Sunkuk Kim

A Health Performance Evaluation Model of Apartment Building Indoor Air Quality

As illnesses attributable to deteriorating indoor air quality (IAQ) increase, people are becoming more aware of the health effects of IAQ because most people in Korea spend >80% of their time indoors. Notably, the IAQ of apartment buildings accounts for a massive share of the construction volume in Korea, which is a highly critical issue. Evaluation of health effects of IAQ would influence not only the statutory criteria for air quality improvement but could also contribute to the development of building design standards. In addition, such evaluation supports quantification efforts for the selection of wholesome construction materials and techniques. Evaluation of the health effects of IAQ is a complex exercise that would require comprehensive consideration of factors such as the concentrations and occurrences of various known, harmful indoor pollutants, ventilation performance in a building and temperature/humidity. Evaluation involves not only quantitative assessment of pollutants but also evaluation of IAQ based on human perception. The aim of this study was to develop a model to evaluate IAQ in quantitative terms based on health impact, but with an emphasis on apartment buildings.

Cost Comparative Analysis of a New Green Building Code for Residential Project Development

AbstractThis paper presents a comprehensive cost comparative analysis for the impact of the new Green Building Code on residential project development from project management perspectives. As the demand for new residential housing is gradually increasing from the long recession, residential project management is vital for project owners making decisions concerning the investment of new green building features, such as energy-efficient appliances, equipment, and lighting. The analysis results show that the incorporation of such green systems causes the construction costs to increase by 10.77% more than the traditional building, whereas the amount of working days only increases by two days. The findings can be used as a guide for project owners to make decisions concerning their monetary initial investments while benefiting from energy cost savings over the life cycle of the building.

An Analysis of the CO2 Reduction Effect of a Column-Beam Structure Using Composite Precast Concrete Members

Over the past 30 years, Korea has adopted structural frames with bearings for apartment buildings. The unit planning flexibility of such a structural system is inadequate, when compared to the column-beam system. The system would allow renovation easily and would provide various other legal benefits to constructors in Korea. For this reason, a column-beam system, named by green frame (GF), implemented with composite precast concrete (PC) members was previously developed. However, since the scheme would require a performance improvement to increase its economic effects and constructability, a further improved system has been developed. In the case of structural construction, it is a construction process that emits the most CO2. Along with the constructability and economic feasibility of a construction system, a reduction in CO2 is also critical. The purpose of this paper was to analyze the CO2-reduction effect of the improved system constructed with enhanced composite PC members. The improved system would greatly contribute to CO2 reduction with an average of 25.0% as compared with the bearing wall structure; and 2.8% compared to the existing GF.

An Enhanced TACT Technique for Finish Work of High-rise Residential Buildings

Execution of the finish work for high-rise residential construction occurs when a mixture of work progresses simultaneously at each floor or sector and is carried on by highly-specialized subcontractor teams. Therefore, the finish work plan requires an effective scheduling method that interfaces between the work and the teams. In order to address these issues, the TACT technique is utilized in Korea. This technique is based on Line-of-Balance and Lean construction. However, according to recent case studies, finish work using TACT technique was frequently delayed with cost overruns because the work was performed without a detailed schedule control plan outlining the relationship between architecture and mechanical, electrical, and plumbing work. This paper describes the enhanced-TACT technique which provides a detailed work flow chart and TACT work template. With improved TACT technique, this paper will contribute to improved cash flow and reduced cycle time and provide quality improvement through work continuity.

3-Aminopropyltriethoxysilane Effect on Thermal and Mechanical Properties of Multi-walled Carbon Nanotubes Reinforced Epoxy Composites

Diglycidyl ether of bisphenol A nanocomposites with unmodified multi-walled carbon nanotubes (u-MWCNTs) and silanized multi-walled carbon nanotubes (si-MWCNTs) were prepared by cast molding method. The effects of 3-aminopropyltriethoxysilane functionalization of MWCNTs on the thermal and mechanical properties of the nanocomposites were examined. The nanocomposites were characterized by thermogravimetric analysis, dynamic mechanical thermal analysis, and flexural testing. The results showed that epoxy composites based on si-MWCNTs showed better thermal stability, glass transition temperature, and flexural properties than the composites based on u-MWCNTs. These results prove the effect of silane functionalization on the interfacial adhesion between epoxy and MWCNTs. This was further confirmed by morphology study of fractured surfaces of nanocomposites by scanning electron microscopy.

