• 한국항공우주학회지
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• 제35권1호
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• pp.66-72
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• 2007

비행체 설계 접근 방법으로서 무선조종 모형시험 기법 적용 방안을 제시하였다. 본 연구에서 제시된 접근 방법은 동적 상사성을 유지한 축소모형 비행체의 비행특성 분석을 통하여 기본 설계 형상의 타당성을 확인하고 그 결과를 비행체 초기 설계 단계에서 공력 설계 절차에 반영하는 것이다. 축소 비행모형 설계 시 실제적 적용이 가능한 상사 법칙을 개발하기 위하여 비행체 운동을 조종안정성 상사를 위한 회전운동과 비행성능 상사를 위한 병진운동으로 분리하였다. 또한, 무선조종 모형 비행시험을 위한 세부 기법을 개발하였다. 무선조종 비행시험으로부터 얻은 결과를 기초로, 제시된 비행체 설계 접근 방법은 비행체 설계 초기 단계에서 설계 형상 타당성을 확인하는데 유용한 것으로 확인되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1333-1343
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• 2016

Spectrum sharing in centrally controlled cognitive radio (CR) networks has been widely studied, however, research on channel access for distributively controlled individual cognitive users has not been fully characterized. This paper conducts an analysis of random channel access of cognitive users controlled in a distributed manner in a CR network. Based on the proposed estimation method, each cognitive user can estimate the current channel condition by using its own Markov-chain model and can compute its own blocking probability, collision probability, and forced termination probability. Using the proposed scheme, CR with distributed control (CR-DC), CR devices can make self-controlled decisions based on the status estimations to adaptively control its system parameters to communicate better.

• 대한조선학회논문집
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• 제43권1호
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• pp.134-146
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• 2006

This paper presents the primary conceptual design results of twenty-passenger class Wing-In-Ground(WIG) effect craft. As a first step, top level requirements were proposed and principal dimensions were determined. Maximum speed in ground effect condition is 150 km/h with two tons payload including passengers. Total weight is estimated as 8.5 tons with 2 tons of thrust. Hull and airfoil sections were designed and self propulsion tests were performed by radio controlled model. Two planing hull forms with the transom stern were proposed and towing tests were performed. The resistance and running attitude were measured and the feasibility is checked for the prototype hull form of the twenty-passenger class WIG craft. The free running tests show the stable smooth running attitude at designed speed. Also this radio controlled model can take off around 0.15 meter wave height. It can be said that the top level requirement for the twenty passenger class WIG ship is satisfied successfully. The design optimization to increase the transport efficiency and safety will be performed in the near future.

• 반도체디스플레이기술학회지
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• 제4권2호
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• pp.11-14
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• 2005

In plasma processing reactors, it is common practice to control plasma density and ion bombardment energy by manipulating excitation voltage and frequency. In this paper, a dually excited capacitively coupled rf plasma reactor is self-consistently simulated with a three moment model. Effects of phase differences between primary and secondary voltage waves, simultaneously modulated at various combinations of commensurate frequencies, on plasma properties are investigated. The simulation results show that plasma potential and density as well as primary self-dc bias are nearly unaffected by the phase lag between the primary and the secondary voltage waves. The results also show that, with the secondary frequency substantially lower than the primary frequency, secondary self·do bias remains constant regardless of the phase lag. As the secondary frequency approaches to the primary frequency, however, the secondary self-dc bias becomes greatly altered by the phase lag, and so does the ion bombardment energy at the secondary electrode. These results demonstrate that ion bombardment energy can be more carefully controlled through plasma simulation.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.162-171
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• 1999

The most important part in automated transport systems is steering control for lane keeping Most of systems developed so far have used the visual information for steering control. In this study, the steering control algorithm based on visual servoing has been developed and tested by applying it on Radio Controlled(R/C) model car equipped with one CCD camera. We also demonstrated the feasibility of using it as a pre-test car before the real car experiment in developing automated vehicles. In order to solve the problem of the limited spave and load of a model car, remote-brained approach has been taken. For steering control of a model car, the PD controller which uses the look ahead offset to generate control input has been implemented and the characteristics of the controller has been explained in view of kinematics. Some experimental results have been also illustrated so as to show the control performance and stability.

