• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.1 s.244
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• pp.57-66
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• 2006

The experimental and the numerical study was performed on the comparison of thermal comfort(TC) and indoor air quality(IAQ) in the lecture room for cooling loads when the operating conditions are changed. PMV value and $CO_2$ concentration of the lecture room were measured and compared with the numerical results. The numerical results showed a good agreement with the experimental one and then the numerical tool was used to analyze thermal comfort and IAQ for a couple of operating conditions. As a result it was found that the increment of the discharge angle of system air-conditioner makes TC uniformity worse, but rarely affects IAQ. Also TC and IAQ were hardly affected by the variation of the discharge airflow. Finally it turned out that TC is merely affected by the increment of the ventilation airflow, but the average $CO_2$ concentration can be satisfied with Japanese IAQ standards of classrooms when the ventilation airflow is more than $800m^3/h$ in this study.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.135-140
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• 2005

Installation of ceiling type unit is achieved by one of efforts for agreeable classroom environment embodiment along with economic growth. But research about changing the position of ceiling type unit is lacking in present. Therefore, this thesis is to study the thermal environment of 5 different position cases of ceiling type, namely Case A, B, C, D, E. Here, Case C is the case that has the position of ceiling type center of the classroom and the other 4 alternatives are 0.7 m away from the Case C according to x and z axis. In this thesis temperature distributions, air current distribution, heat amenities such as PMV of occupants are analyzed as the environmental factors. Through these factors, Case C and Case D are the better position alternatives than the alternatives of Case A, Case B and Case E because the latter cases the air current reaches directly to indoor occupants so that occupants feel chilly. This thesis has a conclusion under the condition of only one inlet air temperature and seat arrangement. But afterwards more inlet air condition and seat arrangement must be considered.

• KIEAE Journal
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• v.7 no.5
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• pp.87-92
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• 2007

As expansion of balconies at apartments has been legalized, the major function of the balconies as a thermal buffer zone is disappearing. This weakens the ability of window to insulate heat and multiplies surface condensation. Thus more and more residents require solutions to increasing surface condensation and aggravation in thermal comfort. This study intends to provide basic data by evaluating performance of triple layered Low-E windows, triple layered clear windows, double layered Low-E windows and double layered clear window used for expanded balconies and marketed within the country in terms of surface condensation and thermal environment through simulation. Results revealed that no surface condensation occurred at double layered Low-E windows and triple layered Low-E windows. Surface condensation took place at double layered clear windows and triple layered clear windows at a relative humidity of 60%. Thermal environment analysis suggested that double layered clear windows showed the most time falling into the range of comfort at $23^{\circ}C$. The figure were $22^{\circ}C$ for triple layered clear windows, $22^{\circ}C$ for double layered Low-E windows and $21^{\circ}C$ for triple layered Low-E windows.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.8
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• pp.683-689
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• 2003

The thermal comfort of an indoor swimming pool is different from that of general indoor space because of the characteristics of large space and the wear conditions of swimmers. Dew condensation by humid air not only makes mold on the floor, wall and roof but also decreases the durability of buildings by penetrating into their structures. In this study, the characteristics of the flow field, the temperature field and the humidity distribution in an indoor swimming pool have been examined by the numerical method to estimate the level of thermal comfort and the generation rate of dew condensation. The results showed that the dew condensation regions were spread widely at the eastern parts of the swimming pool due to the insufficient air flow rate with low velocity and temperature. To prevent the generation of dew condensation in a region, a sufficient warm air flow rate should be supplied to make an air mixing. The values of PMV at horizontal plane of 1.5 m height have the range of -1.0∼1.2, which means the suitable level for swimmers.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.3
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• pp.153-165
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• 2023

The purpose of this study is to propose effective scenarios for green areas in apartment complexes that can improve the connection between green spaces considering wind flow, thermal comfort, and mitigation of the urban heat island effect. The study site was an apartment complex in Godeok-dong, Gangdong-gu, Seoul, Korea. The site selection was based on comparing temperatures and discomfort index data collected from June to August 2020. Initially, the thermal and wind environment of the current site was analyzed. Based on the findings, three scenarios were proposed, taking into account both green patches and corridor elements: Scenario 1 (green patch), Scenario 2 (green corridor), and Scenario 3 (green patch & corridor). Subsequently, each scenario's wind speed, wind flow, and thermal comfort were analyzed using ENVI-met to compare their effectiveness in mitigating the urban heat island effect. The study results demonstrated that green patches contributed to increased wind speed and improved wind flow, leading to a reduction of 31..20% in the predicted mean vote (PMV) and 68.59% in the predicted percentage of dissatisfied (PET). On the other hand, green corridors facilitated the connection of wind paths and further increased wind speed compared to green patches. They proved to be more effective than green patches in mitigating the urban heat island, resulting in a reduction of 92.47% in PMV and 90.14% in PET. The combination of green patches and green corridors demonstrated the greatest increase in wind speed and strong connectivity within the apartment complex, resulting in a reduction of 95.75% in PMV and 95.35% in PET. However, patches in narrow areas were found to be more effective in improving thermal comfort than green corridors. Therefore, to effectively mitigate the urban heat island effect, enhancing green areas by incorporating green corridors in conjunction with green patches is recommended. This study can serve as fundamental data for planning green areas to mitigate future urban heat island effects in apartment complexes. Additionally, it can be considered a method to improve urban resilience in response to the challenges posed by the urban heat island effect.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.115-123
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• 2010

