내충격 실험에 의한 메타카올린 혼합 반응성분체 콘크리트(RPC)의 방호성능 평가

이승욱 전북대학교 산업기술대학원 2017 국내석사

사례분석을 통한 민간투자사업 투자모델의 경제성 분석 연구 : 전북대학교를 중심으로

김성진 전북대학교 산업기술대학원 2016 국내석사

Going into the 1990’s, due to a rise in demand for social infrastructure, welfare, environment and education, it became very difficult for the government to increase investment in social overhead capital facilities without increasing borrowing and relying solely on state funds. For this reason, a mechanism for private investment was established in 1994 through the Act on Private Investment in Infrastructure. This legislation aimed at efficiently resolving the issue of distribution of state finance and securing funds for construction of social infrastructure facilities. Based on BTO and BTL schemes, our private investment business has provided an efficient supply of funds to social infrastructure at an early stage which, in turn, has increased benefit to the public and brought greater stability to management of public finance. Initially, regional state universities showed interest in private investment, seeing it as a viable solution to the lack of facilities expansion caused by weakening financial conditions and strong reliance on state funds. However, Pusan National University’s failed attempt and changing business climate soon caused interest to decline. Recently, there have been positive developments in business conditions including the implementation of new private investment schemes, namely BTO-rs, BTO-a, by the Ministry of Strategy and Finance in 2015. Chonbuk National University has continued to hold interest in private investment, having decided to retain its private investment department. However, lack of accurate profit and loss calculation analysis has prevented further development. In this regard, a profit and loss calculation analysis focusing on Chonbuk National University as a case study has been carried out. The output should enable domestic higher educational institutions to utilise private investment at opportune moments to promptly secure much needed space and deliver savings to the national budget. With a focus on the BTO scheme, a commonly used method in private investment, analysis models for benefit-cost ratio, net present value and internal rate of return have been applied to assess the economic efficiency of private investment. The results for this research’s case study were as follows: (1) benefit-cost ratio was at 1.176, greater than the standard value of 1; (2) net present value was at KRW 7.514 billion, greater than the basic economic efficiency rate of 0; and (3) internal rate of return was at 8.20%, greater than the social discount rate (i.e. economic efficiency rate) of 5.5%. All three models showed positive economic efficiency. In the instance of fluctuations in one of construction fee (+/- 15%), social discount rate (+/- 1%) or rent (+/- 15%), all three areas still showed economic efficiency. Having said that, in the case of mixed fluctuations such as construction fee rise of 15% combined with a fall in rent of 5% or a rise in social discount rate in 1%, or construction fee rise of 10% combined with a fall in rent of 10%, economic efficiency was absent. For the facilities reviewed in this research, BTO, BTL, BTO-rs and BTO-a schemes were compared against each other with a focus on internal rate of returns. It was found that for a private investor the BTO-rs scheme would be most appropriate because even at the face of a fall in investment cost, the benefit-cost ratio and internal rate of returns would be maintained. For the past five years, internal return rate for domestic BTO schemes have been lower by 2.03% than the standard return rate of 10.23%. In this regard, carrying campaigns to actively draw in private investors seem necessary. For the same time period, BTO schemes have been higher by 3.16% than the average return rate of 5.04% for BTL schemes, making BTL schemes financially burdensome for state authorities and thus, not a suitable option to take. BTO-a schemes were not seen to be suitable as they focus on limiting loss and this function is not very useful considering, as shown above, economic efficiency still exists in the event of fluctuations in one of construction fee, social discount rate or rent.

