• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.10a
• /
• pp.682-683
• /
• 2014

최근 IT업체들은 온라인 상에서 소비자들이 평소에 쏟아내는 의견들을 수집, 축적해서, 원하는 키워드를 중심으로 내용을 분석함으로써, 특정 주제에 대해 어떤 여론이 형성되고 있으며, 여론이 어떻게 전파되고 있는지 경로를 파악할 수 있는 소셜 빅데이터 분석 툴을 경쟁적으로 개발하고 있다. 본 논문에서는 소셜 빅 데이터를 분석함에 있어 이슈를 감지하고 예측하는 기술을 실제 사례에 적용하여 분석한 결과를 고찰해 보고자 한다. 소셜 미디어 데이터 패턴을 비교 분석하고 부정이슈 감지를 위해 부정 여론을 확산시키는데 영향을 미치는 내용과 작성자를 독립변수로 하고, 평균 이슈 도달 시간 및 속도를 종속변수로 정의한다. 부정 여론 형성의 영향력은 트윗수, 리트윗 수를 기준으로 이슈 감지한다. 분석결과 전체 트윗 중 리트윗 메시지가 큰 비중 차지하고 이슈에 대한 버즈가 증가할수록 리트윗 비중이 증가하였으며 크게 확산될 때는 리트윗량이 크게 증가하여 짧은 시간 안에 넓게 확산하였다.

• Annual Conference of KIPS
• /
• 2024.05a
• /
• pp.95-98
• /
• 2024

현대 소프트웨어는 다양한 서비스 구조가 사용되고 있다. 이러한 환경에서는 각 서비스의 요구사항을 충족시킬 수 있는 기술들이 필요하며, Wasm(WebAssembly)은 많은 서비스에서 요구하는 조건을 만족시킬 수 있는 장점을 가지고 있다. 이에 본 논문에서는 WasmEdge와 다양한 런타임 환경의 성능을 비교하기 위해 로직 실행 시간, HTTP 부하 테스트, 컨테이너 이미지 크기의 세 가지 지표를 분석한다. 결과는 로직 실행 시간에서 Wasm이 1.81초로 가장 빨랐고, 컨테이너 이미지 크기 역시 9.54MB로 가장 작았다. 마지막으로 HTTP 부하 테스트에서는 가장 빠른 트래픽 처리를 보여준 Spring Boot의 평균 초당 15076개보다 WasmEdge가 9239개로 트래픽 처리가 느렸지만, 로직 실행 속도와 컨테이너 이미지 크기가 작기 때문에 충분히 서버리스 컴퓨팅, 마이크로 서버, 엣지 컴퓨팅 분야에서 요구하는 조건을 만족시킬 수 있다.

• Journal of KIISE:Computer Systems and Theory
• /
• v.36 no.2
• /
• pp.102-110
• /
• 2009

The memory wall is the growing disparity of speed between CPU and memory outside the CPU chip. An economical solution is a memory hierarchy organized into several levels, such as processor registers, cache, main memory, disk storage. We introduce a novel memory hierarchy optimization technique in Linux based embedded systems using on-chip SRAM for the first time. The optimization technique allocates On-Chip SRAM to the code/data that selected by programmers by using virtual memory systems. Experiments performed with nine applications indicate that the runtime improvements can be achieved by up to 35%, with an average of 14%, and the energy consumption can be reduced by up to 40%, with an average of 15%.

• Fire Science and Engineering
• /
• v.18 no.1
• /
• pp.31-36
• /
• 2004

The purpose of this study is to present data for the reusing, rehabilitation and estimation of safety of RC structure damaged by fire, and for the prevention of explosive spatting by investigation the properties of explosive spalling, compressive strength and ultrasonic pulse velocity according to kinds of fine aggregate, admixture and water-cement ratios. In explosive spalling properties with kinds of aggregate, explosive spalling does not appear or little at surface in the case of used sea sand, but the case of using recycled sand or crushed sand is worse and worse. Property with the kind of admixture does not appear specially. And high strength concrete with W/C 30.5% was taken spalling, but 55% does not appear. It is found that residual compressive strength after exposed at high temperature showed 45％ in W/C 55%, and 64％ in W/C 30.5％ of its original strength averagely. Ultrasonic pulse velocity is different with kinds of aggregate. W/C. and heating time. When 3 month age after heating ultrasonic pulse velocity is recovered abut 1.3％～8.4％ of its 1 month age after heating.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.1
• /
• pp.55-64
• /
• 1987

The schemes synthesizing the instantaneous unit hydrograph(IUH) are presented by using the geomorphologic parameters of a basin. To this end, the channels in the network are numbered according to the Strahler scheme, and the mathematical formulation corresponding to a dynamic probability theory for deriving the geomorphologic IUH(GUH) is refered to the existing techniques adopted by Rodriguez-Iturbe and Valdes. Also, the mean runoff velocity is applied for expressing a dynamic state of flow. The applicability of the GUH to the real drainage basins is tested by using the data observed in a few basins with areas of the order of 9.2, 20, 33.63, and $109.73km^2$ in Korea. The test is carried out by checking the discrepancies between the observed and simulated values for the peak discharge and its time of occurrence which are the most important parameters of an IUH by varing the mean runoff velocity and the inputs. As a result, good agreement is found between them, and it is shown that the variability in peak discharge of hydrograph depends on the mean runoff velocity more than the constant loss rate.

