• Journal of the Korea Institute of Building Construction
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• v.9 no.5
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• pp.127-133
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• 2009

It is important to increase the strength of binders in order to enhance the strength of concrete. However, when the mineral admixture used for high strength concrete is incorporated individually, its dispersibility decreases due to the phenomenon of compaction, which reduces its fluidity and results in insufficient strength being created. To solve this problem, we can pre-mix each binder in advance to disperse a mineral admixture among binders, which will strengthen the fluidity and strength of concrete. Therefore, this study analyzed the properties of high strength concrete depending on the mix method used, to determine the effect of pre-mix cements ranging from W/B 15 to 35%. It was found that the fluidity of pre-mix increased to a level higher than that of individual mix due to its dispersion and ball bearing effect. The air content was slightly decreased from the result of individual mix due to the micro filler effect, which causes fine particles of silica-fume to fill the voids among cement particles, while the setting time of pre-mix was shorter than that of individual mix, because enhanced dispersion of pre-mix affects hydration heat time. The compressive strength of pre-mix increased due to the phenomenon of compaction of gap structure, and the variation of coefficient decreased by 1.69% on average in strength variation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.37-40
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• 2007

This study investigates the effect of the pre-mix cement to the physical properties of the concrete according to the various combinations of the binders and the silica fume types. The results are summarized as following. For the properties of the fresh, the fluidity in the case that OPC+cilica fume-blast-furnace slag is appropriate compared to OPC+cilica fume+fly ash. Expecially, it is favorable when pre-mix is used. The fluidity time of the A, B depending on silica fume types is favorable, but it is decreased on C. The air content depending on silica fume types is low when the fly ash is used. Specially, the air content in the case that pre-mix is used is low caused by the dispersion of the silica fume. For the properties of the hardened concrete, the compressive and flexible strength when the blast-furnace slag is pre-mixed are high, and they exceed OPC. The strength depending on the silica fume types is high on B, and the strength of the others is similar.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.93-97
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• 2008

The study analyzed on each kind of basic characteristics in mortar to prove an effect of pre-mix cement, ultra high strength binder. The results were as follows. in characteristics of not set mortar, fluidity time was the quickest at the time of using POBSA and was more delayed at the time of using Fly Ash than at the time of using Blast Furnace Slag as a binder. Mortar ring flow and flow con flow got smaller as fluidity time got longer, on the contrary to fluidity time. Unit capacity mass was smaller at the time of using Fly Ash than at the time of using Blast Furnace Slag. According to pre-mix, it was difficult to discover a regular tendency. In characteristics of hardening mortar, the 28th day compressive strength was better than thing mixed after measuring separately in pre-mix. According to a binder's kind, Silica Fume B, C was better than Silica Fume A.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.172-173
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• 2019

In this study, application of ultra high performance concrete(UHPC) with pre-mix binder were presented on civil, architectural and special field. The UHPC can be applied to a variety of site due to its excellent flowability, mechanical properties, impact resistance and fire resistance. It is necessary to apply the pre-mix binder to take into account the productivity and performance improvements of the UHPC.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.199-200
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• 2023

This paper presents a study on the selection of optimal mix proportions for producing lightweight pre-foam concrete as a substitute for Autoclaved Lightweight Concrete (ALC) without the accelerated curing. The study was conducted using a rapid hardening binder made from by-products of the steel industry as the primary raw material. The experimental results established the optimal mix proportions, which included retarder content, water/binder ratio, foam content, and fiber inclusion amount, for the production of lightweight foam concrete. The optimal mix proportion was determined to have a retarder content at the minimum amount required to secure the working time, W/B of 35%, a foam content limited to 65% or less, and a fiber inclusion amount of 0.05% or less.

• Korean journal of food and cookery science
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• v.33 no.2
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• pp.155-161
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• 2017

Purpose: The purpose of this study was to determine the quality characteristics of gluten-free frying pre-mix with insoluble dietary fiber powder (IDFP) from Chinese cabbage by-product. Methods: Frying powder mix was prepared with 0.5, 1.0, 1.5 or 2.0% IDFP. Fried powder mix only whit brown rice powder was used as a control. Spreadability, pick-up ratio and color of batter, texture, moisture and oil contents, oil absorption and sensory evaluation of fried sweet potato were determined. Results: L and a-values of batter decreased with increasing amount of IDFP, whereas b-value increased with IDFP addition. Hardness and crispiness of fried sweet potato increased with IDFP addition until 1.5%. Moisture content of fried sweet potato increased with higher IDFP addition whereas oil content and oil absorption decreased with increasing amount of IDFP. Sensory evaluation of fried sweet potato showed the best results in the 0.5% of IDFP addition group. Conclusion: Overall preference of IDFP samples was significantly higher than that of control. Based on the study, the optimal amount of IDFP for gluten-free fried powder mix was determined to be 0.5-1.5%.

