• 해양환경안전학회지
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• 제28권1호
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• pp.10-18
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• 2022

선박을 통한 세계교역 증가에 따라 침입외래종(Invasive Alien Species, IAS)로 인한 해양생태계파괴 및 사회경제적 피해가 지속적으로 증가하고 있다. 특히 선체표면과 틈새구역(Niche Area)에 부착된 해양생물의 이동은 외래종침입 문제뿐만 아니라 선박의 마찰저항을 증가시켜 운항효율감소 및 온실가스배출 증가를 유발한다. 국제해사기구(IMO)는 최근 선체부착생물 통제 및 관리에 대한 지침 개정작업에 착수하였고 뉴질랜드와 미국 캘리포니아는 이미 자국법으로 선체부착생물 관리를 규제하고 있다. 본 논문에서는 국내에 입항하는 국제운항선 5척을 대상으로 선체부착생물 관리현황과 생물부착현황을 조사하였고, 생물부착종과 피도(Coverage)를 분석하여 생물부착단계 등급(Level of Fouling, LoF rank)을 평가하였다. 모든 선박에서 대형부착생물(Macrofouling)이 관찰되었고 특히 선수 스러스터(Bow thruster), 빌지킬(Bilge keels) 및 해수 흡입구 격자(Sea-chest gratings)와 같은 틈새구역의 대형개체(Macro organisms) 부착이 심각한 수준으로 나타났다. 본 연구에서는 국내 선체부착생물 관리방안을 제시하고, 실선대상 생물부착단계등급 적용 및 검사(Inspection) 방법 개선방안을 제안하고자 하였다.

• 전기화학회지
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• 제11권2호
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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.

• 대한장애인치과학회지
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• 제10권2호
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• pp.84-88
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• 2014

1. 순측접근법은 치수치료를 순측으로 시행한 후 변색된 순측의 치질을 확대하여 삭제하고 레진으로 순면전체를 수복함으로써 치수치료와 동시에 심미성을 회복할 수 있다. 2. 순측으로 치수치료를 시행하므로 시야가 확보에 유리하고 기구조작이 용이해 행동조절이 잘 되지 않는 어린이에게 추천된다.

• 전기화학회지
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• 제6권2호
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• pp.130-133
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• 2003

3,4-dihydroxybenzoic acid(3,4-DHBA)를 전기화학법으로 유리탄소 전극 위에 중합하여 GC/p-3,4-DHBA형의 전극을 제작한 후 이 전극을 도파민으로 재 수식한 전극을 제작하였다. 이 때 고분자 피막 상에 카르복시기와 도파민의 아민 기간에 짝 짓기 반응은 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride(EDC)의 존재하에서 진행되었다. 이 반응과정에서 반응한 도파민의 양은 수정판 분석기(quartz crystal analyzer:QCA)에 의하여 결정하였으며 그때 전극형태는 QCA(Au)/p-3,4-DHBA-dopamine이었다. 이 전극의 표면은 o-퀴논부분을 갖고 있어서 티탄이온에 선택성이 큰 특성을 갖고 있다. 이 전극의 산화환원과정은 $hydroquinone = quinone +2H^+2e^-$으로 두 개의 강한 파와 두개의 약한 파가 CV과정에서 관찰되었다. 이 수식전극으로 Ti(IV)이온을 $4.13\times10^{-5} gcm^{-2}$만큼 포집할 수가 있었다. 이 수식 전극으로 $5.25\times10^{-4}M$에서 $5.25\times10^{-8}M$농도범위까지 정량 할 수 있는 상관계수가 0.997인 검정선을 얻었다.

• Journal of Mechanical Science and Technology
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• 제18권8호
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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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• 제41권5호
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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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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• 제13권12호
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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.

• 대한기계학회논문집B
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• 제41권8호
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• pp.521-529
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• 2017

본 연구에서는 항공기 추진용 가스터빈 엔진의 고증속 터빈 제1단 정익 익렬을 새로이 구축하고, 이 정익의 기본 유동 특성에 대하여 연구하였다. 그 결과 본 연구에서 도입된 정익의 압력면에는 강한 순압력구배가 존재하는 반면, 흡입면에는 앞전에서 미드코드 근처까지 압력면보다 훨씬 더 심한 순압력구배가 존재하고 그 이후 역압력구배가 존재하였다. 두 종류의 유막법을 적용한 유동의 가시화 실험을 통하여, 정익 앞전 상류 영역에 4와류모델 말발굽와류 시스템이 존재함을 확인하였고, 입구 경계층 유동의 박리선과 재부착 유동의 박리선을 정확히 파악하였다. 이와 함께 이 고증속 정익 익렬 하류에서의 2차유동, 압력손실, 선회각, 등에 대한 데이터를 확보하였다.

• Korean Journal of Chemical Engineering
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• 제35권11호
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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.