• 연구논문집
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• s.30
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• pp.15-23
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• 2000

In this study, develop the thermal pump using water evaporation and condensation. Vapor from heating room moves up to pumping room and press the water of pumping room. Consequently water is pumped out to water tank. Then hot vapor direct contact with cold water in condensing room after pumping process. At this time, pressure of condensing room is down to-5kPa and suck in water of tank. This pump executes self ping and good durability because of no mechanical moving parts. Thermal pump is pumped cyclic so that, this pump is not used single. Therefore thermal pump of hot water boiler used to multi-stage for stable pumping rate. As the result of performance test, the developed thermal pump proves pumping action of water evaporation/condensation. And total volume flow rate is 500liter during one hour. If three thermal pump is installed parallel, this pump can use to the hot water boiler in the 300,000kcal/h class.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.170-175
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• 2009

Shock focusing is related with explosive release of shock wave energy on a narrow spot in a short duration of time triggering a spontaneous high pressure near the focal point. It is well known that reflection of planar incident shock wave from the metallic concave mirror such as ellipsoidal, paraboloidal or hemispherical cavities will focus on a focal point. We intend to improve the computational results using a wave propagation algorithm and to resolve the mushroom-like structure. For computation of the concave cavity flow, it is not easy to use a single-block mesh because of the many singular points in geometry and coordinates. We have employed a uniform Cartesian-grid method for the wave propagation algorithm.

• Journal of Korea Multimedia Society
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• v.19 no.4
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• pp.765-773
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• 2016

As multimedia content technology developed, there are many cases that service contents are being provided in many different ways in the cloud-based media service system. A DRM is a technology that can enhance the copyright of the digital content by providing right information. It is available on a single platform and has a problem that the additional cost when the platform is changing. In this paper, we propose a media service system based on cloud computing. It can be used on multiple platforms at the same time by applying a number of DRM for digital contents, and allows use of a new authentication for another platform without any additional cost.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.23-26
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• 2003

An ultrasonic motor is a motor which uses vibration -a type of elastic vibration- to obtain a driving force, which then drives the motor using friction. In this paper, mode conversion type - single resonance mode ultrasonic rotary motor that use langevin type ultrasonic vibrator was studied. This model was proposed for the first time by Japanese Kumada in 1985. In this study, finite element analysis (FEA) of a stator and bidirectional driving characteristic of a rotor was newly obtained. The amplitude and phase of displacement and elliptical trajectory of beam was confirmed by FEA The fabricated motor was operated to clockwise and counterclockwise in 40.8 [kHz] and 44.2 [kHz] respectively. But bidirectional driving characteristics did not coincide each other.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.249-250
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• 2021

The use of smart equipment such as drones is increasing in construction sites. In particular, there are frequent cases where two or more drones must be used at the same time. This leads to different considerations than when operating a single unit. This study aims to analyze the requirements to be considered in the case of the operation of drones that monitor fine dust and drones that reduce fine dust in order to reduce fine dust generated in construction sites.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1416-1418
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• 2004

This paper proposes an image processing algorithm for detecting obstacles on road-lane using DLI(disparity of lane-related information) that is generated by stereo images acquired from dual cameras mounted on a moving vehicle. The DLI is a disparity that is acquired using single lane information from road lane detection. For the purpose to reduce processing time, we use small blocks obtained by edge-histogram based blocking logic. This algorithm detects moving objects such as preceding vehicles and obstacles. The proposed algorithm has been implemented in a personal computer with the road image data of a typical highway. We successfully performed experiments under a wide variety of road conditions without changing parameter values or adding human intervention. Experimental results also showed that the proposed DLI is quite successful.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.121-124
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• 2004

In this paper, Simple and inexpensive analog maximum power point tracker (MPPT) algorithm for photovoltaic power system and low power system of doesn't use digital signal processor (DSP). The control circuit is composed such that the actual current and voltage are sensed directly from the PV array. These two signals are then multiplied by a single-chip multiplier. The multiplier output go through different time constants genesis pulse width modulated to switch. Finally those were verified through simulation.

• Journal of applied mathematics & informatics
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• v.6 no.3
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• pp.943-952
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• 1999

Models of single-server queues with vacation have been widely used to study the performance of many computer communica-tion and production system. In this paper we use the formula for a wide class of vacation policies and multiple types of vacations based on the M/G/1 queue with generalized vacations and exhaustive service. furthermore we derive the waiting times for many complex vacation policies which would otherwise be to analyze. These new results are also applicable to other related queueing models. if they conform with the basic model considered in this paper.

• ETRI Journal
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• v.33 no.4
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• pp.641-644
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• 2011

In this letter, we propose a novel bitrate control, using both Kalman and FIR filters, based on a Hamiltonian analysis with respect to the amount of bits from each macroblock, in an encoding of a general video codec such as H.264/AVC. Since the proposed bitrate control is based on the simple computation of an optimal control method based on the Hamiltonian analysis, it is not necessary to use additional computation, such as a DCT or quantization, to estimate the bits for bitrate control. As a result, the proposed algorithm can be applied to single-pass encoding and can provide sufficient encoding speed with respect to various applications, even those requiring real-time control.

• Transactions of the Society of Information Storage Systems
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• v.10 no.2
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• pp.55-60
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• 2014

Laser projector has many advantages of high brightness, high resolution and small size, but the huge drawback of image degradation called speckle which generated by coherence of laser and roughness of surface interrupts their general use. There are many methods to reduce speckle pattern, but they need effective optical systems to realize display to the far field with huge volume. We designed speckle reduction element by using microlens with controlled curvature to reduce spatial coherence. Vibration element was also applied to reduce temporal coherence which considered response time of eye. Designed element was fabricated by simple reflow method and imprinting method. From the results, the fabricated element performed 48.33% of speckle reduction efficiency and 41.29% of optical efficiency with a single doublet lens.