• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1657-1658
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• 2006

An external electrode fluorescent lamps (EEFLs) have the advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Studies on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high brightness using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter. To solve these problems of CCFL, EEFL (External Electrode Fluorescent Lamp) is introduced. Because electrode of EEFL is on the outer surface of discharge tube, the electrode is perfectly prevented from the sputtering by accelerated ions. And it is possible to drive the many CCFLs at the same time, because EEFL shows the positively resistant characteristic. But EEFL has the large non-radiative power loss in sheath. In this study the novel electrode structure was introduced in order to reduce non-radiative power loss in sheath of EEFL. The novel electrode structure comes from the idea to combine conceptually capacitive discharge with inductive discharge. Thus, this study verifies the change in the optical characteristics according to the change in electrode structure through a Maxwell's electromagnetic field simulation and examines the relationship between the change in the EEFL electrode structure and brightness by measuring the optical characteristics.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1621-1622
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• 2006

This paper presents the effect of driving waveform for piezoelectric bend mode inkjet printhead with optimized mechanical design. Experimental and theoretical studies on the applied driving waveform versus jetting characteristic s were performed. The inkjet head has been designed to maximize the droplet velocity, minimize voltage response of the actuator and optimize the firing frequency to eject ink droplet. The head design was carried out by using mechanical simulation. The printhead has been fabricated with Si(100) and SOI wafers by MEMS process and silicon direct bonding method. To investigate how performance of the piezoelectric ceramic actuator influences on droplet diameter and droplet velocity, the method of stroboscopy was used. Also we observed the movement characteristics of PZT actuator with LDV(Laser Doppler Vibrometer) system, oscilloscope and dynamic signal analyzer. Missing nozzles caused by bubbles in chamber were monitored by their resonance frequency. Using the water based ink of viscosity of 4.8 cps and surface tension of 0.025N/m, it is possible to eject stable droplets up to 20kHz, 4.4m/s and above 8pL at the different applied driving waveforms.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.11
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• pp.968-972
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• 2008

Ni/Ti/Al multilayer system ('/'denotes the deposition sequence) was tested for low-resistance ohmic contact formation to Al-implanted p-type 4H-SiC. Ni 30 nm / Ti 50 nm / Al 300 nm layers were sequentially deposited by e-beam evaporation on the 4H-SiC samples which were implanted with Al (norminal doping concentration = $4\times10^{19}cm^{-3}$) and then annealed at $1700^{\circ}C$ for dopant activation. Rapid thermal anneal (RTA) temperature for ohmic contact formation was varied in the range of $840\sim930^{\circ}C$. Specific contact resistances were extracted from the measured current vs. voltage (I-V) data of linear- and circular transfer length method (TLM) patterns. In constrast to Ni contact, Ni/Ti/Al contact shows perfectly linear I-V characteristics, and possesses much lower contact resistance of about $2\sim3\times10^{-4}\Omega{\cdot}cm^2$ even after low-temperature RTA at $840^{\circ}C$, which is about 2 orders of magnitude smaller than that of Ni contact. Therefore, it was shown that RTA temperature for ohmic contact formation can be lowered to at least $840^{\circ}C$ without significant compromise of contact resistance. X-ray diffraction (XRD) analysis indicated the existence of intermetallic compounds of Ni and Al as well as $NiSi_{1-x}$, but characteristic peaks of $Ti_{3}SiC_2$, a probable narrow-gap interfacial alloy responsible for low-resistance Ti/Al ohmic contact formation, were not detected. Therefore, Al in-diffusion into SiC surface region is considered to be the dominant mechanism of improvement in conduction behavior of Ni/Ti/Al contact.

• The Korean Journal of Pain
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• v.7 no.1
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• pp.74-77
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• 1994

Since its introduction, low level lasers have been utilized in many varied clinical applications for the treatment of musculoskeletal and body surface lesions. Due to the laser beams specific characteristic-coherence, monochromaticity and unidirectionality, without adverse reaction with neighbouring tissue, physicians have used it with relative ease. We observed accelerating effects of healing process of some intractable skin wound, improvement of graft survival, as well as reduction of pain on ulcerating tissues, by treating twice weekly with low level Helium-Neon(He-Ne) and Infrared(IR) laser. The laser's energy density was set at $1\;J/cm^2$ and a fixed frequency of 600 Hz by continuous scanning. Irradiating time was calculated according to the cross diameter of the wound. Further clinical work will be required to evaluate the accelerated healing processes by biostimulating mechanisms of laser ray, especially for the intractable(diabetic) skin ulceration.

