• 조명전기설비학회논문지
• /
• 제28권7호
• /
• pp.1-12
• /
• 2014

This paper is proposed to design the new heat-sink apparatus for improving the heat transfer characteristics in the power LED chip, and results of the operation characteristics were discussed. The core design is that the soldering through-hole on the FR-4 PCB board is formed to the effective heat transfer. That is directly filled with Ag-nano materials, which shows the high thermal conductivity. The heat transfer medium consisting of Ag-nano materials is classified into two structures. Mediums are called as the heat slug and the multi-pin in this work. The heat of the high temperature generated from the LED chip was directly transferred to the heat slug of the one large size. And the accumulated heat from the heat slug was quickly dissipated by the medium of the multi-pin, which is the same body with the heat slug. This multi-pin was designed for the multi-dissipation of heat by increasing the surface areas with a little pins. Subsequently, the speed of the heat transfer with this new heat-sink apparatus is three times faster than the conventional heat-sink. Therefore, the efficiency of the illuminating light will be improved by adapting this new heat-sink apparatus in the large area's LED.

• 한국통신학회논문지
• /
• 제38C권8호
• /
• pp.725-732
• /
• 2013

최근 LED의 저전력, 장수명, 동작 속도, 제어성, 고품질의 색 연출성, 지속 가능성 등의 이유로, LED 응용 분야가 확대되고 있다. 그러나 고출력 LED 조명 시스템을 구현하는데 있어, 방열은 큰 걸림돌이 되고 있다. 본 논문에서는 고출력 투광등 설계를 위한 방열 방안으로 메탈 PCB 설계, 열전 소자, 히트 파이프, 방열판, 팬(fan) 등의 적층 연동 구조를 제안하고 구현 방안을 제시하였다. 아울러 본 논문에서는 RS-485 통신을 통한 DMX512 프로토콜 기반 LED 조명 시스템 제어 방안을 제시하였다. DMX512 프로토콜은 조명장치와 조명제어 모듈의 연결에 대한 사실상 세계적 표준이며 이를 활용한 무대 조명이나 경관 조명 시스템 개발이 지속적으로 이루지고 있다. 본 논문에서는 이를 이용한 LED 조명 제어 및 응용 기술을 소개하고 주제어기를 무선으로 원격 제어하는 방안을 제안하였다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2009년도 제33회 추계학술대회논문집
• /
• pp.93-96
• /
• 2009

고속 비행기술의 발전과 엔진효율의 향상은 비행체와 엔진의 열적부하를 증가시킨다. 극초음속까지 비행체의 속도가 빨라지면 공기흐름을 이용한 냉각이 어렵기 때문에 항공유를 주요 냉각제로서 사용하게 된다. 연료가 열 흡수원(Heat sink)으로서 사용될 때 열분해반응 또는 촉매분해반응과 같은 흡열반응(Endothermic reaction)을 거쳐 분해가 되는데 이러한 특성을 지닌 연료를 흡열연료(Endothermic fuels)라고 한다. 흡열반응은 촉매를 통해 개선될 수 있지만, 코킹침적이 형성되기 이전까지의 온도로 제한된다. 본 연구에서는 흡열연료에 관련된 주요 기술을 조사하여 기초연구에 활용하고자 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권9호
• /
• pp.3396-3411
• /
• 2015

Sensors used in Wireless Sensor Networks (WSN) have mostly limited capacity which affects the performance of their applications. One of the data-gathering methods is to use mobile sinks to visit these sensors so that they can save their limited battery energies from forwarding data packages to static sinks. The main disadvantage of employing mobile sinks is the delay of data collection due to relative low speed of mobile sinks. Since sensors have very limited memory capacities, whenever a mobile sink is too late to visit a sensor, that sensor's memory would be full, which is called a 'memory overflow', and thus, needs to be purged, which causes loss of collected data. In this work, a method is proposed to generate mobile sink tours, such that the number of overflows and the amount of lost data are minimized. Moreover, the proposed method does not need either the sensor locations or sensor memory status in advance. Hence, the overhead stemmed from the information exchange of these requirements are avoided. The proposed method is compared with a previously published heuristic. The simulation experiment results show the success of the proposed method over the rival heuristic with respect to the considered metrics under various parameters.

