• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.401-404
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• 1996

A new method for the electrostatic suspension of disk-shaped objects is proposed which is based on a switched-voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply capable of delivering a dc voltage of positive and/or negative polarity. In addition to the unique feature that no high-voltage amplifiers are needed, this method provides a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping. In this paper, the functional principle of the switched voltage control scheme, numerical analysis, stator electrode design, and a nonlinear dynamic model of the suspension system are described. Experimental results will be presented for a 4-inch silicon wafer that clearly reveal the capability of the proposed control structure to suspend the wafer stably at an airgap length of 50 .mu.m.

• 전자공학회논문지SC
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• 제37권3호
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• pp.84-93
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• 2000

PWM 전압원 인버터를 통상적인 스위칭 방법으로 동작시킬 때, 직류 전압원의 단락을 방지하기 위하여 스위칭 신호에 데드타임을 삽입한다. 이러한 데드타임은 인버터 시스템의 제어 성능에 좋지 않은 영향을 발생시킨다. 따라서 이 데드타임의 영향을 보상하는 것이 필요하다. 또한 이 데드타임의 영향을 근본적으로 방지할 수 있는 최선의 방법으로써 데드타임 최소화 스위칭 방법을 고려할 수도 있다. 본 논문에서는 데드타임 최소화 스위칭 방법의 하나인 새로운 스위칭 방법을 제안하였다. 제안한 스위칭방법에 의하면 전류 극성이 절환되는 경우에 있어서, 단 한 번의 매우 짧은 데드타임만이 적용된다. 적용되는 데드타임은 스위칭 소자의 턴오프 시간보다 짧거나 같다. 그리고 제안하는 방법은 인버터의 출력 전류를 제어하는 경우에 있어서는, 지령전류의 극성 정보에 의하여 구현될 수 있기 때문에 극성 절환 시점을 판단하기 위하여 실제 전류를 이용하는 경우에 비하여 레벨 검출의 난점, 노이즈 등등의 문제점을 해결하기 쉽다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.969-974
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• 2003

A simple and cost-effective method for the electrostatic suspension of thin plates like silicon wafers is proposed which is based on a switched voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply that can deliver a dc voltage of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping origination from the air between the electrodes and levitated object. Using this scheme, a 4-inch silicon wafer was levitated stably with airgap variation decreasing down to 1 $\mu\textrm{m}$ at an airgap of 100 $\mu\textrm{m}$

• 한국정밀공학회지
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• 제22권10호
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• pp.56-64
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• 2005

A simple and cost-effective method for the electrostatic suspension of thin plates like silicon wafers is proposed which is based on a switched voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply that can deliver a DC voltage of positive and/or negative polarity. This method possesses the unique feature that no high-voltage amplifiers are needed which leads to a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping origination from the air between the electrodes and levitated object. Using this scheme, a 4-inch silicon wafer was levitated stably with airgap variation decreasing down to $1 {\mu}m$ at an airgap of $100{\mu}m$.

• 한국전문물리치료학회지
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• 제3권3호
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• pp.67-81
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• 1996

This study was performed to assess the efficacy of high voltage pulsed galvanic current for the healing of wounds in rabbits. Skin wounds were created laterally on the flank of 12 domestic rabbits($3{\times}3cm$). The wounds of each group were treated with an intensity of 170 V at a frequency of 70 pulses per second, which was applied for 30 minutes a day for 10 days. The experimental groups were randomly assigned to either EXP I (n=3), EXP II(n=3), EXP III(n=3) or control(n=3). Each group was stimulated under the following conditions : 1) EXP I (Negative polarity), 2) EXP II (Change in polarity, negative electrode stimulation during the first 3 days and then positive electrode stimulation from 4 to 10 days), 3) EXP III(Positive polarity), 4) control(No stimulation). An active electrode was placed over the wound and a dispersive electrode on the buttock. The rate of wound closure was compared with the original wound size, evaluated by a tracing film in each measurement period. Finally, on the wound in each group, skin tissue was excised for histological evaluation after treatment for 10 days. The results obtained are as follows : 1) It was found that the control group did not show a complete remodeling of epitherial layer and had a chronic inflammatory response. Judging from the irregularity of intercellular space and the loose alignment of connective tissue, these findings show that wound healing was delayed. 2) EXP I showed a significant bactericidal effect, but a moderate response of vasodilation. The rate of wound closure was slower when compared with EXP II, III. 3) EXP II showed a complete remodeling of epitherial layer and a positive repair of connective tissue. Its rate of wound closure was best when compared with the others. 4) EXP III had a slower rate of wound closure than EXP II, but judging from the greater proliferation of collagen fibers and the dense alignment of connective tissue, this positive electrode was very effective in the formation of neo - connective tissue.

