• Smart Structures and Systems
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• 제26권6호
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• pp.693-701
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• 2020

The conventional Kalman Filter (KF) provides a promising way for structural state estimation. However, the physical parameters of structural systems or models should be available for the estimation. Moreover, it is not applicable when the loadings applied to the structures are unknown. To circumvent the aforementioned limitations, a two-stage KF with unknown input approach is proposed for the simultaneous identification of structural parameters and unknown loadings. In stage 1, a modified observation equation is employed. The structural state vector is estimated by KF on the basis of structural parameters identified at the previous time-step. Then, the unknown input is identified by Least Squares Estimation (LSE). In stage 2, based on the concept of sensitivity matrix, the structural parameters are updated at the current time-step by using the estimated structural states obtained from stage 1. The effectiveness of the proposed approach is numerically validated via a five-story shearing model under random and earthquake excitations. Shaking table tests on a five-story structure are also employed to demonstrate the performance of the proposed approach. It is demonstrated from numerical and experimental results that the proposed approach can be used for the identification of parameters of structure and the external force applied to it with acceptable accuracy.

• Smart Structures and Systems
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• 제31권2호
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• pp.131-140
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• 2023

As well-known, the extended Kalman filter (EKF) is a powerful tool for parameter identification with limited measurements. However, traditional EKF is not applicable when the external excitation is unknown. By using least-squares estimation (LSE) for force identification, an EKF with unknown input (EKF-UI) approach was recently proposed by the authors. In this approach, to ensure the influence matrix be of full column rank, the sensors have to be deployed at all the degrees-of-freedom (DOFs) corresponding to the unknown excitation, saying collocated measurements are required. However, it is not easy to guarantee that the sensors can be installed at all these locations. To circumvent this limitation, based on the idea of first-order-holder discretization (FOHD), an improved EKF with unknown input (IEKF-UI) approach is proposed in this study for the simultaneous identification of structural parameters and unknown excitation. By using projection matrix, an improved observation equation is obtained. Few displacement measurements are fused into the observation equation to avoid the so-called low-frequency drift. To avoid the ill-conditioning problem for force identification without collocated measurements, the idea of FOHD is employed. The recursive solution of the structural states and unknown loads is then analytically derived. The effectiveness of the proposed approach is validated via several numerical examples. Results show that the proposed approach is capable of satisfactorily identifying the parameters of linear and nonlinear structures and the unknown excitation applied to them.

• 한국태양에너지학회 논문집
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• 제29권5호
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• pp.8-13
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• 2009

Feasibilities of the application of a micro gas turbine cogeneration system to a large size hospital building are studied by estimating energy demands and supplies. The energy demand for electricity is estimated by surveying and sorting the consumption records for various equipment and devices. The cooling heating, and hot water demands are further refined with TRNSYS and ESP-r to generate load profiles for the subsequent operation simulations. The operation of the suggested cogeneration system in conjunction with the load data is simulated for a time span of a year to predict energy consumption and gain profile. The simulation revealed that the thermal efficiency of the gas turbine is about 30% and it supplies 60% of the electricity required by the building. The recovered heat can meet 56% of total heating load and 67% of cooling, and the combined efficiency reaches up to 70%.

• 한국태양에너지학회 논문집
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• 제40권2호
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• pp.1-10
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• 2020

Korea government published renewable energy obligation policy that public building must be supplied some part of total consumption energy (2019: 27%, 2020: 30%). RETScreen is freely available global energy tool that developed by Canadian National Energy Laboratory to quantify energy saving to compare conventional system. This program can be performed energy modeling, cost analysis, greenhouse gas emission analysis and financial analysis. In this study, GSHP (Ground source heat pump) heating and cooling system were studied for the energy deliverly and ROI (Return On Investment) in an office building. Three cases were studied according to the number of HP (Heat pump) units for the 1,000㎡ office building located in Daejeon. Results indicated that the energy delivery of the case 1 (1 HP unit) covered 57% of the office building heating and cooling energy consumption. The case 2 (2 HP units) covered 87.8% and the case 3 (3 HP units) covered 96.8% of the office building energy consumption. The ROI of the case 1 indicated 7.9 years. While 8.2 years for the case 2 and 9.7 years for the case 3.

• 한국건축친환경설비학회 논문집
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• 제12권6호
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• pp.531-542
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• 2018

Building energy demands have highly risen in modern society; thus, It is necessary to reduce building energy demands especially commercial buildings adopting a curtain wall architecture. Curtain wall architectures have a high ratio of windows which is a vulnerable in heat insulations as cladding. In order to complement insulation performance of windows in these buildings, there are various methods adopted often such as installing blinds, wing wall and films. There are two suggestions of this paper. 1) WWR (Window-to-Wall Ratio) makes a impaction of energy demands in buildings. 2) Another one is an efficiency of blind systems which are installed in buildings in order to reduce cooling demands. It is also critical to make fundamental model for low-energy building construction by processing a lot of simulation As a result by this study, 1) an external blind system is more useful for reducing cooling energy demands rather than an internal blind system. 2) Buildings which have a large window require more amount of cooling demands. In case of WWR 45%, it needs more cooling energy rather than WWR 15% model's 3) Adopting blind system would reduce energy demands. WWR 45% model with external blind systems reduces about 4% of cooling energy demands compared to same model without any blind systems.4) it is necessary to study an efficiency of blind systems combined with renewable energy and it will be possible to reduce more energy demand in building significantly.