• 한국기계가공학회지
• /
• 제16권5호
• /
• pp.150-156
• /
• 2017

This study tests the characteristics of heat radiation by applying the pin-height variables to 30-W LED floodlights. The angle of the heat sink enables us to identify the characteristics of the heat radiation based on the temperature distribution. The results of the study are as follows. When the heat sinks are set towards the ground, the heat transfer decreases in speed only to expands the temperature distribution, which adversely affects the characteristics of heat radiation and expands the temperature distribution of PCB with the LED chip. We verify that the characteristics of heat radiation are adversely affected when the height of the cooling pin decreases and the heat radiation area decreases, which impedes the heat transfer and increases the temperature distribution on the heat sink.

• Advances in Computational Design
• /
• 제6권1호
• /
• pp.31-42
• /
• 2021

This research aims to demonstrate the optimal geometrical design of splayed multiple cross-sectional pin fin heat sinks (SMCSPFHS), which are a type of side-inlet-side-outlet heat sink (SISOHS). The optimiser strength Pareto evolutionary algorithm2 (SPEA2)is employed to explore a set of Pareto optimalsolutions. Objective functions are the fan pumping power and junction temperature. Function evaluations can be accomplished using computational fluid dynamics(CFD) analysis. Design variablesinclude pin cross-sectional areas, the number of fins, fin pitch, thickness of heatsink base, inlet air speed, fin heights, and fin orientations with respect to the base. Design constraints are defined in such a way as to make a heat sink usable and easy to manufacture. The optimum results obtained from SPEA2 are compared with the straight pin fin design results obtained from hybrid population-based incremental learning and differential evolution (PBIL-DE), SPEA2, and an unrestricted population size evolutionary multiobjective optimisation algorithm (UPSEMOA). The results indicate that the splayed pin-fin design using SPEA2 issuperiorto those reported in the literature.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
• /
• pp.177-186
• /
• 2006

Flame surface area is a critical parameter determining turbulent flame speed. Three-dimensionaldirect numerical simulations (DNS) were conducted to figure out the evolution process of flame surface area. Fully compressible Navier-Stokes equations are solved to reproduce premixed flame embedded in isotropic decaying turbulent flow. The tangential straining and curvature of propagating surface affect development of flame area. In this study, four different turbulent intensity flows and three different Le number flames are investigated to force changes in straining and curvature effects. Consistent results are obtained for the probability density functions (PDF) of strain and curvature with previous researches. It is revealed that displacement speed, which is a speed of flame surface relative to unburnt flow, controls the balance between sink and source of flame surface area.

• 한국연소학회지
• /
• 제12권2호
• /
• pp.10-19
• /
• 2007

Flame surface area is a critical parameter determining turbulent flame speed. Three-dimensional direct numerical simulations(DNS) were conducted to figure out the evolution process of flame surface area. Fully compressible Navier-Stokes equations are solved to reproduce premixed flame embedded in isotropic decaying turbulent flow. The tangential straining and curvature of propagating surface affect development of flame area. In this study, four different turbulent intensity flows and three different Le number flames are investigated to force changes in straining and curvature effects. Consistent results are obtained for the probability density functions (PDF) of strain and curvature with previous researches. It is revealed that displacement speed, which is a speed of flame surface relative to unburnt flow, controls the balance between sink and source of flame surface area.

• ETRI Journal
• /
• 제38권4호
• /
• pp.645-653
• /
• 2016

This paper demonstrates the performance of a metal-substrate power module with multiple fabricated chips for a high current electrical application, and evaluates the proposed module using a 1.5-kW sinusoidal brushless direct current (BLDC) motor. Specifically, the power module has a hybrid structure employing a single-layer heat-sink extensible metal board (Al board). A fabricated motor driver IC and trench gate DMOSFET (TDMOSFET) are implemented on the Al board, and the proper heat-sink size was designed under the operating conditions. The fabricated motor driver IC mainly operates as a speed controller under various load conditions, and as a multi-phase gate driver using an N-ch silicon MOSFET high-side drive scheme. A fabricated power TDMOSFET is also included in the fabricated power module for three-phase inverter operation. Using this proposed module, a BLDC motor is operated and evaluated under various pulse load tests, and our module is compared with a commercial MOSFET module in terms of the system efficiency and input current.

• 한국군사과학기술학회지
• /
• 제13권5호
• /
• pp.941-949
• /
• 2010

The present study investigated the swimming pattern and appendage postures of a copepod species, Calanus sinicus, which prevails in the south-east sea of the Korean peninsula, by employing a digital holographic particle tracking velocimetry(PTV) technique. The results showed that the copepod Calanus sinicus had various swimming patterns such as hover, hop, sink, cruise, and downward cruise. Most frequent pattern was the 'hop and sink'. The average swimming speeds ranged from 1.1 to 45.7 body-lengths/s, and the corresponding flow Reynolds number ranged from $10^0$ to $10^2$.