• Applied Chemistry for Engineering
• /
• v.17 no.1
• /
• pp.12-15
• /
• 2006

The purpose of this study was to investigate the effect of reaction conditions, solvents, and surfactants on the average size and size distribution of silica particles in preparing silica fine powders by sodium silicate. Silica fine particles were synthesized by varying kinds of solvents and surfactants using the emulsion method. Span 20, Span 40, Span 60, and Span 80 were used as nonionic surfactants, Dispersing solvents were n-Hexane, n-Heptane, iso-Octane, and n-Decane of the alkane group. In these experiments, it was known that the optimum dispersion stirring time to form the emulsion of the constant size was around 6 min. The mean sizes of silica particles, at a variety of the dispersion stirring speeds, decreased as the dispersion stirring speed increased. Also, in the case of the solvents, the size of the formed silica particles decreased when the molecular weight of the solvent increased. Lastly, in the case of the surfactants, the mean size of silica particles increased as the hydrophobic lipophilic balance (HLB) value of the surfactant decreased.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.5
• /
• pp.871-885
• /
• 2015

The improved DFSA for 2.4GHz multi-tags active RFID is suggested in 2 different ways: 1) simplified tag collection and Ack procedure using query command and 2) modified Schoute's method to control the number of slots in the frame. To evaluate the performance of the improved system we develop the simulation model. Varying the number of tags in the system we track the performance measures such as throughput, recognition time for multi-tags and tag recognition rate during a given time. The suggested method shows the best performance over all measures. Simplification of collection and Ack commands using query commands contributes to reducing tag recognition time. And the modified Schoute's method which controls the frame size using $k_1$ and $k_2$ contributes to throughput improvement and reduces target cognition time by reducing the number of collection rounds.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.16 no.1
• /
• pp.147-156
• /
• 2017

This paper analyzes the performance limit of WAVE system for the platooning service requirements which is referred from the de facto standards. The performance of the packet error rate and mean delay as key parameters in the wireless communication systems should be satisfied to provide safety to the platooning vehicles. The test scenarios are conducted by considering the following vehicle groups: platooning vehicles, vehicles within a hop distance and vehicles within two hop distance( called hidden node vehicles). The models of packet error rate and delay deals with the topology of aforementioned vehicle groups, vehicle speed and communication range. The numerical results are obtained in terms of packet size, packet arrival rate and data transmission rate. Finally, this paper suggests the robust range of packet error rate and delay for the WAVE system to provide the platooning vehicle service.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.1 no.2
• /
• pp.74-83
• /
• 1997

The definition of burning admittance and conventional n-$\tau$ stability rating technique are combined to investigate the high frequency combustion instabilities inside the cylindrical combustion chamber. Perturbed flow variables are written as the sum of fluctuating and time-averaged mean quantities on the assumption that the terms of the order higher than unity are sufficiently small, hence linearized governing equations could be formulated. Chamber admittances up and downstream of the flame front calculated with appropriate boundary conditions result in the burning admittance and corresponding n-$\tau$ neutral stability curve. Configurational and operational design factors are tested to detect the unstable wave-induced LOX-RP1 combustion instabilities. Operational design factors, e.g. pressure or O/F ratio, appear less influential to drive high frequency instability while the location of the flame front and configurational factors enhance or deteriorate the stabilities strongly. Conclusively, LOX-RP1 combustion inside the cylindrical combustion chamber is apt to be unstable against long residence time and shortened chamber length.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.9 no.5
• /
• pp.59-66
• /
• 2010

Korea have experienced a very rapid increase in police-reported collisions between bicycle and motor vehicles over the past decade. Even though cycling accidents are increasing, efforts to make urban areas more accomodating to cyclists are seldom formed. Clearance intervals(including both the yellow change and all-red clearance intervals) at signalized intersections that are of inadequate lengths for bicycles may cause accidents. Data on bicycling speed, acceleration and deceleration were tested and analyzed on the flat. Using the results of the analysis and based on the AASHTO's equation of the bicycle clearance interval, a methodology is got for calculation safe clearance intervals for bicycle riders. The clearance interval call for bicycles will be larger or same than for vehicles because of the speed, acceleration and deceleration difference. Adequate bicycle speed, acceleration and deceleration for korean bicycle users is presented in this paper. It is hoped that traffic engineers to provide safe intersection clearance time for bicycles use the results of this paper.