• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.150-150
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• 2008

본 연구에서는 Wet chemistry damage가 Nanopatterned p-ohmic electrode에 미치는 영향을 연구하였다. Nanopattern은 Metal clustering을 이용하여, P-GaN와 Ohmic형성에 유리한 Pd을 50$\AA$ 적층한 후 Rapid Thermal Annealing방법으로 $850^{\circ}C$, $N_2$분위기에서 3min열처리를 하여 Pd Clustering mask 를 제작하였다. Wet etching은 $85^{\circ}C$, $H_3PO_4$조건에서 시간에 따라 Sample을 Dipping하는 방법으로 시행하였다 Ohmic test를 위해서 Circular - Transmission line Model 방법을 이용하였으며, Atomic Force Microscopy과 Parameter Analyzer로 Nanopatterned GaN surface위에 형성된 Ni/ Au Contact에서의 전기적 분석과, 표면구조분석을 시행하였다. AFM결과 Wet처리시간에 따라서 Etching형상 및 Etch rate이 영향을 받는 것이 확인되었고, Ohmic test에서 Wet chemistry처리에 의한 Tunneling parameter와 Schottky Barrier Height가 크게 증/감함을 관찰하였다. 이러한 결과들은 Wet처리에 의해서 발생된 Defect가 GaN의 표면과 하부에서 발생되며, Deep acceptor trap 및 transfer거동과 밀접한 관련이 있음을 확인 할 수 있었다. 보다 자세한 Transport 및 Wet chemical처리영향에 관한 형성 Mechanism은 후에 I-V-T, I-V, C-V, AFM결과 들을 활용하여 발표할 예정이다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.102-110
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• 2012

ZigBee networks developed for low power and short range communication are being used as home network solution for ubiquitous computing. However, as smart phones and tablet PCs have been widely used, WLANs which use same frequency with ZigBee networks have been increasingly used. Therefore, radio frequency interference causes many problems. To solve radio frequency interference problem among ZigBee networks and WLANs, many researches focus on designing interference minimization schemes in ZigBee networks. However, existing schemes have problems that have waste of resource for detecting interference, and have unnecessary time to avoid interference. In this paper, we propose an interference minimization scheme to solve radio frequency interference in ZigBee networks. The proposed scheme detects interference using ACK mechanism to reduce waste of resource, and avoids interference using table driven channel hopping scheme which is faster than existed schemes. The performance of proposed interference minimization scheme is evaluated by using OPNET simulator. Through the simulation result, we prove that proposed scheme has faster channel hopping than existing schemes.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.2 s.7
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• pp.81-87
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• 2005

In this paper, a VCDRO(Voltage Control Dielectirc Resonator Oscillator) for signal source of doppler radar system is designed and fabricated. The proposed VCDRO is made with new tuning mechanism using CPW line. The coplanar waveguide of $\lambda_{g}$/2 in length with varactor diode is placed on the metallization side under the dielectric resonator and coupled to it. Tuning varactor diode is mounted at one end of the CPW. The proposed circuit tuned by a CPW allows one more varactor diode to be mounted on the optimized CPW, where a greater sensitivity of frequency tuning is needed. With varying the biasing voltage for the varactor diode from 0 V to 15 V, output frequency tuning of 12 MHz is obtained. The PLDRO exhibits output power of 16.5 dBm with phase noise in the phase locked state characteristic of -115 dBc/Hz at 100 Hz, -105 dBc/Hz at the 10 kHz, and -102 dBc/Hz at 1 Hz offset from 10.525 GHz , respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.5
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• pp.331-341
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• 2005

