• Steel and Composite Structures
• /
• 제21권6호
• /
• pp.1327-1345
• /
• 2016

$Al_2O_3$/SiC particulate reinforced (Metal Matrix Composites) MMCs which were produced by using stir casting process, bending strength and hardening behaviour were obtained using an analysis of variance (ANOVA) technique that uses full factorial design. Factor variables and their ranges were: particle size $2-60{\mu}m$; the stirring speed 450 rpm, 500 rpm and the stirring temperature $620^{\circ}C$, $650^{\circ}C$. An empirical equation was derived from test results to describe the relationship between the test parameters. This model for the tensile strength of the hybrid composite materials with $R^2$ adj = 80% for the bending strength $R^2$ adj = 89% were generated from the data. The regression coefficients of this model quantify the tensile strength and bending strengths of the effects of each of the factors. The interactions of all three factors do not present significant percentage contributions on the tensile strength and bending strengths of hybrid composite materials. Analysis of the residuals versus was predicted the tensile strength and bending strengths show a normalized distribution and thereby confirms the suitability of this model. Particle size was found to have the strongest influence on the tensile strength and bending strength.

• 설비공학논문집
• /
• 제27권3호
• /
• pp.113-122
• /
• 2015

HVAC&R systems account for more than 50% of the energy consumption of buildings. The purpose of this study is to propose an optimal design method for the HVAC&R system and to examine the possibility for the energy conservation of a selected system. The energy demand for cooling and heating is determined by using TRNSYS and HEET. By an interaction between total system efficiency and cooling-to-heating load ratio, the optimal HVAC&R systems will be decided. The results showed that this proposed method is significantly capable of determining optimal system and building design for saving energy.

• Earthquakes and Structures
• /
• 제12권3호
• /
• pp.271-284
• /
• 2017

This paper presents a multimodal adaptive nonlinear static method of analysis that, differently from the nonlinear static methods suggested in seismic codes, does not require the definition of the equivalent Single-Degree-Of-Freedom (SDOF) system to evaluate the seismic response of structures. First, the proposed method is formulated for the assessment of r.c. plane frames and then it is extended to 3D framed structures. Furthermore, the proposed nonlinear static approach is re-elaborated as a displacement-based design method that does not require the use of the behaviour factor and takes into account explicitly the plastic deformation capacity of the structure. Numerical applications to r.c. plane frames and to a 3D framed structure with inplan irregularity are carried out to illustrate the attractive features as well as the limitations of the proposed method. Furthermore, the numerical applications evidence the uncertainty about the suitability of the displacement demand prediction obtained by the nonlinear static methods commonly adopted.

• Composites Research
• /
• 제12권6호
• /
• pp.43-52
• /
• 1999

본 연구에서는 복합재 구조물의 설계를 위한 동시공학 시스템을 개발하였다. 동시공학 시스템은 보다 짧은 제품 개발시간과 저렴한 생산비용으로 보다 우수한 품질을 갖는 제품생산을 위해 개발되었다. 본 연구에서는 동시공학 시스템의 개발을 위해 복합재 구조물의 설계와 해석에 관련된 다양한 상용 및 비 상용 소프트웨어들이 조사/수집 되었다. 동시공학 시스템에는 고전적층판이론과 유한요소해석을 이용한 복합재 구조물의 설계 및 해석 모듈,좌굴 및 좌굴후 거동해석 모듈,탄소-탄소 복합재의 열탄성 거동해석 모듈 및 전문가 시스템과 유전자 알고리즘을 이용한 복합재 구조물의 최적설계 모듈로 구성되어 있다. 또한 동시공학시스템은 소프트웨어들의 통합 및 관리를 위해 다중작업 및 그래픽 사용자 인터페이스의 구성이 가능한 마이크로 소프트사의 비주얼 $C++{^\circledR}$에 의해 구현되었다.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2008년도 하계학술발표대회 논문집
• /
• pp.540-545
• /
• 2008

An atrium has great potential in natural ventilation aided by buoyance effect. Architectural design of an atrium is very critical to maximize the effect. However, it is not easy of an atrium to have optimum shape for natural ventilation, from the aesthetic and economic point of view. Admitting this condition, we suggested a strategy to promote natural ventilation, which can be adopted only with small design change. At first, we installed BIPV on the top of an atrium to strengthen buoyancy effect, and combine forced ventilation by low pressure fan. To evaluate the performance of the measure, CFD simulation and Energy-Airflow analysis were achieved.

