• 대한치과보철학회지
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• 제58권3호
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• pp.257-267
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• 2020

흡착식 의치의 목표는 의치상과 하부 조직 사이의 음압 형성과 점막에 의한 의치 주변의 봉쇄에 의해서 의치의 유지를 강화하는 것이다. 본 환자는 잔존치 발거에 따라 완전무치악 상태로 전환하게 된 환자로, 잔존치조제의 흡수와 설하주름부의 부족으로 의치의 안정과 유지가 부족할 것으로 판단되어 하악 흡착식 의치 수복으로 보철계획을 수립하였다. 하악 안정위에서의 예비인상, Centric Tray^® (Ivoclar Vivadent AG, Schaan, Liechtenstein)를 이용한 잠정적 수직고경 결정, Gnathometer M^® (Ivoclar Vivadent AG, Schaan, Liechtenstein)이 부착된 개인트레이를 이용한 폐구정밀인상 및 악간관계 채득, 기능시 의치의 안정을 고려한 인공치 배열, 기능 및 심미를 고려한 연마면 형성, 중합수축을 최소화하여 의치상 내면적합도를 보전하는 의치상 중합 등의 임상 및 기공과정을 통해 기능 및 심미 전반에 걸쳐 만족스러운 하악 흡착식 의치로 수복하였기에 본 증례를 보고하고자 한다.

• 한국식품저장유통학회지
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• 제30권3호
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• pp.472-482
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• 2023

본 연구는 쌀의 세척 및 취반 방법에 따른 isoprothiolane 잔류량을 GC-µECD를 이용하여 분석하였다. 세척 전 현미 잔류량은 17.03 mg/kg이었으며, 도정 후 백미는 1.67 mg/kg이었다. 세척 방법에서 물의 비율과 세척 횟수에 따라 현미와 백미의 isoprothiolane 잔류량은 19.3-59.3 및 43.1-66.5%이었으며, 세척물 온도가 5-40℃ 증가할수록 현미는 56.6-63.1%, 백미는 67.1-74.9% 감소하였다. 세척 방법을 손으로 살살 휘젓거나 비비는 방법으로(A, B 및 C)로 달리하였을 때 현미의 농약 감소율은 63.1-71.6%, 백미는 75.4-87.4%이었다. 현미를 압력밥솥과 전기밥솥을 이용하여 즉시 취반하였을 때 농약은 78.4 및 78.5%, 백미의 경우 94.0 및 94.0%로 감소하였으며, 30분간 불린 후 취반하였을 때 잔류농약은 현미에서 83.4%, 백미는 95.8% 감소하였다. 따라서 현미와 백미의 잔류농약 감소를 위한 가장 효과적인 세척 및 취반 방법은 40℃ 물, 7배 물로 6회 (2, 3회 차는 손으로 비벼서 세척) 세척 후 30분간 물에 불리기이다. 밥솥의 종류에 관계없이 취반할 경우 현미는 평균 83.4%, 백미는 95.8% isoprothiolane이 효과적으로 제거되는 것을 확인하였다.

• 한국안전학회지
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• 제22권4호
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• pp.57-65
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• 2007

Effects on the stiffness of the embankment and sandmat on the construction safety of road embankment was investigated in this study by the numerical experiments using FEM. Two points was mainly focused in this study especially. First the deformation characteristics by the change of the stiffness of sand mat and embankment was investigated by the analyzing the consolidation settlement at the center of the embankment and the lateral displacement at the toe of the embankment. And, the effect of the stiffness on the stress distribution characteristics was also investigated in this study. Furthermore, slope stability analysis was carried out to gain the safe factor by change the stiffness of the sandmat and the embankment. The objective of the study is supplying the result of the numerical experiments for the geotechnical engineers who use the FEM for the safety design of the soil structures. As a result, the stiffness of the superstructures greatly affects on the deformation characteristics both in consolidation settlement and lateral displacement. However, it can be aware that it is not dominants to the stress distribution in the aspect that the no changes in the residual excess pore water pressure. Therefore, the decision of the stiffness has to be carried out deliberately considering not only the consolidation the magnitude of the settlement and the lateral displacement, but the slope stability.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.380-381
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• 2012

