• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1994년도 하계학술대회 논문집 C
• /
• pp.1571-1573
• /
• 1994

In order to substitute for the conventional measuring system which could bring about technical inconveiences, measuring techniques for the fast transient high voltage upto 100 kV and small signals less than 1 V are developed by use of Laser Source with Packets cell. for the former, capacitive voltage divider was specially designed for reducing the impulse voltage less than the half-wave voltage of pockets cell. For the tatter, interferometer type was employed as a mean to removing the fluctuation of Laser output intensity. And also the main beam through the Pockels cell and the reference beam from the Laser source are seperated before being detected respectively by photo diodes. And then, these two signals are amplified and compared for detecting only the small signals applied across the Pockels cell. Throughout this work, Laser-based measuring system is likely to enable us, at this moment, to detect correctly lightning impulse voltage upto 100 kV and the small signals less than 1 V upto the 2 MHz. Such a system could be employed as a possible diagnostic measuring system at the substation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1991년도 하계학술대회 논문집
• /
• pp.846-849
• /
• 1991

This paper reports the principle, system confiquration, test results of optical voltage sensor using quartz pockels cell. The Pockels effect of quartz material is used for designing optical voltage sensor. The quarts material has very high half-wave voltage, so, it can be applied to measure high voltage level. Experimental results show that the optical voltage sensor has excellent linear characteristics within the applied AC voltage of 1200V.

• Journal of Magnetics
• /
• 제19권1호
• /
• pp.20-27
• /
• 2014

This study examined the relationships between protein expression and Poly ADP ribose polymerase in brain cell death in brains damaged by thrombotic stroke and treated with the Full Wave- Cockroft Walton (FWCW) method of Transcranial Magnetic Stimulation (TMS). The two-way switching element for TMS drove a half-bridge inverter of the current resonance of direct current voltage (+) and direct current voltage (-), and the experiment was conducted by stimulating the mice with thrombotic stroke through a range of pulses. Thrombotic stroke was caused of ligation of the common carotid artery of male SD mice, and blood reperfusion was conducted five minutes later. Protein expression was examined in immune reaction cells, which reacted to an antibody to Poly ADP ribose polymerase in the cerebrum cells, and western blotting. Observations of the PARP changes after thrombotic stroke showed that the number of Poly ADP ribose polymerase reactions were significantly lower (p < 0.05) in the group treated with TMS of the FWCW than the group with thrombotic stroke 24 hours after its onset. The application of FWCW-TMS helped prevent the necrosis of nerve cells and might prevent the brain damage that occurs as a result of thrombotic stroke, and improve the function recovery and disorder of brain cells.

• 한국전기전자재료학회논문지
• /
• 제13권8호
• /
• pp.688-693
• /
• 2000

In this paper an optical voltage sensor and an optical current sensor which can be used for the measurement of impulse voltage and current are implemented. BSO single crystal is utilized as a voltage sensor(Pockels effect cell). An rare earth doped YIG is used as a current sensor(Faraday effect cell). A new signal processing technique is adopted not only to avoid the influences o external optical fiber pertubations of transmitting optical fiber but also to improves the frequency response characteristics of the fiber-optic voltage and current sensors. Experimental results show that optical voltage sensor has maximum 2.5% error within the voltage range from 0V to 500V. and optical current sensor has maximum 2.5% error within the current range and that of optical current sensor is about 1.5% within temperature range from -2$0^{\circ}C$ to 6$0^{\circ}C$. The proposed optical sensors have good frequency response characteristics within the frequency range from DC to 10MHz.

• 수산해양기술연구
• /
• 제53권4호
• /
• pp.309-316
• /
• 2017

In this paper, numerical modeling is conducted to analyze the tension of an anchor line by varying the size and drag coefficient of a buoy when the trapnet is influenced by the wave and the current simultaneously. A mass-spring model was used to analyze the behavior of trapnet underwater under the influence of waves and current. In the simulation of numerical model, wave height of 3, 4, 5 and 6 m, a period of 4.4 s, and the flow speed of 0.7 m/s were used for the wave and current condition. The drag coefficients of buoy were 0.8, 0.4 and 0.2, respectively. The size of buoy was 100, 50 and 25% based on the cylindrical buoy ($0.0311m^3$) used for swimming crab trap. The drag coefficient of the trapnet, the main model for numerical analysis, was obtained by a circular water channel experiment using a 6-component load cell. As a result of the simulation, the tension of the anchor line decreased proportional to buoy's drag coefficient and size; the higher the wave height, the greater the decrease rate of the tension. When the buoy drag coefficient and size decreased to one fourth, the tension of the anchor line decreased to a half and the tension of the anchor line was lower than the holding power of the anchor even at 6 m of wave height. Therefore, reducing the buoy drag coefficient and size appropriately reduces the trapnet load from the wave, which also reduces the possibility of trapnet loss.

