• Journal of the Korea Institute of Building Construction
• /
• v.5 no.1 s.15
• /
• pp.105-109
• /
• 2005

Classified with concrete as placing ways - direct ways, sheath way - and placing directing flange direction, web direction - is analyzed section and strength of hardened concrete. The results of this study is belows the more fluid of concrete, the more useful to top-down method. To minimize the voids of the reverse placement joints, It is more effect to use the sheath method than direct method in concrete placement. If the joint face is a plane, it is impossible to extract the air bubbles which caused voids, so we should consider about this, and decide to select which type of joints.

• IE interfaces
• /
• v.13 no.2
• /
• pp.157-165
• /
• 2000

In this paper, an efficient method is proposed to place the cooling lines(CLS) and ejector pins(EPS) of mold design. The other components of mold, except CLS and EPS, can be generated automatically by batch processing. But the placements and sizes of CLS and EPS depend on the shapes of a part, so that the design works of CLS and EPS should be processed interactively. Using the pre-defined reference points, the positions of CLS and EPS can be determined interactively. By the proposed method, the interference occurred during placing CLS and EPS can be avoided, and the proper lengths of them can be calculated automatically. The information of the positions and lengths are stored in BOM database for generating a machining data. The proposed method is implemented with Unigraphics API functions and C language, tested on Unigraphics V15.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.5
• /
• pp.17-23
• /
• 1985

This paper describes a method for the design of a self-tuning controller of single-input/single-output systems with system noises and obsrrvation noises. The method uses state-space techniques to assign the closed-loop system poles to desired locations, but the control law is made up of process input and output measurement values, so that state estimation is unnecessary. Also the difficulties of tracking of reference inputs in state.space pole-placing control are tackled by including the reference input in the cost function proposed by Beger.

• Journal of the Korea Institute of Building Construction
• /
• v.10 no.4
• /
• pp.123-132
• /
• 2010

Rebar work accounts for approximately 30% of the total construction costs for rebars and concrete. Recently, the high rising prices of rebars have become one of the principle factors of rising construction costs. Therefore, construction companies are putting much effort into loss reduction of rebars. Consequently, in this study, we wished to present loss reduction methods of rebars before the preparation of the placing drawings. To devise such methods, we collected previous case studies and analyzed methods that were applied for loss reduction. As a result of the analysis, we were able to find the following methods for loss reduction of rebars: method of reducing the number of splices at the mat foundation, method of reducing splice length at the internal columns or walls of the underground parking lot, method of reducing cap-ties of internal beams of basement floors excluding perimeter beams, and method of reducing anchorage length at the internal column or wall of the underground parking lot. Based on those analysis results, we presented our own loss reduction methods of rebars. Applying our methods resulted in considerable loss reduction.

• Restorative Dentistry and Endodontics
• /
• v.23 no.2
• /
• pp.639-646
• /
• 1998

To evaluate the effect of interface conditions and retention grooves in the Class V composite resin restoration of the maxillary first premolar, the distribution of the values of stress and displacement was analyzed with the two-dimensional finite element method. The results were obtained as follows : 1. Boundary elements and Stiffness values could be used as the interface parameters in the, finite element method. 2. The amount of restriction of the displacement at the cervical margin by placing a retention groove at the cervical wall was about three times as high as that by placing a retention groove at the occlusal wall. 3. Because of the relative amount of tensile components of the stress values in the bucco-lingual direction, the possibility of dislocation of the restoration was much higher at the cervical margin than at the occlusal margin. 4. It might be recommended that both occlusal and cervical retention grooves be used routinely, but if one, it be placed at the cervical wall.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.2
• /
• pp.447-455
• /
• 2014

This study was intended to estimate the efficiency of inducing fiber arrangement in UHPCC (Ultra High Performance Cementitious Composites). For the purpose, UHPCC members produced by several different placing methods according to flow characteristics were prepared; flexural behaviors were compared and correlation between the flexural behavior and the characteristics of fiber arrangement was investigated. Test results showed that placing method for inducing specific fiber arrangement had a considerable influence on the flexural performance. The standard specimen in which fibers are induced to be directed parallel to the principle tensile direction presented higher flexural tensile strength but lower variation. Therefore it should be considered that the flexural tensile strength actually developed in UHPCC member may be highly different and in lager variation. The qualitative variation of fiber arrangement according to the flow of UHPCC was also predicted considering the flow pattern and the boundary effect; the prediction provided good explanation to the difference in the flexural behavior according to the induced flow.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.10b
• /
• pp.1107-1112
• /
• 2000

When top down method is used, it could be a construction method trouble in column joint, between the former concrete and the latter. It could bring a void and weak concrete in column. The purpose of this study is finding a way to prevent concrete void and concrete suitable for top down, through V-metering for top down column and concrete experiment.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04a
• /
• pp.205-210
• /
• 1998

The strength and dimension of recent constructed subway box structures are increased considerably. These increases are resulting in much initial cracks by hydration heat and thermal stress. According to previous studies, decrease of cement amount by using superplasticizer and L/H value is the best way to eliminate hydration heat and stress. The analyses using finite element model were performed. By the result of analysis, the use of superplasticizer and the decrease of the change of longitudinal placing length are proved to be more effective for elimination thermal cracks. By ACI Code, for longitudinal placing length 25 m, the amount of wall temperature reinforcement is always lack despite of concrete mix proportion. With analytical result and the inducing crack joint, the in-site test were performed and the analytical results proved to be effective. However, the inducing crack joint is not effective if it is a small size.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.120-121
• /
• 2017

Generally, slump of plain concrete slab is about 120~150mm and slump loss is easy to occur. So, water is added to concrete because this method is convenient for Placing. In order to solve this problem, performance evaluation of concrete using improvement type PC admixture was carried out. Target slump is 210mm and compressive strength is 18MPa. As a result, slump reference value was satisfied 60 minutes after placing and 7-day compressive strength was 21~25MPa.

• 제어로봇시스템학회:학술대회논문집
• /
• 1989.10a
• /
• pp.907-912
• /
• 1989

A new procedure is presented for optimally placing closed-loop poles of multivariable continuous-time systems in specified regions via linear-quadratic(LQ) state-feedback design. This method has the advantages of pole-placement and LQ-design. In addition, it provides minimum feedback gains in the control law.