• Journal of Korea Game Society
• /
• v.13 no.6
• /
• pp.5-14
• /
• 2013

This study has focused to identify what kinds of psychological state are most closely related in players experiencing flow while playing game. This study constructs a conceptual model of flow for game players by conducting a survey to 303 online game players. The results indicate that the state of flow was reached when players may gain opportunities for having high self-efficacy as they accomplished tasks. At the same time, it indicate that the higher cognitive performance and self-esteem was able to enhance the higher flow experience while playing a game. This study provides both practical and theoretical implications on how to increase players' flow by providing critical psychological states in the game.

• International Journal of Fluid Machinery and Systems
• /
• v.9 no.2
• /
• pp.160-168
• /
• 2016

In high speed turbopumps, cavitation occurs and often causes the flow instabilities such as cavitation surge and rotating cavitation. The occurrence of these cavitation instabilities is considered to relate to dynamic characteristics of the cavitation, which are modelled using a cavitation compliance and a mass flow gain factor. Various types of cavitation such as a blade surface cavitation, a tip leakage vortex cavitation, and a backflow vortex cavitation occur at the same time in the inducer and the dynamic characteristics of each cavitation have not been clarified yet in experiments. Focusing on the blade surface cavitation as one of fundamental cavitation, we investigated the dynamic characteristics of the blade surface cavitation on a flat plate hydrofoil in experiments in the present study.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1115-1119
• /
• 2007

Five control methods (Speed Control, PID Gain Scheduling, Loop Time Control, Simple PID, Switching Control) have been applied to the control of an Inline Co-axial valve by the simulation of AMESim. The simulation results have shown that the speed control method is the most stable and the fastest way to reach to the set point in the simulation of the flow control. Moreover, It has been found that the five control methods have the almost same characteristics in the power consumption, the counter electromotive force, and the motor angular velocity. According to the analysis results, the fast and stable control characteristics of the speed control method is the most suitable for the flow control using a inline co-axial valve with a DC(BLCD) motor.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.184-187
• /
• 2007

본 논문은 DSP Controller를 적용한 연료전지시스템의 유량제어에 관한 논문이다. 그리고 이 연구에서 사용된 시스템은 1kW급 계통연계 연료전지 시스템이다. 이 연료전지 시스템이 안정적으로 전원을 공급할 수 있도록 시스템에서 요구하는 공기 유량을 정확히 공급하도록 제어하는 것이 본 연구의 목적이다. 이 목적을 이루기 위해 공기 공급 장치에 PID 제어기를 설계하여 적용하였다. PID 제어기의 Gain값은 지글러 니콜스 Tuning 방식으로 정하였다. 이 제어기를 적용하여 실험한 결과, 적용 전 상태와 비교하면 맥동이 30% 저감하였고, 정상상태 오차가 제거되어 온도 변화와 같은 외란과 상관없이 정확한 요구 공기 유량을 공급함을 확인할 수 있었다. 그리고 부하가 변동함에 따라 해당 요구 공기 유량이 바뀔 때 1초 내에 그 요구 공기 유량을 추종하여 스택이 안정적으로 운전될 수 있도록 하였다.

• Journal of ILASS-Korea
• /
• v.20 no.3
• /
• pp.135-140
• /
• 2015

Flame transfer function is used to determine the relationship between flow fluctuations and heat release perturbations in a lean premixed gas turbine combustor. The characteristics of flame transfer function are known to depend greatly on flame geometries in addition to other various flow conditions. However, it is not easy to experimentally measure the flame transfer function under various actual combustor operating conditions in terms of time and cost. The current research tries to model the flame transfer function using CFD(Computational Fluid Dynamics). From the results, it is shown that the calculated steady flame geometry can be exactly captured with consideration of the wall heat transfer and radiations. Also, unsteady analysis results show the close characteristics of the flame transfer function to the measured one in both gain and phase.

