Proposed here is an internal representation and mapping method for multimedia information in which retrieval is based on the impression documents desired to make. A user interface design for a system using this method is also proposed. The proposed internal representation and mapping method represents each desired document impression as an axis in a semantic space. Documents are represented as points in the space. Queries are represented as subspaces. The proposed user interface design employs a method of visual presentation of the semantic space. Pictorial examples are given to illustrate the range of impressions represented by the axes. The relations between the axes are represented by dispersion diagrams for the documents stored in the document base. With this method, the user can intuitively decide the appropriate subspace for his needs and can specify it directly. For evaluation purposes, a prototype system has been developed. An image retrieval experiment shows that the proposed internal representation and mapping method and the user interface design provide effective tools for information retrieval.

The new notion of "multiuser interface", an interface for groups working together in a shared workspace, originated from the expansion of CSCW research and the spread of the groupware concept. This paper introduces a new multiuser interface design approach based on the translucent video overlay technique. This approach was realized in the multimedia desktop conference system Team WorkStation. Team WorkStation demonstrates that this translucent video overlay technique can achieve two different goals: (1) fused overlay for realizing the open shared workspace, and (2) selective overlay for effectively using limited screen space. This paper first describes the concept of open shared workspace and its implementation based on the fused overlay technique. The shared work window of Team-WorkStation is created by overlaying translucent individual workspace images. Each video layer is originally physically separated. However, because of the spatial relationships among marks on each layer, the set of overlaid layers provides users with sufficient semantics to fuse them into one image. The usefulness of this cognitive fusion was demonstrated through actual usage in design sessions. Second, the problem of screen space limitation is described. To solve this problem, the idea of ClearFace based on selective overlay is introduced. The ClearFace idea is to lay translucent live face video windows over a shared work window. Through the informal observations of experimental use in design sessions, little difficulty was experienced in switching the focus of attention between the face images and the drawing objects. The theory of selective looking accounts for this flexible perception mechanism. Although users can see drawn objects behind a face without difficulty, we found that users hesitate to draw figures or write text over face images. Because of this behavior, we devised the "movable" face window strategy.

This paper presents a new method for estimating lattice parameters of a system with additive white noise. A new lattice structure filter is used to reduce the effect of additive white noise, and then, an overfitting lattice filter is proposed to obtain the ARMA parameters by using the estimated lattice parameters with additive white noise.

In two-dimensional simulation of thin-base RHET, we combined three different simulation methods--the Schrödinger equation, the Monte Carlo simulation, and two-dimensional device simulation within a drift and diffusion model. We found that, in the thin-base RHET, the potential distribution differs from that expected from the thick-base RHET. In the thin-base RHET, the potential of the intrinsic base region does not equal that of the base electrode because the intrinsic base region is depleted and the negative emitter voltage (VEB0) raises the potential of both the intrinsic base and the nondoped region under the intrinsic base. There are also modified by the collector voltage. We also show emitter current-voltage characteristics, transfer ratio, and transit time calculated using this method and compare them with results for the one-dimensional case.

This paper deals with communication model in a software development project when there happens some trouble on it. First, we analyze a communication process in the real projects, and investigate what type of communication exists and which aspect is thought to be important by the members of the projects. Then we propose a communication model based on the analysis. We focus on the communication in case of troubles, and the process is modeled using charge, competence and knowledge of each member in the project. The features of the model lies in the ability to simulate communication route dynamically. The results of the simulation is compared with the real data, and also the use of the model for communication support system is discussed.

We present a new apparent bandgap narrowing model for semiconductor device simulation. The new model is derived from revised data of previous measurements on the apparent bandgap narrowing by using a corrected intrinsic carrier concentration. The revised values reveal sufficient agreement with our theoretical calculation. The new model is implemented in a triangular mesh device simulator TRIMEDES. Simulated BJT current-voltage and current-temperature characteristics using the proposed model reveal excellent agreement with measurements.

In the delayed regulation medel, X(t+1)=AX(t){1-X(t-1)}, new bifurcation regions which have been overlooked in the past studies were found out for -1.01A0 and 2.27563A2.2838. In the former fixed point lying at 0 is destabilized at A=-1, and new type bifurcation is induced for A-1, where oscillation with saw-tooth waveform is observed. In the latter the stability once lost for A2.271 is restored for A2.27563, and the stable region continues up to A=2.2838.

