• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.157-162
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• 2010

In this paper, We propose that the adaptive cooperative relay transmission technique using closed-loop MIMO scheme for duplex communication system. As the mobility between relay and base station is little, closed-loop MIMO is better diversity gain than open-loop MIMO. At this time, more than one relaying terminals are included in one cooperative group to share their transmission and take precoding weight feedback. For minimization of throughput reduction caused by increasing feedback bits, we use codebook-based MRT that limit the number of feedback bits. Among the cooperative relay group, the best relays are selected from the base stataion and get the feedback. A protocol senarios are also proposed for this relay system.

• Defense and Technology
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• no.1 s.167
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• pp.42-47
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• 1993

일반적으로 잠수함은 핵추진 잠수함과 디젤추진 잠수함으로 구분되는데, 디젤추진 잠수함은 비교적 소형으로 값이 싸고, 상황에 따라서 핵추진 잠수함보다 용이하게 운용할 수 있으므로 그 존재가치가 아직도 크다고 할수 있습니다. 특히 디젤추진 잠수함용으로 폐회로 디젤기관, 스털링기관, 연료전지, 소형 원자로등의 추진방법이 개발되어 금세기안에 실용화되리라 예상되므로 수중지속능력에 대한 디젤추진방식의 제한점은 곧 극복되리라 판단됩니다

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.317-318
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• 2006

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.90-97
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• 1991

A stepping motor can be driven with open-loop or closed-loop control. The major disadvantage of open-loop control is that it is subjected to resonance and instability in certain speed range, and that there is no way to check stalling or error in position. In this paper, a closed-loop control system consisting of a microcomputer, a hybrid stepping motor, a drive, a lead screw, and an encoder which is used as a position sensor is developed. A control program is programmed in assembly language for real time control and the versatile interface adapter(VIA) is used as the interface with the microcomputer. The experimental results of the stepping motor were eliminated on all kinds of inertia load, and maximum start stop pulse rate and maximum slewing pulse rate were also increased about twice respectively.

• Korean Journal of Optics and Photonics
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• v.8 no.5
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• pp.426-430
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• 1997

A signal processor is implemented to verify the possibility of a closed-loop signal processing for the open-loop fiber-optic gyroscope (FOG). As an all-digital implementation of phase tracking scheme, it does analog-to digital conversion of the detector output and signal processing all-digitally thereafter for a noise-immune FOG signal processor. It has a potential of 36-bits resolution in the $2\pi$ range which is best in the number and sets no limit in the magnitude of the phase shift. The new signal processor was tested on an all-fiber gyroscope and turned out to have a resolution of $3\mu$rad(corresponds to 0.74 deg/hr), which is good enough to measure the Earth's rotation rate.

• Journal of the Korean Magnetics Society
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• v.27 no.3
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• pp.98-103
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• 2017

In this paper, an efficient closed-loop degaussing technique is proposed to control real-time degaussing currents required for a minesweeper. To achieve this, new principle and algorithm for controling degaussing currents are presented, and they are compared to conventional ones. To validate the proposed method, a minesweeper mockup is tested by means of a rigorous numerical simulation. Results show that the method successfully yields satisfactory degaussing performances for several course angle changes of the mockup.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.135-145
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• 2019

Analysis of a long cycle or a trend of time series data based on a long-term observation would require comparability between data observed in the past and the present. In the present study, we proposed an approach to ensure the compatibility among the instruments used for the long-term observation, which would allow to secure continuity of the data. An open-path gas analyzer (Model LI-7500, LI-COR, Inc., USA) has been used for eddy covariance flux measurement in the Gwangneung deciduous forest for more than 10 years. The open-path gas analyzer was replaced by an enclosed-path gas analyzer (Model EC155, Campbell Scientific, Inc., USA) in July 2015. Before completely replacing the gas analyzer, the carbon dioxide ($CO_2$) and latent heat fluxes were collected using both gas analyzers simultaneously during a five-month period from August to December in 2015. It was found that the $CO_2$ fluxes were not significantly different between the gas analyzers under the condition that the daily mean temperature was higher than $0^{\circ}C$. However, the $CO_2$ flux measured by the open-path gas analyzer was negatively biased (from positive sign, i.e., carbon source, to 0 or negative sign, i.e., carbon neutral or sink) due to the instrument surface heating under the condition that the daily mean temperature was lower than $0^{\circ}C$. Despite applying the frequency response correction associated with tube attenuation of water vapor, the latent heat flux measured by the enclosed-path gas analyzer was on average 9% smaller than that measured by the open-path gas analyzer, which resulted in >20% difference of the sums over the study period. These results indicated that application of the additional air density correction would be needed due to the instrument heat and analysis of the long-term observational flux data would be facilitated by understanding the underestimation tendency of latent heat flux measurements by an enclosed-path gas analyzer.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.897-902
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• 2007

