• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1545-1550
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• 2014

Fault detection and diagnosis (FDD) of photovoltaic (PV) power systems is one of significant techniques for reducing economic loss due to abnormality occurred in PV modules. This paper presents a new FDD method against PV power systems by using statistical comparison. This comparative approach includes deviation signals between the outputs of two neighboring PV modules. We first define a binary hypothesis testing under such deviation and make use of a generalized likelihood ratio testing (GLRT) theory to derive its FDD algorithm. Additionally, a recursive computational mechanism for our proposed FDD algorithm is presented for improving a computational effectiveness in practice. We carry out a real-time experiment to test reliability of the proposed FDD algorithm by utilizing a lab based PV test-bed system.

• International Journal of Railway
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• v.6 no.2
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• pp.78-84
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• 2013

This paper is about the first experiment in Korea that was conducted on speeding increase up with rail speeds at 430km/h at high speed railway of designed 350km/h. and analysis data collected on vibration accelerations of roadbed. There are barely references on roadbed behavior measurement with rail speeds more than 350 km/h in Korea as it has never been conducted the experiment on it. So the experiments were confirmed the reliability through crosschecking the figures/values from respective sensors and measuring devices after measuring EMS and ICP types. Based on the study, values of vibration acceleration were less than 12% compared with the ones that conducted while speeding up of HEMU-430X. Also, figures of HSB for concrete bed tracks were 52% against the standard. According to the results, all the performance evaluation of vibration acceleration for roadbeds in transition zones is under the standard.

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.1
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• pp.7-17
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• 2010

ITS(Intelligent Transport System) as things are used for Broadcast service using TDMB/TPEG/NAVI rather than personal seamless service. It is attaching weight to Traffic information gathering, Charging, Settlement service. This research is applied to improve DCCP(Datagram Congestion Control Protocol) which has function as protecting data and preserving message boundary. The improving method is like that we solve data trust in UDP because Connection and Transmission overhead in UDP is less than in TCP. We fix the data loss which is generated from unordered delivery section of IP base wireless service by using DCCP protocol. We guarantee of connection with OBE(On-Board Equipment) and reliance about transmission of data by complement to mapping table and multi-hoping. Finally, We evaluate the performance about transmission of IP based data. We constructed a test-bed near research center for this test.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.77-87
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• 2012

Recently, Load and Resistance Factor Design (LRFD) based on reliability analysis has become a global trend for economical and rational design. In order to implement the LRFD, quantification of uncertainty for load and resistance should be done. The reliability of result relies on input variable, and therefore, it is important to obtain exact uncertainty properties of load and resistance. Since soil stress is the main reason causing the settlement or deformation of ground and load on the underground structure, it is essential to clarify the uncertainty of soil stress distribution for accurately predict the uncertainty of load in LRFD. In this study, laboratory model test on silty sand bed under probabilistic load is performed to observe propagation of upper load uncertainty. The results show that the coefficient of variation (COV) of soil stress are varied depending on location due to non-linear relationship between upper load increment and soil pressure increment. In addition, when the load uncertainty is transmitted through ground, COV is decreased by damping effect.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.8
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• pp.8-17
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• 2012

Unlike traditional lightings, LED lighting is one of objects that sends user an emotional segments through brightness control from various color temperature and dimming control. Also, within present interior lighting environment, emotional researches about traditional fluorescent lamp and newly implemented LED lighting environment are in active progress. Despite the fact adjectives describing emotions and scale modeling have been repeatedly used in many cases for a long time, there seems to be a lack of results in reliability, and there is a limitation for applying into actual lighting design. The purpose of this study is to construct an actual sized test-bed, which is used to draw out one's emotional words of behavior patterns from inner emotional experiences about lighting environment in an office space. Also, having fluorescent lamp and LED lighting as the main test subjects, we have tested emotional parts according to the changes of color temperature and adjective vocabularies chosen from user's action, and we have compared and analyzed the drawn out data. Also, having fluorescent lamp and LED lighting as the main test subjects, we have tested emotional parts according to the changes of color temperature and adjective vocabularies chosen from user's action, and we have compared and analyzed the drawn out data.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.71-74
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• 2010

Using the technology demonstration model of 75-tonf-class combustor which is expected to be used to the rocket engine of a korean space launch vehicle, 2 times of firing tests were carried out. Firing tests were done at 50% of the nominal flow rate because of incapability of the test facility and limit of the test bed strength. Through the low pressure firing tests of 75-tonf-class channel cooling thrust chamber, reliability and stability at the ignition and combustion phases were confirmed. Additionally it was foreseen that the 75-tonf-class thrust chamber would satisfy the performance requirements.

