• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1180-1188
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• 2015

In this paper, we propose a new subband quantizer which is a type of quad-tree for applying to digital hologram compression based on Fresenelet transform. After executing Fresnelet transform to the captured digital holgoram, we analyze effect of the designed quantizer for the reconstructed objects from analyzing average energy of each coefficient and visual importance in all subbands. We analyze distribution of coefficient and set dynamic range for each subband, and then design subband quantizer. For enhancing effectiveness of the designed quantize, we adopt a method using the coefficients which are located out of dynamic range, which are named by exception indices. From this, we can obtain more effective quantizer which has higher performance in a range of σ′ = 5.0.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.550-564
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• 2020

Distillation columns are one of the main equipment used for the separation of chemical components in petrochemical process design. However, in spite of the efficient operation in wide range, and the advantage of data collection for equipment verification, the distillation columns are inherently known for high energy consumption and capital cost. Hence, the trade-off analysis needs to be done between investment cost and operation cost to develop the most economical distillation columns. This study was conducted using Aspen Plus, a popular process simulation program, in the pursuit of broad application by as many process engineers as possible. In this paper, design variables for optimization of distillation columns were defined to improve emphatically the design quality with reducing erratic practice of many engineers. In addition, by eliminating unnecessary reviewing step and establishing systematic and efficient procedures, the amount of time for design and human resources were minimized. Aspen Process Economic Analyzers (APEA) program was introduced in order to calculate the investment cost reliably, and the efficient systematic procedure for utilization of APEA was established.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.496-497
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• 2006

90년대에 들어서면서부터 미래원천기술 개발에 필요한 양성자원 및 중성자원의 중요성이 부각됨으로써, 이에 적합한 고에너지(수백 MeV${\sim}$수 GeV) 및 대전류(수십 mA)의 대형 양성자 가속기가 개발되어 반도체 생산, 의료장비 등 여러 분야에 널리 적용되고 있는 추세이다[1, 2]. 이에 양성자 사업단은 21세기 미래 원천기술을 개발하고 산업경쟁력을 제고하며 공공복지를 증진시킬 수 있는 양성자가속기를 개발하여, NT, BT, IT, ST등 중요 국가과학기술분야의 발전기반을 확충하기 위한 프론티어 사업목표로 하고 있으며 이에 부응할 수 있는 양성자 가속기 연구센터 건설계획을 설정하여 추진 중에 있다. 본 논문에서는 양성자 가속기 연구센터 건설계획 과정 중에서 전력설비 설계 방법, 즉 154kV 수전 설비, 직류전원계통, 무정전 전원계통 설비, 접지 및 피뢰설비의 기능 및 특징에 관해 기술하고자 한다.

• KIISE Transactions on Computing Practices
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• v.20 no.11
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• pp.604-609
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• 2014

Decoding processes in portable media players have a high computational cost, resulting in high power consumption by the CPU. If decoding computations are reduced, the power consumed by the CPU is also be reduced, but such a choice generally results in a degradation of the video quality for the users, so it is essential to address this tradeoff. We proposed a new CPU power management scheme that can make use of the scalability property available in the H.164/SVC standard. We first proposed a new video quality model that makes use of a video quality metric(VQM) in order to efficiently take into account the different quantization factors in the SVC. We then propose a new dynamic voltage scaling(DVS) scheme that can selectively combine the previous decoding times and frame sizes in order to accurately predict the next decoding time. We then implemented a scheme on a commercial smartphone and performed a user test in order to examine how users react to the VQM difference. Real measurements show that the proposed scheme uses up to 34% fewer energy than the Linux DVFS governor, and user tests confirm that the degradation in the quality is quite tolerable.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.242.1-242.1
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• 2011

산화물 반도체는 높은 이동도와 낮은 공정 온도, 넓은 밴드갭으로 인한 투명성등 많은 장정을 가지고 있어 최근 많이 연구되고 있다. 그 중에서도 InGaZnO (IGZO)는 In, Ga 함유량으로 박막의 전기적 특성을 쉽게 조절할 수 있고 상온에서 비정질 상태로 증착되어 균일성에 장점이 있다. IGZO 박막을 TFT에 적용 시 MOSFET과는 다르게 축적 상태에서 채널이 형성되기 때문에 산화물 반도체 내에 캐리어 농도는 TFT 특성에 많은 영향을 미친다. 또한, 실리콘 기반의 트랜지스터는 이온 주입 및 확산 공정을 통해서 선택적으로 $10^{20}/cm^3$ 이상의 고농도 도핑을 실시하여 좋은 트랜지스터 특성을 확보할 수 있으나 IGZO 박막에는 이러한 접근이 불가능하다. 따라서 IGZO 박막의 캐리어 농도를 조절할 수 있으면 소스/드레인과 반도체의 접촉 저항 감소 및 전계 효과 이동도등 많은 특성을 개선할 수 있다. 본 연구에서는 UV light를 이용하여 IGZO 박막의 캐리어 농도를 조절하였다. IGZO 박막은 UV light 조사로 인해 Mo와 IGZO박막의 접촉저항이 $3{\times}10^3\;{\Omega}^*cm$에서 $1{\times}10^2\;{\Omega}^*cm$로 감소하였다. 이는 UV 조사로 표면에 금속-OH 결합이 생성되어 IGZO 박막의 캐리어 농도가 ${\sim}5{\times}10^{15}/cm^3$에서 ${\sim}3{\times}10^{17}/cm^3$까지 증가하기 때문이다. 또한 표면에 생성된 OH기는 강한 친수성 성질을 보여주고 표면의 높은 에너지 상태는 Self-Assembly Monolayer (SAM) 공정 적용이 가능 하다. 본 실험에서는 SAM 공정을 적용하여 IGZO-based TFT 제작에 성공하였고, 이 TFT는 UV 조사 시간에 따라 전계 효과 이동도가 0.03 $cm^2/Vs$에서 2.1 $cm^2/Vs$으로 100배 정도 증가하였다.

