• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.44 no.5
• /
• pp.1-6
• /
• 2007

In wireless mesh networks (WMNs), the end-to-end throughput of a flow decreases drastically according to the traversed number of hops due to interference among different hops of the same flow in addition to interference between hops of different flows with different paths. This paper proposes a distributed multi-channel assignment scheme based on hops (DMASH) to improve the performance of a static WMN. The proposed DMASH is a novel distributed multi-channel assignment scheme based on hops to enhance the end-to-end throughput by reducing interference between channels when transmitting packets in the IEEE 802.11 based multi-interface environments. The DMASH assigns a channel group to each hop, which has no interference between adjacent hops from a gateway in channel assignment phase, then each node selects its channel randomly among the channel group. Since the DMASH is a distributed scheme with unmanaged and auto-configuration of channel assignment, it has a less overhead and implementation complexity in algorithm than centralized multi-channel assignment schemes. Simulation results using the NS-2 showed that the DMASH could improve remarkably the total network throughput in multi-hop environments, comparing with a random channel assignment scheme.

• Journal of Biomedical Engineering Research
• /
• v.20 no.1
• /
• pp.107-113
• /
• 1999

The purpose of this study was to develop a miniature imaging gamma probe with high performance that can detect small or residual tumors after surgery. Gamma probe detector system consists of NaI(Tl) scintillator, position sensitive photomultiplier tube (PSPMT), and collimator. PSPMT was optically coupled with 6.5 mm thick, 7.62 cm diameter of NaI(Tl) crystal and supplied with -1000V for high voltage. Parallel hexagonal hole collimator was manufactured for characteristics of 40-mm hole length, 1.3-mm hole diameter, and 0.22 mm septal thickness. Electronics consist of position and trigger signal readout systems. Position signals were obtained with summing, subtracting, and dividing circuit using preamplifer and amplifier. Trigger signals were obtained using summing amplifier, constant fraction discriminator, and gate and delay generator module with preamplifer. Data acquisition and processing were performed by Gamma-PF interface board inserted into pentium PC and PIP software. For imaging studies, flood and slit mask images were acquired using a point source. Two hole phantom images were also acquired with collimator. Intrinsic and system spatial resolutions were measured as 3.97 mm and 5.97 mm, respectively. In conclusion, Miniature gamma probe images based on the PSPMT showed good image quality, we conclude that the miniature imaging gamma probe was successfully developed and good image data were obtained. However, further studies will be required to optimize imaging characteristics.

• Journal of KIISE:Software and Applications
• /
• v.29 no.9
• /
• pp.605-618
• /
• 2002

The CBD (Component Based Development) is a requisite technique for the Time-To-Market, and a highly reusable component should be provided to develop a variety of domain applications with the use of components. To increase the reusability of components, they should be developed by analyzing requirements of many different kinds of domains. However, to analyze requirements of a variety of domains related to the components to be developed and to include them inside the components will give burden to developers. Also, providing only general components that have common facilities for the several domains is not easy to accomplish the time-to-market since there are other domains that the developers have to develop. As such, developing common component through the analysis of several domains at the time of the CD (Component Development) does not always guarantee high reusability of the component, but gives burden to developers to develop another development since such components have common functions. Considering this, this paper proposes the component customization technique to reuse common components as well as special components. The reusability of the component can be increased by providing changeability of the attribute, behavior and message flow of the component. This customization technique can change the message flow to integrate developed components or to provide new functions within the component. Also, provides a technique to replace the class existing within the component with other class or to exchange the integrated component with the component having a different function so that requirements from a variety of domains may be satisfied. As such, this technique can accept the requirements of several domains. As such, this customization technique is not only the component with a common function, but it also secures reusability components in the special domain.

• Journal of KIISE:Software and Applications
• /
• v.27 no.2
• /
• pp.193-200
• /
• 2000

The extraction of face regions is required for Head Gesture Interface which is a natural user interface. Recently, many researchers are interested in using color information to detect face regions in image sequences. Two most widely used color models, HSI color model and YIQ color model, were selected for this study. Actually H-component of HSI and I-component of YIQ are used in this research. Given the difference in the color component, this study was aimed to compare the performance of face region detection between the two models. First, we search the optimum range of facial color for each color component, examining the detection accuracy of facial color regions for variant threshold range about facial color. And then, we compare the accuracy of the face box for both color models by using optimal facial color and motion information. As a result, a range of $0^{\circ}{\sim}14^{\circ}$ in the H-component and a range of $-22^{\circ}{\sim}-2^{\circ}$ in the I-component appeared to be the most optimum range for extracting face regions. When the optimal facial color range is used, I-component is better than H-component by about 10% in accuracy to extract face regions. While optimal facial color and motion information are both used, I-component is also better by about 3% in accuracy to extract face regions.

• Journal of Broadcast Engineering
• /
• v.23 no.2
• /
• pp.246-252
• /
• 2018

Hand gestures are attracting attention as a NUI (Natural User Interface) of wearable devices such as smart glasses. Recently, to support efficient media consumption in IoT (Internet of Things) and wearable environments, the standardization of IoMT (Internet of Media Things) is in the progress in MPEG. In IoMT, it is assumed that hand gesture detection and recognition are performed on a separate device, and thus provides an interoperable interface between these modules. Meanwhile, deep learning based hand gesture recognition techniques have been recently actively studied to improve the recognition performance. In this paper, we propose a method of hand gesture recognition based on CNN (Convolutional Neural Network) for various applications such as media consumption in wearable devices which is one of the use cases of IoMT. The proposed method detects hand contour from stereo images acquisitioned by smart glasses using depth information and color information, constructs data sets to learn CNN, and then recognizes gestures from input hand contour images. Experimental results show that the proposed method achieves the average 95% hand gesture recognition rate.

