• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.284-288
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• 2005

This paper proposes the direct detection method of phase angle for the power source, which is based on the PLL method. The proposed method using a bidirectional photo-coupler is used to directly detect the zero crossing of phase voltage and calculate the angular frequency in the controller based on a M/T algorithm. Through the method, the additional installation space in the traditional method using a potential transformer can be minimized and it can be easy to design. The paper presents straightforward schematic circuits, design and experimental results.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2007년도 춘계학술대회
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• pp.221-225
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• 2007

We have prepared $\delta$-phase SbTe alloy with various Sb contents of 64, 72, and 76 at. % and investigated the phase change temperature, the crystal structures of $\delta$-phase SbTe alloy, and determined the ovonic threshold switching voltages with edge contact type phase transition dimensions. As a result, the crystallization temperature is slightly reduced from 126 to $122^{\circ}C$, whereas the melting temperature is not changed. The ovonic threshold switching voltage is reduced from 1.6 to 0.9 V as increasing the Sb content from 64 to 76 at. %. It is found that the reductions of crystallization temperature and the ovonic threshold switching voltage are closely related with the interplanar spacing between adjacent atomic layers and the stacking number of atomic layers in a unit cell.

• 한국표면공학회지
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• 제24권1호
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• pp.16-16
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• 1991

Generally brittle eta phase produced during TiC deposition has a effect on the TRS (transverse rupture strength ; thoughness). Therefore it is necessary to reduce eta(η), phase for the improvement of tool life. At this experiment some properties (TRS, bonding strength, tool life, eta phase)have been investigated by inserting TiN or TiCN underlayer between TiC layer and substrate. The results obtained were as follows; 1. by inserting underlayer eta phase were decreased and TRS was increased, but the bonding strength was decreased. 2. the diffusion of W, Co from the substrate was hindered by the underlayer. 3. TiC layer with TiCN underlayer had the finsest grain size. 4. by inserting underlayer (TiCN or TiN) the tool life was improved and especially notch and crater wear resistance was greatly improved.

• 동력기계공학회지
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• 제4권4호
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• pp.59-64
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• 2000

Especially, demands for the noise reduction of mold transformer has been becoming an common issue because it has been used mainly at the residence area such as building and ship. So, this paper investigates the noise source and countermeasure of mold transformer radiated high noise abnormally. The result of impact hammering test for core of transformer ascertains the core resonance by harmonics of line frequency and high noise can be reduced to avoid core resonance by changing torque strength of tie rod. Magnetic field analysis is performed to identify the reason that noise of V-phase is higher than U and W-phase in the normal condition. It is the cause that flux density and magnetic force of V-phase is higher than the other phase respectively.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권9호
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• pp.438-444
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• 2001

The simple motor construction and low cost, fault tolerant power electronic drive has made the switched reluctance drive a strong contender for many applications. But the switched reluctance drive does exhibit higher levels of vibration and acoustic noise than that of most competing drives. The main source of vibration in the switched reluctance drive is generated by rapid change of radial force when phase current is extinguished during commutation action. In this paper, a hybrid excitation method is proposed to reduce vibration and acoustic noise of the switched reluctance drive. The hybrid excitation has 2-phase excitation by long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are reduced because the scheme reduces abrupt change of excitation level by distributed and balanced excitation.

• 대한화학회지
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• 제57권2호
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• pp.204-209
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• 2013

We calculate in this study the pressure dependence of the frequencies for the Raman modes of A ($A_g$), B ($A_g$, $B_{2g}$) and C ($B_{1g}$, $B_{3g}$) at constant temperatures of 274 and 294K (room temperature) for the solid phase I of benzene. Using the mode Gr$\ddot{u}$neisen parameter of each lattice mode, which correlates the pressure dependence of the crystal volume and the frequency, the Raman frequencies of those modes are computed for phase I of benzene. Our results show that the Raman frequencies of the three lattice modes (A, B and C) increase as the pressure increases, as expected. The temperature effect on the Raman frequencies is not significant, which can be explained by the experimental measurements.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.381-383
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• 2000

The photovoltaic power generation system has a great future as clean energy instead of fossil fuel which has many environmental problems such as exhausted gas or air pollution. In a utility interactive photovoltaic generation system, a three-phase inverter is used for the connection between the photovoltaic array and the utility. This paper presents a three phase inverter for photovoltaic power system with current controller, voltage controller, PLL control system and the phase detector of interactive voltage by using da transformation. The proposed inverter system provides a sinusoidal ac current for domestic loads and the utility line with unity power factor. The results of the operated from January to October show the system characteristics.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권6호
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• pp.146-155
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• 2016

