• Geomechanics and Engineering
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• 제15권2호
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• pp.769-774
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• 2018

The growth of cities requires the construction of new tunnels close to the existing ones. Prediction and control of ground movement around the tunnel are important especially in urban area. The ground respond due to EPB (Earth Pressure Balance) pressure are investigated using the finite element method by ABAQUS in intersection of the triplet tunnels (Line 2, 3 and 4) of Mashhad Urban Railway in Iran. Special attention is paid to the effect of EPB pressure on the tunnel face displacement. The results of the analysis show that in EPB tunneling, surface settlement and face displacement is related to EPB pressure. Moreover, it is found that tunnel construction sequence is a great effect in face displacement value. For this study, this value in Line 4 where is excavated after line 3, is smaller than that line. In addition, the trend of the displacement curves are changed with the depth for all lines where is located in above and below, close to and above the centerline tunnel face for Line 2, 3 and 4, respectively. It is concluded that: (i) the surface settlement decreases with increasing EPB pressure on the tunnel face; (ii) at a constant EPB pressure, the tunnel face displacement values increase with depth. In addition, this is depended on the tunneling sequence; (iii) the trend of the displacement curves change with the depth.

• 대한전기학회논문지:전력기술부문A
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• 제55권10호
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• pp.426-432
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• 2006

This paper describes the concepts of Static Line Rating (SLR) and Dynamic Line Rating (DLR) and the computational methods to demonstrate them. Calculation of the line capacity needs the heat balance equation which is also used for computing the reduced tension in terms of line aging. SLR is calculated with the data from the worst condition of weather throughout the year. Even now, the utilization ratio is obtained from this SLR data in Korea. DLR is the improved method compared to SLR. A process for DLR reveals not only improved line ratings but also more accurate allowed line ratings based on line aging and real time conditions of weather. In order to reflect overhead transmission line aging in DLR, this paper proposes the method that considers the amount of decreased tension since the lines have been installed. Therefore, the continuous allowed temperature for remaining life time is newly acquired. In order to forecast DLR, this paper uses weather forecast models, and applies the concept of Thermal Overload Risk Probability (TORP). Then, the new concept of Dynamic Utilization Ratio (DUR) is defined, replacing Static Utilization Ratio (SUR). For the case study, the two main transmission lines which are responsible for the north bound power flow in the Seoul metropolitan area are chosen for computing line rating and utilization ratio. And then line rating and utilization ratio are analyzed for each transmission line, so that comparison of the present and estimated utilization ratios becomes available. Finally, this paper proves the validity of predictive DUR as the objective index, with simulations of emergency state caused by system outages, overload and so on.

• 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.

• 한국건설관리학회논문집
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• 제1권3호
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• pp.75-80
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• 2000

공간의 분할이 많은 건축공사에서는 반복적 특성으로 인해 공정계획상에 다수의 대안이 존재한다. 공사기간은 각 액티비티의 기간뿐 아니라 반복되는 액티비티의 배열방법에 의해서도 많은 영향을 받는다. 본 연구는 각 액티비티에 적정한 선행 액티비티를 할당함으로써 여유시간을 최소화하는 공정계획기법을 제시하는 것을 목적으로 진행되었다. Line of Balance 기법을 기본으로 하는 기존연구와는 달리 본 연구에서는 AON방식의 네트워크 기법을 기본으로 하여 공간과 자원의 두 축 사이에 액티비티를 배열하였다. 각 액티비티별로 자원과 공간의 양방향으로 가장 적절한 선행 액티비티를 검색하여 여유시간을 최소화한다. 본 연구에서 제시한 액티비티 배열방법을 공동주택공사 건설공사를 대상으로 적용한 결과, 액티비티 배열을 달리함에 따라서 다수의 대안이 존재함을 확인할 수 있었으며 그중 적정대안을 찾아낼 수 있었다. 본 기법은 공동주택공사와 같은 다수의 유사공간으로 구성된 건설공사의 공정 계획에 도움을 줄 수 있을 것으로 판단된다.

• 대한치과교정학회지
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• 제15권1호
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• pp.75-84
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• 1985

By observing the correlationships between the characteristics of the facial pattern and the methods of establishing the position of the lower central incisor to the five reference lines on the lateral roentgenocephalograms, the author tried to find the most useful method of them, the criteria of which were the independence of a variation according to facial patterns, the close relationships with soft tissue and lip balance, and the simple and consistent usefulness in clinical practice. The subject consisted of forty normal occlusions, forty class II div I malocclusions, forty class III malocclusions, ten treated claas II div 1 cases and ten treated class III cases, all were in 14-17 yrs of age. The findings of this study are as follows: 1. The position of the lower central incisor to EP, OP, MP and NB showed variations according to ANB, FMA, facial convexity and Holdaway angle. 2. The position of the lower central incise. to AP line (A-Pog) was not co..elated with ANB, FMA, facial convexity and Holdaway angle, so it can be used consistently, regardlesss of the facial pattern. 9. The lineal position of the incisal edge of the lower central incisor to AP line has a profound influence on harmonious soft tissue and lip balance.

