• Structural Engineering and Mechanics
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• 제78권3호
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• pp.333-350
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• 2021

Motivated by the demand of seismic protection of museum collections and development of performance-based seismic design guidelines, this paper investigates the seismic fragility of sliding artifacts based on incremental dynamic analysis and three-dimensional finite element model of the artifact-showcase-museum system considering nonlinear behavior of the structure and contact interfaces. Different intensity measures (IMs) for seismic fragility assessment of sliding artifacts are compared. The fragility curves of the sliding artifacts in both freestanding and restrained showcases placed on different floors of a four-story reinforced concrete frame structure are developed. The seismic sliding fragility of the artifacts within a real-world museum subjected to bi-directional horizontal ground motions is also assessed using the proposed IM and engineering demand parameter. Results show that the peak floor acceleration including only values initiating sliding is an efficient IM. Moreover, the sliding fragility estimate for the artifact in the restrained showcase increases as the floor level goes higher, while it may not be true in the freestanding showcase. Furthermore, the artifact is more prone to sliding failure in the restrained showcase than the freestanding showcase. In addition, the artifact has slightly worse sliding performance subjected to bi-directional motions than major-component motions.

• 보존과학회지
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• 제31권2호
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• pp.147-157
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• 2015

최근 중요유물의 가치를 제고하고 일반인의 이해를 돕기 위한 방법으로 복제품을 전시하는 경우가 많아지고 있다. 우리나라에서 유물복제는 외형에만 치중한 복원 복제 방법으로 많이 이루어지고 있다. 복제품, 유물복원이 증대하고 있는 상황에서 유물에 손상을 최소화하고 조형물처럼 커다란 유물에도 적용 가능한 복원기술의 연구가 필요하다. 월정교 출토 사자상 복원을 위한 모본 제작은 미술사적 조사를 바탕으로 3차원 스캔을 활용한 실측도와 단면도를 만들었고 이를 기초로 비접촉식 복제방법을 선택하였다. 비접촉식 방법의 장점은 정밀한 결과물도 얻을 수 있는 것이다. 일반적으로 비접촉식 방법일 경우 소형 유물에만 적용 가능하고 추가적인 재처리 등의 문제점이 있는 것으로 알려져 있으나 금번 연구대상인 사자상 같은 조형물에도 정밀하게 적용 가능함을 발견할 수 있었다. 따라서 이 연구는 월정교 출토 사자상의 학술적 가치를 제고하는 한편 사자상의 형태를 이용한 복원을 통해 복원된 월정교의 역사적 진정성을 보완하는 의미가 있으며, 유사 유물의 복제와 복원에 관하여 연구 자료로 활용될 수 있을 것이다.

• 열처리공학회지
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• 제17권1호
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• pp.2-9
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• 2004

This study has examined the metallurgical microstructures and alloy compositions of 3 bronze artifacts, a vessel, a spoon and a chopstick, manufactured in the Koryo Dynasty. The results show that they were made from Cu-Sn alloys whose Sn content ranges from 22 to 24% by weight. It is of significant importance to find that they were all given special thermo-mechanical treatments during their manufacturing. It has been found that the Koryo bronze workers were well aware of the mechanical properties of ${\alpha}$, ${\beta}$, ${\gamma}$ and ${\delta}$ phases that appear in the Cu-Sn alloys. Knowing how to promote or suppress the formation of each phase, they were able to find proper alloy compositions and temperatures for the high Sn alloys to be successfully forged. The present study will detail the Koryo bronze technology as estimated from the microstructures of the 3 bronze artifacts. The results of the reproduction experiments with Cu-24%Sn will also be presented to explain how the microstructures develop and to estimate the mechanical properties of each phase.

• Journal of Magnetics
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• 제18권4호
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• pp.422-427
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• 2013

The aim of this study was to investigate effects of the number of acquisitions (NEX) on signal-to-noise (SNR) and artifacts in SENSE parallel imaging of magnetic resonance imaging (MRI). 3.0T MR System, 8 Channel sensitivity encoding (SENSE) head coils were used along with an in-vivo phantom. Reference sequence of 3D fast field echo (FFE) was consisted of NEX values of 2, 4, 6, 8, 10 and 12. The T2 turbo spin echo (TSE) sequence used for exams achieved SENSE factors of 1.2, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0, 3.2, 3.5, 3.8 and 4.0. Exams were conducted five times for each SENSE factor to measure signal intensity of the object, the posterior phase-encode direction and frequency direction. And SNR was calculated using mean values. SENSE artifacts were identified as background signal intensity in the phase-encoded direction using MRIcro. It was found that SNR increased but SENSE artifacts reduced with NEX of 4, 8 and 12 when the NEX increased in reference scan. It is therefore concluded that image quality can be improved with NEX of 4, 8 and 12 for reference scanning.

• 보존과학연구
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• 통권13호
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• pp.37-58
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• 1992

Iron artifacts from Busǒ Sansǒng inffered to late Baikjae periodwere studied on the aspects of metallugy. These materials were the largest size ever since excavated. From the analytical results these artifacts were found to be pureiron system without impurities or hypo-eutectoid steel system in below 0.3% in carbon contents. From the content of phosphorus in the range of 0.03∼0.05% as aim purity it was shown that charcoal were used for making these iron artifacts from sponge iron not fusion method. By observing metallugical structure it was found that iron artifacts was manufactured by repetitive folding and hammering forging method and some by heating method for adding carbon with cool water. This method were to improve the quality of the soften steel to harden one. In addition to those above repetitive hammering method eliminated the nonferrous materials such as slag inclusion and remained relatively pure ferrite.

