• 조명전기설비학회논문지
• /
• 제19권3호
• /
• pp.66-74
• /
• 2005

최근 급속도로 발전되고 있는 산업분야에서 서보시스템은 빠른 응답특성과 고도의 정밀성이 요구되고 있다. 이러한 특성의 요구로 인하여 산업용 서보전동기 구동시스템에 고정자 혹은 회전자 자속벡터의 순시위치와 고정자 전류를 검출하여 좌표변환에 의해 고정자 전류를 여자성분과 토크성분으로 분리 제어하는 벡터제어 이론이 많이 적용되고 있다. 벡터제어에서는 좌표변환과 SVPWM 발생을 위해 많은 연산을 요구하므로 디지털 제어시스템에서 DSP에 많은 부담을 주고 있다. 그러나 직접토크제어(DTC) 알고리즘은 디지털 제어 구조로 토크와 고정자 자속 성분의 전류제어에 룩업 테이블을 사용하므로 벡터제어처럼 많은 제어기와 복잡한 연산을 필요로 하지 않고, 동적 응답특성이 전동기의 정수변화에 영향이 적으면서 직접 전동기의 토크와 고정자 자속을 독립적으로 제어할 수 있는 장점을 가진다. 따라서 본 논문에서는 표면 부착형 영구자석 동기전동기(SPMSM)를 사용하여 DTC에 의한 서보 전동기 제어와 벡터제어에 의한 서보 제어시스템 결과를 비교하여 직접토크제어 알고리즘의 산업용 서보 시스템으로의 적용 가능성을 확인하였다.

• 전력전자학회논문지
• /
• 제6권2호
• /
• pp.115-124
• /
• 2001

본 논문에서는 유도전동기 회전자 자속 기준제어를 위하여 비선형 관측기인 확장된 루엔버거 관측기 원리를 적용한 새로운 회전자 자속관측기를 제안하였다. 확장된 루엔버거 관측기는 확장된 칼만 필터와 유사하게 동특성 오차의 선형화 기법을 따트고 있으나 통계학적 속성의 노이즈 공분산을 고려하지 않는 결정론적 관측기로서 비선형 상태관측기 설계시 요구되는 좌표변환 및 선형화 파정에서 비선형 편미분 방정식의 직접적인 해를 펼요로 하지 않아 구현이 비교적 용이하다. 제안된 회전자 자속관측기는 직교좌표의 고정자 전류, 회전자 자속, 속도 및 부하 토크로 구성된 6차 미분방정식으로부터 유도되었으며 축약된 형태의 이득행렬을 갖는다. 시뮬레이션 및 실험은 파라 미터중 회전자 저항 값이 변동된 상황을 가정하여 수행하였으며, 시뮬레이션 결과 제안된 관측기를 이용한 자속 추정시 극점 재배치를 통하여 동특성 오차의 수렴성을 제어할 수 있으며, 부하 설험결과 제안된 관측기를 적용하는 경우에는 슬립적분형 간접벡터제어에 비해 보다 정확한 벡터제어가 가능함이 확인되었다.

• Journal of Plant Biotechnology
• /
• 제7권3호
• /
• pp.161-167
• /
• 2005

Brassinosteroids are steroidal plant hormones and are known to modulate physiological and cellular response in a wide range of plant species. Considerable insights has been achieved of the physiological role of brassinosteroid in Brassica species in the past few years, but their effect on direct organogenesis has not been extensively studied. In this sense, under optimal basal media and growth conditions we tested the cellular and organogenic response of 24-epibrassinolide (EBL) in a variable concentration (0.1 to $5.0\;{\mu}M$) and Zeatin (Z) (1.0 to $100\;{\mu}M$) and their synergic effect on hypocotyl explants of cauliflower and broccoli. The isolated EBL accelerated cell elongation and promotes direct organogenesis. One micromolar EBL + $10\;{\mu}M$ of Z was the most efficient combination for cell elongation, cell differentiation as well as for organogenesis. A suppressing effect on root induction was confirmed for all the tested hormone levels. The general results indicate a synergic effect of EBL-Z and EBL potentates Zeatin activity, at least in certain tissues. Besides de genetic factors, we can speculate that the natural hormone concentration in the explants might affect the responses by application of exogenous growth regulators. Experiments with new plant growth regulators, like brassinolide, are important aiming to maximize or accelerate plant regeneration for in vitro multiplication or for genetic transformation.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
• /
• pp.199-199
• /
• 2011

