• 한국건축시공학회지
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• 제14권5호
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• pp.415-422
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• 2014

본 연구는 공공건축물의 실적공사비 분석을 통해 총공사비에 대한 적정보정율을 기초자료로 제시하고자 한다. 이에 대해 조달청에서 발주한 2009~2011년에 준공된 53개 프로젝트를 연구 대상으로 하였다. 공사비 분석은 주요 공정인 건축, 기계, 전기, 통신, 부대시설에 대하여 빈도론적 관점에서 중위수를 활용한 절대오차율을 기반으로 총공사비에 대해 비교 분석하였다. 이를 통해 적합회귀모형을 선정하고 보정율을 책정하였다.

• 한국위성정보통신학회논문지
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• 제9권2호
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• pp.110-113
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• 2014

본 논문에서는 가우시안 이진 대칭 채널에서 쇄상부호를 사용할 때의 최적 내 외 부호율에 관하여 연구한다. 쇄상부호의 전체 부호율이 고정되어 있을 때, 내 부호율이 감소할수록 내 부호의 오류 검출 능력은 향상되지만, 반대로 외 부호의 오류 정정 능력은 감소하게 된다. 이러한 trade-off 관계를 이용하여 본 논문에서는 쇄상부호의 최대 성능 이득을 얻기 위한 내 부호와 외 부호에의 최적의 중복(redundancy) 분포에 관하여 연구한다. 분석한 결과, 가우시안 이진 대칭 채널에서는 외 부호화율을 최소화하고 내 부호화율을 최대화함으로써 전체 쇄상부호 시스템의 성능을 극대화 시킬 수 있음을 알 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.224-227
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• 2008

The present study performs a test of a change in a condenser pressure on two kinds of power plants having different condenser pressure-heat rate correction curve and evaluates the results. According to a result of the test, it is confirmed that a sub-critical drum type steam power plant is optimally operated at the condenser pressure of 38㎜Hga that is designed, even during winters. On the other hand, it can be found that a supercritical once through type steam power plant operated at the condenser pressure that is reduced below a design value, that is, up to 28㎜Hga during winters is advantageous in view of turbine efficiency and is operated without a problem in facility operation such as moisture erosion, turbine vibration, etc. Also, the present study compares and reviews a condenser pressure-heat rate correction curve proposed by a manufacturer and a test value. The present study proposes optimum condenser operation pressure capable of concurrently satisfying the stable operation and efficiency improvement of the power plant facility that is operating, making it possible to support an efficient operation of a power plant.

• Asian Journal of Atmospheric Environment
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• 제11권2호
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• pp.107-113
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• 2017

This study describes (1) the impact of positive sampling artifacts caused by not only a filter-based sampling, but also a denuder-based sampling in the determination of particle-phase organic carbon (POC), (2) the effect of sample flow rate on positive artifacts, and (3) an optimum flow rate that provides a minimized negative sampling artifact for the denuder-based sampling method. To achieve the goals of this study, four different sampling media combinations were employed: (1) Quartz filter-alone (Q-alone), (2) quartz filter behind quartz-fiber filter (QBQ), (3) quartz filter and quartz filter behind Teflon filter (Q-QBT), and (4) quartz filter behind carbon-based denuder (Denuder-Q). The measurement of ambient POC was carried out in an urban area. In addition, to determine gas-phase OC (GOC) removal efficiency of the denuder, a Teflon filter and a quartz filter were deployed upstream and downstream of the denuder, respectively with varying sample flow rates: 5, 10, 20, and 30 LPM. It was found that Q-alone sampling configuration showed a higher POC than QBQ, Q-QBT, and Denuder-Q by 12%, 28%, and 23%, respectively at a sample flow rate of 20 LPM due to no correction for positive artifact caused by adsorption of GOC onto the filter. A lower quantity of GOC was collected from the backup quartz filter on QBQ than that from Q-QBT. This was because GOC was not in equilibrium with that adsorbed on the front quartz filter of QBQ during the sampling period. It is observed that the loss of particle number and mass across the denuder increases with decreasing sample flow rate. The contribution o f positive arti facts to POC decreased with increasing sample flow rate, showing 29%, 25%, and 22% for 10, 20, and 30 LPM, respectively. The 20 LPM turns out to be the optimum sample flow rate for both filter and denuder-based POC sampling.

