• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.3-5
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• 2006

Recent advances in the internet infrastructure have resulted in a large number of huge Web sites and portals worldwide. These Web sites are being visited by various types of users in many different ways. Among all the web page access sequences from different users, some of them occur so frequently that may need an attention from those who are interested. We call them frequent access patterns and access sequences that can be frequent the candidate patterns. Since these candidate patterns play an important role in the incremental Web mining, it is important to efficiently generate, add, delete, and search for them. This thesis presents a novel tree structure that can efficiently store the candidate patterns and a related set of algorithms for generating the tree structure adding new patterns, deleting unnecessary patterns, and searching for the needed ones. The proposed tree structure has a kind of the 3 dimensional link structure and its nodes are layered.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.423-425
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• 2007

In this paper, Medium Access Control(MAC) protocol designed for Wireless Body area Sensor Network(Bio-MAC) is proposed, Because in WBSN, the number of node is limited and each node has different characteristics. Also, reliability in transmitting vital data sensed at each node and periodic transmission should be considered so that general MAC protocol cannot satisfy such requirements of biomedical sensors in WBSN. Bio-MAC aims at optimal MAC protocol in WBSN. For this, Bio-MAC used Pattern -SuperFrame, which modified IEE E 802.15.4-based SuperFrame structurely. Bio-MAC based on TDMA uses Medium Access-priority and Pattern eXchange -Beacon method for dynamic slot allocation by considering critical sensing data or power consumption level of sensor no de etc. Also, because of the least delay time. Bio-MAC is suitable in the periodic transmission of vital signal data. The simulation results demonstrate that a efficient performance in WBSN can be achieved through the proposed Bio-MAC.

• Journal of Information Science Theory and Practice
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• v.2 no.2
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• pp.33-47
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• 2014

Mobile devices are the most important equipment for accessing various kinds of services. These services are accessed using wireless signals, the same used for mobile calls. Today mobile services provide a fast and excellent way to access all kinds of information via mobile phones. Mobile service providers are interested to know the access behavior pattern of the users from different locations at different timings. In this paper, we have introduced an associated tree for analyzing user behavior patterns while moving from one location to another. We have used four different parameters, namely user, location, dwell time, and services. These parameters provide stronger frequent accessing patterns by matching joins. These generated patterns are valuable for improving web services, recommending new services, and predicting useful services for individuals or groups of users. In addition, an experimental evaluation has been conducted on simulated data. Finally, performance of the proposed approach has been measured in terms of efficiency and scalability. The proposed approach produces excellent results.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.143-152
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• 2004

Recently, software programming method based on EJB for object oriented software design and implement has been used frequently. Usually, case that use permanent data that use Database in EJB base application is most. Part connected with Database-Access that take charge in Entity Bean class of server side creation program. In this paper using J2EE relationship DAO pattern class each separate. This is no much difference with existent pattern method, but in same pattern common classes are designed so that composition may be possible. And as well as use Entity Bean class that created each DBMS classes are different, is doing Rata Source so that connection work is available without alteration or creation of additional program in several DBMS environments.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.3
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• pp.158-166
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• 2008

These days, mobile embedded systems adopt flash memory capable of XIP feature since they can reduce memory usage, power consumption, and software load time. XIP provides direct access to ROM and flash memory for processors. However, using XIP incurs unnecessary degradation of applications' performance because direct access to ROM and flash memory shows more delay than that to main memory. In this paper, we propose a memory management framework, dynamic XIP, which can resolve the performance degradation of using XIP. Using a constrained RAM cache, dynamic XIP can dynamically change XIP region according to page access pattern to reduce performance degradation in execution time or energy consumption resulting from native XIP problem. The proposed framework consists of a page profiler gathering applications' memory access pattern using PMU and an XIP manager deciding that a page is accessed whether in main memory or in flash memory. The proposed framework is implemented and evaluated in Linux kernel. Our evaluation shows that our framework can reduce execution time at most 25% and energy consumption at most 22% compared with using XIP-only case adopted in general mobile embedded systems. Moreover, the evaluation shows that in execution time and energy consumption, our modified LRU algorithm with code page filters can reduce more than at most 90% and 80% respectively compared with applying just existing LRU algorithm to dynamic XIP.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.401-407
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• 2006

