• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.598-603
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• 2007

In this paper we propose a QMAC to support QoS(Quality of Service) and to enhance the transmission throughput in Wireless Sensor Networks(WSNs). In the proposed QMAC, sender nodes send transmission request packets with QoS requirements to the receivers node using CSMA/CA MAC protocol. And the receiver node assigns slots according to the packet priority, network topology, and the amount of traffics using TDMA. Using QMAC we get the enhanced throughput and QoS support by lowering the duplicated slot assignment.

• Composites Research
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• v.14 no.5
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• pp.12-19
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• 2001

In aircraft composite structures, structural defects such as matrix cracks, delaminations and fiber breakages are hard to detect if they are breaking out in operating condition. Therefore, to assure the structural integrity, it is desirable to perform the real-time health monitoring of the structures. In this study, a fiber optic sensor was applied to the composite beams to monitor failure and strain in real-time. To detect the failure signal and strain simultaneously, laser diode and ASE broadband source were applied in a single EFPI sensor using wavelength division multiplexer. Short time courier transform and wavelet transform were used to characterize the failure signal and to determine the moment of failure. And the strain measured by AEFPI was compared with the that of strain gage. From the result of the tensile test, strain measured by the AEFPI agreed with the value of electric strain gage and the failure detection system could detect the moment of failure with high sensitivity to recognize the onset of micro-crack failure signal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.560-567
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• 2011

In this paper, we reduced the optical noise interference using polarizers in a visible light communication system. In a transmitter, two light-emitting diodes(LEDs) are modulated synchronously by the original and the reversed signals of the transmitted data, and the two LED lights are radiated through orthogonal polarizers. In a receiver, two optical signals are detected through orthogonal polarizers and differentially amplified to remove the optical noise. In an environment that noise light from a fluorescent lamp is much stronger than the signal, the receiver with orthogonal polarizers removed the 120 Hz noise, and synchronous light transmission of the original and the reversed signals using two LEDs reduced the illumination flickering to about one-eighth that using one LED.

• Geophysics and Geophysical Exploration
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• v.21 no.4
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• pp.231-243
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• 2018

Streaming potential (SP) arises from fluid flow through effectively connected pores. From this potential, formation water information as well as fluid flow properties can be estimated. As micro particles being located in boundary between subsurface porous media and fluid are charged to form electrical double layer, fluid flow caused by several reasons generates SP, one of electrokinetic phenomena. Occurrence mechanism of SP is complex and signal strength is relatively weak compared to noise. However, application of self potential survey using SP to monitoring of formation fluid is expanding because of its' convenience of exploration without artificial source and repetitiveness of signal. This paper accounts for the occurrence mechanism of SP studied before, including governing equations and analyzes previous various case studies of SP according to the change of physical properties of materials. It helps to increase understanding about SP and also lays the foundations of the application of SP to fields.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.7
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• pp.813-826
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• 1999

실시간 멀티미디어 응용의 등장으로 멀티캐스트와 QoS(Quality of Service) 지원이 필수적인 망 서비스로 부각되고 있다. 이에, ATM 기반의 인터넷에서 IP 멀티캐스트의 효율적인 처리를 위하여 MARS(Multicast Address Resolution Server)가 제안되었고, 기존의 최선 서비스 기반의 인터넷에서 QoS(Quality of Service)를 지원하기 위하여 RSVP(Resource Reservation Protocol)가 제안되었다. 본 논문에서는 ATM 망에서 QoS가 지원되는 IP 멀티캐스트 서비스를 제공하기 위하여 MARS 구조에서 RSVP를 지원하는 두 가지 방안을 제안하고, 시뮬레이션을 통하여 그 성능을 분석하였다. 제안하는 두 가지 방법은 각각 'RSVP 전 홉 노드 방식'과 'MARS 서버 방식'이라 명명하였다. RSVP 전 홉 노드 방식은 송신원으로부터 ATM 망으로 진입하는 노드와 수신원을 향하여 ATM 망을 진출하는 노드 간에 각각 일대일 양방향 VC를 설정하여 멀티캐스트 그룹에 속하는 수신원들이 보내는 자원 예약 메시지를 ATM 망에서 전송하는 방안이다. MARS 서버 방식은 ATM 망을 진출하는 노드와 MARS 서버간에 MARS 제어 메시지 교환을 위해 존재하는 ATM VC를 사용하여 RSVP의 자원 예약 메시지를 전송하고, MARS 서버가 RSVP 자원 예약 메시지를 처리하도록 그 기능을 확장함으로써 ATM 망에서 필요로 하는 제어 VC 수를 절약할 수 있는 방안이다. 시뮬레이션을 통하여, MARS 서버 방식은 ATM 제어 VC의 수를 절약할 수 있을 뿐 아니라 경우에 따라 RSVP 자원 예약 메시지 전달 지연을 줄일 수도 있음을 볼 수 있었다. 그러나, MARS 클러스터 내에 동시에 존재하는 RSVP 흐름이 많을 때에는 MARS 서버 방식의 경우 MARS 서버에서의 병목 현상으로 인해 성능이 저하될 수 있다.Abstract Emerging real time multimedia applications require multicast service with a QoS(Quality of Service) support. An overlay service architecture MARS(Multicast Address Resolution Server) is proposed to support IP multicast over an ATM network, and a resource reservation protocol RSVP is proposed to provide QoS support in the Internet which is originally based upon best effort service only. In this paper, we propose two schemes to support IP multicast service with QoS support over ATM networks: 'RSVP Previous Hop Node(RPHN) scheme' and 'MARS server based scheme'. In RPHN scheme, the RSVP reservation messages are transported via one-to-one ATM control VC from the egress nodes to the ingress nodes of the the multicast flow set up between each pair of nodes. The RSVP message processing occurs at the ingress nodes of the multicast flow. Whereas, in the MARS server based scheme, the RSVP reservation messages are transported via the MARS control VCs between the egress nodes and the MARS server. The RSVP message processing burden is imposed at MARS server in this scheme. For MARS server based scheme, no additional ATM VC is required for RSVP reservation message transmission, while the processing burden at the MARS server is high. Simulation results show that the MARS server based scheme, may accomplish RSVP reservation message delivery with smaller delay as well as saving of the number of ATM VCs. When the number of simultaneous RSVP flows in the MARS cluster is large, however, MARS based scheme may suffer performance degradation since MARS server becomes a performance bottleneck.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.391-397
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• 2005

