• Transactions on Electrical and Electronic Materials
• /
• v.2 no.3
• /
• pp.1-6
• /
• 2001

A simulation method is proposed to study the amorphous structure of carbon nitride. The material properties of a non-uniform nitrogen distribution in an amorphous CN matrix can be studied. The cohesive energy of a group of randomly generated atoms can be minimized to find the relative positions of atoms. From the calculated configuration of atoms, many properties of amorphous carbon nitride can be calculated such as bulk modulus, P-V curve, sp$^3$/sp$^2$ ratio of carbon, and vibrational spectra. The calculation shows that the cohesive energy of non-uniform nitrogen distribution is lower than that of a uniform distribution. This may suggest that the regular structure of carbon nitride can at most be metastable. It is not easy to incorporate nitrogen atoms into a carbon matrix.

• Journal of the Korean Vacuum Society
• /
• v.16 no.1
• /
• pp.74-78
• /
• 2007

Much interests has been drawn for noble micro-engineering processes for the continuous size reduction on bulk materials from the field of micro-electronics with much downsized IC chips. A traditional microprocessing based on mechanical blade as well as a relatively long pulsed laser usually influence the physico-chemical properties of intact materials when the techniques are applied to process materials with a spatial resolution less than 10 microns. Meanwhile, ultrafast laser pulses are known to exhibit a very small heat-affect zone(HAE) compared to the traditional laser processing and to be applicable for the new functional materials with high performance in optical and electrical properties. In this report, we will review in brief the recent research works on the enhancement of micro-cutting speed of thin silicon wafer as well as the formation of Ge nanostructures based on ultrafast laser pulses.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.67-68
• /
• 2002

The properties and mechanism of silicon protuberance and groove processing by diamond tip sliding using atomic force microscope (AFM) in atmosphere were studied. To control the height of protuberance and the depth of groove, the processed height and depth depended on load and diamond tip radius were evaluated. Nanoprotuberances and grooves were fabricated on a silicon surface by approximately 100-nm-radius diamond tip sliding using an atomic force microscope in atmosphere. To clarify the mechanical and chemical properties of these parts processed, changes in the protuberance and groove profiles due to additional diamond tip sliding and potassium hydroxide (KOH) solution etching were evaluated. Processed protuberances were negligibly removed, and processed grooves were easily removed by additional diamond tip sliding. The KOH solution selectively etched the unprocessed silicon area. while the protuberances, grooves and flat surfaces processed by diamond tip sliding were negligibly etched. Three-dimensional nanofabrication is performed in this study by utilizing these mechanic-chemically processed parts as protective etching mask for KOH solution etching.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1784-1787
• /
• 2005

In this paper, proportional modulator which controls the second pressure of the pneumatic system was studied and proportional operating of modulator was gotten by two digital valves that have a fast dynamic characteristics and were controlled by PWM operating method. In order to more precision pressure control, this modulator consist of not only high speed two digital valves but also pressure sensor, measurement equipment and controller having a microprocessing function. In this study, for the development of the new proportional modulator, various research such as PWM control method, test equipment manufacturing, testing and evaluation were accomplished.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.28 no.10
• /
• pp.101-106
• /
• 2014

Although anti-freezing heating cable has been widely installed in most residential boiler pipe, there were excessive energy consumption and fire risk due to inadequate temperature control. In this paper, a new energy saving fire risk-free controller was developed by using microprocessing operation which include detection of not only boiler room temperature but also pipe surface one. Its actual effect has been verified to save more than a half of the energy consumption comparing to conventional controller through temperature and humidity chamber experiment.

• Proceedings of the KIEE Conference
• /
• 1998.07g
• /
• pp.2553-2555
• /
• 1998

A single crystal Mn-Zn ferrite was directly etched by focused $Ar^+$ laser beam in $CCl_2F_2$ gas atmosphere. AES has been performed for locally investigating the surface composition of an etched layer. MnCl, ZnCl being created after the substrate and $CCl_2F_2$ chemically reacting was remained in the vicinity of laser irradiation area because of their low vapor pressure. Various patterns using computer were formed on the substrate. The etched grooves and patterned shapes were observed by SEM measurement.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.43-49
• /
• 2003

