• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.11
• /
• pp.538-543
• /
• 2006

A high-Power continuous-wave (CW) ten-vane double-strapped magnetron oscillator has been investigated using three-dimensional (3D) particle-in-cell (PIC) numerical simulation code, MAGIC3D. The resonant modes and their resonant frequencies of the ten-vane strapped magnetron resonator were obtained to show a large mode separation near the ${\pi}$-mode. An electron cloud formed in an anode-cathode gap, called an interaction space was confined well enough to result in no leakage current. Five spokes were clearly observed in the electron cloud, which definitely ensured the ${\pi}$-mode oscillation in the ten-vane magnetron. Numerical simulations predicted that the saturated microwave output power measured at the coaxial output port was 5.41 kW at the microwave frequency of 893 MHz, corresponding to a power conversion efficiency of 72.6% when the external axial magnetic field was 1150 gauss and the electron beam voltage and current were 6 kV and 1.25 A, respectively.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.12 no.1
• /
• pp.24-33
• /
• 2012

This paper describes a multi-mode LDPC decoder which supports 19 block lengths and 6 code rates of Quasi-Cyclic LDPC code for Mobile WiMAX system. To achieve an efficient implementation of 114 operation modes, some design optimizations are considered including block-serial layered decoding scheme, a memory reduction technique based on the min-sum decoding algorithm and a novel method for generating the cyclic shift values of parity check matrix. From fixed-point simulations, decoding performance and optimal hardware parameters are analyzed. The designed LDPC decoder is verified by FPGA implementation, and synthesized with a $0.18-{\mu}m$ CMOS cell library. It has 380,000 gates and 52,992 bits RAM, and the estimated throughput is about 164 ~ 222 Mbps at 56 MHz@1.8 V.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.158.1-158
• /
• 2001

An algorithmic gray code analog-to-digital converter (ADC), which is based on gray coding, is proposed in this article. The realization method makes use of a MOS triangular function circuit to provide a high-speed operation and low accumulated error. The proposed ADC is simple, small in size and suitable for fabrication using a standard CMOS process. Simulation results showing the performances of the proposed circuit are also included.

• Electric Engineers Magazine
• /
• s.350
• /
• pp.21-25
• /
• 2011

전기설비에 접근하여 활선작업을 수행하는 과정에서 "안전조치, 작업공구, 먼지, 분진, 쥐, 절연" 등의 문제로 기인하는 단락사고가 발생하면 플라즈마(plasma) 아크 형태의 전기적 방전이 일어나므로, 아크 플래시 위험에 노출된 작업자는 심각한 화상은 물론 생명에 위험을 초래할 수 있다. 이러한 위험으로부터 근로자를 보호하기 위하여 IEEE Std. 1584에 수행절차와 방법에 대하여 상세히 해설하고 있고, NFPA 70E는 보호기준 등을 규정하고 있다. 국내에서도 이 기준 등을 참고하여 산업안전기준에 관한 규칙에 의거, 활선작업 및 활선근접작업에 관한 기술지침(KOSHA CODE E-3G-2005)과 난연성 전기 작업복 선정에 관한 기술지침(KOSHA CODE E-32-2006을 규정하고 있다. 그러나 국내에서는 외국 기업 일부를 제외하고는 아크 플래시 위험분석 업무를 실무에 적용하는 사례를 찾아보기 어렵다. 또한 적용 범위에 있어서도 난연성 전기 작업복 선정에 관한 기술지침을 600V 이상의 활선작업 및 활선근접 작업시만 착용하도록 한정한 것은 아크 플래시 위험에 대한 보호가 충분하지 않은 것으로 판단된다. 오히려 고압보다도 저압회로 고장 지점의 최소 단락전류에서 차단기의 동작시간이 지연되는 경우, 사고에너지를 더 증가시키기 때문에 위험성과 빈도는 높아질 수 있다 이와 관련하여 본문에서는 "아크 플래시 위험" 분석 및 평가방법에 대하여 살펴보기로 한다.

