• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.1
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• pp.27-33
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• 2023

An optimized design of the transportation insulated box must be considered to control the thermal damage in order to maintain the fresh condition for temperature-sensitive medicine and frozen food safety. The inside temperature of the insulated box is a natural convection enclosure state, thermal stratification naturally occurs as time passes in case of with outside heat load. The latent heat material (LHM) placement inside the box maintains the target temperature of the product for temperature fluctuations during transport, and LHM application is a common and efficient method. In this work, inside temperature stratification in an insulated box depending on the LHM pack position is numerically simulated and experimented. The insulated box is made up of vacuum insulation panel (VIP), and LHM modules are placed over six faces inside the box, with the same weight. The temperature curves for 72 hrs as experiment results clearly show the temperature stratification in the upper, middle, and lower at the LHM melting time region. However, the temperature stratification state is uniformly changed in accordance with the condition of the upper and lower placement weight of the LHM pack. And also, the temperature uniformity by changed placement weight of LHM has an effect on maintaining time for target air temperature inside the box. These results provide information on the optimized design of the insulated box with LHM.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.355-363
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• 2015

HVDC technology has become popular as an economic mode of bulk power transmission over very long distances. Polymeric insulators in HVDC power transmission lines are affected by surface tracking and erosion problems due to contamination deposit, which pose a greater challenge in maintaining the reliability of the HVDC system. In addition, polymeric insulators are also naturally affected by aging due to various environmental stresses, which in turn accelerates the surface tracking and erosion problems. Research works towards the improvement of tracking and erosion resistance of polymeric insulators by adding nano-sized fillers in the base material are being carried out worldwide. However, surface tracking and erosion performance of nano-filled aged polymeric insulators for HVDC applications are not well reported. Hence, in the present work, tracking and erosion resistance of the nano $Al(OH)_3$ filled silicone rubber insulation material has been evaluated under DC voltages at different filler concentrations and aged conditions, as per IEC 60587 test procedures. Leakage current and contact angle measurements were carried out to understand the surface hydrophobicity. Moving average technique was used to analyze the trend followed by leakage current. Water aged specimen shows less tracking resistance when compared with thermal aged specimen. It is observed that nano-filler concentration of 5% is even sufficient to get better tracking/erosion resistance under DC voltages.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.4
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• pp.201-208
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• 2011

Objectives: According to the compliance of the asbestos-related regulation, every building has to be inspected for asbestos presence before its abatement work. This study was performed for identifying the types and contents of asbestos in building bulk samples. Materials and Methods: Bulk samples were collected during the asbestos inspection in 2010. We grouped the bulk samples into the regulated asbestos containing materials(RACM), presumed asbestos containing materials(PACM), and construction products. Additionally, the types of asbestos in all bulk samples were identified by polarization microscopy(PLM). Results: The RACMs were from building, house, pipe and facility. The RACMs were found mainly building (72.1%) and house (93.7%). The contents of chrysotile in building, house and facility were 66.9% (1-90%), 89.7% (2-90%) and 11.0% (2-90%), respectively. PACMs were surfacing material, thermal system insulation (TSI), and miscellaneous material. The miscellaneous materials that showed a high detection rate (79.2%) were ceiling, roofing and wall materials. Among them, the roofing materials had high chrysotile content(9.7%, 2-21%), followed by wall (8.7%, 2-21%) and ceiling (3.4%, 1-17%). In the construction products, asbestos was found mainly in slate (92.6%, 2-21%), including chrysotile. The slate had high asbestos content (9.7%, 2-21%), followed by cement flat board (8.7%, 2-19%) and textile (3.4%, 1-17%) Conclusions: Utilizing these results, it would be contributed to construct a useful ACM database and prevent from asbestos exposure to workers in the asbestos abatement and maintenance works.

