• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.5
• /
• pp.567-577
• /
• 2016

The hutches which are installed in the beamline are largely classified into two, i.e XPP (X-ray pump probe) and CXI (Coherent X-ray image). Laser room is installed on the hutch and provides laser to XPP and CXI simultaneously. And two hutches have heavy crane to install some optics equipments. Safety and reliability of hutch structures should be taken into account for the precise operating of the laser facilities, so vibration analysis is essential to do this. The main purpose of vibration analysis is to install hutch structures with large stiffness. We have changed materials specification several times to install hutch structures having strong stiffness. Now hutch structures were installed and checked vibration status at laser room and XPP hutch. The results of laser table and robot arm satisfy vibration criteria. This paper explains about the design and vibration analysis of hutch structures.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.3B
• /
• pp.253-262
• /
• 2006

The present paper presents a direct numerical simulation of turbulent flows in a compound open-channel. Mean flows and turbulence structures are provided, and they are compared with the numerical data and measured data available in the literature. The simulated results show that twin vortices are generated near the juncture of the main channel and the floodplain and their maximum magnitude is about 5% of bulk streamwise velocity. At the juncture, the simulated wall shear stress becomes the maximum unlike the experimental data. A quadrant analysis shows that both sweeps and ejections become the main contributor to production of Reynolds shear stresses. A conditional quadrant analysis reveals that the directional tendency of dominant coherent structures determines the production of Reynolds shear stress and the pattern of twin vortices.

• The Journal of the Acoustical Society of Korea
• /
• v.26 no.8
• /
• pp.381-389
• /
• 2007

In this paper, the measuring method of underwater acoustic communication channel characteristics in the shallow water using the autocorrelation characteristic of PN sequence and the undorwater communication channel analysis results from the received signal sample data are described. For measuring the underwater acoustic communication channel characteristics, two PN sequences are used as a transmitted data of I-channel and Q-channel of QPSK symbol and QPSK signal is transmitted with symbol rate of 5 kHz and carrier frequency of 25 kHz. In the receiver the received signal, which pass through 675 m and 1492 m, is sampled and then stored. Using the stored sample data, the scattering function, coherent time, delay power profile, spaced-tone autocorrelation function, delay spread, and coherent bandwidth of each propagation distance cases are analyzed. Based on the analysis results, several guidelines are suggested for the design and implementation of underwater transmission system.

• Proceedings of the IEEK Conference
• /
• 2002.07a
• /
• pp.536-539
• /
• 2002

The use of concatenated codes in noncoherent synchronous optical fiber CDMA networks is proposed. The concatenated code sequences are generated using balanced Walsh code sequences and Walsh code sequences. The selection of balanced Walsh code sequences is presented and the design of fully programmable transmitter and receiver is reported. The analysis of the system BER performance shows that multiple-access interference is completely eliminated and the BER performance of the proposed system is better than that of the non-coherent synchronous optical fiber CDMA system using optical orthogonal codes with double hard-limiters.

• Journal of Industrial Technology
• /
• v.17
• /
• pp.153-160
• /
• 1997

This paper has analyzed the performance against a single tone jamming for the CPM DS-SS system with a Binary FSK Modulation. The CPM DS-SS system designed with the different phase shift of the same pseude-noise code has the advantage of reducing the jamming and interference effects on multi-users communication environment. Analytical results show that the system preformance improves by increasing parrallel users in the presence of the coherent single-tone, which is the worst interference since the jamming signal has the same frequency as a carrier.

• Proceedings of the KOSOMBE Conference
• /
• v.1995 no.11
• /
• pp.257-261
• /
• 1995

Confocal laser scanning microscopy (CLSM)는 기존의 coherent or incoherent microscopic imaging 보다 횡축 방향 (lateral direction)으로 고해상도를 가지며, 층과 층 사이를 구분하는 광축 방향 (axial direction)의 optical sectioning에 의해 샘플의 3D 구조를 고해상도로 영상화함으로써 3D 구조 및 생체 기능 분석을 가능하게 해 준다. 본 논문에서는 CLSM에 의한 3D 영상화 원리와 촛점면 부근에서 얻어지는 광세기 분포, 얻어진 2D slice 영상의 시각화 및 응용에 대해 논의된다.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.21 no.48
• /
• pp.153-164
• /
• 1998

본 논문은 2-상태 시스템의 신뢰도 계산을 위하여 Heidtmann[3]이 제시한 가역 알고리즘을 부울 대수를 사용하여 경로집합으로부터 절단집합을 유도하거나, 역으로 절단집합으로부터 경로집합을 유도함으로서 효율성을 입증하였으며, 포함-불포함 공식(inclusion-exclusion formula)과 추축 분해법칙(pivotal decomposition rule)을 이용하여 직·병렬구조 및 복합구조의 신뢰도를 계산할 수 있는 알고리즘을 개발, 분석하였다.

• Journal of the Optical Society of Korea
• /
• v.12 no.1
• /
• pp.7-12
• /
• 2008

Directional emission of light exiting a photonic crystal waveguide by a coherent action of radiative surface modes was recently demonstrated, and subsequently the substantial enhancement of the directional emission was achieved by engineering the surface and adjusting relevant parameters. Here we present the analysis of surface modes causing the enhanced emission by the plane wave expansion method and the finite-difference time-domain method. In particular, surface band structures are calculated for nonradiative and radiative surface modes, respectively, and intensity profiles of some representative modes for nonradiative and radiative cases are given.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.94-97
• /
• 1998

In this paper we derive the pdf for the envelope of the received signal in Nakagami fading environment. Then, using this pdf we analyze the performance of Noncoherent FSK and DPSK in Nakagami fading channel. For ASK it is difficult to find the threshold value in Nakagami fading we confine our discussion in the special case of m=1, which is in Rayleigh fading.

• Proceedings of the KAIS Fall Conference
• /
• 2006.05a
• /
• pp.397-400
• /
• 2006

본 논문에서는 DSP를 이용하여 코히어런트 레이더에 사용될 수 있는 확장성이 용이한 디지털 펄스 압축기를 시간영역에서 설계하고 그 내용을 분석하였다. 수신 거리 셀 및 FIR 필터 탭(tap) 수에 따른 펄스압축 연산시간을 ADSP21060을 사용하여서 분석함으로써, 설계하고자하는 레이더 시스템 요구 파라미터 들이 정해지는 경우 펄스압축기 구성에 소요되는 DSP의 수행 기능과 소요 수를 쉽게 예측할 수 있도록 운용특성을 분석하였다.