활성화 슬래그를 활용한 컬러 모르타르용 바인더 개발과 실용화

전의현 전북대학교 일반대학원 2017 국내박사

Ordinary Portland Cement (OPC) is a key in the color of concrete which has very monotonous and dark gray. To consider a beautiful appearance of concrete structures, various concrete such as aggregate exposure concrete, photo engraved concrete and colored concrete which is called architectural concrete, has been developed. Among those things, colored concrete is generally used as the exterior finishing materials with the design element as well as a structural function in the concrete structures. Colored concrete is able to make various colors which a user and an architect require with various pigments in white portland cement (WPC). Pigments are used in permanent coloring of concrete with colors different from the natural color of the cement or the aggregates with mixing WPC. However, the existing colored concrete has some problems such as increases in construction cost due to high unit price of WPC, decreases in workability and increases of efflorescence, etc. Colored concrete is an attractive alternative to traditional concrete which has poor esthetic properties, in the view point of architectural designs. White Portland Cement (WPC) and inorganic pigment have been used in colored concrete, but there are some physical problems such as increases in efflorescence, and poor workability and low economics. In this study, color expression characteristics and physical properties of colored mortar using activated ground granulated blast-furnace slag (GGBS) was investigated and compared with general WPC colored mortar. The results show that the addition ratio of GGBS influences significantly the color value efficiency in colored mortar. The overall amount of CaO, Ca(OH)2 in the colored mortar using GGBS was smaller than that of WPC colored mortar, and it was contributed to decreases efflorescence and gave more visible color to mortar. And the flow of colored mortar was decreased with mixing inorganic pigments, but increased in proportion to the addition rate of the GGBS. In addition the strength of colored mortars with activated GGBS at the curing period of 28 days was higher than that of the general WPC colored mortar, although its strength was developed slowly at the early ages.

황토의 양이온 교환 능력에 따른 VOCs 흡착특성 평가

조준현 전북대학교 일반대학원 2019 국내석사

The energy issues caused by the oil crisis in 1970s have led to eco-friendly construction of high thermal and airtight insulation in the construction sector, and as a result, it began also cause problems with indoor air quality. Representative of all indoor air pollutants is Volatile Organic Compounds(VOCs) which are mainly produced from finishes and furniture, and this directly affects the human body. Therefore, this paper has tried to evaluate the cation exchange capacity and adsorption performance of VOCs by selecting the Hwangtoh from Gochang, Sancheong, Iksan, and Hongcheon area which are the most representative Hwangtoh producing areas in Korea. Component analysis, mineralogical composition, specific surface area and pore analysis, which are closely related to cation exchange capacity was measured using XRF, XRD, and BET equipments respectively, where the Hwangtoh from Sancheong area had the best composition, specific surface area, and porosity. The cation exchange capacity was measured by neutral ammonium acetate method and methylene blue method, which are typical methods of measuring cation exchange capacity, and the Gochang and Sancheong area was shown to have the highest cation exchange capacity. The adsorption performance of VOCs on Hwangtoh was evaluated by selecting three polar (diethylamine, methylethylketone, formaldehyde) and two nonpolar (benzene, cyclohexane) among the VOCs regulated by Korea, and the Sancheong area has shown the highest adsorption capacity in the Hwangtoh. For two polar (methylethylketone, formaldehyde) VOCs, a similar tendency was found in cation exchange ability and adsorption performance.

