Abstract: In this paper, three dimensional flow characteristic was
presented by a revision of an impeller of an axial turbo fan for
improving the airflow rate and the static pressure. TO consider an
incompressible steady three-dimensional flow, the RANS equations
are used as the governing equations, and the standard k-ε turbulence
model is chosen. The pitch angles of 44°, 54°, 59°, and 64° are
implemented for the numerical model. The numerical results show that
airflow rates of each pitch angle are 1,175 CMH, 1,270 CMH, 1,340
CMH, and 800 CMH, respectively. The difference of the static
pressure at impeller inlet and outlet are 120 Pa, 214 Pa, 242 Pa, and 60
Pa according to respective pitch angles. It means that the 59° of the
impeller pitch angle is optimal to improve the airflow rate and the
static pressure.
Abstract: Typhoon Morakot hit Taiwan in 2009 and caused
severe damages. The government employs a compulsory relocation
strategy for post-disaster reconstruction. This study analyzes the
impact of this strategy on community solidarity. It employs a multiple
approach for data collection, including semi-structural interview,
secondary data, and documentation. The results indicate that the
government-s strategy for distributing housing has led to conflicts
within the communities. In addition, the relocating process has
stimulated tensions between victims of the disaster and those residents
whose lands were chosen to be new sites for relocation. The
government-s strategy of “collective relocation" also worsened
community integration. In addition, the fact that a permanent housing
community may accommodate people from different places also posts
challenge for the development of new inter-personal relations in the
communities. This study concludes by emphasizing the importance of
bringing social, economic and cultural aspects into consideration for
post-disaster relocation..
Abstract: In this paper, we propose a practical digital music matching system that is robust to variation in sound qualities. The proposed system is subdivided into two parts: client and server. The client part consists of the input, preprocessing and feature extraction modules. The preprocessing module, including the music onset module, revises the value gap occurring on the time axis between identical songs of different formats. The proposed method uses delta-grouped Mel frequency cepstral coefficients (MFCCs) to extract music features that are robust to changes in sound quality. According to the number of sound quality formats (SQFs) used, a music server is constructed with a feature database (FD) that contains different sub feature databases (SFDs). When the proposed system receives a music file, the selection module selects an appropriate SFD from a feature database; the selected SFD is subsequently used by the matching module. In this study, we used 3,000 queries for matching experiments in three cases with different FDs. In each case, we used 1,000 queries constructed by mixing 8 SQFs and 125 songs. The success rate of music matching improved from 88.6% when using single a single SFD to 93.2% when using quadruple SFDs. By this experiment, we proved that the proposed method is robust to various sound qualities.
Abstract: This paper introduces a measure of similarity between
two clusterings of the same dataset produced by two different
algorithms, or even the same algorithm (K-means, for instance, with
different initializations usually produce different results in clustering
the same dataset). We then apply the measure to calculate the
similarity between pairs of clusterings, with special interest directed
at comparing the similarity between various machine clusterings and
human clustering of datasets. The similarity measure thus can be used
to identify the best (in terms of most similar to human) clustering
algorithm for a specific problem at hand. Experimental results
pertaining to the text categorization problem of a Portuguese corpus
(wherein a translation-into-English approach is used) are presented, as well as results on the well-known benchmark IRIS dataset. The
significance and other potential applications of the proposed measure
are discussed.
Abstract: Extensive information is required within a R&D environment,
and a considerable amount of time and efforts are being
spent on finding the necessary information. An adaptive information
providing system would be beneficial to the environment, and a
conceptual model of the resources, people and context is mandatory
for developing such applications. In this paper, an information model
on various contexts and resources is proposed which provides the
possibility of effective applications for use in adaptive information
systems within a R&D project and meeting environment.
Abstract: The global chaos synchronization for a class of time-delayed power systems is investigated via observer-based approach. By employing the concepts of quadratic stability theory and generalized system model, a new sufficient criterion for constructing an observer is deduced. In contrast to the previous works, this paper proposes a theoretical and systematic design procedure to realize chaos synchronization for master-slave power systems. Finally, an illustrative example is given to show the applicability of the obtained scheme.
Abstract: The accuracy of estimated stability and control
derivatives of a light aircraft from flight test data were evaluated. The light aircraft, named ChangGong-91, is the first certified aircraft from
the Korean government. The output error method, which is a maximum likelihood estimation technique and considers measurement
noise only, was used to analyze the aircraft responses measures. The
multi-step control inputs were applied in order to excite the short period mode for the longitudinal and Dutch-roll mode for the lateral-directional motion. The estimated stability/control derivatives of Chan Gong-91 were analyzed for the assessment of handling
qualities comparing them with those of similar aircraft. The accuracy of the flight derivative estimates derived from flight test measurement
was examined in engineering judgment, scatter and Cramer-Rao bound, which turned out to be satisfactory with minor defects..