Cool-down performance after soaking is important because it affects passenger's thermal comfort. The cooling capacity of HVAC system determines initial cool down performance in most cases, the performance is also affected by location, and shape of panel vent, indoor seat arrangement. Therefore, optimal indoor designs are required in developing a new car. In this paper, initial cool down performance is predicted by CFD(computational fluid dynamics) analysis. Experimental time-averaging temperature data are used as inlet boundary condition. For more reliable analysis, real vehicle model and human FE model are used in grid generation procedure. Thermal and aerodynamic characteristics on re-circulation cool vent mode are investigated using CFX 12.0. Thermal comfort represented by PMV(predicted mean vote) is evaluated using acquired numerical data. Temperature and velocity fields show that flow in passenger's compartment after soaking is considerably unstable at the view point of thermodynamics. Volume-averaged temperature is decreased exponentially during overall cool down process. However, temperature monitored at different 16 spots in CFX-Solver shows local variation in head, chest, knee, foot. The cooling speed at the head and chest nearby panel vent are relatively faster than at the knee and foot. Horizontal temperature contour shows asymmetric distribution because of the location of exhaust vent. By evaluating the passenger's thermal comfort, slowest cooling region is found at the driver's seat.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.979-988
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• 2014

Recently, the interest in the thermal comfort is ever increasing as the time people stay in the automobile is gradually increasing. So far, however, the cooling performance of the HVAC(heating and ventilation air conditioning) system is evaluated by thermal environment criteria such as indoor air velocity and temperature, not by a thermal comfort index. Furthermore, the precise criteria has not been established yet when the thermal comfort for the automobile is evaluated using numerical analysis. In this study, the numerical analysis of automobile indoor thermal comfort according to various parameters such as HVAC operating mode, airflow, passenger boarding conditions is performed during the HVAC system's initial operating time(20 minutes). The solar ray tracing model and S2S radiation model are used and validated to simulate an external heat source. Based on this study, an evaluation model which can predict the thermal comfort index for the combination of the above parameters is presented.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.5
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• pp.12-20
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• 2010

The purpose of this study is to evaluate human thermal comfort by spatial structure and to explore solutions to improve the thermal environment of a small urban space. The study site was Korea University campus. Thermal conditions were measured to evaluate the quality of the thermal environment in each type of space within the study site. Micrometeorology measurements, analysis of space characteristics for using fish-eye lens photography, and thermal comfort modeling through the use of collected meteorological data, such as temperature and humidity, were performed. Results showed that the level of thermal comfort for humans differs depending on the types of space within the study site. Thermal comfort is better in open spaces than enclosed in the aspect of radiative mean temperature, Predicted Mean Vote(PMV), and Physiologically Equivalent Temperature(PET). This fact is probably due to shadows or buildings or trees that may block solar radiation. Thus, it is necessary to consider the spatial arrangements of buildings and trees to enhance openness and ventilation in the space. Paving materials and exterior building materials should also be selected to lower the radiant temperature. Given these results, a quantitative evaluation on human thermal comfort could propose a way to plan user comfortable small urban spaces. Study methods used and results provided in the study can promote a better way for urban space planning direction to improve environmental quality.

• Korean Journal of Environmental Agriculture
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• v.37 no.4
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• pp.268-276
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• 2018

BACKGROUND: In the month of January 2018, fine dust alerts and warnings were issued 36 times for $PM_{10}$ and 81 times for PM2.5. Air quality is becoming a serious issue nation-wide. Although interest in air-purifying plants is growing due to the controversy over the risk of chemical substances of regular air-purifying solutions, industrial spread of the plants has been limited due to their efficiency in air-conditioning perspective. METHODS AND RESULTS: This study aims to propose a vegetation-based bio-filter system that can assure total indoor air volume for the efficient application of air-purifying plants. In order to evaluate the quantitative performance of the system, time-series analysis was conducted on air-conditioning performance, indoor air quality, and comfort index improvement effects in a lecture room-style laboratory with 16 persons present in the room. The system provided 4.24 ACH ventilation rate and reduced indoor temperature by $1.6^{\circ}C$ and black bulb temperature by $1.0^{\circ}C$. Relative humidity increased by 24.4% and deteriorated comfort index. However, this seemed to be offset by turbulent flow created from the operation of air blowers. While $PM_{10}$ was reduced by 39.5% to $22.11{\mu}g/m^3$, $CO_2$ increased up to 1,329ppm. It is interpreted that released $CO_2$ could not be processed because light compensation point was not reached. As for the indoor comfort index, PMV was reduced by 83.6 % and PPD was reduced by 47.0% on average, indicating that indoor space in a comfort range could be created by operating vegetation-based bio-filters. CONCLUSION: The study confirmed that the vegetation-based bio-filter system is effective in lowering indoor temperature and $PM_{10}$ and has positive effects on creating comfortable indoor space in terms of PMV and PPD.