Mobile QR Code QR CODE : Journal of the Korean Institute of Illuminating and Electrical Installation Engineers

Journal of the Korean Institute of Illuminating and Electrical Installation Engineers

ISO Journal TitleJ Korean Inst. IIIum. Electr. Install. Eng.

테이퍼된 편광유지 광섬유의 테이퍼 구간 길이에 따른 압력 및 온도 응답 변화에 대한 연구 A Study on the Effect of Pressure Sensitivity on the Length of Taper Section in Tapered Polarization Maintaining Fiber

Sungwook Choi ; Yong Wook Lee

In this paper, we propose a temperature-independent polarimetric optical fiber pressure sensor (OFPS) using a polarization Sagnac loop composed of a polarization beam splitter, wave plate combination , and a sensor head. The sensor head consists of 10-cm-long tapered panda-type polarization-maintaining fiber (PMF) and a fiber Bragg grating (FBG) directly spliced with PMF, and the sensor head is located inside a pressure chamber. The tapered section length was varied to 0, 200, 300, and 400μm to investigate the dependence of the pressure sensitivity on tapered section length. A pressure-induced birefringence change of PMF results in a wavelength shift of the interference spectrum. Since the PMF has a cross sensitivity to temperature, the FBG is utilized for the compensation of the temperature effect on it. The FBG, which is sensitive to an ambient temperature change but nearly insensitive to a pressure change, was utilized to compensate for the temperature cross sensitivity of the tapered HBF. From the investigation, the pressure sensitivity of the tapered PMF was found out to be proportional to the tapered length. In consequence, the maximum pressure sensitivity of approximately -22.92nm/MPa could be obtained using tapered PMF with tapered section length of 400μm. Its adjusted R2 value representing the sensor linearity was measured as ~0.9887 in an applied pressure measurement range of 0∼0.5MPa.

자외선 LED기반의 스마트팜 미생물 살균 분석 Analysis of Microbial Sterilization Based on Ultraviolet LEDs for Smart Farm

Beom-Su kim ; Hong-Shik Lee ; Yong-Kab Kim

Recently, introduction of various systems on smart farm has been brought great attention to high-quality green plant production. In the management system of farm, especially in the case of hydroponics, plant and water pollution damages caused by reproduction of harmful bacteria such as Pythium or Fusarium have become repeated problems of plant growth. Therefore, many studies have been researched on contamination of nutrient solution from smart farm with hydroponics and ultraviolet sterilizing system against harmful bacteria. In this paper, a module of 280mW optical power was manufactured using UV-C LED of 278nm wavelength and sterilization effect on E. Coli, C. Michiganensis, P. Cichorii, and F. Oxysporium was analysed under 84mW, 140mW, and 196mW, which are photovoltaic conditions. As a result, when the sterilizing system was exposed to UV-C LED light of 196mW optical output for three minutes, the four kind of microbes were sterilized by 91% and all of the colonies were disappeared by 99.99% after five minutes.

시간대별 차등요금제에서 정수선형계획을 이용한 부하계획법 An Integer Linear Programming based Load Scheduling Method under Time-of-Use Rate

Gwang Won Kim

Load scheduling is a kind of demand response. It is useful for saving electricity bill and for protection of the environment as well. This paper presents a linear programming based load scheduling method under time-of-use rate; all the decision variables are integer and can be 0 or 1. In the proposed method, practical time-related conditions among loads are sincerely considered and another condition of power limit is considered also. The number of decision variables is not much, which is helpful to understand the proposed idea and to get optimal results by integer linear programming. In the case study, the proposed method is applied to a realistic problem considering various situations to show its effectiveness. The proposed method is expected to be applied usefully to energy management system(EMS) for home or factory as well.

변전소 고장복구를 위한 적합도 함수에 관한 연구 A Study on Fitness Function for Substation Fault Restoration

Jae-Young Hong ; Chul-Won Park

In order to reduce blackout recovery time and economic losses, intelligent methods for substation rapidly fault recovery are required. Genetic Algorithm is one of the approaches to solving optimization problems. In this paper, we will study on the fitness function for applying the genetic algorithm for substations recovery. First, the theory(principle) of genetic algorithm is introduced, and then the SOP (Standard Operation Procedure) of the substation is reviewed. A fault recovery algorithm for substation using fitness functions to transformer capacity, DS (Disconnector) switching, transformer and D/L (Distribution Line) is proposed. Finally, the performance of the proposed GA-based fault recovery algorithm is evaluated through several simulation.

