• Progress in Superconductivity
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• 제9권2호
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• pp.162-166
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• 2008

We are developing a sensitive gamma ray spectrometer based on superconducting transition edge sensors. The detector consists of a small piece of high purity Sn as an absorber and a Ti/Au bilayer as a temperature sensor. It is designed to measure the thermal signal caused by absorption of gamma rays. The mechanical support and the thermal contact between the absorber and the thermometer were made with Stycast epoxy. The bilayer was formed by e-beam evaporation and patterned by wet etching on top of a $SiN_X$ membrane. A sharp superconducting transition of the film was measured near 100 mK. When the film was biased to the edge of the transition, signals were observed due to single photon absorption emitted from an $^{241}Am$ source. The measured spectrum showed several characteristic peaks of the source including 59.5 keV gamma line. The full with at half maximum was about 900 eV for the 59.5 keV gamma line. The background was low enough to resolve low energy lines. Considerations to improve the energy resolution of the gamma ray spectrometer are also discussed.

• 센서학회지
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• 제12권4호
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• pp.164-169
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• 2003

최근에 남북철도나 대륙횡단열차 등에 대한 사업성 타당조사가 이뤄지면서 철도차량에 대한 관심이 높아지고 있다. 타교통수단과 비교하여 철도차량은 환경친화적, 정시성, 신뢰성, 그리고 안전성의 특성이 있다. 우리는 한국형 고속철도차량을 평가하기 위한 하드웨어와 소프트웨어를 제작하였다. 소프트웨어는 측정된 데이터를 분석할 수 있도록 해준다. 이 논문에서는 센서를 사용한 철도차량 전기장치 측정에 관해서 연구하였다. 이 시험을 하기 위해서 신호변환시스템을 개발하였다. 이 계측시스템을 이용해서 가선전압, battery전압, 차축속도 등에 관한 중요한 시험결과를 얻을 수 있었다.

• 한국물환경학회지
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• 제24권1호
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• pp.1-6
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• 2008

Biological and chemical sensors are the two most frequently used sensors to monitor the water resource. Chemical sensor is very accurate to pick up the types and to measure the concentration of the chemical substance. Drawback is that it works for just one type of chemical substance. Therefore a lot of expensive monitoring system needs to be installed to determine the safeness of the water, which costs too much expense. Biological sensor, on the contrary, can judge the degree of pollution of the water with just one monitoring system. However, it is not easy to figure out the type of contaminant with a biological sensor. In this study, an endeavor is made to identify the toxicant in the water using the shape of the chlorophyll fluorescence induction curve (FIC) from a biological monitoring system. Wem-tox values are calculated from the amount of flourescence of contaminated and reference water. Curve fitting is executed to find the representative curve of the raw data of Wem-tox values. Then the curves are digitalized at the same interval to train the neural network model. Taguchi method is used to optimize the neural network model parameters. The optimized model shows a good capacity to figure out the toxicant from FIC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2299-2318
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• 2019

Location-aware networks are of great importance for both civil lives and military applications. Methods based on line-of-sight (LOS) measurements suffer sever performance loss in harsh environments such as indoor scenarios, where sensors can receive both LOS and non-line-of-sight (NLOS) measurements. In this paper, we propose a data association (DA) process based on the expectation maximization (EM) algorithm, which enables us to exploit multipath components (MPCs). By setting the mapping relationship between the measurements and scatters as a latent variable, coefficients of the Gaussian mixture model are estimated. Moreover, considering the misalignment of sensor position, we propose a space-alternating generalized expectation maximization (SAGE)-based algorithms to jointly update the target localization and sensor position information. A two dimensional (2-D) circularly symmetric Gaussian distribution is employed to approximate the probability density function of the sensor's position uncertainty via the minimization of the Kullback-Leibler divergence (KLD), which enables us to calculate the expectation step with low computational complexity. Moreover, a distributed implementation is derived based on the average consensus method to improve the scalability of the proposed algorithm. Simulation results demonstrate that the proposed centralized and distributed algorithms can perform close to the Monte Carlo-based method with much lower communication overhead and computational complexity.

• 한국IT서비스학회지
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• 제22권2호
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• pp.57-70
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• 2023

In order to establish an autonomous driving environment, it is necessary to study traffic safety and demand prediction by analyzing information generated from the transportation infrastructure beyond relying on sensors by the vehicle itself. In this paper, we propose a real-time traffic information generation method using sensor convergence technology of transportation infrastructure. The proposed method uses sensors such as cameras and radars installed in the transportation infrastructure to generate information such as crosswalk pedestrian presence or absence, crosswalk pause judgment, distance to stop line, queue, head distance, and car distance according to each characteristic. create information An experiment was conducted by comparing the proposed method with the drone measurement result by establishing a demonstration environment. As a result of the experiment, it was confirmed that it was possible to recognize pedestrians at crosswalks and the judgment of a pause in front of a crosswalk, and most data such as distance to the stop line and queues showed more than 95% accuracy, so it was judged to be usable.

• 한국산업경영시스템학회:학술대회논문집
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• 한국산업경영시스템학회 2002년도 춘계학술대회
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• pp.387-396
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• 2002

Batch processes are a significant class of processes in the process industry and play an important role in the production of high quality speciality materials. Examples include the production of semiconductors, chemicals, pharmaceuticals, and biochemicals. With on-line sensors connected to most batch processes, massive amounts of data are being collected routinely during the batch on easily measured process variables such as temperatures, pressures, and flowrates. In this paper, multivariate SPC charts for on-line monitoring of the progress of new batches are developed which utilize the information in the on-line measurements in real-time. We propose the formation of statistical model which describes the normal operation of a batch at each time interval during the batch operation. An on-line monitoring scheme based on the proposed method can handle both cross-correlation among process variables at any one time and auto-correlation over time. And the control limits for the monitoring charts are established from sound statistical framework unlike previous researches which use the external reference distribution. The proposed charts perform real-time, on-line monitoring to ensure that the batch is progressing in a manner that will lead to a high-quality product or to detect and indicate faults that can be corrected prior to completion of the batch. This approach is capable of tracking the progress of new batch runs, identifying the time periods in which the fault occurred and detecting underlying cause.

