• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.372-373
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• 2019

본 논문은 다중 권선 결합 인덕터를 이용한 능동 셀 밸런싱 회로의 밸런싱 속도를 향상시킬 수 있는 새로운 동작 모드를 제안한다. 다중 권선 결합 인덕터를 사용한 능동 셀 밸런싱 회로는 두 셀이 하나의 결합 인덕터 권선을 공유하며, 셀과 결합 인덕터 사이의 연결을 제어하기 위해 셀당 하나의 스위치가 사용된다. 이 회로는 비교적 높은 전압을 갖는 소스 셀에 저장된 에너지를 결합 인덕터에 저장한 뒤, 그 에너지를 목표 셀로 전달하는 방식으로 셀 밸런싱을 수행한다. 하지만, 회로 구조상서로 다른 권선을 공유하고, 동일한 위치에 연결된 셀 간 밸런싱을 수행할 경우, 두 번의 에너지 전달 과정을 통해 목표 셀로 에너지가 전달 되게 된다. 이는 에너지 전달 경로를 증가시키므로 회로의 효율과 셀 밸런싱 속도를 크게 저하시킨다. 본 논문은 위의 셀 조건에서 에너지 전달 경로를 단축시켜 셀 밸런싱 속도를 향상시킬 수 있는 새로운 동작 모드를 제안한다. 새로운 동작 모드 성능은 15W급 시작품을 이용하여 검증되었다.

• Journal of Intelligence and Information Systems
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• v.29 no.1
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• pp.107-119
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• 2023

The technology that recognizes a soldier's motion and movement status has recently attracted large attention as a combination of wearable technology and artificial intelligence, which is expected to upend the paradigm of troop management. The accuracy of state determination should be maintained at a high-end level to make sure of the expected vital functions both in a training situation; an evaluation and solution provision for each individual's motion, and in a combat situation; overall enhancement in managing troops. However, when input data is given as a timer series or sequence, existing feedforward networks would show overt limitations in maximizing classification performance. Since human behavior data (3-axis accelerations and 3-axis angular velocities) handled for military motion recognition requires the process of analyzing its time-dependent characteristics, this study proposes a high-performance data-driven classifier which utilizes the long-short term memory to identify the order dependence of acquired data, learning to classify eight representative military operations (Sitting, Standing, Walking, Running, Ascending, Descending, Low Crawl, and High Crawl). Since the accuracy is highly dependent on a network's learning conditions and variables, manual adjustment may neither be cost-effective nor guarantee optimal results during learning. Therefore, in this study, we optimized hyperparameters using Bayesian optimization for maximized generalization performance. As a result, the final architecture could reduce the error rate by 62.56% compared to the existing network with a similar number of learnable parameters, with the final accuracy of 98.39% for various military operations.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.607-607
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• 2013

차세대 비휘발성 메모리 소자로서 각광받고 있는 저항 변화 메모리(resistive switching random access memory; ReRAM) 소자는 속도가 빠르고, 에너지 소모가 적으며, 고집적화를 이루기 용이하다는 강점을 보유하고 있다. 지금까지 저항변화 물질의 최적화를 위해 매우 다양한 물질들이 연구되고 있으며, 그 물질에 따라 스위칭 메커니즘 및 동작 방법이 다르게 보고되어 왔다. 하지만 저항변화 메모리의 스위칭 거동은 전형적인 전기적 제어 조건으로부터 구현되었기 때문에 한정된 소자 특성을 나타낼 수밖에 없었다. 본 연구에서는 새로운 메모리 제어 조건으로 빛을 이용함으로써 한정된 소자 특성으로부터 벗어나고자 하였다. 저항 변화 물질로 잘 알려진 ZnO를 표면적이 넓은 형태로 합성하기 위하여 hydrothermal 방법으로 FTO 기판 위에 수직하게 배열된 ZnO 나노와이어를 형성하고 그 위에 Au 상부 전극을 형성하여 금속-절연체-금속 소자 구조를 제작하였다. 본 연구에서는 전형적인 전기적 제어 조건에 더불어 빛의 입사 유무 조건을 바꿔가면서 Au/ZnO 나노와이어/FTO 소자의 저항 변화 특성을 평가 하였을 뿐만 아니라 전기적 인가 없이 오직 빛만으로 두 가지 안정한 저항 상태를 반복적으로 전환하는 특성을 유도하였다. 본 결과를 바탕으로 필라멘트 이론에 기초한 저항 변화 메커니즘을 설명하는 모델이 제시되었다.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.50-51
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• 2015

본 논문에서는 다수의 PV-부스트 컨버터를 입력으로 하는 계통연계형 풀브리지 인버터의 DC링크 커패시터간 전압 균등화 방법을 제안한다. 다수의 PV가 입력으로 연결된 인버터의 경우 각 PV의 부분 그늘짐 현상과 같은 조건에 따라서 최대 전력점이 달라질 수 있다. 각각의 PV와 연결된 부스트 컨버터의 출력 은 인버터의 DC링크 커패시터로서 각각이 직렬로 연결되는데 각 전압 분배는 PV의 입력에 따라 결정되게 된다. PV의 발전조건이 바뀌어 부스트 출력전압 편차가 극심해져서 더 이상 부스트 컨버터로서의 역할을 할 수 없는 조건이 갖춰진다면 PV에서의 안정적인 발전을 기대할 수 없을 것이다. 또한 DC링크 커패시터 간 전압의 불균형은 시스템을 설계함에 있어서 소자의 더 넓은 범위에서의 동작조건을 만족시켜야 하기 때문에 효율 면에서 나쁜 영향을 미치게 된다. 시뮬레이션을 통해서 DC링크 커패시터 간 전압 균등화 방법을 검증하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.35-42
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• 2010

