• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.31-35
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• 2004

정보통신 기술의 발달과 디지털 방송의 시작, 뉴미디어의 출현으로 인한 통신과 방송의 융합은 가속화되고 있다. 또한 2010년까지 광대역통신망 BcN과 홈네트워크 구축을 위한 정부정책이 실행 중에 있다. 100Mbps의 전송속도를 구현해야 하는 광대역 통신망(BcN)을 위해 기존 인터넷 백본 1)망은 잘 구축이 되어 있으나 가입자까지의 망 구조에 많은 문제점을 앉고 있다. 기존 전화국을 이용한 XDSL과 지역 SO를 활용한 Cable Modem의 경우 병목현상과 이론상 속도 또한 BcN과 통방통합이 요구하는 50-100Mhz의 전송속도를 만족하지 못한다. 새로운 망 구조를 구축하기 위해 많은 비용과 시간의 소요가 예상된다 가입자 망 구축에 따른 많은 방법과 이론이 제시되고 있다. 똔 논문에선 지역 SO를 활용하여 가입자까지 망을 통방통합과 BcN에 적합한 가입자 망을 새롭게 구성하는 것을 목표로 한다. 먼저 지역 50의 망을 활용하기 위해선 기존 KT와 파워콤의 COF(Glass Optical Fiber)망과 지역 케이블 SO의 HFC 망을 이용하기에는 동축케이블 망의 물리적 특성에 따른 한계로 통방통합과 BcN에 부적합하다. Tree And Branch 구조의 HFC망 대신 $SMF^{2)}$의 기존 SO의 자가망을 새롭게 설계하고 광분배망 기술인 $E-PON^{3)}$방식을 접목시켜 최대한 동축망을 사용하지 않고 굴곡 특성에 약한 $FOG^{4)}$의 특성을 극복하기 위해 $POF^{5)}$망을 이용하여 댁내 홈게이트웨이까지 연결하는 방식으로 지역 SO를 거점으로 활용하여 댁내까지 FHHT와 홈 네트워크까지의 가입자 망을 새롭게 구성하고자 한다. 저장의 효율성을 위해 이진 포멧인 IPMP화된 MP4 파일을 생성할 수 있다.으로써, 에러 이미지가 가지고 있는 엔트로피에 좀 근접하게 코딩을 할 수 있게 되었다. 이 방법은 실제로 Arithmetic Coder를 이용하는 다른 압축 방법에 그리고 적용할 수 있다. 실험 결과 압축효율은 JPEG-LS보다 약 $5\%$의 압축 성능 개선이 있었으며, CALIC과는 대등한 압축률을 보이며, 부호화/복호화 속도는 CALIC보다 우수한 것으로 나타났다.우 $23.87\%$($18.00\~30.91\%$), 갑폭 $23.99\%$($17.82\~30.48\%$), 체중 $91.51\%$($58.86\~129.14\%$)이였으며 성장율은 사육 온도구간별 차는 없었다.20 km 까지의 지점들(지점 2에서 지점 6)에서 매우 높은 값을 보이며 이는 조석작용으로 해수와 담수가 강제혼합되면서 표층퇴적물이 재부유하기 때문이라고 판단된다. 영양염류는 월별로 다소의 차이는 있으나, 대체적으로 지점 1과 2에서 가장 낮고, 상류로 갈수록 점차 증가하며 지점 7 상류역이 하류역에 비해 높은 농도이다. 월별로는 7월에 규산염, 용존무기태질소 및 암모니아의 농도가 가장 높은 반면에 용존산소포화도는 가장 낮다. 그러나 지점 14 상류역에서는 5월에 측정한 용존무기태질소, 암모니아, 인산염 및 COD 값이 7월보다 다소 높거나 비슷하다. 한편 영양염류와 COD값은 대체적으로 8월에 가장 낮으나 용존산소포화도는 가장 높다.출조건은 $100^{\circ}C$에서 1분간의 고온단시간 추출이 적합하였다. 증가를 나타내었는데

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.889-901
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• 2021

