In this study, flow analysis was performed using ANSYS CFX to evaluate the performance of the 30kg hydrogen fuel cell hexa-copter drone in hovering flight. In the case of a hydrogen fuel cell hexa-copter drone, a total of four cooling fans are mounted on the drone's body in two pairs on the left and right to cool the fuel cell module. In order to evaluate the effect of the air flow from the cooling fan on the aerodynamic properties of the hydrogen fuel cell drone as the mounted cooling fan operates, the change in thrust for the case where the cooling fan operates and does not operate was compared and analyzed. Looking at the analysis results, it was found that the presence or absence of the drone's cooling fan had little effect on the drone's thrust through the thrust results for the six wings.

A sirocco fan consists of a housing and an impeller with blades. There are many design parameters for improving its performance and efficiency. Thus, the objective of present study is to investigate the effect of blade size(such as blade length and height) and the number of blades on the flow characteristics of a sirocco fan using a commercial CFD software, Star CCM+. From the results of our previous and present study, it is revealed that blade inclination angle and blade height had a great effect on the flow characteristics, such as the static pressure rise and flow rate. There are important factors in improving the flow characteristics, as following order, the blade inclination angle, blade height, blade length, blade radius of curvature, the number of blades. it was obtained that maximum in static pressure rise and flow rate were, respectively, 20.8Pa and 6.41CMM under the our simulation condition.

본 연구는 온라인 플랫폼을 활용한 건강사정 학습 프로그램이 간호 대학생의 문제해결과정, 비 판적 사고 성향, 수업참여도 및 수업몰입도에 미치는 효과를 알아보기 위한 단일집단 사전사후설계 (one-group pretest-posttest design)를 적용한 원시실험연구(pre-experimental research)이다. 연구 대상자 는 C북도 G군 소재 J대학교 건강사정 및 실습 교과목을 수강하는 간호학과 2학년 학생 52명을 대상으로 온라인 플랫폼을 활용한 건강사정 학습 프로그램 참여 전‧후 자료를 수집하였다. 분석한 결과, 문제해결과 정(t=-2.569, p=.013), 비판적 사고 성향(t=-5.363, p<.001), 수업참여도(t=-4.429, p<.001), 수업몰입도 (t=-3.747, p<.001)가 프로그램 참여 전‧후 통계적으로 유의하게 향상된 것으로 나타났다. 따라서 건강사정 수업 시 간호 대학생들의 문제해결과정, 비판적 사고 성향, 수업참여도, 수업몰입도 향상을 위해서 온라인 플랫폼을 활용한 학습 프로그램을 활용할 수 있을 것으로 사료된다.

최근 우리나라는 중앙집권식 규제혁신을 지양하고, 지방자치단체와 긴 밀한 협력을 위하여 규제개선을 추진하고 있다. 이러한 정부의 방향은 행정규제기본법 제1조에 명시된 ‘불필요한 행정규제를 폐지하고 비효율 적인 행정규제의 신설을 억제함으로써 사회・경제활동의 자율과 창의를 촉진하여 국민의 삶의 질을 높이고 국가경쟁력의 지속적 향상’이라는 목 적과 연결된다. 그러나 기존 연구는 상술한 법령에 따라 국가적 차원에 서 규제 또는 정부규제의 개념을 적용하거나 특정사무를 중심으로 접근 하고 있다. 반면 본 연구는 지방자치단체가 제정한 규칙을 통해 지역 개 인 또는 조직의 행위를 제약한다는 지방규제의 개념을 제시하였다. 뿐만 아니라 지방자치제가 도입되었음에도 불구하고 자치권이 부족하다는 비 판적 입장에서 자치사무와 위임사무를 구분하여 분석하였다. 분석 결과, 지방규제는 자치사무보다 위임사무가 많았으며, 위임사무 중 유형별로 기본권에 제한이 있는 3호 유형이 가장 많았고, 3호 유형 중 세부유형에 는 기준설정이 가장 많은 부분을 차지하고 있었다. 또한 지방규제 등록 변경사유는 정부의 지방규제 완화 방침과 달리 누락 또는 기존규제에 기 준을 설정하는 등의 규제가 다수를 이루고 있었다. 이와 같은 분석을 통 해 정부가 지방규제를 개선하는 이른 바 규제개혁을 주장하고 있음에도 불구하고 실제 규제의 내용은 완화와 반대되는 흐름 및 현황을 나타내고 있었다.

