• KCI Concrete Journal
• /
• v.13 no.2
• /
• pp.58-66
• /
• 2001

Recently, polymer-modified mortar has been studied for proposed use on industrial floors as top coat with thin thickness, typically 5~15mm. The purpose of this study is to evaluate basic properties of self-leveling materials using polymer dispersions as kinds of SBR, PAE, St/BA with thin coat (under 3mm). Superplasticizer and thickener have been included in the mixes to reduce bleeding and drying shrinkage as well as to facilitate the workability required. The self-leveling materials using four types of polymer dispersion are prepared with polymer-cement ratio which respectively range from 50% and 75%, and tested for basic characteristics such as unit weight, air content, flow, consistency change and adhesion in tension. From the test results, the self-leveling materials using PAE emulsion at curing age of 28days are almost equal to those of conventional floor using urethane and epoxy resin. The adhesion in tension of self-leveling mortars using SBR latex and PAE emulsion at curing age of 3days is over 17 kgf/cm$^2$(1.67MPa). Consistency change is strongly dependent on the type of polymer dispersion. It is concluded that the self-leveling materials using polymer dispersions can be used in the same manner as conventional floor using thermosetting resin in practical applications, in the selection of polymer dispersions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.372-378
• /
• 2005

Finite element analysis of concrete slab system in apartment building was executed using the tables of orthogonal arrays, and optimal design process was proposed. At first, experimental results show that sound peak components to influence the overall level and the rating of floor impact sound insulation were coincident with natural frequencies of the reinforced concrete slab. Finite element model of concrete slab was compared with experimental results, and well corresponded with an error of less than 10%. The tables of orthogonal arrays were used for finite element analysis with 8 factors. 3 related to material properties and 5 related to slab shape parameters and its results were analyzed by statistical method, ANOVA. The most effective factor among them was slab thickness, and main effect factor from slab shape parameters was different from each natural frequency. The interaction was found in the higher mode over $3^{rd}$ natural frequency. From main effect plot and interaction plot, the optimal design factor to increase the natural frequency was determined.

• Structural Engineering and Mechanics
• /
• v.64 no.3
• /
• pp.339-346
• /
• 2017

Slabs prevent harmful effects of fire that may occur in any floor. However, it is necessary to protect the slabs from fire. Insulation materials may be appropriate to protect reinforced concrete (RC) slab from elevated temperature. In the present study, a model has been developed in artificial neural network (ANN) to predict the moment capacity ($M_r$) of RC slabs exposed to fire with insulation material. 672 data were obtained for ANN model through author's prepared program. Input layer in model consisted of seven input parameters; such as effective depth (d), ratio of d'/d, thermal conductivity coefficient ($k_{insulation}$), insulation materials thickness ($L_{insulation}$), reinforcement area ($A_{st}$), fire exposure time ($t_{\exp}$), and concrete compressive strength ($f_c$). The predicted $M_r$ by ANN was consistent with the obtained $M_r$ by author. It is proposed to ease computational complexity in determining $M_r$ using ANN. The effects of using insulation material on the moment capacity in RC slabs were also investigated. Insulating material with low thermal conductivity has been found to be more effective for durability to high temperature.

• Journal of Korean Society of Steel Construction
• /
• v.14 no.4
• /
• pp.481-487
• /
• 2002

Currently, the load transfer's mechanism from a beam to a column has yet to ve clarified in a concrete filled steel tubular (CFT) structure with a connection type of an exterior diaphragm. The loads for each floor are transferred to the concrete core from a steel beam through ha contacted face between an in-filled concrete and the interior surface of a steel tube. Thus, a Push-Out test was performed to investigate the load transfer mechanism. A total of 30 samples were tested to confirm the bond stress and/or axial load distribution between a steel tube and in-filled concrete for CFT column. The main parameters considered for this study included concrete type, steel tube-shape/length, and the effect of a weld joint wit ha backing strip for a column splice. Test results were summarized to confirm load transfer behavior between a concrete and steel tube for each experimental parameter, using the analytical approach to verify experimental results.

• Journal of the Korea Institute of Building Construction
• /
• v.23 no.4
• /
• pp.465-476
• /
• 2023

This study introduces the development of a precast concrete double-wall, applicable to basement construction in apartment buildings. Unlike traditional precast concrete double walls, the developed double-wall doesn't require specialized manufacturing equipment such as a lathe. The constructability of these advanced technologies was validated through a full-scale mock-up test using the precast concrete double wall. The test specimens were constructed to represent a structural wall with a thickness of 250mm. It was observed that the quality of the in-situ concrete, filled between two single panels of 110mm thickness each, was excellent. The construction efficiency of the developed double-wall system for basement construction in an apartment building was also examined. Expert interviews about installation times of precast concrete elements were conducted to evaluate the speed of the basement floor's installation. The results showed that installation of precast concrete elements, including the proposed double walls, could be completed within 20 to 29 days for a basement in an apartment building. This indicates a three-fold increase in construction efficiency compared to traditional methods relying on in-situ casting.

