• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.10-18
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• 2022

With the increase in world trade through ships, the destruction of the marine ecosystem and socioeconomic damage due to invasive alien species (IAS) are continuously increasing. In particular, marine organisms attached on the hull surface and niche area increase the friction resistance of ships as well as the invasion of non-indigenous species, and causes a decrease in operational efficiency and an increase in GHG (Green House Gas) emissions. The International Maritime Organization (IMO) has recently begun revising guidelines for the control and management of ship's biofouling, and New Zealand and California in the United States are already regulating biofouling management under their own laws. This study investigated the management status of the submerged surface of ships and marine organisms attachments on five international ships entering South Korea, and analyzed species group and coverage (%) of biofouling communities to evaluate the LoF (Level of Fouling) rank. Macroflouling was observed on all ships surveyed, and specially, the adhesion of macro organisms in niche areas such as bow thruster, bilge keels and sea-chest gratings appeared to be at a serious level. This study proposed the management direction our country should take with regard to ship's biofouling and the improvement measures for evaluation of LoF rank and inspection methods of hull and niche ares.

• Journal of the Korean Electrochemical Society
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• v.11 no.2
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• pp.100-104
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• 2008

Titanium sheet metal substrates used in thin film batteries were wet etched and their surface area was increased in order to increase the discharge capacity and power density of the batteries. To obtain a homogeneous etching pattern, we used a conventional photolithographic process. Homogeneous hemisphere-shaped wells with a diameter of approximately $40\;{\mu}m$ were formed on the surface of the Ti substrate using a photo-etching process with a $20\;{\mu}m{\times}20\;{\mu}m$ square patterned photo mask. All-solid-state thin film cells composed of a Li/Lithium phosphorous oxynitride (Lipon)/$LiCoO_2$ system were fabricated onto the wet etched substrate using a physical vapor deposition method and their performances were compared with those of the cells on a bare substrate. It was found that the discharge capacity of the cells fabricated on wet etched Ti substrate increased by ca. 25% compared to that of the cell fabricated on bare one. High discharge rate was also able to be obtained through the reduction in the internal resistance. However, the cells fabricated on the wet etched substrate exhibited a higher degradation rate with charge-discharge cycling due to the nonuniform step coverage of the thin films, while the cells on the bare substrate demonstrated a good cycling performance.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.10 no.2
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• pp.84-88
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• 2014

Traditional method of pulpectomy for a necrotic primary anterior tooth was done on lingual side. But it could not recover the discoloration of crown effectively. For the purpose of treating the discoloration of crown after lingual pulpectomy, additional methods of crown restoration were needed like : celluloid crown, open-faced crown, rasin-faced crown. Neverthless, these kinds of complete coverage methods had some disadvantages such as possibility of tooth fracture by increased tooth preparation. In order to overcome the shortcomings of lingual pulpectomy, labial treatment could be considered as an alternative. It is a method that treats necrotic pulp through the labial access opening. After finishing the pulp treatment, discolored labial tooth structure was removed extending from access opening. Discoloration of deep area could be masked effectively using opaque sealant. Cavity on labial side was restored with composite resin. This labial approach method has several advantages. First, it gives a direct vision for effective pulp treatment which is also very useful for children with poor behavior. Second, most of lingual tooth structure could be saved and occlusal contact of lingual surface remains undisrupted. Only nonfunctional discolored labial surface may removed. Third, complete removal of discolored part of a labial tooth and immediate resin restoration could be done effectively after pulp treatment. Moreover, it also could be used for pulp treatment having serious dental caries on labial surface with sound lingual tooth structure. This report presents cases with discolored upper anteior primary tooth, approaching labial side with successful restoration.

