• Smart Structures and Systems
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• 제12권3_4호
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• pp.363-379
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• 2013

Dynamic displacement of structures is an important index for in-service structural condition and behavior assessment, but accurate measurement of structural displacement for large-scale civil structures such as long-span bridges still remains as a challenging task. In this paper, a vision-based dynamic displacement measurement system with the use of digital image processing technology is developed, which is featured by its distinctive characteristics in non-contact, long-distance, and high-precision structural displacement measurement. The hardware of this system is mainly composed of a high-resolution industrial CCD (charge-coupled-device) digital camera and an extended-range zoom lens. Through continuously tracing and identifying a target on the structure, the structural displacement is derived through cross-correlation analysis between the predefined pattern and the captured digital images with the aid of a pattern matching algorithm. To validate the developed system, MTS tests of sinusoidal motions under different vibration frequencies and amplitudes and shaking table tests with different excitations (the El-Centro earthquake wave and a sinusoidal motion) are carried out. Additionally, in-situ verification experiments are performed to measure the mid-span vertical displacement of the suspension Tsing Ma Bridge in the operational condition and the cable-stayed Stonecutters Bridge during loading tests. The obtained results show that the developed system exhibits an excellent capability in real-time measurement of structural displacement and can serve as a good complement to the traditional sensors.

• Advances in Energy Research
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• 제1권2호
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• pp.97-106
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• 2013

This study designs and tests a photovoltaic system with distributed maximum power point tracking (DMPPT) methodology using a field programmable gate array (FPGA) controller. Each solar panel in the distributed PV system is equipped with a newly designed DC/DC converter and the panel's voltage output is regulated by a FPGA controller using PI control. Power from each solar panel on the system is optimized by another controller where the quadratic maximization MPPT algorithm is used to ensure the panel's output power is always maximized. Experiments are carried out at atmospheric insolation with partial shading conditions using 4 amorphous silicon thin film solar panels of 2 different grades fabricated by Chi-Mei Energy. It is found that distributed MPPT requires only 100ms to find the maximum power point of the system. Compared with the traditional centralized PV (CPV) system, the distributed PV (DPV) system harvests more than 4% of solar energy in atmospheric weather condition, and 22% in average under 19% partial shading of one solar panel in the system. Test results for a 1.84 kW rated system composed by 8 poly-Si PV panels using another DC/DC converter design also confirm that the proposed system can be easily implemented into a larger PV power system. Additionally, the use of NI sbRIO-9642 FPGA-based controller is capable of controlling over 16 sets of PV modules, and a number of controllers can cooperate via the network if needed.

• 한국가스학회지
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• 제23권5호
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• pp.52-58
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• 2019

본 연구에서는 국내 도시가스 인수량에 대한 예측 모델을 개발하였다. 국내의 도시가스 회사는 KOGAS에 차년도 수요를 예측하여 보고해야 하므로 도시가스 인수량 예측은 도시가스 회사에 중요한 사안이다. 도시가스 사용량에 영향을 미치는 요인은 용도구분에 따라 다소 상이하나, 인수량 데이터는 용도별 구분이 어렵기 때문에 특정 용도에 관계없이 영향을 주는 요인으로 외기온도를 고려하여 모델개발을 실시하였다.실험 및 검증은 JB주식회사의 2008년부터 2018년까지 총 11년 치 도시가스 인수량 데이터를 사용하였으며, 전통적인 시계열 분석 중 하나인 ARIMA(Auto-Regressive Integrated Moving Average)와 딥러닝 기법인 LSTM(Long Short-Term Memory)을 이용하여 각각 예측 모델을 구축하고 두 방법의 단점을 최소화하기 위하여 다양한 앙상블(Ensemble) 기법을 사용하였다. 본 연구에서 제안한 일별 예측의 오차율 절댓값 평균은 Ensemble LSTM 기준 0.48%, 월별 예측의 오차율 절댓값 평균은 2.46%, 1년 예측의 오차율 절댓값 평균은 5.24%임을 확인하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.347-352
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• 2006

