• 제어로봇시스템학회논문지
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• 제12권7호
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• pp.621-630
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• 2006

The T-50 advanced trainer aircraft combines advanced aerodynamic features and a fly-by-wire flight control system in order to produce a stability and highly maneuverability. The flight control system both longitudinal and lateral-directional axes to achieve performance enhancements and improve stability. The T-50 employs the RSS concept in order to improve the aerodynamic performance in longitudinal axis and the longitudinal control laws employ the dynamic inversion with proportional-plus-integral control method. And, lateral-directional control laws employ the blended roll system both beta-betadot feedback and simple roll rate feedback with proportional control method in order to guarantee aircraft stability. This paper details the design process of developing lateral-directional control laws, utilizing the requirement of MIL-F-8785C and MIL-F-9490D. And, this paper propose the analysis of aircraft characteristics such as dutch-roll mode, roll mode, spiral mode, gain and phase margin about gains for lateral-directional inner loop feedback.

• Asian-Australasian Journal of Animal Sciences
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• 제14권9호
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• pp.1245-1249
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• 2001

A study was conducted with 14 gayals to study their growth pattern from birth to 24 months of age, and gayal was compared with native calves and crossbred calves of gayals and exotic animals. A significant difference in liveweight gains up to 3 months (p<0.001) or up to 6 months (p<0.05) was found between gayal and native calves, but the difference reduced with increase of age and found non-significant (p>0.05) at 9 months and 12 months. The daily liveweight gain up to 3, 6, 9 or 12 months of age of gayals were 404.60, 306.80, 315.20 and 312.20 g/d, respectively and of native calves were 217.3, 245.3, 262.0 and 269.0 g/d, respectively. Gayal female calves had lower weights at birth (20.2 kg) and weaning (81.8 kg) and daily liveweight gains (298.5 g/d) than males (24.3 kg, 84.0 kg and 317.8 g/d, respectively) but the differences were not significant (p>0.05). Cross breeding gayal cows with Friesian bulls increased daily liveweight gain of the crossbred calves. The rate of increase of daily liveweight gain may further be increased if gayals are crossed with beef type animals, and optimum feeding may also be required which needs further research.

• 한국통신학회논문지
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• 제21권8호
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• pp.2003-2012
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• 1996

The 16- and 32-state Trellis-coded M-ary 4-dimensional (4-D) orthogonal modulation scheme with a frequency-reuse technique have been investigated. Here, 5 coded bits form a rate 4/5 convolutional encoder provide 32 possible symbols. Then the signals are mapped by a M-ary 4-D orthogonal modulator, where each signal has equal energy and is PSK modulated. In the M-ary 4-D modulator, we have employed the vectors which is derived by the optimization technique of signal waveforms in a 4-D sphere. This technique is usedin maximizing the minimum Euclidean distance between a set of signal poits on a multidimensional sphere. By combinig trellis coding with M-ary 4-D modulation and proper set-partitioning, we have obtained a considerable impeovement in the free minimum distance of the system over an AWGN channel. The 16-state scheme obtains coding gains up to 5.5 dB over the uncoded two-independent QPSK scheme and 2.5 dB over the two-independent 2-D TCM scheme. And, the 32-state scheme obtains coding gains up to 6.4 dB over the uncoded two-independent QPSK schemeand 3.4 dB over the two-independent 2-D TCM scheme.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.384-386
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• 2003

Striking in change that present our country is much by electricity industry reform and the Korea Electric Power Corporation is deciding power distribution system reliability indices every year but power distribution system for reliability evaluation and establishment of investment program are consisting punily. If consider efficient inflection of resources and hereafter power distribution division that is limited for target achievement of schedule level service evaluation and reliability side in operation of the power distribution system, can expect efficient practical use of the power distribution property if gains in electrical side about these change and most suitable investment way consist because there is necessity of electric power plan establishment of area electric power distribution place of business unit. This paper consider proper reliability level and maximum effect through quantitative analysis to gain electrical gains of the power distribution system in reliability side depending on trend DB(Data Base) of data of electric power system composition appliance in this treatise and apply data administration and reliability rate analysis that serve to decide most suitable investment precedence to supply of electric power property to power distribution system present investment algorithm.

• 한국통신학회논문지
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• 제30권7C호
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• pp.617-623
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• 2005

본 논문은 QAM 변조방식과 준정지 Rayleigh 페이딩 채널 환경에서 3개의 송신 안테나를 사용할 경우 추가로 주파수 대역을 사용하지 않고 최대 다이버시티 이득을 획득하는 새로운 시공간블록부호들을 제안한다. 이 제안된 부호들은 기존의 A-ST-CR 부호와 같이 성상 회전 선부호기와 Alamouti 부호를 적절히 직렬 연접하여 구성된다. 전산 실험 결과, 이 부호들은 모두 기존의 ST-CR 부호보다 높은 코딩 이득을 획득하고, 특히 제안된 부호들 중 가장 좋은 성능을 보이는 부호는 QPSK와 16-QAM 변조방식을 사용할 경우 평균 심벌오율 10$^{-5}$에서 기존의 ST-CR 부호에 대하여 각각 약 1.5dB와 3dB 코딩 이득의 성능 향상을 보인다.