• Journal of the Korean Electrochemical Society
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• v.6 no.2
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• pp.130-133
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• 2003

3,4-dihydroxybenzoic acid(3,4-DHBA) was electropolymerized on glassy carbon electrode to give the GC/p-3,4-DHBA type electrode which was modified with dopamine by the help of 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride(EDC) acting as a coupling agent. The carboxylic sites on the polymeric surface of p-3,4-DHBA and mine group at the dopamine gave a QCA(Au)/p-3,4-DHBA-dopamine type of modified electrodes. The o-quinone moieties at the electrode surface exhibited high selectivity to titanium ions in solution. The redox process of the electrode is hydroquinone : quinone +$2H^+2e^-$, which had two strong and two weak pairs of peaks at CV. The modified electrode can deposit Ti(IV) ions as much as $4.13\times10^{-5}gcm^{-2}$. The calibration curve of the electrodes, log of the surface coverage-normalized redox response vs log[Ti], exhibited an excellent correlation$(r{\geq}0.997)$ for titanium concentrations ranging from $5.25\times10^{-4}\;to\;5.25\tiems10^{-8}M.$.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1435-1450
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• 2004

Experimental data are presented which describe the effects of a combustor-level high free-stream turbulence on the near-wall flow structure and heat/mass transfer on the endwall of a linear high-turning turbine rotor cascade. The end wall flow structure is visualized by employing the partial- and total-coverage oil-film technique, and heat/mass transfer rate is measured by the naphthalene sublimation method. A turbulence generator is designed to provide a highly-turbulent flow which has free-stream turbulence intensity and integral length scale of 14.7% and 80mm, respectively, at the cascade entrance. The surface flow visualizations show that the high free-stream turbulence has little effect on the attachment line, but alters the separation line noticeably. Under high free-stream turbulence, the incoming near-wall flow upstream of the adjacent separation lines collides more obliquely with the suction surface. A weaker lift-up force arising from this more oblique collision results in the narrower suction-side corner vortex area in the high turbulence case. The high free-stream turbulence enhances the heat/mass transfer in the central area of the turbine passage, but only a slight augmentation is found in the end wall regions adjacent to the leading and trailing edges. Therefore, the high free-stream turbulence makes the end wall heat load more uniform. It is also observed that the heat/mass transfers along the locus of the pressure-side leg of the leading-edge horseshoe vortex and along the suction-side corner are influenced most strongly by the high free-stream turbulence. In this study, the end wall surface is classified into seven different regions based on the local heat/mass transfer distribution, and the effects of the high free-stream turbulence on the local heat/mass transfer in each region are discussed in detail.

• Journal of Periodontal and Implant Science
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• v.41 no.5
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• pp.253-258
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• 2011

Purpose: Immediate implantation presents challenges regarding site healing, osseointegration, and obtaining complete soft-tissue coverage of the extraction socket, especially in the posterior area. This last issue is addressed herein using the double-membrane (collagen membrane+high-density polytetrafluoroethylene [dPTFE] membrane) technique in two clinical cases of posterior immediate implant placement. Methods: An implant was placed immediately after atraumatically extracting the maxillary posterior tooth. The gap between the coronal portion of the fixture and the adjacent bony walls was filled with allograft material. In addition, a collagen membrane (lower) and dPTFE membrane (upper) were placed in a layer-by-layer manner to enable the closure of the extraction socket without a primary flap closure, thus facilitating the preservation of keratinized mucosa. The upper dPTFE membrane was left exposed for 4 weeks, after which the membrane was gently removed using forceps without flap elevation. Results: There was considerable plaque deposition on the outer surface of the dPTFE membrane but not on the inner surface. Moreover, scanning electron microscopy of the removed membrane revealed only a small amount of bacteria on the inner surface of the membrane. The peri-implant tissue was favorable both clinically and radiographically after a conventional dental-implant healing period. Conclusions: Secondary closure of the extraction socket and immediate guided bone regeneration using the double-membrane technique may produce a good clinical outcome after immediate placement of a dental implant in the posterior area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.109-110
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• 2008

We have performed a density functional theory study to investigate the reaction of the $HfCl_4$ molecule on $H_2O$ terminated Si (001)-$(2\times1)$ surface. The reaction of the $HfCl_4$ molecule is more favorable on OH-terminated site than H-terminated site. The first $HfCl_4$ molecule is adsorbed on a OH-terminated site with 0.21 eV energy benefit. The second $HfCl_4$ molecule is adsorbed on the most adjacent OH-terminated site of the first molecule and the energy benefit is 0.28 eV. The third and forth molecules have same tendency with the first and second ones. The adsorption energies of the fifth and sixth $HfCl_4$ molecules are 0.01 eV, -0.06 eV respectively. Therefore, we find that the saturation Hf coverage is approximately 5/8 of the available hydroxyl site, which is $2.08\times10^{14}/cm^2$. Our model is well matched with an experimental study by reference.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.12
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• pp.6133-6137
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• 2012

