• Journal of the Korean Institute of Intelligent Systems
• /
• v.16 no.3
• /
• pp.291-296
• /
• 2006

In context-aware computing environment, some context is characterized by a single event, but many other contexts are determined by a sequence of events which happen with some timing constraints. Therefore context inference could be conducted by monitoring the sequence of event occurrence along with checking their conformance with timing constraints. Some context could be described with fuzzy concepts instead of concrete concepts. Multiple entities may interact with a service system in the context-aware environments, and thus the context inference mechanism should be equipped to handle multiple entities in the same situation. This paper proposes a context inference model which is based on the so-called fuzzy colored timed Petri net. The model represents and handles the sequential occurrence of some events along with involving timing constraints, deals with the multiple entities using the colored Petri net model, and employs the concept of fuzzy tokens to manage the fuzzy concepts.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.49 no.4
• /
• pp.111-119
• /
• 2012

Time Stretched Pulse (TSP) is used for transmitting and analyzing the impulse signal over the designated spatial place. However, if transfer functions of transmitter and receiver are unknown, performance investigation of free field in temporal domain is barely possible due to the overlap between the direct and indirect signal from the space. Generally, the free field or hemi-free field is evaluated by the Annex A of ISO 3745 in which utilizing the inverse square law with one-third octave band signals. In this paper, the author performs analysis of free field via applying TSP with inverse square law and the results are compared with the one-third octave band signals. According to the analysis of deviation between the corresponding signal and inverse square law model, the proposed TSP method provides the comparable performance index to the one-third octave band signal with reduced measuring time. Provided that the pre-whitening can be implementable by employing the speaker and microphone transfer function, further analyses from TSP compression are able to be performed such as multipath separation from time domain data. The anechoic chamber used in this experiment is verified conformance with ISO 3745 for free field and hemi-free field condition for limited frequency of the signal.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.7
• /
• pp.171-179
• /
• 2002

STEP-NC is the next generation CNC controller taking STEP-based data model as the interface scheme (or language) between CAM and CNC, and carrying out various intelligent functions. At the moment, efforts are being made worldwide to establish international standard for the new interface scheme formalized as ISO14649. As the new language is being established, increasing attention is being paid to the development of the new CNC. Korea STEP-NC is an integrated STEP-NC system taking ISO 14649 as an input, and carrying out various intelligent functions. It is composed of 5 modules: 1) Shop Floor Programming System (PosSFP), 2) Tool Path Generator (PosTPG), 3) Tool Path Viewer (PosTPV), 4) Man Machine Interface (PosMMI), and 5) CNC Kernel (PosCNC). Distinguished from other prototypes (of Europe and USA), the Korea STEP-NC is top-down designed, and bottom-up implemented comprehensively incorporating all the crucial components for realizing the full benefit of STEP-NC paradigm, without using any existing commercial CAD/CAM systems and CNC kernels. The Korea STEP-NC prototype was successfully demonstrated and evaluated in the ISO conventions Together with prototypes of Europe and USA, Korea STEP-NC will be used as a reference system fur the Triangular Conformance Test to be jointly carried out by ISO TC184 SC1, SC4, and IMS Project.

• Smart Structures and Systems
• /
• v.26 no.2
• /
• pp.227-239
• /
• 2020

Despite proven effectiveness and accuracy in laboratories, the existing damage assessment based on guided ultrasonic waves (GUWs) or acoustic emission (AE) confronts challenges when extended to real-world structural health monitoring (SHM) for railway tracks. Central to the concerns are the extremely complex signal appearance due to highly dispersive and multimodal wave features, restriction on transducer installations, and severe contaminations of ambient noise. It remains a critical yet unsolved problem along with recent attempts to implement SHM in bourgeoning high-speed railway (HSR). By leveraging authors' continued endeavours, an SHM framework, based on actively generated diffuse ultrasonic waves (DUWs) and a benchmark-free condition contrast algorithm, has been developed and deployed via an all-in-one SHM system. Miniaturized lead zirconate titanate (PZT) wafers are utilized to generate and acquire DUWs in long-range railway tracks. Fatigue cracks in the tracks show unique contact behaviours under different conditions of external loads and further disturb DUW propagation. By contrast DUW propagation traits, fatigue cracks in railway tracks can be characterised quantitatively and the holistic health status of the tracks can be evaluated in a real-time manner. Compared with GUW- or AE-based methods, the DUW-driven inspection philosophy exhibits immunity to ambient noise and measurement uncertainty, less dependence on baseline signals, use of significantly reduced number of transducers, and high robustness in atrocious engineering conditions. Conformance tests are performed on HSR tracks, in which the evolution of fatigue damage is monitored continuously and quantitatively, demonstrating effectiveness, adaptability, reliability and robustness of DUW-driven SHM towards HSR applications.

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.9
• /
• pp.981-986
• /
• 2015

As the seriousness of global environment pollution is gaining increasing public attention, research into greenhouse gas emissions of ships is being carried out globally. At a domestic level, however, in a number of significant fields such research has not been conducted to date. This study examined countermeasures for the reduction of $CO_2$ emission in the fields of electronic control engines, trim optimization, propeller polishing, hull cleaning, and anti-fouling paint using an actual sea-going vessel. Selected countermeasures were applied during sea trials of the ship and the effect of specific fuel oil consumption analyzed. It was found that each countermeasure resulted in a decrease of fuel consumption of 1~5%. The energy efficiency operational indicator (EEOI) was calculated and found to also be improved by 1~5%. Further research into the EEOI of domestic shipping is planned to enhance conformance with international environmental regulations and improve global competitiveness.

