• Computational Structural Engineering : An International Journal
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• 제2권1호
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• pp.25-32
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• 2002

Natural draught cooling towers often develop visible crack structures as consequences of progressive damage processes over their life-time. The aim of this paper is a numerical demonstration of the progressive damage process of cooling towers, representatively for the reinforced concrete structures, in order to improve the durability and extend the life-time of structures subjected to such damage processes. For the analyses, the applied material model for reinforced concrete will be briefly introduced. An existing natural draught cooling tower with a pronounced crack structure, in which this crack structure indicates the typical damage pattern of large cooling towers will be numerically simulated. The change of dynamical behavior of the structure with regard to natural frequencies, reflecting the global damage process due to the degrading stiffness of the structure in dependence of the load type and intensity, will be presented and discussed.

• 한국시뮬레이션학회논문지
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• 제7권2호
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• pp.105-114
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• 1998

Using finite elements, a simulation is prformed for the pipe systems to investigate free vibrational characteristics, that is natural frequencies, considering the intial tension due to the velocity and the pressure of the inside fluid flow. To confirm the program developed in this study, the results are compared with the results of commercial software ANSYS. When the initial tension is neglected in curved pipes, the natural frequencies are reduced as flow velocity increases, and the rapid decreases of the natural frequencies took place. However, when the initial tension is taken into account, the natural frequencies are not changed with the change of the flow velocity. In free vibrational simulation of pipe systems, it is necessary to calculate the initial state force due to the velocity and the pressure of the fluid flow from the equilibrium first, then the force should be included in the equation of motion of the systems to get more accurate natural frequencies.

• 한국환경교육학회지:환경교육
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• 제23권4호
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• pp.15-31
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• 2010

This research aimed for revealing social interaction-based environmental learning elements at the natural history museum. First, we carried out a survey of the perceptual change about 'the environment' concept. It was for confirming whether environmental learning occurred in visiting. Second, we found environmental learning elements through analyzing dialogues among small group members during looking around the museum. Social interaction-based environmental learning elements were classified into five; knowledge, affection, value, skill, behaviour. Each environmental learning element included several sub-elements, so we revealed totally 9 environmental learning sub-elements. By results, we said characteristics and possibility of the natural history museum as an informal environmental educational institution. It is meaningful for extending areas of environmental education.

• 한국어류학회지
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• 제22권4호
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• pp.230-237
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• 2010

자연하천에 서식하는 미꾸라지의 등, 체측, 후두부 피부조직에 대한 점액세포의 계절변화를 조사하였다. 2008년 3월부터 2009년 2월까지 계절변화에 대한 월별 조사에서 피부조직의 일반적인 형태변화는 없었으나, 상피조직 단위면적당 존재하는 점액세포의 크기와 개수는 겨울철에 가장 높게 나타났고, 여름철에 가장 낮게 나타나 계절변동에 따른 점액세포의 유의한 변화가 관찰되었다. 특히 후두부 부위는 점액세포의 계절변동 폭이 크고, 늦가을 환절기의 기온급감에 따른 점액세포의 급격한 변화를 보여 환경변화에 대한 반응이 가장 민감한 부위로 여겨진다. 또한 점액세포는 수온이 감소함에 따라 외부형태가 작은 구형에서 크고 긴 원주세포형으로 변화하였으며, 다량의 점액물질이 분비되었다. 본 연구를 통해 "저온"은 겨울철 미꾸라지 피부의 점액세포를 변화시키는데 밀접한 연관이 있는 중요한 환경요인으로 여겨진다.

• 한국기후변화학회지
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• 제8권2호
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• pp.153-161
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• 2017

The purpose of this study is to screen for the effects of climate change and climate change adaptation in the insurance industry. There is now a consensus that the climate is changing, with potential risk to the global economy and human health and so on. On the other hand, unknown is the extent to which insurance business pattern have already been affected. But the increase in damage due to climate change is likely to raise insurance company losses. In this regard, I conduct especially an effects of the insurance industry on climate change. And than, I analyzed what insurance companies would do to lessen the impact of climate change. As a result, the impact of climate change on the insurance industry is a huge increases in claims due to disasters and diseases arising from climate change. And another thing is growth in climate change-related legislation, regulations and reporting requirements such as financial soundness regulation and climate change risk disclosure. Therefore, the insurance industry needs to build a climate change adaptation strategies include capital raising, liquidity of assets, faithful debt management and so forth.