The rack cylinder is an important part of the pile leg structure of the jack up platform. Because of its complex structure, the flow field around the rack cylinder is different from that around the ordinary cylinder, which brings difficulties to the research of the rack cylinder. In this paper, using CFD(Computational Fluid Dynamics) solved the flow field of chords with different rack height and rack width under different KC and Re, the characteristics of the flow field around the cylinder with rack are obtained. The results show that Re, KC, rack height and rack width all have different effects on the flow field. When Re and KC are constant, Cd will increase with the increase of rack height ratio, the change of Cd and Cl is not significant, while the change of Cd and Cl varies with Re when the chord structure is fixed.

본 연구는 간호대학생의 진로적응력을 증진하기 위한 고려로 낙관성과 진로적응력 간 관계에서 학습몰입의 매개 효과를 파악하고자 수행된 서술적 조사연구이다. 연구대상은 G시와 M시의 4년제 대학 간호학과에 재학 중인 학생이며, 자료는 2023년 4월부터 5월까지 수집하였다. 자료 분석을 위해 기술적 통 계, Pearson 상관계수, Baron과 Kenny의 회귀분석을 실시하였다. 연구결과, 첫째, 낙관성은 학습몰입에 정 적인 영향을 나타냈다. 둘째, 낙관성은 진로적응력에 정적인 영향을 나타냈다. 셋째, 학습몰입은 낙관성과 진로적응력 사이에서 부분 매개효과를 나타냈다. 이로써 간호대학생의 진로적응력을 증진하기 위해서는 낙 관성과 학습몰입을 촉진하기 위한 전략들이 간호교육현장에서 필요함을 알 수 있다.

PURPOSES : This study is to initiated to estimate the impact of mixed traffic flow on expressway section according to the market penetration rate(MPR) of automated vehicles(AVs) using a enhanced intelligent driver model(EIDM). METHODS : To this end, microscopic traffic simulation and EIDM were used to implement mixed traffic flow on basic expressway section and simulation network was calibrated to understand the change of impact in mixed traffic flow due to the MPR of AVs. Additionally, MOEs of mobility aspects such as average speed and travel time were extracted and analyzed. RESULTS : The result of the impact of mobility MOEs by MPR and level of service indicated that 100% MPR of AVs normally affect positive impact on expressway at all level of service. However, it was analyzed that improvements in the level of service from LOS A to C are minimal until the MPR of AVs reaches 75% or higher. CONCLUSIONS : This research shows that impact of MPR of AVs using EIDM of mixed traffic flow on basic expressway. Increasing MPR of AVs affects positive impact on expressway at all level of services. However, MPR from 25% to 75% of AVs in LOS A to C shows minimal impacts. Therefore, to maximize the effectiveness of AVs, appropriate traffic operation and management strategies are necessary.

In general, systems are developed by repeatedly performing the processes of design, analysis, manufacturing, and performance testing. In particular, systems with temperature, pressure, and flow rate often utilize computational fluid dynamics tools at the design stage. In this paper, we aim to verify the reliability of the analysis results of Solidworks Flow Simulation, which is widely used in heat flow analysis at the design stage. A tube furnace was manufactured, various experiments were performed, and a study was conducted to compare the analysis results. The details of the experiment are as follows. First, an experiment was conducted in which the heater was heated to 900°C without insulating the exposed part of the tube. The detailed contents of the experiment are as follows; - Heating heater and measuring temperature without supplying flow inside the tube, - Tube flow supply (25°C, 15 lpm air) and heater heating/temperature measurement. Second, an experiment was performed in which the exposed part of the tube was insulated (thickness 50 mm) and the heater was heated to 900°C. The detailed contents of the experiment are as follows; - Insulate the outside of the tube except for the flanges at both ends of the tube, and heat the heater and measure the temperature without supplying flow inside the tube. - Insulate the outside of the tube except for the flanges at both ends of the tube, supply flow rate inside the tube (25°C, 15 lpm air) and measure heater heating/temperature. - Insulate the flange of the flow supply section, heat the heater and measure temperature without supplying flow inside the tube. - Insulate the flange of the flow supply section, heat the supply air (277°C, 15 lpm) and measure the temperature using a heating gun without heating the heater. - Insulate the flange of the flow supply section, supply heated air (277°C, 15 lpm) and measure heater heating/temperature. - Insulate the flange of the flow supply section and measure temperature according to heater heating (900°C) and supply temperature (25°C, 277°C 15 lpm). The following results were derived from the experimental and analysis results. - When the exposed part of the tube is insulated, the temperature inside the tube increases and the steady-state power decreases compared to non-insulated. - In areas with insulation, the temperature error between experiment and analysis results is not large. - When flow rate is supplied, there is a large temperature error in experiment and analysis results. - The temperature change after the center of the heater is not large for a temperature change of 15 lpm flow rate. From these results, it can be seen that Solidworks Flow Simulation has a significant difference from the experimental results when there is a flow rate in the tube. This was thought to be because the flow rate acts as a disturbance, and this cannot be sufficiently accounted for in the analysis. In the future, we plan to check whether there is a way to solve this problem.

