• Computers and Concrete
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• 제3권4호
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• pp.213-233
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• 2006

Over the past years techniques for non-linear analysis have been enhanced significantly via improved solution procedures, extended finite element techniques and increased robustness of constitutive models. Nevertheless, problems remain, especially for real world structures of softening materials like concrete. The softening gives negative stiffness and risk of bifurcations due to multiple cracks that compete to survive. Incremental-iterative techniques have difficulties in selecting and handling the local peaks and snap-backs. In this contribution, an alternative method is proposed. The softening diagram of negative slope is replaced by a saw-tooth diagram of positive slopes. The incremental-iterative Newton method is replaced by a series of linear analyses using a special scaling technique with subsequent stiffness/strength reduction per critical element. It is shown that this event-by-event strategy is robust and reliable. First, the model is shown to be objective with respect to mesh refinement. Next, the example of a large-scale dog-bone specimen in direct tension is analyzed using an isotropic version of the saw-tooth model. The model is capable of automatically providing the snap-back response. Subsequently, the saw-tooth model is extended to include anisotropy for fixed crack directions to accommodate both tensile cracking and compression strut action for reinforced concrete. Three different reinforced concrete structures are analyzed, a tension-pull specimen, a slender beam and a slab. In all cases, the model naturally provides the local peaks and snap-backs associated with the subsequent development of primary cracks starting from the rebar. The secant saw-tooth stiffness is always positive and the analysis always 'converges'. Bifurcations are prevented due to the scaling technique.

• 한국태양에너지학회 논문집
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• 제34권5호
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• pp.109-115
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• 2014

The supply rate of renewable energy has been increasing under the influence of an energy scarcity. Government has supported the use of renewable energy by government subsidies. The operation of renewable may not been operating appropriately, although increasing the use of renewable energy. We found out some problems of the operation of renewable energy and offered some improvements. This research proposes the efficient operation method for the solar thermal system, and proposed operation method was compared and evaluated with existing operation strategy after selecting one building installed solar thermal system. Recently, the interest to renewable energy has increased because of the environmental issues and energy crisis. However the utilization of the renewable energy system is low because of the use of renewable energy system and existing renewable energy system independently, although supply rate of renewable system is increasing. Especially, in the case of solar thermal system heating load is not responsible for the load of hot water supply in many cases. Therefore, suggesting efficient operation plans and evaluations of the energy consumption and efficiency of a solar thermal system is needed.

• 동굴
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• 제90호
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• pp.35-56
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• 2009

본 연구의 목적은 동굴환경의 황폐화에 대한 지속가능한 동굴의 연구, 관광 및 보존을 위하여 첨단정보화 기술인 유비쿼터스 정보기술을 활용한 새로운 차원의 동굴시스템을 제시하는데 있다. 이러한 환경문제를 극복할 수 있는 방안으로 첫째, 동굴에 대한 법제도나 조례 등으로 강력한 관리방안이 제시되거나 휴식년제 도입 등으로 행정적인 방안이 있으며, 둘째, 최첨단 정보기술을 적용하여 효율적이고 지속가능한 동굴의 관리로 지하동굴 자원의 청정환경을 도모하는 방법이 있다. 유비쿼터스 동굴의 구축에는 첨단 자동정보시스템 인 감지시스템(USN), 모니터링시스템(RFID/UFID), 무선통신시스템(WiBro/WiFi), 공간정보시스템(GIS), 항공레이저시스템(LiDAR), 저열 조명시스템(ELD) 및 통합관리시스템 등이 적용되었다. 이러한 유비쿼터스 동굴 구현에 필요한 첨단화 정보기술분야의 산업적인 융합에 의한 차세대 동굴살리기 명품솔류션 구현을 통하여 공간정보기반의 유비쿼터스 동굴관리시스템의 모델을 제시하였다. 따라서 u-cave모델은 정책의 적용에 따라 동굴의 자연관리, 생태관리, 시설관리, 관광관리, 문화관리 및 소득창출 등의 시너지 효과를 달성할 수 있는 것으로서 동굴의 자연환경보존 기반의 수단으로서 기여 될 수 있다.

