상선에 비해 잦은 변침을 하고 어획물로 인한 중량 및 무게중심의 변화와 같은 다양한 운항조건을 가진 어선의 경우, 조종성능 은 선박 운항 시에 매우 중요한 역할을 한다. 소형 어선의 사고는 2022년 기준 전체 해상 사고의 약 60%를 차지하며, 이는 부족한 조종성 능으로 인한 충돌과 좌초 사고가 주요 원인이다. 특히 10톤 미만의 소형선박에서 발생한 사고는 전체 사고의 약 65%를 차지하는데, 소형 어선의 조종성능 관련 기준이 부재하여 이를 정확히 평가하기엔 어려움이 있다. 이에 본 연구에서는 4.99톤급 소형 어선을 대상선으로 선 정하여 3D-CAD로 모델링 한 후, 상용 수치해석 프로그램인 STAR-CCM+를 활용하여 선박의 조종운동 시뮬레이션 환경을 구축하였다. 이 를 바탕으로 다양한 표준재화상태와 무게중심을 고려하여 10° / 10° 및 20° / 20° zigzag test와 35° turning test를 수행하였고, 선체 중량이 증가 함에 따라 변침성능이 감소하고 선회성능이 향상되는 경향을 분석하였다. 그 중, 만재출항과 부분만재입항 상태에서는 상대적으로 선회 성능이 부족한 결과를 확인하였다. 이를 바탕으로 소형선박의 안전한 운항을 위한 표준재화상태와 무게중심을 고려한 조종성능의 평가 및 그에 상응하는 표준화된 조종성능 평가 기준의 필요성을 제시하였다. 또한, 본 연구의 조종성능 평가 결과가 소형선박의 조종성능 평 가 기준 선정을 위한 기초자료로 활용될 수 있을 것으로 기대된다.

PWR spent nuclear fuel generally showed an oxide film thickness of 100 um or more with a combustion rate of 45 MWD/MTU or higher, while CANDU spent nuclear fuel with an average combustion rate of about 7.8 MWD/MTU had few issues related to hydride corrosion. Even based on the actual power plant data, it is known that the thickness of the oxide film is 10 μm or less on the surface of the coating tube, and brittleness caused by hydride is shown from the thickness of the oxide film of about 80 μm, so it is not worth considering. However, since corrosion may be accelerated by lithium ions, lithium ions may be said to be a very important factor in controlling the hydro-chemical environment of heavy water. Lithium has a negative effect on the corrosion of zirconium alloys. However, since local below 5 ppb to prevent corrosion. maintained at a concentration between 0.35 and 0.55 ppm. Hydrogen is known to have a positive effect by suppressing radioactive decomposition of the coolant and suppressing cracks in nickelbased alloys. However, too much hydrogen can produce hydride in a pressure tube composed of Zr-2.5Nb, so DH (Disolved Hydrogen) maintains the range of 0.27–0.90 ppm. pH and conductivity are completely determined by lithium ions, and DH can be completely removed below 5 ppb to prevent corrosion. Therefore, for cladding corrosion simulation of the CANDU spent nuclear fuel, a hydrochemical of the equipment, not 310°C, and 14 uS·Cm−1 is targeted as conditions for corrosion acceleration. In addition, for acceleration, the temperature was set to 345°C (margin 10°C), which is the maximum accommodation range of the equipment, not 310°C.

Particle morphology change and different experimental condition analysis during composite fabrication process by traditional ball milling with discrete element method (DEM) simulation were investigated. A simulation of the three dimensional motion of balls in a traditional ball mill for research on the grinding mechanism was carried out by DEM simulation. We studied the motion of the balls, the ball behavior energy and velocity; the forces acting on the balls were calculated using traditional ball milling as simulated by DEM. The effect of the operational variables such as the rotational speed, ball material and size on the flow velocity, collision force and total impact energy were analyzed. The results showed that increased rotation speed with interaction impact energy between balls and balls, balls and pots and walls and balls. The rotation speed increases with an increase of the impact energy. Experiments were conducted to quantify the grinding performance under the same conditions. Furthermore, the results showed that ball motion affects the particle morphology, which changed from irregular type to plate type with increasing rotation speed. The evolution was also found to depend on the impact energy increase of the grinding media. These findings are useful to understand and optimize the particle motion and grinding behavior of traditional ball mills.

Most of steam power plants in Korea are using the method of heating the feed water whenever the ambient temperature around the power plant area below 5°C to prevent freezing water flowing in the pipe in winter time. But this kind of heat supplying system is not useful to save energy. If we take the method that the temperature of the each pipe is controled by direct measure of temperature by attaching sensor on the outside surface of the feed water tubes, then we can expect that a plenty of energy can be saved. In this study, the computer simulation is used to compare the energy consumption loads of both systems. Energy saving rate is calculated for the location of Incheon area in winter season. Four convection heat transfer coefficients for the ambient air and three initial flowing water temperature inside the tube were used. The result shows that the temperature control system using sensor represents more than 95% of energy saving rate in Incheon area. Even in the severe January weather condition, the energy saving rate is almost 75% in two days basis and even 83% in one day basis.