Abstract: In order to compare the performance of the carbon dioxide and HFC-125 heat pumps for medium-and high-temperature heating, both heat pump cycles were optimized using a simulation method. To fairly compare the performance of the cycles by using different working fluids, each cycle was optimized from the viewpoint of heating COP by two design parameters. The first is the gas cooler exit temperature and the other is the ratio of the overall heat conductance of the gas cooler to the combined overall heat conductance of the gas cooler and the evaporator. The inlet and outlet temperatures of secondary fluid of the gas cooler were fixed at 40/90°C and 40/150°C.The results shows that the HFC-125 heat pump has 6% higher heating COP than carbon dioxide heat pump when the heat sink exit temperature is fixed at 90ºC, while the latter outperforms the former when the heat sink exit temperature is fixed at 150ºC under the simulation conditions considered in the present study.
Abstract: The objective of this paper is to a design of pattern
classification model based on the back-propagation (BP) algorithm for
decision support system. Standard BP model has done full connection
of each node in the layers from input to output layers. Therefore, it
takes a lot of computing time and iteration computing for good
performance and less accepted error rate when we are doing some
pattern generation or training the network.
However, this model is using exclusive connection in between
hidden layer nodes and output nodes. The advantage of this model is
less number of iteration and better performance compare with standard
back-propagation model. We simulated some cases of classification
data and different setting of network factors (e.g. hidden layer number
and nodes, number of classification and iteration). During our
simulation, we found that most of simulations cases were satisfied by
BP based using exclusive connection network model compared to
standard BP. We expect that this algorithm can be available to
identification of user face, analysis of data, mapping data in between
environment data and information.
Abstract: This study aims to segment objects using the K-means
algorithm for texture features. Firstly, the algorithm transforms color
images into gray images. This paper describes a novel technique for
the extraction of texture features in an image. Then, in a group of
similar features, objects and backgrounds are differentiated by using
the K-means algorithm. Finally, this paper proposes a new object
segmentation algorithm using the morphological technique. The
experiments described include the segmentation of single and multiple
objects featured in this paper. The region of an object can be
accurately segmented out. The results can help to perform image
retrieval and analyze features of an object, as are shown in this paper.
Abstract: The compression-absorption heat pump (C-A HP), one
of the promising heat recovery equipments that make process hot
water using low temperature heat of wastewater, was evaluated by
computer simulation. A simulation program was developed based on
the continuity and the first and second laws of thermodynamics. Both
the absorber and desorber were modeled using UA-LMTD method. In
order to prevent an unfeasible temperature profile and to reduce
calculation errors from the curved temperature profile of a mixture,
heat loads were divided into lots of segments. A single-stage
compressor was considered. A compressor cooling load was also
taken into account. An isentropic efficiency was computed from the
map data. Simulation conditions were given based on the system
consisting of ordinarily designed components. The simulation results
show that most of the total entropy generation occurs during the
compression and cooling process, thus suggesting the possibility that
system performance can be enhanced if a rectifier is introduced.
Abstract: Stream Control Transmission Protocol (SCTP) has been
proposed to provide reliable transport of real-time communications.
Due to its attractive features, such as multi-streaming and multihoming,
the SCTP is often expected to be an alternative protocol
for TCP and UDP. In the original SCTP standard, the secondary path
is mainly regarded as a redundancy. Recently, most of researches
have focused on extending the SCTP to enable a host to send its
packets to a destination over multiple paths simultaneously. In order
to transfer packets concurrently over the multiple paths, the SCTP
should be well designed to avoid unnecessary fast retransmission
and the mis-estimation of congestion window size through the paths.
Therefore, we propose an Enhanced Cooperative ACK SCTP (ECASCTP)
to improve the path recovery efficiency of multi-homed host
which is under concurrent multiple transfer mode. We evaluated the
performance of our proposed scheme using ns-2 simulation in terms
of cwnd variation, path recovery time, and goodput. Our scheme
provides better performance in lossy and path asymmetric networks.
Abstract: In this paper, we address the problem of reducing the
switching activity (SA) in on-chip buses through the use of a bus
binding technique in high-level synthesis. While many binding
techniques to reduce the SA exist, we present yet another technique for
further reducing the switching activity. Our proposed method
combines bus binding and data sequence reordering to explore a wider
solution space. The problem is formulated as a multiple traveling
salesman problem and solved using simulated annealing technique.
The experimental results revealed that a binding solution obtained
with the proposed method reduces 5.6-27.2% (18.0% on average) and
2.6-12.7% (6.8% on average) of the switching activity when compared
with conventional binding-only and hybrid binding-encoding
methods, respectively.
