• Journal of Biomedical Engineering Research
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• v.28 no.3
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• pp.369-376
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• 2007

With the convergence of ubiquitous networking and medical technologies, ubiquitous healthcare(U-Healthcare) service has come in our life, which enables a patient to receive medical services at anytime and anywhere. In the u-Healthcare environment, intelligent real-time biosignal aquisition/analysis techniques are inevitable. In this study, we propose a motion artifact cancelation method in portable photoplethysmography(PPG) signal aquisition using an accelerometer and an adaptive filter. A preliminary experiment represented that the component of the pedestrian motion artifact can be found under 5Hz in the spectral analysis. Therefore, we collected PPG signals under both simulated conditions with a motor that generates circular motion with uniform velocity (from 1 to 5Hz) and a real walking condition. We then reduced the motion artifact using a recursive least square adaptive filter which takes the accelerometer output as a noise reference. The results showed that the adaptive filter can remove the motion artifact effectively and recover peak points in PPG signals, which represents our method can be useful to detect heart rate in real walking condition.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.799-802
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• 2012

본 논문은 기존의 헬스케어 서비스의 한계를 극복하기 위해 최근 대두되고 있는 스마트 헬스케어 서비스(smart healthcare service)에 관한 연구이다. 스마트 헬스케어는 스마트폰의 기능에 맞추어 기초체력 운동 지수, 섭취 칼로리, 심박 체크 등의 다양한 서비스를 제공할 수 있지만, 최근에는 보건의료서비스에 특화시켜 환자와 의사가 직 간접적으로 진료를 할 수 있게끔 하는 스마트폰 환경에서의 원격진료 서비스가 부각되고 있다. 그러나 헬스케어를 위한 HL7 CDA 표준의 문서 교환방식은 실시간 데이터 획득을 요구하는 원격진료 서비스 환경에 적합하지 못하다. 이에 본 논문에서는 HL7v2.x의 트리거 이벤트를 통한 메시지 전송방식과 HL7 CDA RIM(Reference Information Model)을 응용하는 실시간 HL7 의료정보 전송 방안을 제안한다.

• Journal of Biomedical Engineering Research
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• v.30 no.6
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• pp.503-509
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• 2009

The development of technology has led to ubiquitous health care service, which enables many patients to receive medical services anytime and anywhere. For the ubiquitous health care environment, real-time measurement of biomedical signals is very important, and the medical instruments must be small and portable or wearable. So, such devices have been developed to measure biomedical signals. In this study, we develop the biomedical monitoring device which is sensing the PPG signal, one of the useful signal in the field of ubiquitous healthcare. We design a watch-like biomedical signal monitoring system without a finger probe to prevent the user's inconvenience. This system obtains the PPG from the radial artery using a sensor in the wrist band. But, new device developed in this paper is easy to get the motion artifacts. So, we proposed new algorithm removing the motion artifacts from the PPG signal. The method detects motion artifacts by changing the degree of brightness of the light source. If the brightness of the light source is reduced, the PPG pulses will disappear. When the PPG pulses have disappeared completely, the remaining signal is not the signal that results from the changing blood flow. We believe that this signal is the motion artifact and call it the noise reference signal. The motion artifacts are removed by subtracting the noise reference signal from the input signal. We apply this algorithm to the system, so we can stabilize the biomedical monitoring system we designed.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.113-122
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• 2017

The district heating system, which is the main axis of Korea's collective energy business, contributes to the national benefit and safety with the economical heat energy supply system.However, due to the uncertainty of management subjects and the shortage of professional technical personnel, there are many problems such as deterioration of thermal efficiency and unfairness of the price of the apartment houses. In this paper, we propose the monitoring points necessary for the efficiency and fault management of the district heating customer-side. And we propose a standard reference model to standardize it. We propose a technical methodology to improve the service quality and energy efficiency of the district heating facilities by applying IoT sensor technology, real-time monitoring and integrated management system.

• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.372-385
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• 2002

In this paper, we propose an efficient buffer replacement method for the real-time multimedia data. The proposed method has multi level priority to consider the real-time characteristics. Each priority level is divided into a cold data set that is likely to be referenced for the first time and a hot data set that is likely to be re-referenced. An operation to select the victim data is sequentially executed from the cold set with the minimum priority level to the hot set with the maximum Priority level. It is chosen only at the lower level than or equal to the priority of the transaction that requests a buffer allocation. In the cold set, our method selects a media that has the maximum size in the level for a target of victim first of all. And in the hot set, our method selects a medium that has the maximum interval of the reference first of all. Since it maintains many popular media in the limited buffer space, the buffer hit ratio is increased. It also manages many service requests. As a result, our method improves the overall performance of the system. We compare the proposed method with the Priority-Hints method in terms of the buffer hit ratio and the deadline missing ratio of transactions. It is shown through the performance evaluation that our method outperforms the existing methods.

• Smart Structures and Systems
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• v.23 no.3
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• pp.263-278
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• 2019

Moving train load parameters, including train speed, axle spacing, gross train weight and axle weights, are identified based on strain-monitoring data. In this paper, according to influence line theory, the classic moving force identification method is enhanced to handle time-varying velocity of the train. First, the moments that the axles move through a set of fixed points are identified from a series of pulses extracted from the second derivative of the structural strain response. Subsequently, the train speed and axle spacing are identified. In addition, based on the fact that the integral area of the structural strain response is a constant under a unit force at a unit speed, the gross train weight can be obtained from the integral area of the measured strain response. Meanwhile, the corrected second derivative peak values, in which the effect of time-varying velocity is eliminated, are selected to distribute the gross train weight. Hence the axle weights could be identified. Afterwards, numerical simulations are employed to verify the proposed method and investigate the effect of the sampling frequency on the identification accuracy. Eventually, the method is verified using the real-time strain data of a continuous steel truss railway bridge. Results show that train speed, axle spacing and gross train weight can be accurately identified in the time domain. However, only the approximate values of the axle weights could be obtained with the updated method. The identified results can provide reliable reference for determining fatigue deterioration and predicting the remaining service life of railway bridges.

