中高等學校 數學敎育課程의 連繫性에 관한 硏究 : 幾何學的 領域을 中心으로

김명수,이재돈,송현섭 대구대학교 부설 과학교육연구소 1992 과학교육 Vol.5 No.-

Suppression of NH3 and N2O emissions by massive urea intercalation in montmorillonite

Kim, Kwang Seop,Park, Man,Choi, Choong Lyeal,Lee, Dong Hoon,Seo, Young Jin,Kim, Chan Yong,Kim, Jong Su,Yun, Seok-In,Ro, Hee-Myong,Komarneni, Sridhar Springer-Verlag 2011 Journal of soils and sediments Vol.11 No.3

RADIAL UNIFORMITY OF NEUTRON IRRADIATION IN SILICON INGOTS FOR NEUTRON TRANSMUTATION DOPING AT HANARO

KIM MYONG-SEOP,LEE CHOONG-SUNG,OH SOO-YOUL,HWANG SUNG-YUL,JUN BYUNG-JIN Korean Nuclear Society 2006 Nuclear Engineering and Technology Vol.38 No.1

The radial uniformity of neutron irradiation in silicon ingots for neutron transmutation doping (NTD) at HANARO is examined by both calculations and measurements. HANARO has two NTD holes named NTD1 and NTD2. We have been using the NTD2 hole for 5 in. NTD commercial service, and we intend to use two holes for 6 in. NTD. The objective of this study is to predict the radial uniformity of 6 in. NTD at the two holes. The radial neutron flux distributions inside single crystal and noncrystal silicon loaded at the NTD2 hole are calculated by the VENTURE code. For NTD1, the radial distributions of the reaction rate for a 6 in. NTD with a neutron screen are calculated by MCNP, and measured by gold wire activation. The results of the measurements are compared with those of the calculations. From the VENTURE calculation, it is confirmed that the neutron flux distribution in the single crystal silicon is much flatter than that in the non-crystal silicon. The non-uniformities of the measurements for radial neutron irradiation are slightly larger than those of the calculations. However, excluding local dips in the measurements, the overall trends of the distributions are similar. The radial resistivity gradient (RRG) for a 5 in. silicon ingot is estimated to be about $1.5\%$. For a 6 in. ingot, the RRG of a silicon ingot irradiated at HANARO is predicted to be about $2.1\%$. Also, from the experimental results, we expect that the RRG would not be larger than $4.4\%$.

Development and characteristics of the HANARO neutron irradiation facility for applications in the boron neutron capture therapy field

Kim, Myong-Seop,Lee, Byung-Chul,Hwang, Sung-Yul,Kim, Heonil,Jun, Byung-Jin Institute of Physics in association with the Ameri 2007 Physics in medicine & biology Vol.52 No.9

<P>The HANARO neutron irradiation facility for various applications in the boron neutron capture therapy (BNCT) field was developed, and its characteristics were investigated. In order to obtain the sufficient thermal neutron flux with a low level of contamination by fast neutrons and gamma rays, a radiation filtering method was adopted. The radiation filter was designed by using a silicon single crystal, cooled by liquid nitrogen, and a bismuth crystal. The installation of the main components of the irradiation facility and the irradiation room was finished. Neutron beam characteristics were measured by using bare and cadmium-covered gold foils and wires. The in-phantom neutron flux distribution was measured for flux mapping inside the phantom. The gamma-ray dose was determined by using TLD-700 thermoluminescence dosimeters. The thermal and fast neutron fluxes and the gamma-ray dose were calculated by using the MCNP code, and they were compared with experimental data. The thermal neutron flux and Cd ratio available at this facility were confirmed to be 1.49 ? 10<SUP>9</SUP> n cm<SUP>−2</SUP> s<SUP>−1</SUP> and 152, respectively. The maximum neutron flux inside the phantom was measured to be 2.79 ? 10<SUP>9</SUP> n cm<SUP>−2</SUP> s<SUP>−1</SUP> at a depth of 3 mm in the phantom. The two-dimensional in-phantom neutron flux distribution was determined, and significant neutron irradiation was observed within 20 mm from the phantom surface. The gamma-ray dose rate for the free beam condition was expected to be about 80 cGy h<SUP>−1</SUP>. These experimental results were reasonably well supported by calculation using the facility design code. This HANARO thermal neutron facility can be used not only for clinical trials, but also for various pre-clinical studies in the BNCT field.</P>

