• Journal of Electrical Engineering and Technology
• /
• 제7권6호
• /
• pp.1023-1033
• /
• 2012

An underwater planar covering problem is studied where the coverage region consists of polygonal cells, and line sweep motion is used for coverage. In many subsea applications, sidescan sonar has become a common tool, and the sidescan sonar data is meaningful only when the sonar is moving in a straight line. This work studies the optimal line sweep coverage where the sweep paths of the cells consist of straight lines and no turn is allowed inside the cell. An optimal line sweep coverage solution is presented when the line sweep path is parallel to an edge of the cell boundary. The total time to complete the coverage task is minimized. A unique contribution of this work is that the optimal sequence of cell visits is computed in addition to the optimal line sweep paths and the optimal cell decomposition.

• 한국통신학회논문지
• /
• 제34권9B호
• /
• pp.876-882
• /
• 2009

본 논문에서는 relay 기반 OFDMA 시스템에서 cell throughput 향상을 위한 Base Station (BS)과 Relay Station (RS)의 sub-cell 커버리지 조절 기법을 제안하였다. Relay 시스템에서는 BS-RS 링크에서 무선 자원을 추가로 소비하기 때문에, 이를 고려하지 않고 sub-cell 커버리지를 설정하면, 자원 사용량이 증가하여 throughput이 저하될 수 있기 때문에 자원 소모를 고려한 sub-cell 커버리지 설정이 필요하다. 이 때, 설정된 sub-cell 커버리지를 고정하여 운용할 수도 있지만, 트래픽 상황의 변화에 따라서 커버리지를 효과적으로 조절해주면, throughput 성능을 더욱 향상시킬 수 있다. 본 연구에서는 MS가 이동할 때에, 멀티홉 전송에 따른 relay link에서의 자원의 소모와 자원 재사용 정도를 함께 고려하여 sub-cell 커버리지를 조절하는 기법을 제안하고 분석하였다. 제안하는 커버리지 조절 기법에서는 BS와 RS로부터의 수신 SINR 값 비율로 threshold 값을 정하고 이를 이용하여 sub-cell 경계를 설정하였다. 그리고 트래픽의 변화에 따라 멀티홉에서의 자원의 소모와 자원 재사용을 고려한 effective transmitted bits per subchannel을 이용하여 sub-cell 경계를 적응적으로 조절하였다. 성능 분석을 위해 이 경우 cell throughput을 도출하였다. 제안하는 커버리지 조절 기법을 적용할 때, 고정하여 운용하는 경우에 비해, cell throughput이 향상되는 것을 확인하고, 정량적으로 분석하였다.

• 한국통신학회논문지
• /
• 제34권5A호
• /
• pp.414-420
• /
• 2009

본 논문에서는 OFDMA 기반 relay 시스템에서 throughput 성능개선을 위한, Base Station (BS)과 Relay Station (RS)의 sub-cell 커버리지 설정기법을 제안한다. Relay 시스템에서는 BS-RS 링크에서 무선 자원을 추가로 소비하므로, RS간 자원의 재사용을 고려하면 자원의 효과적 사용이 가능하다. 그러나, 이때 신호의 간섭이 증가하므로 단말기의 수신 Signal to Interference and Noise Ratio (SINR)에 영향을 미치게 된다. 그리므로 본 연구에서는 자원 재사용 정도에 따른 사용가능 자원의 증가를 수신 SINR과 함께 sub-cell 커버리지 결정의 요인으로 함께 고려한다. 모의실험을 통한 결과분석을 통해 throughput 성능을 개선할 수 있는 sub-cell 커버리지를, 다양한 자원재사용 패턴에 따라 도출하였다.

• 로봇학회논문지
• /
• 제2권4호
• /
• pp.304-309
• /
• 2007

This paper describes an efficient path generation method for area coverage. Its applications include robots for de-mining, cleaning, painting, and so on. Our method is basically based on a divide and conquer strategy. We developed a novel cell decomposition algorithm that divides a given area into several cells. Each cell is covered by a robot motion that requires minimum time to cover the cell. Using this method, completeness and time efficiency of coverage are easily achieved. For the completeness of coverage in dynamic environments, we also propose a path following method that makes the robot cover missed areas as a result of the presence of unknown obstacles. The effectiveness of the method is verified using computer simulations.

