• 한국통신학회논문지
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• 제33권9C호
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• pp.652-660
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• 2008

어플리케이션에 맞춤화 된 다양한 임베디드 시스템은 리소스의 효율적인 관리를 위해 임베디드 OS의 종류와 버전에 맞는 디바이스 드라이버가 요구된다. 본 논문에서는 동일한 OS의 새로운 버전에 대해 확장성이 용이한 디바이스 드라이버 자동생성 시스템을 제시한다. 제안한 시스템에서는 특정 OS 고유의 디바이스 드라이버 구조를 템플릿으로 작성한 후 라이브러리화하며, 라이브러리에 저장된 템플릿을 기본골격으로 하여 시스템의 특성에 따른 코드를 추가하는 방법으로 디바이스 드라이버를 생성한다. 생성된 디바이스 드라이버를 커널에 등록하여 데이터 전송 시간을 비교한 결과 매뉴얼로 설계한 디바이스 드라이버에 비해 자동생성된 TFT-LCD 드라이버, USB 인터페이스 키보드 마우스 드라이버, 그리고 AC'97 컨트롤러 드라이버가 각각 경미한 증가를 보였다. 생성된 드라이버를 커널 컴파일 한 후의 코드 사이즈도 각각 경미한 증가를 보였다.

• Nuclear Engineering and Technology
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• 제48권5호
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• pp.1162-1173
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• 2016

In this paper, we describe a physicomathematical model of the processes that occur in a sodium circuit with a variable flow cross-section in the case of a water leak into sodium. The application area for this technique includes the possibility of analyzing consequences of this leak as applied to sodium-water steam generators in fast neutron reactors. Hydrodynamic processes that occur in sodium circuits in the event of a water leak are described within the framework of a one-dimensional thermally nonequilibrium three-component gas-liquid flow model (sodium-hydrogen-sodium hydroxide). Consideration is given to the results of a mathematical modeling of experiments involving steam injection into the sodium loop of a circulation test facility. That was done by means of the computer code in which the proposed model had been implemented.

• 전기학회논문지P
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• 제63권4호
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• pp.254-259
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• 2014

In this paper, we describe construction of a wind stabilization demo-site and effects of output power control of wind turbines for suppression of ramp rate using ESS (Energy Storage System). It is difficult to control the output power of distributed generator such as wind turbine which of variation is very large. If the large capacity wind farm be interconnected into power system may cause blackout due to Power Quality. For these reasons, the international standards such as Grid-Code is limited to less than 10 [%/min] of renewable energy ramp rate. The case of Korea, government actively conducts propagating large-scale renewable energy for green growth policy, to interconnecting more renewable energy into power system is necessary for stabilization technology. For these reasons, the POSCO consortium has constructed a wind stabilization demo-site that is configured as 500 [kWh] battery energy storage systems can output up to 3 [C-Rate] and two wind turbines rated 750 [kW]. In POSCO consortium, which implements various methods stabilizing output power of wind turbine such as smoothing, section firming and ramp control, we derive the results of long-term demonstration that can be controlled to satisfy to the international standard about ramp rate [%/kW] of wind turbine output power.

• Nuclear Engineering and Technology
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• 제47권6호
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• pp.700-711
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• 2015

Sodium-cooled fast breeder reactors use liquid sodium as a moderator and coolant to transfer heat from the reactor core. The main hazard associated with sodium is its rapid reaction with water. Sodium-water reaction (SWR) takes place when water or vapor leak into the sodium side through a crack on a heat-transfer tube in a steam generator. If the SWR continues for some time, the SWR will damage the surface of the defective area, causing it to enlarge. This self-enlargement of the crack is called "self-wastage phenomena." A stepwise numerical evaluation model of the self-wastage phenomena was devised using a computational code of multicomponent multiphase flow involving a sodium-water chemical reaction: sodiumwater reaction analysis physics of interdisciplinary multiphase flow (SERAPHIM). The temperature of gas mixture and the concentration of NaOH at the surface of the tube wall are obtained by a numerical calculation using SERAPHIM. Averaged thermophysical properties are used to assess the local wastage depth at the tube surface. By reflecting the wastage depth to the computational grid, the self-wastage phenomena are evaluated. A two-dimensional benchmark analysis of an SWAT (Sodium-Water reAction Test rig) experiment is carried out to evaluate the feasibility of the numerical model. Numerical results show that the geometry and scale of enlarged cracks show good agreement with the experimental result. Enlarged cracks appear to taper inward to a significantly smaller opening on the inside of the tube wall. The enlarged outer diameter of the crack is 4.72 mm, which shows good agreement with the experimental data (4.96 mm).

