• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1142-1145
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• 2008

This paper proposes a novel cluster-based lookup service in mobile ad hoc networks. By applying a self-adaptive multi-hop clustering, we avoid the empty region problem of grid system and omit the need of GPS device. The novelty of the proposed scheme is in its exploitation of hashing function for location querying to achieve low communication overhead. By varying different simulation parameters, we show that the proposed scheme is scalable and adaptive to many networks scenarios. Experiment results demonstrate that our scheme reduces the communication overhead significantly.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.907-910
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• 2000

QPSK 복조기는 위상 오차에 따른 문제점을 극복하기 위해 수신단에서는 반송파의 주파수와 위상을 tracking 하는 Carrier recovery loop부분이 필요하다〔1〕. Carrier recovery loop는 multiplier, arm filter, matched filter, decimator, loop filter, NCO로 구성이 된다〔2〕.기존 Carrier recovery loop의 NCO는 sine과 cosine의 lookup table을 갖는 구조로 되어있어, 전력소모가 크다는 문제점을 가지고 있다. 따라서 본 논문에서는 lookup table을 사용하지 않는 저 전력 구조의 QPSK복조기의 Carrier recovery loop의 NCO를 설계했다.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.4
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• pp.123-128
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• 1994

Hardware realization of a digital 2-D homomorphic filter for real time contrast enhancement of video signal is presented. In homomorphic filter, logarithmic and exponential conversion used the memory lookup table method and because the hardware is implemented by multiplierless TTL devices, it can be designed to specific IC. The contrast gain can be controlled externally and the transfer function of homomorphic filter can be easily varied by the change of lookup table memory data.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.267-268
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• 2007

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.599-602
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• 2014

FPGA상에 AES 복호화 코어를 FIPS-197사양에 기술된 AES 알고리즘의 복호화부분을 구현하였다. 키값의 길이는 128/192/256비트를 지원하며, 별도의 코어 로직은 FPGA의 6-input lookup table의 이점을 살리도록 설계되었으며, 이결과로 2000개의 lookup table만을 이용하여 256비트 키에서 3Gbps의 처리가 가능하게 되었다. 코어는 난수 및 FIPS-197, SP-800a와 AESAVS사양의 테스트 벡터를 통해서 검증하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.137-146
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• 2006

IP address lookup has become a major bottleneck of packet forwarding and a critical issue for high-speed networking techniques in routers. In this paper, we propose an efficient high-speed IP address lookup scheme using adaptive multiple hashing and prefix grouping. According to our analysis results based on routing data distributions, we grouped prefix lengths and selected the number of hash functions in each group adaptively. As a result, we can reduce collisions caused by hashing. Accordingly, a forwarding table of our scheme has good memory efficiency, and thus is organized with the proper number of memory modules. Also, the proposed scheme has the fast building and searching mechanisms to develop the forwarding table only during a single memory access.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.6
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• pp.393-400
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• 2017

For comparison to the Li-ion battery, evaluating a thermal battery must consider additional variables. The first one is the temperature difference between the battery and its unit cell. Thermal batteries and their unit cells have a temperature difference that is caused by the thermal battery activation mechanism and its shape. The second variable is the electrochemical reaction steps. Most Li-ion batteries have a constant electrochemical reaction at the electrode, and battery voltage is affected when the concentration of Li ions is changed. However, a thermal battery has several steps in its electrochemical reaction, and each step has a different potential. In this study, we used unit cell discharge tests based on interpolating a 4D lookup table to estimate the performance of a thermal battery. From the test results, we derived an estimation algorithm by interpolating the table, which is queried from specified profile groups. As a result, we found less than a 5 percent difference between estimation and experiment at the 1.3 V cut-off time.

• The KIPS Transactions:PartA
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• v.13A no.1 s.98
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• pp.11-18
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• 2006

In the Internet of various networks, it is difficult to reduce real routing time by just minimizing their hop count. We propose an adaptive proximity route selection method in DHT-based peer-to-peer systems, in which nodes select the nぉe with smallest lookup latency among their routing table entries as a next routing node. Using Q-Routing algorithm and exponential recency-weighted average, each node estimates the total latency and establishes a lookup table. Moreover, without additional overhead, nodes exchange their lookup tables to update their routing tables. Several simulations measuring the lookup latencies and hop-to-hop latency show that our method outperforms the original Chord method as well as CFS' server selection method.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.3
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• pp.227-240
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• 2003

When we develop and use the java-based distributed object system, the system developer must deploy distributed object, which is implemented to predefined interface, to network and the system user acquires reference about distributed object and changes reference to interface type. Sharing of interface is essential for these works In this paper, we propose the IRSJ(interface repository service based on jim) to improve efficiency of interface sharing at the JINI system development. the IRSJ is consisted of the java classes for JINI system and interface sharing service. If development teams perform collaborative work in short distance, the IRSJ can search interface file without information of lookup server or interface writer If development teams perform collaborative work in long distance, the IRJS can search interface with only an address of server that executes lookup service. Although the interface object not requires additional search, the interface object that failed search interface can download interface and use interface using remote event model. When the message service fails in interface search, the message service sends interface request message to a development team member who use the IRSJ automatically, so that interface sharing may be possible in short time.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.1
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• pp.7-12
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• 2007

In this paper, we introduce an approach to design multi-fuzzy controllers for the superheat and the low pressure that have an influence on energy efficiency and stabilization of aft conditioning system. Air conditioning system is composed of compressor, condenser several evaporators and several expansion valves. It is quite difficult to control the air conditioning system because the change of the refrigerant condition give an impact on the overall air conditioning system. In order to solve the drawback, we design multi-fuzzy controllers which control simultaneously both three expansion valve and one compressor for the superheat and the low pressure of air conditioning system. The proposed multi fuzzy controllers are given as two kinds of controller types such as a continuous simplified fuzzy inference type and a discrete fuzzy lookup_table type. Here the scaling factors of each fuzzy controller ate efficiently adjusted by veal coding type Genetic Algorithms. The values of performance index of the conventional type are compared with the simulation results of discrete lookup_table type and continuous simplified inference type.