• Journal of Positioning, Navigation, and Timing
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• 제12권2호
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• pp.141-148
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• 2023

In this paper, impacts of tropospheric delay gradient correction on PPP positioning performance were analyzed. A correction for tropospheric delay error due to the gradient was created and applied using external data, and reference station data were collected on a sunny day and a rainy day to analyze the GPS only dual-frequency PPP positioning results. As a result, on the sunny day, the convergence time was about 35 minutes and the final 3D position error was 10 cm, regardless of whether the correction for the tropospheric delay error by the gradient was applied. On the other hand, on the rainy day, the 3D position error converges only when the correction was applied, and the convergence time was about 34 minutes. Furthermore, the final 3D position error was improved from 30 cm to 10 cm. In addition, the analysis of the PPP by reference station location on the rainy day showed that the PPP positioning performance was improved when the correction was applied to a user located in an area where the weather changes.

• 대한기계학회논문집A
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• 제26권6호
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• pp.1035-1046
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• 2002

Time Delay Control(TDC) is a robust nonlinear control scheme using Time Delay Estimation(TDE) and also has a simple structure. To apply TDC to a real system, we must design Time Delay Controller to guarantee stability. The earlier research stated sufficient stability condition of TDC for general plants. In that research, it was assumed that time delay is infinitely small. But, it is impossible to implement infinitely small time delay in a real system. So, in this research we propose a new sufficient stability condition of TDC for general plants with finite time delay. And the simulation results indicate that the previous sufficient stability condition does not work even for small time delay, while our proposed condition works well.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.119.3-119
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• 2001

When building a network-based real-time control system, a network-induced delay time should be surly considered for real time schedulability to be guaranteed. The network delay time on end-to-end communication has been analyzed theoretically and modeled mathematically from many previous works. There also exist any other delay element not considered before. In this paper, the remote feedback control system using the CAN protocol is proposed to control three axes´ manipulator arm and the application layer of CAN is modeled to analyze the delay elements defined by three types of time delay: Software delay time, Controller delay time, and Access delay time, in details. The analyzed results are used as an important component to determine PID gains of the proposed system. The effect of the delay time on the control performance is evaluated by com paring the response characteristics of the control system through simulation.

• 제어로봇시스템학회논문지
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• 제14권6호
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• pp.564-572
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• 2008

The performance of the direct adaptive time-delay command shaping filter depends on the select time-delay. In the previously introduced direct adaptive command shaping filter, however, the time-delay value is fixed and only the magnitudes of the impulses are learned. In this paper, the authors introduce a new scheme to adapt the time-delay which is to be used in conjunction with the direct adaptive command shaping for the improved vibration suppression in flexible motion system. In order to formulate the time-delay adaptation scheme, the authors have analyzed the effect of the time-delay value on the performance of the direct adaptive command shaping filter. By modifying the direct adaptation formula based on the analysis result the authors have established a set of equations to adapt the time-delay toward the optimal value. Simulation results show the effectiveness of the proposed time-delay adaptation approach for the improved vibration suppression.

• 제어로봇시스템학회논문지
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• 제16권3호
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• pp.286-292
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• 2010

In this paper, we investigate the relationship between the performance of telerobotic systems and the two independent time-delay on different modality, which are haptic and video. Especially, we try to find some performance improvement when the amount of delay of haptic and video is synchronized. Experiments were conducted with 10 subjects by scanning the amount of video and haptic delay independently. It is rather interesting to note that the teleoperation performance was not that sensitive to video delay, and the synchronized video and haptic delay doesn't show better performance than the case when haptic delay is lower than video delay.

• 한국통신학회논문지
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• 제29권10B호
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• pp.831-840
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• 2004

무선 링크 상에서의 QoS 제공을 위해서는 트래픽 소스와 무선 채널 그리고 오류 제어 방식간의 상호 작용에 대해 정확히 이해하여야 하고 또한 이를 계량화 하는 것이 필요하다. 이 논문에서는 이와 같은 상호작용을 네트워크 계층 관점에서 분석하고 이를 딜레이 성능의 분석에 적용하였다. 시간에 따라 전송 용량이 변하는 무선 링크 상에서 on/off 트래픽 소스가 데이타를 전송하는 시나리오를 가정하였다. 패킷 딜레이 분포는 uniformization과 Laplace transform이라는 두 가지 방식으로 유도 되었고 두 방식간의 장단점이 비교되었다. 수식으로 표현된 딜레이 분포는 다시 딜레이에 대한 서비스 요건이 주어진 경우, 무선 유효 대역폭 (wireless effective bandwidth) 이라는 양을 계산하기 위해 사용되었다. 수치적인 분석과 시뮬레이션을 통해서 이 논문에서 제안한 분석의 정확도를 검증하였고 오류 제어와 대역폭 할당이 패킷 딜레이 성능에 미치는 영향을 분석하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.469-470
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• 2010

