• 한국지반환경공학회 논문집
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• 제21권1호
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• pp.5-12
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• 2020

지진원으로부터 전파되는 진동은 거리에 따른 감쇠와 지형 혹은 지질구조에 따라 지역마다 다른 증·감폭 특성을 가진다. 지진원에서 기반암까지의 전파되는 진동은 이격거리에 따른 감쇠의 영향이 크며, 이는 감쇠식을 통해 쉽게 추정할 수 있다. 하지만 지표면에 전달되는 진동 추정은 기반암 상부에 위치한 토층 고유주기의 영향을 받기에 위치별 지질정보 파악이 중요하다. 지질정보 기반 진도 추정을 위해 지반조사 자료가 필요하며, Vs 주상도가 없을 경우 표준관입시험을 통해 대상지반의 강도 및 특성 파악에 주로 사용된다. 국토지반정보 포털시스템에서는 국내 지반에서 수행된 지반조사자료를 통합하여 관리하고 있으며, 표준관입시험 정보가 약 40만공을 구축되어 있다. 본 연구에서는 지반정보를 기반으로 체감형 진도정보 산출을 위해 권역별로 증폭계수 정량화 가능성을 검토하였다. 이때 SPT-N치를 자료를 통해 전단파 주상도를 생성하고, 대상지역에 지반응답해석을 수행하였다. 권역별 증폭계수와 지진파의 주기별 진도 분포는 해석방법 및 권역설정에 따라 큰 차이를 보였다.

• 한국콘텐츠학회논문지
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• 제21권7호
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• pp.127-133
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• 2021

산업용 IoT 환경에서 센서들은 감지하고 있는 대상의 데이터들을 연속으로 생성하며, IoT 게이트웨이에 전달한다. 따라서 대량의 실시간 센서 데이터를 관리하는 것은 IoT 게이트웨이에 필수적인 기능이며 이러한 센서 데이터를 관리하기 위해 키-값 스토리지 엔진들이 널리 사용되고 있다. 그러나 IoT 게이트웨이에 사용되는 키-값 스토리지 엔진들은 산업용 IoT 환경에서 생성되는 센서 데이터들의 특징을 고려하지 않고 있으며 이 때문에 제한된 성능을 보인다. 본 논문에서는 산업용 IoT 환경에서 센서 데이터의 특징을 활용하여 키-값 스토리지 엔진을 최적화한다. 제안하는 최적화 기법은 키-값 스토리지 엔진의 입력인 키를 분리하여 계층적인 색인화 작업을 하는 것이다. 이를 통해 과도하게 발생하는 쓰기 증폭을 줄이며 성능을 향상 시킬 수 있다. 이러한 최적화 기법을 LevelDB에 구현하였으며, 제안하는 기법을 평가하기 위해 TPCx-IoT의 워크로드를 사용했다. 실험 결과에 따르면 제안하는 기법의 성능은 기존의 방법보다 21배 더 좋으며 이는 제안하는 기법이 산업용 IoT 환경에서 데이터 수집을 고속으로 처리할 수 있음을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.2966-2986
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• 2023

Climate change is a constant threat to human life, and it is important to understand the public perception of this issue. Previous studies examining climate change have been based on limited survey data. In this study, the authors used big data such as news articles and social media data, within which the authors selected specific keywords related to climate change. Using these natural language data, topic modeling was performed for discourse analysis regarding climate change based on various topics. In addition, before applying topic modeling, sentiment analysis was adjusted to discover the differences between discourses on climate change. Through this approach, discourses of positive and negative tendencies were classified. As a result, it was possible to identify the tendency of each document by extracting key words for the classified discourse. This study aims to prove that topic modeling is a useful methodology for exploring discourse on platforms with big data. Moreover, the reliability of the study was increased by performing topic modeling in consideration of objective indicators (i.e., coherence score, perplexity). Theoretically, based on the social amplification of risk framework (SARF), this study demonstrates that the diffusion of the agenda of climate change in public news media leads to personal anxiety and fear on social media.