• Journal of ILASS-Korea
• /
• v.15 no.4
• /
• pp.170-176
• /
• 2010

This paper describes the grid-size dependency of the conventional Eulerian-Lagrangian method to spray characteristics such as spray penetration and SMD in modeling DME sprays. In addition, the reduction of the grid-size dependency of the present Gas-jet model was investigated. The calculations were performed using the KIVA code and the calculated results were compared to those of experimental result. The results showed that the conventional Eulerian-Laglangian model predicts shorter spray penetration for large cell because of inaccurate calculation of momentum exchange between liquid and gas phase. However, it was shown that the gas-jet model reduced grid-size dependency to spray penetration by calculating relative velocity between liquid and ambient gas based on gas jet velocity.

• International Journal of Reliability and Applications
• /
• v.9 no.1
• /
• pp.53-70
• /
• 2008

In this paper, we discuss the plethora of uses for the software package R, and focus specifically on its helpful applications in reliability data analyses. Examples are presented; including the R coding protocol, R code, and plots for various statistical as well as reliability analyses. We explore Kaplan-Meier estimates and maximum likelihood estimation for distributions including the Weibull. Finally, we discuss future applications of R, and usages of quantile regression in reliability.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1995.05a
• /
• pp.847-852
• /
• 1995

A shielding analysis for KSC-7, the shipping cask for transporting the 7 PWR spent fuel assemblies, has been carried out. Radiation source term has been calculated on spent fuel with burnup of 50,000 MWD/MTU and 1.5 years cooling time by ORIGEN2 code. The shielding calculation for the cask has been made by using MCNP4A code with continuous cross section data library from ENDF/B-V. As a result of neutron dose rate analysis, another shielding calculational model on spent fuel shipping cask was provided which is using the Monte Carlo method.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.470-480
• /
• 2008

After 1th line was built in 1974, the history of subway in Korea has been expended to 9th line which is under construction. It is time to prepare nation wide subway grounding system urgently according to the domestic electric standard that aligns to world wide standard by WTO/TBT treat (1995). Newly added grounding system to the fundamentally different system caused many problems. PSD(platform screen door) and other newly added equipment are also need grounding system. By the electrical code(established by Korea Electric Association), low voltage equipment(including grounding system) under 1,000V AC are in the process of change into IEC 60374. IEC 60364 standard will be added to the electrical code(established by Korea Electric Association) in 2007 and amended and after 3-5 years later, it will become a complete IEC 60364. So the purpose of this study is to compare the domestic rail road grounding system and suggest the standardized grounding system for the newly built subway.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05a
• /
• pp.169-174
• /
• 1998

An 1200-day time-dependent fuel-management for the transition from 37-element fuel to CANFLEX-NU fuel in a CANDU 6 reactor has been simulated to show the compatibility of the CANFLEX-NU fuel with the reactor operation. The simulation calculation were carried out with the RFSP code, provided by cell averaged hel properties obtained from the POWDERPUFS-V code. The refueling scheme for both fuels was an eight bundle shift art a time. The simulation results show that the maximum channel and bundle powers were maintained below the licence limit of the CANDU 6. This indicates that the CANFLEX-NU fuel bundle is compatible with the CANDU 6 reactor operation during the transition period.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.465-466
• /
• 2006

In this paper, novel analog duty cycle corrector (DCC) with a digital duty error detector is proposed. The digital duty error detector measures the duty error of the clock and converts it into a digital code. This digital code is then used to accurately correct the duty ratio by adaptively steering the charge-pump current. The proposed duty cycle corrector was implemented using an 80nm DRAM process with 1.8V supply voltage. The simulation result shows that the proposed duty cycle corrector improves the settling time up to $70{\sim}80%$ at 500MHz clock frequency for the same duty correction accuracy as the conventional analog DCC.