• Journal of the Korean Vacuum Society
• /
• v.15 no.4
• /
• pp.427-433
• /
• 2006

We have fabricated nanodot arrays by using phase separated (PS- b- PMMA) diblock copolymer film and anodic aluminum oxide (AAO) membrane as templates with hexagonal arrays of cylindrical microdomains perpendicular to the substrate. Pulsed laser deposition technique was used to deposit various kinds of materials including Ag, Ni, ZnO, Si:Er, and Co/Pt onto Si substrates. The size and separation of nanodots correspond to those of the templates used, The density of nanodots was estimated to be $6{\times}10^{11}/cm^2$ and $1{\times}10^{10}/cm^2$ when the diblock copolymer and AAO were used, respectively. In particular, the optical properties of ZnO and Si: Er nanodot arrays were investigated and the strong photoluminescence at 380 nm and $1.54{\mu}m$ was observed from ZnO and Si:Er nanodot arrays, respectively.

• Proceedings of the KIEE Conference
• /
• 2001.07c
• /
• pp.1631-1633
• /
• 2001

In manufacturing processes, various and suitable pulse shapes are required for the purpose of material processing and the pulseshape is regarded as a dominant factor due to the specific property of processing materials. Therefore, in this study, a variable pulse width, high duty cycle Pulse Forming Network(PFN) is constructed by time sequently. The power supply for this experiment consists of three switching circuits. The PFN elements operate at low voltage and drive the primary of HV leakage transformer. The secondary of the transformer has a full-wave rectifier, which passes the pulse energy to the load in a continuous sequence of properly phased and nested increments. We investigated laser pulse width as various delay time among three switching circuit. As a result, we tan obtain various laser pulse width from about 4ms to 10ms. The maximum laser pulse width obtained at this experiment was about 10ms at delay time of 4ms among each switching circuit.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.9
• /
• pp.541-545
• /
• 2000

We propose a pulsed $CO_2$laser below 30W by the AC(60Hz) switching control of leakage transformer primary which has some advantages of cost and size compared to a typical pulsed power supply. Pulse repetition rate is adjusted from 5 Hz to 60 to Hz control laser output. In this laser a low voltage open loop control for high voltage pulse discharge circuit is employed to aviod the Hv sampling or switching and high voltage leakage transformer is used to convert low voltage pulse rectified from AC to high voltage one. A ZCS(Zero Crossing Switch) circuit and a PIC(programble one-chip microprocessor are used to control gate signal of SCR precisely. The pulse repetition rate is limited by 60Hz due to the frequency of AC line and a high leadkage inductance. The maximum laser output was about 23 W at pulse repetition rate of 60Hz total gas mixture of $CO_2$ : $N_2$ : He=1: 9: 15 and total pressure of 18 Torr

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.11a
• /
• pp.87-95
• /
• 2005

Laser sealing/cutting technique, one of the 4 core technologies to manufacture self-luminous glass tubes (SLGTs) has been developed. Through the analysis of commercial products it is found that Pyrex Is used for SLGTs. A CO2 laser, which is commonly used for glass work was used for the study The factors affecting the sealing/cutting were laser intensity, duration. Irradiation method, and pressure inside the tube. The whole Process is composed of 2 stages. In the first stage. both ends of the tubes are sealed while tritium is insected in the tubes. And the tritium sealed tubes are cut in the desired size in the second stage. Defocused beam was used for seal ing and focused beam was used for cutting. After the sealing/cutting, the tubes were heat treated to prevent fracture due to the residual heat stress.

• Proceedings of the KIEE Conference
• /
• 1999.07e
• /
• pp.2192-2194
• /
• 1999

In this study, We have accomplished a new approach to develope a cheap and compact pulsed $CO_2$ laser system. We used a fast SCR as switching device instead of a thyatron in the pulsed power supply. Using the Pulse transformer, energy in the condenser is tranferred to the secondary, electrodes of discharge tube, from the primary. An axial and water cooled type was adopted as the laser cavity. The laser performance characteristics as various parameters, such as gas pressure and pulse repetition rate, have been investigated. As a result, the maxium laser output was 12.3[W] at a pulse repetition rate of 120[pps] and a filling pressure of 12[Torr].

