• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.119-122
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• 2009

As architectures have recently become high-risers and mega-structured, stable high strength products have been ensured. Accordingly, use of precast concrete accouplement has been increased in order to facilitate air compression and rationalize construction. Since not only external heating but a1so internal temperature rise caused by the accumulation of cement hydration heat in manufacturing process, precast concrete members with large cross-section used for high-rise mega-structure's columns and beams may exhibit different temperature history compared to the precast concrete members for wall and sub-floor with relatively small cross-sections. Therefore, this study aims to elucidate the characteristics of temperature history of mass concrete members cast with high-strength concrete fur precast concrete application. In this study, large cross-sectional precast concrete mock-up, unit cement quantity, and temperature histories in manufacturing precast concrete member under different curing condition were inclusively investigated.

• Geomechanics and Engineering
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• v.32 no.6
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• pp.601-613
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• 2023

Low liquid limit silt, widely distributed in the middle and down reaches of Yellow River, has the disadvantages of poor grading, less clay content and poor colloidal activity. It is very easy to cause vehicle jumping at the bridge-embankment transition section when the low liquid limit silt used as the backfill at the abutment back. In this paper, a series of laboratory tests were carried out to study the physical and mechanical properties of the low liquid limit silt used as back filling. Ground granulated blast furnace slag (GGBFS) was excited by active MgO and hydrated lime to solidify silt as abutment backfill. The optimum ratio of firming agent and the compaction and mechanical properties of reinforced soil were revealed through compaction test and unconfined compressive strength (UCS) test. Scanning electron microscope (SEM) test was used to study the pore characteristics and hydration products of reinforced soil. 6% hydrated lime and alkali activated slag were used to solidify silt and fill the model of subgrade respectively. The pavement settlement regulation and soil internal stress-strain regulation of subgrade with different materials under uniformly distributed load were studied by model experiment. The effect of alkali activated slag curing agent on curing silt was verified. The research results can provide technical support for highway construction in silt area of the Yellow River alluvial plain.

• Geomechanics and Engineering
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• v.35 no.1
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• pp.95-108
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• 2023

Soft soil ground is a crucial factor limiting the development of the construction of transportation infrastructure in coastal areas. Soft soil is characterized by low strength, low permeability and high compressibility. However, the ordinary treatment method uses Portland cement to solidify the soft soil, which has low early strength and requires a long curing time. Microbially induced carbonate precipitation (MICP) is an emerging method to address geo-environmental problems associated with geotechnical materials. In this study, a method of bio-cementitious mortars consisting of MICP and cement was proposed to stabilize the soft soil. A series of laboratory tests were conducted on MICP-treated and cement-MICP-treated (C-MICP-treated) soft soils to improve mechanical properties. Microscale observations were also undertaken to reveal the underlying mechanism of cement-soil treated by MICP. The results showed that cohesion and internal friction angles of MICP-treated soft soil were greater than those of remolded soft soil. The UCS, elastic modulus and toughness of C-MICP-treated soft soil with high moisture content (50%, 60%, 70%, 80%) were improved compared to traditional cement-soil. A remarkable difference was observed that the MICP process mainly played a role in the early curing stage (i.e., within 14 days) while cement hydration continued during the whole process. Micro-characterization revealed that the calcium carbonate filling the pores enhanced the soft soil.

• Composites Research
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• v.14 no.6
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• pp.47-58
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• 2001

This paper describes applications of cure monitoring techniques by using embedded fiber optic strain sensors, which are extrinsic Fabry-Perot interoferometric (EFPI) and/or fiber Bra99 grating (FBG) sensors, to three kinds of molding methods of autoclave, FW and RTM molding methods. In these applications, internal strain of high-temperature curing resin was monitored by EFPI sensors. From theme experimental results, it was shown that strain caused by thermal shrink at cooling stage could be measured well. In addition, several specific matters to these molding methods were considered. As thor an autoclave molding of unidirectional FRP laminates, it was confirmed that off-axis strain of unidirectional FRP could be monitored by EFPI sensors. As for FW molding using room-temperature (RT) cured resin, it was found that the strain outputs from EFPI sensors represented curing shrinkage as well as thermal strain and the convergence meant finish of cure reaction. It was also shown that this curing shrinkage should be evaluated with consideration on logarithmic change in stiffness of matrix resin. As for a RTM melding, both EFPI and FBC sensors were employed to measure strain. The results showed that FBG sensors hale also good potential for strain monitoring at cooling stage, while the non-uniform thermal residual strain of textile affected the FBG spectrum after molding. This study has proven that embedded fiber optic strain sensors hale practical ability of cure monitoring of FRP. However, development of automatic installation methods of sensors remains as a problem to be solved for applications to practical products.

• Korean Journal of Construction Engineering and Management
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• v.20 no.1
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• pp.133-140
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• 2019

The concrete mix should be designed and produced to reflect the specific site conditions during concrete placement. That is, the concrete mix design should be planned considering temperatures, work environments, pouring methods, etc. The objective of this research is to understand the external factors of curing temperature and delay time that influence concrete strengths during pouring work, and provide concrete mix design that can be most robust to the effects of external factors. The Taguchi's robust method is used in preparing the concrete mix design to achieve the research objective. In a case study, an indoor concrete test was performed to find the optimal combination of concrete mixes with external factors of curing temperature and delay time. Concrete test cylinders were made to test concrete strengths given different external factors. The study results showed that the optimal performance of concrete strength can be achieved by applying the robust method when preparing a concrete mix design.

