• Proceedings of the KIEE Conference
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• 2006.07d
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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.

• Proceedings of the KSRS Conference
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• v.2
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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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• v.25 no.5
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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.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.10
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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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• v.6 no.2
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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.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.3
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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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.616-624
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• 2002

In satellite communication, which use the satellite, the protection of TT&C channel which controls the position, performance, and operation is required. In this thesis, we analyzed the weakness of authentication algorithm which is used for protection of TT&C generation and operation. Also, we proposed the authentication algorithm which complements key recovery attack structurely without increasing additional computational amount and verified its performance. The proposed authentication algorithm can satisfy Rivest's recommendation by increasing the computational complexity from $2^{55}$ operations to $2^{111}$ operations. In addition, it can be applied to the existing satellite system because the length of TT&C data and message authentication codes used for the input of authentication algorithm are unchanged.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.345-351
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• 2000

This study is to dvelop a radiotelemetry system to transmit and receive ECG (electrocardiograph) and event signals by using the frequency division multiplexing(FDM) technique. ECG signal sensed by the electrodes is amplified and added to the event signals acting in different frequency range for lead-off, nurse call and low level battery by using FDM. The sub-carrier oscillator using Colpitts circuits and main carrier frequency which is multiplied is frequency modulated by this superhetrodyne technique, and demodulated from the compose IF signal through the quadrature demodulator. A pulse counter demodulator and filtering circuits extract the original ECG and event signals.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.131-134
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• 2024

본 논문에서는 기존 철도 운영 및 관리시에 철도 주변환경으로 부터 발생하는 소음, 진동, 미세먼지 센서에서 다양한 실시간 스트림 데이터를 감지하고 정형화된된 데이터 패턴을 인식하고 분석할 수 있도록 데이터를 구성 및 저장하고 분석된 데이터를 표현할 수 있도록 시각화 지원을 위한 모니터링 시스템 플랫폼을 구현하였다. 데이터 전송을 위해 시리얼 통신 기법을 주로 적용하였으나, 센서와 디바이스의 증가로 인해 시리얼 통신의 한계가 나타났다. 따라서, 본 연구에서는 기존의 아두이노와 서버 간의 직접 통신 방식 대신 라즈베리파이를 도입하여 MQTT Broker(브로커)를 설치하고 통신을 진행하였다. 철도 데이터 모니터링 시스템 플랫폼은 NoSQL 데이터베이스인 MonGoDB와 데이터 시각화할 수 있는 Grafana를 이용하여 구축하였다.