• 한국항공우주학회지
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• 제34권5호
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• pp.93-100
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• 2006

본 논문에서는 레이더와 원격측정시스템으로부터 수신되는 다중센서자료를 모사하는 시뮬레이터 설계와 이들 자료를 융합하기 위한 알고리듬 개발에 대하여 소개한다. 설계된 데이터 시뮬레이터는 실제 센서 시스템으로부터 얻게 되는 시간의 비동기, 통신지연, 다중 갱신주기들을 갖는 모의센서 자료를 생성하며 실제적인 센서 모델을 이용하여 측정 잡음을 생성한다. 융합알고리듬은 센서 바이어스 상태를 고려한 PVA모델을 기초로 21차 분산형 칼만 필터로 설계되었고, 센서의 이상이나 정상적이 아닌 측정치를 검출하기 위한 로직도 포함되었다. 설계된 알고리듬을 시뮬레이터에서 생성한 모의 자료 및 실제 자료를 적용하여 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.1779-1780
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• 2006

오늘날 대부분의 감시 시스템은 유선에 의한 계측 시스템을 사용하고 있다. 하지만, 유선 감시 시스템은 흩어져 있는 많은 지점의 데이터를 측정하기 어렵고, 초기 설치시나 변경 시에 많은 비용이 소요된다. 우리나라에는 다수의 통신 기지국이 설치되어 있어, 무선 통신망의 구축이 잘 되어 있기 때문에 무선 통신망을 계측 시스템에 적용할 경우 이용하기 용이하고 계측 된 데이터를 송수신시 소모되는 비용 또한 저렴하다. 때문에, 넓게 분포되어 있는 지점의 데이터 측정에는 무선 통신망을 이용하는 것이 유선 계측 시스템의 여러 단점들을 보완할 수 있어 시스템 구성 및 관리에 유리하다. 무선 감시 시스템은 넘게 분포된 불특정 지점의 데이터를 측정할 수 있으며, 무선 통신에 기본적으로 사용되는 시간 정보를 이용하여 여러 계측기의 데이터를 동시에 측정할 수 있다. 또한 센서에서 데이터를 메인 서버로 전송하는 동작 이외에 메인 서버의 명령으로 센서에서 데이터를 취득하여 메인 서버로 재전송할 수 있는 양방향 통신의 구축 또한 용이하다. 본 논문에서는 CDMA 모듈을 통한 무선 통신을 이용하여 여러 지점의 데이터를 동시에 계측할 수 있는 양방향 통신 시스템 구축에 관하여 연구한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.930-933
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• 2006

A new algorithm for satellite microwave rainfall retrievals over the land of Taiwan using TMI (TRMM Microwave Imager) data on board TRMM (Tropical Rainfall Measuring Mission) satellite is described in this study. The scattering index method (Grody, 1991) was accepted to develop a rainfall estimation algorithm and the measurements from Automatic Rainfall and Meteorological Telemetry System (ARMTS) were employed to evaluate the satellite rainfall retrievals. Based on the standard products of 2A25 derived from TRMM/PR data, the rainfall areas over Taiwan were divided into convective rainfall area and stratiform rainfall areas with/without bright band. The results of rainfall estimation from the division of rain type are compared with those without the division of rain type. It is shown that the mean rainfall difference for the convective rain type is reduced from -6.2mm/hr to 1.7mm/hr and for the stratiform rain type with bright band is decreased from 10.7 mm/hr to 2.1mm/hr. But it seems not significant improvement for the stratiform rain type without bright band.

• ETRI Journal
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• 제25권5호
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• pp.387-400
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• 2003

Since its launching on 21 December 1999, the Korea Multi-Purpose Satellite-I (KOMPSAT-I) has been successfully operated by the Mission Control Element (MCE), which was developed by the ETRI. Most of the major functions of the MCE have been successfully demonstrated and verified during the three years of the mission life of the satellite. This paper presents the operational performances of the various functions in MAPS. We show the performance and analysis of orbit determinations using ground-based tracking data and GPS navigation solutions. We present four instances of the orbit maneuvers that guided the spacecraft form injection orbit into the nominal on-orbit. We include the ground-based attitude determination using telemetry data and the attitude maneuvers for imaging mission. The event prediction, mission scheduling, and command planning functions in MAPS subsequently generate the spacecraft mission operations and command plan. The fuel accounting and the realtime ground track display also support the spacecraft mission operations.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.807-814
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• 2004

Land seismic reflection survey has been increasingly demanded in various civil engineering works because of its own ability to delineate layers, water table, to detect cavities or fracture zones, to estimate seismic velocities of each layer. However, our shallow subsurface structures are very complex. The relatively thin layer(mostly soil) to the wavelength directly followed by a basic rock with high impedance used to generate complicated surface waves, kind of channel waves with high amplitude that is dominate in entire seismograms and hence the useful reflection events will be almost hopelessly immersed in the undesired surface waves. Thus, it would seem that the use of traditional seismic survey could not be likely to provide in itself a satisfactory information about our exploration targets. This paper hence introduces an efficient measuring strategy illustrating a properly controlled arrangement of the vertical single force sources commonly used, yielding a very sharply elongated form of P-energy with a minimum of S radiation energy, what we call, P-beam source. Abundant experiments of physical modeling showed that in that way the surface waves could be enormously reduced and the reflection events would be additive and thus reinforced. Examples of field data are also illustrated. The contribution of P-beam source will be great in civil engineering area as well as in general geological exploration area.

