• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1100-1106
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• 2010

LED는 온도가 일정이상 올라가면 효율이 떨어지고 수명이 짧아지는 단점이 있다. 본 연구는 이러한 LED의 효율적인 온도제어에 대한 것이다. LED의 방열을 위해 방열판과 팬을 사용하고 시스템의 온도제어는 원칩 마이크로프로세서와 PID제어를 통해 원하는 온도를 제어할 수 있음을 실험을 통해 확인한다. 궁극적으로 팬을 냉각장치로 사용하고 이를 잘 제어하면 LED 시스템 구동전력의 약 2%만을 사용하여 적절한 조도와 온도를 유지하는 성능을 얻을 수 있음을 제어실험을 통해 확인하였다.

• Journal of Power Electronics
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• 제13권4호
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• pp.569-583
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• 2013

In this study, the simultaneous use of a multi-level converter (MLC) as a DC-motor drive and as an active battery cell balancer is investigated. MLCs allow each battery cell in a battery pack to be independently switched on and off, thereby enabling the potential non-uniform use of battery cells. By exploiting this property and the brake regeneration phases in the drive cycle, MLCs can balance both the state of charge (SoC) and temperature differences between cells, which are two known causes of battery wear, even without reciprocating the coolant flow inside the pack. The optimal control policy (OP) that considers both battery pack temperature and SoC dynamics is studied in detail based on the assumption that information on the state of each cell, the schedule of reciprocating air flow and the future driving profile are perfectly known. Results show that OP provides significant reductions in temperature and in SoC deviations compared with the uniform use of all cells even with uni-directional coolant flow. Thus, reciprocating coolant flow is a redundant function for a MLC-based cell balancer. A specific contribution of this paper is the derivation of a state-space electro-thermal model of a battery submodule for both uni-directional and reciprocating coolant flows under the switching action of MLC, resulting in OP being derived by the solution of a convex optimization problem.

• Journal of Genetic Medicine
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• 제13권1호
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• pp.1-13
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• 2016

Although some mutations are beneficial and are the driving force behind evolution, it is important to maintain DNA integrity and stability because it contains genetic information. However, in the oxygen-rich environment we live in, the DNA molecule is under constant threat from endogenous or exogenous insults. DNA damage could trigger the DNA damage response (DDR), which involves DNA repair, the regulation of cell cycle checkpoints, and the induction of programmed cell death or senescence. Dysregulation of these physiological responses to DNA damage causes developmental defects, neurological defects, premature aging, infertility, immune system defects, and tumors in humans. Some human syndromes are characterized by unique neurological phenotypes including microcephaly, mental retardation, ataxia, neurodegeneration, and neuropathy, suggesting a direct link between genomic instability resulting from defective DDR and neuropathology. In this review, rare human genetic disorders related to abnormal DDR and damage repair with neural defects will be discussed.

• 한국유체기계학회 논문집
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• 제18권3호
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• pp.26-32
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• 2015

The authors are developing a motion of floater body type wave energy converter of the float-counterweight system. This consists of the driving pulley, wire, float and counterweight suspended from idler pulleys and rachet mechanism. Though it has succeeded in solving the major structural strength problem in which the floats would slam against adjacent structure(s) by wave load acting horizontally. In order to overcome this problem. We propose a new system in which the wire transmitting the power is wound around the pulleys and the float receiving the wave power is pulled by the wire from both its upper and lower ends to avoid the occurrence of slackening during the wave cycle. In the paper, we developed the dynamics model for the proposed system. Energy gain has been calculated for realistic wave conditions and compared with the original float-counterweight device. The important differences from the float-counterweight system are that (1) both upward and downward motions of water surface can be utilized without problem. (2) slackening of energy gain and wire tension are effectively suppressed, and (4) for the same time averaged energy gain, the maximum wire tension is fairly lowered.

• Journal of Welding and Joining
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• 제20권5호
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• pp.78-86
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• 2002

A metallurgical model for the prediction of prior austenite grain size considering the dissolution kinetics of M$_3$C precipitates at the heat affected zone of SA508-cl.3 was proposed. The isothermal kinetics of grain growth and dissolution were respectively described by well-known equation, $dD/dT=M({\Delta}F_{eff})^M$ and Whelan's analytical model. The isothermal grain growth experiments were carried out for measure the kinetic parameters of grain growth. The precipitates of the base metal and the specimens exposed to thermal cycle were examined by TEM-carbon extraction replica method. The model was assessed by the comparison of BUE simulation experiments and showed good consistencies. However, there was no difference between the model considering and ignoring $M_3C$ precipitates. It seems considered that pinning force exerted by $M_3C$ Precipitates was lower than driving force for grain growth due to large size and small fraction of precipitates, and mobility of grain boundary was low in the lower temperature range.

