• 한국항해학회지
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• 제18권3호
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• pp.19-30
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• 1994

By use of the recent tropical cyclones' data in the Northwest Pacific Ocean, the occurrence frequency and region of typhoon as well as the features of the monthly mean track were analyzed. As the result of this study, (1) mean occurrence frequency of typhoon per year is 27.5, and 68% of total typhoons were formed in July to October and shown the highest frequency in August. (2) The ave-rage duration of typhoons is 8.5 days, and super typhoon which maximum sustained surface wind speeds is more than 130 knots occurs most frequently in October and November. (3) The highest frequency ap-pears around the Caroline, Mariana and Marshall Islands, and in wintertime, typhoon occurs in lower lati-tude comparing with those in summertime. (4) The typhoon track depends upon the distribution of pres-sure system and steering current in neighbouring areas. The mean track of typhoon can be classified into three types such as westward-moving type, northward-moving type and abnormally moving type. The west-ward-moving typhoons make landfall on the southern China by way of the South China Sea in June and July, on mid-part of China in August and September, and on Indo-china Peninsula in October and Novem-ber. The northward-moving typhoons approximately move on north~northwestward track to $20~30^{\circ}N$ from the occurrence region, then recurve to the East Sea through Korean Peninsula and Kyushu Island in June and July, to the Noth Pacific Ocean along the Japanese Islands in August and September and to the North Pacific Ocean through the seas far south off the Japan in October and November.

• 한국기계가공학회지
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• 제12권1호
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• pp.70-76
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• 2013

Recently, the performance and function of electrical and electronic system in automotive vehicles is developing at a rapid rate with the advancement of IT technologies. Combined together with micro-controller and sensor technologies, the Vehicle Smart System (VSS) being developed to improve driver's convenience and comfort has been employed to a variety of applications. In addition to the convenience system, the Auto-parking Assistance System (AAS) that is now attracting a new attention has been already applied to some vehicles, but it is currently limited to luxury car models only. In this paper, we present a fuzzy controller that enables autonomous parking assistance without the AAS. The controller can perform the assistance with information provided from moving status, current position and steering angle as one is able to park a car based on his/her experience and knowledge for driving and parking. We have evaluated its performance of the proposed controller by simulation and tested the excellence of the controller by building a model vehicle embedded with the micro-controllers.

• 한국항공우주학회지
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• 제37권12호
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• pp.1217-1224
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• 2009

고정익 항공기가 3차원의 복잡한 경로를 추종하기 위해 필요한 비교적 간단하며 효과적인 유도 제어 방법을 제시한다. 소개되는 방법은 비선형 경로 추종 유도 기법을 외부 루프로 사용한다. 외부 루프는 원하는 경로와 함께 항공기의 현재 위치와 속도를 바탕으로 비행 경로를 변화하기 위한 가속도 명령을 생성한다. 가속도 명령은 중력과 벡터적으로 결합되어 Specific Force Acceleration을 만든다. 이렇게 생성된 Specific Force Acceleration은 내부 루프를 위한 명령으로 쓰이는데, 이는 항공기가 가속도 자체보다는 Specific Force Acceleration을 더 직접적으로 제어할 수 있기 때문이다. 나아가 배면 비행이나 Slow Roll, Knife-Edge 등과 같은 옆미끄럼짐 기동을 하기 위해 필요한 롤 자세 제어 기법도 제시한다. 마지막으로 표준이 되는 여러 가지 곡예비행 경로들에 대한 시뮬레이션을 수행함으로써 제시된 기법의 성능을 검증한다.

• 한국항해항만학회지
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• 제35권5호
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• pp.359-363
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• 2011

본 연구에서는 만타 형상을 가진 무인잠수정(Manta-type unmanned underwater test vehicle)의 제어 성능 평가를 수행 하였다. 제어 방법으로서 PID제어, Fuzzy 제어가 적용되었으며, 6자유도 운동 수학모델과 Matlab Simulink을 이용하여 조종 운동 시뮬레이션을 수행하였다. 또한, 설계된 제어기로 수심제어 및 방위제어에 적용하여, 조류의 외란 하에서 제어 성능을 평가하였다.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.80-86
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• 2020

Autonomous driving is one of the most important new technologies of our time; it has benefits in terms of safety, the environment, and economic issues. Path following algorithms, such as automated lane keeping systems (ALKSs), are key level 3 or higher functions of autonomous driving. Pure-Pursuit and Stanley controllers are widely used because of their good path tracking performance and simplicity. However, with the Pure-Pursuit controller, corner cutting behavior occurs on curved roads, and the Stanley controller has a risk of divergence depending on the response of the steering system. In this study, we use the advantages of each controller to propose a hybrid control strategy that can be stably applied to complex driving environments. The weight of each controller is determined from the global and local curvature indexes calculated from HD map information and the current driving speed. Our experimental results demonstrate the ability of the hybrid controller, which had a cross-track error of under 0.1 m in a virtual environment that simulates K-City, with complex driving environments such as urban areas, community roads, and high-speed driving roads.

• Current Optics and Photonics
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• 제7권2호
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• pp.157-165
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• 2023

We propose a highly directional waveguide grating antenna for an optical phased array, achieving high directionality of more than 97% by interleaving the trenches with different etching depths in the silicon nitride layer, and adopting a multilayered structure. Meanwhile, the multilayered structure reduces the perturbation strength, which enables a centimeter-scale radiation length. The beam-steering range is 13.2°, with a wavelength bandwidth of 100 nm. The 1-dB bandwidth of the grating is 305 nm. The multilayered grating structure has a large tolerance to the fabrication variation and is compatible with CMOS fabrication techniques.