• The Journal of Asian Finance, Economics and Business
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• 제7권11호
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• pp.127-135
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• 2020

This study aims to measure the effects of real interest rate (RIR), gross domestic savings (GDS), and net exports (EN) shocks on Indonesia's economic growth (EG). The focus on Indonesia is unique due to the abundant resources available in the nation, but they are unsuccessful in boosting economic growth. This study applied a quantitative method to comprehensively analyze the correlation between variables by employing Vector Autoregression Model (VAR) combined with Vector Error Correction Model (VECM). Various procedures are preformed: Augmented Dickey-Fuller test (ADF), Optimum Lag Test, Johansen Cointegration Test, Granger Causality Test, as well as Impulse Response Function (IRF) and Error Variance Decomposition Analysis (FEVD). The data were collected from the World Bank and the Asian Development Bank from 1986 to 2017. The findings of the study indicated that economic growth responded positively to real interest rate shocks, which implies that when the real interest rate experiences a shock (increase), the economy will be inclined to growth. While, economic growth responded negatively to gross domestic savings and net export shocks. Policymakers are expected to consider several matters, particularly the economic conditions at the time of formulating policy, so that the prediction effectiveness of a policy can be appropriately assessed.

• 대한원격탐사학회지
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• 제35권6_1호
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• pp.907-917
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• 2019

최근 국토 모니터링, 지형 분석 등 많은 분야에서 고해상도 위성영상의 수요가 증가와 함께 기하보정의 필요성이 증가하고 있다. 자동 정밀 기하보정 방법으로 GCP(Ground Control Point) 칩과 위성영상간의 정합을 통해 지상기준점을 자동으로 추출하는 방법이 있다. 자동 정밀 기하보정은 GCP 칩과 위성영상의 정합 성공률이 중요하다. 따라서 제작된 GCP 칩의 정합 성능 평가가 중요하다. GCP 칩의 정합 성능 평가를 위해 국토관측 위성용으로 구축된 총 3,812점의 GCP 칩을 실험 자료로 사용했다. KOMPSAT-3A 영상과 Google Map의 GCP칩 정합 결과를 분석한 결과 유사한 결과를 얻을 수 있었다. 따라서 Google Map 위성영상으로 고해상도 위성영상을 충분히 대체할 수 있다고 판단했다. 또한 GCP 칩의 정합 성능 검증에 필요한 시간을 줄이기 위해 자동화된 방법으로 Google Map의 중심점과 오차 반경을 이용한 방법을 제시했다. 실험 결과 최적의 오차 반경은 17 pixel(약 8.5 m)로 설정하는 것이 가장 좋은 분류 정확도를 보였다. Google Map 위성영상과 자동화된 검증 방법으로 남한 전역에 구축된 GCP 칩 3,812개의 정합 성능 평가를 진행했으며 남한에 구축된 GCP 칩은 약 94%의 정합 성공률을 보였다. 이후 정합에 실패한 GCP 칩을 분석하여 주요 정합 실패원인을 분석하였다. 분석 결과 남한 전역에 구축된 GCP 칩 중 재제작이 필요한 GCP 칩을 제외한 나머지 GCP 칩은 국토위성영상 자동 기하보정에 충분히 사용할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권6호
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• pp.1463-1479
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• 2013

In this paper, we propose an unequal protection physical coding sub-layer (PCS) forward error correction (FEC) scheme for efficient and high-quality transmission of video data over optical access networks. Through identifying and resolving the unequal importance of different video frames and passing this importance information from MAC-layer to PCS, FEC scheme of PCS can be adaptive to application-layer data. Meanwhile, we jointly consider the different channel situations of optical network unit (ONU) and improve the efficiency of FEC redundancy by channel adaptation. We develop a theoretical algorithm and a hardware method to achieve efficient FEC assignment for the proposed unequal protection scheme. The theoretical FEC assignment algorithm is to obtain the optimal FEC redundancy allocation vector that results in the optimum performance index, namely frame error rate, based on the identified differential importance and channel situations. The hardware method aims at providing a realistic technical path with negligible hardware cost increment compared with the traditional FEC scheme. From the simulation results, the proposed Channel and Application-layer data Adaptation Unequal Protection (CAAUP) FEC scheme along with the FEC ratio assignment algorithm and the hardware method illustrates the ability of efficient and high-quality transmission of video data against the random errors in the channel of optical access networks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권5호
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• pp.1316-1332
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• 2012

