• The Journal of Engineering Research
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• v.2 no.1
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• pp.103-111
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• 1997

EDFA (Erbium Doped Fiber Amplifier) is widely used to compensate the loss in fiber optic transmission system. The characteristics of EDFA are investigated by analyzing the mechanism amplifying the optical power of an input with several factors to obtain the criteria for designing EDFA. When it is used in fiber optic transmission system, signal to noise characteristics in the receiver is deteriorated due to the spontaneous emission noise of EDFA. We investigate the operating conditions of EDFA to reduce BER (Bit Error Rate).

• Mineral and Industry
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• v.15 no.1
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• pp.15-24
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• 2002

납석은 전남 일대를 중심으로 약 5,200만 톤이 부존 되어 있고 매년 약 80-90만 톤씩 생산되고 있어 , 국내 비금속광 중 생산액 순으로 4위 정도를 차지하고 있다. 수요의 대부분은 국내에서 조달하고, 생산량의 약 30% 정도를 수출하고 있지만 최근에는 고품위 광석을 중심으로 수입이 증가하는 추이를 보이고 있다. 방석의 국내 수요도 과거에는 내화벽돌용이 주를 이루었지만 근래에는 유리 장성유용이 가장 큰 시장역할을 하는 것으로 변모하였다. 물량만으로는 시멘트 부원료용이 가장 많지만 가격이 낮아 시장규모는 별로 크지 못하다. 시장가격을 기준으로 추정한 국내 납석시장의 규모는 수출시장을 포함할 경우 200억 원 규모이지만 소수의 상위 생산광산에서 주요한 시장을 차지하고 있어 다수의 소규모 광산들은 약 40억원 정도의 시장을 두고 경쟁하고 있다. 납석은 저가 광물인 만큼 고부가가치화를 시키려는 노력이 필요하며, 다량 부존되어 있는 저품위광을 활용하기 위한 노력과 다른 비금속광물과의 경쟁력을 지닐 수 있도록 분체물을 처리하는 분야의 연구 역시 필요할 것이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.854-855
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• 2013

최근 국내 전력공급 문제에 따라 다양한 에너지절감형 기술과 제품이 연구되고 있다. 특히 국내 기준 전체 전력 소비량의 약 20%를 차지하는 조명분야에서는 기존 조명을 대체할 친환경, 고효율 LED 조명에 대한 기술이 대두되고 있다. LED 조명은 원리의 특성상 광효율과 비례하여 LED 접합부 온도가 상승하며 이는 광효율과 수명을 저하시킨다. 이에 다양한 방열기술이 LED 조명기술의 핵심이라 할 수 있다. 본 논문에서는 LED 모듈 접합부의 발열을 열전소자를 활용하여 열전발전 함으로써 에너지를 절감하고, 열회수를 통한 방열효과를 제공 하는 LED 조명을 제안한다.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.68-69
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• 2017

본 논문에서는 독립형 태양광 시스템의 설계에서 배터리 용량 선정 방식에 관련하여 부하손실확률(LLP: Loss of Load Probability)이 0 인 기준을 토대로 시스템 무정전 전력공급을 위한 시행 착오법을 제안하였으며 시스템의 수명주기비용(LCC: Life Cycle Cost)을 분석하여 기존 시스템에 비해 경제성을 높이고자 한다. 제안한 방식의 검증을 위하여 시뮬레이션을 수행하였다.

• Fire Science and Engineering
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• v.12 no.3
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• pp.11-20
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• 1998

A new experimental technique using a laser sheet and thermocouples is introduced to evaluate an intuitive criterion for tracking of a smoke front using thermocouples. From synchronized photos of the smoke front along with temperature signals, the intuitive criterion is shown to be acceptable. Smoke visualization by a laser sheet proves to have several advantages over the conventional techniques such as the use of smoke generators.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.311-321
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• 2019

With Korean Government's Renewable energy 3020 plan and 8th Basic plan for long-term power supply, renewable energy industries in Korea are active and catching attention from many relevant industry's relations. Especially with Interconnection guarantee policy established in Oct, 2016, DERs interconnection delay due to lack of allowable distribution hosting capacity is happening and reduction of reinforcement cost for distribution system where 70 % of DERs in South Korea are installed became one of important issues of KEPCO. Therefore, KEPCO needed to extract reasonable solutions to increase feasible hosting capacity of distribution feeders in order to reduce reinforcement cost under the condition of no matter in distribution system operation. This paper proposes feasible hosting capacity of distribution feeders that can be adopted and the status of DER installation in distribution system, PV output data, minimum load in distribution feeders as well as capacity of distribution lines have been investigated and analyzed in proof of the proposal.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.4
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• pp.362-370
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• 2001

