• 한국화재소방학회논문지
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• 제34권1호
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• pp.79-88
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• 2020

이 연구는 초고층건축물의 고층부에서 소방력의 공급의 효율성을 분석하고 이를 효율적으로 공급하는 방안을 제안하였다. 연구결과는 다음과 같다. 첫째, 화재감지는 외부에서 경보·진동·음성 등 화재경보의 다양화, 화재발생지점의 명확화 및 건축물 외부에도 화재층 표시를 통해 소방력 공급시간을 단축할 필요가 있다. 둘째, 신호통신은 무선통신보조설비의 설치대상을 강화하고, 중계기 설치를 보완하며, 다중통신망을 구성할 것을 제안하였다. 셋째, 행동결정은 인접건축물에서 도하의 방법으로 진압대원 및 소방장비를 공급하고, 일정 층마다 파괴가 용이한 유리창을 설치하며 식별표시도 필요하다. 넷째, 현장대응은 활강과 수직구조기법을 적용하여 소방장비의 공급 및 진압대원의 진입을 돕고 드론을 이용하여 소방장비를 공급한다. 마지막으로 충분한 소화액 제공은 헬리콥터와 인접한 건축물을 이용하여 소방용수를 공급한다.

• 한국태양에너지학회 논문집
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• 제36권5호
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• pp.73-89
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• 2016

To assure maximum economic benefits and the energy performance of solar water heating systems, the proper sizing of components and operating conditions need to be optimized. In recent years, a number of studies to design optimally solar water heating systems have been tried. This paper presents a design method for optimizing the various capacity-related and installation-related design variables based on life cycle cost using a genetic algorithm. The design variables considered in this study included the types and numbers of solar collector and auxiliary heaters; the types of storage tanks and heat exchangers; the solar collector slope; mass flow rates of the fluid on the hot and cold sides. The suggested method was applied for optimizing a solar water heating system for an elementary school in Seoul, South Korea. In addition, the effectiveness of the proposed optimization method was assessed by analyzing the obtained optimal solutions of six case studies, each of which was simulated with different solar fractions. It is observed that a trade-off between the equipment cost and the energy cost results in an optimal design that yields the lowest life cycle cost. Therefore, it could be helpful to apply the optimal solar water heating system by comparing the various design solutions obtained by using the optimization method instead of the engineer's experience and intuition.

• Corrosion Science and Technology
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• 제15권4호
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• pp.182-188
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• 2016

Significant piping wall thinning caused by Flow-Accelerated Corrosion (FAC) and Erosion-Corrosion (EC) continues to occur, even after the Mihama Power Station unit 3 secondary pipe rupture in 2004, in which workers were seriously injured or died. Nuclear power plants in many countries have experienced FAC and EC-related cases in steam cycle piping systems. Korea has also experienced piping wall thinning cases including thinning in the downstream straight pipe of a check valve in a feedwater pump line, the downstream elbow of a control valve in a feedwater flow control line, and failure of the straight pipe downstream of an orifice in an auxiliary steam return line. Cause analyses were performed by reviewing thickness data using Ultrasonic Techniques (UT) and, Scanning Electron Microscope (SEM) images for the failed pipe, and numerical simulation results for FAC and EC cases in Korea Nuclear Power Plants. It was concluded that the main cause of wall thinning for the downstream pipe of a check valve is FAC caused by water vortex flow due to the internal flow shape of a check valve, the main cause of wall thinning for the downstream elbow of a control valve is FAC caused by a thickness difference with the upstream pipe, and the main cause of wall thinning for the downstream pipe of an orifice is FAC and EC caused by liquid droplets and vortex flow. In order to investigate more cases, additional analyses were performed with the review of a lot of thickness data for inspected pipes. The results showed that pipe wall thinning was also affected by the operating condition of upstream equipment. Management of FAC and EC based on these cases will focus on the downstream piping of abnormal or unusual operated equipment.

• 전기학회논문지
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• 제62권4호
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• pp.523-528
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• 2013

In recent years, many efforts are increasingly being made to conserve the natural environment with enhanced emission standards and air quality standards. Also there are various methods necessary to be researched to minimize the emission of air pollutants. In particular, boilers of industrial facilities are major portions of the air pollution. The front duct which needs to be designed to reduce the gases to the electrostatic precipitator requires a bent tube, a reduction/extend tube and an auxiliary equipment, that is, a guide vane. This paper proposes an optimum design of the guide vane by a case study for electrostatic precipitator's flow uniformity. The operating conditions of this study are as follows: BMCR (Boiler Maximum Continuous Rate) and MGR (Maximum Guaranteed Rate) are 75%, 50%, and 30%; turbulent fluid dynamics model is based upon K-${\varepsilon}$ formulation. Presentation of the computed motion of particles is found to be quite useful to predict the precipitator performance by use CFD (Computational Fluid Dynamics).

