• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.504-507
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• 2005

This paper presents a self-levelling system for a mass, which undergoes a severe acceleration, with integrated displacement feedback control. After a general description of such a system, theoretical analysis is investigated to design an active control device. That is, the self levelling system is used to reduce the 'static' deflections while isolating the 'dynamic' vibration. A computer simulation model of 45 kg with two air spring mounts is considered to predict the performance of the control system. The results showed the controller can reduce the mass's displacement to the level of 1/3-1/5. Thus the self-levelling system can be applied usefully to reduce the dispalcement of a mass which experiences a high g dynamics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1317-1326
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• 2008

This paper presents a self.levelling system for a mass, which undergoes a severe acceleration, with integrated displacement feedback control. After a general description of such a system, theoretical analysis is investigated to design an active control device. The self-levelling system can be used to reduce the "quasi-static" deflection while isolating the "dynamic" vibration. A computer simulation model of 45 kg with two air spring mounts is considered to predict the performance of the control system. Important control parameters were acquired to meet the requirement of the system. The results showed the controller can reduce the displacement of the mass to the level of about 1/5 after control. Thus the self-levelling system can be applied usefully to reduce the displacement of a mass which experiences a high g dynamics.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.505-508
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• 2006

Self-leveling mortar is walkable bottom mortar which can maintain the horizontality of self fluid and have the the quick-setting quality, the low-human-effort practicable material of high-quality bottom in construction. In accordance with more adhesive strength with bottom side and absorption control, Primer is used for purpose to prevent pin-hole occurrence by self leveling mortar application prior to construction. This study is composed measurement of absorption, adhesive strength. Used material is NP-40 as nonionic emulsifying agent, uses SA-210L as negative ion emulsifying agent, uses APS, SBS as ridical initiator. A result of test, in accordance with image of Primer, as low temperature and application frequency, indicates low absorption rate and adhesive strength, as solid powder and dryness time is increse, absorption rate and adhesive strength lowly shows figure.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.6
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• pp.733-739
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• 2009

Recently it is being increased rapidly to install magnetic marker and RFID tag on the underground utility lines before backfilling to ensure effective it's management. However, due to changes an attitude and damages of sensors. By pressure and vibration during soil compacting, detecting rate is significantly reduced as well as it allows to use only one line of various pipes since it has an unique frequency. Also it is required too long time to reach to target point with an non-accurate navigational GPS receiver and hard to update existing data base with a manual input of new data in the field. To improve these problems, the researcher developed the field management system that apply with ball typed self-levelling marker which is free from the changes of attitude for sensors during compaction as well as has various radio frequency applicable to many kind of pipes and ensure fast positioning to target point using an incorporated system with PDA based DGPS receiver which allows loading a field GIS software and RFID detector. Further, it provides with viewing all of RFID data on the DGPS receiver screen directly and also input new data to existing data base in the field automatically.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.36-41
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• 1995

Recently, as the problems according to the deteriorated structure were gathering sterength, there were required the advent of the high peformance for polymer ceme at compostie in building constrution devision. The polymer cement mortar was developed for improvements of the various problems in ordinary cement mortar. finishing method using the super flowing polymer-based self levelling mortar for concrete slab and floor.

• Journal of Ocean Engineering and Technology
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• v.12 no.1
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• pp.153-161
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• 1998

This paper is to investigate the Fluidity of Antiwashout Underwater Concrete containing Fly Ash. The results of study are concluded as follows: the increase in Slump Flow value did not happen in the plain concrete which was replaced cement by Fly Ash; however, the maximum value could reach in the replacement of 30% of Fly Ash by weight of cement in the Fly Ash replaced concrete. On the condition of Fly Ash-Antiwashout Underwater Concrete in expecting 50 cm of the Slump Flow, it was necessary that the usage amount of Superplasticizer be around 1% of unit Binder, and 1.5% in 60 cm of the Slump Flow, respoectively.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.990-1003
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• 2006

To cope with the change of railway safety environment and to prevent the catastrophic accident, the railway safety management system was established through the legislation of railway safety rules. And to audit and evaluate the accomplishment of railway safety rules by the railway operators, the Integrated Railway Safety Audit System(IRSAS) has been conducting. This study find out the strategy to stabilize the IRSAS by applying Theory of Constraints(TOC) Thinking Process. For meeting the IRSAS's goal of effective levelling up of railway safety, the two necessary conditions, 1)the secure of substantial safety through the IRSAS and 2)the execution of efficient IRSAS, should be fulfilled. Estimated undesirable effects(UDEs) from the IRSAS were identified, and 3 of them were selected for creating the requisite conflict clouds. Entities from these conflict clouds were synthesized into a core conflict cloud that foamed the base of Current Reality Tree. The strategic direction for change extracted from the conflict cloud is the reinforcement of IRSAS preparation system including the level up of operator's self audit, the deepening of preliminary survey, the establishment of complementing system of audit check list and the build up of auditor's specialization. These injection were logically validated via a Future Reality Tree and expected to be confirmed by further progressing of IRSAS.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.665-678
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• 2007

It was applied the grouting method to fill densely the space between the bottom of the caisson and the ground with the grout mixture mixed with anti-washout admixture after locating accurately the precast caisson on three concrete landing pads but it is far different from a costly conventional method, which place concrete to build the foundation of reinforcement concrete on the spot after excavating inside of the temporary coffering wall for the bridge foundation in the sea. To verify the grouting method in advance, the full-scale trial test was performed twice on the land. After confirming the fluidity of material for the injection and some possible problems during construction and then enhancing the original design, the main process is ongoing and it has been finished 12 spots until now. The purpose of this study is to introduces for the first time in Korea the grouting method including the automatic and the manual monitoring process applied to, based on the main process of the caisson foundation finished already in the site. In a similar construction it is sincerely expected to be referred to in the future.