• Journal of the Korean Institute of Gas
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• v.25 no.1
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• pp.7-13
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• 2021

The re-liquefaction drum is a product that installed spray nozzles at the top to directly spray overcooled LNG into evaporative gas and installed demistors to facilitate gas separation, which was developed to increase the re-liquidity efficiency of small scale re-liquefaction facilities. In the hydrostatic test of the drum, no leakage occurred even at a pressure of 1.5 times the design pressure, but during the BOR(Boil Off Rate) test, the bolt loosening occurred due to contraction and expansion by temperature change. For the continued use of the product, insulation construction on flange connections was developed to enable detachment and attachment, and the comparison of heat load with existing insulation confirmed that it was very small compared to the inlet flow rate in the drum.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.16-19
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• 2009

Recently, for improvement of the magnetic field of high temperature superconductor (HTS) apparatus, many studies investigating on operating in the range of $20{\sim}65K$ with liquid helium or the conducting method using cryocooler is actively reviewed. Also, the cooling method using solid nitrogen as cryogen is being suggested. Since the nitrogen has very large specific heat in solid state, it is expected that it can enable long time operation without a continuous supply of cooling energy. However, there is still insufficient data on the characteristics of solid nitrogen such as thermodynamic properties and liquid-solid phase change. Especially, there was almost no study done on the electrical insulation properties of solid nitrogen so far. In this study, solid nitrogen to find the electrical characteristics was made by using cryocooler and cryostat, and investigated the flashover discharge and breakdown. The results of this study will be useful as a basic data for electrical insulation design of the HTS system using solid nitrogen as cryogen.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.138-147
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• 2007

Recently, framed structure is increasingly being used as apartment structure due to the advantages during remodeling. Therefore, the use of lightweight panel as separating wall is increasing. To construct lightweight panel structures with sound insulation performance appropriate to the conditions of each field, measurement of sound reduction index(SRI) through panel structures should be performed. In this study, measurement of SRI through 46 kinds of panel structures was performed in the condition of various factors such as surface density, air space and absorber. The result showed that SRI of panel structures was generally higher by increasing of surface density. In the case of double panel with no absorber, SRI at below critical frequency was gradually increased according to rise of air space. Double panel with absorber make remarkable improvement in SRI at low frequency, but there is a little difference compared with SRI of double panel with no absorber over critical frequency.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.2
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• pp.13-18
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• 2013

The authors designed a high temperature superconductor (HTS) racetrack coil for a 10 MW class superconducting synchronous wind turbine generator. The designed HTS racetrack coil was analyzed by an electromagnetic finite element method (FEM) to determine the magnetic field distribution, inductance, stress, etc. This paper describes the stress analysis and structure design result of the HTS racetrack coil for 10 MW class superconducting synchronous wind turbine generators, considering orthotropic material properties, a large magnetic field, and the resulting Lorentz force effect. Insulated HTS racetrack coils and no-insulation HTS racetrack coils were also considered. According to the results of the stress analysis, the no-insulation HTS racetrack coil results were better than the insulated HTS racetrack coil results.

• Progress in Superconductivity and Cryogenics
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• v.21 no.1
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• pp.36-39
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• 2019

This paper presents an analytic method to calculate energy conversion between electromagnetically coupled high-temperature superconducting and copper coils. The energy transfer from one coil to the other is commonly observed during quench of a no-insulation (NI) high temperature superconductor (HTS) magnet. Proper understanding of this phenomenon is particularly important to protect an NI HTS magnet, especially to avoid any potential mechanical damages. In this paper, analytic equations are obtained to estimate the energy transfer between the NI and copper coils. The well-known lumped-parameter circuit model is adopted provided that key parameters of the coils are given.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.157-167
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• 1994

This study was conducted to analyze the relationship between the types of fiber and its content and the levels of airborne fiber concentrations at eight parking lots where sprayed insulation material was found on the walls and ceilings. Also this study was designed to find the relationship between the levels of airborne fiber concentrations and such variables as air current, humidity, total exhaust volume, surface condition of insulation material and building age. The results obtained were as follows : 1. No significant correlation was found between the levels of airborne tiber concentration and the building age, air current, humidity, total exhaust volume, space and the number of traffics. 2. A significant correlation was found between the levels of airborne fiber concentration and the MMMF content of the insulation material(r=0.7594). However, no significant correlation was found between the levels of airborne fiber concentration and total fiber content of insulation material. 3. The differences of the airborne fiber concentrations among Cateogory 1, 2 and 3 classified by the degrees of surface insulation material maintenance were very significant. 4. Two bulk samples contained 30% crodicolite and 1% anthophylite. The MMMFs, in all parking lots, included mineral wool, cellulose fiber, trace cellulose fiber, trace tiber glass and vermiculite. 5. The mean value and the range of airborne fiber concentrations at 8 parking lots were $0.0239{\pm}0.0095f/cc$ and 0.0054-0.0447 f/cc, respectively. The fiber concentrations of 35 out of 38 samples(92%) were over 0.01 f/cc which is the Environment Administration's recommended asbestos level for the underground space. This study suggests that most of building insulation materials used in Korea, contain MMMF and sometimes asbestos. Currently, MMMF pollution levels may exceed the Environment Administration's recommended level for underground space. It has been found that airborne fiber concentrations increased significantly with MMMF content and with the maintenance condition of surface material. Therefore, it is recommended that a proper management technique should be developed and immediately implemented since the conditions of surface material will be gradually deteriorated due to building age and usage. Since health hazards of the MMMF, similar to those of asbestos, are being gradually acknowledged, a proper management technique which is applicable to control total airborne fiber concentrations, both asbestos and MMMF, be developed and an acceptable indoor air standard be promulgated as early as possible.