• KIEAE Journal
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• 제12권3호
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• pp.89-94
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• 2012

The international community is paying close attention to the climatic changes caused by the meteorological anomalies. In response to such phenomena, after the adoption of the United Nations Framework Convention on Climate Change in 1992, efforts to actively respond to the meteorological changes are proliferating all over the world; even in the Republic of Korea, the issue to tackle the meteorological changes has emerged as a top-priority national agenda. In the year of 2008, after the declaration of the low-carbon, green-growth paradigm by the government, the UNFCCC COP15 has announced a 30% reduction target of the emission of the greenhouse gases by 2020 as compared to the "Business As Usual, BAU" and has also confirmed, as a commitment plan to achieve reduction in the emission of greenhouse gases, the reduction target of greenhouse gases for all sectors, industries and years. (26.9% for buildings) Since the construction of the new apartment houses in the year of 2001, the "Building Energy Efficiency Rating", has been applied to newly constructed building complexes, built in 2010; the accumulated emission reduction has been evaluated at around 450,000toe and the accumulated carbon dioxide emission reduction is at $826,000tCO_2$ And through the prediction of these values under various scenarios (New construction, new construction / expansion of existing uses, when transferred to 1stgrade), the effects on the degree of reduction of greenhouse gases by the increased certification of the Building Energy Efficiency Rating are an alyzed and it is our aim to express the importance of the certification system capable of carrying out a quantitative evaluation of the building energy in order to establish the strategy to reduce the emission of carbon dioxide.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.166-167
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• 2015

Because of energy crisis at all around the world, there is many method and system which for improving energy efficiency has appeared in construction industry. And then, 20% of entire building energy loss is emissed to exterior of buildings, that is important to building's entire energy efficiency. So, many research has been conducted for imporve exterior energy efficiency and generally it called insulation of wall. Method for wall insulation can be classified interior system and exterior system which defined installation place of insulation board whether interior or exterior of structural wall. However, interior system has thermal problem such as thermal-bridge which can be necessarily occur condensation. and exterior system has constructional problem such as difficult to construction because exterior and finish work so expensive construction cost than other insulation method. Thus, sandwich insulation wall system has been appeared for solving these problems. Sandwich insulation system must using wall connecting things because both side walls is divided by center insulation. At this, Through the heat at wall connecter, it can be occured thermal-bridge and broken insulation board when under construction will be bring negative effect by reducing wall thickness and insulation deficit. At this study, we were compared previous sandwich insulation system and analysis these system's problem for develop the improving constructability and performance of sandwich insulation system.

• 에너지공학
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• 제26권4호
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• pp.92-99
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• 2017

국내에서는 국토부 7대 신산업, 산업부 8대 신산업으로 제로에너지빌딩이 지정되었으며, 건물외피의 단열성능 극대화와 건물 기기 효율향상 및 신재생 보급 확대를 위해 부처간 융합을 통해 제로에너지빌딩 보급 활성화 달성을 목표로 하고 있다. 국내에서 시행 중인 제로에너지빌딩 인증제에 해당되는 건물에너지효율등급 1++이상이 되는 건축물들의 부하(냉방, 난방, 급탕, 조명, 환기)들의 에너지소요량을 분석하여 대략적인 부하들의 수준을 파악하고 제로에너지빌딩 인증제 고도화를 위한 기초 자료로 활용될 수 있도록 하는 목적이 있다. 제로에너지빌딩 인증에 해당되는 건축물은 2017년 기준 61개 가량 되는 것으로 파악되고 있으며, 패시브 측면과 액티브 측면을 고려하여 5대 부하별 대략적인 기준 값과 1차 에너지소요량을 산정하였다. 부하기준 산정을 위한 데이터의 표본이 적어 명확한 기준이 된다고 보기는 어려우나 앞으로 제로에너지빌딩 인증 기준을 고도화하기 위해 다양한 방법들을 적용하여 해석할 필요성이 있다고 판단된다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.286-292
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• 2012

In recent years, building energy has received much attention and there are many support system to reduce building energy consumption. In addition, It is clear that encouraging to energy efficiency investments can be beneficial to our society, because of the energy supply instability and higher energy price in Korea. Nevertheless, ESCO business, represent the existing building energy retrofit business, hardly has not expanded in Korea. besides, in the case of existing building, it is more difficult to achieve the energy retrofit measures than new building, due to the existing buildings have attributes such as a long life and a lots of energy factor, etc. Therefore, for activate ESCO business and expand ESCO bussiness target to small-to-medium building, it is needed to optimization of retrofitting methods for existing small-to medium buildings in Korea. this research was to derive energy retrofit methods through the energy audit and analysis performed for a small-to-medium building located in Suwon, Korea.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.24-25
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• 2014

Up to now, most the fenestration industry is consisted of glazing and window frame in Korea. According to the Fenestration Energy Consumption Efficiency Rating System and Energy Saving Design Standards of Buildings, u-value of fenestration is defined as the value of calculation with glazing and frame. For this reason, when applying for a building permit, in most cases, the official approval test report of the set of windows and doors is used. Nevertheless, in windows construction progresses, most construction manager take delivery of the glazing and frame separately. For those reason, windows and doors are constructed regardless of the report of the Fenestration Energy Consumption Efficiency Rating System in most construction fields. From now on, the research of the connection method between reality of policy and reality of construction fields should be carried out.