In this study, numerical analysis was performed for the purpose of analyzing the flow characteristics and performance according to the change in the inflow hydrogen temperature and differential pressure of the receptacle of the hydrogen charging system. The pressure distribution and turbulent kinetic energy in the filter area were analyzed by changing the outlet pressure condition under the inlet hydrogen temperature condition, and the flow velocity change at the outlet was compared and analyzed. As a result of the analysis, as the differential pressure decreased, the flow rate at the outlet of the receptacle decreased by up to about 70% at the 2.86 MPa condition compared to the 1.86 MPa condition, and the mass flow rate decreased by about 56.5% at the maximum. It was found that the standard CV performance was not satisfied when the differential pressure at the inlet and outlet was 1.12 MPa or less under the 363K temperature condition.

This study focused on how retail tech promotes differentiated customer experiences in offline fashion stores. The purpose of this study is to determine the effects of the characteristics of fashion retail tech stores on consumers’ flow and satisfaction. We surveyed Koreans aged 10 to 50 who had experienced offline fashion retail tech stores. The survey was conducted from April 28, 2023, to May 21, 2023. The total number of survey respondents was 200. The quantitative data collected through questionnaires was analyzed using SPSS 25.0. To reveal the effects of fashion retail tech store characteristics on consumer’s flow and satisfaction, frequency analysis, we conducted frequency analysis, factor analysis, reliability analysis, correlation analysis, and regression analysis. The results of this study, figured out that fashion retail tech store’s characteristics, including playfulness, efficiency, interaction, and information provision, have a significant impact on behavior flow, emotional flow, and satisfaction. As a result of analyzing the influence of consumers’ flow led to satisfaction, it was confirmed that emotional flow positively influenced satisfaction, but behavioral flow had no meaningful effect on satisfaction. The results of our study can be used to make a successful marketing strategy and can serve as foundational data for consumer research on retail-tech-applied offline fashion stores.

The purpose of flow analysis is to develop a simple CFD analysis model to develop a heat transfer analysis model including transient heat transfer characteristics, especially phase change, of thin film evaporators. The simple analytical model focuses on the evaporation phase change. To reduce the computational cost, the shape was simplified to two dimensions, and the simulation time was set short with a focus on simulating the phase change phenomenon. In the future, based on this analysis model, we will develop an analysis model for simulating not only vaporization but also liquefaction, that is, transient distillation phenomenon, according to the shape of the thin film distillation device.

In this study, numerical modeling on the gas flow and off-gases in the low temperature carbonization furnace for carbon fiber was analyzed. The furnace was designed for testing carbonization process of carbon fibers made from various precursors. Nitrogen gas was used as a working gas and it was treated as an incompressible ideal gas. Three-dimensional computational fluid dynamics for steady state turbulent flow was used to analyze flow pattern and temperature field in the furnace. The off-gas mass fraction and cumulative emission gas of species were incorporated into the CFD analyses by using the user defined function(UDF). As a results, during the carbonization process, the emission of CO2 was the dominant among the off-gases, and tow moving made the flow in the furnace be uniform.

The following results were obtained by conducting a flow experiment. The experiment with air volume showed that the ducts with 3 shapes in the same cross-sectional area were large in the order of circular duct, square duct, and flexible duct. As a result of measuring the pressure value by duct shape to determine the cause of the difference between the flow rate and the air volume value by duct, the negative pressure was large in the order of circular duct, square duct, and flexible duct. in the countercurrent test, In the case of circular ducts, the deviation was high, In the case of Flexible ducts, the mild increase in the countercurrent is judged to be the difference in pressure and friction received by shape.

