• Journal of the Korea institute for structural maintenance and inspection
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• 제17권6호
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• pp.61-69
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• 2013

This research is aimed to evaluate characteristics and dynamic modeling of MR damper for semi-active vibration control. A MR damper of semi-active type was designed and made for the purpose of controlling the vibration of a real-size model structure. Usually a semi-active control system equipped with a MR damper requires a dynamic model which expresses numerical data about the damping capacity and dynamic characteristics generated by a MR damper. To fulfil the requirement, a Power model and a Bingham model were particularly employed among many dynamic models of MR damper. Those models being contrasted with other ones, a dynamic test was carried out on the developed MR damper. In the test, excitation frequencies were conditioned to be 0.15 Hz, 1.0 Hz, and 2.0 Hz, and three different currents were adopted for each frequency. From these test results, it was found that displacement affected control capacity of the MR damper. The test results led to the identification of model variables for each dynamic model, on the basis of which a force-speed relation curve and expected damping force were derived and contrasted to those of the developed MR damper. Therefore, it was proven that the MR damper designed and made in this research was effective as a semi-active controller, and also that displacement of 2mm at minimum was found to be secured for vibration control, through the test using various displacements.

• Journal of the Earthquake Engineering Society of Korea
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• 제1권1호
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• pp.41-49
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• 1997

This paper presents the result of an international cooperative research on the post-correlation analysis of forced vibration tests and the prediction of earthquake responses of a large-scale seismic test structure. The dynamic analysis is carried out using the axisymmetric finite element method incorporating in finite elements for the for field soil region. Through the post-correlation analysis, the properties of the soil layers are revised so that the best correlation in the responses may be obtained compared with the measured force vibration test data. Utilizing the revised soil properties as the initial linear values, the seismic responses are predicted for an earthquake using the equivalent linearlization technique. It has been found that the predicted responses by the equivalent nonlinear procedure are in excellent agreement with the observed responses, while those using the linear properties are fairly off from the measured results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제23권9호
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• pp.781-788
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• 2013

Grunt(stick-slip) noise happens between rear lining and drum on braking condition while vehicle is returning to steady position after nose-dive. The study presents a new testing and analysis methods for improving brake grunt noise on vehicle. Grunt noise is called a kind of stick slip noise with below 1 kHz frequency that is caused by the surfaces alternating between sticking to each other and sliding over each other with a corresponding change in friction force. This noise is typically come from that the static friction coefficient of surfaces is much higher than the kinetic friction coefficient. For the identification of the excitation mechanism and improvement of grunt noise, it is necessary to study variable parameters of rear drum brake systems on vehicle and to implement CAE analysis with stick slip model of drum brake. The aim of this study has been to find solution parameters throughout test result on vehicle and dynamo test. As a result of this study, it is generated from stick slip between rear lining and rear drum and it can be solved to reduce contact angle of lining with asymmetric and is effected not only brake drum strength but also rear brake size and brake factor.

• Journal of Digital Convergence
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• 제10권10호
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• pp.229-235
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• 2012

Police questioning is police measure for acquiring information or inquiring an identification without questionee's will in order to accomplish the goal under the Police Act. However, like spear and shield, it has its own inherent limits between both sides of public power and human right and has stirred an hot issue in our society for longtime. The core problem is whether policeman can force a questionee stop when the questionee refuses policeman's stop requirement, the first step for police questioning. Some opinions argue that police questioning has somewhat effects on crime prevention and suspect arrest but people still have inconvenience and refusal from experiences of reckless police questioning in the past. Because of this, the police needs to recover people's trust on police questioning. In order to do so, in case of police questioning, human right should be superior to crime prevention or suspect arrest. This is the time's call. So when there is a police questioning, policeman's exertion of it on the questionee who refuse it should be conducted under strict conditions.

• International Journal of Highway Engineering
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• 제18권6호
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• pp.41-50
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• 2016

OBJECTIVES : In this study, microstructural components of crumb rubber modified asphalt (CRMA) binder were investigated using environmental scanning electron microscope (ESEM). To clearly understand the elemental composition of the CRMA binder, energy dispersive X-ray spectroscopy (EDX) was employed on the ESEM samples. METHODS : CRMA binders were produced using open blade mixers at $177^{\circ}C$ for 30 min. The binders were artificially aged through a series of accelerated aging processes. Sample preparation was done by making a mold shape on the glass slide. Thereafter, the morphology of the CRMA binder was observed using the ESEM coupled with the EDX. RESULTS : The images captured from the ESEM indicate that the unaged CRMA binder appears to have a single-phase continuous nonuniform structure after the addition of crumb rubber particles, whereas the artificially aged CRMA binder was observed to have two different phases. ESEM coupled with EDX shows detailed internal structure of the modified binders compared to other technologies (i.e., optical microscopy, atomic force microscopy, and conventional scanning electron microscope). CONCLUSIONS : The captured images resemble the internal structures such as the viscous properties of the unaged CRMA binder and the interaction between the rubber particles and the base binder at aged condition. ESEM is a powerful instrument and with the introduction of EDX, it provided more details of the network microstructure of the asphalt binder. ESEM coupled with EDX is recommended for use in future investigation of microstructure of asphalt binders.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권4호
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• pp.860-877
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• 2013

