• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.1133-1136
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• 1999

A magnetic levitation control system is inherently nonlinear and very unstable. Thus there should be a stabilizing compensator network and a negative feedback path using noncontact photoresistor or ultrasonic sensors for the levitation operation. Since the photo sensor plays a key role in the system, the steady-state error and transient performance of the overall system depend on the characteristics of the sensors. But the sensor itself also suffers from nonlinearity, and the magnitude of sensor input heavily depends on environmental conditions. To improve the output performance, we added a linearizing circuit for the sensor characteristics and a disturbance cancelation circuit to avoid sensitive output due to extraneous interfering light.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.1
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• pp.18-22
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• 2012

In this paper, we propose a sensor-based LED lighting system that can significantly reduce standby powers. The proposed LED lighting system has the more advanced power circuit and control mechanism compared to existing one. The whole power circuit consists of two subcircuits. One is designed to apply electric powers to controller, PIR(Pyroelectric Infrared Ray) sensor and CdS, and the other one is designed to apply electric powers to LED module. Such a power circuit configuration makes the standby powers reduction of LED lighting system possible. From the experimental results, we confirmed that the standby powers saving performance of the developed power circuit is superior to that of the conventional one.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.429-434
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• 2019

A lateral flow immunoassay platform utilizing antibody functionalized water soluble CdSe/ZnS semiconductor quantum dots (QDs) was developed for the analysis of human serum amyloid A-1 (hSAA1) in a buffer solution. hSAA1 was chosen as a target protein because it is regarded as a potential biomarker associated with early diagnosis and prognosis in patients of lung cancer. The immunoassay strip on a nitrocellulose membrane was fabricated by spraying two lines composed of a test line with a monoclonal antibody against hSAA1 (10G1) (anti hSAA1) and a control line of anti-chicken IgY. While the CdSe/ZnS QDs synthesized in an organic phase were transferred to a water phase by ligand exchange using carboxylic acid modified alkane thiol. The QDs was then conjugated to monoclonal antibody against hSAA1 (14F8) [anti hSAA1 (14F8)] and used as a fluorescent detection probe. The sequential lateral flow of hSAA1 in different concentration and QDs-anti hSAA1 (14F8) complex allowed to form the surface sandwich complex of anti hSAA1 (10G1)/hSAA1/QD-anti hSAA1 (14F8), which was then analyzed using fluorescence microscope. A 100 nM concentration of hSAA1 protein can be detected by naked eyes under an optimized lateral flow buffer condition with a sensing time of 5 mins.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.99-100
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• 2011

본 논문에서는 CdS센서를 이용하여 장애물의 위치를 판단하고 목적지까지의 최단거리를 계산하여 항체를 주행시키는 시스템에 대해 제안한다. 제안한 시스템은 크게 장애물의 위치를 판단하는 구조물부와 무인항체, 그리고 이것을 관장할 윈도우 기반의 Supervisory program으로 구성된다. 본 논문에서는 제안한 시스템의 S/W와 H/W를 설계하고 구현한 결과를 제시한다.

• Journal of Energy Engineering
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• v.20 no.4
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• pp.353-357
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• 2011

An embedded two-axis solar tracking system was developed by using AVR micro controller for enhancing solar energy utilization. The system consists of an Atmega128 micro controller, two step motors, two step drive modules, CdS sensors, GPS module and other accessories needed for functional stability. This system is controlled by both an astronomical method and an optical method. Initial operation is performed by the result from the astronomical method, which is followed by the fine controlled operation using the signals from Cds sensors. The GPS sensor generates UTC, longitude and latitude data where the solar tracker is installed. A database of solar altitude, azimuth, and sunrise and sunset times is provided by UART (Universal Asynchronous Receiver/Transmitter).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.12
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• pp.1177-1183
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• 2012

This study aims to develop a system that maximizes the radiative heat transfer from the heliostat to the receiver by using the configuration factor and a solar tracking device. As the heat transfer from the heliostat to the receiver is delivered by solar radiation, the configuration factor commonly utilized for radiation is applied to control the heliostat. Tracking the sun and calculating its position are possible by using an illuminance sensor (CdS) and Simulink. By applying optimized algorithms programmed using Simulink that maximize the configuration factors among the heliostat, receiver, and sun in real time, the solar absorption efficiency of the receiver can be maximized. Simulations were performed on how to change the angle required to control the elevation and azimuthal angle of the heliostat during the daytime with respect to various distances.

• Journal of Sensor Science and Technology
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• v.6 no.4
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• pp.328-336
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• 1997

The CdSe thin films were grown on the Si(100) wafers by a hot wall epitaxy method (HWE). The source and substrate temperature are $600^{\circ}C$ and $430^{\circ}C$ respectively. The crystalline structure of epilayers was investigated by double crystal X-ray diffraction(DCXD). Hall effect on the sample was measured by the van der Pauw method and studied on the carrier density and mobility dependence on temperature. From Hall data, the mobility was increased in the temperature range 30K to 150K by impurity scattering and decreased in the temperature range 150k to 293k by the lattice scattering. In order to explore the applicability as a photoconductive cell, we measured the sensitivity(${\gamma}$), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in Cu vapor compare with in Cd, Se, air and vacuum vapour. Then we obtained the sensitivity of 0.99, the value of pc/dc of $1.39{\times}10^{7}$, the MAPD of 335mW, and the rise and decay time of 10ms and 9.5ms, respectively.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1733-1735
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• 2002

The important parameters deciding the fluctuation of laser beam are smoothing capacitor, frequency and the characteristics of laser resonator. In this thesis, we control the fluctuation of $CO_2$ laser in realtime by changing Duty-Ratio of IGBT and switching frequency with fixed the smoothing capacitor to improve the fluctuation of laser beam. We detect the light on laser resonator using a CdS photo sensor to improve ripple factor of laser beam and feedback fluctuated signals refined by a band pass filter into the control circuit to stabilize fluctuation actively. There is much to be desired in the realtime controlling technique of the light on laser discharge tube in electrical signal. We propose switching control technique with microprocessor and photo sensing technique by controlling switch devices optimum operation and feedback signals detected by a photo sensor into the laser power supply in order to improve ripple factor of the $CO_2$ laser beam.

• Electrical & Electronic Materials
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• v.9 no.10
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• pp.1027-1032
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• 1996

The auto-illumination controller for office, residence, and so on was studied. The system consists of parts of a power supply, a signal oscillator, a lamp controller and two kinds of sensor. The lamp controller has two thyristors triggered by the IR sensor(SCRI) and CdS sensor(SCR2) respectively, When the illuminance around this system is higher than operating value of its sensor, lamp is turned off automatically. Otherwise, the light of lamp gets dim by CdS sensor. In case IR sensor senses the body heat of people around itself, the illuminance of the lamp gets maximum. The illuminance of the lamp can be changed dimmly by control of the variable resistor (RV) connected with SCR2 in series. The turning - on time of the lamp can be also controlled using a variable resistor(Rt) connected with a signal oscillator in parallel. Changing resistance Rt changes the time constant(.tau.), which triggers the gate of SCR2. Though people left the surrounding of lamp, the lamp keeps light for a while.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.89-95
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• 2014

An LED lighting which adjusted brightness according to the surround ambient implemented using PWM technology and power devices. To measure the brightness of surround ambient a CdS sensor was used. A control board for the generation of the PWM signal was made using a MCU and duty ratio was controlled according to light intensity of surround ambient of the system. To drive the LED lamps which require high-voltage and high-current power devices were used for switching the DC power supply. Measurement results show that the IGBT is excellent as only lineality but the PowerBJT is more good to consider to efficiency and cost.