• 설비공학논문집
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• 제17권9호
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• pp.863-872
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• 2005

It is important to control indoor environment for influence on health and comfort of occupants in large-sized discount stores. On the other hand large-sized discount stores have a large number of visitors, vestibules, open spaces, high energy consumption and increasing of outside air intake. This study aims to offer the design data of building services system that can save energy and control environment through field measurement selecting two large-sized discount stores. Indoor environment factors such as temperature, relative humidity, air velocity and concentrations of $CO_2$, CO gas and TSP were measured and evaluated. In each case of $CO_2$, and CO gas, its maximum values were 2,800 ppm and 20 ppm. So proper strategy for the indoor air quality is indispensable in this type of building. Dry bulb temperature varies from $18^{\circ}C$ to $28^{\circ}C$ according to a measuring point and time. From this results, it is inferred these buildings had excessive equipment capacity. In terms of economical and environmental points, these data will be utilized to the design of HVAC system of retail facilities.

• 한국철도학회논문집
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• 제14권5호
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• pp.425-432
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• 2011

철도시설물 유형별 전과정 온실가스 배출량에 관한 연구결과를 분석한 결과 철도건설에 사용된 콘크리트가 주요 발생원임을 확인하였다. 친환경설계전략(ECODESIGN PILOT)을 활용하여 철도시설물의 제품유형을 분석한 결과에서도 철도시설물은 재료집약제품으로 분류되었다. 따라서, 본 연구에서는 건설재료측면에서 철도시설물의 온실가스배출량을 저감하는 방안을 도출하고 이를 철도현장에 시범, 적용함으로써 그 저감효과를 분석하였다. 연구에서 고려한 철도시설물의 온실가스 배출저감기술은 고로슬래그를 이용하여 시멘트 사용량을 저감한 친환경 콘크리트와 콘크리트 구조물의 수명을 보장할 수 있는 콘크리트 열화방지제이다. 그리고 설계단계에서 철도노선에 대한 온실가스배출량을 사전에 평가하고 예측할 수 있는 저탄소 철도노선 평가 및 설계기술이다.

• 한국환경생태학회지
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• 제32권2호
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• pp.225-230
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• 2018

본 연구는 생태지역 유형에 따른 방문자의 경험에 대한 인식을 비교하는데 목적을 두고 수행되었다. 연구목적 달성을 위해 생태지역 유형을 자연생태지역과 인공생태지역으로 구분하였으며, 생태지역별 방문 경험자를 대상으로 방문경험에 대한 인식도 분석과 인식도에 따른 만족도 분석을 실시하였다. 먼저, 방문경험 인식 측정요소에 대한 분석결과, 생태체험, 환경친화, 사회성, 휴식 등의 4개 요인이 도출되었다. 자연생태지역과 인공생태지역에 따라 방문경험 요인별로 인식차이를 비교한 결과, 전반적으로 자연생태지역에서의 방문경험 인식이 높은 것으로 나타났다. 또한, 생태지역방문경험 인식이 방문자 만족도에 미치는 영향 분석 결과에서는 자연생태지역과 인공생태지역에서 휴식성이 가장 많은 영향을 미치는 요인으로 나타났다. 자연생태지역에서는 생태체험 요인, 인공생태지역에서는 환경친화 요인이 방문자 만족에 영향을 미치는 것으로 분석되었으며, 이에 대한 계획 및 관리적 차원의 시사점을 제시하였다.

• 상하수도학회지
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• 제21권1호
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• pp.139-147
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• 2007

For environmental remediation of a contaminated groundwater plume, the use of zero-valent metal represents one of the latest innovative technologies. In this study, the effects of denitrification by zero-valent iron adsorbed in mesoporous silicas have been studied for groundwater contaminant degradation. The mesoporous silica was functionalized with 3-mercaptopropyltrimethoxysilane (MPTS) ligands and the zero-valent iron precipitated in the mesopore of granular silica was made by $FeCl_2$ and $NaBH_4$. Hydrogen was exchanged with $Fe^{2+}$ ions in the granular silicas. And then the ions were reduced by sodium borohydride in the mesoporous silicas. The surface area of the silica determined via the BET method ranged from 858 to $1275m^2/g$. The reductive reaction of nitrate-nitrogen indicated that the degradation of nitrate-nitrogen appeared to be pseudo first-order with the observed reaction rate constant kobs ($0.1619h^{-1}$) and to be directly proportional to the specific surface area. Therefore, the mesoporous silica with nano zero-valent iron proposed as a novel treatment strategy for contaminated groundwater was successfully implemented herein for the removal of nitrate-nitrogen.