시멘트 콘크리트 수화가스 분석 및 실험동물 노출 유해성 평가

장홍석 전북대학교 일반대학원 2013 국내박사

When visiting underground spaces that have poor ventilation or building that are surrounded by cement concrete, we can detect a pungent odor as the unique smell of concrete. This odor is caused by the various gases occurring by the hydration process of cement concrete (or mortar), while the amount and types of gas depend on the composite materials and environmental factors such as moisture, temperature etc. And gases from hydration process of cement concrete(mortar) can be released through fast diffusion in concrete and have a significant influence on men’s health and air pollution, and they are becoming a serious problem throughout the world. However, only a few investigations on hydration gas released from cement concrete have been carried out. The focus of this paper is to make the measuring process the emission of hydration gases from cement concrete, analysis of occurrence mechanism and laboratory animal exposure risk assesment of cement concrete. In this study, first, the capture and analysis processor of gas were configured using Air Pollution Process Test Method and Indoor Air Quality Test Method to conduct the qualitative and quantitative analysis of gas which occurs in the concrete. And the following experiments were progressed: 1) This paper is to measure the emission of NH3 from cement mortar using different aggregate according to the area of production and to investigate the relationship between the amount of organic matter and ammonium(NH4+) contained in the aggregate as well as the emission of NH3 from cement mortar using different aggregate from area of production. 2) To evaluate the pattern of gases emission from cement concrete mixed with additives, the emission levels of gas including ammonia (NH3), volatile organic compounds(VOCs), Radon were measured from 3 different mortar types(Ordinary Portland Cement, Ordinary Portland Cement with fly ash, Ordinary Portland Cement with GBFS) on various time points after manufacture. 3) In order to determine what the VOCs and ammonia gas from concrete the potential have an effect in the progression of Asthma disease, the Asthma was induced to mice using OVA model. The mice were allowed to live within a concrete cage after this, and it was identified what a physiological changes were occuring for them. 4) To examine their effects on allergic respiratory system, mice were sensitized with ovalbumin(OVA) and divided five groups(normal, asthma control, OPC mortar, OPC mortar with fly ash and OPC mortar with GBFS). And mice were housed in each cage for 10 days with OVA challenges to induce asthma. Results are as follows 1) In the case of ammonia gas which occurs in the concrete, the Indophenol method using the solution absorption method was applied, and in the case of VOCs, the analysis processor was organized using Purge & Trap GC/MS method. 2) It is found that NH3 released from cement mortars is produced by the reaction of NH4+ adsorbed into the aggregate with a strong alkali in cement mortar, as a process of ammonia volatilization. The concentrations of NH3 emission from cement mortar according to the aggregate used from different areas of production differ by more than 4 times. And the differences depend on the content of NH4+ adsorbed into the aggregate. The results of the experiment indicate that the content of ammonium ion in sand is strongly related to the content of organic matter. This is because ammonium ion is composed of organic matter and the increase of organic matter leads to the increase of ammonium ion due to the high CEC of the aggregate. 3) As the mixing ratio of GBFS and Fly ash was increased, the ammonia emission of concrete was increased. In the case of Fly ash concrete, the ammonia adsorbed on the surface of Fly ash in SCR treatment process for nitrogen control was identified as a source of gas. In the case of GBFS, the atmospheric nitrogen dissolved in the form of freedom nitrogen in the manufacturing process of the molten slag in high temperature state, and the magnesium mixed into the slag were the causes. 4) A trace of VOCs was analyzed in OPC mortar, Fly ash mortar, GBFS mortar and especially, Fly ash mortar were occurred the emission of the most diverse types of VOCs in the early material age. In addition, in the case of the admixture, various VOCs was analyzed depending on the type of synthesis. 5) Histopathologically, increased infiltration of lymphocytes was observed in perivascular area of lung of mice housed in both OPC mortar and OPC mortar with fly ash cages compared to asthma control. Moreover, severe bronchial lumen obstruction and increased hypertrophy of bronchial epithelial cells (p<0.05) were observed in OPC mortar with fly ash group compared to OPC mortar or asthma control groups. Lungs of two mortar groups (OPC, OPC with fly ash) generally expressed higher levels of genes related with asthma including IL-4, eotaxin and EGF compared to asthma control mice. Additionally, OPC mortar with fly ash group showed higher expression of IL-5, 13 and MCP-1 compared to asthma control group. These results indicate that OPC mortar and fly ash might contribute to exacerbate asthma.

푸른곰팡이와 물벼룩 노출실험을 통한 황토의 친환경성 평가

이보람 전북대학교 일반대학원 2016 국내석사

Recently government is developing ‘Shinhanok’ for popularizing ‘Hanok’ that is traditional Korean house. ‘Shinhanok’ is a structure based on the wooden construction method and the external appearance of Hanok. Not only that, modern technology and materials are also used. For this reason, it lacks the beneficial effects of Hanok such as environmental performance. Because the significance of Hanok is environmental performance, it is necessary to consider this point. There are natural materials being used in Hanok as representative reason of environmental performance. Therefore, it has emerged as an important issue to identify the effects of a natural construction material used for Hanok. Hwangtoh is a natural construction material used for various purposes, such as deodorant, anti-gas and building materials. The moisture controlling effect of Hwangtoh is commonly known, but has not been scientifically proven; the deodorization effect has not been identified, either. The purpose of this study is to indicate performance of Hwangtoh with the numerical data by analyzing the functional characteristics, such as moisture controlling and deodorizing effects of Hwangtoh as a construction material. In this study, moisture controlling and deodorizing effects of Hwangtoh are assessed and the biological tests based on its performance were conducted. The results were as follows. Ammonia deodorizing amount of Hwangtoh was three times larger than that of cement. In addition, the ammonia deodorizing performance of Hwangtoh was not correlated with the thickness of Hwangtoh and it had needed enough time to be absorbed. In accordance with ammonia deodorizing, survival rate of Daphnia in Hwangtoh were higher than in cement. The moisture controlling performance of Hwangtoh was maximum 9 times higher than that of cement. The moisture controlling performance of Hwangtoh was changed according to the thickness of Hwangtoh and it had needed enough time to absorb the water. Because of the water absorption of hwangtoh, growth rate of fungi in Hwangtoh by moisture controlling was lower than in cement. In this study, the performance of Hwangtoh were indicated with the numerical data and were verified through biological experiments which can support the numerical data.

