• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7C
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• pp.743-750
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• 2003

With the expansion of computer technology the mobility of a mobile agent code having the flexibility in the dispersive computer situation is used to set up the applications distributed on the Internet. As it also has the ability to transmit the mobile code of a mobile agent and to receive it from a far-off host, the executive circumstances of the host system in which an agent is executed have to access to an agent code and the executive state capable of executing an agent code. Therefore, it is difficult to prevent the forgery, the alteration and the wrong execution of an agent from a malicious host. This dissertation suggests the mechanism which can protect an agent from the malicious action through the executive pursuit of a code-named mobile agent. The security of this mechanism is verified through the protective process of a mobile agent in this mechanism.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.921-924
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• 2000

The purpose of this paper is to investigate the effects of admixture such as AE water reducing agent and Flyash on properties of cement mortar for floor. As for the effects of AE water reducing agent kinds, fluidity and air content increase in order for melamine type, lignine type and naphtalene type. As Flyash contents increase, fluidity shows high, but air content shows decline tendency. compressive strength according to AE water reducing agent kinds increase in order for melamine type, lignine type and naphtalene type. As AE water reducing agent content increases, it shows to be decreased. As for the effects of Flyash, it retards at early age but at later age it gains high with increase of Flyash contents due to pozzanic reaction. Drying shrinkage shows to be docreased slightly with increase of AE water reducing agent.

• Fire Science and Engineering
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• v.22 no.5
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• pp.83-89
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• 2008

Using the high expansion foam generator of ISO 7203-2 which spray 6 liter at 5 bar, foam generation characteristics was studied. Wind flow rate, foam screen, concentration of foam agent solution and concentration of salt of water were varied to find the effect of the parameters on foam generation. Research result showed that expansion ratio of foam was increased with wind flow rate. The expansion ratio of foam in the perforated type standard screen was higher than the wire mesh screen. Expansion ratio and drainage time were increased with increase of foam solution concentration. But a increase of salt concentration in solution showed the decrease of expansion ratio and drainage time.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.929-932
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• 2000

In this paper, physical properties of fresh and hardened mortar for floor using expansion agent are described under various grain shape, grading and chloride contents of aggregates. According to experimental results, as fineness modulous increase, fluidity show high it also shows high with cement mortar using riversand and continuous distribution of grading. We can not detect any difference in fluidity according to chloride contents. Air content shows to be decreased with crushed stone having large fineness modulous and continuous distribute on of grading. chloride content does not influence on the air content. compressive strength tends to increase when crushed sand with continuous distribution of grading is used and chloride contents decreases.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.288-289
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• 2014

The purpose of this research is to examine strength properties of epoxy-modified mortar with expansive and swelling agent contents. The polymer-modified mortars (PMMs) using epoxy resin are prepared with various polymer-binder ratios, expansive and swelling agent contents. The PMMs using epoxy resin are tested for compressive, flexural and tensile strengths. As a result, the strength properties of the PMMs using epoxy resin are depending on the polymer-binder ratio rather than expansive and swelling agent content, and are remarkably improved over unmodified mortar (UMM).

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1996.11a
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• pp.57-61
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• 1996

Our goal was to make a cost-effective automatic fire extinguishing system for the engine compartment use of automobiles. We designed this system for the engine compartment. This system consists of 1)foam extinguisher, 2)four nozzles, 3)a pipe arrangement, and 4)an extinguishing device which is equipped with a glass bulb as detector. First and foremost, the extinguishing device was carefully designed to keep the system cost to a minimum. Second, a AFFF foam extinguisher was used because no other fire-fighting agents proved effective against fire in the engine compartment. The AFFF(Aqueous Film Forming Foam) agent which was used in the extinguisher is the 3M company's Light Water. We sought, however, to make other foams by using Halon 1301 and Halon alternatives such as HCFC Blend A, HFC-227ea. We selected these alternatives instead of air in order to raise the expansion ratio of the AFFF agent. By these means we discovered that it is possible to increase the expansion ration of the AFFF agent up to 44:1. We then demonstrated that our automatic fire extinguishing system is the most effective and lowest cost-system yet devised for passenger cars.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.229-233
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• 1995

