• 한국산학기술학회논문지
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• 제10권12호
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• pp.3614-3621
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• 2009

본 논문에서는 이득 및 주파수 특성이 개선된 CMOS 저전압 전류모드 적분기가 설계되었다. 설계된 전류모드 적분기는 본 논문에서 새롭게 제안한 선형 캐스코드 회로를 기본으로 구성되었다. 제안된 전류모드 적분기는 기존의 전류미러형 전류모드 적분기의 이득(43.7dB) 및 단위이득주파수(15.2MHz) 비해서 높은 전류이득(47.8dB) 및 단위 이득 주파수(27.8MHz)의 특성을 얻을 수 있었다. 제안된 전류모드 적분기의 응용회로로써 차단주파수 7.03MHz를 갖는 5차 체비세프 저역통과 필터를 설계하였다. 설계된 모든 회로들은 1.8V-$0.18{\mu}m$ CMOS 공정파라메터로써 HSPICE를 이용하여 시뮬레이션되었다.

• 대한전자공학회논문지SD
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• 제45권8호
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• pp.37-43
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• 2008

본 논문에서는 고속 동작에서 동적 전력 소비와 정적 전력 소비를 동시에 줄일 수 있는 self-timed current-mode Logic(STCML)을 제안한다. 제안된 로직 스타일은 펄스 신호로 가상 접지를 방전하여 로직 게이트의 누설 전류(subthreshold leakage current)를 획기적으로 감소시켰다. 또한, 본 로직은 개선된 self-timing buffer를 사용하여 동적모드 동작 시 발생되는 단락 회로 전류(short-circuit current)를 최소화하였다. 80-nm CMOS 공정을 이용하여 실시한 비교 실험 결과, 제안된 로직 스타일은 기존의 대표적인 current-mode logic인 DyCML에 비하여 동일한 시간 지연에서 26 배의 누설 전력 소비를 줄이고 27%의 동적 전력 소비를 줄일 수 있었다. 또한, 대표적인 디지털 로직 스타일인 DCVS와의 비교 결과, 59%의 누설 전력 소비감소 효과가 있었다.

• 대한임베디드공학회논문지
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• 제12권3호
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• pp.121-130
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• 2017

NAND flash memory has advantages of non-volatility, little power consumption and fast access time. However, it suffers from inability that does not provide to update-in-place and the erase cycle is limited. Moreover, the unit of read/write operation is a page and the unit of erase operation is a block. Therefore, erase operation is slower than other operations. The AGC, the proposed garbage collection policy focuses on not only garbage collection time reduction for real-time guarantee but also wear-leveling for a flash memory lifetime. In order to achieve above goals, we define three garbage collection operating modes: Fast Mode, Smart Mode, and Wear-leveling Mode. The proposed policy decides the garbage collection mode depending on system CPU usage rate. Fast Mode selects the dirtiest block as victim block to minimize the erase operation time. However, Smart Mode selects the victim block by reflecting the invalid page number and block erase count to minimizing the erase operation time and deviation of block erase count. Wear-leveling Mode operates similar to Smart Mode and it makes groups and relocates the pages which has the similar update time. We implemented the proposed policy and measured the performance compare with the existing policies. Simulation results show that the proposed policy performs better than Cost-benefit policy with the 55% reduction in the operation time. Also, it performs better than Greedy policy with the 87% reduction in the deviation of erase count. Most of all, the proposed policy works adaptively according to the CPU usage rate, and guarantees the real-time performance of the system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.288-293
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• 2008

The cooling load in winter is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. The development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the performance of a multi-heat pump with 3-piping system was investigated as a function of refrigerant charge and its performance was analyzed in cooling mode, heating mode, and heat recovery mode. COP in the heating or cooling mode showed little dependence on refrigerant charge at overcharge conditions, while those were strongly dependent on refrigerant charge at undercharge conditions and outdoor inlet temperature. In the heat recovery mode, the performance of the system was very sensitive to charge amount at all conditions. Optimum charge amount in the heat recovery mode was 14% lower than that in the cooling mode at the standard condition because the refrigerant only passed the indoor units. It is required to store the excessive refrigerant charge in a storage tank to optimize the system performance at operating modes.