• Journal of Korea Water Resources Association
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• v.51 no.8
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• pp.665-676
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• 2018

Interrill erosion on a hillslope results from the combined action of the detachment of soil particles by raindrop impact and the sediment transport of surface runoff. This study newly defined the rainfall power which detaches soil particles and the sheet-flow power contributed to sediment transport in terms of energy expenditure rate of soil erosion and presented the effective power equation for interrill erosion by rainfall-induced sheet flow. The rainfall and sheet-flow power was evaluated by factors related with rainfall, slope, and runoff and coefficients of the power equation were analyzed based on references. Futhermore it was confirmed that the relative scales between the rainfall power and the sheet-flow power according to rainfall intensity reflect on the hydrological response and physical process of interrill erosion. From application of the field data for surface runoff and soil erosion it was verified that the rainfall and sheet-flow power is an appropriate equation to estimate a interrill erosion.

• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.9-14
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• 1988

Perovskite type compounds of the $La_{1-x}Ca_xFeO_{3-y}$ system were prepared from stoichiometric mixtures of La_2O_3,\;CaCO_3$, and Fe(NO-3)_3{\cdot}9H_2O$ by heating at 1100$^{\circ}C$ for 24 hours. The crystallographic structures of the solid solutions of all compositions were orthorhombic systems. X-ray diffraction and Mohr salt analysis revealed that at higher y value the phase transition due to vacancy ordering occured and that the lattice volume decreased when the x value was increased. The value of nonstoichiometric ratio y were found to be in the range of $0.0{\sim}0.5$. Electrical conductivities of this systems are measured in temperature range of -100 to 100$^{\circ}C$. Ionic contribution to total conductivity was found from activation energy in the phase containing the open pathway due to vacancy ordering.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.3 s.357
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• pp.43-51
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• 2007

OneNAND flash combines the advantages of NAND and NOR flash, and has become an alternative to the former. But the advanced features of OneNAND flash are not utilized effectively in demand paging systems designed for NAND flash. We propose delayed dual buffering, a demand paging system which fully exploits the random-access I/O interface and dual page buffers of OneNAND flash demand paging system. It effectively reduces the time of page transfer from the OneNAND page buffer to the main memory. On average, it achieves and 28.5% reduction in execution time and 4.4% reduction in paging system energy consumption.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.4
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• pp.80-89
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• 2010

Most of the discussed power efficient routing algorithms, such as LEACH, PEDAP and etc., assume that a base station has infinite resources and there is no traffic limit. However, these assumptions cannot be applied to typical wireless sensor network environments, especially a small sensor network using a normal node as the base station. Moreover, many studies on the wireless sensor networks have not been considering the reverse transmission scheme which transmits data from a sink node to the normal nodes. We propose a bitarray-based reverse routing method which is a power efficient routing algorithm for the wireless sensor networks. The proposed method can be easily implemented by using the tree-based routing scheme and can be worked well with the small memory size for the address of sensor nodes. The experimental result shows that the amount of message transmission of the proposed bitarray-based reverse routing method can be reduced about 61.3% or more compared to the previous methods.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.141-150
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• 2005

Wireless Sensor Networks have been rapidly developed due to the advances of sensor technology and are expected to be applied to various applications in many fields. In Wireless Sensor Networks, schemes for managing the network energy-efficiently are most important. For this purpose, there have been a variety of researches to suggest routing protocols. However, existing researches have ideal assumption that all sensor nodes have sensing data to transmit. In this paper, we designed and implemented a sensing-aware cluster selection algorithm based on LEACH-C for the sensor network in which part of sensors have sensing data. We also simulated proposed algorithm on several network situation and analyzed which situation is suitable for the algorithm. By the simulation result, selecting cluster head among the sensing nodes is most energy-efficient and the result shows application of sensing-awareness in cluster head selection when not all sensors have sensing data.