Distribution of anchovy (Engraulis japonica) eggs and larvae was studied in the southwestern sea of Korea in July and November, 2001. Anchovy eggs were found mainly in the oceanic fronts of the northern sea area which were formed in the offshore area of Chuja Is. Bogil Is. and Chungsan Is. from west to east. Anchovy eggs were also found in the surrounding sea of Cheju Is. in the southern sea front area. The waters were highly heterogeneous and the water masses were bordered based on temperature $(10.8-26.4^{\circ}C)$ and salinity (28.9-33.7 psu). The anchovy eggs were mostly found outside of the China Coastal Water, where salinity was below 31 psu. The anchovy eggs were not found in November. Abundance of the anchovy larvae were higher in July than November. Temperature ranged from $10.8^{\circ}C\;to\;25.9^{\circ}C\;and\;15.9^{\circ}C\;to\;20.5^{\circ}C$, and salinity ranged from 28.9psu to 34.1psu and 33.2psu to 34.1psu in July and November, respectively. Non-swimmable larvae were found throughout the whole area of the southwestern sea of Korea. The area beyond the oceanic front had anchovy eggs dispersed from the spawning grounds to offshore. Dispersion pattern showed that the eggs were transported from the spawning grounds with a process of advection and diffusion based on the flow pattern which were caused by winds. Distribution pattern of the anchovy eggs and larvae may be used for the prediction of oceanic currents in each area.

• Korean Membrane Journal
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• v.7 no.1
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• pp.1-18
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• 2005

The permeate flux decline due to membrane fouling can be addressed using a variety of theoretical stand-points. Judicious selection of an appropriate theory is a key toward successful prediction of the permeate flux. The essential criterion f3r such a decision appears to be a detailed characterization of the feed solution and membrane properties. Modem theories are capable of accurately predicting several properties of colloidal systems that are important in membrane separation processes from fundamental information pertaining to the particle size, charge, and solution ionic strength. Based on such information, it is relatively straight-forward to determine the properties of the concentrated colloidal dispersion in a polarized layer or the cake layer properties. Incorporation of such information in the framework of the standard theories of membrane filtration, namely, the convective diffusion equation coupled with an appropriate permeate transport model, can lead to reasonably accurate prediction of the permeate flux due to colloidal fouling. The schematic of the essential approach has been delineated in Figure 5. The modern approaches based on appropriate cell models appear to predict the permeate flux behavior in crossflow membrane filtration processes quite accurately without invoking novel theoretical descriptions of particle back transport mechanisms or depending on adjust-able parameters. Such agreements have been observed for a wide range of particle size ranging from small proteins like BSA (diameter ${\~}$6 nm) to latex suspensions (diameter ${\~}1\;{\mu}m$). There we, however, several areas that need further exploration. Some of these include: 1) A clear mechanistic description of the cake formation mechanisms that clearly identifies the disorder to order transition point in different colloidal systems. 2) Determining the structure of a cake layer based on the interparticle and hydrodynamic interactions instead of assuming a fixed geometrical structure on the basis of cell models. 3) Performing well controlled experiments where the cake deposition mechanism can be observed for small colloidal particles (< $1\;{\mu}m$). 4) A clear mechanistic description of the critical operating conditions (for instance, critical pressure) which can minimize the propensity of colloidal membrane fluting. 5) Developing theoretical approaches to account for polydisperse systems that can render the models capable of handing realistic feed solutions typically encountered in diverse applications of membrane filtration.

• Archives of Plastic Surgery
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• v.41 no.4
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• pp.325-329
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• 2014

Background Liposuction is a procedure to reduce the volume of subcutaneous fat by physical force. Intracellular storage fat is composed of triglyceride, whereas circulating fat particles exist as cholesterol or triglycerol bound to carrier proteins. It is unavoidable that the storage form of fat particles enters the circulation system after these particles are physiologically destroyed. To date, however, no studies have clarified the fatal characteristics of fat embolism that occurs after the subclinical phase of free fat particles. Methods A mixture of human lipoaspirate and normal saline (1:100, 0.2 mL) was injected into the external jugular vein of rats, weighing 200 g on average. Biopsy specimens of the lung and kidney were examined at 12-hour intervals until postoperative 72 hours. The deposit location and transport of the injected free fat particles were confirmed histologically by an Oil Red O stain. Results Inconsistent with previous reports, free fat particles were transported from the intravascular space to the parenchyma. At 24 hours after infusion, free fat particles deposited in the vascular lumen were confirmed on the Oil Red O stain. At 72 hours after infusion, free fat particles were accumulated compactly within the parenchymal space near the perivascular area. Conclusions Many surgeons are aware of the fatal results and undiscovered pathophysiologic mechanisms of free fat particles. Our results indicate that free fat particles, the storage form of fat that has been degraded through a physiological process, might be removed through a direct transport mechanism and phagocytotic uptake.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.380-383
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• 2006