• Journal of electromagnetic engineering and science
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• v.16 no.2
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• pp.80-86
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• 2016

This paper proposes the algorithm for forward link adaptive coding and modulation (ACM) and the detailed design for a satellite communication system to improve network reliability and system throughput. In the ACM scheme, the coding and modulation schemes are changed by as much as the channel can provide depending on the quality of the communication link. To implement the forward link ACM system in the Ka-band, channel prediction and modulation/coding decision methods are proposed and simulated. The parameters of the adaptive filter predictor based on the least mean square are optimized, the minimum mean square error of the channel predictor is 0.0608 when step size and the number of filter tap are 0.0001 and 4, respectively. A test-bed is set up to verify the forward link ACM system, and a test is performed using a Ka-band satellite (i.e., Communication, Ocean, and Meteorological Satellite [COMS]). This test verifies that the ACM scheme can increase the system throughput.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5534-5540
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• 2015

This In the railway signaling system, applications of axle counter in addition to track circuit goes on increasing for detecting train position. Consequently, this paper compares sensor methods of axle counter with between geo-magnetism method and proximity sensor method. And it presents differences and results, to improve reliabilities of train detection and axle counting. Also, this article presents an applied result which is based on field experience, with regard to installation, considering attachment condition of sensor part for accurate axle counting. This study acquires expandability that is able to perform not only axle counting function but also various other functions (direction detection of train, speed detection of train, and so on). It was a result of a change of design in order to judge phase difference of sensors, to improve reliability of axle counting. Furthermore, it does not subordinate to characteristics (type, weight of train). And it is confirmed that the omission of axle counting was not occurred in 350km/h. This was the result of Lab test after the construction of transfer equipment of trial axle and Test Bed for axle counting. Both of them are self-productions. Through this, it prepares foundation which is able to apply not only to train detection but also to speed of passing trains, formation number of trains, detector locking condition - when the train passes the section of switch point, and level crossing devices. Furthermore, it would be judged to contribute safety train operation if proximity sensor method applies to the whole railway signaling system from now on.

• Physical Therapy Rehabilitation Science
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• v.7 no.4
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• pp.186-190
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• 2018

Objective: Deep neck flexor muscle endurance (DNFET) is important to cervical pain patients. However, there is no normative data of the DNFET hold time of Korean university students. The purpose of this study was to provide normative data and the reliability of the DNFET times of Korean university students and to compare the DNFET hold times between male and female subjects. Design: Cross-sectional study. Methods: The participants included 39 male and 39 female students with no cervical pain. Each DNFET was measured while the subjects kept their chin tucked in while in a supine (hook-lying) position and with the head lifted 2.5 cm off the bed. The DNFET was conducted on each subject twice and the mean values were obtained. After each measurement, the participants rested for 5 minutes. Inter-rater reliability was measured by intraclass correlation coefficient (ICC) by three separate evaluators. Results: The inter-rater reliability was good, showing an ICC (2,3) value = 0.785 (95% confidence interval, 0.370-0.942). The DNFET time scores for men and women were $25.14{\pm}9.96$ seconds and $15.23{\pm}6.10$ seconds, respectively, in which the time scores of the men were significantly longer compared to women (p<0.05). Conclusions: Asymptomatic men displayed higher DNFET scores than women. This study can help clinicians test cervical function of patients and set an interventional goal. These findings serve as a basis that insists Korean women to increase their amount of physical activity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12B
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• pp.1042-1051
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• 2004

The IEEE1394 is a favorable protocol for A/V networks recently in home and there are two types of transmission in this protocol which are asynchronous and isochronous. The more nodes participate in the IEEE1394 network, the more problems of resource exhaustion and connection repetition may occur. So this paper proposes a middleware for isochronous connection management and reliable multimedia data transmission in the IEEE1394-IEC61883 based home networks. In this paper, proposed middleware is supporting the various types of isochronous connection, guaranteeing the reliability of isochronous connection and providing the characteristic of a real-time data transmission. We support CORBA API for multimedia service and the proposed architecture was implemented using a test-bed and we verified the proposed architecture in a test-bed.