• Journal of Welding and Joining
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• v.17 no.1
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• pp.77-81
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• 1999

Through-hole PCB(Printed Circuit Board) was soldered by flow soldering process using cleaning or noncleaning fluxes. Preheating temperature and conveyor speed were changed in the range of 323∼413K and 0.3∼2m/min respectively. The soldered joints were tensile tested in order to evaluated bonding strength. As experimental results, relatively high tensile fracture load, 120∼140N, were obtained in case of preheating temperature of 383K, and conveyor speed was 0.6∼1.0 m/min. Fractured surfaces of higher tensile strength show some dimple area, while those of lower tensile fracture load show brittle fracture.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10b
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• pp.340-344
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• 2007

유비쿼터스 지능공간에서 사람의 행동과 위치를 모니터링하는 것은 서비스 제공을 위해 기본적이며 필수적인 단계이다. 본 논문에서는 스마트 펜던트(SmartPendant)의 카메라 영상과 GPS위치 정보를 이용한 새로운 웨어러블 컴퓨터를 제안한다. 우선, 행동 인식를 위해 영상간에 특정 픽셀 값 차와 옵티컬 플로우를 사용하였으며, 인식이 가능한 행동으로는 걷기, 멈춤, 방향전환이다. 또한, GPS를 이용한 사용자의 위치 정보는 위도와 경도에 대한 스트링값을 패킷값으로 변환하여 지능형 상황인지 서버에 전달된다.

• Proceedings of the Korean Society for Information Management Conference
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• 2013.08a
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• pp.83-87
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• 2013

본 연구는 국내 D-Space 기반의 11개 리포지터리에 구축된 콘텐츠 현황을 두가지 관점에서 조사하고 분석하였다. 각 리포지터리에 구축된 콘텐츠의 더블린코어(DC) Type 유형을 추출하여 그 현황을 조사하였으며, 2,500여 콘텐츠들을 무작위 샘플링하여 원문 구축현황 및 유형을 살펴보았다. 그 결과 각 리포지터리에는 표준화되지 않은 다양한 Type 유형을 자체적으로 사용하고 있었으며, 원문을 제공하는 방식 또한 다양하게 나타났다. 이에 본 연구에서는 각 기관별로 사용하는 39가지의 Type 유형을 9개 유형으로 병합한 기준을 제시하고, 향후 리포지터리 콘텐츠를 수집하는 측면에서 품질관리 정책 수립을 위한 제언과 시스템 구축을 위한 워크플로우를 제시하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.12-13
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• 2019

Maritime Big Data Linkage System is a system for linking maritime related internal and external data used in Korean e-Navigation. It is possible to create data acquisition, conversion, storage, analysis, management application service by technology of maritime data generated from inside and outside, and it can be configured and processed in units of components. It is also possible to monitor the flow of data defined by the workflow.. Through this study, it is expected that e-navigation service will be able to link data more efficiently and easily.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.93-96
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• 2023

머신 러닝의 수요가 증가함에 따라, 머신 러닝 워크플로우의 배포 수요도 증가했다. Kubeflow를 통해 머신 러닝 배포를 편리하게 할 수 있으며, Kubeflow Pipelines에서는 하나의 작업을 여러 컨테이너로 분산시켜서 연산하는 것이 가능하다. 하지만 컨테이너 수를 많이 늘릴수록 반드시 성능이 향상되는 것은 아니다. 따라서, 본 연구에서는 성능 향상의 한계를 제공하는 원인을 분석하기 위해서, Kubeflow에서 CPU 집약적인 작업을 여러 컨테이너로 분산시켜서 연산을 수행하였다. 컨테이너 수에 따른 연산 완료 시간을 비교 및 분석한 결과, 컨테이너 수가 증가할수록 연산 속도 향상이 빨라지나, 어느 시점을 지나면 속도가 다시 완만하게 줄어드는 현상을 확인하였다. 이는 리소스 제한으로 인해 모든 컨테이너가 동시에 스케줄링 되지 못한 것이 가장 큰 원인으로 분석하였다.

