• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.280-285
• /
• 2000

With recent development of technology of high stiffness material and the structural design, the construction of high rise structures such as tall building, tower has increased. The more flexible and slender structure is vulnerable to the internal and external dynamic loads induced by earthquake, wind and traffic load. There have been great effort and many researches to minimize the influence of dynamic loads on the structure. The traditional and stable method, the application of the passive damper, is not able to comply with various dynamic loads, while the mass damper which active control technology is integrated can effectively comply with load types. Therefore, the application of active control of huge structures with AMD(Active mass damper) or HMD(Hybrid Mass damper) is increasing. Up to now, most of actuators are servomotor and hydraulic actuator. But it is known that the electromagnetic actuator applies non contacting control force, which makes the control system easier with no characteristic change depending on time. In this paper, Hybrid mass damper with electromagnetic actuator was designed and applied to building scaled structure. The performance of designed HMD tested by shake table test is included.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.978-983
• /
• 2000

This paper presents the system identification of a small-scale building model with an active mass driver and the controller design using Matlab program. As the AMD is a mechanical system which has a dynamic characteristic and whose mass can not be neglected compared to that of the building mass, the AMD-building interaction should be included in the controller design. The system identification is carried out for the AMD-building system with two acceleration inputs of the shaking table and the AMD and single acceleration output of the building. The mathematical model for the AMD-building is obtained and compared with the experimental result. The controller is designed based on the mathematical model using the optimal control algorithm of LQG strategy. The experimental results are compared with the numerical results. It is shown that both results are in good agreement in the system identification and the controlled responses.

• 보존과학연구
• /
• s.30
• /
• pp.31-46
• /
• 2009

In the study, we confirmed morphological traits and calculated the Risk Class of 25 mould species, including Tyromyces palustris, through decomposition rate of substrate for characteristic confirmation of injured microorganisms. We received the injured microorganisms in wood and it was pure cultivated. We observed growth traits and decomposition rate of substrate. Also, it allows the calculation of Risk Class to be worried in the case of growth in wooden cultural properties. As a result, Tyromyces palustris, representative of brown-rot, has the characteristics about decomposition rate of substrate - Cellulose ; more active(+++), Lignin ; more active(+++), Xylan ; more active(+++), Starch ; active(++). We classified Tyromcyes palustris as a first Risk Class and as a second Risk Class about Schizophyllum commune et al(9 species, See table 1. We look forward to offering standard data base for evaluating Risk Class as a matter of applying preventive conservation in wooden cultural properties through our study.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.3
• /
• pp.150-157
• /
• 2002

This paper presents preliminarily an implementation of digital high-performance motion control system of Reluctance Synchronous Motor (RSM) drives with direct torque control (DTC). The system consist of stator flux observer, torque estimator, two hysteresis band controllers, an optimal switching look-up table, IGBT voltage source inverter, and TMS320F240 DSP controller made by Texas Instruments. The stator fluff observer is based on the combined voltage and current model with stator flux feedback adaptive control, and the input of the observer are the stator voltage and current of motor terminal for wide speed range. The rotor position and speed sensor used 6000 pulse/rev encoder. In order to prove rightness of the suggested control algorithm, we have some simulation and actual experimental system at $\pm$20 and $\pm$2000 rpm. The developed digitally high-performance motion control system+ are shown a good response characteristic of control results and high performance features using 1.0kW RSM which has 2.57 Ld/Lq salient ratio.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 1998.11a
• /
• pp.273-277
• /
• 1998

The purpose of this study was to develop a large representative data base for jeans marketing strategy. This study was to survey brand awareness and analyze brand image and consumer's seeking image. The 700 questionnaires were distributed and 656 reliable ones were used for statistical analysis. A SAS statistical package including frequency table, factor analysis, analysis of variance, Duncan's multiple range test, Peason's correlation test was used. The results are as follows: 1. Brand awareness involves "brand recall" based on asking a person to name recalled first, and "brand recognition" based on asking to identify brand name from 30 given brands. The result indicated that "Levi" was dominant for brand recall and Guess was dominant for brand recognition. 2. Regarding the brand image, the result showed that "Vov" was best represented for sophisticated 8t trendy brand images, "Storm" for sophisticated brand image, "Jambangee" for reasonable price & comfortable brand images, and "Levis" for classic & design/color brand images. 3. As a result of factor analysis on consumer's seeking image, six factors(characteristic/gay, intelligent/sexy, feminine/sophisticated, active/functional, cute/young, simple/comfortable) were found. Several factors had a relationship with demographic variables, preferred design, fashion interest.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.11
• /
• pp.970-977
• /
• 2008