In this paper, a three part algorithm is employed to obtain stable convergence during stress dependent oxidation simulation using the finite element method is presented. By introducing (1) a reduced integration formulation, (2) an averaging procedure for the mid-side node velocities at the Si/SiO2 interface, and (3) a three-node element to discretize the oxidant diffusion equation, major improvements in achieving stable convergence are realized during stress dependent oxidation simulation. This technique is generally applicable for an oxidation simulator using the finite element method.

This paper is concerned with the stress simulation of a LOCOS structure during not only oxidation but also the subsequent cooling down based on viscoelastic stress modeling. A viscoelastic model is successfully applied to the oxide, nitride and silicon substrate for a LOCOS structure. Thermal stress is also taken into account during the cooling down process. The viscoelastic deformation problem of all the three materials for the LOCOS structure are solved by a two-dimensional finite element method. It is the first time to show that the stress values after cooling down to room temperature are much higher than those right after oxidation. It is also shown that varying the cooling down rates results in the different stress values after cooling down.

In recent years, ion implantation has become one of the key techniques in semiconductor fabrication. The annealing of the damage produced during implantation is, however, not fully understood. Ion implantation at high temperatures allows the time-resolved study of implantation-enhanced diffusion. During the process, point defects are generated by the ion implantation and consumed by recombination in the bulk as well as by diffusion to the surface and recombination there. With increasing temperatures, the recombination of point defects, which are acting as diffusion vehicles, results in reduced effective diffusion. Profiles processed above 900 show marked uphill diffusion at the surface caused by large gradients of the point defect concentrations. This uphill diffusion affirms the generally accepted pair diffusion theories. Since the point defects are in steady state even after process times which are short compared to the total process time, we are able to give a qualitative analysis of the dose dependence of the diffusion. By extensive numerical simulations, we could estimate the product of bulk recombination rate and equilibrium concentrations of self-interstitials and vacancies as well as the interface recombination velocity for the self-interstitials. The results obtained are in qualitative agreement with previous work of others. The results demonstrate, in fact, clearly the advantages of the method presented. But due to experimental problems concerning the temperature measurement, which have not been fully resolved up to now, the results have to be considered as crude estimates.

We have developed a new model to analyze the thermal failure mechanism due to electrical-over-stress (EOS) for two-dimensional planar pn-junction structures where the failure power is proportional to about 1/5 power of the failure time. We adopted a pseudo two-dimensional numerical simulation method where a pn-junction diode is divided into small elements and represented by a circuit network composed of many minute resistors and diodes. The failure mechanism studied by Wunsch and Bell, that is one of many studies for one-dimensional pn-diodes, is not valid for the case of two-dimensional pn-junction, such as a planar type junction. On the contrary, the failure mechanism was found to be much correlative with the junction structure, especially the impurity concentration in the substrate in the two-dimensional case. When the impurity concentration in the substrate is high enough (e.g. Nsub1017[cm-3]), the breakdown occurs at the whole junction. The heat transfer is one-dimensional and the failure power is proportional to about 1/2 power of the failure time, which is well known results reported by many researchers: e.g. Wunsch &Bell. On the other hand, when the impurity concentration in the substrate is low enough (e.g. Nsub1016[cm-3]), the breakdown occurs locally at the junction edge. The heat transfer is two-dimensional and the failure power is in proportion to about 1/5 power of the failure time.

Theoretical network analysis of a network constructed of "Interconnectable Star Couplers" whose all diagonal elements of transmission matrix are zero is investigated. Under certain connection rules, Interconnectable Star Coupler can be connected each other without oscillation and ghost formation. The rules are: (1) Network should not contain any loop. (2)Only single port pair should be connected between neighbor star couplers. (3)Network shold not contain any usual star coulpler. "Coupled Star Network", which is constructed under the connection rules, is able to form Cascade Star topology, Stratified Star topology and their mixed topology. It is shown that the Coupled Star Network is equivalent to a large Interconnectable Star Coupler so that bidirectional communication, which can add confidentiality to the broadcasting bus and doubles communication capacity, is available. A new configuration of Coupled Star Network using passive Interconnectable Star Couplers and optical amplifiers is proposed. This network has two separated bidirectional communication channel which can be applied for so-called Multimedia LAN. As a result of comparison between Cascade Star topology and Stratifide Star topology, it is shown that the latter topology is superior to former topology, from the view point of signal degeneration and maximum round trip delay time. Cascade Star topology, however, is superior to Stratified Star topology from the angle of total fiber length. Accordingly, optimized network topology is thought to be mixed topology of these.

