• Nuclear Engineering and Technology
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• v.32 no.3
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• pp.227-234
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• 2000

It is known that loose parts in the reactor coolant system (RCS) cause serious damage to the systems. This paper is concerned with estimating the mass of a loose part in the steam generator of a nuclear power plant. We developed the mass estimation algorithm based on the Hertz theory in order to estimate the mass of the loose parts and applied the algorithm to the impact test data of YGN3. The mass estimation values were compared with real values in order to verify the algorithm. The result showed that the average error of the mass estimation value is less than 27%.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.234-237
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• 1997

In the Closing time in order to operate synchronous generators parallely, it is generated the asynchronous phenomena. These asynchronous phenomena give rise of the eddy current on the rotor. These eddy current are solved analytically for the Laplace' Equ. ${\nabla}^2{\widetilde{H}}=0$ in free space and for the Bullard's Equ. ${\nabla}^2{\widetilde{H}}$+${\sigma}_r{\mu}_r{\nabla}$${\times}$${\widetilde{\nu}}_r$${\times}$${\widetilde{H}}^{III}$=${\sigma}_r{\mu}_r{\frac{{\partial}H}{{\partial}t}}$ for the rotor by using each double Fourier series component of the 3D H-field

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.82-84
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• 2003

This paper presented a method to develop a relay model by the user-written model function of PSS/E. As for the voltage instability, although generator current limiters, transformer's tap-changers and dynamic loads have been considered as the dominant components, the protection system is also very important because it may influence the system's dynamic behaviour. Hence a distance relay model implemented with the suggested method was added, and then the operating characteristics of the distance relay under the voltage instability condition were investigated.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.509-512
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• 2008

본 논문에서는 원전 증기발생기세관 진단을 위한 와전류탐상의 전자기 수치해석을 수행하였다. 전자기적 특성을 해석하기 위하여 맥스웰 방정식을 이용하여 지배방정식을 유도하였고, 3차원 전자기 유한요소 프로그램인 OPERA 3D를 이용하여 전자기 수치 해석을 수행하였다. 신호해석을 위해 사용된 프로브의 종류는 배열와전류프로브이며, FBH 결함의 신호를 해석하였다. 결함의 깊이는 세관 두께의 40[%], 60[%] 및 100[%]로 하였다. 시험주파수는 100[kHz], 300[kHz], 400[kHz]를 사용하였고, 각각의 결함 및 시험주파수에 대한 결과를 비교 분석하였다. 본 논문의 결과는 앞으로 배열와전류프로브를 이용하여 원전 증기발생기세관 진단을 할 경우 신호 해석에 도움이 될 것으로 사료된다.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.57-61
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• 2008

A 1MW class HTS(High-Temperature Superconducting) synchronous motor has been developed. This motor was aimed to be utilized for industrial application such as large motors operating in large plants. The HTS field windings of the developed motor is cooled by way of Neon thermosiphon mechanism and the stator coil is cooled by water through hollow copper conductor. This paper describes performance test results of our motor, which was conducted at steady state in generator mode and motor mode.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.238-246
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• 2011

A 3-5 GHz UWB radar chip in 0.13 ${\mu}m$ CMOS process is presented in this paper. The UWB radar transceiver for surveillance and biometric applications adopts the equivalent time sampling architecture and 4-channel time interleaved samplers to relax the impractical sampling frequency and enhance the overall scanning time. The RF front end (RFFE) includes the wideband LNA and 4-way RF power splitter, and the analog signal processing part consists of the high speed track & hold (T&H) / sample & hold (S&H) and integrator. The interleaved timing clocks are generated using a delay locked loop. The UWB transmitter employs the digitally synthesized topology. The measured NF of RFFE is 9.5 dB in 3-5 GHz. And DLL timing resolution is 50 ps. The measured spectrum of UWB transmitter shows the center frequency within 3-5 GHz satisfying the FCC spectrum mask. The power consumption of receiver and transmitter are 106.5 mW and 57 mW at 1.5 V supply, respectively.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.145-151
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• 2005

The synthetic breaking test method was developed to evaluate the breaking performance of ultra high-voltage circuit breaker and made up of two independent circuits; current source circuit and voltage source circuit. In application of this test method, it is necessary to extend the arc of the test breaker. So, the new re-ignition system using VTGS (Vacuum Triggered Gap-Switch) was constructed to improve the efficiency and reliability of this test. In this re-ignition system, VTGS operates in high vacuum state of $5{\time}10^{17}$torr and control system consists of the triggering device and the air M-G (Motor-Generator). This re-ignition system showed the operating characteristics, such as delay time ($t_d$) and jitter time ($t_j$ not exceeding 5us and 1us respectively, and had the operating voltage of $25\~150kVdc$ at the gap distance of 24mm.

