Hiroaki Morikawa

Learn More
User context recognition is one of the important technologies for realizing context aware services. Conventional multi sensor based approach has advantages in that it can generate variety of contexts with less computation resources by using many different sensors. However, such systems tend to be complex and cumbersome and, thus, do not fit in well with(More)
Ubiquitous structural monitoring (USM) of buildings using wireless sensor networks is one of the most promising emerging technologies for mitigation of seismic hazard. This technology has the potential to change fundamentally the traditional monitoring systems. This paper provides an introduction of wireless sensor network technology for USM, and identifies(More)
In this paper, we describe an approach for building context-aware applications in the ubiquitous computing environment, where a huge number of sensors are embedded in our living space. The raw data from sensors can be used as low level context information, and also be used to infer higher level context information. We present several ubiquitous computing(More)
This paper proposes a novel technique enabling flow-level multi-path forwarding on a hop-by-hop packet switched network such as IP networks. Generally on such networks, any packet from a node toward a destination is forwarded along the same path, even if some of the packets belong to a different flow with different characteristics. Depending on the packet(More)
This paper compares several routing and wavelength assignment algorithms for a hybrid optical network architecture combining optical circuit switching (OCS) and multi-wavelength optical packet switching (MW-OPS). In this network, due to the fact that wavelength resources in a fiber are shared between OCS and MW-OPS and in MW-OPS each multi-wavelength(More)
In this paper, we study the problem of efficiently mining frequent partite episodes that satisfy partwise constraints from an input event sequence. Through our constraints, we can extract episodes related to events and their precedent-subsequent relations, on which we focus, in a short time. This improves the efficiency of data mining using trial and error(More)
In this paper, we present a fast and practical algorithm for a map-matching problem searching a path on a given graph that minimizes Fréchet distance from a given trajectory, which is a natural measurement based on the sequential order of the trajectory. However, it sometimes costs seriously to compute the Fréchet distance while making(More)
Based on the Open Data Charter of G8 in 2013, the Japanese government published a dataset covering approximately 4.4 million corporations in December 2015, but the dataset is merely rated as 3-star in the 5-star rating system of Open Data. To improve usability, we defined a schema for corporation data, converted the dataset into 5-star using this schema,(More)
Development of wireless technology enabled mobile networking at any time, anyplace. In the not too remote future, many everyday objects such as portable devices and appliances will be equipped with small wireless network interfaces and tied to digital networks. Utilizing such nodes and vast number of networked sensors scattered in every place will provide(More)