The field feasibility tests for a phytoextraction process were performed to identify the effect of citric acid as a chelate on the uranium (U) transfer into the plant for the naturally U contaminated soil in Duckpyeongri, Korea. For the feasibility tests, lettuce and Chinese cabbage were cultivated for 49 days on four testing grounds ($1m{\times}1m{\times}0.5m$ in each) in 2016. The citric acid solution was added to two testing grounds (one for lettuce and the other for Chinese cabbage) increasing the U transfer in two crop plants and their results were compared to those without the citric acid solution. When without the citric acid solution, the U concentration of plant after the cultivation was low (< $45{\mu}g/kg$ for leaves and < $450{\mu}g/kg$ for roots). However, with the addition of 50 mM citric acid solution, the U concentration of lettuce leaves and roots increased by 24 times and 1.8 times, and the U concentration of Chinese cabbage leaves and roots increased by 86.7 times and 5.4 times. The absolute accumulated U amount (${\mu}g$) in lettuce and Chinese cabbage also increased by 8.7 times and 50 times, compared to those without citric acid solution. Less than 8% of the U amount of exchangeable/carbonate phases was removed by using the lettuce and Chinese cabbage when the citric acid solution was not applied. However 52% and 66% of the U amount in exchangeable/carbonate phases were removed by the lettuce and the Chinese cabbage when the citric acid solution was added. The effect of the citric acid on the U transfer capability into the plants was quantitatively investigated by the field feasibility test, suggesting that U existing as exchangeable/carbonate phase in soil can be successfully removed by the phytoextraction process using Chinese cabbage with citric acid.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1997년도 춘계학술대회
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• pp.69-69
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• 1997

In the screening of tropical medicinal plants using PAE receptor binding assay, the ether extract of Ardisia crispa showed the potent antagonistic activity. Ardisia crispa have been used to heal the scurf, earache, orchitis, fever and diarrhoea, cough and given to the mother after childbirth to ‘wash out dirty blood’ in Malaysia. By means of activity guided isolation, compound AC7-1 was isolated as the potent PAF antagonist. In this study, antiplatelet effects of compound AC7-1 were examined in vitro platelet aggregation assay using the chronolog aggregometer. Compound AC7-1 inhibited PAF-, collagen-, ADP-, thrombin-induced platelet aggregation in human, rabbit and rat platelet rich plasma. In vitro rabbit platelet aggregation, the IC$\_$50/ value of compound AC7-1 was 5 ${\times}$ 10$\^$-6/ M against PAF(5 ${\times}$ 10$\^$-7/M)-induced aggregation. The IC$\_$50/ values of AC7-1 on PAF-induced platelet aggregation increased with increase of the concentration of PAF used. This result suggested the competitive nature of the AC7-1 antagonism. In vitro rat platelet aggregation, the IC$\_$50/ values of AC7-1 on collagen-, ADP-induced platelet aggregation were 4 ${\times}$ 10$\^$-6/ M, 2 ${\times}$ 10$\^$-5/ M, respectively. Also in vitro human platelet aggregation, AC7-1 potently inhibited both the primary phase and secondary phase of thrombin-induced aggregation.

• 정보처리학회논문지B
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• 제19B권1호
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• pp.63-76
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• 2012

본 논문에서는 통계기반의 복합명사 분해 방법과 어휘의미망(U-WIN)과 사전 뜻풀이에서 추출한 의미관계 정보를 이용하는 한국어 복합명사 의미 태깅 시스템을 제안한다. 본 시스템은 크게 복합명사 분해, 의미제약, 그리고 의미 태깅의 세 가지 부분으로 이루어진다. 분해과정은 세종말뭉치에서 추출한 위치별명사 빈도를 사용하여 최적의 구성 명사 분해 후보를 선정하고 의미제약을 위한 구성 명사 재분해와 외래어 복원의 과정을 수행한다. 의미범위 제약과정은 유사도 비교의 계산량을 줄이고 정확도를 높이기 위해 원어 정보와 Naive Bayes Classifier를 이용해 가능한 경우 구성 명사의 의미를 선 제약한다. 의미 분석 및 태깅 과정에서는 bigram 구성 명사의 각 의미 유사도를 구하고 하나의 체인을 만들어가며 태깅을 수행한다. 본 시스템의 성능 평가를 위해 표준국어대사전에서 추출한 3음절 이상의 40,717개의 복합명사를 대상으로 의미 태깅된 테스트 셋을 구축하였다. 이를 이용한 실험에서 99.26%의 분해 정확도를 보였으며, 95.38%의 의미 분석 정확도를 보였다.