• 한국유체기계학회 논문집
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• 제16권4호
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• pp.35-43
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• 2013

Most of the nuclear power plants(NPPs) adopts pressure difference type flow meters such as venturi and orifice meters for the measurement of feedwater flow rates to calculate reactor thermal power. However, corrosion products in the feedwater deposits on the flow meter by fouling as operating time goes. These effects lead to severe errors in the flow indication and then determination of reactor thermal power. The averaging BDFT, which has developed by Yun et al., has a potentiality to minimize this problem thanks to its inherent measurement principle. Therefore, it is expected that the averaging BDFT can replace the venturi meter for the feedwater pipe of steam generator of NPPs. The present work compares the amplification factor, K, based on CFD calculation against the K obtained from experiments in order to confirm whether a commercial CFD code can be applicable to the evaluation of characteristic for the averaging BDFT. In addition to this, the simulations to take into account of fouling effect are also carried out by rough wall option. The results show that the averaging BDFT is a promising flow meter for the accurate measurement of flow rates in the fouling condition of the NPPs.

• 한국위성정보통신학회논문지
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• 제8권2호
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• pp.29-35
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• 2013

본 논문에서는 GPS L1 신호에 대한 기만의 종류 및 이를 검출하기 위한 방법에 대한 연구를 수행하고 GPS L1 신호에 대한 기만신호 검출 및 판단 알고리즘을 구현한 후 시뮬레이션을 통하여 성능을 분석하였다. 수신기의 동작 여부에 따라 기만과 재밍신호가 차이가 있으며 기만신호는 재밍신호와 달리 GPS 신호와 유사한 신호로 수신기를 공격하므로 기만 대상 수신기에서는 정상동작하는 것처럼 판단하게 되며 따라서 수신기에서 기만공격을 판단하기란 매우 어렵다. 기만신호 검출 및 판단 알고리즘의 성능을 검증하기 위하여 소프트웨어 기반의 기만신호/정상 GPS 신호생성기와 소프트웨어 기반의 수신기를 구현하였다. 본 논문에서 기만신호의 코드지연 및 도플러 주파수 변이에 따른 수신기의 DLL/PLL의 출력 오차를 확인하였다. 또한 수신기의 출력값인 의사거리, 신호세기, 항법해를 이용하여 기만신호 검출 및 판단 알고리즘을 구현하였으며 기만신호를 효율적으로 검출 및 판단할 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.835-842
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• 2014

Cutback control in a grid code is one of the functions of a wind power plant (WPP) that is required to support the system protection and frequency stability. When a cutback control command signal is delivered to the WPP from the system operator, the output of a WPP should be decreased to 20% of the rated power within 5 s. In this paper, we propose a dedicated cutback control algorithm of a WPP based on the ratio of the command power to the available power. If a cutback control signal is delivered, the algorithm determines the pitch angle for the cutback control and starts the pitch angle control. The proposed algorithm keeps the rotor speed at the speed before the start of the cutback control to quickly recover the previous output prior to the cutback control. The performance of the algorithm was validated for a 100 MW aggregated WPP based on a permanent magnet synchronous generator under various wind conditions using an EMTP-RV simulator. The results clearly shows that the proposed algorithm not only successfully reduces the output to the command power within 5 s by minimizing the fluctuation of the pitch angle, but also rapidly recovers to the output level before the cutback control.