고전압 양극성 펄스 파워 모듈레이터를 위한 게이트 직렬 구동에 대한 연구 A Study on the Series Gate Driving for High Voltage Bipolar Pulsed Power Modulator

Seung-Ho Song ; Seung-Hee Lee ; Hong-Je Ryoo

This paper presents the study of the gate circuit of the bipolar pulsed power modulator. In order to output a high voltage bipolar pulse, the modulator has a modular structure in which a full bridge sub-modules are stacked in series. The gate circuit is designed to operate the discharge switch of the sub-module through a simple structure. The entire gate circuit is driven by a signal from a pair of control loops connected through a transformer. The operation of the designed gate circuit is divided into four operating modes according to the input signal and analyzed in detail. The gate signals according to the change of circuit parameters are confirmed by a result of PSpice-based simulation modeling. Testing circuit consisting of top and bottom switches are implemented, and the basic operation is verified by gate drive experiments.

고복굴절 광자결정 광섬유 기반 직렬형 광섬유 투과형 격자를 이용한 스트레인 및 온도의 분리 측정에 관한 연구 A Study on Separate Measurement of Strain and Temperature Incorporating Serial Fiber Transmission Gratings Based on High Birefringence Photonic Crystal Fiber

Do Kyung Kim ; Yong Wook Lee

In this paper, we conducted seperate measurement of strain and temperature incorporating serial fiber transmission gratings (FTGs) based on high birefringence photonic crystal fiber (HBPCF). Two FTGs were fabricated on HBPCF in series using a CO2 laser, and the fabricated sensor have different interference spectra for orthogonal input polarizations aligned to the principal of HBPCF. Two resonance dips with the lowest transmittance in each interference spectrum were designated Dip 1 and 2 and used as sensor indicators. Dip 1 and 2 have different cladding-mode orders due to birefringence of HBPCF. The strain and temperature responses for Dip 1 and 2 of the serial HBPC-FTG were independently investigated in the strain range of 0∼2050με and the temperature range of 30∼90℃, respectively. As a result, Dip 1 and 2 exhibited linear and independent responses in the above strain and temperature range. Based on the previously measured strain and temperature sensitivities, it is possible to separately estimate any strain and temperature changes applied to the serial HBPC-FTG by measuring the wavelength shifts of Dip 1 and 2.

LED구동회로를 위한 새로운 LED단락 검출방법 A Novel LED Short Detection Method for LED Driving Circuit

Jae-Jung Yun

If some LEDs are shorted, overcurrent flows through an LED string consisting of multiple LEDs connected in series. In the LED driving circuit, a current regulator with semiconductor devices such as transistors can protect overcurrent but it generates heat in semiconductor devices, which can damage the LED driving circuit and LED string. In this paper, a novel LED short detection circuit is proposed to solve the LED short problem. The proposed circuit consists of an comparator and a MOSFET and operates in combination with a current regulator. It detects when the LED is shorted and then opens the transistor in current regulator so that the LED current does not flow. To verify the operation and effectiveness of the proposed circuit, a prototype of current regulator and short detection circuit was fabricated and tested by connecting to three LED strings. At LED diving voltage of 18V, The LED currents of all LED strings were 38.7mA∼39.1mA by the constant current operation of current regulators. When a LED is shorted in any LED string and the proposed circuit is not used, the collector-emitter voltage of the transistor in the current regulator was increased to 4.23V and the power consumption of 164.5mW is generated in the transistor. However, when using the proposed circuit, it protects the LED string and LED driving circuit by opening the transistor so that the LED current does not flow.

Rogowski Coil과 Current Transformer의 직렬 아크 사고 측정 신호 비교 Comparison of Series Arc Fault Measurement Signal Between a Rogowski Coil and Current Transformer

Chan-Gi Cho ; Jae-Beom Ahn ; Jin-Han Lee ; Yong-Joo Kim ; Hong-Je Ryoo

The protection method for an arc of the photovoltaic generation system affected by the wire aging and poor contact of electrodes has been required. About a household photovoltaic systems, the series arc fault detection circuit and algorithm has been implemented, and the current transformer (CT) is used to detect the arc current. Although the CT is a useful current sensing device under the low current condition of the household photovoltaic systems, it is difficult to adopt for the medium-size photovoltaic generation system because of the saturation of transformer, wire thickness, and limited winding area. In this paper, the possibility of the sensing method using rogowski coil to detect the series arc fault of the medium-size photovoltaic power plant.