• Fashion & Textile Research Journal
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• v.15 no.2
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• pp.231-239
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• 2013

This research developed a smart girdle for adult women in their 20's that has an inserted carbon weaving heater to help with relief from coldness and abdominal disease through the thermal insulation effect. A pocket of powernet fabric was attached to the inside of the girdle for the easy insertion and separation of the heating device, while the heating device was fixed to a mesh material by cotton yarn and was wrapped with elastic lining material to prevent the mechanical devices from being exposed. A set of 3 hooks was attached to the center of the back of the heating device in consideration of convenience and mobility. Whereas the switch was inserted into around the right waistband, and the battery into the inner pocket around the waist, to integrate the heating device with the girdle. The satisfaction and usability of the fabricated smart girdle was verified by having research participants wear it to evaluate the appearance change caused by the device, the inconvenience of wearing/unwearing, mobility, and the satisfactory functionality of the device. As a result, the grand mean was evaluated to be high, with appearance (4.19), mobility (4.17), and functionality (4.51) being higher than 4.00; which indicates that the heat generation function of the smart girdle is effective. It may be said that such collection and analysis of data that reflect users' opinions have value and significance in that they can be grafted onto future research on new technology as well as they contribute to taking a step forward in the rapidly increasing research of smart clothing, with the new-type clothing equipped with new function.

• Fire Science and Engineering
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• v.20 no.4 s.64
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• pp.33-41
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• 2006

Nowadays in Korea, KS F 2271(Testing method for incombustibility of internal finish material and element of buildings) has been using for the evaluation of fire safety performance of sandwich panels. The test method in Japan and in Korea was based on the same way. When the Japanese standard building code was revised in 2000, the test method in the ISO 5660-1 was adopted for the test method for combustion performance of internal finishing materials and elements of buildings. According to this, the revision version of draft substituting the test method in the KS F 2271 for one in the ISO 5660-1(Cone Calorimeter method) is informed in Korea. In this study, combustion properties of sandwich panels were tested using the cone calorimeter method. Ignition time, peak heat release rate and total heat released of four sandwich panels and four core materials (thermal insulation material), which are widely used in Korea, were tested. Test results were analyzed for each specimen. Finally, test results were classified by Japanese standard building code and Canadian NBC revised.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.6
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• pp.426-432
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• 2021

Injection molding is used in many industrial fields such as home appliances, vehicle parts, and electronic device parts because various resins can be molded, leading to mass production of complex shapes. Generally, the empirical prediction method is used to set the initial processing conditions of injection molding. However, this approach requires a lot of cost and its presented solution is not accurate. In this paper, injection molding was simulated through the Moldflow^TM in order to manufacture the spacer for gas insulated switch. Through the simulation, the flow of the resin with respect to the diameter of the inlet was analyzed. It was found that the process was possible at a higher resin temperature as the diameter of the inlet increased. In addition, through thermal analysis during injection of the resin, it was confirmed that a stagnation phenomenon occurred at the insert portion during injection molding, and the temperature of the resin was higher than that of the mold. As in this paper, if the spacer is manufactured by optimizing the injection hole and the temperature of the injection process based on simulation, it is expected that the spacer can be manufactured with high productivity.

• Journal of the Korean Geotechnical Society
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• v.25 no.9
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• pp.19-27
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• 2009

In order to investigate anti-freeze process of precast concrete L-type retaining walls in cold regions, test walls were installed in the campus of Kitami Institute of Technology (KIT, Hokkaido, Japan). The wall consists of following three sections, i) back filled with frost susceptible clay soil, ii) using thermal insulation material, and back filled with frost susceptible soil, iii) back filled with frost-unsusceptible soil. The freezing front distribution and ground temperature within the backfill were observed and deflections of the walls were measured over three freeze-thaw seasons. Some understanding of the mechanisms of the build-up of frost heave pressure was gained, and the effectiveness of replacement method was observed. A simulation was performed to predict the shape of the freezing front in the backfill behind L-type walls with various cross sections. These findings were employed to propose a method for determining the appropriate zone to be replaced with frost unsusceptible backfill material in cold regions.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.425-432
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• 2023