Geologic disposal at deep depth is an acceptable way to dispose of high-level radioactive waste and isolate it from the biosphere. The geological repository system comprises an engineered barrier system (EBS) and the host rock. The system aims to delay radionuclide migration through groundwater flow, and also, the flow affects the saturation of the bentonite in the EBS. The thermal conductivity of bentonite is a function of saturation, so the temperature in the EBS is directly related to the flow system. High-temperature results in the two-phase flow, and the two-phase flow system also affects the flow system. Therefore, comprehending the influencing parameters on the flow system is critical to ensure the safety of the disposal system. Various studies have been performed to figure out the complex two-phase flow characteristics, and numerical simulation is considered an effective way to predict the coupled behavior. DECOVALEX (DEvelopment of COupled models and their VALidation against EXperiments) is one of the most famous international cooperating projects to develop numerical methods for thermo-hydro-mechanicalchemical interaction, and Task C in the DECOVALEX-2023 has the purpose of simulating the Fullscale Emplacement (FE) experiment at the Mont-Terri underground research laboratory. We used OGS-FLAC, a self-developed numerical simulator combining OpenGeoSys and FLAC3D, for the simulation and targeted to analyze the effecting parameters on the two-phase flow system. We focused on the parameters of bentonite, a key component of the disposal system, and analyzed the effect of compressibility and air entry pressure on the flow system. Compressibility is a parameter included in the storage term, defining the fluid storage capacity of the medium. While air entry pressure is a crucial value of the water retention curve, defining the relation between saturation and capillary pressure. From a series of sensitivity analyses, low compressibility resulted in faster flow due to low storage term, while low air entry pressure slowed flow inflow into the bentonite. Low air entry pressure means the air easily enters the medium; hence the flow rate becomes lower based on the relativity permeability definition. Based on the sensitivity analysis, we further investigate the effect of shotcrete around the tunnel and excavation damaged zone. Also, long-term analysis considering heat decay of the radioactive waste will be considered in future studies.

Since 1992, various numerical codes, such as TOUGH-FLAC and ROCMAS, have been developed and validated to dispose of Spent Nuclear Fuel (SNF) safely through a series of DEvelopment of COupled models and their VALidation against EXperiments (DECOVALEX) projects. These codes have been developed using different approaches, such as general two-phase flow and Richards’ flow which is an approximated approach neglecting gas pressure change, to implement the same multiphysics behaviors. However, the quantitative analysis for numerical results, which originated from different fundamental approaches, has not been conducted accurately. As a result, improper utilization of the approach to analyze certain conditions occurring such as dramatic gas pressure change may result in erroneous outcomes and systemic problem pertaining to TH analysis. In this study, the quantitative analysis of the two approaches, in terms of TH behavior, was conducted by comparing them with a 1D simulation of the CTF1 experiment carried out by laboratory experiment. The results calculated by different approaches show agreement in terms of TH behaviors and material properties change until 120°C. The results verify the applicability of Richards’ flow approach in a high temperature environment above the current thermal criteria, set as 100°C, and gas pressure change does not have a significant impact until 120°C. Therefore, although further studies for applicability of Richards’ flow are needed to suggest the appropriate temperature range, these quantitative analyses may contribute to the performance assessment of a compact repository using the high-temperature bentonite concept, which is currently gaining attention.

In this paper, a basic study was conducted to observe the temperature inside the tube according to the heating temperature of the tube furnace. In a tube furnace, a tube is inserted, and the air space outside the tube is heated to increase the temperature of the gas inside the tube through conduction of the tube. Tube furnaces are widely used in research to capture volatile nuclides. In this case, a volatile nuclide capturing filter is inserted inside the tube, and an appropriate temperature is required to capture it. Since the tube furnace heats the air space outside the tube to the target temperature, a difference from the temperature inside the tube occurs. In particular, if a flow of gas occurs inside the tube, a larger temperature difference may occur. In order to confirm this temperature difference, an experimental device was constructed, and basic data was produced through several experiments. The following studies were conducted to produce data. First, the temperature of the air layer of the heating unit and the temperature inside the tube were measured in real time in the absence of gas flow inside the tube. Second, the temperature of the air layer of the heating unit and the temperature inside the tube were measured in real time while air having a certain temperature was flowing inside the tube. As a result of the experiment, when there is no flow inside the tube, when the heating target temperature is low, the temperature inside the tube is significantly lower than the target temperature, and when the target temperature is high, the temperature inside the tube approaches the target temperature. It was found that when there is about 20°C air flow inside the tube, the temperature inside the tube is significantly lowered even if the heating target temperature is high. In the future, additional research on changing the temperature of the gas flowing inside the tube will be conducted, and the results of this study are expected to greatly contribute to the design of a tube furnace that captures volatile nuclides.