• 분석과학
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• 제18권1호
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• pp.89-95
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• 2005

Studies on the electrochemical reduction of 7-acetoxy-4-bromomethyl-coumarin (ABMC), 7-acetoxymethyl coumarin (AMC), and coumarin in 0.1 M tetraethyl ammonium perchlorate acetonitrile solution were carried out with direct current, differential pulse polarography, cyclic voltammetry, and controlled potential coulometry. The electrochemical reduction of ABMC was proceeded through three irreversible steps coupled with the chemical reactions. The solution color was changed to yellow when the carbonyl group was reduced during second step and the color change was independent with bromo group of ABMC. Fluorescent intensity was highest when the electrochemical reduction was controlled at near the overpotential of supporting electrolyte (-2.3 volts).

• KIEAE Journal
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• 제16권6호
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• pp.129-134
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• 2016

Today, natural ventilation systems are widely applied in multi-family housing. However, studies using the wind data trend line of the blower door test are insufficient. Purpose: Through this study, we will propose a computational method about ventilation performance of natural ventilation systems by conducting blower door test. Method: First, we sealed the gaps between the main systems including the natural ventilation system and conducted the blower door test. Next, the natural ventilation system was opened, the blower door test was conducted, and the difference in air flow rate between when closed and when opened was checked. Blower door test was carried out with a pressure difference of 50 Pa. Result: Therefore, the ventilation performance of the natural ventilation system was checked by drawing a trend line using the data to calculate the air flow rate at 2 Pa of the natural ventilation equipment standard pressure difference.

• 한국환경교육학회지:환경교육
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• 제21권1호
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• pp.45-56
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• 2008

This study is to consider the fundamental perceptions of pre-service elementary school teachers to natural environments. The recognition items of questionnaire for those environments include ones of water, atmospheric, soil, biologic and oceanic environments constituting of the earth system. From the results of the study, they affirmatively recognized biologic environment, but they showed highly negative recognitions to others. In other side, it is considered that their recognitions to natural environments were probably transferred by the things which involve press media, curricula and real lives. On the basis of the study results, systematic teaching-learning for natural environments is essential because the encouragement of eco-friendly attitude, one of main goal for environmental education, is budded from basic understandings to natural environments. Affirmatively environmental worldviews for elementary school students are important for reasons why teacher's quality and practice will is fundamental, and then teacher could change the views of the students for environmental education. So, preparing balanced attitudes, right concepts and connection to applicable knowledges for natural environments, pre-service elementary school teachers in environmental education must be pointed to organized education between human and natural environment.

• 아동학회지
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• 제22권1호
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• pp.97-107
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• 2001

This study argues the nature of the microgenetic method in respect to child development research and explores its merits and limitations. The microgenetic method focuses on observations that span the entire period from the beginning of developmental change to the time it reaches a relatively stable state. This produces a high density of observations relative to the rate of change in the phenomenon. In this way, observed behavior may be used in intensive trial-by-trial analysis. The microgenetic method is superior to other methods in the possibilities for observing developmental changes as they occur, examining various aspects of change, detecting variability in behavior, and flexibility in application regardless of theoretical perspectives. Limitations of this method include reliability problems due to repeated observations, artificiality relative to the natural situation, inconsistency of short-and long-term change, and demands on children's motivation for participation in research.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.397-397
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• 2019

With the consequences of climate change becoming more evident, research on climate-associated risks has become a basis for climate adaptation and mitigation. Amongst the different sectors and natural resources considered in assessing such risks, drought is one impact to our environment that experiences stress from climate change but is often overlooked and has the potential to bring severe consequences when drought occurs. For example, when temperatures are higher, water demand increases and water supply decreases; when precipitation patterns fluctuate immensely, floods and droughts occur more frequently at greater magnitudes, putting stress on ecosystems. Hence, it is important for us to evaluate drought risk to observe how different climate change and socioeconomic scenarios can affect this vital life resource. In this study, we review the context of drought risk on the basis of climate change impacts and socioeconomic indicators. As underlined in the IPCC AR5 report, the risks are identified by understanding the vulnerability, exposure, and hazards of drought. This study analyzed drought risk on a global scale with different RCP scenarios projected until the year 2099 with a focus on the variables population, precipitation, water resources, and temperature.