In this study we have the properties of drying shrinkage crack of hardened cement mortar using admixtures. The drying shrinkage cracking test process has been examined by the restrained drying shrinkage strain by restraining rate measuring properties of strain-with- restraint by JIS original proposal and keeps a flow value of mortar about 100$\pm$5%. The results show that the usage of shrinkage reducing agent 1.5% was effective on the control of drying shrinkage in OPC and CP by restraining rate 20% and strain-with-restraing 20~30 $\mu$, the usage of expansion agent 0.45% was effective by restraining rate 50~60% and strain-with-restraint 40~80$\mu$, and the effectiveness was increased with shrinkage reducing agent. Also. admixtures such as Flyash, CP and NC reduced restrained shrinkage and drying shrinkage cracking and more with shrinkage reducing agent

• Resources Recycling
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• v.21 no.6
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• pp.12-22
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• 2012

This study investigated a utilization technology of light burned dolomite. light burned dolomite ($CaMg(CO_3)_2$) generated in furnace (steel manufacturer) is an alternative to quick lime. Using light burned dolomite has an effect on reducing the consumption of fluorite slag MgO concentration in supersaturated solution by prolonging the life of softening effect. Armophous MgO, not containing periclase is formed by firing dolomite under $800^{\circ}C$. It has larger surface area and higher reactivity than periclase, and also shows better expansion effect than quicklime. Due to those effects, therefore, armophous MgO produced from light burned dolomite is used as an alternative expansion agent in mortar. In the experiment, characteristics of light burned dolomite were compared to those of existing expansion agents such as anhydrite and quicklime. Then, each expansion and shrinkage rates were measured over a period of about 3 months in both of 1m Jis mold at labscale and apartment mortar flooring at field scale. In the result, it was observed that light burned dolomite in mortar flooring more compensates for the expansion and shrinkage rates than the existing expansion agents, showing low expansion rate of below 0.05% and also decreases the crack.

• Journal of Food Hygiene and Safety
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• v.16 no.3
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• pp.227-231
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• 2001

Basic materials for various making gangjung, various concentration 0∼25.0%(w/v) of coating agent and 0∼20.0% of substitutional materials carried out an experiment in sensory evaluation, expansion rate and hardness of substitutional materials. The results are as follows: 1. Added coating agent far improvement of decreasing aroma, arabic gum and dextrin significant from 20.0% to 25.0% compared with others. A good results flavor strength score and hedonic score of added 20.0% arabic gum are highest. 2. Expansion rate is caused by substitutional waxy rice, expansion rate decreased above 20.0% as tapioca above 5.0%, rice above 10.0%, brown waxy rice and wheat flour 15.0%. 3. After firing gangjung of substitutional materials, hardness increase concentration of substitutional materials. Therefore substitutional materials added to tapioca below 5.0%, rice and wheat flour 10.0%, brown waxy rice 15.0% is thought of good.

• Korean Journal of Materials Research
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• v.30 no.2
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• pp.93-98
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• 2020

Effective control of the heat generated from electronics and semiconductor devices requires a high thermal conductivity and a low thermal expansion coefficient appropriate for devices or modules. A method of reducing the thermal expansion coefficient of Cu has been suggested wherein a ceramic filler having a low thermal expansion coefficient is applied to Cu, which has high thermal conductivity. In this study, using pressureless sintering rather than costly pressure sintering, a polymer solution synthesis method was used to make nano-sized Cu powder for application to Cu matrix with an AlN filler. Due to the low sinterability, the sintered Cu prepared from commercial Cu powder included large pores inside the sintered bodies. A sintered Cu body with Zn, as a liquid phase sintering agent, was prepared by the polymer solution synthesis method for exclusion of pores, which affect thermal conductivity and thermal expansion. The pressureless sintered Cu bodies including Zn showed higher thermal conductivity (180 W/m·K) and lower thermal expansion coefficient (15.8×10^-6/℃) than did the monolithic synthesized Cu sintered body.