• Journal of Positioning, Navigation, and Timing
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• 제11권4호
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• pp.269-277
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• 2022

In this paper, we overview the system development status of the national maritime precise point positioning-real-time kinematic (PPP-RTK) service in Korea, also known as the Precise POsitioning and INTegrity monitoring (POINT) system. The development of the POINT service began in 2020, and the open service is scheduled to start in 2025. The architecture of the POINT system is composed of three provider-side facilities-a reference station, monitoring station, and central control station-and one user-side receiver platform. Here, we propose the detailed functionality of each component considering unidirectional broadcasting of augmentation data. To meet the centimeter-level user positioning accuracy in maritime coverage, new reference stations were installed. Each reference station operates with a dual receiver and dual antenna to reduce the risk of malfunctioning, which can deteriorate the availability of the POINT service. The initial experimental results of a testbed from corrections generated from the testbed network, including newly installed reference stations, are presented. The results show that the horizontal and vertical accuracies satisfy 2.63 cm and 5.77 cm, respectively. For the purpose of (near) real-time broadcasting of POINT correction data, we designed a correction message format including satellite orbit, satellite clock, satellite signal bias, ionospheric delay, tropospheric delay, and coordinate transformation parameters. The (near) real-time experimental setup utilizing (near) real-time processing of testbed network data and the designed message format are proposed for future testing and verification of the system.

• International Journal of Computer Science & Network Security
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• 제22권2호
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• pp.232-240
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• 2022

To fulfill user expectations, the rapid evolution of software techniques and approaches has necessitated reliable and flawless software operations. Aging prediction in the software under operation is becoming a basic and unavoidable requirement for ensuring the systems' availability, reliability, and operations. In this paper, an improved evolutionary computing-driven extreme learning scheme (ECD-ELM) has been suggested for object-oriented software aging prediction. To perform aging prediction, we employed a variety of metrics, including program size, McCube complexity metrics, Halstead metrics, runtime failure event metrics, and some unique aging-related metrics (ARM). In our suggested paradigm, extracting OOP software metrics is done after pre-processing, which includes outlier detection and normalization. This technique improved our proposed system's ability to deal with instances with unbalanced biases and metrics. Further, different dimensional reduction and feature selection algorithms such as principal component analysis (PCA), linear discriminant analysis (LDA), and T-Test analysis have been applied. We have suggested a single hidden layer multi-feed forward neural network (SL-MFNN) based ELM, where an adaptive genetic algorithm (AGA) has been applied to estimate the weight and bias parameters for ELM learning. Unlike the traditional neural networks model, the implementation of GA-based ELM with LDA feature selection has outperformed other aging prediction approaches in terms of prediction accuracy, precision, recall, and F-measure. The results affirm that the implementation of outlier detection, normalization of imbalanced metrics, LDA-based feature selection, and GA-based ELM can be the reliable solution for object-oriented software aging prediction.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권1호
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• pp.261-279
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• 2023

In this article, the uplink achievable rate is investigated for massive multiple-input multiple-output (MIMO) under correlated Ricean fading channel, where each base station (BS) and user are both deployed multiple antennas. Considering the availability of prior knowledge at BS, two different channel estimation approaches are adopted with and without prior knowledge. Based on these channel estimations, a two-layer decoding scheme is adopted with maximum ratio precoding as the first layer decoder and optimal second layer precoding in the second layer. Based on two aforementioned channel estimations and two-layer decoding scheme, the exact closed form expressions for uplink achievable rates are computed with and without prior knowledge, respectively. These derived expressions enable us to analyze the impacts of line-of-sight (LoS) component, two-layer decoding, data transmit power, pilot contamination, and spatially correlated Ricean fading. Then, numerical results illustrate that the system with spatially correlated Ricean fading channel is superior in terms of uplink achievable rate. Besides, it reveals that compared with the single-layer decoding, the two-layer decoding scheme can significantly improve the uplink achievable rate performance.

• 풍력에너지저널
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• 제14권3호
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• pp.34-42
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• 2023

The reduction of operation and maintenance (O&M) costs is a critical factor in determining the competitiveness of wind energy. Predictive maintenance based on the estimation of remaining useful life (RUL) is a key technology to reduce logistic costs and increase the availability of wind turbines. Although a mechanical component usually has sudden changes during operation, most RUL estimation methods use the trend of a state index over the whole operation period. Therefore, overestimation of RUL causes confusion in O&M plans and reduces the effect of predictive maintenance. In this paper, two RUL estimation methods (load based and data driven) are proposed for the bearings of a wind turbine with the results of trend classification, which differentiates constant and increasing states of the state index. The proposed estimation method is applied to a bearing degradation test, which shows a conservative estimation of RUL.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.759-767
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• 2021