DESIGN OF A NEUTRON SCREEN FOR 6-INCH NEUTRON TRANSMUTATION DOPING IN HANARO

Kim, Hak-Sung,Oh, Soo-Youl,Jun, Byung-Jin,Kim, Myong-Seop,Seo, Chul-Gyo,Kim, Heon-Il Korean Nuclear Society 2006 Nuclear Engineering and Technology Vol.38 No.7

The neutron transmutation doping of silicon (NTD), as a method to produce a high quality semiconductor, utilizes the transmutation of a silicon element into phosphorus by neutron absorption in a silicon single crystal. In this paper, we present the design of a neutron screen for a 6' Si ingot irradiation in the NTD2 hole of HANARO. The goal of the design is to achieve an even flat axial distribution of the resistivity, or $Si^{30}(n,{\gamma})Si^{31}$ reaction rate, in the irradiated Si ingot. We used the MCNP4C code to simulate the neutron screen and to calculate the reaction rate distribution in the Si ingot. The fluctuations in the axial distribution were estimated to be within ${\pm}2.0%$ from the average for the final neutron screen design; thus, they satisfy the customers' requirement for uniform irradiation. On the other hand, we determined the optimal insertion depths of the Si ingots by varying the critical control rod position, which greatly affects the axial flux distribution.

A Study on $He^+$ Ion Beam Extraction in the Duoplasmatron Ion Source

Myong-Seop KIM,Hae-iLL BAK Korean Nuclear Society 1991 Nuclear Engineering and Technology Vol.23 No.4

각확산도가 작은 $He^+$ 이온빔 인출전류를 최대로 얻기 위하여 Duoplasmatron 이온원의 동작특성을 조사하였다. 이온원의 기체압력, 아크전류. 전자석 전류, 인출전압등을 변화시키면서 인출되는 $He^+$ 이온빔 전류의 변화를 관찰하였다. 열음극으로는 Ni망위에 BaO와 SrO의 혼합물을 코팅한 산화물 필라멘트를 사용하였으며, 그것의 평균수명은 약 100시간이었다. 인출전류는 아크전류에 선형적으로 비례했다 이온원 전자석전류를 증가시킴에 따라 인출전류는 증가하였지만 빔의 각확산도가 커졌다. 최대의 인출전류는 0.084 Torr의 이온원 압력에서 얻어졌다. 인출전류는 이론에서와 마찬가지로 인출전압의 3/2승에 비례하였다. 5.72 kV의 인출전압에서는 최적인출조건하에서 50 $\mu$A의 인출전류가 얻어졌다. The operational characteristics of the duoplasmatron ion source are investigated in order to obtain the maximum achievable extraction current of the $He^+$ ion beam with the small divergence. Under the variations of the gas pressure, the arc current, the magnet current and the extraction voltage of the ion source, the change of the extracted $He^+$ ion beam current is observed. An oxide filament, the mixture of BaO and SrO coated on Ni meshes, is used as the hot cathode, and its average lifetime is about 100 hours. The extraction current is linearly proportional to the arc current. As the magnet current of the ion source is increased, the extraction current increases, but the beam divergence becomes larger. The maximum extraction current is obtained at the source pressure of 0.084 Torr. The extraction current is proportional to the extraction voltage raised to the power of 3/2 as estimated from theory. At the extraction voltage of 5.72 kV, the maximum extraction current of 50 $\mu$A is obtained under the optimized extraction condition.