Narrowband interference can severely degrade the performance of GPS receivers. Detecting the presence of interference and then characterizing it can lead to its removal. Receivers can be reconfigured to focus on other signals or satellites that are less vulnerable to that interference at that moment. Using hardware reconfigurability of FPGA receivers and characterizing the effect of narrowband interference on the GNSS signal quality lead us to a new RFI mitigation technique in which the highest quality and less vulnerable signal can be chosen at each moment. In the previous work [1], the post processing capability of a software GPS receiver, has been used to detect and characterize the CW interference. This is achieved by passing the GPS signal and the interference through the correlator. Then, using the conventional definition of C/No as the squared mean of the correlator output divided by its variance, the actual C/No for each satellite is calculated. In this work, first the 'Exclusion zone' for each satellite signal has been defined and then by using some experiments the effects of different parameters like signal power, jamming power and the environmental noise power on the Exclusion zone have been analyzed. By monitoring the Doppler frequency of each satellite and using the actual C/No of each satellite using the traditional definition of C/No and actual data from a software GPS receiver, the decision to reconfigure the receiver to other signal can be made.

• 한국정보과학회논문지:소프트웨어및응용
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• 제33권11호
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• pp.953-964
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• 2006

협력 필털링은 그 유용성으로 인해 현재 학문적으로나 상업적으로 널리 사용되고 있지만 확장성 문제, 평가 데이타의 희박성 문제, 초기 평가 문제 둥을 안고 있다. 본 논문에서는 이러한 문제들을 일부 해결하기 위해 에이전트 간 협력에 기초한 분산 협력필터링 방법을 제안하였다. 제안 방법에서는 사용자의 평가정보를 에이전트가 지역 데이타베이스에 보관하고 이 정보를 친구들에게만 전파하는 방법을 사용함으로써 사용자 증가에 따른 확장성 문제를 해결하고자 하였다. 그리고 평가 데이타 부족에 따른 추천질 저하를 줄이기 위해 친구 에이전트의 의견을 반영하는 방법을 사용하였고 새로운 사용자에 대해서도 추천이 가능토록 하기 위해 사용자 프로파일을 이용한 협력필터링 방법을 사용하였다. 실험결과, 본 제안 방법이 확장성뿐만 아니라 데이타 희박성 문제 및 새로운 사용자 문제에도 도움이 됨을 확인할 수 있었다.

• Journal of Biosystems Engineering
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• 제41권4호
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• pp.373-388
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• 2016

Background: Recent inquiries into high-quality foods have discussed the importance of the functional aspects of foods, in addition to traditional quality indicators such as color, firmness, weight, trimming loss, respiration rate, texture, and soluble solid content. Recently, functional Chinese cabbage, which makes up a large portion of the vegetables consumed in Korea, has been identified as an anticancer treatment. However, the investigation of practical issues, such as the effects of storage conditions on quality indicators (including functional compounds), is still limited. Purpose: We reviewed various studies on variations in the quality indicators and functional compounds of Chinese cabbage in response to different storage environments, focusing on storage temperature and storage period. In particular, we emphasized the effect of storage temperature and storage period on glucosinolate (GSL) levels, in order to provide guidelines for optimizing storage environments to maximize GSLs. Additionally, we used response surface methodology to propose experimental designs for future studies exploring the optimal storage conditions for enhancing GSL contents. Review: Large variations in quality indicators were observed depending on the cultivar, the type of storage, the storage conditions, and the harvest time. In particular, GSL content varied with storage conditions, indicating that either low temperatures or adequate air composition by controlled atmospheric storage may preserve GSL levels, as well as prolonging shelf life. Even though genetic and biochemical approaches are preferred for developing functional Chinese cabbage, it is important to establish a practical method for preserving quality for marketability; a prospective study into optimal storage conditions for preserving functional compounds (which can be applied in farms), is required. This may be achievable with the comprehensive meta-analysis of currently published data introduced in this review, or by conducting newly designed experiments investigating the relationship between storage conditions and the levels of functional compounds.

• The Korean Journal of Physiology and Pharmacology
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• 제8권1호
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• pp.51-55
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• 2004

Sopungsungi-won has been used as a traditional medicine for diabetes and it has been proved to be a potential remedy for type 2 diabetes mellitus. We previously reported that water extract of Sopungsungi-won exhibits anti-diabetic effects both in vivo and in vitro experiments. In the present study, we have chosen to examined anti-apoptotic effect of Rheum undulatum, which is the main component of Sopungsungi-won, on pancreatic ${\beta}-cells$, HIT-T15, against hydrogen peroxide $(H_2O_2)$. oxidative stress. To investigate the anti-apoptotic effect of Rheum undulatum water extract (RUWE) against $H_2O_2-induced$ apoptosis in pancreatic ${\beta}-cell$ line of hamster, HIT-T15, MTT assay, DAPI staining, TUNEL assay, RT-PCR and caspase-3 enzyme assay were performed. The morphological analysis demonstrated that cells treated with $H_2O_2$ exhibited classical apoptotic features, while such changes was reduced in cells pre-treated with RUWE. In addition, RUWE pre-treated cells prior to $H_2O_2$ treatment induced increase of levels of bcl-2 expression and decrease of caspase-3 enzyme activity compared to cells treated with $H_2O_2$ only. These results provide the possibility of usage of RU in patients with progressively deteriorated diabetes.

