• 경영과학
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• 제18권2호
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• pp.125-134
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• 2001

This paper is concerned with the development of a GIS-based distribution system with service consideration. The proposed model could be used for a wide range of logistics applications in planning, engineering and operational purpose for logistics system. This research addresses the formulation of those complex prob1ems of two-echelon logistics system to plan the incorporating supply center locations and distribution problems based on GIS. We propose an integrated logistics model for determining the optimal patterns of supply centers and inventory allocations (customers) with a three-step sequential approach. 1) First step, Developing GIS-distance model and stochastic set-covering program to determine Optimel pattern of supply center location. 2) Second step, Optimal sector-clustering to support customers. 3) Third step, Optimal vehicle rouse scheduling based on GIS, GIS-VRP In this research we developed GUI-tree program, the GIS-VRP provide the vehicle to users and freight information in real time. We applied a set of sample examples to this model and demonstrated samp1e results. It has been found that the proposed model is potentially efficient and useful in solving multi-depot problem through examples. However the proposed model can provide logistics decision makers to get the best supply schedule.

• 한국군사과학기술학회지
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• 제13권5호
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• pp.933-940
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• 2010

A numerical analysis for the space frame structure under ballistic and blast loads was performed using LS-DYNA, a commercial code. The space frame structure was developed to be adapted to the ground vehicle in the future and it was designed to build with Al7039 frames and lightweight multi-layered panels for the purpose of weight reduction and shock mitigation. The analyses have done for side impacts by a cylindrical projectile and Comp. C-4 explosive representing major threats to the vehicle. The deformed shape of the panel section and stresses as well as accelerations of the frames calculated from LS-DYNA were compared to the test results to validate the analysis model. The internal energies for panels and frames from LS-DYNA were also compared to each other to discern their role in absorbing the ballistic and blast impact.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.307-310
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• 1997

In case of environment requiring safety such as human body and requiring flexible shape, a conventional mechanical actuator system does not satisfy requirement. Therefore, in order to solve this problem, a research of various smart material such as EAP (Electro Active Polymer), EAC (Electro Active Ceramic) and SMA (Shape Memory Alloy) is in progress. Recently, the highest preferring material among various smart material is EP (Electrostictive Polymer), because it has very fast response time, poerful force and large displacement. The previous researches have been studied properties of polymer and simple control, but present researches are studied a polymer actuator. An EP (Electostrictive Polymer) actuator has properties which change variably as shape and environmental condition. Therefore, in order to coincide with a user's purpose, it is important not only to decide a shape of actuator and mechanical design but also to investigate a efficient controller. In this paper, we constructed the control logic with an adaptive fuvy algorithm which depends on the physical properties of EP that has a dielectric constant depending on time.

• International Journal of Aeronautical and Space Sciences
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• 제11권4호
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• pp.285-302
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• 2010

Active aeroelastic control is an emerging technology aimed at providing solutions to structural systems that under the action of aerodynamic loads are prone to instability and catastrophic failures, and to oscillations that can yield structural failure by fatigue. The purpose of the aeroelastic control among others is to alleviate and even suppress the vibrations appearing in the flight vehicle subcritical flight regimes, to expand its flight envelope by increasing the flutter speed, and to enhance the post-flutter behavior usually characterized by the presence of limit cycle oscillations. Recently adaptive and robust control strategies have demonstrated their superiority to classical feedback strategies. This review paper discusses the latest development on the topic by the authors. First, the available control techniques with focus on adaptive control schemes are reviewed, then the attention is focused on the advanced single-input and multi-input multi-output adaptive feedback control strategies developed for lifting surfaces operating at subsonic and supersonic flight speeds. A number of concepts involving various adaptive control methodologies, as well as results obtained with such controls are presented. Emphasis is placed on theoretical and numerical results obtained with the various control strategies.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1534-1536
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• 2005

A DC-DC converter is being widely used for various household appliances and for industry applications. The DC-DC converter is powered from single battery, and the voltage is varied according to the purpose. In the vehicle, various accessories whose electric power is different are being used. Thus, plural number of DC-DC converter should be provided, so these situations bring complicated circuits, and accordingly, higher cost. Under such backgrounds, in this paper, we propose a novel buck-boost chopper circuit with simply configuration which can supply to two or more different output loads. The propose chewer circuit can control output voltages by controlling duty ratio by using typically two switching devices, which is composed by single boost-switch and single buck-switch. The output voltage can be controlled widely. A few modified circuits developed from the fundamental circuit are represented including the general multi-load circuit. And all this merits and appropriateness was proved by computer simulation and experience.

• 한국기계가공학회지
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• 제19권11호
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• pp.102-108
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• 2020

The demand for lightweight materials and high-strength steel has rapidly increased to help reduce the weight of a vehicle body; it improves the fuel efficiency of automobiles and provides passenger safety. Additionally, as the material becomes thinner, the demand for its resistance against corrosion becomes higher. Hence, the application of the surface-treated steel sheet has surged rapidly. In this study, a weld bonding experiment using a delta spot welding machine is performed on a thin sheet of a different material (Al6061-T6/GA440). The thickness of the material was kept at 1 mm to reduce the weight of the automobile body parts. Additionally, the purpose of this study is to control the heat input by applying the welding conditions of a multi-stage pressure pattern to improve corrosion resistance shear strength. The analysis of nugget diameter measurement, shear tensile test, and salt spray test was performed to achieve the aim.