• 한국위성정보통신학회논문지
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• 제9권2호
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• pp.74-79
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• 2014

전통적인 스캔모드는 과거 Envisat이나 Radarsat 위성 등에서 사용되면서 환경 감시 및 관측 분야에 높은 효율성을 지닌 영상 획득을 수행하였으나 해상도의 저하 및 안테나 패턴의 왜곡으로 인해 영상 품질 저하 문제가 지적되어왔다. 최근 이러한 스캔 모드 영상의 단점을 극복하기 위한 새로운 운용 모드로서 TOPS SAR 기법이 제안되어 운용단계에 접어들었다. TOPS 모드는 단일 위성에서 높은 품질의 광역 관측 레이더 영상을 제공하지만 이를 실제로 구현하기 위해서는 매우 복잡한 시스템 설계 능력이 요구된다. 본 논문에서는 TOPS 모드의 원리에 대해 소개하고, 모의 실험을 통하여 TOPS 모드의 동작을 구현한다. SAR 원시데이터를 가상으로 생성한 후 방위방향 안테나 패턴을 스캔 모드와 비교하여 TOPS 모드에서 스캔모드의 단점인 영상 품질 왜곡이 억제됨을 보인다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.595-600
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• 2011

This study analyzed passenger's access modes that connect to regional railway station and developed a model of access mode choice based on transit smart card data of Seoul station as a case study. The study boundary includes sixteen bus stops around the station. The results show that most passengers access to station have less than two transfers. Of total 15000, eighty percent of passengers use metro and the rest of people take a bus. Interestingly, it is found that almost same proportions of passengers use metro and bus for egress the station. Consequently, metro is found to be most likely used mode compared to bus for both access and egress trips.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.443-448
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• 2005

This paper proposed a regeneration inverter system, which can regenerate the excessive power form dc bus line to ac source for traction system. The proposed regeneration inverter system for dc traction can reduce harmonics which are include to ac current source. The regenerative inverter is operated as two modes. As a regeneration inverter mode, it can recycle regenerative energy caused by decelerating tractions and as an active power filter mode, it can compensate for harmonic distortion produced by the rectifier substation. In the paper, a regeneration inverter used PWM DC/AC converter algorithm. And an active power filter used p-q theory. The simulation was composed as a prototype model[3kW]. Simulation results show that two algorithm can be used to real model[100kW]. Finally, the inverter was successfully operated as regeneration mode.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1842-1847
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• 2007

In this study, we are to analyze the life and the main failure mode of flexible tubes fitting for pneumatic that are usually applied in the factory automation line. Flexible tubes fitting for pneumatic have complicated failure cause because they are organized as a complex of various elements. Therefore, in this paper, we analyzed the main failure mode of flexible tubes fitting for pneumatic, and then performed life test and performance test according to the international standards. On the basis of these processes, we estimate shape parameter that is the main factor for the calculation of test time for the reliability of flexible tubes fitting for pneumatic and their data analysis of life distribution.

• Journal of information and communication convergence engineering
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• 제9권2호
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• pp.129-134
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• 2011

Nowadays, most of exhibits are material antiquities while the exhibit of intangible cultural heritage is deficient and the form is less advanced which cannot meet the exhibition needs of digital times. This has resulted in insufficient display of intangible heritage's value which may not facilitate inherit and protection of intangible heritage, no other than protection mechanism of forming healthy industrialization. This article has established digital exhibition mode in museum about intangible cultural heritage by analysis on current museum and using mobile communication and augmented reality techniques. Discuss the mode in the layer integrating creative industry and mobile industry and provide practicable reference project of forming the healthy industrialization mechanism for protecting intangible heritage.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.638-641
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• 2002

This paper presents design and construct of flat type step-down piezoelectric transformer for the application to AC-adapters. This piezoelectric transformer operated in resonance vibration mode. In this paper, Finite element method(FEM) was used for analysis piezoelectric transformers. Vibration mode and electric field of piezoelectric transformer at resonance frequency were simulated. Using this simulation, we manufactured flat type piezoelecric transformer and measured its output characteristics. As results, output power was linearly increased by increasing input power at resonance frequency. And it was found that the transformer exhibited an output power of 11.4[W] at 60[V] input voltage. From these results, we expect that this piezoelecric transformer can be applied to AC adapters.