• 한국정보과학회논문지:시스템및이론
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• 제31권12호
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• pp.673-681
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• 2004

디지털 비디오의 사용이 보편화되면서 비디오에 대한 효율적인 브라우징이나 검색의 요구가 증가하게 되었다. 이러한 연산을 지원하기 위해서는 효과적인 비디오 인덱싱이 결랍되어야 한다. 비디오 인덱싱에서 가장 기초적인 단계의 하나는 비디오론 샷과 장면으로 파싱하는 것이다. 일반적으로, 비디오 파싱은 복잡한 연산을 필요로 하기 때문에, 기존의 단일 컴퓨터 환경에서는 많은 시간이 소요된다. 기존의 연구는 일정한 시간 동안에 각 슬레이브들에게 작업을 할당하는 라운드 로빈 방식을 사용하였다. 그러나 이러한 방식은 이질적인 환경에서는 적용하는데 어려움이 있다. 본 논문에서는 이질적인 분산 컴퓨팅 환경에서 사용가능한 병렬 파싱 알고리즘인 사이즈 적응적인 라운드 로빈과 동적으로 사이즈 적응적인 라운드 로빈 방식을 제안하였다 성능을 비교하기 위해 몇 가지 실험을 하였으며, 그 결과를 분석하였다.

• 전기학회논문지
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• 제66권6호
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• pp.955-961
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• 2017

In this paper, we propose a parallel approximate string matching algorithm with k-mismatches for multiple fixed-length patterns (PMASM) in DNA sequences. PMASM is developed from parallel single pattern approximate string matching algorithms to effectively calculate the Hamming distances for multiple patterns with a fixed-length. In the preprocessing phase of PMASM, all target patterns are binary encoded and stored into a look-up memory. With each input character from the input string, the Hamming distances between a substring and all patterns can be updated at the same time based on the binary encoding information in the look-up memory. Moreover, PMASM adopts graphics processing units (GPUs) to process the data computations in parallel. This paper presents three kinds of PMASM implementation methods in GPUs: thread PMASM, block-thread PMASM, and shared-mem PMASM methods. The shared-mem PMASM method gives an example to effectively make use of the GPU parallel capacity. Moreover, it also exploits special features of the CUDA (Compute Unified Device Architecture) memory structure to optimize the performance. In the experiments with DNA sequences, the proposed PMASM on GPU is 385, 77, and 64 times faster than the traditional naive algorithm, the shift-add algorithm and the single thread PMASM implementation on CPU. With the same NVIDIA GPU model, the performance of the proposed approach is enhanced up to 44% and 21%, compared with the naive, and the shift-add algorithms.

• 정보보호학회논문지
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• 제28권1호
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• pp.85-93
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• 2018

생체 정보를 이용한 사용자 인증은 차세대 인증 방법으로서 기존의 인증 시스템에서 급진적으로 사용되고 있는 인증 방법이다. 대부분의 생체 인증 시스템은 수집된 생체 정보가 가지는 노이즈로 인한 문제, 데이터의 품질에 대한 문제, 인식률의 한계 등 많은 문제점들을 가지고 있다. 이를 해결하기 위한 방법으로 본 논문에서는 비선형적인 실제 데이터를 정확하게 처리하기 위해 비선형기법인 Dual QML을 사용하고, 또한 정확한 영역을 추출하여 인증의 정확도를 증가시키는 전처리 과정을 추가로 제안하여 정확도 증가뿐만 아니라 성능을 향상시키는 방법을 제안하고자 한다. 앞서 발표된 Dual QML은 생체 정보로 얼굴, 장문, 귀를 사용하였다. 본 논문은 앞선 Dual QML 실험에 사용하지 않은 홍채를 생체 정보로 사용하여 홍채 인식을 위한 방법으로도 Dual QML이 우수하다는 것을 보이고자 한다. 마지막으로 실험을 통해 이에 대한 실증을 보이고자 한다.