• 한국건설관리학회논문집
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• 제20권6호
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• pp.98-106
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• 2019

최근 국내 건설공사에서 공기관련 클레임과 분쟁의 발생건수가 급격한 증가세를 보이고 있다. 이러한 현상은 전통적으로 발주자 우위의 국내 건설 계약관행이 계약당사자간 상호적이며 균형적인 관계로 변화되고 있음을 시사하는 것이다. 공기지연 분석은 건설공사 착공시 승인된 공정표의 종류, 공사진행 과정에서 공정표 실적관리를 어떻게 했는지에 따라 적용 방법을 선정하게 된다. 그리고 공기지연 분석에서 가장 중요한 전제조건은 공사초기에 합의된 완전한 CPM공정표가 준비되어 있고, 그러한 공정표의 실적관리가 제대로 기록되어 있는 것이다. 본 연구는 국내 민간 발주자의 대형신축건물을 공사하는 과정에서 시공자가 손해를 보았다며 발주자를 상대로 손해배상을 청구한 사건의 공기지연 분석 방법론을 적용에 관한 것이다. 본 연구에서는 불완전한 CPM공정표에 계획공정 분석법 적용이 적절한 지 판단하고, 이에 대한 대안으로 새로운 기준의 계획공정 대비 완료공정법을 제안한다. 그리고 사례 프로젝트에 계획공정 대비 완료공정법을 적용한 다음, 계획공정 분석법 결과와 비교분석한다. 본 연구의 목적은 국내 건설공사의 공정관리 현실에 적합한 공기지연 분석방법을 제시함으로써, 향후 국내 건설공사의 공기지연관련 분쟁과 소송에서 의미 있는 참고자료로 활용될 수 있도록 하는 것이다.

• 한국건축시공학회지
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• 제12권6호
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• pp.636-647
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• 2012

Construction projects have become so large, complicated and incredibly high-tech that process management is currently considered one of the most important issues. Unlike typical manufacturing industries, most major construction activities are performed in the open air and thus are exposed to various environmental factors. Many studies have been conducted with the goal of establishing efficient techniques and tools for overcoming these limitations. Productivity analysis and prediction, one of the related research subjects, must be considered when evaluating approaches to reducing construction duration and costs. The aim of this research is to present a quantified impact analysis of construction delay factors on construction productivity of a steel staircase system, which has been widely applied to high rise building construction. It is also expected to improve the process by managing the factors, ultimately achieving an improvement in construction productivity. To achieve the research objectives, this paper analyzed different delay factors affecting construction duration by means of multiple regression analysis focusing on steel staircase systems, which have critical effects on the preceding and subsequent processes in structure construction. Statistical analysis on the multiple linear regression model indicated that the environment, labor and material delay factors were statistically significant, with 0.293, 0.491, and 0.203 as the respective quantified impacts on productivity.

• 한국건설관리학회논문집
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• 제5권6호
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• pp.129-137
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• 2004

본 연구는 국내 건설공사의 공기지연 클레임과 관련된 공기지연 분석실태와 해외 건설에서 활용되고 있는 공기지연 분석실태에 대한 문헌고찰을 실시하였다. 국내외 공기지연 클레임 분석방법을 비교하여 볼 경우, 해외에서 일반적으로 쓰여지고 있는 공기지연 분석방법이 국내에서는 적극적으로 활용되고 있지 못함을 파악할 수 있다. 본 연구에서는 국내외 공기지연 분석방법 관련 문헌 및 연구자료를 조사하여 공기지 연 분석방법의 주요개념 및 특성을 정리하였다. 주요한 분석방법으로는 계획대비실적 비교방법, What-if방법, But-for방법, CPA방법, 그리고 DAMUDS방법 등이 있었다. 본 연구에서는 조사된 주요한 공기지연 분석방법들의 적용방법의 특성 및 절차를 명확히 제시하기 위하여, 발생한 공기지연에 대한분석방법의 사례연구를 실시하였다.