Low-temperature polysilicon (LTPS) technology has continued to mature with the passing of each year since LTPS mass production began. The integration of complex circuits has become possible with advances in microprocessing, leading to the realization of panels with highly advanced functions. At the same time, efforts have been made to meet market demands for lower costs, thereby boosting competitive strength. Today, LTPS-TFT LCDs have become standard equipment for the monitors of digital still cameras, and inroads are being made into the massive cellular phone market. Micro displays such as electronic viewfinders, which were previously only possible with high-temperature polysilicon technology, can now also be made with LTPS, thus expanding the scope of the technology. AMOLED displays using the LTPS-TFT as a back plane are also approaching the stage of industrialization. The hidden potential for the OLED to replace the familiar LCD has prompted Widespread anticipation for this emerging technology. This paper reflects on the history of LTPS technology, then looks forward to its future prospects and suggests a variety of potential fields of application.

• Journal of Korean Port Research
• /
• v.11 no.2
• /
• pp.273-280
• /
• 1997

Recently the importance of the cargo handling equipments in a port has been increasing to get strong competition from other ports. Many ports are making efforts to modernize their cargo handling equipments. The kernel technology of such equipments is the speed control of DC motor which is used as an essential part of them. In this paper, we discuss the speed control of a DC motor as a basic work for building cargo handling equipments in a port. DC Motors are still widely used in industrial fields, as driving power motor for electrical fields. DC drives, being easy to control, are widely used in many variable-speed and position control drive system. Traditional analog control circuits used in such applications have many disadvantages. Complex control schemes are difficult to implement with analog components. All these factor and invention of the microprocessor has made it possible to use digital control circuits, using microprocessing system. These digital circuits have been found to be reliable, flexible, and also immune to noise. In this paper it presents the speed control of a SCR DC motor driver which using dual converter by 80c196kc microprocessor. We developed a thyristor power amplifier which does not cause damage thyristor because it is designed to prevent triggering the two SCRs in the same arm simultaneously. And it was analyzed voltage and currents wave at reactive load.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10b
• /
• pp.1649-1654
• /
• 1991

In 1995 the VSOP satellite, which is called MUSES-B in Japan, will be launched under the VLBI Space Observatory Programme(VSOP) promoted by ISAS(Institute of Space and Astronautical Science) of Japan. We are now developing the GPS Receiver(GPSR) and On-board Orbit Determination System. This paper describes the GPS(Global Positioning System), VSOP, GPSR(GPS Receiver system) configuration and the results of the GPS system analysis. The GPSR consists of three GPS antennas and 5 channel receiver package. In the receiver package, there are two 16 bits microprocessing units. The power consumption is 25 Watts in average and the weight is 8.5 kg. Three GPS antennas on board enable GPSR to receive GPS signals from any NAVSTARs(GPS satellites) which are visible. NAVSATR's visibility is described as follows. The VSOP satellite flies from 1, 000 km to 20, 000 km in height on the elliptical orbit around the earth. On the other hand, the orbit of NAVSTARs are nearly circular and about 20, 000 km in height. GPSR can't receive the GPS signals near the apogee, because NAVSTARs transmit the GPS signals through the NAVSTAR's narrow beam antennas directed toward the earth. However near the perigee, GPSR can receive from 12 to 15 GPS signals. More than 4 GPS signals can be received for 40 minutes, which are related to GDOP(Geometric Dillusion Of Precision of selected NAVSTARs). Because there are a lot of visible NAVSTARs, GDOP is small near the perigee. This is a favorqble condition for GPSR. Orbit determination system onboard VSOP satellite consists of a Kalman filter and a precise orbit propagator. Near the perigee, the Kalman filter can eliminate the orbit propagation error using the observed data by GPSR. Except a perigee, precise onboard orbit propagator propagates the orbit, taking into account accelerations such as gravities of the earth, the sun, the moon, and other acceleration caused by the solar pressure. But there remain some amount of calculation and integration errors. When VSOP satellite returns to the perigee, the Kalman filter eliminates the error of the orbit determined by the propagator. After the error is eliminated, VSOP satellite flies out towards an apogee again. The analysis of the orbit determination is performed by the covariance analysis method. Number of the states of the onboard filter is 8. As for a true model, we assume that it is based on the actual error dynamics that include the Selective Availability of GPS called 'SA', having 17 states. Analytical results for position and velocity are tabulated and illustrated, in the sequel. These show that the position and the velocity error are about 40 m and 0.008 m/sec at the perigee, and are about 110 m and 0.012 m/sec at the apogee, respectively.