In this study, crosstalk between dominant interconnect pairs in an A/D converter circuit is analyzed in frequency domain and effects of termination conditions on crosstalk are described, based on the practical circuit conditions. An A/D converter circuit is a mixed circuit where both clean and noisy signals coexist such that the circuit probably suffers from distortion by crosstalk. An analog input signal and the reference voltage signal, which dominate the overall conversion performance of the A/D converter circuit, are ready to be distorted by crosstalk and include specific termination conditions, such as non-matching and capacitive termination, respectively. Thus, this study presents the model of crosstalk considering impedance mismatch at both ends and analyzes effects of the practical termination conditions in the analog input and the reference voltage interconnects on crosstalk. A typical circuit configuration of the two interconnects is described and crosstalk including near-end and far-end termination impedances is modeled. Effects of the near-end impedance mismatch in the analog input interconnect and the far-end capacitive termination in the reference voltage interconnect are estimated in the frequency domain by using the model of crosstalk and experiments are performed to confirm the estimated results. Microstrip lines are used as interconnects, involving the increase of loss in high frequencies.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.207-212
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• 2015

Continuous, high-quality supply of electrical energy is the backbone of any modern economy. Any equipment operating at a power station must be reliable and safe. All major power supply components such as transformers, cables, generators, and switchgear need to be kept in perfect operating condition. The lifetime of power cables, used as the main means of transferring electric power, is understood to be about 30 years, from the time of manufacturing. The dielectrics between two conductors of a cable must be able to withstand electrical stresses from high-voltage input. This condition should be verified throughout the lifetime of the cable system. Several techniques, such as VLF-tan${\delta}$, partial discharge, and insulation resistance are used in order to determine the operating conditions of cables. In this paper, we present our work on insulation resistance to diagnose cables in operation at the Western Power station in Taean, Chungcheong Namdo Province, South Korea. As a result we have found cables the life time of which is 38 years.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.1
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• pp.46-56
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• 1991

In this paper, 16word X 8bit Content Addressable and Reentrant Memory(CARM) is described. This device has 4 operation modes(read, write, match, reentrant). The read and write operation of CARM is like that of static RAM, CARM has the reentrant mode operation where the on chip garbage collection is accomplished conditionally. Thus function can be used for high speed matching unit of dynamic data flow computer. And CARM also can encode matching address sequentially according to therir priority. CARM consists of 8 blocks(CAM cell, Sequential Address Encoder(S.A.E). Reentrant operation. Read/Write control circuit, Data/Mask Register, Sense Amplifier, Encoder. Decoder). Designed DARM can be used in data flow computer, pattern, inspection, table look-up, image processing. The simulation is performed using the QUICKSIM logic simulator and Pspice circuit simulator. Having hierarchical structure, the layout was done using the 3{\;}\mu\textrm{m} n well CMOS technology of the ETRI design rule.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.127-132
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• 2006

This paper presents a dual-mode amplifier which operates as amplifier or frequency multiplier according to the input frequency. It satisfies the 802.11a/b/g frequency band of wireless LAN standard. A conventional dual-band wireless LAN transmitter consists of the separating power amplifiers operating at each frequency band, but the proposed dual-mode amplifier operates as an amplifier for the 802.11b/g signal and as a frequency multiplier for the 802.11a signal according to each LAN bias condition. The amplifier mode shows the gain of 13dB, the PldB of 17dBm and second harmonic suppression of below -37dBc. And the frequency-doubler mode shows the gain of 3.3dB, the output power of 7.3dBm and third harmonic suppression of below -50dBr.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.12
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• pp.620-631
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• 2001

In interactive environments including computer games and virtual reality applications, we have increased need for interactive control of articulated body motions. Recently, physically based methods including constrained dynamics techniques are introduced to this area, in order to produce more realistic animation sequences. However, they are hard to achieve real-time control of articulated bodies, due to their heavy computations. In this paper, we present a procedural method for interactive animation of articulated bodies. In our method, each object of the constrained body is first moved according to their physical properties and external forces, without considering any constraints. Then, the locations of objects are adjusted to satisfy given constraints. Through adapting this two-stage approach, we have avoided the solving of large linear systems of equations, to finally achieve the interactive animation of articulated bodies. We also present a few example sequences of animations, which are interactively generated on PC platforms. This method can be easily applied to character animations in virtual environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.239-244
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• 2017

The demand for electric power is increasing every year. All facilities operating at power stations and all facilities used in transmitting high volumes of electric power are therefore expected to operate with a high degree of reliability. 6.6 kV XLPE 100 SQ 1C cables are used to deliver high levels of generated electric power. Depending on the method of manufacture, installation environment, and usage conditions, the deterioration processes of power cables start from the instant of operation. Cable junctions may break down in three years from the start of operation due to manufacturing or construction defects. We have invented the first device in Korea to monitor the status of live cables and installed these at Korea Western Power Co., Ltd.. We have set the criteria to determine deterioration status and specified the degree of deterioration at which one should replace the cables. In this paper, we present the effect of insulation layer and sheath on the insulation resistance status in cables.