• Bulletin of the Korean Chemical Society
• /
• v.32 no.7
• /
• pp.2377-2384
• /
• 2011

Azo-acenaphthylene oligomers with repeating acenaphthylene units "n" up to 4, 5, 7, 17 and 19 have been prepared successfully using nitroxide mediated Stable Free Radical Polymerization (SFRP). Azo-acenaphthylene oligomers, reversibly end-capped by the stable nitroxide 2,2,6,6-tetramethyl-1-piperidinoxyl (TEMPO), were further reacted via radical addition to 4-(naphthalenemethoxy)styrene monomer for diblock co-polymer formation. Characterization of the oligomers and diblock co-polymers was accomplished using MALDI-MS supported by GPC (Gel Permeation Chromatography) and $^1H$ NMR spectrometry. MALDI-MS afforded definitive results by providing an inter-peak interval of 152 (m/z), corresponding to acenaphthylene monomer, and inter-peak interval of 260 (m/z) for the naphthalenemethoxystyrene monomer unit in block copolymers. Our study opens the way to control the number of repeat units in the oligomers. Further these oligomers can be tailored with various monomers for the formation of block copolymers.

• The Korean Journal of Pain
• /
• v.9 no.1
• /
• pp.215-218
• /
• 1996

Frostbite involves freezing of tissues and usually affects the distal aspects of the extremities or exposed parts of the face. such as the ears, nose, chin, and cheeks. It produces tissue injury by ice crystal formation between the cells, cellular dehydration, and microvascular occulsion. There are four degrees of frostbite. First degree is accompanied by erythema and edema; second degree, by vesiculation, blistering, and eschar formation; third degree, by hemorrhagic blistering and bluish gray discoloration; and fourth degree, by injury to subcutaneous tissue, muscle, tendon, and bone leading to mottled, dry, black, and necrotic changes. We successfully treated 2 patients suffering from frostbite by performing sympathetic ganglion block with pure alcohol. We concluded sympathetic ganglion block is one of the most effective treatments for frostbite.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.24-25
• /
• 2011

Molecular self-assembly has several advantages over other nanofabrication methods. Molecular building blocks ensure ultrafine pattern precision, parallel structure formation allows for mass production and a variety of three-dimensional structures are available for fabricating complex structures. Nevertheless, the molecular interaction for self-assembly generally relies on weak forces such as van der Waals force, hydrogen bonding, or hydrophobic interaction. Due to the weak interaction, the structure formation is usually slow and the degree of ordering is low in a self-assembled structure. To promote self-assembly, directed assembly methods employing prepatterned substrates or external fields have been developed and gathered a great deal of technological attention as a next generation nanofabrication process. In this presentation a variety of directed assembly methods for soft nanomaterials including block copolymers, peptides and carbon nanomaterials will be introduced. Block copolymers are representative self-assembling materials extensively utilized in nanofabrication. In contrast to colloid assembly or anodized metal oxides, various shapes of nanostructures, including lines or interconnected networks, can be generated with a precise tunability over their shape and size. Applying prepatterned substrates$^{1,2}$ or introducing thickness modulation$^3$ to block copolymer thin films allowed for the control over the orientational and positional orderings of self-assembled structures. The nanofabrication processes for metals, semiconductors$^4$, carbon nanotubes$^{5,6}$, and graphene$^{6,7}$ templating block copolymer self-assembly will be presented.

• Journal of architectural history
• /
• v.30 no.5
• /
• pp.29-42
• /
• 2021

The Don-am district is a residential area that was supplied in 1936 as a land readjustment project(Tojiguhoekjeongri). The Don-am district was newly supplied with residential areas and urban hanoks were built in large numbers. The Don-am district was influenced by urban planning and legislation at that time. These affected in the layout and plan of urban hanok. Residential block in the Don-am district were developed sequentially from the late 1930s to the 1960s. Residential block were divided by modern construction company and sold by individual lots. The blocks supplied to the Don-am district made uniformly the corner out-off(Ga gak) for creating a vehicle-centered road. So urban hanoks located in the corner plot was transformed in response to the road. Residential blocks in Don-am district was divided into three to four rows. Therefore, alleys were created inside the block. Newly made alleys consist of a privately owned road(Sa-do), a public road(Gong-Do), and open space in the site. And the alleys were used as an entry space for sharing with neighboring. Urban hanoks of Don-am district have had changed and adapted to the formation of these alleys.

• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.190-192
• /
• 2004

In this paper, we propose a low bit-rate embedded video compression scheme with 3-D block partition coding in the wavelet domain. The proposed video compression scheme includes multi-level 3-dimensional dyadic wavelet decomposition, raster scanning within each subband, formation of block, 3-D partitioning of block, and adaptive arithmetic entropy coding. Although the proposed video compression scheme is quit simple, it produces bit-stream with good features, including SNR scalability from the embedded nature. Experimental results demonstrate that the proposed video compression scheme is quit competitive to other good wavelet-based video coders in the literature.

• The Korean Journal of Pain
• /
• v.10 no.2
• /
• pp.241-245
• /
• 1997

Persistent hiccup is defined as duration lasting longer than 48 hours. Reflex arc of hiccup is divided into three parts : afferent, central, efferent. Afferent portion of the neural pathway of hiccup formation is composed of vagus nerve, phrenic nerve, and sympathetic chain arising from T6 to T12. Efferent limb is phrenic nerve. Hiccup center is located in brain stem, midbrain, reticular system and hypothalamus. Persistent hiccup is very difficult to treat by conventional methods. We performed cervical epidural block of the phrenic nerve root for three patients suffering from persistent hiccup. The therapeutic effect was perfect. The mechanism of the cervical epidural block is not yet defined however it is thought to block the efferent nerve fibers and suppress the reflex arc of hiccup. We conclude cervical epidural block is relatively safe and very effective for treating persistent hiccup.

