• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2739-2742
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• 2012

6LoWPAN is a standard to enable IPv6 packets to be carried on top of low power wireless networks. It needs to achieve security in 6LoWPAN, which is being defined at the 6LoWPAN working group of the IETF. IPSec is already part of IPv6, which makes it a candidate to be directly employed or adapted for WSNs. Some results showed that the adoption of IPSec is viable, and also point towards the successful design and deployment of security architecture for WSNs. IPSec requires two communicating entities to share a secret key that is typically established dynamically with the IKE. However, there are some limitations to use IKE on wireless networks. In this article, we show requirements for being Efficient Key management Mechanism for IPSec on 6LoWPAN and analyze candidate protocols.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.11
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• pp.419-426
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• 2014

The recent trend of performance increase in the smart mobile devices demands more power consumption and lower batter life time. Among three battery models of mathematical model, electrochemical model and electric model, the Thevenin's equivalent circuit with non-linear function model of SOC in the electrical model is widely used. However, the OCV results have only limited accuracy because of the characteristic shift caused by temperature and age and atypical impedance property that cannot expressed by electrical components. In this paper, the new battery model that improves the accuracy of the existing models is proposed. In the proposed simulator the mathematical model for SOC characteristic is improved and the adjustment for the temperature, the age of battery and atypical electrical characteristics. In the experimental results of predicting of the battery in the static and dynamic state, the proposed simulator shows improved MSE comparing to the results of the existing methods.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1023-1026
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• 2006

에드 혹 네트워크는 불규칙한 이동성을 지닌 다수의 노드들에 의해 자율적으로 구성되는 네트워크이다. 그러나 에드 혹 네트워크는 저 전력, 낮은 프로세싱 능력, 무선채널이라는 에드 혹 네트워크만의 특징으로 인해 패킷 드롭, 재전송 공격, 서비스 거부 공격, 비잔틴 공격, 신원사칭과 같은 보안상 여러 가지 공격에 취약하다는 문제점을 안고 있다. 때문에 이러한 취약점을 개선하려는 방안으로 노드 간에 인증, 기밀성, 무결성을 비롯한 여러 가지 요소를 충족시키기 위한 보안기법이 연구되어 왔다, 그러나 Ad Hoc 네트워크는 기존의 회선을 사용하는 정적인 형태의 네트워크가 아닌 시간에 동적으로 네트워크 구조가 변화하며, 네트워크에서 불규칙한 이동성을 지닌 노드들은 적은양의 자원을 소유하는 원인으로 인해 기존의 보안기법은 효과적이지 못하다. 본 논문에서는 신뢰성이 확보된 이웃 노드 간에 그룹을 형성하고, 그룹멤버의 안전성을 입증하는 그룹 인증서를 생성하여 그룹에 접근하는 단일노드 혹은 또 다른 그룹간의 인증을 수행하는 기법을 제안한다. 또한 그룹 멤버 간에 그룹 키를 생성하여 데이터 유출에 대한 위험성 문제를 해결하고, 인증과 기밀성 유지로 인한 자원소비를 감소시킬 수 있도록 하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.473-476
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• 2003

Nowaday, Internet is doing the role of a large distributed information service tenter and various information and database servers managing it are in distributed network environment. However, the we have several difficulties in deciding the server to disposal input data depending on data properties. In this paper, we designed server mining mechanism and Intellectual data mining system architecture for the best efficiently dealing with input data pattern by using neural network among the various data in distributed environment. As a result, the new input data pattern could be operated after deciding the destination server according to dynamic binding method implemented by neural network. This mechanism can be applied Datawarehous, telecommunication and load pattern analysis, population census analysis and medical data analysis.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.6
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• pp.82-92
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• 2001

This paper describes implementation of an embedded 32-Bit RISC core for portable communication/information equipment, such as cellular phones, PDA(Personal Digital Assistants), notebook, etc. The RISC core implements the ARM$\circled$V 4 instruction set, operates with typical 5-stage pipeline. It supports Thumb code to improve the code density, and uses the dynamic power management method of pipeline registers. It was modeled and simulated in RTL level using VHDL, and verified with ARMulator of ADS (Arm Developer Suite) and had average CPI of 1.44. The core is synthesized automatically using the cell library based on $0.6{\mu}m$ CMOS 1-poly 3-metal CMOS technology. It consists of about 41,000 gates and the clock frequency is expected to be above 45 MHz.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.699-702
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• 2009