The addition of a carbanion to ${\yen}{\acute{a}}{\yen}{\hat{a}}$-unsaturated carbonyl compounds is of importance in the C-C bond formation reactions for modern pharmaceuticals and organic synthesis. Recently, heterogeneous asymmetric catalysis became more attractive area of research because of the easy recovery and separation of the catalyst from the reaction system. Most of synthetic methods for heterogeneous catalysts were grafting or immobilization of homogeneous catalyst onto the solid supports. Trans-1,2-Diaminocyclohexane(DACH) and L-proline ligands have been enormously used as chiral ligands in several catalytic transformation under homogenous conditions. Our group prepared l-proline functionalized mesoporous silica was synthesized under acidic condition using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer template (EO20PO70EO20, Pluronic P-123, BASF). Furthermore, we successfully directly synthesized trans-1,2 diaminocyclohexane functionalized mesoporous silica by using microwave method. The direct functionalization of chiral ligand into the framework of mesoporous materials is expected to be useful for the heterogeneous asymmetric catalysis. So, we adopt the direct synthesis of chiral ligand functionalized mesoporous silica by using thermal and microwave irradiation. Then, chiral ligand functionalized mesoporous silicas were applied to enantioselective asymmetric catalytic reactions.

• 한국주조공학회지
• /
• 제33권4호
• /
• pp.157-161
• /
• 2013

A ribbon-type polycrystalline silicon wafer was directly fabricated from liquid silicon via a novel technique for both a fast growth rate and large grain size by exploiting gas pressure. Effects of processing parameters such as moving speed of a dummy bar and the length of the solidification zone on continuous casting of the silicon wafer were investigated. Silicon melt extruded from the growth region in the case of a solidification zone with a length of 1cm due to incomplete solidification. In case of a solidification zone wieh a length of 2 cm, on the other hand, continuous casting of the wafer was impossible due to the volume expansion of silicon derived from the liquid-solid transformation in solidification zone. Consequently, the optimal length of the solidification zone was 1.5 cm for maintaining the position of the solid-liquid interface in the solidification zone. The silicon wafer could be continuously casted when the moving speed of the dummy bar was 6 cm/min, but liquid silicon extruded from the growth region without solidification when the moving speed of the dummy bar was ${\geq}$ 9 cm/min. This was due to a shift of the position of the solid-liquid interface from the solidification zone to the moving area. The present study reports experimental findings on a new direct growth system for obtaining silicon wafers with both high quality and productivity, as a candidate for an alternate route for the fabrication of ribbon-type silicon wafers.

• 수산해양기술연구
• /
• 제60권1호
• /
• pp.71-79
• /
• 2024

In compliance with environmental regulations at sea and the introduction of unmanned autonomous ships, electric propulsion ships are garnering significant attention. Induction machines used as propulsion electric motor (PEM) have maintenance advantages, but speed control is very complicated and difficult. One of the most commonly used techniques for speed control is DTC (direct torque control). DTC is simple in the reference frame transformation and the stator flux calculation. Meanwhile, two-level and three-level voltage source inverters (VSI) are predominantly used. The three-level VSI has more flexibility in voltage space vector selection compared to the two-level VSI. In this paper, speed is controlled using the DTC method based on the specifications of the PEM. The speed controller employs a PI controller with anti-windup functionality. In addition, the characteristics of the two-level VSI and three-level VSI are compared under identical conditions. It was confirmed through simulation that proper control of speed and torque has been achieved. In particular, the torque ripple was small and control was possible with a low DC voltage at low speed in the three-level VSI. The study confirmed that the application of DTC, using a three-level VSI, contributes to enhancing the system's response performance.

