• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.79-80
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• 2013

YAFFS2는 빠른 마운트와 안정성 등의 이유로 휴대용 기기의 파일 시스템으로 오랫동안 사용되었다. YAFFS2의 복사되는 유효 페이지를 최소화 하고 가비지 콜렉션 효율성을 최대화하기 위해 탐욕 기반 정책을 가진다. 하지만 탐욕 기반 가비지 콜렉션으로 인해 오랫동안 값이 변하지 않는 콜드 데이터를 가진 더티 블록은 가비지 콜렉션 대상 블록으로 선정되지 못하는 문제가 있다. 따라서 본 논문에서는 YAFFS2에서 콜드 데이터를 고려한 가비지 콜렉션 기법을 제안하고 성능 평가를 통해 제안 기법의 우수성을 증명한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.577-583
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• 2004

Optimal parameters were selected to design an inverter circuit that drives a cold cathode fluorescent lamp for LCD backlight using a piezoelectric transformer and it was verified by an experiment. In this paper, the applied inverter topologies are a push-pull type and a half-bridge type, and the dimming control methods of these drive system were used a analog control method and a burst control method each other. When change a control voltage from 2.5V to 4.5V in the analog control method, the brightness 0-100% was seen in current 1-6 mA. And, the input/output efficiency were obtained 90.3%. Also, the control performance of 1-6 mA was seen in duty ratio 5-50% in the burst control method, and the input/output efficiency of the designed inverter got 82.1%.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.1
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• pp.52-59
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• 2010

The conventional CCFL (Cold Cathode Fluorescent Lamp) inverter used in the backlight unit for LCD-TV, composed of the three power stage, can degrade the whole power conversion efficiency. In this paper, a novel scheme to drive the CCFL, composed only of the two power stage without using a dc/dc power stage, is proposed to enhance the whole power conversion efficiency. By adopting the proposed "4-in-1 Transformer", the current balance and the simultaneous ignition among the four CCFL lamp are assured with the one inverter circuit. The proposed scheme features the simple circuit structure, which can save the volume and the cost in the LCD backlight unit. Design considerations are discussed and design procedures are derived. Experimental results of the proposed scheme for 40" LCD-TV are presented to confirm the theoretical analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.8-14
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• 2009

A lamp which is currently employed to LCD(Liquid Crystal Display) Backlight is almost CCFL(Cold Cathod Fluorescent Lamp) and EEFL(External Electrode Fluorescent Lamp). However, the use of these lamps is being restricted as RoHS(the Restriction of the use of certain Hazardous Substances in electrical and electronic equipment) regulation is gradually reinforced. According to this situation, the manufacturing of a lamp which doesn't use mercury is unescapable. Moreover, LCD TV has a defect which take place Motion Blur phenomenon due to response time of LC(Liquid Crystal), and Hold-type characteristic which only exists in LCD differently to CRT, PDP. In this paper, an inverter is proposed to drive a plane light source lamp which is not containing mercury. Driving circuit of proposed inverter is simple because the number of semiconductor device and magnetic device is reduced by using forward topology. Also, Motion Blur phenomenon is decreased by dividing the plane light source lamp to six block along vertical direction, and scanning. Finally, we proved usefulness of proposed inverter through experiment.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.748-753
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• 2011

Generally, in the temperature and environment test of railway electronics, cold and heat resistant tests are involved. Relevant KRS standards describe "There is no problem" as acceptance criteria for function check during the temperature and environment tests. According to this requirement, testers perform some function and performance tests which are easy to perform during test procedure using temperature chamber. This paper reviews the limit of current check method for cold and heat resistant tests and proposes an alternative. An alternative is the application of data sheet. Using data sheet, the temperature of equipped components is checked whether this temperature meet acceptance criteria or not. Also, this paper suggests temperature test range guidelines comparing temperature standards for general IC component. For the example in real field, this method uses the lowest temperature and the highest temperature in major domestic cities.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.477-486
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• 2017

For the analysis of the optical characteristics of electrodeless lamps, all the lamp surface temperatures have been treated the same. However, the interpretation of optical properties in this way has not been sufficient in terms of accuracy. In this paper, to overcome this problem, we divided the inside of the bulb into two parts, hot spot and cold spot, and analyzed the density difference of mercury by different temperatures. Here, it is assumed that the distribution of temperature and density is linear. The effect of optical characteristics through redistribution of hot spot and cold spot density was analyzed. It was also confirmed that the ratio of the density of the redistributed discharge gas has a great influence on the saturation of the optical characteristics. Therefore, it is proved that the design method through the domestic setting is very useful in the actual design, and the method for shortening the time for stabilizing the optical characteristics is obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.32-34
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• 2001

we have quantitatively investigated the possibility of feeding oxygen radical in air environment. The oxygen radical generation from the plasma was verified and its efficiency was found to be dependent on the cathode material by the analysis with optical emission spectroscopy as well as by the quartz crystal micro-balance method.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.7
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• pp.819-825
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• 2014

The diurnal range of temperature in korea is increasing. We know that the environment has deteriorated through report about railway damage and economic loss caused by climate. In these conditions, Monitoring device for railway must operate to support the operations and maintenance. Therefore, In this paper, COM-based monitoring device implemented using Industrial-Extended electronic components and made, We tested compliance about temperature environment of actual railway. We verified through testing about cold and dry heat of monitoring device. Used components in this product will be able to utilize the development of the railway industry of electronics.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.217-220
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• 2001

CaN(gallium nitride) MODFET(modulation doped field effect transistor) large signal model was studied using Modified Materka-Kacprzak large signal MODFET model. using the Dambrine's method［3, at 45MHz-40㎓, Measured S-parameter and DC characteristics. based on measuring results, small signal parameter extraction was conducted. by the cold FET［4］method, measured parasitic elements were de-embedding. Extracted small signal parameters were modeled using modified Materka model, a sort of fitting function reproduce measuring results. to confirm conducted large signal modeling, modeled GaN MODFET's DC, S-parameter and Power characteristics were compared to measured results, respectively. by results were represented comparatively agreement, this paper showed that modified Materka model was useful in the GaN MODFET large signal modeling.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.4
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• pp.262-269
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• 2005

Semiconductor scientists and engineers ideally desire the faster but the cheaper non-volatile memory devices. In practice, no single device satisfies this desire because a faster device is expensive and a cheaper is slow. Therefore, in this paper, we use heterogeneous non-volatile memories and construct an efficient hierarchy for them. First, a small RAM device (e.g., MRAM, FRAM, and PRAM) is used as a write buffer of flash memory devices. Since the buffer is faster and does not have an erase operation, write can be done quickly in the buffer, making the write latency short. Also, if a write is requested to a data stored in the buffer, the write is directly processed in the buffer, reducing one write operation to flash storages. Second, we use many types of flash memories (e.g., SLC and MLC flash memories) in order to reduce the overall storage cost. Specifically, write requests are classified into two types, hot and cold, where hot data is vulnerable to be modified in the near future. Only hot data is stored in the faster SLC flash, while the cold is kept in slower MLC flash or NOR flash. The evaluation results show that the proposed hierarchy is effective at improving the access time of flash memory storages in a cost-effective manner thanks to the locality in memory accesses.