• ETRI Journal
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• v.32 no.6
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• pp.854-862
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• 2010

One-way delay variation (OWDV) has become increasingly of interest to researchers as a way to evaluate network state and service quality, especially for real-time and streaming services such as voice-over-Internet-protocol (VoIP) and video. Many schemes for OWDV measurement require clock synchronization through the global-positioning system (GPS) or network time protocol. In clock-synchronized approaches, the accuracy of OWDV measurement depends on the accuracy of the clock synchronization. GPS provides highly accurate clock synchronization. However, the deployment of GPS on legacy network equipment might be slow and costly. This paper proposes a method for measuring OWDV that dispenses with clock synchronization. The clock synchronization problem is mainly caused by clock skew. The proposed approach is based on the measurement of inter-packet delay and accumulated OWDV. This paper shows the performance of the proposed scheme via simulations and through experiments in a VoIP network. The presented simulation and measurement results indicate that clock skew can be efficiently measured and removed and that OWDV can be measured without requiring clock synchronization.

• Journal of KIISE:Information Networking
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• v.34 no.2
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• pp.100-109
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• 2007

Streaming protocol with the Available Bandwidth measurement scheme has problems that are to measure a Available Bandwidth uncorrectly and slowly. In this basis, in order to overcome limitations of the previous streaming protocols, we propose the NABO that is a New Available Bandwidth measurement scheme used by OWD(One-Way Delay). Proposed NABO(New Available Bandwidth measurement based on OWD) measures the constant transmission delay occurred by bottleneck link capacity and the variable delay. Competing traffic contribute to the variable delay. Through the measurement of the constant transmission delay and the competing traffic, a NABO can measure the Available Bandwidth correctly and fast in network. The simulation result proves that the proposed NABO has a performance that satisfies both accuracy viewpoint and measurement speed viewpoint.

• Journal of the Korea Society of Computer and Information
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• v.13 no.1
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• pp.175-183
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• 2008

QoS-support technology in networks is based on measuring QoS metrics which reflect a magnitude of stability and performance. The one-way delay measurement of the QoS metrics especially requires a guarantee of clock synchronization between end-to-end hosts. However, the hosts in networks have a relative or absolute difference in clock time by reason of clock offsets. flock skews and clock adjustments. In this paper, we present a theorem, methods and simulation results of one-way delay and clock offset estimations between end-to-end hosts. The proposed theorem is a relationship between one-way delay, one-way delay variation and round-trip time And we show that the estimation error is mathematically smaller than a quarter of round-trip time.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.56.2-56
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• 2002

A dye process of textile industry is important part that finally gives required quality to the textile material. To produce a proper dye for the customers, color management that precise color measurement from original color sample and rapid estimation of corresponding color recipe is most essential. In the practical dye manufacturing process, color management falls into two categories. First one is color management with an expert knowledge of colorist, the other one is computer aided way. In the former management way, color management fully depends on colorists' expert without support of the measurement and computational devices. Objective color management is impossible in this way. The...

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.181-193
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• 2010

The paper presents an alternative way to classical stereocorrelation. First, 2D image processing of random patterns is described. Sub-pixel displacements are determined using phase analysis. Then distortion evaluation is presented. The distortion is identified without any assumption on the lens model because of the use of a grid technique approach. Last, shape measurement and shape variation is caught by fringe projection. Analysis is based on two pin-hole assumptions for the video-projector and the camera. Then, fringe projection is coupled to in-plane displacement to give rise to 3D measurement set-up. Metrological characterization shows a resolution comparable to classical (stereo) correlation technique ($1/100^{th}$ pixel). Spatial resolution seems to be an advantage of the method, because of the use of temporal phase stepping (shape measurement, 1 pixel) and windowed Fourier transform (in plane displacements measurement, 9 pixels). Two examples are given. First one is the study of skin properties; second one is a study on leather fabric. In both cases, results are convincing, and have been exploited to give mechanical interpretation.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.796-801
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• 1994

