• Journal of Drive and Control
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• v.10 no.2
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• pp.1-6
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• 2013

This study describes a method which can attenuate reaction force effectively for an air spring system composed of an air spring and auxiliary chamber. For the analysis, the nonlinear governing equation of the air spring system is derived. For a performance improvement of the system, change of the heat transfer effect and the mass flow rates is included in the analysis of the air spring system. The simulation study is presented to show the reaction force is changed by variations in heat transfer characteristics and the air spring system of isothermal process has the best performance. As a result, to improve attenuation characteristics of reaction force, a process in the air spring system should be maintained near isothermal process.

• Journal of Drive and Control
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• v.14 no.1
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• pp.29-34
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• 2017

This study analyzed a life test method for a power take-off (PTO) gearbox. An engine transfers mechanical power (rotation and torque) to a hydraulic pump through a PTO Gearbox with one input shaft and three output shafts. PTO gear box durability under high loads over long time periods was tested using dynamometers. In order to reflect the rated operating conditions, power must be distributed to each output shaft, and experiments were conducted under various conditions to verify the characteristics of the distributed power. An accelerated life test was designed using speed and torque as acceleration factors. Also, efficiency tests were conducted under various load conditions. Also, a lubrication oil composition analysis was performed to analyze gearbox wear status.

• ETRI Journal
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• v.28 no.5
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• pp.545-554
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• 2006

A widely tunable multi-channel grating cavity laser is proposed and experimentally demonstrated. The device is implemented in Littman configuration with an echelle grating based on Rowland circle construction and realized by monolithically integrating all elements in an InP substrate. Lasing wavelength is selected by turning on an amplifier and the appropriate channel element in the array, and it is tuned by controlling light deflection electrically. The 6-channel device exhibits a tuning range of about 50 nm with a side mode suppression ratio of more than 30 dB. This is accomplished by adjusting the applied current of the dispersive element and phase control section.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.1
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• pp.59-65
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• 2008

Manufacturing Execution System (MES) is a system that companies can use to measure and control critical production activities. This paper shows case study of implementation of MES (Manufacturing Execution System) and its methodology in a medium sized production company. This study focused on two important things in MES implementation. First, it provides critical success factors (CSFs) and construction method for success of MES implementation. Second, it presents guidelines for MES implementation in small and medium-size company. Some of the benefits with regards to MES implementation and its results are introduced in the end of this paper.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.928-933
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• 1998

The temperature and stress behaviour of mass concrete pier at early ages was analysed based on the finite element method. The pier investigated is a three-dimensional structure of which the cross-sectional shape varies from a circle to an ellipsoid along the longitudinal axis. In order to obtain the transient temperature and stress distributions in the structure, a three dimensional method was adopted, because the structure of this type cannot be modeled accurately by a two-dimensional method. Temperature analysis was performed by taking into consideration of the cement type and content, boundary and environment conditions including the variations of atmospheric temperature and wind velocity. The results of this study may be useful for the temperature control to restrain thermal cracking and the construction management to design the resonable curing method of mass concrete structure.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1095-1100
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• 2000

Concrete structure often exhibit cracks due to the combination of material construction and design error. Minor crack can be tolerated depending on exposure condition, but major cracks are aesthetically unpleasant and affect the durability and safety of the structure. All of the reinforced concrete structure have many inevitable cracks for various reason such as drying shrinkage, heat liberation of cement and over loads. Epoxy resin injection widely used for repairing cracks in concrete is too sensitive to high temperature. Besides, the problem in the epoxy resin injection is the difficulty of quality control after execution. Whereas, Ultra Fine Cement is similar in coefficient of thermal expansion and modulus of elasticity to concrete. The objective of the study is to find out that it is possible for Ultra Fine Cement to be used for repairing cracks in reinforced concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1057-1062
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• 2000

The purpose of this study is to practice the method which can estimate 28-days strength of concrete in advance. This method is made for reliant quality control. Based on existing experiment, concrete that flyash added and normal concrete are placed into wall structure, and it is examined the difference between experiment use concrete and field use concrete. The result of this study are as follows : 1) Core test specimen have 10% lower strength to standard curing specimen. 2) At 28-days accelerated strength by microwave, average 35% in normal concrete, average 23% in flyash added concrete. 3) At coefficient of determination between compressive strength and accelerated strength, 0.84 in normal concrete core, 0.86 in standard curing normal concrete, 0.86 in flyash added concrete, 0.90 in standard curing flyash added concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.191-196
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• 1997

Steel is the most used as materials for construction and corrosion expansion of steel due to outdoor corrosive environmental factor bring serious problem on the durability of concrete structures time after time. It is the purpose of this study to see whether it is effective of not, when sacrificial anode method is adapted. Indoor accelerated corrosion testing was carried out to see its effective in a short term. From the mid result, potential of steel in concrete in case of adapting sacrifice anode method satisfacts protection standard value (less than-850mV vs CSE), therefore sacrificial anode method is considered as a proper protection steps against corrosion of steel.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.413-416
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• 2005

The super early hardening cement is widely used for reducing construction period. But there are some problems with handling the cement because the loss of workability is so big to control. In this study, the fluidity properties of super early hardening cement paste was evaluated at early age of hydration by using gel-time determination method. 4 types of set controlling agent were selected and combinations of them were used for gel-time test. As a result, the gel-time of super early hardening cement paste was extended up to 20 minutes by using the combinations of several types set controlling agent.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.169-172
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• 2005

Today, peoples have much interest about safety while an abnormal weather phenomenon is weighted increased. R.C buildings are consisting of main loaded members. Concrete are brittle materials and they are which come to brittle fracture rapidly by progress of cracks. With the exchange of such research in inside and outside of the country, the structure measurement method of having used PZT and the optical fiber (FBG) will be the actual condition which has accomplished the stock. Specially, seismic activity that gives damage to construction and members happens in on time. Therefore, the purpose of this study is the fundamental research which detects damagesof main members using the compound sensor which consisted of the radio sensors of resistance, PZT, and FM system.