• Journal of Communications and Networks
• /
• 제12권4호
• /
• pp.317-329
• /
• 2010

In recent years, many sparse estimation methods, also known as compressed sensing, have been developed. However, most of these methods presume that the measurement matrix is completely known. We develop a new blind maximum likelihood method-the expectation-sparse-maximization (ESpaM) algorithm-for models where the measurement matrix is the product of one unknown and one known matrix. This method is a variant of the expectation-maximization algorithm to deal with the resulting problem that the maximization step is no longer unique. The ESpaM algorithm is justified theoretically. We present as well numerical results for two concrete examples of blind channel identification in digital communications, a doubly-selective channel model and linear time invariant sparse channel model.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.1871-1876
• /
• 2005

In this paper, We present a new nonlinear adaptive control law using a disturbance accommodating control (DAC) observer for a Japanese automatic landing flight experiment vehicle called ALFLEX. A future spaceplane must have ability to deal with greater fluctuations in the stability and control derivatives of flight dynamics, because its flight region is much wider than that of conventional aircraft. In our previous studies, digital adaptive flight control systems have been developed based on a linear-parameter-varying (LPV) model depending on dynamic pressure, and obtained good simulation results. However, under previous control laws, it is difficult to accommodate uncertainties represented by disturbance and nonlinearity, and to design a stable flight control system. Therefore, in this study, we attempted to design a nonlinear adaptive control law using the DAC Observer and inverse dynamic methods. A good tracking property of the obtained system was confirmed in numerical simulation.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 추계학술대회 논문집
• /
• pp.358-361
• /
• 2000

To reduce the leadtime for a new model according to the strict market requirements, automobile manufacturer begins to utilize 3-dimensional CAD based techniques such as DMU(Digital Mock-Up). RP(Rapid Prototyping), VE(Virtual Engineering). But, not so many satisfactory utilities have been introduced to deal with the emotional properties such as embossment on the surface of interior parts and touch from material characteristics in virtual environment. It is required to manufacture prototype parts to verify actual feeling of the passengers in real automobile. This paper suggests a methodology to enhance emotional property via embedding embossment on the surface of prototype car interior trim without deterioration of dimensional accuracy using RIM(Reaction Injection Molding) and vacuum forming method.

• 한국통신학회논문지
• /
• 제21권8호
• /
• pp.1958-1969
• /
• 1996

This paper proposed a new approach to adaptive call admission control based on a neural network for multiple service classes with different quality of service (QoS) in the ATM-based Broadband Integrated Services Digital Networks. the proposed method extend Hiramatsu's neural network based "leaky pattern table" method for the single QoS[1, 2, 3] to deal with multiple services with different QoS by constructing multiple pattern tables based on each service's acceptance or rejection at the call set-up requests, and by simultaneously controlling each service's QoS according to the target QoS of the service and the trunk capacity. Computer simulation results on two service classes with different traffic characteristics and different cell loss rates as QoS, highlight good performance and effectiveness of the proposed call admission controller for multiple service classes.e classes.

• Journal of information and communication convergence engineering
• /
• 제11권3호
• /
• pp.167-172
• /
• 2013

Recently, mobile communication systems are suffering from exponentially increasing data traffic. As a promising solution to the increase in data traffic, a coordinated multi-point transmission and reception (CoMP) scheme has been proposed. Although a great deal of research has been done on this new technology, the performance of mobile communication systems with CoMP has not been evaluated properly in a typical indoor environment. To address this, we have developed a system-level simulator and evaluated the performance of mobile communication systems with CoMP. Unlike previous works, we have used an actual antenna pattern in our simulator and link-level results are properly taken into account through link-level abstraction. By using a system-level simulator, we have evaluated the performance of mobile communication systems with CoMP in an indoor environment and found that unlike an outdoor cellular environment, CoMP may not improve the performance of overall mobile communication systems in an indoor environment.

• Acta Via Serica
• /
• 제7권1호
• /
• pp.83-104
• /
• 2022

This article attempts to explain current social perceptions in Mexico about the Silk Road. Based on a critical geopolitics approach, the author analyzes how the idea of the Silk Road is socially constructed in Mexican popular geopolitics, focusing on studying digital mass media between 2013 and 2020. The main research questions are: how is the Silk Road notion constructed in Mexican popular geopolitics and what are the geopolitical implications for Mexico? The article discovers that in Mexico, the idea of the "Silk Road" is profoundly close to the idea of the Belt and Road Initiative (BRI) given China's geostrategic discourse that constructs the BRI as a "New Silk Road". The article also argues that Mexico's social-political agency to deal with China may be hindered by divergent social perceptions in favor and against the "Silk Road".

• 전자통신동향분석
• /
• 제39권2호
• /
• pp.66-76
• /
• 2024

Artificial-intelligence (AI) semiconductors are crucial for securing national core competitiveness, including dominating the AI and data ecosystem and succeeding in the Digital New Deal. When examining the macroenvironment, the global division of labor in the semiconductor industry has weakened owing to the technological competition between the United States and China. Major countries are aiming to build the entire semiconductor ecosystem around their territories. As a result, these countries are formulating policy goals tailored to their realities and actively pursuing key policies such as research and development, securing manufacturing bases, workforce development, and financial support. These policies also focus on intercountry cooperation and bold government policy support, which is deemed essential. To secure core competitiveness in AI semiconductors, South Korea needs to examine the policy directions of major countries and actively formulate and implement policies for this semiconductor industry.