This paper deals with the dynamic characteristics of the shaft with impeller model which is the most important part in developing the resin mixing machine. Through reverse engineering, it is possible to make the shaft with impeller geometry model which is necessary vibration characteristic analysis by commercial impeller. The natural frequency analysis and structural analysis using finite element analysis software are performed on the imported commercial shaft with impeller model. The most important fundamental natural frequency of the shaft with impeller model is around 14.5 Hz, which well agrees with modal testing. The most effective design variables were extracted by ANOM(analysis of means) and pareto chart. This paper presents approximation 2nd order polynomial as design variables using RSM(response surface methodology). Generally, RSM take 2 or 3 design variables, but this method uses 5 design variables with table of mixed orthogonal array. Further more, the analyzed result of the commercial shaft with impeller is to be utilized for the structural design of resin chock mixing machine.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.8
• /
• pp.3946-3965
• /
• 2018

Network anomaly detection in Software Defined Networking, especially the detection of DDoS attack, has been given great attention in recent years. It is convenient to build the Traffic Matrix from a global view in SDN. However, the monitoring and management of high-volume feature-rich traffic in large networks brings significant challenges. In this paper, we propose a moving window Principal Components Analysis based anomaly detection and mitigation approach to map data onto a low-dimensional subspace and keep monitoring the network state in real-time. Once the anomaly is detected, the controller will install the defense flow table rules onto the corresponding data plane switches to mitigate the attack. Furthermore, we evaluate our approach with experiments. The Receiver Operating Characteristic curves show that our approach performs well in both detection probability and false alarm probability compared with the entropy-based approach. In addition, the mitigation effect is impressive that our approach can prevent most of the attacking traffic. At last, we evaluate the overhead of the system, including the detection delay and utilization of CPU, which is not excessive. Our anomaly detection approach is lightweight and effective.

• Proceedings of the KIEE Conference
• /
• 2001.07e
• /
• pp.47-52
• /
• 2001

This paper presents a high-performance control system for Reluctance Synchronous Motor (RSM) drives with direct torque control (DTC). The system consist of stator flux observer, rotor position/speed estimator, torque estimator, two hysteresis band controllers, an optimal switching look-up table, IGBT voltage source inverter, and F240/C31DSP controller by using fully integrated control software. The stator flux observer is based on the combined voltage and current model with stator flux feedback adaptive control that inputs are current and voltage sensing of motor terminal with estimated rotor angle for wide speed range. The rotor position is estimated by the observed stator flux-linkage space vector. The estimated rotor speed can be determinated by differentiation of the rotor position used only in the current model part of the flux observer for a low speed operating area. To prove the suggested control algorithm, we have a simulation and testing at actual experimental system. The developed digitally high-performance position sensorless control system are shown a good motion control response characteristic results and high performance features using 1.0Kw RSM.

• The Research Journal of the Costume Culture
• /
• v.26 no.2
• /
• pp.217-232
• /
• 2018

As the types of wedding ceremonies become diversified, and consumers' needs become more selective, greater importance is given to wedding planners' roles in the wedding industry, and consumers require differentiated types of wedding service. As a preliminary qualitative study in this field, an ethnographic study was conducted to identify factors valued by consumers when selecting a wedding planner in the wedding planner market, which has rapidly grown in recent years. An in-depth interview was performed with eight participants in terms of wedding planner utilization type and consumers' understanding of wedding preparation with a wedding planner. The collected data were analyzed through taxonomy, component analysis and decision table analysis; for validation, professional wedding planners were asked to review the items valued by consumers in selecting a wedding planner. Four factors - expense characteristic, wedding planners, wedding consulting companies, and customer characteristics - were identified, along with eight sub-factors (capability, service attitude, technical communication, personal factors, wedding planner encounter paths, spouse's satisfaction status, and companies). Out of these, price (within budget), wedding planners' capability, wedding planners' service attitude are expected to be meaningful in further research because they were found to be attributes commonly valued by every respondent. This study is significant in that it has made a new approach to understanding wedding planner selection attributes through ethnographic research and identified new wedding planner selection attributes.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.2
• /
• pp.1-6
• /
• 2008

In recent years, developments in the semiconductor and electronic industries have brought a rapid increase in the use of large size silicon wafer. For further improvement of the ultra precision surface and flatness of Si wafer necessary to high density ULSI, it is known that polishing is very important. However, most of these investigation was experiment less than 300mm diameter. Polishing is one of the important methods in manufacturing of Si wafers and in thinning of completed device wafers. This study reports the machining variables that has major influence on the characteristic of wafer polishing. It was adapted to polishing pressure, machining speed, and the slurry mix ratio, the optimum condition is selected by ultra precision wafer polishing using load cell and infrared temperature sensor. The optimum machining condition is selected a result data that use a pressure and table speed data. By using optimum condition, it achieves a ultra precision mirror like surface.