• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.763-768
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• 2001

The purpose of this study is to research a specific material characteristics of top down concrete at column joint and to reduce column joint opening. Based on the established top down study, the experiment to apply an real construction case is performed. When the concrete placed into joint of top down column, raised air bubble is left as opening. This study is examined the incomplete packing reason in the top down column and found to air deflation method. The result of study is below (1) As the method to minimize column opening caused from confined air, it is required that an air exhaust port installation in joint column. (2) From air exhaust port installation, most of air bubble in column part is exhausted. As the concrete placing height is going up, air bubble size is going smaller.

• Journal of the Korea Institute of Building Construction
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• v.5 no.4 s.18
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• pp.145-152
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• 2005

Long-term axial shortening of the vertical elements of tail buildings results in differential movements between two elements and may lead to the additional moments of connection beam and slab elements, and other secondary effects, such as cracks of partitions or curtain walls. Accurate prediction of time-dependent column shortening is essential for tall buildings from both strength and serviceability aspects. The compensation method is different from reinforced concrete and SRC(Steel Reinforced Concrete) members. The SRC columns are usually compensated according to total differential shortening between two vertical elements. In this study, column shortenings of 37-story W building under construction are predicted and compensated. The SRC column shortenings are compared with the actual column shortening by field measurement and the column shortenings are reanalysed and recompensated.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.6
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• pp.1208-1211
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• 1999

Semi HPLC using a column switching technique was used to determine the trace content of vitamin B12 in various foods. Total analytical time required less than 20 mins per sample and the recovery ratio was 99.9, 99.6, 100.1 and 99.8% for 1.0, 10.0, 100.0 and 1,000 g/kg, respectively. The content of vitamin B12 in various foods obtained using column switching method showed higher levels compared to labels in dried milk(0.5 g/100g) and in grain products(0.51~34.36 g/100g). Thus, this column switching method was more sensitive, effective and precise than the microbiological analysis currently used to determine the trace compounds like a vitamin B12.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.90-99
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• 2004

Stone column is one of the soft ground improvement method, which enhances ground conditions through ground water draining, settlement reducing and bearing capacity increasing complexly by using crushed stone instead of sand in general vertical drain methods. In recent, general construction material, sand is in short of supply, because of the unbalance of demand and supply. Also, the bearing capacity improving effect of stone column method is needed in many cases so the bearing capacity estimation is considered as important point. Nevertheless, adequate estimation methods to predict bearing capacity of stone column considering stone column and improving ground behavior reciprocally is not yet prepared. To contribute this situation, bearing capacity behavior of stone column were simulated as numerically on various property cases of crushed stone and surrounded ground. Through the numerical analysis of simulation results, bearing capacity behavior prediction formula was suggested. This formula was verified by comparing the prediction result with in situ test.

• Mass Spectrometry Letters
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• v.12 no.4
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• pp.186-191
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• 2021

A new method for chemical separation of light rare-earth elements (LREEs) using gas-pressurized extraction chromatography (GPEC) is described. GPEC is a microscale column chromatography system that features a constant flow of solvents, which is created by pressurized nitrogen gas. The separation column with a Teflon tubing was packed with LN resin. The proposed GPEC method facilitates production of lesser chemical wastes and faster separation owing to the use of low solvent volume compared to traditional column chromatography. We evaluated the separation of Ba, La, Ce, and Nd using various elution solvents. The column reproducibility of the proposed GPEC system ranged from 2.4% to 4.9% with RSDs of recoveries, and the column-to-column reproducibility ranged from 3.1% to 6.3% with RSDs of recoveries. The proposed technique is robust, and it can be useful for the fast separation of LREEs.

• Communications for Statistical Applications and Methods
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• v.2 no.2
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• pp.366-375
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• 1995

A method is presented for finding estimable functions in a row-column design. It can easily be applied because the method consists of solving equations derived from the design eithout using the design matrix. It determines not only the estimability of treatment effects but also between row(or column)and treatment effects.

• Analytical Science and Technology
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• v.37 no.2
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• pp.123-129
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• 2024

We present a rapid method for the determination of Cs, Sr, and Ba, heat generators found in highly active liquid wastes, by gas-pressurized extraction chromatography (GPEC) using a column containing a cation-exchange resin. GPEC is a microscale column chromatographic technique that uses a constant flow rate of solvent (0.07 mL/min) with pressurized nitrogen gas supplied through a valve. In particular, because this method uses a small sample volume (a few hundred microliters), it produces less chemical waste and allows for faster separation compared to traditional column chromatography. In this study, we evaluated the separation of Cs, Sr, and Ba using GPEC. The eluate from the column (GPEC or conventional column chromatography) was quantitatively analyzed using inductively coupled plasma-mass spectrometry to measure the column recovery and precision. The column reproducibility of the proposed GPEC system (RSDs of recoveries) ranged from 2.7 to 4.1 %, and the column recoveries for the three elements ranged from 72 to 98% when aqueous HCl was used as the eluent. The GPEC results are slightly different in efficiency and separation resolution compared to those of conventional column chromatography because of the differences in the eluent flow rate as well as the internal diameter and length of the column. However, the two methods had similar recoveries for Cs and Sr, and the precision of GPEC was improved by two-fold. Remarkably, the solvent volume required for GPEC analysis was five times lower than that of the conventional method, and the total analysis time was 11 times shorter.

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

• Korean Management Science Review
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• v.14 no.2
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• pp.69-79
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• 1997

The computational speed of interior point method of linear programming depends on the speed of Cholesky factorization. If the coefficient matrix A has dense columns then the matrix A.THETA. $A^{T}$ becomes a dense matrix. This causes Cholesky factorization to be slow. We study an efficient implementation method of the dense column splitting among dense column resolving technique and analyze the relation between dense column splitting and order methods to improve the sparsity of Cholesky factoror.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2001.11a
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• pp.34-39
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• 2001

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.