• Journal of Information Processing Systems
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• 제13권5호
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• pp.1358-1371
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• 2017

Dynamic thermal rating (DTR) system is an effective method to improve the capacity of existing overhead line. According to the methodology based on CIGRE (International Council on Large Electric systems) standard, ampacity values under steady-state heating balance can be calculated from ambient environmental conditions. In this study, simulation analysis of relations between parameters and ampacity is described as functional dependence, which can provide an effective basis for the design and research of overhead transmission lines. The simulation of ampacity variation in different rating scales is described in this paper, which are determined from real-time meteorological data and conductor state parameters. To test the performance of DTR in different rating scales, capacity improvement and risk level are presented. And the experimental results show that the capacity of transmission line by using DTR has significant improvement, with low probability of risk. The information of this study has an important reference value to the operation management of power grid.

• Journal of Electrical Engineering and Technology
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• 제2권2호
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• pp.178-187
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• 2007

One important issue in power systems is dynamic instability due to loosing balance relation between electrical generation and a varying load demand that justifies the necessity of stabilization. Moreover, Power System Stabilizer (PSS) must have capability of producing appropriate stabilizing signals over a wide range of operating conditions and disturbances. To overcome these drawbacks, this paper proposes a new method for robust design of PSS by using an auto-tuning fuzzy control in combination with Real-Coded Genetic Algorithm (RCGA). This method includes two fuzzy controllers; internal fuzzy controller and supervisor fuzzy controller. The supervisor controller tunes the internal one by on-line applying of nonlinear scaling factors to inputs and outputs. The RCGA-based method is used for off-line training of this supervisor controller. The proposed PSS is tested in three operational conditions; nominal load, heavy load, and in the case of fault occurrence in transmission line. The simulation results are provided to compare the proposed PSS with conventional fuzzy PSS and conventional PSS. By evaluating the simulation results, it is shown that the performance and robustness of proposed PSS in different operating conditions is more acceptable

• 대한토목학회논문집
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• 제32권4D호
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• pp.357-366
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• 2012

기존의 품셈과 지방세법은 건설중장비가 수 년에 걸친 감가상각 대상임에도 불구하고, 물가지수를 제대로 반영하지 못하고 있다. 이에 본 연구에서는, 법인세법과 지방세법 및 기업회계기준서를 분석하여 국내 감가상각제도의 특징과 상각방법을 정리하여 제시하였고, 경제성 이론이 반영된 건설중장비 자본회수계수를 제시하였고, 정액법과 정률법을 사용하여 표준품셈을 기준으로 한 감가상각과 세법을 기준으로 한 감가상각 사례를 제시하였다. 개선방안으로는, 건설중장비의 자발적 사용기간 신청제도와 현행제도와의 관계를 설명하고 도입을 제안하였으며, 국내물가지수를 기초로 월단위 기계경비 감가상각율표를 개발하여 제공하였으며, 그 적용방안을 예시하였다. 또한, 제안한 방안의 장점과 단점을 분석하여 연구의 적용한계와 차후 개선방향도 제시해 보았다. 본 연구를 통해 품셈과 세법에 보다 합리적이고 객관적인 현실성을 반영할 수 있을 것으로 판단된다.

• 전기학회논문지
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• 제59권3호
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• pp.485-491
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• 2010

Total Transfer Capability (TTC) should be pre-determined in order to estimate Available Transfer Capability (ATC). Typically, TTC is determined by considering three categories; voltage, stability and thermal limits. Among these, thermal limits are treated mainly in this paper on the evaluation of TTC due to the relatively short transmission line length of Korea Electric Power Corporation (KEPCO) system. This paper presents a new approach to evaluate the TTC using the Dynamic Line Rating (DLR) for the thermal limit. Since the approach includes not only traditional electrical constraints but also real-time environmental constraints, this paper obtains more cost-effective and exact results. A case study using KEPCO system confirms that the proposed method is useful for real-time operation and the planning of the electricity market.

• 설비공학논문집
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• 제14권4호
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• pp.304-314
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• 2002

Performance analysis of the automotive air-conditioning system is conducted by using computer simulation, and performance tests are carried out by using the climate wind tunnel in order to verify simulation. Evaporator and condenser were modeled by using empirical correlation which was obtained from calorimeter data, and compressor was modeled by using map based method. The steady state thermodynamic conditions of refrigerant satisfying mass and energy balance were assumed in the simulation program for automotive airconditioning system. The system performance was analyzed by finite difference method until differential air enthalpy between evaporator inlet and outlet becomes converged. Simulation results are in good agreement with experimental results at most operating conditions. Variation of discharge temperature and pressure of compressor, outlet temperature of evaporator, cooling capacity, and COP were investigated in term of air volume flow rate for evaporator, compressor capacity, compressor speed, superheat of thermostatic expansion valve, and diameter of suction line.