• 대한산업공학회지
• /
• 제30권3호
• /
• pp.213-223
• /
• 2004

We consider the traffic grooming problem for the design of SONET/WDM(Synchronous Optical NETwork/Wavelength Division Multiplexing) ring networks. Given a physical network with ring topology and a set of traffic demands between pairs of nodes, we are to obtain a stack of rings with the objective of minimizing the number of ADMs installed at the nodes. This problem arises when a single ring capacity is not large enough to accommodate all the demands. As a solution method, an efficient algorithm based on the branch-and-price approach has been reported in the literature for the problem in which only unidirecional path switched ring (UPSR) was considered. In this study, we suggest integer programming models and the algorithms based on the same approach as the above one, considering two-fiber bidirectional line switched ring(BLSR/2), and BLSR/4 additionally. Using the results, we compare the number of required ADMs for all types of the ring architecture.

• 한국경영과학회지
• /
• 제22권2호
• /
• pp.13-29
• /
• 1997

This paper considers a new routing problem, successive max-min connection ratio problem (SMCRP), arised in circuit telecommunication networks such as SONET and WDM optical transport network. An optimization model for SMCRP is established based on link-flow formulation. It's first optimization process is an integral version of maximum concurrent flow problem. Integer condition does not give the same connection-ratio of each node-pair at an optimal solution any more. It is also an integral multi-commodity flow problem with fairness restriction. In order to guarantee fairness to every node-pair the minimum of connection ratios to demand is maximized. NP- hardness of SMCRP is proved and a heuristic algorithm with polynomial-time bound is developed for the problem. Augmenting path and rerouting flow are used for the algorithm. The heuristic algorithm is implemented and tested for networks of different sizes. The results are compared with those given by GAMS/OSL, a popular commercial solver for integer programming problem.n among ferrite-pearlite matrix, the increase in spheroidal ratio with increasing fatigue limitation, 90% had the highest, 14.3% increasing more then 70%, distribution range of fatigue.
ife was small in same stress level. (2) $\sqrt{area}_{max}$ of graphite can be used to predict fatigue limit of Ductile Cast Iron. The Statistical distribution of extreme values of $\sqrt{area}_{max}$ may be used as a guideline for the control of inclusion size in the steelmaking.

• 한국주조공학회지
• /
• 제18권6호
• /
• pp.550-554
• /
• 1998

The microstructures of rapidly solidified binary Ti-Al alloys containing $45{\sim}58\;at%Al$ have been studied using C/S (carbon/sulfur), N/O (nitrogen/oxygen) analyser, X-ray fluorescence spectrometer (XRF), X-ray diffractometer (XRD), optical microscope (OM) and scanning electron microscope (SEM). The phases present in the alloys and their distribution were found to be a sensitive function of Al content. Essentially single-phase (${\gamma}$) microstructures were observed to alloys with 45 at%Al, 55 at%Al and 58 at%Al. In other content alloys, two phase (${\alpha}_2$, ${\gamma}$) microstructures were observed. The 48 at%Al, 52 at%Al alloys contain (${\gamma}+{\alpha}_2$) phase and ${\alpha}_2$ phase. These results indicate that rapid solidification affect the solidification path, then metastable phase forming during solidification.

• 한국연소학회지
• /
• 제1권1호
• /
• pp.75-82
• /
• 1996

Laser induced incandescence, LII, recently developed technique for measuring soot concentration in flames, can overcome most of limitations of conventional laser extinction measurement. In this study, experiments were performed to investigate the effect of laser intensity, detection wavelength, and also laser beam quality on both LII signal at a particular position and peak-to-centerline LII signal ratio. The results of LII signal with increasing laser intensity shows its near-independence of laser intensity once threshold level of laser intensity has been reached. However, this near-independence depends on laser beam quality and the incident optical setup. The peak-to-centerline LII signal ratio slowly but continuously increases with laser power. This fact is due to the dependence of LII signal on particle mean diameter. LII signal is attenuated during it passes through the flame containing soot particles. The attenuation rate is inversely proportional to detection wavelength. In this study, LII signal at 680 nm band is 10% greater than the signal at 400 nm band.

• 한국항공우주학회지
• /
• 제39권7호
• /
• pp.682-687
• /
• 2011

일반적으로 탑재 교정을 위한 교정 반사경 구동장치는 교정임무 수행 시에는 주광경로 상의 전개위치로 반사경을 구동하며, 교정 후에는 주광경로와 이격된 수납위치로 반사경을 구동한다. 교정 반사경 구동장치의 결함 발생 시에는 반사경이 전개된 상태로 남아 주광경로를 차단하지 않도록 반사경을 강제 수납한다. 본 논문에서 제안한 결함 안전장치를 가지는 교정용 반사경 구동장치는 구동을 위한 스텝모터, 전개 및 수납 상태확인을 위한 마이크로 스위치, 베어링과 스프링의 기능을 동시에 갖는 피봇베어링 등으로 구성된다. 본 논문에서는 상기의 기능을 갖는 교정 반사경 구동장치 구현을 위한 구동장치 구성을 제안하였으며, 구성요소의 최적화 설계치를 도출하고 기능시험을 통해 결함안전 기능을 갖는 교정 반사경 구동장치의 유효성을 검증하였다.

