• Solar Energy
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• v.15 no.1
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• pp.13-28
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• 1995

In this study, the history of Korean traditional Ondol was investigated and the latent heat materials and bioceramics were selected to develop the latent heat storage-bioceramics Ondol system based on the Korean traditional Ondol(sensible heat storage type), and the thermal characteristics of Ondol were analyzed experimentally The results could be summarized as follows; 1. Korean traditional Ondol has been originated in "Whaduk" which had been utilized continuously for about $2{\times}10^6$ years from the Old Stone Age to the Bronze Age, and Korean traditional Ondol using in these days has been utilized for about 976 years from the Koryu Dynasty to the Modern Ages. 2. $Na_2SO_4{\cdot}10H_2O(SSD)$ was selected as latent heat material for the latent heat storage Ondol. 3. Ondol unit was filled with the latent heat material of 0.63 kg and the dimension of Ondol unit was $400mm{\times}400mm{\times}27mm(width{\t\imes}depth{\times}height)$. 4. The comfortable surface temperature($23{\sim}29^{\circ}C$) of the latent heat storage Ondol was lasted 5 hours at the room temperature of $16{\sim}18^{\circ}C$, whereas that of sensible heat storage Ondol was lasted only 1.0 hours in the same conditions. 5. For the thermal effect of bioceramics, the Ondol air temperature i.n case of bioceramics treatment on the pannel was higher than that of without bioceramics treatment.

• Journal of the Korea Furniture Society
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• v.20 no.5
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• pp.504-516
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• 2009

Korean traditional architecture has been carried out in the manner that it harmonized surrounding natural environments and never disturbed them in the scale which did not overwhelm the nature, based on the view of architecture predicated on Yin Yang School. The exposed grain of the wood like pillar, hinge and house rafte, the linear expression of the construction material and the formation between the window and door monopolizing the front side presented a harmony with the nature showing the linear structure. Furthermore the ceiling is low due to the sit life style thanks to the ondol (Korean under-floor heating system and the furniture was made in simple manner to utilize the space as large as possible, for the interior was narrow and close, and also the furniture placing in the middle of the room was movably manufactured to improve the room space. Like this Korean traditional furniture was close associated with the low height and simplicity and harmonized with the blank of the wall accordingly, and it characterized linear & planar natural beauty focusing on the simple and refined unique beauty, because it was made in a good harmony with the interior utensils. This study has presented that the organic characteristics of Korean traditional aesthetic of architecture and the natural beauty being intrinsic in traditional furniture have a mutual relation on the basis of not only the visual recognition, also the aesthetic of naturalism made of the natural material, the constructional naivety as a frame method and the linear & planar formative beauty shown in appearance.

• Journal of Climate Change Research
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• v.6 no.2
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• pp.113-119
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• 2015

Emission from the traditional Korean fireplace, or the under-floor heating and cooking device, can contribute significantly to airborne pollutants inventories. This study has systematically measured emissions of airborne pollutants from the fireplace when used different fuels such as firewood, agricultural crop residuals, household wastes. The results show that emission factors of airborne pollutants through the primary combustion of firewood were 3.22 g/kg for TSP, 2.93 g/kg for $PM_{10}$, 2.65 g/kg for $PM_{2.5}$, 174.19 g/kg for CO, 7.77 g/kg for NO, 0.15 g/kg for $SO_2$, 40.53 g/kg for TVOC and 0.03 g/kg for $NH_3$; from burning of agricultural crop residues, 2.85 g/kg for TSP, 1.38 g/kg for $PM_{10}$, 1.14 g/kg for $PM_{2.5}$, 126.47 g/kg for CO, 12.60 g/kg for NO, 0.20 g/kg for $SO_2$, 33.73 g/kg for TVOC and 0.02 g/kg for $NH_3$; and for household wastes, 10.52 g/kg for TSP, 8.52 g/kg for $PM_{10}$, 6.23 g/kg for $PM_{2.5}$, 72.86 g/kg for CO, 11.73 g/kg for NO, 0.20 g/kg for $SO_2$, 47.10 g/kg for TVOC and 0.20 g/kg for $NH_3$.