Measuring noise, sound quality or acoustical comfort presents a difficult task for the acoustic engineer. Sound and noise are ultimately jugded by human beings acting as analysers. Regulations for determining noise levels are based on A-weighted SPL measurement performed with only one microphone. This method of measurement is usually specified when determining whether the ear can be physically damaged. Such a simple measurement procedure is not able to determine annoyance of sound events or sound quality in general. For some years investigations with binaural measurement analysis technique have shown new possibilities for the objective determination of sound quality. By using Artificial Head technology /1/, /2/ in conjunction with psychoacoustic evaluation algorithms - and taking into account binaural signal processing of human hearing, considerable progress regarding the analysis of sounds has been made. Because sound events often arise in a complex way, direct conclusions about components subjectively judged to be annoying with regard to their causes and transmission paths, can be drawn in a limited way only. A new procedure, complementing binaural measurement technology combined with mulit-channel measuements of acceleration sensor signals has been developed. This involves correlating signals influencing sound quality, analyzed by means of human hearing, with signals form different acceleration sensors fixed at different positions of the sound source. Now it is possible to recognize the source and the transmission way of those signals which have an influence on the annoyance of sound.

• IE interfaces
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• v.11 no.3
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• pp.41-53
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• 1998

Several performance measurement systems have been proposed and are currently being used in many organizations. However, no performance measurement system has presented a mechanism for integrating all of the information of performance measures in a way that considers the relationships between them. This paper proposes the performance information integration method (PIIM) which synthesizes all useful information of performance measures with consideration of the relationships and generates a single, global, organizational performance score. The PIIM showed good performance in the implementation in one long-term care facility. This paper provides performance measurement systems with an integration mechanism for multiple performance measures.

• The Journal of Korean Physical Therapy
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• v.31 no.2
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• pp.82-87
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• 2019

Purpose: The purpose of this study was to examine the effects of plank exercises with resistance of one-sided hip adduction on abdominal muscle thickness. Methods: Thirty subjects were divided into a group that underwent plank exercises with one-sided hip adduction resistance (n=15) and a group that underwent plank exercises only (n=15). Their changes in abdominal muscle thickness before the experiment (n=15) and three and six weeks after the experiment were analyzed using a two-way repeated analysis of variance at a statistical significance level of ${\alpha}=0.05$. When there was any interaction between the time of measurement and each group, post hoc t-tests were conducted at a statistical significance level of ${\alpha}=0.01$. Results: The results of the experiment showed statistically significant differences in the thickness of the rectus abdominis, internal oblique muscle, and transversus abdominis, depending on the time of measurement and the interaction between the time of measurement and each group (p<0.05). Statistically significant differences were observed in the thickness of the external oblique, depending on the time of measurement, the interaction between the time of measurement and each group, and variances between the groups (p<0.05). Conclusion: The results of this study indicated that plank exercises with resistance of one-sided adduction are effective for increasing abdominal muscle thickness. The study's overall findings will likely be used as basic data for lumbar stabilization exercises and rehabilitation treatment.

• Korean Management Science Review
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• v.26 no.1
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• pp.137-159
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• 2009

An organizational performance measurement practice is a function of performance measurement system and performance management system they are currently employing, and its quality is determined by evaluating the followings in a comprehensive manner: first, if they are measuring right things; second, if they are measuring in a right way; third, if they are actively facilitating a process of data collection, structuring, analysis, interpretation, and dissemination; and fourth, if they are using performance measurement results for the primary purposes of performance measurement. This study proposes a diagnostic framework for evaluating the performance measurement practices of public broadcasting which include the qualities of performance measurement and performance management, and develop a structured questionnaire for that purpose. The framework proposed in this study does not serve only as a useful tool for public broadcasting to revise their respective performance measures and performance measurement systems, but it also make their respective performance measurement practices a strategic management tool as well as an operational management one.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.393-402
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• 1993

Two field test installations are discussed. In the first one a new ammonia sensor and an accurate ventilation rate sensor are combined. They are installed in the exhaust chimney in a ventilated pig house. The relative humidity and the room temperature are measured as well. In the second one, an in situ NH$_3$longrightarrowNO converter with subsequent NOx analyser is also being added for accurate ammonia measurement . In this way , the continuous measurement of the total NH$_3$emission can be obtained , the performance of the NH$_3$ sensor can be evaluated, and the ammonia reduction techniques can be tested. The outputs of measurement are fed into a data acquisition system then to a PC in the laboratory. There has been realised the first test installation with which research on the new ammonia sensor is carried out. The primary research results are presented.