• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.4
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• pp.321-326
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• 2010

The non-explosive release device using jack mechanism is designed and fabricated for the small satellite. As a triggering actuator for the release device, a piezo rotory motor with torque of more than $1.7kgf{\cdot}cm$ is employed to guarantee stable activation. For performance tests of separation device, we conducted release time test, preload test and shock test. The device was operated within 1.172sec and activated stably under load of 45kgf. Maximum shock was measured as 18G that is much less than the pyro-separation device produces. We confirmed the possibility as a satellite separation device through above presented tests.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.784-787
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• 2006

In this paper, we propose a method for nonlinear grapheme segmentation in Korean printed character type classification. The characters are subdivided into six types based on character type information. The feature vector is consist of mesh features, vertical projection features and horizontal projection features which are extracted from gray-level images. We classify characters into 6 types using Back propagation. Character segmentation regions are determined based on character type information. Then, an optimal nonlinear grapheme segmentation path is found using multi-stage graph search algorithm. As the result, a proposed methodology is proper to classify character type and to find nonlinear char segmentation paths.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.03a
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• pp.79-95
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• 1994

기체분리용 고분자분리막은 1977 미국 Monsanto 사의 Prism 분리기가 성공적으로 상업화된 이래 분리막의 수요가 점차 확장되어 가고 있다. 기체 분리공정은 크게 저온 분리법 (Cryogenic process), PSA (pressure swing adsorption) 그리고 분리막법 등이 있다. 저온 분리법과 PSA법의 공정에 대한 설계 및 운전기술 등이 잘 발달되어 있으며 현재 널리 사용되고 있는 보편화된 기술인 반면, 분리막 기술은 상대적으로 새로운 기술이며 성공적으로 상업화된지 약 15년이 되었다. 분리막을 이용한 기체분리법은 다른 공정에 비하여 에너지소비가 적고 설비투자도 적게 필요한 장점이 있다. 특히 적은 양의 기체를 생산하는 데 경제적이며 장비가 가볍고 좁은 공간에서도 사용할 수 있다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.5
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• pp.19-29
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• 2006

In this study, numerical simulation of airframes separating from a missile system has been preformed. For the time-accurate trajectory simulation, six D.O.F equations of motion of multiply connected bodies were derived and these equations have been coupled with the unstructured overset mesh technique for the treatment of independent mesh blocks moving with each body component. Applications were made for the simulation of the airframe separation at missile angles of attack of 0 and 5 degrees. It was demonstrated that the present method is efficient and robust for the prediction of unsteady time-accurate flow fields involving multiple bodies in relative motion.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.4
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• pp.729-736
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• 2019

In this paper, we propose a method to improve the background sound separation performance by adding a Wiener filter to the end of the non - negative matrix factorization method. In the case of a mixed voice signal with background sound, a part that has not yet been completely separated may remain in the signal that separated first by the non-negative matrix factorization method. In this case, it can be reduced in proportion to the size of the residual signal due to the Wiener filter, so that the background sound separation or reduction effect can be expected. Experimental results show that the addition of the Wiener filter is more effective than the case of applying the non-negative matrix factorization method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.8
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• pp.767-773
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• 2010

This paper describes development of a non-explosive separation device which can be equipped on small satellites. The spur geared micro DC motor, which has high reliability and advantage of price, is adopted as an actuator. The proposed separation device has resettability and it does not need extra jig to reload. In addition, the simple structure makes it easy to fabricate and assemble. To verify the performance of the proposed device, the response time tests, maximum preload tests and maximum shock level tests were performed. Also, through the vibration tests and thermal vacuum tests, feasibility of the proposed separation device was shown in launching and space environments. Therefore, we expect that the proposed separation device can replace the imported separation devices in near future.

• The Korean Journal of Mycology
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• v.34 no.2
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• pp.88-91
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• 2006

Attempts were made to investigate the conditions of mycelia of one low-temperature type strain and one high-temperature type strain of shiitake showing poor fruit-body formation in bed-log, and to survey harmful microorganisms formed on the log surface in Gapyung County, Korea. When tested the growing ability of mycelia, the low-temperature type strain showed ca. 1.1% decrease compared with preserved original strain. And, the high-temperature type one showed ca. 8.0% decrease. The growth of isolated mycelia was tested in sawdust medium. The high-temperature type strain showed ca. 10.8% decrease compared with original strain, and the low-temperature type one showed ca. 25.1% decrease. Weight reduction rate was investigated. The high-temperature strain showed ca. 20.1% decrease and the low-temperature one ca. 19.0%. When compared with non-treatment, original high-temperature type strain showed 107.0% decrease, the isolated high-temperature type strain 49.5%, original low-temperature type one 85.4%, isolated low-temperature type one 50.0%. As the results of confrontation culture, the high-temperature type strain and the low-temperature type one were same as the original ones, respectively. And, in the bed-logs, Hypoxylon truncatum, Coriolus versicolor, Inonotus xeranticus, Daedaleopsis tricolor, Graphostroma platystoma, two species of Myxomycetes, Trichoderma sp. Hypoxylon fragiforme, H. howeianum, and Nitschkia confertula were observed as harmful microorganisms, and the bed-logs were not in good condition.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.5
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• pp.457-463
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• 2009

This paper describes the development of non-explosive separation(NES) device which can be equipped on a small satellite. It comprises mechanism itself and spring-type shape memory alloy(SMA) actuator. In order to design SMA actuator properly, the necessary actuation force is measured. Based on that result, SMA actuator is designed and fabricated. Finally, SMA actuator and the proposed mechanism are integrated. In order to evaluate performance of the developed NES, we carried out a response time test, preload test and shock level test. In near future, we expect to replace the imported NES device with the developed device.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.151-154
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• 1998

이 논문에서 비선형 배열 MUSIC 빔형성 기법을 이용하여 예인형 선배열 센서 시스템의 표적 좌우 방위 분리 방법을 기술하였다. 이 기법은 배열 운동모델 Water-Pully 모델과 방향센서의 정보를 이용하는 칼만필터를 설계하여 예인함 기동에 따른 배열형상을 추정하고 표적의 좌우방위를 분리하기 위하여 추정된 배열형상에서 MUSIC 빔형성 기법으로 신호처리를 수행하였다. 또한 예인주기와 예인진폭과 같은 예인함 기동형태의 전형적인 빔형성 기법과 MUSIC 빔형성 기법으로 표적의 좌우 방위 분리 성능을 비교 분석하였다.

• Membrane Journal
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• v.3 no.2
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• pp.51-59
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• 1993

해수는 약 3.5%의 여러가지 염류가 용해되어 있는 수용액으로 이러한 용존염류를 제거하여 담수를 얻는 방법으로는 증발법, 냉동법 등과 같이 물의 상변화를 이용하는 방법과 역삼투압법, 전기투석법과 같이 분리막을 이용하여 압력차, 전위차로 분리하는 방법이 실용화되어 있다. 이중에서 역삼투압법은 상변화가 필요없기 때문에 소요에너지가 적고 장치가 Compact하여 설치비 및 설치부지가 적게 든다는 이점을 가지고 있으며, 특히 최근에는 우수한 분리막의 개발 및 공정기술의 향상으로 다른 공정들에 비해 경쟁력을 갖게 되었다.