• Annals of Clinical Neurophysiology
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• 제19권2호
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• pp.113-117
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• 2017

The performance of electroencephalogram (EEG) recordings is affected by electrode type, electronic parameters such as filtering, amplification, signal conversion, data storage; and environmental conditions. However, no single method has been identified for optimal EEG recording quality in all situations. Therefore, we aimed to provide general principles for EEG electrode selection as well as electronic noise reduction, and to present comprehensive information regarding the acquisition of satisfactory EEG signals. The standards provided in this document may be regarded as Korean guidelines for the clinical recording of EEG data. The equipment, types and nomenclature of electrodes, and the details for EEG recording are discussed.

• International Journal of Oral Biology
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• 제45권3호
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• pp.77-83
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• 2020

In the oral cavity, complex microbial community is shaped by various host and environmental factors. Extensive literature describing the oral microbiome in the context of oral health and disease is available. Advances in DNA sequencing technologies and data analysis have drastically improved the analysis of the oral microbiome. For microbiome study, bacterial 16S ribosomal RNA gene amplification and sequencing is often employed owing to the cost-effective and fast nature of the method. In this review, practical considerations for performing a microbiome study, including experimental design, molecular analysis technology, and general data analysis, will be discussed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.31-35
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• 2000

A cantilever deflection measurement system for AFM(atomic force microscope) was constructed by the laser deflection method using LEP type PSD. Design process including sensitivity analysis was presented and the performance of the system was demonstrated by several experiments using a sample specimen with 50nm-step on the surface. The measured displacement-amplification-factor showed good agreement with the expected one with about 8% deviation. The step height measurement data were compared to what were acquired by commercial AFM, and the result showed that there were about 5nm-deviation between the two data. These results satisfies our expectation in the stage of system design.

• ETRI Journal
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• 제28권1호
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• pp.1-8
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• 2006

A novel all-optical gain-controlled (AOGC) bidirectional amplifier is proposed and demonstrated in a compact structure. The AOGC function using fiber Bragg grating (FBG) pairs controls both directional signals independently, and combinations of optical interleavers and isolators suppress Rayleigh backscattering (RB) noise. The amplifier achieves high and constant gain with a wide dynamic input signal range and low noise figure. The performance does not depend on the input signal conditions, whether static-state or transient signals, or whether there is symmetric or asymmetric data traffic on bidirectional transmission. Transmission comparison experiments between invariable symmetrical and random variable asymmetric bidirectional data traffic verify that the all-optical gain control and bidirectional amplification functions are successfully combined into this proposed amplifier.

• Journal of Information Processing Systems
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• 제10권3호
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• pp.459-470
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• 2014

In this paper, the average probability of the symbol error rate (SER) and throughput are studied in the presence of joint spectrum sensing and data transmission in a cognitive relay network, which is in the environment of an optimal power allocation strategy. In this investigation, the main component in calculating the secondary throughput is the inclusion of the spatial false alarms, in addition to the conventional false alarms. It has been shown that there exists an optimal secondary power amplification factor at which the probability of SER has a minimum value, whereas the throughput has a maximum value. We performed a Monte-Carlo simulation to validate the analytical results.

• 제어로봇시스템학회논문지
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• 제12권5호
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• pp.419-424
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• 2006

In this study, a thermal control system which applied a Peltier device for the polymerase chain reaction(PCR) machine is to be designed. Here in order for it to easily follow the characteristics of the thermal cycle existing for gene amplification of the PCR sample, a PCR control board utilizing a thermal sensor, a Peltier, and a 8 bit microprocessor is made up. Especially a fuzzy type PD control algorithm is applied periodically in time response, and control system is implemented. For that matter, the characteristic data of subject system is obtained and analysed to begin with. Based on this analysed data, the proposed control algorithm is applied and an evaluation of the performance of the whole system take place through the PC.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.439-440
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• 2006

This paper presents precise measurement system for the lifetime of OLED. The proposed system collects the data for using voltage drop across the OLED Panels, and then the computer program makes an analysis of the data. In this process of measurement, the current across OLED material must be amplified because the current is very small. However, amplifying the current causes the amplification of noise. Therefore, the proposed system measures the current using an algorithm which minimizes the noise.