Cloud computing has become one of the most important technologies for reducing cost and increasing productivity by efficiently using IT resources in various companies. The cloud computing system has mainly been built for private enterprise, but public institutions, such as governments and national institutes, also plans to introduce the system in Korea. Various researches have pointed to security problems as a critical factor to impede the vitalization of cloud computing services, but they only focus on the security threats and their correspondents for addressing the problems. There are no studies that analyze major security issues with regard to introducing the cloud computing system. Accordingly, it is necessary to research the security factors in the cloud computing given to public institutions when adopting cloud computing. This research focuses on the priority of security solutions for the stepwise adoption of cloud computing services in enterprise environments. The cloud computing security area is classified into managerial, physical and technical area in the research, and then derives the detailed factors in each security area. The research derives the influence of security priorities in each area on the importance of security issues according to the identification of workers in private enterprise and public institutions. Ordered probit models are used to analyze the influences and marginal effects of awareness for security importance in each area on the scale of security priority. The results show workers in public institutions regard the technical security as the highest importance, while physical and managerial security are considered as the critical security factors in private enterprise. In addition, the results show workers in public institutions and private enterprise have remarkable differences of awareness for cloud computing security. This research compared the difference in recognition for the security priority in three areas between workers in private enterprise, which use cloud computing services, and workers in public institutions that have never used the services. It contributes to the establishment of strategies, with respect to security, by providing guidelines to enterprise or institutions that want to introduce cloud computing systems.

• Tribology and Lubricants
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• 제36권4호
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• pp.215-231
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• 2020

The paper presents extensive survey and review of experimental and analytical researches on fluid film bearings and squeeze film dampers (SFDs) for turbomachinery available in open literature (major archival international journals) published recently (2018 and 2019 only). Over 60 published research works are reviewed based on the research topics and objectives, the types of bearings, size of bearings, and main design parameters with a brief summary of experiments and/or predictions in each work. Some important findings and general observations about the experimental and/or predictive data are also presented. There are several major trends observed throughout the survey. A large portion of the papers focuses on bearing surface textures and effect of operating and assembly conditions on static and/or dynamic forced performances, as well as bearing surface roughness and wear patterns. Researches on geometry of orifices and recesses in hydrostatic (or hybrid) bearings, as well as bearing system stability predictions using thermohydrodynamic analysis and computational fluid dynamics (CFD), are considered as significant topics. Studies on SFDs mainly focus on experimental identification of force coefficients for various SFD geometries and sealing conditions. Reliable experiments of fluid film bearings and SFDs along with the development of experimentally benchmarked predictive tools enable reinforcement of the path for reliable implementations of the bearing components into high performance rotating machinery operating at extreme and harsh conditions. The extensive list of sources of recent experiments in the available open literature is a welcome addition to the analytical community to gauge the accuracy of predictive tools.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1255-1255
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• 2001

The study used 356 veal calf meat samples received from Finland (n=16), France (n=109), Italy (n=81) and The Netherlands (n=150). Calves were raised under experimental protocols that compared feeding and housing practices normally used in each county to treatments aiming at improving animal welfare. Samples were taken at the $8^{th}$ rib of Longissimus thoracis muscle 24h after slaughter, They were kept refrigerated ( $2-4^{\circ}C$) under vacuum package for 6d and then frozen ($-20^{\circ}C$) until meat quality evaluation. Measurements included pH, color (Hunter Lab system), shear force, chemical composition (DM, Ash, Ether Extract, collagen and haematin content), weight and area cooking losses and a sensory evaluation by a group of panelists. A sample of meat was ground with a blade mill and scanned in duplicate between 1100 and 1498 nm (FOSS NIR Systems 5000). WinISI software was used to develop a discriminating equation using NIR spectra (SNV-detrend, derivative=1, gap=4nm, smooth=4nm). The Proc ANOVA and DISCRIM of SAS were used for all the laboratory determinations. County of production had a significant (P<0.01) effect on all the parameters. However, discriminant analysis using any or few laboratory parameters resulted in great errors of county classification. A more accurate (98.8%) classification was obtained only when using all the laboratory parameters. NIRS classified correctly 354 of the 356 samples (99.4%). Provided with a larger data set, NIRS could be used to identify country of production of veal meat.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제13권8호
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• pp.1587-1592
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• 2009

RFID is Playing a central role in ubiquitous technology according with the advent of the ubiquitous era, and the development of an RFID reader is also emerging as an important technical development field. In this paper, we developed a hardware system which is able to make use of the 13.56MHz RFID infrastructure being used as a transportation card, a credit card, and so on as well as the 125KHz RFID infrastructure being used in security company, and which is applicable to a location identification, an entrance and exit control, and security control over the TCP/IP communication. The existing local RFID methods have some problems which bottlenecks such as administrative problems, technical problems, and so force frequently occur because a casual server is placed and operated in a company. Hence, in this paper we developed an RFID multi reader which is connected to a central administrable server over the TCP/IP in order to solve these problems, and we make it be possible to keep an security control and be easy to install, transfer and administrate RFID infrastructures.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제38권1호
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• pp.57-62
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• 2014

Most analytical models of the human body have focused on conscious responses. A patellar tendon reflex, a representative example of spinal reflexes, occurs without a neural command. Muscle forces and activation of the quadriceps femoris muscles in healthy adults during patellar tendon reflex are identified in this study. The model is assumed to move in the sagittal plane, and the thigh and the trunk are assumed to be fixed in a sitting position so that the shank can move similar to a pendulum. The knee joint is modeled as a revolute joint, and the ankle joint is modeled as a fixed joint so that the shank and the foot can be regarded as one rigid body. Muscle forces are calculated following the inverse dynamic approach. Kinematic data obtained from an experiment (Mamizuka, 2007) are used as input data. Muscle activations are identified using a Hill-type muscle model. The obtained simulation results are compared with experimental results for validating the model and the underlying assumptions.