• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.450-451
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• 2008

In this paper, we have designed the Anti-Reflection (AR) coating for 850, 1310 nm(multi type) and 1310, 1550 nm(multi type) wavelength ranges on the ferrule facet of special optical connector. The reflectance of the AR coated ferrule facet is designed under 5% for 850, 1310 nm(multi type) and 1310, 1550 nm (multi type). AR thin film was deposited by ion- assisted deposition in low temperature. The average return loss of the AR coated ferrule facet is 47.1 dB.

• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.227-231
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• 2011

An external optical modulation using absorption s in a Fabry-Perot laser diode (FP-LD), has been proposed and experimentally demonstrated for multicasting in a WDM-PON. The center wavelengths of absorption s in an FP-LD move to short-wavelength rapidly by only a small current (~1 mA) injection. If the current injection is stopped, the s move back to the original position. Such a movement of the s can make the FP-LD act as an external optical modulator, which is found to modulate at a maximum modulation speed of 800 Mbps or more. For a multicasting transmitter in a WDM-PON, the proposed modulator can be cost-effectively applied to a multi-wavelength laser source with the same periodicity of the longitudinal mode. Instead of the multi-wavelength laser source, tunable-LDs are used for experiments. The 32 channel multicasting system with the proposed modulator has been demonstrated, showing power penalties of 1.53~4.15 dB at a bit error rate of $10^{-9}$ with extinction ratios better than 14.5 dB at 622 Mbps.

• ETRI Journal
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• v.28 no.5
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• pp.631-637
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• 2006

In this paper we study the optimization issues of ring networks employing novel parallel multi-granularity hierarchical optical add-drop multiplexers (OADMs). In particular, we attempt to minimize the number of control elements for the off-line case. We present an integer linear programming formulation to obtain the lower bound in optimization, and propose an efficient heuristic algorithm called global bandwidth resource assignment that is suitable for the design of large-scale OADM networks.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.8 s.350
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• pp.1-14
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• 2006

Multi-constraint QoS routing has been seen as crucial network property in the next generation optical Internet based on DWDM Networks. This paper proposes a new QoS routing algorithm based on flooding method, called bounded flooding routing (BFR) algorithm which can meet multi-constraint QoS requirements. Primarily, the BFR algorithm tries to reduce network overhead by accomplishing bounded-flooding to meet QoS requirements, and improve blocking probability and wavelength utilization. Also, as one effort to improve routing performance, we introduce a new concept, ripple count, which does not need any link-state information and computational process. For extensive analysis and simulation study, as a critical concern, in DWDM-based networks we deploy limited wavelength conversion capability within DWDM nodes. And the simulation results demonstrate that the BFR algorithm is superior to other predominant routing algorithms (both original flooding method and source-directed methods) in terms of blocking probability, wavelength channels required and overhead.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.821-822
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• 2010

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.166-167
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• 2001

과장 변환기는 WDM (wavelength division multiplexing) 시스템에서 wavelength relocation을 가능하게 하여 시스템의 유연성과 효율성을 향상시킨다는 측면에서 매우 중요한 기능을 갖는다. WDM 시스템의 채널의 수가 점차 증가함에 따라 채널의 간격이 100 GHz에 이르고 있으며 향후 더욱 조밀해 질것이다. 이러한 DWDM (Dense WDM)시스템에서 사용될 수 있는 파장변환기는 100 GHz단위의 파장변환 기능과 광대역 가변 변위가 필수적이다. (중략)

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.79.3-80
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• 2015

Galaxy overdensities such as galaxy clusters and superclusters are the largest gravitationally bound systems in the Universe. Since they contain many different levels of local densities, they are excellent places to test galaxy evolution models in connection to the environments. The environment studies of galaxies at z ~ 1 are important because the environmental quenching seems to be an important mechanism to reduce star formation activities in galaxies at z < 1. However, there have been not many studies about high redshift galaxy clusters at z ~ 1 because of the lack of wide and deep multi-wavelength data. We have used the multi-wavelength data from the UKIDSS DXS (J and K band), the SWIRE (4 IRAC bands), and the PAN-STARRS (g, r, i, z, y bands) in the ELAIS-N1 field. We identified galaxy cluster candidates at 0.2 < z < 1.6 using the multi-wavelength data. We found several superclusters where cluster candidates are concentrated on few tens of Mpc scale. Interestingly, some of the supercluster candidates consist of galaxy clusters which have high blue galaxy. We will present high redshift galaxy cluster and supercluster candidates in ELAIS-N1 field and galaxy properties in different environments including dense clusters and fields.

• Journal of Korea Multimedia Society
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• v.2 no.4
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• pp.451-458
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• 1999

This paper considers the problem of routing connections in multi-optical tree network using WDM (Wavelength Division Multiplexing), where each connection between a pair of nodes in the network is assigned a path through the network and a wavelength on that path, such that connections whose paths share a common link in the network are assigned different wavelengths. The problem of optimal colouring of paths on multi-optical network is NP-hard[1], but if that is the colouring of all paths, then there exists an efficient polynomial time algorithm. In this paper, using divided & conquer method we gave an efficient algorithm to assign wavelengths to the all paths of a tree network based on the theory of (7) and our time complexity $O(n^4log\; n)$.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.31.4-32
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• 2018

The ADF-S (AKARI Deep Field - South) toward South Ecliptic Pole is one of the deep survey fields designed for the study of Cosmic Infrared Background (CIB). Owing to the easy accessibility with space missions and its low background brightness, the deep extragalactic survey was initiated by AKARI deep far-infrared observations and it will be performed by other future missions (e.g., Euclid, NISS, SPHEREx). The recent optical survey with KMTNet enabled us to identify the optical counterparts for dusty star-forming galaxies such as ULIRG, DOG, SMG. In addition, the NISS will perform the valuable spectro-photometric survey in the ADF-S. Those multi-wavelength data sets helps to trace the major galaxy population contributing to the CIB. Here, we introduce the extragalactic survey with the NISS and report the current status of the multi-wavelength extragalactic studies in the ADF-S.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.34.2-34.2
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• 2021

SPT-CL J2106-5844 is the most massive galaxy cluster at z>1 discovered to date. It has been known to be an isolated system with a singular, well-defined halo. However, recent studies provide lines of evidence for its merging state. We strengthen the case with the multi-wavelength observations from ALMA, ACA, ASKAP, ATCA, and Chandra. With the sensitive, high resolution ALMA+ACA observations, we reconstruct the ICM pressure map from the thermal SZ effect. It reveals two main gas components that are associated with the mass clumps inferred from the weak-lensing analysis. Furthermore, the X-ray hardness map supports the bimodal gas distribution. With these multi-wavelength data, we probe the merger phase in SPT-CL J2106-5844.