• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2006.05a
• /
• pp.215-218
• /
• 2006

A study was made to investigate microstructural evolution and mechanical properties of ultra-fine grained (UFG) pure-Ti produced by equal channel angular (ECA) pressings. The deformed structures were analyzed by finite element method and transmission electron microscopy with the increment of straining. After 4 isothermal ECA pressings, initial coarse grains ($30{\mu}m$) were significantly refined to ${\sim}0.3{\mu}m$ with homogeneous distribution of microstructure which was resulted from $180^{\circ}$ rotation of the sample between pressings. UFG pure-Ti exhibited the considerable improvement in yield strength while losing strain hardening capacity as compared to coarse grained microstructure at ambient temperature, which was mainly attributed to ultra-fine grain microstructure with non-equilibrium grain boundaries.

• Annual Conference of KIPS
• /
• 2003.05a
• /
• pp.527-530
• /
• 2003

In this paper, we implemented the voxel coloring method to reconstruct 3D object from synthetic input Images. Then compare the result between using standard voxel coloring and using coarse-to-fine method. We compared using different voxel space site to see the difference of time processing and the result of 3D object. Photorealistic 3D object reconstruction is a challenging problem in computer graphics. Vexel coloring considered the reconstruction problem as a color reconstruction problem, instead of shape reconstruction problem. This method works by discretizing scene space into yokels, then traversed and colored those in special order. Also there is an extension of voxel coloring method far decreasing the amount of processing time called coarse-to-fine method. This. method works using low resolution instead of high resolution as input and after processing finish, apply some kind of search strategy.

• Proceedings of the Korea Water Resources Association Conference
• /
• 1984.07a
• /
• pp.7-21
• /
• 1984

Entrainment and deposition experiments were counducted in fresh water on four groups of sediments: three well-defined sediments of uniform composition and narrow-size distribution (1 to 9 um, 10 to 50 um, and 50 to 90 um), and a fourth group which was a mixture of these three sediments. In the entrainment experiments and at a particular stress, the steady-state suspended sediment concentration of the coarse group was the lowest while the concentrations of the fine and medium groups were higher that that of the coarse group but were similar to each other. Deposition experiments generally showed an exponential decrease of suspended sediment concentration with time with the decay time being a function of particle size and applied stress.

• Advances in concrete construction
• /
• v.5 no.3
• /
• pp.201-219
• /
• 2017

With the rapid growth in construction sector, it becomes all the more important to assess the amount of Construction and Demolition (C&D) waste being generated and analyze the practices needed to handle and use this waste before final disposal. This serves waste management and disposal issues, paving way to waste utilization in construction industry from the sustainability point of view. C&D waste constitutes a major bulk of total solid waste produced in the world. In this work, an attempt is made to study the performance of concrete using water soaked Recycled Coarse Aggregates (RCA) in replacement levels of 0%, 25%, 50%, 75% and 100% to Natural Coarse Aggregates (NCA). Experiments were designed and conducted to study the performance of RCA based concrete. Further suitable performance enhancement techniques to RCA based concrete were attempted, to achieve compressive strength at least equal to or more than that for no RCA based concrete (control concrete). Performance enhancement study is reported here for 50% and 100% RCA based concretes. All four techniques attempted have given favorable results encouraging use of RCA based concretes with full replacement levels, to adopt RCA based concrete in structural applications, without any kind of concern to the stake holder. Further attempts have also been made to use Recycled Fine Aggregates (RFA) with appropriate modifications to serve as fine aggregates in mortar and concrete. Using RFA blended with river sand fractions as well as RFA with Iron Ore Tailings (IOT) fractions, have given good results to serve as fine aggregates to the extent of 100% replacement levels in mortars and concretes.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1998.03a
• /
• pp.94-99
• /
• 1998