Bioinspired sea urchin-like structures were fabricated on silicon by inductively coupled plasma (ICP) etching using lens-like shape hexagonally patterned photoresist (PR) patterns and subsequent metal-assisted chemical etching (MaCE) [1]. The lens-like shape PR patterns with a diameter of 2 ${\mu}m$ were formed by conventional lithography method followed by thermal reflow process of PR patterns on a hotplate at $170^{\circ}C$ for 40 s. ICP etching process was carried out in an SF6 plasma ambient using an optimum etching conditions such as radio-frequency power of 50 W, ICP power of 25 W, SF6 flow rate of 30 sccm, process pressure of 10 mTorr, and etching time of 150 s in order to produce micron structure with tapered etch profile. 15 nm thick Ag film was evaporated on the samples using e-beam evaporator with a deposition rate of 0.05 nm/s. To form Ag nanoparticles (NPs), the samples were thermally treated (thermally dewetted) in a rapid thermal annealing system at $500^{\circ}C$ for 1 min in a nitrogen environment. The Ag thickness and thermal dewetting conditions were carefully chosen to obtain isolated Ag NPs. To fabricate needle-like nanostructures on both the micron structure (i.e., sea urchin-like structures) and flat surface of silicon, MaCE process, which is based on the strong catalytic activity of metal, was performed in a chemical etchant (HNO3: HF: H2O = 4: 1: 20) using Ag NPs at room temperature for 1 min. Finally, the residual Ag NPs were removed by immersion in a HNO3 solution. The fabricated structures after each process steps are shown in figure 1. It is well-known that the hierarchical micro- and nanostructures have efficient light harvesting properties [2-3]. Therefore, this fabrication technique for production of sea urchin-like structures is applicable to improve the performance of light harvesting devices.

• Structural Engineering and Mechanics
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• 제30권6호
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• pp.713-732
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• 2008

Serviceability and durability of the concrete members can be seriously affected by the corrosion of steel rebar. Carbonation front and or chloride ingress can destroy the passive film on rebar and may set the corrosion (oxidation process). Depending on the level of oxidation (expansive corrosion products/rust) damage to the cover concrete takes place in the form of expansion, cracking and spalling or delamination. This makes the concrete unable to develop forces through bond and also become unprotected against further degradation from corrosion; and thus marks the end of service life for corrosion-affected structures. This paper presents an analytical model that predicts the weight loss of steel rebar and the corresponding time from onset of corrosion for the known corrosion rate and thus can be used for the determination of time to cover cracking in corrosion affected RC member. This model uses fully the thick-walled cylinder approach. The gradual crack propagation in radial directions (from inside) is considered when the circumferential tensile stresses at the inner surface of intact concrete have reached the tensile strength of concrete. The analysis is done separately with and without considering the stiffness of reinforcing steel and rust combine along with the assumption of zero residual strength of cracked concrete. The model accounts for the time required for corrosion products to fill a porous zone before they start inducing expansive pressure on the concrete surrounding the steel rebar. The capability of the model to produce the experimental trends is demonstrated by comparing the model's predictions with the results of experimental data published in the literature. The effect of considering the corroded reinforcing steel bar stiffness is demonstrated. A sensitivity analysis has also been carried out to show the influence of the various parameters. It has been found that material properties and their inter-relations significantly influence weight loss of rebar. Time to cover cracking from onset of corrosion for the same weight loss is influenced by corrosion rate and state of oxidation of corrosion product formed. Time to cover cracking from onset of corrosion is useful in making certain decisions pertaining to inspection, repair, rehabilitation, replacement and demolition of RC member/structure in corrosive environment.

• 상하수도학회지
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• 제18권5호
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• pp.598-607
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• 2004

In this study, the effects of two pre-treatment processes were observed prior to membrane filtration: pre-coagulation and pre-ozonation. To compare the effect of two above-mentioned pre-treatments, we adopted the four schemes: first one is direct membrane filtration of river surface water, second one is membrane filtration after pre-coagulation, third one is membrane filtration after pre-ozonation and fourth one is membrane filtration after pre-coagulation and pre-ozonation. There are two exceptional characteristics in applied processes. One is the usage of the MF membrane which has high ozone resisting characteristic. Therefore, ozone resides in membrane module during filtration. The other is adoption of Jet Mixed Separator (JMS) as coagulation-sedimentation process. The change in transmembrane pressure and permeate water quality were also examined. As a result, considering the filtration performance efficiency and permeate water quality, the process composed of filtration with combination of both pre-coagulation and pre-ozonation was proved most effective. The improved efficiency was due to the reduction of loading rate of fouling inducing materials to membrane module by coagulation process as well as variable reactions, such as degradation, particle destabilization and coagulation, occurred by residual ozone in membrane module. The additional effect of pre-coagulation before pre-ozonation is suppression of AOC, one of the by-products induced by ozonation. Therefore, combination of pre-coagulation and pre-ozonation is the effective process to overcome the major de-merit of ozonation i.e. by-products formation.

• 센서학회지
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• 제26권1호
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• pp.39-43
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• 2017

Development of vision system as a nondestructive evaluation system can be very useful in screening the defective mechanical parts before they are assembled into the final product. Since the tens of thousands of the mechanical parts are used in an automobile carefully inspecting the quality of the mechanical parts is very important to maximize the performance of the automobile. To sort out the defective mechanical parts before they are assembled, auto parts fabrication companies employ various inspection systems. Nondestructive evaluation systems are getting rapidly popular among various inspection systems. In this study, we have developed a vision system to inspect the inside of the brake caliper, a part that is used to compose a brake which is the most important to the safety of the drivers and the passengers. In a brake caliper, a piston is pushed against the brake disk by oil pressure, causing a friction to damp the rotation of the wheel. Inside the caliper, a groove is positioned to adopt an oil seal to prevent the oil leaks. Inspecting the groove with our vision system, we could examine the existence of the contaminants which are normally the residual tiny pieces from the machining process. We used a high resolution GigE camera, 360 degree lens to look in the inside view of the caliper at once, and a special illumination system in this vision system. We used the edge detection technique to successfully detect the contaminants which were in the form of small metal chips. Labview graphical program was used to process the digital data from the camera and to display the vision and the statistics of the contaminants. We were very successful in detecting the contaminants from the various size calipers. We think we are ready to employ this vision system to the caliper production factories.

