• Korean Journal of Materials Research
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• v.34 no.3
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• pp.175-183
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• 2024

Geopolymer, also known as alkali aluminum silicate, is used as a substitute for Portland cement, and it is also used as a binder because of its good adhesive properties and heat resistance. Since Davidovits developed Geopolymer matrix composites (GMCs) based on the binder properties of geopolymer, they have been utilized as flame exhaust ducts and aircraft fire protection materials. Geopolymer structures are formed through hydrolysis and dehydration reactions, and their physical properties can be influenced by reaction conditions such as concentration, reaction time, and temperature. The aim of this study is to examine the effects of silica size and aging time on the mechanical properties of composites. Commercial water glass and kaolin were used to synthesize geopolymers, and two types of silica powder were added to increase the silicon content. Using carbon fiber mats, a fiber-reinforced composite material was fabricated using the hand lay-up method. Spectroscopy was used to confirm polymerization, aging effects, and heat treatment, and composite materials were used to measure flexural strength. As a result, it was confirmed that the longer time aging and use of nano-sized silica particles were helpful in improving the mechanical properties of the geopolymer matrix composite.

• 유학연구
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• v.44
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• pp.303-333
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• 2018

In this paper, Peng Xiao's analysis of his Waitan Alchemy method was conducted, using Zhouyi Chantongqi Fenzhangtongzhenyi as the main text. Unlike former President Zhouyi Chantongqi, Peng Xiao's president Zhoui Chantongqi is characterized by the simultaneous appearance of Neidan and Waitan. It reveals the characteristics of the course. The study of Zhouyi Chantong qi Fenzhangtongzhenyi explains the shift in Waitan and Neitan in Taoism and the change in terms of its meaning and terminology. In this paper, we looked at the basic principles of Alchemy in Zhouyi Chantongqi Fenzhangtongzhenyi, the three main tools of Alchemy : pots, drugs, and fire control. In addition, Huangtan, Liangtan and Xuantan, which were acquired in the specific process of Alchemy, were also identified through text analysis. Finally, we looked at the effects and effects of the Waitan's Alchemy. These studies will provide easier access to the Waitan language, which is more diverse than the original Wei Boyang's Zhouyi Chantongqi and other comments. Based on this, another in-depth study of the Neitan idea of Fenzhangtongzhenyi will be possible in the future.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.698-707
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• 2002

A review is presented of experimental studies on the strength performance of concrete exposed at short-term and rapid heating as in a fire and after cooling. Emphasis is placed on concretes with high original compressive strengths, that is, high-strength concrete(HSC). The compressive strength-temperature relationships from the reviewed test programs are distinguished by the test methods used in obtaining the data(unstressed, unstressed residual strength, and stressed tests) and by the aggregate types(normal or lightweight), The compressive strength properties of HSC vary differently with temperature than those of NSC. HSC have higher rates of strength loss than lower strength concrete in the temperature range of between 20$^{\circ}C$ to about 400$^{\circ}C$. These difference become less significant at temperatures above 400$^{\circ}C$ compressive strengths of HSC at 800$^{\circ}C$ decrease to about 30 ％ of the original room temperature strength. A comparison of lest results with current code provisions on the effects of elevated temperatures on concrete compressive strength and elastic modulus shows that the CEN Eurocodes and the CEB provisions are unconservative.

• Fire Science and Engineering
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• v.30 no.6
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• pp.137-141
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• 2016

Cross contamination between a patient and rescuer or CPR trainees can occur when performing mouth to mouth ventilation during cardiopulmonary resuscitation (CPR). On the other hand, there has been a lack of research on the filtration efficacy of face shields that are designed to protect people from cross-contamination. This study aims to secure the safety of rescuers from communicable diseases in pre-hospital emergency settings and CPR trainees by verifying the protective effects of face shields. The FA shield and CM Shield were used to verify the safety. The bacteria collected from filters used by CPR trainees were incubated. These incubated bacteria were smeared onto the new filters, and were then blown out through the filters using a Bag Valve Mask (BVM) and the pathogens at the front and the back of the filters were checked. While the FA shield was effective in preventing the transmission of pathogens, the CM shield did not prevent the transmission of pathogens. Therefore, some of face shields that received national certification are ineffective in preventing cross-contamination. Accordingly, it is necessary to verify the safety of other face shields used domestically.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.324-329
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• 2020

The emergency evacuation support system provides a safe means of evacuation by preventing the inflow of smoke through the formation of a smoke shield curtain in fire situations and pressurizing fresh air to the inside of the smoke shield curtain. In this study, numerical analysis was performed to examine the effects of the hole size on the flow inside the smoke curtain. As the air supply size decreased, the flow rate through the air supply was formed relatively uniformly from the inlet to the outlet length of the emergency support system. In addition, the size of the air supply hole was more than 20 mm, the flow rate was very low near the outlet, so the air supply hole size should be smaller than 20 mm. In addition, the minor loss of the air supply hole was calculated to be K = 1.5 from the numerical results. Therefore, the proper design of an emergency evacuation support system is possible using the flow characteristics according to the size and minor loss of the air supply hole.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.363-370
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• 2016

Lightweight geopolymers are more readily produced and give higher fire resistant performance than foam cement concrete. Lowering the density of solid geopolymers can be achieved by inducing chemical reactions that entrain gases to foam the geopolymer structure. This paper reports on the effects of adding different concentrations of aluminum powder on the properties of cellular structured geopolymers. The apparent density of lightweight geopolymers has a range from 0.7 to $1.2g/m^3$ with 0.025, 0.05 and 0.10 wt% of a foaming agent concentration, which corresponds to about 37~60 % of the apparent density, $1.96g/cm^3$, of solid geopolymers. The compressive strength of cellular structured geopolymers decreased to 6~18 % of the compressive strength, 45 MPa of solid geopolymers. The microstructure of geopolymers gel was equivalent for both solid and cellular structured geopolymers. The workability of geopolymers with polyprophylene fibers needs to be improved as in fiber-reinforced cement concrete. The lightweight geopolymers could be used as indoor wall tile or board due to fire resistance and incombustibility of geopolymers.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.730-736
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• 2013

