• 한국ITS학회:학술대회논문집
• /
• 한국ITS학회 2008년도 제7회 추계학술대회 및 정기총회
• /
• pp.161-164
• /
• 2008

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권5호
• /
• pp.2067-2080
• /
• 2016

Cooperative spectrum sensing (CSS) for vacant licensed bands is one of the key techniques in cognitive radio networks. Currently, sequential probability ratio test scheme (SPRT) is considered as a powerful soft decision approach to improve the sensing result for CSS. However, SPRT assumes all secondary users (SU) are honest, and thus offering opportunities for malicious SUs to launch the spectrum sensing data falsification attack (SSDF attack). To combat such misbehaved behaviors, recent efforts have been made to trust mechanism. In this paper, we argue that powering SPRT with traditional trust mechanism is not enough. Dynamic SSDF attackers can maintain high trust in an alternant process of submitting honest or false sensing data, resulting in difficultly detecting them. Noting that the trust value of dymamic SSDF attackers behave highly volatile, a novel trusted SPRT scheme (VSPRT) based on volatility decay analysis is proposed in this paper to mitigate the harmful effect of dynamic SSDF attackers in the process of the soft-decision data fusion, and thus improving the accuracy of the final sensing result. Simulation results show that the VSPRT scheme outperforms the conventional SPRT schemes.

• ETRI Journal
• /
• 제37권5호
• /
• pp.1032-1043
• /
• 2015

ETRI's Co-Pilot project is aimed at the development of an automated vehicle that cooperates with a driver and interacts with other vehicles on the road while obeying traffic rules without collisions. This paper presents a core block within the Co-Pilot system; the block is named "Co-Pilot agent" and consists of several main modules, such as road map generation, decision-making, and trajectory generation. The road map generation builds road map data to provide enhanced and detailed map data. The decision-making, designed to serve situation assessment and behavior planning, evaluates a collision risk of traffic situations and determines maneuvers to follow a global path as well as to avoid collisions. The trajectory generation generates a trajectory to achieve the given maneuver by the decision-making module. The system is implemented in an open-source robot operating system to provide a reusable, hardware-independent software platform; it is then tested on a closed road with other vehicles in several scenarios similar to real road environments to verify that it works properly for cooperative driving with a driver and automated driving.

• Journal of Communications and Networks
• /
• 제16권2호
• /
• pp.172-182
• /
• 2014

In this paper, we investigate the fundamental performance limits of the cooperative sensing using energy detection by considering the unlimited number of sensing nodes. Although a lot of cognitive radio research so far proposed various uses of energy detection because of its simplicity, the performance limits of energy detection have not been studied when a large number of sensing nodes exist. First, we show that when the sensing nodes see the independent and identically distributed channel conditions, then as the number of sensing nodes N goes to infinity, the OR rule of hard decision achieves zero of false alarm Pf for any given target probability of detection $\bar{P_d}$ irrespective of the non-zero received primary user signal to noise ratio ${\gamma}$. Second, we show that under the same condition, when the AND rule of hard decision is used, there exists a lower bound of $P_f$. Interestingly, however, for given $\bar{P_d}$, $P_f$ goes to 1 as N goes to infinity. Third, we show that when the soft decision is used, there exists a way of achieving 100% utilization of secondary user, i.e., the sensing time overhead ratio goes to zero so does $P_f$.We verify our analyses by performing extensive simulations of the proposed unlimited cooperative sensing. Finally, we suggest a way of incorporating the unlimited cooperative sensing into a practical cellular system such as long term evolutionadvanced by exploiting the existing frame structure of absolute blank subframe to implement the in-band sensing.

• Journal of Communications and Networks
• /
• 제12권5호
• /
• pp.442-448
• /
• 2010

Cooperative relaying methods have attracted a lot of interest in the past few years. A conventional cooperative relaying scheme has a source, a destination, and a single relay. This cooperative scheme can support one symbol transmission per time slot, and is caned full rate transmission. However, existing fun rate cooperative relay approaches provide asymmetrical gain for different transmitted symbols. In this paper, we propose a cooperative relaying scheme that is assisted with dual relays and provides full transmission rate with the same macro-diversity to each symbol. We also address equalization for the dual relay transmission system in addition to addressing the issues concerning the improvement of system performance in terms of optimal power allocations.