• 한국가스학회지
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• 제22권3호
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• pp.45-52
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• 2018

국제해사기구(IMO)의 선박 배출가스 기준 강화로 인해 LNG 연료추진선박의 필요성이 대두되고 있으며 관련 분야에 대한 기술개발 및 실용화 촉진 연구가 활발하게 진행되고 있다. LNG 연료탱크는 운항 중 연료소비로 인하여 잔류량이 70% 미만이 될 경우 슬로싱을 고려하여야 하므로 재액화 장치를 탑재하기 어려운 중소형 LNG 연료추진선박은 Type C 형태의 압력 탱크가 적용될 가능성이 높다. 이러한 LNG 연료추진선박에 적용되는 LNG 탱크는 구조적 안전성과 더불어 LNG를 오래 보관하기 위한 단열성능이 매우 중요하다. 본 연구에서는 Type C LNG Tank에 대한 단열성능 평가 절차를 제안하였고, 실험을 통해 LNG 탱크의 열적 특성으로 인한 온도, 압력, BOG(Boil Off Gas)의 변화를 비교, 분석함으로서 BOR(Boil Off Rate) 테스트 절차에 대한 타당성과 유효성을 검증하였다.

• 한국진공학회지
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• 제13권1호
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• pp.39-45
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• 2004

UV-나노임프린팅 (Ultraviolet-Nanoimprinting Lithography:UV-NIL) 공정 기술은 수십 나노에서 수 나노미터 크기의 구조물을 적은 비용으로 대량생산 할 수 있다는 장점을 가지고 있는 기술로 최근 전세계적으로 연구가 활발히 진행되고 있다. 본 연구에서는 반도체 공정 중 마스크 제작 공정을 이용하여 나노패턴을 가진 5${\times}$5${\times}$0.09 인치 크기의 수정스탬프(quartz stamp)를 제작하였고, 임프린팅 (imprinting)시에 레지스트(resist)와 스탬프(stamp) 사이에서 발생하는 점착현상(adhesion)을 방지하고자 그 표면에 Fluoroalkanesilane(FAS) 표면처리를 하였다. 웨이퍼의 평탄도를 개선하고 친수(hydrophilic) 상태의 표면을 만들기 위해 그 표면에 평탄화층을 스핀코팅하였고, 1 nl의 분해능을 가진 디스펜서(dispenser)를 이용하여 레지스트 액적을 도포하였다. 스템프 상의 패턴과 레지스트에 임프린트된 패턴은 SEM, AFM 등을 이용하여 측정하였으며, EVG620-NIL 장비를 이용한 임프린팅 실험에서 370 nm - 1 um 크기의 다양한 패턴을 가진 스탬프의 패턴들이 정확하게 레지스트에 전사됨을 확인하였다.

• 한국결정성장학회지
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• 제8권1호
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• pp.83-90
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• 1998

Li, K과 Na-흑연 층간화합물의 stage 전이 특성을 탄소층사이에 존재하는 intercalants의 deintercalation 메카니즘을 고려하여 제시하였다. 온도와 압력을 조절하여 합성된 Li-GICs(graphite intercalation compounds)를 분위기하에서 자발적으로 분해시켰다. 이들 화합물을 XRD 분석한 결과 1, 2 stage의 d001-값이 각각 3.71, 7.06 $\AA$으로 나타났다. 분위기하에서 Li-GiCs를 deintercalation 반응을 시킨 6주 후에 잔유화합물이 형성됨을 알 수 있었다. 또한, two-bulb 법으로 K-GICs를 합성하였으며, K-GDICs(graphite deintercalation compounds)의 구조적 안정성과 stage 전이에 대하여 조사하였다. X-선회절 결과로부터 K-GDICs는 10주 동안 안정한 K-흑연 잔유 화합물을 형성하였다. 그리고 고온, 고압법을 이용하여 합성된 1, 2stage의 Na-GICs의 deintercalation 반응과 열적 안정성에 대한 온도 의존성에 대하여 논하였다. 열적 안정성과 관련하여 Na-GICs의 구조변화를 XRD에 의하여 확인하였다. 이들 과정에 따르면 stage 전이는 무질서한 stage를 가진 GDICs의 불규칙적인 deintercalation에 의하여 형성됨을 제시할 수 있었다.