• International Journal of Aeronautical and Space Sciences
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• 제17권2호
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• pp.222-231
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• 2016

This paper proposes a new method achieving computationally efficient attitude reference system for low cost strapdown sensors and microprocessor platform. The main idea in this method is to define and compare velocity differential vectors, geometrically computed from INS and GPS data with different update rate, for generating attitude error measurements which is further used for filter construction. A quaternion based Kalman filter configuration is applied for the attitude estimation with the adapted measurement model of differential vector comparison. Linearized model for Extended Kalman Filter and low pass filtered characteristics of measurement greatly extend the affordability of the proposed algorithm to the field of simple low cost embedded systems. For performance verification, experiment are done employing a practical low cost MEMS IMU and GPS receiver specification. Performance comparison with a high grade navigation system demonstrated good estimation result.

• 복식문화연구
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• 제23권2호
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• pp.176-192
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• 2015

This work aims at analyzing the comparative feature about female flight attendant uniform designs of Korean and Asian region low cost carriers and providing some basic materials for development of these airline companies. As a research method, examinations were carried out on attendant's uniform both theoretically and empirically. Comparison of uniforms was made among the five Korean carriers and ten typical Asian carriers for empirical research. Results showed the followings. First, all Korean low cost carriers were characterized as formal style except Jin Air. Unlike this, Asian low cost carriers appeared as diverse including formal, semi formal, and casual styles with a uniquely differentiated image. Second, all carriers applied their own symbolic color to their uniform. Third, logo or symbol was adopted as a pattern on scarf in the two Korean companies but it didn't take effect practically. For those Asian carriers, embroidery was used on jacket, jumper and collar. They utilized even a merchandising character to put emphasis on airline image. Fourth, diverse petty items with a decorative effect were used in the case of Korean low cost carriers. In the changing period of uniform, nothing much was changed and remained almost the same as before. Those in the Asian region were characterized with the smallest number of items and the preclusion of decorative add-ons on uniform.

• 제어로봇시스템학회논문지
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• 제13권7호
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• pp.637-648
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• 2007

This paper presents a sensor fusion method based on indirect Kalman filter(IKF) for error compensation of low-cost inertial sensors and its application to the determination of attitude and position of small flying robots. First, the analysis of the measurement error characteristics to zero input is performed, focusing on the bias due to the temperature variation, to derive a simple nonlinear bias model of low-cost inertial sensors. Moreover, from the experimental results that the coefficients of this bias model possess non-deterministic (stochastic) uncertainties, the bias of low-cost inertial sensors is characterized as consisting of both deterministic and stochastic bias terms. Then, IKF is derived to improve long term stability dominated by the stochastic bias error, fusing low-cost inertial sensor measurements compensated by the deterministic bias model with non-inertial sensor measurement. In addition, in case of using intermittent non-inertial sensor measurements due to the unreliable data link, the upper and lower bounds of the state estimation error covariance matrix of discrete-time IKF are analyzed by solving stochastic algebraic Riccati equation and it is shown that they are dependant on the throughput of the data link and sampling period. To evaluate the performance of proposed method, experimental results of IKF for the attitude determination of a small flying robot are presented in comparison with that of extended Kaman filter which compensates only deterministic bias error model.

• 한국항공우주학회지
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• 제46권5호
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• pp.436-444
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• 2018

본 연구의 목적은 국내 저가항공사의 노선 효율성을 평가하는 데 있다. 저가 항공사의 경우 정규 항공사와 달리 국내선과 근거리 국제선만을 운영하고 있어서 매출수익의 원천이 정규항공사에 비해서 다양하지 않다. 특히, 국내 저가 항공사의 경우 화물운송 없이 여객운송과 부가서비스를 통하여 매출수익을 올리고 있다. 때문에 저비용 고효율의 여객운송 노선을 유지하는 것이 절대적으로 중요하다. 이를 위해 본 연구에서는 국내 저비용 항공사가 운영하는 노선과 정규 항공사의 노선들의 상대적 효율성을 평가하고, 평가한 효율성을 바탕으로 노선 효율성을 개선할 수 있는 방안을 제시하였다. 분석 방법은 자료포락법(DEA)을 사용하였고, 기존 문헌연구를 통하여 투입과 산출 요소를 선정하였다. 본 연구의 결과를 기반으로 항공사의 노선 및 판매 전략 수립에 도움을 줄 수 있을 것으로 판단한다.