• Culinary science and hospitality research
• /
• v.2
• /
• pp.25-46
• /
• 1996

The clients of hotel desire to be recognized as special persons who have their own personality and self-consciousness. The other hand, The hotel concentrates upon marketing strategy which acts a part of expanding sales. Namely, They find out the need of client, satisfy the desired need, ensure and manage the existing regular customers and make new clients regular customers. So they gain an advantage over competitive hotels. They make strategics of Telemarketing technique which is one of the developed-marketing techniques, can provide distinctive and familiar service and have an hight effect at the low cost. The attractions of Telemarketing strategy can be explained as follows. 1. It is the medium that have cost efficiency. 2. It possesses attractions to do time management. 3. It has control cash flow. 4. It can improve cash flow. 5. Market expansion can be accomplished. 6. It is a medium fit for prospecting over long-term period. 7. It can improve customer relations. 8. It fits seasonality (seasonal sales) 9. It brings greater order volume. 10. It benefits from lower personnel costs. 11. High volume productivity is realized. 12. It has attraction of versatility. 13. It has ease of start-up.

• Journal of Hydrogen and New Energy
• /
• v.22 no.4
• /
• pp.481-487
• /
• 2011

A fuel cell vehicle using a polymer electrolyte membrane fuel cell (PEM FC) as power source produces electric power by consuming the fuel, hydrogen. The unconsumed hydrogen is recirculated and reused to gain higer stack efficiency and to maintain the humidity in the anode side of the stack. So it is needed considering fuel efficiency to recirculated hydrogen. In this study, the indirect hydrogen recirculation flow rate measurement method for fuel cell vehicle is presented. By modeling of a convergent nozzle ejector and a hydrogen recirculation blower for the hydrogen recirculation of a PEM FC, the hydrogen recirculation flow rate was calculated by means of the mass balance and heat balance at Anode In/Outlet.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.12
• /
• pp.1511-1520
• /
• 2004

A flow visualization of the two-dimensional rigid fling-clap motions of the flat-plate wing are performed to gain knowledge of butterfly mechanisms that might be employed by butterflies during flight. In this numerical visualization, the time-dependent Navier-Stokes equations are solved for cyclic fling and clap types of wing motion. The separation vortex pair that is developed in the fling phase of the cyclic fling and clap motion is observed to be stronger than those of the fling followed by clap and pause motion(1st cycle motion). This stronger separation vortex pair in the fling phase is attributable to the separation vortex pair of the outside space developed in the clap phase as it moves into the opening in the following fling phase. Accordingly, higher lift and power expenditure coefficients in the fling after clap phase is caused by the stronger separation vortex pair.

• 한국연소학회:학술대회논문집
• /
• 2006.04a
• /
• pp.128-134
• /
• 2006

A characterization of turbulent reacting flows has proved difficult owing to the complex interaction between turbulence, mixing, and combustion chemistry. There are many types of time scales in turbulent flame which can determine flame structure. This counter jet type premixed burner produces high intensity turbulence. The goal is to gain better insights into the flame structures at high turbulence. 6 propane/air flames gave been studied with high velocity fluctuation in bundle type nozzle and in one hole type nozzle. By measuring velocity fluctuation, turbulent intensity and integral length scale are obtained. And sets of OH LIF images were processed to see flame structure of the mean flame curvatures and flame lengths for comparison with turbulence intensity and turbulent length scales. The results show that the decrease in nozzle size generates smaller flow eddy and mean curvatures of the flame fronts, and a decrease in Damkohler number estimated from flow time scale measurement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.10a
• /
• pp.687-692
• /
• 2011

Experimental analysis has been carried out on noise reduction of subsonic jet flow with chevron nozzle to investigate relationships between geometry variation of chevron nozzles and jet noise reduction. Including base nozzle, seven nozzles are tested at Mach number 0.9. Parametric variables are chevron count, chevron length, and chevron shape. From these experiment, the more chevron count increase, the more jet noise reduction gain. Varying the chevron length, short chevron nozzle increase the jet noise at certain direction all the more. Chevron shape is also considered as important factor to reduce the jet noise.