• 한국전자통신학회논문지
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• 제17권6호
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• pp.1221-1228
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• 2022

현대 기술의 발전으로 인해 인력을 대체할 수 있는 무인 자동화 설비의 사용이 증가하고 있다. 그러한 자동화 설비 중 하나인 무인 반송차(AGV)의 기술에는 적외선 센서를 통해 라인을 인식하여 정해진 경로를 주행할 수 있는 라인 트레이싱(Line Tracing)이 있다. 본 논문에서는 라인 트레이싱 기술에 아두이노를 이용한 최단 시간 알고리즘을 구성하여 효율적인 주행을 가능하게 하였다. 또한 여기에 RFID 태그를 사용하여 위치·시간 정보를 수집할 수 있도록 설계하였다.

• 한국환경과학회지
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• 제13권3호
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• pp.245-250
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• 2004

The SBR(Sequencing Batch Reactor) process is ideally suited to treat high loading wastewater due to its high dilution rate. SBR operates by a cycle of periods consisting of filling, reacting, settling, decanting and idling. The react phases such as aeration or non-aeration, organic oxidation, nitrification, denitrification and other bio-logical reactions can be achieved in a reactor. Although the whole reactions can be achieved in a SBR with time distributing, it is hard to manage the SBR as a normal condition without recognizing a present state. The present state can be observed with nutrient sensors such as ${NH_{4}}^{+}-N$, ${NO_{2}}^{-}-N$, ${NO_{3}}^{-}-N} and ${PO_{4}}^{ 3-}-P.$ However, there is still a disadvantage to use the nutrient sensors because of their high expense and inconvenience to manage. Therefore, it is very useful to use common on-line sensors such as DO, ORP and pH, which are less expensive and more convient. Moreover, the present states and unexpected changes of SBR might be predicted by using of them. This study was conducted to get basic materials for making an inference of SBR process from ORP(oxidation reduction potential) of synthetic wastewater. The profiles of ORP, DO, and pH were under normal nitrification and denitrification were obtained to compare abnormal condition. And also, nitrite and nitrate accumulation were investigated during reaction of SBR. The bending point on ORP profile was not entirely in the low COD/NOx ratio condition. In this case, NOx was not entirely removed, and minimum ORP value was presented over -300mV. Under suitable COD/NOx ratio which complete denitrification was achieved, ORP bending point was observed and minimum ORP value was under -300m V. Under high COD/NOx ratio, ORP bending point was not detected at the first subcycle because of the fast denitrification and minimum ORP value was under -300mV at the time.

• 한국통신학회논문지
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• 제37C권12호
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• pp.1271-1280
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• 2012

최근 출시되는 주차보조시스템에서 후방물체와의 거리정보를 알아내는 방법으로는 초음파 센서나 레이더 등의 추가 센서장비를 활용하는 방법들이 있다. 하지만, 추가적인 장비의 사용은 추가적인 비용과 함께 기존 차량에서의 도입이 쉽지 않은 문제점을 가지고 있다. 다른 방법으로는 움직임 스테레오 기법이 제안되었다. 하지만, 스테레오 조정(Stereo Rectification) 단계에서 좋은 특징점의 검출과 정확한 매칭결과가 필요하다는 단점을 가지고 있다. 본 논문에서는 후방카메라 1대만을 사용하여 취득한 연속영상정보를 바탕으로 평행주차상황에서 영상의 사각화 변환과 라인단위 적분 사영화 및 블록화 기반 유사도 조사를 통하여 연속거리정보를 추출하는 방법을 제안하고자 한다. 실험에는 Magna Parallel 영상을 사용하였으며, 수행한 실험결과 후방공간에 대한 화면의 라인단위 연속거리의 측정이 가능함을 보였다.

• Journal of Platform Technology
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• 제8권2호
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• pp.22-31
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• 2020

생산라인의 운영 효율화, 설비의 융통성을 위하여 제조계획부터 생산에 이르기까지 산업자동화의 구축과 운영이 활발히 이루어지고 있다. ISO/TC184는 생산라인에서 지역적으로 분산되어 있는 PLC, IoT 등 프로그램식 단위제어기기(Programmable Devices)들의 정보를 공유할 수 있는 운영방식들에 대한 표준화가 진행 중이다. 본 연구에서 셀 콘트롤러의 설계는 열 공정에 대한 온도센서, 가스센서, 압력센서 등의 신호와 이를 대응하는 모터나 밸브 등의 동작을 수행하는 PLC그룹과 IoT 그룹으로 구성하였다. 셀 콘트롤러의 동작과 해석은 SDN(Software Defined Network)를 활용한 열공정에서 수행되는 공정 서비스 유형으로는 실시간(real-time) 전송 서비스, 손실에 민감한 대용량 전송 서비스, 일반(normal) 전송 서비스로 세 종류로 설정하고 수행하였다. 모의실험 결과는 SDN 경로 기법을 활용하여 결과 트래픽 증가 시에 평균 손실률은 약 17% 개선되었고, 실시간 서비스의 지연은 1ms의 낮은 수준으로 성능향상을 확인할 수 있었다.