• Journal of Korean Society of Steel Construction
• /
• v.9 no.4 s.33
• /
• pp.589-600
• /
• 1997

Cold-formed deck sections are used in many composite floor slab applications wherein the steel deck serves not only as the form for the concrete during construction but also as the principal tensile reinforcement for the bottom fiber of the composite slab. This paper provides the results of an experimental study performed for the composite slabs with the new shaped deck plates with the locking ribs, the dove tails, and the powerful embossment, which are the mechanical means to improve positive interlocking effect between the deck and the concrete. A total of 28 specimens are tested to investigate the composite effects between the concrete and metal deck plate. Important parameters in this are the span length, the thickness of the deck plate, support condition, and whether shear studs are placed at each support or not. The test results are summarized for the maximum load and failure behavior for the specimens.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.981-984
• /
• 2008

The super tall building above 100 floors is required that each floor's height is more than 4 meters, and each core wall's thickness is more than 60cm. Therefore, for the successive accomplishment of super tall building, the full scale mock-up test was required. The test results are as follows; Real strength of core wall was satisfied with design strength at 28 days regardless of types of strength, and according to the consolidation effect, lower part's strength was a little higher than upper part's strength. Lateral force of HSC was evaluated with max. $4.5ton/m^2$, and hydration temperature of mock-up test was evaluated that maximun heat of central part revealed about $80^{\circ}C$ at 70MPa and $65^{\circ}C$ at 50MPa, and, the difference between inner and outter part revealed about $30^{\circ}C$ at 70MPa and $12^{\circ}C$ at 50MPa. Also, no crack by hydration temperature was not shown on the surface.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2008.11a
• /
• pp.93-98
• /
• 2008

Haeundae Doosan We've The Zenith project is adjacent to Suyoung-bay, now it is in the process of excavation and foundation work. The main use of the tower is residence which height is 300m and 80 floor, the highest residential reinforced concrete building through the Orient. It is comprised of 3 high- rised buildings and 1 low-rised building, the basement is 230m wide and 200m length sized mass structure. The lateral resistance system is acted effectively against the lateral load and satisfactorily against the wind vibration by the 4 direction extension of the center core wall($700{\sim}800mm$ thickness) and reinforced concrete column set around the slab. Flat-plate slab system(250mm thickness) is adjusted for the slab system and it enables effective work process and shortening the working term by minimizing the ceiling height and not needing to install perimeter beam and drop panel. The strength and serviceability of the structure is able to be monitored and estimated constantly through the health monitoring system during the construction and after the construction.

• Journal of Animal Environmental Science
• /
• v.11 no.3
• /
• pp.153-160
• /
• 2005

This study was conducted to determine the effect of floor type of finishing building and increasing market weight of finishing Pigs on Performance, carcass traits and pork quality. Four hundred and forty-four finishing pigs were confined and administered with different floor type(concrete slat and bedded with sawdust) and increasing market weight(110kg to 130kg) of finishing building. The result obtained from this study were summarized as follows; 1. There was no significant difference between the floor type of finishing building in the body weight gain, feed intake and gain per feed. And also increasing market weight of finishing pigs was not affected the performance of finishing pigs. 2. Increasing market weight of finishing pigs affect the carcass yield. The market weight at 130kg showed more amount of each cut of carcass, especially the belly portion was higher, but backfat thickness was not different. 3. Carcass traits did not show any significant difference due to the difference of market weight of finishing pig and floor type of finishing building. 4. There was no significant difference in the chemical compositions and meat color of pork loin between the floor type of finishing building and increasing market weight of finishing pigs.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.18 no.1
• /
• pp.4038-4051
• /
• 1976

This study was intended to provide the basic design creteria for the refrigerated storage, and to estimate the required optimum capacity of refrigerator for the different sizes and kinds of the existing fruit storage. The structural characteristics of the existing fruit storages in Pyungtaek-khun of Kyungki-do were surveyed. The average out-door air temperature during the expected storage life after harvesting, was obtained by analyzing the weather information. The heat transfer rates through the different models of storage walls were estimated. The refrigerating load required for different models of fruit storage was analyzed in the basis of out-door air temperature. The results obtained in this study are summarized as follows: 1. The fruit storages surveyed were constructed on-ground, under-ground and sub-ground type buildings. The majority of them being the on-ground buildings are mostly made of earth bricks with double walls. Rice hull was mostly used as the insulating materials for their walls and ceilings. About 42% of the buildings were with the horizontal ceiling, 22% with sloped ceiling, and about 36% without ceiling. About 60% of the storage buildings had floor without using insulated material. They were made of compacted earth. 2. There is no difference in heat transfer among six different types of double walls. The double wall, however, gives much less heat transfer than the single wall. Therefore, the double wall is recommended as the walls of the fruit storage on the point of heat transfer. Especially, in case of the single wall using concrete, the heat transfer is about five time of the double walls. It is evident that concrete is not proper wall material for the fruit storage without using special insulating material. 3. The heat transfer through the storage walls is in inverse proportion to the thickness of rice hull which is mostly used as the insulating material in the surveyed area. It is recommended that the thickness of rice hull used as the insulating material far storage wall is about 20cm in consideration of the decreasing rate of heat transfer and the available storage area. 4. The design refrigerating load for the on-ground storages having 20 pyung area is estimated in 4.07 to 4.16 ton refrigeration for double walls, and 5.23 to 6.97 ton refrigeration for single walls. During the long storage life, however, the average daily refrigerating load is ranged from 0.93 to 0.95 ton refrigeration for double walls, and from 1.15 to 1.47 ton refrigeration for single walls, respectively. 5. In case of single walls, 50.8 to 61.4 percent to total refrigerating load during the long storage life is caused by the heat transferred into the room space through walls, ceiling and floor. On the other hand, 39.1 to 40.7 percent is for the double walls. 6. The design and average daily refrigerating load increases in linear proportion to the size of storage area. As the size increases, the increasing rate of the refrigerating load is raised in proportion to the heat transfer rate of the wall. 7. The refrigerating load during the long storage life has close relationship to the out-door air temperature. The maximum refrigeration load is shown in later May, which is amounted to about 50 percent to the design refrigerating load. 8. It is noted that when the wall material having high heat transfer rate, such as the single wall made of concrete, is used, heating facilities are required for the period of later December to early February.