• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권12호
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• pp.761-767
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• 1999

Poly-Si TFTs(polycrystalline silicon thin film transistors) fabricated on a low cost glass substrate have attracted a considerable amount of attention for pixel elements and peripheral driving circuits in AMLCS(active matrix liquid crystal display). In order to apply poly-Si TFTs for high resolution AMLCD, a high operating frequency and reliable circuit performances are desired. A new poly-Si TFT with CLBT(counter doped lateral body terminal) is proposed and fabricated to suppress kink effects and to improve the device stability. And this proposed device with BC(buried channel) is fabricated to increase ON-current and operating frequency. Although the troublesome LDD structure is not used in the proposed device, a low OFF-current is successfully obtained by removing the minority carrier through the CLBT. We have measured the dynamic properties of the poly-Si TFT device and its circuit. The reliability of the TFTs and their circuits after AC stress are also discussed in our paper. Our experimental results show that the BC enables the device to have high mobility and switching frequency (33MHz at $V_{DD}$ = 15 V). The minority carrier elimination of the CLBT suppresses kink effects and makes for superb dynamic reliability of the CMOS circuit. We have analyzed the mechanism in order to see why the ring oscillators do not operate by analyzing AC stressed device characteristics.

• 대한토목학회논문집
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• 제35권3호
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• pp.589-597
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• 2015

기존 케이슨방파제 외해 측에 수로를 설치하고 수로 내에 부유체를 설치한 파력발전시스템에 대해서 연구하였다. 이 시스템은 중복파를 기진력으로 활용하고, 수로 내 수주와 부유체의 공진현상을 이용하여 에너지 추출효율 극대화할 목적으로 제안되었다(Park et al., 2014). 선형파 이론에 기초한 Galerkin 유한요소 모델(Park, 1991)을 이용하여 제안된 발전시스템의 성능을 평가한 결과, 기존의 타 시스템에 비하여 우수한 발전효율을 보임과 수로 내 수주의 공진현상이 성능에 지배적인 영향을 미침을 확인하였다. 또한, 수로와 부이 주변에서 발생하는 유체 점성감쇠가 발전효율에 미치는 영향이 커 이를 최소화하는 노력이 필요한 것으로 평가되었다.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권11호
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• pp.502-510
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• 2006

In this paper, we describe implementation of a computer access device for the severly motor-disability. Many people with severe motor disabilities need an augmentative communication technology. Those who are totally paralyzed, or 'locked-in' cannot use conventional augmentative technologies, all of which require some measure of muscle control. The forehead is often the last site to suffer degradation in cases of severe disability and degenerative disease. For example, In ALS(Amyotrophic Lateral Sclerosis) and MD(Muscular dystrophy) the ocular motorneurons and ocular muscles are usually spared permitting at least gross eye movements, but not precise eye pointing. We use brain and body forehead bio-potentials in a novel way to generate multiple signals for computer control inputs. A bio-amplifier within this device separates the forehead signal into three frequency channels. The lowest channel is responsive to bio-potentials resulting from an eye motion, and second channel is the band pass derived between 0.5 and 45Hz, falling within the accepted Electroencephalographic(EEG) range. A digital processing station subdivides this region into eleven components frequency bands using FFT algorithm. The third channel is defined as an Electromyographic(EMG) signal. It responds to contractions of facial muscles and is well suited to discrete on/off switch closures, keyboard commands. These signals are transmitted to a PC that analyzes in a time series and a frequency region and discriminates user's intentions. That software graphically displays user's bio-potential signals in the real time, therefore user can see their own bio-potentials and control their physiological signals little by little after some training sessions. As a result, we confirmed the performance and availability of the developed system with experimental user's bio-potentials.