Thermal and Mechanical Properties of Epoxy/Carbon Fiber Composites Reinforced with Multi-walled Carbon Nanotubes

Multi-scale hybrid composite laminates of epoxy/carbon fiber (CF) reinforced with multi-walled carbon nanotubes (MWCNTs) were fabricated in an autoclave. For laminate fabrication, 0.5 wt% of pristine MWCNTs or silane-functionalized MWNCTs (f-MWCNTs) were dispersed into a diglycidyl ether of bisphenol-A epoxy system and applied on the woven carbon fabric. The neat epoxy/CF composite and the MWCNTs-reinforced epoxy/CF hybrid composites were characterized by thermogravimetric analysis (TGA), thermomechanical analysis (TMA), tensile testing, and field emission scanning electron microscopy (FE-SEM). A significant improvement in initial decomposition temperature and glass transition temperature of epoxy/CF composite was observed when reinforced with 0.5 wt% of f-MWCNTs. The coefficient of thermal expansion (CTE), measured by TMA, diminished by 22% compared to the epoxy/CF composite, indicating an improvement in dimensional stability of the hybrid composite. No significant improvement in tensile properties of either MWCNTs/epoxy/CF composites was observed compared to those of the neat epoxy/CF composite.

Analysis of Structural Work Scheduling of Green Frame - Focusing on Apartment buildings -

Abstract Apartment housings that adopt a bearing wall structure design, which account for a majority of the housing units available in Korea, are not free from structural constraints th at limit the extension of their service life. The resulting need for reconstruction from the ground up requires a massive c onsumption of resources and energy, and triggers environmental pollution resulting from construction wastes. As a solution to such issues, the government enforces incentive schemes to promote a remodeling-friendly rahmen struc ture design. Green Frame, which is a novel concept of composite precast concrete structure to support rahmen structure apartment housing buildings, can address the constraints of bearing wall structure and conventional rahmen s tructure designs that limit the potential for remodeling projects, while reducing the term of construction. Therefore, this study aims to analyze the characteristics of Green Frame and its absolute term of construction, and compare the te rms of frame work construction in apartment housing projects adopting different structural design approaches to ill uminate their differences. In the end, Green Frame is found to be capable of reducing the term of construction in apartment housing projects. As the term of construction is a very critical element of a construction project, Green Frame will ul timately prove to be one of the key enablers to ensure the success of apartment housing construction projects.Keywords : green frame, structural work, scheduling, apartment buildings

The Study on Measures for Reducing Safety Accidents of Excavator

Safety accident resulting from construction projects getting larger and complex day by day has occurred more often than ever. Particularly, the accident caused by construction equipment, among others, has been on the rise. To prevent such accidents, it`s necessary to come up with the measures for reducing the accident. In this study, the cause of safety accidents was analyzed, reviewing the cases of safety accident maintained by Korea Occupational Safety & Health Agency, and the measures for reducing the accident was suggested with computerized safety checklist. The scope of study was limited to excavator, and the result is summarized as below. 1) Investigation was conducted to identify the cases of accident by excavator with the primary causes. 2) Reduction measures were suggested by category of cause of excavator-caused accident. 3) Checklist to prevent the safety accident, which was based on primary causes, was suggested. 4) The measures to stir up safety consciousness and monitor the safety were suggested, making use of computerized system. This study is expected to lay the foundation for further study in future as well as make a great commitment to reducing the safety accident.

A Lifecycle Health Performance Tree for Sustainable Healthy Buildings

A residential environment configured under inappropriate architectural planning could have a harmful influence on the health of users. Such an issue has led to requirements to improve and to evaluate the health performance of buildings. A proper health performance evaluation would aid tenants or purchasers to make a suitable decision, while also providing building owners and house sellers with useful information regarding the health performance of the buildings. The overall health performance of a building should not merely be a total evaluation score of factors, but a framework that reflects the characteristics and importance of each health-affecting factor. In addition, the overall health performance should include a concept that would enable the use of the tool to estimate and improve the health performance not only at the actual operational stage after completion of a building but over the entire lifecycle including planning, design and construction. To this end, a lifecycle health performance tree (LHT) for sustainable healthy buildings has been developed by this study. Unlike the existing method, which measures the indoor air quality, light and noise factors of a completed space, LHT provides an overall evaluation of the health performance of a space during planning.

An Energy Saving Technique Using Ondol Heating Schedule Control of Housing Units in Korea

This study was performed to determine the heating energy savings and carbon dioxide reduction that would result from turning off ondol heating in housing units in Korea. Lowering the room temperature and intermittent heating of a room are effective methods for reducing heating energy consumption. These techniques were proven in our previous studies by modelling simulations. To confirm the simulations schedule controllers, which automatically turned off the ondol heating in the living room and kitchen from 10 pm to 6 am, were installed at the hot water distributor in five households. The heating gas used in each of the housing units was measured over a period of 5 years, with and without the schedule controllers. We found that approximately 30% of gas consumption, mainly used for heating, can be saved compared to turning on the appliance during the night.