• Journal of the Korean Ceramic Society
• /
• v.54 no.6
• /
• pp.525-529
• /
• 2017

To improve the thermal resistance of a porous borosilicate lining block, we prepared and applied polysiloxane-fumed silica-ethanol slurry on top of the block and fired the coating layer using a torch for 5 minutes at $800^{\circ}C$. We conducted magnified characterizations using a microscope and XRD analysis to observe phase transformations, and TGA-DTA analysis to determine the thermal resistance. Thermal characterizations showed improved heat resistance with relatively high polysiloxane content slurry. Cross-sectional optical microscope observation showed less melting near the surface and decreased pore formation area with higher polysiloxane content slurry. XRD analysis revealed that the block and coating layer were amorphous phases. TGA-DTA analysis showed an endothermic reaction at around $550^{\circ}C$ as the polysiloxane in the coating layer reacted to form SiOC. Therefore, coating polysiloxane on a borosilicate block contributes to preventing the melting of the block at temperatures above $800^{\circ}C$.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.31 no.3
• /
• pp.207-215
• /
• 2009

Purpose: The aim of the present study is to evaluate the long term bone healing after horizontal ridge augmentation using auto block bone graft for implant installation timing. Materials and Methods: Five Beagle dogs(which were 14 months old and weighted approximately 10kg). In surgery 1(extraction & bone defect), premolars(P2, P3,P4) were extracted and the buccal bone plate was removed to create a horizontally defected ridge. After three months healing, in surgery 2(ridge augmentation). Auto block bone grafts from the mandibular ramus were used in filling the bone defects were fixed with stabilizing screws. The following fluorochrome labels were given intravenously to the beagle dogs: oxytetracycline 1week after the surgery, alizarin red 4 weeks after the surgery, calcein blue 8 weeks after the surgery. The tissue samples were obtained from the sacrificed dogs of 1, 4, 8, 12, 16 weeks after the surgery. Non-decalcified sections were prepared by resin embedding and microsection to find thickness of $10{\mu}m$ for the histologic examination and analysis. Results: 1. We could achieve the successful reconstruction of the horizontal bone defect by auto block bone graft. The grafted bone block remained stable morohologically after 16 weeks of the surgery. 2. In the histologic view. We observed osteoid tissue from the sample $4^{th}$ week sample and active capillary reconstruction in the grafted bone from the $12^{th}$ week sample. Healing procedures of auto bone grafts were compared to that of the host bone. 3. Bone mineralization could be detected from the $8^{th}$ week sample. 4. Fluorochrome labeling showed active bony changes and formation at the interface of the host bone and the block graft mainly. Bony activation in the grafted bone could be seen from the $4^{th}$ week samples. Conclusions: Active bone formation and remodeling between the grafted bone and host bone can be seen through the revascularization. After the perfect adhesion to host bone, Timing of successful implant installation can be detected through the ideal ridge formation by horizontal ridge augmentation.

• Journal of the Korean Chemical Society
• /
• v.24 no.3
• /
• pp.259-265
• /
• 1980

Poly (styrene-b-methyl methacrylate) (PS-b-PMMA) was synthesized by free radical telomerization: the telomerization of styrene with $CCI_4$ by using AIBN as initiator followed by a second telomerization of methyl methacrylate using $CCI_3$ end group of the resulting polymer as the macrotelogen, with AIBN initiation, gave the styrene-methyl methacrylate block copolymer. The effects of the concentration of the macrotelogen, the concentration of monomer, the molecular weight of the macrotelogen, the reaction temperature and the concentration of the solvent on the formation of the block copolymer were investigated. Block copolymers containing up to 10 weight percent PMMA were obtained by adjusting the reaction conditions.

• Macromolecular Research
• /
• v.12 no.1
• /
• pp.127-133
• /
• 2004

We have studied the surface micelle formation of polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) at the air-water interface. A series of four PS-b-P2VPs were synthesized by anionic polymerization, keeping the PS block length constant (28 kg/㏖) and varying the P2VP block length (1, 11, 28, or 59 kg/㏖). The surface pressure-area ($\pi$-A) isotherms were measured and the surface morphology was studied by atomic force microscopy (AFM) after Langmuir-Blodgett film deposition onto silicon wafers. At low surface pressure, the hydrophobic PS blocks aggregate to form pancake-like micelle cores and the hydrophilic P2VP block chains spread on the water surface to form a corona-like monolayer. The surface area occupied by a block copolymer is proportional to the molecular weight of the P2VP block and identical to the surface area occupied by a homo-P2VP. It indicates that the entire surface is covered by the P2VP monolayer and the PS micelle cores lie on the P2VP monolayer. As the surface pressure is increased, the $\pi$-A isotherm shows a transition region where the surface pressure does not change much with the film compression. In this transition region, which displays high compressibility, the P2VP blocks restructure from the monolayer and spread at the air-water interface. After the transition, the Langmuir film becomes much less compressible. In this high-surface-pressure regime, the PS cores cover practically the entire surface area, as observed by AFM and the limiting area of the film. All the diblock copolymers formed circular micelles, except for the block copolymer having a very short P2VP block (1 kg/㏖), which formed large, non-uniform PS aggregates. By mixing with the block copolymer having a longer P2VP block (11 kg/㏖), we observed rod-shaped micelles, which indicates that the morphology of the surfaces micelles can be controlled by adjusting the average composition of block copolymers.