환경부하 저감형 말뚝채움재 개발에 관한 연구

송상훤 전북대학교 일반대학원 2021 국내박사

최근 몇 년 동안 건물이 커지고 고층이 증가함에 따라 파일 기초가 건물 기초로 점점 더 많이 적용되었습니다. 또한 소음 및 진동으로 인하여 도심지에서는 매입말뚝공법이 주로 시공되고 있다. 매입말뚝공법에서 보통 포틀랜드 시멘트(OPC)를 말뚝채움재로 사용하고 있다. 그러나, 시멘트는 생산과정에서 다량의 온실가스가 배출되고, 다량의 에너지원이 소비되는 환경적인 문제를 가지고 있다. 따라서 OPC를 대체하는 제품에 대한 연구가 필요하다. 또한 산업활동에서 다량으로 배출되는 고로슬래그 및 저품질 플라이애시 등 순환자원은 대량 재활용하는 연구도 필요하다. 이러한 배경으로 착안하여 본 연구에서는 국내 기준과 재료적 문제로 인하여 대량 재활용에 어려움을 가지고 있는 순환 유동층 보일러의 연소재(CFBC)를 고로슬래그의 알칼리 활성화 반응의 자극제로 재활용한다. 순환 유동층 연소 보일러 Fly Ash는 시멘트와 동일한 경화 반응을 유발할 수 있기 때문에 저 강도를 요구하는 공법에서 시멘트를 대체 할 수있는 것으로 판단되었다. 이를 통한 탄소배출량의 저감 및 순환자원의 재활용이 가능하여 환경적으로 긍정적인 효과를 유도할 수 있는 환경부하 저감형 말뚝채움재(EPFM, Environmental load reduction type Pile Filling Material)를 개발하고자 한다. 환경부하저감형 말뚝채움재 개발을 위해, 다양한 순환 유동층 보일러 연소재에 대한 원시료분석, 말뚝채움재별 압축강도, 흐름특성, 주면마찰력, 내진성능 등을 비교 시험하였다. 또한, 환경안정성 평가(중금속 용출 및 함량, 급성 어독성시험)를 통하여 환경부하 저감형 말뚝채움재를 개발하였다. 그리고 EPFM과 OPC를 사용하여 두 곳에서 비교 검증을 수행하였다. 검증 결과 OPC 이상으로 성능이 확인되었습니다. 이에 EPFM을 아파트 2 개 부지의 기초 공사에 적용하여 부하 시험 결과 OPC 이상의 성능과 시공성을 실현하여 현장 적용성이 우수하다는 것을 확인하였습니다. 이렇게 EPFM을 OPC를 대체하는 말뚝채움재로 적용시 온실가스 저감효과는 0.7549ton CO2/ton으로 총 1,223,267tonCO2에 이르며, 경제적으로도 약 20%정도 절감되어 총 24,306백만원의 원가절감효과가 발생한다.

비정형 외장판넬을 가진 호텔 건설사례 : 강릉 스카이베이 경포호텔

박하일 전북대학교 산업기술대학원 2022 국내석사

건축물의 외장은 건축물의 용도와 밀접한 관계를 가지고 있으며, 설계자의 의도와 목적을 잘 나타낼 수 있어야 한다. 하지만 외부 디자인은 건축물의 구조와 시공성, 비용 등의 문제로 설계, 시공단계에서 많은 제약을 받게 된다. 정형화된 기존의 공법에 비해 시공경험과 사례 부족으로 많은 어려움을 격게 된다. 더욱이 기존의 사각형 형태를 벗어나 기울어지거나 좁아지고 뒤틀려지는 자유로운 곡면으로 이루어진 현태의 비정형 외장 건축물은 더 큰 문제들을 극복해야 한다.

