• Korean Journal of Optics and Photonics
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• v.11 no.2
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• pp.73-79
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• 2000

We measure a beam diameter of scan and sub-scan direction of LSD (Laser Scanning Urnt) which uses $fheta$ lens produced by injecLion molding method as a scanning lens. While the measured beam diameter in scan direction, which is $62muextrm{m}$ to $68\mu\textrm{m}$, shows similar size comparing to the design beam diameter, the sub-scan beam diameter shows sIzable beam diameter deviation as much as 37 11m ranging from $78\mu\textrm{m}$ to $115\mu\textrm{m}$. Injection molding lens has the surface figure error due to the shrinkage III the cooling time and the internal distortion (birefringence) due to the uneven cooling conditIOn so that these bring about wavefront aberration (i.e., the enlargement of beam size), and are eventually expre~sed as the deterioration of the pdnting image. In this paper. we first measure and analyze beam diameter, birefringence (polanzation ratio), and asphedcal figure error of mIens in order to know the principle cause of the beam diameter deviation in sub-scan directIOn. And Lhen. through the analysis of a designed depth of focus and a calculated field curvature (imaging position of the optical axis directIon) using the above figure elTor data, we know Lhat the birefringence IS the main factor of sizable beam diameter deVIation in sub-scan direction. ction.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.168-177
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• 2001

Reverse engineering has been widely used for the shape reconstruction of an object without CAD data and the measurement of clay or wood models fur the development of new products. To generate a surface from measured points by a laser scanner, typical steps include the scanning of a clay or wood model, the generation of compatible input curves, the generation of a surface and manufacturing data like G code or STL file. A laser scanner has a great potential to get geometrical data of a model for its frost measuring speed and higher precision. The data from a laser scanner are composed of many line stripes of points including small spikes and noise. A new approach using automated surface generating algorithm is introduced to deal with problems during reverse engineering process. And the input data and the generated surface are represented in IGES format, thus can be supplied to other CAD/CAM software without any data manipulation.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.7
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• pp.70-82
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• 1993

In this paper, employing the 3-dimensional discrete cosine transform (DCT) for the utilization of the temporal correlation, an adaptive motion sequence coding technique is proposed. The energy distribution in a 3-D DCT block, due to the nonstationary nature of the image data, varies along the veritical, horizontal and temporal directions. Thus, aiming an adaptive system to local variations, adaptive procedures, such as the 3-D classification, the classified linear scanning technique and the VLC table selection scheme, have been implemented in our approach. Also, a hybrid structure which adaptively combines inter-frame coding is presented, and it is found that the adaptive hybrid frame coding technique shows a significant performance gain for a moving sequence which contains a relatively small moving area. Through an intensive computer simulation, it is demonstrated that, the performance of the proposed 3-D transform coding technique shows a close relation with the temporal variation of the sequence to be code. And the proposed technique has the advantages of skipping the computationally complex motion compensation procedure and improving the performance over the 2-D motion compensated transform coding technique for rates in the range of 0.5 ~ 1.0 bpp.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.1
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• pp.7-11
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• 2006

Through SCM modeling, we found that the depletion layer in silicon was of a form of a spherical capacitor with the SCM tip biased. Two-dimensional (2D) finite differential method code with a successive over relaxation (SOR) solver has been developed to model the measurements by SCM of a semiconductor wafer that contains an ion-implanted impurity region. Then, we theoretically analyzed the spherical capacitor and determined the total depleted-volume charge Q, capacitance C, and the rate of capacitance change with bias dC/dV. It is very important to observe the depleted carriers' movement in the silicon layer by applying the bias to the tip. So, we calculated the depleted-volume charge, considering different factors such as tip size, oxide thickness, and applied bias (dc+ac), which have an influence on potential and depletion charges.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.215-221
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• 2023

Proton treatment may deliver a larger dose to a patient's skin than traditional photon therapy, especially when a range shifter (RS) is inserted in the beam path. This study investigated the effects of an RS on skin dose while considering RS with different thicknesses, airgaps and materials. First, the physical model of the scanning nozzle with RS was established in the TOol for PArticle Simulation (TOPAS) code, and the effects of the RS on the skin dose were studied. Second, the variations in the skin dose and isocenter beam size were examined by reducing the air gap. Finally, the effects of different RS materials, such as polymethylmethacrylate (PMMA), Lexan, polyethylene and polystyrene, on the skin dose were analysed. The results demonstrated that the current RS design had a negligible effect on the skin dose, whereas the RS significantly impacted the isocenter beam size. The skin dose was increased considerably when the RS was placed close to the phantom. Moreover, the magnitude of the increase was related to the thickness of the inserted RS. Meanwhile, the results also revealed that the secondary proton primarily contributed to the increased skin dose.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.216-217
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• 2024

최근 클라우드 컴퓨팅 인프라 및 소프트웨어의 지속적인 발전으로 인한 복잡성 증가로 인해 신속한 확장성과 유연성에 대한 요구가 증가하고 있다. 이에 클라우드 네이티브 환경과의 호환성뿐만 아니라 개발과 운영의 효율성을 높이고자 코드로 인프라를 정의하여 자동화된 환경을 구축해 주는 코드형 인프라(Infrastructure as Code, IaC) 기술이 주목받고 있으며, AWS CloudFormation 은 대표적인 솔루션 중 하나이다. 그러나 IaC 형태로 배포되는 템플릿에 취약성이 존재할 경우, 인스턴스가 실행되기 전까지 보안 취약점을 미리 발견하기 어려워 DevOps 사이클에서의 보안 이슈를 야기할 수 있다. 이에 본 논문은 CloudFormation 템플릿의 보안 취약성 스캔이 가능하다고 알려진 오픈 소스 도구의 효율성을 평가하기 위한 사례 연구를 수행한다. 분석 결과를 바탕으로, DevSecOps 달성을 위한 IaC 기반 환경에서 취약성 사전 탐지의 필요성과 세분화된 접근 방식을 제시하고자 한다.