• International Journal of High-Rise Buildings
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• v.8 no.2
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• pp.101-106
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• 2019

Assessing the energy performance of supertall buildings often does not consider variations in energy consumption due to the change of environmental conditions such as temperature, pressure, and wind speed associated with differing elevations. Some modelers account for these changing conditions by using a conventional temperature lapse rate, but not many studies confirm to the appropriateness of applying it to tall buildings. This paper presents and discusses simulated annual energy consumption results from a 600 m tall skyscraper floor plate located in Dubai, UAE, assessed using ground level weather data, a conventional temperature lapse rate of $6.5^{\circ}C/km$, and more accurate simulated 600 m weather data. A typical office floorplate, with ASHRAE 90.1-2010 standards and systems applied, was evaluated using the EnergyPlus engine through the OpenStudio graphical user interface. The results presented in this paper indicate that by using ground level weather data, energy consumption at the top of the building can be overestimated by upwards of 4%. Furthermore, by only using a lapse rate, heating energy is overestimated by up to 96% due to local weather phenomenon such as temperature inversion, which can only be conveyed using simulated weather data. In addition, sizing and energy consumption of fans, which are dependent both on wind and atmospheric pressure, are not accurately captured using a temperature lapse rate. These results show that that it is important, with the ever increasing construction of supertall buildings, to be able to account for variations in climatic conditions along the height of the building. Adequately modeling these conditions using simulated weather data will help designers and engineers correctly size mechanical systems, potentially decreasing overall building energy consumption, and ensuring that these systems are able to provide the necessary indoor conditions to maintain occupant comfort levels.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.2
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• pp.156-172
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• 2021

Objectives: To investigate the trends of industrial injuries among long-term health care workers in Korea Methods: T7866 injuries were selected from the total industrial injuries approved by the Industrial Accident Compensation Insurance Act(Occupational Safety and Health Act) among long-term health care workers between 2007 and 2016 in Korea. We analyzied the trends of industrial injuries according to work process, occurrence type, and causes. Results: The industrial injuries among long-term health care workers increased since 2012. The mostly occurred area for industrial injuries were low back areas, which is related that the most serious industrial injuries occurred when the one long-term healthcare worker lift manually the recipient, from bed(ondol, Korean floor heating system) to a wheelchair, bed to bath bed, and wheelchair to bath chair. In addition to this, lack of workforce, increased work intensity due to overwork contributed the increasing of occupational injury. Conclusions: This study suggests that the main causes of industrial injuries were Lack of facilities and equipment for small private long-term care institutions, The physical load that goes into lifting the recipient directly, work intensity such as excessive workload and increased work speed. We suggest that the social publicization of long-term care service for the elderly, avoiding ways to lift recipients directly, introducing lifting machines as well as improving working methods, and reducing the workload of caregivers are required.

• Journal of the Korean Society of Clothing and Textiles
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• v.15 no.2 s.38
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• pp.77-87
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• 1991