• Journal of Korean Medical classics
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• v.24 no.1
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• pp.95-105
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• 2011

The cough is generally known as a symptom occurred from Lung. But it was descriptive of the symptom every internal organs can cause in "HwangjenaegyeongSomun Haelon". The reason is that, when a pathogenic Gi attack human body, the body skin which have the relationship to Lung is attacked firstly. But the internal organs preside over each seasons of the year, so the season's presiding organ is ultimately attacked. And in "Somun Haelon" the partner symptoms of five solid organs cough and six hollow organs cough are being described, so we can distinguish between each internal organs coughs. Clinically, the cough is most common symptom and one of the most difficult symptom. In my opinion, the origin organ of cough is very various, but the doctor fix their thinking to the Lung, so the cough became a most difficult symptom. This thesis describe pathogenesis and partner symptoms of five solid organs cough and six hollow organs cough. And illustrate clinical examples and some medical prescriptions. Intend to show that various treatment after differentiation of syndromes[辨證施治] surely needed for effective curing of a cough.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.1
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• pp.333-337
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• 2007

Cellulitis is a infectious disease characterized by acute purulent inflammation clinically manifested by erythema, pain or heating sensation caused by palpation, chilling sign and mild to moderate fever. in western medicine most part of the treatment is focused on injecting routine antibiotics hoping for the pathogen(in the case bacteria) to be treated but instead causing the bacteria to be resistant to antibiotics and consequently leads to longer admission. In oriental medicine Cellulitis belongs to the cathegory of Ong(癰), Bal(發) or Dandok(丹毒) on symptoms. The chief cause of acute Cellulitis is the evil of wet and heat blended and the postraumatic infection evil. We experienced a case of acute cellulitis defined as Bicheonbal(비천발) and Chokbaebal(足背發). We attempted to use both methods using acupuncture, herbal medicine(Gamidangkwuijeomtong-tang(加味當歸拈痛湯)) as well as routine antibiotic treatment and as a result we have achieved remarkable results in laboratory tests though there was no difference in shortening the curing process compared to the average time that it take to cure when admitted to western medical center.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.17-30
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• 2023

This study investigates the impact of water immersion and high temperature on the shear strength of cemented sand through direct shear tests. Standard Jumunjin sand was used and cemented with binders, such as ultra-rapid hardening cement and an epoxy aqueous solution. The binder was mixed at concentrations of 4%, 8%, or 12%. Subsequently, cylindrical cemented specimens with a diameter of 64 mm and height of 25 mm were produced using compaction. The curing period was three days, and the specimens were cured under dry air, immersion, and heating conditions. The heating condition involved subjecting the immersed specimens to a microwave oven three times for three minutes to achieve an internal temperature of approximately 90℃. Regardless of the binder type, the cohesion of the cemented sand increased with higher binder content, whereas the internal friction angle exhibited a slight increase or decrease. Compared with ultra-rapid hardening cemented sand, epoxy-cemented sand displayed an average cohesion that was five times higher and an internal friction angle that was 10° higher. Overall, irrespective of binder type, the shear strength decreased during water immersion and increased during heating. Notably, the epoxy-cemented sand exhibited a three-fold increase in cohesion and a more than 20° increase in the internal friction angle during heating.

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.283-291
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• 2011

As the construction industry has recently been transformed by the emergence of ubiquitous and intelligent technology, there have been major changes in the management methods employed. Specifically, next-generation construction management systems have been developed that collect and analyze many pieces of information in real time by using various wireless sensors and networks. The purpose of this study is to understand the current status of Ubiquitous Sensor Networks (USN) in the construction sector, and to gain fundamental data for a system of measuring concrete curing temperature in a construction site that employs a USN. By investigating the application status of USN, it was confirmed that USN has mainly been applied to the maintenance of facilities, safety management, and quality control. In addition, a field experiment in which the curing temperature of concrete was measured using a USN was carried out to evaluate two systems with wireless sensor networks, and the applicability of these systems on site was confirmed. However, it is estimated that the embedded wireless sensor type is affected by metal equipment on site, internal battery of sensor and concrete depth, and studies to provide more stable system by USN are thus required.

• The Journal of Korean Medicine
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• v.20 no.2
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• pp.98-107
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• 1999

This study aimed to find out Oyo-Tang's effects on allergic asthma using the Egg-White Implant(EWI) method model recommended by Siqueira et al. Oyo-Tang has widely been prescribed and used in Oriental Medicine for controlling and curing of cough, nasal obstruction, pharyngeal pain and hoarseness. Previous studies have demonstrated that Oyo-Tang has analgesic, sedative, anticonvulsive, antitussive and antihistamine effects. But it was uncertain whether Oyo-Tang could inhibit the allergic reactions, to alleviate the symptoms of allergic asthma. With such aim. the respiratory patterns and eosinophil infiltration in the tracheal mucosa of rats with experimentally induced allergic asthma (using EWI method) were mainly observed. The results are as follows: 1. Oyo-Tang decreased the number of poor respiration with respect to control group (P<0.05) 2. Oyo-Tang decreased the number of eosinophils infiltrated in tracheal mucosa with respect control group (P<0.05). The above results demonstrate that Oyo-Tang has the inhibitory effects on the process allergic asthma and suggest that it could be used in relieving patients of the symptoms caused allergic asthma.