Purpose: To study the effect of bolus versus no bolus in the coverage of the nodal tumour volume with intensity-modulated radiotherapy (IMRT) for the treatment of nasopharyngeal carcinoma (NPC). Methods and Materials: This retrospective study used data from 5 consecutive patients with NPC who were treated with bolus for large neck nodes using IMRT from November 2011-January 2012 in our institute. All these patients were treated radically with IMRT according to our institution's protocol. Re-planning with IMRT without bolus for these patients with exactly the same target volumes were done for comparison. Comparison of the plans was done by comparing the V70 of PTV70-N, V66.5 of PTV70-N, V65.1 of PTV70-N and the surface dose of the PTV70-N. Results: The mean size of the largest diameter of the enlarged lymph nodes for the 5 patients was 3.9 cm. The mean distance of the GTV-N to the skin surface was 0.6 cm. The mean V70 of PTV70-N for the 5 patients showed an absolute advantage of 10.8% (92.4% vs. 81.6%) for the plan with bolus while the V66.5 of PTV70-N had an advantage of 8.1% (97.0% vs. 88.9%). The mean V65.1 also had an advantage of 7.1% (97.6% vs. 90.5%). The mean surface dose for the PTV70-N was also much higher at 61.1 Gy for the plans with bolus compared to only 23.5 Gy for the plans without bolus. Conclusion: Neck node bolus technique should be strongly considered in the treatment of NPC with enlarged lymph nodes treated with IMRT. It yields a superior dosimetry compared t o non-bolus plans with acceptable skin toxicity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.8
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• pp.521-529
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• 2017

Three-dimensional flow characteristics within a high-acceleration first-stage turbine vane passage has been investigated in a newly-built vane cascade for propulsion. The result shows that there is a strong favorable pressure gradient on the vane pressure surface. On its suction surface, however, there exists not only a much stronger favorable pressure gradient than that on the pressure surface upstream of the mid-chord but also a subsequent adverse pressure gradient downstream of it. By employing two different oil-film methods with upstream coating and full-coverage coating, a four-vortex model horseshoe vortex system can be identified ahead of each leading edge in the cascade, and the separation line of inlet boundary layer flow as well as the separation line of re-attached flow is provided as well. In addition, basic flow data such as secondary flow, aerodynamic loss, and flow turning angle downstream of the cascade are obtained.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2220-2231
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• 2018

Lipase from Candida rugosa was immobilized on $MgO{\cdot}SiO_2$ hybrid grafted with amine, thiol, cyano, phenyl, epoxy and carbonyl groups. The products were analyzed using Fourier transform infrared spectroscopy, nuclear magnetic resonance, low-temperature $N_2$ sorption and elemental analysis. Additionally, the degree of coverage of the oxide material surface with different functional groups and the number of surface functional groups were estimated. The Bradford method was used to determine the quantity of immobilized enzyme. The largest quantity of enzyme (25-28 mg/g) was immobilized on the hybrid functionalized with amine and carbonyl groups. On the basis of hydrolysis reaction of p-nitrophenyl palmitate to p-nitrophenol, it was determined how the catalytic activity of the obtained biocatalysts is affected by pH, temperature, storage time, and repeated reaction cycles. The best results for catalytic activity were obtained for the lipase immobilized on $MgO{\cdot}SiO_2$ hybrids with amine and carbonyl groups. The biocatalytic system demonstrated activity above 40% in the pH range 4-10 and in the temperature range $30-70^{\circ}C$. Lipase immobilized on the $MgO{\cdot}SiO_2$ systems with amine and epoxy groups retains, respectively, around 80% and 60% of its initial activity after 30 days of storage, and approximately 60-70% after 10 reaction cycles.