• Structural Engineering and Mechanics
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• 제30권3호
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• pp.331-350
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• 2008

A framework for multi-platform analytical and multi-component hybrid (testing-analysis) simulations is described in this paper and illustrated with several application examples. The framework allows the integration of various analytical platforms and geographically distributed experimental facilities into a comprehensive pseudo-dynamic hybrid simulation. The object-oriented architecture of the framework enables easy inclusion of new analysis platforms or experimental models, and the addition of a multitude of auxiliary components, such as data acquisition and camera control. Four application examples are given, namely; (i) multi-platform analysis of a bridge with soil and structural models, (ii) multiplatform, multi-resolution analysis of a high-rise building, (iii) three-site small scale frame hybrid simulation, and (iv) three-site large scale bridge hybrid simulation. These simulations serve as illustrative examples of collaborative research among geographically distributed researchers employing different analysis platforms and testing equipment. The versatility of the framework, ease of including additional modules and the wide application potential demonstrated in the paper provide a rich research environment for structural and geotechnical engineering.

• 한국지열·수열에너지학회논문집
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• 제9권4호
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• pp.1-7
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• 2013

This study is to compare energy consumption of air-source, ground-source and dual-source heat pump systems during intermediate season using dynamic simulation. Ground-source heat pump has higher COP than that of air-source but requires additional power consumption of auxiliary equipment such as circulation pump. During intermediate season when the outdoor air temperature is favorable, total COP of air-source heat pump may be greater than that of ground-source when circulation pump power consumption is included. Dual-source heat pump which selects the more favorable heat source is compared with air-source only and ground-source only heat pumps for total power consumption. Results show that power consumption of dual-source heat pump is lower than that of ground-source only by 0.73%.

• 에너지공학
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• 제5권2호
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• pp.183-192
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• 1996

지역난방과 발전겸용의 열병합발전(CHP)시스템과 보조열원설비의 최적운전패턴을 결정하기 위한 수리적 모델을 구축하였다. 현실상황에 접근하여 사회전체, 전력회사 및 난방사업자 각각의 관점에서 최적화 모델이 구성되었다. CHP 시설과 보조열원의 운영권이 다른 경우, 최적운전패턴은 각 당사자의 목적함수에 따라 다르며, 여기에는 열거래요금이 결정적인 영향을 미친다. 본 논문에서는 사회전체 차원의 최적운전패턴을 도출하고, 이러한 패턴이 자율적으로 이루어지게 하는 열요금 구조를 제시하였다. 분석 결과, 사회적 관점에서의 최적화패턴에서는 보조열원의 활용이 중요하게 나타났으며, 현행의 균일 열요금 구조를 시간대별로 차등화된 열요금 구조로 변환할 경우, 자발적으로 시스템전체 차원의 최적화가 이루어질 수 있음이 발견되었다.

• 대한기계학회논문집A
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• 제26권3호
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• pp.452-460
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• 2002

The precision stage using a novel contact-free planar actuator based on magnetic farces, magnetized force and Lorentz farce, is suggested. In the promising magnetic structure, the mover is driven directly without any transmission mechanism, and doesn't need any auxiliary driver for its posture calibration. Then it is estimated that the proposed operating principle is very suitable for work requiring high accuracy and cleanness, or general-purpose nano-stage. In this paper, we discuss a driving principle of the planar system including the magnetic force generation mechanism, a framework for the force model, governing characteristics of the levitated plate, and a planar motion control of the constructed prototype. And experimental results are given to verify the derived theoretical model and a feasibility of the system.

• 한국지진공학회논문집
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• 제22권2호
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• pp.87-94
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• 2018

In this study, seismic performance of bushings and their connection parts was analyzed by performing shaking table tests for various types of bushings widely used as auxiliary equipment of main transformers in domestic substations. As a result of the seismic tests of five types of 154 kV bushings according to the manufacturers, all the bushings secured the structural integrity even at the acceleration of 1.4 g and it was found that leakage of insulating oil didn't occur. Also, the average acceleration amplification rate at the upper part of the bushings was about 2.5 to 3.0 times higher than the lower one. On the other hand, when a representative 345 kV bushing was subjected to the seismic test, the structural integrity was secured even at 1.0 g acceleration similar to the design earthquake load level, but in this test, leakage of insulating oil occurred. However, when a stiffener restricting the connection of the bushing is installed in the same 345 kV bushing, the displacement of the bushing connection is controlled and the stiffener prevent the oil from leaking even at the acceleration of the designed seismic level.

• 유공압시스템학회논문집
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• 제4권4호
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• pp.1-7
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• 2007

Flow rate is one of the important variables for precise motion control and detection of the faults and fluid loss in many hydraulic components and systems. But in many cases, it is not easy to measure it directly. The orifice area of a servo valve by which the fluid flows is one of key factors to monitor the flow rate. In this paper, we have constructed an estimation algorithm for the effective orifice area by using the model of a servo valve cylinder control system and Kalman filter algorithm. Without geometry information about the servo valve, it is shown that the effective orifice area can be estimated by using only displacement and pressure data corrupted with noise. And the effect of the biased sensor data and system parameter errors on the estimation results are discussed. The paper reveals that sensor calibration is important in accurate estimation and plausible parameter data such as oil bulk modulus and actuator volume are acceptable for the estimation without any error. The estimation algorithm can be used as an useful tool for detecting leakage, monitoring malfunction and/or degradation of the system performance.