• Steel and Composite Structures
• /
• v.21 no.2
• /
• pp.443-460
• /
• 2016

In this paper, the efficiency and effectiveness of two strengthening methods for upgrading behavior of the two external weak reinforced concrete (RC) beam-column joints were experimentally investigated under cyclic loading. Since two deficient external RC joints with reduced beam height and low strength concrete were strengthened using one-way steel prop and curbs with and without steel revival sheets on the beam. The cyclic performance of these strengthened specimens were compared with two another control external RC beam-column joints, one the standard RC joint that had not two mentioned deficiencies and another had both. Therefore, four half-scale RC joints were tested under cyclic loading.The experimental results showed that these innovative strengthening methods (RC joint with revival sheet specially) surmounted the deficiencies of weak RC joints and upgraded their performance and bearing capacity, stiffness degradation, energy absorption, up to those of standard RC joint. Also, results exhibited that the prop at joint acted as a fuse element due to adding steel revival sheets on the RC beam and showed better behavior than that of the specimen without steel revival sheets. In other words by stiffening of beam, the prop collected all damages due to cyclic loading at itself and acted as the first line of defense and prevented from sever damages at RC joint.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.500-503
• /
• 1997

In this paper, we investigate the control methodology of inverter Airconditioner, using the three dimensional vector scheme. The method of three dimensional vector aims at the determination of optimal switching patterns for PWM to reduce switching loss and to improve the performance supplied voltage. The induction motors are widely used for home Airconditioners. These motors can be classified into two types: on or off control of Airconditioner and the speed control of motor. For speed control of motors, generally PWM methods are used. The PWM method based upon the modulation of triangular wave can not afford to supply line voltage to the motor sufficiently because of the capacity of processing speed of micro processors. Therefore airconditioner can not be operated efficiently. This problem can be solved with the method of three dimensional vector since it can increase the supplied voltage and maximum operating frequency of motor to 173V and 96Hz, respectively. As the result, this method shows 10 - 15% increase of voltage and 10% increase of operating frequency over the modulation of triangular wave. According to a theoretical study, the number of switching in the method of three dimensional vector is smaller than that of the modulation of triangular wave. The power consumption can be reduced and the supplied voltage can be increased. In other words, the efficiency of Airconditioner can be improved. We show that the method of three dimensional vector can supply higher voltage than the modulation of triangular method through the experiments and verify the degree of improvement of efficiency theoretically.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.6
• /
• pp.3631-3634
• /
• 2013

MicroRNAs (MiRNAs) play important roles in coordinating a variety of cellular processes and abnormal expression has been linked to the occurrence of several cancers. The miRNA miR-451 is downregulated in colorectal carcinoma (CRC) cells, suggested by several research groups including our own. In this study, synthetic miR-451 mimics were transfected into the SW620 human CRC cell line using Lipofectamine 2000 and expression of miR-451 was analyzed by real time PCR, while expression of CAB39, LKB1, AMPK, AKT, PI3K and Bcl2 was analyzed by Western blot, and cell growth was detected by MTT assay. In comparison to the controls, a significant increase in the expression of miR-451 was associated with significantly decreased expression of CAB39, LKB1, AMPK, AKT, PI3K and Bcl2. The capacity of cell proliferation was significantly decreased by miR-451 expression, which also inhibited cell growth. Our study confirmed that miR-451 has a repressive role in CRC cells by inhibiting cell growth through down-regulating the P13K/AKT pathway.

• Journal of the Korean Chemical Society
• /
• v.29 no.4
• /
• pp.365-371
• /
• 1985

A cationic dye, methylene blue $(MTB^+)$ was examined as a counter ion in the separation of organic and inorganic anions by ion-pair chromatography. Nonabsorbing anions could be indirectly detected by photometric detector with the assistance of MTB^+ in visible range (665nm). A mixture of anions was able to be separated with good base line resolution and high sensitivity. The capacity factors were also determined in various experimental conditions to study retention mechanism. The retention followed the ion-interaction model where the $MTB^+$ occupies a primary layer at the stationary phase while the analyte anion and other anions in the system compete for forming the secondary layer.

• Steel and Composite Structures
• /
• v.34 no.3
• /
• pp.347-359
• /
• 2020

The objective of this study is to experimentally scrutinize the axial performance of built-up concrete filled steel tube (CFT) columns composed of steel plates. In this case, the main parameters cross section types, compressive strength of filled concrete, and the effect of welding lines. Welded built-up steel box columns are fabricated by connecting two pieces of cold-formed U-shaped or four pieces of L-shaped thin steel plates with continuous penetration groove welding line located at mid-depth of stub column section. Furthermore, traditional square steel box sections with no welding lines are investigated for the comparison of axial behavior between the generic and build-up cross sections. Accordingly, 20 stub columns with thickness and height of 2 and 300 mm have been manufactured. As a result, welding lines in built-up specimens act as stiffeners because have higher strength and thickness in comparison to the plates. Subsequently, by increasing the welding lines, the load bearing capacity of stub columns has been increased in comparison to the traditional series. Furthermore, for specimens with the same confinement steel tubes and concrete core, increment of B/t ratio has reduced the ductility and axial strength.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.29 no.10
• /
• pp.497-503
• /
• 2017

