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.

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.

청정소화약제는 지구오존층 보호를 위해 발효된 몬트리올 의정서에 따라 할론 1211 및 할론 1310을 대체할 수 있는 약제를 말한다. 국·내외적으로는 청정소화약의 시스템 표준화와 성능평가가 수행되고 있다. 본 논문은 일반적인 청정소화약제 시스템을 바탕으로 다양한 노즐의 형상에 대한 모델링 및 수치해석을 수행하여 최적의 노즐 형상을 제안하였다. Type A와 B의 2가지 형상에 대한 노즐의 3차원 모델링을 통해 노즐의 분출속도가 개선될 수 있도록 하였다. 2가지 형상의 노즐에 대하여 유동해석을 실시하였으며 노즐의 홀 직경을 다르게 하여 가스속도 및 압력분포를 측정하였다. 측정결과 노즐 홀 수 및 직경에 따라 노즐출구에서 분출속도가 달라지는 것을 확인할 수 있었으며 노즐 홀 직경에 관계없이 유량은 압력이 증가함에 따라 증가하는 경향을 나타내었다. 실험을 통해 얻어진 결과를 바탕으로 노즐 직경이 5 mm인 경우의 K-factor값이 101.8 l/min·bar-0.5임을 확인하였으며, 최종적으로 노즐 홀 5 mm인 12개의 홀이 2층 구조로 되어있는 형상의 노즐을 제안하였다.

Vortex tubes are simple tubes that can separate hot and cold air from compressed air without any internal device configuration and are used in many industries. If the vortex tube with these advantages is applied to an air conditioning system, it will be free from the use of refrigerant. In this study, basic study on discharge flow rate and temperature separation characteristics was carried out by varying the number of generator nozzle hole in various shapes of the vortex tube according to the inlet pressure of the vortex tube. Experimental results show that as the number of nozzles increases, the discharge flow rate tends to decrease and the temperature separation characteristics were excellent in the number of nozzles 6~7.

This study involved the shape of water jet nozzle to promote blasting ability and an increase of projection distance when cleaning VLBC cargo hold. Simulation of water jet projection process inside VLBC cargo hold was done in both 2D and 3D environment. The result are promising since both case show the capability of water contacting the desired target.

In this paper, a commercial multibody dynamics program ADAMS was utilized to investigate the model for the multi-joint boom conflicts. In this process, CATIA, ANSYS and ADAMS were used to develop the simulation. The addition of ADAMS made the system more accurate and improved precision of the system. In brief, the 3D CAD model of the structure was initially developed via CATIA. After this, the CATIA models were exported to ANSYS for creating flexible-body modeling by using formatted file. Subsequently, with ADAMS, the flexible body model was directly imported from ANSYS which performed the analyses of the dynamic collision of the nozzle boom conflicts. This contained the information regarding geometry and model shapes of the flexible body. Using ADAMS/Durability, it was possible to determine the strain energy for the nozzle configuration by crashing the contact structure that was created. Via this procedure, the acquired simulation analysis of nozzle showed interestingly good results with respect to the objectives of the study

In this study, the researcher investigated the effects of water mist nozzle shape on water mist according nozzle shape angle(=30°, 45°, 60°, 75° and 90°). It was found that the water mist spray with nozzle When exit angle of water mist nozzle is =90° as result examining about spray special quality of water mist, velocity distribution was expose to maximum. And temperature distribution of target plate was looked tendency that range low. Water mist spray system that consider in this research is one of the most important utilities providing water mist in order to supply fire extinguishing.

This study evaluated the fiber orientation and distribution fiber in the beam members of cementitious materials using conventional and tapered nozzles. For this purpose, the specimens with 10cm × 10cm × 30cm were vertically cast to evaluate the fiber orientation and distribution coefficients on the cutting plane. Compared to the conventional nozzle, the tapered nozzle showed an improvement in the fiber orientation and distribution in the beam member.

In this study, the orientation and distribution of fiber in the vertical members of cementitious materials were evaluated by using conventional and tapered nozzles. For this purpose, the specimens with ϕ 15 × 30 cm were cast to evaluate the fiber orientation and distribution coefficients on the cutting plane. The results showed that the tapered nozzle is more effective in improving the orientation and distribution of the fiber than the conventional nozzle.

This study evaluated the influence of nozzle shapes in the orientation of fibers in cementitious materials. The nozzle shapes involved in the study are conventional, balded, and tapered circulars. The results showed that both the bladed and tapered nozzles increased the control performance of fiber orientation compared to the conventional nozzle. In particular, bladed nozzle was more effective in controlling the fiber orientation.