In recently, a growing concern for the health of urban residents increased interests in a variety of outdoor activities simply be done in terms of cost and time. They are specially interested in low-impact and safe exercises around residential or working area. Walking is the one of easily doing exercise in daytime or nighttime near residential area. The sidewalks of boulevard near the residential area is the best place for exercise because of easy access and the green space with roadside trees. However, if the nighttime is not guaranteed the proper lighting condition, the possibility of exposure to crime and the threat to pedestrian safety can be increased. Because roadside trees are one of the potential obstacle for lighting condition, supplementary lightings are important to mitigate interruption for safety. To meet such a need, the purpose of this study is to propose a simulation approach which improves lighting condition on sidewalks of boulevard with variety of roadside trees. To do so, the simulation approach is applied for analyzing the interrupted condition by classified five standard types of roadside trees considering the growth of them and finding optimal layout of supplementary luminaires by lighting types. The results of this approach shows that it is useful for assessing the safety of pedestrian in nighttime.

Recently, all-electrified houses have constructed and some tasks are being carried out to monitor energy consumption patterns. The energy monitoring includes various elements such as temperature, pressure, water flow, CO2, and electricity. In this monitoring, electricity consumption is one of the essential factors because the performance and energy saving levels are described by this physical quantity. This quantity depends on materials, structure, operation of the house, which operation means consumer's life style and usage patterns of home appliances furthermore. Firstly, this paper shows a control simulation method which were developed a few years ago. And some different methods are proposed considering flexible experimental condition.

We performed high-resolution three-dimensional global magnetohydrodynamic (MHD) simulations to study the interaction between the Earth’s magnetosphere and a prolonged steady southward interplanetary magnetic field (IMF) (Bz = –2nT) and slow solar wind. The simulation results show that dayside magnetic reconnection continuously occurs at the subsolar region where the magnetosheath magnetic field is antiparallel to the geomagnetic field. The plasmoid developed on closed plasma sheet field lines. We found that the vortex was generated at the magnetic equator such as (X, Y) = (7.6, 8.9) RE due to the viscous-like interaction, which was strengthened by dayside reconnection. The magnetic field and plasma properties clearly showed quasiperiodic variations with a period of 8–10 min across the vortex. Additionally, double twin parallel vorticity in the polar region was clearly seen. The peak value of the cross-polar cap potential fluctuated between 17 and 20 kV during the tail reconnection.

입자 기반 유체 시뮬레이션에서 유체와 완전탄성체의 중간 형태인 점탄성체는 유체와는 달리 물질의 변형에 대한 항복응력(yield stress)이 필요하다. 기존 입자 기반의 점탄성체 연구에서는 폰 미제스(von Mises) 항복조건을 사용해 점탄성체의 변형을 표현하였으나 폭발을 표현하지는 못하였다. 본 논문은 물체가 받는 수많은 방향의 힘을 계산해야 하는 폰 미제스의 항복조건과는 달리 최대 주응력과 최소 주응력의 차를 이용해 쉽게 근사 할 수 있는 트레스카(Tresca)의 항복조건을 변형한 이상적 점탄성체 항복조건을 제안한다. 폰 미제스의 항복조건을 쉽게 근사화하기 위해 물체가 받는 힘을 변형된 길이로 표현한 기존 입자 기반의 시뮬레이션과 달리, 본 논문은 트레스카의 항복조건을 바탕으로 2차원 물체가 힘을 받아 변형된 넓이를 주응력으로 가정한다. 가장 큰 힘을 받는 순간을 최대주응력, 가장 적은 힘을 받는 순간을 최소 주응력으로 근사 화하여 차이를 계산한다. 점탄성체의 경계면이 이상적 항복 조건 이상으로 줄어들 때 물체가 한계응력을 이기지 못하고 현실감 있게 폭발하는 과정을 표현할 수 있음을 확인하였다.

지진해일 또는 조석과 같은 파의 거동을 수치모의할 때 해안선의 위치는 파랑의 움직임에 따라 끊임없이 이동하게 된다. 따라서, 이를 수치모형에 효과적으로 반영하기 위해서는 수치모형의 경계선을 파랑의 움직임에 따라 이동시켜야 한다. 본 연구에서는 경사지형을 계단지형으로 단순화한 이동경계조건에 대해 해안선의 이동을 보다 정확히 모의하기 위하여 천수방정식의 비선형항을 2차 정확도의 풍상차분기법으로 차분화하여 해석하였다. 개발된 수치모형을 검증하기 위하여 바닥마