• Journal of Korean Society of Forest Science
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• v.88 no.3
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• pp.389-399
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• 1999

This study was conducted to develop an application software, SIDAS3D(Stand Inventory Data Analysis System for 3 Dimensional Representation), of which the purpose of development is to make it easier to analyze and display the 3D spatial structure of a forest stand, based on the data such as tree position, species, DBH, height, clear length of individual trees, and crown width. This program has a statistical analysis function for stand attributes per hectare and displays simple graphs of stand statistics such as the distribution of diameters, heights, and volumes. It also has two additional functions, of which one is to display the 3D image of stand structure and the other is to display the image of crown projection. In addition, this program provides an imaginary treatment simulation function, which can visually confirm the suitability of silvicultural treatments on computers. To test the precision and reliability of SIDAS3D, data obtained by the precision forest inventory method were used. Statistical analysis ability of SIDAS3D was compared with that of SAS. And its representational ability was compared with that of TreeDraw. According to the verification, SIDAS3D was superior to SAS and TreeDraw in both the data processing time and the interpretative ability of results. It was concluded that SIDAS3D could be used to help users efficiently make decisions for appropriate silvicultural treatments and rational management plans because it has analysis functions providing various valuable information.

• Journal of IKEEE
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• v.14 no.2
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• pp.16-23
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• 2010

Since the interest of a brain science research is increased recently, various devices using brain waves have been developed in the field of brain training game, education application and brain computer interface. In this paper, we have developed a portable EEG measurement and a bluetooth based wireless transmission device measuring brain waves from the frontal lob simply and conveniently. The low brain signals about 10~100${\mu}V$ was amplified into several volts and low pass, high pass and notch filter were designed for eliminating unwanted noise and 60Hz power noise. Also, PIC24F192 microcontroller has been used to convert analog brain signal into digital signal and transmit the signal into personal computer wirelessly. The sampling rate of 1KHz and bluetooth based wireless transmission with 38,400bps were used. The LabVIEW programing was used to receive and monitor the brain signals. The power spectrum of commercial biopac MP100 and that of a developed EEG system was compared for performance verification after the simulation signals of sine waves of $1{\mu}V$, 0~200Hz was inputed and processed by FFT transformation. As a result of comparison, the developed system showed good performance because frequency response of a developed system was similar to that of a commercial biopac MP100 inside the range of 30Hz specially.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.7
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• pp.349-358
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• 2005

False sharing is a result of co-location of unrelated data in the same unit of memory coherency, and is one source of unnecessary overhead being of no help to keep the memory coherency in multiprocessor systems. Moreover. the damage caused by false sharing becomes large in proportion to the granularity of memory coherency. To reduce false sharing in a page-based DSM system, it is necessary to allocate unrelated data objects that have different access patterns into the separate shared pages. In this paper we propose call-site tracing-based shared memory allocator. shortly CSTallocator. CSTallocator expects that the data objects requested from the different call-sites may have different access patterns in the future. So CSTailocator places each data object requested from the different call-sites into the separate shared pages, and consequently data objects that have the same call-site are likely to get together into the same shared pages. We use execution-driven simulation of real parallel applications to evaluate the effectiveness of our CSTallocator. Our observations show that by using CSTallocator a considerable amount of false sharing misses can be additionally reduced in comparison with the existing techniques.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.24-30
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• 2002

Label switching technology is currently emerging as a solution for the rapidly growing of Internet traffic demand. Multiprotocol label switching(MPLS) is one of the standards made by the Internet Engineering Task Force(IETE) intended to enhance speed, scalability, and inter-opearability between label switching technologies. In MPLS, utilization of label space is a very important factor of network performance because labels are basic unit in packet switching. We propose a algorithm to effectively use label space by a multiple disconnect timer at the label switching router. Our algorithm is based on multiple utilization of the connection release timer over the MPLS network with multiple domains. In our algorithm, a relatively linger timeout interval is assigned to the traffic with higher class by the aid of the packet classifier. This reduces delay for making a new connection and also reduces the amount of packets which will be routed to the layer 3. Simulation results shows that reduction of required label number in MPLS network and this indicate our algorithm offers better performance than the existing ones in term of utilization of label space.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.65-76
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• 2002

QoS routing is a routing technique for finding feasible path that satisfies QoS requirements required by application programs. Since QoS routing determines such paths in terms of dynamic network state, it satisfies the requirement of applications and increases the utilization of the network. The overhead is, however, generated by routers to exchange the information of the dynamic state of network. In order to reduce this protocol overhead, a timer based update mechanism is proposed in which router checks the change of the network status periodically and network state information is exchanged if the change is greater than a certain value. Using large update period makes, though, routing performance irresponsive to the parameters which determine the update of the network state of the router. In addition to this, large update period may result in inaccurate network state information at routers and cause resource reservation failure. The resource reservation failure generates additional overhead to cancel the resource reservation of the part of the path. In this paper, we propose mechanisms enhancing the existing network state update policy with respect to these two problems. Performance of the proposed schemes are evaluated through a course of simulation.