저 전력, 내구성, 소형, 빠른 속도 등의 장점을 가지고 있는 플래시 메모리는 생산 기술 발전에 힘입어 센서 노드, 휴대폰, MP3, PMP등의 소형 전자 제품의 저장장치에서부터 SSD형태로 노트북이나 서버에 이르기 까지 그 활용범위가 더욱 확장되어 가고 있다. 다양한 시스템에서 사용될 수 있는 플래시 메모리의 특성상 이에 저장된 데이터의 호환성은 중요한 고려사항이다. 이를 위해 플래시 메모리의 고유한 특성을 숨기고 일반적인 블록장치로 에뮬레이션 해주는 소프트웨어인 FTL과 FAT 파일시스템이 플래시 메모리 관리를 위한 사실상 표준 소프트웨어로써 사용되고 있다. 그러나 범용 컴퓨터를 기반으로 개발된 FTL과 FAT 파일시스템을 열악한 하드웨어로 구성된 시스템에서 구동하는 경우 많은 제약이 발생한다. 따라서 본 논문에서는 이러한 제약사항을 극복하기 위해 최소한의 파일시스템 기능을 제공하는 FAT 표준 호환 FTL을 제안한다. 제안된 기법은 리눅스 운영체제에 동적으로 적재 가능한 모듈형태로 구현되었으며, 실험을 통해 본 논문에서 제안한 기법이 기존 기법 대비 32%의 메모리 공간을 절약할 수 있으며, 동시에 완벽한 FAT 호환성을 제공함을 확인할 수 있었다.

• Transactions of the KSME C: Technology and Education
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• v.4 no.1
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• pp.35-41
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• 2016

Geothermal heat pump (GHP) systems have been proved to be one of the most efficient systems for heating and cooling in buildings. However, an optimal energy performance depends on a good control of the system components, including heat pumps and circulation pumps, which affect to the total energy consumption of system. This paper presents the simulation results of the heat pump performance for two different control schemes, i.e. constant setting temperature (Control-A) and variable setting temperatures (Control-B) in buffer tank. A dynamic simulation tool, TRNSYS 17, was used to model the entire system and to assess the performance of the system. Simulation results show that the Control-B, which controls the temperature in buffer tank with outdoor air temperature, is a effective way to reduce the energy consumptions in heat pump (7.7%) and circulation pump (7.5%).

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.3
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• pp.281-288
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• 2002

This paper has realized a control system of a vibrator using PM excited Transverse Flux Linear Motor(TFLM). Proposed vibrator can supply a vibration force up to 700[N] at rated current, wide operation range of vibration displacement and high frequency for a tested structure. Also, volume of a vibrator system can be decreased because of a high trust force rato(a thrust force per weight=N/Kg). A proposed vibrator instead of a hydraulic vibrator can improve efficiency and have may advantages of maintenance and management. A desired value command is a vibration frequency and displacement in a controller for a vibrator system and a controlled values we a instant position and velocity of a mover Output value of the controller is phase current controlled by PWM converter. In this research, Dynamic simulation has been executed for analysis of a control algorithm and dvnauuc characteristics and is compared with experimental result.

• The Journal of the Korea Contents Association
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• v.7 no.2
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• pp.51-62
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• 2007

Recently microcontrollers are being used in sensor networks to handle sophisticated control and monitoring activities. As applications become more sophisticated, their design and development processes become more complex which consequently necessitates the use of an operating system to manage the complexity and provide an abstraction for portability of code. This paper presents a Low-power real-time operating system, called UbiFOS-USN, designed for sensor networks. We present some of the features that make UbiFOS-USN appropriate especially for small, low-cost microcontrollers typically found in sensor networks. Through experimental results, we show that UbiFOS-USN is quite efficient for a sensor network, both in terms of system performance and memory requirement.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.107-115
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• 2006

The existing DLC system functionally has two defects. One is it has to be controlled by operators whenever customer's portion of loads are increased more than predefined objected load. Therefore, it may be possible for propagating uncontrolled loads if operators make a mistake. The other one is that currently used DLC algorithm is usually focused on ON/OFF load control not concerning about reliving participated customer's inconvenience. Therefore, that is a major obstacle to attract customer participating in demand response program. This paper represents direct load control system using active database. By using active database, DLC system can control customer's load effectively without intervening of operator. And by using dynamic programming based on the order of priority for DLC algorithm, it is possible to maximize participating customer's satisfaction.