• 한국지진공학회논문집
• /
• 제8권2호
• /
• pp.19-25
• /
• 2004

일반적으로 운동방정식을 풀기 위해 많이 이용되는 선형근사모델은 계산이 용이한 반면에 큰 변형상태에서는 그 오차가 커지는 단점이 있다. 따라서 엄밀한 구조물의 응답해석을 위해서는 물성과 기하에 대한 비선형성을 고려해야 한다. 또한, 강과 같이 연성이 큰 재료는 소성 변형을 일으키면서 소산되는 에너지의 대부분이 열로 변하게 되며, 이 열은 열역학 제1 법칙과 2 법칙에 따라 다른 부분으로 전달된다. 이렇게 전달된 열은 온도를 상승시켜 재료의 강도를 약화시키는 역할을 하며, 이것이 다시 구조물의 응답에 영향을 미친다. 본 논문에서는 지진 등의 큰 하중을 받거나 화재로 인한 열 하중을 받는 강구조물의 비선형 대 변형 현상을 적절히 해석할 수 있는 열-탄소성 물성모델을 제안하고 3차원 유한요소해석을 수행하려다.

• Journal of Astronomy and Space Sciences
• /
• 제35권4호
• /
• pp.253-261
• /
• 2018

Korea Astronomy and Space Science Institute (KASI) has been developing the space optical and laser tracking (SOLT) system for space geodesy, space situational awareness, and Korean space missions. The SOLT system comprises satellite laser ranging (SLR), adaptive optics (AO), and debris laser tracking (DLT) systems, which share numerous subsystems, such as an optical telescope and tracking mount. It is designed to be capable of laser ranging up to geosynchronous Earth orbit satellites with a laser retro-reflector array, space objects imaging brighter than magnitude 10, and laser tracking low Earth orbit space debris of uncooperative targets. For the realization of multiple functions in a novel configuration, the SOLT system employs a switching mirror that is installed inside the telescope pedestal and feeds the beam path to each system. The SLR and AO systems have already been established at the Geochang station, whereas the DLT system is currently under development and the AO system is being prepared for testing. In this study, the design and development of the SOLT system are addressed and the SLR data quality is evaluated compared to the International Laser Ranging Service (ILRS) tracking stations in terms of single-shot ranging precision. The analysis results indicate that the SLR system has a good ranging performance, to a few millimeters precision. Therefore, it is expected that the SLR system will not only play an important role as a member of the ILRS tracking network, but also contribute to future Korean space missions.

• 자원ㆍ환경경제연구
• /
• 제18권4호
• /
• pp.587-635
• /
• 2009

본 연구의 목적은 Post-2012 의무부담에 대한 경제적 파급효과 분석을 위해 글로벌 동태연산기능일반균형모형(Global Dynamic Computable General Equilibrium Model : Global CGE Model)을 개발하는 것이다. 즉, 본 모형을 통해 우리나라의 의무부담 증가에 따라서 국제 배출권거래시장과 GNP, 소비, 투자, 수 출입 등 거시경제 변수들에 미치는 영향을 살펴보고자 한다. 기존 연구와는 달리 본 모형은 전 세계를 주요 경제그룹으로 나누어 분석한 글로벌모형으로서 주요 국가의 거시경제지표를 모두 반영하고 있으며, 이론적으로는 내생적 경제성장이론을 적용하고, 정책적으로는 배출권거래제도와 탄소세 등을 반영하고 있다. 특히 외생적인 기술진보를 모형에 반영하였다. 본 분석에 의하면, 온실가스 감축이 강화될수록 경제에 미치는 악영향이 커진다는 것을 알 수 있으며 거시경제지표 중에 무역수지의 감소가 가장 크게 나타나고 그 다음으로 투자 소비의 감소율이 큰 것으로 나타났다. 특히 산업별로는 에너지 의존도가 큰 에너지 다소비 업종일수록 온실가스 감축 영향이 크게 나타난다. 그리고 현재 개발도상국의 지위를 부여받고 있는 한국이 온실가스 감축 의무부담을 받으면 상대적으로 중국 등 다른 개발도상국들은 이득을 본다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 추계학술대회 초록집
• /
• pp.77.1-77.1
• /
• 2010