• Journal of KIISE:Software and Applications
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• v.29 no.5
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• pp.326-335
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• 2002

Recently there have been a number of researches to provide code mobility to lazy functional language (LFL) programs by translating LFL programs to Java programs. These approaches are basically baled on architectural similarities between abstract machines of LFLs and Java. The abstract machines of LFLs and Java programming language, Spineless Tagless G-Machine(STGM) and Java Virtual Machine(JVM) respectively, share important common features such as built- in garbage collector and stack machine architecture. Thus, we can provide code mobility to LFLs by translating LFLs to Java utilizing these common features. In this paper, we propose a new translation scheme which fully utilizes architectural common features between STGM and JVM. By redefining STGM as an eval-apply evaluation model, we have defined a new translation scheme which utilizes Java Virtual Machine Stack for function evaluation and totally eliminates stack simulation which causes array manipulation overhead in Java. Benchmark program translated to Java programs by our translation scheme run faster on JDK 1.3 than those translated by the previous schemes.

• Journal of KIISE:Software and Applications
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• v.31 no.4
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• pp.411-419
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• 2004

When the imaging object rotates in image plane during MRI scan, its rotation causes phase error and non-uniform sampling to MRI signal. The model of the problem including phase error non-uniform sampling of MRI signal showed that the MRI signals corrupted by rotations about an arbitrary center and the origin in image plane are different in their phases. Therefore the following methods are presented to improve the quality of the MR image which includes the artifact. The first, assuming that the angle of 2-D rotational motion is already known and the position of 2-D rotational center is unknown, an algorithm to correct the artifact which is based on the phase correction is presented. The second, in case of 2-D rotational motion with unknown rotational center and unknown rotational angle, an algorithm is presented to correct the MRI artifact. At this case, the energy of an ideal MR image is minimum outside the boundary of the imaging object to estimate unknown motion parameters and the measured energy increases when the imaging object has an rotation. By using this property, an evaluation function is defined to estimate unknown values of rotational angle at each phase encoding step. Finally, the effectiveness of this presented techniques is shown by using a phantom image with simulated motion and a real image with 2-D translational shift and rotation.

• Journal of KIISE:Databases
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• v.30 no.5
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• pp.476-493
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• 2003

Data broadcast is an effective data transmission method from a data base server to numerous mobile clients due to the restrictions on mobile environment such as low wireless communication bandwidth and energy shortage of mobile devices. There are various broadcast methods based on clients' data access frequencies or semantic relationship of data. The broadcast schedule based only on the access frequencies does not consider semantic relations of data, so that when a client needs to access a series of semantically related data, the client has to listen to the wireless channel for a long time. On the other hand, the broadcast schedule based only on semantic relationship of data makes data access time longer when clients highly request specific data which are not semantically related but frequently accessed. In this paper, we present an efficient data broadcast method based on not only data access frequencies but also semantic relationship to improve mobile clients' query response time. The new hybrid broadcast method we propose creates a data broadcast schedule according to the data access frequencies and then the schedule is adjusted to reflect semantic relationship of data. We show our method is efficient by experimental performance analysis.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.10
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• pp.569-578
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• 2003

Data dependencies are one of major hurdles to limit ILP(Instruction Level Parallelism), so several related works have suggested that the limit imposed by data dependencies can be overcome to some extent with use of the data value prediction. Hybrid value predictor can obtain the high prediction accuracy using advantages of various predictors, but it has a defect that same instruction has overlapping entries in all predictor. In this paper, we propose a new hybrid value predictor which achieves high performance by using the information of static and dynamic classification. The proposed predictor can enhance the prediction accuracy and efficiently decrease the prediction table size of predictor, because it allocates each instruction into single best-suited predictor during the fetch stage by using the information of static classification. Also, it can enhance the prediction accuracy because it selects a best- suited prediction method for the “Unknown”pattern instructions by using the dynamic classification mechanism. Simulation results based on the SimpleScalar/PISA tool set and the SPECint95 benchmarks show the average correct prediction rate of 85.1% by using the static classification mechanism. Also, we achieve the average correction prediction rate of 87.6% by using static and dynamic classification mechanism.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.1-14
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• 2002

The most important issue in providing multimedia traffic on a mobile computing environments is to guarantee the mobile host(client) with consistent QoS(Quality of Service). However, the QoS negotiated between the client and network in one cell may not be honored due to client mobility, causing hand-offs between cells. In this paper, a call admission control mechanism is proposed to provide consistent QoS guarantees for multimedia traffics in a mobile computing environment. Each cell can reserve fractional bandwidths for hand-off calls to its adjacent cells. It is important to determine the right amount of reserved bandwidth for hand-off calls because the blocking probability of new calls may increase if the amount of reserved bandwidth is more than necessary. An adaptive bandwidth reservation based on an MPP(Mobility Pattern Profile) and a 2-tier cell structure has been proposed to determine the amount of bandwidth to be reserved in the cell and to control dynamically its amount based on its network condition. We also propose a call admission control based on this bandwidth reservation and "next-cell prediction" scheme using an MPP. In order to evaluate the performance of our call admission control mechanism, we measure the metrics such as the blocking probability of our call admission control mechanism, we measure the metrics such as the blocking probability of new calls, dropping probability of hand-off calls, and bandwidth utilization. The simulation results show that the performance of our mechanism is superior to that of the existing mechanisms such as NR-CAT1, FR-CAT1, and AR-CAT1.