• Nuclear Engineering and Technology
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• 제48권3호
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• pp.733-743
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• 2016

The purpose of this study is to present a rational depreciation method for a pyroprocess cost calculation. Toward this end, the so-called advanced decelerated depreciation method (ADDM) was developed that complements the limitations of the existing depreciation methods such as the straight-line method and fixed percentage of declining-balance method. ADDM was used to show the trend of the direct material cost and direct labor cost compared to the straight-line or fixed percentage of the declining-balance methods that are often used today. As a result, it was demonstrated that the depreciation cost of the ADDM, which assumed a pyroprocess facility's life period to be 40 years with a deceleration rate of 5%, takes up 4.14% and 27.74% of the pyroprocess unit cost ($781/kg heavy metal) in the $1^{st}$ and final years, respectively. In other words, it was found that the ADDM can cost the pyroprocess facility's capital investment rationally every year. Finally, ADDM's validity was verified by confirming that the sum of the depreciation cost by year, and the sum of the purchasing cost of the building and equipment, are the same.

• Structural Engineering and Mechanics
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• 제66권4호
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• pp.543-555
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• 2018

Fiber Reinforced Polymer (FRP), which has a high strength to weight ratio, are now regularly used for strengthening of deficient reinforced concrete (RC) structures. While various researches have been conducted on FRP strengthening, an area that still requires attention is predicting the debonding failure load of prestressed FRP strengthened RC beams. Application of prestressing increases the capacity and reduces the premature failure of the beams largely, though not entirely. Few analytical methods are available to predict the failure loads under flexure failure. With this paucity, this research proposes a method for predicting debonding failure induced by intermediate crack (IC) for prestressed FRP-strengthened beams. The method consists of a numerical study on beams retrofitted with prestressed FRP in the tension side of the beam. The method applies modified Branson moment-curvature analysis together with the global energy balance approach in combination with fracture mechanics criteria to predict failure load for complicated IC-induced failure. The numerically simulated results were compared with published experimental data and the average of theoretical to experimental debonding failure load is found to be 0.93 with a standard deviation of 0.09.

• Wind and Structures
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• 제8권2호
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• pp.89-106
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• 2005

For estimating the vortex excited vibrations of overhead transmission lines, the Energy Balance Principle (EBP) is well established for spans damped near the ends. Although it involves radical simplifications, the method is known to give useful estimates of the maximum vibration levels. For very long spans, there often is the need for a large number of in-span fittings, such as in-span Stockbridge dampers, aircraft warning spheres etc. This adds complexity to the problem and makes the energy balance principle in its original form unsuitable. In this paper, a modified version of EBP is described taking into account in-span damping and in particular also aircraft warning spheres. In the first step the complex transcendental eigenvalue problem is solved for the conductor with in-span fittings. With the thus determined complex eigenvalues and eigenfunctions a modified energy balance principle is then used for scaling the amplitudes of vibrations at each resonance frequency. Bending strains are then estimated at the critical points of the conductor. The approach has been used by the authors for studying the influence of in-span Stockbridge dampers and aircraft warning spheres; and for optimizing their positions in the span. The modeling of the aircraft warning sphere is also described in some detail.

• 설비공학논문집
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• 제15권5호
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• pp.360-371
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• 2003

The calculation of each unit cost of productions is very important for evaluating the economical efficiency and deciding the reasonable sale price. In the present, two methods of exergy costing on multiple energy systems are suggested to reduce the complexities of conventional SPECO method and MOPSA method and to improve the calculation efficiency of exergoeconomics. The suggested methods were applied to a gas-turbine cogeneration and the unit costs of the power and the steam energy were calculated as an example. The main points of our methods are the following three. First, one exergetic cost is applied to one cycle or system. Second, the suggested equations are the internal cost balance equation and the production cost balance equation. Third, necessary states in a system are only inlet and exit states of 1ha components producing energy.

• 한국태양에너지학회 논문집
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• 제33권6호
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• pp.77-84
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• 2013

Degree-day method is very simple but essential index to estimate heating and cooling energy demand in buildings. It has been neglected, however, for the simplicity so it is difficult to find any DB for south Korean cities. Even meteorological department of S. Korea doesn't report the data officially. In this study, current methods that are being used in many countries are investigated and used to calculate degree-days of 35 south Korean cities with 30 years(1981~2010) historical data. The calculation result indicates that the error among 4 major methods are dependent on how daily or hourly temperature are treated in the calculation and how balance point temperature is defined. The errors of the methods are no larger than 6% relative to hourly degree-day method.