In this paper, we proposed multispectral image compression method using CIP (classified inter-channel prediction) and SVQ (selective vector quantization) in wavelet domain. First, multispectral image is wavelet transformed and classified into one of three classes considering reflection characteristics of the subband with the lowest resolution. Then, for a reference channel which has the highest correlation and the same resolution with other channels, the variable VQ is performed in the classified intra-channel to remove spatial redundancy. For other channels, the CIP is performed to remove spectral redundancy. Finally, the prediction error is reduced by performing SVQ. Experiments are carried out on a multispectral image. The results show that the proposed method reduce the bit rate at higher reconstructed image quality and improve the compression efficiency compared to conventional methods. Index Terms-Multispectral image compression, wavelet transform, classfied inter-channel prediction, selective vetor quantization, subband with lowest resolution.

• Korean Journal of Optics and Photonics
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• v.26 no.2
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• pp.73-82
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• 2015

This work demonstrates the indoor SI-traceable calibration of a transmissometer with a 75-m baseline for the measurement of visibility in MOR (Meteorological Optical Range). The calibration is performed using a set of neutral density (ND) filters (OD 0.1-2.5) and a set of high-transmission quartz glass plates (a bare quartz glass plate and antireflective-coated quartz glass plates), the collection consisting of 20 artifacts in total. The luminous transmittance values of the reference artifacts had been calibrated traceable to the KRISS spectral transmittance scale, which ranges from 0.2 % to 99.5 %. The transmissometer to be calibrated typically consists of a loosely collimated light source based on a white LED (CCT ~5000 K) and a luminous intensity detector with a CIE 1924 V(${\lambda}$) spectral response. As a result of calibration, we obtained the MOR error and its uncertainty for the transmissometer in 20 m - 40 km of MOR. Based on the results, we investigated the applicability of the calibration method and the conformity of the transmissometer to the ICAO's (International Civil Aviation Organization) accuracy requirement for meteorological visibility measurement. We expect that this work will establish the standard procedure for the SI-traceable calibration of a transmissometer.

• Journal of Astronomy and Space Sciences
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• v.24 no.1
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• pp.79-90
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• 2007

The AmonRa instrument, the primary payload of the international EARTHSHINE mission, is designed for measurement of deep space albedo from L1 halo orbit. We report the optical design, tolerance analysis and the optical performance of the breadborad AmonRa imaging channel instrument optimized for the mission science requirements. In particular, an advanced wavefront feedback process control technique was used for the instrumentation process including part fabrication, system alignment and integration. The measured performances for the complete breadboard system are the RMS 0.091 wave(test wavelength: 632.8 nm) in wavefront error, the ensquared energy of 61.7%($in\;14\;{\mu}m$) and the MTF of 35.3%(Nyquist frequency: $35.7\;mm^{-1}$) at the center field. These resulting optical system performances prove that the breadboard AmonRa instrument, as built, satisfies the science requirements of the EARTHSHINE mission.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.809-819
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• 2004

In this paper, in order to exclude the expansion of M/W relay frequency or its new frequency assignment possibly, we analyzed a possibility of substituting M/W system by B-WLL or optical fiber network regarding service quality and economical points. To define the target of service quality, pre-condition and analysis method for the selected media have been derived to compare each other. E1 transmission with BER 10$^{-1}$ was chosen as a reference capacity, and service distance was calculated f3r the selected media as a function of availability. Also from the economical point we considered 3 systems such as optical fiber, M/W, and B-WLL based upon basic system structure, and analyzed them for various line configurations of fiber optic and B-WLL according to service period, system capacity, transmission distance, and data rate. It was confirmed that B-WLL can provide quality of service with 99.999 % availability within 1.6 km cell radius, and for optical fiber substitution, the leased fiber conduit on an electric pole is more economical than M/W system irrespective of service period, but in case of directly digging for underground conduit, it turned out ineffective regardless of cabling duct types.