• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.4
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• pp.85-94
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• 2003

The asynchronous design methods proved to have the higher performance in power consumption and execution speed than synchronous ones because it just needs to activate the required module without feeding clock in the system. Despite the advantage of CISC machine providing the variable addressing modes and instructions, its execution scheme is hardly suited for a synchronous Pipeline architecture and incurs a lot of overhead. This paper proposes a novel asynchronous pipeline architecture, A80sl, whose instruction set is fully compatible with that of Intel 80C51, an embedded micro controller. We classify the instructions into the group keeping the same execution scheme for the asynchronous pipeline and optimize it eliminating the bubble stage that comes from the overhead of the multi-cycle execution. The new methodologies for branch and various instruction lengths are suggested to minimize the number of states required for instructions execution and to increase its parallelism. The proposed A80C51 architecture is synthesized with 0.35${\mu}{\textrm}{m}$ CMOS standard cell library. The simulation results show higher speed than that of Intel 80C51 with 36 MHz and other asynchronous counterparts by 24 times.

• 한국해양학회지
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• v.29 no.4
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• pp.392-401
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• 1994

We examined the temporal characteristics of the oceanic eddy diffusion at 5 coastal regions of Korea by measuring the separation distances of multiple drifters released simultaneously at the same by the GPS and Decca transponder system. The observed variance of separation distance, for the time scales from minutes to hours, is proportional to t/SUP m/ with scaling exponent m between 1.2 and 2.0. The observed Lagrangian trajectories of drifters show fractal characteristics instead of random walk or Brown motion. As an effort toward a development of a realistic model of the oceanic eddy diffusion, we simulated the Lagrangian trajectories of drifters by fractional Brown motion (FBM) model. The observed variances of drifter separations can be generated by the FBM process provided the Hurst exponent is the same as the observed one. We further showed that the observed power law in the variance of drifter separations cannot be simulated with an ordinary Brown motion or random walk process.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.234-239
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• 2012

Next generation mobile communication systems have been studied and applied to support various services. In next generation mobile communication systems, the most interested research is the integration of various communication systems and the offer of various services by using high-speed data transmission. The integration of communication systems has been researched by using multi standard modem, while the high-speed data transmission for the offer of various services has been applied by using OFDM. This paper has proposed the method to reduce PAPR by using multi standard modem. with EVM, this paper has also suggested the method to compensate in-band distortion while reducing PAPR. By using the proposed methods, this paper has analyzed and simulated the decrease efficiency of PAPR, the performance of CCDF, and the performance of BER in next generation mobile communication systems. The simulation results improved the performance of next generation mobile communication system can be seen that.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.467-467
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• 2011

기후변화로 인한 수문학적 변동은 지속가능한 수자원 관리를 위해 중요한 인자로 고려되고 있다. 특히, 가뭄 등 기상재해는 자연재해 차원을 넘어서 사회적 갈등으로 발전할 여지가 크며 특히 수자원 배분은 환경, 경제를 뛰어넘은 생존의 문제로 발전하고 있다. 따라서 본 연구는 기후변화가 가져올 가뭄 등 재해관리를 위한 의사지원체계 구축하고 다양한 기후변화 시나리오에 대응할 수 있는 탄력성 있는 수자원전문가시스템의 개발을 통해 이상기후 및 가뭄대비 물분쟁에 대한 합리적 대안을 제시하고자 한다. 본 연구에서는 섬진댐의 상황을 모델로 하고 있다. 섬진강 유역은 섬진강댐의 건설당시 발 빠른 이주대책의 불이행으로 수몰지역 내에 초기 정착민들이 계속 거주하게 되어 댐 제원을 충분히 활용하지 못하고 있어 효과적인 치수사업에 어려움을 겪어오다가 공사간의 협력을 통해 치수능력증대사업을 추진하여 저수지의 저류량을 증가시키고자 섬진강댐 재개발 사업을 추진한 지역이다. 하지만, 유역내의 이상기후로 인한 수문학적인 변동과 가뭄으로 인한 물관련 당사자간의 용수확보분쟁의 소지가 있어 물관리를 위한 수자원전문가시스템의 개발이 시급한 실정인 지역이기도 하다. 대상지역 수자원전문가시스템의 개발을 목표로 HSPF(Hydrologic Simulation Program with FORTRAN)을 이용하여 기후변화로 인한 수문학적 변동성을 파악하였다. 그리고 수자원 전문가 모델로서 외국에서 사용되고 있는 SUPER, HEC-ResSim, RiverWare, MODSIM, WRAP, PowerSim, 그리고 STELLA의 장 단점 등 특성을 분석하여 국내에 적합한 수자원전문가시스템 갖추어야할 기능 및 구성을 분석하였다. 연구 결과 국내실정에 필요한 모델은 공영시각모형(Shared Vision Model)으로서 그 장점은 첫째, 수자원의 관리나 물분쟁시 반드시 필요한 유역의 물리적인 인자와 수역관리에 필요한 수문인자, 그리고 물분쟁의 소지가 있는 의문사항이나 문제점의 해결책을 위한 실마리를 제공할수 있다. 둘째, 물관련 이해당사자들이 직접 참여하여 모형을 평가하고 서로간의 이해관계를 위한 충돌이 발생했을 때 문제해결을 위한 대안을 제시할 수 있는 정보를 제공할 수 있다. 셋째, 물배분의 원칙에 따른 한쪽으로 편중된 대안이 제시되었을 경우에 공동으로 대안에 대한 평가를 통하여 평등한 물배분을 가능하게 한다. 넷째, 시민단체나 환경단체, 그리고 기관책임자들이 공동으로 모형의 형성과정을 지켜본 후 논의할 수 있어 이상적인 모형을 만들 수 있는 장점이 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1097-1104
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• 2010