• 한국초지조사료학회지
• /
• 제33권2호
• /
• pp.100-104
• /
• 2013

포장에서 생육된 잔디 포복경을 이용한 Agrobacterium 형질전환에 있어서 큰 제한인자였던 곰팡이 오염을 제거할 목적으로 포복경 조직에 대한 새로운 살균법을 개발하고자 하였다. 여러 가지 살균방법 중에서 30% NaOCl로 15분간 처리한 다음 0.1% $HgCl_2$로 25분간 처리 했을 때 포복경 절편체의 생존율이 높았으며, 0.1% $HgCl_2$로 처리시 800 mbar의 진공처리를 5분간 실시했을 때 가장 효과적이었다. 또한 Agrobacterium과 공동배양 시 2.5 mg/l의 amphotericin B를 첨가해 준 배지에서 배양했을 때 가장 높은 생존율을 나타내었다. AmB의 처리는 Agrobacterium의 생장에 영향을 미치지 않았다. 또한 살균된 포복경으로 부터 신초의 재분화에도 영향을 미치지 않았으며 곰팡이 오염만을 효율적으로 억제하는 것으로 나타났다. 이러한 결과는 포장에서 대량으로 생육시킨 잔디 포복경을 이용한 Agrobacterium 형질전환 시 그 효율을 증가시키는데 큰 기여를 할 것으로 추측된다.

• 무역상무연구
• /
• 제60권
• /
• pp.257-279
• /
• 2013

Nine FTA like Korea-Chile FTA, Korea-Singapore FTA, Korea-EFTA FTA, Korea-ASEAN FTA, Korea-India CEPA, Korea-EU FTA, Korea-U.S.A. FTA, Korea-Peru FTA and Korea-Turkey have been concluded and implemented in 46 countries as of May, 2013. In addition to these nine FTA, Korea has been negotiating FTA or CEPA(Comprehensive Economic Partnership Agreement) with China and Vietnam and Indonesia. Now Korean government is about to conclude FTA agreement with Indonesia which is one of crucial trading partners in Asian countries so the objective of this paper is to suggest how to design ROO schemes properly in such upcoming FTA agreement since more activation of trade and more utilization of FTA can be depend on the details of ROO schemes. As a result, this paper suggests well-design of ROO schemes as follows ; First, self-issuance origin proof system can be considered because authority-issuance origin proof system may reduce the utilization ratio of FTA. Second, combination of indirect and direct verification system in terms of origin verification system will be more preferable because this will be more fitting to Asian countries as considering trading environments and characteristics of Asian market. Third, criteria to determine origin can be based on wholly obtained plus substantial transformation system which contains CTC plus VC along with some percentage of de minimis. In addition to this, the number of products stipulated in PSR should be minimized and applied similar manner to avoid complexity of deciding origin.

• 한국환경성돌연변이발암원학회지
• /
• 제26권1호
• /
• pp.1-6
• /
• 2006

To enhance our understanding of toxicity mediated through the pathway by which TCDD stimulates gene expression, we have investigated genes whose expressions are changed after treatment with TCDD and/or MNNG in human Chang liver cell. First, we treated with MNNG and TCDD for two weeks to transform human Chang liver cell. We obtained cell looks like to be transformed and compared the differential gene expression by using cDNA chip (Macrogen) which carrys genes related with signal transduction pathways, oncogenes and tumor suppressor genes, etc. We found that TCDD up- or down-regulated 203 and 111 genes including oncogenes and tumor suppressor genes in human Chang liver cell two fold or more, respectively. Second, we compared the differential gene expression after treatment with TCDD only by using cDNA chip (Superarray) which carrys genes related with cell cycle regulations, and found that TCDD up regulated genes related with cell proliferation as well as cell growth inhibition in human Chang liver cell two fold or more, respectively. These results suggest that toxicity induced by TCDD may reflect sustained alterations in the expression of many genes and that the changes reflect both direct and indirect effects of TCDD.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
• /
• pp.1681-1686
• /
• 1991

In robotics and other fields of engineering, techniques for artificial reality or virtual reality are focused on and studied extensively, e.g., virtual existence for tele-operator systems in robotics, and virtual reality of designed objects in architecture. In order to realize the system we should create physical stimulations according to internal models created by experiences in a human brain. The internal model does not have to have direct connections to the real world, however, the stimulation must be signals such that the internal model are retrieved in a human brain. In this paper we propose a technique for tele-virtual reality of dynamic mechanical models, which means that one dynamic mechanical model can be shared by peoples in distant places. Since a stability issue due to time delays arises in the system, we employed a scattering technique developed for a tele-operator system and a kind of passive adaptive controllers. Furthermore, restrictions due to a simple digital implementation of the scattering transformation are discussed and some conditions for stability are shown. The proposed method is applied to a remote tug of war system and the effectiveness is verified.