• 한국토양비료학회지
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• 제45권6호
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• pp.1179-1186
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• 2012

For better understanding of carbon cycle dynamics of an agro-ecosystem, an accurate assessment of seasonal and daily $CO_2$ flux is essential to understand the relationship between various environmental factors and crop productivity. We developed the automatic sliding canopy chamber (ASCC) system that measured continuous net ecosystem productivity (NEP) over whole growing season under the natural meteorological rhythm. The ASCC was composed of two main parts which were sliding part for measuring NEP, and automatic opening and closing chamber (AOCC) for measuring soil respiration (SR) on the soil surface. The ASCC was developed by using open flow method for measuring soil $CO_2$ efflux. The disturbance of natural meteorological condition was minimized by opening the base frames. In the field test with barley (Hordeum vulgare L.), NEP was calculated at $140mg\;CO_2\;m^{-2}h^{-1}$ on a clear day using continuous data and eliminated the possibility of overestimate about 16% using one hour data during the day time. Unlike other small scale chamber system, installation on cropping-field made it possible to take any modifications which might be caused by natural environmental condition.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1510-1512
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• 2004

Platform Screen Door System is a facility on platform to separate platform from track, having automatic sliding door structures interlocked to opening and closing of train door with integrated control unit. When a train comes to a stop at a designed position at a station, onboard ATC/ATO system transmits train berth signal to wayside signaling system. In case of automatic/driverless operation, opening and closing of the Platform Screen Door will be controlled by wayside signaling system. Unfortunately, we often see the case in news that passengers fall into track and their contact with train lead to critical accidents. However, passengers will be free from such accidents on the platform with the Platform Screen Door System. Especially during the rush hours, to ensure passenger's safety and smooth getting on & off, it is necessary to arrange. some station staffs on the platform without the Platform Screen Door System. On the other hand, the Platform Screen Door System will realize such operation by fewer staffs. Due to the above reasons, the Platform Screen Door System is becoming more popular in subway system recently.

• 한국화재소방학회지
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• 제2권1_2호
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• pp.16-24
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• 2001

• KIEAE Journal
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• 제8권6호
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• pp.63-70
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• 2008

Slim floor construction is becoming used throughout many countries. It combines the advantages of flat slab construction with significant inherent resistance to fire. The slim floor system with web openings leads to the reduction of its self-weight. Although the system has enough strength and stiffness, it is necessary to evaluate and improve the effects of dynamic vibration to be able to annoy the residents. Thus, this study evaluates the serviceability of vibration effects based on the dynamic test of five slim composite beams. Based on the experimental results, the initial stiffness and natural frequency of all specimens exhibit the similar trend regardless of the opening and the shape of cross section. The decrease in natural frequency is deeply related to the reduction in the stiffness of specimens and thus, it can be concluded that the damage of slim composite floor can be detected by the measurement of natural frequency instead of the load-carrying capacity and the stiffness.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1488-1493
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• 2004

The purpose of the present work is to develop a compressed air discharging system to eject a projectile from the underwater. For the flow analysis of compressed air tank, projectile ejection tube, and pipe system, the air is assumed as an ideal gas, undergoing 1-dimensional axisymmetric, compressible flow, the Fanno flow analysis was applied. The commercial Fluent code was used to solve 3-D Navier-Stokes equation of the internal flow within the valve. The dynamics of the projectile within the ejection tube was assumed 1-degree of freedom. The calculations were performed to four cases of valve opening area ratio, i.e., 25%, 50%, 75%, and 100% opening area, at both depths of 10m and 50m. The results were shown as the figures of time variation of pressure of the compressed air tank and projectile ejection tube. The velocity and distance of the projectile were also predicted.

• 제어로봇시스템학회논문지
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• 제8권3호
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• pp.275-280
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• 2002

A new algorithm for gradual scene change detection in MPEG based frame sequences is proposed in this paper. The proposed algorithm is based on the fact that most of gradual curves can be characterized by variance distributions of edge information in the frame sequences. Average edge frame sequences are obtained by performing "sober" edge detection. Features are extracted by comparing variances with those of local blocks in the average edge frames. Those features are further processed by the opening operation to obtain smoothing variance curves. The lowest variance in the local frame sequences is chosen as a gradual detection point. Experimental results show that the proposed method provides 85% precision and 86% recall rate fur gradual scene changes.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.404-409
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• 2005

In this paper a 2-stage $CO_2$ cycle was simulated to predict the performance characteristics with operating parameters. The simulation results showed similar tendency compared to the measured system pressure, capacity, COP etc. System characteristics were analyzed with the variations of outdoor temperature and EEV opening. In the simulation, the highest COP was 2.7 at 30-30 Hz and it decreased as compressor frequency increased. Besides, system COP can be increased by optimizing EEV opening.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.439-444
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• 2005

Steady state simulation and dynamic simulation were performed to analyze the operational characteristics of a multi-type refrigeration system, Fully distributed model was adopted to simulate the steady state and transient responses of the system. The main aim was to see the effect of one indoor unit on the other unit. Numerical simulations were carried out for various operation conditions of an indoor unit - secondary fluid inlet temperature, mass flow rate and expansion valve opening. The results showed that the inlet temperature and mass flow rate of the secondary fluid of one indoor unit had minor effect on the operation of the other unit. However, the opening of the expansion valve had significant effect on the performance of the other unit.

• 동력기계공학회지
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• 제14권5호
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• pp.76-82
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• 2010

This paper investigates the optimum operating conditions to construct total automatic control system with high energy efficiency of a newly developed seawater ice machine. The machine has an electronic expansion valve(EEV) and a variable speed rotating drum with an evaporator installed inside. The coefficient of performance(COP) was used as an index to evaluate energy efficiency of the machine. At first, the opening angle of EEV was adjusted to obtain COP of the machine at a constant speed of the drum. Then, we checked seawater ice product versus opening angles of the EEV. Finally, effect of drum's rotating speed in response to product of seawater ice and seawater ice temperature were considered.

• Journal of the Optical Society of Korea
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• 제15권2호
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• pp.146-151
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• 2011

We describe, throughout a Mach-Zehnder interferometric configuration, a new test sieves calibration method based on off-axis digital holography. The experiment is conducted on a test sieve of square openings. The nominal sieve opening is 1.00 mm with maximum individual opening of 1.14 mm in size. The recorded off-axis hologram is numerically processed using Fresnel transforms to obtain an object wave (amplitude and phase). From the reconstructed phase, the average size of the illuminated openings has been measured precisely. The proposed method can provide a real time solution for calibrating test sieves very precisely and with moderate accuracy.