In this study, numerical analysis was performed on a type IV hydrogen storage tank to analyze the temperature change of hydrogen inside the tank and the filling performance by changing the inlet nozzle outlet angle and the number of outlets. Considering the residual state of charge (SOC) inside the initial tank, the initial pressure was 10 MPa, and the temperature of hydrogen inside the tank and the SOC results were analyzed when hydrogen with a temperature of 233 K was introduced under the conditions of liner, wrap, and outside temperature of 298 K. The results of the analysis showed that the charging completion rate reached the charging limit pressure. The analysis showed that time of filling completion, when the filling limit pressure is reached, the SOC result is about 94% for all geometry change conditions, and the filling completion time increases by 5s as the number of outlets decreases. The temperature change of the wrap area at the end of filling is up to 3.6K, which shows that the outside air temperature has a negligible effect on the hydrogen temperature change inside the tank.

3D 프린팅 콘크리트는 임의의 형상을 자유롭게 적층하여 제작할 수 있다는 장점을 가지고 있지만, 노즐의 구조 및 형상에 따라 곡선부의 출력 품질이 달라진다. 또한, 공기중에서 출력한 경우와 수중에 서 출력한 경우 그 품질이 달라진다. 본 연구에서는 고정 마감날을 가진 사각형 노즐을 이용하여 3D 프린팅 모르타르를 수중에서 곡선 형태로 출력하고 적층한 후 출력성능, 적층성능, 및 역학적성능을 평가하였다. 30 × 30 mm 사각형 개구부를 가지고 있고 노즐 끝 양 측면에 고정 마감날이 설치된 노 즐을 사용하였다. 사전 직선 출력시험에서 선정된 조건인 호퍼 회전속도 14 rpm, 노즐 이동 속도 2000 mm/min을 적용하여 출력하였고, 1층 높이를 30mm로 출력하여 5층 적층하였다. 출력 및 적층 결과, 직선부분의 표면은 양호한 반면 곡면부분, 특히 곡률이 큰 곡선부분의 바깥쪽에서 표면균열이 관찰되었다. 직선부분의 치수 일관성은 양호한 반면, 곡률 반경이 작은 곡선부분의 폭 차이가 나타났 다. 곡선부분의 밀도와 압축강도는 직선부분보다 낮았다. 이는 곡선부에서 직사각형 노즐 회전에 따른 재료 토출이 불균일하기 때문인데, 이러한 문제점을 보완할 수 있는 제어 기술 개발이 필요하다.

In this study, we examined the effect of orifice diameter on atomization performance such as SMD(Sauter Mean Diameter), MMD(Mass median diameter), particle size distribution, spray distance, and spray angle when water was sprayed through a siphon nozzle. In addition, the behavior characteristics of spray were analyzed using the CFD(Computational Fluid Dynamics) commercial program. In the downstream direction of the flow, the dispersion and diffusion power of the droplets increased, greatly improving atomization performance. The spray spread in the radial direction when the jet velocity of water increased. As a result, atomization performance improved as the jet velocity increased.

In this study, a vibrating nozzle using the waste vibration energy of the compressor body was installed in the suction flow path to improve the efficiency of the compressor through the pre-compression. To this end, the behavior of the suction valve according to the vibrating nozzle and the mass flow rate of the refrigerant entering the compression chamber were numerically analyzed. The results showed that the mass flow rate increased proportionally as the angle of the vibration nozzle increased. Among the profile shapes of the vibration nozzle, the concave or straight shape showed the highest mass flow rate. Considering the ease of machining, the straight shape is more favorable. On the other hand, as the operating frequency and stroke of the vibration nozzle increased, the mass flow rate also increased proportionally. It can be seen that the largest nozzle angle, operating frequency, and stroke are favorable for pre-compression unless the suction flow is restricted.. In the future, it is necessary to apply the vibrating nozzle system to an actual compressor model to experimentally check the compressor's cooling power, compression work and EER.

In this research, the dynamics equations for a demolition fire vehicle were formulated. This was done by developing an interface that allows co-simulation using ADAMS and MATHEMATICA. In this study, MATHEMATICA alone was used to calculate the constrained dynamics equations, to demonstrate the impact force and the constraint Jacobian of the end-effector as any desired location through the x, y and z axes. Then we mathematically derived a model for a unilaterally constrained multi-link. Assumptions about the fire demolition vehicle of the constraint coordinate and the impact issues of the model are discussed in the next sections. The estimation procedure for the dynamics equation showed good approximation results in terms of solving a reaching task problem.

본 연구에서는 멀티콥터를 이용한 무인항공용 방제약제 살포시 사용하는 상용 노즐에 3가지 타입에 따른 살포양상과 피복도를 조사하였다. 처리구에 플루페녹수론·메타플루미존(flufenoxuron+metaflumizone) 액상수화제와 비펜트린(bifenthrin) 유제를 살포하고난 뒤, 살포 약제의 낙하입자를 감수지를 이용하여 측정하고 감수지의 피복도를 조사하였다. 낙하입자 분석결과 풍속의 차이에 따라 노즐별 낙하입자 균일도에 차이를 보였으며 제형별 차이는 없었다. 노즐별 분사량은 공식 제공정보와 실제 분사량에 차이를 보였다. 이 결과들은 무인항공기 이용 농업현장 방제 및 약제등록시험 가이드라인 설정에 근거자료로 활용될 수 있을 것이다.

In this study, the flow by impingement at water dust collector with movable nozzle was analyzed by computational fluid technique. The velocity and vorticity of the dust collector were compared by positioning the nozzle to up and down. Also, the mean velocity were compared through three specific locations that were the diffuser inlet, movable nozzle surface and dust collector outlet. It can be checked that the vorticity and velocity magnitude are verified by the fluid solver of Fluent. As the result of this study, the movable nozzle located at 4cm down from initial position of the nozzle shows the great characteristics of vorticity and velocity distribution for dust collection.

Microbubble is a part of advanced water treatment technologies, and there are several ways for microbubble generation. A strategy using Venturi (convergent-divergent) nozzle with air-suction holes has advantage of energy and time saving compared with the others. Here, we used 3D printer to make the various nozzle geometries in order to understand two-phase flow in the Venturi nozzle and air-breaking mechanism. It was evaluated the effects of convergent and divergent angles independently on air-suction rate and pressure drop, and the two-phase flow (air bubbles and liquid water) were observed. The convergent angle strongly affect the air-suction rate corresponding with increase of pressure drop. Meanwhile, as the divergent angle increased, it became dominant the minor loss by sudden enlargement of flow area, so that the air-suction rate and pressure drop showed decreased.

In this study, an effervescent atomizer capable of mixing and spraying vegetable oil and kerosene at the same time was proposed to examine the usefulness of vegetable oil and kerosene in terms of recycling of renewable energy and waste resources. The effect of nozzle exit diameter variation on the atomization characteristics such as spray angle, droplet size distribution, cumulative volume distribution, and SMD was investigated using LDPA. The results of this study showed that the spray angles decreased with increasing ALR at the same nozzle exit diameter and increased with increasing nozzle exit diameter under the same ALR condition. SMD was decreased with increasing ALR at all nozzle exit diameters, and SMD was decreased with decreasing nozzle exit diameter even under the same ALR conditions. Also, the droplet was more finely atomized when the nozzle exit diameter is reduced under the same ALR conditions and when the ALR is increased at the same nozzle exit diameter, but the uniformity of the droplets was lowered because the droplet with a larger diameter existed.