The CAD system which enables to design and draw the screw thread gauges was developed and constructed. This system was proposed based on Visual C++ Version 5.0. Even beginner can get drawings as well as concerned data for the manufacturing of screw thread limit gauges by selecting the input data. This system was constructed from relevant standards and regulations (based on the Korean Standard and referred to ISO and JIS), handbooks and textbooks. The system shall provide more powerful and user friendly tool for design and drawing for screw thread gauges such as metric fine and coarse threads, unified fine and coarse threads, Parallel and taper pipe threads. The results of this system are proved to be in good agreement with concerned standards and regulations.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.5
• /
• pp.85-91
• /
• 1998

The CAD system which enables to design and draw the screw thread gauges was developed and constructed. This system was proposed based on Visual C++ Version 5.0. Even beginners can get drawings as well as concerned data for the manufacturing of screw thread limit gauges by selecting the input data. This system was constructed form relevant standards and regulations and was developed based on the Korean Standard and referred to ISO, JIS, handbooks and textbooks. This system shall provide more powerful and user friendly tool for design and drawing for screw thread gauges such as metric fine and coarse threads, unified fine and coarse threads, parallel and taper pipe threads. The results of this system are proved to be in good agreement with concerned standards and regulations.

• Journal of Institute of Control, Robotics and Systems
• /
• v.7 no.12
• /
• pp.985-992
• /
• 2001

This paper proposes a self-organizing fuzzy modeling(SOFUM)which an create a new hyperplane shaped cluster and adjust parameters of the fuzzy model in repetition. The suggested algorithm SOFUM is composed of four steps: coarse tuning. fine tuning cluster creation and optimization of learning rates. In the coarse tuning fuzzy C-regression model(FCRM) clustering and weighted recursive least squared (WRLS) algorithm are used and in the fine tuning gradient descent algorithm is used to adjust parameters of the fuzzy model precisely. In the cluster creation, a new hyperplane shaped cluster is created by applying multiple regression to input/output data with relatively large fuzzy entropy based on parameter tunings of fuzzy model. And learning rates are optimized by utilizing meiosis-genetic algorithm in the optimization of learning rates To check the effectiveness of the suggested algorithm two examples are examined and the performance of the identified fuzzy model is demonstrated via computer simulation.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.165-168
• /
• 2004

Due to the demolition of old structures, primarily buildings, an amount of discharged construction wastes are increased. From the construction wastes, recycled aggregate can be used as a useful resource for concrete. However, its application to structural member is very limited. In this experimental study, the compressive strength of spun-concrete using recycled aggregate was investigated. Coarse aggregate was replaced with $100\%$ of the recycled coarse aggregate, and recycled fine aggregate was replaced with various amount. According to the test results, the specimen of spun-concrete showed uniform compressive strength regardless the amount of replaced recycled fine aggregate.

• Proceedings of the Korea Institute of Convergence Signal Processing
• /
• 2000.12a
• /
• pp.77-80
• /
• 2000

In this paper, we propose a method of detecting the distance between two vehicles by computing the disparity of the close-rang vehicle stereo image using two digital cameras. The boundary(or edge) of the object considered the vehicle is obtained by using the modified wavelet transform which has multi-resolution characteristics. We analyze the histogram using the coarse-to-fine method considering a whole feature and increase the resolution to obtain the exact disparity. From the results, the distance of the close-range vehicle is detected effectively by using our proposed method.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.1
• /
• pp.17-25
• /
• 2002

This system is composed of fine and coarse apparatus, measurement system and control system. Piezoelectric actuator is designed far fee positioning. We make a study of precision apparatus that is used in the various industrial machine. The study was carried out to develope a precision positioning apparatus, consisting of servo motor and piezoelectric actuator Coarse positioning using lead screw is thrived by servo motor. Control system output a signal from laser interferometer to amplifier of servo motor and piezoelectric actuator after digital signal processing (DSP). Resolution of this apparatus measure with laser interferometer. In this study, design method and control system with ultra precision position apparatus are researched. As the first step, we have estimated for control performance and system stability before an actual apparatus is manufactured by MATLAB with SIMUUNK including various frictions those are composed of pre-design and system modeling.