• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
• /
• pp.312-315
• /
• 2003

Basic design of RC-GCTs (Reserve-Conducting Gate-Commutated Thyristors) by novel punch-through (PT) concept with 5,500v rated voltage is described here. A PT and NPT (non punch-through) concept for the same blocking voltage has been compared in detail. The simulation work indicates that GCT with such PT design exhibits that the forward breakdown voltage is 6,400V which is enough for supporting 5500V blocking. Additionally, the real IGCT turn-off in the mode of PNP transistor has been realized. However, the carrier extraction from N-base to gate terminal will be drastic slowly in terms of NPT structure except for the high on-state voltage drop.

• Structural Engineering and Mechanics
• /
• 제16권4호
• /
• pp.423-440
• /
• 2003

Arbitrary Lagrangian Eulerian finite element methods gain interest for the capability to control mesh geometry independently from material geometry, the ALE methods are used to create a new undistorted mesh for the fluid domain. In this paper we use the ALE technique to solve fuel slosh problem. Fuel slosh is an important design consideration not only for the fuel tank, but also for the structure supporting the fuel tank. "Fuel slosh" can be generated by many ways: abrupt changes in acceleration (braking), as well as abrupt changes in direction (highway exit-ramp). Repetitive motion can also be involved if a "sloshing resonance" is generated. These sloshing events can in turn affect the overall performance of the parent structure. A finite element analysis method has been developed to analyze this complex event. A new ALE formulation for the fluid mesh has been developed to keep the fluid mesh integrity during the motion of the tank. This paper explains the analysis capabilities on a technical level. Following the explanation, the analysis capabilities are validated against theoretical using potential flow for calculating fuel slosh frequency.

• 한국안전학회지
• /
• 제26권5호
• /
• pp.54-58
• /
• 2011

Emergency preparedness plan(EPP) is the systematic management of activities that involve a material degree of risk of loss or other damage to the surroundings(people, property and environment), and the boundary of accident recovery plan(ARP). The main purpose of the program is to provide a safety management system to each facility in order to enable to prevent accident and to control accident immediately. The EPP includes not only typical safety-related documentations such as material safety data sheet(MSDS), standard operation procedure(SOP), emergency response plan(ERP). EPP is established basis of the preliminary safety analysis involving risk identification, assessment and prevention plans. The program is also helpful for government or related agencies to control a number of accidents in small-scale companies in the whole country.

• Steel and Composite Structures
• /
• 제33권3호
• /
• pp.403-432
• /
• 2019

Axially functionally graded (AFG) beams are a new class of composite structures that have continuous variations in material and/or geometrical parameters along the axial direction. In this study, the exact analytical solutions for the free vibration of AFG and uniform beams with general elastic supports are obtained by using Euler-Bernoulli beam theory. The elastic supports are modeled with linear rotational and lateral translational springs. Moreover, the material and/or geometrical properties of the AFG beams are assumed to vary continuously and together along the length of the beam according to the power-law forms. Accordingly, the accuracy, efficiency and capability of the proposed formulations are demonstrated by comparing the responses of the numerical examples with the available solutions. In the following, the effects of the elastic end restraints and AFG parameters, namely, gradient index and gradient coefficient, on the values of the first three natural frequencies of the AFG and uniform beams are investigated comprehensively. The analytical solutions are presented in tabular and graphical forms and can be used as the benchmark solutions. Furthermore, the results presented herein can be utilized for design of inhomogeneous beams with various supporting conditions.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2023년도 봄 학술논문 발표대회
• /
• pp.121-122
• /
• 2023

Existing modular research has been mainly focused on S (shelter structure) and I (infill interior finishing material), and considerable research has been conducted, and the results are being proposed. However, in the case of the rest (exterior materials and windows, etc.), existing construction methods and materials are borrowed, and supporting hardware members and insulation materials are constructed on site, which acts as a factor hindering overall shortening of the construction period. That is, since the advantages and characteristics of modularity cannot be utilized in the absence of modular cladding, manufacturing of cladding is required. Therefore, it is necessary to develop a cladding system that can drastically reduce the construction period in factories while considering the structural characteristics of PC modulars.

• 한국콘텐츠학회논문지
• /
• 제16권8호
• /
• pp.529-539
• /
• 2016

본 연구는 지역사회 건강증진사업에서 주민참여에 영향을 미치는 사업지원요인을 규명하기 위한 서술적 연구이다. B시에서 주최한 3개월간 일만보 걷기사업을 중도에 포기하지 않고 끝까지 참여한 지역주민 418명을 대상으로 하였다. 자료는 자기보고식 설문지를 이용하여 수집하였고, T검정과 분산분석, 다중회귀분석으로 분석하였다. 사업 참여자 중 물리적 지원(만보기(p<.001), 걷기기록장(p<.001), 실천저금통(p=.002))을 이용하거나, 정보적 지원(걷기교육, 주민리더교육)에 참여하거나(p<.001), 촉진행사 및 모임(보건소별 걷기모임)에 참여횟수가 많거나(p<.001), 파트너십(걷기 동아리에 소속된 경우)에 따라서(p<.001) 걷기 참여일수는 통계적으로 유의한 차이가 있었다. 또한 걷기 기록장 사용, 동아리 소속이 걷기 참여의 유의한 영향요인으로 나타났다. 따라서 추후 건강증진 사업운영 시 참여자의 건강증진 행위실천을 돕기 위한 물품을 지원하고 파트너십을 구축(모임, 동아리) 하는 등 주민참여 향상을 위한 다양한 정책전략이 필요하다.