• 한국멀티미디어학회논문지
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• 제18권11호
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• pp.1391-1399
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• 2015

In recent times, studies sentiment analysis are being actively conducted by implementing natural language processing technologies for analyzing subjective data such as opinions and attitudes of users expressed on the Web, blogs, and social networking services (SNSs). Conventionally, to classify the sentiments in texts, most studies determine positive/negative/neutral sentiments by assigning polarity values for sentiment vocabulary using sentiment lexicons. However, in this study, sentiments are classified based on Thayer's model, which is psychologically defined, unlike the polarity classification used in opinion mining. In this paper, as a method for classifying the sentiments, sentiment categories are proposed by extracting sentiment keywords for major sentiments by using hashtags, which are essential elements of Instagram. By applying sentiment categories to user posts, sentiments can be determined through the similarity measurement between the sentiment adjective candidates and the sentiment keywords. The test results of the proposed method show that the average accuracy rate for all the sentiment categories was 90.7%, which indicates good performance. If a sentiment classification system with a large capacity is prepared using the proposed method, then it is expected that sentiment analysis in various fields will be possible, such as for determining social phenomena through SNS.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book I
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• pp.457-468
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• 2003

Active ingredients have been around in cosmetics for a long time but have they really resulted in active cosmetic products\ulcorner In order to achieve this, the right active needs to be delivered to the right location at the right concentration for the correct period of time. And the extent (and therefore the concentration) of this delivery depends on the formulation. From a rather theoretical approach based on the polarity of the active ingredient, the stratum corneum and the oil phase, the Relative Polarity Index was established that enables the selection of a suitable emollient for ensuring skin penetration of the active ingredient. Practical examples subsequently show the validity of this approach that demonstrates that one can regulate the delivery of an active molecule (and therefore the efficacy of a cosmetic formulation) by selection and control of the emollient system. Cosmetic formulations are generally quite complex mixtures and subsequent experiments using different emulsifier systems indicated that this component of a cosmetic formulation could also have an impact on steering the active ingredient to the right layer of the skin, although it is too early to be able to derive general rules from this.

• 센서학회지
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• 제14권6호
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• pp.409-414
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• 2005

For an intelligent vehicle driving which uses magnetic markers and magnetic sensors, we can get every kind of road information while moving the vehicle if we use the code that is encoded with N, S pole direction of markers. If we make it an only aim to move the vehicle, it becomes easy to control the vehicle the more we put markers close. By the way, to recognize the direction of a marker pole it is much better that the markers have no effect each other. To get road informations and move the vehicle autonomously we propose the methods of arranging magnetic sensors and algorithm of recognizing the position of the vehicle with those sensors. We verified the effectiveness of the methods with computer simulation.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.78-89
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• 2000

Protein secretion in filamentous fungi has been shown to be restricted to actively growing hyphal tips. To determine whether an increase in the amount of growing surface area of a fungus can lead to an increase in the amount of protein secretion, we examined secretion in a temperature-sensitive Neurospora crassa mcb mutant that shows a loss of growth polarity when incubated at restrictive-temperature. Incubation of the mcb mutant at restrictive-temperature results in a three- to five-fold increase in the level of extracellular protein and a 20- fold increase in carboxymethyl cellulase activity relative to a wild-type strain. A mutation in the cr-l gene has been shown previously to suppress the apolar growth phenotype of the mcb mutant, and we find that the level of extracellular protein produced by a mcb; cr-l double mutant was reduced to that of the wild-type control. Immunolocalization of a secreted endoglucanase revealed that proteins are secreted mainly at hyphal tips in hyphae exhibiting polar growth and over the entire surface area of bulbous regions of hyphae that are produced following a shift of the mcb mutant to restrictive-temperature. These results support the hypothesis that secretion of extracellular protein by a filamentous fungus can be significantly increased by mutations that alter growth polarity.

• 한국발생생물학회지:발생과생식
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• 제27권3호
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• pp.159-165
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• 2023

The Ruvb-like AAA ATPase1 (Ruvbl1; also known as Pontin) is an evolutionary conserved protein belonging to the adenosine triphosphates associated with diverse cellular activities (AAA+) superfamily of ATPases. Ruvbl1 is a component of various protein supercomplexes and is involved in a variety of cellular activities, including chromatin remodeling, DNA damage repair, and mitotic spindle assembly however, the developmental significance of this protein is unknown and needs detailed investigation. We investigated the developmental significance of Ruvbl1 in multiciliated cells of the Xenopus laevis epidermis since ruvbl1 is expressed in the multiciliated cells and pronephros during X. laevis embryogenesis. The knockdown of ruvbl1 significantly impaired cilia-driven fluid flow and basal body polarity in the X. laevis epidermis compared to control embryos, but did not affect cilia morphology. Our results suggest that Ruvbl1 plays a significant role in embryonic development by regulating ciliary beating; however, further investigation is needed to determine the mechanisms involved.