• 물과 미래
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• 제29권4호
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• pp.119-129
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• 1996

여름기간 동안 두 다른 준건조 기지역에 위치한 소유역들(Lucky Hills 그리고 Kendall)로부터 eddy 상관을 기초로 한 에너지 수지와 물수지 방법 그리고 TDR 방법을 이용하여 매일의 토양 함수량이 측정되어졌으며, 그 두 다른 방법들로부터 측정되어지고 계산되어진 매일의 토양 함수량에 대한 비교가 있었다. 그 비교는 유역을 대상으로 하는 경우에 있어서 eddy상관을 이용한 에너지 수지와 물수지 방법 그리고 TDR 방법을 사용한 토양 함수량 특정 방법에 대한 정확돌알아보는데 유용하다. 토양 함수량을 측정하는 이 두 방법들로부터 구해진 회귀 사이의 유사도는 이 방법들 사이의 상관 정도를 알아보는 것에 의해서 설명되어졌다. 단순선형상관분석은 Lucky Hills 유역에서는 TDR 방법에 의해서 측정된 토양 함수량이 에너지와 물수지 방법에 의해서 측정된 토양 함수량의 58% 정도임을 나타냈고, 그리고 Kendall 유역에서는 63% 정도임을 나타내었다. 분포도와 상관분석 결과는, 소유역에서 토양 함수량 측정을 위한 두 방법들에 있어서 유의한 차이를 나타내지 않았다.

• Smart Structures and Systems
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• 제15권5호
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• pp.1311-1327
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• 2015

In this paper, we have applied a new class of approximate analytical methods called Variational Approach (VA) for high nonlinear vibration equations. Three examples have been introduced and discussed. The effects of important parameters on the response of the problems have been considered. Runge-Kutta's algorithm has been used to prepare numerical solutions. The results of variational approach are compared with energy balance method and numerical and exact solutions. It has been established that the method is an easy mathematical tool for solving conservative nonlinear problems. The method doesn't need small perturbation and with only one iteration achieve us to a high accurate solution.

• Architectural research
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• 제14권1호
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• pp.11-18
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• 2012

College of Architecture, Georgia Institute of Technology, Atlanta, GA, US Abstract The intermittent heating and cooling energy need calculation of the ISO 13790 monthly method was examined. The current ISO 13790 method applies a reduction factor to the continuous heating and cooling need calculation result to derive the intermittent heating and cooling for each month. This paper proposes a method for the intermittent energy need calculation based on the internal mean temperature calculation. The internal temperature calculation procedure was introduced considering the heat-balance taking into account of heat gain, heat loss, and thermal inertia for reduced heating and cooling period. Then, the calculated internal mean temperature was used for the intermittent heating and cooling energy need calculation. The calculation results from the proposed method were compared to the current ISO 13790 method and validated with a dynamic simulation using EnergyPlus. The study indicates that the intermittent heating and cooling energy need calculation method using the proposed model improves transparency of the current ISO 13790 method and draws more rational outcomes in the monthly heating and cooling energy need calculation.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.135-138
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• 2006

가스발생기 사이클 엔진시스템 설계를 입력값과 기본 요구값으로 나누어 설계 요구값을 만족하기 위한 설계변수 11개를 정의하였다. 이 11가지의 설계변수를 통하여 설계 요구값을 만족하기 위한 압력 유량 파워 균형 관계식 11개를 제시하였으며, Newton 방법을 이용하여 해를 찾는 프로그램을 제작하였다. 고안된 프로그램을 이용하여 가스발생기 사이클 엔진의 시스템설계를 수행하여 그 유효성을 입증하였다.

• KEPCO Journal on Electric Power and Energy
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• 제5권3호
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• pp.181-188
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• 2019

본 연구에서는 발전시스템의 설계 입출력변수들을 Heat & Mass balance 계산 solver 및 최적화 알고리즘과 연계하고 반복계산 과정을 자동화함으로써 기술 및 경제적 측면을 고려한 최적의 발전시스템 Heat & Mass balance 설계를 도출하는 최적설계 자동화 기법을 개발하였다. 그리고 이에 대한 효과를 분석하기 위하여 발전소 형식별 10종에 대하여 최적설계 기법을 적용한 결과, NPV 및 IRR에 대한 개선 효과를 기대할 수 있었다.