• Smart Structures and Systems
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• v.32 no.3
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• pp.153-166
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• 2023

Health monitoring of civil infrastructures, in particular, old bridges that are still in service, has become more than necessary, given the risk that a possible degradation or failure of these infrastructures can induce on the safety of users in addition to the resulting commercial and economic impact. Bridge integrity assessment has attracted significant research efforts over the past forty years with the aim of developing new damage identification methods applicable to real structures. The bridge of Ouled Mimoun (Tlemcen, Algeria) is one of the oldest railway structure in the country. It was built in 1889. This bridge, which is too low with respect to the level of the road, has suffered multiple shocks from various machines that caused considerable damage to its central part. The present work aims to analyze the stability of this bridge by identifying damages and evaluating the damage rate in different parts of the structure on the basis of a finite element model. The applied method is based on an inverse analysis of the normal stress responses that were calculated from the corresponding recorded strains, during the passage of a real train, by means of a set of strain gauges placed on certain elements of the bridge. The results obtained from the inverse analysis made it possible to successfully locate areas that were really damaged and to estimate the damage rate. These results were also used to detect an excessive rigidity in certain elements due to the presence of plates, which were neglected in the numerical reference model. In the case of the continuous bridge monitoring, this developed method will be a very powerful tool as a smart health monitoring system, allowing engineers to take in time decisions in the event of bridge damage.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.3
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• pp.31-39
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• 2015

This paper presents the static and kinematic positioning accuracy by the real-time GPS positioning modes of the low-cost GPS receivers using NTRIP-based augmentation service. For this, acquires both the raw measurements data of the field tests by LEA 6T GPS module of u-blox AG, and correction communication via NTRIP caster with RTKLIB as an open source program for GNSS solution. With computing the positions of the check points and road tracks by six kinds of GPS positioning modes which are Single, SBAS, DGPS, PPP, RTK, and TCP/IP_RTK, compared these results to the reference position of the check points. The position error average and rmse of the static test by GPS L1 RTK surveying showed $N=0.002m{\pm}0.001m$, $E=0.004m{\pm}0.001m$ in horizontal plane, and $h=-0.116m{\pm}0.003m$ in vertical, these results are very closed to the coordinates with the geodetic receiver. Especially, in case of the kinematic test with obstacles located on both sides of road, the computed track with ambiguity fixing showed very similar trajectory considerably from VRS network RTK mode. And also, evaluate and verify the performance of the TCP/IP_RTK mode developed based on TCP/IP protocol.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.4
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• pp.1-12
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• 2007

A method for assessing fatigue vulnerability of steel bridge members considering corrosion and truck traffic variation with time is proposed to evaluate the reduction of fatigue strength in steel bridge members. A fatigue limit state function including corrosion and traffic variation effect is established. The interaction between the average corrosion depth and the fatigue strength reduction factor is applied to the limit state function as the reduction term of strength. Three types of truck traffic change is modeled for representing real traffic change trend. Monte-Carlo simulation method is used for reliability analysis which provides the data to obtain fatigue vulnerability curves. The estimation method proposed was verified by comparing with the results of reference study and applying to the steel bridges in service.

• Journal of the Korean Society of Costume
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• v.64 no.1
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• pp.136-151
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• 2014

This study systematically analyzed types of fashion brand application focusing on accounts created in Korea. While referring to 'Chanel' which has developed a fashion brand app for the first time in August of 2008, not only for App store by Apple Inc. of the greatest market share but also for Android market, the one and only competitor of App store, the study examined cases of fashion brand app in Korea and foreign countries which have been in service till August of 2013 since the year of 2008. To achieve the research goal, the study conducted a literature research and a case review, categorizing the app by their distinctive functions which were Basic Information, SNS, AR, LBS, Entertainment, Mobile Shopping and Live Streaming. As for the first function, Basic Information, it was considered to provide information on a brand such as prices, sizes and colors of products which should be the most fundamental function of a fashion brand. The function would include look book, catalogues, photographs and others of products, helping users of the app with their understanding on images and concepts of the brand. Second, SNS function was considered useful for its mobility and communication and with the help of theirs, the users share fashion information with each other. Third, AR function as in a filed of virtual reality would edit virtual objects to look real in an actual environment. This would eventually offer the users a chance to try for clothes virtually. The fourth function, LBS, would work with GPS to find a store closest from a present location. This would be a help when the users try to find stores holding promotion events or trails while hiking in mountains. The fifth Entertainment function would include all sorts of games and chances for the users to listen to music and keep fashion diaries. The sixth function, Mobile Shopping, would help the users purchase items online via the app as they would not visit a store in person. The seventh function, Live Streaming, would give the users chances to actually see fashion collections in real time, held all over the world in every season. Because of this function, not only fashion experts but also regular people have become able to enjoy the fashion shows. The distinctive characteristics of the fashion brand application discussed in the study will be a useful reference when any relevant fields try to design other new fashion brand application.