최근 전력화되는 무기체계들은 최신 기술이 반영된 고가의 장비가 대다수이며, 운용유지비도 지속적으로 증대되고 있는 추세이다. 이러한 무기체계들을 효율적으로 운용, 유지하는 요소로서는 정비계획, 경제적 비용 및 수리부속 소요 등이 있으며 그 중 수명주기 동안 수리부속 소요를 사전에 예측하는 것이 운용유지비 효율성 증대와 운용가용도를 높이는 중요한 방식이라 할 수 있다. 수리부속 소요 분석의 시작으로는 무기체계 배치 시 동시에 보급되는 동시조달수리부속(CSP: Concurrent Spare Parts, 이하 CSP) 산정이라 할 수 있을 것이다. CSP는 무기체계가 초기 일정기간 동안 재보급 없이 주어진 운용임무를 성공적으로 수행하고자 하는데 목적이 있으므로 이 기간 동안에 운용가용도를 달성하는 필수요소이다. 현재 CSP 산정 방식은 품목의 고장율과 운용 시간 등의 반영하여 분석하고 있지만, 분석된 CSP는 기술적 고장을 대비하는 목적이며, 초도 운용환경에서 휴먼에러 등으로 인한 예기치 않은 고장 발생에 대처하는 부분에서는 제한적인 것이 현실이다. 해당 고장은 무상정비 범위에도 포함되지 않으며, 초도 운용기간 중 무기체계를 운용 불가 상태로 만드는 심각한 요소에 해당된다. 이러한 무기체계의 운용 불가 상태를 예방하기 위하여 초도 운용환경 중 휴먼에러를 고려한 CSP가 필요하며, 그에 대한 산정 방안과 기준을 제시한다.

• 한국식품영양학회지
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• 제34권5호
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• pp.487-497
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• 2021

To investigate the industrial availability of liquid fermentation (PL-ferment) by Phellinus linteus mycelium as a postbiotics for the inhibition of inflammation, PL-ferment was fractionated into culture supernatant (CS), hot-water extract (HW) from PL-ferment, EtOH-precipitate (CP) fractionated from HW, and the dialysate (DCP) of CP. Compared to the other fractions, DCP which is expected to contain exopolysaccharide (EPS) as the major component, significantly decreased the production of NO, IL-6, and MCP-1 in LPS-induced RAW 264.7 cells, and IL-6 and IL-8 in TNF-α and IFN-γ-induced HaCaT cells. The general component analysis results showed that no significant difference in components was observed between the fractions, whereas sugar composition analysis revealed that DCP had decreased glucose and increased mannose contents compared to the other fractions. This suggests that mannose played an important role in the anti-inflammatory activity of the active fraction, DCP. Molecular weight distribution analysis revealed that DCP was mainly composed of low-molecular-weight material-removed high-molecular-weight polysaccharides of 18-638 kDa, suggesting that EPS originated from P. linteus EPS. In conclusion, our results suggest that the DCP of P. linteus mycelium fermentation using the anti-inflammatory activity could be used industrially as postbiotic material.

• 기술혁신학회지
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• 제22권3호
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• pp.362-381
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• 2019

본 논문에서는 기술혁신에 영향을 미치는 요인 중 산업별 혁신시스템과 R&D 지원서비스의 요인이 엔유씨전자의 사례에서 어떻게 작용하는지 살펴보았다. 엔유씨전자는 투입구 변경과 착즙률 개선의 기술혁신을 통해 높은 혁신성과를 달성하였다. 이는 산업별 혁신시스템의 각 구성요소가 엔유씨전자의 기술혁신과 부합하는 측면이 있었기 때문이다. 엔유씨전자의 성과향상은 자체적인 혁신노력과 함께 정부출연연구소의 R&D 지원서비스가 있었기 때문에 가능했다. 기술혁신 과정에서 제품설계와 가상실험 등 기업 스스로 해결할 수 없는 영역의 고차원적인 서비스를 받을 수 있었다. 중소기업에게 부족한 부분을 보완해주는 정부와 공공기관의 지원 역할이 중요했다고 할 수 있다. 산업별 혁신시스템의 각 구성요소별로 보면 새로운 기술기회가 많은 만큼 지속성이 낮다, 모방이 쉽고 전유성이 낮지만 복합적인 측면도 있다, 기술축적의 누적성은 비교적 높은 편이다, 외부지식의 활용 가능성이 높다, 주체와 네트워크 모두 중요한 역할을 하였다, 시장여건이 매우 유리하였다 등으로 요약될 수 있다. R&D 지원서비스의 측면에서는 직접적인 효과로서 스크류의 재질과 형상에 대한 가상실험을 통해 엄청난 시간과 비용의 절약이 이루어졌다는 점을 들 수 있다. 간접적인 효과로서는 외부지원에 의한 기술개발을 계기로 엔유씨전자의 자체적인 핵심역량이 크게 강화되었고 혁신의 선순환구조가 정착되었다는 점을 들 수 있다.