This study was conducted to examine the effects of the salt concentration in seafood wastewater on the high-rate anaerobic digestion process. In the general high-rate anaerobic process test, the TCODcr removal efficiency at 6 hr or more HRT was 81.1~0.7%, and the optimal HRT for seafood wastewater process was found to be 6 hr or more. The methane content in the biogas was 70.1~76.8% during the operation, and was hardly affected by the change in the influent load. The results of the anaerobic digestion efficiency according to the salt concentration showed that the removal efficiency of TCODcr was 83.4~89.2% below a $4,000mgCl^-/L$ salt concentration, and mid-70% at a $5,000mgCl^-/L$ salt concentration. Therefore, the salt concentration had to be kept below $4,000mgCl^-/L$ to ensure stable treatment efficiency. Below a $3,000mgCl^-/L$ salt concentration, the methane generation was 0.2999~0.346$m^3CH_4/kgCODrem.$, which was similar to the theoretical methane gas generation in STP condition ($0.35m^3CH_4/gTCODrem.$). The methane content in the biogas was 64.7~73.3% below a $3,000mgCl^-/L$ salt concentration, but decreased with an increase in the salt concentration, to 50.1~56.9% at a $4,000mgCl^-/L$ concentration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3220-3226
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• 2011

In order to monitor internal risk factors such as fire, terror, etc. on the subway station, the surveillance systems using CCTV and various kinds of sensors have been implemented and recently, introduction of surveillance systems using an advanced IT technology, sensor network technology is tried on several areas. Since 2007, Korean government has made an effort to develop the intelligent surveillance and monitoring system, which can monitor fire, intrusion, passenger congestion, health-state of structure, etc., by using wireless sensor network technology and intelligent video analytic technique. For that purpose, this study carried out field wireless communication environment test on Chungmuro Station of Seoul Metro on the basis of ZigBee that is considered as a representative wireless sensor network before field application of the intelligent integrated surveillance system being developed, arranged and analyzed and ZigBee based wireless communication environment test results on the platform and waiting room of Chungmuro Station on this paper. Results of wireless spectrum analysis on the platform and waiting room showed that there is no radio frequency overlapped with that of ZigBee based sensor network and no frequency interference with adjacent frequencies separated 10MHz or more. As results of wireless data transmission test using ZigBee showed that data transmission is influenced by multi-path fading effect from the number and flow rate of passengers on the platform or the waiting room rather than effects from entrance and exit of the train to/from the platform, it should be considered when implementing the intelligent integrated surveillance system on the station.

• Journal of Korean Society of Forest Science
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• v.112 no.1
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• pp.105-116
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• 2023

As forest fires' scale has increased, they have become disasters that destroy not only forests but also property, human psychological balance, and even human lives. As a result, governmental support has become a crucial part of the forest fire restoration process. Quickly restoring victims' quality of life (QOL) from not only an ecological perspective but also from their human perspective has become an important goal. Therefore, through structural equation modeling, this study analyzed effects of government support, post-traumatic stress disorder (PTSD), and resilience on 195 Uljin and Samcheok forest fire victims' QOL. In the final research model, the total standardized effect on QOL of government support to PTSD and resilience was found to have significant effect (0.417). By path, the effect of government support on QOL through resilience was verified as 0.172. Examination of the path between latent variables revealed that resilience had the greatest influence on QOL, and government support had a significant effect, thus confirming that they were the main factors affecting QOL.

• Journal of Korean Medical Ki-Gong Academy
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• v.11 no.1
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• pp.144-172
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• 2009

objectives : This research aimed to study the similar effects between Jwahun and Sojucheon_practice, as both Induces to SooSengg-HwaGang(the coordination of water and fire). methods : 141 recipients of the survey was conducted in the Jwahun room of Korean medicine Hospital, which contained to body reaction between the moment of the Jwahun and after the Jwahun. And the result of them compared with the body's response of Sojucheon_practice results : 1. In a survey, 78% of the patients had responses that were sweating. The area sweating a lot in the survey is the face, abdomen, chest and was, in this order, the ratio was high. About feeling of warmth and coolness, survey of those who felt the warmth ratio was 79%, those who did not feel the coolness ratio was 77%, most of the responses were warm bodies. 46% of patients replied that feels warm in the belly. It said the fact that Jwahun directly to the lower body is to warm. 2. Symptoms of congestion of the head on the survey, 78% of investigators did not appeal. Other investigators were responding they were dizzy. Research on pain and itching, but no response was at 84%. Among the responses to the itchiness, itching perineum was 11% of the respondents. The rest was weak. 3. Associated with defecation in the survey, the investigators found that 33% of respondents said fart. Urine is 22% of respondents said. Abdominal reactions, 33% of respondents answered was taking a tone in the abdomen. In response to the whole body reaction, the most relaxing 39% of the respondents said, 22% of respondents replied that the body feel lighter. 4. After Jwahun, belly is warm and cathartic reactions were the most responsive. This said that Jwahun even after, in the lower abdomen lasting warmth as can be seen. Smooth bowel movements disproves the abdominal organs is a good move. It will also be seen in the same context of bowel movements, abdominal response when just doing Jwahun. conclusions : Jwahun activate the meridians and through the perineum stimulation induced imdokmaek(任督脈) SooSengg-HwaGang(水升火降) to enable the training and some Sojucheon can have similar effects.