Abstract: For the efficient and safe use of the cable-stayed
bridge, a design based on the detailed local analysis of the cable anchor
system is required. Also, a theoretical design process for the anchor
system should be prepared and reviewed. Generally, the size of the
fixing pipe in the anchor system is decided according to the
specifications prepared by cable-manufacturing companies, and
accordingly, there is difficulty determining the initial inner diameters
of the fixing pipes. As such, there is no choice but to use the products
with the existing sizes. In this study, the existing design process of the
fixing pipe, is a type of guide pipe anchor in the cable anchor system,
is reviewed, a formula determining the thickness of the fixing pipe is
proposed, and the convenience and validity of the suggested equation
is compared with the results of the existing designs to verify its
convenience and validity.
Abstract: The fault current levels through the electric devices
have a significant impact on failure probability. New fault current
results in exceeding the rated capacity of circuit breaker and switching
equipments and changes operation characteristic of overcurrent relay.
In order to solve these problems, SFCL (Superconducting Fault
Current Limiter) has rising as one of new alternatives so as to improve
these problems. A fault current reduction differs depending on
installed location. Therefore, a location of SFCL is very important.
Also, SFCL decreases the fault current, and it prevents surrounding
protective devices to be exposed to fault current, it then will bring a
change of reliability. In this paper, we propose method which
determines the optimal location when SFCL is installed in power
system. In addition, the reliability about the power system which
SFCL was installed is evaluated. The efficiency and effectiveness of
this method are also shown by numerical examples and the reliability
indices are evaluated in this study at each load points. These results
show a reliability change of a system when SFCL was installed.
Abstract: A horizontal anaerobic digester was developed and
tested in pilot scale for Korean food waste with high water contents
(>80%). The hydrogen sulfide in the biogas was removed by a
biological desulfurization equipment integrated in the horizontal
digester. A mixer of the horizontal digester was designed to easily
remove the sediment in the bottom and scum layers on surface in the
digester. Experimental result for 120 days of operation of the pilot
plant showed a high removal efficiency of 81.2% for organic
substance and high stability during the whole operation period were
acquired. Also food waste was treated at high organic loading rates
over 4 kg•VS/m3∙day and a methane gas production rate of 0.62
m3/kg•VSremoved was accomplished.
The biological desulfurization equipment inside the horizontal
digester was proven to be an economic and effective method to reduce
the biogas desulfurization cost by removing hydrogen sulfide more
than 90% without external desulfurization equipments.
Abstract: In this study, a new procedure for inspecting damages on LNG storage tanks was proposed with the use of structural diagnostic techniques: i.e., nondestructive inspection techniques such as macrography, the hammer sounding test, the Schmidt hammer test, and the ultrasonic pulse velocity test, and destructive inspection techniques such as the compressive strength test, the chloride penetration test, and the carbonation test. From the analysis of all the test results, it was concluded that the LNG storage tank cover was in good condition. Such results were also compared with the Korean concrete standard specifications and design values. In addition, the remaining life of the LNG storage tank was estimated by using existing models. Based on the results, an LNG storage tank cover performance evaluation procedure was suggested.
Abstract: In this paper, we propose a novel metal oxide
semiconductor field effect transistor with L-shaped channel structure
(LMOS), and several type of L-shaped structures are also designed,
studied and compared with the conventional MOSFET device for the
same average gate length (Lavg). The proposed device electrical
characteristics are analyzed and evaluated by three dimension (3-D)
ISE-TCAD simulator. It can be confirmed that the LMOS devices
have higher on-state drain current and both lower drain-induced
barrier lowering (DIBL) and subthreshold swing (S.S.) than its
conventional counterpart has. In addition, the transconductance and
voltage gain properties of the LMOS are also improved.
Abstract: This study presents a blower for air management system of fuel cell modules. A blower is composed of BLDC motor and impeller. Magnetic equivalent circuit model and finite element analysis are used to design the motor, and an improved structure is considered to reduce a mechanical loss induced from bearing units. Finally, air blower system combined with the motor and an impeller is manufactured and output properties, such as an air pressure and an amount of flowing air, are measured. Through the experimental results, a validity of the simulated one is confirmed.
Abstract: IMCS is Integrated Monitoring and Control System for
thermal power plant. This system consists of mainly two parts; controllers and OIS (Operator Interface System). These two parts are
connected by Ethernet-based communication. The controller side of communication is managed by CNet module and OIS side is managed
by data server of OIS. CNet module sends the data of controller to data
server and receives commend data from data server. To minimizes or
balance the load of data server, this module buffers data created by controller at every cycle and send buffered data to data server on request of data server. For multiple data server, this module manages
the connection line with each data server and response for each request
from multiple data server. CNet module is included in each controller
of redundant system. When controller fail-over happens on redundant system, this module can provide data of controller to data sever
without loss. This paper presents three main features – separation of get task, usage of ring buffer and monitoring communication status –of CNet module to carry out these functions.