• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.679-690
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• 2003

As the rate of increase in areal density of the HDD has accelerated, dynamic characteristics of the HDD actuator need to be improved with respect to the performance of the tracking servo and shock transmission. Therefore, it is important to analyze the vibration characteristic of the HDD actuator that consists of the VCM part, E-block and pivot bearing. In this paper, vibration modes of the HDD actuator are investigated the using finite element and experimental modal analyses methods. To develop a detailed finite element model, finite element models of each components of the actuator assembly are constructed and tuned to the results of the EMA. The VCM coil is modeled as an equivalent finite element model that has an orthotropic material property using auto-model updating program. Auto-model updating program with improved sensitivity based iterative method is applied to build a detailed finite element model using the result of the EMA. A detailed finite element model of the HDD actuator is then constructed and analyzed.

• 한국치위생학회지
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• 제16권5호
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• pp.695-700
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• 2016

Objectives: The purpose of the study was to investigate the effect of CAD/CAM ceramic thickness on shade. Methods: 24 disk-shaped ceramic specimens (E.Max CAD & Empress CAD, $12mm{\times}12mm$) were prepared and divided into 4 groups (n=6). Ceramic specimens in 2 thicknesses (0.8 mm, 1.0 mm) were made low translucency(LT) shade A2. All specimens were measured as L*, a*, b* using spectrophotometer. The color differences(${\Delta}E$ values) between the specimen and a control target block ($12{\times}12{\times}1.2mm$) were calculated. Two-way ANOVA performed between 2 groups(material and thickness). Results: As the thickness increased, the $L^*$ (for all groups) and $b^*$ value (for all groups) increased and the $a^*$ value(for LR group) decreased. The mean color differences caused by thickness was acceptible (${\Delta}E$ > 2) for group LD1. But the mean color differences by thickness were not selected (${\Delta}E$ < 2) for group LD2, LR1, LR2. Conclusions: The different thickness can influence the final color of CAD/CAM ceramic.

• Elastomers and Composites
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• 제20권1호
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• pp.13-24
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• 1985

It is generally agreed that strong linkages exist between rubber chains and reinforcing filler particles. The purpose of this study is to examine the effect of rubber-filler attachments on the various mechanical properties of the rubber. In particular, the modulus and strength will be altered by these attachments. For this study, the curing properties are examined by means of ODR (Oscillating Disk Rheometer), the physical properties by means of Instrong. The results of this study can be summarized as follows. In the ODR test, the carbon black filled stock has shorter scorch time than gum stock and, the silica and clay filled stock has longer scorch time than gum stock. In the modulus, ten sile and swelling properties, the vulcanizates filled with carbon black had higher those values than inorganic filler loaded NR vulcanizates, but the rebound rate showed that the silica filled NR vulcanizates was lower than other inorganic filler contained NR vulcanizates and the ISAF filled NR vulcanizates was lower than other carbon block contained NR vulcanizates.

• 약학회지
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• 제34권3호
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• pp.161-165
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• 1990

An automated, simple, and reliable method was developed for determining in vitro drug release rate from transdermal delivery dosage forms. The patch is held in position in the heating block by sandwiching it between the middle plate and the bottom plate of diffusion cell. The dissolution profile of the commercially available transdermal scopolamine patch was determined over a 72-h period, and the results were compared with those obtained with other methods; paddle-over-disk method, reciprocating method, and diffusion cell method. It was demonstrated that the flow-through method is equivalent in terms of release rate profile and accumulated released drug amount over the lifetime of the dosage form tested. Also this method is simple, reliable and reproducible. Therefore, this technique can be used in a quality control for assuring product uniformity.

• Restorative Dentistry and Endodontics
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• 제15권1호
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• pp.67-80
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• 1990

This study was performed for elucidating the effects on surface polishing of composite resins. In this study, Silux(microfilled), Graft(hybrid), Bisfil- I (hybrid posterior) and Hi-pol(conventional) were used. Sixty specimens were made with 4 brands of composite resins and Optilux system in $2.0{\times}1.3{\times}1.0cm$ resin block which has a cavity with 0.5cm diameter and 0.5cm depth. Polishing was done with #600 sand paper and Soflex, Super-snap, Micron finishing system, or Composite polishing kit. Final polished surfaces were measured by roughness tester(Kasaka Lab. Ltd., Japan) and image analyser(Omnimet Image Analyser, Buehler, USA). The results were as follows, 1. The celluloid strip produced the smoothest surfaces. 2. Light curing microfilled composite resin, Silux, had smoother surface than any others. 3. The surfaces polished by Soflex were smoothest. 4. Aluminum oxide disk, Soflex and Super-Snap, made smoother surface than diamond bur, M.F.S., or silicon point, Composite polishing kit. 5. The roughness values of surface polished by M.F.S. composed of diamond burs, were less than those of Composite polishing kit made from silicone points.