• Applied Microscopy
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• v.28 no.4
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• pp.435-446
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• 1998

It is suggested that Urechis unicinctus is a filler feeder as like many tide and watery invertebrates which filtrate food materials by ciliary movement. However, the structure of the filter is not yet known in U. unicinctus, nor the filtering mechanism is not well understood. This study reveals ciliated epithelial cells in the foregut and the features of the cilia are good accord with that of known filtrating apparatus of other tide animals. This may implies that the foregut is in function of filtration and the food materials are filtrated by the ciliary movement. With the observation of the filtrating apparatus in the foregut, the intestine of U. unicinctus can be functionally compartmented into 3 parts. These are already known midgut and hindgut in function of digestion and respiration respectively, and the foregut in function of filtrating apparatus for foods. The filtrating apparatus of U. unicinctus is composed of the pseudostratified columnar epithelial cells with numerous cilia. The cilia are well differentiated kinocilia with the typical microtubule pattern, kinetosome and cilia roots. There are two kinds of striated cilia roots, the main root and the accessory root. The main root is extended perpendicularly from the cell surface to basement membrane and the short accessory root is branched with an acute angle of about $80^{\circ}$ from the main root at level of basal plate of the kinetosome. The spacial approaches of the main root with the large fused form of mitochondria is one of the characteristic features which might be in structural consideration an intimate association between energy source and energy mass consuming cell organelles.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.515-520
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• 2007

Recently, the treat of sludge is usually progressed by ocean disposal. But it will be totally banned by content of its heavy metal according to London Dumping Convention, gradually. The stable way of treat of sewage sludge should be examined urgently. To solve the problem, recently, there are efficient and environment-oriented method. One of them is to produce absorbent through the activation. This study produces absorbent through steam activation. As basic experiment, optimum activation condition for preparation of good absorbent is researched through study of the fellowing variables : steam flow rate, activated temperature, activation time. As the result of this with standard on iodine adsorptivity, it is chosen, that steam flow rate "30 mL/hr", activation temperature $"500^{\circ}C"$, activation time "60 minutes". At the time, iodine adsorptivity and yield shown that 228.4 mg/g, 77.23%. And also, by using nitrogen adsorption, SEM and EDS are confirmed that pore development, specific surface area, mean pore size, chemical component and content. Pore developed by steam activation is also confirmed that it is micropore.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.477-486
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• 2017

For the analysis of the optical characteristics of electrodeless lamps, all the lamp surface temperatures have been treated the same. However, the interpretation of optical properties in this way has not been sufficient in terms of accuracy. In this paper, to overcome this problem, we divided the inside of the bulb into two parts, hot spot and cold spot, and analyzed the density difference of mercury by different temperatures. Here, it is assumed that the distribution of temperature and density is linear. The effect of optical characteristics through redistribution of hot spot and cold spot density was analyzed. It was also confirmed that the ratio of the density of the redistributed discharge gas has a great influence on the saturation of the optical characteristics. Therefore, it is proved that the design method through the domestic setting is very useful in the actual design, and the method for shortening the time for stabilizing the optical characteristics is obtained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.6
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• pp.130-136
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• 2002

A novel ozonizer has been developed using a high frequency surface discharge and a high purity Ti-Si-Al ceramic catalyst as its dielectric component. A cylindrical thin compound ceramic catalyst in reactor is adhered to inside of the film-like outside electrode. And, when experiment condition are oxygen gas temperature of 20 ［$^{\circ}C$］, inner reactor pressure of 1.6 atm 600［Hz］ and flow late of 2［l/min］. the ozonizer can easily produce ozone concentration(50～60［g/㎥］for oxygen) and power efficiency(180［g/kWh］for oxygen) without using a special enrichment means. At 2［l/min］, 20［$^{\circ}C$］, 1.6［atm］, 600［Hz］and 40［W］, the result of simulation to gas temperature of reactor using general code Phoenics, the maximum temperature of reactor was 132［$^{\circ}C$］in reactor. Ant the result electric field simulation of Ti-Si-Al type reactor using general code Flux 2D, maximum electric field was 0.131E.08［V/m］.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2914-2920
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• 2013

In this paper, we prepared the samples with the heat-treated substrate by means of co-evaporation method. The samples prepared with heat-treated substrate of $500^{\circ}C$showed the vacancy on the surface, and it could be prevented by Se ambient condition. The samples prepared with variable heat-treated substrates such as $430^{\circ}C$, $460^{\circ}C$, $480^{\circ}C$ and $500^{\circ}C$ showed the increase of grain resulted to the increase of the density. Based on the XRD analysis, the heat treatment could remove the Cu2Se phase of the samples, but it didn't affect the absorption index of the samples. We, therefore, conclude the absorption index is not affected by heat treatment and is controlled by the thickness of the sample.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6403-6410
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• 2015

Medical polymer PLGA is biocompatible, biodegradation, mechanical characteristic and biostability, and the degradation time can be adjust by controlling the number of monomer. In this paper, PLGA membranes have different composition ratio by L/D type was prepared by phase transition method. And the PLGA membrane in phosphate buffered saline(PBS) at the different test temperatures for different periods of time to examined for change in mass and measured the pH of degradation media. Measurement of Tg and surface structure was performed using a DSC and Stereoscopic microscope. As the molecular weighter increase, hydrolysis rate was decrease in geometrical progression. According to the composition ratio by L/D type, degradation rate and the change of pH are large.