• 대한인간공학회지
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• 제30권5호
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• pp.589-595
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• 2011

Objective: This study compares two visual occlusion methods for the evaluation of in-vehicle interfaces. Background: Visual occlusion is a visual demand measuring technique which uses periodic vision/occlusion cycle to simulate a driving(or mobile) environment. It has been widely used for the evaluation of in-vehicle interfaces. There are two major implementation methods for this technique: (1) occlusion using PLATO(portable liquid crystal apparatus for tachistoscopic occlusion) goggles; (2) occlusion using a software application on a touchscreen device. Method: An experiment was conducted to examine the visual demand of an in-vehicle interface prototype using the goggle-based and the touchscreen-based occlusion methods. Address input and radio tuning tasks were evaluated in the experiment. Results: The results showed that, for the radio tuning task, there were no significant differences in total shutter open time and resumability ratio between the two occlusionconditions. However, it took longer for the participants to input addresses with the touchscreen-based occlusion. Conclusion & Application: The results suggest that touchscreen-based method could be used as an alternative to traditional, gogglebased visual occlusion especially in less demanding visual tasks such as radio tuning.

• 한국분무공학회지
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• 제22권1호
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• pp.8-12
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• 2017

Recently, manufacture and sales of passenger car with GDI (Gasoline Direct injection) were dramatically increased in Korea. In this study, investigation on the exhaust emission characteristics of GDI vehicles according to mileage were conducted by using chassis dynamometer and emission analyzer. Test cars selected 5 types with G4FD engine (1600 cc) and emissions of total 14 vehicles analyzed. Measurement and evaluation on emissions (CO, NOx, NMOG, $CO_2$) characteristics of GDI vehicles with mileages from 40,000 to 80,000 km in certification driving cycle (CVS-75) were carried out in this study. It is revealed that emission results of all test cars shows below emission standard, NMOG emission value of about 80,000 km doubled that of 40,000 km and emission increased by accumulated mileage. Also, increasing pattern of NOx emissions shows when the vehicle mileages was increased and $CO_2$ emission increasing trend obviously do not show according to mileages.

• Journal of information and communication convergence engineering
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• 제11권4호
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• pp.247-252
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• 2013

An intelligent light emitting diode (LED) dimming system is designed and implemented for energy-saving lighting systems. An LED light bulb is powered by an LED driver controlled by a microcontroller using pulse width modulation (PWM) signals. By changing the duty cycle of the PWM signals, the LED driver generates a driving current of up to 1,000 mA. The current consumption by the LED light bulb exhibits a very linear characteristic that indicates that the level of LED dimming can be finely tuned. Multiple sensors-lighting intensity and ultrasonic range sensors-are combined with the LED dimming system to realize an automatically controllable LED lighting system. The light intensity sensor is capable of sensing ambient light. The ultrasonic range sensor can detect objects from 0.15 to 5.6 m at a resolution of 0.0254 m. The collected information by the light intensity and ultrasonic range sensors is processed by the microcontroller that in turn automatically controls the brightness of the LED light bulb. The algorithm of the software for the LED dimming system is also described.

• 전력전자학회논문지
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• 제15권6호
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• pp.487-497
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• 2010

본 논문에서는 직렬형 하이브리드 자동차의 운전특성을 분석하기 위한 PSIM 시뮬레이터의 개발에 대하여 기술한다. 직렬형 하이브리드 자동차는 엔진이 전동기와 전기적으로 결합되어 있으며 전동기의 출력에 의해서만 구동된다. 엔진/발전기, 전동기, 기어와 같은 파워트레인 각 구성요소들의 정격은 에너지 개념을 이용한 시스템과 Electrical Peaking Hybrid (ELPH)를 이용하여 모델링할 수 있는데, 설계된 하이브리드 자동차를 개발된 PSIM 시뮬레이터를 이용하여 특정 운전주기 하에서 평가하고 분석하였다. 기계적 제동이 사용되는 경우와 회생제동이 사용되는 경우 각각에 대하여 전동기의 평균 입력을 비교하였으며 시뮬레이션 결과를 바탕으로 직렬형 하이브리드 자동차의 연비를 분석하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.860-866
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• 2009

It is very important to choose optimal material having good corrosion resistance and capabilities for the part materials such as the automotive exhaust system under a hot salt corrosion atmosphere. Generally, two types of corrosion come into the automotive exhaust system. One is 'Condensate Corrosion', which is occurred by exhaust gas condensate formed at the inner surface of exhaust system heated up during driving, which results in the acid condensate pitting. The other is 'High Temperature Salt Corrosion' occurring from the interaction between the chloride ion coming from salt at the seaside district or snow salt and the outer surface of exhaust system. By the corrosion attack, the main muffler is firstly damaged and the life cycle of an automobile is significantly decreased. It has been investigated that the hot salt corrosion properties of a STS 409L and 436L ferritic stainless steels which are well-known for the materials of the automotive exhaust system. In addition, the corrosion properties of hot dip aluminum coated STS 409L have been compared with uncoated steels. Aluminum coated STS 409L showed a superior corrosion resistance than uncoated STS 409L, and futhermore showed a better corrosion resistance than a STS 436L, which is an expensive ferritic stainless steel having a excellent corrosion resistance caused from more chromium content of an alloying element.