• 한국추진공학회지
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• 제21권1호
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• pp.8-16
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• 2017

고체 추진기관이 노즐마개에 의해 외기와의 교환이 완벽히 차단된다면, 구조적 안정성은 제작초기 조건인 내부조성간의 잔류반응(Post Cure, Migration etc.), 그리고 자유공간 내의 산소(또는 산화방지제)와 습기(제습제)와의 반응에 종속된다. 이로부터 발생하는 혼합형 고체추진제의 기계적 특성은 매우 복잡하며, 추진기관은 발사직전까지 일교차/년교차의 끊임없는 열하중을 받게 된다. 본 연구에서는 고체 추진기관의 제조공정인 성형오븐에서 출고 후 저장안정화까지의 거동을 고체추진제의 열유변학적 단순특성을 적용하여 신속하게 산출할 수 있는 방법을 제시하였다. 이를 위해 온도제어 가능한 Endurance Test 장치를 고안 제작하였으며, 추가적으로 점진적 응력과 변형율 증가에 따른 비선형 특성도 검토한다.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권2호
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• pp.106-115
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• 2002

The performance of an inverter-driven water-to-water heat pump with an electronic expansion valve (EEV) was measured as a function of compressor frequency, load conditions, and EEV opening. Based on the test results, a controller using proportional integral (PI) feedback or PI feedforward algorithm was designed and tested to investigate capacity modulation and transient response control of the system. Although the relation between superheat and EEV opening of the heat pump showed nonlinear characteristics, a control gain obtained at the rated frequency was applicable to various operating conditions without causing large deviations. When the simple PI feedback control algorithm was applied, a large overshoot of superheat and wet compression were observed due to time delay effects of compressor frequency. However, applying PI feedforward control scheme yielded better system performance and higher reliability, compared to the PI feedback algorithm.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.21-24
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• 2005

Three dimensional circular braided Glass/Aramid hybrid fabric/epoxy resin composite was fabricated. FBG sensor was embedded along the braid yam in order to monitor the internal dimensional changes of the 3-D braid composite. The amount of cure and thermal shrinkage of epoxy resin was also determined using FBG sensor system. FBG sensors with different grating length were embedded and their response were compared. The thermo-optic coefficient of FBG sensor was measured by several preliminary experiments. The internal strain that measured by FBG sensor and electric strain gauge was compared during compressive test. The released residual strain of the fabricated tubular composite was estimated using cutting method. The internal strain of the composite was estimated using FBG sensor system, and the result was compared with the value from electric strain gauge. It was found that FBG sensor system is a very useful technique to investigate inside region of complicated structure.

• 전기학회논문지
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• 제59권3호
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• pp.614-622
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• 2010

The goal of this paper is to develope the control program based on model which can be applied to 1000MW class coal fired thermal power plant. 1000MW class power plant has the higher efficiency and lower cost because the steam conditions of the ultra super-critical process are higher than them of the previous power plants in temperature and pressure. The program includes the state variable controls which have the desired characteristics for the higher temperature and pressure. The program had been developed successfully using advanced process control. The simulation results using the new control program showed the better performance and safer control than them of the previous control program and we could verify the application possibility of the new program for the actual power plant through the load test, comparison, analysis and tuning.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.404-405
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• 2011

In this paper, we present basic modeling of Juju power system using PSCAD/EMTDC. In detail, models of bipolar HVDC system, power transmission line, basic thermal power plant, load, and wind farm have been developed for Jeju power system. For evaluating basic dynamic behavior, we tested the system with a simple scenario and the test result showed acceptable response.

• 한국자동차공학회논문집
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• 제5권4호
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• pp.179-189
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• 1997

Among aftertreatment devices which reduce exhaust gas of diesel engine, diesel oxidation catalyst(DOC) with high reduction efficiency for gaseous matter and particulate matter is now studied actively. In this study, a transient one-dimensional model developed to simulate the thermal and conversion characteristics of adiabatic monolithic converters operating under warm up conditions is presented. This model takes into account the gas solid heat and mass transfer, axial heat conduction, chemical reactions and the related heat release. The model has been used to analyze the transient response of an axisymmetric catalytic converter during a warm-up as a function of catalyst design parameters and operation conditions in order to observe their effects on the lightoff behaviour. The experimental test was carried out 2400 cc light diesel engine with DOC.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.477-480
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• 2007

Inlet fluid temperature of the BRE in the geothermal heat pump system depends on heat exchange rate between the refrigerant of the heat pump and the leaving fluid from the BRE. Because the outlet fluid temperature of the BHE varies with time, inlet fluid temperature has to vary with time. In this study, the module to calculate inlet fluid temperature is developed, which can consider the time-varying outlet fluid temperature and the heat exchange capacity of the heat pump. It is assumed that heat loss or gain of the leaving fluid from outlet to inlet of the BHE is negligible, except when the fluid contacts with the refrigerant of the heat pump. This module is combined with TOUGHREACT, a widely accepted three-dimensional numerical simulator for heat and water flow and geochemical reactions in geothermal systems and is applied to data analyses of the thermal response test.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.559-567
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• 2018

In this paper, we propose a new load forecasting method for smart air conditioning (A/C) based on the modified thermodynamics of indoor temperature and the unbiased finite memory estimator (UFME). Based on modified first-order thermodynamics, the dynamic behavior of indoor temperature can be described by the time-domain state-space model, and an accurate estimate of indoor temperature can be achieved by the proposed UFME. In addition, a reliable A/C load forecast can be obtained using the proposed method. Our study involves the experimental validation of the proposed A/C load forecasting method and communication construction between DR server and HEMS in a test bed. Through experimental data sets, the effectiveness of the proposed estimation method is validated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.102-105
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• 1993

The objective of this study is to solve the operation scheduling problem of plural battery energy storage systems (BESS), and to find useful intonation from its result. Unlike conventional energy storage system, BESS has on hardware characteristics such as high efficiency, fast-acting response and operational loss. Considering rate constraints of thermal unit power as well as hardware characteristics of BESS, the operation scheduling has an intricated problem. In order to solve this optimization problem, we use successive approximations dynamic programming. In two types of operation, the proposed algorithm is applied to test system. one is daily optimal operation, the other weekly optimal operation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2219_2220
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• 2009

The characteristics of the Superconducting Magnetic Energy Storage (SMES) system are faster response, longer life time, more economical, and environment friendly than other Uninterruptible Power Supply (UPS) using battery. Fast charge and discharge time of SMES system can provide powerful performance of improving power quality in the grid. In order to demonstrate the effectiveness of SMES, the authors make a 10kJ SMES system for connection with RTDS (Real Time Digital Simulator). Because the characteristics of superconducting magnet are very important in SMES system, the necessary items such as thermal characteristic, mechanical stress and protection circuit should be considered. In this paper, the authors experimented thermal characteristics of the 10kJ SMES system. The experiment was accomplished using a simulation coils made of aluminium. It has same dimension of the 10kJ class HTS SMES coil. The coil was cooled with GM (Gifford -McMahon) cryocooler through the OFHC (Oxgen Free High thermal Conductivity) conduction bar. The test results of cool down and heat loads characteristics of the simulation coils are described in detail.