Since space time block code (STBC) technique of a transmission diversity technique was introduced, multiple input multiple output techniques using transmission diversity at the basestation for improving transmission data rate, have been studied extensively. Multiplexed STBC OFDM technique uses multiple groups of two transmit antennas and suppresses the interference signals of other STBC OFDM groups at the receivers. In this paper, I propose a new method of iterative decoding and maximal ratio receive combining technique for multiplexed STBC OFDM systems, and simulated and showed the results in comparison with the conventional methods.

• Geophysics and Geophysical Exploration
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• v.21 no.1
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• pp.15-25
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• 2018

Seismic inversion is a high-resolution tool to delineate the subsurface structures which may contain oil or gas. On the other hand, marine controlled-source electromagnetic (mCSEM) inversion can be a direct tool to indicate hydrocarbon. Thus, the joint inversion using both EM and seismic data together not only reduces the uncertainties but also takes advantage of both data simultaneously. In this paper, we have developed a simultaneous joint inversion approach for the direct estimation of reservoir petrophysical parameters, by linking electromagnetic and seismic data through rock physics model. A cross-gradient constraint is used to enhance the resolution of the inversion image and the maximum likelihood principle is applied to the relative weighting factor which controls the balance between two disparate data. By applying the developed algorithm to the synthetic model simulating the simplified gas field, we could confirm that the high-resolution images of petrophysical parameters can be obtained. However, from the other test using the synthetic model simulating an anticline reservoir, we noticed that the joint inversion produced different images depending on the model constraint used. Therefore, we modified the algorithm which has different model weighting matrix depending on the type of model parameters. Smoothness constraint and Marquardt-Levenberg constraint were applied to the water-saturation and porosity, respectively. When the improved algorithm is applied to the anticline model again, reliable porosity and water-saturation of reservoir were obtained. The inversion results indicate that the developed joint inversion algorithm can be contributed to the calculation of the accurate oil and gas reserves directly.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1999.12a
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• pp.209-218
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• 1999