• The Korean Journal of Nuclear Medicine
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• v.3 no.1
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• pp.73-82
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• 1969

The newly developed diagnostic method with application of $^{113}Sn-^{113m}In$ cow system ($^{113}Sn:\;T\frac{1}{2}$ 118 days, $^{113m}In:\;T\frac{1}{2}$ 1.7 hrs, 390 Kev, Single ${\gamma}$) has the remarkable advantages such as increased diagnostic ability by single large dose administration of $^{113m}In$ with no subsequent radiation hazard and shortened examining time. We reformed the research of following scope with the use of developed $^{113}Sn-^{113m}In$ cow (25 mCi) generator: The sizes of particles produced under various conditions were investigated, and possibility for application to the scannings of various organs such as brain, liver, lung, bone marrow and blood pool etc. were studied. Results: $^{113m}InCl_3$ solution eluted from diluted HCl solution (pH 1.5) passed through $^{113}Sn-^{113m}In$ generator, and there can be produced various sized particles of colloidal indium. And there observed the state of distribution of $^{113m}In$ in each organ which showed many differences according to the particle sizes of colloidal indium. The results are stated as follows: 1. The adjustment of pH is the most important factor in making the desirable particle size of colloidal indium. The colloid for blood pool showed the highest level as 7.1%/gm blood, at pH 1.7, the colloid of pH 3.5 for liver scanning showed the highest level, 88.4%, in the liver, the colloid pH 6 showed the highest level, 3.1%, in the spleen, and the colloid of pH 11.0 showed the highest level, 85.3%/gm, in the lung. 2. The colloid for liver scanning made with NaCl-NaOH system showed the highest liver uptake at pH 7.2, and at either higher or lower pH than 7.2 showed decrease of liver uptake more or less. 3. The activity of $^{113m}In$ eluted through $^{113}Sn-^{113m}In$ generator indicated over 90% in the initial 4 ml, and particularly 88.1%-86.0% in the initial 2 ml. 4. The incubation time, tempertaure and mechanical irritation related to colloid formation and coating of colloid were not the definite condition of influence.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.573-582
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• 2010

In this paper, X-band transceiver for high resolution wideband SAR systems is designed and fabricated. Also as a technique for enhancing the performance, error compensation algorithm is presented. The transceiver for SAR system is composed of transmitter, receiver, switch matrix and frequency generator. The receiver especially has 2 channel mono-pulse structure for ground moving target indication. The transceiver is able to provide the deramping signal for high resolution mode and select the receive bandwidth for receiving according to the operation mode. The transceiver had over 300 MHz bandwidth in X-band and 13.3 dBm output power which is appropriate to drive the T/R module. The receiver gain and noise figure was 39 dB and 3.96 dB respectively. The receive dynamic range was 30 dB and amplitude imbalance and phase imbalance of I/Q channel was ${\pm}$0.38 dBm and ${\pm}$3.47 degree respectively. The transceiver meets the required electrical performances through the individual tests. This paper shows the pulse error term depending on SAR performance was analyzed and range IRF was enhanced by applying the compensation technique.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.5
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• pp.510-521
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• 2008

In the study, experiments are performed in the interaction region combined with wave and current to investigate the characteristics of local scour around submarine pipelines. Wave generator and current generator are used for the experiments and two current directions were used; co-direction and counter direction to the wave. The local scour depths around the pipeline are obtained according to the various pipe diameters(D), wave periods(T), wave heights(H), and current velocities(V). The experiments show that the maximum equilibrium local scour depth increases with pipe diameter, wave period, wave height, and current velocity. Using the experimental results, the correlations of scour depth and parameters such as Shields parameter($\theta$), Froude number(Fr), period parameter, Keulegan-Carpenter number(KC), Ursell number($U_R$), modified Ursell number($U_{RP}$) and ratio of velocities($U_{c}/(U_{c}+U_{m})$) are analyzed. In the interaction region combined with waves and currents, Froude number and Shields parameter are found the main parameters to cause the local scour around the submarine pipelines and this means that current governs the scour within any limits of the currents.