• 한국항해항만학회지
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• 제33권9호
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• pp.603-608
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• 2009

In this paper, a 3m-class free running model ship will be introduced with its manoeuvring performance experiments. The results of turning circle test and zig-zag test will be explained. The developed system are equipped with GPS, main control computer, wireless LAN, IMU (Inertial Measurement Unit), self-propulsion propeller and driving rudder. Its motion can be controlled by RC (Radio Control) and wireless LAN from land based center. Automatic navigation is also available by pre-programmed algorithm. The trajectory of navigation can be acquired by GPS and it provides us with important data for ship's motion control experiments. The results of manoeuvring performance experiment have shown that the developed free running model ship can be used to verify the test of turning circle and zig-zag. For next step, other experimental researches such as ship collision avoidance system and automatic berthing can be considered in the future.

• 한국ITS학회 논문지
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• 제8권4호
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• pp.33-38
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• 2009

본 논문은 자동차 오디오 시스템에 내장된 라디오에서 실시간으로 재생되는 연속적인 오디오 신호로부터 음악 신호를 선별하고, 해당 음악에 대한 실시간 음악장르 분류를 통해 자동으로 이퀄라이저를 조절하는 방식을 제안한다. 제안된 방식에서는 음악분류 정확도를 높이고 실시간 신호처리를 실행하기 위해 연속적인 오디오 신호로부터 추출한 음색 특징 벡터와 리듬 특징 벡터를 GMM (Gaussian mixture model) 분류 방식에 적용하여 음악 분류를 수행한다. 제안된 방식은 카오디오 시스템의 라디오로부터 출력된 오디오 신호로부터 분할된 다양한 오디오 구간을 5가지 음악장르로 분류하여 음악 장르 분류 성능을 측정하였다.

• Journal of Electrical Engineering and information Science
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• 제2권4호
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• pp.79-85
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• 1997

A unified, modular and decoupled approach for the simulation of converter fed induction machine systems is presented. The system under consideration could have semiconductor devices connected to the stator or the rotor of the induction machine for the purpose of controlling its performance. The machine model, however is invariant to these aspects. The model spans the circuit and equation domains of description thus allowing he advantages of both these domains of descriptions to be utilized. The results obtained using this machine and switch model for a VSI fed induction machine (stator fed, rotor shorted0 are compared with those from laboratory experiment to establish the validity and accuracy of th approach. Results for a slip energy recovery system are also presented and compared with those of earlier workers to establish the performance of the models and algorithms in he doubly-fed mode of operation of induction machine systems.

• Advances in Traditional Medicine
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• 제7권1호
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• pp.51-64
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• 2007

Mucus is an aqueous gel complex with a constitution of about 95% water, high molecular weight glycoprotein (mucin), lipid, salts etc. Mucus appears to represent a significant barrier to the absorption of some compounds. Natural mucoadhesive agent was isolated and purified from the aqueous extract of the seeds of prosopis pallida (PP). Formulated tablet with the isolated material by wet granulation method. Some natural edible substances are in consideration for candidates as mucoadhesive agents to claim more effective controlled drug delivery as an alternative to the currently used synthetic mucoadhesive polymers. Subjected the materials obtained from natural source i.e. PP and standard synthetic substance, sodium carboxymethyl cellulose for evaluation of mucoadhesive property by various in vitro and in vivo methods. Through standard dissolution test and a model developed with rabbit, evaluated in vitro controlled release and bioadhesive property of theophylline formulation. Mucoadhesive agent obtained from PP showed good mucoadhesive potential in the demonstrated in vitro and in viνo models. The results suggest that the mucoadhesive agent showed controlled release properties by their application, substantially. In order to assess the gastrointestinal transit time in vivo, a radio opaque X-ray study performed in healthy rabbit testing the same controlled release formulation with and without bioadhesive polymer. Plasma levels of theophylline determined by the HPLC method and those allowed correlations to the in vitro mucoadhesive study results. Better correlation found between the results in different models. PP may acts as a better natural mucoadhesive agent in the extended drug delivery system.

• 한국전자파학회논문지
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• 제18권6호
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• pp.674-679
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• 2007

본 논문에서는 이중 모드 마이크로스트립 링 공진기의 크기를 줄이기 위해 4개의 개방 스터브를 삽입하였고, 이를 이용해 중심 주파수 2 GHz에서 100 MHz의 대역폭을 갖는 대역 통과 필터를 설계하였다. 삽입된 개방 스터브의 캐패시턴스 값에 따라 링 공진기의 크기를 조절할 수 있고, 스터브들의 두 가지 조합 형태 각각의 경우에 대역 통과 필터를 설계할 수 있음을 보였다. 제안된 구조를 2단 대역 통과 필터 회로로 모델링하여 위의 두 가지 경우에 각각 필터를 설계 및 제작하였으며, 설계 결과와 측정 결과가 잘 일치함을 확인하였다.