• ALGAE
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• 제35권4호
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• pp.389-404
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• 2020

Red algal fertilization is unusual and offers a different model to the mechanism of intracellular transport of nuclei and polyspermy blocking. A female carpogonium (egg) undergoes plasmogamy with many spermatia (sperm) simultaneously at the receptive structure, trichogyne, which often contains numerous male nuclei. The pattern of selective transport of a male nucleus to the female nucleus, located in the cell body of the carpogonium, remain largely unknown. We tracked the movement of spermatial nuclei and cell organelles in the trichogyne after plasmogamy using time-lapse videography and fluorescent probes. The fertilization process of Bostrychia moritziana is composed of five distinctive stages: 1) gamete-gamete binding; 2) mitosis in the attached spermatia; 3) formation of a fertilization channel; 4) migration of spermatial nuclei into the trichogyne; and 5) cutting off of the trichogyne cytoplasm from the rest of the cell after karyogamy. Our results showed that actin microfilaments were involved in the above steps of fertilization, microtubules are involved only in spermatial mitosis. Time-lapse videography showed that the first ("primary") nucleus which entered to trichogyne moved quickly to the base of carpogonium and fused with the female nucleus. The transport of the primary male nucleus to the egg nucleus was complete before its second nucleus migrated into the trichogyne. Male nuclei from other spermatia stopped directional movement soon after the first one entered the carpogonial base and oscillated near where they entered trichogyne. The cytoplasm of the trichogyne was cut off at a narrow neck connecting the trichogyne and carpogonial base after gamete nuclear fusion but gamete binding and plasmogamy continued on the trichogyne. Spermatial organelles, including mitochondria, entered the trichogyne together with the nuclei but did not show any directional movement and remained close to where they entered. These results suggest that polyspermy blocking in B. moritziana is achieved by the selective and rapid transport of the first nucleus entered trichogyne and the rupture of the trichogyne after gamete karyogamy.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.494-496
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• 2002

A bi-directional and multi-channel wireless telemetry capsule, 11mm in diameter, is presented that can transmit video images from inside the human body and receive a control signal from an external control unit. The proposed telemetry capsule includes transmitting and receiving antennas, a demodulator, decoder, four LEDs, and CMOS image sensor, along with their driving circuits. The receiver demodulates the received signal radiated from the external control unit. Next, the decoder receives the stream of control signals and interprets five of the binary digits as an address code. Thereafter, the remaining signal is interpreted as four bits of binary data. Consequently, the proposed telemetry module can demodulate external signals so as to control the behavior of the camera and four LEDs during the transmission of video images. The proposed telemetry capsule can simultaneously transmit a video signal and receive a control signal determining the behavior of the capsule itself. As a result, the total power consumption of the telemetry capsule can be reduced by turning off the camera power during dead time and separately controlling the LEDs for proper illumination of the intestine.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.30.4-31
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• 2011

The Korea Astronomy and Space Science Institute (KASI) and the Department of Astronomy at the University of Texas at Austin (UT) are developing a near infrared wide-band high resolution spectrograph, IGRINS (Immersion Grating Infrared Spectrograph). The white-pupil design of the instrument optics uses 7 cryogenic mirrors including 3 aspherical off-axis collimators and 4 flat fold mirrors. Two of the 3 collimators are H- and K-band pupil transfer mirrors and they are designed as compensators for the system alignment in each channel. Therefore, their mount design will be one of the most sensitive parts in the IGRINS optomechanical system. The design work will include the computer-aided 3D modeling and finite element analysis (FEA) to optimize the structural stability of the mount models. The mount body will also include a tip-tilt and translation adjustment mechanism to be used as the alignment compensators.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권1호
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• pp.32-38
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• 2002

This paper describes a development of a portable physical activity monitoring system using two accelerometers to quantify physical activity. The system hardware consists of two piezoresistive accelerometers, amplifiers with gain of 30, lowpass filters with cut-off frequency of 15Hz, offset control circuits, one-chip microcontroller and flash memory card. In order to evaluate the performance of the system we acquired 3 channel data at 32 sample/sec from body-fixed accelerometers in chest and right upper leg. And then the acquired data were processed by MatLab on personal computer. We tried to distinguish not only fundamental actions which are steady-state activities such as standing, sitting, and lying but also dynamic activities with walking, up a stairway, down a stairway, and running. Five subjects participated the evaluation process which compare the video data with the measured data. As a result, the activity classification rate of 90.6% on average was obtained. Overall results showed that the steady-state activities could be classified from the low component of 3-axis acceleration signal and dynamic activities could be distinguished from frequency analysis using wavelet transform and FFT. Finally, we could find that this system can be applied to acquire and analyze the static and dynamic physical activity data.

