• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.221-228
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• 1989

The objective of this paper is to develop a numerical technique for analyzing crack driving forces in multi-phase materials. The analysis was based on finite element method coupled with a virtual crack extension technique which is known as the most efficient tool in computational fracture mechanics analysis. The modified J-integral method, proposed by Miyamoto and Kikuchi for the analysis of dual-phase material was carried out by subtracting the J-values for contours surrounding each phase boundary from the J-values for overall contour. It was shown that the proposed numerical procedure, based on the modified J-integral coupled with a virtual crack extension technique, can be used as an effective numerical tool for determining crack driving forces in multi-phase materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3104-3109
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• 2009

The technology of direction finding is very important to find the direction of emitters for ELINT(electronic intelligence) system. The principle of TDOA(time difference of arrival) is to receive an emitter signal with two antennas, measure the time difference between two antennas, and converse the time difference to direction difference. This technology can be used in broadband frequency system and make the system very simple because a phase-discriminator and a voltage comparator are not needed. For fine DF accuracy, high time resolution receiver and long basis line antennas are needed. The DF accuracy of noise added signals is simulated with different time

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.363-368
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• 2003

In this paper, the characteristics of the horn antenna for the high power transfertation system is stuided and several kinds of a horn antenna are compared and finally a conical hem antenna using multi-mode is proposed. In the high power system, the efficiency of power transfer is very important. Therefore the feeding hem of a reflector must have a circular symmetric radiation pattern. And the side lobe must be suppressed to reduce a spillover power loss and interference. By using multi-mode in a circular hem antenna, the whole length can be shorter and the radiation pattern can be adjusted according to the shape and direction of a reflector. This is confirmed by the experiments.

• The Journal of the Korea Contents Association
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• v.4 no.2
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• pp.76-82
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• 2004

The thermal neutron capture cross-section (at 2,200 m/s value) of the $^{141}$Pr(n,$\gamma$)$^{142}$Pr reaction was measured by an activation method by using the heavy water ($D_2$O) thermal neutron facility at the KUR(Kyoto University Reactor). The thermal neutron fiux used in this experiment was monitored with the$^{197}$Au(n,$\gamma$)$^{198}$Au standard cross-section. The previous results and the evaluated data of JENDL-3.2, ENDF/B-VI, and JEF-2.2 were in good agreement with the current result.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.195-201
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• 2016

In this paper, we present the direction finding accuracy of correlative interferometer method and amplitude-phase comparison method. Spiral antennas are used for amplitude-phase comparison method and blade antennas are used for correlative interferometer method. Those are made for uniform circular array (UCA) direction finding antenna systems. We simulate the accuracy of azimuth angle with 3 antennas UCA when SNR is 20 dB and baseline is 0.5 wave length. Correlative interferometer method has better accuracy than amplitude-phase comparison method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.12
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• pp.1100-1107
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• 2015

In this paper, we propose an algorithm to identify Wobble PRI and Sinusoidal PRI among Radar pulses. We applied not only the DTOA(Difference Time Of Arrival) concept of radar pulse signals incoming to antennas but also a rising and falling cub characteristic of those PRIs. After making a program by such algorithm, we input each 40 data to Wobble PRI's and Sinusoidal PRI's identification programs and in result, those programs fully processed the data the according to expectations. In the future, those programs can be applied to the ESM, ELINT system.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.93.1-93.1
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• 2012

세종대 간의대(簡儀臺)는 우리나라 역사상 가장 대규모로 수행된 천문 관련 국책사업의 일환으로 축조된 조선시대의 국립천문대이다. 지금까지 세종대 간의대에 대한 선행 연구는 주로 궁내 위치 및 변화, 개보수 상황 및 중수 여부, 규모와 관련한 주척(周尺) 또는 영조척(營造尺)에 대한 논의 등에 천착하고 있으나 간의대의 외형, 구조, 기능, 역할 등에 대한 연구는 미진한 편이다. 이 중 간의대의 외형에 대한 선행 연구들에서는 원대(元代) 북경 사천대(北京 司天臺, 1279년 전후 축조) 또는 명대(明代) 북경 관성대(北京 觀星臺, 1442년 축조, 現 古觀象臺) 등을 간의대의 원형으로 추정하고 있다. 이 연구에서는 간의대 복원을 위하여 외형에 대한 재해석을 시도하였으며, 이를 위하여 1997년 소더비(Sotheby) 경매 출품본 "경복궁도(景福宮圖)"를 비롯한 각종 경복궁 궁궐도(宮闕圖)를 분석하였다. 또한 구조와 축조 방식의 규명을 위하여 제단(祭壇) 등의 각종 석축물(石築物)을 분석하였으며, 이와 함께 "조선왕조실록"을 비롯한 각종 사료(史料)에 대한 조사를 병행하였다. 이와 같은 연구를 통하여 원대 북경 사천대 또는 명대 북경 관성대와는 다른 세종대 간의대의 독자적인 모델을 제시하였다.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.5
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• pp.329-334
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• 2013

A positioning based service uses one's position information with GPS. This application also use the position based characters and change the smart phone to the vibration mode at the registered position. If the user register some places to be vibrated in the smart phone, the smart phone will be automatically changed to the vibration mode as the registered position is same with the position of GPS in the smart phone. If the smart phone is being leaving some distance from the position, the phone will be released from the vibration mode. Therefore, this paper propose aims for intelligent smart phone.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2528-2533
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• 2010

This paper describes on a software simulator that can be used for an anti-ARM system. The proposed simulator is a valuable tool for investigating the optimum deployment of decoy antennas which are widely using for anti-ARM and calculating the electromagnetic field at the ARM receiver. To verify the effect of decoy antennas, we analyze the field intensity and phase at the receiver. We conduct an analysis of ARM attack in case of using multiple decoy antennas and the proposed simulator can be used to decide the optimum positions of the decoys.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.852-857
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• 2006

This paper presents a precision method to calculate the electric field density of mountain area using digital terrain elevation data(DTED). Generally we calculate the electric field density of a point adding a direct field density and horizontal reflection field density between two points. In this paper, we consider a vertical reflection field density from vertical surface near the wave propagation line between transmitter and receiver. The vertical reflection electric field have different propagation path and polarization from a horizontal reflection field. And the total electric field density adding horizontal field density and vertical reflection value is more accurate than a direct path electrical field density or direct field density adding a horizontal reflection field density.