• 한국정보과학회논문지:정보통신
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• 제28권3호
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• pp.426-434
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• 2001

병렬 VOD 시스템에서 스트라이핑 정책은 비디오 데이터를 분할 하여 각 노드에 잘 정의된 순서로 분배함으로서 노드간에 부하 균등을 통한 시스템의 성능을 높일 수 있는 중요한 기법이다. 본 논문운 노드를 추가할 경우 노드간의 부하 균등을 고려한 데이터 스트라이핑 기법을 제시한다. 병렬 VOD 서버의 추가된 노드에 새 비디오 파일을 저장할 경우 그 노드에 부하가 집중되어 시스템의 성능이 떨어질수 있기 때문에 적절한 새 노드에 이동시켜 배치시키고 새 비디오 파일을 각 노드에 분배시키는 3 가지 스트라이핑 기법들을 제시한후 실험 분석을 통하여 이 기법들을 비교 평가하였다. 그 결과 FSM 양방향 기법이 가장 좋은 성능을 보였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2002년도 춘계학술발표논문집 (상)
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• pp.365-368
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• 2002

본 논문에서는 SANtopiaVM의 데이터 가용성 및 성능을 고려한 에러 핸들링 정책을 제안한다. 제안하는 에러 핸들링 정책은 RAID1과 RAID5에 대한 정책으로 추분하며 에러 발생시의 복구를 위하여 RAID1에서는 FBB(Failed Block Bitmap)라는 비트맵을 추가하여 데이터의 일관성을 유지하고 디스크의 복구 시에는 저기 연산에 대한 부하 분산 및 복구 비용을 감소시키는 쓰기 연산을 제안함으로서 에러 핸들링 시에 입출력 비용을 줄인다. RAID5에서는 추가적인 여분 디스크를 사용한 Sparing Disk 기법을 제안함으로서 디스크 에러 모드에서도 정상 모드의 성능에 근접하는 입출력 성능을 보장하며 빠른 디스크 복구를 지원한다. 제안하는 에러 핸들링 정책은 SANtopiaVM RAID의 오류 발생시, 시스템 성능의 급격한 저하를 완화할 수 있으며 에러로부터 빠른 복구를 지원함으로서 데이터에 대한 효율적인 고 가용성의 특징을 제공한다.

• 반도체디스플레이기술학회지
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• 제10권1호
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• pp.1-6
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• 2011

In this paper, the air flow induced by the rotating flat disk is numerically investigated in a hope to better understand the air flow structures inside the wax spin coater for a silicon wafer polishing station. Due to the complex inner geometry of actual spin coater such as the casing around the rotating ceramic block and servo motor, recirculation of air flow is inevitably found on the coating target if the internal space of spin coater is closed at the bottom and it could be the possible source of contamination on the wax coating. By numerical flow simulation, we found that it is necessary to install the air vent at the bottom and to apply the sufficient air suction in order to control the path of air flow and to eliminate the air recirculation zone above the spinning surface of coating target.

• 정보처리학회논문지A
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• 제9A권3호
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• pp.287-294
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• 2002

본 논문에서는 동적 비트맵 할당 기법을 사용하는 새로운 파일 시스템 기법에 대하여 제안한다. 기존의 파일 시스템들이 슈퍼블록, 아이노드, 디렉토리 엔트리와 같은 메타데이터를 위해 고정된 비트맵 구조의 의존하는 반면, 제안된 기법은 파일 시스템의 특성에 따라 비트맵과 할당 영역을 할당한다. 제안된 기법은 기존의 파일 시스템에서 디스크의 이용율이 파일의 크기에 의존하는 문제를 해결하였다. 성능평가를 통해서 동적 비트맵을 이용한 제안된 파일 시스템이 기존의 기법에 비해 효율적으로 디스크를 사용함을 보였다.

• 대한원격탐사학회지
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• 제5권1호
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• pp.41-56
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• 1989

Improvement of the multichannel sea surface temperature(MCSST) software, which had been developed for the purpose of operating under mainframe computer system, was seeked in order to operate effectively in a mini computer system. CPU time and processing time, which is not a major factor under mainframe computer system, become a critical factor in real time image processing under mini computer system. Due to fixed kernel size(3$\times$4) of the old MCSST software, high spatial resolution characteristics of the original image received from satellites were apparently degraded when images are transformed into a cartesian coordinate system after geometrical distortions of the image due to earth curvature are removed. CPU and processing time were reduced to 0.13 and 0.15~0.22 comparing with the old MCSST's, respectively, by applying disk block I/O and M/T queue I/O method under VAX-11/750 computer. The high resolution quality (1.1km in AVHRR) of the processed image was guaranted using 2$\times$2 kernel size and applying moving window techniques without sacrificing CPU and processing time much.