• 대한토목학회논문집
• /
• 제3권1호
• /
• pp.25-33
• /
• 1983

현행(現行) 콘크리트 표준시방서(標準示方書)에서 WSD 또는 USD로 설계(設計)되는 R.C. 기둥의 설계규준(設計規準)에서 보다 합리적(合理的)인 설계(設計)가 될 수 있는 신뢰성(信賴性) 설계규준(設計規準)을 제안(提案)하는 것이 본(本) 연구(硏究)의 핵심(核心)이다. Cornell의 MFOSM 이론(理論)에 의(依)해 R.C. 기둥 저항(抵抗)의 불확실량(不確實量) 산정(算定) 알고리즘을 유도(誘導)하여 저항(抵抗)의 불확실량(不確實量)을 산정(算定)했으며, 하중(荷重)의 불확실량(不確實量)은 우리의 실정(實情)을 고려(考慮)한 적절(適切)한 값을 선택(選擇)하여 신뢰성(信賴性) 해석(解析) 및 설계규준(設計規準)을 산정(算定)했다. 현행(現行) WSD와 USD 설계법(設計法)의 신뢰성(信賴性) 수준(水準)을 분석(分析)하고 외국(外國)의 경우와 비교(比較) 검토(檢討)함으로써, 우리 나라에 알맞는 목표신뢰성지수(目標信賴性指數) ${\beta}_0=4.0$을 택(擇)하여 LRFD 설계규준(設計規準)에 의(依)한 저항(抵抗)-하중계수(荷重係數)를 제안(提案)했다. 또한 철근(鐵筋)과 콘크리트의 허용응력(許容應力)을 산정제안(算定提案)했다. 본(本) 연구(硏究)에서 제안(提案)한 신뢰성(信賴性)을 설계규준(設計規準) 및 허용응력(許容應力)은 일정(一定)한 신뢰성(信賴性)을 주는 보다 합리적(合理的)인 설계(設計)가 되게 하므로 현행(現行) R.C. 기둥의 설계규준(設計規準)에 신뢰성(信賴性) 설계(設計) 개념(槪念)을 하는 것이 바람직하다고 본다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 하계학술대회 논문집 B
• /
• pp.571-576
• /
• 2002

Electromagnetic analysis has been made for the design of 3 MJ Compulsator (Compensated Pulsed Alternator, CPA) that will be used as the power supply system of the electrothermal-chemical launcher system. using finite element method with ANSYS/Emag. From the analysis results, it was possible to decide the excitation MMF and the rotor/stator size to obtain the desired output current. And using electromagnetic forces from the analysis results. the stresses on the components of 3 MJ CPA could be analyzed. The detailed design based on the analysis results has been made and the fabrication of 3 MJ CPA is in progress. Before assembling components into 3 MJ CPA. an experiment is being made to check the correspondence between analysis results and measurements.

• 한국수소및신에너지학회논문집
• /
• 제20권6호
• /
• pp.526-533
• /
• 2009

In this paper, cycle performance analysis of $CO_2-C_3H_8$ (R744-R290) cascade refrigeration system with internal heat exchanger is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree and gas cooling pressure and evaporating temperature in the propane (R290) low temperature cycle and the carbon dioxide (R744) high temperature cycle. The main results were summarized as follows : The COP of cascade refrigeration system of $CO_2-C_3H_8$ (R744-R290) increases with the increasing subcooling degree, but decreases with the increasing superheating degree. The COP of cascade refrigeration system increases with the increasing evaporating temperature, but decreases with the increasing gas cooling pressure. Therefore, superheating and subcooling degree, compressor efficiency, evaporating temperature and gas cooling pressure of $CO_2-C_3H_8$ (R744-R290) cascade refrigeration system have an effect on the COP of this system.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
• /
• pp.600-602
• /
• 2006

Some abnormal signals diagnostics and analysis through an important equivalent circuits modeling for passive elements under severe accident conditions have been performed. Unlike the design basis accidents, there are inherently some uncertainties in the instrumentation capabilities under the accident conditions. So, the circuit simulation analysis and diagnosis methods are used to assess instruments in detail when they give apparently abnormal readings as an accident alternative method. The simulations can be useful to investigate what the signal and circuit characteristics would be when similar to a variety of symptoms that can result from the environmental conditions such as high temperature, humidity, and pressure condition. In this paper, a new simulator through an analysis of the important equivalent circuits modeling under temperature accident conditions has been designed, the designed simulator is composed of the LabVIEW code as a main tool and the out-put file of the Multi-SIM code as an engine tool is exported to in-put file of the LabVIEW code. The procedure for the simulator design was divided into two design steps, of which the first step was the diagnosis method, the second step was the circuit simulator for the signal processing tool. It has three main functions which are a signal processing tool, an accident management tool, and an additional guide from the initial screen. This simulator should be possible that it could be applied a output signal analysis to some transient signal by variation of the resistance passive elements in the R-L-C equivalent circuit modeling under various degraded conditions in NPPs.

• Ecology and Resilient Infrastructure
• /
• 제7권4호
• /
• pp.308-319
• /
• 2020

본 논문은 경북 영천시 서문보에 최근 건설된 다기능 어도의 현장 적용성을 검토하기 위해 해석 변수를 R/C Slab (S1), R/C+S/C Slab (S2) 및 지하이동통로 규격 (가로 × 세로)을 1.4 × 0.2 m, 1.4 × 0.3 m, 1.4 × 0.6 m와 유속 0.8 m/s, 1.2 m/s, 1.6 m/s 으로 구분하여 해석한 결과 서문보 설계식 안전성을 평가하였다. 서문보의 설계식 보다 R/C+S/C Slab타입이 지하이동통로 출구부는 휨모멘트와 최대응력은 각각 16 - 33%, 24 - 32%, 측벽은 각각 17 - 33%, 20 - 36%, 상부슬래브인 경우도 19 - 33%, 9 - 28% 적게 나타났다. 따라서 최대응력과 휨모멘트가 R/C+S/C Slab 타입이 구조 안전성이 확보되는 것으로 나타났다. 따라서 지하통로는 휨모멘트와 최대 응력이 각각 14%, 18%, 측벽은 17%, 15% 상부슬래브는 16%, 11%의 보완이 요구되는 것으로 판단된다. 이러한 결과는 지하이동통로 규격이 서문보 규격과 동일한 1.4 × 0.3 m 일 때가 1.4 × 0.2 m, 1.4 × 0.6 m보다 안전성이 가장 유리한 것으로 확인되었다. 또한 해석 및 분석 결과를 근거로 서문보 규모의 다기능 어도 적용 시 기본 자료로 활용이 기대된다.