• Tuberculosis and Respiratory Diseases
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• v.84 no.1
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• pp.74-83
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• 2021

Background: This study compared the treatment outcomes of patients with multidrug-resistant tuberculosis (MDR-TB) before and after the implementation of public-private mix (PPM). Factors affecting treatment success were also investigated. Methods: Data from culture-confirmed pulmonary MDR-TB patients who commenced MDR-TB treatment at Pusan National University Hospital between January 2003 and December 2017 were retrospectively reviewed. Patients were divided into two groups in terms of PPM status: pre-PPM period, patients who commenced MDR-TB treatment between 2003 and 2010; and post-PPM period, patients treated between 2011 and 2017. Results: A total of 176 patients were included (64 and 112 in the pre- and post-PPM periods, respectively). 36.9% of the patients were resistant to a fluoroquinolone or a second-line injectable drug, or both. The overall treatment success rate was 72.7%. The success rate of post-PPM patients was higher than that of pre-PPM patients (79.5% vs. 60.9%, p=0.008). Also, loss to follow-up was lower in the post-PPM period (5.4% vs. 15.6%, p=0.023). In multivariate regression analysis, age ≥65 years, body mass index ≤18.5 kg/m², previous TB treatment, bilateral lung involvement, and extensively drug-resistant (XDR)- or pre-XDR-TB were associated with poorer treatment outcomes. However, the use of bedaquiline or delamanid for ≥1 month increased the treatment success. Conclusion: The treatment success rate in MDR-TB patients was higher in the post-PPM period than in the pre-PPM period, particularly because of the low rate of loss to follow-up. To ensure comprehensive patient-centered PPM in South Korea, investment and other support must be adequate.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.275-276
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• 2018

Ultra high performance concrete(UHPC) represents high early age autogenous shrinkage strain due to its low water-to-binder ratio(W/B) and high fineness admixture usage. It has been reported that fiber can control restrained tensile stress and crack. The purpose of the present study is, therefore, to investigate the autogenous shrinkage as well as mechanical properties including compressive strength, flexural strength and modulus of elasticity on the UHPC with fiber type and pre-mix of binder.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.581-584
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• 2004

High ductile fiber reinforced mortar suitable for wet-mix shotcreting (sprayable ductile mortar) 10 the fresh state, while maintaining tensile strain-hardening behavior in the hardened state, has been developed based on micromechanics and workability control. In the development concept of sprayable ductile mortar, micromechanics is adopted to properly select the matrix, fiber, and interface properties to exhibit strain hardening and multiple cracking behaviors in the composites. Within the pre-determined micromechanical constraints, the workability is controlled by optimizing mix proportions. A series of spray tests show the excellent pumpability and sprayability of the sprayable ductile mortar. Subsequent direct tensile tests demonstrate that the tensile performance of sprayed mortar is comparable to that of cast mortar, for the same mix design.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.373-376
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• 2008

Ultra High Strength Concrete(UHSC) is necessary a clear presentation about mechanical property that is different from normal strength concrete and an evaluation of serviceability of high rise building which is used ultra high strength concrete. To mixing ultra high strength concrete with $f_{ck}$=150MPa pre-mix cement were manufactured and experimental study were conducted to evaluated on the mixing properties and compressive strength with major variables as unit cement contents, water-binder ratio and type of pre-mix cement. As a test result, it is shown that the concrete mixing time is required about 5$^{\sim}$6 minute untill the each materials(ordinary portland cement, silica fume, blast-furnace slag powder and anhydrite) are revitalized enough. A slump flow of fresh concrete are shown about 700$^{\sim}$750mm with proper viscosity. And average value of concrete compressive strength are shown about 77% in 7days, 87% in 14days and 102% in 56days for 28days of concrete material age. From this experimental study, a proper mixture proportion of pre-mix cement are recommended about 54$^{\sim}$59% OPC, 25$^{\sim}$30% blast-furnace slag powder and 10$^{\sim}$15% silica fume for mix the ultra high strength concrete with $f_{ck}$=150MPa.