Formation flying is an important technology that enables high cost-effective organization of outer space aircrafts. The ad-hoc wireless network based on direct-sequence ultra-wideband (DS-UWB) techniques is seen as an effective means of establishing wireless communication links between aircrafts. In this paper, based on the theory of matched filter and error bits correction, a hybrid detection algorithm is proposed for realizing multiuser detection (MUD) when the DS-UWB technique is used in the ad-hoc wireless network. The matched filter is used to generate a candidate code set which may contain several error bits. The error bits are then recognized and corrected by an novel error-bit corrector, which consists of two steps: code mapping and clustering. In the former step, based on the modified optimum MUD decision function, a novel mapping function is presented that maps the output candidate codes into a feature space for differentiating the right and wrong codes. In the latter step, the codes are clustered into the right and wrong sets by using the K-means clustering approach. Additionally, in order to prevent some right codes being wrongly classified, a sign judgment method is proposed that reduces the bit error rate (BER) of the system. Compared with the traditional detection approaches, e.g., matched filter, minimum mean square error (MMSE) and decorrelation receiver (DEC), the proposed algorithm can considerably improve the BER performance of the system because of its high probability of recognizing wrong codes. Simulation results show that the proposed algorithm can almost achieve the BER performance of the optimum MUD (OMD). Furthermore, compared with OMD, the proposed algorithm has lower computational complexity, and its BER performance is less sensitive to the number of users.

• 대한전자공학회논문지
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• 제27권4호
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• pp.491-501
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• 1990

Recently, four speech coding techniques, namely, SBC-APCM(sub-band coding adaptive PCM), RPE-LPC(regualr pulse excitation linear predictive codec), MPE-LTP(multi-pulse excited long-term prediction) and CELP (code-excited linear prediction) are proposed for digital mobile radio applications. However, a performance comparison of these coders in the Rayleigh fading environment has not been made yet. In this paper, the performances of the four spech coders in the random bit error and burst error environment are investigated. For the channel coding of SBC-APCM, RPE-LPC and MPE-LTP, the sensitivity of output bit stream is measured and a bit selective forward error correction is provided acording to the measured bit sensitivity. And for an attempt to improve the performance of CELP, an optimum quantizer is applied for transmitting scalar quantities in CELP. However, an improvement over the conventional approach is found to be negligible. For the channel coding of CELP, Reed-Solomon code, Golay code, convolutional code of rate 1/2 shows the best performance. Finally, from the simulation results, it is concluded that CELP is the best candidate for digital mobile radio and is followed by MPE-LTP, SBC-APCM and RPE-LPC.

• 한국재료학회지
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• 제28권12호
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• pp.685-690
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• 2018

In this study, a multifunctional ophthalmic lens material with an electromagnetic shielding effect, high oxygen permeability, and high water content is tested, and its applicability is evaluated. Metal oxide nanoparticles are applied to the ophthalmic lens material for vision correction to shield harmful electromagnetic waves; the pyridine group is used to improve the antibacterial effect; and silicone substituted with urethane and acrylate is employed to increase the oxygen permeability and water content. In addition, multifunctional tinted ophthalmic lens materials are studied using lens materials with an excellent antibacterial effect (2,6-difluoropyridine, 2-fluoro-4-pyridinecarboxylic acid) and functional (UV protection, high wettability) lens materials (2,4-dihydroxy benzophenone, 2-hydroxy-4-(methacryloyloxy)benzophenone). To solve problems such as air bubbles generated during the polymerization process for the manufacturing and turbidity of the lens surface, polymerization conditions in which the defect rate is minimized are determined. The results show that the polymerization temperature and time are most appropriate when they are $110^{\circ}C$ and 40 minutes, respectively. The optimum injection amount of the polymerization solution is 350 ms. The turbid phenomenon that appears in lens processing is improved by 10 to 95 % according to the test time and conditions.