탄산촉진제와 양생 조건에 의한 경소 마그네시아 시멘트의 CO₂ 고정 특성

임용택 전북대학교 일반대학원 2021 국내박사

HMCs were calcined under appropriate conditions to form light-burned MgO, and the specific surface area, and crystal and micro-structures of the fabricated MgO were evaluated. This allowed the determination of the impact of calcination conditions on the sintering characteristics of light-burned MgO. A paste was fabricated by adding a recently developed carbonation accelerator to the light-burned MgO. Magnesium hydrates and carbonates were obtained by adjusting the temperature and CO₂ content and were mineralogically analyzed to understand their formation mechanism. In addition to the analysis of mineralogical and physical properties, a thermodynamic evaluation was conducted to understand the CO₂ capture capacity. 1. The crystal size of MgO powder increased with calcination time and temperature; the calcination temperature was more influential than calcination time. In addition, MgO calcined at 1000 °C was sintered into aggregates, and exhibited typical characteristics of hard-burned MgO rather than those of light-burned MgO. 2. As the crystal size of light-burned MgO increased, hydration slowed down. When the crystal size was 50 nm and above, standard moist curing was unable to completely hydrate MgO into brucite even after 28 days, and MgO residues were obtained. 3. When carbonation-accelerated curing was performed for hard-burned MgO, the specimens cured at 700 °C contained hydromagnesite, while those cured at 800, 900, and 1,000 °C contained a mixture of nesquehonite and brucite. As the crystal size of MgO increased, carbonation slowed down and the amount of residual uncarbonated brucite tended to increase. The rate of CO₂ fixation by hydromagnesite was approximately 90%, and that of nesquehonite was approximately 50 %. 4. When the light-burned MgO specimens were subjected to temperature-controlled standard moist curing with a carbonation accelerator, more carbonates were formed as the crystal size of MgO increased compared to those formed when no carbonation accelerator was added. The formation of carbonates were facilitated by high-temperature curing. However, due to the nature of standard moist curing, each specimen contained a certain amount of uncarbonated brucite. The maximum CO₂ fixation was 39% and the compressive strength was as low as 4 MPa. 5. In the case of hard-burned MgO specimens subjected to temperature-controlled carbonation-accelerated curing, all specimens achieved complete carbonation. Dypingite was formed at 25 °C, in which 86–95 % of CO₂ was fixed, and the maximum compressive strength was as high as 7 MPa. At 60 ℃, hydromagnesite was formed in which 77–86 % of CO₂ was fixed, and the maximum compressive strength did not exceed 4.5 MPa because of mineralogical limits. 6. The addition of a carbonation accelerator did not have a greater effect on the fixation of CO₂ than that the carbonation accelerated curing when used alone. However, when combined with accelerated carbonation curing, the fixed ratio of CO₂ of light magnesia with large crystal size was significantly increased. And substitution of 10 % or more did not differ in the fixed amount of CO₂. In summary, this study examined the powder and hydration characteristics of light-burned MgO by investigating the formation mechanisms of hydrates and carbonates based on the crystal size of MgO and effect of carbonation-accelerated curing. The CO₂ fixation and compressive strength were dependent on the type of MgCO₃ formed. Although this study demonstrated the potential of light-burned MgO cement for atmospheric CO₂ reduction and clarified its mechanisms of CO₂ fixation and strength development, several challenges in the application of light-burned MgO cement in the construction industry remain. Therefore, to apply light-burned MgO to the construction industry, further studies must be conducted to address the water/binder ratio reduction, compressive strength improvement, and long-term durability assessment.

현행 목조건축프로그램 운영에 대한 이수자와 수요자의 평가에 관한 연구

김가영 전북대학교 산업기술대학원 2013 국내석사

The purpose of this study in the operation of the current wooden building program for graduates and consumer surveys, The goal is to learn to the necessary training in the field of education and industrial analysis. Program status through the web site and visit survey was conducted, Each institution's graduates sent questionnaires to more than 250 193 people responded to the General Information for the Curriculum, satisfaction surveys were examined, the wooden building construction and industrial companies sent questionnaires to 250 companies in, Hanok Contractors (35 companies), received a wooden houses Contractors (52 companies), construction companies (22 companies) 109 Companies survey. Analysis for the survey is as follows. (1) Participate in the educational reasons for In order to acquire qualifications for employment or establishment, much higher. (2) Appeared to be the most preferred 5-6 months training period. In addition, was important when selecting education curriculum content and instructor expertise. (3) Company, the manpower required, human nature education, construction education, Theory of education, curriculum requirements in order. Appeared at the conclusion of the various requirements by considering the characteristics of each institution, including educational institutions, educational program created progress has been. Of course, the training programs the direction of the educational program may vary depending on market conditions and industry conditions.