• 한국전기전자재료학회논문지
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• 제20권6호
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• pp.491-495
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• 2007

This paper has demonstrated the electrical properties of SiGe pMOSFETs fabricated on both bulk-Si and PD SOI substrates. Two principal merits, the mobility increase in strained-SiGe channel and the parasitic capacitance reduction of SOI isolation, resulted in improvements in device performance. It was observed that the SiGe PD SOI could alleviate the floating body effect, and consequently DIBL was as low as 10 mV/V. The cut-off frequency of device fabricated on PD SOI substrate was roughly doubled in comparison with SiGe bulk: from 6.7 GHz to 11.3 GHz. These experimental result suggests that the SiGe PD SOI pMOSFET is a promising option to drive CMOS to enhance performance with its increased operation frequency for high speed and low noise applications.

• 한국수자원학회논문집
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• 제41권4호
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• pp.423-432
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• 2008

어류는 생존과 번식을 위해 회유 또는 이동을 하며, 이러한 회유나 이동은 어종에 따라 넓은 범위에서 이루어 질수도 있고 국지적으로 이루어 질 수도 있다. 피라미는 한국의 강과 하천에 우점종으로 서식하는 어종이다. 그러나 하천에 설치된 댐, 보, 암거 등은 어류가 이동하거나 번식하는데 많은 장애가 되고 있다. 실제로 어류 서식처간의 연결부가 배수암거(culvert)로 설치되어 있는 경우에는 평상시 피라미와 같이 몸집이 작은 어류가 이동하는데 장애를 줄 정도의 빠른 유속과 낮은 수심이 발생되고 있다. 그러나 국내에서는 국내 하천에 서식하고 있는 민물고기의 유영특성에 관한 연구가 충분치 않아 현실적으로 어도기능을 위한 합리적인 배수암거 설계기준을 마련하기가 어려운 실정이다. 본 연구의 목적은 배수암거의 평상시 어도기능을 위한 설계유속을 제시하기 위해 국내 하천의 우점종이자 국지회유성 어종인 피라미의 유영특성을 분석하고자 함이다. 피라미의 유영특성을 파악하기 위한 실험은 증진유속방법(incremental velocity test)과 고정유속방법(fixed velocity test)을 병행하여 수행하였다. 실험 결과 피라미(체장 8.9cm)의 유영특성 중 한계유영속도는 0.7 m/s 정도로 나타났다. 따라서 홍수기를 제외한 평상시 유량조건에서 배수암거 설계유속은 피라미(체장 8.9cm)를 대상어종으로 할 경우 0.7 m/s 를 초과하지 않아야 할 것으로 판단된다. 최소수심은 등지느러미까지 충분히 물속에 잠길 수 있는 수심이 필요한 것으로 파악되었다.

• 한국환경과학회지
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• 제23권5호
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• pp.943-962
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• 2014

Industrial gas drying, dilute gas mixtures purification, air fractionation, hydrogen production from steam reformers and petroleum refinery off-gases, etc are conducted by using adsorptive separation technology. The pressure swing adsorption (PSA) has certain advantages over the other methods, such as absorption and membrane, that are a low energy requirement and cost-effectiveness. A key component of PSA systems is adsorbents that should be highly selective to a gas being separated from its mixture streams and have isotherms suitable for the operation principle. The six standard types of isotherms have been examined in this review, and among them the best behavior in the adsorption of $CO_2$ as a function of pressure was proposed in aspects of maximizing a working capacity upon excursion between adsorption and desorption cycles. Zeolites and molecular sieves are historically typical adsorbents for such PSA applications in gas and related industries, and their physicochemical features, e.g., framework, channel structure, pore size, Si-to-Al ratio (SAR), and specific surface area, are strongly associated with the extent of $CO_2$ adsorption at given conditions and those points have been extensively described with literature data. A great body of data of $CO_2$ adsorption on the nanoporous zeolitic materials have been collected according to pressure ranges adsorbed, and these isotherms have been discussed to get an insight into a better $CO_2$ adsorbent for PSA processes.