In this study, we aim to develop a carbon-reducing concrete technology by incorporating biochar. Performance evaluation experiments were conducted on concrete mixtures containing biochar with insulating and carbon-capturing properties, which are essential for key infrastructure sectors such as construction and tunnels. Concrete mixtures were designed with different biochar incorporation rates of 0 %, 5 %, 10 %, 15 %, and 20 %, as w ell as w ater-to-binder ratios of 0.25, 0.30, 0.35, and 0.40. To assess the physical properties of each mixture, unit weight, total porosity, and permeability were measured, while mechanical properties were determined through the measurement of concrete compressive and flexural strengths. Key factors for enhancing the insulating effect of carbon-reducing concrete containing biochar were identified through regression analysis, indicating a close correlation among biochar incorporation rate, unit weight, concrete strength, and thermal conductivity. It is anticipated that it can be utilized as an insulating material to enhance thermal performance in northern regions with severe winter climates.

• Journal of the Korea Institute of Building Construction
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• v.9 no.4
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• pp.63-73
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• 2009

Recently, the use of lightweight panels in building structures has been increasing. Of the various lightweight panel types, styrofoam sandwich panels are inexpensive and are excellent in terms of their insulation capacity and their constructability. However, sandwich panels that include organic material are quite vulnerable to fire, and thus can numerous casualties in the event of a fire due to the lack of time to vacate and their emission of poisonous gas. On the other hand, lightweight foamed concrete is excellent, both in terms of its insulation ability and its fire resistance, due to its Inner pores. The properties of lightweight concrete is influenced by foaming agent type. Accordingly, this study investigates the insulation properties by foaming agent type, to evaluate the possibility of using light-weight foamed concrete instead of styrene foam. Our research found thatnon-heating zone temperature of lightweight foamed concrete using AP (Aluminum Powder) and FP (animal protein foaming agent) are lower than that of light-weight foamed concrete using AES (alkyl ether lactic acid ester). Lightweight foamed concrete using AES and FP satisfied fire performance requirements of two hours at a foam ratio 50, 100. Lightweight foamed concrete using AP satisfied fire performance requirements of two hours at AP ratio 0.1, 0.15. The insulation properties were better in closed pore foamed concrete by made AP, FP than with open pore foamed concrete made using AES.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.429-429
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• 2007

For various applications of liquid crystal displays (LCDs), the uniform alignment of liquid crystal (LC) molecules on treated surfaces is significantly important. Generally, a rubbing method has been widely used to align the LC molecules on polyimide (PI) surfaces. Rubbed PI surfaces have suitable characteristics, such as uniform alignment. However, the rubbing method has some drawbacks, such as the generation of electrostatic charges and the creation of contaminating particles. Thus, we strongly recommend a non contact alignment technique for future generations of large high-resolution LCDs. Most recently, the LC aligning capabilities achieved by ultraviolet and ion-beam exposures which are non contact methods, on diamond-like carbon (DLC) inorganic thin film layers have been successfully studied because DLC thin films have a high mechanical hardness, a high electrical resistivity, optical transparency, and chemical inertness. In addition, nitrogen-doped DLC (NDLC) thin films exhibit properties similar to those of the DLC thin films and a higher thermal stability than the DLC thin films because C:N bonding in the NDLC thin filmsis stronger against thermal stress than C:H bonding in the DLC thin films. Our research group has already studied the NDLC thin films by an ion-beam alignment method. The $SiN_x$ thin films deposited by plasma-enhanced chemical vapor deposition are widely used as an insulation layer for a thin film transistor, which has characteristics similar to those of DLC inorganic thin films. Therefore, in this paper, we report on LC alignment effects and pretilt angle generation on a $SiN_x$, thin film treated by ion-beam irradiation for various N ratios