The tension of cables and motion response significantly affect safety of an immersed tunnel element in the immersion process. To investigate those, a hydrodynamic scale-model test was carried out and the model experiments was conducted under wind, current and wave loads simultaneously. The immersion standby (the process that the position of the immersed tunnel element should be located before the immersion process) and immersion process conditions have been conducted and illustrated. At the immersion standby conditions, the maximum force of the cables and motion is much larger at the side of incoming wind, wave and current, the maximum force of Element-6 (6 cables directly tie on the element) is larger than for Pontoon-8 (8 cables tie on pontoon of the element), and the flexible connection can reduce the maximum force of the mooring cables and motion of element (i.e. sway is expecting to decrease approximate 40%). The maximum force of the mooring cables increases with the increase of current speed, wave height, and water depth. The motion of immersed tunnel element increases with increase of wave height and water depth, and the current speed had little effect on it. At the immersion process condition, the maximum force of the cables decrease with the increase of immersion depth, and dramatically increase with the increase of wave height (i.e. the tension of cable F4 of pontoons at wave height of 1.5 m (83.3t) is approximately four times that at wave height of 0.8 m). The current speed has no much effect on the maximum force of the cables. The weight has little effect on the maximum force of the mooring cables, and the maximum force of hoisting cables increase with the increase of weight. The maximum value of six-freedom motion amplitude of the immersed tunnel element decreases with the increase of immersion depth, increase with the increase of current speed and wave height (i.e. the roll motion at wave height of 1.5 m is two times that at wave height of 0.8 m). The weight has little effect on the maximum motion amplitude of the immersed tunnel element. The results are significant for the immersion safety of element in engineering practical construction process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.229-235
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• 2019

A floating photovoltaic generation system is a new concept that combines existing photovoltaic generation technology with floating technology. This is installed in the water not on conventional land and a building. The system is designed as a unit module type that can be connected to other modules according to the power generation capacity, thereby forming a large-scale power generation facility. As a renewable energy source, it is composed of a floating structure, mooring device, photovoltaic power generation facility, and underwater cable. Because this system is installed outdoors, the effect of the wind load on the structure is very large. In this study, the wind loads most affected on the floating photovoltaic generation structure were obtained by computational fluid dynamic analysis. The flow characteristics and wind loads were analyzed for a range of wind orientations and angles of inclination. The analysis showed the position and magnitude of the maximum wind load to the wind direction and the flow characteristics around the solar panel and floating system. The wind load increased with increasing angle of inclination of the panel to the ground.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.8
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• pp.709-717
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• 2013

This paper presents the development of a specialized underwater leg with a manipulator function(convertible-to-arm leg) for the seabed walking robot named CRABSTER200(CR200). The objective functions of the convertible-to-arm leg are to walk on the seabed and to work in underwater for precise seabed exploration and underwater tasks under coastal area with strong tidal current. In order to develop the leg, important design elements including the degree of freedom, dimensions, mass, motion range, joint structure/torque/angular-speed, pressure-resistance, watertight capability and cable protection are considered. The key elements of the convertible-to-arm leg are realized through concept/specific/mechanical design and implementation process with a suitable joint actuator/gear/controller selection procedure. In order to verify the performance of the manufactured convertible-to-arm leg, a 25bar pressure-resistant and watertight test using a high-pressure chamber and a joints operating test with posture control of the CR200 are performed. This paper describes the whole design, realization and verification process for implementation of the underwater convertible-to-arm leg.

• Journal of Digital Convergence
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• v.13 no.10
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• pp.263-269
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• 2015

This paper suggest remote control technic using TCP/IP protocol network after UART serial communication implemented through RS-232 cable to ethernet module. This is multidisplinary signal technique which is PC signal is converted to internet communication signal. Ethernet module is WIZ1000SR. This is gate module which convert RS-232 protocol to TCP/IP protocol. This module convert serial data transmitted serial device to TCP/IP type data, in contrast TCP/IP data received through network converted to serial data transmitted to serial device. This paper propose that the lower subnet internet layer UDP module make the higher speed in control board than TCP/IP signal.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.483-490
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• 1999

In this paper, the cost-effective design of output reactor which is USCD to suppress the over-voltage at the m motor terminal in the Adjustable Speed Drives(ASD) application is proposed. In the elevator drive svstem. the R IXlwer cable length is relatively shorter than other ASD applications and then the over voltage at the motor terminal depends on the frequency characteristics of the output reactor at the over voltage operating frequency. The over-voltage suppression mechanism of output reactor in ASD application is analyzed and the dominant parameters of output reactor for the over-voltage supression are extracted. Using these as the design values and considering the high frequency characteristics of iron core in the reactor. a new c cost-effective structure of output reactor is proposed. Experimental results of the conventional reactor and the p proposed reactor with a l5kW induction motor are given to verify the propoSLD scheme.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.6
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• pp.709-717
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• 2002