• Journal of KIISE:Computing Practices and Letters
• /
• v.8 no.5
• /
• pp.607-617
• /
• 2002

IETF has proposed CNRP that is a protocol exchanging CNRP objects between server and client for resolving a common name to URIs of the desired Internet resouces. CNRP enables users to access various services via the integrated interface, to easily get the desired resources, and to reuse the results not as the data but as the information. Whereby these advantages, CNRP will be generally used for the integration of the various Internet services or the applications where the resolution of common name is needed. But, CNRP specification doesn't describes the practical implementation method for server and client. Though a few prototype systems are developed in some researches using CNRP, they are not enough to be generally used for the various Internet applications because they doesn't include all objects specified in CNRP specification or they construct systems with one server. So, this Paper proposes the practical implementation method for CNRP server/client through analyzing and solving the problems occurred when implementing them, and implements all objects specified in CNRP specification. This paper also verifies the feasibility of the proposed method by developing the prototype system of the company name resolution service using the CNRP server/client implemented in this study. The CNRP server/client implemented in this paper are used to develop various CNRP application systems.

• Journal of KIISE:Computer Systems and Theory
• /
• v.31 no.12
• /
• pp.704-715
• /
• 2004

Recently, a single or multi processor system uses the hierarchical memory structure to reduce the time gap between processor clock rate and memory access time. A cache memory system includes especially two or three levels of caches to reduce this time gap. Moreover, one of the most important things In the hierarchical memory system is the hit rate in level 1 cache, because level 1 cache interfaces directly with the processor. Therefore, the high hit rate in level 1 cache is critical for system performance. A victim cache, another high level cache, is also important to assist level 1 cache by reducing the conflict miss in high level cache. In this paper, we propose the advanced high level cache management scheme based on the processor reuse information. This technique is a kind of cache replacement policy which uses the frequency of processor's memory accesses and makes the higher frequency address of the cache location reside longer in cache than the lower one. With this scheme, we simulate our policy using Augmint, the event-driven simulator, and analyze the simulation results. The simulation results show that the modified processor reuse information scheme(LIVMR) outperforms the level 1 with the simple victim cache(LIV), 6.7% in maximum and 0.5% in average, and performance benefits become larger as the number of processors increases.

• Journal of KIISE:Computing Practices and Letters
• /
• v.10 no.6
• /
• pp.472-483
• /
• 2004

Many metadata registry management systems have been developed, which are based on ISO/IEC ll179. However, they do not follow the international standard, ISO/IEC ll179 nor provide some of mandatory functions. It is difficult to a develop metadata registry management system for domestic environment because of their hidden implementations. The goals of this paper are to solve the problems of the existing systems and to develop a metadata registry management systems for accumulation of primitive technologies. This paper also shows the metadata registry building process for the science and technology information field using the developed system. This system consists of Metadata Registry Layer, Core Component Layer, Extension Layer, and Service Interface Layer. The developed metadata registry management system follows ISO/IEC ll179 and contains mandatory functions for practical use. Therefore, it can be used as a guideline for building metadata registries and a development process of metadata registry management systems. We can easily reuse its components for development of metadata registry management systems in various fields because the system is designed and implemented based on the component-based development methodology. It also decreases time and cost for developing systems.

• Journal of KIISE:Information Networking
• /
• v.30 no.3
• /
• pp.377-386
• /
• 2003

In this paper, we present an application layer protocol to support secure wireless Internet services, called Application Layer Security(ALS). The drawbacks of the two traditional approaches to secure wireless applications motivated the development of ALS. One is that in the conventional application-specific security protocol such as Secure HyperText Transfer Protocol(S-HTTP), security mechanism is included in the application itself. This gives a disadvantage that the security services are available only to that particular application. The other is that a separate protocol layer is inserted between the application and transport layers, as in the Secure Sockets Layer(SSL)/Transport Layer Security(TLS). In this case, all channel data are encrypted regardless of the specific application's requirements, resulting in much waste of network resources. To overcome these problems, ALS is proposed to be implemented on top of HTTP so that it is independent of the various transport layer protocols, and provides a common security interface with security applications so that it greatly improves the portability of security applications. In addition, since ALS takes advantages of well-known TLS mechanism, it eliminates the danger of malicious attack and provides applications with various security services such as authentication, confidentiality integrity and digital signature, and partial encryption. We conclude this paper with an example of applying ALS to the solution of end-to-end security in a present commercial wireless protocol stack, Wireless Application Protocol.

• Journal of KIISE:Databases
• /
• v.36 no.2
• /
• pp.112-122
• /
• 2009

The EPCglobal leading the development in RFID standards proposed Event Cycle Specification (ECSpec) and Event Cycle Reports (ECReports) for the standard about RFID middleware interface. ECSpec is a specification for filtering and collecting RFID tag data and is treated as a Continuous Query (CQ) processed during fixed time intervals repeatedly. ECReport is a specification for describing the results after ECSpec is processed. Thus, it is efficient to apply Query Indexing technique designed for the continuous query processing. This query index processes ECSpecs as data and tag events as queries for efficiency. In logistics environment, the similar or same products are transferred together. Also, when RFID tags attached to the products are acquired, the acquisition events occur massively for the short period. For these properties, it is inefficient to process the massive events one by one. In this paper, we propose a technique reducing similar search process by considering tag events which are collected by the report period in ECSpec, as a range query. For this group processing, we suggest a queuing method for collecting tag events efficiently and a structure for generating range queries in the queues. The experiments show that performance is enhanced by the proposed methods.