• Journal of Biosystems Engineering
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• 제41권2호
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• pp.126-137
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• 2016

Purpose: The overall objective of this study was to evaluate the vegetation fraction of soybeans, grown under different cropping conditions using an unmanned aerial vehicle (UAV) equipped with a red, green, and blue (RGB) camera. Methods: Test plots were prepared based on different cropping treatments, i.e., soybean single-cropping, with and without herbicide application and soybean and barley-cover cropping, with and without herbicide application. The UAV flights were manually controlled using a remote flight controller on the ground, with 2.4 GHz radio frequency communication. For image pre-processing, the acquired images were pre-treated and georeferenced using a fisheye distortion removal function, and ground control points were collected using Google Maps. Tarpaulin panels of different colors were used to calibrate the multi-temporal images by converting the RGB digital number values into the RGB reflectance spectrum, utilizing a linear regression method. Excess Green (ExG) vegetation indices for each of the test plots were compared with the M-statistic method in order to quantitatively evaluate the greenness of soybean fields under different cropping systems. Results: The reflectance calibration methods used in the study showed high coefficients of determination, ranging from 0.8 to 0.9, indicating the feasibility of a linear regression fitting method for monitoring multi-temporal RGB images of soybean fields. As expected, the ExG vegetation indices changed according to different soybean growth stages, showing clear differences among the test plots with different cropping treatments in the early season of < 60 days after sowing (DAS). With the M-statistic method, the test plots under different treatments could be discriminated in the early seasons of <41 DAS, showing a value of M > 1. Conclusion: Therefore, multi-temporal images obtained with an UAV and a RGB camera could be applied for quantifying overall vegetation fractions and crop growth status, and this information could contribute to determine proper treatments for the vegetation fraction.

• 대한원격탐사학회지
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• 제35권5_2호
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• pp.841-850
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• 2019

본 논문은 상업용 소형 드론의 드론 맵핑 기하 정확도 평가와 지상 LiDAR와 드론 점군 자료의 융합을 통하여 재난 긴급 맵핑 적용성에 관한 연구이다. 기존의 드론 맵핑 절차와 카메라 검정과 광속조정법으로 카메라 모델을 최적화한 드론 맵핑 간의 위치 오차를 비교 분석한 결과, 평면 위치오차는 2~3 m에서 약 0.11~0.28 m 수준으로, 수직 위치오차는 2.85 m에서 0.45 m 수준으로 위치결정 정확도가 향상되었다. 아울러, 드론 맵핑과정에서 누락되기 쉬운 점군 자료의 측면정보를 지상 LiDAR 점군자료와 융합을 통해 보완할 수 있도록 두 점군 자료간 정합을 위한 개선된 좌표계 변환 모델을 제시하여 연구 대상지내 이종 점군 자료를 최대 오차 0.07 m 이내로 정합하였다. 본 논문에서의 재난현장에서의 드론 기반의 긴급 맵핑과 재난 현장정보를 보다 정밀하게 구축하기 위한 점군 자료융합에 관한 연구 성과는 향후 국가 재난안전 관리 현업에 일조할 수 있을 것으로 기대된다.

• 한국산업정보학회논문지
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• 제22권5호
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• pp.39-49
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• 2017

인공위성 발사를 위한 우주발사체는 효율적인 비행을 위하여 다단으로 구성이 되며 단분리, 연료점화 및 연소종료 등의 비행이벤트를 거쳐서 임무를 완수하게 된다. 이 과정에서 발사체는 추력이 발생하는 동력비행구간과 추력이 없는 탄도비행구간의 과정을 반복하여 겪게 된다. 이러한 우주 발사체의 비행특성을 하나의 동력학 모델로 표현하기는 어렵기 때문에 다중모델을 사용하는 추적 알고리즘에 대한 연구가 많이 진행되어 왔다. 다중모델 추적 알고리즘을 사용하는 경우에는 추적 성능의 개선을 기대할 수 있지만, 사용할 각 동력학 모델들을 적절히 선정해야 하는 어려움이 있으며 또한 다중모델 사용으로 인해 계산양이 증가하는 단점이 있다. 본 논문에서는 등가속도 모델과 적응형 Singer 모델을 사용하는 두 개의 칼만필터만으로 다양한 비행특성을 가지는 우주발사체를 효과적으로 추적하는 방법을 제안한다.

• 한국전자통신학회논문지
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• 제18권4호
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• pp.669-676
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• 2023

본 논문에서는 IR 레이저 센서 및 관성 센서를 이용한 골프 퍼팅 거리 측정을 위한 다목적 골프 퍼팅 거리 측정기를 설계, 제작하였다. 거리 측정기는 골프 퍼팅 거리 측정을 위해 실외 50m 측정 범위 내에서 거리 측정과 경사도 측정, 그리고 퍼팅에 영향을 미치는 온도 측정이 가능하도록 설계하였다. 또한, 실내 30m 측정범위 내에서 길이 및 수평도를 측정함으로써 실내 작업을 지원하며, 실내 온도 이상시 웹서버와의 연동을 통해 휴대폰 사용자에 경보를 제공함으로써 실내 또는 차량 화재로부터 안전이 확보될 수 있도록 하였다. 제안된 방법의 정확성과 스마트 폰과의 연동 성능을 평가하기 위해 하나의 시작품을 제작하고 웹서버를 구축하였으며, 반복적인 실험에서 허용 가능한 5%내의 오차율을 보임으로써 유용성을 확인할 수 있었다.