• Journal of Cadastre & Land InformatiX
• /
• v.47 no.2
• /
• pp.121-133
• /
• 2017

Technical regulations in the spatial information domain have been developed by a variety of independent organizations and raised inconsistent and overlapping problems with spatial information standards. Many research projects have been done to solve these problems but due to the difficulty of changing or modifying existing administrative regulations, almost nothing has happened for the harmonization. As a response to the fundamental problem, KATS (Korean Agency for Technology and Standards) recently switched the existing system to "trans- governmental participatory standard operation system" and the administrative change created an independent and consistent standard system in the Ministry of Land, Infrastructure and Transport. The Ministry, as a part of the effort, established its own KSDI(Korean Spatial Data Infrastructure) Standard system. From this context this paper presents a redefinition of technical regulation for the harmonization with spatial information standards, an association model between the standards and regulations, and a maintenance methodology to solve the fore-mentioned problems.

• Journal of Biosystems Engineering
• /
• v.39 no.3
• /
• pp.158-165
• /
• 2014

Purpose: The objective of this paper was to compare test standards regarding the performance and safety of agricultural tractors to identify the differences in test conditions, measurement tolerances, and test procedures. Based on the comparison, some recommendations were proposed for possible revisions or improvements to current tractor test standards. Methods: The test standards and codes of major standards development organizations (SDOs), such as the Organization for Economic Cooperation and Development (OECD), the International Organization for Standardization (ISO), the American Society of Agricultural and Biological Engineers (ASABE), EC type approval, and the board of actions of the Nebraska Tractor Test Laboratories (NTTL), were selected and analyzed. Comparison of the test standards: The ISO provides references for fuel and lubricants for tractor tests, and the OECD provides additional measurements for calculating fuel consumption characteristics during the power take-off (PTO) tests. The ISO, EC type approval, and the ASABE provide PTO protective device and the safety requirements. During drawbar power tests, seven transmission ratios are selected for fully automatic transmissions, according to the OECD. In case of hydraulic lift tests, ISO 789-2 and OECD Code 2 advise the use of a static lift force, while SAE J283 advises the use of additional dynamic lift capacity tests for a better representation of in-field operations. The OECD, the ISO, and EC type approval determine the seat index point (SIP), whereas the ASABE determines the seat reference point (SRP) for roll-over protective structure (ROPS) tests. Diversified measurement tolerances were among the braking performance test standards. The European Union (EU) has developed daily limits for vibration exposures with adaptations from ISO 2631-1. Electromagnetic compatibility evaluations are emerging of high-efficiency tractors due to the long-term conformance to electromagnetic emissions and interferences. Comparisons of tractor test standards discussed in this paper are expected to provide useful information for tractor manufacturers and standards development personnel to improve the performance and safety test standards of tractors.

• Journal of Korean Society of Transportation
• /
• v.36 no.2
• /
• pp.141-154
• /
• 2018

In order to meet the ever-increasing demand for international air travel, several plans are underway to open new airports and expand existing provincial airports. However, existing air demand forecasts have been based on the total air demand in Korea or the air demand among major cities. There is not much forecast of regional air demand considering local characteristics. In this study, the outbound air travel demand in the southeastern region of Korea was analyzed and the fixed-effects model using panel data was proposed as an optimal model that can reflect the inherent characteristics of metropolitan areas which are difficult to observe in reality. The results of model validation show that panel data analysis effectively addresses the spurious regression and unobserved heterogeneity that are difficult to handle in a model using only a few macroeconomic indicators with time series characteristics. Various statistical validation and conformance tests suggest that the fixed-effects model proposed in this study is superior to other econometric models in predicting demand for international demand in the southeastern region.

• Journal of KIISE:Computing Practices and Letters
• /
• v.8 no.6
• /
• pp.647-656
• /
• 2002

Synchronization is the process of making replicated data on multiple devices be consistent, i.e., identical with each other. In Dec. 2000, major handheld computer manufacturers including Nokia, Ericsson, IBM published the SyncML protocol specification. In this paper, we describe the CNU SyncML server for PIMS(Personal Information Management System) service that we developed based on the SyncML specification. The server architecture and capabilities of the frames are presented along with the procedure of message processing by each frame. We put the CNU SyncML server to the conformance tests and interoperability tests to confirm its functionality. The session managing mechanism of the CNU SyncML server showed better performance than our previous implementations.

• Journal of Broadcast Engineering
• /
• v.12 no.3
• /
• pp.203-213
• /
• 2007

DMB video/audio service was successfully launched. DMB data service is a matter of primary concern now. The TTI(Traffic and Travel Information) service is considered as a killer application of the data service. Tn this paper, we propose a method for design and implementation of the broadcasting system for TTI service. The proposed TTI service system consists of an authoring tool, the DB module, the Transmission module and Monitoring module. This system satisfies the national TTA standards of the Traffic and Travel Information data services for terrestrial DMB; TPEG(Transport Protocol Experts Group) platform. The system was designed to support real-time automatic transmission for CTT and CTT SUM, and non real-time authoring & automatic transmission for POI and SDI, and was focused on the capability to make high-quality contents efficiently and to send them to the data inserter reliably. The performance of the implemented system was proven through the conformance tests with the various commercial receivers. After the continuous upgrade, the system is being used in commercial service.