• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.243.1-243.1
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• 2016

Recently, many groups have attempted to fabricate 3-dimensional (3D) structures of GaN such as pyramids, rods, stripes and annulars. Since quantum structures on non-polar and semi-polar planes of 3D structures have less influence of internal electric filed, multi quantum wells (MQWs) formed on those planes have high quantum efficiency. Especially, pyramidal and annular structures consist of various crystal planes with different emission wavelength, providing a possibillity of phosphor-free white light emtting diodes (WLEDs).[1] However, it still has problem to obtain high color rendering index (CRI) number because of narrow-band emission and poor indium composition caused by the formation of few number of facets during metal-organic chemical vapor deposition growth.[2] If we can fabricate 3D structure having more various facets, we can make broad-band emittied WLEDs and improve CRI number. In this study, we suggest a simple method to fabricate 3D structures having various facet and containing high indium composition by means of a combination of metal-organic chemical vapor deposition and wet chemical etching techniques.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.166-169
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• 2001

22,000 Ton hydraulic press was developed using wire winding method. The hydraulic press consists of three piece of frame type. The outer layers of yoke-column frame and main cylinder linear were wound with piano wire(1mm${\times}$4mm) under controlled tension and the total length of wound wire was about 450Km. The developed hydraulic press is used for the forming of heat plate with ultra-large size. To obtain large force with relative small apparatus, high pressure of $1,500 Kgf/cm^2$ was supplied to main cylinder through pressure amplification by booster pump. Therefore sealing technique of main cylinder is so crucial that the seals were made of mitre ring type with super-elastic metal. The press total weight is about 150 tons, which is quite light and compact relative to that of conventional hydraulic press.

• Korean Journal of Veterinary Research
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• v.48 no.1
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• pp.93-98
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• 2008

A 6-year-old female Boston terrier dog was presented with seizure episode, forelimb paraparesis, excessive panting, and ataxia. On physical and neurological examination, episcleral vessel engorgement, delayed postural reaction, delayed pupillary light reflex (both direct and consensual), and crossed forelimb were noted. Serum biochemical profiles were not remarkable other than mildly elevated hepatic enzymes. On cerebrospinal fluid analysis, elevated protein concentration was observed. In magnetic resonance imaging scans, the left frontal brain lesion with ring enhancement strongly suggested the presence of intracranial tumor. Concurrently, secondary hydrocephalus and syringomyelia were also observed. The dog was euthanized at 4 months after initial presentation because of aggravated neurological signs. This case was definitely diagnosed as an intracranial anaplastic oligodendroglioma based on postmortem histopathologic examination.

• Journal of the Korean Wood Science and Technology
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• v.9 no.1
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• pp.1-12
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• 1981

The structure of spiral thickenings, particulary the appearance, arrangement and orientation of thickenings in compression wood of Torreya nucifera, were studied in detail by light and polarizing microscope, scanning and transmission electron microscope. The results obtained are as follows: (1) Using the inclined sections at an angle of 45 degrees to the fiber axis, it seems that we can not only observe the more accurate transverse view of the thickenings but also investigate the formation of their thickenings. (2) Generally 2-4 pieces of thickenings are projected to the cell lumen as nipple-like appearance in transverse section and are as frequent, well developed, forming pair and have the rope-like appearance in radial surface. (3) The secondary wall of early wood is composed of 3 layers (S1, S2, S3) and orientation of thickening appears S helix but that of late wood is of 2 layers (S1, S2) and that orientation shows Z helix. Above two regions are demaracted at several tracheid cells from the growth ring boundary. (4) Orientation of thickening seems to be a element showing the characteristics of compression wood in Torreya nucifera. (5) It believes that the thickenings of compression wood are integral part of the S3 in early wood tracheids and of the S2 in late wood and have the same orientations as the inner-most microfibrils in these layers. (6) Thickening and cavities seem to be not formed together in a secondary cell wall of same tracheids.

• Archives of Pharmacal Research
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• v.20 no.4
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• pp.324-329
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• 1997

AB-type amphiphilic copolymers (abbreviated as LE) composed of poly (L-leucine) (PLL) as the A component and poly (ethylene oxide) (PEO) as the B component were synthesized by the ring-opening polymerization of L-leucine N-carboxy-anhydride initiated by methoxy polyoxyethylene amine $(Me-PEO-NH_2)$ and characterized. Core-shell type nanoparticles were prepared by the diafiltration method. Particle size distribution obtained by dynamic light scattering was dependent on PLL composition and the size for LE-1, LE-2 and LE-3 was $369.6{\pm}267$, $523.4{\pm}410$ and $561.2{\pm}364 nm$, respectively. Shapes of the nanoparticies observed by transmission electron microscope (TEM) were almostly spherical. The critical micelle concentration (CMC) of the nanoparticles determined by a fluorescence probe technique was dependent on the composition of hydrophobic PLL, and the CMC for LE-1, LE-2 and LE-3 was $2.0{\times}10^{-6},1.7{\times}10^{-6}$ and $1.5{\times}10^{-6}(mol/l) $, respectively. Clonazepam release from core-shell type nanoparticles in vitro was dependent on PLL composition and drug loading content.