• 근관절건강학회지
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• 제10권1호
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• pp.19-31
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• 2003

Purpose : The purpose of this study was to examine the effect of the self- efficacy, group cohesion and family support on adherence of aquatic exercise in arthritis patients. Method : The Subjects were 30 patients with arthritis who had participated in the 6-week aquatic exercise programs of Korean Rheumatology Health Professionals Society. All subjects were interviewed from November to December, 2001(1st) and Feburary, 2002(2nd) using a structured questionnaire which was composed of 42 items. SPSS Win 10.0 was used for data analysis. Results : Ten out of thirty were adherer who were keeping aquatic exercise for three months since they completed 6-week aquatic exercise program. The major reasons of adherence were affectional reasons and general condition improvement on the first month. The reasons of 3-month adherence were improvement of arthritis symptoms, affectional improvement, expectations, general condition improvement and group activity. The major reasons of drop out were environment factors and physical factors. The environmental reason were time shortage, economic problem and long distance. And the physical factor were cold, pain and other health problem. The scores of self-efficacy were decreased from 528.00 to 476.00 within 3 months after compeleting aquatic exercise program and that was statistically significant(p=.029). But there were no statistically differences in group cohesion and family support. There was a significant positive correlation between exercise adherence and self-efficacy. Factors influencing the exercise adherence was self-efficacy which accounted for 23% of the variance in the exercise adherence. Conclusion : In conclusion, self-efficacy is a significant variable in the exercise adherence and changes within 3 month after completing aquatic exercise program. The results of this study suggested that the strategy for maintaining self-efficacy should be developed.

• Journal of Microbiology
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• 제44권2호
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• pp.233-242
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• 2006

The objectives of this study were to optimize submerged culture conditions of a new fungal isolate, Ganorderma resinaceum, and to enhance the production of bioactive mycelial biomass and exopolysaccharides (EPS) by fed-batch culture. The maximum mycelial growth and EPS production in batch culture were achieved in a medium containing 10 g/l glucose, 8 g/l soy peptone, and 5 mM $MnCl_2$ at an initial pH 6.0 and temperature $31^{\circ}C$. After optimization of culture medium and environmental conditions in batch cultures, a fed-batch culture strategy was employed to enhance production of mycelial biomass and EPS. Five different EPS with molecular weights ranging from 53,000 to 5,257,000 g/mole were obtained from either top or bottom fractions of ethanol precipitate of culture filtrate. A fed-batch culture of G. resinaceum led to enhanced production of both mycelial biomass and EPS. The maximum concentrations of mycelial biomass (42.2 g/l) and EPS (4.6 g/l) were obtained when 50 g/l of glucose was fed at day 6 into an initial 10 g/l of glucose medium. It may be worth attempting with other mushroom fermentation processes for enhanced production of mushroom polysaccharides, particularly those with industrial potential.

• 산업경영시스템학회지
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• 제41권3호
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• pp.11-20
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• 2018

Recently companies have increased the new projects to improve and innovate the business process in order to adopt the advanced technologies such as IoT (Internet of Things), Big Data Analysis, Cloud Computing, mobile and artificial intelligence technologies for sustainable competitive advantages under rapid technological and socioeconomic external environmental changes. However, there are obstacles to achieve the project goals, corporate's strategy and objectives due to various kind of risks based on characteristics of projects and conflicts of stakeholders participated on projects. Hence, the solutions are required to resolve the various kind of risks and conflicts of stakeholders. The objectives of this study are to investigate the impact of the project governance, agency conflicts on the project success based on agency theory by using the statistical hypothesis testing the relationship among those variables. As a result of hypothesis testing, we could find that the project governance impacts positively on project success and negatively on the agency conflicts. Further, the agency conflicts impacts negatively on the project success. Finally, we could find that the agency conflicts such as goal conflict, different risk attitude and information asymmetry between project manager and team members impact negatively on the project success. Meanwhile, the project governance impact positively on the project success, negatively impact on the agency conflicts such as goal conflict, different risk attitude and information asymmetry between project manager and project team members. In order to increase the project success rate, the project governance institutions such as PGB (Project Governance Board), EPMO (Enterprise Project Management Office), PSC (Project Steering Committee) are needed to prevent or reduce the agency conflicts between project manager and team members.