• 대한전자공학회논문지
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• 제27권12호
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• pp.1859-1864
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• 1990

The effect of H+ and OH- ion concentrations at doped Si semiconductor/pH buffer solution interfaces were investigated in terms of cyclic current-voltage characteristics. The effects of space charge on oppositely doped Si semiconductors, i.e., p-and n-Si semiconductors, can be effectively applied to study the pH effects and the slow surface states at the interfaces. The adsorptions of H+ and OH- inons on the doped Si semiconductor surfaces are physical adsorption rather than chemical adsorption. Adsorptive processes and charging effects of the slow surface states can be explained as the potential barrier variations and the related current-voltage characteristics at the interfaces. Under forward bias, the charged slow surface states on the p-and n-si semiconductor surface are donor and acceptor slow surface states, respectively. The effects of minority carriers on the slow surface states can be neglected at the doped Si semiconductor interfaces.

• 음성과학
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• 제11권3호
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• pp.23-36
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• 2004

Many languages show reverse durational variation between preceding vowel and following voiced/voiceless (lax/tense) consonants. This study investigated the likely effects of phoneme type (tense vs. lax) on the timing structure (duration of syllable, word, phrase and sentence) of Korean. Three rates of speech (fast, normal, slow) applied to stimuli with the target word /a-Ca/ where /C/ is one of /p, p', $p^h$/. The type (tense/lax) of /C/ caused marked inverse durational variations in the two syllables /a/ and /Ca/ and highly different durational ratios between them. Words with /p', $p^h$/ were significantly longer than that with /p/, which contrasts with many other languages where such pairs of words have a similar duration. The differentials between words remained up to the phrase and sentence level, but in general the higher linguistic units did not statistically differ within each level. Thus, the phrase is suggested as a compensatory unit of phoneme type effects in Korean. Different rates did not affect the general tendency. Distribution of time variations (from normal to fast and slow) to each syllable (/a/ and /Ca/) was also observed.

• 전기의세계
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• 제26권3호
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• pp.73-75
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• 1977

A coupled-mode approach is used to analyze the interaction of the carrier wave in solid-state materials with the external slow electromagnetic wave. A general condition for an active coupling is derived. Gain characteristics is also examined as a function of operating frequency and thermal-to-drift veocity variations.

• 한국전자파학회논문지
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• 제27권12호
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• pp.1059-1068
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• 2016

본 논문에서는 프린트 다이폴의 지향성 증가와 동시에 부엽 레벨을 억제하는 기능을 가진 저속파 구조를 제안하고 구성 설계변수의 변화에 따른 전기적 특성의 변화를 알아보고자 한다. 유전체 기판과 도체 막대의 배열로 구성된 프린트 형태의 저속파 구조는 프린트 다이폴 안테나의 여기 방향에 위치하며 안테나의 방사 패턴 및 세기에 영향을 미친다. 이 도체 막대로 된 기생소자는 좁은 간격을 가지고 일정하게 배열되며 소자의 길이는 점차 줄어드는 형상을 가진다. 따라서 본 연구에서는 저속파 구조에서 방사 성능에 영향을 줄 수 있는 변수로 기생소자 배열 간격, 소자 길이, 소자 길이의 테이퍼 각도가 고려되며, 변수들의 변화에 따른 전기장 세기 및 위상 분포가 관찰 및 분석된다. 이를 기반으로 방사패턴이 분석이 되며, 고지향성 특성을 위한 저속파 구조의 기생소자 배열 방안이 제공된다. 제안된 안테나는 Wifi 대역(5.15~5.85 GHz)에서 동작하도록 설계되며, 안테나의 이득을 극대화하고 부엽을 억제하도록 저속파 기생소자의 설계변수가 최적화된다. 제작된 안테나의 시뮬레이션 및 측정 결과 넓은 대역폭 특성을 나타내며, 높은 효율과 이득, 낮은 부엽 레벨을 갖는 것을 확인할 수 있다.