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.2
• /
• pp.257-262
• /
• 2008

In this paper, the key parameters of $CO_2$ laser(focus depth, air blow rate, total laser beam time, number of pulse) are experimented for thru-hole and scribing line on AIN(aluminum nitride) substrate with high thermal conductivity. And, microstrip line & spiral planar inductor are fabricated on AIN substrate using 5 um Cu-plating with self-masking technique. The microstrip line of AIN has 0.1 dB/mm attenuation at 10 GHz and 6 nH spiral planar inductor has 56 maximum quality factor at 1 GHz. Thus, the AIN substrate is promising for GHz applications of high power area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.05b
• /
• pp.57-60
• /
• 2000

In this paper, it is purpose to develop a pulsed $CO_2$ laser with stable output at pulse repetition rate range of 2 KHz. We used a IGBT as a switching device. The laser cavity was fabricated as an axial and water cooled type. It was used a ring blower to increase a cooling effect The laser performance characteristics as parameters, such as pulse repetition rate, gas pressure have been investigated. The experiment was done under 3 electrode-type instead of 2 electrode-type. To achieve 3 electrode-type, we used two pulse-transformers which is operated parallel. As a result, the maximum output was about 28 W at the total pressure of 20 Torr, the gas mixture $Co_2$:$N_2$:He=1:9:15 and the pulse repetition rate of 1300 Hz.

• Proceedings of the KIEE Conference
• /
• 1999.11d
• /
• pp.1072-1074
• /
• 1999

In this study, it is the purpose to develope a cheap and compact pulsed $CO_2$ laser with pulse repetition rate range of 1 kHz. We used a IGBT switched power supply as a power supply, which is cheap and simple comparing to others. PIC one-chip microprocessor was used for precise control of a laser power supply on the control part. And the laser cavity was fabricated as an axial and water cooled type. The laser performance characteristics as various parameters, such as pulse repetition rate gas pressure, and gas mixture rate have been investigated. The experiment was done under the condition of total pressure of $CO_2:N_2$:He = 1.3:10, 1:1.5:5 1:9:15 from 6 Torr to 15 Torr and pulse repetition rate from 100 Hz to 900 Hz. As a result, the maximum average output was about 20.5 W at the total pressure of 15 Torr, the gas mixture $CO_2:N_2$:He = 1:9:15 and the pulse repetition rate of 700 Hz.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.2101-2103
• /
• 2000

In this paper, it is purpose to develop a pulsed $CO_2$ laser with stable output at pulse repetition rate range of 2 kHz. We used a IGBT as a switching device. The laser cavity was fabricated as an axial and water cooled type. It was used a ring blower to increase a cooling effect. The laser performance characteristics as parameters, such as pulse repetition rate, gas pressure have been investigated. The experiment was done under 3 electrode-type instead of 2 electrode-type. To achieve 3 electrode-type, we used two pulse-transformers which is operated parallel. As a result. the maximum output was about 28 W at the total pressure, of 20 Torr(the gas mixture $CO_2$:$N_2$:He=1:9:15 and the pulse repetition rate of 1300 Hz).

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.2098-2100
• /
• 2000

We propose pulsed $CO_2$ laser below 30W by the AC(60Hz) switching control of leakage transformer primary which has some advantage of cost and size compared to a typical pulsed power supply. Pulse repetition rate is adjusted from 5Hz to 60Hz to control laser output. In this laser, a low voltage open loop control for high voltage discharge circuit is employed to avoid the HV sampling or switching and high voltage leakage transformer is used to convert rectified low voltage pulse to high voltage one. A ZCS(Zero Cross Switch) circuit and a PIC one-chip microprocessor are used to control gate signal of SCR precisely. The pulse repetition rate is limited by 60Hz due to the frequency of AC line and a high leakage inductance. The maximum laser output was obtained about 23W at pulse repetition rate of 60Hz, total gas mixture of $CO_{2}/N_{2}$/He = 1/9/15, SCR gate trigger angle 90$^{\circ}$, and total pressure of 18Torr.