In this paper, we present a small-sized and light weighted dual-band antenna for an access point of 2.4/5 GHz dual-band WLAN(Wireless Local Area Network). The antenna for WLAN should show the characteristic of omni-directional radiation pattern. First, to obtain the omni-directional radiation pattern the proposed dual-band antenna has an orthogonal inverted triangular type element at the center and locates four resonating elements symmetrically around it. Also, for the purpose of easy manufacturing and miniaturization of the antenna, we changed the central element which had the orthogonal inverted triangular type structure into the plate type. Measured $S_{11}$ for the proposed dual-band plate type antenna showed characteristic which was less then -12.8 dB for WLAN frequency bands. Measured results for the maximum gain showed 3.17 dBi at 2.44 GHz, 5.38 dBi at 5.77 GHz with omni-directional radiation pattern. The implemented antennas showed applicable performances for the access point of WLAN.

• The KIPS Transactions:PartA
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• v.12A no.3 s.93
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• pp.223-228
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• 2005

Several researchers have pointed out that the energy consumption in memory takes a dominant fraction on the energy budget of a whole embedded system. This applies to the embedded Java virtual machine tn, and to develop a more energy-efficient JVM it is absolutely necessary to optimize the energy usage in Jana memory. In this paper we have analyzed the logical memory access pattern in JVM as it executes numerous number of bytecode instructions while running a Java program. The access pattern gives us an insight how to design and select a suitable memory technology for Java memory. We present the memory access pattern for the three logical data spaces of JVM: heap, operand stack, and local variable array. The result saws that operand stack is accessed most frequently and uniformly, whereas heap used least frequently and non-uniformly among the three. Both heap and local variable array are accessed mostly in read-only fashion, but no remarkable difference is found between read and write operations for operand stack usage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.947-953
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• 2011

These days, a consistent and fatal attack attribute toward a database has proportionally evolved in the similar development form to that of security policy. Because of access control-based defensive techniques regarding information created in closed networks and attacks on a limited access pathway, cases of infringement of many systems and databases based on accumulated and learned attack patterns from the past are increasing. Therefore, the paper aims to separate attack information by its types based on a virtual infringement pattern system loaded with dualistic VM in order to ensure stability to limited certification and authority to access, to propose a system that blocks infringement through the intensive management of infringement pattern concerning attack networks, and to improve the mechanism for implementing a test that defends the final database, the optimal defensive techniques, and the security policies, through research.

• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.313-318
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• 2006

In this paper, we propose an efficient Care of Address (CoA) configuration scheme for network mobility support in the railroad environment. Mobile routers in a train visit each access router in the fixed order. Such regular movement characteristic of a train enables a current subnet access router to inform the next subnet access router of the mobile routers' interface identifiers before the mobile routers move to the next subnet access router. So, the next subnet access router can make care of addresses for the mobile routers in advance. The numerical results show that the proposed scheme outperforms the stateless scheme with respect to CoA configuration time.

• KDI Journal of Economic Policy
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• v.42 no.3
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• pp.1-32
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• 2020

This paper studies urban growth in Korean cities. First, I document that population growth patterns change over time and that the current population distribution supports random urban growth. I confirm two empirical laws-Zipf's law and Gibrat's law-both of which hold in the period of 1995-2015, but do not hold in the earlier period of 1975-1995. Second, I find a systematic employment growth pattern of Korean cities in spite of the random population growth. I examine market access effects on employment growth. Market access, a geographical advantage, has a significant influence on urban employment growth. The market access effect is higher in the Seoul metropolitan area than in the rest of the country. This effect is stronger on employment growth in the manufacturing industry compared to employment growth in the service industry. These results are robust with various checks (e.g., different definitions of urban areas). The results here suggest that policymakers should consider geographical characteristics when they make policy decisions with respect to regional development.