The media transport system is used in a printer, a ATM(Automated Tellor Machine), and so on. The media transport system has many problems through miniaturization and rapid transportation of these machines. In the paper feeding mechanism, it is important to feed the sheet without jamming under any conditions. To avoid sheet jamming, first we need to predict the behavior of the sheet exactly. In this paper, the analysis of media behavior is based on J. Stolte's studies. In all of OA machines, a flexible beam or plate is pushed from the channel. The motion may be constrained by guides. This leads to a transient and geometrically nonlinear problem. The behavior of paper is simulated by dynamic elastica theory. The shape of guide is represented by parametric cubic curve. But J. Stolte's studies did not considered contact condition between sheet and guide. So Klarbring's Model. will be applied. And the analysis of flexible media has to include aerodynamic effect for more exact behavior analysis, because the flexible media can be deformed drastically by a little force. Therefore aerodynamic force must be applied to the governing equation. Lastly, the simulation of this model is performed, and the experiment is performed for verification of this model. The experimental results of low exit velocity are consistent with the simulation results, however experimental results of high exit velocity do not agree well with analytical results. The reason is that there may be other effects like nip Phenomena

• Plant Journal
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• v.11 no.1
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• pp.50-57
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• 2015

This study presents prediction of maximum fly ash conveying capacity of fly ash system in a power plant. The mixture ratio and pressure drop characteristics of air-fly ash flow in piping system are not well understood due to the complexity of particle motion mechanism. In this paper, the researcher investigated the optimum mixture ratio when the pressure drop of fly ash conveying system is equal to maximum static pressure of displacement fly ash transport blower and the capacity of fly ash transport according to the optimum mixture ratio by experimenting the fly ash conveying system of domestic D coal thermal power plants, which is currently in operation. The experiment results showed that the maximum fly ash conveying capacity of fly ash system were founded under the condition of maximum air volume 5,040 m3/h, static pressure of trip condition 1,163 mmH2O. In addition, it was predicted maximum mixture ratio of the air-fly ash was 8.66 and maximum capacity of fly ash conveying was 52,600 kg/h under these conditions.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.381-388
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• 2008

An X-linked skeletal disorder, SEDT (spondyloepiphyseal dysplasia tarda) is a genetic disease characterized by a disproportionately short trunk and short stature caused by mutations in the SEDL gene. This gene is evolutionarily conserved from yeast to human. The yeast SEDL protein ortholog, Trs20p, has been isolated as a member of a large multi-protein complex called the transport protein particle (TRAPP), which is involved in endoplasmic reticulum (ER)-to-Golgi transport. The interaction between SEDL and partner proteins is important in order to understand the molecular mechanism of SEDL functions. We isolated several SEDL-binding proteins derived from rat cells by an immobilized GST-fusion method. Furthermore, the SEDL-homologue proteins were identified using motif based methods. Common motifs between SEDL-binding proteins and SEDL-homologue proteins were classified into seven types and 78 common motifs were revealed. Sequence similarities were contracted to seven types using phylogenetic trees. In general, types I-III and VI were classified as having the function of acetyl-CoA carboxylase, glycogen phosphorylase, isocitrate dehydrogenase, and enolase, respectively, and type IV was found to be functionally related to the GST protein. Types V and VII were found to contribute to TRAPP vesicle trafficking.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.1 no.1
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• pp.52-57
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• 2002

A simulation tool for an optimal ATIS design and drivers' dynamic route choice behavior analysis is developed, which is applicable to urban networks. Due to the difficulty to make drivers feel the time pressure according to traffic conditions, current SP questionnaire survey type surveys have a limitation to capture correct driver reactions to real-time traffic Information provision. The simulator Is a web-based upgraded version, named WATiSim (Web-based ATIS Simulator), to quickly perform a wide population survey with a minimal cost using INTERNET Furthermore, the time pressure issue is lessened by its interface and simulation modules. After WATiSim mimicked a VMS based ATIS in a partial network of Seoul Metropolitan, reactions of drivers to various traffic conditions were surveyed through INTERNET and analyzed using a logit model. Drivers under the ATIS environment clearly understood the provided traffic information, and their reactions were closely related to traffic conditions, scheduled delay, trip purposes as well as toll charge if any.