• 한국전기전자재료학회논문지
• /
• 제30권11호
• /
• pp.683-687
• /
• 2017

We investigated the structure of an ultra-thin insulating board with low thermal conductivity along z-axis, which was based on the idea of void layers created during the glass infiltration process for the zero-shrinkage low-temperature co-fired ceramic (LTCC) technology. An alumina and four glass powders were chosen and prepared as green sheets by the tape casting method. After comparison of the four glass powders, bismuth glass was selected for the experiment. Since there is no notable reactivity between alumina and bismuth glass, alumina was selected as the supporting additive in glass layers. With 2.5 vol% of alumina powder, glass green sheets were prepared and stacked alternately with alumina green sheet to form the 'alumina/glass (including alumina additive)/alumina' structure. The stacked green sheets were sintered into an insulating substrate. Scanning electron microscopy revealed that the additive alumina formed supporting bridges in void layers. The depth and number of the stacking layers were varied to examine the insulating property. The lowest thermal conductivity obtained was 0.23 W/mK with a $500-{\mu}m-thick$ substrate.

• 한국수소및신에너지학회논문집
• /
• 제19권6호
• /
• pp.505-513
• /
• 2008

The two-step thermochemical cycle was examined on the $CeO_2$, YSZ, and $ZrO_2$-supported $NiFe_2O_4$ to investigate the effects of support material addition. The supported $NiFe_2O_4$ was prepared by the aerial oxidation method. Thermal reduction was conducted at 1573K and 1523K while water-splitting was carried out at 1073K. Supporting $NiFe_2O_4$ on $CeO_2$, YSZ and $ZrO_2$ alleviated the high-temperature sintering of iron-oxide. As a result, the supported $NiFe_2O_4$ exhibited greater reactivity and repeatability in the water-splitting cycle as compared to the unsupported $NiFe_2O_4$. Especially, $ZrO_2$-supported $NiFe_2O_4$ showed better sintering inhibition effect than other supporting materials, but hydrogen production amount was decreased as cycle repeated. In case of $CeO_2$-supported $NiFe_2O_4$, improvement of hydrogen production was found when the thermal reduction was conducted at 1573K. It was deduced that redox reaction of $CeO_2$ activated above 1573K.

• 원예과학기술지
• /
• 제30권2호
• /
• pp.201-207
• /
• 2012

본 연구는 딸기 소식물체의 급속대량 증식을 위한 기내배양에서 적정한 지지물과 최적의 MS 배지 이온강도를 구명하기 위해 수행되었다. 딸기($Fragaria$ $ananassa$ 'Houkouwase') 절편체는 지지물로 agar와 Tosilee(상업적 플러그 육묘용 배지) 배지를 사용하고, 공급된 MS 배지는 기본 MS(대조구), 1/2 MS, 1/4 MS의 강도로 공급하여 자가영양배양 하에서 미세증식하였다. Agar 배지에서 생육을 비교했을 때 1/2 MS 강도에서 초장과 근장이 가장 길었다. 또한 1/2 MS 강도에서 지상부 생체중과 건물중, 그리고 엽면적이 1/4 MS와 기본 MS 강도에서보다 우수했다. 기본 MS의 Tosilee 배지에서 딸기 소식물체를 배양했을 때 초장, 근장, 지상부와 지하부의 생체중과건물중이 agar 배지에서 배양했을 때보다 더 양호했다. 자가영양배양을 통한 기내미세번식 딸기 소식 물체는 1/2 MS 강도의 agar 배지에서 배양하기보다는 기본 MS 강도의 토실이배지에서 가장 우수한 생육을 나타냈다.

• Tribology and Lubricants
• /
• 제34권2호
• /
• pp.43-48
• /
• 2018

This paper presents the thermohydrodynamic analysis of tilting journal pad bearings supporting a power turbine rotor applied to a 250 kW super-critical $CO_2$ cycle. In the analysis, the generalized Reynolds equation and 3D energy equation are solved to predict oil film temperature and the 3D heat conduction equation is solved for pad temperature. The power turbine rotor is supported by two tilting pad bearings consisting of five pads with an oil supply block between the pads. Copper backing pads with higher thermal conductivity compared to steel backing pads are adopted to improve thermal management. The predicted maximum pad temperature is around $55^{\circ}C$ which is approximately $15^{\circ}C$ higher than oil supply temperature. In addition, the predicted minimum film thickness is 50 mm at a rotating speed of 5,000 rpm. These results indicate that there is no issue in the thermal behavior of the bearing. An operation test is performed with a power turbine module consisting of a power turbine, a reduction gear and a generator. Thermocouples are installed at the 75% position from the leading edge of the pad to monitor pad temperature. The power turbine uses compressed air at a temperature of $250^{\circ}C$ in its operation. The steady state pad temperatures measured in the test show good agreement with the predicted temperatures.