• Proceedings of the KWS Conference
• /
• 2007.11a
• /
• pp.82-84
• /
• 2007

• Progress in Medical Physics
• /
• v.26 no.2
• /
• pp.87-92
• /
• 2015

The gated RapidArc may produce a dosimetric error due to the stop-and-go motion of heavy gantry which can misalign the gantry restart position and reduce the accuracy of important factors in RapidArc delivery such as MLC movement and gantry speed. In this study, the effect of stop-and-go motion in gated RapidArc was analyzed with varying gating window time, which determines the total number of stop-and-go motions. Total 10 RapidArc plans for treatment of liver cancer were prepared. The RPM gating system and the moving phantom were used to set up the accurate gating window time. Two different delivery quality assurance (DQA) plans were created for each RapidArc plan. One is the portal dosimetry plan and the other is MapCHECK2 plan. The respiratory cycle was set to 4 sec and DQA plans were delivered with three different gating conditions: no gating, 1-sec gating window, and 2-sec gating window. The error between calculated dose and measured dose was evaluated based on the pass rate calculated using the gamma evaluation method with 3%/3 mm criteria. The average pass rates in the portal dosimetry plans were $98.72{\pm}0.82%$, $94.91{\pm}1.64%$, and $98.23{\pm}0.97%$ for no gating, 1-sec gating, and 2-sec gating, respectively. The average pass rates in MapCHECK2 plans were $97.80{\pm}0.91%$, $95.38{\pm}1.31%$, and $97.50{\pm}0.96%$ for no gating, 1-sec gating, and 2-sec gating, respectively. We verified that the dosimetric accuracy of gated RapidArc increases as gating window time increases and efforts should be made to increase gating window time during the RapidArc treatment process.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.92-92
• /
• 2010

전북대학교에서는 우리나라 최초로 0.4 및 2.4 MW 급 초음속 열플라즈마 시험 시설 구축사업을 진행하고 있으며, 이를 이용한 응용 분야 별 선행연구를 수행하고 있다. 구축 시험 시설의 핵심장치인 MW 급 대출력 초음속 열플라즈마 발생기로는 양극과 음극 사이에, 전기적으로 절연된 도넛 형태의 간극을 다수 삽입하여 아크 길이를 늘림으로써, 플라즈마 출력을 비례하여 높일 수 있는 Segmented 형 아크 직류 토치를 사용하고자 하며, 제작을 위해 설계 중인 토치는 0.4 및 2.4 MW 출력에 대해, 마하 2 이상의 초음속 유동에서 각각 13 및 20 MJ/kg 이상의 플라즈마 비엔탈피 구현을 목표로 하고 있다. 특히, 이와 같은 고엔탈피 초음속 유동의 달성은 0.4MW 급의 경우엔 공기유량 0.01 kg/s 이상에서, 2.4 MW 급의 경우엔 0.05 kg/s 이상에서 10Torr 이하의 진공과 투입된 MW 규모의 열량을 지속적으로 유지 및 제거할 수 있는 시설이 있어야 구현 가능하므로 이를 위한 건축과 지원시설 구축을 동시에 진행하고 있다. 본 발표에서는 0.4 MW 급 초음속 열플라즈마 시험 시설을 중심으로, 상기 MW 급 Segmented 형 아크 직류토치와 이를 구동하기 위한 대출력 초음속 열플라즈마 시험 시설에 대해 그 동안 전북대학교에서 진행되어 온 개념설계 내용을 소개하고자 한다. 덧붙여, 최근 본 사업단에서 선행 연구 중인 고엔탈피 초음속 열플라즈마 진단 계측 기법과 향후 응용분야 및 핵심 연구개발 과제 등에 대한 간략한 소개도 함께 하고자 한다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.5 no.4
• /
• pp.3-7
• /
• 1991

This paper proposes a simplifying model for the calculation of the radiant flux and radiation energy in an RD(Radiation Dominated) arcplasma. Defects of the previous models are that the radiant flux and radition energy must be numerically solved by the three dimensional integration, and these calculations demand enormous computing time. These attribute to the global properties of radiation transfer. This paper suggests a simple calculation technique of radiation characteristics by considering the relation between the plasma states and the radiation transfer process and by the systematic tabulation of the relation.

• Journal of Welding and Joining
• /
• v.14 no.6
• /
• pp.81-92
• /
• 1996

This study is to compare the weldability of Zircaloy-4 end cap of nuclear fuel pin using by GTA and Nd :YAG LB. The welding parameters which affect bead width and penetration depth have been investigated. The effect of joint geometry of end cap for GTAW and LBW has been studied and optimum conditions of Zircaloy-4 endcap welding have been found. Microstructures and microhardness of GTA and LB welded zones have been also compared.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.8 no.1 s.20
• /
• pp.5-13
• /
• 2005

In order to evaluate the credibility of the welded joint design for combat vehicle using A12519, the numerical analysis for the joint model has been studied and the results are compared with the experimental works by the impact projectiles. The numerical approach using LS-DYNA involves the process of the crack initiation and propagation as well as the applications of the failure criteria for both the ductile and brittle failures. The good agreement between the numerical and experimental works are proved.