The purpose of this study were to investigate the bed climate and the physiological responses in sleep on the traditional Korean floor heating system called Ondol. Ondol has been the most widely used heating system in Korea, yet there has been a no systematic studies examined its environmental effects on human body. Experimental room was constructed to match the typical thermal environment of Ondol. (floor surface temperature; $32\~33^{\circ}C$, air temperature; $22.5{\pm}1.0^{\circ}C$, relative humidity; $64.0{\pm}4.0\%$RH, air velocity; 0.25 m/sec.) Three different combinations of bedclothes were chosen for the experiment based on the study results showing that they were the most widely used types in Korea. Type 1 was the combination of a cotton-padded mattress with a cotton-padded Korean style blanket. Type 2 was a cotton-padded mattress with a cotton-guilted Korean style blanket. Type 3 was a cotton-padded matless with a polyacryl blanket. Thermal resistance of each of these combina-tions in the bedclothes was measured using thermal manikin. Two adult female was chosen for the seven hour sleeping experiment which was known to be the average sleeping hours of Korean adult female. The bed climate was measured with the temperature under the mattress, the surface temper-ature of the mattress, and the air temperature and the relative humidity of the space between the mattress and blanket. The skin temperature, rectal temperature of the subjects and the bed climate were measured eight times, one hour before the experiment and every hour during the experiment. The weight loss and the subjective sensation were measured for the each subjects before and after the experiment. The procedure was repeated twice with two subjects and three types of bedclothes, yielding twelve combinations of results. The results were as follows; 1. With the surface temperature of $32\~33^{\circ}C$ of Ondol, air temperature was $22.5{\pm}1.0^{\circ}C$ with $64.0{\pm}4.0\%$ RH. The bed climates were $39.2{\pm}40.8^{\circ}C$ under the mattress, $35.3\~36.2^{\circ}C$ on the mattress, and $26.9\~32.0^{\circ}C$ with $56.0\~71.3\%$ RH between the mattress and the blanket. 2. Mean skim temperature during sleep was 34.2"C with local skin temperature of $34.0\~35.5^{\circ}C$. The skin temperatures of abdomen, thigh, foot were higher than the other parts of the body. 3. The skin temperature of chest, thigh, leg and back varied significantly according to the combinations of bedclothes. With the cotton-padded blanket, the skin temperature was the highest, while with the cotton-guilted blanket showed lowest. 4. Examining the relationship between the mean skin temperature and the local skin temper-ature, the chest temperature showed the highest correlation with the former. Therefore, the chest temperature can be recommended to represent the skin temperature in measuring the bed climate. 5. The subjective bed climates were $39.0\~40.4^{\circ}C$ under the mattress, $35.2\~35.9^{\circ}C$ on the mattress, $29.8\~31.6^{\circ}C$ with $56.8\~68.4\%$ RH between the mattress and blanket. In sum, from this experiment we not only obtained the reliable value of bed climates on Ondol, but also showed that the bed climates and the physiological responses were affected differently according to the materials of bed clothes.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.1
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• pp.94-131
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• 2007

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2004 and 2005 has been done. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD and flow visualization(PIV, PTV and LDV methods) technologies were widely applied for developing facilities and their systems. (2) The research trends of the previous two yews are surveyed as groups of natural convection, forced convection, electronic cooling, heat transfer enhancement, frosting and defrosting, thermal properties, etc. New research topics introduced include natural convection heat transfer enhancement using nanofluid, supercritical cooling performance or oil miscibility of $CO_2$, enthalpy heat exchanger for heat recovery, heat transfer enhancement in a plate heat exchanger using fluid resonance. (3) The literature for the last two years($2004{\sim}2005$) is reviewed in the areas of heat pump, ice and water storage, cycle analysis and reused energy including geothermal, solar and unused energy). The research on cycle analysis and experiments for $CO_2$ was extensively carried out to replace the Ozone depleting and global warming refrigerants such as HFC and HCFC refrigerants. From the year of 2005, the Gas Engine Heat Pump(GHP) has been paid attention from the viewpoint of the gas cooling application. The heat pipe was focused on the performance improvement by the parametric analysis and the heat recovery applications. The storage systems were studied on the performance enhancement of the storage tank and cost analysis for heating and cooling applications. In the area of unused energy, the hybrid systems were extensively introduced and the life cycle cost analysis(LCCA) for the unused energy systems was also intensively carried out. (4) Recent studies of various refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and of alternative refrigerants including carbon dioxide. Efficiency of various compressors and expansion devices are also dealt with for better modeling and, in particular, performance improvement. Thermoelectric module and cooling systems are analyzed theoretically and experimentally. (5) According to the review of recent studies on ventilation systems, an appropriate ventilation systems including machenical and natural are required to satisfied the level of IAQ. Also, an recent studies on air-conditioning and absorption refrigeration systems, it has mainly focused on distribution and dehumidification of indoor air to improve the performance were carried out. (6) Based on a review of recent studies on indoor environment and building service systems, it is noticed that research issues have mainly focused on optimal thermal comfort, improvement of indoor air Quality and many innovative systems such as air-barrier type perimeter-less system with UFAC, radiant floor heating and cooling system and etc. New approaches are highlighted for improving indoor environmental condition as well as minimizing energy consumption, various activities of building control and operation strategy and energy performance analysis for economic evaluation.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.211-220
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• 2014