• Journal of Communications and Networks
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• 제18권2호
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• pp.162-172
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• 2016

The placement of the complete baseband processing in a centralized pool results in high data rate requirement and inflexibility of the fronthaul network, which challenges the energy and cost effectiveness of the cloud radio access network (C-RAN). Recently, redesign of the C-RAN through functional split in the baseband processing chain has been proposed to overcome these challenges. This paper evaluates, by mathematical and simulation methods, different splits with respect to network level energy and cost efficiency having in the mind the expected quality of service. The proposed mathematical model quantifies the multiplexing gains and the trade-offs between centralization and decentralization concerning the cost of the pool, fronthaul network capacity and resource utilization. The event-based simulation captures the influence of the traffic load dynamics and traffic type variation on designing an efficient fronthaul network. Based on the obtained results, we derive a principle for fronthaul dimensioning based on the traffic profile. This principle allows for efficient radio access network with respect to multiplexing gains while achieving the expected users' quality of service.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.56-64
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• 2015

This study presents a model-based gain scheduling strategy for PI-based EGR controllers. The air-to-fuel ratio is used as an indirect measurement of the EGR rate. In order to cope with the nonlinearity and parameter varying characteristics of the EGR system, we proposed a static gain model of the EGR system using a new scheduling parameter. With the 810 steady-state measurements, the static gain model achieved 0.94 of R-squared value. Based on the static gain of the EGR system, the PI gains were robustly designed using quantitative feedback theory. Consequently, the gains of the PI controller are scheduled according to the static gain parameter of the EGR path in runtime. The proposed model-based gain scheduling strategy was validated through various operating conditions of engine experiments such as setpoint step responses and disturbance rejections.

• 수산해양기술연구
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• 제59권2호
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• pp.145-154
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• 2023

In this study, to control the heading angle of a ship, which is constantly subjected to various internal and external disturbances during the voyage, an LADRC (linear active disturbance rejection control) design that focuses more on improving the disturbance removal performance was proposed. The speed rate of change of the ship's heading angle due to the turn of the rudder angle was selected as a significant factor, and the nonlinear model of the ship's maneuvering equation, including the steering gear, was treated as a total disturbance. It is the similar process with an LADRC design for the first-order transfer function model. At this time, the gains of the controller included in LADRC and the gains of the extended state observer were tuned to RCGAs (real-coded genetic algorithms) to minimize the integral time-weighted absolute error as an evaluation function. The simulation was performed by applying the proposed GA-LADRC controller to the heading angle control of the Mariner class vessel. In particular, it was confirmed that the proposed controller satisfactorily maintains and follows the set course even when the disturbances such as nonlinearity, modelling error, uncertainty and noise of the measurement sensor are considered.

• 전자공학회논문지
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• 제53권6호
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• pp.21-28
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• 2016

본 논문은 수중 음파 센서 네트워크의 패킷 전송률을 높이고 에너지 소모량을 줄이기 위한 협력 전송 기법을 제안한다. 제안하는 기법은 각 노드에서 가상 안테나 배열이라고 부르는 분산 안테나들이 같은 패킷들을 전송하고, 수신노드에서는 수신된 패킷들을 결합하여 패킷 손실률을 낮춘다. 따라서 높은 전송 손실, 전파 지연 및 주위 잡음과 같은 수중 채널의 고유 특성을 고려한 채널 특성 기반의 협력 전송 기법은 중계노드들을 통한 높은 다이버시티 이득을 제공하여 수중 음파 센서 네트워크의 신뢰성을 향상시킨다. 또한 송신노드에서 채널 상태, 거리 비용, 각 노드 당 남은 에너지를 고려하여 이웃노드들 중에서 목적지와 중계노드를 선택하는 알고리즘을 제안한다. 모의실험 결과는 OPNET Moduler를 통해 제안된 방법의 평균 에너지 소비, 패킷 전달 비율, 응답 시간 측면에서 비-협력 기법 및 SPF(Shortest Path First) 기법보다 향상된 성능을 보여준다.

• 환경정책연구
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• 제2권2호
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• pp.41-63
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• 2003

CDM(Clean Development Mechanism) project is said to be a mechanism, which profits both the investing country and the host country, while additionally contributing to the reduction of greenhouse gases of the earth as a whole. However in reality, most of the proposed projects do not end up in agreement because of the problems related to differences in recognition between the investing country and the host country of the CDM project. This outlines the background for this research which proposes a new design of institutional arrangements of CDM projects in the Northeast Asian region, mainly Japan, China and Korea. In addition, we investigate the feasibility of the proposed design. The research firstly focuses on the reduction in transaction costs that the participation of Korea will have on a Japan-China CDM project. This paper further emphasizes the potential gains that would materialize if a CDM project involved the whole Northeast Asian region, and not only one country. Our research suggests that an approximate reduction of 23% in transaction costs, and about 4% reduction in the total costs of a CDM project can be expected to follow the Korean participation. In addition to decreasing costs we find that a Korean involvement in a CDM project with Japan will lead to efficiency gains illustrated by a higher increase in the IRR(Internal rate of return) in a Japan-Korea project(11.45% to 12.21%) compared to an IRR incresement of 10.57% to 11.27% for a pure Japanese CDM project. Similar results of a rise in the IRR is found for the whole investment period of 20 years. We can hence conclude that Korean participation in a Japan-China CDM project would improve the implementation possibilities of CDM project in the Northeast Asia region.