• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.421-422
• /
• 2011

The first part is about development of a liquid target for a neutron source, which is designed to overcome many of the limitations of traditional beam-target neutron generators by utilizing a liquid target neutron source. One of the most critical aspects of the beam-target neutron generator is the target integrity under the beam exposure. A liquid target can be a good solution to overcome damage to the target such as target erosion and depletion of hydrogen isotopes in the active layer, especially for the one operating at high neutron fluxes with no need for water cooling. There is no inherent target lifetime for the liquid target neutron generator when used with continuous refreshment of the target surface exposed to the energetic beam. In this work, liquid target containing hydrogen has been developed and tested in vacuum environment. Potentially, liquid targets could allow a point neutron source whose spatial extension is on the order of 1 to $10{\mu}m$. And the second is about the vacuum ultraviolet (VUV) spectrometer which is designed as a five-channel spectral system for ITER main plasma measurement. To develop and verify the design, a two-channel prototype system was fabricated with No. 3 (14.4 nm~31.8 nm) and No. 4 (29.0 nm~60.0 nm) among the five channels. For test of the prototype system, a hollow cathode lamp is used as a light source. The system is composed of a collimating mirror to collect the light from source to slit, and two holographic diffraction gratings with toroidal geometry to diffract and also to collimate the light from the common slit to detectors. The two gratings are positioned at different optical distances and heights as designed. To study the appropriate detector for ITER VUV system, two different electronic detectors of the back-illuminated charge coupled device and the micro-channel plate electron multiplier were installed and the performance has been investigated and compared in the same experimental conditions. The overall system performance was verified by measuring the spectrums.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.657-662
• /
• 2005

In this study, the deposition of micrometer-scale metallic interconnects on LCD glass for the repair of open-circuit type defects is investigated. Although there had been a few studies Since 1980 s for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and $W(CO)_6$ was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 nm depending on laser power and scan speed while the width was controlled between $3\~50{\mu}$ using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below 1 $O\cdot{\mu}m$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.28 no.5
• /
• pp.395-400
• /
• 2008

Alternating magnetic field was used for detection of surface flaws on nonmagnetic and magnetic metallic specimens. The nondestructive sensor probe was composed of the planar coil with inductive magnetic thin film yoke as a sensing component and a single straight typed exciting coil. The planar inductive coil sensor with magnetic yoke was fabricated by sputtering, electroplating, dry etching and photolithography process. The alternative currents with the range of 0.1A to 1.0A (0.7 MHz to 1.8 MHz) were applied to the exciting coil. The specimens were prepared with the slit shaped artificial surface flaws (minimum depth and width; 0.5 mm) on metallic plate (Al; nonmagnetic metal and FeC; magnetic metal). The detected signal for the positions and shapes of surface flaws on specimens were obtained with high sensitivity and high signal to ratio. The measured output signals by the non-contacted scanning on surface of FeC specimen with micron-sized crack were converted to the images of the flaws. And these results were compared with the optical images, respectively.

• Korean Journal of Optics and Photonics
• /
• v.10 no.5
• /
• pp.430-438
• /
• 1999

We have utilized soft-aperturing by gain media to develop a high-power tunable Ti:Sapphire laser with sub-40-fs and broad tuning range. The tunable spectral range was only limited by the bandwidth of mirrors. We made use of knife-edge slits near an intra-cavity prism controlled by micro-stepping-motors to tune the center wavelength continuously. The tunability of the center wavelength was ranged from 770 nm to 870 nm, and the measured pulsewidth was sub-40 fs throughout the above spectral range. The shortest pulsewidth was about 17 fs at the center wavelength of 820 nm and the spectral bandwidth was 72 nm. At 5 W pumping power of the Ar-ion laser we obtained average output power of 440 mW~580 mW. For the cw and Kerr-lens mode-lodking conditions, we have evaluated the value of an amplitude modulation to be ${\gamma}=2.5{\times}10^{-8}/W$ from the calculated waists of a Gaussian beam on the Ti:sapphire crystal surface. Using this result we demonstrate that the generation of sub-40-fs Kerr-lens mode-locked pulse can be described by the Ginzberg-Landau model which is a weak pulse shaping model.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.8 s.173
• /
• pp.165-173
• /
• 2005

This paper presents the results for deposition of micrometer-scale metal lines on glass for the development of TFT-LCD circuit repair-system. Although there had been a few studies in the late 1980's for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and W(CO)s was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 m depending on laser power and scan speed while the width was controlled between 50um using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below $1{\Omega}{\cdotu}um$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.1
• /
• pp.42-53
• /
• 2004

An experimental study on the refrigerant-side pressure drop of slit fin-tube heat exchanger has been carried out. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the pressure drop on design conditions of condenser in micro-fin tube for R22 and its alternatives, R407C (R32/125/134a, 23/25/52 wt.％) and R410A (R32/125, 50/50 wt.％). Experiments were carried out under the conditions of inlet refrigerant temperature of 6$0^{\circ}C$ and mass fluxes varying from 150 to 250 kg/$m^2$s for R22, R407C and R410A. The inlet air conditions are dry bulb temperature of 35$^{\circ}C$, relative humidity of 40% and air velocity varying from 0.68 to 1.43 m/s. Experiments show that pressure drop for R410A and R407C were 17.8∼20.2％ and 5∼6.8％ lower than those of R22 respectively for the degree of subcooling of 5$^{\circ}C$. For the mass fluxes of 200∼250 kg/$m^2$s, the deviation between the experimental and predicted values for the pressure drop was less than $\pm$20％ for R22, R407C and R410A.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.39 no.3
• /
• pp.59-64
• /
• 2002