• 한국전자파학회논문지
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• 제26권3호
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• pp.300-304
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• 2015

본 논문에서는 무선전력전송용 전 방향 빔 조향 직교 공진기를 제안하였다. 전 방향 빔 조향 직교 공진기는 2개의 루프를 수직으로 교차하여 이들의 연결 관계를 스위치로 제어하는 방식이다. 스위치의 연결 방식에 따라 루프에 흐르는 전류의 방향이 결정되고, 그에 따라 빔 조향 방향이 결정된다. 수직으로 교차한 공진기의 전류와 그에 따라 형성되는 자기장의 벡터 합의 원리를 이용하여 대각선 방향으로의 빔 조향을 실현하였다. 4개의 스위치 mode를 통해서 총 8개 방향으로 빔 조향이 가능하다. 적합한 스위치 mode를 사용하여 전 방향에 대한 전송 효율을 구하면 시뮬레이션과 측정 결과가 각각 56.3~60.0 %(편차 3.7 %), 41.2~48.7 %(편차 7.5 %)으로 비교적 전 방향에 대해 균일한 전송 효율을 얻을 수 있다.

• 대한기계학회논문집A
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• 제29권3호
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• pp.395-402
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• 2005

Recently Multidisciplinary Design Optimization Based on Independent Subspaces (MDOIS), an MDO (multidisciplinary design optimization) algorithm, has been proposed. In this research, an MDO problem is defined for design of a belt integrated seat considering crashworthiness, and MDOIS is applied to solve the problem. The crash model consists of an airbag, a belt integrated seat (BIS), an energy absorbing steering system, and a safety belt. It is found that the current design problem has two disciplines - structural nonlin- ear analysis and occupant analysis. The interdisciplinary relationship between the disciplines is identified and is addressed in the system analysis step in MDOIS. Interdisciplinary variables are belt load and stiffness of the seat, which are determined in system analysis step. The belt load is passed to the structural analysis subspace and stiffness of the seat back frame to the occupant analysis subspace. Determined design vari- ables in each subspace are passed to the system analysis step. In this way, the design process iterates until the convergence criterion is satisfied. As a result of the design, the weight of the BIS and Head Injury Crite- rion (HIC) of an occupant are reduced with specified constraints satisfied at the same time. Since the system analysis cannot be formulated in an explicit form in the current example, an optimization problem is formu - lated to solve the system analysis. The results from MDOIS are discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권12호
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• pp.5842-5861
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• 2019

A current autonomous vehicle determines its driving strategy by considering only external factors (Pedestrians, road conditions, etc.) without considering the interior condition of the vehicle. To solve the problem, this paper proposes "An Optimal Driving Support Strategy(ODSS) based on an Genetic Algorithm for Autonomous Vehicles" which determines the optimal strategy of an autonomous vehicle by analyzing not only the external factors, but also the internal factors of the vehicle(consumable conditions, RPM levels etc.). The proposed ODSS consists of 4 modules. The first module is a Data Communication Module (DCM) which converts CAN, FlexRay, and HSCAN messages of vehicles into WAVE messages and sends the converted messages to the Cloud and receives the analyzed result from the Cloud using V2X. The second module is a Data Management Module (DMM) that classifies the converted WAVE messages and stores the classified messages in a road state table, a sensor message table, and a vehicle state table. The third module is a Data Analysis Module (DAM) which learns a genetic algorithm using sensor data from vehicles stored in the cloud and determines the optimal driving strategy of an autonomous vehicle. The fourth module is a Data Visualization Module (DVM) which displays the optimal driving strategy and the current driving conditions on a vehicle monitor. This paper compared the DCM with existing vehicle gateways and the DAM with the MLP and RF neural network models to validate the ODSS. In the experiment, the DCM improved a loss rate approximately by 5%, compared with existing vehicle gateways. In addition, because the DAM improved computation time by 40% and 20% separately, compared with the MLP and RF, it determined RPM, speed, steering angle and lane changes faster than them.

• 대한전자공학회논문지SD
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• 제43권12호
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• pp.15-22
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• 2006

본 논문에서는 UWB(Ultra Wide Band)통신시스템을 위한 1.8V 8-bit 500MSPS의 D/A 변환기를 제안한다. 전체적인 D/A 변환기의 구조는 높은 선형성과 낮은 글리치 특성을 갖는 상위 6-MSB(Most Significant Bit) 전류원 매트릭스(Current Cell Matrix)와 하위 2-LSB(Least Significant Bit) 전류원 매트릭스로 구성된 2단 매트릭스 구조로 설계하였다. 또한 동일한 지연시간을 갖는 Thermometer Decoder와 고속 동작에서 전력을 최소화하기 위한 저 전력 스위칭 디코더(Current Switching Decoder Cell)를 제안함으로서 D/A 변환기의 고속 동작에서 성능을 향상시켰다 설계된 DAC는 1.8V의 공급전압을 가지는 TSMC $0.18{\mu}m$ 1-poly 6-metal N-well CMOS 공정으로 제작되었으며, 제작된 D/A 변환기의 측정결과, 매우 우수한 동적성능을 확인하였다. 500MHz 샘플링 클럭 주파수와 50MHz의 출력신호에서 SFDR은 약 49dB, INL과 DNL은 각각 0.9LSB, 0.3LSB 이하로 나타났으며, 이 때의 전력소비는 약 20mW로 기존의 8-bit D/A변환기에 비해 매우 낮음을 확인 할 수 있었다 D/A 변환기의 유효 칩 면적은 $0.63mm^2(900um{\times}700um)$이다.