A new multi constant modulus algorithm (MCMA) for a blind decision feedback equalizer is proposed. In order to avoid the error propagation problem in the conventional DFE structure, Feed-Back Filter coefficients are updated only after Feed-Forward Filter coefficients are sufficiently converged to the steady state. Therefore, it has the problem of slow convergence speed characteristics. To overcome this drawback, the proposed MCMA algorithm uses not only new cost function considering the minimum distance between the received signal and the representative value containing the statistical characteristics of the transmitted signal, but also adaptive step-size according to the equalizer outputs to fast convergence speed of FBF. Simulations were carried out under the certified communication channel environment to evaluate a performance of the proposed equalizer. The simulation results show that the proposed equalizer has an improved convergence and SER performance compared with previous methods. The proposed techniques offer the possibility of practical equalization for cable modem and terrestrial HDTV broadcast (using 8-VSB or 64-QAM) applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.721-728
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• 2009

Equal/unequal 4-way power divider suitable for satellite communication using SIW technology is presented in this paper. The control of positions of guiding posts provides equal or unequal power division ratios by maintaining the width of the SIW unchanged. In addition, the detailed descriptions for the proposed power divider include the general characteristics of radial waveguide, feeding part using coaxial cable, simple SIW structure, power-guiding posts, and transition for measurement. The comparison between the simulated and measured data shows a good agreement at a center frequency of 10 GHz. The measured input impedance bandwidths for equal and unequal power divisions are about 2.1 GHz and 3 GHz under the condition of less than VSWR 2:1, respectively.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.37-44
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• 2016

Optical fiber temperature sensing systems have incomparable advantages over traditional electrical-cable-based monitoring systems. However, the fiber optic interrogators and sensors have often been rejected as a temperature monitoring technology in real-world industrial applications because of high cost and over-specification. This study proposes a multiplexed fiber optic temperature monitoring sensor system using an economical Optical Time-Domain Reflectometer (OTDR) and Hard-Polymer-Clad Fiber (HPCF). HPCF is a special optical fiber in which a hard polymer cladding made of fluoroacrylate acts as a protective coating for an inner silica core. An OTDR is an optical loss measurement system that provides optical loss and event distance measurement in real time. A temperature sensor array with the five sensor nodes at 10-m interval was economically and quickly made by locally stripping HPCF clad through photo-thermal and photo-chemical processes using a continuous/pulse hybrid-mode laser. The exposed cores created backscattering signals in the OTDR attenuation trace. It was demonstrated that the backscattering peaks were independently sensitive to temperature variation. Since the 1.5-mm-long exposed core showed a 5-m-wide backscattering peak, the OTDR with a spatial resolution of 40 mm allows for making a sensor node at every 5 m for independent multiplexing. The performance of the sensor node included an operating range of up to $120^{\circ}C$, a resolution of $0.59^{\circ}C$, and a temperature sensitivity of $-0.00967dB/^{\circ}C$. Temperature monitoring errors in the environment tests stood at $0.76^{\circ}C$ and $0.36^{\circ}C$ under the temperature variation of the unstrapped fiber region and the vibration of the sensor node. The small sensitivities to the environment and the economic feasibility of the highly multiplexed HPCF temperature monitoring sensor system will be important advantages for use as system-integrated temperature sensors.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.12
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• pp.830-842
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• 2015

This paper aims to develop a SI(structural identification) technique using the kinetic energy optimization technique(KEOT) and the direct matrix updating method(DMUM) to decide on optimal location of sensors and to update FE model respectively, which ultimately contributes to a composition of more effective SHM. Owing to the characteristic structural flexing behavior of cable bridges, which makes them vulnerable to any vibration, systematic and continuous structural health monitoring (SHM) is pivotal for them. Since it is necessary to select optimal measurement locations with the fewest possible measurements and also to accurately assess the structural state of a bridge for the development of an effective SHM, a SI technique is as much important to accurately determine the modal parameters of the current structure based on the data optimally obtained. In this study, the KEOT was utilized to determine the optimal measurement locations, while the DMUM was utilized for FE model updating. As a result of experiment, the required number of measurement locations derived from KEOT based on the target mode was reduced by approximately 80 % compared to the initial number of measurement locations. Moreover, compared to the eigenvalue of the modal experiment, an improved FE model with a margin of error of less than 1 % was derived from DMUM. Finally, the SI technique for long-span bridges proposed in this study, which utilizes both KEOT and DMUM, is proven effective in minimizing the number of sensors while accurately determining the structural dynamic characteristics.