• 디자인학연구
• /
• 제17권2호
• /
• pp.351-362
• /
• 2004

일반적으로 사람들은 주변에서 일어나는 어떤 현상을 눈으로 보고 그것에 대해 각자 어떤 방식으로든 반응한다. 그리고 보여 지는 것이 무엇인가에 따라 아주 다양한 순차적 행동이 이어진다. 육체적, 지적인 능력과 경험적 교육에 대한 큰 장애가 없는 사람일수록 스스로의 행동에 대해 외부의 물리적 힘에 의한 행위의 교정보다는 보고, 듣고, 느낌에 의해 자발적으로 행동을 규제하는 쪽을 선호한다. 다른 한편으로 우리들이 일상생활에서 편리하게 사용하고 있는 도구들일지라도 사용자 스스로 행동을 규제해야 하는 기능들이 상황에 따라 빈번히 요구된다. 그렇지 않으면 사용자 측면에서 별로 의식하지 않고 사용하고 있으나 무언가 필요성을 느끼면서도 뚜렷한 대안을 찾지 못한 채 현재의 기능에 적응하고 있는 경우일 것이다. 구체적인 예를 들자면 가정에서 요리나 설거지, 혹은 세면이나 목욕 시에 수도꼭지를 틀지만 계몽적인 측면에서 익히 접해온 절약이란 말과 안이한 행동사이를 오가면서 스스로를 제어하지 못한다. 이런 점에서 흐르는 물의 양을 작업 공간내에서 시각적으로 바로 확인 할 수 있는 부가적인 기능을 갖춘 도구가 있다면, 모두에서 언급하였듯이 사용자가 자발적으로 자신의 행위를 조절 할 수 있으며, 또한 정확한 물의 양을 측정함으로써. 여러 가지 후속적인 행동에 아주 요긴하게 이용될 수 있을 것이다. 이와 같이 작업공간에서의 유량측정이 가능한 수전금구는 시대적 조류와 더불어 디지털의 기술을 적용한 유량측정센서를 수도꼭지에 부착하고 부피를 최소화함으로써 구조나 형태를 최적화하는 조형 작업을 통해 시대 조류에 부응하는 제품으로 업그레이드 될 수 있다. 따라서 본 연구는 일상생활에서 꼭 필요로 하는 수전금구에 대해 사회적, 환경적 요구에 부합하며, 이종 기술이 적용된 새로운 개념의 제품을 기능적, 구조적, 조형적 측면에서 연구함으로써 향후 이와 관련된 유사한 제품개발의 참고 자료를 마련 하고자 하였다.

• 대한인간공학회지
• /
• 제19권2호
• /
• pp.63-74
• /
• 2000

This paper is to clarify a thermal physiological index that can account for the effects of local thermal environment. For this purpose two young female subjects exposing themselves to the above while sitting on a chair, sitting on the floor and lying on the floor were measured. These three representative postures accompanied the different contact surface areas, thereby the heat conduction rate between the floor and subject was quantitatively measured for each posture. It made the present study deal with the effect of heat conduction concerning the modified mean skin temperature and finally propose new weighting coefficients for the mean skin temperature calculation based on the Hardy & DuBois' formulas. In order to verify the proposed model, the experiment was carried out using a floor heating system. The comparison between the experimental result and prediction revealed that the proposed model should be about 10% more accurate than the conventional one in the case of lying on the floor which the heat conduction effect becomes important.

• 디지털융복합연구
• /
• 제7권1호
• /
• pp.157-164
• /
• 2009

This research focuses on entrepreneurial orientation(EO) of technology spin-offs as they are expected to reduce the gap between their technology and the market. Entrepreneurial orientation is an organizational activity or process that redistributes or combines resources in an innovative way and takes risk to create new values. It helps improve the level of organizational innovation to deal with uncertainty. An empirical study was performed to analyze the EO of spin-offs established by members of university faculties and research institutes in Korea. Antecedent variables to EO are hypothesized to include public policy for university faculty members and researchers at research institutes, the relationship with incubating organizations, and the level of social networking with other firms. The EO and technological performance relationships are also hypothesized. Data from a total of 121 spin-off organizations were collected and a series of multiple regressions were performed. The performance variable included both technological performance, such as the number of newly marketed products and new technology and subjective performance, such as the level of satisfaction with sales amount and profitability. Several important conclusions were drawn from this study. First, while government policy is not related to EO, the policy of a university or a research institute has a significant effect on the level of innovativeness. Second, a high percentage of human resources applied at the incubating organization results in a negative effect on risk taking. The level of cooperation with the incubating organization too is not related to Entrepreneurial Orientation. Third, the intensity of cooperative networking with other firms has a significant effect on risk-taking. Network relationship with government related organizations is not related to Entrepreneurial Orientation. This study analyzes the importance and role of policy of the university and research institute and networking with other firms to improve EO. It also suggests that a high composition of human resources at the incubating organization has a negative relationship with EO.