The turnover-type sluice gate is typically actuated by the open circuit hydrauic system since the single-rod cylinder is used rather than the double-rod cylinder. However, here the closed circuit hydrauic system is applied for the operation of turnover-type sluice gate for the purpose of convenient operation. The closed circuit hydraulic system of turnover-type sluice gate is composed of a bi-directional pump, single-rod cylinders, pilot operated check valves, check valves and a counter balance valve. The usefulness of the closed circuit hydraulic system is verified for the several operational conditions by the computer simulations.

• Korean Architects
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• no.3 s.359
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• pp.58-60
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• 1999

지난호에서 개괄적으로 설명한 아카시아에 대해서 이번 호부터는 목적이나 연혁 및 중요한 행사 등을 설명한다. 먼저 지난호에서 잘못 표현된 것을 바로잡는다. 아카시아 학생건축상은 ARCASIA Students Prize(아시아건축상은 Award임)이다. 이번 우리협회가 주최하는 제10차 아카시아학술토론회의 주제는 '건축에서의 기술과 전통으로 수정되었다. 지난 2월 피ㆍ카시 아카시아 신임회장의 우리협회 방문시 다각적으로 행사협의를 하는 과정 중에 아카시아 자체가 아시아에서의 일이므로 굳이 아시아를 다시 언급할 필요가 없다는데 중지를 모아 수정한 것이다. 그리고 친교행사 항목은 주최국에 따라서 조금씩 달리 구성한다. 개막식과 환영만찬을 함께 하기도 하고 구분하기도 한다. 또한 우정의 밤과 폐회만찬은 문화의 밤을 별도로 넣고 폐회만찬에 우정의 밤을 함께 하기도 한다. 이번 대회에는 개막식에 환영만찬을 곁들이고, 문화의 밤에는 우리의 전통적인 그 무엇을 보여주고, 폐회만찬시 우정의 밤 행사를 함께 함으로써 참가국들의 장기자랑을 끝으로 공식일정을 마치는 계획을 하고 있다. 이번 호에서는 아카시아 학술토론회를 중심으로 회원국 및 지역구분, 연혁 등을 아카시아의 규약 및 정관, 그리고 점검표를 참고로 하여 소개한다.

• 전기의세계
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• v.31 no.10
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• pp.675-680
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• 1982

전동기제어시스템은, thyristor의 개발로 펄스폭변 조형인버터와 같은 switching기능을 내포한 전원장치의 적용으로, 정류기구가 기계적접점형식에서 전기적 무접점화되어 대체되는 추세에 있어, 속도조정방식도 바꾸어져야 하게 되었다. TRANSVEKTOR제어를 적용한 자계Orientation 방식은, 이러한 관점으로 볼 때, 근원적으로 교류전동기의 속도조정기능을 실용화하는데는 가장 효과적인 방식이라고 볼 수 있다. 더욱이 제지공장 및 직물공장등 폐회로 제어운전을 하는 공정의 전동력기구에서는, 현재 활발히 개발되고 있는 전자계산조직의 활용으로, 종래 직류전동기로서의 Leonard방식의 속도제어를 하는 것에 비하여, 속응성, 신뢰성 및 그 정도에 있어서 월등하게 우수한 기능을 가진 전동기제어시스템의 실용화가 가능하게 되었다.