• 한국ITS학회 논문지
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• 제21권6호
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• pp.177-193
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• 2022

장차 자율주행 기술이 접목된 수요응답형 서비스가 새로운 교통수단으로써 널리 퍼질것으로 예측된다. 차량 편의성, 이동/배차 신속성, 플랫폼 편리성 등 여러 서비스 요인을 내포하는 만큼 성공적인 정착을 위해서는 서비스 요소별 우선순위가 파악될 필요가 있다. 이에 본 연구에서는 수요응답형 자율주행 대중교통 서비스의 잠재적 이용자를 대상으로 온라인 설문조사를 통해 서비스 요소별 중요도 순위를 도출하였다. 상위 항목에 대하여 AHP(분석적 계층화과정) 분석 결과, 이동/배차 신속성, 플랫폼 편리성, 차량 편의성 순으로 중요한 것으로 드러났다. 하위 항목에 대하여 평균 순위 분석 결과, 차량 편의성은 차내 혼잡도가, 이동/배차 신속성은 대기시간이, 플랫폼 편리성은 이용시간 예약 가능성이 가장 중요한 것으로 나타났다. 이용자 집단별로 차별화된 접근 전략을 수립하기 위해 집단별 분석도 수행하였다. 그 결과, 고령자층이 많은 지역에 서비스를 도입할 때는 모바일 플랫폼보다 차량에 더 중점을 두고, 자가용 보유자가 많은 지역에서는 기존 대중교통 대비 이동과 배차를 빠르게 처리하고, 차내 혼잡도를 낮추며, 이용시간을 예약할 수 있도록 하는 것이 바람직하다.

• Asian-Australasian Journal of Animal Sciences
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• 제13권6호
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• pp.861-882
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• 2000

The seed, or grain, of modern cultivars of Lupinus angustifolius, commonly known as Australian sweet lupins (ASL), is an established feed resource for the intensive animal industries of Australia, Japan, Korea and several other countries in Asia and Europe. Since the introduction of ASL to the world marketplace about 25 years ago, researchers in many countries have found them to be a valuable component of the diet of beef and dairy cattle, sheep, pigs, poultry, finfish and crustaceans. The seed of ASL contains ~32% crude protein (CP) (~35% DM basis) and 5% oil. The main storage carbohydrates in the seed are the ${\beta}$-galactans that comprise most of the cell-wall material of the kernel and the cellulose and hemicellulose of the thick seed coats. ASL seeds contain about 40% non-starch polysaccharides (NSP) and a negligible amount of starch. This makes them an excellent ingredient for ruminant diets, as the risk of acidosis is very low. The seed of modern cultivars of domesticated Lupinus species contain negligible amounts of lectins and trypsin inhibitors so they do not require preheating before being used as an ingredient in feeds for monogastric species. They have a high digestibility coefficient for protein, >90% for most species, but a low energy digestibility, ~60%, which is mostly due to the high content of NSP. The low content of methionine (0.22%) and of lysine (1.46%) is typical of the legumes. The lysine availability for pigs is >70%. Lupin kernels contain ~39% CP (~42% DM basis), 6% oil and 30% NSP. They have a higher digestible energy for pigs and finfish and a higher metabolisable energy for poultry than whole seed. Commercial operations rarely achieve complete separation of kernel from hull and it is more likely that the kernel fraction, called splits or meats, will contain ~36% CP. The replacement of soybean meal or peas with ASL in cereal-based diets for most intensively reared animals, birds and fish is possible provided lysine, methionine and digestible energy levels are kept constant. This makes ASL economically competitive in many, but not all, circumstances.

• Asian-Australasian Journal of Animal Sciences
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• 제16권4호
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• pp.625-634
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• 2003

Oil palm fronds (OPF) are one of the main by-products of the oil palm industry in Malaysia. It contains about 38.5 % crude fibre with ME values of about 5.65 MJ/kg dry matter. OPF has great potential to be utilized as a roughage source or as a component in a complete feed for ruminant animals. This paper briefly reviews the availability of OPF in Malaysia and its importance in the local beef and dairy industry. About 26 million metric tonnes of OPF are produced on dry matter basis annually during pruning and replanting operations in the plantations. The nutritive value of OPF and studies to improve its feeding value is highlighted. The optimum level of inclusion for ruminant feeding is 30 % and improvement to intake and digestibility can be further enhanced with addition of other oil-palm by-products. Performances of beef and dairy cattle fed fresh OPF or as silage, pellets and cubes are shown. Good quality OPF silage can be produced without using any additive and the significant improvement on the rate of growth and milk yield were shown. With good formulations, OPF based diets can allow live weight gains of between 600-850 g/day and for local crossbred dairy animals, milk yield of about 11.1 to 20.3 liter/day can be obtained. Pellet based on ground OPF seemed to be less well utilized for ruminant feeding due to its smaller particle size. OPF based cubes which have longer particle size is more suitable for beef and dairy cattle. Long-term feeding of OPF based feeds have been shown to produce good quality carcasses, and the meat is safe for consumption.