In recent years, studies on the prediction of building load using Artificial Neural Network (ANN) models have been actively conducted in the field of building energy In general, building loads predicted by ANN models show a sharp deviation unless large data sets are used for learning. On the other hands, some of the input data are hard to be acquired by common measuring devices. In this work, we estimate daily building loads with a limited number of input data and fewer pastdatasets (3 to 10 days). The proposed model with fewer input data gave satisfactory results as regards to the ASHRAE Guide Line showing 21% in CVRMSE and -3.23% in MBE. However, the level of accuracy cannot be enhanced since data used for learning are insufficient and the typical ANN models cannot account for thermal capacity effects of the building. An attempt proposed in this work is that learning procersses are sequenced frequrently and past data are accumulated for performance improvement. As a result, the model met the guidelines provided by ASHRAE, DOE, and IPMVP with by 17%, -1.4% in CVRMSE and MBE, respectively.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2002.02a
• /
• pp.285-290
• /
• 2002

Power systems are becoming larger and larger for meeting electric power demand. Therefore, the over-currents resulting from contingencies such short circuits are increasing higher. The Maximum short circuit current of modern power system is becoming so large that circuit breaker are not expected th be able to shut down the current in the future. In order to cut over-currents, a system composed of a superconducting fault current limiter(SFCL) and traditional breaker seems to provide a promising solution for future power operation. In present paper, three line-to-ground fault is assumed to happen at the center of 345kV transmission lines in a large capacity electric power system The superconducting fault current limiter was represented using a commutation type, which consists of a non-inductive superconducting coil and current limiting element(resistor or reactor). The introduction merits of the SFCL were investigated quantitatively by RTDS/EMTDC from the viewpoint of current limiting performance, the prevention of the voltage drop at the load bus and comparison characteristics for two type SFCL. Desired design specification and operation parameters of SFCL were also given qualitatively by the performance evaluation of the two type SFCL in the power system.

• Preventive Nutrition and Food Science
• /
• v.8 no.3
• /
• pp.289-293
• /
• 2003

Antioxidant activity and nicotine degradation activity (NDA) of 21 medicinal herbs were determined by using a 1,1-diphenol-2-picrylhydrazyl (DPPH) method and a PLC/PRF5 human liver cell line method, respectively, to develop an anti-smoking aid. The highest and lowest antioxidant activities represented by $IC_{50}$/ value were 30 $\mu$g/mL of Eugenia caryophyllus and 3,270 $\mu$g/mL of Panax ginseng C. A. Meyer, respectively. Antioxidant activity of Eugenia caryophyllus was equal to 38.0$\pm$1.2 mg VCEAC(vitamin C equivalent antioxidant capacity)/ g herb. The highest and lowest NDA values were 1.81 of Astrgalus membranaceus Bunge and 1.01 of Raphani seed and Lespedeza tomentosa Sieb, respectively. Eleven medicinal herbs with high antioxidant activity and/or NDA were selected to make an herbal tea. The herbal tea had high antioxidant activity (50 $\mu$g/mL $IC_{50}$/ and 22.4$\pm$1.4 mgVCEAC/g) and NDA (1.243). The medicinal herb tea could help smokers quitting smoking by degrading and exhausting nicotine accumulated in body and removing reactive oxygen species.

• Journal of Information Technology Services
• /
• v.12 no.1
• /
• pp.229-245
• /
• 2013

The information security industry market is sluggish despite high expectation for its growth, and thus policies are required to define the causes and to address these issues. The policy formulation requires various historical market and human resource data for analyzing the industry, which cannot be guaranteed secured. This study executed face-to-face in-depth interviews with the frontline businesses in order to gather live opinions and to analyze industry's value chain, problems, and difficulties with a view to defining policy tasks for the development of the industry. The findings of the study revealed the current technical level of the information security industry, the frontline difficulty, and industrial ecosystem status. Based on these findings, the industry revitalization policy was devised and proposed. Objectives of the policy included the fostering of capacity to conceptualize, plan, and design industrial strategies based on the analysis of the industry's value chain and ecosystem, the expansion of the industry's value-added through the enhanced securing and management of the Intellectual Property Rights (IPR), and the nurturing of the security Human Resources (HR) in line with the industrial demand.

• Journal of Chest Surgery
• /
• v.19 no.2
• /
• pp.188-196
• /
• 1986

Spirometry and regional function studies using 99m-Technetium were performed preoperatively to predict postoperative pulmonary function change in 34 patients who had various pulmonary resectional procedures at the Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital. Between two months and fourteen months postoperation all the patients were reinvestigated with spirometry and clinical examination to evaluate their functional respiratory status. The postoperative obtained values, especially forced vital capacity [FVC] and forced expiratory volume in one second [FEV1] among the other parameters were compared with the postoperative predicted values. Estimated values of FVC and FEV1 derived from preoperative spirometry and quantitative perfusion lung scan correlated well with the measured postoperative values. The linear regression line derived from correlation between postoperative estimated[X] and postoperative measured[Y] values of FVC and FEV1 in all patients are as follows; 1. Y=0.76x + 0.39 in correlation of FVC [r=0.91] 2. Y=0.88x + 0.17 in correlation of FEV1 [r=0.96],br> This method of estimation was one of the best methods of predicting postoperative pulmonary function change and valuable in determining the extent of safe resection and postoperative prognosis to a poor risk patient with chronic obstructive lung disease.