처방전달시스템은 처방의 수행은 의사가, 그에 따른 의약품조제는 약사가 수행함으로써 의약품의 오․남용을 방지하기 위한 의약분업의 실시에 따른 국민불편의 최소화와 약화사고에 따른 인증문제 등을 지원하기 위한 정보시스템이다. 처방전달시스템은 환자 개인정보의 허용된 범위 내에서의 공유와 공유를 위한 각종 개인정보 보호장치, 처방의 안전한 전달을 위한 내용의 비밀보장과 위변조방지 및 송신자와 수신자의 인증을 위한 장치가 필수적으로 필요하다. 또한 자료의 생명주기 측면에서 본다면, 처방전의 생성은 병․의원에서 이루어지며 소멸은 약국 및 환자에의해 이루어진다. 자료의 유통과정에 살펴보면 처방전달시스템의 주요성공요인은 정보의 생산자인 병․의원(의사)의 적극적인 정보제공의지와 이를 지원하는 편리한 정보시스템의 구축이라고 할 수 있다. 정보의 생산자인 병․의원 정보시스템 환경은 다양하고 복잡하기 때문에 기존의 애플리케이션을 이용하면서 처방의 전송을 위해서는 기존 애플리케이션 및 플랫폼에 독립적이며 자료의 적합한 취합과 통합이 가능하도록 지원하는 시스템이 필요하다. 처방전달 메시징시스템은 이러한 복합적인 정보시스템 환경을 지원하며 동시에 처방정보의 안전한 전달을 위해 플랫폼으로 실행될 수 있는 시스템을 말한다. 또한 처방의 비교적 짧은 생명주기와 지역적 생산, 유통구조를 적합하게 지원하기 위해 지역별 독립시스템의 구축과 공통정보 활용을 위한 중앙시스템과의 역할분담 모델에 근거한 분산시스템의 구축이 요구된다. 본 연구에서의 처방전달 메시징시스템은 일반적인 메시지서비스의 특성을 기본으로 자료전달을 위해 자료 암호화와 복호화, 송신자와 수신자에 대한 인증 및 자료접근 제한기능을 제공하며 각 클라이언트와 서버간의 실시간 연결 혹은 지연연결을 지원하는 독립적인 애플리케이션이다. 이러한 처방전달 메시징시스템을 구성하는 각 요소에 대해 정의하고 개념적 모델을 설계하고자 한다.에게 청구되며, 소비자에게 전송 되는 청구서는 사용자DB를 참조하여 사용자가 미리 정의한 원하는 형태로 변환되어 전달되며, 필요시 암호화 과정을 거치는 것이 가능해야 한다. 전송된 청구서는 전자우편의 경우, 암호해독이 가능한 전용 브라우저를 통해 열람 되며, 이는 다시 전용 브라우저를 통해 지불인증이 승인되어 청구 제시서버에게 전송된다. EBPP 시스템의 제어 흐름은 크게 기업이 청구 정보를 소비자에게 제시하는 흐름과 소비자의 지불 승인으로 인해 기업이 은행에 지불을 요구하는 흐름으로 구분할 수 있다. 본 논문에서는 통합 청구서버 및 정구 제시서버의 역할 및 구성 요소들에 대해 서술하고, EBPP 시스템과 연동하여야 하는 메일 서버와의 상호 작용에 대해 서술할 것이다. 본 시스템을 아직 구현이 되지 않은 관계로 시스템의 성능 등의 수치적 결과를 제시할 수 없는 상태다., 취약계층을 위한 일차의료, 의약관리), ${\circled}2$ 보건소 조직 개편 및 민간의료기관과 협력체계 확립, ${\circled}3$ 전문인력 확보 및 인력구성 조정, 그리고 ${\circled}4$ 방문보건사업의 강화 등이다., 대사(代謝)와 관계(關係)있음을 시사(示唆)해 주고 있다.ble nutrient (TDN) was highest in booting stage (59.7%); however no significant difference was found among other stages. The concentrations of Ca and P were not different among mature stages. According to these results, the yellow ripe period is appropriate to harvest the whole crop rice for forage considering dry matter yields,

• Geophysics and Geophysical Exploration
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• v.6 no.1
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• pp.13-22
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• 2003

TSP (Tunnel Seismic Profiling) survey is a technique for imaging and characterizing geological structures ahead of a tunnel face. The seismic modeling algorithm and the synthetic data could be helpful for TSP surveys. However, there is few algorithm to describe the propagation of the elastic waves around the tunnel. In this study, existing 2-dimensional seismic modeling algorithm using finite element method was modified to make a suitable algorithm for TSP modeling. Using this algorithm, TSP modeling was practiced in some models. And the synthetic data was analyzed to examine the propagation characteristics of the elastic waves. First of all, the modeling for the homogeneous tunnel model was practiced to examine the propagation characteristics of the direct waves in the vicinity of the tunnel. And the algorithm was applied to some models having reflector which is perpendicular or parallel to the excavation direction. From these, the propagation characteristics of the reflected waves were examined. Furthermore, two source-receiver arrays were used in respective models to investigate the properties of the two arrays. These modeling algorithm and synthetic data could be helpful in interpreting TSP survey data, developing inversion algorithm and designing new source-receiver arrays.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.1-4
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• 2014

A radio communication system has interference caused by other radio transmitters operated in co-channel or adjacent channels. Therefore technical specifications are made by considering and investigating the effects of interference between the new system and present systems when the new system will be started to serve in the near future. FTS is used for preventing an abnormal mission and guaranteeing public protection. Recently the next generation FTS's are researched to reinforce the security and to increase the operating capability of simultaneous use. EFTS known as one of the next generation FTS's is suitable for such purposes. In this paper the effects of interference signals on the performance of EFTS are investigated. Noncoherent DPSK and noncoherent CPFSK are considered for the modulation method of EFTS and a FMCW and a pulse RADAR considered as a interferer. The power of FMCW is 20.3dB lower than the power of EFTS and the power of pulse RADAR is 19.1dB lower than that of EFTS. Simulation results show that FMCW interferer reduce $E_b/N_o$ of about 1dB and $E_b/N_o$ of EFTS deteriorates about 0.5dB due to interference signals generated from pulse RADAR.