This paper presents the signal-to-noise ratio (SNR) and signal-to-interference plus noise ratio (SINR) estimation based on A-Preamble of IEEE 802.16m IMT-Advanced WiMax system with simulation results. The downlink signal of IEEE 802.16m has two kinds of A-Preambles: the PA-Preamble and the SA-Preamble. This paper proposes the effective method of estimating SNR and SINR with A-Preambles, and also shows that this method can recognize the ICI(Inter-Carrier-Interference) occurrence due to doppler frequency. With the recognition of ICI, the mobile station can save the power by operating 1-tap equalizer in usual cases, and activating ICI mitigation module only when it perceives the ICI occurrence.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2C
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• pp.238-245
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• 2010

For orthogonal frequency division multiplexing (OFDM) systems sharing the spectrum with narrow band primary devices, a fractional bandwidth (FBW) mode has been proposed recently to reduce the interference to the primary users. The FBW mode divides the total OFDM bandwidth into subbands and activates (or deactivates) a subset of the subbands according to the result of spectrum sensing. In this paper, we analyze the detection error probability of FBW mode information which is delivered by the sequence embedded in the preamble and evaluate the performance in wireless regional area network environments. The results show that the detection probability derived analytically estimates the actual value from simulation adequately and that a low detection error probability less than $10^{-3}$ is obtained at a low signal-to-noise power ratio.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.7
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• pp.574-581
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• 2012

Because of the exposed blade, the UAV using the rotors entail the risks during operation. While a wrapped duct around the fan blades reduces risks, it is a higher thrust performance than the same power load rotor. In this paper, for applying advantages of a ducted fan, the tri-ducted fan air vehicle configuration is proposed. The vehicle has three ducted fans. Two of them are the same shape and size and the third one is the smaller. It is possible to control a rapid attitude stability using thrust vector control. The equations of motion of the tri-ducted fan were derived. Lyapunov control input was applied to the system and stable inputs were derived. A nonlinear simulation was fulfilled by using parameters of a prototype vehicle. It verified a stable attitude and analyzed results.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.2
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• pp.157-168
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• 2016

Radioactive waste container designs should comply with the requirements for safety (i.e., transportation, storage, disposal) and other criteria such as economics and technology. These criteria are also applicable to the future management of the large amount of LLW and VLLW to arise from decontamination and decommissioning (D&D) of nuclear power plants, which have different features compared to that of wastes from operation and maintenance (O&M). This paper proposes to develop a set of standard containers of multi-purpose usage for transportation, storage and disposal. The concepts of the containers were optimized for management of D&D wastes in consideration of national system for radioactive waste management, in particular the Gyeongju Repository and associated infrastructures. A set of prototype containers were designed and built : a soft bag for VLLW, two metallic containers for VLLW/LLW (a standard IP2 container for sea transport and ISO container for road transport). Safety analyses by simulation and tests of these designs show they are in compliance with the regulatory requirements. A further development of a container with concrete is foreseen for 2016.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.640-652
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• 2012

Many studies have investigated the smart grid architecture and communication models in the past few years. However, the communication model and architecture for a smart grid still remain unclear. Today's electric power distribution is very complex and maladapted because of the lack of efficient and cost-effective energy generation, distribution, and consumption management systems. A wireless smart grid communication system can play an important role in achieving these goals. In this paper, we describe a smart grid communication architecture in which we merge customers and distributors into a single domain. In the proposed architecture, all the home area networks, neighborhood area networks, and local electrical equipment form a local wireless mesh network (LWMN). Each device or meter can act as a source, router, or relay. The data generated in any node (device/meter) reaches the data collector via other nodes. The data collector transmits this data via the access point of a wide area network (WAN). Finally, data is transferred to the service provider or to the control center of the smart grid. We propose a wireless cooperative communication model for the LWMN.We deploy a limited number of smart relays to improve the performance of the network. A novel relay selection mechanism is also proposed to reduce the relay selection overhead. Simulation results show that our cooperative smart grid (coopSG) communication model improves the end-to-end packet delivery latency, throughput, and energy efficiency over both the Wang et al. and Niyato et al. models.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8A
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• pp.827-835
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• 2007

In this paper, the extension method of data transmission range as adapting AAS(Adaptive Antenna Systems) in ECMA(European Computer Manufacturers Association) standard MB-OFDM(MultiBand-Orthogonal Frequency Division Multiplexing) UWB systems is proposed, and the complementary beamforming method which can solve hidden beam problem when we adapt AAS in CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) systems is proposed. To design the complementary beamforming, Gram-Schmidt orthogonalization is utilized, whose beam pattern exhibits perfect nulling at the main beam angles and provides uniform power for detection of channel utilization out of main beam. The proposed method can be utilized with any arbitrary beamforming when we make main beamforming. Through computer simulation, it can be shown that proposed AAS and complementary beamforming increase data transmission range from 2m to 3.95m in 480Mbps data transmission system and increase throughput about 20% as compared with general UWB AAS systems.