• Transactions of the KSME C: Technology and Education
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• v.4 no.1
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• pp.19-26
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• 2016

This paper presents the measurement and analysis results for the performance of HGCHP system using a cooling tower as a supplemental heat rejector. In order to demonstrate the performance of the hybrid approach, we installed the monitoring equipments including sensors for measuring temperature and power consumption, and measured operation parameters from February 1, 2014 to February 28, 2015. Leaving load temperatures to building showed an average value of $11.7^{\circ}C$ for cooling and $39.5^{\circ}C$ for heating, respectively. From the analysis, the daily PF of hybrid GCHP system varied from 2.6 to 6.6 over the measurement period.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.189-190
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• 2021

자율운항선박의 원활한 개발을 위해 선박 조타 지연에 관하여 선박선회성능으로 시험해 그 결과를 알아보고, 추후 지연 시간에 따른 조타 실험을 계획해 발전에 기여한다.

• The Journal of the Acoustical Society of Korea
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• v.17 no.3
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• pp.59-64
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• 1998

본 논문에서는 LSP 벡터 양자화의 성능에 대하여 분석하고 성능이 향상된 새로운 LSP 벡터 양자화 방법을 제안한다. 먼저, 10msec프레임 구조를 가지고 Moving Average 예측 필터를 사용한 LSP Split 벡터 양자화의 성능을 여러 훈련 방법과 벡터 Split 방법 및 Bit 할당 방법에 따라 비교한다. 다음, Split 벡터 양자화의 문제점을 해결하기 위하여 새로 운 Split 벡터 양자화 검색 방법을 제안한다. 스펙트럼 왜곡지수를 이용한 양자화 성능 측정 결과 새로 제안된 방법이 기존의 방법보다 우수한 양자화 성능을 보인다.

• Journal of Korea Multimedia Society
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• v.11 no.4
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• pp.462-470
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• 2008

This study applies fuzzy functions to improve image quality under the assumption that uncertainty of image information due to low contrast is based on vagueness and ambiguity of the brightness pixel values. To solve the problem of low contrast images whose brightness distribution is inclined, we use the k-means algorithm as a parameter of the fuzzy function, through which automatic critical points can be found to differentiate objects from background and contrast between bright and dark points can be improved. The fuzzy function is presented at the three main stages presented to improve image quality: fuzzification, contrast enhancement and defuzzification. To measure improved image quality, we present the fuzzy index and entropy index and in comparison with those of histogram equalization technique, it shows outstanding performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.831-839
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• 2012

In this paper, an exponential model of Korea is proposed to minimize an altitude-error of high-altitude target due to atmosphere refraction at radar system. The relation between surface refractivity and refractivity gradient, which is extracted using the least square fit from the measured data at 7 weather stations, is applied to the exponential model. And in order to verify the proposed model, the altitude-errors for a standard atmosphere, a CRPL(Central Radio Propagation Lab.) exponential model, the proposed model are extracted and analyzed using a ray tracing. As a result, the proposed model can improve the altitude estimation performance of radar compared to conventional atmosphere refractive index models.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.502-502
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• 2007

A catenary system should be designed to have an uniform elasticity over a span in order to maintain the lowest possible loss of contact between a pantograph and a contact wire. A elasticity uniformity of a catenary can be regarded as a important design factor used for predicting the current collection performance for a catenary. There are a couple of formulas to calculate the degree of elasticity uniformity of a catenary according to the literature survey. The effectiveness of these formulas is reviewed by performing catenary elasticity and loss of contact analysis for various different configurations of catenary systems using a beam element based FEM program. The results reveals that these formulas are not suitable to predict the current collection performance for a catenary. Therefore, a new formula based on the standard deviation of the elasticity over a span is proposed in this study. The analysis results show that the new formula for an elasticity uniformity of a catenary is very effective in predicting the current collection performance for a catenary.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1095-1102
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• 1991

In this paper, we proposed the differential demodulation technique of 2-h CPM and analyzed its error performances. We derived the sets of modulation indices of 2-h phase codes adequate to the differential detection. The power spectra of 2-h CPM signals with various sets of mudulation indices are illustrated and compared, Besides, the error performances for the differential detectors are calculated and detectors using Viterbi algorithm are compared and analyzed by computer simulations.

• Proceedings of the Korea Contents Association Conference
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• 2005.11a
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• pp.359-363
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• 2005

본 논문에서는 다양한 무선 통신 채널 환경에서 레일리 페이딩과 라이시안 페이딩 등을 모두 포함할 수 있고 이동 통신과 위성 통신에서도 적용할 수 있는 페이딩 모델로서 나카가미 페이딩 모델을 도입하고 전자기기에서 방출되는 임펄스 간섭파를 채널 환경으로 모델링하여 결합변조기법을 채용한 DS-CDMA 시스템의 성능을 분석하였다. 변조방식으로는 대역폭 효율 개선을 위해 MFSK와 MDPSK를 고려한 결합변조기법을 채용하였으며 실내 무선 페이딩 채널로써 직접파대 반사파 전력비를 나카가미 페이딩 심도지수 m으로 산출하여 임펄스 지수A와 가우스 잡음 전력 대 임펄스 잡음 전력비 $\Gamma'$를 파라미터로 하여 시스템 오율성능을 분석하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.22-25
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• 2011

본 연구에서는 경제성에 기반한 초고층건물 구조시스템의 대안평가 방안에 대하여 연구하였다. 초고층건물 구조시스템의 대안평가 항목은 크게 구조성능, 경제성, 공기의 세 가지로 나눌 수 있다. 일반적으로 구조성능은 주어진 기준의 만족여부로 평가하며, 최종적으로는 경제성이 평가에 결정적인 영향을 미치게 된다. 본 연구에서는 구조성능을 만족하는 대안에 대하여 공기를 비용으로 환산하고, 최종적으로는 물량에 의한 비용과 공기에서 환산된 비용을 합산하여 대안을 평가하는 방안을 제안하였다. 공기의 비용화는 공기의 비용연동지수를 구하고 이로부터 공기의 대체경제성비용을 산정하는 방법으로 고려하였다. 제안된 대안평가 과정은 수많은 대안을 짧은 시간에 평가할 수 있도록 전산시스템 구현가능성을 염두에 두고 구축하였다.

• Fire Science and Engineering
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• v.23 no.5
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• pp.66-71
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• 2009

In this study, I evaluated toxicity that analyze performance of flame-retardant about flame-retardant painting wood and combustion gas that is based on the toxicity index. Processing condition of flame retardant solution and treatment method of samples didn't affect greatly to performance of flame retardant. Occurrence of combustion gas showed a almost similar result from the sample which spraying flame retardant solution and toxicity corresponds to high level, Hazard Class III, and the flame retardant solution saturation sample which makes put out Hazard Class II which is a low toxicity relatively.