• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.64-70
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• 2010

This paper presents how to decide on tuning factor(${\delta}$) and quality factor(Q) values in design of single-tuned passive harmonic filters. Tuning factor(${\delta}$) and quality factor(Q) values have to consider before decision on circuit parameters of passive filters. A Study on these two value has not been scarcely performed and only experienced values has been used in passive harmonic filter design by far. As a experienced value, in cases of 5th and 7th filter, tuning factor(${\delta}$) is about 0.94 and 0.96 respectively and quality factor(Q) is, in all cases of, 50. If Single-tuned passive harmonic filter will be off-tuned, performance of filter will be decreased steeply and occur to parallel resonance between system reactance and filter capacitance. Therefore During the operation, In order not to off-tuning, Filter must be tuned at former order than actual tuning order. This is the same that total impedance of filter must have a reactive impedance. In this paper, Tuning factor(${\delta}$) is decided via example of real system and using the bode-plot and then performance of filters confirmed by filter current absorbtion rate. And Quality factor(Q) decided using the bode plot in example system and then performance of filters confirmed by filter current absorbtion rate also, which makes a calculated filter parameters to satisfy IEEE-519 distortion limits. Finally, Performance of the designed passive harmonic filter using the tuning factor(${\delta}$) and quality factor(Q) values, decided in this paper is verified by experiment and shows that 5th, 7th, 9th, 11th and 13th current harmonic distortions are decreased within IEEE-519 distortion limits, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.2
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• pp.111-116
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• 2003

In this paper, a CMOS baseband analog receiver for wireless home network is discussed. It is composed of a Gilbert type mixer, an Elliptic 6th order 1ow pass filter, and a 6-bit A/D converter. The main role of the mixer is generating a mixed analog signal between the 200MHz output signal of CMOS RF stage and the 199MHz local oscillator. After the undesired high frequency component of the mixed signal comes out. Finally, the analog signal is converted into digital code at the 6-bit A/D converter, The proposed receiver is fabricated with 0.25${\mu}{\textrm}{m}$ 1-poly 5-metal CMOS technology, and the chip area is 200${\mu}{\textrm}{m}$ X1400${\mu}{\textrm}{m}$. the receiver consumes 130㎽ at 2.5V power supply.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.4
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• pp.20-30
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• 2001

A novel 200 MHz CMOS transconductor using translinear cells is proposed. The proposed transconductor consists of voltage followers and current followers based on translinear cells and a resistor. For wide applications, a single-input single-output, a single-Input differential-output, and a fully-differential transconductor are systematically designed, respectively. The theory of operation is described and computer simulation results are used to verify theoretical predictions. The results show that the fully-differential transconductor has a linear input voltage range of ${\pm}2.7$ V, a 3 dB frequency of 200 MHz, and a temperature coefficient of less than 41 $ppm/^{\circ}C$ at supply voltages of ${\pm}3$ V. In order to certify the applicability of the fully-differential transconductor, A ladder-type 3th-order cllitic low pass filter is also designed based on the inductance simulation method. The filter has a ripple bandwidth of 22 MHz, a pass-band ripple of 0.36 dB, and a cutoff frequency of 26 MHz.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.50-52
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• 2006

본 논문은 고성능 다결정 실리콘(Poly-Si) 박막 트랜지스터 (Thin Film Transistor)에서 단일 수직 그레인 경계(Single Perpendlcular Grain Boundary)가 고온 캐리어 스트레스(Hot Carrier Stress) 및 정전류 안정성 평가에서 어떠한 효과를 보이는가에 대해서 살펴보았다. 고온 캐리어 스트레스 하에서($V_G=V_{TH}+1V,\;V_D$ =12V),그레이 경계가 없는 다결정 실리콘 TFT와 비교했을 때 그레인 경계를 가지고 있는 다결정 실리를 TFT는 전기 전도(Electric Conduction)에 작용하는 자유 캐리어(Free Carrier)의 개수가 적기 때문에 상대적으로 더욱 우수한 전기적 특성을 나타낸다. 먼저 1000초 동안 고온 캐리어 스트레스를 가해준 결과 단일 그레인 경계를 가진 다결정 실리콘에서의 트랜스 컨덕턴스(Transconductance)의 이동 정도는 5% 미만으로 확인되었다. 반면에 같은 스트레스 조건 하에서 그레인 경계가 존재하지 않는 다결정 실리콘의 경우에는 그 이동 정도가 약 25%에 달하는 것으로 측정되었다. 다음으로 정전류 스트레스(Constant Current Stress) 인가시, 수직형 그레인 경계가 채널 영역 내에 존재하지 않는 다결정 실리콘 TFT는 드레인 접합 부분의 전계 세기를 비교했을 때, 그레인 경계를 가지고 있는 다결정 실리콘 TFT보다 상대적으로 낮은 원 인 때문에 적게 열화되는(Degraded) 특성을 확인할 수 있었다.