In the RFID system using ISM-band, The tag mounted at the object has used the DC power by rectifying the RF signals of the small antenna for operating the micro-controller and memory. The performance of the tag would be reduced because of the second harmonics generated by the nonlinearity of the semiconductor and the spurious signal excited the high order mode of the antenna. This paper has realized the novel type low-pass filter with "the Stub-I type DGS slot structure" to improve the efficiency of the tag by suppressing the harmonics. The optimized frequency character at the pass-band/stop-band has obtained by tuning the stub width and slit width of I type slot. The measured result of the LPF has the cutoff frequency 3.25 GHz, the insertion loss about -0.29~-0.3 dB at pass-band 2.4 GHz~2.5 GHz, the return loss about -27.688~-33.665 dB at pass-band with a good performance, and the suppression character is about -19.367 dB at second harmonics frequency 4.9 GHz. This DGS LPF may be applied the various application as the RFID, WLAN to improve the efficiency of the system by suppressing the harmonics and spurious signals. 

• Journal of Energy Engineering
• /
• v.15 no.4 s.48
• /
• pp.243-249
• /
• 2006

An experimental study on the refrigerant-side pressure drop of slit fin an tube heat exchanger has been carried out. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the pressure drop on design conditions of condenser in micro-fin tube for R22 and Rl34a. Experiments were carried out under the conditions of inlet refrigerant temperature of $60^{\circ}C$ and mass fluxes varying from $150\;to\;250\;kg/m^{2}s$ for R22 and Rl34a. The inlet air conditions are dry bulb temperature of $35^{\circ}C$, relative humidity of 40% and air velocity varying from 0.68 to 1.43 m/s. Experiments show that pressure drop for R134a was $22{\sim}22.6%$ higher than R22 for the degree of subcooling $5^{\circ}C$ For the mass fluxes of $200{\sim}250\;kg/m^{2}s$, the deviation between the experimental and predicted values for the pressure drop was less than ${\pm}20%$ for R22 and Rl34a.

• Journal of Fashion Business
• /
• v.3 no.4
• /
• pp.147-160
• /
• 1999

This paper is intended to compare and analyze the fashion trends that were introduced in the recent shows, held abroad and in Korea, so as to investigate how well the designers in Taegu and Kyungbuk (TK) area are keeping up with the international vogue. The research has done, analyzing Pret-a-Porter in Paris and the three events held in the TK area in 1997 -The Taegu Collection, Kyungbuk Fashion Festival and Textile & Apparel Fair and using reference pictures and documentary records. In order to investigate the trends the research is divided by four groups which are the silhouette, the detail, the color and the Fashion image and has done with the help of three postgraduate students. The results are as follows. 1. The Silhouette The slim-line has the greatest importance in the silhouette analysis of the recent collections. Like Elongated and Fit & Flare, tight-fitting and female-line were also appeared quite a lot. Compared with foreign collection, Korean collections put the bigger importance on the slim-line. 2. The Detail The printings, using paintings and plant-logos had the large portion of the accessories in both foreign and Korean collections. Draw string and wrap style were also presented a lot. Especially, at the Korean collections, layerd, corsage, and craft accent were emphasized, too. As for the necklines the similarity was found over the four events considering. Camisole neckline and halter neck were presented the most, and bared top, Vneckline, boat and low-neck which can highlight the feminity were often appeared as well. Considering collars, tailored and peaked collars which are frequently used for the jackets, were usually shown at the collections. Like convertable, shirts, wing and Italian collar, the collars that can be applied for the sports wears were presented a lot. Virtually no variation of design was found in the sleeve analysis. While set-in-sleeve and sleeveless were found commonly, not so many ornaments were added to the sleeves. The ankle and knee length for the pants and skirts were common. Furthermore, including the micro-mini, showing extremely feminine style the mini-style had the 20% portion of the skirt-length. Unbalanced lengths, using bias-cut were presented quite a lot on the runways. Deep slit skirts, wide pants and irregular hem skirts were in vogue. On the runways of Paris, more than 21% of the design was the burmuda pants. 3. The Color Red and Blue were in vogue in the four collections considering. Sometimes, yellowish was combined in Korean collections. Black and pale tone were appeared to be in fashion also with light grayish, moderate and deep tone. 4. The Fashion image As for the fashion image, feminine-decorative trend amounted to the large percentage in korean collections. At the foreign collection feminine-decorative trend and feminine trend were predominant, then mannish trend and simple trend were apeared equally. The research shows that TK area and foreign collections are fairy similar, which means that the designers in TK area have been making their efforts to satisfy the clients who have the international minds. However, compared with foreign collections, TK collections were apprered to be strongly inclined to only a few trends. Consequently the season trends are not as diverse as the foreign trends, which cannot satisfy the fashion taste of the clients in TK area. The local designers should know the tendency and the taste of the clients and make the more efforts to read local clients' mind.