Hydraulic structures have been constructed with low cost concrete so as to increase the investment efficiency. As the construction of agricultural irrigation and drainage project is concentrated on off-farming season and come to construction less than 28-day strength in quality control. As we are aware the major thrust construction of short period is now in hydraulic structures rather then the large- scale. This paper will propose the relationship between the 7-day and 28-day compressive strength of concrete be investigated. Test will be carried out on nine different concrete mixes and 180 core drilled form the hydraulic structures with 7-day and 28-day compressive strengths ranging approximately from 24 to 30Mpa.

• ETRI Journal
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• v.44 no.3
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• pp.491-503
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• 2022

Metal-oxide-semiconductor field-effect transistors (MOSFETs) are continuously scaling down in the nanoscale region to improve the functionality of integrated circuits. The scaling down of MOSFET devices causes short-channel effects in the nanoscale region. In nanoscale region, leakage current components are increasing, resulting in substantial power dissipation. Very large-scale integration designers are constantly exploring different effective methods of mitigating the power dissipation. In this study, a transistor-level input-controlled stacking (ICS) approach is proposed for minimizing significant power dissipation. A low-power ICS approach is extensively discussed to verify its importance in low-power applications. Circuit reliability is monitored for process and voltage and temperature variations. The ICS approach is designed and simulated using Cadence's tools and compared with existing low-power and high-speed techniques at a 22-nm technology node. The ICS approach decreases power dissipation by 84.95% at a cost of 5.89 times increase in propagation delay, and improves energy dissipation reliability by 82.54% compared with conventional circuit for a ring oscillator comprising 5-inverters.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.820-823
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• 2008

본 논문은 기존의 XIP 기법에서 발생할 수 있는 메모리 접근 성능저하를 해결하기 위한 동적 XIP 기법을 제안하였다. 동적 XIP 기법은 상대적으로 성능저하가 적을 것으로 예상되는 코드 페이지들을 동적으로 선택하여 XIP 영역으로 설정하고, 성능저하가 크게 나타날 것으로 예상되는 코드 페이지들을 램 캐시에 캐싱하여 성능을 향상시킨다. 본 논문은 램 캐시를 관리하기 위해 MIN 캐시 알고리즘 및 메모리 접근 비용을 고려한 오프라인 캐시 알고리즘과, 페이지 접근에 대한 최신성(Recency) 및 슬라이딩 윈도우에 저장된 페이지 접근 기록에 기반하여 메모리 접근 비용을 예측하는 온라인 캐시 알고리즘, 온라인 캐시 알고리즘의 램 캐싱 판단의 정확성을 높이는 기법을 제안하였다. 본 논문은 온·오프라인 알고리즘의 성능비교를 위해 시뮬레이터를 통해 성능을 평가하였고, 유용성을 시험하기 위해 온라인 알고리즘을 리눅스를 기반으로 구현하여 성능을 평가하였다. 본 논문에서 제안한 동적 XIP는 실제 구현한 환경에서 실험한 결과, 작은 크기의 캐시를 사용하고도 수행시간에서는 최대 27%, 에너지 소모량에서는 최대 24%의 성능이 향상됨을 보였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.855-857
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• 2007

In recent years, Wireless Mesh Network (WMN) is a compelling topic to many network researchers due to its low cost in deployment, ease and simplicity in installation and scalability and robustness in operation. In WMN, Gateway nodes (Access Point-AP) are in charge of steering the traffic from the external network (e.g. Internet...) to client devices or mesh clients. The limited bandwidth of wireless links between Gateways and intermediate mesh routers makes the Gateways becomes the bottleneck of the mesh network in both uplink stream and downlink stream. In this paper, we propose a mechanism to permit Gateways collaboratively work to manipulate the traffic to fit our network. They will move the traffic from congested links to the unused capacity on other links.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.225-234
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• 2012

In Wireless Sensor Networks (WSNs) where deployed sensors are not stationary, the most important demand of is to design a cost effective and reliable network. This paper proposes an energy aware network construction and routing scheme, which is based on the hierarchical approach to distribute the task in some sensors in order to prolong the network lifetime. It aims to make even the energy consumption on constitute nodes. With the node hierarchy, the sink initiates the construction by electing gateway nodes in the network and the elected gateway nodes participate to form logical clusters by electing a cluster head in each cluster. Then, the cluster heads aggregate data from the sensing sensors and transmit the data to the sink through the gateway. Our simulation result illustrates that the proposed scheme provides a basement to reduce the source of energy dissipation in network construction, and as well as in data routing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.43-51
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• 2015

Upcoming cellular networks such as LTE-advanced and IEEE 802.16m are enhanced by relay stations to support high data rate multimedia services and minimize the shadow zone with low cost. Enhancing the relay stations, however, divides the multihop cellular network into smaller microcells and the distance between microcells is closer, which intends large intra-cell and inter-cell interference. Especially the access link on downlink in the OFDMA cellular network is the throughput bottleneck due to the severe interference caused by base stations and relay stations transmitting large data to mobile stations simultaneously. In this paper, we present interference aware channel allocation algorithm to avoid severe interference on multihop cellular networks with random topology. Proposed algorithm increases SINR(signal to interference plus noise ratio) and decreases number of required control messages for channel allocation, so that increases overall throughput on the networks.

• The KIPS Transactions:PartA
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• v.13A no.2 s.99
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• pp.147-156
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• 2006

Recently, streaming service accounts for large part of internet traffic and it is becoming the most popular service. Because of P2P's scalability, P2P-based streaming system is proposed. There are frequent leave and join of a node. To overcome the group dynamics, Multiple Multicast Trees Methods were suggested. However, since they did not consider discrepancy in peers' capacity, it may cause the trees to be long and unstable. So we suggest Resilient Capacity-Aware Multicast Tree construction scheme (R-CAT) that promotes superior peer to upper position in the tree and construct more stable and short multicast trees. By simulation we can show that R-CAT cost more overhead packets for tree joining process, but it reduce the end-to-end delay of the resulting tree and the number of packets lost during the node joining and leaving processes much more than SplitStream.