Durability problems of gas diffusion layer(GDL) is one of the important issues for accomplishing commercialization of proton exchange membrane fuel cell(PEMFC). GDL is strongly related to the performance of PEMFC because one of the main function of GDL is to work as a path of fuel, air and water. When the GDL is degraded, it causes water balance problems such as the flooding phenomenon. Thus, investigating the durability characteristics of the GDL is important and understanding the GDL degradation process is needed. In this study, the GDLs are degraded by carbon corrosion stress method which is the electrochemical degradation mode. To determine the effects of carbon corrosion of the GDL, 1.45 V of potential is imposed for 96 hours. In this manner, in the previous research, the structure between the substrate and the MPL is weaken. Further investigations are needed to clarify this phenomenon. Therefore, in this study, the carbon corrosion stress method is carried out with GDLs which have various MPL penetration levels and the effects of the MPL penetration level on the characteristics change of the GDL are analyzed. The changes in characteristics are measured with various properties of GDL such as weight, thickness and static contact angle. The degraded GDL shows loss of their properties.

• Environmental Analysis Health and Toxicology
• /
• 제24권4호
• /
• pp.287-292
• /
• 2009

Over the a few decades, the incidences of obesity and associated metabolic syndrome diseases have been increased dramatically and resulted in a global health crisis. Recent findings suggest endocrine disrupting chemicals (EDCs) as an obesogen, because they disrupt normal development and homeostatic controls over adipogenesis and energy balance in obesity. Furthermore, risk of cardiovascular disease and mortality is elevated among those who were obese during childhood. Thus, we focused on etiology of obesity in children and performed biological monitoring of bisphenol A (BPA), which is a broadly exposed EDC in environment. Study subjects were age and sex-matched obese and normal children in Seoul (N=52; age, $8.67{\pm}1.46$ years). Exposure levels of BPA were analyzed with HPLC/FLD as a conjugated form in urine. As results, ranges of urinary BPA were 0~54.38 ${\mu}g/g$ creatinine (median, 4.57 ${\mu}g/g$ creatinine). Levels of urinary BPA were 1.7 fold higher in the obese children than those in the controls (medians of obese and control children, 7.31 and 4.25 ${\mu}g/g$ creatinine, respectively, p=0.22). In the near future, enlarge scaled studies should be performed to confirm the risk of BPA for obesity.

• 한국초전도ㆍ저온공학회논문지
• /
• 제15권3호
• /
• pp.40-48
• /
• 2013

Cryoablation device is a surgical instrument to produce the cooling effect to destroy detrimental biological tissue by utilizing low temperature around 110 K. Usually, this device has the concentrated cooling region, so that it is suitable for concentrated and thick target. Accordingly, it is hard to apply this device for the target which is distributed and thin target. In this study, the design procedure of a closed-loop cryoablation device with multiple J-T expansion part is developed for the treatment of incompetent of great saphenous vein. The developed cyoablation device is designed with the analysis of 1-dimensional (1-D) bio-heat equation. The energy balance is considered to determine the minimum mass flow rate of refrigerant for consecutive flow boiling to develop the uniform cooling temperature. Azeotropic mixed refrigerant R410A and zeotropic mixed refrigerant (MR) of R22 ($CHClF_2$) and R23 ($CHF_3$) are utilized as operating fluids of the developed cryoablation device to form the sufficient temperature and to verify the quality of the inside of cryoablation probe. The experimental results of R410A and the zeotropic MR show the temperature non-uniformity over the range are $244.8K{\pm}2.7K$ and $239.8K{\pm}4.7K$ respectively. The experimental results demonstrate that the probe experiences the consecutive flow boiling over the target range of 200 mm.

• Korean Chemical Engineering Research
• /
• 제48권4호
• /
• pp.462-469
• /
• 2010

기체와 액체가 만나는 2상 공정들은 화학공학, 생명화학공학, 환경공학, 식품공학 등에 두루 존재한다. 위와 같은 공정의 최적화를 위해서는 거품의 움직임과 형태에 대한 정확한 파악이 필요하다. 액체 내부에서 거품의 움직임은 액체의 밀도, 점도, 표면장력과 거품의 크기와 속도에 영향을 받는다. 본 논문에서는 고점도 실리콘 오일 내부에서의 거품의 움직임과 형태를 관찰하였다. 또한 국외 논문 및 저서에서 정립된 거품의 에너지 수지 식, 항력계수와 변형계수를 이용하여 거품의 종말속도, 항력계수, 변형계수, 형태를 예측해 보고 이를 실험결과와 비교해 보았다. 실험 결과 거품의 속도는 점도가 낮을 경우가 더 빨랐고, 거품의 항력계수는 점도가 클 때 더 컸다. 거품의 형태는 점도가 클 때 덜찌그러진(구형에 가까운) 형태였다. 실험결과와 국외 논문 및 저서에서 정립된 항력계수와 변형계수를 이용한 예측결과를 비교해 본 결과 Batchelor가 제시한 이론이 가장 정확한 예측을 하는 것으로 나타났다. Batchelor가 제시한 거품의 에너지 수지식, 항력계수와 변형계수를 사용하여 예측한 거품의 2차원 측면 형태는 실험에서 관찰된 거품의 2차원 측면 형태와 유사하였다.