• 한국정보통신학회논문지
• /
• 제17권3호
• /
• pp.556-560
• /
• 2013

고성능 스마트폰이 본격 보급되면서 폭발적으로 증가하고 있는 데이터 트래픽을 효과적으로 수용하기 위한 해법들에 대한 관심이 높아지고 있다. 이동통신용으로 활용할 수 있는 주파수에 제한이 있기 때문에, 최근에는 동일주파수를 사용하면서 추가적으로 용량을 확보할 수 있는 펨토셀에 대한 연구 및 개발이 활발히 진행되고 있다. 본 논문에서는 기존 매크로 신호가 존재하는 환경에서 데이터 오프로딩을 위하여 펨토셀을 구축할 경우를 가정하여, 펨토셀의 커버리지를 수학적으로 분석하였다. 분석 결과, 펨토셀의 출력이 증가할수록 그리고 파일럿 채널에 할당하는 전력의 비율이 높아질수록 펨토셀의 커버리지가 증가하지만, 매크로 기지국 신호가 강한 트래픽 밀집 지역에서는 펨토셀의 커버리지가 매우 제한적임을 알 수 있었다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
• /
• pp.125-128
• /
• 2000

In this paper, the handoff margins are analyzed using the propagation attenuation which is modeled as a product of the fourth power of the distant and a log-normal random variable whose standard deviation is 8 ㏈. The effect of handoff techniques on cell coverage for CDMA system are shown that soft handoff increases cell coverage relative to hard handoff. When the cell radius extends 5-10 % and the outage probability is 10 %, the relative cell coverage area is extended 3.22 ㏈-3.99 ㏈ and 2.55 ㏈-2.85 ㏈ with power control and without power control, respectively.

• 한국ITS학회:학술대회논문집
• /
• 한국ITS학회 2010년도 춘계학술대회
• /
• pp.10-13
• /
• 2010

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.129.3-129
• /
• 2001

In this paper, a novel navigation method is presented for the cleaning robot in the unknown workspace. In order to do this, we propose a new map representation method and a complete coverage navigation method. First, we discuss a triangular cell map representation which makes the cleaning robot navigate with shorter path and increased flexibility than a rectangular cell map representation. Then we proposed a complete coverage navigation and map construction method which the cleaning robot can navigate the complete workspace although it has perfectly no information about environment. Finally, we evaluate the performance of our proposed triangular cell map comparing to that of the rectangular cell map via the existing ...

• 한국임상약학회지
• /
• 제21권3호
• /
• pp.193-207
• /
• 2011

Purpose: The purpose of this study is to assess appropriateness of current standard for insurance coverage by Health Insurance Review & Assessment Service (HIRA) on chemotherapy used in the treatment of advanced non-small cell lung cancer (NSCLC), by reviewing a variety of clinical evidences, and thereby, if needed, to propose an updated evidence-based recommendations. Methods: We collected data from HIRA regarding on the insurance standard which includes the scope and conditions for coverage on systemic chemotherapy of NSCLC. We performed a search for clinical databases and examined the most current clinical evidence from clinical literature including various clinical practice guidelines. Based on the collected data the appropriateness of HIRA standard for insurance coverage of chemotherapy of NSCLC was assessed. Results: Collected data demonstrated that HIRA standard did not reflect the most current clinical practice and evidence. Some were inappropriately listed in HIRA formulary and accepted as a chemotherapy being covered by insurance, despite the lack of evidences of clinical efficacy or superiority over other chemotherapeutic agents or regimens. In addition, there seems to be a need for a modification on the standard for insurance coverage of certain newer chemotherapeutic agents based on the current accumulated data showing their clinical efficacy and benefits in the selected group of NSCLC patients. Therefore, we concluded that current HIRA standard for insurance coverage on chemotherapy of NSCLC needs to be revised and we proposed an updated recommendation based on these latest clinical evidences. Conclusion: The standard for insurance coverage of chemotherapy should be continually examined its appropriateness based on the most recent clinical evidences in a timely manner so as to provide the most effective and safe therapy to cancer patients.

• 한국통신학회논문지
• /
• 제25권10B호
• /
• pp.1641-1647
• /
• 2000

This paper presents an analysis of coverage and capacity for the multi-layer CDMA cellular system. The multi-layer CDMA system that shares a common frequency band consists of macrocells for outdoor users and picocells for indoor users. Though macrocells and picocells interfere with each other the capacity of the whole system can be increased, We have analyzed the effect of muual interference upon cell coverage soft handover areas and capacities. The parameters involved in the engineering of the system are discussed. The study results sow that we can control the service coverage of indoor picocells with the system parameters set properly. It is also show that the capacity of the whole system that the capacity of the whole system can be enhanced smoothly by deploying the indoor picocells within existing macrocells.