• Journal of Korean Elementary Science Education
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• v.39 no.3
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• pp.433-448
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• 2020

In this study, the tasks of thermal equilibrium and heat insulation concept were divided into scientific and everyday contexts to analyzed the level of familiarity, feeling of knowing, state curiosity, and state anxiety that students feel in task contexts and their relationship. The subjects of this study were One hundred nine students in sixth grade of elementary schools located in metropolitan cities. The results of this study were as follows. First, there was no difference in the level of feeling of knowing, state curiosity, and state anxiety in the task of scientific and everyday contexts. In the case of familiarity, there was no consistent tendency in the concept of thermal equilibrium and heat insulation. And the group who recognized the task context familiarly had higher feeling of knowing and lower state anxiety than the group who recognized the task context unfamiliarly. Second, familiarity and feeling of knowing showed high positive correlation, state anxiety and familiarity showed negative correlation, and state anxiety and feeling of knowing had also negative correlation. In addition, familiarity had a negative effect on state anxiety, and FOK had a positive effect on state curiosity and a negative effect on state anxiety. There was no significant moderating effect of the task context. Third, in case of state curiosity, the group perceived the knowledge gap was very small had the highest state curiosity, and the group perceived the knowledge gap was very large had the lowest state curiosity. In case of state anxiety, the less the knowledge gap was perceived, the lower the anxiety was triggered. This study broadens our understanding of the learning process and provides implications for effective instruction strategies for students' cognitive and emotional states.

• Journal of the Korean Institute of Educational Facilities
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• v.2 no.2
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• pp.17-25
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• 1995

Because of energy crisis and environment pollution, we have become more conscious of the need to conserve heat in buildings. In response to this need. new requirements have been developed for insulation and other matters relating to energy consumption. Among others, more promising is to use the energy that is all around us in the dynamic forces of nature:the wind, tides, waves, rivers, geothermal hot spots, and the sun. The problem is that we have not been forced to find the technological means to convert these natural energies into usable forms because it has been too easy simply to dig or pump our energy out of the ground. Now, the problem is not a shortage of energy itself, but a shortage of technology for converting the energy that lies aoo around us into usable forms. Energy-conversion technology is the real issue, and solar energy is one of the brightest and most promising frontiers in energy conversion. All buildings are wrapped in a skin. Generally skins protect the person in stay from rain, wind, dust, noise, cold, hot etc.. However, there are some skins that provide energy from given environment into the building. Out of aoo, transparent insulation material is one of these materials that most effectively satisfies this kind of envelope function. Since, there are no research on transparent insulation in Korea, it has been studied very actively in Europe and in America. Thus, in this thesis, we will theoratically study and analyze how the heat flows through a trans arrent insulated opaque wall of a school building in Korea. It will be an important information for the effective using guidelines of transparent insulation materials in Korea.

• KIEAE Journal
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• v.14 no.3
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• pp.87-95
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• 2014

The purpose of this study is to evaluate the correlation coefficients between the airtightness and sound insulation performance of Han-style windows in New Han-ok. To achieve these goals, field measurements were accomplished in 18 bedrooms of 16 Han-oks in which actual residents were living, and then lab measurements were proceeded in the reverberation lab for evaluating the sound insulation performance. Followings are results. The results of the correlation analysis between the airtightness(Air change per hour at 50 Pa, ACH50) and sound insulation performance(Sound reduction index, Rw) in bedrooms of actual Han-oks, it was found that there were no significant correlation between two evaluating values. On the other hand, it was analyzed that the correlation coefficients of total 24 structures(double casement windows, single casement window, casement and sliding windows, single sliding window, 6 types per each structure) were located on 0.6757 exponentially and 0.4154 lineary in the lab evaluating conditions. But, The results of evaluating 4 structure classificatorily, it was found that there were high correlation coefficients(0.8665~0.9273 at ACH50, 0.8414~0.9346 at Rw). These results were signified that the correlation coefficients were changed according to the each structure and case by case analysis were necessary at the same time.

• Journal of the Korea Safety Management & Science
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• v.14 no.2
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• pp.65-70
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• 2012

This study was performed to test the combustive properties of the pipe insulation materials which are mainly used in the industries and buildings. Fire characteristic test of pipe insulation film according to the KS F ISO 5660-1 was performed. The experimental materials commonly used in the pipe insulation were used four kinds of films. Two kinds of 4 types of products that have the flame retardant performance and the other two types of them have no flame retardant performance. They were selected for fire characteristic test. The result of finding 25kW/$m^2$ radiation from the ignition was that flame retardant products were 140sec and the other one were 69sec in average of heat release rate(HRR). The result of flame retardant products in the 50kW/$m^2$ was 34sec and the other one were 15sec in average of HRR. However, the HRR of flame retardant products was much higher than the other one. Flame propagation test was conducted according to the KOFEIS 1001. The result of flame retardant products was that flame retardant products had a hold without fire spread after firing them. But the other one were completely fired after firing them. Therefore, I want to recommend that flame retardant products need to be used by the regulation to prevent or decrease a fire spread.