• Macromolecular Research
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• v.15 no.4
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• pp.330-336
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• 2007

Luminescent CdSe/ZnS QDs, with emission in the red region of the spectrum, were synthesized and encapsulated in poly(ethylene glycol)-poly(D,L-lactide) diblock copolymer micelles, to prepare water-soluble, bio-compatible QD micelles. PEG-PLA diblock copolymers were synthesized by ring opening polymerization of D,L-lactide, in the presence of methoxy PEG as a macro initiator. QDs were encapsulated with PEG-PLA polymers using a solid dispersion method in chloroform. The resultant polymer micelles, with encapsulated QDs, were characterized using various analytical techniques, such as UV- Vis measurement, light scattering, fluorescence spectroscopy, transmission electron microscopy (TEM) and atomic forced microscopy (AFM). The polymer micelles, with encapsulated QDs, were spherical and showed diameters in the range of 20-150 nm. The encapsulated QDs were highly luminescent, and have high potential for applications in biomedical imaging and detection.

• Journal of Plant Biology
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• v.31 no.3
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• pp.169-185
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• 1988

Vessel elements in lateral root, tap root, transition region, stem and mid vein of 1-year old, 3-year old and 5-year old ginseng (Panax ginseng C.A. Meyer) are studied with light microscope to clarify the distribution and differentiation of several kinds of vessel elements. Vessel elements are classified into five types such as ring vessel, spiral vessel, scalariform vessel, reticulate vessel and pitted vessel according to the secondary thickenings of cell wall. All of the five types are not observed in each organ, but diverse kinds of vessels are present in stem and mid vein compared with the underground organs such as tap root and lateral root. The length of vessel elements is longest (680$\mu$m) in stem and shortest (143$\mu$m) in tap root. The diameter of vessel elements is 19.0$\mu$m in tap root and the angle of perforation plate comes under 22$^{\circ}$-60$^{\circ}$. The degree of differentiation of vessel elements according to the length, diameter and angle of perforation plate of vessel elements is highest in tap root regardless of the age of ginseng. Three types of perforation plate such as scalariform, intermediate type of simple and scalariform, and simple perforation plate are observed. The vascular tracheids are characteristically observed in mid vein of 1-year old ginseng, and in transition region of 3 and 5-year old ginseng.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2187-2192
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• 2011

Hydrogen peroxide plays a key role as a second messenger in the normal cellular signaling but its overproduction has been implicated in various life-threatening diseases. Peroxalate chemiluminescence is the light emission from a three component reaction between peroxalate, hydrogen peroxide and fluorophores. It has proven great potential as a methodology to detect hydrogen peroxide in physiological environments because of its excellent sensitivity and specificity to hydrogen peroxide. We developed chemiluminescent micelles composed of amphiphilic polymers, peroxalate and fluorescent dyes to detect hydrogen peroxide at physiological concentrations. In this work, we studied the relationship between the chemiluminescence reactivity and stability of peroxalate by varying the substitutes on the aryl rings of peroxalate. Alkyl substitutes on the aryl ring of peroxalate increased the stability against water hydrolysis, but diminished the reactivity to hydrogen peroxide. Chemiluminescent micelles encapsulating diphenyl peroxalate showed significantly higher chemiluminescence intensity than the counterpart encapsulating dimethylphenyl or dipropylphenyl peroxalate. Diphenyl peroxalate-encapsulated micelles could detect hydrogen peroxide generated from macrophage cells stimulated by lipopolysaccharide (LPS) and image hydrogen peroxide generated during LPS-induced inflammatory responses in a mouse.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1697-1698
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• 2008

PLS(Pohang Light Source) is 2.5 Gev synchrotron radiation source in Pohang, Korea, which is under operation since 1995. The hardware and software of the old BPM(Beam Position Monitor) data acquisition system for the PLS storage ring was completely upgraded to increase its performance and stability. The new BPM data acquisition system is based on VME-based EPICS (Experimental Physics and Instrument Control System) IOC system. We used 16-bit resolution analog-to-digital conversion board to digitize analog BPM signals. We developed a data average software to average raw BPM data using reflective memory board. We also developed device drivers for VME I/O boards used, IOC database for PV's(Process Variables). The new BPM data acquisition system is currently running for routine operation with good performance and stability. In this paper, we present the hardware and software of the new BPM data acquisition system DTL water skid cooling system and Resonant Control Cooling.

• Journal of the Korean Geosynthetics Society
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• v.13 no.3
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• pp.31-38
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• 2014

The geogrid encased stone column (GESC) system, which increases the confinement effect, has been developed to improve the load carrying capacity of stone columns. The resonable design method for calculating the geogrid ring tension force and ultimate bearing capacity that can be applied to the design of GESC is proposed. In order to calculate design procedure for GESC, two ultimate bearing capacities were compared. One is the ultimate bearing capacity measured using data of the field loading test in light railway site and the other is the ultimate bearing capacity using suggested design procedure of GESC. The results indicated that design method of GESC higher ultimate bearing capacities compared with field loading test.