• Journal of the Korea Institute of Building Construction
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• v.6 no.3 s.21
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• pp.75-82
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• 2006

This study investigates the influence of various blending factors on cement paste fluidity and find out the most effective evaluation method of cement paste flow, comparing flow test apparatuses such as ring flow(R-F), flow cone(F-C) and mini slump(M-S). A viscometer also measures the rheology coefficients to secure faithful numerical data. Firstly, series I examines cement paste, affected by several cement products and mineral admixture types in the range of W/B 40%, ordinary fluidity, and W/B 30%, high fluidity. In this series, the three types of cement product depended on companies, are randomly used and the mineral admixture, such as fly ash, blast furnace slag and silica fume, are incorporated in the cement paste, in response to the ratio of 10, 20, to 30%, respectively. In addition, series II studies various chemical admixture types, affecting the cement paste. This series is carried out with manufacturing companies and component types in the range of W/C 30%, high fluidity. For the manufacturing companies, randomly four products are used and for the component types, polycaboxylate, melamine, naphthalene and lignosulfonate type are chosen. Test results showed that in the fluidity test of cement paste considering various types of blending factors, R-F exhibited similar tendency with F-C and M-S. In the analysis of consistency curves measured by viscometer, the fluidity evaluation method using flow test apparatuses was significantly effective, except for the some of the low fluidity specimens. In conclusion of this study, R-F was the most convenient, faithful and effective fluidity evaluation method of cement paste.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1771-1779
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• 2016

In these days, the world is getting connected to the internet like a sophisticated net, such an environment gives a suitable environment for cyber attackers, so-called cyber-terrorists. As a result, a number of cyber attacks has significantly increased and researches to find cyber attack traffics in the field of network monitoring has also been proceeding. But cyber attack traffics have been appearing in new forms in every attack making it harder to monitor. This paper suggests a method of tracking down cyber attack traffic sources by defining relational information flow of traffic data from highest cascaded and grouped relational flow. The result of applying this cyber attack source tracking method to real cyber attack traffic, was found to be reliable with quality results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.63-68
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• 2019

Emerging applications such as Smart factory, in-car network, wide area power network require strict bounds on the end-to-end network delays. Flow-based scheduler in traditional Integrated Services (IntServ) architecture could be possible solution, yet its complexity prohibits practical implementation. Sub-optimal class-based scheduler cannot provide guaranteed delay since the burst increases rapidly as nodes are passed by. Therefore a leaky-bucket type regulator placed next to the scheduler is being considered widely. This paper proposes a simple server that achieves both fair scheduling and traffic regulation at the same time. The performance of the proposed server is investigated, and it is shown that a few msec delay bound can be achieved even in large scale networks.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.6
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• pp.255-260
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• 2017

The limitation of real-time video conferencing system is that the delay of network and buffering and the transmission of user information are not efficiently performed between systems, so real - time performance is not guaranteed completely. In order to overcome this problem, the study on the extension of the network infrastructure and the jitter delay is actively carried out, but the study on the buffering delay is insufficient. In this paper, we propose a frame-rate control buffer management (FRCB) scheme to solve the problem caused by buffering delay. The FRCB is used to prevent overflow and underflow of the buffer by adopting the two-stage buffer threshold of Fast-play THreshold (FTH) and Slow-play THreshold (STH). Therefore, it showed better performance than jitter buffer even under high CPU load, and showed that it is suitable for high quality real time video conferencing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9B
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• pp.823-833
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• 2003

To satisfy the requirements of the real-time Internet services, queue management and scheduling schemes should be enhanced to accommodate the delay and jitter characteristic of them. Although the existing queue management schemes can address the congestion problems of TCP flows, they have some problems in supporting real-time services. That is, they show performance degradation when burst traffics are continuously going into the system after the queue is occupied at a predefined threshold level. In addition, under the congestion state, they show large jitter, which is not a desirable phenomenon for real-time transmissions. To resolve these problems, we propose a SDRED (State Dependent Random Early Detection) and dynamic scheduling scheme that can improve delay and jitter performances by adjusting RED parameters such as ma $x_{th}$ and $w_{q}$ according to the queue status. The SDRED is designed to adapt to the current traffic situation by adjusting the max,$_{th}$ and $w_{q}$ to four different levels. From the simulation results, we show that the SDRED decreases packet delays in a queue and has more stable jitter characteristics than the existing RED, BLUE, ARED and DSRED schemes.mes.mes.