• Nuclear Engineering and Technology
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• 제39권3호
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• pp.193-206
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• 2007

The Korea Atomic Energy Research Institute has developed an advanced fast reactor concept, KALIMER-600, which satisfies the Generation IV reactor design goals of sustainability, economics, safety, and proliferation resistance. The concept enables an efficient utilization of uranium resources and a reduction of the radioactive waste. The core design has been developed with a strong emphasis on proliferation resistance by adopting a single enrichment fuel without blanket assemblies. In addition, a passive residual heat removal system, shortened intermediate heat-transport system piping and seismic isolation have been realized in the reactor system design as enhancements to its safety and economics. The inherent safety characteristics of the KALIMER-600 design have been confirmed by a safety analysis of its bounding events. Research on important thermal-hydraulic phenomena and sensing technologies were performed to support the design study. The integrity of the reactor head against creep fatigue was confirmed using a CFD method, and a model for density-wave instability in a helical-coiled steam generator was developed. Gas entrainment on an agitating pool surface was investigated and an experimental correlation on a critical entrainment condition was obtained. An experimental study on sodium-water reactions was also performed to validate the developed SELPSTA code, which predicts the data accurately. An acoustic leak detection method utilizing a neural network and signal processing units were developed and applied successfully for the detection of a signal up to a noise level of -20 dB. Waveguide sensor visualization technology is being developed to inspect the reactor internals and fuel subassemblies. These research and developmental efforts contribute significantly to enhance the safety, economics, and efficiency of the KALIMER-600 design concept.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.19-26
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• 2020

Small nuclear reactor features higher power capacity, longer operation life than conventional power sources. It could be an ideal alternative of existing power source applied for special equipment for terrestrial or underwater missions. In this paper, a 25kWe heat pipe cooled reactor power source applied for multiple use is preliminary designed. Based on the design, a thermal-hydraulic analysis code for heat pipe cooled reactor is developed to analyze steady and transient performance of the designed nuclear reactor. For reactor design, UN fuel with 65% enrichment and potassium heat pipes are adopted in the reactor core. Tungsten and LiH are adopted as radiation shield on both sides of the reactor core. The reactor is controlled by 6 control drums with B₄C neutron absorbers. Thermoelectric generator (TEG) converts fission heat into electricity. Cooling water removes waste heat out of the reactor. The thermal-hydraulic characteristics of heat pipes are simulated using thermal resistance network method. Thermal parameters of steady and transient conditions, such as the temperature distribution of every key components are obtained. Then the postulated reactor accidents for heat pipe cooled reactor, including power variation, single heat pipe failure and cooling channel blockage, are analyzed and evaluated. Results show that all the designed parameters satisfy the safety requirements. This work could provide reference to the design and application of the heat pipe cooled nuclear power source.

• 한국정보통신학회논문지
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• 제12권7호
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• pp.1209-1217
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• 2008

본 논문에서는 $GF(2^m)$ 상에서 표준기저를 사용한 두 다항식의 곱셈을 비트-병렬로 실현하는 새로운 형태의 비트-병렬 곱셈기를 제안하였다. 곱셈기의 구성에 앞서, 피승수 다항식과 기약다항식의 곱셈을 병렬로 수행 한 후 승수 다항식의 한 계수와 비트-병렬로 곱셈하여 결과를 생성하는 VCG를 구성하였다. VCG의 기본 셀은 2개의 AND 게이트와 2개의 XOR 게이트로 구성되며, 이들로부터 두 다항식의 비트-병렬 곱셈을 수행하여 곱셈 결과를 얻도록 하였다. 이러한 과정을 확장하여 m에 대한 일반화된 회로의 설계를 보였으며, 간단한 형태의 곱셈회로 구성의 예를 $GF(2^4)$를 통해 보였다. 또한 제시한 곱셈기는 PSpice 시뮬레이션을 통하여 동작특성을 보였다. 본 논문에서 제안한 곱셈기는 VCG의 기본 셀을 반복적으로 연결하여 구성하므로, 차수 m이 매우 큰 유한체상의 두 다항식의 곱셈에서 확장이 용이하며, VLSI에 적합하다.