• 에너지공학
• /
• 제23권3호
• /
• pp.157-162
• /
• 2014

해당 연구에서는 수정된 폴리올법을 이용하여 합성한 카본블랙 탄소지지체의 Pt촉매의 전기적, 전기화학적 특성을 평가하였다. 또한 Polyol_Pt/C 촉매는 고분자전해질연료전지의 공기극에 적용하여 산소환원반응성을 측정하였다. 산소환원반응성과 고분자전해질연료전지 성능평가를 통해 상용 Pt/C (JM_Pt/C)촉매와 비교하여 전기화학적인 촉매성능을 비교하였다. 촉매의 활성표면적을 구하기 위해 순환전압전류주사법을 이용하였고, 산소환원반응성을 측정하기 위해 회전원판전극으로 선형주사전류법을 이용하였다. 또한 고분자전해질연료전지 완전지 성능 측정을 진행하였다. 그 결과 Polyol_Pt/C 촉매의 활성표면적 ($196m^2g^{-1}$)은 JM_Pt/C 촉매의 그 값 ($183m^2g^{-1}$) 보다 우수하였다. 촉매들의 산소환원반응성에 경우에도 Polyol_Pt/C 촉매는 JM_Pt/C 촉매보다 우수한 반파장전위 및 한계전류밀도를 나타내었다. 또한 완전지 평가시, MEA 공기극을 위한 Polyol_Pt/C 촉매 담지량을 기존의 0.4에서 0.15로 줄였을 때, 성능저하가 적게 나타났고, 300시간의 장기간 성능 평가에서도 연료전지 성능이 거의 일정하게 유지되었다. 이를 토대로 수정된 폴리올법에 의해 합성된 Polyol_Pt/C 촉매는 경제적인 이용 및 우수한 내구성을 가지고 있음을 밝혀내었다.

• 한국전기전자재료학회논문지
• /
• 제33권6호
• /
• pp.475-482
• /
• 2020

For electronic paper displays using electrophoresis, the response time and reflectivity of the image panel fabricated by filtering are analyzed. For the filtering process, a square wave and ramp wave are applied to white charged particles with a unique q/m value. We divide the sample panels into #1 to #4 according to the applied waveform in the filtering process. Step waves comprising two steps are used to drive the panel; therefore, we divide the driving conditions into D1~D4. The applied voltage at the first stage of the half cycle of the driving waveform moves the charged particles attached via the image force from the electrode, and the applied voltage at the second stage moves the floating charged particles by detaching. As mentioned, four types of driving conditions (D1 to D4) classified according to the half cycle of the driving waveform are applied to the samples #1 to #4), which are classified according to four types of filtering process. When driving condition D1 is applied to the four types of sample panels, the rise time of #1 is 1.59s, #2 is 1.706s, #3 is 1.853s, and #4 is 1.235s, resulting in #4 being relatively faster compared with other sample panels, and showing the same trend in other driving conditions. As a result, we confirm that applying the driving condition D1 causes abrupt movement of the white charged particles injected into the cell. When the same driving waveform (D1) is applied to each sample, reflectivities of 32.1% for #1, 31.4% for #2, 27.9% for #3, and 63.4% for #4 are measured. From the experiment, we confirm that the driving condition D1 (1s of 3.5 V, 9s of 3.0 V) and ramp wave #4 in filtering are desirable for good reflectivity and response time. Our research is expected to contribute to the improvement of the filtering process and optimization of the driving waveform.

• 한국전자파학회논문지
• /
• 제25권3호
• /
• pp.339-347
• /
• 2014

본 논문에서는 유연성 기판을 이용한 새로운 광대역 메타물질 구조의 흡수체를 제안하였다. 제안된 메타 물질 구조의 단위 셀은 유연성 있는 폴리이미드 기판 위의 동일 평면상에 놓여진 ELC 공진기와 cut-wire 구조로 이루어졌으며, 설계 주파수 대역 밖에서 레이더 단면적(RCS) 값을 감소시키기 위하여 제안된 구조의 금속 패턴 층은 입사 전자파의 진행 방향과 평행하게 놓았다. 총 $33{\times}45$개의 단위 셀들의 배열로 이루어진 흡수체 시작품을 제작하고, 측정한 결과, 주파수 9.06 및 15.0 GHz에서 각각 92 % 및 93 % 이상의 최대 흡수율과 75 %의 full-width at half-maximum 대역폭을 나타내었다. 제안된 금속 접지 판이 없는 메타물질 구조는 마이크로파 주파수대 광대역 흡수체로 곡면 구조에도 응용이 가능하다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 하계학술대회 논문집 E
• /
• pp.1705-1707
• /
• 1997

In this work, a possible new PD de technique, based on the electro-optic effect(P effect), has been proposed. The refractive index ellipsoid of EO crystal, as $LiNbO_3$, is changed by both the externally a electric field and its hysteresis loop of which effect on this hysteresis loop gives rise t discrepancy of index variation. Therefore, an eq regarding the phase variation of modulated beam through $LiNbO_3$ crystal under applied e field, is newly proposed considering the influen hysteresis characteristics. For this purpose generated from needle-plane electrode in oil has detected by use of $LiNbO_3$ cell and analyzed b equation. As a result, it is observed that PD measu phase intervals are limited by the cr characteristics such as asymmertrical P-E hyst and half-wave voltage.

• 한국광학회지
• /
• 제19권1호
• /
• pp.48-53
• /
• 2008

본 논문에서는 $90^{\circ}$ 꼬인 네마틱 액정 셀에 전계를 인가하지 않았을 때 어두운 상태를 나타내는 normally black 모드 구현 시, 높은 명암비를 제공하는 광학구조를 제안하였다. 제안된 구조에서 +A 필름과 ${\lambda}/2$ 필름을 각각 1 장씩 사용하여 $90^{\circ}$ 꼬인 액정층을 통과한 빛의 가시광 파장대에서 편광 상태가 거의 동일하게 만들어 줌으로써, 어두운 상태의 분광특성을 향상시킬 수 있다. PSD(Parameter Space Diagram) 방법을 사용하여 최적조건을 구해 계산한 결과 500: 1 이상의 높은 명암비를 확보할 수 있었으며, 어두운 상태뿐만 아니라 밝은 상태의 분광특성도 향상됨을 시뮬레이션 및 실험을 통해 확인할 수 있었다.