• 한국건설관리학회논문집
• /
• 제4권2호
• /
• pp.91-98
• /
• 2003

국내 건축설계 프로젝트에서는 협력업체간의 커뮤니케이션이 원활치 못하여 건축 부위 설계 시 성능 및 비용을 만족하는 적절한 설계대안 생성이 어려울 뿐 아니라, 설계단계에서부터 시공단견1에 이르기까지 다양한 원인으로 발생되는 설계변경에 적절히 대응하지 못하고 있다. 따라서 분야별 설계도서의 불일치로 인한 시공 품질 저하 등의 문제가 발생되고 있다. 이에 따라 본 연구에서는 건축설계단계에서 합리적인 건축설계대안 생성을 위한 협력설계 의사결정 지원시스템 구축방법의 개념을 제시하였다.

• Fashion, Industry and Education
• /
• 제14권1호
• /
• pp.59-68
• /
• 2016

This paper identified the source of inspiration to cooperatively design a fashion collection from US undergraduate clothing design students and addressed how to implement team-based learning strategy to conceptual clothing design in class. Data was collected from the total of 51 students in a senior clothing design course at a large 4-year university in the US. The assigned project for this class was to develop a group collection under a same theme. Each student worked with his/her team member(s) to create an outfit and the entire class worked as a group to create a cohesive collection. The study showed that the sources of inspiration for the themes/concepts came from 11categories: historic era/old Hollywood glamour, shape/line/structure/architectural, fairy tales movies, nature/abstract, circus/mysterious, occasion/place, object, designer/artist, futuristic, culture, and various movies. To implement cooperative learning strategies in the clothing design class, a total of five class presentation/discussion sessions were held for theme/concept decision, fabric decision, design decision, test garment evaluation and design modification, and final products. Throughout the design process, team-based learning strategy promoted students' engagement and participation and inspired their critical thinking skills for making decisions within a team.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제4권3호
• /
• pp.289-304
• /
• 2010

This paper proposes a novel scheme for cooperative spectrum sensing on distributed cognitive radio networks. A fuzzy logic rule - based inference system is proposed to estimate the presence possibility of the licensed user's signal based on the observed energy at each cognitive radio terminal. The estimated results are aggregated to make the final sensing decision at the fusion center. Simulation results show that significant improvement of the spectrum sensing accuracy is achieved by our schemes.

• Architectural research
• /
• 제13권3호
• /
• pp.31-40
• /
• 2011

Profit-keeping behaviors naturally occur in the market to satisfy consumers, and the logic behind it lies in the economies of scale. On the flip side, some commodities transacted in the market are not available or can not be easily acquired unless the demand is high enough. Under this proposition, some consumers rise and find their own solution to meet the services at a reasonable cost or at an adequate level. The commonly adopted way is to establish a cooperative, and it stirs purchasing power by pooling resources and further bargains price and service quality. As a consumer cooperative, housing cooperatives notably found in rural towns enable the elderly to continue independent living. This study is to take a closer look at residential life of the rural elderly in housing cooperatives. Utilizing in-depth focus group interviews with 40 residents in four housing cooperatives, this qualitative research draws main factors affecting the decision to move in, residential assessment, and strengths and weakness of living in a housing cooperative. The primary factor influencing the moving decision is to continue to independent living in a familiar community, and the bottom line is planning ahead. Frailty and bereavement are found to be the leading occasions for them to move. The participants are satisfied with the independent living arrangement, and particularly, cited such features as safety and security, elderly-friendly design, common spaces, freedom, social activities and efficient living. Also, it is stated that some cooperative natures such as control over the property and giving a voice on management render positive impacts on the satisfaction with communal living. In spite of all the benefits and strengths, participants face with a public notion that an independent living arrangement like a housing cooperative has never done before in rural towns, so that most people recognize it as part of dependent living arrangements like nursing home.

• 한국통신학회논문지
• /
• 제35권5A호
• /
• pp.431-439
• /
• 2010

모든 노드에서 다중 안테나를 갖고 다중 릴레이가 존재하는 협동 통신망을 고려한다. 연판정 후 전송 기법을 적용하여 쌍 오류 확률을 구하고 이를 이용하여 심볼 오류 확률을 유도한다. 하지만 이러한 다중 릴레이 시스템 에서 간섭을 피하기 위해 일반적으로 전송률 측면에서 비효율적인 직교 채널의 사용이 요구된다. 이를 해결하기 위해 순시적인 신호 대 잡음의 비가 가장 큰 릴레이를 선택하도록 하는 선택 기법을 적용하고, 이 시스템에 대한 성능을 분석 한다. 또한, 릴레이의 개수가 증가할수록 모든 릴레이를 사용할 때보다 릴레이 선택 기법을 사용했을 때의 성능이 우수함을 보인다.