• Journal of the Korean association of regional geographers
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• v.13 no.2
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• pp.129-142
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• 2007

The Purpose of this study is to evaluate the value of abandoned paddy fields as wetland ecosystems and their suitability as habitats for various species. Physical and chemical characteristics of soils and the change of vegetation in paddy fields were analysed -with the passage of time after cease of cultivation. The results of analyses for soil characteristics, vegetation succession, and functional values of abandoned paddy fields as wetlands were as follows: First, top soils become coarser as years after abandonment increase. Second, as the years of abandonment passed. there were significant differences in organic matter, available phosphorate and calcium, while not in magnesium and cation exchange capacity(CEC). Third, species increased from early stage till middle stage, and decreased in late stage. In similarity analysis of species composition, sites were classified into three groups according to the stage of succession. Upper and lower terraces at Daetgol were classified as early stage of succession. The 1st, 2nd and 3rd terraces at Nonbanggol were in middle stage, while tile 4th and 5th were in late stage. Forth, according to evaluation sheets of MoE and RAM(Rapid Assessment Method) standards, me overall average of functional value of Nonbanggol site were 2.13, classified as "common".

• Journal of The Korean Association For Science Education
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• v.32 no.4
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• pp.686-702
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• 2012

This study investigated the impact of grouping methods on free inquiry implementation through the use of mixed research methods. Some 113 7th graders and 2 science teachers in two middle schools participated in this study. The 113 students who participated in this study were grouped by homogeneity and heterogeneity according to scientific inquiry skills and personality types respectively, and performed free inquiry activities on the same subject for three weeks. Data were collected by means of a test on science inquiry skills and from focus group interviews with 36 students and in-depth interviews with 2 teachers. The quantitative results of this study showed that homogeneous grouping was more effective than heterogeneous grouping in improvement of scientific inquiry skills. Meanwhile, the qualitative results revealed both the students and teachers perceived that it was effective to compose a small group according to their affective quality than their cognitive quality. Particularly, most of the students preferred the method of small group from the personality types. Some students and both teachers proposed that it is necessary to collect enough information on students and to use them in mixture with the method of small group according to the affective quality.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.2066-2067
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• 2009

1차년도에는 햅틱 시나리오의 비주얼 쓰레드로서의 환경을 구축하여 햅틱 렌더링과 그래픽 렌더링의 연동을 위한 연구를 수행하였고 햅틱 장비로부터 오는 다양한 데이터 처리를 위한 데이터 로딩 기법을 연구하고 이를 멀티 코어 CPU를 이용하여 단일 조명상에서 광선 추적하는 알고리즘을 개발하였다. 당해연도에는 1Khz 의 속도를 가진 햅틱 렌더링과의 불연속성을 해결하기 위하여 GPU를 이용한 보다 빠른 고품질의 광선 추적 알고리즘을 개발하고자 한다. 이를 위하여 NVIDIA의 범용 솔루션인 CUDA를 통해 병렬 처리를 통해 실시간으로 다중 광원을 가진 Dynamic한 장면을 갱신할 수 있도록 한다. 또한 심장, 폐, 간과 같은 반투명한 재질을 가진 신체 장기 표현을 위해 각 재질에 맞는 양방향의 표면 내부 산란 분포함수를 간략화하여 차후 년도의 연구에 반영한다.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.12
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• pp.577-582
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• 2002

The objective of this paper is to produce a weighted graph map for path-planning of an autonomous mobile robot(AMR) based on the measurements from a single ultrasonic sensor, which are acquired when the autonomous mobile robot explores unknown indoor circumstance. The AMR navigates in th unknown space by following the wall and gathers the range data using the ultrasonic sensor, from which the occupancy grid map is constructed by associating the range data with occupancy certainties. Then, the occupancy grid map is converted to a weighted graph map suing morphological image processing and thinning algorithms. the path- planning for autonomous navigation of a mobile robot can be carried out based on the occupancy grid map. These procedures are implemented and tested using an AMR, and primary results are presented in this paper.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.2
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• pp.63-68
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• 2000

A passively mode-locked ring type fiber laser had been installed in order to get the short pulses The single and the double mode-locking were appeared, and the shortest pulse length of 65 fs was obtained with a 110 m long dispersion shifted fiber(DSF) in a local cavity of 139.8 m. Also high order harmonic modelocking of 17th and Q-switched high order harmonic modelocking were obtained.

• Journal of Chest Surgery
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• v.27 no.6
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• pp.472-476
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• 1994

The incidence of single coronary artery is extremely rare in a review of congenital anomalies of the coronary arteries. This 27-year-old male patient was referred for the evaluation of cardiac condition showing exertional dyspnea[NYHA class II-III] and chest discomfort for about 1 year. A complete catheterization study including angiogram disclosed large single coronary artery arising from left aortic sinus [Ogden classification L-4] associated with bicuspid aortic valvular stenosis and low grade supravalvular aortic stenosis. Calcified stenotic aortic valve was fully removed with caution and the 19mm St. Jude Medical valve was then implanted in the small nortic annulus. The patient had an uneventful recovery and was discharged on 13th postoperative day.