This study reports the formation characteristics of tar, ash and clinker due to a wood pellet grade and the performance analysis of wood pellet boiler in terms of the moisture contents change of the wood pellet. Tar was accumulated on the heating surface according to combustion of wood pellet, the ash was yielded on the floor of combustion chamber in a wood pellet boiler and the clinker was solidified at the burner due to combustion of the 3rd grade wood pellet. Especially, the moisture contents is important factor to define the grade. Wood of logging residues has a non-uniform moisture contents after the field process, yields of tar, ash and clinker are increased in case of combustion due to the high ash contents. For these reasons, emission of harmful compounds in the exhaust gas, decrease of boiler efficiency and the system operating errors are observed. In the performance analysis of wood pellet boiler in terms of the moisture contents change of the 1st grade wood pellet, the boiler efficiency was reduced by 27.08% with 6.6% moisture contents increase. The optimum moisture contents of wood pellet is needed to improve the boiler performance and efficiency.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.2
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• pp.114-119
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• 2013

The present study tested 5 concrete mixes to develop reliable mixing proportions for the sustainable alkali-activated(AA) foamed concrete as a thermal insulation material for the floor heating system of buildings. The AA binder used was composed of 73.5% ground granulated blast-furnace slag, 15% fly ash, 5% calcium hydroxide, and 6.5% sodium silicate. As a main variable, the unit binder content varied from $325kg/m^3$ to $425kg/m^3$ at a space of $25kg/m^3$. The test results revealed that AA foamed concrete has considerable potential for practical applications when the unit binder content is close to $375kg/m^3$, which achieves the minimum quality requirements specified in KS F 4039 and ensures economic efficiency. In addition, lifecycle assessment demonstrated the reduction in the environmental impact profiles of all specimens relative to typical ordinary portland cement foamed concrete as follows: 99% for photochemical oxidation potential, 87~89% for global warming potential, 78~82% for abiotic depletion, and 70~75% for both acidification potential and human toxicity.

• Journal of Energy Engineering
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• v.8 no.2
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• pp.224-232
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• 1999

Latent heat storage system using micro-encapsuled phase change material is effective method for floor heating of house and building. The temperature profile in capsule block and flow rate of hot water are important parameters for the development of heat storage system. In the present study, a mathematical model based on 3-D, non-steady state, Navier-Stokes equations, scalar conservation equations and turbulence model ($\kappa$-$\varepsilon$), is used to predict the temperature profiles in capsule and the velocity vectors in hot water pipe. The multi-block grids and fine grids embedding are used to join the circle in hot water pipe and square in capsule block. The phase change process of the capsule is quite complex not only because the size of phase change material is very small, but also because phase change material is mixed with the cement to form thermal storage block. In calculation, it's assumed that the phenomena of phase change is limited only the thermal properties of phase change material and the change of boundary is not happened in capsule. The purpose of this study is to calculate the temperature profiles in capsule block and velocity vectors in hot water pipe using the numerical calculation. Two kinds of thermal boundary condition were considered, the first (case 1) is the adiabatic condition for the both outside surfaces of the wall, the second (case 2) is the case in which one surface is natural convection with atmosphere and another surface is adaibatic. Calculation results are shown that the temperature profile in capsule block for case 1 is higher than that for case 2 due to less heat loss in adaibatic surface. Specially, in the domain of near Y=0, the difference of temperature is greater in case 1 than in case 2. The detailed experimental data of capsule block on the temperature profile and the thermal properties such as specific heat and coefficient of heat transfer with the various temperature are required to predict more exact phenomena of heat transfer.