Measurements of In-phantom Neutron Flux Distribution at the HANARO BNCT Facility

Kim Myong Seop,Park Sang Jun,Jun Byung Jin Korean Nuclear Society 2004 Nuclear Engineering and Technology Vol.36 No.3

In-phantom neutron flux distribution is measured at the HANARO BNCT irradiation facility. The measurements are performed with Au foil and wires. The thermal neutron flux and Cd ratio obtained at the HANARO BNCT facility are $1.19{\times}10^9\;n/cm^{2}s$ and 152, respectively, at 24 MW reactor power. The measured in-phantom neutron flux has a maximum value at a depth of 3 mm in the phantom and then decreases rapidly. The maximum flux is about $25\%$ larger than that of the phantom surface, and the measured value at a depth of 22 mm in the phantom is about a half of the maximum value. In addition, the neutron beam is limited well within the aperture of the neutron collimator. The two-dimensional in-phantom neutron flux distribution is determined. Significant neutron irradiation is observed within 20 mm from the phantom surface. The measured neutron flux distribution can be utilized in irradiation planning for a patient.

Amplification of ENSO effects on Indian summer monsoon by absorbing aerosols

Kim, Maeng-Ki,Lau, William K. M.,Kim, Kyu-Myong,Sang, Jeong,Kim, Yeon-Hee,Lee, Woo-Seop Springer-International 2016 Climate dynamics Vol.46 No.7

<P>In this study, we present observational evidence, based on satellite aerosol measurements and MERRA reanalysis data for the period 1979-2011, indicating that absorbing aerosols can have strong influence on seasonal-to-interannual variability of the Indian summer monsoon rainfall, including amplification of ENSO effects. We find a significant correlation between ENSO (El Nino Southern Oscillation) and aerosol loading in AprilMay, with La Nina (El Nino) conditions favoring increased (decreased) aerosol accumulation over northern India, with maximum aerosol optical depth over the Arabian Sea and Northwestern India, indicative of strong concentration of dust aerosols transported from West Asia and Middle East deserts. Composite analyses based on a normalized aerosol index (NAI) show that high concentration of aerosol over northern India in April-May is associated with increased moisture transport, enhanced dynamically induced warming of the upper troposphere over the Tibetan Plateau, and enhanced rainfall over northern India and the Himalayan foothills during May-June, followed by a subsequent suppressed monsoon rainfall over all India, consistent with the elevated heat pump (EHP) hypothesis (Lau et al. in Clim Dyn 26: 855-864, 2006. doi: 10.1007/s00382-006-0114-z). Further analyses from sub-sampling of ENSO years, with normal (<1-sigma), and abnormal (>1-sigma) NAI over northern India respectively show that the EHP may lead to an amplification of the Indian summer monsoon response to ENSO forcing, particularly with respect to the increased rainfall over the Himalayan foothills, and the warming of the upper troposphere over the Tibetan Plateau. Our results suggest that absorbing aerosol, particular desert dusts can strongly modulate ENSO influence, and possibly play important roles as a feedback agent in climate change in Asian monsoon regions.</P>

Enhanced surface warming and accelerated snow melt in the Himalayas and Tibetan Plateau induced by absorbing aerosols

Woo-Seop Lee,Maeng-Ki Kim,William K M Lau,Kyu-Myong Kim,Sung Kim 한국기상학회 2010 한국기상학회 학술대회 논문집 Vol.2010 No.4

Physical Parameter-Based SPICE Models for InGaZnO Thin-Film Transistors Applicable to Process Optimization and Robust Circuit Design

Dae Hwan Kim,Yong Woo Jeon,Sungchul Kim,Yongsik Kim,Yun Seop Yu,Dong Myong Kim,Hyuck-In Kwon IEEE 2012 IEEE electron device letters Vol.33 No.1

<P>In this letter, we show that the physics-based equation that was derived for amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) in our previous work can be successfully incorporated into the SPICE model via Verilog-A. The proposed model and extracted SPICE parameters successfully reproduce the measured current-voltage characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs and the load line diagram of a-IGZO TFT inverters. The main advantage of our model is that each parameter has its physical meaning and most of them can be related with the fabrication conditions of AOS TFTs. To show the advantage of the proposed models and extracted SPICE parameters more clearly, we investigate the effect of ionized donor concentration (<I>N</I><SUB>D</SUB><SUP>+</SUP>) on the inverter circuit operation and determine the optimum value of <I>N</I><SUB>D</SUB><SUP>+</SUP> and device dimensions considering the tradeoff between the power consumption and the output swing in a-IGZO inverters. The proposed physics-based SPICE model via Verilog-A is expected to play a significant role in the process optimization and circuit design with AOS TFTs.</P>