• 아동학회지
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• 제8권2호
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• pp.1-15
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• 1987

Prior studies on child development have focused mainly on environmental variables including mother variations. However, several studies proved that child variables, especially inherited temperament, influence or change the environment. The current study investigates the temperament of 5 - to 8 - month - old infants. One hundred and forty-three mothers of the infants responded to the RITQ that was devised by Carey and McDevitt (1978). The RITQ examined 9 temperamental categories. Based on the score, the subjects were divided into five subgroups-Difficult, Slow-to-Warm-Up, Intermediate High, Intermediate-Low, and Easy. The important findings are as following : (1) There were significant sex differences. Females appeared to have significantly more representation in the slow-to-warm-up, intermediate-high, and intermediate-low groups. There were more males in the easy group. In the comparison of the two sexes as to the mean score in the nine categories males were found to be more approaching, less intensive, positive mood, and highly distractible. (2) Infants' temperament was not related to the mothers' education level and their work status. (3) The mothers' global ratings were consistent with subgroup temperament characteristics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.420-425
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• 1996

In this paper a robust speed controller for an induction motor is proposed. The speed controller consists or a fuzzy sliding adaptive controller(FSAC) and a sliding mode torque observer(SMTO). FSAC removes the problem or oscillations caused by discontinuous inputs of the sliding mode controller. The controller also provides robust characteristics against parameter and sampling time variations. Although, however, the performance of FSAC is better than PI controller and fuzzy controller in robustness, it generates the problem of slow response time. To alleviate this problem, a compensator, which performs feedforward control using torque signals produced by SMTO, is added. The simulation and hardware implementation results show that the proposed system is robust to the load disturbance, parameter variations, and measurement noises.

• 대한산업공학회지
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• 제21권1호
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• pp.33-49
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• 1995

Simulated annealing(SA) has been admitted as a general purpose optimization technique which can be utilized for almost all kinds of combinatorial optimization problems without much difficulty. But there are still some weak points to be resolved, one of which is the slow speed of convergence. In this study, we carefully review various previous efforts to improve SA and propose some variations of SA which can enhance the speed of convergence to the optimum solution. Then, we apply the revised SA algorithms to the scheduling and hardware allocation problems occurring in high-level synthesis(HLS) of VLSI design. We confirm the efficiency of the proposed methods through several HLS examples.

• 대한전기학회논문지:전력기술부문A
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• 제48권6호
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• pp.719-727
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• 1999

A robust position control method of the BLDC motor using a new sliding mode control strategy is presented. The main property of variable structure system(VSS) is that the system response is robust and insensitive to parameter variations and external disturbances in the sliding mode. When using the conventional VSS, generally the reaching phase problem occurs, which cause the system response to be sensitive to parameter variations and external disturbances. Furthermore, the speed of response is relatively slow because the swithching surface is a linear function. In order to overcome these problems, VSS with nonlinear sliding surface eliminating reaching phase is proposed. The validity of the proposed scheme is shown by results of simulations of simulations and experiments for the BLDC motor with variable load.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.315-319
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• 2001

It is shown, that both cosmic radiation (external source) and natural radioactive gases (inner source) are sources of neutrons near the Earth crust. Correlation between the Earth crust dynamics and variations of thermal and slow neutron flux near the Earth surface is studied. It is shown, that variations of neutron flux near the Earth crust can be used for short-term predicting of natural hazards.

• The Journal of the Acoustical Society of Korea
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• 제25권4E호
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• pp.159-165
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• 2006

Human, horse and rat bloods in a cylindrical chamber where flow was controlled by a stirring magnet were used for studying red blood cell aggregation. Ultrasound backscattered powers from blood were obtained from the backscattered signals measured by a 5 MHz focused transducer in a pulse-echo setup. The experimental results showed the differences in red blood cell (RBC) aggregation tendency among the three mammalian species with an order of horse > human > rat. The ultrasound backscattered power decreased with stirring speed in human and horse blood, but no variations were observed in rat blood. Sudden flow stoppage led to the slow increase of the backscattered power for human and horse blood. There was no self-aggregation tendency in rat blood. The enveloped echo images showed the spatial and temporal variations of RBC aggregations in the cylindrical chamber. These observations from the different mammalian species may give a better understanding of the mechanism of RBC aggregation.