• 한국전기전자재료학회논문지
• /
• 제24권1호
• /
• pp.32-35
• /
• 2011

Top-emission device has a merit of high aperture ratio and narrow emission spectrum compared to that of bottom-emission one. Emission spectra of top-emission organic light-emitting diodes depending on a layer thickness and view angle were analyzed using a theory of microcavity. Device structure was manufactured to be Al (100 nm)/TPD/$Alq_3$/LiF (0.5 nm)/Al (2 nm)/Ag (30 nm). N,N'-diphenyl-N,N'- di (m-tolyl)-benzidine (TPD) and tris (8-hydroxyquinoline) aluminium (Alq3) were used as a hole-transport layer and emission layer, respectively. And a thickness of TPD and Alq3 layer was varied in a range of 40 nm~70 nm and 60 nm~110 nm, respectively. Angle-dependent emission spectrum out of the device was measured with a device fixed on a rotating plate. Since the top-emission device has a property of microcavity, it was observed that the emission spectrum shift to a longer wavelength region as the organic layer thickness increases, and to a shorter wavelength region as the view angle increases. Layer thickness and view-angle dependent emission spectra of the device were analyzed in terms of microcavity theory. A reflectivity of semitransparent cathode and optical path length were deduced.

• 한국정밀공학회지
• /
• 제15권5호
• /
• pp.93-99
• /
• 1998

Although laser interferometer measurement system has advantages of measurement range and accuracy, it has some disadvantages when measurement of multi degrees of freedom of motion are required. Because the traditional error measurement methods for geometric errors (two straightness and three angular errors) of a slide of machine tools measures error components one at a time. It may also create an optical path difference and affect the measurement accuracy. In order to identify and compensate for geometric errors of a moving rigid body in real time processes, an on-line error measurement system for simultaneous detection of the five error components of a moving object is required. Using laser alignment technique and some optoelectronic components, an on-line measurement system with 5 degrees of freedom was developed for the geometric error detection in this study Performance verification of the system has been performed on an error generating mechanism. Experimental results show the feasibility of this system for identifying geometric errors of a slide of machine tools.

• Progress in Superconductivity
• /
• 제6권2호
• /
• pp.95-98
• /
• 2005

We present results of Raman spectroscopic studies of superconducting $YBa_2Cu_3O_7$ (YBCO) coated conductors. Raman scattering is used to characterize optical phonon modes, oxygen content, c-axis misalignment, and second phases of the YBCO coated conductors at a micro scale. A two-dimensional mapping of Raman spectra with transport properties has been performed to elucidate the effect of local propertied on current path and superconducting phase. The information taken from the local measurement will be useful for optimizing the process condition.

• 한국전자파학회논문지
• /
• 제25권11호
• /
• pp.1190-1196
• /
• 2014

본 논문은 넓은 고도 범위와 낮은 측정 오차를 갖는 주파수 변조 연속파(FMCW) 레이더 고도계의 설계 방안을 제안한다. 측정 고도의 동적 범위를 줄이기 위해 전파 고도계의 송신 경로에 광 지연선을 적용하여 넓은 고도 범위를 얻을 수 있다. 송신 전력과 수신단 이득을 제어하여 또한 수신 전력의 동적 범위를 줄일 수 있다. 더불어, 직접 디지털 합성기를 사용하여 변조 선형성을 향상시키고, 기준 클럭 신호를 위상 고정 루프의 옵셋(offset) 주파수로 사용하여 위상잡음을 최소화함으로써 낮은 고도 측정오차를 갖는다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.103.1-103.1
• /
• 2014

Due to their excellent optical and electrochemical properties, conjugated polymers have attracted much attention over the last two decades and employed to opto-electrical devices. In particular, conjugated polymers possess many attractive features that make them suitable for a variety of sensing task. For example, their delocalized electronic structures can be strongly modified by varying the surrounding environment, which significantly affected molecular energy level. In other word, conjugated polymers can detect and transduce the environmental information into a fluorescence signal. Conjugated polymers also display amplified quenching compared to small molecule counterparts. This amplified fluorescence quenching is attributed to the delocalization and migration of the excitons along the conjugated polymer backbones. Long backbones of conjugated polymer provide the transporting path for electron as a conduit, allowing that excitons migrate rapidly into quencher site along the backbone. This is often referred to as the molecular wire effect or antenna effect. Moreover, structures of conjugated polymers can be easily tailored to adjust solubility, absorption/emission properties, and regulation of electron/energy transfer. Based on this versatility, conjugated polymers have been utilized to many novel sensory platforms as a promising material. In this tutorial, I will highlight a variety of fluorescence sensors base on conjugated polymer and explain their sensory mechanism together with selected examples from reference literatures.