• 인터넷정보학회논문지
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• 제22권3호
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• pp.59-66
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• 2021

이 연구에서는 소프트웨어 개발 과정에서 소프트웨어 시스템의 품질을 높이기 위해 요구사항에 대한 추적성 관리 및 변경 관리를 체계적으로 수행하는 요구사항 모니터링 방법을 제안한다. 이를 위해 산출물 간 연관 관계를 정의하기 위한 추적 매트릭스와 개별산출물들에 대한 변경 관리를 체계적으로 수행하기 위한 산출물 변경 이력 관리 모델을 제시한다. 또한 특정 산출물이 변경될 때 연관된 산출물에 변경이 파급되는 상황을 쉽게 파악할 수 있도록 하는 시각적 대시보드도 제안한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.351-354
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• 2002

DVR(Digital Video Recorder), a recently popular visual monitoring system, is required to support multi camera channel display(upto 16 channels) with various display modes in real-time. For such a multichannel display system, it is well known that tearing artifacts become more serious. Thus, one needs to design a display system for DVR so that it does not show tearing artifacts as much as possible, but keeps real-time display speed. In this paper, we present our efforts in designing and implementing a display system which rarely ever shows tearing artifacts, but without degradation of required real-time display speed, and which displays character information stably without blinking.

• 보존과학회지
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• 제37권1호
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• pp.25-33
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• 2021

To extend the application of digital technology to the replication of artifacts, meticulous details of the process and the diversity of three-dimensional (3D) printing output materials need to be supplemented. Thus, in this study, a bronze mirror with Hwangbichangcheon inscription was digitalized by 3D scanning, converted into a voxel model, and virtual conservation treatment was performed using a haptic device. Furthermore, the digital mold of the bronze mirror completed by Boolean modeling was printed using a 3D sand-printer. Such contactless replication based on digital technology reflects the stability, precision, expressivity, collectivity, durability, and economic feasibility of artifacts. Its application can be further extended to cultural products as well as such areas as education, exhibition, and research. It is expected to be in high demand for metal artifacts that require casting. If empirical studies through experimental research on casting are supplemented in the future, it could extend the application of digital technology-based contactless replication methods.

• 한국멀티미디어학회논문지
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• 제25권1호
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• pp.29-38
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• 2022

Although image compression is one of the essential technologies to transmit image data on a variety of surveillance and mobile healthcare applications, it causes unnecessary compression artifacts such as blocking and ringing artifacts by the lossy compression in the limited network bandwidth. Recently, image restoration methods using convolutional neural network (CNN) show the significant improvement of image quality from the compressed images. In this paper, we propose Image Denoising Convolutional Neural Networks (IDCNN) to reduce the compression artifacts for the purpose of improving the performance of object classification. In order to evaluate the classification accuracy, we used the ImageNet test dataset consisting of 50,000 natural images and measured the classification performance in terms of Top-1 and Top-5 accuracy. Experimental results show that the proposed IDCNN can improve Top-1 and Top-5 accuracy as high as 2.46% and 2.42%, respectively.

• 보존과학회지
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• 제29권4호
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• pp.297-309
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• 2013

철제유물은 출토되는 순간 급격한 환경변화로 인해 빠른 속도로 부식이 진행되므로 보존처리 과정을 거쳐 부식을 억제한다. 그러나 보존처리가 완료된 철제유물도 재부식이 발생하는 경우가 다수이며, 재부식된 유물의 보존처리는 1차 보존처리 시보다 그 처리가 어렵고 처리기간 또한 길어진다. 본 연구는 보존처리가 완료된 이후 보관과정에서 발생하는 부식생성물을 과학적으로 분석하여 재부식의 요인을 찾고자 하였다. 경주지역의 세 유적에서 출토된 철제유물을 동일한 약품과 방법으로 2002~2009년 동안 보존처리를 완료하였으나, 포장 보관 상태의 일부 철제유물에서 재부식 징후가 관찰되었다. 이중 재부식의 징후가 확인된 단조 철제유물 9점을 선별하여 질량측정, 육안관찰, 현미경을 통한 물리적 변화를 관찰하였고, SEM-EDS, XRD, IC, ICP분석을 통해 화학적 변화를 분석하였다. 그 결과, 유물에서 탈락된 부분의 접면에 형성된 황갈색 부식생성물은 군집한 형상만 다를 뿐 결정상은 공통적으로 침상형이 확인되었으며, 적색에서 황갈색으로 갈수록 침상의 형태가 뚜렷하였다. 보존처리가 완료된 시점의 경과에 따라 부식생성물이 증가할수록 유물의 질량이 증가하였고 염화이온의 농도가 상대적으로 높아지는 경향이 나타났다. 채집된 모든 시료의 부식생성물에 대한 XRD분석에서는 ${\beta}$-FeOOH(akaganeite)이 확인되었고, ICP분석 결과 $Na^+$, $Ca^{2+}$성분을 확인할 수 있었다.