Modeling and numerical simulation of crystal growth of Si film and heat transport in 3D structure were made for optimization of physical and geometrical parameters used during laser recrystallization. Based on simulations a new concept called micro-absorber was introduced for obtaining defect-free Si films.

The groupware for new idea generation system, GUNGEN, has been developed. GUNGEN consists of a distributed and cooperative KJ method support system and an intelligent productive work card support system. The system was implemented on a network consisting of a number of personal computers. The distributed and cooperative KJ method is carried out on computers. The ideas proposed by participants are classified into several groups on the basis of similarity and then a conclusion is derived. The intelligent productive work card support system can be used as a multimedia database to refer to the previous data of the distributed and cooperative KJ method.

An automatic optimization system for semiconductor devices has been built-up by fully interfacing an optimizer and a device-analysis code supplemented with sensitivity analysis. The device-analysis code is thought of as a part of a pipeline of simulators. The latters are regarded as subprocesses by the optimizer, which controls their I/O stream. The action of the pipeline is iterated until the optimum set of design parameters is determined. An important feature of the system is that all the derivatives required in the sensitivity analysis are calculated analytically, this providing a substantial improvement in both the numerical accuracy and computational efficiency, and making the scheme attractive from the application standpoint. A few examples of optimization of MOS devices are shown and the performance is reported, indicating that a system of this kind can usefully be exploited in a design environment.

Unlike a noise removal recursive or averaging filter, this letter presents a temporal filter which attenuates temporal high frequency components and improves visual effects. Although temporal aliasing occurs, the proposed filter proceeds temporal bandlimitation not affected by them. To reduce effects caused by aliasing components, a spatial filtering which is applied along the trajectory of motion is investigated. The proposed filter presents a de-aliasing and effective bandlimiting characteristics as well as reducing of noises.

Suppose that there are terminals on two concentric circles, Cin and Cout, with Cin inside of Cout. We are given a set of nets each of which consists of a terminal on Cin and a terminal on Cout. The routing area is the annular region between the two circles. In this paper, we present an O(nk-1) time algorithm for testing whether the given net set is k-layer routable without vias, where k2 and n is the number of nets.

A Monte Carlo calculation is performed to examine the transport coefficients of the electron gas under an inhomogeneous electric field. The expressions constructed from the M. C. results are then incorporated into the hydrodynamic formulation to calculate the internal characteristics of a silicon BJT device. The calculated results agree well with the Monte Carlo prediction.

We have developed an efficient general-purpose two-dimensional device simulation system which consists of a solver, and pre- and post-processors. This system can easily handle any complicated device having a non-rectangular shape. It can also be applied to compound semiconductor devices with heterojunctions, including optical devices such as laser diodes. In order to handle any device, a new program for construction of device geometry is developed as a preprocessor. It has an efficient graphic interface to reduce the time required to input data for simulations, which is a very time consuming task for complicated devices. A new efficient data structure representing device geometry is introduced in the program. During postprocessing, any physical quantity can be displayed on the multi-window screen. In addition, a general-purpose solver for basic semiconductor equations is implemented in the system. Using this system, any device can be successfully analyzed in a unified manner and the turn-around time for the simulation is significantly reduced.

The VSTEP concept and its practical application in the form of an LED-type pnpn-VSTEP demonstrating low power consumption through electro-photonic operational modes are both shown. Further, with focus primarily on the new laser-mode VSTEP with high-intensity light output and narrow optical beam divergence, the design features such as threshold gain and optical absorptivity, device fabrication, and characteristics are explained. The possibility of ultimate performance based mainly on electrical to optical power conversion efficiency, important from the application viewpoint of optical interconnection, are also discussed. Also, as two examples of functional optical interconnection achieved by VSTEP, serial-to-parallel data conversion and optical self-routing switches are shown. Finally, future opto-electronic technologies to be developed for two-dimensionally integrable surface-type optical semiconductor devices, including the VSTEP, are discussed.