• 한국태양에너지학회 논문집
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• 제34권2호
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• pp.24-31
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• 2014

So many energy saving strategies to realize the low energy house are proposed in these days. Even if the energy saving performances are similar between the strategies, the costs are in abroad ranges. Therefore, the application of the energy saving strategies should be based upon two considerations; one is energy saving performance and the other is the cost. In this study, the decision making method for application of the passive design technologies in the design stage of the low energy apartment house are suggested. By utilizing the result of this study, practitioners can make an effective design alternatives which solve the conflicted values; energy saving and cost.

• Journal of Information Processing Systems
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• 제14권3호
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• pp.600-606
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• 2018

Smart city is currently the main direction of development. The automatic management of instrumentation is one task of the smart city. Because there are a lot of old instrumentation in the city that cannot be replaced promptly, how to makes low-cost transformation with Internet of Thing (IoT) becomes a problem. This article gives a low-cost method that can identify code wheel instrument information. This method can effectively identify the information of image as the digital information. Because this method does not require a lot of memory or complicated calculation, it can be deployed on a cheap microcontroller unit (MCU) with low read-only memory (ROM). At the end of this article, test result is given. Using this method to modify the old instrumentation can achieve the automatic management of instrumentation and can help build a smart city.

• 한국도로학회논문집
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• 제11권1호
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• pp.59-67
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• 2009

센싱 기술의 발달로 다양한 종류의 매체를 이용한 우수한 차량 검지장비들이 개발되고 있는 요즘, 간단한 구조의 저가형 검지장비 또한 적은 예산으로 여러 곳에 설치할 수 있다는 장점 때문에 지속적인 연구가 이루어지고 있다. 본 연구에서는 저가형 차량 검지장비로서 센서를 사선으로 설치하여 좌우 및 전후 바퀴의 통과시간 간격과 차량의 윤거값을 적용하여 차량속도를 추정하는 방법을 제안하였다. 출고된 차량의 제원조사에서 얻어진 대표 윤거값을 축거와 뒤윤거의 비율에 따라 소형과 대형 차량으로 구분하여 적용하므로 기존의 연구보다 정확한 속도추정이 가능하도록 개선하였다. 특히, 소형과 대형차량을 구분하는 파라미터를 통하여 조사지점의 차종구성 비율을 고려한 정확도 보정이 가능하다. 간단하고 저가로 개발된 본 연구의 사선형 센서를 이용한 검지장비는 적은 비용으로 교통상황을 설명하는데 효율적으로 활용될 것으로 기대된다.

• 전자공학회논문지B
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• 제32B권10호
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• pp.1338-1346
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• 1995

In this paper, we suggest the implementation of a DGPS system using two low cost commercial C/A code GPS modules and modems and its efficient operational techniques to provide DGPS service which guarantees the position accuracy of better than 10 meters for more users. The proposed DGPS system can be implemented easil at low cost because it needs a GPS module and a modem for each reference station and user. The reference station makes plans of the receiving schedule from the satellite set at each period and then provides the correction data for various satellite sets in a period. The main contribution of this paper is that users can utilize the correction data continuously and efficiently through the recursive least squares lattice filtering method. Experimental results show the position accuracy of better than 10 meters using the suggested DGPS system in almost real time.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 추계학술대회 논문집
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• pp.5-6
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• 2012

In this paper, a simplified maximum power point tracking technique for the solar charger is presented. Main advantages of the proposed charger include low cost and optimized charge time. The maximum power point tracking method is used to deliver the maximum power from PV array to the battery thereby reducing the charge time. Moreover, the proposed technique which tracks the maximum power point by adjusting output current helps reduce the quantity of required number of sensors for the charger. The experimental protype was implemented by using an 80W PV array, a buck converter and a digital signal processor to verify the feasibility of the proposed method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.451-454
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• 2002

In this paper, studied on the one-chip design of low cost for the micro-stepping drive having 5-phase Pentagon Type winding. Micro-stepping method in order to eliminate effectively the resonant phenomena and to Increase the positional resolution. This paper proposed trapezoidal current wave- form for current control and provided design- method by using only one-chip of low cost. Therefore the drive will be simple and small size. Also the drive will have a lot of advantage at commercial business. Finally the above study has been implemented on the VHDL. Simulation has been performed to verify the PWM for micro-stepping drive.