• Journal of Korean Society of Steel Construction
• /
• v.28 no.5
• /
• pp.303-312
• /
• 2016

Many researches on the application of stainless steels as structural steels have been performed thanks to their material properties such as superior ductility and corrosion resistance. Ferritic stainless steels(STS430) with little or no nickel have been used increasingly in building structure because it is inexpensive compared to austenitic stainless steels(STS304) with nickel, but provide performances similar to the austenitic stainless steel. This paper deals with block shear fracture behavior of base metal in stainless steel welded connection. Although the block shear fracture behavior for welded connection due to stress triaxiality is different from that of bolted connection, the block shear strength of welded connection in current design specifications has been predicted based on that of bolted connection. The main parameters are weld length and welding process(Arc and TIG welds). The ultimate strengths of TIG welded specimens were higher than those of arc welded specimens and current design predictions by AISC, EC3 etc. were compared with test strengths.

• Applied Chemistry for Engineering
• /
• v.22 no.1
• /
• pp.31-36
• /
• 2011

Tetrafluoromethane ($CF_4$) has been used as the plasma etching and chemical vapor deposition (CVD) gas for semiconductor manufacturing processes. However, the gas need to be removed efficiently because of their strong absorption of infrared radiation and the long atmospheric lifetime which cause global warming effects. A waterjet gliding arc plasma system in which plasma is combined with the waterjet was developed to effectively produce OH radicals, resulting in efficient destruction of $CF_4$ gas. Design factors such as electrode shape, electrode angle, gas nozzle diameter, electrode gap, and electrode length were investigated. The highest $CF_4$ destruction of 93.4% was achieved at Arc 1 electrode shape, $20^{\circ}$ electrode angle, 3 mm gas nozzle diameter, 3 mm electrode gap and 120 mm electrode length.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.242-247
• /
• 2011

본 연구는 한국형 Reach File을 개발하기 위한 선행 연구로써 한국형 Reach File의 필수 구성요소 중 하나인 속성을 설계하는 것을 목표로 하였다. 이를 위해 우선 미국 Reach File 구축 사례를 검토하였고, 특히 최종 버전인 RF3(Reach File version 3)의 속성 내역을 정리하여 설계에 참조하였다. 국내 TMDL 업무 분석을 수행하여 업무 활용 측면에서 요구되는 속성도 모델링을 통해 속성 설계에 반영하였으며, 아울러 아크-노드 모델(Arc-node model) 기반의 네트워크 형식의 공간자료를 구축하는 것을 가정하여 네트워크 분석에도 활용이 가능하도록 선형 및 점형 도형자료 간 위상관계도 속성 설계에 반영하였다. 연구 결과에서 한국형 Reach File의 속성은 '위상(topology)', '위치(location)', '주제(theme)'의 세 가지 대분류에 따라 모델링되었으며, 각 분류에 따라 세부 속성이 정의되었다. 고유 식별자를 포함하여 선형 도형자료의 경우 총 53개, 점형 도형자료의 경우 총 13개의 세부 속성이 정의되었고, 각 속성에 대한 속성명, 필드명, 데이터 타입 및 길이 등에 관한 상세 설계서가 작성되었다. 본 연구를 통해 개발된 속성 설계서는 향후 한국형 Reach File 구축에 직접 활용이 가능하며, 따라서 한국형 Reach File의 구체적인 개발 방향의 설정에도 기여할 것으로 예상된다. 향후 연구에서는 속성 설계서 결과를 바탕으로 한국형 Reach File 구축 및 활용에 관한 연구가 뒤따라야 한다.

• Journal of the Korean Vacuum Society
• /
• v.10 no.4
• /
• pp.431-439
• /
• 2001

In this paper, the a-Diamond films were synthesized using filtered vacuum arc source (FVAS), FVAS was composed of a torus structure with bending angle of 60 degree. The radius of torus was 266 mm, the radius of plasma duct was 80 mm and the total length was 600 mm. The magnet parts were composed of one permanent magnet and five solenoid magnets. The plasma duct was electrically isolated from the ground so that a bias voltage could be applied. The baffles inside plasma duct were installed in order to prevent the recoil effect of macro-particles. Cathode was made of graphite with 80 mm in diameter. The effects of solenoid magnet on plasma extraction were investigated by computer simulation and experiment using Taguchi's methode. The source and extraction magnet affected the arc stabilization. The extraction beam current was maximized with low value of the source magnet current and high value of the filtering magnet current. The beam current density was 3.2 mA/$\textrm{cm}^2$ and average deposition rate was 5 $\AA$/sec when the currents of arc discharge, source, extraction, bending, deflection and outlet magnet were 30 A, 1 A, 3 A, 5 A, 5 A, and 5 A, respectively. The beam current density and the efficiency of beam transportation were increased with the positive bias voltage of the plasma duct.