• 생물환경조절학회지
• /
• 제25권4호
• /
• pp.270-276
• /
• 2016

This study analysed overall heat transfer coefficient, heat transmission, and rate of indoor air heating provided by water curtain in order to determine the heat transfer characteristic of double-layered greenhouse equipped with a water curtain system. The air temperatures between the inner and outer layers were determined by the water flow rate and inlet water temperature. Higher water flow rate and inlet water temperature resulted in the increased overall heat transfer coefficient between indoor greenhouse air and water curtain. However, it was found that with higher levels of water flow rate and inlet water temperature, indoor overall heat transfer coefficient was converged about $10W{\cdot}m^{-2}{\cdot}^oC^{-1}$. The low correlation of overall heat transfer coefficient between water curtain and air within double layers was likely because the combination of greenhouse shape, wind speed and outdoor air temperature as well as water curtain affected the heat transfer characteristics. As water flow rate and inlet water temperature increased, the heat transferred into the greenhouse by water curtain also tend to rise. However it was demonstrated that the rate of heat transmission from water curtain into greenhouse with water curtain system using underground water was accounted for 22% to 28% for total heat lost by water curtain. The results of this study which quantify heat transfer coefficient and net heat transfer from water curtain may be a good reference for economical design of water curtain system.

• Nuclear Engineering and Technology
• /
• 제9권4호
• /
• pp.211-222
• /
• 1977

고준위 방사성 폐액의 고화처리 방법들 중 하나인 Vitrification Process의 연구로서 핵연료 재처리 과정에서 유출되는 가상적인 비활성폐액 중에 함유되어 있는 분열 및 부식 생성물들의 질산화물과 유리화시키기 위해 사용되는 첨가제의 열분해에 관하여 연구 조사되었다. 결정수를 갖고 있는 화합물들의 열분해시점은 75$^{\circ}C$이하였지만, 무수화합물들은 비교적 높은 분포를 보였다. 110$0^{\circ}C$까지 가열하여 얻어진 질량손실율을 이론치와 비교하였을 때, 대부분의 화합물은 릴치하거나 근사하였지만, Sodium, Cesium, Lithium, Ruthenium 등의 질산화물의 질량손실율은 이론치 보다 훨씬 높았다. 여기서 얻어진 결과는 고준위 폐액의 가소처리과정 또는 조사된 화합물들의 혼합에 따른 열분해를 분석하는데도 이용될 수 있을 것이다.

• KIEAE Journal
• /
• 제17권3호
• /
• pp.59-67
• /
• 2017

Purpose: As we are facing the global crisis from the climate change and energy depletion, urgent actions are needed to design a integrated sustainable building. This paper suggests that a sustainable design awards can stimulate for architects to bring the cutting-edge ideas into a realized building in comparison to green building certification system. AIA COTE Top 10 design awards, organized and run by AIA(American Institute of Architects) COTE(Committee on the Environment) from 1997, is analyzed as a case study. By researching the core of the AIA COTE Top 10 design awards system in terms of evaluation measures and submission requirements, meaningful suggestions were drawn to supplement Korea Green Building Awards system and to design and realize leading green buildings in Korea. Method: The comparison between AIA COTE Top 10 and Korea Green Building Design Awards was made in terms of evaluation measures, submission requirements, and green building certification systems. Result: This paper finally suggests the following three points in conclusion: 1) Set the standards of evaluation measures reflecting the three aspects(economy, environment, social) of sustainability, 2) Set the qualitative evaluation measures and corresponding submission requirements that can apply in the design awards in comparison to green building certification system, 3) Develop and balance submission requirements in response to evaluation measures to proceed systematic evaluation of the green buildings.