• 대한기계학회논문집A
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• 제32권10호
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• pp.866-872
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• 2008

Torsional oscillations of the mechanical drivetrain in electric vehicles are generated under rapid driving conditions. These lead to an uncomfortable jerking of the vehicle and to an increased stress of the mechanical components. To analyze this phenomenon, a drivetrain model is constructed with lumped parameters. The model parameters are identified by geometrical design data and experimental tests. The proposed model is validated by simulation and experimental tests in the time and the frequency domains. As a result, the torsional oscillations are observed at 7Hz of a low damped natural frequency. Also, the analysis of the effect of the parameter variations on the oscillations shows that the oscillation characteristic is mainly dependent on the rotor inertia, and the stiffness of the mounting of the drive aggregate and the driveshaft. The results will be utilized on the basis of the design of an electric drivetrain and an active control of drivetrain oscillations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권2호
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• pp.480-497
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• 2012

As a new business concept, machine-to-machine (M2M) communications are born from original telemetry technology with the intrinsic features of automatic data transmissions and measurement from remote sources typically by cable or radio. M2M includes a number of technologies that need to be combined in a compatible manner to enable its deployment over a broad market of consumer electronics. In order to provide better understanding for this emerging concept, the correlations among M2M, wireless sensor networks, cyber-physical systems (CPS), and internet of things are first analyzed in this paper. Then, the basic M2M architecture is introduced and the key elements of the architecture are presented. Furthermore, the progress of global M2M standardization is reviewed, and some representative applications (i.e., smart home, smart grid and health care) are given to show that the M2M technologies are gradually utilized to benefit people's life. Finally, a novel M2M system integrating intelligent road with unmanned vehicle is proposed in the form of CPS, and an example of cyber-transportation systems for improving road safety and efficiency are introduced.

• 한국초지조사료학회지
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• 제8권3호
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• pp.68-76
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• 1988

The variation of rumination response in steers fed a same amount of orcharugrass hay was investigated. With three steers (6, 12, 24 months) of the Japanese Black Breed, rumination behaviour was measured continuously during a 5 days period by masseter EMG telemetry system. The results are summarized as follows: 1. The average daily rumination time of respective animals were 438,447 and 433 min. with small daily variation both within and among animal. But the rumination time per DM kg of hay consumed varied from 66 to 138 min., and calf spent longer than older calf. 2. Actural chewing time showed small variation, and percentage of actural chewing time spent in rumination time was from 88 to 93% on individual average. 3. The daily number of chewing in rumination was approximately 25,000 to 30,000 with large individual differences. The chews per DM kg intake varied from 3,800 to 9,600, and calf chewed more than older calf. 4. The average rate of chewing per 100 sec. (chewing speed), there was a large difference between animals i.e. 104, 114, 131 respectively, but very little variance between days in individual. 5. No relation between day to day variations in eating time and rumination behavior, but significantly positive correlation was observed in the relation among rumination time, chewing time, No. of boluses and No. of chews. 6. Active time of day in rumination altered considerably day to day, but variation in the amount of rumination per day as expressed by the rumination time was relatively small.

• 한국통신학회논문지
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• 제27권6B호
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• pp.616-624
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• 2002

인공 위성을 이용한 위성 통신망에서는 위성의 위치, 성능, 그리고 동작을 제어하는 관제신호(Telemetry, Tracking and Command, TT&C)채널의 보호가 요구된다. 본 논문에서는 관제신호의 생성 및 수행의 보안을 위하여 사용되는 인증 알고리즘의 취약점을 분석하고 부가적인 계산량을 크게 증가시키지 않으면서도 키 복구 공격(key recovery attack)에 대해 구조적으로 보완하는 인증 알고리즘을 제안하고 검증하였다. 제안한 인증 알고리즘은 입력으로 사용되는 관제신호 데이터의 크기와 메시지 인증 코드의 크기를 변경하지 않아 기존의 위성 시스템에 그대로 적용 가능하며 키 복구 공격에 대한 계산 복잡도를 기존의 2$^{55}$번의 수행에서 2$^{111}$ 번으로 증가시켜 divest의 권고만을 만족시킬 수 있음을 보인다.

• 대한의용생체공학회:의공학회지
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• 제21권4호
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• pp.345-351
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• 2000

본 연구는 심전신호와 부가정보 신호의 다중신호를 주파수분할 다중방식과 주파수변조에 의해 무선전송하기 위함이다. 심전신호는 전극으로부터 유도되고 아날로그 증폭기에 의해 증폭된다. 전극 전착부실, 간호사 호출 및 저전압 배터리 신호의 부가정보 신호는 서로 주파수가 중복되지 않도록 발진되고 주파수분할 다중방식에 의해 합성되어 주파수 변조된다. 주파수 변조된 신호는 콜피츠회로에 의해 발진된 기본 반송파로 주파수 변조되고 체배되어 송신 반송주파수로 변환된다. 수신된 신호는 슈퍼헤테로다인 방식에 의해 중간주파수로 변환되고 쿼드래처 복조기에 의해 주파수 변조된 신호는 복조된다. 펄스카운터와 저역통과필터에 의해 심전신호와 부가정보 신호들은 복조된다.