• Journal of the Korea Concrete Institute
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• v.29 no.3
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• pp.275-281
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• 2017

This study examined the effect of water-to-binder ratio (W/B) and phosphate-to-binder ratio (P/B) on the flow, setting time, compressive strength development, and pH variation of magnesium-potassium phosphate composites, MKPC mortars. Ten mortars mixtures were prepared with the W/B varying from 20% to 40% at each P/B of 0.3 or 0.5. The hydration products and microstructural pore distribution of the MKPC pastes were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP). The initial flow and setting time of MKPC mortars tended to decrease with an increase of P/B, indicating that the final setting time was shortened by approximately 24% when P/B increased from 0.3 to 0.5. The slope of the early-strength development measured in the MKPC mortars was considerably higher than that of cement concrete specified in code provisions. For obtaining a relatively good 28-day strength (above 30 MPa) and a near neutral pH (below 9.0) in MKPC mortars, the P/B and W/B need to be selected as 0.5 and 30%, respectively. The strubite-K crystal increased with the increases of P/B and W/B, which leads to the decrease of the macro-capillary pores.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.116-124
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• 2015

The objective of this study is to evaluate the effects of the replacement levels of grinded fly-ash on the repaired mortar based on a polymer. The main parameters are the curing temperature and replacement levels of grinded fly-ash. The curing temperature and the replacement levels of grinded fly-ash are varied at $40^{\circ}C$, $20^{\circ}C$ and $5^{\circ}C$, and between 0% and 35% of the total binder by weight, respectively. The flow in fresh mortar and compressive strengths according to ages, the relationship of stress-strain, elastic modulus and modulus rupture in hardened mortar, as well as scanning the electron microscopy and the X-ray diffraction of mortar, were measured, respectively. The test results showed that the flow, elastic modulus and modulus rupture are great in mortar specimens with 20~30% of the replacement levels of grinded fly-ash. In addition, compressive strengths according to ages were affected by the replacement levels of grinded fly-ash and the curing temperature indicated that the strength development ratio of mortar with 20% of the replacement levels of grinded fly-ash was greater than others. In the prediction of the compressive strength specified by the ACI 209 code, the strength development at an early and late age can be generalized by the functions of the replacement levels of grinded fly-ash and the curing temperature. In the analysis of scanning the electron microscopy and the X-ray diffraction, the number and intensity of peaks increased and the form of CSH gels on the surface of the particle of grinded fly-ash was observed.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.2
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• pp.41-51
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• 2004

Recycled plastic containers, so-called 'Tarai' in Korea which are often used as food containers, were collected from 23 domestic manufacturers. Then, their components were analyzed to find out whether they are safe for the use of food-contact material, to meet the standards and specifications of Korean hygienic regulations, the 'Food Code.' The components of the material were analyzed by using Fourier Transform-Infrared (FT-IR), Differential Scanning Calorimeter (DSC), and Elementary Analyzer (EA). The analysis of the FT-IR and the DSC showed that the main component of the samples was polyethylene. Furthermore, the analysis of the EA for 'Tarai' sample revealed the same ratio of C and H elements as in the case of polyethylene which was 1 to 2. Phenol and formaldehyde were not detected in all the samples. As for the antioxidant tests, Irganox 1010, Irganox 1076 and Irganox 1330 were detected in various samples. With regard to the material test for heavy metals, 7 out of 23 samples exceeded the limit value of 100 mg/kg in lead contents. No standard and specification is yet prescribed in the 'Food Code' for the material of 'Tarai' as plastic containers for food. This study suggests that the use of 'Tarai' as a food container should be strictly controlled.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.3
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• pp.265-273
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• 2019

This study was performed to evaluate clinical use of laser fluorescence (LF) to identify early childhood caries lesions suitable for applying resin infiltration. 20 exfoliated primary molars with proximal caries were selected and cut buccolingually cross the central pit for regarding the mesial and distal surfaces respectively. 27 specimens corresponding to ICDAS code 1 and 2 were selected and the LF values were measured. When infiltrant resin was applied, double staining for microscopy detection has done simultaneously. Tooth samples were sliced with 0.7 mm thick. The maximum lesion depth, maximum penetration depth, and average penetration rate were measured from the confocal scanning laser microscope image. Pearson correlation analysis was performed. The intraclass correlation coefficient of LF values shows excellent agreement. LF values had positive correlation with penetration rate, but not lesion depth and penetration depth. Significant correlation between LF readings and penetration rate was verified in deep enamel caries and dentin caries except shallow enamel caries. Infiltrant resin could penetrate with a higher rate and LF values could be increased in more active caries lesions. In assessing radiologically similar caries lesion, laser fluorescence might be useful for identifying caries activity.