• Journal of Korean Institute of Architectural Sustainable Environment and Building Systems
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• v.12 no.6
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• pp.567-578
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• 2018

The purpose of this study was to evaluate condensation prevention for condensation vulnerable areas around built-in furniture of apartment buildings by applying auxiliary heating device. Recently, the condensation and mold problems of apartment buildings has been growing due to high insulation and high air-tightness performance for energy saving. Condensation at built-in furniture were generally found in winter at the of furniture's back panels, adjacent surfaces of wall, floor and ceiling. These problems are related to the weather conditions and indoor room conditions in winter. To solve these problems, auxiliary heating device was developed and could be installed. The aim of paper is to analyze the thermal environment around the built-in furniture which were applied and not applied auxiliary heating device in winter. In results, it was possible to increase the surface temperature of vulnerable areas around built-in furniture by applying auxiliary heating device, and to minimize condensation problems by using the minimum device.

• Journal of the Korean housing association
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• v.15 no.1
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• pp.33-40
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• 2004

Considering the present development situation of rental apartment since 1982, the supply of rental housing for low-income dwellers has contributed a amount of quantities, but has been deficient qualities in housing policy. To propose the device of remodeling for low-income dwellers in deteriorated apartment, this study investigated the energy consumption of central heating system and the characteristics of maintenance cost in permanent rental apartment. The results of evaluation of alternative heating systems by Life Cycle Costing in permanent rental apartment were as follows; From Life Cycle 15∼20 years by Present Worth Method, the economic heating system of remodeling is central heating system (heat source: B-C oil), unit heating system(natural gas), central heating system(natural gas) in order.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.4
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• pp.23-32
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• 2019

Increasing crop production with the same amount of resources is essential for enhancing the economy in agriculture. The first prerequisite is to understand relationships between the resources. The concept of WEF (Water-Energy-Food) nexus analysis was first introduced in 2011, which helps to interpret inter-linkages among the resources and stakeholders. The objective of this study was to analyze energy-water nexus in greenhouse cultivation by estimating reference evapotranspiration and heating load. For the estimation, this study used the physical model to simulate the inside temperature of the agricultural greenhouse using heating, solar radiation, ventilated and transferred heat losses as input variables. For estimating reference evapotranspiration and heating load, Penman-Monteith equation and seasonal heating load equation with HDH (Heating Degree-Hour) was applied. For calibration and validation of simulated inside temperature, used were hourly data observed from 2011 to 2012 in multi-span greenhouse. Results of the simulation were evaluated using $R^2$, MAE and RMSE, which showed 0.75, 2.22, 3.08 for calibration and 0.71, 2.39, 3.35 for validation respectively. When minimum setting temperature was $12^{\circ}C$ from 2013 to 2017, mean values of evapotranspiration and heating load were 687 mm/year and 2,147 GJ/year. For $18^{\circ}C$, Mean values of evapotranspiration and heating load were 707 mm/year and 5,616 GJ/year. From the estimation, the relationship between water and heat energy was estimated as 1.0~2.6 GJ/ton. Though additional calibrations with different types of greenhouses are necessary, the results of this study imply that they are applicable when evaluating resource relationship in the greenhouse cultivation complex.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.121-126
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• 2003

This paper is concerns with the development of the formulae to predict deformation of curved plate due to line heating. For this purpose thermal elasto-plastic analysis has been carried out for both flat and curved plate models with varying parameters which affect the result of line heating. based on the results of numerical analysis, the formulae for predicting angular deformation has been derived through the regression analysis, which. It has been seen that the present model well agrees with the numerical analysis results and can reflect the curvature effect of plate to be heated. This paper ends with some comments on this formulae.

• Proceedings of the Korean Geotechical Society Conference
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• 1993.10b
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• pp.213-218
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• 1993

The paper deals with problems connected with heating and ventilation of underground premises for public use. Some properties of rock and special problems connected with designing ventilation systems for underground spaces are first briefly discussed. The rest of the paper deals with design of ventilation and heating systems. The conclusion is that there are no large problems with heating and ventiliation of underground premises, but there are still problems connected with for instance thermal properties of rock when water flows in the cracks. An optimum design demands better knowledge of these properties.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.214-220
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• 2011

This paper studies about the assessment of thermal performance between wet ondol system and electric ondol system. Electrical ondol systems shows faster warm-up time, higher floor surface temperature distribution and lower power consumption than wet ondol system. However, if we provide heat regularly wet ondol system which has more heat capacity shows greater thermal storage than electric ondol system. Therefore, we could conclude that wet ondol system which keeps temperature regularly by the thermal storage show better energy-efficiency in case of using the central heating and district heating system. However, Electrical ondol system shows better efficiency in case of using the space during short time or individual heating systems which needs to heat quickly. The Experiment says that electric ondol system has more benefits on timing to reach the set temperature and energy-efficiency than wet ondol system.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2989-2994
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• 2008

The shopping center in underground passage for efficient space utilization is increased in urban area. This study describes operation characteristics of HVAC systems with ventilation and individual heating and cooling unit for shopping center in underground passage. In order to compare energy saving, thermal environment and installation space, etc., an integrated simulator with heat production and distribution system was designed and constructed. Energy delivery efficiency is improved over 20%, and energy saving of the hybrid system is calculated as over 30% compared to conventional all air type in the case of heating. And also the results showed that humidity decreased about $5{\sim}6%$, also characteristics of thermal control is improved over 34%.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1577-1586
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• 2017

The Proportional-Integral-Derivative (PID) controller is still the most widespread control strategy in the industry. PID controllers have gained popularity due to their simplicity, better control performance and excellent robustness to uncertainties. This paper presents the optimal tuning of a PID controller for domestic induction heating systems with a series resonant inverter for controlling the induction heating power. The objective is to design a stable and superior control system by tuning the PID controller with a derivative filter (PIDF) through Fuzzy logic. The paper also compares the performance of the Fuzzy PIDF controller with that of a Ziegler-Nichols PID controller and a fine-tuned PID controller with a derivative filter. The system modeling and controllers are simulated in MATLAB/SIMULINK. The results obtained show the effectiveness and superiority of the proposed Fuzzy PID controller with a derivative filter.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.915-920
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• 2006

Recently available heat pump system by using air heat-source is not efficient. Because the mean temperature of korean winter season is low, economy of air heat-source heat pump descend, and COP is below 3.0. This paper was practiced the simulation on evaluation criteria for heat pump heating and cooling systems to resident building. As a result, heating and cooling composition heat pump system apply to the building needed to be provided heat source for 24 hours.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.4
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• pp.297-302
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• 2011

According to the standards for district heating substation established by Korea District Heating Corporation, water heating supply systems at over 150 Mcal/h capacity must employ the 2-stage heat exchanger that improves the system efficiency by reusing the heat included in the return water of district heating system already used for space heating. In this paper, the operating characteristics of the system in accordance with the load distribution of two heat exchangers for pre-heating and re-heating cold city water are investigated. The results including mass flow rate, return temperature etc. help to manage district heating system economically.